A Computational Method for Resolving Ambiguities in Coordinate Structures
数字示波器外文翻译文献
数字示波器外文翻译文献(文档含中英文对照即英文原文和中文翻译)原文:Design and FPGA implementation of a wireless hyperchaotic communication system for secure real-time image transmission AbstractIn this paper, we propose and demonstrate experimentally a new wireless digital encryption hyperchaotic communication system based on radio frequency (RF) communication protocols for secure real-time data or image transmission. A reconfigurable hardware architecture is developed to ensure the interconnection between two field programmable gate array developmentplatforms through XBee RF modules. To ensure the synchronization and encryption of data between the transmitter and the receiver, a feedback masking hyperchaotic synchronization technique based on a dynamic feedback modulation has been implemented to digitally synchronize the encrypter hyperchaotic systems. The obtained experimental results show the relevance of the idea of combining XBee (Zigbee or Wireless Fidelity) protocol, known for its high noise immunity, to secure hyperchaotic communications. In fact, we have recovered the information data or image correctly after real-time encrypted data or image transmission tests at a maximum distance (indoor range) of more than 30 m and with maximum digital modulation rate of 625,000 baud allowing a wireless encrypted video transmission rate of 25 images per second with a spatial resolution of 128 ×128 pixels. The obtained performance of the communication system is suitable for secure data or image transmissions in wireless sensor networks.IntroductionOver the past decades, the confidentiality of multimedia communications such as audio, images, and video has become increasingly important since communications of digital products over the network (wired/wireless) occur more frequently. Therefore, the need for secure data and transmission is increasing dramatically and defined by the required levels of security depending on the purpose of communication. To meet these requirements, a wide variety of cryptographic algorithms have been proposed. In this context, the main challenge of stream cipher cryptography relates to the generation of long unpredictable key sequences. More precisely, the sequence has to be random, its period must be large, and the various patterns of a given length must be uniformly distributed over the sequence. Traditional ciphers like DES, 3DES, IDEA, RSA, or AES are less efficient for real-time secure multimedia data encryption systems and exhibit some drawbacks and weakness in the high streamdata encryption. Indeed, the increase and availability of a high-power computation machine allow a force brute attack against these ciphers. Moreover, for some applications which require a high-levelcomputation and where a large computational time and high computing power are needed (for example, encryption of large digital images), these cryptosystems suffer from low-level efficiency. Consequently, these encryption schemes are not suitable for many high-speed applications due to their slow speed in real-time processing and some other issues such as in the handling of various data formatting. Over the recent years, considerable researches have been taken to develop new chaotic or hyperchaotic systems and for their promising applications in real-time encryption and communication. In fact, it has been shown that chaotic systems are good candidates for designing cryptosystems with desired properties. The most prominent is sensitivity dependence on initial conditions and system parameters, and unpredictable trajectories.Furthermore, chaos-based and other dynamical systembased algorithms have many important properties such as the pseudorandom properties, ergodicity and nonperiodicity. These properties meet some requirements such as sensitivity to keys, diffusion, and mixing in the cryptographic context. Therefore, chaotic dynamics is expected to provide a fast and easy way for building superior performance cryptosystems, and the properties of chaotic maps such as sensitivity to initial conditions and random-like behavior have attracted the attention to develop data encryption algorithms suitable for secure multimedia communications. Until recently, chaotic communication has been a subject of major interest in the field of wireless communications. Many techniques based on chaos have been proposed such as additive chaos masking (ACM), where the analog message signal is added to the output of the chaos generator within the transmitter. In, chaos shift keying is used where the binary message signal selects the carrier signal from two or more different chaotic attractors. Authors use chaotic modulation where the message information modulates a parameter of the chaotic generator. Chaos control methods rely on the fact that small perturbations cause the symbolic dynamics of a chaotic system to track a prescribed symbol sequence. In, the receiver system is designed in an inverse manner to ensure the recovery of theencryption signal. An impulsive synchronization scheme is employed to synchronize chaotic transmitters and receivers. However, all of these techniques do not provide a real and practical solution to the challenging issue of chaotic communication which is based on extreme sensitivity of chaotic synchronization to both the additive channel noise and parameter mismatches. Precisely, since chaos is sensitive to small variations of its initial conditions and parameters, it is very difficult to synchronize two chaotic systems in a communication scheme. Some proposed synchronization techniques have improved the robustness to parameter mismatches as reported in, where impulsive chaotic synchronization and an open-loop-closed-loopbased coupling scheme are proposed, respectively. Other authors proposed to improve the robustness of chaotic synchronization to channel noise, where a coupled lattice instead of coupled single maps is used to decrease the master-slave synchronization error. In, symbolic dynamics-based noise reduction and coding are proposed. Some research into equalization algorithms for chaotic communication systems are also proposed. For other related results in the literature, see. However, none of them were tested through a real channel under real transmission conditions. Digital synchronization can overcome the failed attempts to realize experimentally a performed chaotic communication system. In particular, when techniques exhibit any difference between the master/transmitter and slave/receiver systems, it is due to additive information or noise channel (disturbed chaotic dynamics) which breaks the symmetry between the two systems, leading to an accurate non-recovery of the transmitted information signal at the receiver. In, an original solution to the hard problem of chaotic synchronization high sensibility to channel noise has been proposed. This solution, based on a controlled digital regenerated chaotic signal at the receiver, has been tested and validated experimentally in a real channel noise environment through a realized wireless digital chaotic communication system based on zonal intercommunication global-standard, where battery life was long, which was economical to deploy and which exhibited efficient use of resources, knownas the ZigBee protocol. However, this synchronization technique becomes sensible to high channel noise from a higher transmission rate of 115 kbps, limiting the use of the ZigBee and Wireless Fidelity (Wi-Fi) protocols which permit wireless transmissions up to 250 kbps and 65 Mbps, respectively.Consequently, no reliable commercial chaos-based communication system is used to date to the best of our knowledge. Therefore, there are still plentiful issues to be resolved before chaos-based systems can be put into practical use. To overcome these drawbacks, we propose in this paper a digital feedback hyperchaotic synchronization and suggest the use of advanced wireless communication technologies, characterized by high noise immunity, to exploit digital hyperchaotic modulation advantages for robust secure data transmissions. In this context, as results of the rapid growth of communication technologies, in terms of reliability and resistance to channel noise, an interesting communication protocol for wireless personal area networks (WPANs, i.e., ZigBee or ZigBee Pro Low-Rate-WPAN protocols) and wireless local area network (WLAN, i.e., Wi-Fi protocol WLAN) is developed. These protocols are identified by the IEEE 802.15.4 and IEEE 802.11 standards and known under the name ZigBee and Wi-Fi communication protocols, respectively. These protocols are designed to communicate data through hostile Radio Frequency (RF) environments and to provide an easy-to-use wireless data solution characterized by secure, low-power, and reliable wireless network architectures. These properties are very attractive for resolving the problems of chaotic communications especially the high noise immunity property. Hence, our idea is to associate chaotic communication with theWLAN or WPAN communication protocols. However, this association needs a numerical generation of the chaotic behavior since the XBee protocol is based on digital communications.In the hardware area, advanced modern digital signal processing devices, such as field programmable gate array (FPGA), have been widely used to generate numerically the chaotic dynamics or the encryption keys. The advantage of these techniques is that the parameter mismatch problem does not existcontrary to the analog techniques. In addition, they offer a large possible integration of chaotic systems in the most recent digital communication technologies such as the ZigBee communication protocol. In this paper, a wireless hyperchaotic communication system based on dynamic feedback modulation and RF XBee protocols is investigated and realized experimentally. The transmitter and the receiver are implemented separately on two Xilinx Virtex-II Pro circuits and connected with the XBee RF module based on the Wi-Fi or ZigBee protocols. To ensure and maintain this connection, we have developed a VHSIC (very high speed integrated circuit) hardware description language (VHDL)-based hardware architecture to adapt the implemented hyperchaotic generators, at the transmitter and receiver, to the XBee communication protocol. Note that the XBee modules interface to a host device through a logic-level asynchronous serial port. Through its serial port, the module can communicate with any logic and voltage-compatible Universal Asynchronous Receiver/Transmitter (UART). The used hyperchaotic generator is the well-known and the most investigated hyperchaotic Lorenz system. This hyperchaotic key generator is implemented on FPGA technology using an extension of the technique developed in for three-dimensional (3D) chaotic systems. This technique is optimal since it uses directly VHDL description of a numerical resolution method of continuous chaotic system models. A number of transmission tests are carried out for different distances between the transmitter and receiver. The real-time results obtained validate the proposed hardware architecture. Furthermore, it demonstrates the efficiency of the proposed solution consisting on the association of wireless protocols to hyperchaotic modulation in order to build a reliable digital encrypted data or image hyperchaotic communication system.Hyperchaotic synchronization and encryption techniqueContrary to a trigger-based slave/receiver chaotic synchronization by the transmitted chaotic masking signal, which limits the performance of the rate synchronization transmission, we propose a digital feedback hyperchaoticsynchronization (FHS). More precisely, we investigate a new scheme for the secured transmission of information based on master-slave synchronization of hyperchaotic systems, using unknown input observers. The proposed digital communication system is based on the FHS through a dynamic feedback modulation (DFM) technique between two Lorenz hyperchaotic generators. This technique is an extension and improvement of the one developed in for synchronizing two 3D continuous chaotic systems in the case of a wired connection.The proposed digital feedback communication scheme synchronizes the master/transmitter and the slave/receiver by the injection of the transmitted masking signal in the hyperchaotic dynamics of the slave/receiver. The basic idea of the FHS is to transmit a hyperchaotic drive signal S(t) after additive masking with a hyperchaotic signal x(t) of the master (transmitter) system (x , y , z ,w ). Hyperchaotic drive signal is then injected both in the three subsystems (y , z ,w ) and (r r r w z y ,,). The subscript r represents the slave or receiver system (r r r r w z y x ,,,). At the receiver, the slave system regenerates the chaotic signal )(t x r and a synchronization is obtained between two trajectories x(t) and )(t x r if()()0||lim =-∞→t X t X r t (1) This technique can be applied to chaotic modulation. In our case, it is used for generating hyperchaotic keys for stream cipher communications, where the synchronization between the encrypter and the decrypter is very important. Therefore, at the transmitter, the transmitted signal after the additive hyperchaos masking (digital modulation) isS(t) = x(t) + d(t). (2)where d(t) is the information signal and x(t) is the hyperchaotic carrier. At the receiver, after synchronization of the regenerated hyperchaotic signal )(t x rwith the received signal )(t S r and the demodulation operation, we can recover the information signal d(t) correctly as follows:)()()(t x t S t d r r -=. (3)Therefore, the slave/receiver will generate a hyperchaotic behavior identical to that of the master/transmitter allowing to recover correctly the information signal after the demodulation operation. The advantageof this technique is that the information signal d(t) doesnot perturb the hyperchaotic generator dynamics, contraryto the ACM-based techniques of and, because d(t) is injected at both the master/transmitter and slave/receiver after the additive hyperchaotic masking. Thus, for small values of information magnitude, the information will be recovered correctly. It should be noted that we have already confirmed this advantage by testing experimentally the HS-DFM technique performances for synchronizing hyperchaotic systems (four-dimensional (4D) continuous chaotic systems) in the case of wired connection between two Virtex-II Pro development platforms. After many experimental tests and from the obtained real-time results, we concluded that the HS-DFM is very suitable for wired digital chaotic communication systems. However, in the present work, one of the objectives is to test and study the performances of the HS-DFM technique in the presence of channel noise through real-time wireless communication tests. To performthe proposed approach, a digital implementation of the master and slave hyperchaotic systems is required. Therefore, we investigate the hardware implementation of the proposed FHS-DFM technique between two Lorenz hyperchaotic generators using FPGA. To achieve this objective, we propose the following details of the proposed architecture.译文:无线超混沌通信系统安全的实时图像传输的设计和FPGA实现摘要在本文中，我们提出并论证了一种基于无线电频率通信协议对数据或图像安全实时传输的新的无线数字超混沌加密通信系统。
ai的理解之桥英文演讲范文
ai的理解之桥英文演讲范文The Bridge of AI's Understanding.In the annals of human ingenuity, the advent ofartificial intelligence (AI) stands as a pivotal moment, a testament to our insatiable quest for knowledge and progress. As we venture further into the realm of AI, we encounter a fundamental challenge: the need to bridge the gap between human understanding and machine cognition.The human mind operates with an intuitive grasp of language, context, and common sense that often eludes AI systems. This cognitive divide poses a significant barrier to AI's ability to fully comprehend and engage with the complexities of human communication and reasoning.To overcome this challenge, we must construct a bridge of understanding, a conceptual framework that enables AI to traverse the chasm between its computational prowess and the nuanced world of human experience. This bridgecomprises several key elements:Natural Language Processing (NLP):NLP empowers AI systems to analyze, interpret, and generate human language. By leveraging advanced algorithms and vast datasets, NLP enables AI to extract meaning from text, dialogue, and other linguistic inputs. Thiscapability is essential for AI to understand the intentions, sentiments, and knowledge conveyed through language.Machine Learning (ML):ML algorithms allow AI systems to learn from data, identify patterns, and make predictions. Through supervised learning, AI can be trained on labeled datasets torecognize objects, classify information, and solve problems. Unsupervised learning, on the other hand, enables AI to extract insights from unlabeled data, revealing hidden structures and relationships.Knowledge Graphs:Knowledge graphs are vast networks of interconnected facts and concepts that represent the world's knowledge. By incorporating knowledge graphs into AI systems, we provide them with a structured understanding of the world, enabling them to reason over complex relationships and infer new knowledge.Machine Comprehension:Machine comprehension tasks evaluate AI's ability to read and understand human-written text. These tasks challenge AI systems to extract specific facts, answer questions, and make inferences based on the provided text. Machine comprehension is crucial for AI's ability to engage in meaningful conversations and provide informative responses.Common Sense Reasoning:Common sense refers to the shared knowledge and assumptions that humans rely on in everyday life. AIsystems must be equipped with common sense reasoning capabilities to navigate the world in a logical and sensible manner. This involves inferring missing information, resolving ambiguities, and making plausible assumptions based on context.Bridging the Gap:By integrating these elements into AI systems, we begin to create a bridge that connects human understanding to machine cognition. NLP provides the foundation for language comprehension, while ML and knowledge graphs furnish AI with the ability to learn and reason over vast amounts of information. Machine comprehension equips AI with the capacity to extract meaning from text, while common sense reasoning enables AI to make logical inferences and navigate the complexities of human communication.The construction of this bridge of understanding is not without its challenges. AI systems must be able to process vast amounts of data, handle ambiguity and uncertainty, and avoid bias and discrimination. Ensuring the ethical andresponsible development of AI is also paramount.Despite these challenges, the potential benefits of bridging the gap between human understanding and machine cognition are immense. AI systems could revolutionize healthcare, transportation, education, and countless other domains. By empowering AI with the ability to truly understand human language, context, and common sense, we unlock the potential for AI to become a transformative force for good.As we embark on this journey, we must proceed with both ambition and caution. The bridge of AI's understanding is not an end in itself but a means to foster innovation, solve global challenges, and enhance the human experience. It is a testament to the enduring human spirit of exploration and our unwavering belief in the power of knowledge.。
机器人顶刊论文
机器人顶刊论文机器人领域内除开science robotics以外，TRO和IJRR是机器人领域的两大顶刊，最近师弟在选择研究方向，因此对两大顶刊的论文做了整理。
TRO的全称IEEE Transactions on Robotics，是IEEE旗下机器人与自动化协会的汇刊，最新的影响因子为6.123。
ISSUE 61 An End-to-End Approach to Self-Folding Origami Structures2 Continuous-Time Visual-Inertial Odometry for Event Cameras3 Multicontact Locomotion of Legged Robots4 On the Combined Inverse-Dynamics/Passivity-Based Control of Elastic-Joint Robots5 Control of Magnetic Microrobot Teams for Temporal Micromanipulation Tasks6 Supervisory Control of Multirotor Vehicles in Challenging Conditions Using Inertial Measurements7 Robust Ballistic Catching: A Hybrid System Stabilization Problem8 Discrete Cosserat Approach for Multisection Soft Manipulator Dynamics9 Anonymous Hedonic Game for Task Allocation in a Large-Scale Multiple Agent System10 Multimodal Sensorimotor Integration for Expert-in-the-Loop Telerobotic Surgical Training11 Fast, Generic, and Reliable Control and Simulation of Soft Robots Using Model Order Reduction12 A Path/Surface Following Control Approach to Generate Virtual Fixtures13 Modeling and Implementation of the McKibben Actuator in Hydraulic Systems14 Information-Theoretic Model Predictive Control: Theory and Applications to Autonomous Driving15 Robust Planar Odometry Based on Symmetric Range Flow and Multiscan Alignment16 Accelerated Sensorimotor Learning of Compliant Movement Primitives17 Clock-Torqued Rolling SLIP Model and Its Application to Variable-Speed Running in aHexapod Robot18 On the Covariance of X in AX=XB19 Safe Testing of Electrical Diathermy Cutting Using a New Generation Soft ManipulatorISSUE 51 Toward Dexterous Manipulation With Augmented Adaptive Synergies: The Pisa/IIT SoftHand 22 Efficient Equilibrium Testing Under Adhesion and Anisotropy Using Empirical Contact Force Models3 Force, Impedance, and Trajectory Learning for Contact Tooling and Haptic Identification4 An Ankle–Foot Prosthesis Emulator With Control of Plantarflexion and Inversion–Eversion Torque5 SLAP: Simultaneous Localization and Planning Under Uncertainty via Dynamic Replanning in Belief Space6 An Analytical Loading Model for n -Tendon Continuum Robots7 A Direct Dense Visual Servoing Approach Using Photometric Moments8 Computational Design of Robotic Devices From High-Level Motion Specifications9 Multicontact Postures Computation on Manifolds10 Stiffness Modulation in an Elastic Articulated-Cable Leg-Orthosis Emulator: Theory and Experiment11 Human–Robot Communications of Probabilistic Beliefs via a Dirichlet Process Mixture of Statements12 Multirobot Reconnection on Graphs: Problem, Complexity, and Algorithms13 Robust Intrinsic and Extrinsic Calibration of RGB-D Cameras14 Reactive Trajectory Generation for Multiple Vehicles in Unknown Environments With Wind Disturbances15 Resource-Aware Large-Scale Cooperative Three-Dimensional Mapping Using Multiple Mobile Devices16 Control of Planar Spring–Mass Running Through Virtual Tuning of Radial Leg Damping17 Gait Design for a Snake Robot by Connecting Curve Segments and ExperimentalDemonstration18 Server-Assisted Distributed Cooperative Localization Over Unreliable Communication Links19 Realization of Smooth Pursuit for a Quantized Compliant Camera Positioning SystemISSUE 41 A Survey on Aerial Swarm Robotics2 Trajectory Planning for Quadrotor Swarms3 A Distributed Control Approach to Formation Balancing and Maneuvering of Multiple Multirotor UAVs4 Joint Coverage, Connectivity, and Charging Strategies for Distributed UAV Networks5 Robotic Herding of a Flock of Birds Using an Unmanned Aerial Vehicle6 Agile Coordination and Assistive Collision Avoidance for Quadrotor Swarms Using Virtual Structures7 Decentralized Trajectory Tracking Control for Soft Robots Interacting With the Environment8 Resilient, Provably-Correct, and High-Level Robot Behaviors9 Humanoid Dynamic Synchronization Through Whole-Body Bilateral Feedback Teleoperation10 Informed Sampling for Asymptotically Optimal Path Planning11 Robust Tactile Descriptors for Discriminating Objects From Textural Properties via Artificial Robotic Skin12 VINS-Mono: A Robust and Versatile Monocular Visual-Inertial State Estimator13 Zero Step Capturability for Legged Robots in Multicontact14 Fast Gait Mode Detection and Assistive Torque Control of an Exoskeletal Robotic Orthosis for Walking Assistance15 Physically Plausible Wrench Decomposition for Multieffector Object Manipulation16 Considering Uncertainty in Optimal Robot Control Through High-Order Cost Statistics17 Multirobot Data Gathering Under Buffer Constraints and Intermittent Communication18 Image-Guided Dual Master–Slave Robotic System for Maxillary Sinus Surgery19 Modeling and Interpolation of the Ambient Magnetic Field by Gaussian Processes20 Periodic Trajectory Planning Beyond the Static Workspace for 6-DOF Cable-Suspended Parallel Robots1 Computationally Efficient Trajectory Generation for Fully Actuated Multirotor Vehicles2 Aural Servo: Sensor-Based Control From Robot Audition3 An Efficient Acyclic Contact Planner for Multiped Robots4 Dimensionality Reduction for Dynamic Movement Primitives and Application to Bimanual Manipulation of Clothes5 Resolving Occlusion in Active Visual Target Search of High-Dimensional Robotic Systems6 Constraint Gaussian Filter With Virtual Measurement for On-Line Camera-Odometry Calibration7 A New Approach to Time-Optimal Path Parameterization Based on Reachability Analysis8 Failure Recovery in Robot–Human Object Handover9 Efficient and Stable Locomotion for Impulse-Actuated Robots Using Strictly Convex Foot Shapes10 Continuous-Phase Control of a Powered Knee–Ankle Prosthesis: Amputee Experiments Across Speeds and Inclines11 Fundamental Actuation Properties of Multirotors: Force–Moment Decoupling and Fail–Safe Robustness12 Symmetric Subspace Motion Generators13 Recovering Stable Scale in Monocular SLAM Using Object-Supplemented Bundle Adjustment14 Toward Controllable Hydraulic Coupling of Joints in a Wearable Robot15 Geometric Construction-Based Realization of Spatial Elastic Behaviors in Parallel and Serial Manipulators16 Dynamic Point-to-Point Trajectory Planning Beyond the Static Workspace for Six-DOF Cable-Suspended Parallel Robots17 Investigation of the Coin Snapping Phenomenon in Linearly Compliant Robot Grasps18 Target Tracking in the Presence of Intermittent Measurements via Motion Model Learning19 Point-Wise Fusion of Distributed Gaussian Process Experts (FuDGE) Using a Fully Decentralized Robot Team Operating in Communication-Devoid Environment20 On the Importance of Uncertainty Representation in Active SLAM1 Robust Visual Localization Across Seasons2 Grasping Without Squeezing: Design and Modeling of Shear-Activated Grippers3 Elastic Structure Preserving (ESP) Control for Compliantly Actuated Robots4 The Boundaries of Walking Stability: Viability and Controllability of Simple Models5 A Novel Robotic Platform for Aerial Manipulation Using Quadrotors as Rotating Thrust Generators6 Dynamic Humanoid Locomotion: A Scalable Formulation for HZD Gait Optimization7 3-D Robust Stability Polyhedron in Multicontact8 Cooperative Collision Avoidance for Nonholonomic Robots9 A Physics-Based Power Model for Skid-Steered Wheeled Mobile Robots10 Formation Control of Nonholonomic Mobile Robots Without Position and Velocity Measurements11 Online Identification of Environment Hunt–Crossley Models Using Polynomial Linearization12 Coordinated Search With Multiple Robots Arranged in Line Formations13 Cable-Based Robotic Crane (CBRC): Design and Implementation of Overhead Traveling Cranes Based on Variable Radius Drums14 Online Approximate Optimal Station Keeping of a Marine Craft in the Presence of an Irrotational Current15 Ultrahigh-Precision Rotational Positioning Under a Microscope: Nanorobotic System, Modeling, Control, and Applications16 Adaptive Gain Control Strategy for Constant Optical Flow Divergence Landing17 Controlling Noncooperative Herds with Robotic Herders18 ε⋆: An Online Coverage Path Planning Algorithm19 Full-Pose Tracking Control for Aerial Robotic Systems With Laterally Bounded Input Force20 Comparative Peg-in-Hole Testing of a Force-Based Manipulation Controlled Robotic HandISSUE 11 Development of the Humanoid Disaster Response Platform DRC-HUBO+2 Active Stiffness Tuning of a Spring-Based Continuum Robot for MRI-Guided Neurosurgery3 Parallel Continuum Robots: Modeling, Analysis, and Actuation-Based Force Sensing4 A Rationale for Acceleration Feedback in Force Control of Series Elastic Actuators5 Real-Time Area Coverage and Target Localization Using Receding-Horizon Ergodic Exploration6 Interaction Between Inertia, Viscosity, and Elasticity in Soft Robotic Actuator With Fluidic Network7 Exploiting Elastic Energy Storage for “Blind”Cyclic Manipulation: Modeling, Stability Analysis, Control, and Experiments for Dribbling8 Enhance In-Hand Dexterous Micromanipulation by Exploiting Adhesion Forces9 Trajectory Deformations From Physical Human–Robot Interaction10 Robotic Manipulation of a Rotating Chain11 Design Methodology for Constructing Multimaterial Origami Robots and Machines12 Dynamically Consistent Online Adaptation of Fast Motions for Robotic Manipulators13 A Controller for Guiding Leg Movement During Overground Walking With a Lower Limb Exoskeleton14 Direct Force-Reflecting Two-Layer Approach for Passive Bilateral Teleoperation With Time Delays15 Steering a Swarm of Particles Using Global Inputs and Swarm Statistics16 Fast Scheduling of Robot Teams Performing Tasks With Temporospatial Constraints17 A Three-Dimensional Magnetic Tweezer System for Intraembryonic Navigation and Measurement18 Adaptive Compensation of Multiple Actuator Faults for Two Physically Linked 2WD Robots19 General Lagrange-Type Jacobian Inverse for Nonholonomic Robotic Systems20 Asymmetric Bimanual Control of Dual-Arm Exoskeletons for Human-Cooperative Manipulations21 Fourier-Based Shape Servoing: A New Feedback Method to Actively Deform Soft Objects into Desired 2-D Image Contours22 Hierarchical Force and Positioning Task Specification for Indirect Force Controlled Robots。
植物多倍体基因组组装流程
植物多倍体基因组组装流程Plant polyploidy refers to the condition where plants have multiple sets of chromosomes. This phenomenon is quite common in the plant kingdom and has been found in various plant species. Polyploidy can occur naturally or can be induced artificially through breeding techniques. Understanding the genome of polyploid plants is crucial for plant breeding, genetic studies, and crop improvement. However, the assembly of polyploid genomes posessignificant challenges due to the presence of multiple homologous chromosomes and repetitive sequences. In this article, we will discuss the general workflow and challenges involved in the assembly of polyploid plant genomes.The first step in assembling a polyploid plant genome is the generation of high-quality sequencing data. Next-generation sequencing technologies, such as Illumina sequencing, have revolutionized the field of genomics by providing massive amounts of short-read data at arelatively low cost. These short reads are generated from fragmented DNA and need to be assembled into longer contiguous sequences, known as contigs. However, the assembly of polyploid genomes using short-read data alone is challenging due to the presence of repetitive sequences, which can result in misassemblies and collapsed repeats.To overcome this challenge, researchers often employ a combination of short-read and long-read sequencing technologies. Long-read sequencing platforms, such as Pacific Biosciences (PacBio) and Oxford Nanopore Technologies (ONT), generate much longer reads that can span repetitive regions and provide valuable informationfor resolving complex genomic structures. These long reads can be used to scaffold the short-read assembly, improving the contiguity and accuracy of the final genome assembly.Once the sequencing data is generated, the next step is to preprocess and clean the data to remove low-quality reads, adapter sequences, and other artifacts. This is typically done using specialized software tools, such as Trimmomatic or Cutadapt. After preprocessing, the reads areusually subjected to error correction to improve the accuracy of the assembly. Several error correction tools, such as Pilon and QuorUM, are available for this purpose.After preprocessing and error correction, the short-read and long-read data are typically assembled separately using different assembly algorithms. Short-read assemblers, such as SPAdes and Velvet, use de Bruijn graph-based algorithms to assemble the short reads into contigs. Long-read assemblers, such as Canu and Flye, employ overlap-layout-consensus (OLC) algorithms to assemble the long reads into contigs. The contigs generated from the short-read and long-read assemblies are then combined using scaffolding algorithms to produce a more complete and accurate assembly.One of the major challenges in polyploid genome assembly is the presence of homologous chromosomes and repetitive sequences. These sequences can lead to collapsed repeats and misassemblies in the assembly process. To address this, researchers often employ various strategies, such as haplotype phasing, to separate the homologouschromosomes and resolve complex genomic structures. Haplotype phasing involves assigning the short reads or long reads to their respective homologous chromosomes, allowing for the reconstruction of individual chromosome sequences.Another challenge in polyploid genome assembly is the presence of allelic variation and heterozygosity. Polyploid plants can have multiple copies of each gene, and these copies can differ in sequence due to allelic variation. Resolving allelic variation and heterozygosity is important for accurately representing the gene content and genetic diversity of the polyploid genome. Various methods, such as read mapping and variant calling, can be used to identify and resolve allelic variation in the assembly process.In conclusion, the assembly of polyploid plant genomes is a complex and challenging task. It requires the integration of multiple sequencing technologies, preprocessing steps, and assembly algorithms to generate a high-quality assembly. The presence of homologous chromosomes, repetitive sequences, and allelic variationfurther complicates the assembly process. However, advancements in sequencing technologies and computational algorithms have greatly improved our ability to assemble and analyze polyploid plant genomes. These assemblies provide valuable resources for studying plant evolution, genetic diversity, and crop improvement.。
Aeroacoustics_气动声学(理论教程)
Aeroacoustics 气动声学翻译：岳刚伟简介本翻译英文原文源于STAR-CCM+12.02版本的帮助文件，仅供从事CFD相关领域的同学参考，译者从2010年开始从事汽车行业的CFD仿真分析工作，本翻译根据自身的理解进行，翻译过程中错误在所难免，请予以指正。
附制作的空气动力学视频，请提出指导建议，感谢！https:///x/page/w0159lk8pka.html?https:///x/page/s0156bgaa11.html?Computational aeroacoustics (CAA) is a branch of multiphysics modeling and simulation that involves identifying noise sources that are induced by fluid flow and propagation of the subsequently generated sound waves.计算气动声学（CAA）是多体物理学的建模和仿真的一个分支，包括识别流体流动和随后产生的声波的传递而产生的噪声源。
Noise sources originate from various types of flow, such as:噪声源来自于各种类型的流动，例如：Turbulent flow over solid bodies (bluff body flows)固体表面的湍流（钝体/非线性流动）Turbulent boundary layer flows (for example, automobile, aircraft components)湍流边界层流动（例如汽车、飞机部件）High-speed turbulent shear flows (for example, free jet flow) 高速湍流切变流动（例如，自由射流）High-speed impinging flows (for example, jet impingement, rocket exhaust noise)高速撞击流（如射流冲击、火箭排气噪声）Structural vibration that is induced by fluid flow (fluid-structure interactions)由流体流动（流体与结构相互作用）引起的结构振动High-speed rotating flows (for example, rotorcrafts or turbomachinery)高速旋转流（例如，直升机或涡轮机械）Turbulent combustion (reacting flows)湍流燃烧（反应流）Blast waves (explosions)爆炸波（爆炸）A typical CAA simulation requires the following components:典型的CAA仿真需要以下组件：Navier-Stokes equations for fluid flow流体流动的纳维-斯托克方程High-resolution turbulence models高精度的湍流模型Analytical or computational acoustic wave propagationmodels解析或计算声波传播模型The noise signatures at the locations of interest exhibit corresponding noise spectra—that is, the intensities of sound pressure level over a range of frequencies. The noise characteristic can be tonal noise with a distinct peak at a frequency (such as engine noise; jet impingement noise, or Noise, Vibration, and Harshness (NVH)) or broadband noise spread over a frequency range (typical of turbulence-induced noise).关注部位的噪声特征表现出相应的噪声谱，即声压级在某一频率范围内的强度。
电脑的用途 英语作文
Computers have revolutionized the way we live and work,and their uses are incredibly diverse and widespread.Here are some of the most common and impactful applications of computers in our daily lives:munication:Computers have transformed the way we communicate.Email, instant messaging,and social media platforms allow us to stay in touch with friends, family,and colleagues across the globe instantly.cation:In the educational sector,computers are used for research,online learning, and digital classrooms.They provide access to a wealth of information and enable interactive learning experiences.3.Business and Finance:Computers are integral to business operations,from managing inventory to processing transactions.They are also used in financial modeling,stock trading,and accounting.4.Entertainment:Computers have revolutionized the entertainment industry.They are used for gaming,streaming movies and music,and creating digital art and animations.5.Healthcare:In healthcare,computers are used for managing patient records,conducting research,and aiding in diagnostics and treatment plans.6.Data Analysis:Computers are essential for data collection,storage,and analysis.They help in making informed decisions in various fields such as science,marketing,and policymaking.7.Manufacturing:Computers are used to control machinery and automate processes in manufacturing,leading to increased efficiency and reduced human error.8.Transportation:Computers are used in transportation systems for navigation,traffic management,and vehicle control,including autonomous vehicles.9.Science and Research:Computers are used for complex calculations,simulations,and modeling in scientific research,helping to push the boundaries of knowledge in fields such as physics,chemistry,and biology.10.Home Automation:Computers are at the heart of smart homes,controlling lighting, heating,security systems,and appliances.11.Creative Industries:In the creative industries,computers are used for graphic design,music production,film editing,and3D modeling.12.Ecommerce:Computers have enabled the growth of online shopping,making it easier for consumers to purchase goods and services from anywhere.ernment and Public Services:Governments use computers for managing public records,providing services to citizens,and ensuring national security.14.Agriculture:Computers are used in precision farming to monitor crop health, optimize irrigation,and increase yield.15.Space Exploration:In space exploration,computers are used to control spacecraft, analyze data from space missions,and simulate space environments.In conclusion,the versatility of computers is astounding,and their influence on modern society is profound.As technology continues to advance,the applications of computers are likely to expand even further,offering new opportunities and challenges for the future.。
英语论文结论部分写作特点总结
英语论文写作论文结论部分（Conclusion）写作特点总结ConclusionConclusion是作者对所研究课题进行的总体性讨论，具有严密的科学性和客观性，反映本研究课题的价值，同时对以后的研究具有指导意义。
Conclusion与Introduction遥相呼应，因为Introduction部分介绍了本课题的研究目的，那么Conclusion要告诉读者这些目的是否达到，在研究中做了哪些工作，取得了什么结果，这些结果说明了什么问题，有何价值和意义，研究过程中存在或发现了哪些问题，原因是什么，建议如何解决等。
Conclusion的具体内容通常包含以下几个部分：(1) 概括说明本课题的研究内容、结果及其意义与价值。
(2) 比较具体地说明本研究证明了什么假设或理论，得出了什么结论，研究结果有何实用价值，有何创造性成果或见解，解决了什么实际问题，有何应用前景等。
(3) 与他人的相关研究进行比较。
(4) 本课题的局限性、不足之处，还有哪些尚待解决的问题。
(5)展望前景，或指出进一步研究的方向。
Conclusion通常使用现在时态Result和Conclusion本次选取5篇文章，第一篇，论文中的主要Result已在第2部分和第三部分中叙述，在Conclusion又重新总结了一下。
第二篇，论文中的主要Result写在Conclusion中。
第三篇，论文中的主要Result写在第3部分（3.CASE STUDIES AND RESULTS）中，Result和Conclusion是分开的。
第四篇，论文中的主要Result已第4部分的（IV. Results and Discussion）中进行叙述，Result和Conclusion是分开的。
第五篇，论文中的主要Result已第4部分的（4. Results and discussion）中进行叙述，Result 和Conclusion是分开的。
第1篇题目：An overview of NACA6-digit airfoil series characteristics with reference to airfoils forlarge wind turbine bladesIV. ConclusionsThe two-dimensional aerodynamics characteristics of the NACA 63 and 64 six-digit series of airfoils measured in the NASA LTPT have been investigated, with a view to verify RFOIL calculations at high Reynolds numbers. The following conclusions can be drawn: - The zero-lift angle of the NACA 64-618 airfoil needs to be adjusted with -0.4 degrees.- The zero-lift angle of The NACA 63-615 needs to be corrected with -0.87 degrees in the smooth case and with +1 degree in case of wrap around roughness.-The maximum lift coefficients predicted with RFOIL match the LTPT data well at Re=3x106, but under predict the Cl,max at Re=6x106 by 3.5 % , up to 6.5% at Re=9x106.-It is uncertain if the established differences in lift between experiment and calculations are caused by a constant bias in the measurements or by the fact that the RFOIL code fails to predict the right level of maximum lift.-RFOIL consistently under predicts the drag coefficient. The difference is about 9% for a wide range of airfoils and Reynolds numbers-NACA standard roughness causes a reduction in the lift coefficient of 18% to 20% for most airfoils from the NACA 64 series-The zero-lift angle of airfoil NACA 64-418 with wrap-around roughness needs a correction of +0.54 degrees.-Wind tunnel experiments and side-by-side tests in the field with one clean rotor need to be done to be able to better predict the effects of roughness.写作特点：内容：第1句，概括了文章的的主要研究内容。
ABB变压器设计与模拟软件说明书
38ABB review 3|13Title picture Simulating the detailed electromagnetic behavior of transformers is essential for good product design.Picture perfect DAnIEl SZARy, jAnuSZ DuC, BERTRAnD POulIn, DIETRICH BOnMAnn, GöRAn ERIkSSOn, THORSTEn STEInMETZ, ABDOlHAMID SHOORy – Power transformers are among the most expensive pieces of equipment in the entire electrical power network. For this reason, great effort is expended to make the design of transformers as perfect as possible. Invaluable tools in this endeavor are simulation software packages that are based on the finite element method. Simulation software not only predicts the effects of basic physics, but it also provides a way for ABB’s century of experience in transformer design to be used in the design and exploited to the fullest. This is important as different types of transformers present different challenges in terms of magnetic flux loss mechanisms, complex nonlinear behavior and idiosyncrasies of physical design. All these factors must be accommodated while keeping computational overhead within reason.Electromagnetic simulations of transformersPicture perfect 3940ABB review 3|13mal hot spots and thus shorten the life of the transformer.Whereas resistive and eddy-current losses can be accurately calculated by 2-D simu-lation, the calculation of stray losses out-side the windings is a complex 3-D prob-lem and a suitable transformer model is necessary to solve it. This model can be created by simulation software suites that are based on the finite element method. Finite element analysis (FEA) is a sophisticated tool widely used to solve engineering problems arising from electromag-netic fields, ther-mal effects, etc. In FEA, using smaller element sizes yields higher, and thus better, resolution of the problem, but also increases the computa-tional power required, so a balance must be struck between element size, degree of model detail, approximation of material properties, computing time and the preci-sion of the results.Simulation software can resolve the basic electromagnetic field situation by solving Maxwell’s equations in a finite region of space with appropriate boundary condi-tions (current excitation and conditions at the outer boundaries of the model). How-ever, the rest of the simulation depends on the input of the user. This is where ABB’s long experience in transformer design bears fruit. Nonlinear material properties and device complexity are two significant factors that drive the computational horsepower required for the software simulation of both oil-immersed and dry-type power transformers. However, a deep knowledge of power transformer design allows very accurate simulations to be made without running up against computational limits. Power transformers have a critical task: They must step the voltage up and back down on the way from the power plant to the final consumer. In a perfect world, they would be 100 percent efficient, but in reality, every transformer generates losses. In general, the so-called load losses in transformers have three com-ponents: resistive and eddy-current loss-es that appear in windings and busbars, and stray losses that are generated in the metallic parts of transformers ex-posed to magnetic fields, eg, the tank, core clamping structures and tank shielding. This unavoidable leakage of magnetic flux not only represents a loss of energy, but can also cause local ther-An accurate calculation of stray losses and their spatial distribution requires appro-priate numerical models for the loss mechanisms in the construction materials them-selves. 1 loss distribution of the steel plate for rotation angle 45 degrees 1a Computed by resolving the interior 1b Computed by SIBC technique41the loss – a procedure that would require excessive computer power for a full 3-D simulation. Fortunately, one can employ surface impedance boundary conditions (SIBCs) to significantly reduce the solution volume and thus the computer power re-quirements. Here, the interior of the metal-lic object is removed from the computa-tional domain and the effect of eddy currents flowing close to its surface is tak-en into account by specifying analytically the surface impedance – ie, the ratio be-tween electric and magnetic fields at the surface.The usefulness of the SIBC method can be illustrated. An infinitely long steel plate with a 12 × 50 mm cross-section and skin depth of 1 mm at 50 Hz can be simulated at various rotation angles in a magnetic field. The total eddy-current loss is com-puted using a full volume resolution of the plate interior (requiring 4,220 finite ele-ments for the entire computational domain) ➔1a and an SIBC formulation (requiring 1,674 finite elements)➔1b. The SIBCyields a virtually identical loss value com-pared with the full volume case ➔2. The relative gain in using SIBC is significant even for this small object and as the size increases the relative gain is magnified.At ABB, different numerical techniques for computing loss distributions in transformer construction materials are being evaluated and improved. The objective is to find the most accurate models that can be used in 3-D simulations while keeping computa-tional overhead reasonable. This is accom-plished by combining carefully controlled experimental measurements on test ob-jects with detailed simulations. Simulating stray loss An accurate calculation of stray losses and their spatial distribution requires appropri-ate numerical models for the loss mecha-nisms in the construction materials them-selves. Losses are significant in solid materials, but also in laminated materials, such as laminated steel, since stray fields are, in general, not restricted to the plane parallel to the lamination planes. In addition to ed-dy-current loss, there is also hysteresis loss in ferromagnetic materials due to mi-croscopic energy dissipation when thematerials are subjected to oscillating mag-netic fields. Furthermore, in order to com-pute the total loss distribution accurately, the model has to take into account the nonlinearity of the magnetization curve. This nonlinearity not only influences the magnetic field distribution but also, indi-rectly, the eddy current distribution. The high degree of anisotropy in laminated steel introduces additional complications that must be taken into account.The so-called skin effect also complicates matters: Eddy currents induced close to the surface of a metallic object tend to have a shielding effect, resulting in an ex-ponential decay of fields and current to-wards the interior of the object. This skin effect becomes more pronounced as con-ductivity and permeability increase, imply-ing that, in typical materials of interest, the characteristic decay length (“skin depth”) is of the order of a millimeter or less. As a consequence, the losses are concentrated in this thin layer. At first sight, it seems nec-essary to resolve the skin depth layer into several finite elements in order to compute Picture perfect Different types of advanced numerical simulations, usually based on FEA, are applied to develop and i mprove dry-type transformer technologies and products.2 Simulated total loss in the plate as a function of rotation angle. The SIBC technique gives results very close to those obtained by resolving the entire volume.3 Geometry of the power transformer simulation model (tank not shown)42ABB review 3|13insulation and cooling of the active part are performed by ambient air. Different types of advanced numerical simula-tions, usually based on FEA, are applied to develop and improve dry-type trans-former technologies and products.TriDry – dry-type transformers with triangular wound cores In contrast to conventional transformers with planar-stacked magnetic cores, the three-core legs of the TriDry experience identical magnetic conditions ➔5. Nu-merical simulation of the magnetic fields in the core are particularly challenging because an anisotropic material model is required as the permeability is very high parallel to the laminations but much low-er in the orthogonal direction ➔5. These simulations give fundamental insight into the magnetic behavior of the TriDry transformers. Also, detailed analyses of the emitted stray field intensities of TriDry transformers can be performed by nu-merical simulations. These can be re-quired to ensure legal compliance – for example, to the 1 microtesla RMS limit for transformers installed in Switzerland in sensitive areas.to make the computational load more managable.In the initial design, where the tank shunts are too far apart and of insuffi-cient height, loss densities were signifi-cantly higher directly opposite the active part, relative to other areas of the tank ➔4a. The critical regions exposed to magnetic field impact are clearly visi-ble in the figure – mainly above and be-low the magnetic shunts. Several design iterations increased shunt height and number, and decreased spacing. The losses generated in the tank conse-quently decreased by almost 40 percent. The simulations allowed the required performance to be attained while mini-mizing the extra material, and thus costs, involved ➔4b.Electromagnetic simulations of dry-type transformers The active part (consisting of the main parts: core, windings, structural compo-nents and leads) of a dry-type transform-er is not immersed in an insulation liquid, in contrast to oil-immersed power and distribution transformers. Both electric Different suggested loss modeling tech-niques for nonlinear and/or laminatedmaterials are then evaluated based onthese results.Electromagnetic simulations ofoil-immersed power transformersThe windings in autotransformers (anABB 243 MVA single-phase 512.5/230/13.8 kV type is used here for illustration)tend to produce high amounts of strayflux relative to their physical size. Thisimplies potentially high stray losses andpossible hot spots in the transformertank. However, with appropriate simula-tion and design, a tank shielding can beproduced that avoids this. In the caseshown here, magnetic shunts mountedon the tank wall were employed asshielding. Shunts are ferromagnetic steelelements that guide the flux emanatingfrom the transformer winding ends.The 3-D FEA model included all the im-portant constructional parts necessaryto carry out the magnetic simulationsand loss calculations ➔3. Because ofthe complexity of the real transformer,some simplifications were introducedThe objective is to find the most ac-curate models that can be used in 3-D simulations while keeping computa-tional overheadreasonable.4 Influence of the tank shunt geometry on the distribution of the losses generated in the transformer tank 4a Short, spaced tank shunts give high losses (right)4b longer, closer-spaced tank shunts result in lower losses (right)43Dry-type variable-speed drive transformers Variable-speed drive transformers are used to supply AC motors. The power electronics associated with these trans-formers generate current harmonics that increase winding loss, potentially leading to hot spots. This must be taken into consideration when constructing simula-tion models. A typical example of wind-ing loss simulation is shown in ➔6. Here, the relative winding loss distribution overthe end sections of the foil conductors of the two opposite winding blocks is shown for a 12-pulse transformer with two secondary windings. The winding loss at the fundamental frequency is more uniformly distributed along the conductor surface than the winding lossof the fifth harmonic frequency. This isbecause the currents of the two second-ary windings are in phase at the funda-mental frequency, resulting mainly in axi-al flux. However, these currents are inopposing phase at the fifth harmonic fre-quency, resulting in a radial flux that con-centrates losses in the winding regionnear the axial gap between them. Thiscauses hot spots, requiring the design tobe amended accordingly.Simulation successNumerical simulation of electromagnetic fields have proven to be a very powerful tool in the development and design of to-day’s transformers. Appropriate numeri-cal models facilitate, for instance, the simulation of stray losses in structural components, winding losses or core magnetization – applicable to different types of transformers.The numerical simulations described here are used in research, development and engineering by ABB and they make a significant contribution to ABB’s high-quality oil-immersed and dry-type trans-former products.Daniel Szary janusz Duc ABB Corporate Research Kraków, Poland *******************.com *****************.com Bertrand Poulin ABB Power Products, Transformers Varennes, Quebec, Canada ************************.com Dietrich Bonmann ABB Power Products, Transformers Bad Honnef, Germany ***********************.com Göran Eriksson ABB Corporate Research Västerås, Sweden ***********************.com Thorsten Steinmetz Abdolhamid Shoory ABB Corporate Research Baden-Dättwil, Switzerland *************************.com ************************.comSurface imped-ance boundary conditions (SIBCs) can significantly reduce the solu-tion volume and thus the computer power require-ments.Picture perfect 6 Electromagnetic simulations of a 12-pulse transformer; winding loss distribution over the end sections of the foil conductors6a At the fundamental frequency 6b At the fifth harmonic frequency 5 TriDry transformer and the simulated magnetic flux density distribution in its magnetic core.5a TriDry transformer 5b Magnetic flux density distribution。
phase-field modeling
Phase field modelsFrom Wikipedia, the free encyclopediaJump to: navigation, searchA phase field model is a mathematical model for solving interfacial problems. It has mainly been applied to solidification dynamics,[1]but it has also been applied to other situations such as viscous fingering,[2]fracture dynamics, [3] vesicle dynamics,[4] etc.The method substitutes boundary conditions at the interface by a partial differential equation for the evolution of an auxiliary field (the phase field) that takes the role of an order parameter. This phase field takes two distinct values (for instance +1 and −1) in each of the phases, with a smooth change between both values in the zone around the interface, which is then diffuse with a finite width.A discrete location of the interface may be defined as the collection of all points where the phase field takes a certain value (e.g., 0).A phase field model is usually constructed in such a way that in the limit of an infinitesimal interface width (the so-called sharp interface limit) the correct interfacial dynamics are recovered. This approach permits to solve the problem by integrating a set of partial differential equations for the whole system, thus avoiding theexplicit treatment of the boundary conditions at the interface.Phase field models were first introduced by Fix[5] and Langer,[6] and have experienced a growing interest in solidification and other areas.Contents∙ 1 Equations of the Phase field modelo 1.1 Variational formulationso 1.2 Sharp interface limit of the Phase field equations∙ 2 Multi Phase Field Models∙ 3 Software∙ 4 Further reading∙ 5 References[edit] Equations of the Phase field modelPhase field models are usually constructed in order to reproduce a given interfacial dynamics. For instance, in solidification problems the front dynamics is given by a diffusion equation for either concentration or temperature in the bulk and some boundary conditions at the interface (a local equilibrium condition and a conservation law),[7] which constitutes the sharp interface model.A two phase microstructure and the order parameter φ profile is shown on a line across the domain. Gradual change of order parameter from one phase to another shows diffuse nature of the interface.A number of formulations of the phase field model are based on a free energy functional depending on an order parameter (the phase field) and a diffusive field (variational formulations). Equations of the model are then obtained by using general relations of Statistical Physics. Such a functional is constructed from physical considerations, but contains a parameter or combination of parameters related to the interface width. Parameters of the model are then chosen by studying the limit of the model with this width going to zero, in such a way that one can identify this limit with the intended sharp interface model.Other formulations start by writing directly the phase field equations, without referring to any thermodynamical functional (non-variational formulations). In this case the only reference is the sharp interface model, in the sense that it should be recovered when performing the small interface width limit of the phase field model.Phase field equations in principle reproduce the interfacial dynamics when the interface width is small compared with the smallest length scale in the problem. In solidification this scale is the capillary length d o, which is a microscopic scale. From a computational point of view integration of partial differential equations resolving such a small scale is prohibitive. However, Karma and Rappel introduced the thin interface limit,[8] which permitted to relax this condition and has opened the way to practical quantitative simulations with phase field models. With the increasing power of computers and the theoretical progress in phase field modelling, phase field models have become a useful tool for the numerical simulation of interfacial problems.[edit] Variational formulationsA model for a phase field can be constructed by physical arguments if one have an explicit expression for the free energy of the system. A simple example for solidification problems is the following:where φ is the phase field, u = e / e0 + h(φ) / 2, e is the local enthalpy per unit volume, h is a certain polynomial function of φ, and e0 = L2 / T M c p (where L is the latent heat, T M is the melting temperature, and c p is the specific heat). The term withcorresponds to the interfacial energy. The function f(φ) is usually taken as a double-well potential describing the free energy density of the bulk of each phase, which themselves correspond to the two minima of the function f(φ). The constants K and h0 have respectively dimensions of energy per unit length and energy per unitvolume. The interface width is then given by . The phase field model can then be obtained from the following variational relations:[9]where D is a diffusion coefficient for the variable e, and η andare stochastic terms accounting for thermal fluctuations (and whose statistical properties can be obtained from the fluctuation dissipation theorem). The first equation gives an equation for the evolution of the phase field, whereas the second one is a diffusion equation, which usually is rewritten for the temperature or for the concentration (in the case of an alloy). These equations are, scaling space with l and times with l2 / D:where is the nondimensional interface width, α = Dτ / W2h0,and , are nondimensionalized noises.[edit] Sharp interface limit of the Phase field equationsA phase field model can be constructed to purposely reproduce a given interfacial dynamics as represented by a sharp interface model. In such a case the sharp interface limit (i.e. the limit when the interface width goes to zero) of the proposed set of phase field equations should be performed. This limit is usually taken by asymptotic expansions of the fields of the model in powers of the interface width . These expansions are performed both in the interfacial region (inner expansion) and in the bulk (outer expansion), and then are asymptotically matched order by order. The result gives a partial differential equation for the diffusive field and a series of boundary conditions at the interface, which shouldcorrespond to the sharp interface model and whose comparison with it provides the values of the parameters of the phase field model.Whereas such expansions were in early phase field models performed up to the lower order in only, more recent models use higher order asymptotics (thin interface limits) in order to cancel undesired spureous effects or to include new physics in the model. For example, this technique has permitted to cancel kinetic effects,[8] to treat cases with unequal diffusivities in the phases,[10] to model viscous fingering[2] and two-phase Navier–Stokes flows,[11] to include fluctuations in the model,[12] etc.[edit] Multi Phase Field ModelsMultiple order parameters describe a polycrystalline material microstructure.In multi a phase field model microstructure is described by set of order parameters each one is related to a specific phase or crystallographic orientation. This model is mostly used for solid state phase transformations where multiple grains evolve (e.g. grain growth, recrystallization or first order transformation like austenite to ferrite in ferrous alloys.[edit] Software∙The Mesoscale Microstructure Simulation Project (MMSP) is a collection of c++ classes for grid-based microstructure simulation. ∙The Microstructure Evolution Simulation Software (MICRESS) is a multi-phase field simulation package developed at RWTH-Aachen.[edit] Further reading∙R. Gonzalez-Cinca et al., in Advances in Condensed Matter and Statistical Mechanics, ed. by E. Korucheva and R. Cuerno, NovaScience Publishers (2004) a review on phase field models.∙L-Q Chen, Annual Review of Materials Research, Vol. 32: 113-140 (2002) Phase field models in solidification∙N. Moelans, B. Blanpain, P.Wollants, Calphad, Vol. 32: 268-294 (2008) An introduction to phase-field modeling for microstructure evolution∙I. Steinbach:Phase-field models in Materials Science –Topical Review, Modelling Simul. Mater. Sci. Eng. 17 (2009)073001∙S.G.Fries, B.Böttger, J.Eiken,I.St einbach:Upgrading CALPHAD to microstructure simulation: the phase-field method, Int.J.Mat.Res100(2009)2∙R. Qin and H. K. D. H. Bhadeshia, a critical assessment of the phase field method, 2010, published in Materials Science andTechnology.[edit] References1.^WJ. Boettinger et al. Annual Review of Materials Research Vol. 32:163-194 (2002)2.^ a b R. Folch et al. Phys. Rev. E 60, 1734 - 1740 (1999)3.^ A. Karma et al. Phys. Rev. Lett. 87, 045501 (2001)4.^T. Biben et al. Phys. Rev. E 72, 041921 (2005)5.^ G.J. Fix, in Free Boundary Problems: Theory and Applications, Ed.A. Fasano and M. Primicerio, p. 580, Pitman (Boston, 1983).6.^ J.S. Langer, Models of pattern formation in first–order phasetransitions, in Directions in Condensed Matter Physics p. 165, Ed. G.Grinstein and G. Mazenko, World Scientific, Singapore, (1986).7.^J.S. Langer, Rev. Mod. Phys. 52, 1 (1980)8.^ a b A. Karma and W.J. Rappel Phys. Rev. E 57, 4323 - 4349 (1998)9.^P.C. Hohenberg and B.I. Halperin, Rev. Mod. Phys. 49, 435 (1977)10.^G. B. McFadden et al., Physica D 144, 154-168 (2000)11.^ D. Jacqmin, J. Comput. Phys. 155,96-127 (1999)12.^R. Benítez and L. Ramírez-Piscina Phys. Rev. E 71, 061603 (2005)。
动态信任关系建模和管理技术研究
49.Gerck E Toward Real-World Models of Trust 1998
20.Chen R.W.Yeager Poblano:A Distributed Trust Model for Peer-to-Peer Networks.Sun Microsystems 2000
21.Winsborough W H.N Li Towards Practical Automated Trust Negotiation 2002
11.A.Abdul-Rahman.S.Halles A distributed trust model 1997
12.A.Abdul-Rahman.S.Hailes Using recommendations for managing trust in distributed systems 1997
34.F.Cornelli.E.Damiani.S.C.Vimercati.S.Paraboschi,P.Samarati A reputation-based approach for choosing reliable resources in peer-to-peer networks 2002
●由于PeerTrust和SecDWTrust都采用了社群信任查询的方法,因此在可信节点占大多数的情况下可以避免虚假的推荐,在~定程度上减轻了联合作弊的危害。而DwTrust 仪依赖直接经验进行判断,在缺乏赢接交互历史的情况下,无法识别联合欺骗行为。
SOAPdenovo2 基因组组装
SOAPdenovo2:an empirically improvedmemory-efficient short-read de novo assemblerRuibang Luo 1,2†,Binghang Liu 1,2†,Yinlong Xie 1,2,3†,Zhenyu Li 1,2†,Weihua Huang 1,Jianying Yuan 1,Guangzhu He 1,Yanxiang Chen 1,Qi Pan 1,Yunjie Liu 1,Jingbo Tang 1,Gengxiong Wu 1,Hao Zhang 1,Yujian Shi 1,Yong Liu 1,Chang Yu 1,Bo Wang 1,Yao Lu 1,Changlei Han 1,David W Cheung 2,Siu-Ming Yiu 2,Shaoliang Peng 4,Zhu Xiaoqian 4,Guangming Liu 4,Xiangke Liao 4,Yingrui Li 1,2,Huanming Yang 1,Jian Wang 1,Tak-Wah Lam 2*and Jun Wang 1*FindingsThe increased use of next generation sequencing (NGS)has resulted in an increased growth of the number of de novo genome assemblies being carried out using short reads.Although there are several de novo assemblers available,there remains room for improvement as shown in recent assembly evaluation projects such as Assem-blathon 1[1]and GAGE [2].Since the publication of the first version of SOAPdenovo [3],it has been used to as-semble many large eukaryotic genomes,but reports haveindicated areas that would benefit from updates,includ-ing assembly coverage and length [4,5].SOAPdenovo2,as with SOAPdenovo,is made up of six modules that handle read error correction,de Bruijn graph (DBG)construction,contig assembly,paired-end (PE)reads mapping,scaffold construction,and gap clos-ure.The major improvements we have made for in SOAPdenovo2are:1)enhancing the error correction al-gorithm,2)providing a reduction in memory consump-tion in DBG constructions,3)resolving longer repeat regions in contig assembly,4)increasing assembly length and coverage in scaffolding and 5)improving gap clos-ure.Our data show that SOAPdenovo2outperforms its predecessor on the majority of the metrics benchmarked in the Assemblathon 1as well as GAGE;and in addition,was able to substantially improve the original assembly*Correspondence:twlam@cs.hku.hk ;wangj@ †Equal contributors 2HKU-BGI Bioinformatics Algorithms and Core Technology ResearchLaboratory &Department of Computer Science,University of Hong Kong,Pokfulam,Hong Kong 1BGI HK Research Institute,16Dai Fu Street,Tai Po Industrial Estate,Hong KongFull list of author information is available at the end of thearticle©2012Luo et al.;licensee BioMed Central Ltd.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (/licenses/by/2.0),which permits unrestricted use,distribution,and reproduction in any medium,provided the original work is properly cited.Luo et al.GigaScience 2012,1:18/content/1/1/18of the Asian(YH)genome[6]that was done using SOAPdenovo.Improvements in SOAPdenovo2Dealing with sequencing error in NGS data is inevitable, especially for genome assembly applications,the out-come of which could be largely affected by even a small amount of sequencing error.Hence it is mandatory to detect and revise these sequencing errors in reads before assembly[2,7].However,the error correction module in SOAPdenovo was designed for short Illumina reads(35-50bp),which consumes an excessive amount of compu-tational time and memory on longer reads,for example, over150GB memory running for two days using40-fold100bp paired-end Illumina HiSeq2000reads.Thus, by a skillful exploitation of data indexing strategies,we redeveloped the module,which supports memory effi-cient long-k-mer error correction and uses a new space k-mer scheme to improve the accuracy and sensitivity (see Additional file1:Supplementary Method1and Figures S1-S3).Simulation test shows that the new ver-sion runs efficiently and corrects more reads authentic-ally(see Additional file1:Tables S1and S2).In DBG-based large-genome assembly,the graph construction step consumes the largest amount of mem-ory.To reduce this in SOAPdenovo2,we implemented a sparse de Bruijn graph method[8](see Additional file1: Supplementary Method2),where reads are cut into k-mers and a large number of the linear unique k-mers are com-bined as a group instead of being stored independently. Another important factor in the success of DBG-based assembly is k-mer size ing a large k-mer has the advantage of resolving more repeat regions;whereas, use of small k-mers is advantageous for assembling low coverage depth and removing sequencing errors.To fully utilize both these advantages,we introduced a multiple k-mer strategy[9]in SOAPdenovo2(see Additional file 1:Supplementary Method3and Figure S4).First,we removed sequencing errors using small k-mers for graph building,and then we rebuilt the graph using larger k-mers iteratively by mapping the reads back to the previ-ous DBG to resolve longer repeats.Scaffold construction is another area that needs im-provement in NGS de novo assembly programs[10].In the original SOAPdenovo,scaffolds were built by utiliz-ing PE reads starting with short insert sizes(~200bp) followed iteratively to large insert sizes(~10kbp)[3]. Although this iterative method greatly decreased the complexity of scaffolding and enabled the assembly of larger genomes,there remained many issues that resulted in lower scaffold quality and shorter length.For example,1)the heterozygous contigs were improperly handled;2)chimeric scaffolds erroneously built with the smaller insert size PE reads which then hindered the later steps to increase of scaffold length when adding PE reads with larger insert size;and3)false relationships between contigs without sufficient PE information sup-port were created occasionally.To improve this in SOAPdenovo2,the main changes during the scaffolding stage were as follows:1)we detected heterozygous con-tig pairs using contig depth and local contig relation-ships.Under these conditions,only the contig with higher depth in the heterozygous pairs was kept in scaf-fold,which reduced the influence of heterozygosity on the scaffolds length;2)chimeric scaffolds that were built using a smaller insert size library were rectified using in-formation from a larger insert size library,and3)we developed a topology-based method to reestablish rela-tionships between contigs that had insufficient PE infor-mation support(see Additional file1:Supplementary Method4and Figures S5-S7).Short reads enabled us to reconstruct large vertebrate and plant genomes,but the assembly of repetitive sequences longer than the read length still remain to be tackled.In scaffold construction,contigs with certain distance relationship,but without genotypes amid were connected with wildcards.The GapCloser module was designed to replace these wildcards using the context and PE reads information.In SOAPdenovo2,we have improved the original SOAPdenovo GapCloser module, which assembled sequences iteratively in the gaps to fill large gaps.At each iterative cycle,the previous release of GapCloser considered only the reads that could be aligned in current cycle.This method could potentially make for an incorrect selection at inconsistent locationsTable1Evaluation of Assemblathon1dataset assembliesContig N50Contigpath NG50ScaffoldN50Scaffoldpath NG50Number ofStructural ErrorSubstitutionError rateCopy NumberError rateGenomecoverage(%)Memory(G)Runtime(h)V1207,78313,357329,38413,53914,306 5.40E-059.14E-0398.8467 V1.05*343,88982,2641,684,436116,6511,878 1.20E-05 6.75E-0398.8208 V2.0357,238111,36515,077,357170,4321,414 4.25E-06 2.79E-0398.82010§ALLPATHS-LG*163,63372,4808,185,650210,6491,244 2.92E-06 6.71E-0298.310012 Contig and scaffold path NG50were defined in Assemblathon1[1].*SOAPdenovo v1.05and ALLPATHS-LG’s evaluation result data were from[1].§Time spent on filtering contamination was not included.with insufficient information for distinguishment due to the high similarity between repetitive sequences.For SOAPdenovo2,we developed a new method that consid-ered all reads aligned during previous cycles,which allowed for better resolution of these conflicting bases,and thus improved the accuracy of gap closure.(see Additional file 1:Supplementary Method 5).Testing and assessmentTo test the performance of SOAPdenovo2,we assembled the Assemblathon1benchmark dataset [11]and evalu-ated the assembly using the Assemblathon1’s official evaluation pipeline [1].Our analyses showed that SOAP-denovo2performed better than the initial release of SOAPdenovo [3](hereafter referred to as ‘SOAPde-novo1’)and SOAPdenovo v1.05(hereafter referred to as ‘SOAPdenovo1.05’)used in Assemblathon1.Notably,SOAPdenovo1.05was developed two years after SOAP-denovo1for the Assemblathon1and has never been for-mally released.It included partial improvements and new features from SOAPdenovo2,including the new contig and scaffold construction improvements,butwithout the new error correction and gap closure pared with the results of SOAPdenovo1,the new scaffold N50was nearly an order of magnitude longer and the accuracy was higher due to the reduction of structural error by 90.12%,substitution error by 92.13%,and copy number error by 69.47%(Table 1,Figure 1).We also compared our results with that of ALLPATHS-LG [5],and SOAPdenovo2produced contig N50and scaffold N50that were approximately 1.53and 1.84-times longer.The SOAPdenovo2assembly also had a much lower amount of copy number errors,but did have more substitution errors [1].The lower substitution error in ALLPATHS-LG is likely because it includes a step analogous to “editing the assembly ”to eliminate ambiguity,but it does so at the expense of more compu-tational consumption.Improvements of SOAPdenovo2have also been observed in assembling GAGE [8]dataset (see Additional file 1:Supplementary Method 6and Tables 2and 3).As shown in Tables 2and 3,the correct assembly length of SOAPdenovo2increased by approxi-mately 3to 80-fold comparing with that of SOAPde-novo1.Worth mentioning,there are only two levels ofTable 2Assemblies of S.aureus and R.sphaeroidesSpecies VersionContigs ScaffoldsNumberN50(kb)Errors N50corrected(kb)Number N50(kb)Errors N50corrected (kb)S.aureusSOAPdenovo179148.615623493420342SOAPdenovo28098.62571.5381,08621,078ALLPATHS-LG*37149.713117.6101,47711,093R.sphaeroidesSOAPdenovo12,242 3.5392 2.89561051870SOAPdenovo27211810614.13332,54942,540ALLPATHS-LG*19041.93136.7323,1913,310All datasets were downloaded from /data/.*ALLPATHS-LG was using the latest version42807.insert size for Staphylococcus aureus and Rhodobacter Sphaeroides ,the setting of which is optimal for ALL-PATHS-LG,but mismatches with the requirement of SOAPdenovo2to come up with an optimal assembly (see Additional file 1:Supplementary Method 4);thus,the results of GAGE might not be able to illustrate the power of SOAPdenovo2,especially for the scaffolding part.We also used SOAPdenovo2to reassemble and update the previously assembled YH Asian Genome [12].The previous assembly was done using SOAPdenovo1[3],but in addition it was also limited by the very short read lengths (~35bp)that were the standard output of Illu-mina Genome Analyzers (GAIIx)at that time and by the insert sizes available (maximum size is 10kb).To pro-vide an updated assembly with the new program,we generated a new set of PE 100bp-long reads with an in-sert size ranging from 180bp to 40kbp using the Illu-mina HiSeq 2000[13](see Additional file 1:Table S3).These new data were put through both the SOAPde-novo1and SOAPdenovo2pipelines.To test out the per-formance of each new feature in SOAPdenovo2,we also assembled the genome with or without the multi k -mers and sparse DBG modules.As shown in Table 4and Figure 2,using the new data,we found that the Contig N50and Scaffold N50of SOAPdenovo2were,respectively, 1.64and 3.84-times longer than SOAPdenovo1.The result is also 3-fold and 50-fold longer than the first YH genome version.Not-ably,by using sparse DBG,the memory consumption forgraph construction decreased dramatically,but the N50contig and N50scaffold dropped.This is due to the shorter k -mer length required by sparse DBG ’s design to acquire higher k -mer depth,which in turn disabled some repetitive sequences from being solved (see Additional file 1:Supplementary Method 2).By using larger k -mer length,ALLPATHS-LG outperformed SOAPdenovo2on contig N50by 1.49-times,but for scaffold N50,SOAPdenovo2is 6Mbp (1.37-times)longer.SOAPdenovo2covered the reference genome 5.38%more and ran 3.36-times faster on the same machine than ALLPATHS-LG.To confirm the contribution of new algorithms,we evaluated both the YH genome assembled by SOAPdenovo1and SOAPde-novo2respectively by aligning them to the NCBI human reference genome hg19[14].We obtained a reference coverage increase from 81.2%to 93.9%,and we found that approximately 95.9%of the newly assembled regions were repetitive sequences.The increased reference coverage is mainly due to the improved SOAPdenovo2,not to the newly sequencing data.A previous report had indicated that most of the seg-mental duplications (SD)were lost in the earlier published version of the YH [4].To investigate the SD coverage of new version YH genome sequences,we aligned the contigs of the first version and the new version to 134Mb of pub-lished human SD sequences [15]and found that up to 99%of the published SD sequences were now sufficiently represented (≥90%of each sequence)in the updated as-sembly,while only 21.5%were represented in the earlierTable 4Summary of YH dataset assembliesData and ProgramVersionk -merScaffold total length(bp)Scaffold N50(bp)Contig total length(bp)Contig N50(bp)Coverage Time (h)Peak Memoryat Graph Construction (G)SOAPdenovo YH old data v1252,837,024,602455,3802,327,931,6784,93380.51%48^140SOAPdenovo YH new datav1312,901,125,4265,806,4952,661,982,49812,70981.16%58^107v2Multi-k -mer 45-612,905,148,69022,297,1382,799,723,05120,92693.91%74^155v2Sparse 352,874,598,20118,033,6222,767,141,36718,85693.17%78^35v2Sparse &Multi-k -mer35-492,888,094,84717,576,2722,776,209,13418,96093.20%81^35ALLPATHS-LG §YH new data42807962,809,141,26116,195,6842,600,792,53331,10188.53%249*343To be consistence with the result of ALLPATHS-LG,contigs and scaffolds shorter than 1kb were filtered for SOAPdenovo assemblies.§Without ‘FixLocal ’due to the module failure (see Additional file 1:Supplementary Method 7).^Time consumption including SOAPdenovo ’s error correction,assembly and gap closure modules.*Time consumption including ALLPATHS-LG ’s preparation and assembly modules.Table 3Assemblies of Bombus ImpatiensAssemblerContigs Scaffolds NumberN50(kb)E-size (kb)Number N50(kb)E-size (kb)SOAPdenovo164,3617.910.452,0411225SOAPdenovo212,55075.791.15,0841,3521,596ALLPATHS-LG*------*The published ALLPATHS-LG could not be used to assemble this genome because it requires at least one library with overlapping paired-end reads.version(see Additional file1:Table S4).The rate of SD sequences that appeared more than once with sufficient coverage for each copy was increased from0.02%to52.6% in the updated version.The assembly of fragmented genes (noted in[4])was also improved(see Additional file1: Table S5).For example,average coverage of gene GRM5 increased from90%to96%and the number of fragments decreased from162to4.The work here demonstrates that SOAPdenovo2is greatly improved over the initial version and specifically in areas that have been highlighted as problems in the cur-rently available short-read de novo assembly programs.It thus provides an effective solution for carrying out de novo genome assembly especially for eukaryotic genomes.We have also been able to provide a much better quality ver-sion of the previously assembled YH genome[13],which will serve as an excellent reference genome for use in Chinese population studies,as well as for general human genome studies.SOAPdenovo2has been successfully deployed in public computing clouds including TianHe series supercomputer and Amazon EC2.Availability and requirementsProject name:SOAPdenovo2Project home page and forum:http://soapdenovo2./Operating system(s):Unix,Linux,MacProgramming language:C,C++Other requirements:GCC version≥4.4.5License:GNU General Public License version3.0 (GPLv3)Any restrictions to use by non-academics:none Contact:bgi-soap@ Availability of supporting dataThe raw reads from the YH genome generated in this work are available from the BGI website[16],the EBI short read archive with study accession[EMBL: ERP001652],and also from the GigaScience database[6]. The updated assembly is also available at GigaScience [13].In order to facilitate readers to repeat the experi-ments,the tools and configured packages including commands and necessary utilities are available from our FTP server ftp:///BGI/ SOAPdenovo2,and are also being made available from the GigaScience database[17].Additional fileAbbreviationsbp:Base pair;DBG:de Bruijn graph;PE:Paired end;SD:Segmental duplication;YH:Asian genome.Competing interestsThe authors declare that they have no competing interests.Authors ’contributionsRL,BL,YX and ZL contributed equally to this work.Ju W,Ji W,HY,TL,Yi L and RL managed the project.RL,BL,YX and ZL led the design.RL,WH,JY,GH,YC,QP,YL,JT,GW,HZ,YS,Yo L,CY,DC,SY,XZ,SP,XL and GLimplemented and tested the software.BW,Ya L,CH performed sequencing.RL and BL wrote the paper.All authors read and approved the final manuscript.AcknowledgementsWe would like to thank the users of SOAPdenovo who tested the program,reported bugs,and proposed improvements to make it more powerful and user-friendly.Thanks to TianHe research and development team of National University of Defense Technology to have tested,optimized and deployed the software on TianHe series supercomputers.The project was supported by the State Key Development Program for Basic Research of China-973Program (2011CB809203);National High Technology Research and Development Program of China-863program (2012AA02A201);the National Natural Science Foundation of China (90612019);the Shenzhen Key Laboratory of Trans-omics Biotechnologies (CXB201108250096A);and the Shenzhen Municipal Government of China (JC201005260191A andCXB201108250096A).Tak-Wah Lam was partially supported by RGC General Research Fund 10612042.Author details 1BGI HK Research Institute,16Dai Fu Street,Tai Po Industrial Estate,Hong Kong.2HKU-BGI Bioinformatics Algorithms and Core Technology Research Laboratory &Department of Computer Science,University of Hong Kong,Pokfulam,Hong Kong.3School of Bioscience and Bioengineering,South China University of Technology,Guangzhou 510006,China.4School of Computer Science,National University of Defense Technology,No.47,Yanwachi street,Kaifu District,Changsha,Hunan 410073,China.Received:24July 2012Accepted:10December 2012Published:27December 2012References1.Earl D,Bradnam K,St John J,Darling A,Lin D,Fass J,Yu HO,Buffalo V,Zerbino DR,Diekhans M,Nguyen N,Ariyaratne PN,Sung WK,Ning Z,Haimel M,Simpson JT,Fonseca NA,Docking TR,Ho IY,Rokhsar DS,Chikhi R,Lavenier D,Chapuis G,Naquin D,Maillet N,Schatz MC,Kelley DR,Phillippy AM,Koren S,et al :Assemblathon 1:a competitive assessment of de novo short read assembly methods.Genome Res 2011,21:2224–2241.2.Salzberg SL,Phillippy AM,Zimin A,Puiu D,Magoc T,Koren S,Treangen TJ,Schatz MC,Delcher AL,Roberts M,Marçais G,Pop M,Yorke JA:GAGE:a critical evaluation of genome assemblies and assembly algorithms.Genome Res 2012,22:557–567.3.Li R,Zhu H,Ruan J,Qian W,Fang X,Shi Z,Li Y,Li S,Shan G,Kristiansen K,LiS,Yang H,Wang J,Wang J:De novo assembly of human genomes with massively parallel short read sequencing.Genome Res 2010,20:265–272.4.Alkan C,Sajjadian S,Eichler EE:Limitations of next-generation genomesequence assembly.Nat Methods 2011,8:61–65.5.Gnerre S,Maccallum I,Przybylski D,Ribeiro FJ,Burton JN,Walker BJ,SharpeT,Hall G,Shea TP,Sykes S,Berlin AM,Aird D,Costello M,Daza R,Williams L,Nicol R,Gnirke A,Nusbaum C,Lander ES,Jaffe DB:High-quality draft assemblies of mammalian genomes from massively parallel sequence data.Proc Natl Acad Sci U S A 2011,108:1513–1518.6.Wang J,Wang W,Li R,Li Y,Tian G,Goodman L,Fan W,Zhang J,Li J,ZhangJ,Guo Y,Feng B,Li H,Lu Y,Fang X,Liang H,Du Z,Li D,Zhao Y,Hu Y,Yang Z,Zheng H,Hellmann I,Inouye M,Pool J,Yi X,Zhao J,Duan J,Zhou Y,Qin J,et al :Genome sequence of YH:the first diploid genome sequence of a Han Chinese individual.GigaScience 2011,/10.5524/100015.7.Zerbino DR,Birney E:Velvet:algorithms for de novo short read assemblyusing de Bruijn graphs.Genome Res 2008,18:821–829.8.Ye C,Ma ZS,Cannon CH,Pop M,Yu DW:Exploiting sparseness in de novo genome assembly.BMC Bioinformatics 2012,13Suppl 6:S1.9.Peng Y,Leung HC,Yiu SM,Chin FY:IDBA-UD:a de novo assembler for single-cell and metagenomic sequencing data with highly uneven depth.Bioinformatics 2012,28:1420–1428.10.Dayarian A,Michael TP,Sengupta AM:SOPRA:scaffolding algorithm for paired reads via statistical optimization.BMC Bioinformatics 2010,11:345.11.The Assemblathon ..12.Wang J,Wang W,Li R,Li Y,Tian G,Goodman L,Fan W,Zhang J,Li J,Zhang J,Guo Y,Feng B,Li H,Lu Y,Fang X,Liang H,Du Z,Li D,Zhao Y,Hu Y,Yang Z,Zheng H,Hellmann I,Inouye M,Pool J,Yi X,Zhao J,Duan J,Zhou Y,Qin J,et al :The diploid genome sequence of an Asian individual.Nature 2008,456:60–65.13.Wang J,Li Y,Luo R,Liu B,Xie Y,Li Z,Fang X,Zheng H,Qin J,Yang B,Yu C,Ni P,Li N,Guo G,Ye J,Fang L,Su Y,Asan,Zheng H,Kristiansen K,Wong GK,Nielsen R,Durbin R,Bolund L,Zhang X,Li S,Yang H,Wang J:Updated genome assembly of YH:the first diploid genome sequence of a Han Chinese individual (version 2,07/2012).GigaScience Database 2012,/10.5524/100038.14.The UCSC Genome Bioinformatics site ./.15.She X,Jiang Z,Clark RA,Liu G,Cheng Z,Tuzun E,Church DM,Sutton G,Halpern AL,Eichler EE:Shotgun sequence assembly and recent segmental duplications within the human genome.Nature 2004,431:927–930.16.Yan Huang -The first Asian diploid genome ..17.Luo R,Liu B,Xie Y,Li Z,Huang W,Yuan J,He G,Chen Y,Pan Q,Liu Y,Tang J,Wu G,Zhang H,Shi Y,Liu Y,Yu C,Wang B,Lu Y,Han C,Cheung D,Yiu SM,Liu G,Zhu X,Peng S,Li Y,Yang H,Wang J,Lam TW,Wang J:Software and supporting material for “SOAPdenovo2:an empirically improved memory-efficient short read de novo assembly ”.GigaScience Database 2012,/10.5524/100044.。
2024年度初中英语中考阅读理解课件
Weigh the evidence presented in the text to determine the truth or falsehood of a statement
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Main ideas
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Identify the topic
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If there are multiple choices, compare and contrast them
with the information in the text to find the best match
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Inference and True/False Questions
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Common question types and problem solving techniques
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Identify key information
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Look for specific details in the text that directly answers
Reading comprehension passages typically cover a range of topics, including but not limited to school life, daily activities, social issues, and science and technology
reasonable guess based on the information you have and move
英语 算法 -回复
英语算法-回复The Basics of Algorithm: Understanding the Core Principles [英语算法]Introduction:In the world of computer science, algorithms are the building blocks of software development. They are step-by-step instructions that guide computers to perform specific tasks efficiently and effectively. Understanding algorithms is crucial for programmers and developers, as it helps enhance the performance and functionality of their programs. This article will delve into the basics of algorithms, exploring their core principles, and providingstep-by-step explanations.1. What is an Algorithm?An algorithm is a set of well-defined instructions that solve a specific problem or perform a specific task. It can be thought of as a recipe that defines a series of steps to achieve a desired outcome. Algorithms are at the heart of software development, enabling computers to process and manipulate data in a logical and structured manner.2. Understanding Algorithm Complexity:Algorithm complexity refers to the resources (time and space) required by an algorithm to solve a problem. It is crucial to analyze the complexity of an algorithm to determine its efficiency and scalability. Two main factors are considered when analyzing algorithm complexity: time complexity and space complexity.a. Time Complexity:Time complexity measures the amount of time an algorithm takes to solve a problem. It focuses on how the algorithm's performance changes with the input size. Common notations used to describe time complexity include O(1), O(n), O(log n), O(n^2), etc. These notations give an idea of how the algorithm's performance scales as the input size grows.b. Space Complexity:Space complexity measures the amount of memory an algorithm requires to solve a problem. It determines how much additional memory the algorithm consumes as the input size increases. Common notations used for space complexity include O(1), O(n), O(n^2), etc. These notations provide insights into the memory usage of the algorithm.3. Algorithm Design Techniques:Several algorithm design techniques are employed to create efficient and optimized algorithms. Here are a few commonly used techniques:a. Divide and Conquer:This technique involves breaking down a large problem into smaller subproblems, solving them independently, and then combining the results to obtain the final solution. Merge Sort and Quick Sort are examples of divide and conquer algorithms.b. Dynamic Programming:Dynamic programming breaks down a problem into smaller overlapping subproblems and solves them in a bottom-up manner. It stores the results of subproblems to avoid redundant computations. The Fibonacci series is often used to demonstrate dynamic programming.c. Greedy Algorithm:Greedy algorithms make locally optimal choices at each step, with the hope that these choices will lead to a globally optimalsolution. They do not consider the future consequences of their choices. Dijkstra's algorithm for finding the shortest path is a classic example.4. Analyzing and Comparing Algorithms:When designing algorithms, it is essential to analyze and compare them to determine their effectiveness and efficiency. Some key factors to consider when analyzing and comparing algorithms include:a. Worst-case, Average-case, and Best-case Analysis:Algorithms may perform differently based on various input scenarios. Analyzing their performance in worst-case, average-case, and best-case scenarios helps understand their strengths and weaknesses.b. Big O Notation:The Big O notation provides an upper bound on the time or space complexity of an algorithm. By comparing algorithms' Big O notations, one can determine which algorithm is more efficient for a given problem.c. Benchmarking:Benchmarking involves running algorithms on various inputs and measuring their performance. This helps understand the practical impact of an algorithm and allows for real-world comparisons.Conclusion:Algorithms are the fundamental building blocks of software development. Understanding their core principles, analyzing their complexity, and employing appropriate design techniques are essential for any programmer or developer. By continuously improving algorithms, we can create more efficient and powerful software that can tackle complex problems with ease.。
晒晒我们班的数学牛人英语作文600字英语作文
全文分为作者个人简介和正文两个部分：作者个人简介：Hello everyone, I am an author dedicated to creating and sharing high-quality document templates. In this era of information overload, accurate and efficient communication has become especially important. I firmly believe that good communication can build bridges between people, playing an indispensable role in academia, career, and daily life. Therefore, I decided to invest my knowledge and skills into creating valuable documents to help people find inspiration and direction when needed.正文：晒晒我们班的数学牛人英语作文600字英语作文全文共3篇示例，供读者参考篇1My Class Math ProdigyYou know how every class has that one kid who just seems to be operating on another level when it comes to math? The one who solves complicated equations in their head while therest of us are still trying to borrow from the tens column? Well, in my class, that freakishly gifted mathlete is Aiden Patel.I still remember the first time I realized Aiden was a legitimate math genius. It was during Mrs. Thompson's algebra class back in 9th grade. She had written out a hairy polynomial equation on the whiteboard and asked if anyone could simplify it. Most of us just stared at it blankly, completely overwhelmed. But Aiden's hand shot straight up. Mrs. Thompson called on him, probably expecting him to at least attempt an algebraic solution. Instead, Aiden just blurted out the correct simplified form immediately. He didn't show any work or explain his reasoning - he had somehow arrived at the final answer through pure mental calculation!Mrs. Thompson and the rest of the class were dumbfounded. After an awkward silence, she reluctantly confirmed that Aiden was indeed correct. From that day on, he solidified his reputation as the undisputed math whiz of our grade. Anytime a teacher posed a remotely challenging math problem, all eyes immediately turned to Aiden. Without fail, his hand would shoot up and he would effortlessly recite the solution, even for the most labyrinthine equations and proofs.What makes Aiden's talents even more remarkable is that he doesn't come off as a natural-born genius in other subjects. In English class, he struggles with essays and literary analysis just like the rest of us. He's an okay athlete but nothing special on the sports teams. In areas outside of mathematics, he seems...well, pretty normal and averagely intelligent. But when it comes to numbers, logic, patterns, probability - anything even remotely related to math - Aiden is in a completely different stratosphere. It's honestly mind-boggling.His skills extend far beyond simply being a human calculator, too. In Geometry last year, he didn't just memorize formulas and theorems - he seemed to derive an innate, intuitive FEEL for shapes, angles, spatial reasoning, and proofs. Sketching out an elegant geometric proof on the board was like artistic expression for Aiden. He would get this intense look of rapturous focus, like he was conceiving dimensions and axioms that the rest of us couldn't even perceive.Then in AP Calculus this year, he took his talents to even higher realms of abstract mathematics. Aiden treated integrals, derivatives, and limits not just as headache-inducing computations, but as frameworks for modeling and understanding the entire universe. To him, calculus was abeautiful language for describing motion, change, and the infinite. Our teacher Mr. Singh says Aiden grasps calculus concepts that most students don't fully understand until graduate-level real analysis.Despite his otherworldly skills, Aiden carries himself with an easygoing humility. He's not an eccentric math obsessive or arrogant teacher's pet - just a regular teenager who happens to possess savant-level aptitudes. Aiden is honestly a solid,down-to-earth guy who loves video games, alt rock, and pizza as much as the next kid. His freakish talents don't define his whole personality.That said, there's no doubt Aiden is destined for greatness in mathematics and anything else quantitative. Most of us will likely end up in fairly conventional career paths - Aiden is practically guaranteed to become an ingenious researcher, pioneering scientific pioneer, or era-defining technological innovator. Maybe he'll map ultra-dense computational networks, reformulate economic theory through a numerical lens, or even help unify physics' grand unified theory. Nothing seems beyond the lofty scope of Aiden's supreme mathematical mind.For now though, Aiden is just enjoying his teenage years alongside the rest of us average Joes. Every so often in class, ourMath Maestro still leaves us all slack-jawed at the depth and dexterity of his numerical abilities. His gift is both incredibly fascinating and utterly mystifying to the mere mortal students around him. While the rest of us get migraines from quadratics and polynomials, Aiden casually crests stratospheres of mathematical brilliance that we can scarcely fathom. We're all just lucky we get to witness his precocious genius bloom firsthand during these formative high school years. Who knows what cosmic truths and revelations that incredible mind will one day unlock for us?篇2The Mathletes of Class 3BThere's something special about Class 3B – we're a bunch of math whizzes! I'm not just saying that to brag, although a little bragging is definitely allowed. We've got a squad of number nerds who can calculate like calculators on steroids. Let me introduce you to the Mathletes of 3B.First up, we have Aisha, our resident human calculator. This girl can rattle off square roots of 10-digit numbers faster than I can say "mathematic-ally challenged." Rumor has it she does complex equations in her head for fun during recess. I'vewitnessed her resolving quarrels over pocket money by crunching numbers mid-argument. "You owe Jayden 3.75 for that candy bar trade last week," she'll announce, and just like that, the matter is settled. Aisha is, without a doubt, our undisputed Math Queen.Then there's Thomas, a soft-spoken boy who becomes a math beast when challenged. His genius lies in geometric constructions and 3D visualizations. You should see the masterpieces he can create using just a compass, ruler, and well, his brilliant mind. Last year's Math Fair had everyone gawking at his mind-bending geometric art installments. Who knew angles and lines could be sculpted into such hypnotic patterns? That's our Thomas – a modern-day Euclid with a knack for shapes.We can't forget Samantha, whose superpower islightning-fast mental math. This human calculator can crush arithmetic problems at warp speed, all while braiding her hair or doodling geometric doodles. Show her a string of numbers, and within seconds, she'll burst out with the precise answer…and maybe a silly math pun too. "Whatdo you call a line that really loves pizza? A slice of pi!" Samantha's brain is basically a parallel processing unit dedicated to crunching numbers at turbo speeds.Of course, every elite squad has its unsung heroes too. In our case, it's the tireless efforts of Ethan and Priya. These two form an unstoppable equation-solving duo, dividing and conquering every challenge thrown their way. Ethan is a master at algebraic manipulation, while Priya has a supernatural intuition for patterns and sequences. Together, they're an unmatchable math force, often staying back late to tackle bonus problems "just for fun." Their dedication, teamwork, and sheer love for the subject inspires all of us mathsters.As you can tell, Class 3B isn't just about books and blackboards. We're a squad of number nerds, mental math masters, and problem-solving prodigies. We revel in the beauty of mathematics, finding solutions where others only see garbles of numbers and symbols. Some may call us "uncool" for getting excited over mathematical puzzles, but hey, to each their own. We're the Mathletes, and we wear that badge with geeky pride!篇3Math Prodigies in Our ClassYou know that feeling when the math teacher announces a surprise test, and a collective groan echoes through the classroom? Well, not for the math geniuses in our class! Whilethe rest of us break into a cold sweat, these remarkable individuals barely bat an eyelash. They're the ones who make complex equations look like child's play, leaving us mere mortals in awe of their brilliance.At the top of the leaderboard, we have Emily, our resident math prodigy. From the moment she stepped into our classroom, it was clear that numbers held no secrets from her. She's like a human calculator, effortlessly crunching through complex problems that would leave the rest of us scratching our heads in bewilderment. Emily's ability to grasp advanced mathematical concepts with ease is nothing short of extraordinary.Then there's Michael, the master of mental math. This guy can solve multi-digit calculations in his head faster than most of us can punch numbers into a calculator. It's like he has a built-in supercomputer in his brain, processing intricate equations at lightning speed. We've all witnessed him breeze through challenging problems on the whiteboard, leaving the teacher in a state of utter amazement.Don't get me started on Samantha, the queen of logic and reasoning. Her ability to dissect word problems and unravel their hidden mathematical gems is truly remarkable. She has a knack for breaking down complex scenarios into a series of logicalsteps, making even the most convoluted problems seem straightforward. Samantha's analytical prowess is the envy of our entire class.And let's not forget about David, the geometry master. This guy can visualize and manipulate shapes in his mind like a seasoned architect. Whether it's calculating the area of irregular polygons or solving intricate proofs, David navigates the world of geometry with an ease that defies comprehension. His spatial reasoning skills are off the charts!But what truly sets these math whizzes apart is not just their exceptional abilities; it's their passion for the subject. They genuinely love the thrill of tackling complex problems and finding elegant solutions. You can see the excitement in their eyes when a new mathematical challenge presents itself, and they dive into it with an enthusiasm that's nothing short of infectious.Of course, being surrounded by such mathematical brilliance can be both inspiring and intimidating for the rest of us. But you know what? We've learned to embrace and appreciate their talents. After all, they're the ones who keep our class on its toes, pushing us to strive for excellence and never settle for mediocrity.So, here's to the math prodigies in our class – the ones who make numbers dance and equations sing. They may have left us in the dust academically, but their dedication and love for mathematics have undoubtedly inspired us to reach for greater heights. Who knows, maybe one day we'll join their ranks and become math whizzes ourselves!。
霍尔传感器
摘要中国已经成为世界汽车保有量较大的国家之一，机动车消耗的原油占国家整个原油消耗量的比例逐年提高，同时，由机动车尾气排放造成的环境污染也日益严重。
解决这一难题最可行的方法就是发明一种绿色环保的新型汽车，由此，混合动力汽车进入人们的视野。
专家估算，使用混合动力汽车，和普通汽车相比，至少可节油10%到30%，可见，使用和推广混合动力汽车技术有极其可观的现实意义，关系到国计民生。
我国的混合动力汽车技术研究起步较晚，但是已经取得了很多成就，国内的很多院校和科研院所都具备了一定的研发能力，我国的混合动力汽车技术正飞速发展，车用动力电机系统的开发是混合动力汽车动力系统、供电系统以及解决燃油污染问题等的技术的关键。
本文所阐述的使用霍尔传感器的车用永磁同步电机控制技术就是针对混合动力汽车技术中核心的永磁同步电动机控制提出的一种新的控制方法，目的是在降低系统成本的同时提高永磁同步电机的控制精度。
本使用霍尔传感器的车用永磁同步电机控制技术已经申请专利，本发明专利属于机电领域，具体涉及一种车用永磁同步电机控制方法。
车用动力电机系统是专门为混合动力汽车设计的提供动力的系统。
由于混合动力汽车的比较复杂的工况和启动时的大扭矩要求，对电机及其控制器要求有比较高的控制精度、快速的响应速度和能够迅速的在电动和发电的工况下迅速切换并具备大的转速范围。
这些要求使用永磁同步电机作为混合动力汽车的动力电机。
吉林大学硕1学位论文永磁电机运行时霍尔传感器只能得到60度分辨率的电角度，而永磁同步电机的精确控制需要得到连续角度信号，因此，直接使用霍尔传感器作为角度信号只能满足永磁无刷电机的控制要求，满足不了永磁同步电机的控制要求。
为实现永磁同步电机的精确控制，就要提高系统对电角度的分辨率，现在比较普遍的方法是通过旋转编码器或旋转变压器得到电机的实际运行电角度，以通过旋转编码器得到电机的实际运行电角度，电机控制器计算实际电角度最为方便，而采用旋转变压器也可以通过硬件电路得到和旋转编码器相同的信号。
recurring method
recurring method"Recurring method" can refer to a variety of processes or techniques that are repeated or used on a regular basis. It can be applied in different contexts such as business, education, personal development, and more.In a business context, a recurring method may refer to a specific approach or system that is regularly employed to achieve certain objectives. This could include recurring billing methods for subscription-based services, where customers are charged at regular intervals for the services they receive. It could also refer to the use of recurring meetings or check-ins to monitor progress on ongoing projects or initiatives.In education, a recurring method might involve the use of regular assessments or evaluations to track students' progress over time. It could also refer to the practice of revisiting and reinforcing previously covered material to ensure retention and understanding.In personal development, a recurring method could be a habitual practice or routine aimed at self-improvement, such as daily meditation, exercise, or journaling.In a broader sense, the concept of a recurring method underscores the importance of consistency and repetition in achieving desired outcomes. It acknowledges that many goals are best pursued through sustained, ongoing effort rather than one-time actions.Overall, a recurring method can be a powerful tool in various aspects of life, providing structure, consistency, and the opportunity for continuous improvement. By systematically applying certain methods or practices on a recurring basis, individuals and organizations can work towards long-term success and growth.。
介绍自己擅长什么的英语作文
I am an individual with a multifaceted skill set that has been honed through persistent dedication, continuous learning, and practical application across various domains. This essay aims to provide you with a comprehensive understanding of my core competencies, which I have cultivated over the years.Firstly, in the realm of academics, I specialize in the field of Computer Science and Engineering. I hold a strong command over programming languages such as Python, Java, and C++. My expertise extends from front-end web development to back-end systems architecture, including proficiency in frameworks like ReactJS, AngularJS, Node.js, and Django. I have consistently delivered projects involving complex algorithms, data structures, machine learning models, and software engineering principles. Beyond coding, I possess a keen interest in computational theory and artificial intelligence, allowing me to approach problems with both a theoretical and practical perspective.Secondly, my forte lies in effective communication and leadership abilities. Throughout my academic and professional journey, I've had numerous opportunities to lead teams, organize events, and conduct presentations. These experiences have fine-tuned my interpersonal skills and ability to articulate ideas clearly and persuasively. I excel at interpreting technical information for non-technical stakeholders, thereby bridging the gap between technical and business realms. Moreover, my empathetic leadership style enables me to foster collaborative environments where team members feel valued and motivated.Thirdly, I pride myself on my critical thinking and problem-solving skills. Whether it's tackling intricate mathematical conundrums or resolving real-world business challenges, I apply analytical rigor to every task. I approach problems systematically, breaking them down into manageable components before devising innovative solutions. This strategic mindset is instrumental in project planning and execution, ensuring that objectives are met efficiently and effectively.In the domain of research and writing, I am adept at conducting meticulous literature reviews, synthesizing information from diverse sources, and presenting findings coherently. My written work reflects a high degree of clarity,depth, and adherence to scholarly standards. I have published articles in reputable journals, showcasing my ability to contribute meaningfully to the intellectual discourse in my field.Lastly, I am passionate about continuous personal and professional growth.I believe in lifelong learning and hence invest time in staying updated with the latest trends and technologies in my industry. My adaptability and eagerness to learn new skills have allowed me to navigate through different roles and responsibilities with ease.In terms of extracurriculars, I also boast significant accomplishments in public speaking and debating, demonstrating my confidence and poise under pressure. Additionally, I am fluent in English, Mandarin, and Spanish, enabling me to engage in cross-cultural dialogue and collaborate effectively in international settings.In conclusion, my strengths lie in a blend of technical prowess, leadership acumen, critical thinking, research aptitude, and cultural sensitivity. These attributes equip me to excel in dynamic, challenging environments where innovation and collaboration are key. I continually strive to refine these skills and expand my horizons, driven by an insatiable curiosity and passion for excellence. Each day presents a new opportunity to deepen my knowledge, sharpen my abilities, and make meaningful contributions to any endeavor I undertake.This self-portrait, while highlighting my current proficiencies, underscores my commitment to ongoing improvement and the relentless pursuit of quality and high standards in all aspects of my life and career.。
十年后的景象,英语作文
十年后的景象,英语作文英文回答：A Decade of Transformation: Visions for the Future.As we embark on the threshold of a new decade, it is an opportune moment to envision the transformative shifts that will shape our world in the years to come. From technological advancements to societal changes, the next ten years hold the potential to unlock unprecedented possibilities.Technological Advancements.Artificial intelligence (AI) will continue to play a pivotal role in revolutionizing industries, from healthcare to manufacturing. AI-powered systems will enhance efficiency, optimize decision-making, and automate complex tasks, freeing up human capital for more creative andvalue-added endeavors.Quantum computing, still in its nascent stages, promises to unleash computational power that is orders of magnitude greater than anything currently available. This breakthrough will enable groundbreaking discoveries in fields such as materials science, drug development, and financial modeling.The internet of things (IoT) will connect billions of devices, creating a vast network of sensors and data that will streamline operations, improve infrastructure, and transform our daily lives.Societal Changes.Demographic trends will continue to reshape societies worldwide. An aging population will require innovative approaches to healthcare, elder care, and social security systems. Conversely, a growing youth population in developing countries presents both challenges and opportunities for education, employment, and civic engagement.Urbanization will intensify, with megacities becoming hubs of innovation, economic growth, and cultural diversity. However, this growth also presents challenges related to housing, transportation, and pollution.Climate change will remain a pressing issue, demanding urgent action to mitigate its effects and adapt to its consequences. Sustainable practices, renewable energy, and carbon capture technologies will play a critical role in preserving our planet for future generations.Global Interconnectedness.The world is becoming increasingly interconnected through globalization, trade, and technology. This interdependence will facilitate collaboration, innovation, and the sharing of ideas. However, it also poses challenges related to geopolitical tensions, economic inequality, and global governance.International organizations such as the United Nationsand the World Bank will continue to play a vital role in fostering cooperation, resolving conflicts, and promoting sustainable development.Ethical Considerations.As technology advances at an unprecedented pace, it is imperative to consider its ethical implications. AI systems must be designed with fairness, transparency, and accountability in mind. Genetic engineering and other emerging technologies raise complex questions about human enhancement and the limits of scientific intervention.It is crucial to engage in informed discussions and develop ethical frameworks that guide the responsible use of these technologies and safeguard our values and fundamental rights.Conclusion.The next decade holds immense promise and unprecedented challenges. By harnessing technological advancements,adapting to societal changes, and fostering global interconnectedness, we can create a future that is both equitable and sustainable. It is our collective responsibility to navigate the complexities of these transformative shifts and ensure that the fruits of progress are shared by all.中文回答：十年景象，未来愿景。
旋转编码器的原理（Principleofrotaryencoder）
旋转编码器的原理（Principle of rotary encoder）Rotary encoder principle.Txt comrades: do not stock, the risk is too great, or the most safe to do tofu! Do the hard, it is dried bean curd, do dilute is bean curd brain, do thin is bean curd skin, do not have is soya bean milk, put smelly, it is smelly bean curd! Can not lose! First, the principle and characteristics of rotary encoder:Rotary encoder is a speed displacement sensor which integrates light, mechanical and electrical technology. When the rotary encoder shaft drives the grating disk to rotate, the light emitted by the light emitting element is cut into intermittent light by the grating disk slit and is received by the receiving element to produce an initial signal. After the signal is processed by subsequent circuit, the pulse or code signal is output. The utility model has the characteristics of small size, light weight, wide variety, complete function, high frequency response, high resolving power, small torque, low energy consumption, stable performance, reliable service life, etc..1 、 incremental encoderWhen an incremental encoder rotates, it has a corresponding phase output. The judgement of the rotation direction and the increase or decrease of the pulse number need to be realized by means of the backward steering circuit and counter. The counting starting point can be arbitrarily set up, and the unlimited accumulation and measurement of the plurality of circles can be realized. The Z signal, which emits a pulse at each turn, is used as the reference zero. When the pulse is fixed and the resolution needs to be improved, the frequency of theoriginal pulse can be multiplied by two signals with 90 degrees of phase difference A and B.2. Absolute encoderAbsolute encoder shaft rotation sensor, are in one-to-one correspondence with the location of the code (binary, BCD code output, etc.) from the code size change can distinguish the positive and negative direction and displacement of the position, without judgment circuit. It has an absolute zero bit code. When the power or shutdown is switched on and re - measured, the code of the power failure or shutdown position can be read out accurately, and the zero bit code can be found accurately. In general, the absolute encoder range of measurement is 0~360 degrees, but the special model can also realize the multi circle measurement.3 、 sine wave encoderSine wave encoder is also an incremental encoder, the main difference is that the output signal is sinusoidal analog signals, rather than digital signals. Its appearance is mainly to meet the needs of the electrical field - as a feedback detection element of the motor. This coder can be used when people need to improve the dynamic characteristics on the basis of other systems.In order to ensure good performance of motor control, the feedback signal of encoder must be able to provide a large number of pulses, especially when the speed is low, the traditional incremental encoder to produce a large number ofpulses in many ways have problems, when the high-speed motor (6000rpm), transmission and processing of digital signals is difficult. In this case, the signal processing to the servo motor of the required bandwidth (e.g. encoder pulses per revolution of 10000) will easily exceed MHz threshold; on the other hand, the analog signal can greatly reduce the amount of trouble, and the ability to simulate the encoder pulse. Thanks to the interpolation of sine and cosine signals, it provides a computational method for rotation angles. This method allows for a high increase in fundamental sine, for example, to obtain more than 1000000 pulses per turn from each of the 1024 sine wave encoders.The bandwidth required to receive this signal is sufficient as long as a little greater than 100KHz. Interpolation frequency doubling needs to be completed by two systems.Two 、 output signal1, signal sequenceGeneral encoder output signal in addition to A and B two-phase (A, B two channel signal sequence phase difference of 90 degrees), each turn also output a zero bit pulse Z..When the main shaft rotates clockwise, the output pulse is shown as follows. The A channel signal is located before the B channel. When the spindle rotates counterclockwise, the A channel signal is located behind the B channel. From this we can judge whether the main shaft is positive or reverse.The differential signal output by the sine output encoder is shown in the following figure:2, zero signalEach revolution of the encoder sends a pulse, called a zero pulse or an identification pulse. The zero pulse is used to determine the zero position or the identification position. To accurately measure the zero pulse, regardless of the rotation direction, the zero pulse is used as a high output combination of the two channels. Because of the phase difference between the channels, the zero pulse is only half the length of the pulse.3, warning signalSome of the encoder and alarm signal output, you can power failure, light-emitting diode fault alarm, so that users can replace the encoder in time.Three 、 output circuit1, NPN voltage output and NPN open collector output lineThis circuit consists of only one NPN transistor and one pull-up resistor, so when the transistor is in static state, the output voltage is the supply voltage, and it is compatible with the TTL logic on the circuit, so it can be compatible with it. When there is an output, the transistor is saturated and the output turns to a low level of 0VDC, while the other side jumps from zero to positive voltage.As the cable length, the transmitted pulse frequency, and the load increase, the influence of this circuit form increases. Therefore, these effects should be taken into account in order to achieve the desired effect. The open collector line cancels the pull-up resistor. The collector and the power line feedback encoder this way transistor is different, it can obtain the current output signal with different voltage encoder.2, PNP and PNP open collector lineThe line is the same as the NPN circuit, the main difference is the transistor, which is PNP, whose emitter is forced to receive a positive voltage, and if there is a resistor, the resistor is pull-down and connected between the output and zero volts.3 、 push-pull circuitThis circuit is used to improve the performance of the circuit, so that it is higher than the aforementioned lines. In fact, the main limitations of the NPN voltage output line is because they use the resistance in the transistor off showed much higher impedance than the transistor, in order to overcome some shortcomings in the push-pull circuit, additional access to another transistor, whether this is also the positive direction is zero direction transformation, the output is low impedance. The push-pull circuit improves frequency and performance, and facilitates longer line data transmission, even at high rates. The level of signal saturation remains low, but is sometimes higher than the aforementioned logic. In any case, push pulllines can also be applied to receivers of NPN or PNP lines.4, long line drive circuitWhen the operating environment requires electrical interference, there is a long time between the encoder and the receiving systemDistance,Long term drive line can be used. Data is sent and received in two complementaryIn the channel, so interference is suppressed (interference is caused by cables or adjacent devices). This interference can be considered as "common mode interference"". In addition, the transmission and reception of the bus driver are performed in a differential manner, or the difference in voltage between the complementary transmission channels. Therefore, it is not third of common mode interference, the transmission that is compatible with the RS422 in the DC5V system; in the special chip, power up to DC24V, can be in bad conditions (cable length, strong interference etc.) use.5 、 differential lineDifferential lines are used in analog encoders with sinusoidal long line drives, which require the transmission of signals to be free from interference. Like long line drive circuits, two phase difference signals of 180 degrees are generated for digital signals. The circuit specifically sets up a uniqueimpedance of 120 ohms, which is balanced with the input resistance of the receiver, while the receiver must have equal load impedance. Usually, a 120 ohm terminal resistor is connected in parallel between complementary signals to achieve this purpose.Four, commonly used terms- the number of output pulses / revolutionTurn the rotary encoder output pulses, the optical rotary encoder and rotary encoder, usually within the same number of grooves (also in the circuit to make the output pulse number increased to 2 times the slot number 4 times).- resolutionThe resolution represents the maximum rotation of the rotary encoder and the maximum equal fraction of the readout position data. The absolute value does not output in pulse form, but represents the current spindle position (angle) in the form of code. Unlike an incremental type, it is equivalent to an incremental type of "output pulse / turn"".- gratingOptical rotary encoder with two kinds of gratings: metal and glass. If it is made of metal, it has a through hole; if it is made of glass, it is coated with an anti - light film on the surface of glass. There is no transparent line (groove) on it. If the number of slots is small, it can be machined on a metaldisk by punching or grooving. Metal gratings are used on impact resistant encoders, which are less shock resistant than metal gratings, so please note that the impact is not applied directly to the encoder in use.- the maximum response frequencyThe maximum number of pulses that can be answered within 1 secondExample: the maximum response frequency is 2KHz, that is, 2000 pulses can be answered in 1 secondFormula is as followsMaximum response speed (RPM) /60 * (pulse count / turn) = output frequency HzThe maximum response speed.Is the highest response speed, the pulse occurring at this speed is responsive to the formula as follows:Maximum response frequency (Hz) / (pulse number / turn) x 60= axis speed rpm- output waveformThe waveform of an output pulse (signal).In the output signal phase differenceThe relative time difference between two output pulse waveforms when two phases are output.- output voltageThe voltage of an output pulse. The output voltage varies with the output current. For each series of output voltages, refer to the output current characteristic diagram- starting torqueRotate the encoder shaft at rest to rotate the necessary torque.In general, the torque in operation is smaller than the starting torque.- axle allowable loadRepresents the maximum load that can be added to the shaft. There are two kinds of radial and axial loads. The radial load is vertical to the shaft, the force is related to the eccentricity, the deflection angle, etc. the axial load is horizontal in the shaft, and the force is related to the force of the push-pull shaft. The magnitude of these two forces affects the mechanical life of the shaft- axis moment of inertiaThis value represents the inertia of the rotating shaft and the resistance to the change in speed- speedThis speed indicates the mechanical load limit of the encoder. If this limit is exceeded, the service life of the bearing will be adversely affected, and the signal may also be interrupted.- grayGray code is advanced data, because it is a unit distance and cyclic codes, so it is safe. Only a step change. In data processing, the gray code must be converted into binary code.In the current workThe load current allowed by a channel.- working temperatureThe data and tolerances referred to in the parameter list are guaranteed in this temperature range. If slightly higher or lower, the encoder is not damaged. When the working temperature is restored, the technical specifications can be reached- working voltagePower supply voltage of encoder。
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Later in the paper, we try to resolve the ambiguities by determining the modification relation in the coordinate constructions (CCs) such as in (1) to (3).
2 Modification Relation in Coordination
Resolving ambiguities in a coordinate construction is to determine the way of conjoining constituents (words, phrases, or clauses) and/or to determine the scope of coordination, i.e., immediacy relations among the constituents involved. For instance, in sweet and sour pork, the right immediacy relation is ((sweet and sour) pork) rather than (sweet and (sour pork)). Consider other examples. (1) Tom is a ((stock and estate) keeper). (2) John is a (student and (chess player)). (3) Old men and women were left at the village. In each of these sentences, a noun or an adjective that appears in the left hand side of coordinator(s) has two (or more) modificant candidates: it may or may not modify the head noun in the right hand side.
3 Identifying Modification Relation in Coordination
We have found through linguistic observations that a variety of information supplies important cues for disambiguation. Some of them are computable and effectively used in a computer model of disambiguation. The ones we thought most important include: similarities in syntactic forms and/or meanings, selectional restrictions, and orthographic forms. 3.1 Linguistic Observations Similarities in Syntactic Forms and Meanings We see that similarities on forms and meanings are crucial to determine the structure of a coordinate construction. If the modifier is not an adjective, for instance, it is likely that two constituents before and after the coordinator are conjoined when they belong to the same subcategory and match in number: (4) ((business and management) sections) (5) (businesses and (culture activities)) In the following examples, (6) ((research and development) section) (7) (researcher and (system engineer)) it is obvious that the research and development have more in common in meaning than research and section, and that researcher and engineer are semantically more similar than researcher and system. Likewise, we see: (8) (lovely (cats and dogs)) *((lovely cats ) and dogs) Selectional Restrictions Consider the sentence: (9) Peter likes ((green vegetables) and (music)). we know in (9) that green as a color can be used to modify concrete entities like vegetables, but not abstract one like music. This means that selectional restriction (SR), a semantic restriction imposed on lexical items when forming a sentence, is an important factor to determining the structure of coordinate constructions. In this paper, we discuss SR in the context of adj+nl+and+n2 and its extension (e.g., adj n 1 , nk)2. Other Linguistic Cues Orthographic forms often play an important role in disambiguating the structures of coordinate constructions. It is likely that all nouns can be conjoined when they are in capital forms. An example: (10) ((Research and Development) Section) When the conjoined nouns in a coordinate structure are preceded by a determiner, the usual 1 In this case, the coordination of stock and estate keeper is considered to be the reduced form of stock keeper keeper. 2 Hereafter, and in adj+nl+and+n2 and in nl±and-f-n2+n3 represents a coordinator such as and, or, comma, and the like.
(3a) Women are left at the village and old men were left at the village. (3b) Old men were left at the village and old women were left at the village.
Abstract
This paper describes a method for determining syntactic structure in coordinate constructions. It is based on the information taken from semantic similarities, selectional restrictions, and some other linguistic cues. We discuss the role the information plays in resolving ambiguities that appear in coordinate constructions, describe the means of acquiring the necessary information automatically from two on-line corpora and a lexical database, and devise two algorithms for disambiguating coordinate constructions. An experiment that follows shows effectiveness of our method and its applicability to resolving ambiguities in some other syntactic structures.
1 Introduction
Syntactic ambiguity appears, among others, in coordinate constructions. It is an annoying problem in analyzing structure and meaning of a sentence. A parser, for instance, is to detect the scope of a coordinate structure and identify its inner modification relations. However, the current parsers (e.g., the Link parser) often fail to handle the problem and/or produce a large number of parses. There are a few computational studies that have tried to resolve ambiguities in coordinate constructions (e.g., Paritong, 1992; Cooper, 1991; Bayer, 1996). For example, Kurohashi and Nagao (1994), in analyzing long Japanese sentences, proposed a syntactic analysis method for detecting conjunctive structures by using lexical similarity and structural parallelism. Mela and Fouquere (1996) used a direct process to determine the scope of a coordinate structure based on the concept of functor, argument and subcategorization. Unfortunately, neither of them has sufficiently dealt with .the syntactic structure of a coordination especially when a coordinator (such as and, or and comma) has two or possibly more preceding and succeeding constituents. We in this paper propose a method for determining the structure of a coordinate construction using information on similarities, selectional restrictions, and oilier linguistic cues. In Section 2 we identify the problem and describe the ideas behind our method in Section 3. We give disambiguation algorithms, show an disambiguation experiment, and evaluate its results in Section 4. In Section 5 we suggest an applicability of our method to resolving other syntactic ambiguities.