NASA_STD_8739_1_A WORKMANSHIP STANDARD FOR POLYMERIC
NASA STD7009 建模与仿真标准★
NASA-STD-7009NASA TECHNICALSTANDARDApproved: 07-11-2008 National Aeronautics and Space AdministrationWashington, DC 20546-0001Expiration Date: 07-10-2013Superseding NASA-STD-(I)-7009 STANDARD FOR MODELS AND SIMULATIONSMEASUREMENT SYSTEM IDENTIFICATION:NOT MEASUREMENT SENSITIVEDOCUMENT HISTORY LOGApproval Date Description Status DocumentRevisionInterim 12-01-2006 Interim Baseline ReleaseRelease Baseline 07-11-2008 BaselineFOREWORDThis standard is published by the National Aeronautics and Space Administration (NASA) to provide uniform engineering and technical requirements for processes, procedures, practices, and methods that have been endorsed as standard for models and simulations (M&S) developed and used in NASA programs and projects, including requirements for selection, application, and design criteria of an item. This standard was specifically developed to respond to Action 4 from the 2004 report “A Renewed Commitment to Excellence,” with consideration also given to related findings as identified in the Columbia Accident Investigation Board (CAIB) Report.This standard is approved for use by NASA Headquarters and NASA Centers, including Component Facilities.This standard covers the development and operation (or execution) of M&S, as well as the analysis and presentation of the results from M&S. This also includes the proper training ofM&S practitioners and the identification of recommended practices, while ensuring thecredibility of the results from M&S is assessed and properly conveyed to those making critical decisions.Requests for information, corrections, or additions to this standard should be submitted via “Feedback” in the NASA Technical Standards System at .Original Signed By July 11, 2008Michael G. Ryschkewitsch Approval DateNASA Chief EngineerSECTION TABLE OF CONTENTSPAGEDOCUMENT HISTORY LOG (2)FOREWORD (3)TABLE OF CONTENTS (4)LIST OF FIGURES (6)LIST OF TABLES (6)1. SCOPE (7)1.1 Purpose (7)1.2 Applicability (8)1.3 Focus (9)2. APPLICABLEDOCUMENTS (9)2.1 General (9)2.2 GovernmentDocuments (9)2.3 Non-GovernmentDocuments (9)2.4 Order of Precedence (9)3. ACRONYMSANDDEFINITIONS (10)3.1 Acronyms and Abbreviations (10)3.2 Definitions (10)4. REQUIREMENTS (14)4.1 Programmatics (15)4.2 Models (16)4.3 Simulations and Analyses (18)4.4 Verification, Validation, and Uncertainty Quantification (19)4.5 Identification and Use of Recommended Practices (21)4.6 Training (22)4.7 Assessing the Credibility of M&S Results (23)4.8 Reporting Results to Decision Makers (24)5.GUIDANCE (26)5.1 ReferenceDocuments (26)5.2 KeyWordListing (28)TABLE OF CONTENTS, continuedSECTION PAGE Appendix A M&S Risk Assessment (29)Appendix B Credibility Assessment Scale (31)Appendix C Compliance Matrix (51)LIST OF FIGURESFigure Title Page 1 Sample M&S Risk Assessment Matrix (30)Scale (31)2 CredibilityAssessmentWeights (45)3 Subfactor4 Bar Chart and Radar Plot for Factor Scores (47)Illustration (49)Flag5 DeficiencyFlagIllustration (50)6 Exceedance7 Sufficiency Thresholds and Color Coding on Bar Chart and RadarPlot for Factor Scores (50)LIST OF TABLESTable Title Page1 Key Aspects of Credibility Assessment Levels (33)2 Level Definitions for Evidence Subfactors in the M&SDevelopment Category (37)3 Level Definitions for Evidence Subfactors in the M&S OperationsCategory (40)4 Level Definitions for Factors in the Supporting Evidence Category.. 425 Level Definitions for the Technical Review Subfactors (44)6 Roll-up of Subfactor Scores to Factor Score (46)7 Roll-up of Factor Scores to Overall Score (47)8 Roll-up of Factor Scores to Category Score (48)STANDARD FOR MODELS AND SIMULATIONS1. SCOPE1.1 PurposeThis standard was developed in response to Action 4 from the 2004 report “A Renewed Commitment to Excellence,” which stated the following:“Develop a standard for the development, documentation, and operation of models and simulationsa.Identify best practices to ensure that knowledge of operations is captured in the userinterfaces (e.g., users are not able to enter parameters that are out of bounds),b.Develop process for tool verification and validation, certification, reverification,revalidation, and recertification based on operational data and trending,c.Develop standard for documentation, configuration management, and qualityassurance,d.Identify any training or certification requirements to ensure proper operationalcapabilities,e.Provide a plan for tool management, maintenance, and obsolescence consistent withmodeling/simulation environments and the aging or changing of the modeledplatform or system,f.Develop a process for user feedback when results appear unrealistic or defyexplanation.”Subsequently, in 2006, the NASA Chief Engineer provided the following further guidance:g.“Include a standard method to assess the credibility of the models and simulationspresented to the decision maker when making critical decisions (i.e., decisions thateffect human safety or mission success) using results from models and simulations,h.Assure that the credibility of models and simulations meet the project requirements.” Each of the requirements and recommendations in this standard can be traced to one or more of the eight objectives listed above. The traceability matrix of the requirements in this standard to the eight objectives can be found online upon accessing this standard at URL; refer to “Requirements Traceability Matrix.” Some of these objectives are met by recommendations rather than by requirements as a result of either (a) the practical impossibility of satisfying the requirement in all cases, or (b) further guidance received from NASA Headquarters.These eight objectives are encapsulated in the overall goal for this standard, which is to ensure that the credibility of the results from M&S is properly conveyed to those making critical decisions. Critical decisions based on M&S results, as defined by this standard, are those technical decisions related to design, development, manufacturing, ground, or flight operations that may impact human safety or program/project-defined mission success criteria. The intent is to reduce the risks associated with critical decisions. This standard covers the development and operation (or execution) of M&S as well as the processes of analysis and presentation of the results from the M&S.This standard addresses aspects of M&S that are common across NASA activities. Discipline-specific details of M&S should be addressed in future documents, such as Recommended Practices (usually entitled “Handbooks” in the NASA document hierarchy), and are not included in this standard.The scope of this standard covers the development and maintenance of models, the operation of simulations, the analysis of the results, training, recommended practices, the assessment of the M&S credibility, and the reporting of the M&S results. Some of the key features of this standard are requirements and recommendations for verification, validation, uncertainty quantification, training, credibility assessment, and reporting to decision makers; also included are the cross-cutting areas of documentation and configuration management (CM).The requirements/recommendations in sections 4.7 and 4.8 are the culmination of the standard. The requirements/recommendations in sections 4.1 – 4.6 are intended to support the requirements in sections 4.7 and 4.8. This is accomplished by ensuring that sufficient details of the M&S process along with intermediate results are available to support the requirements in sections 4.7 and 4.8 and to respond to in-depth queries by the decision maker. Appendix A provides guidance for assessing the risk of using M&S in engineering decisions. Appendix B provides details related to some of the requirements/recommendations in sections 4.7 and 4.8. Appendix C contains a template for a compliance matrix.1.2ApplicabilityThis standard applies to M&S used by NASA and its contractors for critical decisions in design, development, manufacturing, ground operations, and flight operations. (Guidance for determining which particular M&S are in scope is provided in section 4.1 and Appendix A.) This standard also applies to use of legacy as well as commercial-off-the-shelf (COTS), government-off-the-shelf (GOTS), and modified-off-the-shelf (MOTS) M&S to support critical decisions. Generally, for such M&S, particular attention may need to be paid to defining the limits of operation and to verification, validation, and uncertainty quantification. Programs and projects are encouraged to apply this standard to M&S, if the M&S results may impact future critical decisions.This standard does not apply to M&S that are embedded in control software, emulation software, and stimulation environments. However, Center implementation plans for NPR 7150.2, NASA Software Engineering Requirements, should specifically cover embedded M&S, and addresssuch M&S-specific issues as numerical accuracy, uncertainty analysis, sensitivity analysis, M&S verification, and M&S validation.This standard may be cited in contract, program, and other Agency documents as a technical requirement. Requirements are indicated by the word “shall”; explanatory or guidance text is indicated in italics.1.2.1Tailoring for application to a specific program or project shall be formally documented as part of program or project requirements and approved by the Technical Authority.1.3 FocusIn general, standards may focus on engineering/technical requirements, processes, procedures, practices, or methods. This standard focuses on requirements and recommendations. Hence, this standard specifies what shall or should be done; it does not prescribe how the requirements are to be met, nor does it specify who is the responsible party for complying with the requirements.DOCUMENTS2. APPLICABLE2.1 GeneralThe documents listed in this section contain provisions that constitute requirements of this standard as cited in the text of section 4.2.1.1The latest issuances of cited documents shall be used unless otherwise approved by the assigned Technical Authority.The applicable documents are accessible via the NASA Online Directives Information System at and the NASA Technical Standards System at, or may be obtained directly from the Standards Developing Organizations or other document distributors.2.2Government DocumentsNone.2.3Non-Government DocumentsNone.2.4 Order of PrecedenceThis document establishes requirements and guidance for models and simulations but does not supersede nor waive established Agency requirements found in other documentation.2.4.1Conflicts between this standard and other requirements documents shall be resolved by the responsible Technical Authority.3. ACRONYMS AND DEFINITIONS3.1Acronyms and AbbreviationsAIAA American Institute of Aeronautics and AstronauticsASME American Society of Mechanical EngineersCAIB Columbia Accident Investigation BoardScaleCAS CredibilityAssessmentManagementCM ConfigurationCOTS Commercial-Off-The-ShelfCPIAC Chemical Propulsion Information Analysis CenterDMSO Defense Modeling and Simulation OfficeGOTS Government-Off-The-ShelfIEEE Institute of Electrical and Electronics EngineersISG Implementation Study GroupOrganization for StandardizationISO InternationalJANNAF Joint Army-Navy-NASA-Air ForceSimulationsandM&S ModelsMOTS Modified-Off-The-ShelfNASA National Aeronautics and Space AdministrationNASTRAN NASA Structural AnalysisNPR NASA Procedural RequirementsPMBA Primary Mirror Backplane AssemblyReq. RequirementGuideRPG RecommendedPracticesInteroperability Standards OrganizationSISO SimulationSTD StandardValidationV&V Verification&Validation, and AccreditationVV&A Verification,3.2 DefinitionsThe definitions listed below are those used in this document. Wherever possible, these definitions have been taken from official NASA documents. In some cases, after reviewing definitions of interest in the International Organization for Standardization (ISO), the Defense Modeling and Simulation Office (DMSO), professional society publications, and English language dictionaries, some of these definitions were taken or adapted from these sources to achieve the goal and objectives stated in section 1.1. Some definitions may have alternate meanings in other documents and disciplines.Abstraction: The process of selecting the essential aspects of a reference system to be represented in a model or simulation while ignoring those aspects that are not relevant to the purpose of the model or simulation (adapted from Fidelity ISG Glossary, Vol. 3.0).Accuracy: The difference between a parameter or variable (or a set of parameters or variables) within a model, simulation, or experiment and the true value or the assumed true value.Analysis: Any post-processing or interpretation of the individual values, arrays, files of data, or suites of executions resulting from a simulation.Artifact: Any tangible product that is produced by the project team, i.e., requirements documents, help systems, code, executables, test documentation, test results, diagrams, etc.Calibration: The process of adjusting numerical or modeling parameters in the model to improve agreement with a referent.Model: The numerical representation of the mathematical model.ComputationalConceptualModel: The collection of abstractions, assumptions, and descriptions of physical processes representing the behavior of the reality of interest from which the mathe-matical model or validation experiments can be constructed (adapted from ASME V&V 10).Configuration Management (CM): A management discipline applied over the product's life cycle to provide visibility into and to control changes to performance, functional, and physical characteristics (NPR 7120.5D, NASA Space Flight Program and Project Management Requirements).Credibility: The quality to elicit belief or trust in M&S results.Decision: Those technical decisions related to design, development,Criticalmanufacturing, ground, or flight operations that may impact human safety or mission success, as measured by program/project-defined criteria.Emulation: The use of an M&S to imitate another system, so that the M&S behaves like or appears to be the other system.Endorsement: A formal assurance that a product, process, or service conforms to specified characteristics. (Examples of endorsement include “accreditation”—the official acceptance of a model or simulation and its associated data to use for a specific purpose—and “certification,” which is similar to accreditation, but often applies to a class of purposes or a general domain and generally implies an independent and/or third-party certifier.)HumanSafety: The condition of being protected from death, permanently disabling injury, severe injury, and several occupational illnesses. In the NASA context this refers to safety of the public, astronauts, pilots and the NASA workforce (adapted from NPR 8000.4 and the NASA Safety Hierarchy).Limits of Operation: The boundary of the set of parameters for which an M&S result is acceptable based on the program/project-required outcomes of verification, validation, and uncertainty quantification.Model: The mathematical equations, boundary values, initial conditions,Mathematicaland modeling data needed to describe the conceptual model (ASME V&V 10).Mission Success Criteria: Standards against which the program or project will be deemed a success. Mission success criteria may be both qualitative and quantitative, and may cover mission cost, schedule, and performance results as well as actual mission outcomes (NPR 7120.5C, NASA Program and Project Management Processes and Requirements).Model: A description or representation of a system, entity, phenomena, or process (adapted from Banks, J., ed. (1998). Handbook of Simulation. New York: John Wiley & Sons).(A model may be constructed from multiple sub-models; the sub-models and the integrated sub-models are all considered models. Likewise, any data that goes into a model is considered part of the model. A model of a model (commonly called a metamodel), e.g., a response surface constructed from the results of M&S, is considered a model).Referent: Data, information, knowledge, or theory against which simulation results can be compared (adapted from ASME V&V 10).Risk: The combination of the probability that a program or project will experience an undesired event and the consequences, impact, or severity of the undesired event, if it were to occur. Both the probability and consequences may have associated uncertainties (adapted from NPR 7120.5D).SensitivityAnalysis: The study of how the variation in the output of a model can be apportioned to different sources of variation in the model input and parameters (adapted from Saltelli and others, 2000).Simulation: The imitation of the characteristics of a system, entity, phenomena, or process using a computational model.Stimulation: The description of a type of simulation whereby artificially generated signals are provided to real equipment in order to trigger it to produce the result required for verification of a real-world system, training, maintenance, or for research and development.Subject Matter Expert: An individual having education, training, or experience in a particular technical or operational discipline, system, or process and who participates in an aspect of M&S requiring his/her expertise.Tailoring: The documentation and approval of the adaptation of the processes and approach to complying with requirements according to the purpose, complexity, and scope of a NASA program or project. (NPR 7123.1A, NASA Systems Engineering Processes and Requirements).Uncertainty: (1) The estimated amount or percentage by which an observed or calculated value may differ from the true value (The American Heritage Dictionary of the English Language, 4th ed.). (2) A broad and general term used to describe an imperfect state of knowledge or a variability resulting from a variety of factors including, but not limited to, lack of knowledge, applicability of information, physical variation, randomness or stochastic behavior, indeterminacy, judgment, and approximation (adapted from NPR 8715.3B, NASA General Safety Program Requirements).Quantification: The process of identifying all relevant sources ofUncertaintyuncertainties, characterizing them in all models, experiments, and comparisons of M&S results and experiments, and of quantifying uncertainties in all relevant inputs and outputs of the simulation or experiment.Validation: The process of determining the degree to which a model or a simulation is an accurate representation of the real world from the perspective of the intended uses of the model or the simulation.Verification: The process of determining that a computational model accurately represents the underlying mathematical model and its solution from the perspective of the intended uses of M&S.Waiver: A documented authorization intentionally releasing a program or project from meeting a requirement (NPR 7120.5D). Deviations and exceptions are considered special cases of waivers.4. REQUIREMENTSThis standard establishes a minimum set of requirements and recommendations for the use of M&S to support critical decisions.For decisions based on results from M&S, the risk assumed by the decision maker is often misestimated due to inadequate assessment of uncertainties within M&S development, verification, validation, execution, analysis, and reporting. This standard establishes practicesto enable a more accurate assessment of this risk by making M&S credibility more apparent tothe decision maker. This standard emphasizes documentation and CM of M&S to enforce transparency, repeatability, and traceability; and it requires that key M&S personnel receive appropriate training.The requirements and recommendations are generic in nature because of their broad applicability to all types of M&S. Implementation details of the M&S requirements should be addressed in discipline-specific Recommended Practices, project/program management plans, etc.The following organizational structure is employed in this standard:4.1 Programmatics4.2 Models4.3 Simulations and Analyses4.4 Verification, Validation, and Uncertainty Quantification4.5 Identification and Use of Recommended Practices4.6 Training4.7 Assessing the Credibility of M&S Results4.8 Reporting Results to Decision MakersIn many instances, the modeling, simulation, and analysis activities are interwoven, particularly during the development, verification, and validation phases. This standard is intended to be inclusive of all these possibilities.Many of the requirements in this standard require documentation. With the exception of the documentation required for reports to decision makers (section 4.8), this documentation may consist of a reference to other existing documents, such as a journal article, a technical report, or a program/project document, provided that all the required details are contained in the referenced document(s).4.1 ProgrammaticsCritical decisions that are based entirely or partially on M&S are usually made within the context of a program or project. Program and project management have the responsibility to identify and document the parties responsible for complying with the requirements in this standard.The actual person identified by program and project management to fulfill the role of the “responsible party” in specific requirements will likely vary depending upon the context of the requirement; for example, the responsible party might be the lead, or another supporting person associated with the model development, operation, analysis, and/or reporting of results to decision makers.Program and project management in collaboration with the Technical Authority have the responsibility to identify and document the extent and level of formality of documentation needed to meet the documentation requirements in this standard. Some requirements, in particular, 4.1.5,4.2.6, 4.2.8, 4.3.6, 4.4.1, 4.4.2, 4.4.4, 4.4.5, 4.4.6, 4.4.7, 4.4.8, and 4.4.9, are to be interpreted as meaning that the activity in question is not required per se, but that whatever was done is to be documented, and if nothing was done a clear statement to that effect is to be documented. Program and project management in collaboration with the Technical Authority have the responsibility to identify and document the critical decisions to be addressed with M&S and to determine which M&S are in scope.The latter determination should be based upon the risk posed by the anticipated use of the M&S. Appendix A describes a representative M&S risk assessment matrix for this purpose.Furthermore, the Technical Authority has the particular responsibility to assure appropriate outcomes of Req. 4.1.3.The responsible party performs the following:Req. 4.1.1 – Shall document the risk assessment for any M&S used in critical decisions,Req. 4.1.2 – Shall identify and document those M&S that are in scope.Req. 4.1.3 – Shall define the objectives and requirements for M&S products including the following:a. The acceptance criteria for M&S products, including any endorsement for theM&S.b. The rationale for the weights used for the subfactors in the CredibilityAssessment Scale (see Appendix B.4).c. I ntended use.d. M etrics (programmatic and technical).e. V erification, validation, and uncertainty quantification (see section 4.4).f. Reporting of M&S information for critical decisions (see section 4.8).g.CM (artifacts, timeframe, processes) of M&S.(The acceptance criteria in 4.1.3 (a) includes specification of what constitutes a favorable comparison for the Verification Evidence, Validation Evidence, Input Pedigree Evidence, andUse History level definitions in the Credibility Assessment Scale (see Appendix B).)Req. 4.1.4– Shall develop a plan (including identifying the responsible organization(s)) for the acquisition, development, operation, maintenance, and/or retirement of the M&S. Req. 4.1.5 – Shall document any technical reviews performed in the areas of Verification, Validation, Input Pedigree, Results Uncertainty, and Results Robustness (seeAppendix B).Req. 4.1.6 – Shall document M&S waiver processes.Req. 4.1.7 – Shall document the extent to which an M&S effort exhibits the characteristics of work product management, process definition, process measurement, processcontrol, process change, and continuous improvement, including CM and M&Ssupport and maintenance.4.2 ModelsThe processes of developing conceptual, mathematical, or computational models are all considered to be modeling activities. Empirically adjusting the results of a simulation in an attempt to improve correlation is considered a modeling activity.For models, the responsible party performs the following:Req. 4.2.1 – Shall document the assumptions and abstractions underlying the conceptual model, including their rationales.Req. 4.2.2 – Shall document the basic structure and mathematics of the model (e.g., reality modeled, equations solved, behaviors modeled, conceptual models).(For COTS, GOTS, MOTS, and legacy M&S, some of the documentation required in 4.2.1 and 4.2.2 may be available in published user guides; a reference to the user guides will suffice for this part of the documentation.)Req. 4.2.3 – Shall document data sets and any supporting software used in model development and input preparation.Req. 4.2.4 – Shall document required units and vector coordinate frames (where applicable) for all input/output variables in the M&S.Req. 4.2.5 – Shall document the limits of operation of models.Req. 4.2.6 – Shall document any methods of uncertainty quantification and the uncertainty in any data used to develop the model or incorporated into the model.Req. 4.2.7 – Shall document guidance on proper use of the model.(Guidance on proper use of a model includes descriptions of appropriate practices for set-up, execution, and analysis of results.)Req. 4.2.8 – Shall document any parameter calibrations and the domain of calibration.Req. 4.2.9 – Shall document updates of models (e.g., solution adjustment, change ofparameters, calibration, and test cases) and assign unique version identifier,description, and the justification for the updates.Req. 4.2.10 – Shall document obsolescence criteria and obsolescence date of the model. (Obsolescence refers to situations where changes to the real system invalidate the model—see item (e) of Diaz Action #4.)Req. 4.2.11 – Shall provide a feedback mechanism for users to report unusual results to model developers or maintainers.Req. 4.2.12 – Shall maintain (conceptual, mathematical, and computational) models and associated documentation in a controlled CM system.Req. 4.2.13 – Shall maintain the data sets and supporting software referenced in Req. 4.2.3 and the associated documentation in a controlled CM system.。
NASA Work Breakdown Structrue(WBS)Handbook
NASA/SP-2010-3404NASAWork Breakdown Structure (WBS) HandbookJanuary 2010NASA STI Program…in ProfileSince its founding, the National Aeronautics and Space Administration (NASA) has been dedicated to the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) program plays a key part in helping NASA maintain this important role.The NASA STI program operates under the auspices of the Agency Chief Information Officer. It collects, organizes, provides for archiving, and disseminates NASA‟s STI. The NASA STI program provides access to the NASA Aeronautics and Space Database and its public interface, the NASA technical report server, thus providing one of the largest collections of aeronautical and space science STI in the world. Results are published in both non-NASA channels and by NASA in the NASA STI report series, which include the following report types:Technical Publication: Reports of completed research or a major significant phase of research that present the results of NASA programs and include extensive data or theoretical analysis. Includes compilations of significant scientific and technical data and information deemed to be of continuingreference value. NASA counterpart of peer-reviewed formal professional papers but has less stringent limitations on manuscript length and extent of graphic presentations.Technical Memorandum:Scientific and technical findings that are preliminary or of specialized interest, e.g., quick release reports, working papers, and bibliographies that contain minimal annotation. Does not contain extensive analysis.Contractor Report: Scientific and technical findings by NASA sponsored contractors and grantees.Conference Publication:Collected papers from scientific and technical conferences, symposia, seminars, or other meetings sponsored or co-sponsored by NASA.Special Publication: Scientific, technical, or historical information from NASA programs, projects,and missions, often concerned with subjects having substantial public interest.Technical Translation:English-language translations of foreign scientific and technical materialpertinent to NASA‟s mission.Specialized services also include creating custom thesauri, building customized databases, and organizing and publishing research results.For more information about the NASA STI program, see the following:Access the NASA STI program home page at E-mail your question via the Internet to help@Fax your question to the NASA STI help desk at 301-621-0134Phone the NASA STI help desk at 301-621-0390Write to: NASA STI Help Desk, NASA Center for AeroSpace Information, 7115 Standard Drive,Hanover, MD 21076-1320NASA/SP-2010-3404Work Breakdown Structure (WBS) HandbookNational Aeronautics and Space Administration NASA HeadquartersWashington, D.C. 20546January 2010To request print or electronic copies or provide comments, contact the Office of the Chief Engineer atNASA HeadquartersElectronic copies are also available fromNASA Center for AeroSpace Information7115 Standard DriveHanover, MD 21076-1320at/TABLE OF CONTENTSList of Figures and Illustrations (vii)Preface (viii)P.1 Purpose (viii)P.2 Applicability (viii)P.3 Refer ences (viii)Acknowledgments (ix)Chapter 1 Introduction (1)1.1 Background Information (1)1.2 Policy (1)Chapter 2 WBS Overview (2)2.1 Definition (2)2.2 WBS Hierarchy (3)2.2.1 Establishing and Maintaining WBS Codes in NASA‟s Management Systems (6)2.2.2 Contract Work Breakdown Structure (CWBS) and CWBS Dictionary (7)2.2.3 WBS Elements by Other Performing Entities (8)2.3 Development Guidelines (9)2.4 Summary (10)Chapter 3 WBS Development and Control (11)3.1 WBS and the Project Life Cycle (11)3.2 WBS Activities and Responsibilities (12)3.3 Development Considerations (14)3.3.1 Compatibility of WBS and CWBS (14)3.3.2 Compatibility with Internal Management Systems (15)3.3.3 Correlation with Other Requirements (15)3.3.4 Number of Levels (16)3.3.5 All Inclusiveness (19)3.3.6 Change Control (20)3.4 WBS Development Techniques (20)3.4.1 Preparing Functional Requirement Block Diagrams (21)3.4.2 Coding WBS Elements in a Consistent Manner (21)3.4.3 Preparing Element Tree Diagrams (22)3.4.4 Preparing a WBS Dictionary (24)3.4.5 Using Development Checklists (26)3.4.6 Using WBS Templates (28)3.5 Common Development Errors (28)3.5.1 Using Unsuitable Old WBS (28)3.5.2 Non-Product Elements (28)3.5.3 Center Breakouts at Inappropriate Levels (29)3.5.4 Incorrect Element Hierarchy (31)Chapter 4 WBS Uses (33)4.1 Technical Management (34)4.1.1 Specification Tree (34)4.1.2 Configuration Management (34)4.1.3 Integrated Logistics Support (34)4.1.4 Test and Evaluation (35)4.2 Work Identification and Assignment (35)4.3 Schedule Management (35)4.4 Cost Management (36)4.5 Performance Management (37)4.6 Risk Management (38)APPENDIX A: Acronym Listing (40)APPENDIX B: Glossary of Terms (41)APPENDIX C: Standard Project Level 2 Templates andWBS Dictionary Content Descriptions (43)APPENDIX D: Standard Data Requirements Document (49)APPENDIX E:Contractor CWBS Example (51)List of Figures and Illustrations2-1 Partial WBS Illustration (2)2-2 WBS Levels Illustration (4)2-3 Partial WBS with Numbering System (5)2-4 MdM Code Request Template Illustration (7)2-5 WBS/CWBS Relationship (8)3-1 WBS and the Project Life Cycle (11)3-2 WBS Element Content (12)3-3 WBS Development Activities & Responsibilities (14)3-4 WBS Hierarchy Ill ustration (17)3-5 Relationships between WBS, OBS, CA, WP, and PP (19)3-6 Agency WBS Numbering System (22)3-7 Partial WBS Tree Diagram Illustrating Recommended Practices (23)3-8 Sample Software WBS Illustration (24)3-9 WBS Dictionary Illustration (26)3-10 Unsuitable Non-Product, Phase-Oriented WBS (29)3-11 Unsuitable Functional/Organizational Oriented WBS (29)3-12 Center Breakout Guidance for a WBS (31)3-13 Illustration of Incorrect Element Hierarchy (32)4-1 The WBS as a Project Management Tool for Integration (33)4-2 WBS and the Development of the PMB (38)PREFACEP.1 PurposeThe purpose of this document is to provide program/project teams necessary instruction and guidance in the best practices for Work Breakdown Structure (WBS) and WBS dictionary development and use for project implementation and management control. This handbook can be used for all types of NASA projects and work activities including research, development, construction, test and evaluation, and operations. The products of these work efforts may be hardware, software, data, or service elements (alone or in combination). The aim of this document is to assist project teams in the development of effective work breakdown structures that provide a framework of common reference for all project elements.The WBS and WBS dictionary are effective management processes for planning, organizing, and administering NASA programs and projects. The guidance contained in this document is applicable to both in-house, NASA-led effort and contracted effort. It assists management teams from both entities in fulfilling necessary responsibilities for successful accomplishment of project cost, schedule, and technical goals.Benefits resulting from the use of an effective WBS include, but are not limited to: providing a basis for assigned project responsibilities, providing a basis for project schedule development, simplifying a project by dividing the total work scope into manageable units, and providing a common reference for all project communication.P.2 ApplicabilityThis handbook provides WBS development guidance for NASA Headquarters, NASA Centers, the Jet Propulsion Laboratory, inter-government partners, academic institutions, international partners, and contractors to the extent specified in the contract or agreement.P.3 ReferencesNPR 7120.5, “NASA Space Flight Program and Project Management Requirements” Appendix GNPR 7120.7, “NASA Information Technology and Institutional Infrastructure Program and Project Requirements”NPR 7120.8, “NASA Research and Technology Program and Project Management Requirements” Appendix KMPD 7120.1, “Earned Value Management Policy” (MSFC Document)MPR 7120.5, “Earned Value Management System Requirements” (MSFC Document)Mil-HDBK-881A, Department of Defense Handbook, Work Breakdown Structures for Defense Materiel ItemsPMI 978-1-933890-13-5, “Practice Standard for Work Breakdown Structures”AcknowledgmentsPrimary point of contact: Kenneth W. Poole, Office of Strategic Analysis and Communication, Marshall Space Flight Center.The following individuals are recognized as core contributors to the content of this handbook update: Richard H. Beisel, Jr., Technical WriterJimmy W. Black, NASA/Marshall Space Flight CenterKenneth W. Poole, NASA/Marshall Space Flight CenterA special acknowledgement also goes to all the unknown individuals who actively participated in, and contributed to the NASA “Work Breakdown Structure Reference Guide”, dated May 1994. This document served as the foundation for much of the content contained in this handbook.Chapter 1: Introduction1.1 Background InformationIn accordance with NASA directives NPR 7120.5, NASA Space Flight Program and Project Management Requirements, NPR 7120.7, NASA Information Technology and Institutional Infrastructure Program and Project Requirements, and NPR 7120.8, NASA Research and Technology Program and Project Management Requirements, the WBS and WBS Dictionary are mandatory elements of a project‟s management baseline. This section provides general WBS information including policy, definition, guidelines, and development process.1.2 PolicyPer NPR 7120.5, NPR 7120.7, and NPR 7120.8, a project WBS is a key element of NASA project management processes. The WBS and WBS Dictionary requirements contained in these three documents apply to all types of NASA programs and projects depending on the product line involved. The WBS is a core element of a project‟s baseline throughout all life cycle phases. It is the responsibility of each project manager and their project team to ensure that the WBS requirements are adhered to, not only during initial WBS development, but also in its on-going maintenance and control. The standard project WBS structures and templates identified in the above NPRs were intended to apply only to new projects established on or after June 1, 2005.Chapter 2: WBS Overview2.1 DefinitionEach NASA program has a set of goals which are developed from NASA mission needs. These program goals are expanded into specific project objectives. The function of management is to plan and direct project activities to achieve the program goals.A WBS is a product-oriented family tree that identifies the hardware, software, services, and all other deliverables required to achieve an end project objective. The purpose of a WBS is to subdivide the project‟s work content into manageable segments to facilitate planning and control of cost, schedule, and technical content. A WBS is developed early in the project development cycle. It identifies the total project work to be performed, which includes not only all NASA in-house work content, but also all work content to be performed by contractors, international partners, universities, or any other performing entities. Work scope not contained in the project WBS should not be considered part of the project. The WBS divides the work content into manageable elements, with increasing levels of detail. The following example displays a portion of a WBS which illustrates how project work may be hierarchically subdivided.Figure 2-1: Partial WBS IllustrationA WBS is developed by first identifying the system or project end item to be structured, and then successively subdividing it into increasingly detailed and manageable subsidiary work products or elements. Most of these elements are the direct result of work (e.g., assemblies, subassemblies, and components), while others are simply the aggregation of selected products into logical sets (e.g., buildings and utilities) for management control purposes. In either case, the subsidiary work product has its own set of goals and objectives which must be met in order for the project objectives to be met. Detailed tasks which must be performed to satisfy the subsidiary work product goals and objectives are then identified and defined for each work product or element on which work will be performed. Completion of an element is both measurable and verifiable based upon specific completion criteria established during upfront project planning by the project team. Because WBS element/product completion can be verified, a WBS provides a solid basis for technical, schedule, and cost plans and status. No other structure (e.g., code of account, functional organization, budget and reporting, cost element) satisfactorily provides an equally solid basis for incremental project performance assessment. 2.2 WBS HierarchyThe project WBS structure should encompass the entire project‟s approved scope of work. It usually consists of multiple levels of products along with associated work content definitions that are contained in a companion document called the WBS Dictionary. All NASA projects have the capability of subdividing the work content down to any level necessary for management and insight. However, the Agency‟s Core Financial System currently limits the ability to capture costs to a maximum of seven levels. These seven levels of the WBS are defined below.•Level 1 is the entire project.•Level 2 elements are the major operational product elements along with key common, enabling products (as defined in NPR 7120.5 and NPR 7120.8 standard WBS templates).•Level 3-7 contains further definable subdivisions of the products contained in the level 2 elements (e.g., subsystems, components, documents, functionality).There are numerous terms used to define level three and succeeding levels of the WBS below the system level. Some typical examples used for hardware and software product elements are subsystem, subassembly, component, module, functionality, equipment, and part. Project management and other enabling organizational support products should use the subdivisions and terms that most effectively and accurately depict the hierarchical breakdown of project work into meaningful products.A properly structured WBS will readily allow complete aggregation of cost, schedule, and performance data from lower elements up to the project or program level without allocation of a single element of work scope to two or more WBS elements. WBS elements should be identified by a clear, descriptive title and by a numbering scheme as defined by the project that performs the following functions: •Identifies the level of the WBS element.•Identifies the higher-level element into which the element will be integrated.The following general illustration depicts how work scope can be arranged as hierarchical WBS levels of work within a project. All project effort must be included, including all NASA in-house, contracted, international partner, university, and any other performing entity implementations. Enablingorganizational common products must also be reflected appropriately with a project WBS (e.g., Project Management, Safety & Management Assurance (S&MA), Systems Engineering and Integration (SE&I)).Figure 2-2: WBS Levels IllustrationThe following portion of a project WBS reflects an example of the NASA authorized WBS numbering system. This numbering scheme is called the NASA Structure Management (NSM) system. For each Agency project, the WBS established by the project must use the NSM numbering scheme and also must correlate exactly through level seven to the corresponding financial accounting structure utilized for each project within the NASA Core Financial System. This requirement helps to ensure that project costs are applied to the correct work scope being implemented by the project. This process is necessary for carrying out successful Earned Value Management (EVM) processes.Figure 2-3: Partial WBS with Numbering SystemThe top two levels of a project WBS are dictated and controlled by the Agency through standard, level-two WBS templates. These templates, along with their associated narrative content descriptions, are contained in NPR 7120.5 (Appendix G for Space Flight projects) and NPR 7120.8 (Appendix K for Technology Development projects). WBS levels 3 and lower are developed and should be controlled by project management and, as-required, prime contractors that are involved in project implementation. In cases where prime contractors are involved, lower-level element coding must be traceable to the appropriate upper-level elements that are controlled by the NASA Project Manager. While not being a requirement, it is recommended that the prime contractor lower-level WBS numbering scheme be consistent with the overall project WBS numbering format. This will allow easier total project integration of cost and EVM data for project reporting.NASA standard level-two WBS templates and narrative descriptions can be found in Appendix C.2.2.1 Establishing and Maintaining WBS Codes in NASA’s Management Systems All Programmatic and Institutional WBS element codes are not recognized as official NASA structures until first being approved and established in the Agency‟s Metadata Management (MdM) system. The MdM system is a web-based e nterprise application that contains the Agency‟s official NSM data elements and associated attributes. MdM is the only Agency application used for identifying, creating, tracking, organizing and archiving of Appropriation, Mission, Theme, Program, Project, and Work Breakdown Structure (WBS) 2 through 7 NSM structural elements. As the Agency‟s enterprise repository for NSM data, MdM supplies WBS codes to the Agency‟s Core Financial System, Budget Formulation System, funds distribution systems, and the Program/Project On-Line Library and Resource Information System(POLARIS) as they require coding structure data. The WBS approval process involves designated MdM code approvers that have been established across the Agency to review new WBS elements requested by programmatic and institutional organizations. It should be noted that project managers are not currently included as MdM code approvers. Because of this, all project managers should continually monitor new WBS elements that are added to their projects for validity and correctness.Process instructions for entering new or modifying existing, WBS elements within the MdM system may be obtained from the designated MdM code requester point of contact at each NASA Center. Additional information regarding the MdM system may also be obtained by contacting the MdM Help Desk (mdmhelpdesk@). All modifications made to existing WBS element codes contained in Agency management systems listed above must also first be initiated and approved through the MdM System. A WBS code that has been approved and officially entered into the MdM System cannot be removed. This restriction enhances a project‟s ability to maintain accurate historical project data.As a program/project or institutional organization determines the need, a code request may be submitted to the authorized Center MdM code requester that addresses any of the following MdM activity categories:The creation of new WBS elements.The modification of attribute data associated with any WBS element.The total closure of a WBS element so that it is unavailable for any further Commitment,Obligation, Cost, and Disbursement (COCD).The “t echnical” clos ure a WBS element so that it is unavailable for any further Commitmentsand Obligations, but does allow availability for any final costs or disbursements for the element.The “r etire ment” of WBS elements that are stil l in the Formulation structure and haven‟t beenapproved to receive funds.The MdM request may involve the use of a standard request template. The following example of a request template reflects necessary data required to enable the request to be adequately reviewed, approved, and entered into the MdM system by the authorized code requester.Figure 2-4: MdM Code Request Template Illustration2.2.2 Contract Work Breakdown Structure (CWBS) and CWBS DictionaryFor projects involving significant contracted effort, a project‟s preliminary WBS should be included in the Request for Proposal (RFP) and used as a starting point for individual contractors to develop their extended CWBS. It is important to remember that each project will have only one WBS and that the contractor‟s CWBS is just an extension of the upper-level project WBS elements. The RFP will also contain specific instructions to contractors that their proposal should be submitted in accordance with the specified preliminary WBS. As noted in the previous section, the contractor‟s WBS coding scheme must be traceable to upper-level project controlled elements. Again, while not a requirement, it is highly recommended that the extended CWBS be developed using a numbering format that is consistent with the standard NASA project WBS element numbering format.The CWBS contains the complete WBS hierarchy for a specific contract scope of work. It is developed by the contractor in accordance with the contract statement of work (SOW). It includes the WBS elements for the products which are to be furnished by the contractor. The contractor extends these elements and defines the lower-level products. It should be noted that within the contractor‟s own internal management systems and WBS process, there is not the same limitation of a maximum seven levels of product hierarchy, as is the case for NASA‟s WBS hierarchical format. However, as NASA projects reflect a total integrated WBS structure (containing both in-house and contractor effort), only the upper-element levels of contractor products can typically be included due to the seven-level limitation of the NSM numbering system. The contractor reporting requirements will indicate the CWBS levels or elements for which contract status is to be reported to the government. Contractor WBS reporting requirements are contained in a standard contractor Data Requirements Document (DRD) which should be a part of the RFP. A standard DRD template is shown in Appendix D.A properly formulated CWBS provides a consistent and visible framework that facilitates uniform planning, assignment of responsibilities, data summarization, and status reporting. A properly formulated CWBS is also a key consideration in the successful implementation of EVM processes.The following figure illustrates the relationship of an overall project WBS and its CWBS elements:Figure 2-5: WBS/CWBS RelationshipThe following is a typical contract clause used for incorporating the CWBS into a contract. Project managers should work with the contracts or procurement organization to develop the desired contractual language for such a clause.“A Contract Work Breakdown Structure has been negotiated between the governmentand the contractor. The top levels of the Contract Work Breakdown Structure areformally incorporated into the contract as set forth in Appendix E. The elements shownin this exhibit may not be changed except by contractual action. Lower-tier elementswhich are not shown in this exhibit may be changed by the contractor as appropriate,provided that notification of such changes is provided to NASA‟s Contracting Officer.”A CWBS example is found in Appendix E.2.2.3 Work Breakdown Structure Elements by Other Performing EntitiesFor projects involving scope content being implemented by other performing entities, such as (but not limited to) international partners and universities, the WBS should also reflect this work content withincontractual arrangements, they are nonetheless responsible for specified WBS elements through some type of directed agreement arrangement with NASA. This work content must also be subdivided to an appropriate level of product-oriented detail for project planning, control, and reporting. The resulting work elements must be clearly identified and included within the project WBS under the correct hierarchical branches in just the same manner as contractor CWBS elements. Again, while not a requirement, it is highly recommended that the extended WBS for other entity work be developed using a numbering format that is consistent with the standard NASA WBS element numbering format, or at a minimum clearly traceable to the correct upper-level WBS hierarchical elements.2.3 Development GuidelinesOnly one WBS is prepared for each NASA project and includes both in-house and contractor effort. While there is no single "right way" to prepare and utilize a WBS, there are some generally recommended guidelines that should be followed. Considering the following general guidance will assist in creating and implementing a WBS.a.The WBS is prepared as early as project definition will permit.b. A preliminary WBS is initially developed early in project formulation to define the top levels of aWBS. These preliminary elements should reflect the entire scope of work contained in the overall project life cycle including project definition, development, launch, and operations.c. A single WBS is used for both technical and business management through level seven.d.Both high level and detailed WBS planning should involve all stakeholders to ensure that properplanning is done and that ALL parties agree on the final WBS prior to approval.e.When a project is authorized by a Program Commitment Agreement, the WBS becomesformalized as the project outline; changes to it must be formally approved by the program office. f. A preliminary CWBS is developed from the basic elements of the preliminary WBS and expandedfor use in the RFP, preparation of proposals, and the evaluation and selection process.g.Normally, only the second or third level elements of the preliminary CWBS will be specified byNASA in an RFP. The CWBS is considered a preliminary CWBS until it is finalized as a result of negotiation and incorporated formally into the contract.h. A total project WBS is created by combining the elements of the NASA in-house WBS elementswith the contractor‟s CWBS elements, and also by all other WBS elements being implemented by other performing entities.i.As the project scope of work changes, the WBS is revised to reflect changes that are formallyapproved.j.All top-level WBS elements do not have to be sub-divided to the same level of detail. As associated element risk, cost, and/or complexity increases, further breakdown may be necessary.k.When high-risk items are located at low CWBS levels (also low WBS levels by other performing entities), these items can be identified against the higher-level WBS or CWBS element of which the high risk item is a part.While most project WBS structures are different, the above guidance can help a project team ensure that proper and recommended WBS characteristics exist for any project.2.4 SummaryAs previously discussed, a WBS defines all work to be performed for project completion. It is a product-oriented structure, not an organizational structure. To develop and maintain a WBS, you must have a clear understanding of the project's objectives and the end item(s) or end product(s) of the work to be performed. The WBS provides a common reference for all project communication, both internally within the team and externally to project stakeholders. The WBS also provides a means of rolling up project data to any desired level for analysis and oversight.Because of its product orientation, a WBS provides the framework to plan, track and assess the project's technical, schedule, and cost performance.。
美国航空航天局
NASA将于美东时间2022年11月14日凌晨0时7分发射“阿尔忒弥斯1”号，11月4日前将把SLS火箭和“猎户座” 飞船转运至肯尼迪航天中心39B发射工位。
2022年10月，美国国家航空航天局（NASA）宣布，一组科学家和专家于当地时间10月24日开启对“不明空中 现象”(UAP)的新研究，该现象以前被称为不明飞行物现象（UFO）。
喷气推进实验室（JPL）美国国家航空航天局拥有46年的研究历史，由国家航空咨询委员会的四个主要实验 机构与其中80名成员改组而成，陆军弹道飞弹署（Army Ballistic Missile Agency）和海军研究中心（Naval Research Laboratory）的一部份也整合到NASA的组织里。
2018年11月12日，美国国家航空和宇宙航行局宣布计划25年内载人登陆火星。
当地时间2021年11月9日，美国国家航空航天局局长比尔·尼尔森表示，该部门的载人登月项目将推迟到 2025年以后。美国前总统特朗普曾定下于2024年重返月球的目标，然而该项目已经数次推迟。对此，尼尔森表示， 该计划在科学上不具可行性。
发射时间为格林尼治标准时间2015年3月13日凌晨2点44分，美国东部时间下午晚上10点44分。磁场多尺度任 务耗资大约11亿美元，美国宇航局戈达德太空飞行中心负责四颗卫星的制造和测试，此外还有多所机构和高校研 发的科学仪器被安装在MMS卫星上。本项任务将使我们进一步认识磁重联现象。
机构设置
实验机构
管理机构
研发机构
太阳出现巨大黑子美国国家航空航天局（NASA）华盛顿指挥部为最高管理机构。下设埃姆斯研究中心 （NASA-ARC）、德莱顿飞行研究中心（NASA-DFRC）、格伦研究中心（NASA-GRC）、戈达德空间研究所（NASAGISS）、戈达德航天飞行中心（NASA-GSFC）、独立认证与鉴定研究所（NASA-ⅣVF）、喷气推进实验室（NASAJPL）、肯尼迪航天中心（NASA-KSC）、兰利研究中心（NASA-LRC）、马歇尔航空飞行中心（NASA-MSFC）、斯 坦尼斯航天中心（NASA-SSC）、沃罗普飞行研究所（NASA-WFF）和白沙试验研究所（NASA-WST F）。
Glider Flying Handbook说明书
Glider Flying Handbook2013U.S. Department of TransportationFEDERAL AVIATION ADMINISTRATIONFlight Standards Servicei iPrefaceThe Glider Flying Handbook is designed as a technical manual for applicants who are preparing for glider category rating and for currently certificated glider pilots who wish to improve their knowledge. Certificated flight instructors will find this handbook a valuable training aid, since detailed coverage of aeronautical decision-making, components and systems, aerodynamics, flight instruments, performance limitations, ground operations, flight maneuvers, traffic patterns, emergencies, soaring weather, soaring techniques, and cross-country flight is included. Topics such as radio navigation and communication, use of flight information publications, and regulations are available in other Federal Aviation Administration (FAA) publications.The discussion and explanations reflect the most commonly used practices and principles. Occasionally, the word “must” or similar language is used where the desired action is deemed critical. The use of such language is not intended to add to, interpret, or relieve a duty imposed by Title 14 of the Code of Federal Regulations (14 CFR). Persons working towards a glider rating are advised to review the references from the applicable practical test standards (FAA-G-8082-4, Sport Pilot and Flight Instructor with a Sport Pilot Rating Knowledge Test Guide, FAA-G-8082-5, Commercial Pilot Knowledge Test Guide, and FAA-G-8082-17, Recreational Pilot and Private Pilot Knowledge Test Guide). Resources for study include FAA-H-8083-25, Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-2, Risk Management Handbook, and Advisory Circular (AC) 00-6, Aviation Weather For Pilots and Flight Operations Personnel, AC 00-45, Aviation Weather Services, as these documents contain basic material not duplicated herein. All beginning applicants should refer to FAA-H-8083-25, Pilot’s Handbook of Aeronautical Knowledge, for study and basic library reference.It is essential for persons using this handbook to become familiar with and apply the pertinent parts of 14 CFR and the Aeronautical Information Manual (AIM). The AIM is available online at . The current Flight Standards Service airman training and testing material and learning statements for all airman certificates and ratings can be obtained from .This handbook supersedes FAA-H-8083-13, Glider Flying Handbook, dated 2003. Always select the latest edition of any publication and check the website for errata pages and listing of changes to FAA educational publications developed by the FAA’s Airman Testing Standards Branch, AFS-630.This handbook is available for download, in PDF format, from .This handbook is published by the United States Department of Transportation, Federal Aviation Administration, Airman Testing Standards Branch, AFS-630, P.O. Box 25082, Oklahoma City, OK 73125.Comments regarding this publication should be sent, in email form, to the following address:********************************************John M. AllenDirector, Flight Standards Serviceiiii vAcknowledgmentsThe Glider Flying Handbook was produced by the Federal Aviation Administration (FAA) with the assistance of Safety Research Corporation of America (SRCA). The FAA wishes to acknowledge the following contributors: Sue Telford of Telford Fishing & Hunting Services for images used in Chapter 1JerryZieba () for images used in Chapter 2Tim Mara () for images used in Chapters 2 and 12Uli Kremer of Alexander Schleicher GmbH & Co for images used in Chapter 2Richard Lancaster () for images and content used in Chapter 3Dave Nadler of Nadler & Associates for images used in Chapter 6Dave McConeghey for images used in Chapter 6John Brandon (www.raa.asn.au) for images and content used in Chapter 7Patrick Panzera () for images used in Chapter 8Jeff Haby (www.theweatherprediction) for images used in Chapter 8National Soaring Museum () for content used in Chapter 9Bill Elliot () for images used in Chapter 12.Tiffany Fidler for images used in Chapter 12.Additional appreciation is extended to the Soaring Society of America, Inc. (), the Soaring Safety Foundation, and Mr. Brad Temeyer and Mr. Bill Martin from the National Oceanic and Atmospheric Administration (NOAA) for their technical support and input.vv iPreface (iii)Acknowledgments (v)Table of Contents (vii)Chapter 1Gliders and Sailplanes ........................................1-1 Introduction....................................................................1-1 Gliders—The Early Years ..............................................1-2 Glider or Sailplane? .......................................................1-3 Glider Pilot Schools ......................................................1-4 14 CFR Part 141 Pilot Schools ...................................1-5 14 CFR Part 61 Instruction ........................................1-5 Glider Certificate Eligibility Requirements ...................1-5 Common Glider Concepts ..............................................1-6 Terminology...............................................................1-6 Converting Metric Distance to Feet ...........................1-6 Chapter 2Components and Systems .................................2-1 Introduction....................................................................2-1 Glider Design .................................................................2-2 The Fuselage ..................................................................2-4 Wings and Components .............................................2-4 Lift/Drag Devices ...........................................................2-5 Empennage .....................................................................2-6 Towhook Devices .......................................................2-7 Powerplant .....................................................................2-7 Self-Launching Gliders .............................................2-7 Sustainer Engines .......................................................2-8 Landing Gear .................................................................2-8 Wheel Brakes .............................................................2-8 Chapter 3Aerodynamics of Flight .......................................3-1 Introduction....................................................................3-1 Forces of Flight..............................................................3-2 Newton’s Third Law of Motion .................................3-2 Lift ..............................................................................3-2The Effects of Drag on a Glider .....................................3-3 Parasite Drag ..............................................................3-3 Form Drag ...............................................................3-3 Skin Friction Drag ..................................................3-3 Interference Drag ....................................................3-5 Total Drag...................................................................3-6 Wing Planform ...........................................................3-6 Elliptical Wing ........................................................3-6 Rectangular Wing ...................................................3-7 Tapered Wing .........................................................3-7 Swept-Forward Wing ..............................................3-7 Washout ..................................................................3-7 Glide Ratio .................................................................3-8 Aspect Ratio ............................................................3-9 Weight ........................................................................3-9 Thrust .........................................................................3-9 Three Axes of Rotation ..................................................3-9 Stability ........................................................................3-10 Flutter .......................................................................3-11 Lateral Stability ........................................................3-12 Turning Flight ..............................................................3-13 Load Factors .................................................................3-13 Radius of Turn ..........................................................3-14 Turn Coordination ....................................................3-15 Slips ..........................................................................3-15 Forward Slip .........................................................3-16 Sideslip .................................................................3-17 Spins .........................................................................3-17 Ground Effect ...............................................................3-19 Chapter 4Flight Instruments ...............................................4-1 Introduction....................................................................4-1 Pitot-Static Instruments ..................................................4-2 Impact and Static Pressure Lines................................4-2 Airspeed Indicator ......................................................4-2 The Effects of Altitude on the AirspeedIndicator..................................................................4-3 Types of Airspeed ...................................................4-3Table of ContentsviiAirspeed Indicator Markings ......................................4-5 Other Airspeed Limitations ........................................4-6 Altimeter .....................................................................4-6 Principles of Operation ...........................................4-6 Effect of Nonstandard Pressure andTemperature............................................................4-7 Setting the Altimeter (Kollsman Window) .............4-9 Types of Altitude ......................................................4-10 Variometer................................................................4-11 Total Energy System .............................................4-14 Netto .....................................................................4-14 Electronic Flight Computers ....................................4-15 Magnetic Compass .......................................................4-16 Yaw String ................................................................4-16 Inclinometer..............................................................4-16 Gyroscopic Instruments ...............................................4-17 G-Meter ........................................................................4-17 FLARM Collision Avoidance System .........................4-18 Chapter 5Glider Performance .............................................5-1 Introduction....................................................................5-1 Factors Affecting Performance ......................................5-2 High and Low Density Altitude Conditions ...........5-2 Atmospheric Pressure .............................................5-2 Altitude ...................................................................5-3 Temperature............................................................5-3 Wind ...........................................................................5-3 Weight ........................................................................5-5 Rate of Climb .................................................................5-7 Flight Manuals and Placards ..........................................5-8 Placards ......................................................................5-8 Performance Information ...........................................5-8 Glider Polars ...............................................................5-8 Weight and Balance Information .............................5-10 Limitations ...............................................................5-10 Weight and Balance .....................................................5-12 Center of Gravity ......................................................5-12 Problems Associated With CG Forward ofForward Limit .......................................................5-12 Problems Associated With CG Aft of Aft Limit ..5-13 Sample Weight and Balance Problems ....................5-13 Ballast ..........................................................................5-14 Chapter 6Preflight and Ground Operations .......................6-1 Introduction....................................................................6-1 Assembly and Storage Techniques ................................6-2 Trailering....................................................................6-3 Tiedown and Securing ................................................6-4Water Ballast ..............................................................6-4 Ground Handling........................................................6-4 Launch Equipment Inspection ....................................6-5 Glider Preflight Inspection .........................................6-6 Prelaunch Checklist ....................................................6-7 Glider Care .....................................................................6-7 Preventive Maintenance .............................................6-8 Chapter 7Launch and Recovery Procedures and Flight Maneuvers ............................................................7-1 Introduction....................................................................7-1 Aerotow Takeoff Procedures .........................................7-2 Signals ........................................................................7-2 Prelaunch Signals ....................................................7-2 Inflight Signals ........................................................7-3 Takeoff Procedures and Techniques ..........................7-3 Normal Assisted Takeoff............................................7-4 Unassisted Takeoff.....................................................7-5 Crosswind Takeoff .....................................................7-5 Assisted ...................................................................7-5 Unassisted...............................................................7-6 Aerotow Climb-Out ....................................................7-6 Aerotow Release.........................................................7-8 Slack Line ...................................................................7-9 Boxing the Wake ......................................................7-10 Ground Launch Takeoff Procedures ............................7-11 CG Hooks .................................................................7-11 Signals ......................................................................7-11 Prelaunch Signals (Winch/Automobile) ...............7-11 Inflight Signals ......................................................7-12 Tow Speeds ..............................................................7-12 Automobile Launch ..................................................7-14 Crosswind Takeoff and Climb .................................7-14 Normal Into-the-Wind Launch .................................7-15 Climb-Out and Release Procedures ..........................7-16 Self-Launch Takeoff Procedures ..............................7-17 Preparation and Engine Start ....................................7-17 Taxiing .....................................................................7-18 Pretakeoff Check ......................................................7-18 Normal Takeoff ........................................................7-19 Crosswind Takeoff ...................................................7-19 Climb-Out and Shutdown Procedures ......................7-19 Landing .....................................................................7-21 Gliderport/Airport Traffic Patterns and Operations .....7-22 Normal Approach and Landing ................................7-22 Crosswind Landing ..................................................7-25 Slips ..........................................................................7-25 Downwind Landing ..................................................7-27 After Landing and Securing .....................................7-27viiiPerformance Maneuvers ..............................................7-27 Straight Glides ..........................................................7-27 Turns.........................................................................7-28 Roll-In ...................................................................7-29 Roll-Out ................................................................7-30 Steep Turns ...........................................................7-31 Maneuvering at Minimum Controllable Airspeed ...7-31 Stall Recognition and Recovery ...............................7-32 Secondary Stalls ....................................................7-34 Accelerated Stalls .................................................7-34 Crossed-Control Stalls ..........................................7-35 Operating Airspeeds .....................................................7-36 Minimum Sink Airspeed ..........................................7-36 Best Glide Airspeed..................................................7-37 Speed to Fly ..............................................................7-37 Chapter 8Abnormal and Emergency Procedures .............8-1 Introduction....................................................................8-1 Porpoising ......................................................................8-2 Pilot-Induced Oscillations (PIOs) ..............................8-2 PIOs During Launch ...................................................8-2 Factors Influencing PIOs ........................................8-2 Improper Elevator Trim Setting ..............................8-3 Improper Wing Flaps Setting ..................................8-3 Pilot-Induced Roll Oscillations During Launch .........8-3 Pilot-Induced Yaw Oscillations During Launch ........8-4 Gust-Induced Oscillations ..............................................8-5 Vertical Gusts During High-Speed Cruise .................8-5 Pilot-Induced Pitch Oscillations During Landing ......8-6 Glider-Induced Oscillations ...........................................8-6 Pitch Influence of the Glider Towhook Position ........8-6 Self-Launching Glider Oscillations During Powered Flight ...........................................................8-7 Nosewheel Glider Oscillations During Launchesand Landings ..............................................................8-7 Tailwheel/Tailskid Equipped Glider Oscillations During Launches and Landings ..................................8-8 Aerotow Abnormal and Emergency Procedures ............8-8 Abnormal Procedures .................................................8-8 Towing Failures........................................................8-10 Tow Failure With Runway To Land and Stop ......8-11 Tow Failure Without Runway To Land BelowReturning Altitude ................................................8-11 Tow Failure Above Return to Runway Altitude ...8-11 Tow Failure Above 800' AGL ..............................8-12 Tow Failure Above Traffic Pattern Altitude .........8-13 Slack Line .................................................................8-13 Ground Launch Abnormal and Emergency Procedures ....................................................................8-14 Abnormal Procedures ...............................................8-14 Emergency Procedures .............................................8-14 Self-Launch Takeoff Emergency Procedures ..............8-15 Emergency Procedures .............................................8-15 Spiral Dives ..................................................................8-15 Spins .............................................................................8-15 Entry Phase ...............................................................8-17 Incipient Phase .........................................................8-17 Developed Phase ......................................................8-17 Recovery Phase ........................................................8-17 Off-Field Landing Procedures .....................................8-18 Afterlanding Off Field .............................................8-20 Off-Field Landing Without Injury ........................8-20 Off-Field Landing With Injury .............................8-20 System and Equipment Malfunctions ..........................8-20 Flight Instrument Malfunctions ................................8-20 Airspeed Indicator Malfunctions ..........................8-21 Altimeter Malfunctions .........................................8-21 Variometer Malfunctions ......................................8-21 Compass Malfunctions .........................................8-21 Glider Canopy Malfunctions ....................................8-21 Broken Glider Canopy ..........................................8-22 Frosted Glider Canopy ..........................................8-22 Water Ballast Malfunctions ......................................8-22 Retractable Landing Gear Malfunctions ..................8-22 Primary Flight Control Systems ...............................8-22 Elevator Malfunctions ..........................................8-22 Aileron Malfunctions ............................................8-23 Rudder Malfunctions ............................................8-24 Secondary Flight Controls Systems .........................8-24 Elevator Trim Malfunctions .................................8-24 Spoiler/Dive Brake Malfunctions .........................8-24 Miscellaneous Flight System Malfunctions .................8-25 Towhook Malfunctions ............................................8-25 Oxygen System Malfunctions ..................................8-25 Drogue Chute Malfunctions .....................................8-25 Self-Launching Gliders ................................................8-26 Self-Launching/Sustainer Glider Engine Failure During Takeoff or Climb ..........................................8-26 Inability to Restart a Self-Launching/SustainerGlider Engine While Airborne .................................8-27 Self-Launching Glider Propeller Malfunctions ........8-27 Self-Launching Glider Electrical System Malfunctions .............................................................8-27 In-flight Fire .............................................................8-28 Emergency Equipment and Survival Gear ...................8-28 Survival Gear Checklists ..........................................8-28 Food and Water ........................................................8-28ixClothing ....................................................................8-28 Communication ........................................................8-29 Navigation Equipment ..............................................8-29 Medical Equipment ..................................................8-29 Stowage ....................................................................8-30 Parachute ..................................................................8-30 Oxygen System Malfunctions ..................................8-30 Accident Prevention .....................................................8-30 Chapter 9Soaring Weather ..................................................9-1 Introduction....................................................................9-1 The Atmosphere .............................................................9-2 Composition ...............................................................9-2 Properties ....................................................................9-2 Temperature............................................................9-2 Density ....................................................................9-2 Pressure ...................................................................9-2 Standard Atmosphere .................................................9-3 Layers of the Atmosphere ..........................................9-4 Scale of Weather Events ................................................9-4 Thermal Soaring Weather ..............................................9-6 Thermal Shape and Structure .....................................9-6 Atmospheric Stability .................................................9-7 Air Masses Conducive to Thermal Soaring ...................9-9 Cloud Streets ..............................................................9-9 Thermal Waves...........................................................9-9 Thunderstorms..........................................................9-10 Lifted Index ..........................................................9-12 K-Index .................................................................9-12 Weather for Slope Soaring .......................................9-14 Mechanism for Wave Formation ..............................9-16 Lift Due to Convergence ..........................................9-19 Obtaining Weather Information ...................................9-21 Preflight Weather Briefing........................................9-21 Weather-ReIated Information ..................................9-21 Interpreting Weather Charts, Reports, andForecasts ......................................................................9-23 Graphic Weather Charts ...........................................9-23 Winds and Temperatures Aloft Forecast ..............9-23 Composite Moisture Stability Chart .....................9-24 Chapter 10Soaring Techniques ..........................................10-1 Introduction..................................................................10-1 Thermal Soaring ...........................................................10-2 Locating Thermals ....................................................10-2 Cumulus Clouds ...................................................10-2 Other Indicators of Thermals ................................10-3 Wind .....................................................................10-4 The Big Picture .....................................................10-5Entering a Thermal ..............................................10-5 Inside a Thermal.......................................................10-6 Bank Angle ...........................................................10-6 Speed .....................................................................10-6 Centering ...............................................................10-7 Collision Avoidance ................................................10-9 Exiting a Thermal .....................................................10-9 Atypical Thermals ..................................................10-10 Ridge/Slope Soaring ..................................................10-10 Traps ......................................................................10-10 Procedures for Safe Flying .....................................10-12 Bowls and Spurs .....................................................10-13 Slope Lift ................................................................10-13 Obstructions ...........................................................10-14 Tips and Techniques ...............................................10-15 Wave Soaring .............................................................10-16 Preflight Preparation ...............................................10-17 Getting Into the Wave ............................................10-18 Flying in the Wave .................................................10-20 Soaring Convergence Zones ...................................10-23 Combined Sources of Updrafts ..............................10-24 Chapter 11Cross-Country Soaring .....................................11-1 Introduction..................................................................11-1 Flight Preparation and Planning ...................................11-2 Personal and Special Equipment ..................................11-3 Navigation ....................................................................11-5 Using the Plotter .......................................................11-5 A Sample Cross-Country Flight ...............................11-5 Navigation Using GPS .............................................11-8 Cross-Country Techniques ...........................................11-9 Soaring Faster and Farther .........................................11-11 Height Bands ..........................................................11-11 Tips and Techniques ...............................................11-12 Special Situations .......................................................11-14 Course Deviations ..................................................11-14 Lost Procedures ......................................................11-14 Cross-Country Flight in a Self-Launching Glider .....11-15 High-Performance Glider Operations and Considerations ............................................................11-16 Glider Complexity ..................................................11-16 Water Ballast ..........................................................11-17 Cross-Country Flight Using Other Lift Sources ........11-17 Chapter 12Towing ................................................................12-1 Introduction..................................................................12-1 Equipment Inspections and Operational Checks .........12-2 Tow Hook ................................................................12-2 Schweizer Tow Hook ...........................................12-2x。
NASA-STD-8739.3
NASA-STD-8739.3 w/Change 2December 1997PREVIOUS VERSION PUBLISHED AS NHB 5300.4(3A-2)SOLDERED ELECTRICALCONNECTIONS NASA TECHNICAL STANDARDNational Aeronautics andSpace AdministrationREVISIONSREVISION DESCRIPTION DATE Initial Issue12/15/97(FDG) Change 1Typographical corrections to the headers12/8/00on pages A10 and A12 (Changed (WBHIII)Acceptable to Unacceptable)Change 2Replaced erroneous figure 14 on page A-6 1/18/01(which was a duplicate of figure 8) with the (WBHIII)correct figureFOREWORDEffective Date: December 15 1997This Standard provides a baseline for NASA project offices to use when preparing or evaluating process procedures for the manufacture of space flight hardware or mission critical ground support equipment.This Standard:a. Prescribes NASA’s process and end-item requirements for reliable soldered electricalconnections.b. Establishes responsibilities for training personnel.c. Establishes responsibilities for documenting process procedures including supplierinnovations, special processes, and changes in technology.d. For the purpose of this Standard, the term supplier is defined as in-house NASA,NASA contractors, and subtier contractors.NASA Installations shall:a. Review and invoke the provisions of this Standard for procurements involving handsoldering of space flight hardware and mission critical ground support equipment.b. Review and invoke the provisions of this Standard for in-house operations involvinghand soldering of space flight hardware and mission critical ground supportequipment.c. Tailor specific provisions of this Standard to address program or unique contractual ormission requirements.d. Assure that NASA suppliers invoke this Standard on subcontractors, purchase orders,and on subtier suppliers where applicable.e. Furnish copies of this Standard in the quantities required to NASA suppliers andsubtier suppliers.Questions concerning the application of this Standard to specific procurements shall be referred to the procuring NASA installation, or its designated representative.This Standard cancels NHB 5300.4(3A-2), “Requirements for Soldered Electrical Connections.”This Standard shall not be rewritten or reissued in any other form not approved by NASA.Other processes not covered by this Standard may be required. The design, materials, and processes shall be defined in engineering documentation.Comments and suggestions for improving this Standard may be submitted using the form “NASA Technical Standard Improvement Proposal.” A copy of the form is included in Appendix B.Frederick D. GregoryAssociate Administrator forSafety and Mission AssuranceDISTRIBUTION:SDL1 (SIQ)NASA TECHNICAL STANDARDS FOR SPACE FLIGHT AND MISSION CRITICAL GROUND SUPPORT HARDWARENASA Technical Standards can be found on the World Wide Web at URL addresshttp://www//office/codeq/qdoc.pdf.Title Number Soldered Electrical Connections NASA-STD-8739.3 Crimping, Interconnecting Cables, Harnesses, and Wiring NASA-STD-8739.4Fiber Optic Terminations, Cable Assemblies, and Installation NASA-STD-8739.5 Workmanship Standard for Staking and Conformal Coating ofNAS 5300.4(3J-1)Printed Wiring Boards and Electronic AssembliesWorkmanship Standard for Surface Mount Technology NAS 5300.4(3M)Standard for Electrostatic Discharge Control (ExcludingNASA-STD-8739.7 Electrically Initiated Explosive Devices)CONTENTSPARAGRAPH PAGEFOREWORD (i)TABLE OF CONTENTS (iv)LIST OF FIGURES (vii)LIST OF TABLES (viii)LIST OF APPENDICES (viii)1.SCOPE....................................................................................................................1-1 1.1Purpose..........................................................................................................1-11.2Applicability...................................................................................................1-12.APPLICABLE DOCUMENTS................................................................................2-1 2.1Applicable Specifications................................................................................2-1 2.2Other Documents...........................................................................................2-2 3DEFINITIONS AND ACRONYMS.........................................................................3-13.1Definitions......................................................................................................3-1 3.2Acronyms.......................................................................................................3-74.GENERAL...............................................................................................................4-1 4.1General..........................................................................................................4-1 4.2Reliable Soldered Connections.......................................................................4-1 4.3Documentation...............................................................................................4-2 4.4Approval of Departures From This Standard..................................................4-24.5Rework and Repair........................................................................................4-25.TRAINING AND CERTIFICATION PROGRAM...................................................5-1 5.1General..........................................................................................................5-1 5.2Vision Requirements......................................................................................5-1 5.3Certification Levels........................................................................................5-1 5.4Training Program Requirements.....................................................................5-2 5.5Documentation...............................................................................................5-2 5.6Maintenance of Certification Status................................................................5-3 5.7Training Resources.........................................................................................5-46.FACILITIES, EQUIPMENT, MATERIALS, AND PARTS.....................................6-1 6.1Facility Cleanliness.........................................................................................6-1 6.2Environmental Conditions..............................................................................6-1 6.3Electrostatic Discharge Requirements.............................................................6-2 6.4Tool and Equipment Control..........................................................................6-2 6.5Soldering Tools and Equipment......................................................................6-3 6.6Conductor Preparation Tools.........................................................................6-4 6.7Thermal Shunts..............................................................................................6-5 6.8Inspection Optics...........................................................................................6-5 6.9In-Process Storage and Handling....................................................................6-5 6.10Material Solderability.....................................................................................6-5 6.11Solder............................................................................................................6-5 6.12Liquid Flux.....................................................................................................6-6 6.13Solvents and Cleaners.....................................................................................6-66.14Personnel Protection......................................................................................6-77.PREPARATION FOR SOLDERING.......................................................................7-1 7.1Preparation of Soldering Tools.......................................................................7-1 7.2Preparation of Conductors..............................................................................7-17.3Preparation of Printed Wiring Boards, Terminals, and Solder Cups.................7-28.PARTS MOUNTING...............................................................................................8-1 8.1General..........................................................................................................8-1 8.2Mounting of Terminals...................................................................................8-3 8.3Mounting of Parts to Terminals......................................................................8-4 8.4Mounting of Parts to PWB’S..........................................................................8-58.5Lead Terminations, Printed Wiring Boards.....................................................8-89.ATTACHMENT OF CONDUCTORS TO TERMINALS........................................9-1 9.1General..........................................................................................................9-1 9.2Turret and Straight Pin Terminals...................................................................9-2 9.3Bifurcated Terminals......................................................................................9-4 9.4Hook Terminals.............................................................................................9-7 9.5Pierced Terminals...........................................................................................9-8 9.6Solder Cups (Connector Type).......................................................................9-8 9.7Solder Cups (Swaged Type)...........................................................................9-9 9.8Insulation Sleeving Application......................................................................9-910.SOLDERING TO TERMINALS............................................................................10-1 10.1General........................................................................................................10-1 10.2Solder Application........................................................................................10-1 10.3High Voltage Terminations...........................................................................10-110.4Solder Cleaning............................................................................................10-211.HAND SOLDERING OF PRINTED WIRING ASSEMBLIES..............................11-1 11.1General........................................................................................................11-1 11.2Solder Application........................................................................................11-111.3Solder Cleaning............................................................................................11-312.AUTOMATIC WAVE SOLDERING....................................................................12-1 12.1General........................................................................................................12-1 12.2Preparation and Assembly............................................................................12-2 12.3Process Parameters......................................................................................12-2 12.4Wave Soldering............................................................................................12-2 12.5Cleaning.......................................................................................................12-312.6Inspection....................................................................................................12-313.QUALITY ASSURANCE PROVISIONS..............................................................13-1 13.1General........................................................................................................13-1 13.2Magnification Aids.......................................................................................13-1 13.3Documentation Verification..........................................................................13-1 13.4Documentation Authorization.......................................................................13-2 13.5Verification of Tools, Equipment, and Materials...........................................13-313.6Inspection Criteria........................................................................................13-314.CLEANLINESS REQUIREMENTS......................................................................14-1 14.1General........................................................................................................14-1 14.2Cleanliness Testing.......................................................................................14-1 14.3Testing Frequency........................................................................................14-1 14.4Test Limits...................................................................................................14-1 14.5Resistivity Of Solvent Extract Test...............................................................14-114.6Sodium Chloride (NacI) Equivalent Ionic Contamination Test......................14-215.VERIFICATION....................................................................................................15-1 15.1General........................................................................................................15-1LIST OF FIGURESFigure 6-1. Comfort Zone -- Temperature Versus Humidity Requirements...............................6-1 Figure 8-1. Terminal Damage...................................................................................................8-3 Figure 8-2. Roll Flange Terminal..............................................................................................8-3 Figure 8-3. V-Funnel Type Swage............................................................................................8-4 Figure 8-4. Elliptical Funnel Type Swage.................................................................................8-4 Figure 8-5. Stress Relief Examples...........................................................................................8-5 Figure 8-6. Horizontal Mount...................................................................................................8-5 Figure 8-7. Vertical Mount.......................................................................................................8-6 Figure 8-8. Radial Leaded Parts................................................................................................8-6 Figure 8-9. Hole Obstruction....................................................................................................8-7 Figure 8-10. Stress Relief Part Termination..............................................................................8-7 Figure 8-11. Bend Angle..........................................................................................................8-7 Figure 8-12. Conductors Terminating on Both Sides................................................................8-8 Figure 8-13. Lapped Lead Height above Board........................................................................8-9 Figure 8-14. Lapped Round Termination................................................................................8-10 Figure 8-15. Lapped Ribbon Leads.........................................................................................8-11 Figure 8-16. Clinched Termination.........................................................................................8-12 Figure 8-17. Lead Bend..........................................................................................................8-12 Figure 8-18. Straight-Through Termination............................................................................8-13 Figure 8-19. Straight-Through Lead Retention.......................................................................8-13 Figure 9-1. Wrap Orientation...................................................................................................9-2 Figure 9-2. Conductor Wrap....................................................................................................9-3 Figure 9-3. Turret Terminal......................................................................................................9-4 Figure 9-4. Continuous Run Wrapping--Turret Terminals.........................................................9-4 Figure 9-5. Bottom Route Connections to Bifurcated Terminals...............................................9-5 Figure 9-6. Side Route Connections to Bifurcated Terminals....................................................9-6LIST OF FIGURES - CONT.Figure 9-7. Lead Wrap.............................................................................................................9-7 Figure 9-8. Continuous Run Wrapping--Bifurcated Terminals...................................................9-7 Figure 9-9. Continuous Run Wrapping--Bifurcated Terminals Alternate Procedure...................9-7 Figure 9-10. Connections to Hook Terminals...........................................................................9-8 Figure 9-11. Connections to Pierced Terminals.........................................................................9-8 Figure 9-12. Connections to Solder Cups (Connector Type).....................................................9-9 Figure 9-13. Connections to Swaged Type Solder Cup.............................................................9-9 Figure 10-1 Solder-Ball Termination.....................................................................................10-2 Figure 11-1. Heel Fillet...........................................................................................................11-2 Figure 11-2. Round Lead Termination....................................................................................11-3LIST OF TABLESTable 6-1. Solvents and Cleaners..............................................................................................6-6 Table 7-1. Solder Contaminant Levels Maximum Allowable Percentby Weight of Contaminant.....................................................................................7-2 Table 14-1. Cleanliness Test Values.......................................................................................14-2LIST OF APPENDICESAPPENDIX A:ACCEPTABLE AND UNACCEPTABLE SOLDER CONNECTIONS........A-1 APPENDIX B:NASA TECHNICAL STANDARD IMPROVEMENT PROPOSAL.............B-1CHAPTER 1 - SCOPE1.1Purpose1.This publication sets forth requirements for hand and wave soldering to obtain reliable electrical connections. The prime consideration is the physical integrity of solder connections.2.Special requirements may exist that are not covered by or are not in conformance with the requirements of this publication. Engineering documentation shall contain the detail for such requirements, including modifications to existing hardware, and shall take precedence over appropriate portions of this publication when approved in writing by the procuring NASA Center prior to use.1.2Applicability1.This publication applies to NASA programs involving soldering connections for flight hardware, mission critical ground support equipment, and elements thereof, and wherever invoked contractually.2.This publication does not define the soldering requirements for Surface Mount Technology (SMT).THIS PAGE INTENTIONALLY LEFT BLANKCHAPTER 2 - APPLICABLE DOCUMENTS2.1Applicable SpecificationsCopies of the following specifications, when required in connection with a specific procurement, can be obtained from the procuring NASA Center or as directed by the contracting officer. Unless otherwise specified, the issue in effect on the date of invitation for bids or requests for proposal shall apply. The following related documents form a part of this publication to the extent specified herein.FEDERAL SPECIFICATIONS:TT-I-735Isopropyl AlcoholO-E-760Ethyl Alcohol (Ethanol) Denatured Alcohol; ProprietarySolvents and Special Industrial SolventsO-M-232"Methanol (Methyl Alcohol)"NASA SPECIFICATIONS:NHB 5300.4 (3L)Standard for Electrostatic Discharge Control (ExcludingElectronically Initiated Explosive Devices)NHB 1700.1(V1)NASA Safety Policy and Requirements DocumentNHB 8060.1C Flammability, Odor, Offgassing and CompatibilityRequirements and Test Procedures for Materials inEnvironments that Support CombustionNATIONAL STANDARDS:American National Standards Institute (ANSI):ANSI/J-STD-004Requirements for Soldering FluxesANSI/J-STD-006Requirements for Electronic Grade Solder Alloys andFluxed and Non-Fluxed Solid Solders for ElectronicSoldering ApplicationsANSI/NCSL Z540-1-1994General Requirements for Calibration Laboratoriesand Measuring and Test EquipmentAmerican Society for Testing and Materials (ASTM):ASTM/D1007Standard Specification for Secondary Butyl Alcohol2.2Other Documents:Industrial Ventilation: A Manual of Recommended Practice.Published by the American Conference of Governmental Industrial Hygienists;1330 Kemper Meadow Drive; Cincinnati, OH 45240.URL Occupational Safety and Health Administration, 29 CFR.CHAPTER 3 - DEFINITIONS AND ACRONYMS3.1.DefinitionsThe following definitions apply to terms used in this Standard.Article. A unit of hardware or any portion thereof required by the contract.Assembly. A functional subdivision of a component, consisting of parts or subassemblies that perform functions necessary for the operation of the component as a whole. Examples: regulator assembly, power amplifier assembly, gyro assembly, etc.Axial lead. Lead wire extending from a component or module body along its longitudinal axis.Bifurcated (split) Terminal. A terminal with a slot or split opening in which conductors are placed before soldering.Birdcage. A defect in stranded wire where the strands in the stripped portion between the covering of an insulated conductor and a soldered connection (or an end-tinned lead) have separated from the normal lay of the strands.Blister. Raised areas on the surface of the laminate caused by the pressure of volatile substances entrapped within the laminate.Blow Hole. A cavity in the solder surface whose opening has an irregular and jagged form, without a smooth surface.Bridging. A buildup of solder between components, conductors, and/or base substrate forming an undesired conductive path.Certification. The act of verifying and documenting that personnel have completed required training and have demonstrated specified proficiency and have met other specified requirements.Circumferential Separation. A crack or void in the plating extending around the entire circumference of a PTH, or in the solder fillet around the conductor, in the solder fillet around an eyelet, or at the interface between a solder fillet and a land.Cold Flow. Movement of insulation (e.g. Teflon) caused by pressure.Cold Solder Connection. A solder connection exhibiting poor wetting and a grayish, porous appearance due to insufficient heat, inadequate cleaning before to soldering, or excessive impurities in the solder.Component. A functional subdivision of a system, generally a self-contained combination of assemblies performing a function necessary for the system's operation. Examples: power supply, transmitter, gyro package, etc.Conduction Soldering. Method of soldering which employs a soldering iron for transfer of heat to the soldering area.Conductor. A lead, solid or stranded, or printed wiring path serving as an electrical connection. Conformal Coating. A thin electrically nonconductive protective coating that conforms to the configuration of the covered assembly.Connection. An electrical termination that was soldered. A solder joint.Construction Analysis. The process of destructively disassembling, testing, and inspecting a device for the purpose of determining conformance with applicable design, process, and workmanship requirements. This process is also known as Destructive Physical Analysis (DPA). Contaminant. An impurity or foreign substance present in a material that affects one or more properties of the material. A contaminant may be either ionic or nonionic. An ionic, or polar compound, forms free ions when dissolved in water, making the water a more conductive path. A non-ionic substance does not form free ions, nor increase the water's conductivity. Ionic contaminants are usually processing residue such as flux activators, finger prints, and etching or plating salts.Crazing. An internal condition occurring in the laminate base material in which the glass fibers are separated from the resin.Cup Terminal. A hollow, cylindrical terminal to accommodate one or more conductors. Delamination. A separation between plies within a base material or any planar separation within a multilayer PWB.Deviation. A specific authorization, granted before the fact, to depart from a particular requirement of specifications or related documents.Dewetting. The condition in a soldered area in which the liquid solder has not adhered intimately, but has receded, characterized by an abrupt boundary between solder and conductor, or solder and terminal/termination area leaving irregularly shaped mounds of solder separated by areas covered with a thin solder film.Disturbed Solder Joint. Unsatisfactory connection resulting from relative motion between the conductor and termination during solidification of the solder.Dross. Oxide and other contaminants that form on the surface of molten solder.Egress. An opening that provides a pathway from the interior of an enclosed space. Encapsulating Compound. An electrically nonconductive compound used to completely enclose and fill in voids between electrical components or parts.Excessive Solder Joint. Unsatisfactory solder connection wherein the solder obscures the configuration of the connection.Eyelet. A hollow tube inserted in a terminal or PWB to provide mechanical support for component leads or for electrical connection.Flatpack. A part with two straight rows of leads (normally on 0.050 inch centers) that are parallel to the part body.Fillet. A smooth concave buildup of material between two surfaces; e.g., a fillet of solder between a conductor and a solder pad or terminal.Flux. A chemically-active compound which, when heated, removes minor surface oxidation, minimizes oxidation of the basis metal, and promotes the formation of an intermetallic layer between solder and basis metal.Fractured Solder Joint. A joint showing evidence of cracking, resulting from movement between the conductor and termination, after solidification of the solder.Haloing. Mechanically-induced fracturing or delaminating on or below the surface of the base PWB material; it is usually exhibited by a light area around holes, other machined areas, or both. Hook Terminal. A terminal formed in a hook shape.Insufficient Solder Connection. A solder connection characterized by incomplete coverage of one or more of the metal surfaces being joined or by incomplete solder fillets.Interfacial Connection. A conductor that connects conductive patterns between opposite sides of a PWB.Interlayer Connection. An electrical connection between conductive patterns in different layers of a PWB.Joint. A solder joint; a termination.Lifted Land. A land that has lifted or separated from the base material, whether or not any resin is lifted with the land.Mission Essential Support Equipment. Equipment used in a closed loop with the system, where failure of this equipment would degrade the mission or imperil personnel. This category includes items of ground support equipment whose functions are necessary to support the count down phase and those items of ground support equipment used in pre-count down phases whose problems can create a safety hazard, cause damage to flight hardware, or inability to detect a problem on the flight hardware.Measling. Discrete white spots below the surface of the base material, usually caused by moisture, pressure, and/or thermally induced stress.Nick. A cut or notch on a conductor.Nonwetting. A condition whereby a surface has contacted molten solder, but the solder has not adhered to all of the surface; basis metal remains exposed.Offgassing. The release of volatile parts from a substance when placed in a vacuum environment that may affect crew members.。
2011年职称英语(理工类)阅读理解中英文背诵模板
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关于nasa的英语作文
关于nasa的英语作文Title: Exploring the Universe: NASA's Endeavors。
NASA, the National Aeronautics and Space Administration, stands as a beacon of human achievement and exploration. Founded in 1958, NASA has been at the forefront of space exploration, scientific discovery, and technological innovation. In this essay, we delve into the multifaceted role of NASA, its contributions to humanity, and the challenges it faces as it pushes the boundaries of space exploration.First and foremost, NASA's primary mission is toexplore space and advance our understanding of the universe. Through its various space missions, NASA has achieved remarkable feats, including landing humans on the moon, launching spacecraft to study distant planets and galaxies, and sending robotic probes to explore the far reaches ofour solar system and beyond.One of NASA's most iconic achievements is the Apollo moon landing missions. In 1969, NASA successfully landedthe Apollo 11 spacecraft on the lunar surface, makinghistory as Neil Armstrong and Buzz Aldrin became the first humans to set foot on another celestial body. This monumental achievement not only demonstrated the technological prowess of NASA but also inspired generations of people around the world to dream of exploring the cosmos.In addition to lunar exploration, NASA has played a crucial role in studying other planets in our solar system. Through missions like the Mars rovers and the Voyager spacecraft, NASA has provided invaluable insights into the geology, atmosphere, and potential habitability of planets beyond Earth. These missions have expanded ourunderstanding of the solar system and laid the groundworkfor future human exploration of other planets.Furthermore, NASA has been at the forefront ofscientific research in space. The Hubble Space Telescope, launched in 1990, has revolutionized our understanding ofthe universe by capturing stunning images of distantgalaxies, nebulae, and other cosmic phenomena. Hubble's observations have led to groundbreaking discoveries, suchas the existence of dark energy and the age of the universe, and have reshaped our understanding of cosmic evolution.Moreover, NASA plays a vital role in Earth science research, monitoring the planet's climate, atmosphere, and natural disasters from space. Satellites like the Landsat series and the Terra spacecraft provide essential data for understanding and addressing global environmental challenges, such as climate change, deforestation, and pollution. NASA's Earth science missions contribute to our efforts to protect and sustain our planet for future generations.Despite its numerous achievements, NASA facessignificant challenges as it continues to push the boundaries of space exploration. Budget constraints,political pressures, and technical hurdles often hinder the agency's ambitious goals. Additionally, the inherent risksof space travel pose challenges to the safety and well-being of astronauts and spacecraft.However, despite these challenges, NASA remains committed to its mission of exploration and discovery. The agency continues to push the boundaries of human knowledge and inspire future generations to pursue careers in science, technology, engineering, and mathematics (STEM). Through international collaboration and public-private partnerships, NASA strives to overcome obstacles and achieve new milestones in space exploration.In conclusion, NASA stands as a symbol of human ingenuity, curiosity, and perseverance. From the historic moon landings to the cutting-edge discoveries of the Hubble Space Telescope, NASA has transformed our understanding of the universe and our place within it. As we look to the future, NASA will continue to lead the way in exploring the cosmos, inspiring generations to dream of reaching for the stars.。
nasa 体系工程手册
nasa 体系工程手册NASA的体系工程手册是一份非常重要的指南，用于指导NASA在设计、开发和运行航天器及相关项目时的系统工程实践。
该手册为NASA工程师和项目团队提供了一套标准化的方法和工具，以确保项目的成功和可靠性。
该手册被称为NASA-STD-8739.8，全名为"NASA Systems Engineering Handbook: Management of a System's Architecture and Technical Baseline"（《NASA体系工程手册：系统架构和技术基线的管理》）。
该手册最新版本为2009年发布的Rev C版本。
这份手册提供了一种系统工程的方法论和框架，以支持复杂的航天器和系统的设计和开发。
内容包括以下主要方面：1. 系统工程基础：介绍了系统工程的基本概念、原则和过程。
2. 体系结构与技术基线管理：讨论了系统架构的定义、演化和管理，并提供了技术基线的控制和变更管理的指导。
3. 需求分析与管理：介绍了需求工程的方法和技术，包括需求的获取、分析、验证和管理。
4. 设计：讨论了系统设计的原则和方法，包括工程解决方案的开发、评估和选择。
5. 验证和验证：介绍了验证和验证的过程，以确保系统满足要求。
6. 决策分析：提供了一些决策分析工具和技术，以支持系统工程师在项目决策中的思考和分析。
此外，该手册还包括了一些附录，提供了进一步的资源和参考资料，如流程图、模板和相关标准等。
需要注意的是，由于技术的不断发展和进步，NASA体系工程手册可能会进行更新和修订。
因此，最好参考最新版本的手册和相关指导文件来确保遵守最新的NASA系统工程规范和最佳实践。
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2004nasa safety standard
National Aeronautics and NASA-STD-8719.13B w/Change 1 Space Administration July 8, 2004 SOFTWARE SAFETY STANDARDNASA TECHNICAL STANDARD REPLACES NASA-STD-8719.13A DATED SEPTEMBER 1997FOREWORDThe NASA Software Safety Standard (hereinafter referred to as “this Standard”) is approved for use by NASA Headquarters and all NASA Centers and is intended to provide a common framework for consistent practices across NASA programs.This Standard was developed by the NASA Office of Safety and Mission Assurance to provide the requirements for software safety across all NASA Centers, programs and facilities. It describes the activities necessary to ensure that safety is designed into the software that is acquired or developed by NASA. All Program/Project Managers, Area Safety Managers, IT managers, and other responsible managers are to assess the inherent safety risk of the software in their individual programs. The magnitude and depth of software safety activities should reflect the risk posed by the software while fulfilling the requirements of this Standard.This Standard revises NASA-STD-8719.13A. Changes in software technology, software development methodology, and the field of computing necessitate updating this Standard on a regular basis. Requirements for new technology and methodology areas, such as commercial off-the-shelf software, software reuse, and security are included.Comments and questions concerning the contents of this publication should be referred to the National Aeronautics and Space Administration Headquarters, Director, Safety and Assurance Requirements Management Division, Office of the Chief for Safety and Mission Assurance, Washington, DC 20546./s/Bryan O’ConnorChief of the Safety and Mission Assurance OfficeRECORD OF CHANGESChange No. Date Title or Brief Description EnteredByDateEntered1 7/28/2004Correcterroneous paragraph numbering forparagraphs 5, 5.1.1, 5.1.2, 5.1.3, 5.1.4, 5.2, 5.3,5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 5.10, 5.11, 5.12, 5.13,5.14, 5.15, 5.16, 6,6.1, 6.2, 6.3, 6.4, and7.Correction of paragraph numbering caused somepage numbers to change, the Table of Contentshas been revised accordingly.WBHIII 7/24/2004CONTENTSPARAGRAPH PAGE1 SCOPE (1)1.1 Purpose (1)1.2 Applicability (2)1.3 Assumptions (3)1.4 Guide to this Standard (3)1.4.1 Requirements (3)1.4.2 Software Safety Personnel (3)1.4.3 Plans and Documents (4)DOCUMENTATION (5)2 RELATEDDocuments (5)2.1 Applicable2.1.1 Government documents (5)2.1.2 Non-government documents (5)Documents (5)2.2 Reference2.2.1 Government documents (5)2.2.2 Non-government documents (5)3 DEFINITIONS AND ACRONYMS (7)3.1 Definitions used in this Standard (7)3.2 Acronyms used in this Standard (13)DETERMINATION (14)SOFTWARE4 SAFETY-CRITICALProcess (14)4.1 Determination4.2 Software as Part of System Safety Analysis (16)MANAGEMENT (17)SAFETY5 SOFTWARE5.1 Organization and Responsibilities (17)5.1.1 Center Safety and Mission Assurance Organization (17)5.1.2 Program/Project/Facility Management Responsibilities (18)5.1.3 Software Safety Personnel (19)5.1.4 Other Personnel Responsibilities (21)5.2 Software Safety Planning (21)5.3 Personnel Qualifications and Training (23)5.4 Resources (23)5.5 Software Life Cycles (24)Requirements (24)5.6 Documentation5.7 Traceability (25)5.8 Discrepancy and Problem Reporting and Tracking (26)Management Activities (26)5.9 SoftwareConfiguration5.10 Software Assurance Activities (27)5.11 Tool Support and Approval (28)5.12 Off-the-shelf Software (COTS/GOTS/OTS) (28)Management (29)5.13 ContractProcess (29)5.14 Certification5.15 Waivers/Deviations (30)5.16 Security (31)6 SOFTWARE DEVELOPMENT AND SAFETY ANALYSES (32)6.1 Software Safety Requirements and Analysis (32)6.2 Software Design and Safety Analysis (34)6.3 Software Implementation and Safety Analysis (35)6.4 Software Test and Safety Analysis (36)7 OPERATIONAL USE OF THE SOFTWARE (40)Appendix A. Example - Tailoring Activities to Implement Standard.......................................1-A Appendix B. Requirements Compliance Matrix........................................................................1-B1 SCOPE1.1 PurposeThis Standard specifies the software safety activities, data, and documentation necessary for the acquisition or development of software in a safety-critical system. Safety-critical systems that include software must be evaluated for software’s contribution to the safety of the system during the concept phase, and prior to the start, or in the early phases, of the acquisition or planning for the given software. Unless the evaluation proves that the software is not involved in the system safety, this Standard is to be followed. See section 1.2 for guidance, and section 4.1 for requirements (and definition), on the determination of safety-critical software.The purpose of this Standard is to provide requirements to implement a systematic approach to software safety as an integral part of the project’s overall system safety program, software development, and software assurance processes. It describes the activities necessary to ensure that safety is designed into software that is acquired or developed by NASA and that safety is maintained throughout the software and system life cycle. How these requirements are met will vary with the program, project, facility, Mission, and Center. The NASA-GB-8719.13, Software Safety Guidebook, provides additional information on how to implement software safety and software safety related activities in a manner consistent with the software’s role in system safety. The risk posed by safety-critical software will vary with the system safety criticality (e.g., type of hazard) and the level of control or influence the software has on system safety factors. While the requirements of this Standard cannot be tailored, the specific activities and depth of analyses needed to meet the requirements can, and should, be tailored to the software safety risk. That is, while the requirements must be met, the implementation and approach to meeting these requirements may and should vary to reflect the system to which they are applied. Substantial differences may exist when the same software safety requirements are applied to dissimilar projects. Appendix A shows how an example medium-sized project might meet the requirements of this Standard. A compliance matrix listing all of the requirements in this Standard along with the personnel roles and responsibilities required for each requirement, is available in Appendix B. This matrix can be used by the program, project, or facility as a checklist to ensure coverage of all requirements in the StandardThere are two kinds of safety requirements: process oriented and technical. Both need to be addressed and properly documented within a program, project, or facility. This Standard contains process oriented requirements (what needs to be done to ensure software safety). Technical requirements are those that specify what the system must include or implement (e.g., two-fault tolerance). Use of this Standard does not preclude the necessity to follow applicable technical standards.Software safety activities occur within the context of system safety, system development, and software development and assurance. In an ideal system environment, information flows freely among all elements of the program/project, and concerns are appropriately addressed. Providing the needed information to the concerned parties in a timely manner is key to any successful exchange.The requirements specified in this Standard will:• Identify when software plays a part in system safety and generate appropriate requirements to ensure safe operation of the system.• Ensure that software is considered within the context of system safety, and that appropriate measures are taken to create safe software.• Ensure that software safety is addressed in project planning, management, and control activities.• Ensure that software safety is considered throughout the system life cycle, including generation of requirements, design, coding, test, and operation of the software.• Ensure that software acquisitions, whether off-the-shelf or contracted, have evaluated, assessed, and addressed the software for its safety contributions and limitations.• Ensure that software verification activities include software safety verifications.• Ensure that the proper certification requirements are in place and accomplished prior to the actual operational use of the software.• During operational use of the software, ensure that all changes and reconfigurations of the software are analyzed for their impacts to system safety.1.2 ApplicabilityThis Standard applies to all safety-critical software acquired or developed by NASA. Section 4.1 (and section 3, Glossary) defines what software is considered safety-critical. Section 4.1 also details the “litmus test” that all projects must apply to their software, to determine if it is safety-critical and therefore subject to this Standard.The NPR 8715.3 NASA Safety Manual specifies the methodology for determining whether a system is safety-critical. This software safety standard further defines whether the software in a safety-critical system is also safety-critical.This Standard applies to software that resides in hardware (i.e., firmware). This Standard also applies to government furnished software, purchased software (including commercial-off-the-shelf (COTS) software), and any other reused software when included in a safety-critical NASA system. Safety-critical software can be found in all types of systems, including Flight, Ground Support, and Facilities.If the system is already in development or is a legacy system, then the software within the system should be assessed for its contribution to the safety of the system. If the software is found to be safety-critical, a plan should be worked out with the safety personnel on how the system will or will not meet the requirements in this Standard. Legacy systems will be addressed on acase-by-case basis and the decisions should be documented. Systems in the maintenance and operation phase should at least have the safety requirements marked during the routine maintenance cycle.In addition, COTS software cannot be ignored in safety-critical systems. The COTS software should be assessed before use and verified within the system it is contained to ensure the COTS cannot do something inadvertent to cause a hazard (see NASA-GB-8719.13 NASA Software Safety Guidebook).A key factor to keep in mind when determining the applicability of this Standard is that the presence of non-software hazard controls or mitigations (e.g., operator intervention, hardware overrides) reduces, but does not normally eliminate, the software safety risk. Hence, the need for applying this Standard is not removed. The NASA Software Safety Guidebook, NASA-GB-8719.13, should be used to create a set of activities and analyses tailored to meet the requirements of this Standard.This Standard does not discourage the use of software in safety-critical systems. When designed and implemented correctly, software is often the first, and sometimes the best, hazard detection and prevention mechanism in the system. Software can be used to prevent problems before they lead to hazardous conditions. This Standard provides requirements that will ensure that the safety-critical software receives the required levels of attention throughout the project life cycle.1.3 AssumptionsSoftware covered by this Standard is to be developed following sound software engineering practices and in accordance with appropriate development standards and requirements.Any software covered by this Standard is also be covered by the NASA-STD-8739.8 NASA Software Assurance Standard. Software safety is a discipline of the software assurance process, and it provides complementary activities to the other software assurance disciplines. This Standard stresses coordination between these disciplines, as well as with system safety and software development, to minimize duplication of effort.All activities of this Standard are to be accomplished as an integral part of the overall management, engineering, and assurance activities for any safety-critical system containing software.1.4 Guide to this Standard1.4.1 RequirementsRequirements are designated with a number (e.g., 5.2.1) and contain a shall statement. These statements are the only sentences to be considered requirements. In some cases, additional explanatory information is added to clarify or add specific guidelines related to a requirement. Many sections begin with an introductory paragraph(s) that describes in less formal terms, or at a higher level, the requirements embodied in the section. Additional information, such as good practices, may also be included in these paragraphs. These introductory paragraphs are to be considered as guidance and not as requirements.1.4.2 Software Safety PersonnelThe use of the terms software safety personnel, software safety engineer, and software safety manager are not used in this document as prescriptive, required personnel assignments. The authors recognize that one or more individuals with varying titles and additional responsibilities may fill these positions. There is no implication for required use of these titles within any organization. They are merely used herein to provide a consistent label for those with expertise in software and system safety who will be evaluating and performing the functions and procedures discussed in this Standard. This may be fulfilled by systems safety personnel withstrong software backgrounds, software engineers with safety exposure and systems safety guidance, or software assurance engineers with safety expertise.Software expertise is needed for safety-critical systems with software. The safety of systems with software can be affected by the language, compiler, operating system, software development strategy, software design architecture, development tools, etc. Software safety must go beyond mere identification of systems hazards to possible software functions. For this, a certain expertise is needed as well as an understanding of the system and environment in which the software must operate. It would be great if several individuals contained all this knowledge, but this is not always possible. Thus a collaboration is usually needed between systems, systems safety and software to jointly determine software’s safety contribution, the controls, design features, verifications, and requirements needed to assure the system is as safe as possible.1.4.3 Plans and DocumentsThis Standard often refers to recording information in an “appropriate document.” It is not the intent of this Standard to designate what documents a program, project, or facility must generate. The software safety information must be recorded within the documentation, but the exact type of documentation is left up to the program, project, or facility.When specific plans are mentioned (e.g., the Software Safety Plan), they can be standalone documents or incorporated within other documents (e.g., system safety plan, a software management/development plan, or a software or system assurance plan)..DOCUMENTATION2 RELATED2.1 Applicable DocumentsDocuments cited in this Standard are listed in this section.2.1.1 Government documentsNATIONAL AERONAUTICS AND SPACE ADMINISTRATIONNPD 8700.1 NASA Policy for Safety and Mission AssuranceNPD 2820.1 NASA Software PoliciesNPR 8715.3 NASA Safety ManualNPD 2810.1 Security of Information TechnologyNPR 2810.1 Security of Information TechnologyNASA-STD-8739.8 NASA Software Assurance StandardNASA-GB-8719.13 NASA Software Safety Guidebook2.1.2 Non-government documentsIEEE 1228 Standard for Software Safety PlansISO 8402 Quality Management and Quality Assurance – Vocabulary IEEE 610.12 Standard Glossary of Software Engineering Terminology RTCA DO-178B Software Considerations in Airborne Systems and EquipmentCertification2.2 Reference DocumentsDocuments listed in this section are for reference only.2.2.1 Government documentsNATIONAL AERONAUTICS AND SPACE ADMINISTRATIONNPR 7120.5 Program and Project Management Processes and Requirements NPR 8000.4 Risk Management Procedures and Guidelines2.2.2 Non-government documentsIEEE 12207.0 Standard for Information Technology: Software life cycleprocessesDOD Joint SoftwareSoftware System Safety Handbook System SafetyCommittee3 DEFINITIONSANDACRONYMS3.1 Definitions used in this StandardTerm DefinitionAccident An unplanned event or series of events that results in death, injury,occupational illness, or damage to or loss of equipment, property, ordamage to the environment; a mishap. [IEEE 1228]Baseline A specification or product that has been reviewed formally and agreedupon, that thereafter serves as the basis for further development, and thatcan be changed only through formal change control procedures.Black Box Testing Testing that ignores the internal mechanism of a system or component and focuses solely on the outputs generated in response to selected inputs andexecution conditions. [IEEE 610.12]Certification The process of formally verifying that a system, software subsystem, orcomputer program is capable of satisfying its specified requirements in anoperational environment for a defined period of time. This includes anyrequirements for safing the system upon the occurrence of failures withpotential safety impacts.Component A constituent element of a system or subsystem.Customer The NASA program, project, facility, or other entity that acquires software developed by another organization.Decomposition The process of breaking a system or component up into constituent parts.For requirements, the top-level requirements will be general, and lower-level (decomposed) requirements will be specific.Deviation A documented variance that authorizes departure from a particular safety requirement where the intent of the requirement is being met throughalternate means that provide an equivalent level of safety. Deviations areonly employed for variances identified prior to development. Deviationsdo not require a revision to documents defining the affected item. Failure Non-performance or incorrect performance of an intended function of aproduct. A failure is often the manifestation of one or more faults.Failure Modes And Effects Analysis (FMEA) A bottom-up systematic, inductive, methodical analysis performed to identify and document all identifiable failure modes at a prescribed level and to specify the resultant effect of the modes of failure.Fault An inherent defect in a product which may or may not ever manifest, such as a bug in software code.Fault Tree Analysis (FTA) An analytical technique, whereby an undesired system state is specified and the system is then analyzed in the context of its environment and operation to find all credible ways in which the undesired event can occur.Fault Detection, Isolation, And Recovery (FDIR) Detection: The ability to discover faults; the process of determining that a fault has occurred.Isolation: The process of determining the location or source of a fault. Recovery: A process of overcoming a fault without permanent reconfiguration.Firmware The combination of a hardware device and computer instructions and/or computer data that reside as read-only software on the hardware device.Functional Requirements Functional requirements define what the system or subsystem must do to fulfill its mission, including timing and performance requirements. All requirements that will be expressed in the system, rather than in the process to create the system, are functional requirements.Hazard Existing or potential condition that can result in, or contribute to, a mishap or accident.Hazard Control Means of reducing the risk of exposure to a hazard. This includes design or operational features used to reduce the likelihood of occurrence of ahazardous effect or the severity of the hazard.Hazard Mitigation Any action that reduces or eliminates the risk from hazards.Independent Verification And Validation (IV&V) Verification and validation performed by an organization that is technically, managerially, and financially independent of the development organization. IV&V, as a part of Software Assurance, plays a role in the overall NASA software risk mitigation strategy applied throughout the life cycle, to improve the safety and quality of software systems.Memorandum Of Agreement (MOA) A written agreement between two or more parties that defines the roles and responsibilities of each party with respect to the collaborative efforts of a particular program/project. A MOA is sometimes called a Memorandum of Understanding (MOU).Mission-Critical Item or function that must retain its operational capability to assure no mission failure (i.e., for mission success).Off-The-Shelf Software Ready-made software used “as-is” within a system.• Commercial Off-the-shelf (COTS) software refers to purchased software such as operating systems, libraries, or applications.• MOTS (modified off-the-shelf) software is typically a COTS product whose source code can be modified.• GOTS (government off-the-shelf) software is typically developed by the technical staff of the government agency for which it iscreated.Partitioning Separation,physically and/or logically, of safety-critical functions from other functionality.Preliminary Hazard Analysis (PHA) A gross study of the initial system concepts. It is used to identify all of the energy sources that constitute inherent hazards. The energy sources are examined for possible accidents in every mode of system operation. The analysis is also used to identify methods of protection against all of the accident possibilities.Project Life Cycle Steady progression of a project from its beginning to its completion anddecommissioning. A set of steps or phases through which a projectadvances. This includes formulation/conception through sign-off anddelivery to the customer and may include operations, maintenance andretirement depending on how the project is defined. The operations andmaintenance phases through retirement may be a separate project life cycleand as such still needs to address the requirements in this Standard. Regression Testing The selective retesting of a system that has been modified to ensure thatany defects have been fixed and that no other previously working functionshave failed or ceased to work as expected as a result of the changes. Reused Software Software created for another system that is incorporated into the systemunder development.Risk The combination of (1) the probability (qualitative or quantitative) that aprogram or project will experience an undesired event and (2) theconsequences, impact, or severity of the undesired event were it to occur. Safety-Critical Any condition, event, operation, process, equipment, or system thatpossesses the potential of directly or indirectly causing harm to humans,destruction of the system, damage to property external to the system, ordamage to the environment.Safety-Critical Software Software is safety-critical if it meets at least one of the following criteria:1. Resides in a safety-critical system (as determined by a hazardanalysis) AND at least one of the following:a. Causes or contributes to a hazard.b. Provides control or mitigation for hazards.c. Controls safety-critical functions.d. Processes safety-critical commands or data.e. Detects and reports, or takes corrective action, if the systemreaches a specific hazardous state.f. Mitigates damage if a hazard occurs.g. Resides on the same system (processor) as safety-criticalsoftware.2. Processes data or analyzes trends that lead directly to safetydecisions (e.g., determining when to turn power off to a wind tunnel to prevent system destruction).3. Provides full or partial verification or validation of safety-criticalsystems, including hardware or software subsystems.Safety And Mission Assurance (SMA) SMA refers to the organization, i.e., the offices and people at all NASA Field Installations and Headquarters, who support customers with policy, process, and standards development; oversight and insight; and technology development and transfer, in the disciplines of safety, reliability, maintainability, and quality.Safety Assurance Ensuring that the requirements, design, implementation, verification and operating procedures for the identified software minimizes or eliminatesthe potential for hazardous conditions.Software Acquisition The process of obtaining software from another organization via a documented agreement; a set of activities that are used to acquire software products from another organization.Software Assurance The planned and systematic set of activities that ensure that software life cycle processes and products conform to requirements, standards, and procedures. [IEEE 610.12] For NASA this includes the disciplines of Software Quality (functions of Software Quality Engineering, Software Quality Assurance, Software Quality Control), Software Safety, Software Reliability, Software Verification and Validation, and IV&V.Software Element A portion of a software item that is logically discrete. The softwareelement will depend on context, and can be a subset of the requirements,software design, software source code, or any software entity.Software Development Life Cycle All activities required to analyze, define, develop, test, and deliver a software product. The development life cycle ends when the software becomes operational and is accepted formally for use by the customer and/or operations. Once operational, any changes/upgrades are to be treated as reduced scale software development lifecycles and the main activities (analyze, define, develop, test and deliver) should apply during these maintenance activities.Software Hazard A hazard caused by incorrect software control of hazardous hardware. The software might be functioning correctly (according to its requirements) orin a failure mode.Software Life Cycle The period of time that begins when a software product is conceived and ends when the software is no longer available for use. The software life cycle typically includes a concept phase, requirements phase, design phase, implementation phase, test phase, installation and checkout phase, operation and maintenance phase, and sometimes, retirement phase. [IEEE 610.12] The software development life cycle is a subset of this larger life cycle.Software Patch A modification made directly to an object program without reassembling or recompiling from the source program. [IEEE 610.12]Software Safety The aspects of software engineering and software assurance that provide a systematic approach to identifying, analyzing, and tracking softwaremitigation and control of hazards and hazardous functions (e.g., data andcommands) to ensure safer software operation within a system.Software Safety Analysis The application of system safety engineering techniques throughout the software life cycle to ensure that errors that could reduce system safety have been eliminated or controlled to an acceptable level of risk.Software Safety Change Analysis An evaluation of whether a proposed change could invoke a hazardous state, affect a hazard control, increase the likelihood of a hazardous state, adversely affect safety-critical software, or change the safety-criticality of an existing software component. This activity determines the impact of changes made in assumptions, specifications, requirements, design, code, equipment, test plans, environment, user documentation, and training materials.Software Safety Plan A document that details the activities, general relative schedule of needed activities, communication paths and responsibilities for performing software safety activies as part of the systems safety program. This does not have to be a standalone document, but could be included as part of the systems safety plan or, for small projects, an overall assurance plan. While it may be written by either the project/program/facility or by the safety personnel within the Center SMA organization(s), both must sign off on it.。
nasa_std_8739_6
This page intentionally left blank.DOCUMENT HISTORY LOGThis document is subject to reviews per Office of Management and Budget Circular A-119, Federal Participation in the Development and Use of Voluntary Standards (02/10/1998) and NPR 7120.10, Technical Standards for NASA Programs and Projects.This page intentionally left blank.TABLE OF CONTENTSCHAPTER 1.Scope (8)1.1Scope (8)1.2Applicability (8)1.3Special Requirements (9)1.4RELIEF FROM REQUIREMENTS (9)CHAPTER 2.Applicable Documents (10)2.1Specifications (10)2.2Other Documents (11)CHAPTER 3.Definitions and Acronyms (12)3.1Acronyms (12)3.2Terms and Definitions (13)CHAPTER 4.General (14)4.1Implementation. (14)4.2Changes in Requirements. (14)CHAPTER 5.Training Requirements (15)CHAPTER 6.FACILITY Operating Conditions (16)6.1Temperature and RELATIVE Humidity (RH) (16)6.2Occupational Health Requirements (16)CHAPTER 7.Electrostatic Discharge Control Standard Implementation (17)7.1Applicable ESD Standard (17)7.2ESD Requirements Addendum to ANSI/ESD S20.20 (17)CHAPTER 8.Polymeric Applications Standard Implementation (18)8.1Applicable Polymeric Applications Standard (18)8.2Exclusion of IPC J-STD-001ES Chapter 10 for Polymeric Applications (18)CHAPTER 9.Soldering Standard Implementation (19)9.1Applicable Soldering Standard (19)9.2Use of Cancelled NASA Workmanship Soldering Standards (19)9.3IPC J-STD-001ES Training Programs (19)CHAPTER 10.Cable Harness Assembly Standard Implementation (21)10.1Applicable Cable Harness Standard (21)10.2Use of IPC J-STD-001ES for Soldering (21)CHAPTER 11.Fiber Optic Cable Assembly Standard Implementation (22)11.1Applicable Fiber Optic Cable Standard (22)APPENDIX A Requirements for Workmanship Standards Training Programs (23)A.1General (23)A.2Workmanship Certified Personnel (23)A.3Responsibility for Personnel Certification (25)A.4Certification Records (27)A.5Minimum Certification Requirements for Operators, Inspectors, and PersonnelAssociated with Local ESD Control Programs (27)A.6Minimum Certification Requirements for Instructors (27)A.7Vision Requirements (28)A.8General Training Program Requirements for NASA Workmanship Standards (29)A.9Training Program Requirements, NASA Training Centers (32)A.10IPC® J-STD-001ES Training (33)A.11Courses (34)A.12Student Requirements (35)A.13Enrollment (36)A.14Applicability of Training (37)LIST OF TABLESTable 1:Workmanship Requirements Documents (8)Table A-1:Recommended Course Lengths (35)LIST OF FIGURESNoneIMPLEMENTATION REQUIREMENTSFOR NASA WORKMANSHIP STANDARDSCHAPTER 1. SCOPE1.1SCOPEThis publication sets forth quality requirements for the manufacture of electronic assemblies and for electrostatic discharge (ESD) control which augment requirements found in one or more of the documents listed in Table 1.Table 1: Workmanship Requirements Documents1.1.1Where there are conflicts between the requirements found in this document and NPD 8730.5, the requirements of NPD 8730.5 take precedence.1.1.2Where there are conflicts between the requirements found in this document and the documents in Table 1, the requirements of this document take precedence.1.2APPLICABILITY1.2.1This standard applies to NASA Centers, including component facilities, and to the Jet Propulsion Laboratory, other contractors, grant recipients, or parties to agreements to the extent specified or referenced in their contracts, grants, or agreements.1.2.2This standard applies to critical work, as defined by NPD 8730.5. Critical work is any task that if performed incorrectly or in violation of prescribed requirements poses a credible risk of loss of human life; serious injury; loss of a Class A, B, or C payload (see NPR 8705.4); loss of a Category 1 or Category 2 mission (see NPR 7120.5); or loss of a mission resource valued at greater than $2M (e.g., NASA space flight hardware, Government test or launch facility).1.2.3The workmanship requirements of this document do not apply to suppliers of commercial-off-the-shelf (COTS) items. Projects which use COTS hardware for applications described in1.2.2 above are responsible for identifying and managing risk associated with hardware that was built without material controls, production methods, and/or quality inspections defined by the workmanship standards.1.3SPECIAL REQUIREMENTS1.3.1Local workmanship requirements not contained in this publication or the standards referenced in Table 1 shall be formally documented (Requirement).1.3.2Local requirements which conflict with requirements stated herein or in the standards in Table 1 shall be formally approved per paragraph 1.4.1 below and traceable to approved requests for relief (Requirement).1.4RELIEF FROM REQUIREMENTS1.4.1The NASA program or project office is responsible for assuring that requests for relief from requirements in this publication are documented and adjudicated in accordance with NASA-STD-8709.20, Management of Safety and Mission Assurance Technical Authority (SMA TA) Requirements.CHAPTER 2. APPLICABLE DOCUMENTS2.1SPECIFICATIONSCopies of the following documents required in connection with a specific procurement may be obtained from the procuring NASA Center or as directed by the contracting officer. FEDERAL REGULATIONS:Occupational Safety and Health Administration, 29 C.F.R.Federal Acquisition Regulations (FAR), Quality Assurance, 48 C.F.R. pt. 46NASA DIRECTIVES (NPD)NPD 8730.2 NASA Parts PolicyNPD 8730.5 NASA Quality Assurance Program PolicyNASA PROCEDURAL REQUIREMENTS (NPR) DOCUMENTSNPR 1800.1 NASA Occupational Health Program ProceduresNPR 7120.5 NASA Space Flight Program and Project Management Requirements NPR 8705.4 Risk Classification for NASA PayloadsNASA STANDARDS:NASA-STD-8709.20 Management of Safety and Mission Assurance Technical Authority(SMA TA) Requirements.NASA-STD-8739.1 Workmanship Standard for Polymeric Applications on ElectronicAssemblies.NASA-STD-8739.2 Workmanship Standard for Surface Mount Technology.NASA-STD-8739.3 Soldered Electrical Connections.NASA-STD-8739.4 Crimping, Interconnecting Cables, Harnesses, and Wiring.NASA-STD-8739.5 Fiber Optic Terminations, Cable Assemblies, and Installation. NASA HANDBOOKS:NASA-HDBK-8739.21 Workmanship Manual for Electrostatic Discharge Control (ExcludingElectrically Initiated Explosive Devices)INDUSTRY SPECIFICATIONS:ANSI/ESD S20.20 Standard for the Development of an ESD Control Program for theProtection of Electrical and Electronic Parts, Assemblies, andEquipment (Excluding Electrically Initiated Explosive Devices). IPC J-STD-001 Requirements for Soldered Electrical and Electronic Assemblies IPC J-STD-001ES Space Applications Electronic Hardware Addendum to J-STD-001E SAE AS9100 Quality Management Systems: Requirements for Aviation, Space &Defense Organizations2.2OTHER DOCUMENTSIndustrial Ventilation Manual of Recommended Practices, American Conference of Governmental Industrial HygienistsCHAPTER 3. DEFINITIONS AND ACRONYMS3.1ACRONYMSANSI American National Standards InstituteAO-HRR American Optical Hardy-Rand-RittlerCD Compact DiscCFR Code of Federal RegulationsCIS Certified IPC® Application SpecialistCIT Certified IPC® TrainerCOTS Commercial Off The ShelfDCMA Defense Contract Management AgencyE-NMTTC Eastern NASA Manufacturing Technology Transfer CenterESD Electrostatic DischargeFAR Federal Acquisition RegulationsGSFC Goddard Space Flight CenterHBM Human Body ModelHQ OSMA NASA Headquarters, Office of Safety and Mission AssuranceIPC®Registered trademark for IPC-Association Connecting ElectronicIndustriesJPL Jet Propulsion LaboratoryJSC NASA Johnson Space CenterNPD NASA Policy DirectiveNPR NASA Procedural RequirementsMIT Certified IPC® Master TrainerMSFC NASA Marshall Space Flight CenterOSHA Occupational Safety and Health AdministrationSAE Society of Automotive EngineersSATERN System for Administration, Training, and Educational Resources forNASASMA Safety and Mission AssuranceSTD StandardTA Technical AuthorityTAA Technical Assistance AgreementW-NMTTC Western NASA Manufacturing Technology Transfer Center3.2TERMS AND DEFINITIONSThe below listed definitions are in addition to those listed in NASA-STD 8709.22, Safety and Mission Assurance Acronyms, Abbreviations, and Definitions.NASA Level A Instructor Instructor certified to teach one or more of NASA-STD-8739.1,NASA-STD-8739.2, NASA-STD-8739.3, NASA-STD-8739.4, orNASA-STD-8739.5 courses to operators, inspectors, and Level Binstructors (See A.2.1.g). The local ESD Control Plan may choose todefine and use a NASA Level A Instructor classification in its trainingsection.Level B Instructor Instructor certified to teach one or more of NASA-STD-8739.1, NASA-STD-8739.2, NASA-STD-8739.3, NASA-STD-8739.4, or NASA-STD-8739.5 courses to operators and inspectors. (See A.2.1.d). The localESD Control Plan may choose to define and use a Level B Instructorclassification in its training section.Mission Hardware Hardware used in Category 1 and Category 2 projects and/or Class A,B, or C payloads.NASA Level A Training CenterThe Eastern NASA Manufacturing Technology Transfer Center atNASA Goddard Space Flight Center and the Western NASAManufacturing Technology Transfer Center at Jet PropulsionLaboratory.NASA Workmanship Standards Technical CommitteeNASA civil service employees who are the primary points of contactfor the NASA Workmanship Standards Program for each NASACenter. See /workmanship for the current roster.CHAPTER 4. GENERAL4.1IMPLEMENTATION.NASA quality assurance and/or engineering personnel are responsible for providingprogram/project support by advising, assisting, and managing suppliers, NASA personnel, and delegated agencies in the proper and effective implementation of the provisions of this publication.4.2CHANGES IN REQUIREMENTS.When changes are made to the requirements herein, NASA quality assurance and/or engineering personnel are responsible for providing program/project support by assuring that the new requirements are flowed to program/project mission assurance plans, prime contracts, and subcontracts, and for providing this information to delegated agents serving as inspectors in supplier manufacturing facilities.CHAPTER 5. TRAINING REQUIREMENTSThis section supersedes the requirements of Section 5 of NASA Standards 8739.1, 8739.4, and 8739.5.5.1 PERSONNEL TRAINING/CERTIFICATIONPersonnel performing manufacturing processes and inspections prescribed in workmanship standards listed in Table 1 shall be trained and certified in accordance with Appendix A (Requirement).5.2 PROGRAM IMPLEMENTATIONWorkmanship training and certification programs shall be implemented in accordance with Appendix A of this standard (Requirement).CHAPTER 6. FACILITY OPERATING CONDITIONSThis section establishes requirements for work environment conditions for workmanship processes applied to NASA mission hardware. This section supersedes the requirements of NASA-STD-8739.1, Section 6.3.1.2; NASA-STD-8739.4, Section 6.2.1; and the last sentence of NASA-STD-8739.5, Section 6.2.1. This section establishes requirements which augment or modify the requirements of IPC J-STD-001ES and ANSI/ESD S20.20.6.1TEMPERATURE AND RELATIVE HUMIDITY (RH)6.1.1Temperature and relative humidity (RH) shall be monitored in the processing area and maintained within the following limits (Requirement):a. For temperature: 18° - 30° C (65° - 85° F).b. Maximum relative humidity: 70 percent RHc. For ESD-sensitive hardware, minimum humidity: 30 percent RH.d. For ESD-sensitive hardware, HBM Class 0, minimum humidity: 40 percent RH.6.1.2 For instances where maintaining an RH level shown in c. or d. above is not practical, special methods, procedures, equipment, and assurance requirements designed to overcome the risks of relative humidity levels below 30% RH shall be used and documented in the applicable ESD Control Program Plan.6.2OCCUPATIONAL HEALTH REQUIREMENTSRelated occupational health requirements for protection and assessment of individuals exposed to lead (Pb) containing solders can be found in NPR 1800.1 and OSHA regulations (29 CFR 1910.1025). See also NPD 8730.2, Appendix A, paragraph d, NOTE.CHAPTER 7. ELECTROSTATIC DISCHARGE CONTROLSTANDARD IMPLEMENTATION7.1APPLICABLE ESD STANDARDANSI/ESD S20.20 contains baseline ESD control requirements for mission hardware.7.2ESD REQUIREMENTS ADDENDUM TO ANSI/ESD S20.207.2.1See paragraph 6.1.2 of this standard for relative humidity requirements.7.2.2 ANSI/ESD S20.20 requires the development and implementation of an ESD Control Program which provides detailed requirements and acceptance levels applicable to local production facilities. A recommended ESD Control Program plan template is provided in NASA-HDBK-8739.21.7.2.3ESD wrist straps and heel strap systems shall be verified to be functional each time they are put on prior to entry into an Electrostatic Protected Area (EPA) or prior to coming within one meter of an ESD sensitive item (Requirement).CHAPTER 8. POLYMERIC APPLICATIONS STANDARDIMPLEMENTATION8.1APPLICABLE POLYMERIC APPLICATIONS STANDARDNASA-STD-8739.1 contains baseline staking, bonding, conformal coating, and encapsulation requirements for mission hardware. This section defines requirements which are applicable to, and in addition to, those found in the baseline document.8.2EXCLUSION OF IPC J-STD-001ES CHAPTER 10 FOR POLYMERICAPPLICATIONSChapter 10 of IPC J-STD-001ES shall not be used without waiver approval (Requirement).CHAPTER 9. SOLDERING STANDARD IMPLEMENTATION9.1APPLICABLE SOLDERING STANDARD9.1.1J-STD-001ES contains baseline soldering requirements for mission hardware. This section defines requirements which are applicable to and/or in addition to those found in the baseline document.Note: J-STD-001, Class 3 is not an authorized substitute for the most recent revision of IPC J-STD-001ES.9.2USE OF CANCELLED NASA WORKMANSHIP SOLDERING STANDARDS9.2.1NASA-STD-8739.2 and NASA-STD-8739.3 are cancelled documents as of October 2011. Use of these standards without waiver is allowed for programs and projects that have assurance baseline documents which were published prior to their cancellation. Programs and projects shall obtain waiver approval prior to using cancelled standards in their baseline requirements (Requirement).9.2.2Programs and projects that have invoked NASA-STD-8739.2 and NASA-STD-8739.3 in their baseline requirements prior to October 2011 may use IPC J-STD-001ES for soldering new mission hardware without waiver approval. Inspectors trained to J-STD-001ES may inspect hardware built to cancelled NASA soldering standards in accordance with the accept/reject criteria of the cancelled standard, however, when an artifact is identified that is considered a defect in accordance with IPC J-STD-001ES criteria, authorized technical experts and contract authorities shall disposition the defect (e.g., use or repair) based on mission risk. Programs and projects that are building, replacing, modifying, or repairing equipment defined by drawings which invoke the cancelled NASA soldering standards may work to the requirements and training certifications of IPC J-STD-001ES without waiver.9.3IPC J-STD-001ES TRAINING PROGRAMSThree training program approaches, as described below, are available and recognized as valid for students seeking operator and inspector training to IPC J-STD-001ES. Suppliers are responsible for determining how they meet the training requirement for operators and inspectors, whether through IPC® course offerings or through a locally developed training program. See Appendix A, sections A.2 through A.6 for NASA workmanship certification requirements.9.3.1IPC® Modular IPC J-STD-001ES Training: The IPC® offers a six-module IPC J-STD-001ES course which is recognized as valid for meeting the NASA workmanship training requirement for IPC J-STD-001ES. The IPC® may be contacted to obtain information concerning certified suppliers of this training and for registration instructions. Certification to IPC J-STD-001ES under IPC training policy is constrained to the specific modules or combination of modules completed. This constraint is noted on the IPC certificate. As a minimum, Module 1, Module 6, and one other Module (either 2, 3, 4, or 5) shall be taken to meet the minimum IPC J-STD-001ES training requirement (Requirement). Students who take the modular course are instructed in all quality class levels including the space class.9.3.2IPC® Non-Modular IPC J-STD-001ES Training: The IPC® offers a non-modular course in which students are instructed only in the space quality class. This non-modular IPC J-STD-001ES class is considered valid for meeting the workmanship training requirement for IPC J-STD-001ES. This non-modular course does not provide training for IPC J-STD-001 quality Class 1, 2, and parts of Class 3 and therefore may not be acceptable for contracts which require IPC J-STD-001 Class 1, IPC J-STD-001 Class 2, or IPC J-STD-001 Class 3 IPC® CIS certification (these contracts would not be those applicable to NASA mission hardware).9.3.3Custom IPC J-STD-001ES Training: The supplier has the option to create a training program for IPC J-STD-001ES which meets the requirements of Appendix A, with the condition that only IPC® certified trainers (IPC® CIT or IPC® MIT) act as the instructor.9.3.3.1 Custom training program curriculum and materials which are developed solely by the supplier and used by Level B instructors, IPC® CITs, and IPC® MITs at supplier facilities shall be made available to NASA programs and projects for review and approval upon request (Requirement).9.3.3.2 Custom computer-based courses shall not be used for IPC® J-STD-001ES initial training (Requirement).9.3.3.3 For custom IPC® J-STD-001ES retraining courses, computer-based training is allowed, but shall be combined with practical exercises and exams which are administered and evaluated by an IPC® CIT or IPC® MIT (Requirement).CHAPTER 10. CABLE HARNESS ASSEMBLY STANDARDIMPLEMENTATION10.1APPLICABLE CABLE HARNESS STANDARDNASA-STD-8739.4 contains baseline requirements for electrical cable and cable harness assembly for mission hardware.10.2 USE OF IPC J-STD-001ES FOR SOLDERINGWhere NASA-STD-8739.4 invokes NASA-STD-8739.3 for soldering processes and inspections, IPC J-STD-001ES may be used without waiver approval.CHAPTER 11. FIBER OPTIC CABLE ASSEMBLY STANDARDIMPLEMENTATION11.1APPLICABLE FIBER OPTIC CABLE STANDARDNASA-STD-8739.5 contains baseline requirements for fiber optic cable assembly for mission hardware. This standard does not contain any changes to the baseline requirements.APPENDIX A REQUIREMENTS FOR WORKMANSHIP STANDARDS TRAINING PROGRAMSA.1 GeneralA.1.1 This section:a. Establishes the training and certification requirements for workmanship operators, inspectors, and instructors.b. Establishes training requirements for NASA-STD-8739.1, NASA-STD-8739.2, NASA-STD-8739.3, NASA-STD-8739.4, NASA-STD-8739.5, IPC J-STD-001ES and ANSI/ESD S20.20.c. Establishes requirements for ensuring that successful completion of the courses by workmanship operators, inspectors, and instructors results in a common knowledge baseline among those personnel, and that common and predictable student processing practices are applied.A.1.2 NASA Level A training centers have been designated at NASA Goddard Space Flight Center (GSFC) and the Jet Propulsion Laboratory (JPL) for the purposes of providing master training sites for the dissemination of training for all levels of NASA workmanship students, including Level B instructors. Terms and requirements included in this document for NASA Level A training centers do not apply to courses designed for GSFC or JPL internal use. See /workmanship for NASA Level A training center contact information.A.1.3 NASA Center Safety and Mission Assurance (SMA) organizations may sponsor and manage local Level B instructors for the purpose of providing greater access to training by operators and inspectors with lower associated travel costs.A.2 Workmanship Certified PersonnelA.2.1 The following personnel shall be certified in workmanship standards (Requirement):a. Operator: Builds and inspects printed wiring assemblies, cables, and cable harnesses (electrical). For soldering per J-STD-001ES, the terminology for an IPC-trained operator is Certified IPC® Application Specialist (CIS).b. Inspector: Inspects printed wiring assemblies, cables, and cable harnesses (electrical) for defects in accordance with workmanship standard requirements. For interconnections which are soldered per J-STD-001ES, the terminology for an IPC-trained inspector is CIS-inspector.c. ESD operator and ESD program monitor: Handles ESD sensitive hardware or performs special duties relative to ESD controlled area certification. The local ESD control implementation plan may define alternative names for these roles.d. Level B instructor: Trains operators and inspectors to NASA workmanship standards; NASA-STD 8739.1, NASA-STD 8739.2, NASA-STD 8739.3, NASA-STD 8739.4, and/orNASA-STD 8739.5. Suppliers and NASA Centers may choose to use a Level B instructor designation for ESD training (see Table A-1 Note).e. ESD Instructor: Instructs ESD operators, ESD program monitors, and local instructors to the local ESD control implementation plan traceable to ANSI/ESD S20.20 and as defined in the plant-local ESD Control Program. The local ESD Control Program defines the minimum qualifications required for ESD instructors and any hierarchies that apply to instructors and students they teach.f. Certified IPC® Trainer (CIT): Trains CIS operators and inspectors inside or outside of their own company.g. NASA Level A Instructor (on behalf of a NASA Level A training center): Trains operators, inspectors, and Level B instructors inside and outside of their own company to NASA-STD-8739.1, NASA-STD-8739.2, NASA-STD-8739.3, NASA-STD-8739.4, and NASA-STD-8739.5. Suppliers and NASA Centers are permitted to use a NASA Level A instructor designation for ESD training (see Table A-1 Note).h. Certified Master IPC® Trainer (MIT): Trains CISs and CITs inside or outside of their own company.A.2.2 Level B instructors sponsored by, or working on behalf of, a NASA Center SMA organization may train operators and inspectors inside and outside of their own company as well as U.S. government civil service personnel (NASA and Non-NASA).A.2.3 Level B instructors employed in a Level B Supplier Training Program:a. May train o perators and inspectors who are employed by the instructor’s company or operators and inspectors who work for companies contracted to their company (e.g., subcontract to NASA).b. May not train students from organizations to which the instructors’ organization delivers mission hardware and/or that have contractual oversight authority.A.2.4 Training of personnel to NASA workmanship standards and IPC® standards is specific to the student type (e.g., operator, inspector, instructor, CIS-operator, CIS-inspector only). Individuals who desire dual certification as an operator and an inspector for the NASA workmanship standards shall make special arrangements with their instructor to take a training program(s) that result in dual certification (Requirement).A.2.5 CIS training using the IPC J-STD-001ES non-modular course results in dualoperator/inspector training except if inspector-only training is requested.A.2.6 Personnel who are trained to the instructor level (NASA Standard, or IPC standards) meet the training prerequisite for operator and inspector certification.Certifying authorities are responsible for ensuring that personnel who perform more than one role (e.g. instructor and inspector) are competent to perform all work assignments.A.2.7 Certified workmanship personnel shall not inspect their own work (Requirement).A.2.8 Where training is performed using primarily computer-based material without the presence of an instructor (e.g., on-line, SATERN, CD-based), the requirements described herein relative to the certification and responsibilities of trainers do not apply. See paragraphs 9.3.5 and A.8.23 through A.8.25 for limitations on the use of computer-based training.A.3 Responsibility for Personnel CertificationA.3.1 Suppliers who are required to comply with one or more of the workmanship standards in Table 1 are responsible for ensuring that all operators and inspectors in their company who manufacture NASA mission hardware are capable of performing their tasks in a way that results in compliant product. Suppliers who employ Level B instructors are responsible for ensuring that the Level B instructors have a sufficient mastery of the course content they teach, have the appropriate teaching skills to properly instruct students, and have sufficient ability to assess their students’ mastery of the subject matter. Evidence that operators, inspectors, and instructors are able to meet workmanship requirements is required in the form of a supplier certification (except NASA Level A instructors, see paragraph A.3.8, and Level B instructors who work on behalf of Center SMA organizations, see paragraph A.3.6).A.3.2 Certification criteria in addition to that specified in this document may be applied at the supplier’s discretion. Pers onnel who no longer meet one or more of the minimum criteria for certification shall have their certification revoked (Requirement). Recertification shall be performed every two years and is typically timed to coincide with completion of retraining (Requirement).A.3.3 The supplier shall assign an expiration date for Workmanship certification that is not longer than twenty-four months after the certification date. (Requirement).A.3.4 The supplier shall apply local policies for reinstating the certification of operators who fail to meet the minimum requirements for competency and work period interruption (Requirement). Local policies may employ retraining and other methods (e.g., mentoring) to ensure that inactive or ineffective personnel can demonstrate the required competency and knowledge of the requirements.A.3.5 Local policies for managing personnel certification shall be documented and maintained under configuration change control (Requirement) and shall include as a minimum:a. Procedures for certification and recertification.b. Procedures for recording certification, recertification, and the method of identifying/recalling certified personnel.A.3.6 The certifying authority for Level B instructors who teach on behalf of a NASA Center’s SMA organization shall be the Center’s representative on the NASA Workmanship Standards Technical Committee (Requirement). The Center’s representative on the NASA Workmanship Standards Technical Committee may delegate this responsibility. See/workmanship for the current roster.A.3.7 Suppliers who are required to comply with IPC J-STD-001ES are responsible for ensuring that all CITs and MITs used by their organization to train CISs carry valid IPC® certifications. Additional certification criteria may be imposed by th e supplier at the supplier’s discretion.A.3.8 The NASA Workmanship Standards Program Manager is responsible for certifying NASA Level A Instructors who teach operator, inspector, and Level B instructor courses for NASA-STD-8739.1, NASA-STD-8739.2, NASA-STD-8739.3, NASA-STD-8739.4, and NASA-STD-8739.5. Responsibility for the certification of Western NASA Manufacturing Technology Transfer Center (W-NMTTC) NASA Level A instructors may be delegated by the NASA Workmanship Standards Program Manager to JPL’s represen tative on the NASA Workmanship Standards Technical Committee. The JPL representative on the NASA Workmanship Standards Technical Committee may delegate this responsibility.A.3.9 Portability of Workmanship TrainingA.3.9.1 NASA workmanship standards training, except ESD training, obtained from a NASA Level A or Level B trainer is transferable and valid for work performed at all NASA supplier facilities.A.3.9.2 When using IPC training courses for J-STD-001ES training, it is the supplier’s decision whether to use the modular or the non-modular course. Either is considered acceptable for meeting NASA quality assurance requirements that specify J-STD-001ES, with the following exception: Since the non-modular course is not considered equivalent to the modular course (the former is a subset of the latter) it does not satisfy contracts invoking IPC J-STD-001E Class 1, Class 2, or Class 3.A.3.9.3 IPC J-STD-001ES training, using either the IPC modular course or the non-modular course, shall be treated as portable between suppliers (Requirement).A.3.9.4 Supplier custom-developed IPC J-STD-001ES training shall not be treated as portable between suppliers (Requirement).A.3.9.5 Early retraining after change of employment may be required if the prior training did not include the full requirements set (i.e. partial training, See A.8.10).A.3.10 Portability of NASA Workmanship Certification.A.3.10.1 NASA workmanship certification is not portable between suppliers for operators, inspectors, non-IPC® instructors, and ESD program monitors. NASA workmanship certifications for these personnel shall be revoked when employment is terminated (Requirement).A.3.10.2 A change of employer requires the new employer to recertify the newly hired individual.A.3.10.3 Employers who are the workmanship certifying authority for operators, inspectors, and Level B instructors may send new employees to retraining.。
[RBCC变循环火箭冲压发动机燃烧室直连式试验台]Status of the RBCC Direct-Connect Mixer Combustor Experi
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Available from NASA Center for Aerospace Information 7121 Standard Drive Hanover, MD 21076 National Technical Information Service 5285 Port Royal Road Springfield, VA 22100
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NASA/TM—2002-211555
Status of the RBCC Direct-Connect Mixer Combustor Experiment
James F. Walker, Hani Kamhawi, Thomas M. Krivanek, Scott R. Thomas, and Timothy D. Smith Glenn Research Center, Cleveland, Ohio
May 2002
The NASA STI Program Office . . . in Profile Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) Program Office plays a key part in helping NASA maintain this important role. The NASA STI Program Office is operated by Langley Research Center, the Lead Center for NASA’s scientific and technical information. The NASA STI Program Office provides access to the NASA STI Database, the largest collection of aeronautical and space science STI in the world. The Program Office is also NASA’s institutional mechanism for disseminating the results of its research and development activities. These results are published by NASA in the NASA STI Report Series, which includes the following report types: • TECHNICAL PUBLICATION. Reports of completed research or a major significant phase of research that present the results of NASA programs and include extensive data or theoretical analysis. Includes compilations of significant scientific and technical data and information deemed to be of continuing reference value. NASA’s counterpart of peerreviewed formal professional papers but has less stringent limitations on manuscript length and extent of graphic presentations. TECHNICAL MEMORANDUM. Scientific and technical findings that are preliminary or of specialized interest, e.g., quick release reports, working papers, and bibliographies that contain minimal annotation. Does not contain extensive analysis. CONTRACTOR REPORT. Scientific and technical findings by NASA-sponsored contractors and grantees. • CONFERENCE PUBLICATION. Collected papers from scientific and technical conferences, symposia, seminars, or other meetings sponsored or cosponsored by NASA. SPECIAL PUBLICATION. Scientific, technical, or historical information from NASA programs, projects, and missions, often concerned with subjects having substantial public interest. TECHNICAL TRANSLATION. Englishlanguage translations of foreign scientific and technical material pertinent to NASA’s mission.
NASA空间日工具包指南说明书
Credit: NASA Fighting the Force (of Gravity)Lesson Reference: Space Day Toolkit at and a NASA Rotor Motorlesson Objectives:•Students will identify the four forces affecting an aircraft’s flight.•Students will explain how rotor movement is responsible for creating the liftneeded to overcome gravity.•Students will construct a rotary wing model.•Students will understand that increased lift is required for flight if the weight ofan aircraft increases.•Students will experiment to show that both rotor speed and blade angle will affecta helicopter’s lift.National Standards: Math•Number and Operationso Work flexibly with fractions, decimals, andpercents to solve problems•Communicationo Organize and consolidate mathematical thinkingthrough communication•Connectionso Understand how mathematical ideas interconnect and build on one another toproduce a coherent wholeo Recognize and apply mathematics in contexts outside of mathematics•Representationo Create and use representations to organize, record, and communicatemathematical ideasScience•Unifying Concepts and Processeso Evidence, models, and explanationo Change, constancy, and measuremento Form and function•Content Standard A: Science as Inquiryo Abilities necessary to do scientific inquiryo Understandings about scientific inquiry•Content Standard B: Physical Scienceo Motions and forceso Transfer of energyCredit: NASA •Content Standard E: Science and Technology o Abilities of technological design o Understandings about science and technology •Content Standard F: Science in Personal and Social Perspectives o Science and technology in society •Content Standard G: History and Nature of Scienceo Science as a human endeavoro Nature of science ISTE NETS Technology Standards•Creativity and Innovationo Use models and simulations to explore complex systems and issues•Communication and Collaborationo Develop an understanding of engineering design•Critical Thinking, Problem Solving, and Decision MakingBackground Information: (from Space Day Tookit and NASA Main Rotor Motor lesson )Can you guess how long helicopters have been around? For a long, long time! As far back as 1486, Leonardo da Vinci designed a very simple helicopter. Some scholars say his wasn’t the first; around AD 320 in China, Ko Hung described a “Chinese Flying Top.” Today, his design is thought to be the earliest known example of a helicopter. Now we know that four important forces (push or pull affecting an object’s movement) influence a helicopter’s flight. So, what are they? Just keep reading!What forces affect a helicopter’s flight? Lift: Force pushing up on a helicopter, caused by horizontal rotor and blades . Lift is produced by the pressure differences caused by the shape of rotating blades; this is the same way lift is produced by aircraft wings. The rapidly moving air over the top of the blade creates low pressure; the air beneath the blade is moving slower, so it creates higher pressure. Highpressure under the rotor blades creates lift which causes the aircraft to rise. Since the paper models have no motor, they only have one source of lift. As the paper models fall, they will spin, imitating the rotation of the rotor blades of a helicopter. Because there is no thrust to produce upward movement, the helicopter will not fly upward, but the spin will reduce the rate of fall by producing lift, resisting the force of gravity.Weight: Force working against lift; caused by gravity’s downward pull on helicopter; affected by kind and amount of material presentSource: NASAThrust: Force pushing a helicopter forward through the air, caused by tail rotor and bladesDrag: Force working against thrust ; caused when air molecules hit surface of helicopter, slowing it downWhat are the differences in the way helicopters and airplanes fly?Helicopters: •Gain lift as moving air passes over horizontal rotor •Gain thrust as air moves over vertical (tail) rotor blades •Can hover (stay in one place) and rise and land vertically (up and down)•Can take off and land in tight spaces •Fly at slow speeds, compared with airplanes •Unstable by nature; require constant pilot monitoring; can’t easily correct course Airplanes: •Gain lift as moving air passes over fixed wings or propellers •Receive thrust from jet engines, rockets, or propellers•In most case s, can’t hover or rise and land vertically •Cannot take off and land in restricted spaces •Fly at high speeds, compared with helicopters •Stable by nature; do not require constant pilot monitoring; often correct course themselves As mentioned, a helicopter uses lift to overcome gravity , which acts on a helicopter’s weight by constantly pulling it downward. To create lift , a helicopter uses a horizontal rotor and attached rotor blades (usually two). Because of a helicopter’s unique properties (see above), it is used in a variety of situations: search and rescue, firefighting, law enforcement, and medical evacuation, to name a few. One important consideration for engineers designing new helicopters is to examine the effect of weight on a helicopter’s performance. The rotor must be able to create enough lift to overcome the downward pull of gravity on the combined weight of the cargo and helicopter.Materials:•Plastic toy helicopter or model helicopter (optional)•Copies of Rotor Diagram (3 copies per student)•Scissors•Measuring tape•Small paper clips•Stopwatches•Calculators• 3 meters of lightweight crepe paper or cassette/video tape rib bon•Scotch tape•Data Collection FormAdvance Teacher Preparation:Make copies of the rotor template so that each student can construct a helicopter. Also, obtain old audio or videotape cassettes. You will need to open them to access the tape inside that will be used for the activity. The students will enjoy seeing where the tape came from, especially since both of these mediums have been replaced by CDs, DVDs, and Blu-Rays. (Or, rolls of crepe paper is good to use, if video tape is not available.)Lesson Presentation:1.Engage the students by demonstrating the flying of a plastic toy helicopteror a remote-control helicopter. (If one of these items is not available, show students a picture of a helicopter.)Ask the students how a helicopter is like an airplane.2.Discuss that the helicopter experiences four forces of flight, with gravity beingthe most difficult to overcome. (If students are unfamiliar with the forces of flight, explain, as needed, using the background information.) Provide specific details about how a helicopter achieves lift (refer to the background information). rm the students that they are going to be acting as engineers designing a newhelicopter. The students will need to run a series of tests to see if cargo placement inside a helicopter affects the r otor’s ability to create lift, if increased weight will affect the rotor’s ability to lift the helicopter, and the difference in the number of blade rotations with increased weight and placement of cargo.4.In order to perform the necessary experiments, tell the students that they willneed to build a helicopter. Pass out the Data Collection Form and the Rotor Motor template, and make sure that each student has scissors.5.Have the students build the helicopter.a.)Cut along the solid lines of the template.b.) F old on dotted lines.The h elicopter blades should be folded in oppositedirections.Panel X and Y fold to the center,and Panel Z will be folded up to help make the body more sturdy and lower the center of gravity.c.) Repeat the steps so that each student has 3 helicopters.6.Allow the students to begin the experiment as a class.Make sure that all of the students have Wing A benttowards the outside and Wing B bent towards the body(or fuselage) of the helicopter. Also, have the studentsturn the helicopter sideways and make sure that theshape of the fuselage and the wings looks like a “Y.” Ifnot, instruct the students to fluff the wings up so thatthe wings are at an angle forming what is called a dihedral wing. This is called the angle of incidence.7.Model for the students how to release the helicopter by dropping it straight down;not tossing it. Tell the students to stand and drop the helicopter while making observations. Repeat this as a class and have the students record the direction that the helicopter is rotating, clockwise or counterclockwise, on the Data Collection Form.8.Ask the students to switch the blades of the helicopter by flipping the Wing Atowards the fuselage and Wing B away from it. Remind them to fluff the wings once more before dropping. Have them predict as a class how the flight will change.Have them drop the helicopter and record their observations, specifically noting whether or not the helicopter is rotating clockwise or counterclockwise. Discuss why this is happening with the students (air flow and the position of the blades). 9.Ask the students if they can accurately count the number of rotations that thehelicopter made as it descended. (This is not possible as it is going very quickly, which would make accurate counting difficult.)10.Brainstorm with the students ideasas to how they could accuratelycount the number of rotations.After some discussion, show themthe cassette/video (or crepe paper)ribbon.To determine the number ofrotations,inform the students thatthey need to tape the cassette (orother) ribbon to the bottom of thefuselage. Before they drop th eirhelicopter, they need to stand on Source: NASAthe loose end of the tape.Make sure that when the students hold thehelicopter at arm’s height to the ground, there are no twists in the ribbon. Then, when they drop the helicopter as usual, the ribbon will twist, which will count the number of rotations. Each twist in the ribbon represents one rotation of thehelicopter. When you count the number of twists, it will be the total number of rotations. It is important to demonstrate this because the students will be using this technique on the Data Collection Form. (see form)11.After testing the helicopter as a class, direct the students’ attention to the DataCollection Form, as they will be providing answers on this form.In Part 1 on the Data Collection Form, tell the students that they will be recording the affect of increased weight on lift and rotation of the blades.They will start by recording the lift time (how long it stays in the air) and rotation with no added weight (no paper clips) by running three trials and calculating the average lift time. This test will be repeated, but the weight will be changed by adding one paper clip to the bottom of the fuselage (demonstrate how to attach the paper clip) and conducting three trials for an average. Finally, add additional weight by attaching a second paper clip to the bottom. Again, perform three trials, record the times, and calculate the average lift time.In Part 2, inform the students that they will be deciding if the location of the weight (paper clips) affects the lift time and rotation. An example would be if the paper clip was positioned near the top of the rotor or on the blades and how it would affect the flight of the helicopter. On each of the three diagrams provided, make sure to show the location of the paper clips.*Tell the students to answer the questions on the Data Collection Form concerning the experiment.12.Allow the students to begin the experiment and move at their own individual pace.(You may allow students to work with a partner.) Make sure to circulate during the activity in case of any questions or to provide support if needed. Summarization:Discuss the experiment results with the class making sure to emphasize that the two forces being studied in this experiment were lift and gravity. Based on the data collected, the students should conclude that the effect of gravity increased when extra weight was added, as well as the number of rotations. This should be evident in the data by the lift time decreasing when more paper clips were added and the number of rotations getting greater. The discussion on how lift was affected regarding the placement of the paper clips will vary depending on where the students chose to place the weight. Again, the conclusion that the students draw should match the data that was collected. Finally, discuss the reason that it is difficult and, even in some instances, impossible to take a helicopter in for a high-altitude rescue. (There would not be enough air molecules under the rotor blades to lift the helicopter safely.)Career Connection: (from STEM Careers and Career Exploration at O-Net Online) Aerospace Engineer – engineering duties to include designing, constructing and testing aircraft, missiles, and spacecraft. Sample job titles include Aerospace Engineer, Flight Test Engineer, Design Engineer, Systems Engineer, Structures Engineer, Test Engineer, Aeronautical Engineer, Aerospace Stress Engineer, Avionics Engineer, and Flight Systems Test Engineer.Helicopter Mechanic – diagnose, adjust, repair or overhaul aircraft engines and assemblies, such as hydraulic and pneumatic systems. Sample job titles include Aircraft Mechanic, Aircraft Maintenance Technician, Aircraft Technician, Aircraft Maintenance Director, Aircraft Maintenance Supervisor, Aircraft Restorer, Aviation Maintenance Technician, and Helicopter Mechanic.Helicopter Pilot – pilot and navigate the flight of rotary wing aircraft,usually for the transport of passengers and cargo. Must have pilot certificate and rating for aircraft type used. Sample job titles include Airline Captain, First Officer, Pilot, Airline Pilot, Check Airman, Co-Pilot, Airline Transport Pilot, and Commuter Pilot.Evaluation:•Data Collection Form (especially the questions describing the relationship between the number of twists and the weight and placement of cargo)•Teacher observationLesson Enrichment/Extension:•Have students run additional trials to see if the blade angleaffects lift by changing the angle (angle of incidence) of thetwo folded blades. Ask them to create a chart to collect data.•Experiment with different weights of paper for the helicopterand graph the results.•Have the students formulate an experiment to explore therelationship of height to number of rotations.•Compare the flight of the paper helicopter to that of a mapleseed or dandelion.•Construct a bar or line graph to illustrate data collected onthe charts.•Have the students create helicopters of differing size s and compare the results.Associated Websites:•“Helicopter Development in the Early Twentieth Century,” U.S. Centennial of Flight Commission•“What is Gravity,” NASA•Rescue Mission Game- Rockface•NASA: Mars Helicopter Inguenity AnimationsSource: Vincent Madarieta WordpressSource: NASA Rotor MotorObservations from first flight (please include if the rotation is clockwise or counterclockwise):_____________________________________________________ _____________________________________________________ _____________________________________________________Observations after switching the rotor blades (please include if the rotation is clockwise or counterclockwise):_____________________________________________________ _____________________________________________________ _____________________________________________________1:Weight Location 2:Weight Location 3:Follow-up QuestionsWhat two forces were being studied in this activity?______________________________________________________________ ______________________________________________________________ ______________________________________________________________ Based on your data, was the effect of gravity increased when extra weight was added? What was your evidence?______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________How was the number of rotations affected? Why do you think this happened?______________________________________________________________ ______________________________________________________________ ______________________________________________________________ Based on your evidence, was lift affected by the location of the paper clips? What was your evidence?______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ Did the placement of the paperclips affect the number of rotations? Explain.______________________________________________________________ ______________________________________________________________ ______________________________________________________________High altitude rescue is often hard, and sometimes impossible for a helicopter to perform. How could this difficulty be related to the force of lift? Hint: The number of air molecules decreases at elevations above sea level (higher altitudes). ______________________________________________________________ ______________________________________________________________ ______________________________________________________________。
NASA POWER API客户端用户指南说明书
Package‘nasapower’December5,2023Type PackageTitle NASA POWER API ClientVersion4.1.0URL https:///nasapower/BugReports https:///ropensci/nasapower/issuesDescription An API client for NASA POWER global meteorology,surface solar energy and climatology data API.POWER(Prediction Of Worldwide EnergyResources)data are freely available for download with varying spatialresolutions dependent on the original data and with several temporalresolutions depending on the POWER parameter and community.This work isfunded through the NASA Earth Science Directorate Applied Science Program.For more on the data themselves,the methodologies used in creating,a web-based data viewer and web access,please see<https:///>. Depends R(>=3.5.0)License MIT+file LICENSEImports cli,crul,lubridate,jsonlite,readr,rlang,tibble(>=3.0.2)RoxygenNote7.2.3Encoding UTF-8Language en-USNeedsCompilation noRepository CRANSuggests knitr,purrr,rmarkdown,spelling,testthat(>=3.0.0),vcr(>=0.6.0)VignetteBuilder knitr-applicationCategory Tools-keywords NASA,meteorological-data,weather,global,weather,weather-data,meteorology,NASA-POWER,agroclimatology,earth-science,data-access,climate-data-isPartOf https://1Config/testthat/edition3Config/testthat/parallel trueAuthor Adam H.Sparks[aut,cre](<https:///0000-0002-0061-8359>), Scott Chamberlain[rev](<https:///0000-0003-1444-9135>,ScottChamberlain reviewed nasapower for rOpenSci,see<https:///ropensci/software-review/issues/155>.),Hazel Kavili[rev](Hazel Kavili reviewed nasapower for rOpenSci,see<https:///ropensci/software-review/issues/155>.),Alison Boyer[rev](Alison Boyer reviewed nasapower for rOpenSci,see<https:///ropensci/software-review/issues/155>.),Fernando Miguez[ctb](<https:///0000-0002-4627-8329>,Fernando Miguez provided assistance in identifying improper missingvalue handling in the POWER data,see<https:///femiguez/apsimx/pull/26>.),Maëlle Salmon[ctb](<https:///0000-0002-2815-0399>,MaëlleSalmon contributed a patch tofix issues with using the R package,'vcr',for testing the API queries,see<https:///ropensci/nasapower/pull/64>.),Phillip D.Alderman[ctb](<https:///0000-0003-1467-2337>,Phillip Alderman contributed a patch tofix an issue with,'The`file`argument of`vroom()`must use`I()`for literal data as ofvroom1.5.0.',see<https:///ropensci/nasapower/pull/67>.),Western Australia Agriculture Authority(W AAA)[cph](Supported thedevelopment of'nasapower'through Adam H.Sparks'time.)Maintainer Adam H.Sparks<*********************>Date/Publication2023-12-0512:40:02UTCR topics documented:get_power (2)query_parameters (6)Index9 get_power Get NASA POWER Data From the POWER APIDescriptionGet POWER global meteorology and surface solar energy climatology data and return a tidy data frame tibble::tibble()object.All options offered by the official POWER API are supported.Requests are formed to submit one request per point.There is no need to make synchronous requests for multiple parameters for a single point or regional request.See section on“Rate Limiting”for more.Usageget_power(community=c("ag","re","sb"),pars,temporal_api=c("daily","monthly","hourly","climatology"),lonlat,dates=NULL,site_elevation=NULL,wind_elevation=NULL,wind_surface=NULL,time_standard=c("LST","UTC"))Argumentscommunity A character vector providing community name:“ag”,“re”or“sb”.See argu-ment details for more.pars A character vector of solar,meteorological or climatology parameters to down-load.When requesting a single point of x,y coordinates,a maximum of twenty(20)pars can be specified at one time,for“daily”,“monthly”and“climatology”temporal_api s.If the temporal_api is specified as“hourly”only15pars canbe specified in a single query.See temporal_api for more.These values arechecked internally for validity before sending the query to the POWER API.temporal_api Temporal API end-point for data being queried,supported values are“hourly”,“daily”,“monthly”or“climatology”.Defaults to“daily”.See argument detailsfor more.lonlat A numeric vector of geographic coordinates for a cell or region entered as x,y (longitude,latitude)coordinates.See argument details for more.dates A character vector of start and end dates in that order,e.g.,dates=c("1983-01-01","2017-12-31").Not used whentemporal_api is set to“climatology”.See argument details for more.site_elevation A user-supplied value for elevation at a single point in metres.If provided this will return a corrected atmospheric pressure value adjusted to the elevation pro-vided.Only used with lonlat as a single point of x,y coordinates,not for usewith“global”or with a regional request.wind_elevation A user-supplied value for elevation at a single point in metres.Wind Eleva-tion values in Meters are required to be between10m and300m.Only usedwith lonlat as a single point of x,y coordinates,not for use with“global”orwith a regional request.If this parameter is provided,the wind-surface param-eter is required with the request,see https:///docs/methodology/meteorology/wind/.wind_surface A user-supplied wind surface for which the corrected wind-speed is to be sup-plied.See wind-surface section for more detail.time_standard POWER provides two different time standards:•Universal Time Coordinated(UTC):is the standard time measure that usedby the world.•Local Solar Time(LST):A15degree swath that represents solar noon atthe middle longitude of the swath.Defaults to LST.ValueA data frame as a class,an extension of the tibble::tibble,object of POWER data includ-ing location,dates(not including“climatology”)and requested parameters.A decorative header of metadata is included in this object.Argument details for“community”There are three valid values,one must be supplied.This will affect the units of the parameter and the temporal display of time series data.ag Provides access to the Agroclimatology Archive,which contains industry-friendly parameters formatted for input to crop models.sb Provides access to the Sustainable Buildings Archive,which contains industry-friendly param-eters for the buildings community to include parameters in multi-year monthly averages.re Provides access to the Renewable Energy Archive,which contains parameters specifically tai-lored to assist in the design of solar and wind powered renewable energy systems. Argument details for temporal_apiThere are four valid values.hourly The hourly average of pars by hour,day,month and year,the time zone is LST by default.daily The daily average of pars by day,month and year.monthly The monthly average of pars by month and year.climatology Provide parameters as22-year climatologies(solar)and30-year climatologies(mete-orology);the period climatology and monthly average,maximum,and/or minimum values. Argument details for lonlatFor a single point To get a specific cell,1/2x1/2degree,supply a length-two numeric vector giving the decimal degree longitude and latitude in that order for data to download,e.g.,lonlat=c(-179.5,-89.5).For regional coverage To get a region,supply a length-four numeric vector as lower left(lon, lat)and upper right(lon,lat)coordinates,e.g.,lonlat=c(xmin,ymin,xmax,ymax)in that order for a given region,e.g.,a bounding box for the south western corner of Australia:lonlat =c(112.5,-55.5,115.5,-50.5).*Maximum area processed is4.5x4.5degrees(100 points).For global coverage To get global coverage for“climatology”,supply“global”while also speci-fying“climatology”for the temporal_api.Argument details for datesif one date only is provided,it will be treated as both the start date and the end date and only a single day’s values will be returned,e.g.,dates="1983-01-01".When temporal_api is set to “monthly”,use only two year values(YYYY),e.g.dates=c(1983,2010).This argument should not be used when temporal_api is set to“climatology”and will be ignored if set.wind_surfaceThere are17surfaces that may be used for corrected wind-speed values using the following equa-tion:W SC h gt=W S10m×(hgtW S50m)α.Valid surface types are described here.vegtype_135-m broadleaf-evergreen trees(70%coverage)vegtype_220-m broadleaf-deciduous trees(75%coverage)vegtype_320-m broadleaf and needleleaf trees(75%coverage)vegtype_417-m needleleaf-evergreen trees(75%coverage)vegtype_514-m needleleaf-deciduous trees(50%coverage)vegtype_6Savanna:18-m broadleaf trees(30%)&groundcovervegtype_70.6-m perennial groundcover(100%)vegtype_80.5-m broadleaf shrubs(variable%)&groundcovervegtype_90.5-m broadleaf shrubs(10%)with bare soilvegtype_10Tundra:0.6-m trees/shrubs(variable%)&groundcovervegtype_11Rough bare soilvegtype_12Crop:20-m broadleaf-deciduous trees(10%)&wheatvegtype_20Rough glacial snow/iceseaice Smooth sea iceopenwater Open waterairportice Airport:flat ice/snowairportgrass Airport:flat rough grassRate limitingThe POWER API endpoints limit queries to prevent server overloads due to repetitive and rapid requests.If youfind that the API is throttling your queries,I suggest that you investigate the use of limit_rate()from ratelimitr to create self-limiting functions that will respect the rate limits that the API has in place.It is considered best practice to check the POWER website for the latest rate limits as they differ between temporal API s and may change over time as the project matures. NoteThe associated metadata shown in the decorative header are not saved if the data are exported to a file format other than a native R data format,e.g.,.Rdata,.rda or.rds.Author(s)Adam H.Sparks<*********************>Referenceshttps:///docs/methodology/https://Examples#Fetch daily"ag"community temperature,relative humidity and#precipitation for January11985at Kingsthorpe,Queensland,Australiaag_d<-get_power(community="ag",lonlat=c(151.81,-27.48),pars=c("RH2M","T2M","PRECTOTCORR"),dates="1985-01-01",temporal_api="daily")ag_d#Fetch single point climatology for air temperatureag_c_point<-get_power(community="ag",pars="T2M",c(151.81,-27.48),temporal_api="climatology")ag_c_point#Fetch interannual solar cooking parameters for a given regionsse_i<-get_power(community="re",lonlat=c(112.5,-55.5,115.5,-50.5),dates=c("1984","1985"),temporal_api="monthly",pars=c("CLRSKY_SFC_SW_DWN","ALLSKY_SFC_SW_DWN"))sse_iquery_parameters Query the POWER API for Detailed Information on Available Param-etersDescriptionQueries the POWER API returning detailed information on available parameters.Usagequery_parameters(community=NULL,par=NULL,temporal_api=NULL)Argumentscommunity An optional character vector providing community name:“ag”,“sb”or“re”.par An optional character vector of a single solar,meteorological or climatology parameter to query.If unsure,omit this argument for for a full list of all theparameters available for each temporal API and community.temporal_api An optional character vector indicating the temporal API end-point for data be-ing queried,supported values are“hourly”,“daily”,“monthly”or“climatol-ogy”.DetailsIf par is not provided all possible parameters for the provided community,community and temporal API,temporal_api will be returned.If only a single parameter is supplied with no communityor temporal_api then the complete attribute information for that parameter will be returned for all possible communities and temporal API s combinations.If all three values are provided,only the information for that specific combination of parameter,temporal API and community will be returned.ValueA list object of information for the requested parameter(s)(if requested),community and temporalAPI.Argument details for temporal_apiThere are four valid values.hourly The hourly average of pars by hour,day,month and year.daily The daily average of pars by day,month and year.monthly The monthly average of pars by month and year.climatology Provide parameters as22-year climatologies(solar)and30-year climatologies(mete-orology);the period climatology and monthly average,maximum,and/or minimum values.Author(s)Adam H.Sparks,<*********************>Examples#fetch the complete set of attribute information for"T2M".query_parameters(par="T2M")#fetch complete temporal and community specific attribute information#for"T2M"in the"ag"community for the"hourly"temporal API.query_parameters(par="T2M",community="ag",temporal_api="hourly")#fetch complete temporal and community specific attribute information#for all parameters in the"ag"community for the"hourly"temporal API. query_parameters(community="ag",temporal_api="hourly")Indexget_power,2list,7query_parameters,6tibble::tibble,4tibble::tibble(),29。
中考英语缩略词与缩写练习题30题
中考英语缩略词与缩写练习题30题1. You can watch many interesting programs on _____.A.VIPTVC.WTOA答案：B。
“CCTV”是中国中央电视台的缩写，A 选项“VIP”是贵宾的意思；C 选项“WTO”是世界贸易组织的缩写；D 选项“USA”是美国的缩写。
题干中说可以看很多有趣的节目，只有CCTV 是电视台可以看节目。
2. If you are a very important person, you can get special treatment asa _____.A.VIPTVC.WTOA答案：A。
“VIP”是贵宾的意思，B 选项“CCTV”是中国中央电视台的缩写；C 选项“WTO”是世界贸易组织的缩写；D 选项“USA”是美国的缩写。
题干中说如果你是一个非常重要的人，会得到特殊待遇，符合VIP 的含义。
3. _____ is an important international organization for trade.A.VIPTVC.WTOA答案：C。
“WTO”是世界贸易组织的缩写，A 选项“VIP”是贵宾的意思；B 选项“CCTV”是中国中央电视台的缩写；D 选项“USA”是美国的缩写。
题干中说一个重要的国际贸易组织，是WTO。
4. _____ stands for the United States of America.A.VIPTVC.WTOA答案：D。
“USA”是美国的缩写，A 选项“VIP”是贵宾的意思；B 选项“CCTV”是中国中央电视台的缩写；C 选项“WTO”是世界贸易组织的缩写。
题干中说代表美利坚合众国，是USA。
5. We can see many international news on _____.A.VIPTVC.BBCA答案：C。
“BBC”是英国广播公司的缩写，可以看到很多国际新闻。
A 选项“VIP”是贵宾的意思；B 选项“CCTV”是中国中央电视台的缩写；D 选项“USA”是美国的缩写。
美国航天科技项目延迟及成本增加审计分析
2、对负责 SLS 项目的官员进行了访谈，并审查了其成本数 据，以确定该项目在未来发射阶段的追加成本预算；然后分析 了 SLS 计划当前已发生的成本估计，以确定当前估计的范围相 对于 SLS 基线成本估计的范围发生了何种变化。
3、获得并审查了项目的季度报告和风险登记册，列出了最 主要的项目风险及其潜在的成本和进度影响，还有迄今为止采 取的措施；与项目官员讨论了项目可能发生的风险。此外，还比 较了三个不同时间点的项目时间表以评估项目组件和软件是 否按预期进展。
with Options Analysisy ［J］.Industrial Marketing Management，2013（02）. ［3］Gardner J W.The valuation of information technology：A guide for strategy development，valuation，and finantional planning［J］.John Wiley and sons Inc，1965. ［4］Haire.M.Biological，Models and Empirical Histories in the Growth of Organizations ［D］.New York：John Wiley，1959. ［5］陈佳贵.关于企业生命周期与企业蜕变的探讨［J］.中国工 业经济，1995（11）. ［6］罗红雨.基于企业生命周期的成本战略研究［J］.财会月刊， 2009（17）. ［7］杨海平，崔荣芳.基于企业生命周期的财务战略分析［J］.财 会通讯（综合版），2008（10）.
国外载人航天器标志相关标准综述
国外载人航天器标志 相关标准综述
Review of Foreign Standards for Manned Spacecraft Lable
尹玉梅 孙晓君 赵晓凌（北京空间科技信息研究所）
1 概述
标志是由符号、文字、颜色和几何形状（或边框） 等组合形成的传递特定信息的视觉形象。规范化的标 志种类、样式和使用方法能够方便航天员和地面操作 人员的使用和操作载人航天器产品，提高工作效率， 避免发生误操作和意外伤害，从而保护载人航天器和 航天员的安全。本文重点调研和分析“国际空间站” （ISS）标准、美国国家航空航天局（NASA）标准， 梳理出标准中标志规定的相关要素和主要内容，为我 国载人航天器标志相关标准编制提供参考和借鉴，更 好规范我国载人航天相关工作的开展。
空间站标准作为以美国为主体、其他国家参与 的工程类标准，其目的在于确保各参与国之间空间站 工程的合作协调顺利进行，以促进多边工程项目的有 效研制和管理。由于“国际空间站”以美国为主体， 且美国航天事业起步早，技术先进，拥有较为完备的 NASA 标准体系，在“国际空间站”建设和运行过程中， 使用了 NASA 现有标准。通过调研，国外载人航天
第 2 部分根据标志的六种类型逐一给出各类标 志的详细目录（包括图形编号、字体要求、使用材料、
约束条件，如脱出有害气体、气味、抗真菌、使用位 置等要求）、标志样例及相关说明（包括标志材质、 各组成图形和文字的颜色、字体大小、样式。以及该 标志的使用对象、用途），使用者可以从目录中选择 需要的标志。
《标志方法文档及详细目录》是关于“国际空 间站”标志的最为详细、最为全面的标准，其中很多 标志已在各类 NASA 的飞行器中得到应用，NASA 和 NASA 的合作者均需从该标准中选择所需要的标 志。如果所使用的标志不在《标志方法文档及详细目 录》内，使用者需要提交申请，将新的标志作为标准 的候选标志。《标志方法文档及详细目录》也被用于 “国际空间站”相关标志的设计、制作等。
The NASA Astrophysics Data System Obsolescence of Reads and Cites
Library and Information Services in Astronomy IVJuly2-5,2002,Prague,Czech RepublicB.Corbin,E.Bryson,and M.Wolf(eds)The NASA Astrophysics Data System:Obsolescence ofReads and CitesMichael J.Kurtz,Guenther Eichhorn,Alberto Accomazzi,Carolyn S.Grant,Donna M.Thompson,Elizabeth H.Bohlen,and Stephen S.MurrayHarvard-Smithsonian Center for Astrophysics,Cambridge,MA02138USAkurtz@Abstract.The obsolescence of an article,how its use declines as it ages,has long been a central element of bibliometric studies.Normally this is de-termined using the citations to an article.We determine this function using the reads an article receives and then compare this with the func-tion determined from a citation study.There are both similarities and differences.The similarities are strong enough that the normative theory of citations must be true in the mean.1.Readership as a function of ageBecause the use of the Astrophysics Data System(ADS)is now the dominant means by which astronomers access the technical literature the ADS usage logs can provide a uniquely powerful view of the way an entire discipline(astronomy) uses the technical literature.Here we will examine the obsolescence(e.g.White and McCain(1989),Line and Sandison(1975))of the technical literature of astronomy as a function of article age based on the actual readership of an article.This is an extension and reexamination of the work done in Kurtz et al.(2000).We use,as our basic data source,the log of all article“reads”using the ADS between Januaryfirst and August20th,2001.We define a“read”as every time a user,who has access to a list of articles,their dates,journal names,titles and authors,chooses to view more information about an article.Currently50% of these“reads”are of the abstract,38%are of one of the forms of whole text, 8%are of the citation list,and the rest are distributed amongst the ten other options.There are more than4.2million“reads”in this log.For this study we extracted those for any of the three major U.S.astronomy journals The Astrophysical Journal,The Astronomical Journal,and The Pub-lications of the Astronomical Society of the Pacific.All three of these journals have been stable over the past century,are currently among the most important astronomy journals,and have had their full text versions beginning with their first issues available on-line through ADS since well before the beginning of the223224M.Kurtz et al.190019201940196019802000110100publication yearHCI 19751980198519901995200010100publication year H C IFigure 1.LEFT:The average number of reads per article per year for three U.S.astronomy journals.The thin line represents the actual data,the thick line is the model in the text,and the three dotted lines represent the three components of the model.RIGHT:An expanded view showing the most recent 25years.Note that the model fits the actual data very well.reporting period.These journals accounted for slightly more than 1.8million reads in the first 7.66months of 2001.1.1.The obsolescence model for readsFigure 1—LEFT shows the average number of reads per article per year for these three journals as a function of publication year.This shows more than a full century from the first issue of The Publications of the Astronomical Society of the Pacific in 1889through 2000.Figure 1—RIGHT shows an expanded view of the last 25years of data from figure 1—LEFT.The dotted lines show the relevant three components of the four component readership model of Kurtz et al.(2000),as modified here.In this model research article readership (R)is parameterized by the sum of four exponential functions with very different time constants;we associate these four functions with four different modes of readership:Historical (R H ),Interesting (R I ),Current (R C )and New (R N ).The New (R N )mode,which corresponds to the newly arrived (either on-line or in the mail)issue,cannot be parameterized by the data in figures 1—LEFT and 1—RIGHT.The Historical (R H )mode we actually parameterize as a constant,H 0.We leave the exponential form in equation C (with k H =0)because other combinations of multiplicative and time constants can also be found which fit the data well,including some combinations with k H =0.R =R H +R I +R C +R N(C )whereR H =H 0e −k H TNASA ADS:Obsolescence of Reads and Cites225R I=I0e−k I TR C=C0e−k C TR N=N0e−k N TandH0=1.5;k H=0I0=45;k I=0.065C0=110;k C=0.4N0=1600;k N=16The three longer term functions,R H,R I,and R C are parameterized to fit the data shown infigures1—LEFT and1—RIGHT.The R N function is included for completeness;k N is taken from Kurtz et al.(2000).N0is obtained by assuming k N is correct,and ascribing all readership of the Astrophysical Journal electronic edition which does not originate with ADS to the N mode. This is a very crude approximation,but the three component(R H,R I,and R C) model for archival readership is not effected by the N mode usage,which fades very rapidly following publication.The three mode model is not unique but does provide a very goodfit to the existing data,asfigures1—LEFT and1—RIGHT show.No model consisting of only two exponential functions canfit both the recent and historical data,as comparing the twofigures makes clear.Most studies of obsolescencefind that the use of the literature declines exponentially with age,and parameterize this with a single number,often called the“half-life,”which is related to the coefficient in the exponent by half-life= log e(2)/k,the point where the use of an article drops to half the use of a newly published article.There are several other definitions of half-life in the literature, we use this one.Thus the Historical(R H)component of equation C does not have a half-life;the half-life of the Interesting(R I)component is10.7years; the half-life of the Current(R C)component is1.7years.Kurtz et al.(2000) estimate the half-life of the New(R N)component at16days.Several studies(e.g.Egghe(1993)and references therein)decompose the exponential decay in use into the product of an intrinsic decay and the general growth of the literature.The results presented here are for the mean current use per article published as a function of time since the present,thus we measure directly the intrinsic decay.Kurtz et al.(2000)show the growth of the astro-nomy literature has been3.7%per year,measured in terms of number of papers published over the past22years.The total number of papers read over time in each mode is just the integral of the function from zero to infinity,which for a negative exponent is just the ratio of the two constants:H0/k H=∞reads(one and a half reads per year forever);I0/k I=818reads;C0/k C=275reads;N0/k N=100reads.This assumes no growth in the number of reads,If the number of reads per year increases long term at the3.7%at which the number of publications is now increasing the constants in the exponents would all be increased by0.037;this would have very little effect on the integrals of the R N and R C functions,but would more than triple the articles read in the R I mode;and the R H mode would grow apace with the growth in the number of reads.226M.Kurtz et al.1.2.DiscussionBeginning with Burton and Kebler(1960)there have been a number of studies (see White and McCain(1989)for a review)which suggest that the obsolescence function consists of the sum of two exponentials,which Burton and Kebler(1960) attribute to“classic”and“ephemeral”papers;parameterizations(e.g.Price (1965))tend to be similar to our R H+R I functions.If we ignore the R N component,which neither this study,nor any of the other studies of obsolescence could see,we still very clearlyfind three separate components to the obsolescence function.Why have these three components not been seen til now?We suggest that the data available to previous studies has not been adequate to see these subtle effects.Most studies have used citation data to determine the obsolescence function.Because it takes time after a paper is published for it to be cited(e.g.section2)the peak in the R C mode is obscured in citation data. Also citation studies have substantial problems accounting for the growth of the literature,which has not been at all constant over the past century.Related to this is the determination of the size of the sample universe(the number of relevant papers to the study)at past times.There are certainly other possibilities,perhaps the obsolescence function is different for reads and cites,and perhaps the very existence of the ADS has changed the way the literature is used.We will explore these questions further in section2.The reason why readership studies have not seen the three component nature of archival readership which we see,we suggest,is that the data available in such studies has been too sparse.The largest astronomy library,the Cen-ter for Astrophysics Library,has a reshelve rate of about1000/month(Coletti (1999)),which is less than0.2%of the rate of reads in ADS.Additionally many astronomers keep(and use)their own paper copies of recent journals,which would suppress the R C mode in library use.2.The relationship between reads and citesCentral to bibliometrics is the study of citations(Garfield(1979)),and central to the study of citations is the so called normative assumption(Liu(1993)) that“the number of times a document is cited...reflects how much it has been used...”(White and McCain(1989)).There have been many articles suggesting problems with citations studies(e.g.MacRoberts and MacRoberts(1989)),and many articles defending them(e.g.Small(1987)).White(2001)and Phelan (1999)discuss these issues.The readership data discussed in section1provide a totally independent, direct new measure of“how much(an article)is used.”Comparing the read-ership statistics with citation measures will show exactly the similarities and differences between citations,which are an indirect measure of use,but,some would argue,a direct measure of usefulness and reads,which are a direct meas-ure of use,but perhaps an indirect measure of usefulness.Here we expand considerably on the comparison presented in Kurtz et al.(2000).NASA ADS:Obsolescence of Reads and Cites2272.1.The mean relationship between reads and citesWhile there have been many dozens of studies on obsolescence using citations, and many dozen more using readership as determined by using library circulation statistics(see White and McCain(1989)for review),there are very few studies comparing the two methodologies over the same data.Tsay(1998)compared the readership obsolescence function(obtained by reshelving statistics)for a number of medical journals with the citation obsolescence function for the same journals. He found the half-life of the readership function was significantly shorter than the half-life of the citation function.Tsay(1998)reviewed the literature and found only one previous comparable study:Guitard,in1985(discussed in Line (1993)),using photocopy requests as the use proxy,found the citation half-life shorter than the readership half-life.We have only found two other studies.Cooper and McGregor(1994),also using photocopy data,find citation half-life substantially longer than the use half life;also theyfind“no correlation between obsolescence measured by pho-tocopy demand and obsolescence measured by citation frequency.”Satariano (1978)used the questionnaire method tofind“citation patterns reflect a cross-disciplinary focus that is not found in the journals most often read.”We believe Kurtz et al.(2000)contains thefirst study using a data-set large enough to show the similarities and differences between the two obsolescence functions.Here we use a substantially improved data-set;a complete discussion will be published in Kurtz et al.(2003).Synchronous relation Kurtz et al.(2000)found that the instantaneous obsol-escence function for articles from the recent technical astronomy literature as measured by citations is simply equal to a proportionality constant times the function measured by reads times an exponential ramp-up to account for the time delay from when an article isfirst published to when an article which cites that article is published:C=cR(1−e−k D T)(D) wherec≈0.05;k D=0.7The proportionality constant,c,represents the number of reads per citation. This changes with the(always incomplete)citation databases and with time,as the ADS use increases.Currently we estimate that the average paper is read about twenty times using ADS for every time it is cited.In comparing the citation and reads obsolescence functions we have adjusted c to provide the best fit to the samples.Figure2—LEFT compares the reads and cites obsolescence functions for re-cent articles.The readership data is for articles from The Astrophysical Journal, The Astronomical Journal,The Publications of the Astronomical Society of the Pacific,and The Monthly Notices of the Royal Astronomical Society which were read between1January2001and20August2001.The citation data are taken from those four journals and both Astronomy&Astrophysics and Nature,where the publication date was also between1January2001and20August2001.Only citations to one of the four journals in the readership sample were taken;the data contain45,000citations.228M.Kurtz et al.1975198019851990199520000.40.50.60.70.80.9123publication year 1900192019401960198020000.010.11publication year HCIFigure 2.LEFT:A comparison of the C =cR (1−e −k D T )model with the actual citations for papers from the 2001sample for the most recent 25years.The thick line shows the actual citations,the thin line is the model,using the actual reads,and the dotted line is the model using the reads model,equation C.RIGHT:A comparison of the C =cR (1−e −k D T )model with the actual citations for papers from the six year sample for the last 111years.The thick line shows the actual citations,the thin line is the model,using the actual reads,and the dotted lines are the modified reads model from equation C and its components.As can be seen from figure 2—LEFT the citation function follows the reads function very closely.In particular the R C function clearly has an analog in the citation data;despite the suppression of the steep increase compared with the raw reads due to the exponential ramp-up.The change in slope in the citation function seen beginning about 1994is exactly what is predicted from the reads function;the number of citations in 1998and 1999are more than 40%above that expected by an extrapolation of the exponential decay seen between 1975and 1990,a decay which corresponds very closely to the R I function.We suggest this shows that the citation derived obsolescence function has two components with exactly the same parameters as the two mid-range (in time)readership functions.To examine the obsolescence function over a longer time period we use a different dataset of citations.We take all citations to the four journals in the readership sample from articles published between 1January 1995and 20August 2001in the ADS database.The data contain 625,000citations.We continue to use as our comparison the 2001reads sample.Clearly papers published in 1995could not have cited papers published in 2000,so comparison with recent obsolescence is impossible.This comparison is in figure 2—LEFT.We use these data exclusively to examine the long term behavior of the obsolescence function.Figure 2—RIGHT shows the long term obsolescence function obtained from citation data compared with the readership function.They clearly are notNASA ADS:Obsolescence of Reads and Cites229 the same.The citation function follows the R I function but not the R H+R I function.This is not a statisticalfluke based on having a small number of citations;the number of citations in the period from1889to1940which are “missing”from the citation function exceed5,000.In the year1900,for example, there were18citations in the six year sample,about150would be expected, were the R H mode to produce citations at the same amplitude as the R I mode.We are therefore driven to the conclusion that:C=c(R C+R I)(1−e−k D T)(E) wherec≈0.05;k D=0.7for research articles in the astronomy literature.There are a number of possible reasons for the citation obsolescence function to be different from the reads function.There are also a number of possible reasons why the citation obsolescence function measured here does not show the R H component,whereas this component is seen in other citation based obsolescence functions,beginning with Price(1965).We see no clear candidate explanation which accounts for both differences,however.Discussion We have shown that the citation rate as a function of time is equal to a constant times the sum of two modes of the readership function.There is no a priori reason why the constant c in equation E should not actually be a function of time;why should the number of citations per read(about0.05)be constant,independent of the age of the article?Examiningfigures2—LEFT and2—RIGHT we see that if c is a function of time it cannot change by more than about1%per year.This is an extraordinary result,it says that within the(small)measurement error the C function and the R C+R I function must be measuring exactly the same thing,the mean usefulness of journal articles as a function of time.Because the private act of reading an article entails none of the various sociological influences as the public act of citing an article(Seglen(1997)lists several of these factors)this suggests that in the mean these factors do not influence the citation rate.Unless the sum of all the various sociological influences as a function of time is exactly the same as the usefulness of articles as a function of time the existence of these influences would cause c not to be constant.That c is constant means that at every age the total effect of these various influences is zero.We therefore assert that we have proven that the normative theory of citing (Liu(1993))is true in the mean.ReferencesBurton,R.E.and Kebler,R.W.1960,The Half-Life of some Scientific and Tech-nical Literature,American Documentation,11,18.Coletti,D.J.1999,Report from the Librarian,Harvard-Smithsonian Center for Astrophysics,John G.Wolbach Library.230M.Kurtz et al.Cooper,M.D.and McGregor,G.F.1994,Using Article Photocopy Data in Bib-liographic Models for Journal Collection Management.Library Quarterly 64,386.Egghe,L.1993,On the Influence of Growth on Obsolescence,Scientometrics27, 195.Garfield,E.1979,Citation Indexing:Its Theory and Application in Science, Technology,and Humanities,New York:Wiley.Kurtz,M.J.,G.Eichhorn,A.Accomazzi, C.S.Grant,S.S.Murray,and J.M.Watson2000.The NASA Astrophysics Data System:Overview.A&AS143,41-59.Kurtz,M.J.,G.Eichhorn,A.Accomazzi,C.S.Grant,M.Demleitner,and S.S.Murray2003.The NASA Astrophysics Data System:Sociology, Bibliometrics,and Impact.Journal of the American Society for Informa-tion Science,to appearLiu,M.1993,Progress in Documentation The Complexities of Citation Practice:A Review of Citation Studies.Journal of Documentation49,340. Line,M.B.1993,Changes in the Use of Literature with Time—Obsolescence Revisited,Library Trends,41,665.Line,M.B.and Sandison,A.1975,Progress in Documentation-Obsolescence and Changes in Use of Literature with Time,Journal of Documentation 30,283.MacRoberts,M.H.and MacRoberts,B.R.1989,Problems in Citation Analysis, Journal of the American Society for Information Science,40,342. Phelan,T.J.1999,A Compendium of Issues for Citation Analysis,Scientomet-rics,45,117.Price,D.J.de Solla1965,Networks of Scientific Papers,Science,149,510. Satariano,W.A.1978,Journal Usein Sociology:Citation Analysis versus Read-ership Patterns.Library Quarterly48,293.Seglen,P.O.1997,Citations and Journal Impact Factors:Questionable Indic-ators of Research Quality.Allergy52,1050.Small,H.G.1987,The Significance of Bibliographic References,Scientometrics, 12,339.Tsay M.-Y.1998,Library Journal Use and Citation Half-Life in Medical Science.Journal of the American Society for Information Science49,1283. White,H.D.2001,Authors as Citers over Time.Journal of the American Society for Information Science,52,87.White,H.D.and McCain,K.W.1989,Bibliometrics,Annual Review of Inform-ation Science and Technology,24,119.。
nasa格言
NASA格言引言[NASA](（National Aeronautics and Space Administration，美国国家航空航天局）是美国政府主导的宇航员航天机构，其使命是探索太空、促进科学研究和发现新的知识。
作为一个具有世界级声誉的组织，NASA秉持着一系列价值观和目标，这些价值观和目标被总结为了它们的格言。
在本文中，我们将深入探讨NASA格言的含义和其对NASA使命的重要性。
NASA格言的重要性NASA格言是该机构的核心理念和行动准则。
这些格言不仅激励着NASA的工作人员，还体现了NASA作为一个组织的追求和目标。
它们在NASA的各个领域和项目中发挥着重要的作用，将NASA推向了科学和技术的前沿。
接下来，我们将具体探讨NASA格言的内容和意义。
1. “出征太空”1.1 太空探索的意义太空探索一直以来都是NASA的核心使命之一。
通过”出征太空”，NASA旨在推进人类对宇宙的理解和知识的创新。
太空探索不仅涉及到宇宙物理学和天文学的研究，还涉及到对地球环境的监测和保护。
通过在太空中进行观测和实验，NASA能够获得独特的数据和洞察力，对于解决地球上的各种问题和挑战非常重要。
1.2 推动科学和技术的进步“出征太空”也反映了NASA在科学和技术领域的重要性。
太空探索不仅需要高超的工程技术，还需要创新和发展最新的科学方法和技术手段。
NASA的科学家和工程师在推动先进技术和科学研究方面发挥着关键作用，这有助于促进科学和技术的进步，并推动全球技术和经济的发展。
1.3 太空探索的挑战与机遇“出征太空”意味着面临着巨大的挑战和机遇。
太空环境对人类来说是极其恶劣和敌对的，但这也为人类提供了探索和开发的机会。
太空探索需要解决许多技术和工程上的问题，例如重力和辐射的影响，长时间太空旅行的生命支持系统，以及宇宙中未知的风险和威胁。
然而，面对这些挑战，NASA始终坚持着”出征太空”的使命，推动人类探索太空的边界。
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NASA TECHNICAL STANDARD NASA-STD-8739.1A With Change 2National Aeronautics and Space Administration Washington, DC 20546Approved: 2008-03-04 Change 2 Approved: 2011-03-29WORKMANSHIP STANDARD FOR POLYMERIC APPLICATION ON ELECTRONIC ASSEMBLIES Measurement System Identification:Metric (English)Requests for Relief from the requirements in this documentare processed through theNASA Safety and Mission Assurance Technical Authorityper NPR 8715.3 paragraph 1.13APPROVED FOR PUBLIC RELEASE – DISTRIBUTION IS UNLIMITEDThis page intentionally left blank.DOCUMENT HISTORY LOGStatus DocumentRevisionApprovalDateDescriptionBaseline 1999-08-06 Initial ReleaseRevision AUpdate/Revise2008-03-04 Technical corrections and addition of sections coveringbonding and encapsulation.Change 1 2009-07-23Editorial errata to paragraphs 2.1.2, 2.1.3, 4.1.4, 4.5.2.a,5.1.3, 5.2.1, 5.5.1,6.2.2, 6.3.1.1, 6.5.1.a, 6.6.1.b, 6.6.2.b,6.8.1.2, Table 6-1, 8.1.3, 8.4.4, Table 8-1 Notes 2/4,9.1.2.3, 9.1.2.4, 9.1.3.f, 9.1.4.3.c/d/e/f/g, 9.2.1.2, Figures9-1/2/3/4/5/6/7/10, 10.2.5, 10.2.7.f, Figure 10-3, Table10-1, 12.3, 12.3.2/3/6/8, Figures 12-1/2, 13.2.2.a, 13.3.g,13.6.2.d/i thru p, 13.6.3.b/g, 13.7.2.a. 13.7.3.d/e, 13.8.1,13.9.2.j, 13.10.3, 13.11.3.c/d(JWL4) Change 2 2011-03-29Editorial errata to Foreword paragraph 2, and paragraphs1.0, 1.3, 1.4.1, 1.4.2, 4.2.2, and 12.1. Format Pagenumbers. Add reference to NASA-STD 8709.22 inparagraphs 2.1.2 and 3.2.(JWL4)This document is subject to reviews per Office of Management and Budget Circular A-119, Federal Participation in the Development and Use of Voluntary Standards (02/10/1998) and NPD 7120.4, NASA Engineering and Program/Project Management Policy.This page intentionally left blank.FOREWORDThis NASA Standard (NASA-STD) is published by the National Aeronautics and Space Administration (NASA) to provide uniform engineering and technical requirements for processes, procedures, practices, and methods that have been endorsed as standard for NASA programs and projects, including requirements for selection, application, and design criteria of an item. Use of this NASA-STD is the responsibility of the user as required by NASA Policy Directive (NPD) 8730.5, NASA Quality Assurance Program Policy.This NASA-STD is approved for use by NASA Headquarters and NASA Centers, including Component Facilities. This NASA-STD may be applied on contracts for spacecraft, aircraft, balloon payloads, instruments, or launch vehicles.The requirements herein prescribe NASA’s technical requirements, procedures, and documenting requirements for staking, conformal coating, bonding, and encapsulation of printed wiring boards and electronic assemblies. These may be tailored to the program applications to obtain the most cost effective, best quality product. These requirements describe basic considerations necessary to ensure reliable staking, conformal coating, bonding, and encapsulation of printed circuit boards and electronic assemblies. Included are requirements which establish the responsibility for documenting fabrication and inspection procedures to be used for NASA work including supplier innovations, special processes, and changes in technology. For the purpose of this document, the term “supplier” is defined as in-house NASA, NASA contractors, and subtier contractors.Requests for information, corrections, or additions to this NASA-STD can be submitted via “Feedback” in the NASA Technical Standards System at . This NASA-STD was developed by the NASA Headquarters Office of Safety and Mission Assurance, Safety and Assurance Requirements Division and the NASA Workmanship Technical Committee which is managed by NASA Goddard Space Flight Center.March20084,O’ConnorBryans/Date O’Connor ApprovalBryanChief, Safety and Mission AssuranceNASA-STD 8739.1 Change 2 approved by: Michael G. Stamatelatos, Ph.D. on 29 March 2011NASA Technical Standards for Mission Hardware and Mission-CriticalGround Support EquipmentNASA Technical Standards can be found on the World Wide Web at URL address/public/public_query_NASA_stds.taf.Title NumberWorkmanship Standard for Staking and Conformal Coating of Printed Wiring Boards and Electronic Assemblies NASA-STD 8739.1A with Change 2Workmanship Standard for Surface Mount Technology NASA-STD 8739.2 with Change 2Soldered Electrical Connections NASA-STD-8739.3 with Change 4Crimping, Interconnecting Cables, Harnesses, and Wiring NASA-STD-8739.4 with Change 6Fiber Optic Terminations, Cable Assemblies, and Installation NASA-STD-8739.5 with Change 2NOTE: NASA-STD-8739.7, Standard for Electrostatic Discharge Control (Excluding Electrically Initiated Explosive Devices), was referenced inearlier versions of this document as a NASA Technical Standard forFlight Hardware Workmanship. It has been replaced with ANSI/ESDS20.20, Protection of Electrical and Electronic Parts, Assemblies andEquipment (Excluding Electrically Initiated Explosive Devices)TABLE OF CONTENTS1. SCOPE (11)1.1 Purpose (11)1.2 Applicability (11)1.3 Special Requirements (11)1.4 Approval of Departures from this Standard (11)2. APPLICABLE DOCUMENTS (12)2.1 Applicable Documents (12)2.1.1 General (12)2.1.2 Government Documents (12)2.1.3 Non-Government Documents (12)3. ACRONYMS AND DEFINITIONS (13)3.1 Acronyms (13)3.2 Definitions (14)4. GENERAL REQUIREMENTS (18)4.1 General (18)4.2 Documentation (18)4.3 Rework and Repair (18)4.4 Electrostatic Discharge Requirements (19)4.5 Selection and Approval Requirements for Polymeric Materials (19)5. TRAINING AND CERTIFICATION PROGRAM (22)5.1 General (22)5.2 Vision Requirements (22)5.3 Personnel Certification Levels (23)5.4 Training Program Requirements (23)5.5 Documentation (24)5.6 Maintenance of Certification Status (24)5.7 Training Resources (25)6. FACILITIES, TOOLS, AND MATERIALS (26)6.1 Safety (26)6.2 Facility Cleanliness (26)6.3 Environmental Conditions (26)6.4 Silicone Operations (27)6.5 Tool and Equipment Control (27)6.6 Material Storage and Records Retention (28)6.7 Inspection Optics (29)6.8 In-Process Storage and Handling (29)6.9 Solvents (29)7. CLEANLINESS REQUIREMENTS (31)7.1 General (31)7.2 Cleanliness Testing (31)7.3 Test Limits (32)7.4 Resistivity of Solvent Extract (32)7.5 Sodium Chloride Salt Equivalent Ionic Contamination Test (32)8. PREPARATION FOR POLYMERIC APPLICATIONS (34)8.1 Surface Preparation (34)8.2 Masking (34)8.3 Priming (34)8.4 Material Preparation (36)8.5 Test Specimen (38)8.6 Conformal Coating Specimens (38)9. STAKING (39)9.1 Requirements (39)9.2 Fastener Staking (47)9.3 Torque Striping (49)10. CONFORMAL COATING (50)10.1 Purpose (50)10.2 Conformal Coating Application (50)10.3 Curing (53)10.4 Cleanup (53)10.5 Touchup/Rework (53)11. BONDING (58)11.1 General (58)11.2 Bonding (58)12. ENCAPSULATION (60)12.1 General (60)12.2 Pre-cure Examination (60)12.3 Post-cure Inspection (60)12.4 Potting Connectors used with Shielded Cable (62)12.5 Cleanup (62)13. QUALITY ASSURANCE (63)13.1 General (63)13.2 Documentation Verification (63)13.3 Documentation Authorization (64)13.4 Verification of Tools, Equipment, and Materials (64)13.5 General Inspection Methods for Polymeric Applications (64)13.6 Acceptance/Rejection Criteria for Staking (65)13.7 Acceptance/Rejection Criteria for Fastener Staking and Torque Striping (67)13.8 Inspection Methods for Conformal Coating (68)13.9 Acceptance/Rejection Criteria for Conformal Coating (68)13.10 Acceptance/Rejection Criteria for Bonding (69)13.11 Acceptance/Rejection Criteria for Encapsulation (70)APPENDIX A. CONFORMAL COATING PROBLEMS (72)A.1 Conformal Coating Thickness (72)A.2 Coverage – Points and Edges (72)A.3 Bubbles (72)LIST OF FIGURESFigure 9-1: Default Staking for Horizontally-Mounted Sleeveless Cylindrical Part (42)Figure 9-2: Default Staking for Horizontally-Mounted Sleeved Cylindrical Parts (42)Figure 9-3: Default Staking of a Single Vertically-Mounted Rectangular Part (43)Figure 9-4: Default Staking for an Array of Vertically-Mounted Rectangular Parts (43)Figure 9-5: Staking for Radial Lead Components (44)Figure 9-6: Staking for Radial Multi-lead Rectangular Components (44)Figure 9-7: Wire Bundle Staking (45)Figure 9-8: Single Wire Staking (45)Figure 9-9: Toroid Staking (46)Figure 9-10: Vibration Dampening Staking (47)Figure 9-11: Locking of Screws and Bolts with Nuts (48)Figure 9-12: Thread Locking of Blind Screw (49)Figure 9-13: Torque Striping Methods (49)Figure 10-1: Spray Application (51)Figure 10-2: Conformal Coating – Bubbles (54)Figure 10-3: Conformal Coating – Scratches (55)Figure 10-4: Conformal Coating - Lifting and Peeling (56)Figure 10-5: Conformal Coating – Coverage Defects (57)Figure 11-1: Component Bonding - Excess Bonding Material (59)Figure 12-1: Encapsulating Wires at Connector (61)Figure 12-2: Module Encapsulation (62)LIST OF TABLESTable 6-1: Solvent and Cleaners (30)Table 7-1: Cleanliness Test Values (33)Table 8-1: Demoisturizing Schedules for Polymeric Applications Surface Preparation (35)Table 10-1: Conformal Coating Thickness (52)1. SCOPEThis standard prescribes NASA’s technical requirements, procedures, and documentation requirements for polymeric applications for electrical and electronic assemblies.1.1 P urposeThis publication sets forth requirements for staking, conformal coating, bonding, and encapsulation of components used in electronic hardware.1.2 A pplicabilityThis publication is applicable to NASA programs involving polymeric applications for flight hardware, mission critical ground support equipment, and elements thereof and wherever invoked contractually.1.3 S pecial RequirementsSpecial requirements that are not in conformance with the requirements of this publication and which are documented in the engineering drawings shall be traceable to prior NASA approval (also see 1.4) (Requirement).1.4 A pproval of Departures from this Standard1.4.1 Minor departures from this standard require prior written approval from the NASA project management. In addition, for non-NASA suppliers, written approval is required from the cognizant NASA contracting officer. The supplier is responsible for assuring that any departures from this publication are evaluated by, coordinated with, and submitted for approval prior to use or implementation. Departures which reduce the requirements herein may warrant a request for relief per NASA-STD-8709.20, Management of Safety and Mission Assurance Technical Authority.1.4.2 Reserved.2. APPLICABLE DOCUMENTS2.1 A pplicable Documents2.1.1GeneralThe documents listed in this section contain provisions that constitute requirements of this NASA-STD. The latest issuance of cited documents is to be used unless otherwise approved by the assigned Technical Authority. The applicable documents are accessible via the NASA Online Directives Information System at /, the NASA Technical Standards website at , or directly from the Standards Developing Organizations (SDOs) or other document distributors.2.1.2Government Documents27 CFR 21.35 Code of Federal Regulations, Title 27, Alcohol, Tobacco and Firearms,Part 21, Formulas for Denatured Alcohol and Rum, Subpart D,Specially Denatured Spirits Formulas and Authorized Uses, FormulaNo. 3-AO-M-232 Methanol (Methyl Alcohol)NASA-STD-6001 Flammability, Odor, Offgassing and Compatibility Requirements andTest Procedures for Materials in Environments that SupportCombustionNASA-STD 8709.22 Safety and Mission Assurance Terms and DefinitionsNPD 8730.5 NASA Quality Assurance Program PolicyOSHA Standards Occupational Safety and Health Administration (OSHA), Title 29, Codeof Federal Regulations (CFR), Part 1910, Occupational Safety andHealth Standards.TT-I-735A Specification for Isopropyl Alcohol2.1.3Non-Government DocumentsANSI/NCSL Z540.1 Requirements for the Calibration of Measuring and Test EquipmentSpecification for sec-Butyl AlcoholASTM-D-1007 StandardASTM-D-2240 Standard Test Method for Rubber Property – Durometer Hardness ASTM-E-595 Standard Test Method for Total Mass Loss and Collected VolatileCondensable Materials From Outgassing in a Vacuum Environment ANSI/ESD S20.20 Standard for Electrostatic Discharge Control (Excluding ElectricallyInitiated Explosive Devices)3. ACRONYMS AND DEFINITIONS3.1 A cronymsThe following acronyms apply to terms used in this Standard. CFR Code of Federal RegulationsCTE Coefficient of Thermal ExpansionCVCM Collected Volatile Condensable MaterialCVD Chemical Vapor DepositionPackageDIP Dual-In-LineDOT Department of TransportationElectronic, and Electromechanical EEE Electrical,EPA Environmental Protection AgencyESD ElectrostaticDischargeGSFC Goddard Space Flight CenterJPL Jet Propulsion LaboratoryMSDS Material Safety Data SheetNASA National Aeronautics and Space AdministrationStandardNASA-STD NASANPD NASA Policy DirectiveNPR NASA Procedural RequirementsSDO Standards Developing OrganizationsOSHA Occupational Safety and Health Administration OSMA Office of Safety and Mission AssurancePRT Platinum Resistance ThermometerPWA Printed Wiring AssemblyPWB Printed Wiring BoardQPL Qualified Products ListHumidityRH RelativeLossMassTML TotalUV Ultraviolet3.2 D efinitionsNote: Definitions for SMA terms are found in NASA-STD 8709.22, Safety and MissionAssurance Acronyms, Abbreviations, and Definitions. Terms unique to this NASA-STDare listed below.Accelerator: A compounding material used in small amounts with a curing agent to increase the cure rate.Area Array Package: A package with an X-Y grid interconnect pattern on the under-surface (i.e., ball grid array, column grid array, land grid array, pin grid array).Batch: That quantity of material that was subjected to unit chemical processing or physical mixing, or both, designed to produce a product of substantially uniform characteristics.Blister: Undesirable rounded elevation of the surface of a polymer, whose boundaries may be more or less sharply defined.Bonding: Bonding refers to fastening parts or materials to a substrate or assembly using a polymer sandwich construction.Catalyst: A substance that changes the rate of a chemical reaction without undergoing permanent change in its composition; a substance that markedly speeds up the cure of a compound when added in minor quantity as compared to the amount of primary reactants.Certification of Personnel: The act of verifying and documenting that personnel have completed the required training and have demonstrated specified proficiency and have met other specified requirements.Coefficient of Thermal Expansion (CTE): The measure of the fractional change in dimension per unit change in temperature.Conductor: A lead or wire, solid, stranded, or printed wiring path serving as an electrical connection.Conformal Coating: A thin electrically nonconductive protective coating that conforms to the contours of the printed wiring assembly (PWA) or electronic assemblies.Conformal Coating Specimen: A representative sample of the conformal coating process that is created simultaneously with the same materials, at the same time, and with the same processes as used to coat the finished item.Contaminant: An impurity or foreign substance present in a material that affects one or more properties of the material. A contaminant may be either ionic or nonionic. An ionic, or polar, compound forms free ions when dissolved in water, making the water a more conductive path. A nonionic substance does not form free ions, nor increase the water’s conductivity. Ionic contaminants are usually processing residue such as flux activators, fingerprints, and etching or plating salts.Cure: A chemical reaction that hardens and changes the physical properties of a material(s).Deterioration: (as in the context of the condition of stored polymer materials) A change in the material that can be observed prior to its use, or during use, that indicates it no longer meets its performance requirements. Deteriorated in this context includes degraded or separated.Dielectric: A material with a high resistance to the flow of electrical current, and which is capable of being polarized by an electrical field.Dielectric Strength: The maximum voltage that a dielectric can withstand under specified conditions without resulting in a voltage breakdown, usually expressed as volts per unit dimension.Diluent: Any material that reduces the concentration of the fundamental resin; usually a liquid added to the resin to afford lower viscosity.Embedment: The complete encasement of a component or module in a resin. Equivalent to “encapsulation.”Encapsulation: The complete encasement of a component or module in a resin. Encapsulation is equivalent to “potting,” “embedment,” and “molding.”Engineering Documentation: Drawings and specifications which provide instructions, design features, requirements, acceptance criteria, and other documentation to invoke and/or modify requirements.Filler: A material added to polymers in order to reduce cost or modify physical properties.Fillet: A smooth, generally concave, buildup of material between two surfaces (e.g., a buildup of conformal coating material between a part and the printed wiring board (PWB)).Flatpack: A part with two straight rows of leads (normally on 1.27mm (0.050 inch) centers) that are parallel to the part body.Flux: A chemically-active compound which, when heated, removes minor surface oxidation, minimizes oxidation of the basis metal, and promotes the formation of an intermetallic layer between solder and basis metal.Gelling: Formation of a semi-solid system consisting of a network of solid aggregates in which liquid is held; the initial gel-like solid phase that develops during the formation of a resin from a liquid.Glass Transition Temperature (Tg): The approximate midpoint of the temperature range over which the glass transition takes place. The glass transition is a reversible change in an amorphous polymer or in amorphous regions of a partially crystalline polymer from (or to) a viscous or rubbery condition to (or from) a hard and relatively brittle one. Not only do hardness and brittleness undergo rapid changes in this temperature region, but other properties, such as dissipation factor, thermal expansibility, and specific heat, also change rapidly. The glass transition has its origin in short scale segmental motion involving intramolecular rotation of the main chain, and, if present, side chains or pendant groups. Moreover, the observed transition temperature can vary significantly depending on the specific property chosen for observation andon details of the experimental technique (for example, rate of heating, frequency). Therefore, the observed Tg should be considered only an estimate.Impregnation: An encapsulation process that results in complete saturation of the unit with the insulating material to include penetration and filling of every void replacing all air and gasses.Lifting: Any separation of conformal coating from the PWA.Measling: A condition at the interface of the conformal coating and base material, in the form of whitish spots or patches which reveal a separation of the conformal coating from the surface of the printed wiring board or from the surface of attached components or from both.Mix Record: A record of the procedure followed for mixing the polymeric compounds.Module: A separable unit in a packaging scheme.Molding: The complete encasement of a component or module in a resin. Equivalent to “encapsulation.”Offgassing: Deaeration or other gaseous emission from a liquid or solid material when exposed to reduced pressure, heat, or both that may affect crew members. Reference NASA-STD-6001.Outgassing: Gaseous emission from a liquid or solid material when exposed to reduced pressure, heat, or both.Part Lead: The conductor attached to a part.Peeling: The separation of conformal coating from the PWA, usually due to improper preparation or abrasion. Peeling is distinguished from lifting in that the layer of conformal coating is not continuous.Polymer: A compound of high molecular weight that is derived from either the joining together of many small similar or dissimilar organic molecules or by the condensation of many small molecules by the elimination of water, alcohol, or a solvent.Potting: The complete encasement of a component or module in a resin. Equivalent to “encapsulation.”Printed Wiring Assembly (PWA): The PWA consists of the PWB, components, and associated hardware and materials.Printed Wiring Board (PWB): A pattern of conductors printed (screened) onto the surface of an insulating base to provide interconnection for parts.Repair(ing): The act of restoring the functional capability of a defective article in a manner that precludes compliance of the article with applicable drawings or specifications.Resin: Generally, any synthetic organic material produced by polymerization.Rework: The act of reprocessing noncomplying articles, through the use of original or alternate equivalent processing, in a manner that assures compliance of the article with applicable drawings or specifications.Shall: Signifies a requirement statement herein.Should: Signifies statement of a recommended practice herein.Squeeze-out: The resin and/or reinforcement that is visible at the edges of a bond.Staking: The process of bonding and securing components or parts to PWB’s and electronic assemblies by means of an adhesive material.Staking Compound: An electrically nonconductive adhesive material used for additional support.Stress Relief: The formed portion of a conductor that provides sufficient length to minimize stress between terminations.Substrate: That surface upon which an adhesive is spread for any purpose, such as coating; a broader term than “adherent.”Supplier: In-house NASA, NASA contractors, and subtier contractors.Test Specimen: A sample of the same material processed using the same method, at the same time, and under the same conditions as the original end item product. It used as a quality record of the hardness and cure achieved with the particular material batch and the operations performed.Traceability Code: The code uniquely identifying the production lot by the manufacturer, equivalent to batch code, lot code, or date code.Transmissivity: The fractional quantity of incident radiation transmitted by matter. Viscosity: A measure of the resistance of a material to flow under stress.4. GENERAL REQUIREMENTS4.1 G eneral4.1.1 Implementation. NASA quality assurance personnel will advise and assist suppliers, NASA personnel, and delegated agencies in the proper and effective implementation of the provisions of this publication. Effective implementation includes establishing a system that will identify each inspection point and provide records.4.1.2 Changes in Requirements. When related requirements or changes in requirements are specified, NASA quality assurance personnel will assure that the Government agency delegated to inspect at the supplier’s site of fabrication has received full instructions so that the work will be inspected to actual contract requirements.4.1.3 Nonstandard Processes, Materials, or Parts. When the supplier intends to use processes, materials, or parts not covered by this standard, the supplier shall document the details of fabrication and inspection, including acceptance and rejection criteria, and provide the documentation along with appropriate test data to the procuring NASA Center for approval prior to use (Requirement).4.1.4 Proactive Work Stoppages. If at any time during any phase of polymeric applications, a condition should arise that any responsible party, including the operator, inspector, or manager, feels may damage or in any way affect the reliability of the hardware, the work shall be halted until that condition has been reviewed and resolved (Requirement).4.1.5 Requirement Flow Down. The prime contractors are responsible for delegating the requirements herein to their subtier suppliers as required (Requirement).4.2 D ocumentation4.2.1 The supplier shall document the methods and procedures proposed to incorporate the requirements of this standard into the design, fabrication, and inspection of staking, conformal coating, bonding, and encapsulation applications involved in the contract or purchase order (Requirement).4.2.2 Staking material shall be applied as defined herein and as defined by the additions or previously approved exceptions documented on the engineering drawings (See 1.3 and 1.4). Fabrication shall always follow the instructions of the engineering drawing. Instructions for staking on the engineering drawings shall include, as a minimum, the staking material and the locations to be staked (Requirement).4.2.3 Documents required herein, except as specified by paragraph 4.1.3, shall be submitted to the procuring NASA Center, or its designated representative, as required by the contract or purchase order (Requirement).4.2.4 Applicable supplier polymeric applications program documents, or portions thereof, accepted on other NASA contracts shall be included to avoid duplication of effort (Requirement).4.3 R ework and Repair4.3.1 Rework. Rework is permissible unless excluded by other provisions of the contract.4.3.1.1 All rework shall meet the requirements of this publication and approved engineering documentation (Requirement).4.3.1.2 The discrepancies shall be documented before rework is performed (Requirement).4.3.1.3 Rework procedures shall be approved prior to performing rework by the procuring NASA Center or its designated representative (Requirement).4.3.2 Repair.4.3.2.1 Repairs shall be made only in compliance with applicable contractual requirements and after authorization for each incident by the procuring NASA Center (Requirement).4.3.2.2 Repairs shall be accomplished using documented procedures previously approved by the procuring NASA Center (Requirement).4.3.2.3 For in-house NASA projects, repairs shall be authorized for each incident by the Project Office and the Project quality technical lead (Requirement).4.3.2.4 Repair is not rework.4.4 E lectrostatic Discharge RequirementsElectrostatic Discharge (ESD) requirements shall be in accordance with ANSI/ESD S20.20 (Requirement).4.5 S election and Approval Requirements for Polymeric Materials4.5.1 Minimum Criteria for Material Selection. The polymeric material(s) shall be selected in accordance with the following:a. Workable using the processes described herein such that the intended performance of the polymer is realized in the application. This includes continuous and consistent coverage for conformal coating, material volume control for staking material, and bond line control for bonding materials (Requirement).b. Suitable to the complexity of the assembly and the mission lifetime defined by the project (Requirement).c. Compatible with, and adheres to, the intended substrates (including the PWB, electrical, electronic, and electromechanical (EEE) parts, jumper wires, cable ties, metal brackets, enclosure surfaces) (Requirement).d. Stable with respect to moisture exposure, the project’s test, operating, and storage temperature range, and vacuum conditions (including thermal-vacuum). Other environmental conditions may be applicable such as ionizing radiation and UV radiation (Requirement).e. In vacuum or low-pressure compartments, does not release greater than 1.0 percent total mass loss (TML) and 0.1 percent collected volatile condensable material (CVCM) when tested in accordance with ASTM-E-595 and Project requirements (Requirement).。