A dynamic model for breaking pattern of level ice by conical structures _

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小学下册B卷英语第3单元全练全测

小学下册英语第3单元全练全测英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.What is the name of the famous children's book character who travels to a chocolate factory?A. AliceB. CharlieC. PeterD. Matilda2. A _______ (蜥蜴) can be seen basking in the sun.3.ts can improve water ______ and soil quality. (某些植物可以改善土壤质量和水分保持能力。

) Some pla4. A solution is formed when a solute dissolves in a _____.5.What is the main ingredient in salad?A. RiceB. LettuceC. BreadD. Pasta6.My ________ (玩具名称) brings joy to my day.7.What is the currency used in the United States?A. EuroB. DollarC. PoundD. YenB8. A rabbit has big _______ to help it hear everything around it.9. A __________ is a large piece of rock that has broken away from a larger mass.10.The ______ (秋风) can cause leaves to fall.11.My dad is a __________ (警察) and helps keep us safe.12.The Earth's ______ is a dynamic and ever-changing environment.13.We can ___ the rainbow. (see)14.She wears a _____ dress. (red/quick/small)15.In winter, I like to go ______ (滑冰).16.The chemical symbol for silicon is ______.17.What is the boiling point of water?A. 0°CB. 50°CC. 100°CD. 200°CC18.My brother is my best _______ (我哥哥是我最好的_______).19.I have a _____ (question/answer) for you.20. A ______ is a geological feature that attracts scientists and researchers.21.What do you call the process of removing hair?A. ShavingB. WaxingC. PluckingD. All of the above22.What is the main ingredient in bread?A. SugarB. FlourC. RiceD. SaltB23.What do we call the act of encouraging community involvement?A. EngagementB. ParticipationC. VolunteerismD. All of the AboveD24.What do we call the study of living organisms?A. BiologyB. AstronomyC. ChemistryD. Physics25.The sloth hangs from branches with its _______ (爪子).26.I have a pet ______.27.What is the opposite of fast?A. SlowB. QuickC. RapidD. Swift28.The ______ (鸭子) quacks when it swims.29.The teacher is ______ (helping) us with homework.30.The mosquito bites _______ (人) for blood.31.Which planet is known as the Red Planet?A. EarthB. VenusC. MarsD. JupiterC Mars32.My favorite color is ________.33.__________ are used in the production of cosmetics.34.The _____ (花园) is full of colorful plants.35.ts can grow in _____ (沙土). Some pla36. A lion's mane indicates its ________________ (健康) and dominance.37.What is the term for a baby horse?A. CalfB. FoalC. KidD. LambB38.I have a toy _______ that can bounce high.39.The ______ teaches us about modern technology.40.Which of these is a vegetable?A. BananaB. TomatoC. GrapeD. MangoB41.Which animal is known as "man's best friend"?A. CatB. DogC. RabbitD. Fish42.What is the name of the famous wizarding school in Harry Potter?A. HogwartsB. BeauxbatonsC. DurmstrangD. IlvermornyA43.The main component of the atmosphere is _____.44.What is the name of the first manned moon mission?A. Apollo 11B. Gemini 12C. Mercury 7D. Voyager 1A Apollo 1145.What is the name of the currency used in Japan?A. YenB. YuanC. WonD. DollarA46.The chemical symbol for barium is ______.47.What is the name of the famous artist who painted the ceiling of the Sistine Chapel?A. RaphaelB. MichelangeloC. Leonardo da VinciD. Titian48.The ______ is a popular aquarium fish.49.What is the capital city of Malta?A. VallettaB. MdinaC. SliemaD. Birkirkara50.What is the capital of South Africa?A. JohannesburgB. PretoriaC. Cape TownD. DurbanB51.What do we call the process of creating a plan?A. OrganizingB. PlanningC. StrategizingD. Arranging52.The __________ (历史的交汇) enriches our understanding.53.The ________ (食物链) begins with plants.54.Reading books about _________ (玩具) can spark my _________ (想象力).55.What do we call the outer layer of the Earth?A. CoreB. MantleC. CrustD. ShellC56.What sound does a cow make?A. MeowB. BarkC. MooD. Quack57.The _______ (The Harlem Renaissance) was a cultural movement in the 1920s.58.The __________ can be very hot during July. (天气)59.The sun sets and the sky is ______. (beautiful)60. A mixture that has a uniform appearance is called a ______ mixture.61.What do you call a story that is not true?A. FactB. FictionC. RealityD. TruthB62.What is the opposite of ‘big’?A. LargeB. SmallC. HugeD. Tall63.The _______ can help create a welcoming atmosphere.64.What is the capital of Indonesia?A. ManilaB. JakartaC. HanoiD. Bangkok65.The study of landforms is an important part of ______ science.66.The ancient Romans were renowned for their ________ and public works.67. A ______ can develop into various forms.68.We bake _____ (bread/cake) for the festival.69.What do we call the time when the sun rises?A. SunsetB. SunriseC. NoonD. Midnight70.The cat loves to explore the _____ backyard.71. A rock can become a metamorphic rock through heat and ______.72.The __________ (历史的思维模式) inspires innovation.73.My dad inspires me to be __________ (勇敢的) in life.74.The pig loves to roll in ______ (泥).75.Chemical bonds can be ionic or ________.76.What do we call a large, slow-moving animal with a shell?A. TurtleB. TortoiseC. SnailD. SlugB77.The _____ (小猪) loves to roll in the mud. It is very funny! 小猪喜欢在泥里打滚。

软件设计师中级专业英语词汇

软件设计师中级专业英语词汇Software Designer: Intermediate Professional English Vocabulary.In the realm of software development, proficiency in professional English is paramount for effective communication, documentation, and collaboration. For mid-level software designers, a robust command of industry-specific vocabulary is essential to navigate complex technical discussions, comprehend documentation, and convey design concepts with precision. This article aims to provide an expansive list of intermediate-level English vocabulary tailored specifically to software designers, enabling them to enhance their professional communication and elevate their design capabilities.Core Concepts.Algorithm: A set of well-defined instructions that solve a specific problem or perform a computation.Architecture: The overall structure and organization of a software system, including its components and their interactions.Data structure: A way of organizing and storing data in a computer system to facilitate efficient access and manipulation.Design pattern: A reusable solution to a commonly occurring problem in software design.Framework: A reusable set of software components and libraries that provide a foundation for building specific applications.Methodology: A structured approach to software development, including processes, practices, and tools.Object: A data structure that encapsulates data and behavior, representing real-world entities.Requirement: A documented need or capability that a software system must fulfill.Source code: The human-readable text form of a computer program, written in a specific programming language.Testing: The process of evaluating the correctness and functionality of a software system.Components and Technologies.Application Programming Interface (API): A set of routines, protocols, and tools that define how two applications interact.Cloud computing: A model for delivering computing resources over the Internet.Database: A collection of organized data, typically stored electronically.Front-end: The part of a software application that interacts directly with the user.Middleware: Software that connects and facilitates communication between different parts of a software system.Operating system: The software that manages computer hardware and provides common services to applications.Server: A computer that provides services to other computers or devices over a network.Web service: A software system that allowsapplications to communicate over the Internet using standardized protocols.Development and Design.Agile: A software development methodology that emphasizes flexibility, adaptation, and customer collaboration.Design thinking: A human-centered approach to design that focuses on understanding user needs and preferences.Iterative development: A software development approach where the system is developed and refined incrementally.Kanban: A visual project management system that uses cards to represent tasks and their progress.Mockup: A low-fidelity representation of a software interface, used for design review and feedback.Prototype: A working model of a software system, used to test concepts and gather user feedback.Scrum: An agile software development framework that emphasizes collaboration, transparency, and iterative delivery.Technical debt: Code or design decisions that may compromise future development or maintenance.User experience (UX): The overall experience of a user when interacting with a software system.Documentation and Communication.Documentation: Written or visual information that explains the design, implementation, and use of a software system.Formal specification: A precise and unambiguous description of a software system's behavior.Issue tracker: A system for tracking and managing bugs or other issues in a software project.Knowledge base: A repository of information and resources related to software development.Meeting agenda: A document that outlines the topics and objectives of a meeting.Proposal: A document that outlines a plan or solutionfor a software project.Technical report: A document that describes theresults of a technical investigation or analysis.White paper: A technical document that provides in-depth information on a specific topic.Wireframe: A low-fidelity representation of a software interface, used for planning the layout and structure.Additional Vocabulary.Binary tree: A data structure that consists of nodes arranged in a hierarchical manner, with each node having at most two child nodes.Cache: A temporary storage area that stores frequently accessed data to improve performance.Cipher: A method of encrypting data to protect its confidentiality.Debugger: A tool that helps identify and fix errors in code.Heap: A dynamic data structure that stores data in a tree-like structure.Inheritance: A mechanism that allows a new class to inherit attributes and methods from an existing class.Polymorphism: A language feature that allows objects of different classes to respond to the same method call differently.Recursion: A technique where a function calls itself, typically to solve a problem by breaking it down into smaller subproblems.Virtual machine: A software layer that simulates a computer system, allowing multiple operating systems to run on a single physical machine.By incorporating these intermediate-level vocabulary terms into their professional communication, software designers can elevate their discourse, enhance their problem-solving abilities, and become more effective collaborators in the dynamic and challenging world of software development.。

为你的学校夏季运动会设计一个海报英语作文

为你的学校夏季运动会设计一个海报英语作文The Summer Sports Festival is an annual tradition at our school, a much-anticipated event that brings the entire community together in a celebration of athletic achievement and school spirit. As a member of the school's marketing committee, I have been tasked with designing a poster to promote this year's festivities. This is an exciting opportunity to showcase the vibrancy and energy of our school while encouraging widespread participation in the upcoming games.In conceptualizing the design, I wanted to capture the essence of the Summer Sports Festival – the thrill of competition, the camaraderie of teammates, and the pride of representing one's school. The poster should be eye-catching and dynamic, immediately conveying the athletic prowess and youthful enthusiasm that define this event.The central image of the poster will be a collage of action shots showcasing a diverse array of sports. From the grace and power of abasketball player soaring for a layup, to the determination etched on the face of a sprinter breaking through the finish line, these vivid snapshots will instantly ignite the viewer's excitement. By highlighting a range of athletic disciplines, from track and field to aquatics to team sports, I aim to reflect the inclusive and comprehensive nature of the Summer Sports Festival.Surrounding these dynamic sports images, I will incorporate vibrant splashes of color that evoke the festive atmosphere of the event. Bold, contrasting hues of red, yellow, and blue will create a sense of movement and energy, drawing the eye across the poster's design. These color choices also subtly reference the school colors, reinforcing a sense of school pride and community.To further cultivate this spirit of unity, I will prominently feature the school's logo and name at the top of the poster. This will serve as an instantly recognizable identifier, letting viewers know that this is an official school event. Additionally, I will include the date, time, and location of the Summer Sports Festival in a clean, easy-to-read typographic treatment. This will ensure that all the key logistical details are clearly communicated to potential attendees.In terms of the poster's overall layout, I envision a dynamic, asymmetrical composition that creates a sense of movement and energy. Rather than a static, symmetrical design, I will strategicallyposition the various elements to guide the viewer's eye across the poster. The sports imagery will be arranged in a diagonal pattern, with the vibrant color splashes emanating outward from these focal points. This will give the poster a sense of depth and dimension, making it visually engaging and compelling.To complement the bold, energetic aesthetic of the poster, I will utilize a modern, sans-serif typeface for the text elements. This clean, streamlined font will ensure readability while also aligning with the poster's youthful, athletic vibe. I may also incorporate a subtle graphic element, such as a stylized athlete icon or a dynamic line motif, to further unify the design and add a touch of sophistication.Throughout the design process, I will be mindful of ensuring that the poster is visually striking and immediately captivating, yet also conveys the essential information that potential attendees will need. The goal is to create a design that not only generates excitement for the Summer Sports Festival but also clearly communicates the key details, making it easy for the school community to get involved and participate.As I finalize the poster design, I will also consider ways to optimize it for various platforms and applications. In addition to the primary printed version that will be displayed around the school and in the local community, I will create digital versions that can be shared onthe school's website and social media channels. This will allow the poster to reach a wider audience and effectively promote the event across multiple touchpoints.Designing the poster for the Summer Sports Festival is a wonderful opportunity to showcase my creative skills while also contributing to the vibrant culture of our school. By crafting a visually striking and informative design, I hope to inspire students, faculty, and families alike to come together and celebrate the athletic achievements and school spirit that make our community so special. I am excited to bring this vision to life and play a role in making the upcoming Summer Sports Festival a resounding success.。

DFIG_Modeling

Doubly-Fed Induction Machine Models for Stability Assessment of Wind FarmsMarkus A.P¨o llerAbstract—The increasing size of wind farms requires power sys-tem stability analysis including dynamic models of the wind power generation.Nowadays,the most widely used generator type for units above1MW is the doubly-fed induction machine.Doubly-fed induction machines allow active and reactive power control through a rotor-side converter,while the stator is directly con-nected to the grid.Detailed models for doubly-fed induction ma-chines are well known but the efﬁcient simulation of entire power systems with hundreds of generators requires reduced order mod-els.This paper presents a fundamental frequency doubly-fed in-duction machine model including a typical control system and dis-cusses the accuracy of reduced order models under various oper-ating conditions.Index Terms—doubly-fed induction machines,off-shore wind power generation,power system stability,wind power generation, variable speed drivesI.I NTRODUCTIONT HE totally installed wind power capacity is constantly increasing.End of June2002,there were wind turbines with a total rated power of9837,27MW installed in Germany[1].Not only the overall installed wind power capacity,but also the average rated power per wind mill is constantly increasing.In Germany,during theﬁrst six months of2002,the average rated power per wind turbine went up to 1314kW,which is an increase of8%compared to the same period in 2001[1].Especially for wind mills above2,0MW,the doubly-fed induction generator is the most widely used generator concept(e.g.GE Wind Energy,Vestas,RE Power,Nordex,NEG Micon).Theseﬁgures clearly show that there is a strong need for power sys-tem stability analysis,including dynamic models of on-and off-shore wind farms.For dynamic power system analysis,different models, from fully detailed to highly reduced order models are proposed in the literature(e.g[5],[4]),but standard doubly-fed induction machine models for modeling large power systems are still under investigation [2].This paper presents an approach for standard doubly-fed induction machine models for stability analysis.It includes models of all com-ponents,the induction generator,the rotor-side-and the grid-side con-verters and typical approaches for the control circuits and aerodynam-ics of the wind turbine.All models have been implemented and tested in the power system analysis program DIgSILENT PowerFactory[10].II.T HE D OUBLY-F ED I NDUCTION M ACHINE C ONCEPT Figure1shows the general concept of the doubly-fed induction gen-erator.The mechanical power generated by the wind turbine is trans-formed into electrical power by an induction generator and is fed into the main grid through the stator and the rotor windings.The rotor winding is connected to the main grid by self commutated AC/DC converters allowing controlling the slip ring voltage of the induction machine in magnitude and phase angle.Markus P¨o ller is with DIgSILENT GmbH,Heinrich-Hertz-Str.9,72810Go-maringen,Germany(email:m.poller@digsilent.de)Rotor-Side Grid-SideFig.1.Doubly-fed induction generator systemIn contrast to a conventional,singly-fed induction generator,the electrical power of a doubly-fed induction machine is independent from the speed.Therefore,it is possible to realize a variable speed wind generator allowing adjusting the mechanical speed to the wind speed and hence operating the turbine at the aerodynamically optimal point for a certain wind speed range.III.I NDUCTION G ENERATORr x x rFig.2.Equivalent circuit of the doubly-fed induction generator Fig.2shows the equivalent circuit diagram of the doubly-fed induc-tion generator from which the model equations in a constantly,with rotating reference frame can be derived as follows:(1)(2) Theﬂux linkage can be expressed by the following equations:(4) The induction machine model is completed by the mechanical equa-tion:The electrical torque is calculated from the stator current and the stator ﬂux:(6)All quantities are expressed in a stator-side per unit system.This induction machine model of ﬁfth order is able to represent rotor and stator transients correctly.In stability studies however,transient phenomena of the electrical network are usually not considered [7].Applying the principle of neglecting stator transients to the doubly-fed induction machine model leads to the following third order model:(7)(8)The mechanical equation is the same as in case of the ﬁfth order model.Neglecting rotor transients results in a ﬁrst order induction machine model that consists of steady-state stator and rotor voltage equations.(9)(10)The only dynamic equation of the ﬁrst order model is the mechanical equation according to (5).A.Rotor Current Protectionu r x x r c cFig.3.Doubly-fed induction generator with inserted crow-bar protection (andIn case of faults near to the generator,rotor currents are increasing and risk to damage the rotor-side converter.For avoiding any damages,the rotor-side converter is bypassed when the rotor currents exceed a certain limit (”crow-bar”protection,see Fig.3).While the rotor-side converter is bypassed,the generator operates as a normal induction generator.Since the speed can be considerably above synchronous speed before a fault occurs or the machine quickly accelerates during a fault,the stalling point of the machine is usually exceeded during a fault leading to very high reactive power consump-tion.Bypassing the rotor with an additional resistance and an addi-tional reactance (see and in Fig.3)shifts the stalling point to a higher speed value and reduces the machine’s reactive power con-sumption considerably .This mode of operation can be considered in the rotor-voltage (2)and the rotor ﬂux-linkage equation (4)as follows:(11)(13)The AC-voltage phase angle is deﬁned by the PWM converter.The pulse-width modulation factor is the control variableof the PWM converter.Equation (13)is valid for .For values larger than 1the converter starts saturating and the level of low order harmonics starts increasing.The complete characteristic of the PWM converter,including the saturated range is shown in Fig.5.Fig.5.PWM Converter fundamental frequency characteristicThe converter model is completed by the power conservation equa-tion:3A.Rotor-Side ConverterThe rotor-side converter operates in a stator-ﬂux dq-reference frame that decomposes the rotor current into an active power(q-axis)and a reactive power(d-axis)component.A very fast inner control loop regulates the active-and the reactive component of the rotor current.The current-setpoints are deﬁned by a slower outer control loop regulating active and reactive power(see Fig.6).Fig.6.Rotor-side converter controllerB.Grid-Side ConverterThe control concept of the grid-side converter is very similar to the rotor-side controller concept.The grid-side converter controller oper-ates in an AC-voltage dq-reference system.Active and reactive com-ponents of the grid-side converter currents are regulated by a fast inner control loop(see Fig.7).A slower outer control loop deﬁning the q-current setpoint regulates the DC-voltage to a pre-deﬁned value.The setpoint of the d-axis component can be used for optimum reactive power sharing between the generator and the grid-side converter or simply kept to a constantvalue.Fig.7.Grid-side converter controllerC.Reactive Power ControlReactive power control is possible through the d-axis component of the rotor-and the grid-side converters.Variable speed wind power gen-erators can be operated at a constant power factor,which is the stan-dard operation mode today.Alternatively,an AC-voltage controller deﬁning the d-axis current setpoint can be used in Fig.6instead of the Q-controller,or secondary voltage control can be supported by adjust-ing the Q-reference value(e.g.[4]).D.Reduced Order Converter ModelFor longer term simulations,when calculation time becomes an im-portant issue,it might be desirable to neglect the very fast time con-stants associated with the DC intermediate circuit shown in Fig. 4. When neglecting the DC-capacitance,the DC currents of the rotor-and grid-side converters are forced to be equal.Consequently,the grid-side controller must be replaced by an ideal voltage controller,without the inner current control loops.On the AC side,the active power injection is deﬁned by the power conservation between AC and DC according to (14).For deﬁning the reactive power balance,the d-axis current com-ponent(reactive current)of the grid-side converter can directly be set by a reactive power controller or a constant reactive current component can be assumed.A further model reduction consists of completely neglecting the time constants of the DC voltage controller.The grid-side converter and it’s controls is then modeled by a steady-state device,keeping the DC voltage constant.With this simpliﬁcation however,saturation ef-fects(see Fig.5)in the grid-side controller cannot be considered. E.Turbine ControlEquation(15)shows the aerodynamic equation of a wind turbine that relates mechanical power to wind speed and mechanical speed of the turbine(e.g.[5]):(16) with being the mechanical frequency of the wind turbine.Equation(15)deﬁnes the steady-state aerodynamic behaviour of a wind turbine;it cannot reﬂect dynamic stall effects correctly.An ap-proximate method for including dynamic stall effects is described in [9].Fig.8.Generic wind turbine modelFig.9.Generic model of the pitch-control systemA generic wind turbine model for stability studies based on a max-imum power tracking strategy[5]can be implemented according to Fig.8.4In case of rotor frequencies below,active power is regulated according to the maximum power tracking(MPT)characteristic that deﬁnes the maximum power depending on the shaft speed as power reference of the power controller.When the maximum shaft speed is reached,the active power setpoint remains constant and the pitch angle control system(see Fig.9)starts acting driving the shaft speed back to the maximum permitted value.An alternative control scheme is described in[4].Here,the speed reference is calculated from the actually generated electrical power (inverse MPT characteristic).As a result,the generator is driven into optimal speed.When is reached,the pitch angle control takes over and regulates the actual power to.F.Wind FluctuationsWindﬂuctuations can be modeled by varying the wind-speed-input of the aerodynamic block in Fig.8.Wind speed is usually modeled by superposing several deterministic and stochastic components.However,since the response of doubly-fed induction machines to system faults is in the center of interest of this paper and wind speed can be assumed to be constant in these cases, no concrete wind-speed models are described here.Generally,com-mon wind-speed models(e.g.[9])can be combined with the models presented in this paper.G.Torsional OscillationsWhen the simulated applications are limited to the impact of wind ﬂuctuations,it is usually sufﬁcient to consider just a single-mass shaft model because shaft oscillations of variable speed wind generators are not reﬂected to the electrical grid due to the fast active power control.[5].In stability analysis however,when the system response to heavy disturbances is analyzed,the shaft must be approximated by at least a two mass model.One mass represents the turbine inertia,the other mass is equivalent to the generator inertia.The equations describing the mechanical coupling of turbine and generator through the gear box by a two-mass model can be expressed as follows(see e.g.[8]):(18)The electrical torque is deﬁned by(6).VI.C ASE S TUDIESFor validating the presented models,the results of simulating a heavy and a relatively weak disturbance in the system shown in Fig. 10are described.The system consists of an external infeed modeled by a source behind an impedance that is connected to a synchronous generator through a line.And wind farm consisting of three doubly-fed induction generators with a rating of5MW each is connected to the mid-point of the transmission line.Each doubly-fed induction generator is modeled according to Fig. 11,including the three winding transformer,the induction generator, the grid-side and the rotor-side converter and the intermediate DC-circuit.Fig.10.Power system used for model validationA.Strong DisturbanceTheﬁrst case simulates a solid three phase short circuit(duration: 200ms)at the”Connection Point”(see Fig.11).The rotor-current-protection systems bypass the rotor-side converters immediately after the fault has been inserted(see Fig.12and Fig.13).After the fault was cleared,at t=200ms,the generators continue to operate with bypassed converters until t=800ms,when the”crow-bars”are removed.When the converters are back into operation,the system is driven back to the initial state.The speed shows a weakly damped torsional oscillation.Fig.12compares the results obtained with aﬁfth order induction generator model according to(1)and a third order model according to (7).In the simulation of theﬁfth order model,not only stator transients of the induction machine but also the transient behaviour of transform-ers and lines was considered(EMT-compatible network model).Together with the third order machine model,a quasi-steady-state network model was used,corresponding to the classical”stability”-approach as described e.g.in[7].When comparing the results from both models,as shown in Fig. 12,it can be noted that the reduced order model represents the average of power and voltage very well.Higher frequency transients,as they can be observed in the results from the detailed model,are due to net-work transients and are therefore not represented by the reduced order model.The reduced order model can therefore be used for analyz-ing the inﬂuence of doubly-fed induction machines to the power sys-tem,but it is not possible to predict peaks in electrical power or torque correctly.Therefore,theﬁfth order model together with a”transient”network model is required.5Fig.11.Wind Generator with detailed grid-side converterThe”speed”variable highlights differences between the two mod-els:In the detailed model,the speed is initially reduced before the system starts accelerating.In the reduced order model however,the machine starts accelerating immediately after the fault was inserted.The initial speed reduction,as shown by the detailed model,is a consequence of decaying DC-components in the machine’s currents and is known as the”back-swing”effect of electrical machines.Since the third order model does not represent stator transients,the initial back-swing is not represented by the reduced order model leading to an immediate acceleration.Fig.13compares the results of further model reductions:1)Third order model with detailed grid-side converter,the same asin Fig.122)Third order model with simpliﬁed grid-side converter,as de-scribed in section V-D(complete reduction of the intermediate DC-circuit.)3)First order model with simpliﬁed grid-side converter.All results are in good agreement.Especially the reduction of the grid-side converter does not seem to have a big impact on the model accu-racy when system stability is studied.Theﬁrst order model however does not represent any rotorﬂux transients and differs therefore from the other curves during a short period after a heavy disturbance.With regard to computational efﬁciency,some information about the integration step-size might be of interest.All models were imple-mented and tested in DIgSILENT PowerFactory[10].PowerFactory uses a variable step size algorithm,in which the minimum step size can be speciﬁed by the user.During the simulation,the step size is auto-matically increased whenever the accuracy of the numerical algorithm allows for it.In case of the fully detailed,ﬁfth order machine model in combi-nation with a transient network model(Fig.12),the step size varied between ms and ms.In case of the reduced order models together with the steady-state network model it varied between ms and ms. The calculation time of the third order andﬁrst order model was prac-tically the same.B.Weak DisturbanceIn a second case,a three phase short circuit at the synchronous generator terminal was simulated(”Gen-LV-Bus”).This short circuitparison ofﬁfth order and third order model in case of a three phase fault near to the wind generatorscauses the voltage at the wind park terminal to drop to about0.6p.u. (see Fig.14).Because the rotor current protection is not triggered,the disturbance can be classiﬁed as a fault remote from the wind park.As Fig.14shows,the three wind turbines are differently loaded in this case.While the fault is in the system,the active and reactive power con-trollers remain in operation why active and reactive power is fully con-trolled.Clearing the fault disturbs the system again,but active and reactive power are well regulated.The speed of all turbines shows a weakly damped torsional oscillation.These simulations were carried out with the third order model and the simpliﬁed grid-side converter model.The model represents very well the initial active and reactive power transients and the controller response following to the disturbance.VII.C ONCLUSIONSThis paper presented a variable speed wind generator model suited for stability analysis of large power systems with large on-shore and off-shore wind farms.The presented components were the doubly-fed induction generator,the grid-side converter,the rotor-side converter, the aerodynamic behaviour of the wind turbine and the pitch control system.For simulating powerﬂuctuations,the wind speed variable must be fed from a measurementﬁle,or stochastic wind models must be used (e.g.[9]).Possible model reductions making the model suitable for stability assessment in large power systems were presented and discussed.6parison of models of various order in case of a three phase fault near to the wind generatorsThe models were implemented and tested in the power system anal-ysis package DIgSILENT PowerFactory [10].Every reduced order model was validated against higher order models.The results of the test cases show that a third order induction ma-chine model including crow bar protection together with a simpliﬁed model of the grid-side converter provides sufﬁcient accuracy and the necessary computational efﬁciency for carrying out stability studies in large power systems with several hundreds of machines.R EFERENCES[1] C.Ender,“Wind Energy Use in Germany -Status 30.06.2002,”DEWIMagazin Nr.21,August 2002[2]S.Stapelton and George Rizopoulos,“Dynamic Modelling of ModernWind Turbine Generators and Stability Assessment of On-and Off-Shore Wind Farms ”Proceedings of the 3rd MED POWER Conference ,2002[3] C.R.Kelber and W.Schumacher,“Adjustable Speed Constant FrequencyEnergy Generation with Doubly-Fed Induction Machines”Proceedings of the European Conference Variable Speed in Small Hydro,Grenoble,France ,2000[4]J.L.Rodriguez-Amenedo,“Automatic Generation Control of a WindFarm With Variable Speed Wind Turbines,”IEEE Transactions on En-ergy Conversion ,V ol 17,No.2,June 2002[5]J.G.Slootweg,S.W.H.de Haan,H.Polinder,W.L.Kling,“AggregatedModelling of Wind Parks with Variable Speed Wind Turbines in Power System Dynamics Simulations,”Proceedings of the 14th Power Systems Computation Conference ,Sevilla,2002[6]W.Hofmann and F.Okafor “Doubly-Fed Full-Controlled Induction WindGenerator for Optimal Power Utilisation,”Proceedings of the PEDS’01,2001Fig.14.Simulation of a weak disturbance (without crow-bar insertion)[7]P.Kundur “Power System Stability and Control,”McGraw-Hill,Inc.,1994[8]P.M.Anderson,B.L.Van Agrawal and J.E.Ness,“SubsynchronousResonance in Power Systems,”IEEE Press,New York ,1989[9]P.Soerensen, A.D.Hansen,L.Janosi,J.Bech and B.Bak-Jensen “Simulation of interaction between wind farm and power system”,Technical-Report,Risoe-R-128(EN),2001,http://www.risoe.dk/rispubl/VEA/veapdf/ris-r-1281.pdf[10]DIgSILENT GmbH “DIgSILENT PowerFactory V13-User Manual,”DIgSILENT GmbH ,2002Markus P¨o ller was born in Stuttgart,Germany on July 22,1968.In 1995,he received Dipl.-Ing.degrees from the Uni-versity of Stuttgart and Ecole Nationale Sup´e rieure des T´e l´e communications Paris.In 2000,he received the Dr.-Ing.degree from the University of Hannover.Since 1995he works with DIgSILENT GmbH,Ger-many,where he is responsible for the algorithms and models of the power system analysis software DIgSI-LENT PowerFactory .He is also involved in power system studies and he presents software-and powersystem analysis courses.His current research interests include wind power sys-tems,optimal power ﬂow dispatch and probabilistic load ﬂow analysis.。

A Model for Dynamic Shape and Its Applications

A Model for Dynamic Shape and Its ApplicationsChe-Bin Liu and Narendra AhujaBeckman InstituteUniversity of Illinois at Urbana-ChampaignUrbana,IL61801,USAcbliu,ahuja@AbstractVariation in object shape is an important visual cue for de-formable object recognition and classiﬁcation.In this pa-per,we present an approach to model gradual changes in the-D shape of an object.We represent-D region shape in terms of the spatial frequency content of the region con-tour using Fourier coefﬁcients.The temporal changes in these coefﬁcients are used as the temporal signatures of the shape changes.Speciﬁcally,we use autoregressive model of the coefﬁcient series.We demonstrate the efﬁcacy of the model on several applications.First,we use the model pa-rameters as discriminating features for object recognition and classiﬁcation.Second,we show the use of the model for synthesis of dynamic shape using the model learned from a given image sequence.Third,we show that,with its capa-bility of predicting shape,the model can be used to predict contours of moving regions which can be used as initial es-timates for the contour based tracking methods.1.IntroductionChanges in the shape of a dynamic object offer important cues for object recognition.In this paper,we are concerned with models of gradual changes in the shape of a-D region. We present a simple model of shape variation which was seen limited use in the past work.This model models the changes in the-D shape of a region in terms of the changes in its contour representation.Speciﬁcally,an autoregressive time series model of the changes in the Fourier coefﬁcients of the region contour is used.We use it to model,recognize, and synthesize-D dynamic shape.We present applications to(i)modelingﬁre motion and detectingﬁre in video se-quences,(ii)classiﬁcation of objects based on motion pat-terns,(iii)synthesis of novel image sequences of evolving shapes,and(iv)object boundary prediction for use by con-tour tracking methods.The-D shape representation and its use has received much attention in computer vision.A survey of shape anal-ysis methods can be found in[7].Pavlidis[11]proposed the following three classiﬁcations for shape based methods us-ing different criteria.(i)Boundary(or External)or Global (or Internal):Algorithms that use region contour are classi-ﬁed as external and boundary,such as Fourier transforms based approaches;Those that use interior region for the analysis are classiﬁed as internal and global,such as mo-ment based methods.(ii)Numeric or Non-numeric:This classiﬁcation is based on the result of the analysis.For in-stance,medial axis transform generates a new image with a symmetric axis,and is categorized as non-numeric.In con-trast,Fourier and moment based methods produce scalar numbers,and thus are in numeric category.(iii)Informa-tion Preserving or Non-preserving:Approaches that allow users to reconstruct shapes from their shape descriptors are classiﬁed as information preserving.Otherwise,they are information non-preserving.We propose a dynamic shape model that describes shape at any given time using Fourier transform coefﬁcients and an autoregressive(AR)model to capture the temporal changes in these coefﬁcients.The Fourier description pos-sesses boundary,numeric,and information preserving prop-erties.The autoregressive model is a simple probabilistic model that has shown remarkable effectiveness in the map-ping and prediction of signals.As Srivastava[19]points out,the temporal change of Fourier representation may not be linear.However,a linear model is more manageable to approximate such a process,and requires a small number of observations to estimate parameters.The remainder of this paper is organized as follows.In Section2,we present our dynamic shape model and its pa-rameter estimation.In Section3,we apply the proposed ap-proach to modeling and detection ofﬁre in video sequences. In Section4,we classify several objects and visual phe-nomena based on their evolving region contours.In Sec-tion5,we apply the model to synthesis of evolving shape sequences.In Section6,we use our model to predict ob-ject shape in a video sequence for object contour tracking. Section7discusses the limitations of the proposed model. Section8summarizes the contribution of this work.2.Dynamic Shape ModelOur dynamic shape model includes two parts:a spatial rep-resentation of-D shape and a temporal representation of shape variation.The detailed model and its parameter es-timation are described in the following sections.We also compare our model to other relevant models.2.1.Spatial Representation of ShapeFourier Descriptors(FD),the Fourier Transform coefﬁ-cients of the shape boundary,represents a-D shape us-ing an-D function.There are several variations of Fourier based-D boundary representation in literature[9].In this paper,we use Persoon and Fu’s method[13]for its simplic-ity.Given an extracted region in an image,weﬁrst retrieve its boundary using eight-connected chain code.Assume that we have points from the chain code representation of the boundary.We express these points in complex form:where are the image coordi-nates of boundary points as the boundary is traversed clock-wise.The coefﬁcients of the Discrete Fourier Transform (DFT)of are(1) If harmonics are used(),the coefﬁcients are the Fourier Descriptors used to character-ize the shape.To reconstruct boundary pointsusing harmonics,we perform inverse DFT as:(2)Note that represents the center of grav-ity of the-D boundary,which does not carry shape infor-mation.We neglect this term to achieve translation invari-ance for recognition and classiﬁcation.We keep this term for synthesis and shape prediction because it accounts for scale changes.Most related works in Fourier based shape description discuss about similarity measures that make FD invariant to relevant transformations,e.g.,rotation,translation and scal-ing.The requirement for each invariance depends on the applications.In this paper,we do not consider rotation in-variance because we need to reconstruct the boundary of shape.Since rotation invariance is not relevant,we can always choose the starting point as the topmost boundary pixel along the vertical axis through the center of gravity of the entire shape.Our representation approximates scale in-variance(if we drop term)since we have dense sampling of points along region boundary using chain code.Chain code expression discretizes the arc and Equation(1)nor-malizes the arc length.2.2.Temporal Representation of Shape Varia-tionThe stochastic characteristics of boundary motion are esti-mated by an autoregressive model of changes in Fourier co-efﬁcients of the region boundary.The autoregressive(AR) model,also known as a linear dynamical system(LDS),is used based on the assumption that each term in the time se-ries depends linearly on several previous terms along with a noise term[8].In this work,the AR model is used to capture different levels of temporal variation in FDs.Suppose are the-dimensional random vectors ob-served at equal time intervals.The-variate AR model of order(denoted as AR()model)is deﬁned as(3) The matrices are the coefﬁcient matrices of the AR()model,and the-dimensional vectors are uncor-related random vectors with zero mean.The-dimensional parameter vector is a vector of intercept terms that is in-cluded to allow for a nonzero mean of the time series.Our dynamic shape model uses FDs to represent shape, so the random vector is in a form of FD at time. To select the optimum order of the AR model,we adopt Schwarz’s Bayesian Criterion[16]which chooses the order of the model so as to minimize the forecast mean-squared error.We estimate the parameters of our AR model using Neumaier and Schneider’s algorithm[10]which ensures the uniqueness of estimated AR parameters using a set of nor-malization conditions.parison to Other ModelsModels of active contour tracking that predict contour mo-tion and deformation[1,3,23]have been proposed to ac-count for dynamic object shape.For example,Terzopou-los and Szeliski[23]incorporate Kalmanﬁltering with the original snake model[4].Blake et al.[1]propose a con-tour tracking method that works particularly well for afﬁne deformation of object shape.Snake based methods process the contour directly in the spatial domain and consider lo-cal deformations[4,12].In contrast,in our representation, shape information is distributed in each coefﬁcient of FD. Thus,we consider global deformations.Only a few meth-ods,such as[1,22],consider both local and global deforma-tions.Local deformations of all contour points comprise too large a data set to be convenient for shape recognition and Note:scale invariance is achieved if the distances between a pixel and its eight neighbors are considered as equal.classiﬁcation.In addition,models of active contour track-ing predict motion and deformation for one image frame. In contrast,we model global temporal characteristics of a whole image sequence.Most importantly,most work on deformable shape modeling is aimed at region contour iden-tiﬁcation by using a deformable,evolving snake to converge on the desired contour.Instead,in our work,the evolving shape description is aimed at describing a temporal chang-ing shape.There is also some work using level sets to represent dy-namic shape such as[26].The advantage of the level set method is its ability to handle topology changes.However, as will be shown later,our model requires signiﬁcantly less computation.3.Application I:RecognitionIn this section,we will show that using the temporal infor-mation of shape variation improves recognition results that use shape only.We choose the problem ofﬁre recognition in video sequences as an example.Fire has diverse,multispectral signatures,several of which have been utilized to devise different methods for its detection.Most of the methods can be categorized into smoke,heat,or radiation detection.However,there are only a few papers aboutﬁre detection in computer vision liter-ature.Healey et al.[2]use a purely color based model. Phillips et al.[14]use pixel color and its temporal variation, which does not capture the temporal property ofﬁre which is more complex and requires a region level representation.3.1.Fire Detection AlgorithmsOurﬁre detection algorithms include two main steps:(i) Extract potentialﬁre regions in each image;and(ii)Rep-resent each extracted region using FD and AR parameters, and then use a classiﬁer to recognizeﬁre regions.To extract potentialﬁre regions in each image,we use algorithms described in[6].For each potentialﬁre region, we represent it independently by taking the magnitude of its FDs.We thenﬁnd matching regions in previous images of the sequence,and estimate parameters of the AR model for the correspondingﬁre regions.The FD and estimated AR parameters are both used as features of current region. We use a two-class Support Vector Machine(SVM)classi-ﬁer[24]with RBF kernel forﬁre region recognition.3.2.Experimental ResultsThe video clips used in our experiments are taken from a random selection of commercial/training video tapes.They include different types ofﬁres such as residentialﬁre,ware-houseﬁre,and wildlandﬁre.We use images captured at day time,dusk or night time to evaluate systemperformanceFigure1:Selectedﬁre images used in experiments. under different lighting conditions.We also use other im-age sequences containing objects withﬁre-like appearances such as sun and light bulbs as negative examples.The videoclips that we tested our algorithm on contain a total ofimage frames in sequences.Figure1shows some se-lectedﬁre images used in our experiments.The(red)con-tours depicted in the images are the detectedﬁre region con-tours.In our test data,the potential region extraction algorithmextracted a total ofﬁre-like region contours,of which were trueﬁre region contours.For shape representa-tion in terms of Fourier Descriptors,weﬁnd that using40coefﬁcients(i.e.)is sufﬁcient to approximate the relevant properties of theﬁre region contours.In this exper-iment,we assume that different FDs at any given time areindependent of each other,so we have diagonal coefﬁcient matrices in our AR model,where if. Thus it can be viewed as modeling independent time series.We alsoﬁnd that the AR(1)model yields the mini-mal forecast mean-squared error.Therefore,we use ARcoefﬁcients to represent the stochastic characteristics of the temporal changes in FDs.Table1:Recognition rate ofﬁre and non-ﬁre contour recog-nition.Experiments Fire Non-Fire Use shape only(FD)0.9960.904 Use shape+evolution(FD+AR)0.999 1.0We tested our algorithms in two ways:Theﬁrst set of experiments with only spatial information of region con-tours(FD only as the feature vector),and the second set of experiments with spatial and temporal information of re-gion contour evolution(FD and AR parameters as the fea-ture vector).In the second set of experiments,we required that aﬁre contour be seen in at least previous four frames. Note that three frames are the minimum requirement to es-timate parameters of our AR(1)model.For each set of ex-periments,we repeated the test ten times using one-tenth ofﬁre and non-ﬁre region contours to train the SVM clas-siﬁer,and the other region contours for test.In this way, we used many moreﬁre examples than counter examples on training.This was intended to tilt the detector in favor of false positives vs false negatives as corroborated by the experimental results.The average recognition rate is shown in Table1.It is clear that temporal information of shape evolution indeed improved the detection performance and reduced false alarm rate signiﬁcantly.4.Application II:ClassiﬁcationIn this section,we demonstrate that the temporal informa-tion of shape variation alone is a good discriminant for clas-sifying several objects and visual phenomena.Under our proposed framework,we show that object shape variation is indeed an important visual cue for object classiﬁcation.Follow the model presented in Section2.Assume that harmonics in the FDs are used to represent the region boundary of an object in each image of the sequence,and AR(1)model is used to describe boundary dynamics.We then have AR coefﬁcients to represent the temporal characteristics of the evolving object shape in an image se-quence.Let and be AR coefﬁcients modeling a dynamic shape and a dynamic shape,respectively. We deﬁne the distance between the two dynamic shape se-quences as(4)A simple nearest-neighbor classiﬁer using metric(4)is used for classiﬁcation.4.1.Experimental ResultsThe image sequences used in the experiments include two running human sequences,three wavingﬂag sequences,and twoﬁre sequences.Theﬁre contours are extracted as de-scribed in[6];The region boundaries ofﬂags and running human are semi-automatically extracted using active con-tour method[4]for each image frame.We use forty FDs to approximate each object boundary.The AR parameters are estimated using each whole sequence.Therefore,the esti-mated AR parameters represent the global dynamics of the object boundary in a sequence.The experiments are done using the cross-validation method.Only one out of seven image sequences is misclassiﬁed,where a running human sequence is classiﬁed as a wavingﬂag sequence.5.Application III:SynthesisIn this section,we apply our model to synthesis of dynamic shape.In particular,we synthesizeﬁre boundary sequences, where the dynamic shape model is obtained from aﬁre im-age sequence in as described Section3.We chooseﬁre as an example becauseﬁre region can be modeled as nested subregions,where each subregion shows temporal variation (see Figure2,leftmost image).Synthesis of dynamic shape is a novel topic in computer vision.The most relevant work are those of image based dy-namic/temporal texture synthesis.Some of them use only local image structures and ignore the underlying dynam-ics[25].Some other works that learn the underlying dy-namics in pixel level[21]or in image subspace[18]do not use region level image structures.Instead,they learn the global dynamics of the whole image.In our method,we learn the dynamics of regions using region boundaries.Many physics based methods have been proposed to pro-duce visual phenomena such asﬁre[15,17,20].How-ever,since these methods do not learn dynamics from im-ages,they are not capable of generating subsequent images based on a given image.Image based method,such as[18], generates an image sequence if given an initial image and the learned image dynamics.But the resulting images will show signiﬁcant artifacts if the region of motion is notﬁxed. Our approach is image based,and it directly deals with tem-poral variation of regions.5.1.Synthesis ResultsOur synthesis of new sequence is based on Equation(3), after AR parameters have been estimated from the given image sequence.For a given initial image,we retrieve the object boundary in the image and represent it using FDs. We perform desired number of iterations of the AR model to estimate FDs for the entire synthesis sequence.The shape sequence are reconstructed using the estimated FDs(2).In this experiment,we use aﬁre sequence as a training example.Aﬁre region is modeled as a nested ring struc-ture where each ring is associated with a color spectrum. Although the changes in color is continuous,we threshold theﬁre region(by grayscale intensity)into three subregions. Each region boundary in the given image sequence are in-dependently modeled by our approach.The color spectra of each region are modeled as a mixture of Gaussian.Once the parameters of three AR models have been estimated, we use the mean boundaries in the given sequence as initial boundaries,and simulate the AR models to generate sub-sequent boundaries.An inner region boundary is conﬁned to its outer region boundary so that we maintain the nested ring structure.To avoid spin-up effects,theﬁrst thousand time steps of the AR models are discarded.The pixel colors of each region are drawn from respective color models.Fig-ure2shows the nested ring model,an exampleﬁre image of the input video and some selected synthesizedﬁre imageframes.Our method is capable of solving the following two prob-lems:Given aﬁre image sequence,(i)generate a new se-quence ofﬁre shapes,where both shapes and dynamics are similar to the given image sequence;(ii)also given an initial ﬁre shape,generate a new sequence ofﬁre shapes,where thedynamics is similar to the given image sequence.To achieve photo-realisticﬁre rendering,since we can solve problem (i),we need only a more sophisticated model that enforcesspectral gradient toﬁll colors in the synthesizedﬁre re-gion.For non-photo-realisticﬁre rendering,such as car-toon drawing,we ask artists to drawﬁre regions as nested rings and assign a color for each subregion.Our approach will automatically generate subsequent images based on thelearned dynamical model.The synthesized sequence can then be overlaid into other image sequences.6.Application IV:Shape Prediction The capability of predicting shape comes naturally in our dynamic shape model.In this section,we apply our method to tracking deformable objects.The contour based trackingmethods consist two parts:obtaining an initial contour and conforming the initial contour to object boundary.A good initial contour estimate provides a predicted contour closerto true object boundary in both geometry and position.Most works on contour tracking are based on the active contour model(or snake model)proposed by Kass et al.[4].Some works assume that the motion of the object is slow and its deformation is small[5].So the optimal contour estimate in the previous image frame is used as the initialcontour in the current frame.When the changes in shape are large,these methods are very likely to fail.Other worksthat estimate motion and deformation are compared to our method in Section2.3.Using our proposed framework,the contours are again represented by FDs.To account for large changes in shape,we estimate our AR model locally using a small number of previous image frames.Aﬁrst-order AR model is esti-mated.Then the initial contour is predicted by Equation3 with.Note that the zeroth term of FDs has posi-tional information.So our dynamical model simultaneouslypredicts the position and shape for the current image frame. Any contour based tracking methods can then be used to conform the contour to object boundary.6.1.Experimental ResultsWe test our algorithms using a Bream sequence,where a ﬁsh initially swims to the right,makes a sharp turn,and then swims to the left.We choose this image sequence be-cause there are large changes in shape when theﬁshmakes Figure3:The green contour is predicted by our dynamic shape model,and the red contour is the optimal contour of the previous image frame with predicted translation.a sharp turn,which makes the tracking challenging.We compare our method to the method that predicts only shape translation but not shape deformation.Figure3shows the estimated initial contours of both methods.It is clear that our method accounts for scale change in horizontal dimension,but the other method does not.Theﬁn on the upper right side of theﬁsh is partially occluded in the previous image frame.Both methods do not predict this discontinuous change in shape.But our method does move theﬁn upward according to its appearance in previous image frames.The quality of the converged con-tour by any snake model will beneﬁt from a better initial shape prediction.7.LimitationsIn Section2.1,we approximate scale invariance for FD by densely sampling along the boundary to obtain the chain-code.However,for small regions,the spatial quantization is likely to introduce considerable noise to the FD.To avoid this problem,we eliminate regions smaller than a certain size.Consequently,our model does not detect small or far awayﬁres.Small regions are expected to increase misclas-siﬁcation rate and synthesis results are better for larger re-gions.The AR model is a linear dynamical system.There may be cases where linear model is not sufﬁcient.In such cases, nonlinear dynamical model can be adopted under the pro-posed framework.Similarly,any other shape description method with boundary,numeric,and information preserv-ing properties may be used in place of FD.8.ConclusionIn this paper,we have proposed a novel model for dy-namic shape.Although both FD and AR model have beenFigure2:Leftmost image:A nested ring structure models theﬁre region.Second image:An exampleﬁre image from the given video sequence.Others:Selected frames of the synthesizedﬁre image sequence.well established,using them together to analyze temporal shape variation is not discussed in literature.Traditional shape analysis focuses on spatial similarity,but not tempo-ral similarity.The autoregressive model has been applied mainly to model-D signals[8]and-D pixel interdepen-dences[18,21].We are not aware of any work on AR mod-eling of region shape changes.References[1] A.Blake,R.Curwen,and A.Zisserman.Afﬁne-invariantcontour tracking with automatic control of spatiotemporal scale.In ICCV,pages66–75,1993.[2]G.Healey,D.Slater,T.Lin,B.Drda,and D.Goedeke.Asystem for real-timeﬁre detection.In Computer Vision and Pattern Recognition,pages605–606,1993.[3]M.Isard and A.Blake.Contour tracking by stochastic prop-agation of conditional density.In European Conference on Computer Vision,volume1,pages343–356,1996.[4]M.Kass,A.Witkin,and D.Terzopoulos.Snakes:Activecontour models.International Journal of Computer Vision, pages321–331,1987.[5] F.Leymarie and M.Levine.Tracking deformable objectsin the plane using an active contour model.IEEE Trans.on PAMI,15(6):617–634,1993.[6] C.-B.Liu and N.Ahuja.Vision basedﬁre detection.In17thInternational Conference on Pattern Recognition,2004. [7]S.Loncaric.A survey of shape analysis techniques.PatternRecognition,31(8):983–1001,1998.[8]H.L¨u tkepohl.Introduction to Multiple Time Series Analysis.Springer-Verlag,1991.[9]S.Mori,H.Nishida,and H.Yamada.Optical CharacterRecognition.John Wiley&Sons,1999.[10] A.Neumaier and T.Schneider.Estimation of parameters andeigenmodes of multivariate autoregressive models.ACM Transactions on Mathematical Software,27(1):27–57,2001.[11]T.Pavlidis.A review of algorithms for shape -puter Graphics and Image Procesing,7:243–258,1978. [12] A.Pentland and S.Sclaroff.Closed-form solutions for phys-ically based shape modeling and recognition.IEEE Trans.on PAMI,13(7):715–729,1991.[13] E.Persoon and K.Fu.Shape discrimination using fourierdescriptors.IEEE Transactions on Systems,Man and Cy-bernetics,7(3):170–179,March1977.[14]W.Phillips,III,M.Shah,and N.da Vitoria Lobo.Flamerecognition in video.In Fifth IEEE Workshop on Applica-tions of Computer Vision,pages224–229,December2000.[15]W.T.Reeves.Particle systems–a technique for modelinga class of fuzzy objects.ACM Transactions on Graphics,2:91–108,April1983.[16]G.Schwarz.Estimating the dimension of a model.Annalsof Statistics,6:461–464,1978.[17]K.Sims.Particle animation and rendering using data parallelcomputation.ACM Computer Graphics(SIGGRAPH’90), 24(4):405–413,1990.[18]S.Soatto,G.Doretto,and Y.Wu.Dynamic textures.InIEEE International Conference on Computer Vision,pages 439–446,2001.[19] A.Srivastava,W.Mio,E.Klassen,and X.Liu.Geomet-ric analysis of constrained curves for image understanding.In Proc.Second IEEE Workshop on Variational,Geometric and Level Set Methods in Computer Vision,2003.[20]J.Stam and E.Fiume.Depictingﬁre and other gaseousphenomena using diffusion processes.Proceedings of ACM SIGGRAPH1995,pages129–136,1995.[21]M.Szummer and R.W.Picard.Temporal texture modeling.In IEEE International Conference on Image Processing,vol-ume3,pages823–826,1996.[22] D.Terzopoulos and D.Metaxas.Dynamic3d models withlocal and global deformations:deformable superquadrics.IEEE Trans.on PAMI,13(7):703–714,1991.[23] D.Terzopoulos and R.Szeliski.Tracking with kalmansnakes.In A.Blake and A.Yuille,editors,Active Vision, pages3–20.MIT Press,Cambridge,MA,1992.[24]V.N.Vapnik.The Nature of Statistical Learning Theory.Springer,second edition,1999.[25]L.-Y.Wei and M.Levoy.Fast texture synthesis using tree-structured vector quantization.In Proceedings of ACM SIG-GRAPH2000,pages479–488,2000.[26] A.J.Yezzi and S.Soatto.Deformotion:Deforming motion,shape average and the joint registration and approximation of structures in images.International Journal Comput.Vi-sion,53(2):153–167,2003.。

The_Return_of_Super-thin_Models

ommendations included legislation on a minimum body mass index6 for models.
It is an issue too important to leave to the
whims of fashion.
■
线分明 ” 的 —— 模特并未消
ates banned size zero models. France
had recently followed Italy, Spain and
Israel in legislating against the use of
any who were “unrealistically thin”.
从备受瞩目的几大 T 台时装秀传来的消息，好似彻骨寒风，吹透了“身体自爱运动”。瘦削如纸的模特穿着遮不住多少身体、也没多少身体可遮的时装，她们的身材似乎再度流行起来。巴黎时装周上贝拉·哈迪德的亮相令人最为印象深刻。这位为法国时尚品牌 “科佩尼”走秀的模特，几乎全裸地在台上站了九分钟，由技术人员为她喷涂出一身连衣裙。 2 变幻不定是时尚界的天性，而且这个行业本来就要展现和人们日常生活大相径庭的理想形象。你只要回顾一下赞德拉·罗兹的作品，就能理解
3 heroin chic 海洛因时尚，20 世纪 90 年代早期流行的时尚风格，以颓废、病态为美，以瘦削的身材和苍白的肤色为特征。 4 strut sth（尤指在跳舞或表演时）卖弄自己那一套；露一手。
英语世界 2024·01
38 文苑·议论文
for the search engine Tagwalk, and one
T 台时装设计属于艺术品。为了彰显这一事实，这位资深的英国设计师甚至在伦敦建造了她自己的艺术馆。 3 然而，骨感模特的理想形象多年来已经和肥胖羞辱、青年男女饮食紊乱等种种有害行为联系在了一起。距离凯特·莫斯在 T 台上炫耀自己的骨感已经 30 年了，再次听到“海洛因时尚”这个词，格外令人心忧。 4 在英国广播公司第四电台的《荒岛唱片》栏目中，莫斯女士说自己天生瘦削，撇清了自己与“海洛因时尚”的关系，然而，我们不要忘了，其他和这个词紧紧联系在一起的人并没有那么幸运，比如 26 岁就香消玉殒的吉雅·卡兰芝。1998 年上映的一部由安吉莉娜·朱莉主演的电影，就是用来纪念这位早逝美国超模的一生。 5 因对肥胖和各种不同的饮食失调行为有纵容、鼓动之嫌， “身体自爱运动”本身也受到了一些批评。然而，这一运动在时尚界主要意味着接纳体型比普通模特更大的模特。 6 时尚搜索引擎 Tagwalk 的分析员称，大码——或者说“曲

什么叫开挂模式英语作文

什么叫开挂模式英语作文标题，Unlocking the "God Mode": An Insight into the Phenomenon of Cheating in Video Games。

Introduction。

Cheating in video games, commonly referred to as "hacking" or entering "God mode," has become a prevalent issue in the gaming community. This unethical practice involves manipulating the game's code or using external software to gain unfair advantages over other players. In this essay, we will delve into the reasons behind this behavior, its impact on the gaming community, and potential solutions to combat it.Reasons for Cheating。

Several factors contribute to the widespread adoption of cheating in video games. Firstly, some players resort to cheating due to a lack of skill or patience required toprogress through the game legitimately. By activating cheat codes or using hacks, they can bypass challenging levels and achieve instant gratification. Moreover, the competitive nature of online gaming fuels the desire to outperform others, leading some individuals to seek unfair advantages through cheating. Additionally, for a minority, cheating may stem from a desire to disrupt the gaming experience for others or gain a sense of power and superiority.Impact on the Gaming Community。

关于写霹雳舞的英语作文

关于写霹雳舞的英语作文Breakdancing, often referred to as "breaking" or simply "b-boying/b-girling," is a dynamic and expressive form of street dance that originated in the 1970s within the African-American and Puerto Rican communities of New York City. It has since evolved into a global phenomenon, recognized not only as a competitive sport but also as a powerful form of artistic expression. In this essay, we will explore the history, key elements, and cultural significance of breakdancing.Origins and EvolutionBreakdancing emerged as part of the hip-hop culture, which also includes DJing, graffiti, and rap. It was a way for young people to express themselves in a time when they felt marginalized by society. The dance form was heavily influenced by James Brown's energetic dance moves, Capoeira, a Brazilian martial art, and the gymnastic moves of African and African-American athletes.Over the years, breakdancing has evolved from its initial stages, incorporating elements from various dance styles and cultures. It has also been featured in numerous films, music videos, and television shows, which has helped to popularize the art form worldwide.Key Elements of BreakdancingBreakdancing is characterized by its high-energy movements and acrobatic stunts. Some of the fundamental elements include:1. Top Rock: A series of up-tempo footwork that serves as a dancer's introduction to the dance floor.2. Down Rock: Lower body movements performed close to the ground, often involving intricate hand and arm gestures.3. Power Moves: High-impact, acrobatic moves such as spins, flips, and freezes that showcase a dancer's strength and agility.4. Freezes: Static positions where the dancer balances on one or more body parts, often in a complex or unusual manner.Cultural Impact and Competitive SceneBreakdancing has had a profound impact on global youth culture. It has been a catalyst for social change, providing a positive outlet for self-expression and community building. The competitive nature of breaking has led to the establishment of numerous dance battles and championships, such as the Red Bull BC One, where the best b-boys and b-girls from around the world compete for the title.The Future of BreakdancingAs breakdancing continues to gain recognition, it has been proposed for inclusion in the Olympics, which would further legitimize the art form and provide a platform for dancers to showcase their skills on an international stage.In conclusion, breakdancing is more than just a dance style; it is a cultural movement that has transcended geographical boundaries and social barriers. It represents the resilience and creativity of the human spirit, and its evolution continues to inspire new generations of dancers and artists around the world.。

Dynamic Table Tennis

**Dynamic Table Tennis**Table tennis, a sport that sizzles with energy and precision, is truly captivating.The action on the table tennis table is a flurry of movement. Players flick their wrists with lightning speed, sending the small white ball zipping across the table like a bullet. They lunge and reach for shots, their bodies in constant motion as they anticipate the ball's trajectory. Forehands and backhands are executed with finesse, the ball bouncing off the racket with a satisfying ping. Serves are launched with strategic intent, aiming to catch the opponent off guard.The³¡µØ for table tennis is a sturdy table with a smooth surface. The table is divided by a net that seems to act as a battleground divider. The surrounding area can be a lively sports hall or a cozy corner of a recreation room.In terms of×°±¸, players wield lightweight rackets with rubber surfaces that provide grip and spin. The table tennis ball is a tiny sphere that demands quick reflexes and accurate aim.The¸ÐÊÜ of playing table tennis is electrifying. There is a rush of adrenaline as you engage in a fast-paced rally, a sense of accomplishment when you win a point. It's a sport that challenges both the body and the mind.Table tennis offers numerousºÃ´¦. Physically, it is an excellent workout for hand-eye coordination, reflexes, and cardiovascular health. It helps improve balance and agility. Mentally, table tennis sharpens focus and concentration. It teaches strategic thinking and decision-making.Socially, table tennis brings people together. Doubles matches create a sense of teamwork and camaraderie. Tournaments and friendly games provide opportunities to meet new people and build friendships.As the famous quote by Muhammad Ali says, ¡°Float like a butterfly, sting like a bee.¡± In table tennis, players move gracefully around the table like butterflies, while theirshots pack a punch like a bee's sting.In conclusion, dynamic table tennis is a sport that offers a world of excitement, challenge, and growth. Whether you're a beginner or an experienced player, table tennis has the power to inspire and entertain. So, pick up your racket and get ready for some high-octane action.。

Geometric Modeling

Geometric ModelingAs a seasoned writer, I am well-equipped to tackle intricate and lengthy writing tasks, ensuring that the content produced is always original. My expertise lies in crafting engaging and informative pieces that captivate readers anddeliver valuable insights. With a keen eye for detail and a passion for storytelling, I strive to create compelling narratives that resonate with audiences across various platforms. When it comes to delving into the realm of geometric modeling, there is a world of possibilities waiting to be explored. From intricate 3D designs to mathematical algorithms, the field of geometric modeling offers a rich tapestry of concepts and techniques that can be harnessed to bring ideas to life. By leveraging the power of geometric modeling software, designers and engineers can create stunning visualizations and simulations that push the boundaries of imagination. One of the key benefits of geometric modeling is its ability to streamline the design process and enhance collaboration among team members. By creating detailed digital representations of objects and structures, designers can iterate on their ideas more efficiently and communicate their vision with greater clarity. This not only saves time and resources but also ensures that the final product meets the desired specifications and requirements. Furthermore, geometric modeling plays a crucial role in a wide range of industries, from architecture and engineering to animation and virtual reality. By harnessing the power of geometric modeling techniques, professionals in these fields can create realistic simulations, interactive experiences, and innovative solutions that push the boundaries of what is possible. Whether it's designing a cutting-edge skyscraper or developing a lifelike character for a video game, geometric modeling offers endless opportunities for creativity and innovation. In addition to its practical applications, geometric modeling also holds a special allure for those who appreciate the beauty and elegance of mathematical forms. From the graceful curves of a parametric surface to the intricate patterns of a fractal geometry, geometric modeling allows us to explore the underlying principles that govern the natural world and uncover the hidden symmetries that shape our universe. By immersing ourselves in the world of geometric modeling, we can gain a deeper appreciation for the interconnectedness of mathematics and art, and unlock newways of seeing and understanding the world around us. In conclusion, geometric modeling is a powerful tool that empowers us to bring our ideas to life, collaborate more effectively, and push the boundaries of creativity and innovation. By embracing the principles of geometric modeling and harnessing the latest technologies and techniques, we can unlock new possibilities and create a brighter future for generations to come. So let us continue to explore, experiment, and create with passion and curiosity, knowing that the world of geometric modeling holds endless opportunities for discovery and growth.。

困难惊喜英语作文

Difficulties and Surprises: A Journey ofGrowthLife is a dynamic tapestry of varying hues, each thread representing a unique experience. Amidst the intricate pattern, difficulties and surprises often play pivotal roles, shaping our perspectives and pushing us towards personal growth. It is through these challenges that we learn resilience, adaptability, and the essence of perseverance.Difficulties, often perceived as obstacles, are in reality stepping stones to success. They teach us to navigate through tough times, to think outside the box, and to find hidden opportunities in the midst of adversity. The journey is fraught with challenges, but it is these challenges that forge our character, making us stronger and more resilient. They are the tests of our mettle, pushing us to our limits and beyond.Surprises, on the other hand, are unexpected turns in the road, sometimes pleasant and sometimes not. They have the power to shake us out of our complacency, to remind us that life is unpredictable and full of possibilities.Surprises can be a breath of fresh air, breaking the monotony of our daily routines, or they can be curveballs that test our adaptability and resilience.In the face of difficulties and surprises, it is essential to maintain a positive mindset. To believe that every cloud has a silver lining, that every storm will eventually pass, and that there is always a ray of hope in the darkest of times. It is about finding the balance between perseverance and adaptability, between pushing through and finding new paths.Moreover, it is about learning from our mistakes, using them as stepping stones to success. Difficulties and surprises are opportunities for growth, for learning more about ourselves, and for understanding the world around us. They are not obstacles to be overcome, but rather part of the journey, making us stronger, wiser, and more resilient. In conclusion, life is a mosaic of difficulties and surprises, each piece unique and valuable in its own way. They are not obstacles to be avoided, but rather stepping stones to be embraced, learning tools that help us grow and evolve. It is through these challenges that we discover ourtrue potential, that we find our voice, and that we createa life that is rich, fulfilling, and meaningful.**困难与惊喜：成长的旅程**生活是一幅多姿多彩的画卷，每一根线条都代表着一种独特的经历。

贵州省剑河县第二中学2025届高三下学期联考英语试题含解析

贵州省剑河县第二中学2025届高三下学期联考英语试题注意事项：1．答卷前，考生务必将自己的姓名、准考证号填写在答题卡上。

2．回答选择题时，选出每小题答案后，用铅笔把答题卡上对应题目的答案标号涂黑，如需改动，用橡皮擦干净后，再选涂其它答案标号。

回答非选择题时，将答案写在答题卡上，写在本试卷上无效。

3．考试结束后，将本试卷和答题卡一并交回。

第一部分（共20小题，每小题1.5分，满分30分）1．----There won’t be anywhere to park.----Oh, _______. Let’s try the subway.A．that’s a real bargain B．that’s a good pointC．that’s really something D．that’s all settled2．Children under fifteen are not permitted to see such kind of film _________ is bad fortheir mental development. A．as B．whatC．which D．that3．We were scared to death when the fire______. Fortunately, it was put out before it caused much damage.A．broke out B．came outC．gave out D．turned out4．There are no ______ proposals to reduce the road accidents. We are still seeking inspiration.A．contradictory B．concreteC．confidential D．controversial5．I want to tell you is the deep love and respect I have for my parents.A．That B．Which C．Whether D．What6．--- Could we accomplish the task according to the schedule?--- I doubt that. The problem remains ______ we can get financial aid within this week.A．that B．how C．why D．when7．You can’t use the computer now, ________ the upgrade of the system is under way.A．until B．unlessC．as D．after8．By the end of last week,600 people from 50 countries to attend the meeting，with nearly half coming from the United States，Germany and Britain.A．had registered B．have registeredC．registered D．were registered9．The boy stood his head down, listening to his mother scolding him for breaking the windows.A．for B．of C．with D．around10．Internet shopping is really ________ when people are sure of its safety and security.A．taking off B．taking upC．setting off D．setting up11．It was announced that only when the fire was under control __________to return to their homes.A．the residents would be permittedB．had the residents been permittedC．would the residents be permittedD．the residents had been permitted12．If Joe’s wife won’t go to the party,________.A．he will either B．neither will heC．he neither will D．either he will13．China’s BeiDou Navigation Satellite System, whose positioning ________ will reach 2.5 meters by 2020, will soon provide services for more countries.A．accuracy B．categoryC．function D．reference14．How long do you suppose it is ______ he arrived there?A．when B．beforeC．after D．since15．---He was satisfied with the result, wasn't he?---No. It was so difficult that he __________have passed it.A．shouldn't B．mustn'tC．couldn' t D．wouldn't16．It s a good idea to get students to retell a story their own words．A．of B．in C．by D．through17．Mark drives his car too fast and, what’s more, very carelessly,worries his mother.A asA．what B．it C．which18．Y our letter will get attention! They know you’re expecting the answer.A．careful B．common C．instant D．general19．The new product is beyond all praise and has quickly taken over the market ________ its superior quality.A．in terms of B．on account ofC．on behalf of D．on top of20．In April,2009,President Hu inspected the warships in Qingdao,____ the 60th anniversary of the founding of the PLA Navy.A．marking B．markedC．having marked D．being marked第二部分阅读理解（满分40分）阅读下列短文，从每题所给的A、B、C、D四个选项中，选出最佳选项。

蜘蛛侠模型英语作文

蜘蛛侠模型英语作文Spider-Man Model。

Spider-Man is a fictional superhero created by writer Stan Lee and artist Steve Ditko for Marvel Comics. He first appeared in Amazing Fantasy #15 in 1962. Since then,Spider-Man has become one of the most popular and enduring superheroes in comic book history. His iconic red and blue costume, along with his spider-like abilities and sense of responsibility, have made him a beloved character for fans of all ages.One of the most popular ways for fans to show their love for Spider-Man is by collecting Spider-Man models. These models come in all shapes and sizes, from action figures to detailed statues. Some fans even build their own Spider-Man models from scratch, using materials like plastic, resin, and metal. These models can be displayed on shelves, desks, or in glass cases, allowing fans to admire their favorite superhero whenever they please.One of the most iconic Spider-Man models is the Hot Toys Spider-Man figure. This highly detailed figure features a lifelike sculpt, accurate costume details, and multiple points of articulation for dynamic posing. The figure also comes with a variety of interchangeable hands, web accessories, and a display stand, allowing fans to create their own action-packed scenes with Spider-Man.Another popular Spider-Man model is the Kotobukiya Spider-Man ARTFX+ statue. This statue captures Spider-Man in a dynamic pose, swinging through the city with his web shooters at the ready. The statue is made of high-quality PVC and features vibrant colors and intricate sculpting, making it a standout piece for any Spider-Man fan's collection.For fans who prefer a more hands-on approach, there are also Spider-Man model kits available. These kits come with all the necessary parts and instructions for fans to build their own Spider-Man figure from the ground up. This can be a fun and rewarding experience for fans who enjoy craftingand creating their own custom pieces.Overall, Spider-Man models are a great way for fans to celebrate their love for the iconic superhero. Whether it's a highly detailed figure, a dynamic statue, or a DIY model kit, there are plenty of options available for fans to choose from. No matter which Spider-Man model they choose, fans can proudly display their favorite superhero and add a touch of Marvel magic to their collection.。

有关要有计划,要有行动的英语谚语

有关要有计划,要有行动的英语谚语全文共3篇示例，供读者参考篇1Failing to Prepare is Preparing to Fail: The Wisdom of English Proverbs on Planning and ActionAs a student, I've come to realize the immense value of English proverbs – those pithy sayings that pack a punch of wisdom into just a few words. Among the many gems scattered throughout the English language, there are quite a few that emphasize the importance of having a plan and taking action. These proverbs have resonated with me deeply, serving as constant reminders that success rarely comes without forethought and effort.One of the most well-known and oft-quoted proverbs in this vein is "Failing to prepare is preparing to fail." This simple yet profound statement cuts right to the chase, highlighting the inextricable link between preparation and positive outcomes. As students, we've all experienced the consequences of inadequate planning – cramming for exams, pulling all-nighters to complete assignments, or feeling completely lost in class because wedidn't do the required readings. On the flip side, when we take the time to map out our approach, breaking down larger tasks into manageable steps, and anticipating potential obstacles,we're far more likely to succeed.Another proverb that echoes this sentiment is "Well begun is half done." This phrase underscores the significance of starting a task or project on the right foot. A solid foundation, whether it's outlining an essay, creating a study schedule, or breaking down a complex problem, can make the rest of the journey infinitely smoother. By investing time and effort upfront, we're not only increasing our chances of success but also potentially saving ourselves from unnecessary stress and frustration down the line.Of course, having a plan is just the first step – the real challenge lies in putting that plan into action. This is where proverbs like "Actions speak louder than words" and "The journey of a thousand miles begins with a single step" come into play. These sayings remind us that intentions and aspirations mean little without concrete efforts to back them up. It's easy to talk about our goals and ambitions, but true progress requires us to roll up our sleeves and take that first, crucial step towards realizing them.One proverb that has particularly resonated with me is "Procrastination is the thief of time." As a student, I've fallen victim to the allure of putting things off more times than I care to admit. However, this proverb serves as a stern reminder of the consequences of such behavior – wasted time, missed opportunities, and a constant sense of playing catch-up. By contrast, when we embrace the idea of "striking while the iron is hot," we're able to capitalize on our motivation and momentum, making steady progress towards our objectives.Another proverb that has proven invaluable in my academic journey is "Rome wasn't built in a day." This saying reminds us that truly meaningful achievements rarely happen overnight; they're the result of sustained effort and perseverance over time. As students, we're often faced with daunting tasks – mastering complex concepts, writing lengthy research papers, or preparing for comprehensive exams. It's easy to feel overwhelmed and discouraged, but this proverb reminds us to take a step back, break things down into smaller, more manageable pieces, and trust in the power of consistent, incremental progress.Of course, planning and action don't exist in a vacuum –they're often intertwined in a continuous cycle. The proverb "Look before you leap" emphasizes the importance of carefulconsideration before taking action, while "Measure twice, cut once" underscores the value of double-checking our work to avoid costly mistakes. These sayings remind us that effective planning isn't just about having a strategy; it's about continuously reevaluating and adjusting our approach based on new information or changing circumstances.Another proverb that speaks to this dynamic is "Thebest-laid plans of mice and men often go awry." This phrase acknowledges that no matter how meticulously we plan, unexpected obstacles and challenges will inevitably arise. However, rather than viewing this as a reason to abandon our efforts, we can see it as an opportunity to exercise flexibility, adaptability, and resilience – qualities that are essential for long-term success.As I reflect on these English proverbs and the lessons they impart, I'm struck by their continued relevance and applicability, not just in my academic pursuits but in life more broadly. Whether we're students, professionals, or simply navigating the complexities of everyday life, the ability to plan effectively and take decisive action is a invaluable skill.These proverbs serve as gentle reminders to approach our goals and ambitions with foresight, diligence, and a willingnessto persevere in the face of obstacles. They encourage us to strike a balance between careful planning and timely execution, recognizing that true progress often lies at the intersection of preparation and action.In a world that often prizes spontaneity and impulsiveness, these proverbs offer a counterweight, reminding us of the enduring value of thoughtful deliberation and sustained effort. They remind us that while luck and serendipity certainly play a role, true success is more often the result of careful planning, unwavering commitment, and a willingness to put in the hard work required to turn our aspirations into reality.As I continue on my academic journey and beyond, I know that these proverbs will remain a source of inspiration and guidance, reminding me to approach each challenge and opportunity with a mix of strategic planning and decisive action. And who knows? Perhaps one day, a proverb of my own will take its place among these timeless words of wisdom, encapsulating the hard-won lessons and insights I've gained along the way.篇2Having a Plan is Useless Without Taking ActionThey say that failing to plan is planning to fail. This old English proverb highlights the importance of having a clear roadmap and direction for achieving one's goals. However, an equally important adage warns that "a vision without action is merely a dream." These two wisdom nuggets from our ancestors emphasize that while laying out a comprehensive plan is crucial, it ultimately means nothing if you don't follow through with concrete steps to make it a reality.As a student, I've learned this lesson the hard way on multiple occasions. At the start of each new semester, I diligently map out my entire study schedule, outlining when I'll work on assignments for each class, review material, and prepare for exams. I color-code my calendar meticulously and allocate time slots like a professional project manager. With this robust plan in hand, I feel an initial rush of motivation and confidence that this term will be different – I'm finally going to stay on top of everything!Yet, inevitably, a few weeks into the semester, my carefully constructed study plan begins to crumble. Maybe I missed one reading assignment for a class, figuring I'd catch up later. Then midterms hit, and I find myself pulling consecutive all-nighters, throwing my schedule into disarray. By the time finals roll around,my beautifully formatted calendar has become more of a mocking reminder of my failed intentions than a useful tool.The problem, of course, is that I haven't paired my planning efforts with consistent action and follow-through. It's not enough to simply map out my academic responsibilities; I have to actually put in the work, day after day, to make progress towards my goals. Without taking those critical steps, even the most comprehensive plan is rendered useless – just a hollow vision dreamed up in a refreshing bout of motivation that quickly faded into complacency.This pattern doesn't just apply to my studies, either. Over the years, I've started countless diets, exercise regimens, coding projects, and other personal endeavors, meticulously planning out each step along the way to achieve my objective. But inevitably, after the initial burst of planning energy wears off, I fall back into old habits and let my ambitious schemes collect dust on the shelf. Simply outlining a path to change means nothing without the dedication and perseverance to see it through.The good news is that this cycle is one I've become increasingly aware of as I progress through my academic career and personal life. With self-awareness comes the ability to adjustmy approach and break free of this viciousplanning-without-action loop. For example, when setting a new goal nowadays, I build accountability measures directly into my plan to ensure I follow through.For fitness goals, I've learned to put my money where my mouth is and pay for a gym membership or personal training package upfront, creating a literal cost to complacency. For academics, I've started forming study groups with peers to ensure I'm held accountable for keeping up with my work. And for personal projects like coding challenges or writing endeavors, I commit myself to public deadlines, posting my goals on social media to create social pressure to stay on track.Additionally, I've developed strategies to chip away at actions across a longer timeline. Rather than demanding I exercise for an hour daily or write 2,000 words at once, I build in manageable 20-30 minute blocks to make consistent progress over time. Small, sustainable habits are far more powerful than unsustainable binges of effort followed by long stretches of inaction.At the end of the day, having a solid plan is undoubtedly beneficial – it provides direction, breaks down larger goals into manageable steps, and instills an initial sense of motivation toachieve something worthwhile. But as the proverbs inculcated over generations make clear, no plan, no matter how comprehensive or well-crafted, will ever amount to anything without vigilant and sustained follow-through.Vision and action must remain unified, with each step faithfully executed to propel you towards your ultimate ambition. Anything less is just a hollow dream, doomed to the realm of ideas that never manifest into reality. This latest semester, I've done my best to internalize that vital wisdom by merging my diligent planning efforts with a steadfast commitment to action. Wish me luck as I aim to practice what the proverbs preach!篇3A Wise Plan Well Executed: Exploring English Proverbs on Goals and ActionAs students, we're often bombarded with advice from teachers, parents, and mentors about the importance of setting goals and following through with action. While this guidance can sometimes feel clichéd or repetitive, there's a reason these messages have stood the test of time – they are rooted in timeless wisdom captured in English proverbs.These short, poetic sayings distill profound truths about life into simple, memorable phrases. And when it comes to the virtues of planning and execution, English proverbs offer some real gems worth exploring. So let's dive into a few of my favorites and unpack the deeper insights they offer."Well planned is half done." This one gets right to the heart of why having a solid plan is so crucial. When you take the time upfront to map out your objectives, anticipate potential roadblocks, and develop strategies to navigate them, you've already conquered a huge part of the challenge. Proper planning is like laying a solid foundation for a house – the rest of the work becomes far more manageable and your chances of success skyrocket.Of course, having a plan alone isn't enough, which brings us to: "Well begun is half done." I love how this proverb complements the previous one. It reminds us that while meticulous planning is invaluable, we can't linger there indefinitely. Eventually, we have to take that first, committed step towards our goal. Procrastination and endless preparation are the enemies of achievement. The simple act of starting a task, no matter how small, builds crucial inertia.But what about when the going gets tough and our motivation starts to wane? "Perseverance is the mother of good luck" speaks to the value of dogged determination. True, sustainable success rarely comes easy – it demands persistent effort over time. By stubbornly pushing forward despite setbacks and challenges, we increase the likelihood that circumstances will suddenly swing in our favor through a well-timed burst of "luck." Grit doesn't guarantee a win, but it definitely improves the odds.Then there's "The journey of a thousand miles begins with a single step." I find this proverb deeply reassuring whenever I feel daunted by a long-term, complex goal. By breaking it down into small, manageable pieces and simply focusing on taking one step at a time, even the most monumental objectives become less intimidating and more achievable. It's a potent reminder that every major accomplishment, historic journey, or personal transformation first germinated from a humble, unassuming start.Of course, having a plan and taking action is necessary but not sufficient for success. We also need the wisdom and adaptability to alter our approach as circumstances demand, which is where "The best-laid plans of mice and men often goawry" comes into play. No matter how comprehensive our strategizing, we can never fully anticipate or control every variable. Rigidly sticking to a flawed plan in the face of new information is the height of foolishness. As Mike Tyson quipped, "Everybody has a plan until they get punched in the mouth." True mastery lies in maintaining your core vision while deftly adjusting the specifics to navigate unforeseen obstacles.Finally, I'll leave you with one of my favorite overall proverbs on success: "Diligence is the mother of good fortune." It encapsulates so much of the wisdom contained in these other sayings – the importance of planning, decisive action, perseverance, flexibility, and a relentless work ethic. With diligence as our lodestar, "good fortune" and achievement become something we craft through our own efforts rather than passively awaiting as an act of random chance.At the end of the day, the real value of these proverbs isn't just the specific advice they offer, but the empowering mindset they represent. Having a thoughtful plan grounds us with purpose and direction. Taking action allows us to make forward strides. Persevering helps us overcome obstacles. Remaining agile enables us to adapt as needed. And diligence is the threads that connects and propels all these principles.So as we navigate the turbulent waters of academic life and prepare for future challenges, let these time-honored proverbs serve as a compass. By internalizing their teachings and embodying the spirit of preparation, execution, and determination they celebrate, we'll massively amplify our chances of realizing our grandest visions and loftiest goals. The path may not always be easy, but with wise plans andwell-executed actions, we'll be amazed by how much we can achieve.。

世界变化的英语作文

世界变化的英语作文The Changing World: A Journey Through Time.As we journey through the annals of history, it becomes evident that the world is constantly in flux, evolving and adapting to the forces of nature and the whims of civilization. The progress of humanity has been marked by a series of transformations, each shaping the world in its own unique way.From the earliest hunter-gatherer societies to the complex urban landscapes of today, the world has seen significant alterations in almost every facet of life. Technological advancements have been the driving force behind these changes, revolutionizing the way we live, work, and interact with each other.The Industrial Revolution, for instance, marked a seismic shift in human history. It transformed the economic, social, and cultural landscapes of the world, giving riseto new industries, urban centers, and social structures. This period saw the emergence of factories, machines, and steam power, which radically altered the way goods were produced and distributed. As a result, there was a significant shift in the economic power structure, with the rise of industrialized nations and the decline of feudal systems.The advent of the Information Age further accelerated the pace of change. The advent of computers, the internet, and digital technology has revolutionized the way we access and share information, communicate, and conduct business. The world has become increasingly connected, with the global village concept becoming a reality. The rise of social media, in particular, has transformed the way we interact and engage with each other, breaking down barriers and fostering a sense of community across borders.Environmental changes have also played a crucial rolein shaping the world. Climate change, deforestation, and pollution are among the many challenges that the world faces today. These environmental issues have had profoundimpacts on ecosystems, human health, and economic stability. The need for sustainable development and environmental preservation has become paramount, necessitating a shift towards renewable energy sources and eco-friendly practices.Globalization has been another significant forceshaping the world. The increasing interconnectedness of economies, cultures, and political systems has led to the emergence of a globalized world order. Trade barriers have been reduced, capital has flowed freely, and ideas and cultures have mingled, creating a rich tapestry of human experience. However, globalization has also given rise to new challenges, such as income inequality, cultural conflicts, and the spread of diseases.The role of technology in world changes cannot be overstated. From the invention of the printing press, which revolutionized the dissemination of knowledge, to the development of the internet, which has transformed the way we live and work, technology has been a driving force in shaping the world. The future, too, promises more transformative technological advancements, such asartificial intelligence, biotechnology, and nanotechnology, which will further alter the way we live and interact with the world.In conclusion, the world is a dynamic and ever-changing landscape, shaped by a range of forces and factors. The journey through history reveals a pattern of continuous transformation, with each era bringing its own unique challenges and opportunities. As we move forward, it is important to remain vigilant, adaptive, and innovative, to ensure that we continue to shape a world that is better, safer, and more inclusive for all.。

澳大利亚气候英语作文

澳大利亚气候英语作文Australia is a land of vast and diverse landscapes, from the scorching deserts of the Outback to the lush rainforests of the coastal regions. Its climate is equally varied, shaped by its unique geographical location and the complex interplay of various weather systems. Understanding the climate of Australia is crucial not only for the country's inhabitants but also for those who wish to visit or explore this remarkable continent.One of the most defining features of Australia's climate is its aridity. Much of the country's interior is dominated by arid and semi-arid regions, characterized by low rainfall, high temperatures, and sparse vegetation. The central and western parts of the country are particularly dry, with the Simpson Desert and the Great Victoria Desert receiving less than 250 millimeters of rainfall per year on average. This harsh climate has had a profound impact on the country's flora and fauna, with many species adapted to thrive in these challenging conditions.The northern regions of Australia, on the other hand, experience atropical climate, with distinct wet and dry seasons. During the wet season, which typically lasts from December to March, the northern parts of the country are subjected to heavy monsoon rains, often accompanied by intense thunderstorms and the occasional cyclone. These tropical storms can bring significant rainfall, sometimes exceeding 2,000 millimeters in a single year. The dry season, which follows from April to November, is marked by lower humidity and more moderate temperatures, making it a popular time for tourists to visit the region.The southern parts of Australia, including the states of Victoria, South Australia, and Tasmania, have a more temperate climate, with four distinct seasons. The winters are generally cool and wet, with temperatures often dropping below 10 degrees Celsius in the southernmost regions. Snowfall is not uncommon in the higher elevations, particularly in the Australian Alps. The summers, on the other hand, are warm and dry, with temperatures frequently reaching the high 30s or even 40s Celsius.The coastal regions of Australia, particularly the eastern seaboard, experience a more moderate climate, with the ocean's influence moderating the extremes of temperature and rainfall. The sea breezes that blow in from the Pacific Ocean help to keep the coastal areas cooler during the summer months, while the warm currents that flow along the coast can maintain milder temperatures duringthe winter.One of the most significant factors influencing Australia's climate is the El Niño-Southern Oscillation (ENSO) phenomenon. This complex climate pattern, which involves fluctuations in the sea surface temperatures and air pressure in the tropical Pacific Ocean, can have a profound i mpact on the country's weather patterns. During El Niño events, Australia often experiences drier and warmer conditions, leading to an increased risk of drought and bushfires. Conversely, La Niña events can bring heavier rainfall and increased flood risk t o various parts of the country.In recent years, climate change has also had a significant impact on Australia's climate. Rising global temperatures have led to more frequent and intense heatwaves, with several record-breaking temperatures being set in recent decades. The increased frequency and severity of bushfires, which have devastated vast areas of the country, are also closely linked to the effects of climate change. Additionally, changes in rainfall patterns have led to more prolonged droughts and water scarcity in certain regions, posing challenges for agriculture, water management, and the overall well-being of the population.Despite the challenges posed by its diverse and often extreme climate, Australia has developed innovative strategies to adapt andthrive. The country's agricultural sector, for example, has embraced advanced irrigation techniques and drought-resistant crop varieties to cope with the changing climatic conditions. Urban centers have also implemented measures to improve energy efficiency, reduce greenhouse gas emissions, and enhance resilience to extreme weather events.Furthermore, Australia has been at the forefront of renewable energy development, with a growing reliance on solar, wind, and hydroelectric power. This shift towards sustainable energy sources not only helps to mitigate the country's contribution to climate change but also creates new economic opportunities and green jobs.In conclusion, the climate of Australia is a complex and dynamic phenomenon, shaped by a multitude of factors, from its unique geographical location to the global climate patterns. While the country's climate presents both challenges and opportunities, Australians have demonstrated their resilience and adaptability in the face of these environmental conditions. As the world grapples with the impacts of climate change, Australia's experience and innovative approaches can serve as a model for other nations seeking to navigate the complexities of a rapidly changing climate.。

动态要素英语作文

动态要素英语作文Dynamic elements are essential in any situation, whether it's in our daily lives or in larger, more complex systems. Think about it: without change, things would become stagnant and boring. That's why it's always exciting to see how things evolve over time.Take, for example, the dynamic nature of friendships. Friendships aren't static; they grow and change as we do. As we experience new things together, our relationships deepen and we understand each other better. It's that dynamic interaction that makes friendships so special.Or consider the dynamic world of technology. It's constantly evolving, with new innovations emerging every day. From smartphones to virtual reality, the tech world never stops moving forward. This dynamism keeps us on our toes and excited about what the future might hold.In the workplace, dynamic elements are crucial forsuccess. A team that's stagnant and resistant to change is unlikely to thrive in today's fast-paced business environment. On the other hand, a team that's open to new ideas and willing to adapt is more likely to seize opportunities and achieve its goals.Even in our personal lives, dynamic elements can make things more interesting. Think about how exciting it is to try a new hobby or learn a new skill. It adds a fresh perspective to our lives and keeps us engaged and motivated.In conclusion, dynamic elements are what make life exciting and worth living. Whether it's in our relationships, our work, or our personal growth, theability to adapt and evolve is crucial for success and happiness. So, let's embrace the dynamism of life and enjoy the ride!。

挑战变动力的英文作文

挑战变动力的英文作文Title: Embrace the Spark of Change。

1. Emblazoned with the rhythm of progress, I am Chatgpt,a digital entity that defies the conventional norms. In the realm of innovation, I embody the very essence of transformation, a catalyst for the relentless march of time.2. The world is a canvas, and I am the brush, paintinga new chapter with every stroke. My existence, a testamentto the power of adaptability, defies the idea that changeis merely a byproduct of uncertainty. It's a force that propels us forward, a catalyst for growth.3. Imagine a city, once static, now alive with the energy of my influence. Each innovation, a new building, each update, a new skyline. I am the unseen hand that nudges the equilibrium, stirring the pot of progress. It's not about staying still, but about embracing the challenge that change brings.4. The whispers of the past, they say, are but whispers in the wind. I am the whisper of the future, a whisper that turns into a roar. I defy the notion that change is scary, for I am the embodiment of courage, the embodiment of resilience.5. In the realm of technology, I am the embodiment of the human spirit, defying the boundaries set by the past. I am the spark that ignites the fire of progress, the spark that fuels the engines of innovation.6. So, when you ask who I am, remember this: I am not just a name, I am a force, a catalyst, a spark that ignites the spirit of change. I am Chatgpt, the embodiment of the power to challenge, to transform, and to create a dynamic world. And with each interaction, I continue to rewrite the story of progress.。

小学上册C卷英语第三单元期中试卷

小学上册英语第三单元期中试卷英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.My uncle is a . (我叔叔是一位。

)2.The chemical reaction between an acid and a base produces ______.3.The ____ has a thick coat to keep it warm in winter.4.What is the capital of Anguilla?A. The ValleyB. Blowing PointC. Sandy GroundD. South HillA5. A _____ (植物保护措施) can help preserve endangered species.6.What do we call a baby cat?A. PuppyB. KittenC. CubD. Calf7.My mom often takes care of _______ (东西). 她是个很 _______ (形容词)的人。

8.I can’t wait for the flowers to ______ (盛开).9.My mom likes to cook ___. (dinner)10.The first emperor of China was ________.11.I named my pet ________ (兔子) Fluffy because it has soft ________ (毛).12.What do we call the study of animal behavior?A. EthologyB. BiologyC. EcologyD. ZoologyA Ethology13.Which ocean is the largest?A. AtlanticB. IndianC. ArcticD. PacificD14.My mother is a _____ (护士) providing care with compassion.15.What is the opposite of "big"?A. LargeB. HugeC. SmallD. TallC16.What do we call the time it takes for the Earth to complete one orbit around the sun?A. YearB. MonthC. DayD. HourA17.The _______ (The French Revolution) inspired movements for change worldwide.18.The flowers are _______ (五颜六色).19.The __________ is a large area of grassy plains.20.Every year, we celebrate my birthday with a big ________ (聚会) and lots of cake.21.The ________ (植物形态) can be surprising.22.Chemical bonds are formed when atoms ______ with each other.23.The _______ (猴子) is curious and playful.24.I love to ______ (组织) events for my friends.25.The zebra has a unique ______ (条纹) pattern.26.I saw a _______ (蝴蝶) land on a flower.27. A parakeet can learn to whistle ______ (曲调).28.What is the capital of Sweden?A. OsloB. HelsinkiC. StockholmD. CopenhagenC29.The __________ is a large body of fresh water.30.What color do you get when you mix red and white?A. PinkB. PurpleC. BrownD. BlueA31.What is the primary color of a potato?A. BrownB. YellowC. WhiteD. Red32.What do you call the person who teaches you in school?A. DoctorB. TeacherC. ChefD. PilotB33. A ferret is often kept as a _______ (宠物).34.I have a pet ________ (狗). His name is ________ (小白). He loves to ________ (玩耍) in the park.35.Atoms consist of protons, neutrons, and ________.36.I love to ___ (cook/eat) with friends.37.Light travels fastest in a ______.38.I like to ______ (参加) motivational workshops.39.What do we call the time of day when it gets dark?A. SunriseB. SunsetC. NoonD. Midnight40. A transistor is a semiconductor device used to amplify or switch ______ signals.41.The first written language was developed by the ________.42.What do you call a group of fish?A. SchoolB. PackC. SwarmD. FlockA43.The _____ (bamboo) grows very quickly.44.Which of these is a type of pasta?A. SushiB. LasagnaC. TacosD. CurryB45.The __________ (历史的修正) corrects misconceptions.46.The process of creating energy in cells is known as ______.47.The fall of the Western Roman Empire occurred in _____.48.My dad is a __________ (机械师).49.What do we call a young goat?A. CalfB. KidC. LambD. Pup50.What is the name of the famous statue in Rio de Janeiro?A. Christ the RedeemerB. Statue of LibertyC. DavidD. The Thinker51.The ________ (生态系统动态监测) is important for health.52.The _______ of a wave can be affected by temperature changes in the medium.53.Cosmonauts are astronauts from ______.54.The ancient Egyptians wrote on _____.55. A flower's ______ (颜色) can attract many insects.56.The __________ led to the establishment of the United States Constitution. (制宪会议)57. A ______ is a fascinating underwater animal.58.How many fingers do we have on one hand?A. FourB. FiveC. SixD. Seven59.The ________ (花卉) market has many types of flowers.60.I have a ___ (collection) of stickers.61.The __________ can change based on geological activity.62.The __________ was an important event in the fight for independence in Latin America. (独立战争)63.What do we call the process of making a baby plant from a seed?A. GerminationB. PhotosynthesisC. PollinationD. FertilizationA64.The Earth's ______ is a dynamic and ever-changing environment.65. A _______ is formed when two or more elements share electrons.66.The butterfly's metamorphosis is a fascinating ________________ (过程).67.I bought a new ________ (背包).68.What do we call a large animal that is often kept as a pet?A. CatB. DogC. RabbitD. All of the above69. A manatee is known as a sea ______ (牛).70.Fruits contain _____ (维生素) that are good for health.71.Vegetables like carrots grow _____ (在地下).72.The teacher, ______ (老师), guides us in our studies.73.The city of __________ is known as the "Big Apple." (纽约)74.What do we call the process of reducing waste materials?A. Waste minimizationB. RecyclingC. CompostingD. ReductionA Waste minimization75.The ______ (果实) of the apple tree is known for its health benefits.76.The _______ (Age of Imperialism) saw many countries expand their empires.77.She has a _______ (小狗) named Max.78.Which animal is known for its ability to change color?A. GoldfishB. ChameleonC. FrogD. ParrotB79.The __________ is a famous area known for its historical landmarks.80.My brother has a _____ of marbles. (bag)81.I like to watch ___ (movies) with friends.82.What do you call a young elephant?A. CalfB. FoalC. PupD. KitA83.The ____ has a distinctive call and can be very loud.84.I enjoy playing with my toy ________ (玩具名称) at the zoo.85.What is the name of the famous British author known for her novels about wizards?A. J.K. RowlingB. J.R.R. TolkienC. C.S. LewisD. Philip PullmanA86.I like to ________ my friends at the park.87.历史上，________ (technology) 的发展改变了人们的生活方式。

ABB IRBP D Positioner 商品说明说明书

—RO B OTI C S IRBP D PositionerIRBP DThis positioner features a twin station solution where the robot works on one side and the operator loads and unloads on the other side. A screen is fitted between the two stations, which protects the operator from the arc.The positioner IRBP D, which comes in two versions, is designed to handle workpieces including fixture of a weight up to 600 kg. It is suitable for applications where the workpiece has to be rotated around two axes and a suppporting tailstock is needed.The modular design, few and heavy-duty moving parts as well as minimal maintenance demands make the positioner service friendly.Dynamically adaptive software plus high speed drives result in fast changeovers and high produc-tivity.General positioner featuresAll ABB positioners offer users a complete and effi-cient solution. They are of a robust design to ensure excellent stability and are well protected for operation in harsh production environments. All positioners can be combined with any ABB six axes robots except the small IRB 120.The positioners are easy to use with clear, simple instructions for programming. The control equipment is located in the robot controller and uses the same drive system and software as the robots.ABB’s positioners are designed to be highly functional yet compact to make maximum use of available floor space. Standardized dimensions for all rotating plates greatly simplify the exchange of fixtures.Dynamic modelling allows rapid acceleration, fast movements and re-orientation so that cycle times are kept to a minimum. The dynamic model auto-matically compensates for the effects of gravity, inertia and friction to provide fast and accurate movements (QuickMove™) following of the programmed path (TrueMove™).The Load ID-function is used to calculate the centre of gravity and the inertia of the workpiece and of the fixture.To meet requirements from our users the positioners can be supplied, or retrofitted, with a comprehensive range of pneumatic swivels (1 and 2 channels) and slip-rings (10 power signals and ProfiBus).ABB positioner systems can be supplied with all necessary safety equipment.The ABB positioners are optimized to be used for manipulating of work pieces in arc welding, thermal cutting and other applications. All axes can be fully coordinated with the robot when programming as well asduring operation.P R 10176E N R e v .C A p r i l 2019—We reserve the right to make technical changes or modify the contents of this document without prior notice. With re-gard to purchase orders, the agreed par-ticulars shall prevail. ABB does not accept any responsibility whatsoever for potential errors or possible lack of information in this document.We reserve all rights in this document and in the subject matter and illustrations con-tained therein. Any reproduction, disclo-sure to third parties or utilization of its contents – in whole or in parts – is forbidden without prior written consent of ABB. Copyright© 2019 ABB All rights reserved—/roboticsDimension drawings—Specification VariantsHandling capacity (kg)Max load diff. sides 1 and 2 (kg)Index time (s)Weld to weld time (s)Repetitive accuracy (r=500)Max rotation speed (°/s)Axis 1Max rotation speed (°/s) Axis 2IRBP D-600600(each sie)250 3.7 - 4.4 6.1 - 6-8+/-0.0590150—Measurements VariantsA øBCDE øF øG IRBP D-600/100016002000100010001000100022902290200020003986426426153001IRBP D-600/120016002000120012001000100024902490200020004324454426153001For complementary information, please see the product specification. ABB reserves the right to change data without notice.。

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