英文翻译与英文原文.陈--
英汉语言对比与翻译
“It is the meaning of a message that is transferred from one language to another, and the transfer is accomplished by analyzing and then reconstructing semantic relationships.”1 “Translation can therefore be defined as the operation by which the relevant signification of linguistic signs is determined through reference to a meaning as formulated in a message, which is then fully reconstructed in the signs of another language.”2 1、2. Delisle, J. Translation: An Interpretive Approach[M]. Eng. trans, by Logan. P & Creery. M., Ottawa: University of Ottawa Press, 1980: 3；52
翻译中英汉语言对比的重要意义 Nhomakorabea就保留原文句法与译文体现原作精神的问题，傅雷也有精辟的论述:“假如破坏本国文字的结构与特性，就能传达异国文字的特性而获得原作的精神，那么翻译真是太容易了。不幸那种理论非但是刻船求剑，而且结果是削足就履，两败俱伤。” 1
01
怒安. 傅雷谈翻译[M]. 沈阳：辽宁教育出版社2005:2
关于英汉语言的比喻
陈安定：英语句子好比“一串珍珠”，而汉语句子则像“一盘大小各异的珍珠，散落玉盘，闪闪发光，灿烂夺目。”1
新视野大学英语2全部课文原文中英文翻译
新视野大学英语2全部课文中英文翻译Unit1Americans believe no one stands still. If you are not moving ahead, you are falling behind. This attitude results in a nation of people committed to researching, experimenting and exploring. Time is one of the two elements that Americans save carefully, the other being labor.美国人相信没有人会停滞不前。
如果你不前进，你就落后了。
这种态度造就了一个致力于研究、试验和探索的民族。
时间是美国人谨慎节约的两个要素之一，另一个是劳动。
"We are slaves to nothing but the clock,” it has been said. Time is treated as if it were something almost real. We budget it, save it, waste it, steal it, kill it, cut it, account for it; we also charge for it. It is a precious resource. Many people have a rather acute sense of the shortness of each lifetime. Once the sandshave run out of a person’s hourglass, they cannot be replaced. We want every minute to count.有人说：“我们只是时钟的奴隶。
研究生英语精读教程（第三版_上）第1单元英文原文与翻译和课后答案（20201219234917）
Unit OneYou Are What You ThinkAnd if you change your mind—from pessimism to optimism—you can change your life 你认为自己是什么样的人，那你就是什么样的人如果你改变想法——从悲观变为乐观——你就可以改变自己的生活Claipe Safran 卡勒普·撒弗兰[ 1 ] Do you see the glass as half full rather than half empty? Do you keep your eyeupon the doughnut, not upon the hole? Suddenly these clichés are scientific questions, as researchers scrutinize the power of positive thinking.[1] 你看酒杯是半杯有酒而不是半杯空着的吗？你的眼睛是盯着炸面圈，而不是它中间的孔吗? 当研究者们仔细观察积极思维的作用时，这些陈词滥调突然间都成了科学问题。
[ 2] A fast-growing body of research—104 studies so far, involving some 15 000people—is proving that optimism can help you to be happier, healthier and moresuccessful. Pessimism leads, by contrast, to hopelessness, sickness and failure, andis linked to depression, loneliness and painful shyness. "If we could teach people tothink more positively," says psychologist Craig A. Anderson of Rice University inHouston，"it would be like inoculating them against these mental ills."[2]迅速增多的大量研究工作——迄今已有 104 个研究项目，涉及大约 15 000人——证明乐观的态度可以使你更快乐、更健康、更成功。
出师表原文及英文翻译
原文：先帝创业未半而中道崩殂（cú）。
今天下三分，益州疲（pí）弊，此诚危急存亡之秋也。
然侍卫之臣不懈于内，忠志之士忘身于外者，盖追先帝之殊遇，欲报之于陛下也。
诚宜开张圣听，以光先帝遗德，恢弘志士之气，不宜妄自菲薄，引喻失义，以塞（sè）忠谏之路也。
宫中府中，俱为一体；陟（zhì）罚臧（zāng）否（pǐ），不宜异同；若有作奸犯科及为忠善者，宜付有司论其刑赏，以昭陛下平明之理；不宜偏私，使内外异法也。
侍中、侍郎郭攸（yōu）之、费祎（yī）、董允等，此皆良实，志虑忠纯，是以先帝简拔以遗（wèi）陛下。
愚以为宫中之事，事无大小，悉以咨之，然后施行，必能裨（bì）补阙漏，有所广益。
将军向宠，性行淑均，晓畅军事，试用于昔日，先帝称之曰能，是以众议举宠为督。
愚以为营中之事，事无大小，悉以咨之，必能使行（háng ）阵和睦，优劣得所。
亲贤臣，远小人，此先汉所以兴隆也；亲小人，远贤臣，此后汉所以倾颓也。
先帝在时，每与臣论此事，未尝不叹息痛恨于桓、灵也。
侍中、尚书、长(zhǎng)史、参军，此悉贞良死节之臣，愿陛下亲之信之，则汉室之隆，可计日而待也。
臣本布衣，躬耕于南阳，苟全性命于乱世，不求闻达于诸侯。
先帝不以臣卑鄙，猥（wěi）自枉屈，三顾臣于草庐之中，咨臣以当世之事，由是感激，遂许先帝以驱驰。
后值倾覆，受任于败军之际，奉命于危难之间，尔来二十有（yòu ）一年矣。
先帝知臣谨慎，故临崩寄臣以大事也。
受命以来，夙（sù）夜忧叹，恐托付不效，以伤先帝之明，故五月渡泸，深入不毛。
今南方已定，兵甲已足，当奖率三军，北定中原，庶(shù)竭驽（nú）钝，攘（rǎng）除奸凶，兴复汉室，还于旧都。
此臣所以报先帝而忠陛下之职分也。
至于斟酌损益，进尽忠言，则攸之、祎、允之任也。
愿陛下托臣以讨贼兴复之效，不效，则治臣之罪，以告先帝之灵。
英文实时翻译
英文实时翻译英文实时翻译是指实时将英文内容翻译成其他语言，比如中文。
以下是一个700字的英文实时翻译示例：原文：Hello everyone, welcome to our conference. Today, we are going to discuss the latest developments in the field of artificial intelligence. Our speakers will share their research findings and insights on various topics, including machine learning, natural language processing, and computer vision. We hope that this conference will provide a platform for professionals in the field to exchange ideas and foster collaborations. Without further ado, letus begin.翻译：大家好，欢迎来到我们的会议。
今天，我们将讨论人工智能领域的最新发展。
我们的演讲者将分享他们在机器学习、自然语言处理和计算机视觉等各个主题上的研究发现和见解。
我们希望这次会议能为该领域的专业人士提供一个交流思想、促进合作的平台。
话不多说，让我们开始吧。
原文：First, we have Dr. Johnson from Stanford University. Hewill be talking about the advancements in deep learning algorithms and their applications in various domains. Dr. Johnson has been at the forefront of research in this field and has published numerous papers on the subject.翻译：首先，我们有来自斯坦福大学的约翰逊博士。
新概念第2册课文Lesson196英文原文+翻译
新概念第2册课文Lesson196英文原文+翻译Last week I went to the theatre. I had a very good seat. The play was very interesting. I did not enjoy it. A young man and a young woman were sitting behind me. They were talking loudly. I got very angry. I could not hear the actors. I turned round. I looked at the man and the woman angrily. They did not pay any attention. In the end, I could not bear it. I turned round again. 'I can't hear a word!' I said angrily. ‘It’s none of your business,' the young man said rudely. 'This is a private conversation!'.上星期我去看戏。
我的座位很好，戏很有意思，但我却无法欣赏。
一青年女子与一青年女子坐在我的身后，大声地说着话。
我十分生气，由于我听不见演员在说什么。
我回过头去怒视着那一男一女，他们却毫不理会。
最后，我忍不住了，又一次回过头去，生气地说：〝我一个字也听不见了!〞〝不关你的事，〞那男的毫不客气地说，〝这是公家间的说话!〞Lesson 2 Breakfast or lunch? 早餐还是午餐?It was Sunday. I never get up early on Sundays. I sometimes stay in bed until lunch time.Last Sunday I got up very late. I looked out of the window. It was dark outside.'What a day!' I thought. 'It's raining again.' Just t hen, the telephone rang. It was my aunt Lucy.' I've just arrived by train,' she said. 'I'm coming to see you.' 'But I'm still having breakfast,' I said.'What are you doing?' she asked. ‘I’m having breakfast,' I repeated.'Dear me,' she said. 'Do you always get up so late? It's one o'clock!''那是个星期天，而在星期天我是历来不早起的，有时我要不时躺到吃午饭的时分。
古诗《春夜喜雨》原文翻译及英文翻译
古诗《春夜喜雨》原文翻译及英文翻译古诗《春夜喜雨》原文翻译及英文翻译引言：《春夜喜雨》是唐诗名篇之一，诗中对春雨的描写，体物精微，细腻生动，绘声绘形。
全诗意境淡雅，意蕴清幽，诗境与画境浑然一体，是一首传神入化、别具风韵的咏雨诗，下面是小编整理的《春夜喜雨》原文翻译及英文翻译，看看怎么用英语来表达杜甫的《春夜喜雨》。
杜甫《春夜喜雨》好雨知时节，当春乃发生。
随风潜入夜，润物细无声。
野径云俱黑，江船火独明。
晓看红湿处，花重锦官城。
【原文翻译】多好的春雨啊，好像知道时节变化，到了春天，它就自然地应时而生。
伴随着和风在夜里悄悄飘洒，滋润着万物轻柔而寂然无声。
野外的小路上空乌云一片漆黑，只有江面小船还亮着一盏孤灯。
清晨观赏细雨湿润的处处春花，朵朵沉甸甸地开遍美丽的成都。
【英文翻译】Happy Rain on a Spring NightGood rain knows its time right;It will fall when comes spring.With wind it steals in night;Mute, it moistens each thing.O’er wild lanes dark cloud spreads;In boat a lantern looms.Dawn sees saturated reds;The town’s heavy with blooms.注释1.知：明白，知道。
说雨知时节，是一种拟人化的写法。
2.乃：就。
发生：萌发生长。
3.发生：萌发生长。
4.潜（qián）：暗暗地，悄悄地。
这里指春雨在夜里悄悄地随风而至。
5.润物：使植物受到雨水的滋养。
6.野径：田野间的小路。
7.晓：天刚亮的时候。
红湿处：雨水湿润的花丛。
8.红湿处：指有带雨水的红花的地方。
9.花重：花沾上雨水而变得沉重。
10.重：读作zhòng（重在这里的意思是：沉重。
所以读作第四声。
At the Edge of the Sea(英文原文+中文翻译)
At the Edge of the SeaRachel CarsonThe shore is an ancient world, for as long as there has been an earth and sea there has been this place of meeting of land and water. Yet it is a world that keeps alive the sense of continuing creation and of the relentless drive of life. Each time that I enter it, I gain some new awareness of its beauty and deeper meanings, sensing that intricate fabric of life by which one creature is linked with another, and each with its surroundings.In my thoughts of the shore, one place stands apart for its revelation of exquisite beauty. It is a pool hidden within a cave that one can visit only rarely and briefly when the lowest of the year’s low tides fall below it, and perhaps from that very fact it acquires some of its special beauty. Choosing such a tide, I hoped for a glimpse of the pool. The ebb was to fall early in the morning. I knew that if the wind held from the northwest and no interfering swell ran in from a distant storm the level of the sea should drop below the entrance to the pool. There had been sudden ominous showers in the night, with rainlike handfuls of gravel flung on the roof. When I looked out into the early morning the sky was full of a gray dawn light but the sun had not yet risen. Water and air were pallid. Across the bay the moon was a luminous disc in the western sky, suspended above the dim line of distant shore—the full August moon, drawing the tide to the low, low levels of the threshold of the alien sea world. As I watched, a gull flew by, above the spruces. Its breast was rosy with the light of the unrisen sun. The day was, after all, to be fair.Later, as I stood above the tide near the entrance to the pool, the promise of that rosy light was sustained. From the base of the steep wall of rock on which I stood, a moss covered ledge jutted seaward into deep water. In the surge at the rim of the ledge the dark fronds of oarweeds swayed, smooth and gleaming as leather. The projecting ledge was the path to the small hidden cave and its pool. Occasionally a swell stronger than the rest, rolled smoothly over the rim and broke in foam against the cliff. But the intervals between such swells were long enough to admit me to the ledge and long enough for a glimpse of that fairy pool, so seldom and so briefly exposed.And so I knelt on the wet carpet of sea moss and looked back into the dark cavern that held the pool in a shallow basin. The floor of the cave was only a few inches below the roof, and a mirror had been created in which all that grew on the ceiling was reflected in the still water below.Under water that was clear as grass the pool was carpeted with green sponge. Gray patches of sea squirts glistened on the ceiling and colonies of soft coral were a pale apricot color. In the moment when I looked into the cave a little elfin starfish hung down, suspended by the merest thread, perhaps by only a single tube foot. It reached down to touch its own reflection, so perfectly delineated that there might have been, not one starfish, but two. The beauty of the reflected images and of the limpid pool itself was the poignant beauty of things that are ephemeral, existing only until the sea should return to fill the little cave.在海边雷切尔·卡森海岸是一个年代久远的世界。
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翻译文献：INVESTIGATION ON DYNAMIC PERFORMANCE OF SLIDE UNIT IN MODULAR MACHINE TOOL （对组合机床滑台动态性能的调查报告）文献作者：Peter Dransfield,出处：Peter Dransfield, Hydraulic Control System-Design and Analysis of TheirDynamics, Springer-Verlag, 1981翻译页数：p139—144英文译文：对组合机床滑台动态性能的调查报告【摘要】这一张纸处理调查利用有束缚力的曲线图和状态空间分析法对组合机床滑台的滑动影响和运动平稳性问题进行分析与研究，从而建立了滑台的液压驱动系统一自调背压调速系统的动态数学模型。
通过计算机数字仿真系统，分析了滑台产生滑动影响和运动不平稳的原因及主要影响因素。
从那些中可以得出那样的结论，如果能合理地设计液压缸和自调背压调压阀的结构尺寸.本文中所使用的符号如下：s1-流源，即调速阀出口流量；S el—滑台滑动摩擦力R一滑台等效粘性摩擦系数：I1—滑台与油缸的质量12—自调背压阀阀心质量C1、c2—油缸无杆腔及有杆腔的液容；C2—自调背压阀弹簧柔度；R1, R2自调背压阀阻尼孔液阻，R9—自调背压阀阀口液阻S e2—自调背压阀弹簧的初始预紧力；I4, I5—管路的等效液感C5、C6—管路的等效液容：R5, R7-管路的等效液阻；V3, V4—油缸无杆腔及有杆腔内容积；P3, P4—油缸无杆腔及有杆腔的压力F—滑台承受负载，V—滑台运动速度。
本文采用功率键合图和状态空间分折法建立系统的运动数学模型，滑台的动态特性可以能得到显著改善。
一、引言在组合机床正常工作中，滑台运动速度的大小和它的方向以及所承受负载的变化都将以程度不同地影响其工作性能。
特别是在工进过程中。
滑台上负载的突然消失引起的前进以及负载的周期性变化而引起的运动不平稳性，都将影响被加工件的表面质量，在严重的情况下会使刀具折断掉。
根据大连机床厂要求，作者采用有束缚力的曲线图和状态空间分析法建立组合机床滑台的新型液压驱动系统一自调背压调速系统的动态数学模型。
为了改善滑台的动态特性，有必要去分析找出滑台产生前冲和运动不平稳的原因以及主要的影响因素，但那必须通过计算机数字仿真和研究得出最后的结果。
二、动态数学模型组合机床滑台的液压驱动系统一自调背压调速系统的工作原理图如图I所示。
这个系统是用来完成"工进一停止一快退”的工作循环。
当滑台在工进时，三位四通换向阀处于图示右位，油泵的供油压力在滥流阀的有效作用下近似地几乎保持恒定，该油液流经过换向阀和调速阀后进入油缸的无杆腔，以推动滑台向前移动；与此同时，从油缸有杆腔排出的压力油经自调背压阀和换向阀流回油箱了。
在这个过程中，两个单向阀和溢流阀的工作状态始终都没有任何变化。
对与象组合机床滑台的液压驱动系统一自调背压调速系统这样的复杂非线性的系统，为了便于研究它的动态特性，建立一个仅着重考虑主要影响因素的合理简单的动态数学模型是尤其重要的[1][2]。
从理论分析和试验研究的列举中可以得知：该系统的过程时间是远大于调速阀的过程时间的，当油缸无杆腔有效承压面积很大时，调速阀出口流量的瞬时的超调反映为滑台运动速度的变化是很小的[2]。
为了更加拓宽和深入研究系统的动态特性，使研究工作能在微型计算机上有效地进行，本文章对原模型[2]做进一步简化处理，假定调速阀在系统的整个通过过程中输出时候恒定的流量，这被看作其为流源。
这样，系统的动态模型的结构简图如图2所示，它是由油缸、滑台，自凋背压阀和联接管路等组成。
功率键合图是一功效流图，它是按着系统的能量传递方式，以实际结构为基础，用集中参数把子系统之间的作用关系抽象地表示为阻性元R、容性元C和感性元I 的三种作用元。
采用这种方法建模物理概念清晰，结合状态空间分析法可以较准确地描述和分析线性系统，该方法在时域中研究复杂非线性系统动态特性的一种有效的方法。
根据自调背压调速系统各元件的主要特性和建模规则[1]，得出了图3所示的系统的功率键合图。
图中每根键上的半箭头表示功率流向，构成功率的两个变量是力变量（油压P或作用力F）和流变量（流量q或速度v）。
O结点表示在系统中属于并联连接，各键上的力变量相等而流变量之和为零；1结点表示在系统中属于串联连接，各键上流变量相等而力变量之和为零。
TF表示不同能量形式间的变换器，TF 下标注的字母表示力变量或流变量的转换比值。
键上的短横杠表示该键上两变量间的因果关系。
全箭头表示控制关系。
在三种作用元中容性元和感性元的力变量与流变量之间具有积分或微分关系，因此，根据图3可推导出具有九个状态变量的复杂非线性状态方程。
本文对滑台动态特性的研究是从滑台的前冲和运动平稳性两方面入手，用四阶定步长Runge-Kutta法在IBM-PC微型计算机上进行数字仿真,仿真结果分别如图4和图5所示。
三、滑台前冲滑台前冲现象是作用在滑台上的负载突然消失（如钻削工作的情况)引起的。
在此过程中，滑台的负载F、运动速度V、油缸两腔压力P3和P4的变化可从图4仿真结果看出。
当滑台在负载的作用下匀速运动时，油缸无杆腔油液压力较高．油液中聚集了大量的能量。
当负载突然消失时，该腔油压随之迅速降低，油液从高压态转入低压态的过程中向系统释放很多能量，致使滑台高速向前冲击。
然而，滑台的前冲使油缸有杆腔油液受压引起背压升高，从而消耗掉系统中的一部分能量，对滑台的前冲起到一定的抑制作用。
应当看到，在所研究的系统中，自调背压阀的入口压力要受到油缸两腔油压的综合性作用。
在负载消失的瞬间，自调背压阀的压力将会迅速地上升，并稳定地处在高于初始背压的数值以上。
从图中可见，自调背压调速系统在负载消失瞬间油缸背压力升高的幅度大于传统的调速系统，所以，其油缸有杆腔中油液吸收的能量就多；结果，滑台的前冲量比传统调速系统要小大约20%。
可见采用自调背庄调速系统作为驱动系统的滑台在抑制前冲方面具有良好的特性，其中自调背压阀起了很大作用。
四、滑台的运动平稳性当作用于滑台上的负载作周期变化时（比如说铣削加工的情况），滑台的运动速度将要产生一定的波动。
为于保证加工质量的要求，必须尽可能地减小其速度波动的范围。
而从讨论问题的方便性出发来说，假设负载按正弦波的规律变化，从而得到的数字仿真结果如图5所示。
由此可见这个系统与传统的调速系统有着相同的变化规律以及非常接近的数值数字。
其中的原因是负载的变化幅度不大，油缸两腔的压力也就没有较大变化，从而最终导致自调背压阀的作用不够明显显示。
五、改善措施通过研究的结果表明，以自调背压调速系统作为驱动系统的滑台，其动态特性要比传统的调速系统好的。
要减少滑台的前冲量，就必需在负载消失的瞬间时候迅速提高油缸有杆腔的背压力；要提高滑台的运动平稳性就需增加系统的刚性，主要措施在于减小油液的体积。
从系统的结构得知，油缸有杆腔与排油管之间有一很大的容积，如图6a所示。
它的存在方面延迟和衰减了自调背压阀的作用，另一方面也降低了系统的刚性，它会限制了前冲特性和运动平稳性的进一步改善。
因此，改善滑台动态特性可从两个方法进行处理：即改变油缸容积和改变自调背压阀结构尺寸。
通过一系统结构性参数的仿真计算以及结果的比较可以得出这样的结果：当把油缸有杆腔与排油管间容积V4同无杆腔与进油管间容积V3之比由原来的5.5改为1时，如图6b所示，同时，把自调背压阀阀芯底端直径由原来的10mm增加为13mm,阻尼三角槽边长从原来的lmm减小到0.7mm时，可使滑台的前冲量减小30%,过渡过程时间明显缩短了，滑台的运动平稳性也将会得到很大的改善。
六、结论通过理论上的分析和计算机仿真研究实验,很明显的是自调背压调速系统作为组合机床滑台的驱动系统是很有推广使用价值的。
影响滑台动态特性的主要因素是油缸内部结构性和自调节背压阀的尺寸。
假如能对其进行合理设计，可使滑台的动态特性得到显著地改善。
同时，也说明了采用有束缚力的曲线图和状态空间分析法研究复杂非线性液压系统的动态特性是既方便又有效的方法。
【附】英文原文翻译文献：INVESTIGATION ON DYNAMIC PERFORMANCE OF SLIDE UNIT IN MODULAR MACHINE TOOL （对组合机床滑台动态性能的调查报告）文献作者：Peter Dransfield,出处：Peter Dransfield, Hydraulic Control System-Design and Analysis of TheirDynamics, Springer-Verlag, 1981翻译页数：p139—144INVESTIGA TION ON DYNAMIC PERFORMANCE OF SLIDE UNIT IN MODULAR MACHINE TOOLPeter DransfieldThis paper deals with the investigation for slide unit's impact and motion stabil-ity in modular machine tool fay means of the method of power bond graph and state space analysis. The dynamic mathematical model of self-adjusting back pressure speed control system used to drive slide unit is established. Main reasons and affect-ing factors for slide unit impact and motion unstability are analysed through compu-ter digital simulation, It is concluded from those that, if the structural dimensions of hydraulic cylinder and back pressure valve are designed rationally, the slide unit's dynamics will markedly be improved.NOMENCLATURESf flow sourceSei sliding friction force in slide unitR equivalent viscous friction coefficient in slide unitIi mass of slide unit and cylinderh mass of SABP valve spoolCi,C2hydraulic capacitances of rod chamber and non-rod chamber in cylinder re-spec-tivelyC3spring compliance of SABP valveR]r R2hydraulic resistances of damping holesR9hydraulic resistance of orifice of SABP valveSe2presetting force of spring in SABP valveI4J5equivalent liquid inertia in pipe linesC^Cg equivalent hydraulic capacitances in pipe linesequivalent hydraulic resistances in pipe linesV-j V^oil-containing volumes in non-rod chamber and rod chamber respectivelyP,r:, P-i oil pressures in non-rod chamber and rod chamber respectivelyF load acted on slide unitV slide unit velocity* Department of Mechanical Engineering, Dalian Ur.iversity of Technology, Dalian. China.INTRODUCTIONDuring operation of modular machine tool, the changes of slid unit's speed and load acted on it in both magnitude and direction will affect working performar.ee to a different extent Particularly the impact caused by sudden vanishing of load and the motion unstability due to periodical change of load in operation will affect the surface quality of the workpiece machined, and the tool would be broken off under serious conditions, By using the method of power bond graph and state space analysis, the dynamic mathematical model of the system used to drive slide unit is established, that is called as self-adjusting back pressure speed control system and abbreviated to SABP system. In order to improve slide unit's dynamics, it is necessary to find out the main reasons and affecting factors, that must be based on computer digital simulation and study on the results.DYNAMIC MATHEMATICAL MODELThe schematic diagram of SABP system is shown in Fig.l, the system is used to perform the cycle of feeding, stopping and returning. Four way control valve works in the right position during slide unit's feeding. The supply pressure of the pump is approximately constant under the action of pressure relief valve, the oil through the control valve and pressure compensated flow control valve enters the non-rod chamber to put slide unit forward. At the same time, the oil from the rod chamber is discharged through SABP valve and directional control valve to tank. In this process, the state of two check valves and pressure relief valve is not changed, To establish the mathematical model as reasonably and simply as possible, consid-eration must be focused on main affecting factors for a complex non-linear system such as the SABP system. It is illustrated by theoretical analysis and test result ' , that the transient time of the system is much longer than that of the flow control valve, and the flowrate overshoot of the valve in transients affects very small to slide unit speed because of the ;large effective sectional area of non-rod chamber in cylinder. For investigating the system's dynamics widely and deeply, the initial mod-el tn is further simplified in this paper, and so the study can be efficiently made with microcomputer. It is assumed that the flowrate through the flow control valve isconstant in the whole transient process, and is denoted to a flow source.Fig.2 shows the structure diagram of the dynamic model of the system, it is composed of cylin-der, slide unit, SABP valve and pipe line; etc.By using the method of power bond graph and state space analysis in this paper, the dynamic mathematical model of the system is to be established- The power bond graph is a power flow diagram, which expresses abstractly the actions among sub-systems as three effects, i.e. resistance effect, capacitive effect and inertia effect, according to the way of energy transform, on the basis of practical structure and by means of method of lumped parameters. The model is characterized by a clear con-ception in physics, and non-linear system can be accurately analysed in combination with method of state space analysis, thus it is a effective method used in the dyna-mic investigation of complex non-linear system in the'timedomain.From main performances of components in SAEP system, the power bond graph of the system has been formed by means of the rule of model establishing ' and is shown in Fig.3. Half arrow in each bond indicates a direction of power How, two variahles of power are effort variable and flow variable. O-junction illustrates algebraic summation of flow variables at common effort, i.e. parallel connection, 1-junction does algebraic summation of effort variables at common flow, i.e. series connection. The symbol TF represents power transformer between two types of energy, and transforming modulus between efforts or flows is noted below the symbol TF. Short transverse bar across one end of each bond shows causality between two variables. A full arrow expresses a control action. Among three actions, there is an integration or differential form in capacitive effect and inertia effect between two variables. So state equation may be derived from Fig.3, there are nine state variables in this complex nonlinear equation. Studying on the slide unit's dynamics is started with impact and motion stability. The equation is simulated by using the method of 4th order Runge-Kutta integration procedure on IBM-PC computer. Fig.4 and Fig.5 illustrate the results respectively.SLIDE UNIT IMPACTSlide unit's impact phenominon results from load's vanishing in the transients, ■ for example, the situation of drilling through workpiece, Fig.4 expounds the variations of the load and speed of slide unit, the pressures of chambers in cylinder. When slide unit motions evenly under the action of load, the oil pressure in non-rod chamber is very high, and there is a lot of hydraulic energy accumulated in side. The pressure decreases at once with load's discharging rapidly. During the process of oil pressure converting from high to low, the system absorbs some of the energy, so slide unit impacts forward with high speed. And then the oil in rod chamber is141compressed to increase back pressure, some of the energy is consumed, which plays a part of restraining the impact of the slide unit. It must be noted that inlet pressure of SABP valve telys on the interaction of pressures of two chambers, and increases rapidly at the instant of load's vanishing, and then stabilizes at some value greate r than initial one. This pressure is also greater than one of traditional speed control system, therefore the energy can be absorbed much more in the rod chamber. In result, the impact of slide unit in SABP system is 20% lawer than in traditional's. It is thus clear that slide unit with SABP system for driving has a good performance in restraining the impact and SABP valve plays an important part in that,MOTION STABILITYWhen load acting on slide unit varies periodically, such as the situation of mill-ing, slide unit's speed will bring about some pulse. In order to meet the requirements of manufacturing quality, the magnitude of the speed pulse must be reduced as small as possible. The variation of the load is assumed to be of sine wave, in order to sim-plify discussion of the problem, The result of digital simulation is shown in Fig.5 It can be seen that, the response of the system is the sameas traditionl's and the differ-ences between them are very small. The reason for this is that the variation of the load is not targe, there the pressures in chambers vary very little that is, the effect of the SABP valve is not obvious.IMPROVEMENTIt is shown by studying, that dynamics of slide unit which used SABP speed control system as driving system is better than that of traditional system. To reduce the slide unit's impact, the back pressure of rod chamber has to be increased rapidly in the transients of load's vanishing; on the other hand, to enhance the slide unit's motion stability, it is necessary to raise the system rigidity. However, main recom-mendation lies in decreasing the volume of oil. It is known from system structure that, there is a lot of oil-containing volume between the rod chamber and drain pipe as shown in Fig.6a. Because the volume exists, not only the effect of SABP valve is delayed and reduced, hut also the rigidity of the system is decreased. Therefore, it is hindered to further improve the impact and motion stability. To make the slide unit dynamics better, the structural dimensions of cylinder's chamber and the SABP valve must be designed suitably. Based on simulations under the various structural dimensions and comparison among the results, the following two measures can be taken for improvements:the ratio between volumeV4 and V3 is changed from 5.5 to 1 approximately, as shown in Fig,6b;142the bottom diameter of spool of the SABP valve is increased from 10 mm to 13 mm and.the length of side of triangular damping slot is decreased from 1 mm to 0.7mm the slide unites impact quantity can be reduced by 30%, and the time of dynamic response is shortened. In addition, slide unit's motion stability may be improved obviously. It is thus evident that improvements are very effective.CONCLUSIONSBy the way of theoretical analysis and computer simulating investigation, it is obvious that the SABP speed control system used as slide units driving system in modular machine tool is valuable for popularization and utilization, Main factors affecting the slide unit dynamics are the structural dimensions of the cylinder and the SABP valve. In the case of rationally designing, the slide unit dynamics may be obviously improved. Meanwhile, it is shown that the method of power bond graph and state space analysis is a very convenient and effective method in studying dynamics of complex non-linear hydraulic system.REFERENCES[1] Peter dransfield Hydraulic Control System-Design and Analysis of TheirDynamics Springer-Verlag, 1981[2] Dong Bengang, Zhang Zhixiang, Investigation on impact property ofselfadjusting back pressure speed control system. Machine tool & Hydraulics No.2, 1987 GuangZhou, China, (in Chinese).。