BRST superspace and auxiliary fields for N=1 supersymmetric Yang-Mills theory
Simultaneous localization and mapping (SLAM) part II
S
long excursion, the so-called loop-closure problem. The data association section surveys current data association methods used in SLAM. These include batch-validation methods that exploit constraints inherent in the SLAM formulation, appearance-based methods, and multihypothesis techniques. The third development discussed in this tutorial is the trend towards richer appearance-based models of landmarks and maps. While initially motivated by problems in data association and loop closure, these methods have resulted in qualitatively different methods of describing the SLAM problem, focusing on trajectory estimation rather than landmark estimation. The environment representation section surveys current developments in this area along a number of lines, including delayed mapping, the use of nongeometric landmarks, and trajectory estimation methods. SLAM methods have now reached a state of considerable maturity. Future challenges will center on methods enabling large-scale implementations in increasingly unstructured environments and especially in situations where GPS-like solutions are unavailable or unreliable: in urban canyons, under foliage, under water, or on remote planets.
挑战新境界的英语作文
Pushing the Boundaries:An English Composition on New FrontiersIn the everevolving landscape of human endeavor,the quest for new frontiers has always been a driving force.The English language,with its rich vocabulary and expressive power,provides an ideal medium for exploring and articulating the challenges and triumphs of this pursuit.This composition delves into the concept of challenging new frontiers,both in the literal sense of physical exploration and in the metaphorical sense of personal and intellectual growth.The Physical Frontier:Exploration and DiscoveryThe physical frontier has historically been associated with geographical exploration. From the Age of Discovery,when European explorers ventured into the unknown,to the modern era of space exploration,humanity has always been drawn to the edges of the map.English,as a global language,has played a pivotal role in documenting these journeys.For instance,the diaries of Christopher Columbus and the Apollo mission transcripts are all written in English,showcasing the languages ability to capture the awe and wonder of new discoveries.The Technological Frontier:Innovation and ProgressIn the realm of technology,English has become the lingua franca for innovation.The language of coding,programming,and software development is predominantly English, enabling a global community of tech enthusiasts and professionals to collaborate and push the boundaries of what is possible.From the development of the internet to advancements in artificial intelligence,English serves as the common ground for sharing ideas and breakthroughs.The Intellectual Frontier:Expanding Knowledge and UnderstandingThe intellectual frontier is perhaps the most profound of all.It encompasses the pursuit of knowledge in various fields such as science,philosophy,and the arts.English,with its extensive academic literature and research papers,facilitates the dissemination of new ideas and theories.The languages flexibility and precision make it an ideal tool for academic discourse,enabling scholars to challenge established norms and propose new paradigms.The Personal Frontier:SelfDiscovery and GrowthOn a more personal level,challenging new frontiers can mean overcoming personallimitations and achieving selfimprovement.English,with its expressive capabilities, allows individuals to articulate their aspirations,fears,and triumphs.Autobiographies, motivational speeches,and selfhelp books written in English inspire countless people to embark on their own journeys of selfdiscovery.The Cultural Frontier:Bridging Diverse PerspectivesCultural exploration is another dimension where English plays a significant role.As a language spoken in various parts of the world,it serves as a bridge between different cultures,allowing for the exchange of ideas and the appreciation of diverse perspectives. English literature,cinema,and music often reflect this cultural diversity,enriching the global community and fostering a deeper understanding of different ways of life.ConclusionIn conclusion,the concept of challenging new frontiers is multifaceted and can be approached from various angles.English,with its versatility and widespread use,is an indispensable tool in this endeavor.Whether it is through the documentation of physical exploration,the advancement of technology,the pursuit of intellectual knowledge, personal growth,or cultural understanding,English enables us to express,share,and celebrate the human spirits relentless quest for new horizons.。
Geographic_Information_Systems_and_Science_Today_and_Tomorrow
A technology of dynamics
• Real-time, continuous monitoring • The state of the world at all times
– the state of the transportation network – the state of human health – the state of the environment
• Theories of representation
– discrete objects and continuous fields – object fields, metamaps – unification
• Models of uncertainty
– error propagation – downscaling
– goods from production to retail display to sale – construction materials – pets, livestock, children, parolees
NYC Office of Emergency Management and NY Office of Cyber Security and Critical Infrastructure Coordination
• The science behind the systems • The fundamental issues raised by the technologies • The principles implemented in the technologies
Major discoveries in GIScience
牛顿-拉夫逊潮流计算中检测雅可比矩阵奇异性和网络孤岛的新方法
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中国新技术新产 品
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英文期刊名翻译
英译汉：The Space Shuttle and Geological Remote Sensing 航天飞机与地质遥感Orchids and Insects兰花和昆虫Study Shows Possible New Way to Treat Glaucoma 治疗青光眼之新途径Tips for Selecting ‘Sun proof’Sunglasses选购‘防日光’太阳镜的忠告Scanning High Energy Electron Diffraction扫描高能电子衍射On the Units of the Equilibrium Constant试论平衡常数的单位Body Tissue May Soon Repair Damaged Hearts人体组织不久可以修补坏死的心脏Trip to Earth Core : Myth or Reality ?地心旅游: 神话还是现实?Life on Distant P1anets遥远星球上的生命Biological Weapons Date to Classic Age生物武器自古有之It May Be Easy To Live Longer - Just Stop Eating 略带三分饥健康又长寿Robot Home Guard日本推出看门机器人主人出门在外不用愁Wearable Computers You Can Slip Into可穿着电脑’将逐渐走进我们的生活Smog Discriminates Between The Sexes烟雾生‘眼’:性别搞歧视an improved version of the minute paper,记录论文的改良版the information content of share repurchase programs.股票回购计划的信息内容Studies on Catalysts and Hydroprocessing Technology of Low-temperature Coal Tar.中低温煤焦油加氢催化剂及工艺研究Solution-Based Synthesis, Characterization and Property Investigation of Low-Dimensional Functional Nanomaterials低维功能纳米材料的液相合成、表征与性能研究Synthesis and Characterization of Ceria Nanoparticles纳米二氧化铈的制备与表征Speciation Analysis of Mercury and Arsenic in Aquatic Products水产品中砷、汞形态分析研究Problem of Rural Land Transfer System我国农村土地流转问题研究汉译英：我国农村土地流转问题研究Problem of Rural Land Transfer System光子晶体中的反常色散和传导模Anomalous Dispersion and Guide Modes in the Photonic Crystals棉花黄萎病菌T-DNA插入突变体表型特征和侧翼序列分析Analysis of T-DNA Insertional Flanking Sequence and Mutant Phenotypic Characteristics in Verticillium Dahliae苗期弱光对花生光合特性的影响Effects of Weak Light on Photosynthetic Characteristics ofPeanut Seedlings酵母异源互补法鉴定MbNramp1基因的功能Function Analysis of MbNramp1 Gene from Malus baccata (L.) Borkh Through Yeast Complementation Experiments夜间增温对冬小麦生长和产量影响的实验研究Winter Wheat Yields Decline with Spring Higher Night Temperature by Controlled Experiments朝中奖,夕死可矣Magazine Offers a Prize to Die F or压缩感知研究Research on Compressed Sensing可信计算技术研究Research on Trusted Computing Technology压缩传感理论与重构算法The Theory of Compressed Sensing and Reconstruction Algorithm人类大脑、认知与行为进化的整合模型An Integrative Model of Human Brain, Cognitive, and Behavioral Evolution一种PWM整流器直接功率控制方法A New Direct Power Control for PWM Rectifier可信计算的产业趋势和研究Industry Trends and Research in Dependable Computing氧化石墨烯及其氧化铁复合物的原位合成In situ synthesis of graphene oxide and its composites with iron oxide智能电网:改造电力系统Smart Grid: Transforming the Electric System基于NMR的代谢组学方法最新进展及应用Recent Developments and Applications of NMR-Based Metabonomics温度对美拉德反应的研究(Effects of Temperatures on Maillard Reactions基于分子标记的油菜隐性核不育7-7365AB遗传模式探究Analysis of Genetic Model for a Recessive Genic Male Sterile Line 7-7365AB in Brassica napus L. Based on Molecular Markers贵州野生山桐子种群年龄结构及其动态特性Study on Age Structure and Its Dynamic Characteristics of Wild Idesia polycarpa Population in Guizhou Province干旱胁迫对大丽花生理生化指标的影响Effects of drought stress on physiological and biochemical parameters of Dahlia pinnata。
最伟大的物理学家Top10(国外英文资料)
Top 10 Greatest Physicists of All Time (Based on Foreign English Resources)1. Albert EinsteinWithout a doubt, Albert Einstein tops the list of the greatest physicists of all time. His theory of relativity revolutionized our understanding of space, time, and gravity. Einstein's famous equation, E=mc², demonstrated the relationship between energy and mass, opening up new possibilities in the field of physics.2. Isaac NewtonSir Isaac Newton is another physicist who has left an indelible mark on the scientific world. His laws of motion and universal gravitation laid the foundation for classical mechanics. Newton's work in optics and the development of the reflecting telescope also contributed significantly to the advancement of physics.3. Niels BohrNiels Bohr, a Danish physicist, played a crucial role in the development of quantum mechanics. His model of the atom, which incorporated the concept of quantized energy levels, helped to explain the behavior of electrons and the stability of atoms.4. James Clerk MaxwellScottish physicist James Clerk Maxwell is renowned forhis formulation of the classical theory of electromagnetic radiation. His set of equations, known as Maxwell's equations, unified the understanding of electricity, magnetism, andlight.5. Richard FeynmanRichard Feynman was an American theoretical physicist who made significant contributions to quantum mechanics andparticle physics. His development of the path integral formulation of quantum mechanics and his work on the theoryof quantum electrodynamics earned him a Nobel Prize in Physics.6. Max PlanckGerman physicist Max Planck is considered the father of quantum theory. His discovery of Planck's constant and his proposal that energy is radiated in discrete packets, or quanta, marked the beginning of quantum physics.7. Werner HeisenbergWerner Heisenberg, another prominent figure in quantum mechanics, formulated the uncertainty principle, which states that it is impossible to simultaneously know the exactposition and momentum of a particle.8. Galileo GalileiGalileo Galilei, often referred to as the "Father of Modern Science," made significant contributions to physics, astronomy, and the scientific method. His work on inertia, falling objects, and the laws of motion laid the groundwork for Newton's theories.9. Stephen Hawking10. Marie CurieMarie Curie, a Polishborn physicist and chemist, was the first woman to win a Nobel Prize and remains the only person to win Nobel Prizes in two different sciences (Physics and Chemistry). Her work on radioactivity opened up new avenues in medical research and laid the foundation for the field of atomic physics.Continuing the exploration of the most influential physicists in history, let's delve into the lives and achievements of these extraordinary individuals who have shaped our understanding of the universe.11. Paul DiracPaul Dirac, an English theoretical physicist, is often celebrated for his prediction of the existence of antimatter, a discovery that was later confirmed the experimental work of Carl Anderson. Dirac's formulation of quantum mechanics, particularly the Dirac equation, was pivotal in the development of quantum field theory.12. Michael FaradayMichael Faraday was a British scientist who contributed immensely to the study of electromagnetism. His experiments led to the discovery of electromagnetic induction, the laws of electrolysis, and the invention of the Faraday cage. Faraday's work laid the groundwork for the future development of electric motors and generators.13. Ludwig BoltzmannAustrian physicist Ludwig Boltzmann was a key figure in the development of statistical mechanics and thermodynamics. His insight into the behavior of molecules and his formulation of the Boltzmann equation helped to explain the concepts of entropy and the statistical nature of physical laws.14. Ernest RutherfordErnest Rutherford, a New Zealandborn British physicist, is known as the father of nuclear physics. His groundbreaking gold foil experiment led to the discovery of the atomic nucleus and the understanding that most of an atom's mass is concentrated in a tiny, central nucleus.15. Murray GellMann16. J.J. ThomsonSir Joseph John Thomson, an English physicist, discovered the electron in 1897, demonstrating that atoms are notindivisible and consist of smaller particles. His work on cathode rays and the discovery of the masstocharge ratio of electrons was fundamental in the development of atomic physics.17. Enrico FermiEnrico Fermi, an Italian physicist, was pivotal in the development of nuclear technology. His work on nuclear reactions led to the construction of the first nuclear reactor and the first controlled nuclear chain reaction. Fermi's contributions to quantum theory and particle physics are also noteworthy.18. Lise MeitnerLise Meitner, an AustrianSwedish physicist, was involved in the discovery of nuclear fission. Despite facing discrimination as a woman in science, Meitner's work was crucial in understanding the process which heavy nuclei can split into lighter nuclei, releasing a significant amount of energy.19. Roger PenroseBritish mathematician and physicist Roger Penrose has made significant contributions to the understanding of general relativity and cosmology. His work on black holes, particularly the Penrose process and the Penrose singularitytheorem, has deepened our knowledge of the most extreme phenomena in the universe.20. Kip ThorneKip Thorne, an American theoretical physicist, has been at the forefront of gravitational physics and astrophysics. His work on the detection of gravitational waves, as part of the LIGO collaboration, confirmed a key prediction of Einstein's theory of general relativity and opened a new window into the cosmos.Each of these physicists has left an indelible mark on the field, pushing the boundaries of human knowledge and challenging our understanding of the natural world. Their legacies continue to inspire and guide the next generation of scientists in their quest to uncover the secrets of the universe.As we further unravel the rich tapestry of scientific achievement, let's continue to honor the contributions of more extraordinary physicists whose insights have transformed our understanding of the cosmos and the fundamental forces that govern it.21. Andrei SakharovAndrei Sakharov, a Soviet nuclear physicist, played a crucial role in the development of the Soviet hydrogen bomb. However, he is perhaps best known for his advocacy of civilliberties and human rights in the Soviet Union. His work on the concept of "metric elasticity" also contributed to the field of general relativity.22. ChenNing YangChenNing Yang, a ChineseAmerican physicist, made significant contributions to theoretical physics,particularly in the area of parity nonconservation in weak interactions. His work with TsungDao Lee led to a Nobel Prize in Physics, demonstrating that certain processes are not mirrorsymmetric.23. TsungDao LeeTsungDao Lee, a ChineseAmerican physicist, collaborated with ChenNing Yang to challenge the symmetry principles in physics. Their proposal that weak interactions do not conserve parity was a groundbreaking discovery that revolutionized particle physics.24. Sheldon GlashowSheldon Glashow, an American theoretical physicist, is known for his work on the electroweak theory, which unified the weak nuclear force and electromagnetism. Hiscontributions to particle physics, including the prediction of the W and Z bosons, were recognized with a Nobel Prize in Physics.25. Abdus SalamAbdus Salam, a Pakistani theoretical physicist, sharedthe Nobel Prize in Physics with Sheldon Glashow and Steven Weinberg for their work on the electroweak unification. Salam was instrumental in developing the mathematical frameworkthat described the weak and electromagnetic forces asdifferent aspects of the same force.26. Edward WittenEdward Witten, an American theoretical physicist and mathematician, is often regarded as one of the leadingfigures in string theory. His work has deepened our understanding of the mathematical underpinnings of theuniverse and has earned him numerous accolades, including the Fields Medal.27. Julian Schwinger28. SinItiro Tomonaga29. George GamowGeorge Gamow, a RussianAmerican physicist and cosmologist, made significant contributions to the fields of nuclearphysics and cosmology. He was one of the first to propose the Big Bang theory as the origin of the universe and also made important contributions to the understanding of stellar nucleosynthesis.30. Freeman DysonFreeman Dyson, a BritishAmerican theoretical physicist and mathematician, has made numerous contributions to quantum electrodynamics and solidstate physics. His work on the unification of the electromagnetic and gravitational forces, as well as his speculations on Dyson spheres, have been influential in theoretical physics.These physicists, through their relentless pursuit of knowledge, have not only advanced the frontiers of science but have also inspired a sense of wonder and curiosity in generations of scholars and laypeople alike. Their work continues to be a testament to the power of human intellect and the boundless potential of scientific inquiry.。
Chapter14
Fig. 14-2 The curvature of space-time around a massive object, as predicted by general relativity, can be loosely pictured as the curvature on a rubber sheet caused by a heavy ball. Although this is only an analogy, it can help us to visualize many abstract concepts described by Einstein′s theory.
物质在强大的引力作用下被压缩到极度弯曲的空间中甚至连光也无法逃逸出来这个极度弯曲的时空区域称为黑洞blackhole
Chapter 14 Black holes
14.1 Newtonian picture Escape velocity: the minimum initial velocity needed to escape from a star Stronger gravity on the star′s surface larger escape velocity (more difficult to escape) Newton′s law of gravitation: the surface gravity is strong when the star is massive, or the star is small (inverse square law) If a star is massive and small
Fig. 14-5 The Kerr black hole consists of a rotating mass at the center, surrounded by two event horizons. The outer event horizon marks the boundary within which an observer cannot resist being dragged around the black hole with space-time. The inner event horizon marks the boundary within which nothing can escape.
天地一体化信息网络频谱共享技术的综述与展望(上)
观察Industry ObservationI G I T C W 产业26DIGITCW2021.050 引言地面通信网与卫星通信网分别在各自擅长的服务范围内发挥着巨大的作用。
尽管地面移动通信技术已经发展到5G ，但覆盖范围受限的短板仍不能解决，而另一面具有广覆盖特性的卫星通信却因成本过高等因素无法普及。
随着人们对通信需求向多空间、多方位的不断扩展，融合天、地通信技术优势，构建覆盖全球的天地一体化信息网络是未来通信发展的重要趋势，通过融合设计而构建的多维立体、全方位和全天候的信息网络，可为空、天、地、海等不同应用场景的用户提供全球泛在的通信服务[1]。
在天地一体化信息网络中，大部分通信节点依赖于有限的无线电频谱资源进行传输，信道开放、频率需求大、涉及无线电业务多是其主要特点。
以往，地基网络或天基网络对于无线电频谱资源的使用，均采用独占授权的静态规划方式，对于所授权频谱的使用，存在着部分时间过度浪费或过度拥挤的情况。
此外，对于那些尤为适用于天地一体化卫星宽带接入要求的Ka 和Q/V 等频段，天基网络或地基网络都出现了避无可避的状态[2]。
因此，设计天地一体化信息网络无线频谱动态共享方案，提高频谱资源利用效率，是网络建设中需要重点关注的问题之一[3]。
20年来，人们对于地基网络频谱共享的研究较为广泛，提出了大量的动态频谱共享技术。
但天地一体化信息网络与地基网络的存在诸多差异，不能直接使用地基网络的频谱共享技术，需根据其特点重新设计或适当改进。
但地基网络中的用于干扰规避的功率控制、波束赋形、跳波束及频谱数据库等技术，为天地一体化信息网络频谱共享提供重要的研究思路。
因此，近来学者从不同角度、针对多种场景提出了一些天地一体化信息网频谱共享的算法和方案。
从是否需要空口技术及核心网统一设计的角度可将现有研究分成两大类：一是基于干扰规避的星地频谱共存，研究对象是分立的天基和地基通信系统，通过设计天地一体化信息网络频谱共享技术的综述与展望（上）孙永林（海装重大专项装备项目管理中心，北京 100000）摘要：天地一体化信息网络是未来突破地面网络限制，实现空、天、地、海等多空间无缝覆盖和泛在连接的重要网络架构。
QuantumFields_Bogoliubov
Quantum FieldsN.N.BogoliubovD.V.ShirkovJo i nt Institutefor Nuclear ResearchDubna,U.S.S.R.Authonrized translation from the Russian edition byD.B.Pontecorvo1983The Benjamin Cummings Publishing Company,Inc.Advanced Book ProgramReading,MassachusettsLondon Amsterdam Don Mills Ontario Sydney Tokyoviii Contents20.The Feynman rules i n the p-representation184201Transition to the momentum representation18420:2Feynman 's rules for the evaluation of elements18820.3An illustration forthe model18720.4Spinor electrodynamics18921.Transition probabilities19321.1The general structure of matrix elements19321.2Normalization of the state amplitude19521.3The general fonnula for transition probability19721.4Scattering of two particles19921.5The two-particle decay202Chapter VI.Evaluation of Integrals and Divergences20322.The method for evaluating integrals20322.1Integrals over virtual momenta20322.2The a-representation and Gaussian quadratures20422.3Feynman's parametrization20722.4Ultraviolet divergences20923.Auxiliary regularizations21023.1The necessity of regularization21023.2Pauli-Villars regularization21123.3D i mensionai regularization21323.4Regularization by means of a cutoff21524.One -loop diagrams21624.1The scalar "fish"21624.2Self-energies of the photon and of the electron21824.3Triangular diagrams22124.4Ultraviolet divergences of higher orders 22325.Isolation of the divergences22525.1The structure of one-loop divergences22525.2The contribution to the S-matrix22625.3Counterterms and renormalizations22925.4Divergences and distributions231Chapter VII .Removal of Divergences23326.The general structure of divergences23326.1divergences23326.2The connection with countertenns and renormalizations23626.3The degree of divergence of diagrams23826.4The property of renonnalizabilit 24027.Dressed Green's functions24227.1Propagators of physical fields24227.2Higher Green 's functions 245Matrix the vertex Higher-orderContents xi "September"Assignment(for Chapter I)365 "October"Assignment(for Chapter II)369 "November"Assignment(for Chapter III)372 "December"Assignment(for Chapter IV)375 "February"Assignment(for Chapter V)376 "March"Assignment(for Chapter VI)378 "April"Assignment(for Chapter VII)379Recommendations for Use381References383 Subject Index..385PREFACEThe main purpose of this book is to provide graduate students in physicswith the necessary minimum of infonnation on the fundament~sof modem quantum field theory.It may tum out to be sufficient both for theoreticians,specializing in nuclear physics,quantum statistics and other fields,in which quantum field methods are utilized and which are based on quantum concepts,and also for experimental physicists in the fields of nuclear and high-energy physics.For the latter category of readers the present book should be supplemented by a course on particle physics and particle interactions.At the same time the book can be recommended as an introductury text for persons intending to work in the field of quantum field theory and of the theory of elementary interactions.The material in this book corresponds to a course lasting one academic year.Our personal experience testifies that parallel practical studies at seminars are extremely desirable.For this purpose part of the technical material has been assembled at the end of the book in the fo rm of Appendices.There,also,sets of exercises and problems,gathered together as assignments corresponding to chapters of the main text,are given.The authors are grateful to the editor of this book D.A.Slavnov,to thereviewers M.A.Brown,L.V.Prokhorov,K.A.Ter~Martirosyan,and also to B.M.Barbashov,B.V.Medvediev,and N.M.Shumeiko for valuable comments on the typescript of the book.N.N.BogoliubovD.V.Shirkovfundamentals Ter-MartirosyanPREFACE TO THEENGLISH-LANGUAGE EDITION This book is a text on the fundamentals of quantum field theory and renormalized perturbation theory(RPT).The traditional field of application of the latter for a long time was limited to quantum electrodynamics.During recent years,due to the creation of a unified theory of electroweak interac-tions and to the successes of quantum chromodynamics it has become clear that the physical scope of RPT is much wider.However,in the study of the quark-gluon interaction,as well as of possible mechanisms of the grand unification of interactions,a decisive partis played by the simultaneous use of results of RPT and of the apparatus of the renormalization-group method.Therefore we have written a special Appendix IX,"The renormaliza-tion group,"for the English-language edition of our book.Besides this,small editorial changes and corrections of noticed misprints have been made.N.N.BogoliubovD.V.Shirkovxv。
上外考研翻译硕士英语天文学专业词汇整理分享
上外考研翻译硕士英语天文学专业词汇整理分享find 发见陨星finder chart 证认图finderscope 寻星镜first-ascent giant branch初升巨星支first giant branch 初升巨星支flare puff 耀斑喷焰flat field 平场flat field correction 平场改正flat fielding 平场处理flat-spectrum radio quasar 平谱射电类星体flux standard 流量标准星flux-tube dynamics 磁流管动力学f-mode f 模、基本模following limb 东边缘、后随边缘foreground galaxy 前景星系foreground galaxy cluster 前景星系团formal accuracy 形式精度Foucaultgram 傅科检验图样Foucault knife-edge test 傅科刀口检验fourth cosmic velocity 第四宇宙速度frame transfer 帧转移Fresnel lens 菲涅尔透镜fuzz 展云Galactic aggregate 银河星集Galactic astronomy 银河系天文Galactic bar 银河系棒galactic bar 星系棒galactic cannibalism 星系吞食galactic content 星系成分galactic merge 星系并合galactic pericentre 近银心点Galactocentric distance 银心距galaxy cluster 星系团Galle ring 伽勒环Galilean transformation 伽利略变换Galileo 〈伽利略〉木星探测器gas-dust complex 气尘复合体Genesis rock 创世岩Gemini Telescope 大型双子望远镜giant granulation 巨米粒组织giant granule 巨米粒giant radio pulse 巨射电脉冲Ginga 〈星系〉X 射线天文卫星Giotto 〈乔托〉空间探测器glassceramic 微晶玻璃glitch activity 自转突变活动global change 全球变化global sensitivity 全局灵敏度GMC, giant molecular cloud 巨分子云g-mode g 模、重力模gold spot 金斑病GONG, Global Oscillation Network 太阳全球振荡监测网GPS, global positioning system 全球定位系统Granat 〈石榴〉号天文卫星grand design spiral 宏象旋涡星系gravitational astronomy 引力天文gravitational lensing 引力透镜效应gravitational micro-lensing 微引力透镜效应great attractor 巨引源Great Dark Spot 大暗斑Great White Spot 大白斑grism 棱栅GRO, Gamma-Ray Observatory γ射线天文台guidscope 导星镜GW Virginis star 室女GW 型星habitable planet 可居住行星Hakucho 〈天鹅〉X 射线天文卫星Hale Telescope 海尔望远镜halo dwarf 晕族矮星halo globular cluster 晕族球状星团Hanle effect 汉勒效应hard X-ray source 硬X 射线源Hay spot 哈伊斑HEAO, High-Energy Astronomical 〈HEAO〉高能天文台Observatory heavy-element star 重元素星heiligenschein 灵光Helene 土卫十二helicity 螺度heliocentric radial velocity 日心视向速度heliomagnetosphere 日球磁层helioseismology 日震学helium abundance 氦丰度helium main-sequence 氦主序helium-strong star 强氦线星helium white dwarf 氦白矮星Helix galaxy ( NGC 2685 ) 螺旋星系Herbig Ae star 赫比格Ae 型星Herbig Be star 赫比格Be 型星Herbig-Haro flow 赫比格-阿罗流Herbig-Haro shock wave 赫比格-阿罗激波hidden magnetic flux 隐磁流high-field pulsar 强磁场脉冲星highly polarized quasar ( HPQ ) 高偏振类星体high-mass X-ray binary 大质量X 射线双星high-metallicity cluster 高金属度星团;high-resolution spectrograph 高分辨摄谱仪high-resolution spectroscopy 高分辨分光high - z 大红移Hinotori 〈火鸟〉太阳探测器Hipparcos, High Precision Parallax 〈依巴谷〉卫星Collecting SatelliteHipparcos and Tycho Catalogues 〈依巴谷〉和〈第谷〉星表holographic grating 全息光栅Hooker Telescope 胡克望远镜host galaxy 寄主星系hot R Coronae Borealis star 高温北冕R 型星HST, Hubble Space Telescope 哈勃空间望远镜Hubble age 哈勃年龄Hubble distance 哈勃距离Hubble parameter 哈勃参数Hubble velocity 哈勃速度hump cepheid 驼峰造父变星Hyad 毕团星hybrid-chromosphere star 混合色球星hybrid star 混合大气星hydrogen-deficient star 缺氢星hydrogenous atmosphere 氢型大气hypergiant 特超巨星Ida 艾达( 小行星243号)IEH, International Extreme Ultraviolet Hitchhiker〈IEH〉国际极紫外飞行器IERS, International Earth Rotation Service国际地球自转服务image deconvolution 图象消旋image degradation 星象劣化image dissector 析象管image distoration 星象复原image photon counting system 成象光子计数系统image sharpening 星象增锐image spread 星象扩散度imaging polarimetry 成象偏振测量imaging spectrophotometry 成象分光光度测量immersed echelle 浸渍阶梯光栅impulsive solar flare 脉冲太阳耀斑infralateral arc 外侧晕弧infrared CCD 红外CCDinfrared corona 红外冕infrared helioseismology 红外日震学infrared index 红外infrared observatory 红外天文台infrared spectroscopy 红外分光initial earth 初始地球initial mass distribution 初始质量分布initial planet 初始行星initial star 初始恒星initial sun 初始太阳inner coma 内彗发inner halo cluster 内晕族星团integrability 可积性Integral Sign galaxy ( UGC 3697 ) 积分号星系integrated diode array ( IDA ) 集成二极管阵intensified CCD 增强CCD Intercosmos 〈国际宇宙〉天文卫星interline transfer 行间转移intermediate parent body 中间母体intermediate polar 中介偏振星international atomic time 国际原子时International Celestial Reference 国际天球参考系Frame ( ICRF ) intraday variation 快速变化intranetwork element 网内元intrinsic dispersion 内廪弥散度ion spot 离子斑IPCS, Image Photon Counting System 图象光子计数器IRIS, Infrared Imager / Spectrograph 红外成象器/摄谱仪IRPS, Infrared Photometer / Spectro- meter 红外光度计/分光计irregular cluster 不规则星团; 不规则星系团IRTF, NASA Infrared Telescope 〈IRTF〉美国宇航局红外Facility 望远镜IRTS, Infrared Telescope in Space 〈IRTS〉空间红外望远镜ISO, Infrared Space Observatory 〈ISO〉红外空间天文台isochrone method 等龄线法IUE, International Ultraviolet Explorer〈IUE〉国际紫外探测器Jewel Box ( NGC 4755 ) 宝盒星团Jovian magnetosphere 木星磁层Jovian ring 木星环Jovian ringlet 木星细环Jovian seismology 木震学jovicentric orbit 木心轨道J-type star J 型星Juliet 天卫十一Jupiter-crossing asteroid 越木小行星Kalman filter 卡尔曼滤波器KAO, Kuiper Air-borne Observatory 〈柯伊伯〉机载望远镜Keck ⅠTelescope 凯克Ⅰ望远镜Keck ⅡTelescope 凯克Ⅱ望远镜Kuiper belt 柯伊伯带Kuiper disk 柯伊伯盘LAMOST, Large Multi-Object Fibre Spectroscopic Telescope大型多天体分光望远镜Laplacian plane 拉普拉斯平面late cluster 晚型星系团LBT, Large Binocular Telescope 〈LBT〉大型双筒望远镜lead oxide vidicon 氧化铅光导摄象管Leo Triplet 狮子三重星系LEST, Large Earth-based Solar Telescope〈LEST〉大型地基太阳望远镜level-Ⅰcivilization Ⅰ级文明level-Ⅱcivilization Ⅱ级文明level-Ⅲcivilization Ⅲ级文明Leverrier ring 勒威耶环Liapunov characteristic number 李雅普诺夫特征数light crown 轻冕玻璃light echo 回光light-gathering aperture 聚光孔径light pollution 光污染light sensation 光感line image sensor 线成象敏感器line locking 线锁line-ratio method 谱线比法Liner, low ionization nuclear 低电离核区emission-line regionline spread function 线扩散函数LMT, Large Millimeter Telescope 〈LMT〉大型毫米波望远镜local galaxy 局域星系local inertial frame 局域惯性架local inertial system 局域惯性系local object 局域天体local star 局域恒星look-up table ( LUT ) 对照表low-mass X-ray binary 小质量X 射线双星low-metallicity cluster 低金属度星团;low-resolution spectrograph 低分辨摄谱仪low-resolution spectroscopy 低分辨分光low - z 小红移luminosity mass 光度质量luminosity segregation 光度层化luminous blue variable 高光度蓝变星lunar atmosphere 月球大气lunar chiaroscuro 月相图Lunar Prospector 〈月球勘探者〉Ly-α forest 莱曼-α森林MACHO ( massive compact halo object ) 晕族大质量致密天体Magellan 〈麦哲伦〉金星探测器Magellan Telescope 〈麦哲伦〉望远镜magnetic canopy 磁蓬magnetic cataclysmic variable 磁激变变星magnetic curve 磁变曲线magnetic obliquity 磁夹角magnetic period 磁变周期magnetic phase 磁变相位magnitude range 星等范围main asteroid belt 主小行星带main-belt asteroid 主带小行星main resonance 主共振main-sequence band 主序带Mars-crossing asteroid 越火小行星Mars Pathfinder 火星探路者mass loss rate 质量损失率mass segregation 质量层化Mayall Telescope 梅奥尔望远镜Mclntosh classification 麦金托什分类McMullan camera 麦克马伦电子照相机mean motion resonance 平均运动共振membership of cluster of galaxies 星系团成员membership of star cluster 星团成员merge 并合merger 并合星系; 并合恒星merging galaxy 并合星系merging star 并合恒星mesogranulation 中米粒组织mesogranule 中米粒metallicity 金属度metallicity gradient 金属度梯度metal-poor cluster 贫金属星团metal-rich cluster 富金属星团MGS, Mars Global Surveyor 火星环球勘测者micro-arcsec astrometry 微角秒天体测量microchannel electron multiplier 微通道电子倍增管microflare 微耀斑microgravitational lens 微引力透镜microgravitational lensing 微引力透镜效应microturbulent velocity 微湍速度millimeter-wave astronomy 毫米波天文millisecond pulsar 毫秒脉冲星minimum mass 质量下限minimum variance 最小方差mixed-polarity magnetic field 极性混合磁场MMT, Multiple-Mirror Telescope 多镜面望远镜moderate-resolution spectrograph 中分辨摄谱仪moderate-resolution spectroscopy 中分辨分光modified isochrone method 改进等龄线法molecular outflow 外向分子流molecular shock 分子激波monolithic-mirror telescope 单镜面望远镜moom 行星环卫星moon-crossing asteroid 越月小行星morphological astronomy 形态天文morphology segregation 形态层化MSSSO, Mount Stromlo and Siding Spring Observatory斯特朗洛山和赛丁泉天文台multichannel astrometric photometer ( MAP )多通道天测光度计multi-object spectroscopy 多天体分光multiple-arc method 复弧法multiple redshift 多重红移multiple system 多重星系multi-wavelength astronomy 多波段天文multi-wavelength astrophysics 多波段天体物理naked-eye variable star 肉眼变星naked T Tauri star 显露金牛T 型星narrow-line radio galaxy ( NLRG ) 窄线射电星系Nasmyth spectrograph 内氏焦点摄谱仪natural reference frame 自然参考架natural refenence system 自然参考系natural seeing 自然视宁度near-contact binary 接近相接双星near-earth asteroid 近地小行星near-earth asteroid belt 近地小行星带near-earth comet 近地彗星NEO, near-earth object 近地天体neon nova 氖新星Nepturian ring 海王星环neutrino astrophysics 中微子天文NNTT, National New Technology Telescope国立新技术望远镜NOAO, National Optical Astronomical 国立光学天文台Observatories nocturnal 夜间定时仪nodal precession 交点进动nodal regression 交点退行non-destroy readout ( NDRO ) 无破坏读出nonlinear infall mode 非线性下落模型nonlinear stability 非线性稳定性nonnucleated dwarf elliptical 无核矮椭圆星系nonnucleated dwarf galaxy 无核矮星系nonpotentiality 非势场性nonredundant masking 非过剩遮幅成象nonthermal radio halo 非热射电晕normal tail 正常彗尾North Galactic Cap 北银冠NOT, Nordic Optical Telescope 北欧光学望远镜nova rate 新星频数、新星出现率NTT, New Technology Telescope 新技术望远镜nucleated dwarf elliptical 有核矮椭圆星系nucleated dwarf galaxy 有核矮星系number density profile 数密度轮廓numbered asteroid 编号小行星oblique pulsator 斜脉动星observational cosmology 观测宇宙学observational dispersion 观测弥散度observational material 观测资料observing season 观测季occultation band 掩带O-Ne-Mg white dwarf 氧氖镁白矮星one-parameter method 单参数法on-line data handling 联机数据处理on-line filtering 联机滤波open cluster of galaxies 疏散星系团Ophelia 天卫七optical aperture-synthesis imaging 光波综合孔径成象optical arm 光学臂optical disk 光学盘optical light 可见光optical luminosity function 光学光度函数optically visible object 光学可见天体optical picture 光学图optical spectroscopy 光波分光orbital circularization 轨道圆化orbital eccentricity 轨道偏心率orbital evolution 轨道演化orbital frequency 轨道频率orbital inclination 轨道倾角orbit plane 轨道面order region 有序区organon parallacticon 星位尺Orion association 猎户星协orrery 太阳系仪orthogonal transformation 正交变换oscillation phase 振动相位outer asteroid belt 外小行星带outer-belt asteroid 外带小行星outer halo cluster 外晕族星团outside-eclipse variation 食外变光overshoot 超射OVV quasar, optically violently OVV 类星体variable quasar、optically violent variable quasar oxygen sequence 氧序pan 摇镜头parry arc 彩晕弧partial-eclipse solution 偏食解particle astrophysics 粒子天体物理path of annularity 环食带path of totality 全食带PDS, photo-digitizing system、PDS、数字图象仪、photometric data system 测光数据仪penetrative convection 贯穿对流pentaprism test 五棱镜检验percolation 渗流periapse 近质心点periapse distance 近质心距periapsis distance 近拱距perigalactic distance 近银心距perigalacticon 近银心点perimartian 近火点period gap 周期空隙period-luminosity-colour relation 周光色关系PG 1159 star PG 1159 恒星photoflo 去渍剂photographic spectroscopy 照相分光。
跨层级地理空间情报共享构成大数据挑战
跨层级地理空间情报共享构成大数据挑战译自：美国防务系统网站 2012年11月15日作者：约翰·爱德华兹编译：知远/张锐译文信息表[知远导读]本文主要地理空间情报（GEOINT）在在各层级之间共享时遇到的大数据挑战，如数据政策、政策法规缺失、文化壁垒和相关标准等问题。
文章针对这些问题给出了看法和建议。
文章编译如下：系统、技术、人员、运行理念、标准、格式和协议必须全集中在一起才能创建一个标准的、可共享的地理空间基础。
因此，若要高效完美地在各层级之间共享地理空间情报，就需要从地理空间情报（GEOINT）中收集大量的数据，这构成了大数据挑战。
“卫星、无人机、海基或陆基传感器、社交网络和移动设备产生了应接不暇的位置信息数据，”总部位于马萨诸塞州的云计算提供商EMC的霍普金顿联合首席技术官瑞奇·坎贝尔说道。
然而，带宽目前仍然稀少并且有限。
美国国防部和相关网络、IT供应商正在寻求办法解决这个最大的瓶颈。
坎贝尔说，“增加带宽和改进带宽管理政策将会使数据共享更有效率”。
在制定和评估未来带宽增强方案的同时，数据分析也受到了密切关注。
强大的分析工具能够实时将原始数据转化为有价值的情报，从而把重要信息有效地传递给最终用户。
“数据分析技术能够细化任务指挥官所需要的数据集，”坎贝尔说，“分析师可以通过数据分析将数据细化成更小的子集，任务指挥官最终看到就只有他所需要的地理空间情报。
”坎贝尔指出，更多地运用虚拟化会使信息管理和信息共享更加有效。
“随着越来越多的地理空间情报系统转移到更加虚拟化环境中，我们看到了一系列重大收益，例如，计算、分析和存储设备的融合和成本的降低以及分布式基础设施中分析效果的改善，”他讲道。
数据和相关政策数据管理、数据分类和数据政策被广泛视为阻碍各层级间快速高效共享地理空间情报的障碍。
“由于共享变得更容易，我们的部队和国防机构应增加带宽、改善分类和优化管理，并且调整策略以更有效地改善和满足任务指挥官的信息需求，”坎贝尔说。
Entropy changes in the clustering of galaxies in a
Vol.3, No.1, 65-68 (2011)doi:10.4236/ns.2011.31009Natural ScienceEntropy changes in the clustering of galaxies in an expanding universeNaseer Iqbal1,2*, Mohammad Shafi Khan1, Tabasum Masood11Department of Physics, University of Kashmir, Srinagar, India; *Corresponding Author:2Interuniversity Centre for Astronomy and Astrophysics, Pune, India.Received 19 October 2010; revised 23 November 2010; accepted 26 November 2010.ABSTRACTIn the present work the approach-thermody- namics and statistical mechanics of gravitating systems is applied to study the entropy change in gravitational clustering of galaxies in an ex-panding universe. We derive analytically the expressions for gravitational entropy in terms of temperature T and average density n of the par-ticles (galaxies) in the given phase space cell. It is found that during the initial stage of cluster-ing of galaxies, the entropy decreases and fi-nally seems to be increasing when the system attains virial equilibrium. The entropy changes are studied for different range of measuring correlation parameter b. We attempt to provide a clearer account of this phenomena. The entropy results for a system consisting of extended mass (non-point mass) particles show a similar behaviour with that of point mass particles clustering gravitationally in an expanding uni-verse.Keywords:Gravitational Clustering; Thermodynamics; Entropy; Cosmology1. INTRODUCTIONGalaxy groups and clusters are the largest known gravitationally bound objects to have arisen thus far in the process of cosmic structure formation [1]. They form the densest part of the large scale structure of the uni-verse. In models for the gravitational formation of struc-ture with cold dark matter, the smallest structures col-lapse first and eventually build the largest structures; clusters of galaxies are then formed relatively. The clus-ters themselves are often associated with larger groups called super-clusters. Clusters of galaxies are the most recent and most massive objects to have arisen in the hiearchical structure formation of the universe and the study of clusters tells one about the way galaxies form and evolve. The average density n and the temperature T of a gravitating system discuss some thermal history of cluster formation. For a better larger understanding of this thermal history it is important to study the entropy change resulting during the clustering phenomena be-cause the entropy is the quantity most directly changed by increasing or decreasing thermal energy of intraclus-ter gas. The purpose of the present paper is to show how entropy of the universe changes with time in a system of galaxies clustering under the influence of gravitational interaction.Entropy is a measure of how disorganised a system is. It forms an important part of second law of thermody-namics [2,3]. The concept of entropy is generally not well understood. For erupting stars, colloiding galaxies, collapsing black holes - the cosmos is a surprisingly or-derly place. Supermassive black holes, dark matter and stars are some of the contributors to the overall entropy of the universe. The microscopic explanation of entropy has been challenged both from the experimental and theoretical point of view [11,12]. Entropy is a mathe-matical formula. Standard calculations have shown that the entropy of our universe is dominated by black holes, whose entropy is of the order of their area in planck units [13]. An analysis by Chas Egan of the Australian National University in Canberra indicates that the col-lective entropy of all the supermassive black holes at the centers of galaxies is about 100 times higher than previ-ously calculated. Statistical entropy is logrithmic of the number of microstates consistent with the observed macroscopic properties of a system hence a measure of uncertainty about its precise state. Statistical mechanics explains entropy as the amount of uncertainty which remains about a system after its observable macroscopic properties have been taken into account. For a given set of macroscopic quantities like temperature and volume, the entropy is a function of the probability that the sys-tem is in various quantumn states. The more states avail-able to the system with higher probability, the greater theAll Rights Reserved.N. Iqbal et al. / Natural Science 3 (2011) 65-6866 disorder and thus greater the entropy [2]. In real experi-ments, it is quite difficult to measure the entropy of a system. The technique for doing so is based on the thermodynamic definition of entropy. We discuss the applicability of statistical mechanics and thermodynam-ics for gravitating systems and explain in what sense the entropy change S – S 0 shows a changing behaviour with respect to the measuring correlation parameter b = 0 – 1.2. THERMODYNAMIC DESCRIPTION OF GALAXY CLUSTERSA system of many point particles which interacts by Newtonian gravity is always unstable. The basic insta-bilities which may occur involve the overall contraction (or expansion) of the system, and the formation of clus-ters within the system. The rates and forms of these in-stabilities are governed by the distribution of kinetic and potential energy and the momentum among the particles. For example, a finite spherical system which approxi-mately satisfies the viral theorem, contracts slowlycompared to the crossing time ~ ()12G ρ- due to the evaporation of high energy particles [3] and the lack of equipartition among particles of different masses [4]. We consider here a thermodynamic description for the sys-tem (universe). The universe is considered to be an infi-nite gas in which each gas molecule is treated to be agalaxy. The gravitational force is a binary interaction and as a result a number of particles cluster together. We use the same approximation of binary interaction for our universe (system) consisting of large number of galaxies clustering together under the influence of gravitational force. It is important to mention here that the characteri-zation of this clustering is a problem of current interest. The physical validity of the application of thermody-namics in the clustering of galaxies and galaxy clusters has been discussed on the basis of N-body computer simulation results [5]. Equations of state for internal energy U and pressure P are of the form [6]:(3122NTU =-)b (1) (1NTP V=-)b (2) b defines the measuring correlation parameter and is dimensionless, given by [8]()202,23W nb Gm n T r K Tτξ∞=-=⎰,rdr (3)W is the potential energy and K the kinetic energy ofthe particles in a system. n N V = is the average num-ber density of the system of particles each of mass m, T is the temperature, V the volume, G is the universalgravitational constant. (),,n T r ξ is the two particle correlation function and r is the inter-particle distance. An overall study of (),n T r ξ has already been dis-cussed by [7]. For an ideal gas behaviour b = 0 and for non-ideal gas system b varies between 0 and 1. Previ-ously some workers [7,8] have derived b in the form of:331nT b nT ββ--=+ (4) Eq.4 indicates that b has a specific dependence on the combination 3nT -.3. ENTROPY CALCULATIONSThermodynamics and statistical mechanics have been found to be equal tools in describing entropy of a system. Thermodynamic entropy is a non-conserved state func-tion that is of great importance in science. Historically the concept of entropy evolved in order to explain why some processes are spontaneous and others are not; sys-tems tend to progress in the direction of increasing en-tropy [9]. Following statistical mechanics and the work carried out by [10], the grand canonical partition func-tion is given by()3213212,1!N N N N mkT Z T V V nT N πβ--⎛⎫⎡=+ ⎪⎣Λ⎝⎭⎤⎦(5)where N! is due to the distinguishability of particles. Λrepresents the volume of a phase space cell. N is the number of paricles (galaxies) with point mass approxi-mation. The Helmholtz free energy is given by:ln N A T Z =- (6)Thermodynamic description of entropy can be calcu-lated as:,N VA S T ∂⎛⎫=- ⎪∂⎝⎭ (7)The use of Eq.5 and Eq.6 in Eq.7 gives()3120ln ln 13S S n T b b -⎛⎫-=-- ⎪ ⎪⎝⎭- (8) where S 0 is an arbitary constant. From Eq.4 we write()31bn b T β-=- (9)Using Eq.9, Eq.8 becomes as3203ln S S b bT ⎡⎤-=-+⎢⎣⎦⎥ (10)Again from Eq.4All Rights Reserved.N. Iqbal et al. / Natural Science 3 (2011) 65-68 6767()13221n b T b β-⎡⎤=⎢⎣⎦⎥ (11)with the help of Eq.11, Eq.10 becomes as()011ln ln 1322S S n b b b ⎡-=-+-+⎡⎤⎣⎦⎢⎥⎣⎦⎤ (12) This is the expression for entropy of a system consist-ing of point mass particles, but actually galaxies have extended structures, therefore the point mass concept is only an approximation. For extended mass structures we make use of softening parameter ε whose value is taken between 0.01 and 0.05 (in the units of total radius). Following the same procedure, Eq.8 becomes as()320ln ln 13N S S N T N b Nb V εε⎡⎤-=---⎢⎥⎣⎦(13)For extended structures of galaxies, Eq.4 gets modi-fied to()()331nT R b nT R εβαεβαε--=+ (14)where α is a constant, R is the radius of a cell in a phase space in which number of particles (galaxies) is N and volume is V . The relation between b and b ε is given by: ()11b b b εαα=+- (15) b ε represents the correlation energy for extended mass particles clustering gravitationally in an expanding uni-verse. The above Eq.10 and Eq.12 take the form respec-tively as;()()3203ln 111bT b S S b b ααα⎡⎤⎢⎥-=-+⎢⎥+-+-⎢⎥⎣⎦1 (16) ()()()120113ln ln 2111b b b S S n b b ααα⎡⎤-⎡⎤⎢⎥⎣⎦-=-++⎢⎥+-+-⎢⎥⎣⎦1 (17)where2R R εεεα⎛⎫⎛⎫=⎪ ⎪⎝⎭⎝⎭(18)If ε = 0, α = 1 the entropy equations for extended mass galaxies are exactly same with that of a system of point mass galaxies approximation. Eq.10, Eq.12, Eq.16and Eq.17 are used here to study the entropy changes inthe cosmological many body problem. Various entropy change results S – S 0 for both the point mass approxima-tion and of extended mass approximation of particles (galaxies) are shown in (Figures 1and2). The resultshave been calculated analytically for different values ofFigure 1. (Color online) Comparison of isothermal entropy changes for non-point and point mass particles (galaxies) for an infinite gravitating system as a function of average relative temperature T and the parameter b . For non-point mass ε = 0.03 and R = 0.06 (left panel), ε = 0.04 and R = 0.04 (right panel).All Rights Reserved.N. Iqbal et al. / Natural Science 3 (2011) 65-68 68Figure 2. (Color online) Comparison of equi-density entropy changes for non-point and point mass particles (galaxies) for an infinite gravitating system as a function of average relative density n and the parameter b. For non-point mass ε= 0.03 and R = 0.04.R (cell size) corresponding to different values of soften-ing parameter ε. We study the variations of entropy changes S – S0with the changing parameter b for differ-ent values of n and T. Some graphical variations for S – S0with b for different values of n = 0, 1, 100 and aver-age temperature T = 1, 10 and 100 and by fixing value of cell size R = 0.04 and 0.06 are shown. The graphical analysis can be repeated for different values of R and by fixing values of εfor different sets like 0.04 and 0.05. From both the figures shown in 1 and 2, the dashed line represents variation for point mass particles and the solid line represents variation for extended (non-point mass) particles (galaxies) clustering together. It has been ob-served that the nature of the variation remains more or less same except with some minor difference.4. RESULTSThe formula for entropy calculated in this paper has provided a convenient way to study the entropy changes in gravitational galaxy clusters in an expanding universe. Gravity changes things that we have witnessed in this research. Clustering of galaxies in an expanding universe, which is like that of a self gravitating gas increases the gases volume which increases the entropy, but it also increases the potential energy and thus decreases the kinetic energy as particles must work against the attrac-tive gravitational field. So we expect expanding gases to cool down, and therefore there is a probability that the entropy has to decrease which gets confirmed from our theoretical calculations as shown in Figures 1 and 2. Entropy has remained an important contributor to our understanding in cosmology. Everything from gravita-tional clustering to supernova are contributors to entropy budget of the universe. A new calculation and study of entropy results given by Eqs.10, 12, 16 and 17 shows that the entropy of the universe decreases first with the clustering rate of the particles and then gradually in-creases as the system attains viral equilibrium. The gravitational entropy in this paper furthermore suggests that the universe is different than scientists had thought.5. ACKNOWLEDGEMENTSWe are thankful to Interuniversity centre for Astronomy and Astro-physics Pune India for providing a warm hospitality and facilities during the course of this work.REFERENCES[1]Voit, G.M. (2005) Tracing cosmic evolution with clus-ters of galaxies. Reviews of Modern Physics, 77, 207- 248.[2]Rief, F. (1965)Fundamentals of statistical and thermalphysics. McGraw-Hill, Tokyo.[3]Spitzer, L. and Saslaw, W.C. (1966) On the evolution ofgalactic nuclei. Astrophysical Journal, 143, 400-420.doi:10.1086/148523[4]Saslaw, W.C. and De Youngs, D.S. (1971) On the equi-partition in galactic nuclei and gravitating systems. As-trophysical Journal, 170, 423-429.doi:10.1086/151229[5]Itoh, M., Inagaki, S. and Saslaw, W.C. (1993) Gravita-tional clustering of galaxies. Astrophysical Journal, 403,476-496.doi:10.1086/172219[6]Hill, T.L. (1956) Statistical mechanics: Principles andstatistical applications. McGraw-Hill, New York.[7]Iqbal, N., Ahmad, F. and Khan, M.S. (2006) Gravita-tional clustering of galaxies in an expanding universe.Journal of Astronomy and Astrophysics, 27, 373-379.doi:10.1007/BF02709363[8]Saslaw, W.C. and Hamilton, A.J.S. (1984) Thermody-namics and galaxy clustering. Astrophysical Journal, 276, 13-25.doi:10.1086/161589[9]Mcquarrie, D.A. and Simon, J.D. (1997) Physical chem-istry: A molecular approach. University Science Books,Sausalito.[10]Ahmad, F, Saslaw, W.C. and Bhat, N.I. (2002) Statisticalmechanics of cosmological many body problem. Astro-physical Journal, 571, 576-584.doi:10.1086/340095[11]Freud, P.G. (1970) Physics: A Contemporary Perspective.Taylor and Francis Group.[12]Khinchin, A.I. (1949) Mathamatical Foundation of statis-tical mechanics. Dover Publications, New York.[13]Frampton, P., Stephen, D.H., Kephar, T.W. and Reeb, D.(2009) Classical Quantum Gravity. 26, 145005.doi:10.1088/0264-9381/26/14/145005All Rights Reserved.。
卫星轨道外推：第一部分(英文批注)
Orbital Propagation: Part I轨道外推：第一部分By Dr. T.S. KelsoWelcome to the Computers and Satellites column of Satellite Times. We are about to embark on an adventure of discovery—an adventure I have been looking forward to for quite some time. I only hope you will enjoy the experience as much as I and want to follow along with each new episode.欢迎来到《卫星时刻》计算机与卫星专栏，我们即将踏上我期待已久的探索之旅。
我谨希望你能和我一同享受这份经历并追随每一段新的旅程。
Along the way, I hope to enlighten you, the reader—whether novice or expert—on the subtleties involved in the theory and practical application of computers to the process of tracking satellites in earth orbit. Whether you simply want to be able to know where to point your TVRO antenna to pick up your favorite television shows, are curious as to where to look to see the Mir space station on a twilight pass, or want to know when you will be able to DX with the space shuttle on the next SAREX mission, we'll cover it all.一路上，我希望无论新手还是专家的每一位读者在卫星地球轨道计算的详细理论和实际应用方面能有所启迪。
探索空间的前沿——比尔·希列尔(1937—2019)
收稿日期：2020年12月20日Received Date: December 20, 2020艾伦·佩恩（伦敦大学学院巴特雷特建筑学院）Alan Penn, Bartlett School of Architecture, University College London, 22 Gordon Street, London WC1H 0QB. E-mail:*************.uk参考文献引用格式：艾伦·佩恩. 探索空间的前沿: 比尔·希列尔(1937-2019) [J]. 城市设计, 2021 (1): 6-13.Penn A. Exploring the frontiers of space: Bill Hillier (1937 - 2019) [J]. Urban Design, 2021 (1): 6-13.比尔·希列尔是位一流科学家和理论学者，于2019年11月5日逝世1（图1）。
他一生都致力于将盎格鲁—撒克逊的实证科学传统延续到建筑学之中。
他揭示了社会如何嵌入我们所建造的房屋以及建成环境的结构之中。
他也揭示了环境的组织构成怎样反过来又影响社会结构，这体现为空间中的行为举止、交通交流使用以及人们交往的模式（图2—图5）。
按照这种方式，他发现了全面揭示社会再生产和社会演变的基本机制，其中社会再生产指社会形态持续存在的时间跨度超越了个人的生命周期，而社会演变则指社会形态以事件的形式不时地迅速变化和创新。
他指出，建筑不只是体现为社会且由社会形成的社会产品，也不简单地作为社会活动发生的被动背景；建筑是积极的生命体，以此不断地建构并再生产社会。
在该体系下，他阐明了建筑物和城市在社会经济的语境之中，有可能繁荣或衰败。
这也辅助人们理解了人类社会的演变。
作为伦敦房地产商的儿子，比尔并不是科班出生的建筑师或科学家。
他在剑桥大学女王学院攻读英语文学学位，也许他本能成为诗人。
高一英语太空生活单选题50题
高一英语太空生活单选题50题1. The first human to walk on the moon was Neil Armstrong in _.A. 1969B. 1979C. 1989D. 1999答案：A。
解析：1969年美国宇航员尼尔·阿姆斯特朗成为第一个在月球上行走的人类，这是非常著名的太空探索历史事件，1979、1989、1999年都不符合这一事实，本题主要考查对这一重要太空探索事件年份的记忆，以及数字在英语中的表达。
2. Yuri Gagarin, the first man in space, was from _.A. RussiaB. AmericaC. ChinaD. Britain答案：A。
解析：尤里·加加林是苏联（ 现在的俄罗斯）的宇航员，他是第一个进入太空的人类。
美国、中国、英国都不是加加林的国籍。
本题考查对太空探索先驱者国籍的了解，以及国家名称的英语单词。
3. Which of the following was an important event in space exploration in 1957?A. The launch of Sputnik 1B. The first space shuttle flightC. The building of the International Space StationD. The first manned mission to Mars答案：A。
解析：1957年苏联发射了斯普特尼克1号，这是太空探索中的一个重要事件。
而太空梭的首次飞行、国际空间站的建造、首次载人火星任务都不是发生在1957年的。
本题考查对1957年这一特定年份太空探索重要事件的记忆，同时涉及到事件名称的英语表达。
4. _ is known as the "father of modern rocketry".A. Konstantin TsiolkovskyB. Albert EinsteinC. Isaac NewtonD. Galileo Galilei答案：A。
太空探索的进程、条件和意义英语作文
太空探索的进程、条件和意义英语作文The Progress, Conditions, and Significance of Space ExplorationIntroductionSpace exploration has always been a topic of great interest to mankind. Over the past few decades, significant progress has been made in this field, thanks to advancements in technology and international collaborations. In this essay, we will discuss the progress, conditions, and the significance of space exploration.ProgressSpace exploration has come a long way since the first satellite, Sputnik, was launched by the Soviet Union in 1957. Since then, various space agencies around the world, including NASA, ESA, and Roscosmos, have sent satellites, probes, and astronauts into space. The Apollo missions, which landed humans on the moon in the late 1960s and early 1970s, remain a significant milestone in space exploration history.In recent years, robotic missions to Mars, such as the Mars rovers Curiosity and Perseverance, have provided valuable insights into the red planet's geology and potential for past life. The International Space Station (ISS), a collaborative projectinvolving multiple countries, has been continuously inhabited since the year 2000, providing a platform for scientific research in microgravity.ConditionsThe conditions of space present unique challenges to exploration. The lack of gravity, extreme temperatures, and exposure to cosmic radiation are just a few of the obstacles that astronauts and spacecraft must overcome. To address these challenges, scientists and engineers have developed advanced technologies, such as space suits, thermal protection systems, and radiation shielding.Another critical condition to consider is the vast distances involved in space exploration. Traveling to planets in our solar system can take months or even years, depending on the speed of the spacecraft and the positions of the planets. To enable faster travel, researchers are exploring new propulsion systems, such as ion engines and nuclear propulsion.SignificanceSpace exploration holds significant importance for humanity. By studying other planets, moons, and asteroids, scientists can gain a better understanding of the origins and evolution of oursolar system. This knowledge can help us better understand Earth and the conditions necessary for life to exist.Furthermore, space exploration has led to the development of numerous technologies that benefit society. Innovations such as GPS, satellite communications, and medical imaging have their roots in space research. Additionally, the pursuit of space exploration inspires the next generation of scientists and engineers to push the boundaries of what is possible.ConclusionIn conclusion, space exploration has made remarkable progress in recent years, thanks to advances in technology and international cooperation. Despite the challenges presented by the harsh conditions of space, researchers continue to push the boundaries of what is possible. The significance of space exploration goes beyond scientific discovery, impacting society through technological advancements and inspiring future generations. As we look towards the future, the prospects for further exploration of our solar system and beyond are truly exciting.。
激光雷达技术研究与应用国际发展态势分析
测量用于跟踪大尺度水的流动的高时间分辨率重力场
微波或激光测距系统
3D-Winds(demo) 测量用于气象预报和污染物传输的对流层风
多普勒激光雷达
（2）行星科学应用 行星科学应用主要聚焦于月球、火星及其他太阳系天体的地质和地形，以及火星大气特性研究。
已经发射的月球轨道车激光雷达主要提供月球表面三维图形，这些信息对于着陆点的选择以及未来
Phoenix Mars
向散射
2007
着陆 后3 个月
2008
Lunar
月球的
激光高
Reconnaissance
全局地
2.7
28
4
70
2
14
2009 2年 在轨
度计
Orbiter
形模型
2.1.1.2 未来 NASA 任务的候选激光雷达仪器 NASA 计划在多个领域使用激光雷达技术，以实现其科学和空间探索目标。这些应用领域可概
本报告以天基激光雷达技术为分析重点，采用定性调研与定量分析相结合的分析方法，对 NASA、ESA 等航天机构的激光雷达项目以及技术进展进行梳理，利用文献计量分析方法对科学研 究论文和专利文献进行分析，全面反映天基激光雷达技术目前的发展态势、应用领域，以及未来的 研发前沿与重点。
1
2 国际激光雷达空间应用任务与科学研究计划
括为以下四个方面：
• 地球科学：提供全球大气和陆地监测的长期在轨仪器；
• 行星科学：提供太阳系天体地质和大气数据的在轨或着陆科学仪器；
• 辅助着陆：提供避险、制导和导航数据的传感器；
• 辅助交会对接：提供飞船方位、距离和靠近速度的传感器。
（1）地球科学应用 国家研究理事会（NRC）在 2007 年发布了名为“地球科学与空间应用：美国未来十年国家需求” 的报告，向 NASA 推荐了未来十年发展的十五项任务。其中，七项任务（表 2-2）是基于激光雷达 技术的，这一事实反映了科学团队对激光雷达在获取全球尺度高分辨率大气数据方面能力的充分信
齐奥尔科夫斯基公式
星际旅行一. 从凡尔纳“超级大炮” 谈起火箭理论地先驱者、俄国科学家齐奥尔科夫斯基(. . ) 有一句名言：“地球是人类地摇篮. 但人类不会永远躺在摇篮里，他们会不断探索新地天体和空间. 人类首先将小心翼翼地穿过大气层，然后再去征服太阳周围地整个空间”. 文档来自于网络搜索迈向星空是一条漫长地征途. 迄今为止，人类在这条征途上走过地路程几乎恰好就是“征服太阳周围地整个空间”，而在这征途上地第一步也正是“穿过大气层”. 文档来自于网络搜索在人类发射地航天器中数量最多地就是那些刚刚“穿过大气层” 地航天器人造地球卫星. 人类迄今发射地人造地球卫星有几千颗，明年地十月四日就是第一颗卫星(前苏联拜克努尔发射场发射) 升空五十周年地纪念日. 除人造地球卫星外，人类还发射过许多其它航天器. 所有这些航天器，都是直接或间接通过火箭发射升空地. 文档来自于网络搜索我们知道，为了克服地球地引力，航天器必须达到很高地速度. 在二十世纪以前地各种技术中，枪炮子弹所达到地速度是最高地，因此在早期地科幻小说中，人们很自然地想到用所谓地“超级大炮” 来发射载人航天器. 其中最著名地是法国科幻小说家凡尔纳(. . ) 发表于一八六六年地小说《从地球到月球》( ). 在这部小说中，凡尔纳让三位宇航员挤在一枚与“神舟号” 飞船地轨道舱差不多大地特制地“炮弹” 中，用一门炮管长达九百英尺(约三百米) 地超级大炮发射到月球上去(不过“炮弹” 没能击中月球，而成为了环绕月球运行地卫星). 文档来自于网络搜索但是凡尔纳虽然有非凡地想象力，却缺乏必要地物理学及生理学知识. 简单地计算表明，他所设想地超级大炮若真地能在三百米长地炮管内把“炮弹” 加速到能够飞向月球地速度即所谓地第二宇宙速度(约为公里秒)，则“炮弹” 在炮管内地平均加速度必须达到米秒以上，这相当于地球表面重力加速度地两万倍以上. 另一方面，脆弱地人体所能承受地最大加速度只有不到地球表面重力加速度地十倍. 这两者地差距无疑是灾难性地. 因此凡尔纳地“炮弹” 虽然制作精良，乘坐起来却一点也不会舒适. 不仅不会舒适，且有性命之虞. 事实上，英勇地宇航员们在“炮弹” 出膛时早就变成了肉饼，“炮弹” 最后有没有击中月球，对他们来说已经不再重要了. 倘若“炮弹” 真地击中月球地话，其着陆方式属于所谓地“硬着陆”，就象陨石撞击地球一样，着陆时地速度差不多就是月球上地第二宇宙速度(约为公里秒)，这样地速度相当于在地球上从比珠穆朗玛峰还高三十倍地山峰上摔到地面时地速度，这无疑是要把肉饼进一步摔成肉酱. 文档来自于网络搜索因此，对于发射航天器(尤其是载人航天器) 来说，很重要地一点就是航天器地加速过程必须发生在一个较长地时间里(减速过程也一样). 但是加速过程持续地时间越长，在加速过程中航天器所飞越地距离也就越大. 以凡尔纳地超级大炮为例，倘若要求炮弹地加速度在人体肌体所能承受地安全范围之内(即小于地球表面重力加速度地十倍)，则“炮弹” 地加速过程必须持续一百秒以上，在这段时间内“炮弹” 地飞行距离约在五百公里以上. “炮弹” 越舒适(即加速度越小)，这段距离就越大. 由于“炮弹” 本身没有动力，因此这段距离必须都在炮管内. 这就是说，凡尔纳超级大炮地炮管起码要有公里长！显然，建造这样规模地大炮是极其困难地，别说凡尔纳时代地技术无法办到，即使在今天也是申请不到经费地. 因此航天器地发射必须采用与凡尔纳大炮完全不同地技术手段. 文档来自于网络搜索火箭就是这样地一种技术手段.二. 齐奥尔科夫斯基公式火箭是一种通过向后喷射物质而前进地飞行器. 从物理学上讲，这种飞行器所利用地是反冲原理，或者说是动量守恒定律. 十九世纪末，齐奥尔科夫斯基对火箭地飞行动力学进行了研究，并于一九零三年莱特兄弟( ) 在同年发明了飞机公开发表了我们现在称之为齐奥尔科夫斯基公式地著名公式(新近发现地一些史料表明，英国皇家军事科学院地科学家早在一八一三年就出于军事目地做过类似研究，但他们地结果没有公开发表). 这一公式地形式非常简单：文档来自于网络搜索()这里与分别为火箭地初始质量及推进过程完成后地末态质量(显然>). 从齐奥尔科夫斯基公式中我们可以看到一个重要地特点，那就是火箭所能达到地速度可以高于喷射物地喷射速度. 这一点之所以重要，是因为它表明我们可以通过较低地喷射速度来达到航天器所需要地高速度，这在技术上要远比直接达到高速度来得容易. 从某种意义上讲，凡尔纳地超级大炮之所以没能成功，正是因为它试图直接达到航天器所需要地高速度. 文档来自于网络搜索但是火箭虽然能够达到比喷射物喷射速度更高地速度，但为此付出地代价却也不小. 因为火箭所要达到地速度越高，其初始质量与推进过程完成后地质量之比就必须越大，从而火箭地有效载荷( 地一部分) 就必须越小. 这是齐奥尔科夫斯基公式地第二个重要特点. 最糟糕地是，齐奥尔科夫斯基公式是一个对数关系式，这是增长极其缓慢地关系式，它地出现表明燃料数量地增加(即地增加) 对速度增加所起地作用非常有限. 这一点极大地限制了火箭地运载效率. 文档来自于网络搜索那么，有没有什么办法可以改善火箭地运载效率呢？齐奥尔科夫斯基提出了多级火箭地设想. 多级火箭地好处，是在每一级地燃料用尽后可以把该级地外壳抛弃，从而减轻下一级所负载地质量. 不过，多级火箭虽然有较高地运载效率，但它在技术上地复杂性也较高. 因此在实际使用时，人们往往在运载效率与技术复杂性之间作折中，三级火箭就是最常见地折中结果. 即便使用多级火箭，为了将几吨地有效载荷送入近地轨道，通常也需要发射质量为几百吨地火箭(比如发射“神舟号” 飞船地长征二号型火箭地发射质量约为四百八十吨，近地轨道地有效载荷则为八吨左右). 这种巨大地消耗，使得航天发射地费用极其高昂. 如果你想到近地轨道上地国际空间站去遨游一下地话，大约要准备两千万美元地费用. 文档来自于网络搜索三. 接近光速在人类目前地火箭技术还是相当初级地. 迄今为止最快地航天器地速度也只有每秒几十公里，这样地速度通常还是借助于太阳或其它行星地引力作用而达到地，并不单纯是火箭地功劳. 比方说一九七六年发射地“太阳神二号” ( ) 探测器在近日点地速度约为公里秒，这一探测器有时被称为是速度最快地航天器. 它地速度就是借助于太阳地引力作用而达到地. 另一方面，在人类迄今发射地航天器中，飞得最远地也不过刚刚飞出冥王星轨道. 用星际空间地标准来衡量，这是很微小地距离. 人类要想走得更远，必须要有更快地航天器. 文档来自于网络搜索在齐奥尔科夫斯基公式中，火箭地速度是没有上限地. 通过提高喷射物地喷射速度，以及增加火箭质量中喷射物所占地比例，火箭原则上可以达到任意高地速度. 但我们知道，物体地运动速度不可能超过光速，这是相对论地基本要求. 因此齐奥尔科夫斯基公式显然不能随意外推，尤其是不能外推到火箭速度接近光速地情形. 那么，有没有一个比齐奥尔科夫斯基公式更普遍地公式，在火箭运动速度接近光速时仍然成立呢？文档来自于网络搜索答案是肯定地. 事实上，这样地公式也很简单：[() ()]这里，表示光速，是双曲正切函数，其它变量地含义与传统地齐奥尔科夫斯基公式相同. 这就是齐奥尔科夫斯基公式在相对论条件下地推广. 对于低速运动地火箭，这一公式会自动退化为齐奥尔科夫斯基公式. 由于双曲正切函数在任何时候都小于，因此由上述公式给出地速度在任何情况下都不会超过光速，从而符合相对论地要求. 文档来自于网络搜索上述公式地一个特例是喷射物地速度等于光速()，即喷射物为光子(或其它无质量粒子)，地情形. 这种火箭常常出现在科幻小说中，通常是以物质与反物质地湮灭作为动力来源. 这是运载效率最高地火箭. 对于这种火箭来说，如果其地质量转化为能量作为动力，它地速度可以达到光速地. 显然，这样地火箭既具有很高地运载效率，又能达到普通火箭望尘莫及地速度，是一种非常诱人地技术. 不过，我们目前地技术距离这种火箭地研制还相差很远. 文档来自于网络搜索四. 飞向深空宇宙地浩瀚是星际旅行家们面临地最基本地事实. 即使能够达到接近光速地速度，飞越恒星际空间所需地时间仍然是极其漫长地. 从地球出发，飞到银河系地中心约需要三万年地时间，飞到仙女座星云( 河外星系) 约需要二百二十万年地时间，而到室女座星系团( 河外星系团) 则需要约六千万年地时间... ... 相对于人类弹指一瞬地短暂生命来说，这些时间显然都太漫长了. 但是幸运地是，所有这些时间都是在静止参照系中测量地. 相对论中有一个著名地时钟延缓效应，它表明运动参照系中地时间流逝会比静止参照系中测量到地慢. 火箭地飞行速度越高，这种时钟延缓效应就越可观，宇航员所感受到地时间流逝也就越缓慢. 考虑到这个因素，宇航员是不是有可能在自己地有生之年，到银河系地中心、仙女座星云、甚至室女座星系团去旅行呢？文档来自于网络搜索答案是肯定地. 我们考虑一个非常简单地情形，即火箭始终处于匀加速过程之中(不用说，这种火箭耗费地能量将是极其惊人地，不过这里我们姑且把技术上地困难抛在一边，只讨论理论上地可能性). 同时，我们把火箭地加速度选为与地球表面地重力加速度一样(这样，宇航员在飞船上感受到地重力环境就与地球表面一样，不会象我们在电视上看到地那样在飞船内随意飘荡)，并且假定火箭在后半程做减速运动(这样，宇航员才能在目地地着陆). 在这样地飞行条件下，如果飞行距离非常大(远远大于一光年)，飞船上地时间流逝与航程之间地关系大致为：文档来自于网络搜索≈ ()这里时间以年为单位，航程则以光年为单位. 这个公式与齐奥尔科夫斯基公式一样，也出现了以增长缓慢著称地对数函数. 只不过，在齐奥尔科夫斯基公式中，对数函数地出现是一件不幸地事情，因为它限制了火箭速度地增加，从而限制了火箭地运载效率；而在现在这个公式中，对数函数地出现却成了一件幸事，因为它延缓了飞船上地时间流逝，从而极大地扩展了宇航员在有生之年可以飞越地距离. 文档来自于网络搜索通过这个公式不难看到，假如旅行地目地地是银河系地中心，即≈ 光年，飞行时间约为二十年. 这就是说，在宇航员看来，仅仅二十年地时间，他就可以到达银河系地中心. 即使算上返航，前后也只要四十年地时间. 这就是相对论地奇妙结论！只不过，当他回到地球时，地球上地日历已经翻过了整整六万年，他地孙子地孙子地孙子... ... (如果有地话) 都早已长眠于地下了. 文档来自于网络搜索同样，我们可以计算出到达仙女座星云所需地时间约为二十九年；到达室女座星系团所需地时间约为三十六年；... ... (现在大家对于对数函数增长之缓慢应该会有一个深刻地印象了吧？). 假如一个宇航员二十岁时坐上火箭出发，如果他可以活到八十岁，那么在他地有生之年(不考虑返航)，他可以到达十万亿光年远地地方. 这个距离已经远远远远地超过了可观测宇宙地范围！唯一地遗憾是，他们只要走得稍远一点，我们就没法分享他们地旅行见闻了. 文档来自于网络搜索因为相对论只保佑他们，不保佑我们.。
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Another possibility for quantizing reductible and/or open gauge theories consists to introduce a set of auxiliary fields as in supersymmetric theories, such as the Wess-Zumino model for which it is only with auxiliary fields that one can obtain a tensor calculus [3], or in topological antisymmetric tensor gauge theories, the so-called BF theories [4]. The introduction of auxiliary fields are needed to close the gauge algebra, and then provides an efficient way to use the usual Faddeev-Popov quantization method [5].
Universit´e d’Oran Es-senia, 31100 Oran, Algeria
February 1, 2008
Abstract
We use a Becchi-Rouet-Stora-Tyutin (BRST) superspace approach to formulate off-shell nilpotent BRST and anti-BRST transformations in four dimensional N =1 supersymmetric Yang-Mills theory. The method is based on the possibility of introducing auxiliary fields through the supersymmetric transformations of the superpartener of the gauge potential associated to a supersymmetric Yang-Mills connection. These fields are required to achieve the off-shell nilpotency of the BRST and anti-BRST operators. We also show how this offshell structure is used to build the BRST and anti–BRST invariant gauge-fixing quantum action.
In the context of superspace formalism, the gauge field, the ghost and anti-ghost fields in gauge theories can be incorporated into a natural gauge superconnection by extending spacetime to a (4, 2)−dimensional superspace [7]. In this framework, the BRST and anti-BRST transformations can be derived by imposing horizontality conditions on the supercurvature associated to a superconnection on a superspace.
∗E-mail: meziane@univ-oran.dz
1
The BV formalism is a very general covariant Lagrangian approach which overcomes the need of closed classical algebra by a suitable construction of BRST operator. The construction is realized by introducing a set of new antifields besides the fields occurring in the theory. The elimination of these antifields at the quantum level via a gauge-fixing procedure leads to the quantum theory in which effective BRST transformations are nilpotent only on-shell.
Let us mention that in the case of supersymmetric theories the corresponding supersymmetric algebra close only modulo equations of motion [8, 9]. So, the appropriate framework to quantize such theories is the BV one. Indeed, in Ref. [10] it has been discussed how to realize the quantization of supersymmetric systems in BV approach.
As shown in [11, 12], a superfield description of the BV quantization method can be realized by simply introducing superfields whose lowest components coincide with the usual fields in the BV formalism. Superfield method has provided a powerful tool for producing supersymmetric field equations for any degree of supersymmetry. In [8, 13], one has also estab-
S0 =
dx4
−1 2g2
trFµν
F
µν
+
−
i 2
trλσµDµ
λ
,
(1)
where (Aµ, λ) is the gauge multiplet, g is the gauge coupling, θ is the instan-
ton
angle,
the
field
strength
2
lished an off-shell superfield formulation of four dimensional N = 1 supersymmetric Yang-Mills theory. Considerably more involved off-shell superfield formulations are also available for N = 2 in terms of harmonic and analytic superspace [14], while the off-shell formulation of N = 4 supersymmetric Yang-Mills theory with non-Abelian gauge group SU(N) is not available in terms of unconstrained fields because it would require the introduction of an infinite set of auxiliary fields [15].
is
Fµν
=
∂µAν −∂ν Aµ+[Aµ, Aν] ,
Fµν
=
1 2
ǫµν
ρσ
F
ρσ
is the dual of F, and Dµ = ∂µ + [Aµ, ]. By construction, the Action (1) is
On the other hand, it is well known that in the superspace formalism one can naturally introduce a set of auxiliary fields that gives rise to the construction of the off-shell BRST invariant quantum action. Indeed, as shown in Ref. [4] for the case of 4D non-Abelian BF theory and Ref. [6] for the case of the simple supergravity where the classical gauge algebra is open [3], the superspace formalism has been used in order to realize the quantization of such theories. It leads to introduce the minimal set of auxiliary fields ensuring the off-shell invariance of the quantum action.