Nearfield_Antenna_Test_Theory
【国家自然科学基金】_混合学习_基金支持热词逐年推荐_【万方软件创新助手】_20140802
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维数减少 结构自适应 组合预测 线性系统 粗糙集理论 粒子群优化算法 粒子群优化法 粒子群优化 粒子群 离散粒子群 社团结构 社会偏好 矿山安全 矿井安全 短期电力负荷 知识网络 相关度 相关反馈 直推式支持向量机(tsvm) 直推式学习 盲源分离 目标轨线迭代可变 监控系统 电力系统 独立成分分析 独立主成分分析 状态观测器 特征波形 特征子空间 演化 滚动轴承 渡阻抗反演 混沌时间序列预测 混合遗传算法 混合聚类法 混合正则化 混合核函数 混合属性 混合学习算法 混合动力公交车 混合分层体系结构 混合像元分解 混合专家(me) 混台参数 液-固挤压 洪水调度 波形内插 正则线性系统 模拟退火 模式分类 模型选择 模型修正 核函数 机械振动
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球面近远场和远近场变换算法
spherical w a v e m o d e expansion theory w h i c h is key to implementing the spherical near-field to far-field
transformation. T h e theory can develop the field in the space w h i c h is built b y the antenna expanding into
球面近场测量能够克服平面和柱面的不足因而得到广泛关注其适用于所有类型的天线能够获得远场全方位辐射特性而基于球面波模式展开理论是实现球面近远场变换的主要内容根据惠更斯原理如果能够获得包围待测天线antennaundertestaut某一封闭面上的电场则可以获得空间中任意一点的电场
第34卷 第 2 期
2019 年 4 月
Abstract
XIE Zhixiang ZHANG Yunhua ZHANG Yurong LI Xin
^School o f Electronic inform ation, Wuhan University, Wuhan 430072, China)
T h important for studying the radiation characteristics of anten
近 远 场 变 换 公 式 ，随 后 进 一 步 推 算 得 到 远 近 场 变 换 的 公 式 ，最 后 将 本 文 算 法 计 算 结 果 与 F E K O 测 量结果 进
行 比 较 ，二 者 吻 合 良 好 ，从 而证 实 了 本 文 两 种 算 法 的 有 效 性 .
关 键 词 球 面 波 ；近 场 ；近 远 场 变 换 ；辐 射 ；加权系数
专业物理英语词汇a
acoustic conductivity 声导率
acoustic diffraction 声衍射
acoustic dispersion 声弥散
acoustic disturbance 声扰动
acoustic electron spin resonance 声电子自旋共振
abundance of elements 元素的丰度
ac bias 交莲压
ac circuit 交羚路
ac galvanometer 交羚疗
ac voltage 交羚压
accelerated motion 加速运动
accelerating chamber 加速室
accelerating electrode 加速电极
accumulated temperature 积温
accumulation 蓄集
accumulation layer 累积层
accumulation point 聚点
accumulation ring 累积环
accumulator 二次电池
accuracy 准确度
accuracy grade 准确度
acoustic gravity wave 声力波
acoustic image 声象
acoustic impedance 声阻抗
acቤተ መጻሕፍቲ ባይዱustic instrument 声学仪器
acoustic interferometer 声波干涉计
acoustic lens 声透镜
acoustic line 声传输线
absolute configuration 绝对组态
遗传算法在模拟电路故障诊断中的应用---优秀毕业论文参考文献可复制黏贴
In order to improve the speed of fault diagnosis, the application in soft fault diagnosis of analog circuits based on sensitivity analysis combined with the genetic algorithm is presented in this paper. We have discussed the sensitivity analysis of analog circuits. Estimate the offset of the component parameters to diagnose the fault of the analog circuits. We convert the diagnosis equation, which is constituted by the incremental test node voltage and the component parameters variation, into the linear programming problem about finding the smallest independent variable based on the hard constraints of the fault diagnosis equation. And the linear programming problem with constraints is converted to the extreme solution without constraints by the penalty function. The genetic algorithm is used to solve the optimal solution. Then, the influence of the control parameters of genetic algorithm is discussed with examples. A new Self-adaptive Genetic Algorithms was proposed and the experiments show that the method has a good efficiency on the soft fault diagnosis of tolerance analog circuits and has a higher speed.
心理学研究方法试卷及答案解析浙江10月自考
浙江省2018年10月高等教育自学考试心理学研究方法试题课程代码：06059一、填空题(每空1分，共10分)1．斯蒂文森的幂定律为：S=__________。
2．非随机取样又称为计划取样或__________。
3．问卷法一般采用五种项目形式，即是否式、等距式、填空式、排列式和__________。
4．经典心理物理方法包括恒定刺激法、平均差误法和__________。
5．相关研究中最常用的指标是__________。
6．标准差和方差是表示__________的指标。
7．信号检测论的理论基础是__________。
8．对策论目前在心理学研究中最常用的方法是__________。
9．冯德是__________学派的创始人。
10．因素分析中的因素荷重是变量与因素之间的__________。
二、单项选择题(在每小题的四个备选答案中，选出一个正确答案，并将正确答案的序号填在题干的括号内。
每小题1分，共8分)1.社会测量的方式有社会测量图、靶式社会图和()。
A.“猜测”技术B.取样技术C.投射技术D.Q技术2.用于分析人际关系的一种技术是()。
A.投射技术B.聚类分析C.Q技术D.因素分析3.等比量表的特点是：()。
A.既无相等单位，又无绝对零B.有绝对零，但无相等单位C.有相等单位，但无绝对零D.既有相等单位，又有绝对零4.置换性随机取样又叫()。
A.非限制性随机取样B.限制性随机取样C.简单随机取样D.计划取样5.拉丁方设计的主要目的是()。
A.省被试B.控制顺序效应C.节省研究费用D.控制个体差异6.潜特征理论的拉希模型只使用()难度参数。
A.一个B.二个1C.三个D.四个7.投射测验用于测量个体的()。
A.个性B.兴趣C.智力水平D.态度8.因素分析的主要方法有主因素分析和()等。
A．判别函数分析B.聚类分析C.主成分分析D.映象分析三、多项选择题(在每小题的五个备选答案中，选出二至五个正确的答案，并将正确答案的序号分别填在题干的括号内，多选、少选、错选均不得分。
球模式展开理论近远场变换及快速算法
球模式展开理论近远场变换及快速算法李南京;李元新;胡楚锋【摘要】基于球模式展开理论的近远场变换是天线球面近场测量系统实现的关键,它将待测天线在空间建立的场展开成球面波函数之和,由于其计算公式复杂,因而计算耗费时间长.该文在实际计算中利用快速傅里叶变换及矩阵的思想可以大幅度提高程序运行速度,节省计算时间.采用该方法对角锥喇叭天线的近远场数据进行仿真验证,结果表明外推远场的结果和理论值吻合良好,说明了该方法在保证计算精度的同时,可缩短计算时间.%The theory of near-field to far-field transformation using spherical-wave expansions is the key to implement the spherical near-field antenna measurement system. It can develop the field in the space which is built by antenna expanding into the sum of spherical wave functions. Because of its complex formula, it will consume a long time to compute. The FFT transformation and the ideas of matrix are put into used in this paper, so the compute speed can be improved and the compute time can be saved. Using this method to testify the near-field data and the far-field data of a horn antenna, the results show that the far-field pattern computed from near-field date and the far-field pattern from theoretical integral equations are compared very well. It is approved that this method can guarantee the calculation precision and shortens the compute time at the same time.【期刊名称】《电子与信息学报》【年(卷),期】2015(037)012【总页数】5页(P3025-3029)【关键词】天线球面近场测量;球模式展开理论;近远场变换;快速算法【作者】李南京;李元新;胡楚锋【作者单位】西北工业大学无人机特种技术重点实验室西安 710065;西北工业大学无人机特种技术重点实验室西安 710065;西北工业大学电子信息学院西安710072;西北工业大学无人机特种技术重点实验室西安 710065【正文语种】中文【中图分类】TN82天线测量按照测试场地通常可划分为：紧缩场测量、远场测量和近场测量［1-3］。
近场测量中双极化探头的极化和通道性能不理想的修正
Without this information, the results of the near-field to far-field transformation will be a combination of the responses of the probe and antenna under test (AUT). When the probe’s pattern is known, one can correct for its contribution and isolate the response of the AUT. Once the AUT’s radiation pattern has been computed, a variety of useful parameters can be extracted (directivity, beam peak direction, phase center location, polarization, etc.).
these antennas have poor cross-polarization levels like the dual log periodic probes discussummary of the probes discussed in this section. TABLE I. COMPARISON OF VARIOUS LINEARLYPOLARIZED PROBES DISCUSSED IN THIS PAPER
Combining Pattern, Polarization and Channel Balance Correction Routines to Improve the Performance of Broad Band, Dual Polarized Probes
语言跨学科研究方法_上海外国语大学中国大学mooc课后章节答案期末考试题库2023年
语言跨学科研究方法_上海外国语大学中国大学mooc课后章节答案期末考试题库2023年1.时频分析有时可说明事件相关电位分析无法说明的问题。
答案:正确2.感觉区辨任务会调用较强的语义搜索与语义记忆的脑区。
答案:错误3.以下不会干扰脑电信号的是？答案:以上皆非4.定性研究主要由选题、文献综述、理论框架、实验和数据分析、结论等要素构成。
答案:错误5.语言学的微观理论视角可以大概分为语音学、音系学、形态学、、句法学、语用学六个方向。
答案:语义学6.控制变量是没有在实验中进行测量，但可能对实验结果产生影响的变量。
答案:错误7.下列哪种数据分析手段必须依赖对特定脑区的先验假设？答案:兴趣区分析8.左侧额下回可能不参与的活动？答案:音位加工9.语言任务的核磁实验设计每个条件下不能只设计单个试次。
答案:正确10.比起正确的句子，语义违反和世界知识违反都引起更大的N400，这说明？答案:相比正确句子的加工，语义或世界知识违反的句子引起了额外的认知过程11.以下哪个研究范式最适合检测阅读加工？答案:注视变化范式12.以下关于最新的神经心理学研究假设的描述，不正确的是？答案:特定脑区和行为的对应关系，在个体间有高度一致性。
13.定性研究的三种主要研究策略是、扎根理论和个案研究。
答案:民族志14.在一个实验中进行多重t-检验，可以帮助研究者控制个体差异。
答案:错误15.研究问题、研究方法和研究结论是科学研究的三个核心要素。
答案:正确16.在注视变化范式中，研究者会给被试呈现一些图片,然后把一个句子录音播放给被试听，并要求被试依据录音去注视图片中的目标物体。
答案:正确17.回视是两个注视点之间眼睛的快速移动。
答案:错误18.事件相关电位（ERP）的认知功能是明确，且独立于实验设计的。
答案:错误19.以下哪个指标不会区分首次注视时间和第二次甚至多次加工时间，却更多关注兴趣区内或者是单个目标上的所有注视时间的总和？答案:总注视时间20.使用启动范式进行汉语研究时，无论语义启动还是句法启动，一般都需要添加一个条件，就是不启动任何一种结构或语义的条件。
量子信息——连续变量篇
Quantum information with continuous variablesSamuel L.BraunsteinComputer Science,University of York,York YO105DD,United KingdomPeter van LoockNational Institute of Informatics(NII),Tokyo101-8430,Japan and Institute of TheoreticalPhysics,Institute of Optics,Information and Photonics(Max-Planck Forschungsgruppe),Universität Erlangen-Nürnberg,D-91058Erlangen,Germany͑Published29June2005͒Quantum information is a rapidly advancing area of interdisciplinary research.It may lead to real-world applications for communication and computation unavailable without the exploitation of quantum properties such as nonorthogonality or entanglement.This article reviews the progress in quantum information based on continuous quantum variables,with emphasis on quantum optical implementations in terms of the quadrature amplitudes of the electromagneticfield.CONTENTSI.Introduction513II.Continuous Variables in Quantum Optics516A.The quadratures of the quantizedfield516B.Phase-space representations518C.Gaussian states519D.Linear optics519E.Nonlinear optics520F.Polarization and spin representations522G.Necessity of phase reference523 III.Continuous-Variable Entanglement523A.Bipartite entanglement5251.Pure states5252.Mixed states and inseparability criteria526B.Multipartite entanglement5291.Discrete variables5292.Genuine multipartite entanglement5303.Separability properties of Gaussian states5304.Generating entanglement5315.Measuring entanglement533C.Bound entanglement534D.Nonlocality5341.Traditional EPR-type approach5352.Phase-space approach5363.Pseudospin approach536E.Verifying entanglement experimentally537 IV.Quantum Communication with Continuous Variables538A.Quantum teleportation5401.Teleportation protocol5412.Teleportation criteria5433.Entanglement swapping546B.Dense coding546rmation:A measure5472.Mutual information5473.Classical communication5474.Classical communication via quantum states5475.Dense coding548C.Quantum error correction550D.Quantum cryptography5501.Entanglement-based versus prepare andmeasure5502.Early ideas and recent progress5513.Absolute theoretical security5524.Verifying experimental security5535.Quantum secret sharing553E.Entanglement distillation554F.Quantum memory555V.Quantum Cloning with Continuous Variables555A.Local universal cloning5551.Beyond no-cloning5552.Universal cloners556B.Local cloning of Gaussian states5571.Fidelity bounds for Gaussian cloners5572.An optical cloning circuit for coherentstates558C.Telecloning559 VI.Quantum Computation with Continuous Variables560A.Universal quantum computation560B.Extension of the Gottesman-Knill theorem563 VII.Experiments with Continuous Quantum Variables565A.Generation of squeezed-state EPR entanglement5651.Broadband entanglement via opticalparametric amplification5652.Kerr effect and linear interference567B.Generation of long-lived atomic entanglement568C.Generation of genuine multipartite entanglement569D.Quantum teleportation of coherent states569E.Experimental dense coding570F.Experimental quantum key distribution571G.Demonstration of a quantum memory effect572 VIII.Concluding Remarks572 Acknowledgments573 References573I.INTRODUCTIONQuantum information is a relatively young branch of physics.One of its goals is to interpret the concepts of quantum physics from an information-theoretic point of view.This may lead to a deeper understanding of quan-REVIEWS OF MODERN PHYSICS,VOLUME77,APRIL20050034-6861/2005/77͑2͒/513͑65͒/$50.00©2005The American Physical Society513tum theory.Conversely,information and computation are intrinsically physical concepts,since they rely on physical systems in which information is stored and by means of which information is processed or transmitted. Hence physical concepts,and at a more fundamental level quantum physical concepts,must be incorporated in a theory of information and computation.Further-more,the exploitation of quantum effects may even prove beneficial for various kinds of information pro-cessing and communication.The most prominent ex-amples of this are quantum computation and quantum key distribution.Quantum computation means in par-ticular cases,in principle,computation faster than any known classical computation.Quantum key distribution makes possible,in principle,unconditionally secure communication as opposed to communication based on classical key distribution.From a conceptual point of view,it is illuminating to consider continuous quantum variables in quantum in-formation theory.This includes the extension of quan-tum communication protocols from discrete to continu-ous variables and hence fromfinite to infinite dimensions.For instance,the original discrete-variable quantum teleportation protocol for qubits and other finite-dimensional systems͑Bennett et al.,1993͒was soon after its publication translated into the continuous-variable setting͑Vaidman,1994͒.The main motivation for dealing with continuous variables in quantum infor-mation,however,originated in a more practical observa-tion:efficient implementation of the essential steps in quantum communication protocols,namely,preparing, unitarily manipulating,and measuring͑entangled͒quan-tum states,is achievable in quantum optics utilizing con-tinuous quadrature amplitudes of the quantized electro-magneticfield.For example,the tools for measuring a quadrature with near-unit efficiency or for displacing an optical mode in phase space are provided by homodyne-detection and feedforward techniques,respectively. Continuous-variable entanglement can be efficiently produced using squeezed light͓in which the squeezing of a quadrature’s quantumfluctuations is due to a non-linear optical interaction͑Walls and Milburn,1994͔͒and linear optics.A valuable feature of quantum optical implementa-tions based upon continuous variables,related to their high efficiency,is their unconditionalness.Quantum re-sources such as entangled states emerge from the non-linear optical interaction of a laser with a crystal͑supple-mented if necessary by some linear optics͒in an unconditional fashion,i.e.,every inverse bandwidth time.This unconditionalness is hard to obtain in discrete-variable qubit-based implementations using single-photon states.In that case,the desired prepara-tion due to the nonlinear optical interaction depends on particular͑coincidence͒measurement results ruling out the unwanted͑in particular,vacuum͒contributions in the outgoing state vector.However,the unconditional-ness of the continuous-variable implementations has its price:it is at the expense of the quality of the entangle-ment of the prepared states.This entanglement and hence any entanglement-based quantum protocol is al-ways imperfect,the degree of imperfection depending on the amount of squeezing of the laser light involved. Good quality and performance require large squeezing which is technologically demanding,but to a certain ex-tent͓about10dB͑Wu et al.,1986͔͒already state of the art.Of course,in continuous-variable protocols that do not rely on entanglement,for instance,coherent-state-based quantum key distribution,these imperfections do not occur.To summarize,in the most commonly used optical ap-proaches,the continuous-variable implementations al-ways work pretty well͑and hence efficiently and uncon-ditionally͒,but never perfectly.Their discrete-variable counterparts only work sometimes͑conditioned upon rare successful events͒,but they succeed,in principle, perfectly.A similar tradeoff occurs when optical quan-tum states are sent through noisy channels͑opticalfi-bers͒,for example,in a realistic quantum key distribu-tion scenario.Subject to losses,the continuous-variable states accumulate noise and emerge at the receiver as contaminated versions of the sender’s input states.The discrete-variable quantum information encoded in single-photon states is reliably conveyed for each photon that is not absorbed during transmission.Due to the recent results of Knill,Laflamme,and Mil-burn͑Knill et al.,2001͒,it is now known that efficient quantum information processing is possible,in principle, solely by means of linear optics.Their scheme is formu-lated in a discrete-variable setting in which the quantum information is encoded in single-photon states.Apart from entangled auxiliary photon states,generated off-line without restriction to linear optics,conditional dy-namics͑feedforward͒is the essential ingredient in mak-ing this approach work.Universal quantum gates such as a controlled-NOT gate can,in principle,be built using this scheme without need of any Kerr-type nonlinear op-tical interaction͑corresponding to an interaction Hamil-tonian quartic in the optical modes’annihilation and creation operators͒.This Kerr-type interaction would be hard to obtain on the level of single photons.However, the off-line generation of the complicated auxiliary states needed in the Knill-Laflamme-Milburn scheme seems impractical too.Similarly,in the continuous-variable setting,when it comes to more advanced quantum information proto-cols,such as universal quantum computation or,in a communication scenario,entanglement distillation,it turns out that tools more sophisticated than mere Gaussian operations are needed.In fact,the Gaussian operations are effectively those described by interaction Hamiltonians at most quadratic in the optical modes’annihilation and creation operators,thus leading to lin-ear input-output relations as in beam-splitter or squeez-ing transformations.Gaussian operations,mapping Gaussian states onto Gaussian states,also include ho-modyne detections and phase-space displacements.In contrast,the non-Gaussian operations required for ad-vanced continuous-variable quantum communication͑in particular,long-distance communication based on en-514S.L.Braunstein and P.van Loock:Quantum information with continuous variables Rev.Mod.Phys.,Vol.77,No.2,April2005tanglement distillation and swapping,quantum memory,and teleportation͒are due either to at least cubic non-linear optical interactions or to conditional transforma-tions depending on non-Gaussian measurements such asphoton counting.It seems that,at this very sophisticatedlevel,the difficulties and requirements of the discrete-and continuous-variable implementations are analogous.In this review,our aim is to highlight the strengths ofthe continuous-variable approaches to quantum infor-mation processing.Therefore we focus on those proto-cols that are based on Gaussian states and their feasiblemanipulation through Gaussian operations.This leads tocontinuous-variable proposals for the implementation ofthe simplest quantum communication protocols,such asquantum teleportation and quantum key distribution,and includes the efficient generation and detection ofcontinuous-variable entanglement.Before dealing with quantum communication andcomputation,in Sec.II,wefirst introduce continuousquantum variables within the framework of quantumoptics.The discussions about the quadratures of quan-tized electromagnetic modes,about phase-space repre-sentations,and about Gaussian states include the nota-tions and conventions that we use throughout thisarticle.We conclude Sec.II with a few remarks on linearand nonlinear optics,on alternative polarization andspin representations,and on the necessity of a phasereference in continuous-variable implementations.Thenotion of entanglement,indispensable in many quantumprotocols,is described in Sec.III in the context of con-tinuous variables.We discuss pure and mixed entangledstates,entanglement between two͑bipartite͒and be-tween many͑multipartite͒parties,and so-called bound ͑undistillable͒entanglement.The generation,measure-ment,and verification͑both theoretical and experimen-tal͒of continuous-variable entanglement are here of par-ticular interest.As for the properties of the continuous-variable entangled states related with theirinseparability,we explain how the nonlocal character ofthese states is revealed.This involves,for instance,vio-lations of Bell-type inequalities imposed by local real-ism.Such violations,however,cannot occur when themeasurements considered are exclusively of continuous-variable type.This is due to the strict positivity of theWigner function of the Gaussian continuous-variable en-tangled states,which allows for a hidden-variable de-scription in terms of the quadrature observables.In Sec.IV,we describe the conceptually and practi-cally most important quantum communication protocols formulated in terms of continuous variables and thus utilizing the continuous-variable͑entangled͒states. These schemes include quantum teleportation and en-tanglement swapping͑teleportation of entanglement͒, quantum͑super͒dense coding,quantum error correc-tion,quantum cryptography,and entanglement distilla-tion.Since quantum teleportation based on nonmaxi-mum continuous-variable entanglement,usingfinitely squeezed two-mode squeezed states,is always imperfect, teleportation criteria are needed both for the theoretical and for the experimental verification.As is known from classical communication,light,propagating at high speed and offering a broad range of different frequen-cies,is an ideal carrier for the transmission of informa-tion.This applies to quantum communication as well. However,light is less suited for the storage of informa-tion.In order to store quantum information,for in-stance,at the intermediate stations in a quantum re-peater,atoms are more appropriate media than light. Significantly,as another motivation to deal with continu-ous variables,a feasible light-atom interface can be built via free-space interaction of light with an atomic en-semble based on the alternative polarization and spin-type variables.No strong cavity QED coupling is needed as with single photons.The concepts of this transfer of quantum information from light to atoms and vice versa, as the essential ingredients of a quantum memory,are discussed in Sec.IV.FSection V is devoted to quantum cloning with con-tinuous variables.One of the most fundamental͑and historically one of thefirst͒“laws”of quantum informa-tion theory is the so-called no-cloning theorem͑Dieks, 1982;Wootters and Zurek,1982͒.It forbids the exact copying of arbitrary quantum states.However,arbitrary quantum states can be copied approximately,and the resemblance͑in mathematical terms,the overlap orfi-delity͒between the clones may attain an optimal value independent of the original states.Such optimal cloning can be accomplished locally by sending the original states͑together with some auxiliary system͒through a local unitary quantum circuit.Optimal cloning of Gauss-ian continuous-variable states appears to be more inter-esting than that of general continuous-variable states, because the latter can be mimicked by a simple coin toss.We describe a non-entanglement-based implemen-tation for the optimal local cloning of Gaussian continuous-variable states.In addition,for Gaussian continuous-variable states,an optical implementation exists of optimal cloning at a distance͑telecloning͒.In this case,the optimality requires entanglement.The cor-responding multiparty entanglement is again producible with nonlinear optics͑squeezed light͒and linear optics ͑beam splitters͒.Quantum computation over continuous variables,dis-cussed in Sec.VI,is a more subtle issue than the in some sense straightforward continuous-variable extensions of quantum communication protocols.Atfirst sight,con-tinuous variables do not appear well suited for the pro-cessing of digital information in a computation.On the other hand,a continuous-variable quantum state having an infinite-dimensional spectrum of eigenstates contains a vast amount of quantum information.Hence it might be promising to adjust the continuous-variable states theoretically to the task of computation͑for instance,by discretization͒and yet to exploit their continuous-variable character experimentally in efficient͑optical͒implementations.We explain in Sec.VI why universal quantum computation over continuous variables re-quires Hamiltonians at least cubic in the position and momentum͑quadrature͒operators.Similarly,any quan-tum circuit that consists exclusively of unitary gates from515S.L.Braunstein and P.van Loock:Quantum information with continuous variables Rev.Mod.Phys.,Vol.77,No.2,April2005the continuous-variable Clifford group can be efficientlysimulated by purely classical means.This is acontinuous-variable extension of the discrete-variableGottesman-Knill theorem in which the Clifford groupelements include gates such as the Hadamard͑in thecontinuous-variable case,Fourier͒transform or the con-trolled NOT͑CNOT͒.The theorem applies,for example,to quantum teleportation which is fully describable by CNOT’s and Hadamard͑or Fourier͒transforms of some eigenstates supplemented by measurements in thateigenbasis and spin or phaseflip operations͑or phase-space displacements͒.Before some concluding remarks in Sec.VIII,wepresent some of the experimental approaches to squeez-ing of light and squeezed-state entanglement generationin Sec.VII.A.Both quadratic and quartic optical nonlin-earities are suitable for this,namely,parametric downconversion and the Kerr effect,respectively.Quantumteleportation experiments that have been performed al-ready based on continuous-variable squeezed-state en-tanglement are described in Sec.VII.D.In Sec.VII,wefurther discuss experiments with long-lived atomic en-tanglement,with genuine multipartite entanglement ofoptical modes,experimental dense coding,experimentalquantum key distribution,and the demonstration of aquantum memory effect.II.CONTINUOUS VARIABLES IN QUANTUM OPTICSFor the transition from classical to quantum mechan-ics,the position and momentum observables of the par-ticles turn into noncommuting Hermitian operators inthe Hamiltonian.In quantum optics,the quantized elec-tromagnetic modes correspond to quantum harmonicoscillators.The modes’quadratures play the roles of theoscillators’position and momentum operators obeyingan analogous Heisenberg uncertainty relation.A.The quadratures of the quantizedfieldFrom the Hamiltonian of a quantum harmonic oscil-lator expressed in terms of͑dimensionless͒creation and annihilation operators and representing a single mode k, Hˆk=បk͑aˆk†aˆk+12͒,we obtain the well-known form writ-ten in terms of“position”and“momentum”operators ͑unit mass͒,Hˆk=12͑pˆk2+k2xˆk2͒,͑1͒withaˆk=1ͱ2បk͑k xˆk+ipˆk͒,͑2͒aˆk†=1ͱ2បk͑k xˆk−ipˆk͒,͑3͒or,conversely,xˆk=ͱប2k͑aˆk+aˆk†͒,͑4͒pˆk=−iͱបk2͑aˆk−aˆk†͒.͑5͒Here,we have used the well-known commutation rela-tion for position and momentum,͓xˆk,pˆkЈ͔=iប␦kkЈ,͑6͒which is consistent with the bosonic commutation rela-tions͓aˆk,aˆkЈ†͔=␦kkЈ,͓aˆk,aˆkЈ͔=0.In Eq.͑2͒,we see that up to normalization factors the position and the momentum are the real and imaginary parts of the annihilation op-erator.Let us now define the dimensionless pair of con-jugate variables,Xˆkϵͱk2បxˆk=Re aˆk,Pˆkϵ1ͱ2បk pˆk=Im aˆk.͑7͒Their commutation relation is then͓Xˆk,PˆkЈ͔=i2␦kkЈ.͑8͒In other words,the dimensionless position and momen-tum operators,Xˆk and Pˆk,are defined as if we setប=1/2.These operators represent the quadratures of a single mode k,in classical terms corresponding to the real and imaginary parts of the oscillator’s complex am-plitude.In the following,by using͑Xˆ,Pˆ͒or equivalently ͑xˆ,pˆ͒,we shall always refer to these dimensionless quadratures as playing the roles of position and momen-tum.Hence͑xˆ,pˆ͒will also stand for a conjugate pair of dimensionless quadratures.The Heisenberg uncertainty relation,expressed in terms of the variances of two arbitrary noncommuting observables Aˆand Bˆfor an arbitrary given quantum state,͗͑⌬Aˆ͒2͘ϵŠ͑Aˆ−͗Aˆ͒͘2‹=͗Aˆ2͘−͗Aˆ͘2,͗͑⌬Bˆ͒2͘ϵŠ͑Bˆ−͗Bˆ͒͘2‹=͗Bˆ2͘−͗Bˆ͘2,͑9͒becomes͗͑⌬Aˆ͒2͗͑͘⌬Bˆ͒2͘ജ14͉͓͗Aˆ,Bˆ͔͉͘2.͑10͒Inserting Eq.͑8͒into Eq.͑10͒yields the uncertainty re-lation for a pair of conjugate quadrature observables of a single mode k,xˆk=͑aˆk+aˆk†͒/2,pˆk=͑aˆk−aˆk†͒/2i,͑11͒namely,͗͑⌬xˆk͒2͗͑͘⌬pˆk͒2͘ജ14͉͓͗xˆk,pˆk͔͉͘2=116.͑12͒Thus,in our units,the quadrature variance for a vacuum or coherent state of a single mode is1/4.Let us further516S.L.Braunstein and P.van Loock:Quantum information with continuous variables Rev.Mod.Phys.,Vol.77,No.2,April2005illuminate the meaning of the quadratures by looking at a single frequency mode of the electric field ͑for a single polarization ͒,E ˆk ͑r ,t ͒=E 0͓a ˆk ei ͑k ·r −k t ͒+a ˆk †e −i ͑k ·r −k t ͔͒.͑13͒The constant E 0contains all the dimensional prefactors.By using Eq.͑11͒,we can rewrite the mode asE ˆk ͑r ,t ͒=2E 0͓x ˆk cos ͑k t −k ·r ͒+pˆk sin ͑k t −k ·r ͔͒.͑14͒Clearly,the position and momentum operators xˆk and p ˆk represent the in-phase and out-of-phase components of the electric-field amplitude of the single mode k with respect to a ͑classical ͒reference wave ϰcos ͑k t −k ·r ͒.The choice of the phase of this wave is arbitrary,of course,and a more general reference wave would lead us to the single-mode descriptionE ˆk ͑r ,t ͒=2E 0͓x ˆk ͑⌰͒cos ͑k t −k ·r −⌰͒+pˆk ͑⌰͒sin ͑k t −k ·r −⌰͔͒,͑15͒with the more general quadraturesxˆk ͑⌰͒=͑a ˆk e −i ⌰+a ˆk †e +i ⌰͒/2,͑16͒p ˆk ͑⌰͒=͑a ˆk e −i ⌰−a ˆk †e +i ⌰͒/2i .͑17͒These new quadratures can be obtained from x ˆk and p ˆk via the rotationͩx ˆk ͑⌰͒pˆk ͑⌰͒ͪ=ͩcos ⌰sin ⌰−sin ⌰cos ⌰ͪͩxˆk pˆk ͪ.͑18͒Since this is a unitary transformation,we again end upwith a pair of conjugate observables fulfilling the com-mutation relation ͑8͒.Furthermore,because pˆk ͑⌰͒=x ˆk ͑⌰+/2͒,the whole continuum of quadratures is cov-ered by x ˆk ͑⌰͒with ⌰͓0,͒.This continuum of observ-ables is indeed measurable by relatively simple means.Such a so-called homodyne detection works as follows.A photodetector measuring an electromagnetic mode converts the photons into electrons and hence into an electric current,called the photocurrent i ˆ.It is therefore sensible to assume i ˆϰn ˆ=a ˆ†a ˆor i ˆ=qaˆ†a ˆwhere q is a con-stant ͑Paul,1995͒.In order to detect a quadrature of themode aˆ,the mode must be combined with an intense local oscillator at a 50:50beam splitter.The local oscil-lator is assumed to be in a coherent state with large photon number,͉␣LO ͘.It is therefore reasonable to de-scribe this oscillator by a classical complex amplitude␣LO rather than by an annihilation operator aˆLO .The two output modes of the beam splitter,͑aˆLO +a ˆ͒/ͱ2and ͑a ˆLO −a ˆ͒/ͱ2͑see Sec.II.D ͒,may then be approximated byaˆ1=͑␣LO +a ˆ͒/ͱ2,aˆ2=͑␣LO −a ˆ͒/ͱ2.͑19͒This yields the photocurrentsi ˆ1=qa ˆ1†aˆ1=q ͑␣LO *+a ˆ†͒͑␣LO +a ˆ͒/2,i ˆ2=qa ˆ2†aˆ2=q ͑␣LO *−a ˆ†͒͑␣LO −a ˆ͒/2.͑20͒The actual quantity to be measured will be the differ-ence photocurrent␦i ˆϵi ˆ1−i ˆ2=q ͑␣LO *aˆ+␣LO a ˆ†͒.͑21͒By introducing the phase ⌰of the local oscillator,␣LO=͉␣LO ͉exp ͑i ⌰͒,we recognize that the quadrature observ-able xˆ͑⌰͒from Eq.͑16͒is measured ͑without mode index k ͒.Now adjustment of the local oscillator’s phase ⌰͓0,͔enables us to detect any quadrature from thewhole continuum of quadratures xˆ͑⌰͒.A possible way to realize quantum tomography ͑Leonhardt,1997͒,i.e.,the reconstruction of the mode’s quantum state given by its Wigner function,relies on this measurement method,called ͑balanced ͒homodyne detection .A broadband rather than a single-mode description of homodyne de-tection can be found in the work of Braunstein and Crouch ͑1991͒,who also investigate the influence of a quantized local oscillator.We have now seen that it is not too hard to measure the quadratures of an electromagnetic mode.Unitary transformations such as quadrature displacements ͑phase-space displacements ͒can also be relatively easily performed via the so-called feedforward technique,as opposed to,for example,photon number displacements.This simplicity and the high efficiency when measuring and manipulating continuous quadratures are the main reasons why continuous-variable schemes appear more attractive than those based on discrete variables such as the photon number.In the following,we shall refer mainly to the conju-gate pair of quadratures xˆk and p ˆk ͑position and momen-tum,i.e.,⌰=0and ⌰=/2͒.In terms of these quadra-tures,the number operator becomesn ˆk =a ˆk †a ˆk =x ˆk 2+p ˆk 2−12,͑22͒using Eq.͑8͒.Let us finally review some useful formulas for the single-mode quadrature eigenstates,xˆ͉x ͘=x ͉x ͘,pˆ͉p ͘=p ͉p ͘,͑23͒where we have now dropped the mode index k .They are orthogonal,͗x ͉x Ј͘=␦͑x −x Ј͒,͗p ͉p Ј͘=␦͑p −p Ј͒,͑24͒and complete,͵−ϱϱ͉x ͗͘x ͉dx =1,͵−ϱϱ͉p ͗͘p ͉dp =1.͑25͒Just as for position and momentum eigenstates,the quadrature eigenstates are mutually related to each other by a Fourier transformation,͉x ͘=1ͱ͵−ϱϱe −2ixp ͉p ͘dp ,͑26͒517S.L.Braunstein and P .van Loock:Quantum information with continuous variablesRev.Mod.Phys.,Vol.77,No.2,April 2005͉p͘=1ͱ͵−ϱϱe+2ixp͉x͘dx.͑27͒Despite being unphysical and not square integrable,the quadrature eigenstates can be very useful in calculations involving the wave functions͑x͒=͗x͉͘,etc.,and inidealized quantum communication protocols based on continuous variables.For instance,a vacuum state infi-nitely squeezed in position may be expressed by a zero-position eigenstate͉x=0͘=͉͐p͘dp/ͱ.The physical,fi-nitely squeezed states are characterized by the quadrature probability distributions͉͑x͉͒2,etc.,ofwhich the widths correspond to the quadrature uncer-tainties.B.Phase-space representationsThe Wigner function is particularly suitable as a “quantum phase-space distribution”for describing the effects on the quadrature observables that may arise from quantum theory and classical statistics.It behaves partly as a classical probability distribution,thus en-abling us to calculate measurable quantities such as mean values and variances of the quadratures in a classical-like fashion.On the other hand,in contrast to a classical probability distribution,the Wigner function can become negative.The Wigner function was originally proposed by Wigner in his1932paper“On the quantum correction for thermodynamic equilibrium”͑Wigner,1932͒.There, he gave an expression for the Wigner function in terms of the position basis which reads͑with x and p being a dimensionless pair of quadratures in our units withប=1/2as introduced in the previous section;Wigner, 1932͒W͑x,p͒=2͵dye+4iyp͗x−y͉ˆ͉x+y͘.͑28͒Here and throughout,unless otherwise specified,the in-tegration will be over the entire space of the integration variable͑i.e.,here the integration goes from−ϱtoϱ͒. We gave Wigner’s original formula for only one mode or one particle͓Wigner’s͑1932͒original equation was in N-particle form͔because it simplifies the understanding of the concept behind the Wigner function approach. The extension to N modes is straightforward.Why does W͑x,p͒resemble a classical-like probability distribution?The most important attributes that explain this are the proper normalization,͵W͑␣͒d2␣=1,͑29͒the property of yielding the correct marginal distribu-tions,͵W͑x,p͒dx=͗p͉ˆ͉p͘,͵W͑x,p͒dp=͗x͉ˆ͉x͘,͑30͒and the equivalence to a probability distribution in clas-sical averaging when mean values of a certain class of operators Aˆin a quantum stateˆare to be calculated,͗Aˆ͘=Tr͑ˆAˆ͒=͵W͑␣͒A͑␣͒d2␣,͑31͒with a function A͑␣͒related to the operator Aˆ.The measure of integration is in our case d2␣=d͑Re␣͒d͑Im␣͒=dxdp with W͑␣=x+ip͒ϵW͑x,p͒,and we shall use d2␣and dxdp interchangeably.The opera-tor Aˆrepresents a particular class of functions of aˆand aˆ†or xˆand pˆ.The marginal distribution for p,͗p͉ˆ͉p͘,is obtained by changing the integration variables͑x−y =u,x+y=v͒and using Eq.͑26͒,that for x,͗x͉ˆ͉x͘,by using͐exp͑+4iyp͒dp=͑/2͒␦͑y͒.The normalization of the Wigner function then follows from Tr͑ˆ͒=1.For any symmetrized operator͑Leonhardt,1997͒,the so-called Weyl correspondence͑Weyl,1950͒,Tr͓ˆS͑xˆn pˆm͔͒=͵W͑x,p͒x n p m dxdp,͑32͒provides a rule for calculating quantum-mechanical ex-pectation values in a classical-like fashion according to Eq.͑31͒.Here,S͑xˆn pˆm͒indicates symmetrization.For example,S͑xˆ2pˆ͒=͑xˆ2pˆ+xˆpˆxˆ+pˆxˆ2͒/3corresponds to x2p ͑Leonhardt,1997͒.Such a classical-like formulation of quantum optics in terms of quasiprobability distributions is not unique.In fact,there is a whole family of distributions P͑␣,s͒of which each member corresponds to a particular value of a real parameter s,P͑␣,s͒=12͵͑,s͒exp͑i␣*+i*␣͒d2,͑33͒with the s-parametrized characteristic functions ͑,s͒=Tr͓ˆexp͑−iaˆ†−i*aˆ͔͒exp͑s͉͉2/2͒.͑34͒The mean values of operators normally and antinor-mally ordered in aˆand aˆ†may be calculated via the so-called P function͑s=1͒and Q function͑s=−1͒,re-spectively.The Wigner function͑s=0͒and its character-istic function͑,0͒are perfectly suited to provide ex-pectation values of quantities symmetric in aˆand aˆ†such as the quadratures.Hence the Wigner function,though not always positive definite,appears to be a good com-promise in describing quantum states in terms of quan-tum phase-space variables such as single-mode quadra-tures.We may formulate various quantum states relevant to continuous-variable quantum communica-tion by means of the Wigner representation.These par-ticular quantum states exhibit extremely nonclassical features such as entanglement and nonlocality.Yet their Wigner functions are positive definite,and thus belong to the class of Gaussian states.518S.L.Braunstein and P.van Loock:Quantum information with continuous variables Rev.Mod.Phys.,Vol.77,No.2,April2005。
天线测量方法综述
紧缩场测量，可以缩短室内远场测量的范围， 采用一个或两个反射面在相对短的距离内产生测试 所需要的平面波，图２为两个反射面的室内紧缩场 天线测试系统的示意图，包括ＲＦ部分（射频源， 接收机，混频器，本振源等），工作站及暗室内的 源天线，两个反射面，待测天线，转台等。
１９６
第九届全国雷达年会学术论文集
津Ｇａｌｔｒｏｎｉｃ公司生产的手机天线虽然是低频，低增 益的通讯天线，但他们希望更多了解手机附近的场 分布，有助于研发工程师发现问题、解决问题，因 此采用了球面近场测试系统。还有很多例子这里就 不一一列举晦７Ｉ。
４结论
选择一个合适的测试方法需对各种因素进行折 衷考虑，因为每种测试方法都有它的优缺点，远场 测量适用于低增益、低频天线的测量，如保密性等 因素要求高，可采用室内远场测量，若测试距离太 大可用紧缩场测量；近场测量适用于高增益、高 频、口径全息测量【５】等情况，不同的波束类型可选 用平面、柱面、球面不同的测试方法。当然根据实 际情况也可将各种测试方法结合使用。对于特殊的 结构甚至可由专门提供天线测试方案的公司进行量 身定做。
天线测量方法
天线测量方法综述
曲晓云１，余新芸２，邵江速３
１．海雷迪埃电子有限公司，上海，２０００７２ ２．俊英科技（上海）有限公司
３．南京电子技术研究所，南京，２１００１３
擅要。选择一个合适的测量方法对于精确测量和正确表征天线特性是很重要的。对于给定的待测天 线（ＡＵＴ）一个天线工程师该如何去选择最佳的测试方法，这是本文要阐述的重点，包括近场测量和远场 测量方法，不同扫描类型的测试系统，以及测量方法的选择与天线口径，频率，增益，波束宽度，极化， 旁瓣电平的关系。
Waves1_Field Theory(波动理论)
标量场：
等值面：
u u x, y , z u x, y, z const
(1.1)(1ຫໍສະໝຸດ 2)同理有等值线，等高线。 性质：等值面充满了标量场所在空间而且互不相交。
1.1.2 矢量场及其矢量线
如果定义场的物理量是矢量，就称这个场为矢量场。
例如：力场，速度场，电场，磁场等等。
由最后一个方程得： x y z 16
2 2
2
R2
这就是要求的矢量管方程。
数量又分：
纯标量 — 与坐标方向的变化无关的数量。 例如：温度，质量。
赝标量 — 与坐标方向的变化相关的数量。
例如：体积，角度，面积……等都是赝标量。 以体积为例，
a c
V a b c bx
b
Heinrich Rudolf Hertz (Feb. 22, 1857 – Jan. 1, 1894) was a German physicist who clarified and expanded the electromagnetic theory of light that had been put forth by Maxwell. He was the first to satisfactorily demonstrate the existence of electromagnetic waves by building an apparatus to produce and detect VHF or UHF radio waves.
Course Outline Calendar
《波动理论》教学大纲 《波动理论》教学日历
Course Goal
通过本课程教学使学生掌握连续介质中声波，电磁波的 基本性质及其运动规律以及量子力学的基本知识。具有分析， 处理和解决声波，电磁波以及量子力学基本问题的能力。为 今后的学习和工作打下基础。
coalescent theory名词解释(一)
coalescent theory名词解释(一)Coalescent theory名词解释1. Coalescent theoryCoalescent theory是基因演化中的一个重要理论模型，其研究的是种群中个体之间的共同祖先关系。
该理论模型通过回溯推断，解释了如何从现有的物种或个体群，推断出它们的共同祖先。
2. AlleleAllele指的是一个基因座上的一个或多个变种。
在基因组的不同位置上，我们可以有不同的allele。
例如，人类眼睛颜色的基因座上可以有褐色allele和蓝色allele。
3. Gene treeGene tree是一种表示基因演化过程中不同个体之间关系的树状图。
在coalescent theory中，gene tree用于描述共同祖先与后代之间的关系。
例如，假设我们研究某个人群中的多个基因座，我们可以通过分析这些基因座的变异情况，重建出一个表示个体之间共同祖先关系的gene tree。
4. Coalescent eventCoalescent event指的是两个或多个个体的基因共同祖先的合并事件。
在coalescent theory中，coalescent event是基因演化过程中的重要事件，它代表了共同祖先关系的形成。
例如，假设我们研究了一个人群的基因演化，我们可以通过观察基因座的变异情况，确定共同祖先在不同个体之间合并的coalescent event。
5. Neutral mutationNeutral mutation是指发生在基因组中没有显著影响个体适应度的突变。
在coalescent theory中，假设大多数的突变是中性的，对个体的适应度没有显著影响。
例如，人类基因组中的一些基因座上的突变，如常见的单核苷酸多态性(SNP)，很可能是中性突变。
6. Effective population sizeEffective population size是指一个理想化的概念，用于估计一个群体中的基因演化过程。
物理专业词汇英语翻译
物理专业词汇英语翻译物理专业词汇英语翻译1/8 fluctuation 1/8 起伏1/f noise 1/f 噪声1/n expansion 1/n 展开3k cosmic blackbody radiation 3k 宇宙黑体辐射4 counter 4 计数器a battery a 电池组a posteriori probability 后验概率a prioriprobability 先验概率a15 structure a15结构abbe coefficient阿贝数abbe invariant 阿贝不变量abbe number 阿贝数abbe prism 阿贝棱镜abberefractometer 阿贝折射计abbe sinecondition 阿贝正弦条件abel theorem 阿贝尔定理abelian group 可换群abelian integral阿贝尔积分aberage life 平均寿命aberration 象差aberrationconstant 光行差常数aberration oflight 光行差aberrationalellipse 光行差椭圆ablation 烧蚀abm state abm 态abnormal 反常的abnormal cathode fall 反常阴极势降abnormal crystallization 异常晶化abnormal dispersion 异常色散abnormal glow 反常辉光放电abnormal grain growth 反常晶粒生长abnormal liquid反常液体abnormalreflection 异常反射abnormal series反常系abrasion 磨损abrasion test 磨损试验abrasives 研磨材料abrikosov'sstructure of fluxlines 阿布里科蓑磁通线结构absence ofgravity 失重absolute 绝对的absoluteacceleration 绝对加速度absolute angularmomentum 绝对角动量3absolute atomicweight 原子的绝对重量absolute blackbody 绝对黑体absoluteconfiguration 绝对组态absolute counting 绝对计数absolute electrometer 绝对静电计absolute electrostatic system 绝对静电制absolute error 绝对误差absolute geopotential 绝对位势absolute humidity 绝对湿度absolute index ofrefraction 绝对折射率absoluteinstability 绝对不稳定性absolutemagnitude 绝对星等absolutemeasurement 绝对测量absolute motion绝对运动absolute ohm 绝对欧姆absolute orbit 绝对轨道absolutepermeability 绝对磁导率absolutepermittivity 绝对电容率absolutepressure 绝对压力absolute rest 绝对静止absolute restframe 绝对静止系absolute rotation绝对转动absolute scale绝对度标absolute space绝对空间absolute stability 绝对稳定absolute system of units 绝对单位制absolute temperature 绝对温度absolute temperature scale 绝对温标absolute thermometer 绝对温度表absolute time 绝对时空间absolute topography 绝对形势absolute unit 绝对单位absolute vacuumgage 绝对真空计absolute velocity绝对速度absoluteviscosity 绝对粘度absolute vorticity绝对涡度absolute weight绝对重量absolute zero 绝对零度absolute zeropoint 绝对零度absorb 吸收absorbed dose吸收剂量absorbent 吸收剂absorber 吸收体absorbingmedium 吸收媒质4absorptiometer吸收计absorption 吸收absorption band吸收带absorptioncoefficient 吸收系数absorption cross section 吸收截面absorption curve 吸收曲线absorption edge 吸收端absorption equilibrium 吸收平衡absorption factor 吸收因子absorption filter 吸收滤光器absorption hygrometer 吸收湿度表absorption index吸收指数absorption jump吸收跃迁absorption limit吸收端absorption line吸收线absorptionmethod 吸收法absorptionmodel 吸收模型absorption ofsound 声的吸收absorptionspectrometer 吸收光谱仪absorptionspectroscopy 吸收光谱学absorptionspectrum 吸收光谱absorption test吸收试验absorptive 吸收的absorptive power吸收本领absorptivity 吸收本领abstract algebra抽象代数abstract group抽象群abstract space抽象空间abstraction 抽象abundance of elements 元素的丰度ac bias 交莲压ac circuit 交羚路ac galvanometer 交羚疗ac voltage 交羚压accelerated motion 加速运动accelerating chamber 加速室accelerating electrode 加速电极accelerating field 加速场accelerating gap加速隙缝acceleratingperiod 加速周期accelerating slit加速隙缝accelerating tube加速管acceleratingvoltage 加速电压acceleration 加速度5accelerationcavity 加速共振腔acceleration gap加速隙acceleration ofgravity 重力加速度accelerator 加速器accelerometer加速计acceptance 肯定acceptor 受主acceptor center受中心acceptorimpurity 受钟质acceptor level 受周级access 选取access speed 选取速度access time 选取时间accessibility 可达性accessible point 可达点accessories 附件accidental coincidence 偶然符合accidental degeneracy 偶然退化accidental error 偶然误差accidentalreflection 偶然反射acclimation 气候驯化acclimatization气候驯化acclimazation 气候驯化accommodation第accommodationcoefficient 适应系数accommodationof the eye 眼的第accord 和音accreting blackhole model 吸积黑洞模型accretion 吸积accretion disk 吸积盘accumulateddose 累积剂量accumulatederror 累积误差accumulatedtemperature 积温accumulation 蓄集accumulationlayer 累积层accumulationpoint 聚点accumulation ring 累积环accumulator 二次电池accuracy 准确度accuracy grade 准确度accuracy of measurement 测量精确度accuracy of readings 读数准确度accuracy rating 准确度acetone 丙酮6 achondrite 无球粒陨石achromat 消色差透镜achromatic 消色的achromatic color无彩色achromaticcondition 消色差achromatic lens消色差透镜achromaticprism 消色差棱镜achromaticquarter waveprism 四分之一波长消色棱镜achromaticsensation 无色感觉achromaticstimulus 无色剌激achromatism 消色差acid 酸acnod 孤点acoumeter 测听计acount 计算acoustic 声的acousticabsorptioncoefficient 吸声系数acoustic absorptivity 吸声系数acoustic admittance 声导纳acoustic analysis 声分析acoustic conductivity 声导率acoustic diffraction 声衍射acoustic dispersion 声弥散acousticdisturbance 声扰动acoustic electronspin resonance声电子自旋共振acousticemission 声发射acoustic far field远程声场acoustic field 声场acoustic filter 滤声器acousticfraunhofer field夫琅和费声场acousticfrequency 音频acoustic fresnelfield 非涅耳声场acoustic gravitywave 声力波acoustic image声象acousticimpedance 声阻抗acousticinstrument 声学仪器acousticinterferometer声波干涉计acoustic lens 声透镜acoustic line 声传输线acoustic load 声负载acoustic material 吸音材料acoustic measurement 声学量度acoustic microscope 超声显微镜acoustic mode 声学模7acoustic near field 近程声场acoustic nuclear magnetic resonance 声核磁共振acoustic ohm 声欧姆acousticparamagneticresonance 声顺磁共振acoustic power声功率acousticpressure 声压acoustic radiator声辐射体acousticreactance 声抗acousticresistance 声阻acousticresonance 声共振acousticresonator 声共振器acoustic shadow声影acoustic signal声信号acousticsounding 声学探测acousticstreaming 声风acoustictransducer 声能转换器acoustic transformer 声变换器acoustic velocity 声速acoustic wave 声波acoustic wind 声风acoustical 声的acoustical holography 声全息学acoustical spectroscopy 声谱学acoustically induced birefringence 声诱发双折射acoustics 声学acoustimeter 声强计acoustodynamic声动力学的acoustoelectricamplification 声电放大acoustoelectriceffect 声电效应acoustoelectroninteraction 声电子相互酌acoustoelectronics 声电子学acoustomagnetoelectric effect 声磁电效应acoustoopticeffect 光声效应acoustooptical声光的acoustoopticalmodulator 声光灯器acoustooptical qswitch 声光q 开关acoustoopticalradiospectrometer 声光射电光谱仪acoustooptics声光学acre 英亩acrobatic metal 特技的金属acryl resin 丙烯酸尸actinic 有光化性的actinic photometer 光化光度计actinic rays 光化射线8actinic value of light 光化度actinides 锕系actinism 光化酌actinium 锕actiniumemanation 锕射气actinium series锕系actinograph 日射仪actinoid nuclei锕系元素核actinometer 日射表actinometry 辐射测量;光能强度测定actinomorphy 辐射对称性actinon 锕射气action 酌action at adistance 超距酌action centre ofthe atmosphere大气活动中心action integral酌积分action principle酌原理action spectrum酌谱action throughmedium 媒递酌action variable酌变量activated 激化了的activated adsorption 活性吸附activated atom 激活原子activated molecule 激活分子activating agent 活化剂activation 活化activation analysis 放射化分析activation cross section 放射化截面activation energy 激活能activationmethod 激活法activator 活化剂active 活性的active carbon 活性炭active current 有效电流active front 活跃锋active galacticnucleus 活动星系核active galaxy 活动星系active hydrogen活性氢active laserelement 激活激光元件active laserspectroscopy 活性激光光谱学active lasersubstance 激活物质active lattice 放射性栅格active locking 受迫模同步active material放射材料9active network 有源网络active oxygen 活性氧active power 有效功率active product 放射性产物active prominence 活动日珥active q switching 激活q 开关active sun 活动太阳active volcano 活火山activity 放射性activitycoefficient 活度系数activity unit 放射性单位actual 真实的actual load 有效的acumulativetemperature 积温acute 尖锐acute angle 锐角acute angled 锐角的acute angledtriangle 锐角三角形acute triangle 锐角三角形acuteness 锐度acyclic 非循环的ada ada 语言adamantineluster 金刚光泽adaptability 适应性adaptation 适应adaptive antenna自适应天线adaptive optics自适应光学adaptometer 适应测量计adatom 吸附原子add 加add circuit 加法电路addend 加数adder 加法器adding element 求和器addition 加法additional 加法的additional code 补码additional heating 附加加热additional mass 附加质量additive 加法的additive group加法群additive method加色法additive property加和性additive theoryof numbers 加性数论10additivity 加和性address 地址address part 地址部分address register地址寄存器adenosinetriphosphate 三磷酸腺苷adequate 适合的adhere 粘着adherence 附着adhesion 附着adhesive force附着力adhesives 粘接剂adiabat 绝热线adiabatic 绝热的adiabaticapproximation绝热近似adiabaticatmosphere 绝热大气adiabatic calorimeter 绝热式量热器adiabatic change 绝热变化adiabatic compression 绝热压缩adiabatic cooling 绝热冷却adiabatic curve 绝热线adiabatic demagnetization 绝热退磁adiabatic equilibrium 绝热平衡adiabaticexpansion 绝热膨胀adiabaticexponent 绝热指数adiabatic freeexpansion 绝热自由膨胀adiabatic heating绝热增温adiabatichypothesis 绝热假说adiabatic index绝热指数adiabaticinvariant 绝热不变量adiabatic lapserate 绝热温度梯度adiabaticmagneticsusceptibility 绝热磁化率adiabatic nucleardemagnetization绝热核去磁adiabaticpotential curve绝热势能曲线adiabaticpotential surface绝热位势面adiabaticprinciple 浸渐原理adiabatic process 绝热过程adiabatic pulsations 绝热脉动adiabatic temperature gradient 绝热温度梯度adiabatic theorem 绝热定理adiabaticity 绝热性adiabatics 绝热线adjacent angles邻角adjacent side 邻边adjointdifferentialequation 伴随微分方程11adjoint operator伴随算符adjoint system伴随系adjunct 代数余子式adjunction 附加adjustable point可定点adjustment 蝶admissible 容许的admissible error容许误差admissible value容许值admittance 导纳admittancematrix 导纳矩阵adsorb 吸附adsorbate 吸附物adsorbed atom吸附原子adsorbent 吸附剂adsorption 吸附adsorption capacity 吸附本领adsorption isotherm 等温吸附式adsorption structure 吸附结构advance of periastron 拱线运动advanced potential 超前势advancing wave 前进波advection 平流平移advection fog 平另advective 平聊aeolian tone 风吹声aerial 空气的aerial survey 航空测量aeroacoustics 空气声学aerobiology 高空生物学aeroclimatology高空气候学aerodone 滑翔机aerodynamicbalance 空气动力天秤aerodynamicdrag 空气阻力aerodynamicfocus 气动力学焦点aerodynamicheating 气动力加热aerodynamic lift气动升力aerodynamicresistance 空气阻力aerodynamics 空气动力学aerogel 气凝胶aerohypsometer 航空测高计aerolite 石陨星aerological 高空气象学的aerological diagram 高空图解12aerology 高空气象学aeromagnetics 航空磁学aeromechanics 空气力学aerometer 气体比重计aeronautical 航空的aeronauticalmeteorologicalobservation 航空气象观测aeronauticalmeteorologicalstation 航空气象站aeronauticalmeteorology 航空气象学aeronautics 航空学aeronomy 高层大气物理aerophysics 航空物理学aeroplane 飞机aeroport 航空航aerosol 气溶胶aerospacescience 空间航空科学aerostatics 气体静力学affine 仿射的affinecoordinates 仿射坐标affine geometry仿射几何affine space 仿射空间affine transformation 仿射变换affinity 亲合势affirmation 肯定affix 标出afocal 非焦点的after discharge 后续放电after heat 残热afterglow 余辉afterimage 残留影象aftershock 余震age 陈化age determination 测定年代age equation 年龄方程age hardening时效硬化age of the moon月龄age theory 年龄理论ageostrophicwind 非地转风aggregate 聚合体aggregation 聚集aging 时效agonic line 无偏线agreement 一致agriculturalclimatology 农业气候学agriculturalmeteorology 农业气象学13agroclimatology农业气候学agrometeorology农业气象学agrophysics 农业物理学aharonov bohmeffect 阿哈拉诺夫玻姆效应air capacitor 空气电容器air cell 空气电池air chamber 气室air compressor 空气压缩机air condenser 空气电容器air coolant 冷却空气air cooler 空气冷却器air cooling 空气冷却air coordinates 空间座标air current 气流air earth current地空电流air flow 气流air gap 气隙air glow 气辉air insulation 空气绝缘air ionizationchamber 空气电离室air mass 气团air mass analysis气团分析air massclassification 气团分类air massmodification 气团变性air massthunderstorm 气团雷暴air monitor 大气污染监视器空气监测器air pocket 气囊air pressure 空气压力air proof 气密的air pump 空气泵air resistance 空气阻力air shower 空气簇射air streamline 空气吝air temperature 气温air thermometer 空气温度表air tight 气密的airborne holography 空中全息照相aircraft observation 飞机观测airplane 飞机airtight packing 气密密封airy pattern 埃里图样airy's disk 埃里斑albedo 反照率albedometry 反射率测定法14alchemy 炼金术alcohol 醇alcoholthermometer 酒精温度表alder transition阿尔得跃迁aleph zero 阿列夫零alexandrite laser翠绿宝石激光器algebra 代数algebraiccomplement 代数余子式algebraiccorrespondence代数对应algebraic curve代数曲线algebraicequation 代数方程algebraicexpression 代数式algebraicfunction 代数函数algebraic geometry 代数几何algebraic polynomial 代数多项式algebraic sum 代数和algebraic surface 代数曲面algebraic system 代数系algebraic variety 代数族algebroidal function 代数型函数algevraic 代数的algol 算法语言algol typeeclipsing binary大陵变星algol variable 大陵变星algorithm 算法algorithmiclanguage 算法语言alidade 照准仪aligned nuclei 排列整齐的核;线列核alignment 定向alignment chart列线图alkali 碱alkali halide 碱金属卤化物alkaline battery碱性蓄电池alkaline earthmetal 碱土金属all weatherremote sensing全天候遥测allende meteorite艾伦德陨星allobar 变压区allochromatic 假色的allomerism 异质同晶allomorphic 同质异晶的allomorphism 同质异晶allotrope 同素异形体allotropic 同素异形的allotropic modification 同素异形变态15allotropic transformation 同素异形变换allotropy 同素异形allow 容许allowable 容许的allowable error容许误差allowable stress容许应力allowabletransition 容许跃迁allowed energyband 容许能带allowed line 容许谱线allowedtransition 容许跃迁alloy 合金alloy diffusedtransistor 合金扩散晶体管alloy diffusiontransistor 合金扩散晶体管alloy junction 合金结alloy junctiondiode 合金结二极管alloy junctiontransistor 合金结型晶体管alloyed steel 合金钢alloyedtransistor 合金晶体管almanac 天文年历almost everywhere 几平处处almost periodic function 殆周期函数almucantar 等高圈alnico 阿尔尼科合金alpha decay 衰变alpha disintegration 衰变alpha emitter 发射体alpha iron 铁alpha particle 粒子alpha particlemodel of nucleus核的粒子模型alpha phase 相alpha process 过程alpha radiation辐射alpha radioactive放射性的alpharadioactivity 放射能alpha rayspectrometer 谱仪alpha rays 射线alpha spectrum射线谱alphanumeric 字母数字式alphatronvacuum gage 真空计altar 天坛座altazimuth 地平经纬仪alternate angles错角alternating 变号的alternating current 交流16alternating current bridge 交羚桥alternating current josephson effect 约瑟夫逊效应alternating field 交变场alternating gradient focusing 强聚焦alternating gradient synchrotron 交变磁场梯度同步加速alternating group交代群alternating load交变负载alternating series交错级数alternation 交错alternative 必择其一altimeter 高度表altitude 高度altitude effect 高度效应altitude rocket高空火箭alto 女中音altocumulus 高积云altostratus 高层云aluminium 铝aluminium alloy铝合金aluminiumelectrolyticcapacitor 铝电解电容器aluminizing 铍铝alundum 人造刚玉amagat 阿马伽amagatmanometer 阿马伽压力计amalgam 汞齐amalgamation 汞齐化amber 琥珀ambient 周围的ambient pressure 环境压力ambient temperature 周围温度ambipolar diffusion 双极扩散americium 镅ametropia 眼反常amici's prism 阿米吴镜ammeter 安培计ammonia 氨ammonia maser氨分子微波激射器ammonia water氨水ammonium 铵amorphous 无定形的amorphous body非晶体amorphouscarbon 无定形碳amorphousmagneticmaterial 非晶磁材料amorphousmagnetism 非晶体磁性17amorphousmetal 非晶态金属amorphoussemiconductor非晶态半导体amorphous state非晶态amorphoussubstance 无定形物质amount 数量amount of evaporation 蒸发量amount of information 信息量amount of precipitation 降水量amount of substance 物质量ampere 安ampere hour 安时ampere meter 安培计ampere second安秒ampere turn 安匝ampere turn permeter 每米安匝数ampere turns 安匝数amphoteric 两性的amphoteric ion两性离子amplidyne 放大发电机amplification 放大amplificationconstant 放大系数amplificationfactor 放大系数amplifiedspontaneousemission 放大自发射amplifier 放大器amplifying tube放大管amplitude 振幅amplitudecharacteristic 振幅特性amplitudediscriminator 脉冲高度鉴别器amplitude distortion 振幅失真amplitude function 振幅函数amplitude mode 振幅模amplitude modulated oscillations 爹振荡amplitude modulation 爹amplitude reflectance 振幅反射度amplitude selector 振幅选择器amplitudetransmittance 振幅透过率anabatic wind 谷风anaclastics 屈光学anafront 上滑锋anallobar 正变压中心analog 数学模型analog circuit 模拟电路analog computer模拟计算机analog method相似法18analog signal 模拟信号analog switch 模拟开关analog to digitalconversion 模拟数字转换analog to digitalconverter a d 变换器模数变换器analogous 类似的analogue 数学模型analogue computer 模拟计算机analogue display 相似表示analogue method 相似法analogy 模拟analyser 分析器analysis 分析analysis centre 分析中心analysis of covariance 协方差解析analysis of variance 方差分析analysis ofweather map 天气图分析analysis situs 拓扑学analytic 分析的analyticcontinuation 解析开拓analytic curve 分析曲线analyticdynamics 解析动力学analyticexpression 分析式analytic form 分析形式analytic function解析函数analyticgeometry 分析几何学analytic line 分析线analytic manifold分析簇analytic method分析法analyticperturbationtheory 解析微扰论analytic set 分析集analytic signal 分析信号analytic transformation 分析变换analytic vector 解析向量analytical balance 分析天平analytical dynamics 分析力学analytical mechanics 分析力学analyzer 分析器analyzing magnet 磁分析器anamorphoticlens 象歪曲透镜anastigmat 消象散透镜anastigmatic 去象散的anastigmaticlens 消象散透镜anastigmatism消象散性anchor ring 锚环19and circuit 与电路and or circuit 与或电路andersonlocalization 安德森定域anderson model安德森模型andersonorthogonalitytheorem 安德森正交定理anderson'sdelocalizationtheory 安德森非定域理论andreevreflection 安德列耶夫反射andromeda 仙女座andromedagalaxy 仙女座星云andromeda nebula 仙女座星云anechoic 无回声的anechoic chamber 无回声室anechoic room 静室anelasticity 滞弹性anemogram 风力自记曲线anemograph 风速计anemometer 风速表anemoscope 测风器风速仪anergy 无力aneroidbarograph 膜盒气压表aneroidbarometer 空盒气压表angle 角angle at centre中心角angle correlation角关联angle of advance超前角angle of attack迎角angle of contact接触角angle ofcontingence 切线角angle ofdeclination 偏角angle ofdeflection 偏转角angle ofdeviation 偏向角angle ofdiffraction 衍射角angle of friction摩擦角angle of incidence 入射角angle of intersection 交叉角angle of lag 滞后角angle of lead 超前角angle of minimum deviation 最小偏角angle of polarization 偏振角angle of reflection 反射角angle ofrefraction 折射角angle of rotation旋转角angle ofscattering 散射角angle of slide 滑动角20angle of view 视角angle preserving保角的angle preservingmap 保角映象angstrom 埃angstrom unit 埃单位angular 角的angularacceleration 角加速度angularcoefficient 角系数angularcoordinates 角座标angularcorrelation 角关联angularderivative 角微离angular dispersion 角色散angular displacement 角位移angular distance 角距angular distribution 角分布angular frequency 角频angular magnification 角放大率angular measure 角度angularmomentum 角动量angularmomentumconservation law角动量守恒定律angular motion角动angular quantumnumber 角量子数angularresolution 角分辨率angularseparation 角距angular unit 角的单位angular velocity角速度angularvibrations 角振动anharmonic 非低的anharmonicoscillation 非谐振动anharmonicoscillator 非谐振子anharmonic ratio非低比anharmonic term非谐项anharmonicity非谐振性anhysteric magnetization curve 无磁滞曲线animal electricity 动物电anion 阴离子anisometric crystal 非等轴晶体anisotropic 蛤异性的anisotropic body 蛤异性体anisotropic exchange interaction 蛤异性交换相互酌anisotropic fluid 蛤异性铃anisotropichamiltonian 蛤异性哈密顿函数anisotropicmedium 蛤异性介质anisotropicsuperfluid 蛤异性超铃21anisotropicturbulence 蛤异性湍流anisotropicuniverse 蛤异性宇宙anisotropy 蛤异性anisotropyconstant 蛤异性常数anisotropyenergy 蛤异性能anisotropymagnetic field 蛤异性磁场anisotropy ratio蛤异性比annealing 退火annihilation 湮没annihilationoperator 湮没算符annihilationradiation 湮没辐射annual 年刊annual aberration 周年光行差annual amount of precipitation 年降水量annual equation 周年差annual mean 年平均annual parallax 周年视差annual precession 年岁差annual range 年较差annual variation年变化annular 环annular eclipse环食annular focus 环形焦点annulation 取消anode 阳极anode battery 阳极电池组anodecompartment 阳极空间anode current 板极电流anode darkspace 阳极暗区anode detection板极检波anode fall 阳极势降anode glow 阳极辉光anode rays 极隧射线anode resistance板极电阻anode voltage 板极电压anomalistic 近点的anomalisticmonth 近点月anomalistic year 近点年anomalon 反常子anomaloscope 色盲检查镜anomalous 反常的anomalous absorption 反常吸收anomalous diffusion 反常扩散anomalous dimension 反常量纲22anomalousdispersion 反常色散anomalouselectricresistivity 反常电阻率anomalous halleffect 反常霍耳效应anomalousmagneticmoment 反常磁矩anomalouspropagation 反常传播anomalouspropagation ofsound 声的反常传播anomalousscattering 反常散射anomalous skineffect 反常囚效应anomaloustransmission 反常透射anomalouszeeman effect 反常塞曼效应anomaly 反常antagonism ofions 离子的对抗酌antapex 背点antarctic circle 南极圈antarctic circle ozon hole 南极圈臭氧孔antecedent 前项antenna 天线antenna aperture 天线孔径antenna array 天线阵antenna circuit 天线电路antenna current 天线电流antenna efficiency 天线效率antenna element天线元件antenna gain 天线增益antennaimpedance 天线阻抗antennaresistance 天线电阻antenna tuning天线党anthracene 蒽anti clockwise 反时针的anti corrosive 防锈剂;防锈的anti hyperon 反超子antiisomorphism 反同构性anti trade winds反信风anti trades 反信风antibaryon 反重子antibondingelectron 反键电子antibondingorbital 反键轨函数anticathode 对阴极anticoincidence 反符合anticoincidence analyzer 舛符合分析器anticoincidence circuit 反符合线路anticoincidence method 反符合法anticommutation relation 反对易关系anticommutative 反对易的23anticyclogenesis反气旋发生anticyclolysis 反气旋消散anticyclone 反气旋区域anticyclonic 反气旋的anticyclonicinversion 反气旋逆温antiderivative 不定积分antideuterium 反氘antideuteron 反氘核antiepicentre 震中对点antiferroelectrics反铁电体antiferromagnet反铁磁体antiferromagnetic domain 反铁磁畴antiferromagnetic resonance 反铁磁性共振antiferromagnetism 反铁磁性antiferromagnon反铁磁振子antihadron 反强子antihydrogen 反氢antila 唧筒座antilepton 反轻子antilogarthm 反对数antimatter 反物质antimeson 反介子antimetrical circuit 相反电路antimonsoon 反季风antimony 锑antineutrino 反中微子antineutron 反中子antinomy 谬论antinucleon 反核子antiparallel 逆平行的antiparallelogram 等边梯形antiparticle 反粒子antiphaseboundary 反相边界antipod 对映体antiproton 反质子antiproton atom反质子原子antiproton beam反质子束antiquark 反夸克antireflectioncoating 透光镀膜;增透膜antiresonance反共振antistokes line反斯托克斯线antistokes ramanlaser 反斯托克斯喇曼激光器antisymmetric斜对称的antisymmetric tensor 斜对称张量;反对称张量24 antisymmetrical state 反对称态antisymmetry 反对称antithesis 反题antitrigonometric function 反三角函数antitriptic wind 减速风antitwilight 反曙暮光antiunitaryoperator 反幺正算符antlia 唧筒座antonoff rule 安托诺夫定则anvil 铁砧anvil cloud 砧状云anyon 任意子apastron 远星点aperiodic 非周期的aperiodicdamping 非周期衰减aperiodic motion非周期运动aperiodicity 非周期性aperture 口径aperturediaphragm 孔径光栏aperture ratio 口径比aperture stop 孔径光栏aperturesynthesis 孔径综合法apex 顶apex angle 顶角apex of the sun 太阳向点aphakic eye 欠晶眼aphelion 远日点apical angle 顶角aplanat 消球差镜aplanatic 等光程的aplanatic lens 消球差镜aplanatic point 等光程点aplanatism 消球差性apochromat 复消色差镜apochromatic 复消色差的apochromaticlens 复消色差镜apodization 切趾法apogee 远地点apolar 非极性的apollo 阿波罗飞船apollo typeasteroid 阿波罗型小行星apostilb 亚熙提apothem 垂幅apparatus 仪器装置25apparentabsorptioncoefficient 表观吸收系数apparent density视在密度apparentdiameter 视直径apparent force表观力apparent horizon可见地平apparent lifetime表观寿命apparentmagnitude 视星等apparent motion 视运动apparent noon 视午apparent orbit 视轨道apparent palce 视位apparent position 视位apparent solar day 真太阳日apparent solar time 真太阳时apparent structure 表观结构apparent sun 真太阳apparition 出现appearancepotential 表观势appendix 附录application 应用applied 应用的appliedacoustics 应用声学appliedclimatology 应用气候学applied elasticity应用弹性理论appliedmathematics 应用数学appliedmechanics 应用力学appliedmeteorology 应用气象学applied optics 应用光学applied physics应用物理学approach 接近approximability可逼近性approximable 可逼近的approximate 近似的;使近似approximate caculation 近似计算approximate formula 近似公式approximate method 近似法approximate number 近似数approximate solution 近似解approximate value 近似值approximatintegr ation 近似积分approximation 近似approximation calculus 近似计算apsidal motion拱线运动apus 天燕座26apw method 增广平面波法aquarius 宝瓶座aqueous solution水溶液aquila 天鹰座ara 天坛座arc 电弧arc discharge 电弧放电arc lamp 弧光灯arc line 弧光谱线arc spectrum 电弧光谱arc trigonometricfunction 反三角函数archimedes'principle 阿基米德原理architecturalacoustics 建筑声学arctic circle 北极圈ardometer 光学高温计。
第四章 近邻法
d ( x, y)
i 1
n
xi yi xi yi
( xi , yi 0, xi yi 0)
第四章 近邻法则和集群
5
关于距离测度
距离
对事物进行分类本身是依据同类样本属性的相似性， 在使用特征向量表示时，体现为同类样本在特征空间中靠的 很近，因此可以用各种方法度量样本数据间的差异。一般说 来，使用欧氏距离是最常用的，它表示两个向量的差向量的 模，这种计算在衡量几何距离时最为合适，例如各城市之间 的距离。 但在模式识别中特征向量的各个分量的含义往往是不同 的，就像苹果的例子中，一个表示重量，一个表示直径，两 者的单位都不一样，因此使用欧氏距离并不合理。一般来说 样本的各个分量的分布范围在数量级上比较相近为好。使用 分量差的绝对值总和表示距离往往是对欧氏距离的简化，将 平方计算改为了绝对值计算。 第四章 近邻法则和集群
16
剪辑近邻法
改进 方法
剪辑近邻法：其基本思想是，利用现有 样本集对其自身进行剪辑，将不同类别 交界处的样本以适当方式筛选，可以实 现既减少样本数又提高正确识别率的双 重目的。
第四章 近邻法则和集群
17
剪辑近邻法
改进 方法
剪辑的过程是：将样本集KN分成两个 互相独立的子集：test集KT和reference 集KR。首先对KT中每一个Xi在KR中找 到其最近邻的样本Yi(Xi) 。如果Yi与Xi 不属于同一类别，则将Xi从KT中删除， 最后得到一个剪辑的样本集KTE（剪辑 样本集），以取代原样本集，对待识别 样本进行分类。
k
决策规则：
if g j (x) min gi (x) then x j
i
k近邻算法的三个基本要素
k近邻算法的三个基本要素K近邻算法是一种常用的分类和回归算法，它基于样本之间的距离来进行分类或预测。
在实际应用中，K近邻算法有着广泛的应用，例如图像识别、自然语言处理等领域。
K近邻算法的三个基本要素包括：距离度量、K值的选择以及分类决策规则。
一、距离度量距离度量是指如何计算两个样本之间的距离。
在K近邻算法中，常用的距离度量包括欧氏距离、曼哈顿距离和闵可夫斯基距离等。
1. 欧氏距离欧氏距离是最常用的一种距离度量，它表示两个样本在n维空间中各个维度上坐标差值平方和的平方根。
假设有两个n维向量$x=(x_1,x_2,...,x_n)$和$y=(y_1,y_2,...,y_n)$，则它们之间的欧氏距离为：$$d_{ij}=\sqrt{\sum_{k=1}^{n}(x_{ik}-y_{jk})^2}$$2. 曼哈顿距离曼哈顿距离也称为城市街区距离或L1距离，它表示两个样本在n维空间中各个维度上坐标差值的绝对值之和。
假设有两个n维向量$x=(x_1,x_2,...,x_n)$和$y=(y_1,y_2,...,y_n)$，则它们之间的曼哈顿距离为：$$d_{ij}=\sum_{k=1}^{n}|x_{ik}-y_{jk}|$$3. 闵可夫斯基距离闵可夫斯基距离是欧氏距离和曼哈顿距离的一般化，它表示两个样本在n维空间中各个维度上坐标差值的p次方和的p次方根。
假设有两个n维向量$x=(x_1,x_2,...,x_n)$和$y=(y_1,y_2,...,y_n)$，则它们之间的闵可夫斯基距离为：$$d_{ij}=(\sum_{k=1}^{n}|x_{ik}-y_{jk}|^p)^{\frac{1}{p}}$$二、K值的选择K近邻算法中的K值是指在分类或预测时选择最近的K个样本进行决策。
K值的选择对于算法的性能影响很大，一般来说，K值越小，算法对于噪声的敏感度越高，而K值越大，则算法对于样本分布的全局特征反应越明显。
感知器准则例题
感知器准则例题感知器准则是一种在模式识别和机器学习中常用的准则，它主要用于二分类问题。
下面是一个简单的感知器准则的例子：假设我们有一个简单的二分类问题，其中特征为 (x)，类别为(y)。
对于这个分类问题，我们定义一个线性分类器 (f(x) = w \cdot x + b)，其中 (w) 是权重向量，(b) 是偏置项。
现在，我们有一个训练数据集 (D = {(x_1, y_1), (x_2, y_2), \ldots, (x_n, y_n)})，其中 (y_i = \pm 1) 表示类别。
我们的目标是找到一个分类器 (f(x))，使得对于训练数据集中的所有样本，(f(x)) 的输出与 (y) 的值一致。
感知器准则的基本思想是：如果存在一个分类器 (f(x)) 能够将训练数据集中的所有样本正确分类，那么这个分类器就是一个好的分类器。
为了找到这样的分类器，我们可以使用感知器算法。
该算法的基本步骤如下：1.初始化权重向量 (w) 和偏置项 (b) 为随机值。
2.对于每个样本 ((x_i, y_i)) 在训练数据集 (D) 中，计算(f(x_i)) 的值。
3.如果 (y_i f(x_i) > 0)（即类别和预测值一致），则不更新权重向量和偏置项。
4.如果 (y_i f(x_i) \leq 0)（即类别和预测值不一致），则根据规则更新权重向量和偏置项。
5.重复步骤 2-4，直到训练数据集中的所有样本都被正确分类，或者达到预设的迭代次数。
感知器准则的优点是简单、易于实现和收敛速度快。
然而，它也有一些限制，例如对非线性问题可能无法找到全局最优解，并且对噪声和异常值敏感。
为了解决这些问题，研究者们提出了许多改进算法，如支持向量机、神经网络等。
近场口径场变换的MoM_PWS方法_胡鸿飞
1
引
言
解 [ 3,4] 。该方法近 场测 量的 采样参 数无 需满 足 Nyquist 取 样 定理 , 而 且由于 进一 步引 入共轭 梯度 快速 Fourier 变 换算 法 ( CGFFT )
[ 5]
近场测量技术不仅能够预计天线的远场性能参数 , 还可 以对天线口径面的幅相分布进行诊断和调整 , 完成研 制新型 高性能天线的任务。 近场测量中的数学变换 和数据 处理是 决定测 量方 法有 效性和测 量 精 度 优 劣的 关 键 技 术。 基于 平 面 波 谱 ( plane wave spectrum, PWS) 的 近 口 径场 变 换 方 法能 够 修 正 探头 效 应 , 并引入 FFT 技 术 , 其 变换 速 度快、 工 程 实用 性 强
。但
是 , 该方法把被测 天 线 ( antenna under test, AUT ) 的 PWS 带宽 限定在可见域 , 忽略衰减波 , 从而制约了口径场的诊断精 度 , 对于电小尺寸的天线尤 为如此。基 于等效 磁流的 近口 径场 变换方法 [ 2] 由积分方程把 扫描面上 切向电 场与口 径面 上等 效流的分布联系起 来 , 通过 奇异 值分 解法 ( SVD) , 求解 矩阵 方程的广义逆矩阵来获得 口径场 幅相分 布的总 体最小 二乘
收稿日期 : 2001- 03- 19 修订日期 : 2001- 05- 21
基金项目 : 国防科技重点实验室基金资助课题 ( 99JS07. 3. 1) 作者简介 : 胡鸿飞 ( 1972- ) , 男 , 博士研究生 , 主要研究方向为现代近场天线测量技术和天线数值分析。
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系统工程与电子技术
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Only Two Approximations Necessary
• Multiple reflections small enough to neglect • Measurements made over a finite plane
Fast and Efficient Data Processing (Primarily FFT)
Copyright 2009 by NSI Page 5
AUT and Probe Properties Examples
AUT and Probe Gain, Friis Transmission Equation
PRe c ⎛ λ ⎞ = G AUT GPr obe ⎜ ⎟ PIn ⎝ 4π R ⎠
Page 15
Plane Wave Scattering Parameters
t00 = Reflection coefficient at input t01 = Receiving coefficients t10 = Transmitting coefficients t11 = Scattering coefficients, plane waves scattered into plane waves
Copyright 2009 by NSI Page 7
Two Key Concepts in Near-Field Theory
Represent the field transmitted by AUT and probe response in terms of spectrum of waves
Copyright 2009 by NSI Page 16
Development of Transmission Equation
Developed using Measurement Approach, Not a Rigorous Derivation Defines and Illustrates Essential Features of Planar Theory Transmission Equation, Solution of Transmission Equation, Probe Correction and Calculation of Far-Field Parameters can be Rigorously Derived
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Single Plane Wave With Two Polarizations
′ ′ ′ b0 = F ′ a0 ⎡ t10 x (0) s02 x (0) + t10 y (0) s02 y (0) ⎤ e ikd ⎣ ⎦ r r ′ = F ′ a0 ⎡ t10 (0) • s02 (0) ⎤ e ikd ⎣ ⎦
Planar Theory
Development Of Plane Wave Theory Development Using Measurement Approach Understanding Working Equations Planar Transmission Equations Solution Using FFT Planar Probe Correction Calculating Far-Field Parameters
Each vector component is a complex number
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Propagation Vector
r k = Propagation vector ˆ ˆ ˆ = kx x + k y y + kx z = Defines direction of plane wave
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Planar Scattering Matrix Schematic
Y
S1
S0 b0
a0
′ S2
′ S0 ′ b0 ′ a0
Probe
r r b(K )
Z
r r a′( K )
r r r r AUT a ( K ) b′( K )
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1 a1 2 a2
b1
b2
b1 = S11a1 + S12a2 b2 = S21a1 + S22a2
S11 = Reflection coefficient at input S12 = Receiving coefficient S21 = Transmitting coefficient S22 = Reflection coefficient at output
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Single, Linearly Polarized Plane Wave
r r ikd ′ ′ b0 = F ′ a0 t10 y ( K = 0) e s02 y ( K = 0)
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Transmission Equation Terms
Near Field Antenna Measurement Theory, Planar, Cylindrical and Spherical
Allen C. Newell Nearfield Systems Inc.
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Page 1
Talk Outline
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Single Plane Wave
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Two Plane Waves Different Directions
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Scattering Matrix for Waveguide
Planar Near-Field
• Development of Transmission Equations • Solution and probe correction • Calculating far-field parameters
Cylindrical Near-Field
• Present Transmission Equation, compare to planar • Probe correction • Far-field parameters
• Plane waves for planar • Cylindrical waves or modes for cylindrical • Spherical waves or modes for spherical
Describe antenna properties using scattering matrix description similar to S parameters for transmission line devices
• Not valid in the near-field • No polarization information
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Theoretical Basis for Planar Near-field Measurements
Scattering Matrix Theory Developed by Dr. D. M. Kerns in 1960’s Does Not Require:
r r ′ t10 (0) and s02 (0) are now complex vectors
′ b0 = Output complex amplitude from probe F ′ = Impedance Mismatch Factor a0 = Input complex amplitude to AUT t10 y = Transmitting Plane Wave Coefficient for AUT ′ s02 y = Receiving Plane Wave Coefficient for Probe
Spherical Near-Field
• Present Transmission Equation, compare to planar • Novel numerical techniques • Probe correction and far-field parameters
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Transmission Equation Requirements
Contain properties of Antenna Under Test (AUT) and probe in terms of measurable data
Measured Data(Position or angles) = Function of [ T(Direction and Polarization) & S(Direction and Polarization)] Where T(Direction and Polarization) ≡ AUT Properties as a function of direction and polarization S(Direction and Polarization) ≡ Probe Properties as a function of direction and polarization
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