英文翻译

第一篇：英文翻译

应用四种算法对机器人PID控制器设计的比较研究 网上发表时间：2010年6月

Mohammad-Taghi Vakil-Baghmisheh · Mina Salim © Springer Science+Business Media B.V.2010

本文比较了四种PID控制器混合进化算法控制机器人的表现，我们尽量减少瞬时状态阶跃响应。为此，一个函数阶跃响应的一些参数（超调量，调节时间时间，上升时间和稳态误差）的定义。我们为了尽量减少瞬时状态阶跃响应，对四种算法的结果进行了比较，四种算法即粒子群优化算法（PSO），蜂群优化算法（QB），遗传算法（GA），SCE算法（shuffled complex evolution）。

在PID控制器设计中，我们要在测试的几种方法的基础上获得的结果，以便我们可以选择一个最好的方法，在我们以往的经验中，关节1, 2,和4用QB算法, 关节3用基因遗传算法,关节5用复杂演化算法取得了很好地效果

关键词：Gryphon robot · Queen-bee · Particle swarm · Shuffled complex evolution ·Nelder–Mead 1 介绍

由于其简单性和高效率，PID控制器被广泛应用于各个行业。PID控制器的传递函数为公式1。

其中Kp为比例增益，KD为微分增益，Ki是积分增益，他们都是变量。通常确定这些参数值的准确值和误差的方法是时域分析和计算。

近年来，PID控制器设计的一些新的方法已被使用，其中包括遗传算法GA（荷兰1975），蚁群算法(Hsiao and Chuang 2004),粒子群优化算法(Gaing 2004),模拟退火算法(SA)(Zhou and Birdwell 1994), 蜂群算法(Luˇci´c and Teodorovi´c 2001;Luˇci´c and Teodorovi´c 2003),，这只是其中一部分算法。

利用这些算法，我们可以把PID控制器的设计问题转化为一个函数问题，从而得到优化。在本文中，我将通过机器人的不同表现，比较四种不同的算法。为此我们定义了一个以阶跃响应的四个参数为变量的函数，四个参数为超调量，调节时间Ts，上升时间Tr，稳态误差Ess，并使用进化算使成本函数最小化。本文的余下部分安排如下，第二部分介绍机器人及其参数，第三部分比较分析GA,PSO,QB和NM方法。第四部分，SEC的算法描述。在第五部分，我们分别用GA,PS,NM,QB-NM,SCE算法的PID控制器设计机器人。第六部分，我们对设计的结果进行介绍和讨论。第七部分为总结。2 机器人介绍

机器人有五个自由度控制他的关节转动，（见表1）我们把他的肩，肘，腕三个关节的表现记录下来，除了精度，连续性和速度是他的两个重要表现。这个机器人由四个微处理器控制，一个控制机器人的各个节点，两个微处理器控制电机，第四个与前三个同步，并使四个微处理器与电脑主机建立正确关系。

控制每个轴的步进电机需要与一个编码器联合、反馈。由于在机器人设计中应用的齿轮比较高，所以机器人的动作缓慢。机器人的关节都可以独立控制。表1 给

出了各个关节的传递函数，这些函数是在Tabriz大学的机器人研究实验室研究出来的。

3.进化算法的综述

在合理的时间里，进化算法可以获取困难问题的最理想解决方案，而那些经典方法无法获得。这些算法被称为最理想是因为通常其他算法没有办法证明他们是最优秀的。在本文中，我们将讨论这四种算法，他们分别是遗传法，粒子群法，蜂群优化算法，SCE算法。3.1 遗传算法

遗传算法是在1975年由荷兰引入，他对自然遗传算法的优化有所启发，遗传算法不需要衍生信息，甚至成本函数在搜索空间不需要连续。模型的变量在特定的环境中变化。我们把这些变量称为染色体，以便提高方案和算法的质量，为此，操作人员在预定的迭代函数中对变量染色体操作，这些操作人员对染色体进行选择，交叉和变异。在下面，我们简要的介绍那些操作人员在连续变量上对染色体的操作。

选择：选择算子应用于染色体。

染色体往往是随机选取的，在本文中，我们利用rollet——wheel选择方法。交叉算子工程的两个后代是由选定的成员决定。为此，一个基因的位置是随机选择的，相应的基因（xm和xd）是由两个新值取代。

其中随机数β的范围是0到1，位于选定的基因后的其他基因与双方父母的染色体交换。一次一个基因突变，变量的基因随机选取了突变率。然后，这些基因被搜索空间中的随机变量替换。3.2 PSO算法

PSO算法最初在1995年由Kennedy和Eberhar提出。是起源对简单社会系统的模拟。动物的小组成员们和他们的同伴共享他寻找食物过程中最佳位置的信息。因此，PSO算法是（Kennedy和Eberhar2004）在搜索个人和社会经验的结合。PSO算法中的每个成员称为粒子，每个粒子在搜索空间中有位置矢量和速度矢量。每个粒子根据自身和变量更新他的位置和速度矢量。根据下列公式（Kennedy等人，2001年）第i个粒子改变他的速度和位置。

其中W表示惯性权重因子，Pi是第i个粒子的最佳位置，目前为止，PG是所有变量的所有粒子的最佳位置。C1，C2是通常被称为学习因素，是常数，D表示问题空间的维数，rand1和rand2是两个随机量，范围0到1.3.3 QB算法

QB算法（2003年Nkrani）是一个相对比较新的集体搜索算法，QB算法已被用于广阔范围的优化问题，如多变量问题（2007，karaboga等），非线性约束问题（tai等，2004）聚类（fathian，2007），基于LVQ（fan，2006）和前馈神经网络（karaboga，2007）等。如各种神经网络的训练。他的基因，种群，选择，交叉，变异，繁殖与遗传算法的一些常见概念。然而，它与标准的遗传算法有两个区别：1.变量的最好成员由一体的父母（蜂王）固定2.它使用了两个不同的突变率，即正常的突变率和更大的突变率。在排序的基础上增加成本函数值和一些染色体变异与正常突变率，防止算法过早收敛，其中两个不同突变率与突变变量之间的比例为ζ。3.4 Nelder–Mead算法

NM单纯算法是一种非梯度优化法，通常用于本地搜索。他采用了启发式的搜索策略，只需要评估成本函数（baharlouei，2006）。一个单纯的多面体，顶点比变量数目更多，如2维空间中的三角形。它的N+1个顶点，每个都是一个潜在的问题解决方案。每一步中最坏的点表现为这个点沿其他N个点的质心方向

一个网关的算法详细解释如下：

3.4.1 NM单纯形算法

设定初始化的基本搜索点，选择n个其他点，选择公式如下

其中λi是一个随机数，范围0到1，ei是第i维的单位向量。

1.令n+1个顶点单纯满足F（X1）≤F（X2）≤•••≤F（Xn+1）2.反射：计算反射点和它的值

3.根据Fr的相对值，下列四种情况的相对值可能出现。a.若Fr

若Fe

c．F（xn）

d．Fr≥F（Xn+1），执行里面的收缩，即计算Xcc和评估F（Xcc）：

如果Fcc

和在这些新的点（新的单纯图形的顶点）评估F（x）5.如果停止条件得不到满足，重复第一步算法。

4.Shuffled复杂演化法

SCE方法是一种启发式的优化方法，是由duan等人在1992年提出，他的表现如下：

4.1 SCE算法

1.在搜索空间形成Npop的随机点 2.为每个值评估原函数

3.对函数值按原函数增加的顺序进行排序 4.对复杂值P进行划分 5.进化

A．q随机的指向每一个复杂选择并划分这些复杂点

B．消除每个复杂点的最坏点，并计算其他平均值，反映到Xw

C．如果（Fr

如果Fc

5.PID控制器设计：

其中kp，ki，kd为比例，微分，积分增益.阶跃响应的超调量MP，总时间ts，上升时间tr和稳态误差ess可作为PID控制器的性能参数。这样的设计，将是一个多目标优化的问题。我们定义一个单一的原函数，使一个单一目标问题转换到多目标问题。

其中，β是加权因子。β<0.7，tr和ts受影响较大，对β> 0.7，MP和ESS受影响较大，如果β= 0.7，对所有四项的影响是一样的。为了评估每个染色体，我们将基因带入控制器的传递函数，这也可以计算系统的阶跃响应。通过对原函数的评价来获取ESS,MP ,Tr和Ts，我们为K,p Kd ,Ki 设定一个上限和下限值，分别为150，-50.β值等于0.7

6.仿真结果

在本文中，我们将提到的进化算法结合起来使用以实现更好的结果，除了SCE。（SCE的方法包括内尔德米德法的修订版本）。每次网关算法完成后，运行20次迭代。每种算法的参数值在下面给出。

GA-NM算法参数设置

选择速率为0.6，突变率为0.01，值为10。表2给出GA-NM算法的迭代次数。PSO-NM算法的参数设置（所有关节）。

QB-NM算法的参数设置

选择率为0.6，正常突变率为0.2.强突变率为0.4，ζ= 0.7，迭代数= 70 SEC算法的参数设置如表3

所有关节的阶跃响应如图3,4,5,6和7.。PID参数和各关节的阶跃响应在表4,5,6,7,8中。从结果中我们可以看到，前三个关节的QB-NM算法，由SCE算法计算的接点4和5需要最小的计算时间。但由于设计PID控制器是脱机的过程中计算时间并不是最重要的因素。在机器人控制器的设计中，除了成本函数，减少超调超调量是最重要。

为联合1和2，新墨西哥州的QB-NM算法建立的函数值足够小，并且超调量是0.因此，QB-NM算法是关节1和2PID控制器设计的首选算法。为联合3，SCE算法实现最小成本函数值，但他可以拉开机器人的软议案。然后，我们更倾向于使用这一配合设置，因为GA-NM算法设计的PID控制器的成本价值小，超调量小。用类似的方式，可以得出结论，QB-NM算法设计的控制器最好联合4.。为联合5，使用SCE算法是最好的，因为可以实现0超调量，并且cost value足够小。

7.结论 在本文中，我们设计的机器人PID控制器使用四个进化算法控制机器人关节，即GA-NM,PSO-NM,QB-NM,SCE算法。为此，我们采用了阶跃响应的四个特殊变量，ESS,MP，Tr,Ts，并且定义的代价函数包含这些功能和最小代价函数。这样，我们将一个单目标函数的优化问题转换为多目标函数的优化问题。在一般情况下，一个算法的优劣不能被直接看出。在机器人PID控制器设计的方法中，我们可以根据结果选择最好的一个。这种情况下，结果表明，接头1。2和4用QB-NM算法，接头3用GA-NM算法，5用SCE算法是最合适的

1.PID 控制器比例积分微分控制器（PID 调节器）是一个控制环，广泛地应用于工业控制系统里的 反馈机制。PID 控制器通过调节给定值与测量值之间的偏差，给出正确的调整，从而有规 律地纠正控制过程。PID 控制器算法涉及到三个部分：比例，积分，微分。比例控制是对当前偏差的反应，积分控制是基于新近错误总数的反应，而微分控制则是基于错误变化率的反应。这三种控 制的结合可用来调节过程系统，例如调节阀的位置，或者加热系统的电源调节。根据具体 的工艺要求，通过 PID 控制器的参数整定，从而提供调节作用。控制器的响应可以被认为 是对系统偏差的响应。注意一点的是，PID 算法不一定就是系统或系统稳定性的最佳控制。一些应用可能只需要运用一到两种方法来提供适当的系统控制。这是通过把不想要的 控制输出置零取得。在控制系统中存在 P,PI,PD,PID 调节器。PI 调节器很普遍，因为微分 控制对测量噪音非常敏感。积分作用的缺乏可以防止系统根据控制目标而达到它的目标 值。注释：由于控制理论和应用领域的差异，很多相关变量的命名约定是常用的。控制环基础 一个关于控制环类似的例子就是保持水在理想温度，涉及到两个过程，冷、热水的混 合。人可以凭触觉估测水的温度。基于此他们设计一个控制行为：用冷水龙头调整过程。重复这个过程，调节热水流直到温度处于期望的稳定值。感觉水温就是对过程值或变量的测量。期望得到的温度称为给定值。控制器的输出对 象和过程的输入对象称为控制参数。测量值与给定值之间的差就是偏差值，太高、太低或 正常。作为一个控制器，在确定温度给定值后，就可以粗略决定改变阀门位置多少，以及 怎样改变偏差值。首次估计即是 PID 控制器的比例度的确定。当它几乎正确时，PID 控 制器的积分作用就是起着逐渐调整温度的作用。微分作用就是根据水温变得更热、更冷，以及变化速率来决定什么时候、怎样调整那些阀门。当偏差小时而做了一个大变动，相当 于一个大的调整控制器，会导致超调。如果控制器反复进行大的变动并且反复越过给定值 的改变，控制环将会不稳定。输出值将在期望值或一常量周围摆动，甚至破坏系统稳定性。人不会这样做，因为我们是有智慧的控制人员，可以从历史经验中学习，但 PID 控制器没 有学习能力，必须正确的设定。为有效的控制系统选择正确的参数被称为整定控制器。如果控制器在零偏差从稳定开始，然后进一步的变化将导致其它一些影响过程的能测 量、不能测量值的变化，并且作用于偏差值上。除主过程以外，其他的对扰动有影响的过 程可以用来抑制扰动或实现对目标值的改变。供给水温的变化就构成了对过程的一个扰 动。理论上，控制器能用来控制可测量对象，以及可以影响偏差的输出、输入标准值的所 有过程参数。控制器在工业中被用来调节温度，压力，流速，化学组成，速度以及其它任 何存在可测量的对象。汽车游览控制就是一个自动化的过程控制的例子。由于它们悠久的历史，简易，良好的理论基础以及简单的设置、维护要求，PID 控制 器被许多应用实践所采纳。

2.PID 控制器理论 注释： 这部分描述PID 控制器理想平行或非相互作用的形式。关于其他形式，“其 请看 它的表达式和 PID 形式”这部分。PID 控制是根据它的三个参数而命名的，三参数结合起来就形成控制参数。因此： Pout，Iout 和 Dout 是控制器的三个参数，下面分别予以确定。

2.1 比例度 比例度是根据当前的错误值而做出的变动。比例度可以通过恒定的 Kp 增加来调整，称为比例增益。比例度计算如下： Pout:比例度 Kp：比例系数，协调参数。e:偏差=SP-PV t:时间或瞬时时间（当前的）一个高的比例增益产生于一种输出值的大的变化。如果比例增益太高，系统将变得不 稳定。响应地，一个小的调整产生于一小的输出变化，而如果比例增益太低，当对系统振 荡作出反映时，控制作用可能太小。缺少扰动的情况下，纯粹的比例控制不能完全解决问题，但是将保留从过程中获得的 具有比例增益的功能的稳态偏差。尽管有稳态补偿，理论和工业实践都表明比例度在输出 2 控制中起到大部分的作用。

2.2 积分值 积分值的大小与偏差的大小及持续时间成正比。根据即时的超时的错误改正，进行积 累补偿。积累的误差通过积分调节后再作用于输出。对总的控制作用的积分大小由积分时 间常数来决定，即 Ki，积分值计算如下： Iout：积分值 Ki:积分时间常数，协调参数 e:偏差=SP-PV ζ：积分时间 积分值加速面向设定值的过程运动并且消除残余的只与控制器发生作用的稳态偏差。然而，因为积分从过去的积累误差作出反应，引起当前的值越过设定值（跨过设定值向其 它方向改变）。想了解更多的关于积分和控制器稳定度的知识，请参见关于环路调谐的部分

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第二篇：英文翻译

Introduction: with the rapid development of the economy, China ‘smprehensive national power has been improved effectively.As a saying said;“Want to become rich first road”.So China has begun to build the high-speed rail since years ago.The building of the high~speed rail is suited to China's national conditions and help our country to run well in the strong competition of the world.大多数经济学家认为：交通基础设施的供应水平和能力必须适度超前，否则就会影响社会经济持续、稳定 和健康发展。这就意味着要加大对交通基础设施的投资，但是政府在加大交通基础设施投资力度的同时，用于改善民生的措施实际却在相对地减少。从中国目前的经济发展和人民的收入状况来说，我认为中国高 铁弊大于利.Most economists believe that: the supply and capability of transportation infrastructure must advance appropriately, otherwise it will affect the sustainable, stable and healthy development of social economy.This means that we have to increase the investment into transportation infrastructure,But while government increase the investment into transportation infrastructure, it will to some extent decrease the practical measures to improve people's livelihood.From China's current situation, I think it will do more harm than good to build high-speed railway in China.Piont1: Building too fast go against the laws of economic development, causing many problems, such as loan repayment, staff placement.And high-speed railway construction needs large investment, from the use of the actual situation, the possibility of short-term cost recovery do not, there is also the problem of capital wasting.建设速度过快，容易违背经济发展规律,同时面对的问题较多，例如贷款偿还，员工安置等。中国第一条高 铁客运专线——从北京到天津，它在 2008 年 8 月通车后一年就亏损了 7 个亿。武广高铁总投资约 1166 亿元，目前的线路至少能开 120 对车，但实际上只开了 33 对，而且还坐不满，这是资本的严重浪费。所 以说高铁建设不仅需要大笔的投资，而且从运用的实际的情况来看，短期收回成本的可能性根本就没有。The fast building speed will violate the rule of economic development, and at same time it faced many problems, such as loan repayment, staff placement.First high-speed railway of China-from Beijing to Tianjin, it was launched in August 2008, after one year it lossed 70 millions.The total investment of

Wuhan-Guangzhou high-speed rail was about 110 billions yuan, now it is able to drive at least 120 pairs of cars, but in fact only 33 to drive, and lots of seats are empty, this is a serious waste of capital.The high-speed railway not only requires large construction investment, but also, it is impossible to recovery the short-term cost based on its actural implement.Poiimnt2: The building of the high spee

d rail can drive the development of the industry related.for example, the building need many workers and the new technology, so it expand the employment and promiot the technological innovation.In another word through the building, more steel products are needed.Another important hand is transport during the Spring Festival.During this period of time, large numbers of people going home together.So the high speed rail can relieve the transportation pressure ectively 高铁的票价较高，例如京津高铁，它行驶 30 分钟，却要 69 元票价，让人望而生叹啊。中国的 GDP 总量 高居世界第二，但人均 GDP 在世界的排名却还在百名开外，穷人还是绝大多数。武广高铁开通后，原有 的一些客运列车停运，意味着中低收入者将被迫选择高铁，接受高票价。这种行为伤及了底层人民的最根 本利 e 而且建设过程中容易出现贪污腐败问题。The fare of high Speed Rail is higher, for example, the Beijing-Tianjin high-speed rail, it costs 69 yuan for only drive 30minuts.China's GDP ranks the second in the world, but per capita GDP still ranks out of hundreds in the world, the poor is the majority.When Wuhan-Guangzhou high-speed railway was used, the original passenger trains were stopped, which means low-incomer will be forced to choose high-speed rail and accept the high fares.This action has

impair interests of the low class people, and the corruption problem will be prone to easily during the process of building.新建高铁实际是在现有几种交通方式的基础上新增一种交通方式。建成之后会与高速公路、现有铁路、飞 机、船运形成竞争关系，在原有运力并不紧张的背景下必然形成运力过剩。新建的高铁主要是客运专线，因此高铁并不会加快货物与资金的周转速度，不会降低全社会运行成本。要修建如此庞大的高速铁路网，必将消耗大量的资金，必将挤占人们收入上涨的空间与企业利润空间（加重税负）如果将此财政投入医疗、。社保、教育、技术研究，则会消除人们存钱的预防养老动机从而扩大消费，利于中国经济可持续发展。综 上所述，在中国大规模修建高铁对中国经济的长远发展来讲是弊大于利，不利于扩大内需、不利于产业结 构调整 结论：The high-speed railway will compete with the existing highway, railway, aircraft, shipping after it consummation which will lead to a situation capacity.The new high-speed railway is mainly to carry passenger, so it will not speed up the turnover rate between cargos and the capital and will not decrease the costs of the whole social transportation.To build such a large network of high-speed rail will need a large amount of money, the government must increase the taxes of people and enterprise to raise the capital.If this financial investment used in health care, social security, education, tec

第三篇：英文翻译

Overview of the Global System for Mobile Communications 1 History of GSM During the early 1980s, analog cellular telephone systems were experiencing rapid growth in Europe, particularly in Scandinavia and the United Kingdom, but also in France and Germany.Each country developed its own system, which was incompatible with everyone else’s in equipment and operation.This was an

undesirable situation, because not only was the mobile equipment limited to operation within national boundaries, which in a unified Europe were increasingly unimportant, but there was also a very limited market for each type of equipment, so economies of scale and the subsequent savings could not be realized.The Europeans realized this early on, and in 1982 the Conference of European s Posts and Telegraphs(CEPT)formed a study group called the Group Special Mobile(GSM)to study and develop a pan-European public land mobile system.The proposed system has to meet certain criteria: ·Good subjective speech quality ·Low terminal and service cost ·Support for international roaming ·Ability to support handheld terminals ·Support for range of new services and facilities ·Spectral efficiency ·ISDN compatibility In 1989, GSM responsibility was transferred to the European Telecommunication Standards Institute(ETSI), and phase I of the GSM specifications were published in 1990.Commercial service was started in mid-1991, and by 1993 there were 36 GSM networks in 22 countries.Although standardized in Europe, GSM is not only a European standard.Over 200 GSM networks are operational in 110 countries around the world.In the beginning of 1994, there were 1.3 million subscribers worldwide, which had grown to more than 55 million by October 1997.With North America making a delayed entry into the GSM field with a derivative of GSM called PCS1900, GSM systems exist on every continent, and the acronym GSM now aptly stands for Global System for Mobile communications.The developers of GSM chose an unproven(at the time)digital system, as opposed to the then-standard analog cellular systems like AMPS in the United States and TACS in the United Kingdom.They had faith that advancements in compression algorithms and digital signal processors would allow the fulfillment of the original criteria and the continual improvement of the system in terms of quality and cost.The over 8,000 pages of GSM recommendations try to allow flexibility and competitive innovation among suppliers, but provide enough standardization to guarantee proper interworking between the components of the system.This done by providing functional and interface descriptions for each of the functional entities defined in the system.2 General Concepts 2.1 Analog Versus Digital Telephony Systems First-generation systems were analog.During the early 1980s these underwent rapid development in Europe.Although the NMT system was used by all the Nordic countries, and the TACS system in the United Kingdom and Italy, there was a variety of systems and no compatibility among them.Compared with these systems, the main advantages offered by GSM, which is the most important of the second-generation digital systems, are: ·Standardization;·Capacity;·Quality;·Security.Standardization guarantees compatibility among systems of different countries, allowing subscribers to use their own terminals in those countries that have adopted the digital standard.The lack of standardization in the first-generation system limited service to within the borders of a country.Mobility is improved, since roaming is no longer limited to areas covered by a certain system.Calls can be charged and handled using the same personal number even when the subscriber moves from one country to another.Standardization also allows the operator to buy entities of the network from different vendors, since the functional elements of the network and the interfaces between these elements are standardized.This means that a mobile phone from any manufacturer is able to communicate with any network, even if this network is built with entities from different vendors.This leads to a large economy of scale and results in cost reduction for both the operator and the subscriber.Furthermore, the phone cost is also reduced, because GSM is an international standard, produced quantities are greater and the level of competition is high.With respect to capacity, the use of the radio resource is much more efficient in a digital system such as GSM than in an analog system.This means that more users can be allocated in the same frequency bandwidth.This is possible with the use of advanced digital techniques, such as voice compression algorithms, channel coding, and multiple access techniques.Note that capacity gains are also achieved with radio frequency reuse, which had also used in analog systems.Frequency reuse means that a given carrier can be employed in different areas.The quality in digital transmission systems is better, thanks to the channel coding schemes that increase the robustness in the face of noise and disturbances such as interference caused by other users or other systems.The quality improvement is also due to the improved control of the radio link, and adaptations to propagation conditions, with advanced techniques such as power control or frequency hopping.This will be explained in greater detail in the next section.In terms of security, powerful authentication and encryption techniques for voice and data communications are enabled with GSM, which guarantees protected access to the network, and confidentiality.2.2 Cellular Telephony In mobile radio systems, one of the most important factors is the frequency spectrum.In order to make the best use of the bandwidth, the system is designed by means of the division of the service area into neighboring zones, or cells, which in theory have a hexagonal shape.Each cell has a Base Transceiver Station(BTS), which to avoid interference operates on a set of radio channels different from those of the adjacent cells.This division allows for the use of the same frequencies in nonadjacent cells.A group of cells that as a whole use the entire radio spectrum available to the operator is referred to as a cluster.The shape of a cell is irregular, depending on the availability of a spot for the BTS, the geography of the terrain, the propagation of the radio signal in the presence of obstacles, and so on.In dense urban areas, for instance, where the mobile telephony traffic is important, the diameter of the cells is often reduced in order to increase capacity.This is allowed since the same frequency channels are used in a smaller area.On the other hand, reducing the cell diameter leads to a decrease in the distance necessary to reuse the frequencies(that is, the distance between two co-channel cells), increasing co-channel interference.In order to minimize the level of interference, several techniques are used on the radio interface.A basic example of cluster organization is shown in Figure 1.In this example, we see a reuse attern for seven different frequencies, f1 to f7.These frequencies correspond to the beacon carrier of each cell, on which signaling information about the cell is broadcast(see Section 2.7).It can be seen from this figure that a given carrier can be reused in two separate geographical areas, as long as these areas are far enough from each other to reduce the effect of interference.With this technique of dividing the area in cells and clusters, the operator can increase the area it is able to cover with a limited frequency bandwidth.Figure 1 Example of a Cell Planning

在80 年代初期期间，模式手机系统在欧洲体验迅速增长，特别在斯堪的那

维亚和英国，以及法国和德国。每个国家开发了它自己的系统，在设备和操作 上是互不相容的。这是一个不受欢迎的情况，因为不仅移动通信设备被限制在国 界之内，这在统一的欧洲是越来越不重要的，而且每种类型的设备都只有一个非 常有限的市场，因此经济尺度及随后的储蓄不可能体会。

欧洲人早就意识到了这点，并且在1982 年欧洲邮电管理联合会(CEPT)上形 成了移动通信特别研究组(GSM)来研发一个能在全欧洲大陆通用的移动通信系 统。提出的系统必须符合以下标准： 〃通话质量好

〃终端及服务费用低 〃支持国际漫游

〃能够支持可随身携带的终端 〃支持一系列新的服务和设备 〃效率高

〃与ISDN 兼容

1989 年，GSM 的责任转移了到欧洲电信标准学院(ETSI)，并且GSM 规格的

第一阶段也在1990 年出版了。商业服务在1991 年中期开始了，截至1993 年有 36 个GSM 网络在22 个国家诞生了。GSM 不仅仅是欧洲标准，尽管它是在欧洲 规范化的。现已有200 多个GSM 网络在全球110 个国家和地区运行。1994 年初 期全球有1,300,000 用户，截至1997 年10 月已突破55,000,000 用户。随着美国

后来在GSM 领域制造了一个词条PCS1900 作为GSM 的拓展,GSM 系统已发展至 各大洲,并且缩写词GSM 现在已可以代表移动通信的全局系统。

GSM 开发商选择了一个当时未经证明的数字系统，与后来的标准模式蜂窝系 统相对，就象美国叫AMPS，而英国叫TACS 一样。他们坚信能够推进压缩算法 和数字信号处理器使其能够根据质量和费用将原始标准和系统连续改善。GSM 推荐8,000 页设法使得在与供应商竞争之中体现灵活性和创新，但提供 足够的标准来保证在系统的组分之间适当配合工作。完成提供功能和接口描述的 功能个体在系统中都有定义。

第一代系统是模拟的。上个世纪80 年代初期在欧洲迅速发展。虽然所有北 欧国家使用TACS 系统，英国和意大利使用NMT 系统，它们之间还有各式各样 的系统不兼容。和这些系统相比，GSM 提供的更重要的第二代数字系统主要优势 体现在： 〃标准化； 〃容量； 〃质量； 〃安全。

标准化保证了不同国家系统之间的兼容性，允许采取了数字化标准的国家的 订户使用他们自己的终端。在第一代系统中缺乏标准化的有限服务为在国家的边 界之内。流动性被改进，漫游不再被限制到某一系统包括的面积之内。既使当用 户从一个国家移动到另一个国家，电话也可以使用同一个个人号码。因为网络的功能元件和这些元素之间的接口被规范化，操作员可以从不同的 供营商购买。这意味着所有制造商的移动电话能与任何网络沟通，即使这个网络 是由不同的供营商的功能元件建立的。这为操作员和订户带来费用成本的降低。此外，电话费用也降低了，因为GSM 是国际标准，生产数量大，竞争水平高。能力方面，数字系统如GSM 比模拟系统使用的无线资源更有效。这意味着 更多的用户可以使用同一频带。这就有可能利用先进的数字技术，如语音压缩算 法，信道编码和多址接入技术。请注意，无线电频率复用也取得了一定增益，这 也已用于模拟系统。频率复用意味着同一载波可以在不同的地区重复使用。由于这种信道编码方案，提高了可靠性及对噪音和其他用户或系统的干扰能 力，数字传输系统的质量更好了。质量改进的原因还在于改善了对无线连接的控 制，并适应传播条件下，使用先进的技术，如电源控制或跳频。质量改进的原因 还在于使用先进的技术如电源控制或跳频改善了无线连接的控制,，传播条件的适

应性等。这些将在下文中做更详尽的解释。

在安全方面，GSM 具有语音和数据通信的强大的认证和加密技术的功能，保 证了保护接入网络和保密性。

在移动通信系统中，一个最重要的因素就是频谱。为了最有效地利用带宽，系统设计的目的是通过基站的服务区到周边小区，理论上是一个正六边形。每个 小区有一个收发基站（BTS），其中，以避免相邻小区的不同无线信道在运行时 产生相互干扰。这样可以在不相邻的小区使用同一载频。一组小区，作为一个整 体，给运营商提供整个无线电频谱是指一个区群。小区的形状是不规则的，这取 决于是否有现成的基站，地理地形，无线电信号传播中存在的障碍，等等。例如，在人口密集的城市地区，移动电话的通行非常重要，小区的直径往往 会减小，以提高其通行能力。

这是允许的，因为同一频道只在一个较小的地区内使用。另一方面，小区直 径的减小导致使用同一频率的小区间的距离（即两个公共通道小区间的距离）缩 小了，增强了各频道之间的相互干扰。为了尽量提高抗干扰的能力，无线接口使 用了一系列技术。

一个基本的区群组织的结构如图1 所示。在这个例子中，我们看到了一个复 用模式的7 个不同的频率，f1 至f7。这些频率对应于每个小区的信标载波，整个

小区的信号信息就靠它们被传播出去（见第2.7 节）。从图中可以看出，某一载 波可在两个不同的地理区域重复使用，只要这两个地区离的足够远，相互之间的 干扰足够小。这一技术把地区分成小区和区群，经营者可以利用有限的带宽增加 覆盖区域的面积。

第四篇：英文翻译

School Profile

Jin Yuan Primary School was founded in 1966，and now it has 40 years‟ history.Thepredecessor of the school is ShiMian kuang Children Shool.In May 1993 ,It was placed under the Dalian Development Zone.In 2002, the new building was reconstruction in the school site.Now it occupies a total area of 18500 square meters, with a total construction area of 9020 square meters, it has got 30 class and 1478 students.Our school always adhere to the school mission-“To lay the foundation for the development of student life” and school

philosophy “To train the younger generation for adapting to the new society”.with “implementing quality education, making our school into modernization, distinctive characteristics, high-grade The 'people satisfaction' schools ”for the school mission and goals.Focusing on behavior, raising habits, pursuingdevelopment, hing research,benefit, the high quality;grasping

characteristics, treeing famous“ as the school ideas.”Innovation in operating a school, Distinctive Features,“ as the school way.Our school has been named the standardization of school facilities,education and management of Dalian advanced group, Green School of Dalian , big break in Dalianadvanced unit for physical education curriculum standard education health system,development zone course reform summary advanced unit, the characteristics of the development of school-based curriculum development awards such as prizes, Excellence Award and many other honors.In addition, teaching and research training center was also named the Development of information technology, sports, music, experimental point of school mental health disciplines.School emphasis on ”Science Education“, it has been named the Science and technology activities advanced units;land-sea model training base in Liaoning Province;Dalian Science and Technology Advanced Unit;advanced science and technology activities in Dalian youth units;The intelligent robot teaching activities carried out to further broaden the field of science teaching in recent years, we got soccer robot competition and the Youth Science and Technology Invention Contest winners many times in national, provincial and municipal.Our school was known by scientific and technological innovations, it has become a golden source of education and school characteristics of primary brand, and its fruitful results of educating people to win recognition of the higher education sector and social praise.Our school actively promoting international exchanges and cooperation.Based on the national culture, the students involved in multicultural perspective, let the student to have the ability to

communicate with different culture and cultural understanding

ability, feeling the other civilizations, inheriting Chinese culture, and for students build facing the world, developing yourself and

development of China's platform.At present,we have established the friendly and cooperative relations with Singapore, Britain and other countries of the schools.Our school is committed to the construction of educational information, establishing the educational information to promote the development strategy of modernization of school education.We was honored with the first model school education information by Dalian Municipal Bureau of Education.Physical education in our schoolis also flourished, we always adhere to the ”Sunshine Sports“ project.To ensure that every student at least one hour of exercise a day, each have a favorite sport, the school was named the physical education curriculum standards of Dalian advanced unit, DalianBig calisthenics demonstration school, Dalian”campus football

project“ Development of school.In recent years,school „s sports teams in all kinds of various game had good performance , and it becomes the school‟sbeautifulcard.Standing at a new starting point, facing the new century, we will try to”build multicultural education, reveal personality, improve

the educational grade, promote the connotation development" as our target, makes determined efforts, scientific planning, and strive to improve the level and constantly expand its reputation, trying to be the children paradise of JinYuan Primary School.

第五篇：英文翻译

whether the university student should pay more atteion on studying or not ?the answer issure.First of all,during these time,we can touch more things,whichwehave not ever meet before and make a graetinflunce on our future life,If we don't handle it well,maybe we will lose a lot of thingswe adapt to sociaty more easily and more diffcult.we have time to play, but when you are playing and relaxing, dont forget the things you must do at school.school life is on of the best sections of your life.you need school life and time to learn and do things.