英文翻译与英文原文.陈--
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—144
INVESTIGA TION ON DYNAMIC PERFORMANCE OF SLIDE UNIT IN MODULAR MACHINE TOOL
Peter Dransfield
This 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.
NOMENCLATURE
Sf flow source
Sei sliding friction force in slide unit
R equivalent viscous friction coefficient in slide unit
Ii mass of slide unit and cylinder
h mass of SABP valve spool
Ci,C2hydraulic capacitances of rod chamber and non-rod chamber in cylinder re-spec-tively
C3spring compliance of SABP valve
R]r R2hydraulic resistances of damping holes
R9hydraulic resistance of orifice of SABP valve
Se2presetting force of spring in SABP valve
I4J5equivalent liquid inertia in pipe lines
C^Cg equivalent hydraulic capacitances in pipe lines
equivalent hydraulic resistances in pipe lines
V-j V^oil-containing volumes in non-rod chamber and rod chamber respectively
P,r:, P-i oil pressures in non-rod chamber and rod chamber respectively
F load acted on slide unit
V slide unit velocity
* Department of Mechanical Engineering, Dalian Ur.iversity of Technology, Dalian. China.
INTRODUCTION
During 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 MODEL
The 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 is
constant 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 IMPACT
Slide 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 is
141
compressed 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 STABILITY
When 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.
IMPROVEMENT
It 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;
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the 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.
CONCLUSIONS
By 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 Their
Dynamics Springer-Verlag, 1981
[2] Dong Bengang, Zhang Zhixiang, Investigation on impact property of
selfadjusting back pressure speed control system. Machine tool & Hydraulics No.2, 1987 GuangZhou, China, (in Chinese).
英语原文及其翻译
Exploring Filipino School Counselors’ Beliefs about Learning Allan B. I. Bernardo [Abstract] School reform efforts that focus on student learning require school counselors to take on important new roles as advocates of student learning and achievement.But how do school counselors understand the process of learning? In this study, we explore the learning beliefs of 115 Filipino school counselors who indicated their degree of agreementwith 42 statements about the process of learning and the factors thatinfluence this process.A principal components analysis of the responses to the 42 statements suggested three factors:(F1)social-cognitive constructivist beliefs, (F2) teacher-curriculum-centered behaviorist beliefs,and (F3) individual difference factors.The preliminary results are briefly discussed in terms of issues related to how Filipino school counselors’ conceptions of learning may guide their strategies for promoting student learning and achievement. [Key words]beliefs about learning, conceptions of learning, school counselors, student learning, Philippines School reform efforts in different parts of the world have focusedon students’learning. In particular,most school improvement programsnow aim to ensure that students acquire the high-level knowledge and skills that help them to thrive in today’s highly competitive globaleconomy (e.g., Lee & Williams, 2006). I n this regard, school reform programs draw from various contemporary theories and research on learning (e.g.,Bransford,Brown, & Cocking, 1999; Lambert & McCombs, 1998).The basic idea is that all school improvement efforts should be directed at ensuring students achieve high levels of learning or attainment of well-defined curricular objectives and standards.For example, textbooks (Chien & Young, 2007), computers and educational technology (Gravoso, 2002; Haertnel & Means, 2003;Technology in Schools Task Force, 2003), and educational assessment systems (Black & Wiliam2004; Cheung & Ng, 2007; Clark, 2001; Stiggins, 2005) are being reconsidered as regards how they can effectively provide scaffolds and resources for advancing student learning. Likewise,the allocation and management of a school’s financial resources are assessed in terms ofwhether these are effectively mobilized and utilized towards improving student learning (Bolam, 2006; Chung & Hung, 2006; Retna, 2007). In this regard, some advocates have also called for an examination of the role of school counselors in these reform efforts (Herr, 2002). Inthe United States, House and Hayes (2002) challenged school counselors to take proactive leadership roles in advocating for the success of all
蓝梅主编 给排水科学与工程专业英语部分课文翻译中文版
第四单元给水系统 一般来说，供水系统可划分为四个主要组成部分:（1）水源和取水工程（2）水处理和存储（3）输水干管和配水管网。常见的未处理的水或者说是原水的来源是像河流、湖泊、泉水、人造水库之类的地表水源以及像岩洞和水井之类的地下水源。修建取水构筑物和泵站是为了从这些水源中取水。原水通过输水干管输送到自来水厂进行处理并且处理后的出水储存到清水池。处理的程度取决于原水的水质和出水水质要求。有时候，地下水的水质是如此的好以至于在供给给用户之前只需消毒即可。由于自来水厂一般是根据平均日需求流量设计的，所以，清水池为水需求日变化量提供了一个缓冲区。 水通过输水干管长距离输送。如果输水干管中的水流是通过泵所产生的压力水头维持的，那么我们称这个干管为增压管。另外，如果输水干管中的水流是靠由于高差产生的可获得的重力势能维持的，那么我们称这个干管为重力管。在输水干管中没有中间取水。与输水干管类似，在配水管网中水流的维持要么靠泵增压，要么靠重力势能。一般来说，在平坦地区，大的配水管网中的水压是靠泵提供的，然而，在不平坦的地区，配水管网中的压力水头是靠重力势能维持的。 一个配水管网通过引入管连接配水给用户。这样的配水管网可能有不同的形状，并且这些形状取决于这个地区的布局。一般地，配水管网有环状或枝状的管道结构，但是，根据当地城市道路和街区总体布局计划，有时候环状和枝状结构合用。城市配水管网大多上是环状形式，然而，乡村地区的管网是枝状形式。由于供水服务可靠性要求高，环状管网优于枝状管网。 配水管网的成本取决于对管网的几何形状合适的选择。城市计划采用的街道布局的选择对提供一个最小成本的供水系统来说是重要的。环状管网最常见的两个供水结构是方格状、环状和辐射状；然而，我们不可能找到一个最佳的几何形状而使得成本最低。 一般地，城镇供水系统是单入口环状管系统。如上所说，环状系统有一些通过系统相互连接的管道使得通过这些连接接的管道，可以供水到同一个需水点。与枝状系统不同，在环状系统中，由于需水量在空间和时间上的变化，管道中的水流方向并非不变。 环状管网可为系统提供余量，提高系统应对局部变化的能力，并且保证管道故障时为用户供水。从水质方面来说，环状形状可减少水龄，因此被推广。管道的尺寸和配水系统的设计对减少水龄来说是重要的因素。由于多方向水流模式和系统中流动模式随时间的变化，水不会停留在一个地方，这样减少了水龄。环状配水系统的优缺点如表4.1所述。 优点:1.Minimize loss of services.as main breaks can be isolated due to multidirectional flow to demand points.2.Reliability for fire protection is higher due to redundancy in the system.3.Likely to meet increase in water demand -higher capacity and lower velocities.4.Better residual chlorine due to in line mixing and fewer dead ends. 5.Reduced water age. 在文献中曾记载过，只考虑最低成本设计的环状管网系统会转化成树状似的结构，这一做法导致在最终的设计中失去最初的几何形状。环状保证了系统的可靠性。因此，一个只考虑最低成本为依据的设计打败了在环状管网中所提供的基本功能。有文献记载设计环状管网系统的方法。尽管这个方法也是仅以考虑最低成本为基础，它通过对管网中所有管道最优化规划从而保持了管网的环状结构。
文献翻译英文原文
https://www.sodocs.net/doc/1010907978.html,/finance/company/consumer.html Consumer finance company The consumer finance division of the SG group of France has become highly active within India. They plan to offer finance for vehicles and two-wheelers to consumers, aiming to provide close to Rs. 400 billion in India in the next few years of its operations. The SG group is also dealing in stock broking, asset management, investment banking, private banking, information technology and business processing. SG group has ventured into the rapidly growing consumer credit market in India, and have plans to construct a headquarters at Kolkata. The AIG Group has been approved by the RBI to set up a non-banking finance company (NBFC). AIG seeks to introduce its consumer finance and asset management businesses in India. AIG Capital India plans to emphasize credit cards, mortgage financing, consumer durable financing and personal loans. Leading Indian and international concerns like the HSBC, Deutsche Bank, Goldman Sachs, Barclays and HDFC Bank are also waiting to be approved by the Reserve Bank of India to initiate similar operations. AIG is presently involved in insurance and financial services in more than one hundred countries. The affiliates of the AIG Group also provide retirement and asset management services all over the world. Many international companies have been looking at NBFC business because of the growing consumer finance market. Unlike foreign banks, there are no strictures on branch openings for the NBFCs. GE Consumer Finance is a section of General Electric. It is responsible for looking after the retail finance operations. GE Consumer Finance also governs the GE Capital Asia. Outside the United States, GE Consumer Finance performs its operations under the GE Money brand. GE Consumer Finance currently offers financial services in more than fifty countries. The company deals in credit cards, personal finance, mortgages and automobile solutions. It has a client base of more than 118 million customers throughout the world
建筑工程及给排水专业中英文对照翻译
Laminar and Turbulent Flow Observation shows that two entirely different types of fluid flow exist. This was demon- strated by Osborne Reynolds in 1883 through an experiment in which water was discharged from a tank through a glass tube. The rate of flow could be controlled by a valve at the outlet, and a fine filament of dye injected at the entrance to the tube. At low velocities, it was found that the dye filament remained intact throughout the length of the tube, showing that the particles of water moved in parallel lines. This type of flow is known as laminar, viscous or streamline, the particles of fluid moving in an orderly manner and retaining the same relative positions in successive cross- sections. As the velocity in the tube was increased by opening the outlet valve, a point was eventually reached at which the dye filament at first began to oscillate and then broke up so that the colour was diffused over the whole cross-section, showing that the particles of fluid no longer moved in an orderly manner but occupied different relative position in successive cross-sections. This type of flow is known as turbulent and is characterized by continuous small fluctuations in the magnitude and direction of the velocity of the fluid particles, which are accompanied by corresponding small fluctuations of pressure. When the motion of a fluid particle in a stream is disturbed, its inertia
英文翻译(原文)
GRA VITY RETAINING?WALL 1. INTRODUCTION Retaining walls are structures used to provide stability for earth or other material where conditions disallow the mass to assume its natural slope, and are commonly used to hold back or support soilbanks,coal or ore piles, and water. Retaining walls are classified, based on the method of achieving stability, into six principal types (Fig.1). The gravity-wall depends upon its weight, as the name implies, for stability. The cantilever wall is a reinforced-concrete wall that utilizes cantilever action to retain the mass behind the wall from assuming a natural slope. Stability of this wall is partially achieved from the weight of soil on the heel portion of the base slab. A counterfort retaining wall is similar to a cantilever retaining wall, except that it is used where the cantilever is long or for very high pressures behind wall and has counterforts, which tie the wall and base together, built at intervals along the wall to reduce the bending moments and sheers. As indicated in Fig.1c, the counterfort is behind the wall and subjected to tensile forces. A buttressed retaining wall is similar to a counterfort wall, except that the bracing is in front of the wall and is in compression instead of tension. Two other types of walls not considered further are crib walls, which are built-up members of pieces of precast concrete, metal, or timber and are supported by anchor pieces embedded in the soil for stability, and semigravity walls, which are walls intermediate between a true gravity and a cantilever wall. (a)(b)(e)
英语原文及翻译
高速视频处理系统中的信号完整性分析 摘要：结合高速DSP图像处理系统讨论了高速数字电路中的信号完整性问题，分析了系统中信号反射、串扰、地弹等现象破坏信号完整性的原因，通过先进IS工具的辅助设计，找出了确保系统信号完整性的具体方法。 关键词：高速电路设计信号完整性 DSP系统 深亚微米工艺在IC设计中的使用使得芯片的集成规模更大、体积越来越小、引脚数越来越多；由于近年来IC工艺的发展，使得其速度越来越高。从而，使得信号完整性问题引起电子设计者广泛关注。 在视频处理系统中，多维并行输入输出信号的频率一般都在百兆赫兹以上，而且对时序的要求也非常严格。本文以DSP图像处理系统为背景，对信号完整性进行准确的理论分析，对信号完整性涉及的典型问题[1]——不确定状态、传输线效应、反射、串扰、地弹等进行深入研究，并且从实际系统入手，利用IS仿真软件寻找有效的途径，解决系统的信号完整性问题。 1 系统简介 为了提高算法效率，实时处理图像信息，本图像处理系统是基于DSP+FPGA结构设计的。系统由SAA7111A视频解码器、TI公司的TMS320C6701 DSP、Altera公司的EPlK50QC208 FPGA、PCI9054 PCI接口控制器以及SBRAM、SDRAM、FIFO、FLASH等构成。FPGA是整个系统的时序控制中心和数据交换的桥梁，而且能够对图像数据实现快速底层处理。DSP是整个系统实时处理高级算法的核心器件。系统结构框图如图1所示。 在整个系统中，PCB电路板的面积仅为15cm×l5cm，系统时钟频率高达167MHz，时钟沿时间为0．6ns。由于系统具有快斜率瞬变和极高的工作频率以及很大的电路密度，使得如何处理高速信号问题成为一个制约设计成功的关键因素。 2 系统中信号完整性问题及解决方案 2．1 信号完整性问题产生机理 信号的完整性是指信号通过物理电路传输后，信号接收端看到的波形与信号发送端发送的波形在容许的误差范围内保持一致，并且空间邻近的传输信号间的相互影响也在容许的范围之内。因此，信号完整性分析的主要目标是保证高速数字信号可靠的传输。实际信号总是存在电压的波动，如图2所示。在A、B两点由于过冲和振铃[2]的存在使信号振幅落入阴影部分的不确定区，可能会导致错误的逻辑电平发生。总线信号传输的情况更加复杂，任何一个信号发生相位上的超前或滞后都可能使总线上数据出错，如图3所示。图中，CLK为时钟信号，D0、D1、D2、D3是数据总线上的信号，系统允许信号最大的建立时间[1]为△t。在正常情况下，D0、D1、D2、D3信号建立时间△t1<△t，在△t时刻之后数据总线的数据已稳定，系统可以从总线上采样到正确的数据，如图3(a)所示。相反，当信号D1、D2、D3受过冲和振铃等信号完整问题干扰时，总线信号就发生
水文与水资源专业英语文章翻译
3单元 地下水位的高低可在一年内大幅波动，下降和上升后，在干燥的季节，降水期。因此，为了保证连续供水，井应穿透许多米水位以下。当水从井里抽水，它在水面产生抑郁，大致锥形的形状，称为漏斗。如果抽重，水表不仅可以降低周围的好但还可延伸到大面积。这在美国西部的部分是这样的。在这种情况下，可以说，地下水被“开采”。即使抽人立即停止，它可能需要数百年的地下水得到补充。下面的例子说明了这一点： 例如，在干燥的美国西南部，含水层补给是每年只有1英寸深的水的十分之二点位置。在这些地区，这是不寻常的泵两英尺或更多的水用于灌溉和其他用途的每年。在这个简单的例子，如果整个含水层抽水的速度，每年的开采量将相当于120年和十年的补给，泵将1200年积累的水。在泵送期间新补给可以忽略不计。机械问题和经济因素阻止完全脱水的含水层，但原则上是有效的例子。 短期承压是适用于任何情况，地下水位上升，在一个以上的水平，这是最初遇到的。这样的情况发生，两个条件必须满足：（1）水，必须限制在一个含水层，是倾斜的，一端暴露在表面，在那里可以得到水；和（2）防渗层，上面和下面的含水层，必须防止水逃避，这样一层被窃听，被上面的水的重量产生的压力会使水上升。如果没有摩擦，井里的水会上升到顶部的水位。含水层。 自流系统作为管道，将水从很远的偏远地区的充电放电点。这样水倒在威斯康星州中部年前现在是从地面和社区许多英里远，伊利诺斯。在南达科他州这样的系统已经从西部的黑山带水，向东跨越国家。在不同的尺度上，城市供水系统可能是人为的自流系统的例子。水塔，为抽水，可能是补给区，管道的承压含水层，在家中的自流井的水龙头。 4单元 矿产勘查在世界表明温度在深油、矿产品通常会增加在地表以下深度增加。在这样的情况下增加温度约0.6度，平均每30米。因此，当地下水在深循环，它变得激烈，如果它上升到表面，水是温泉。一些温泉水在美国，特别是在东部，加热这种方式。在美国，绝大多数的温泉发现于西方。这种分布的原因是，大部分温泉的热源是冷却的火成岩，它是在西方，火成活动已经最近。 间歇泉是间歇性的温泉或喷泉，水柱喷射的伟大力量在不同的时间间隔，通常上升30-60米。水流停止后，一列蒸汽冲出，通常以雷鸣般的轰鸣声。这或许是世界上最著名的间歇泉是黄石公园的老忠实喷发，大约每小时一次。间歇泉也在世界的其他地区，包括冰岛和新西兰，在那里长期间歇泉，意为“喷泉”或“井喷”这个词。 间歇泉时，地下水是地下室加热。室底部，水在巨大的压力下，由于上覆水的重量。因此，一个100度以上的温度就会沸腾所需的前。例如，在一个300米的室内水下必须达到一个温度近230度才开。加热使水膨胀，其结果是某些流出的顶部。这减少了压力，和水变成蒸汽，使间歇泉喷发。 从温泉和间歇泉地下水通常包含在解决方案比其他来源的地下水多材料因为热水比冷水更有效的溶解。当水中含有大量溶解的二氧化硅，硅华沉积在春天。石灰石，方解石的一种，是在石灰岩地区温泉特色存款。一些温泉含硫磺。除了使水的味道不好，硫发出难闻的气味。毫无疑问，臭蛋的春天，内华达州，这种情况。 11单元 一种污染物，是任何物质，生物或化学。在一个可识别的过量的有害的其他理想的生物。在这个框架内，过量的重金属如发汞；某些放射性同位素；氮，磷，钠；和其他有用的，甚至是必要的元素，以及某些致病性细菌和病毒污染物。在某些情况下，材料可作为一种污染物，世界人口中的一段特别的虽然它对其他部分不被认为是有害的。例如，在适当的复合氮超标有害于婴儿，但少了很多成年人如果在所有。在这样的方式，过多的钠盐通常不是有害的，但它可以制约医疗原因盐的摄入饮食的某些人。 不同的物理，地质，生物环境与地下水污染与地表水污染相比是显著的。在后者中，流量和氧气和阳光可用液压，随着速度的过程中污染物的稀释和扩散发生，明显不同于地下水，在污染物降解菌的机会通常局限于土壤或几英尺以下。此外，通过何种渠道地下水运动是非常小的和可变的。由此，显而易见的是，移动速度大大降低，除非，也许，在大的解决渠道内石灰石，以及分散和稀释的机会是非常有限的。此外，地下水通常缺乏氧气，这是造成好氧微生物的种类有帮助但这可能提供了一个“幸福之家”厌氧品种。 大多数土壤和岩石物理过滤出固体的能力，包括污染的固体，是公认的。然而，这种能力会随不同的大小，形状，和滤料颗粒的安排，在选定的沙子和其他材料在水过滤厂使用证明。也知道，但也许不那么普遍，是粘土和其他矿物捕获和交换的一些元素和化合物的能力时，他们游离在溶液中的正或负电荷的元素或化合物。这样的交流，随着吸附和沉淀过程中，污染物的捕获是重要的。这些过程有能力定义的单位是可逆的。他们也可以很容易地在设计设施正确的污染问题所依托的地质环境，土壤和岩石忽视治疗；这种疏忽可能造成地下水污染。这是特别重要的在污水土地应用。 很多猜测，争论，研究发生的地下水污染。地下水污染的主要关注的是化学元素，化合物的引入，和微生物，不含水层，可用于饮用水或是自然发生的，不仅因为该含水层的降解也因为在检测的难度，长期居住，和难度和费用含水层恢复。强有力的论点是，任何废物或可能的污染物应允许进入地下水系统的任何部分。这是一个不可能实现的梦想。相反，答案在于更多的了解自然过程处理废弃物的保证时，土壤和岩石是不能够处理，存储，或回收废物，我们可以发展过程使污染物处理，储存，或可回收。 Extracting and distinguishing environmental change information with high resolution form groundwater and sediments of groundwater system has been the major trend of groundwater sciences towards environmental sciences, This is very useful for forecasting environmental change.4从地下水及其沉积物中提取高分辨率的环境变化信息，实现对环境变化的预警功能是地下水科学向环境科学延伸的重要方向。5而随着全球淡水资源紧缺的形势不断恶化，全球环境变化，特别是全球气候变化对地下水资源的影响成为水文地质研究的新课题。5 With fresh water shortage increasingly serious, the research on effect of globle environmental change, especially globle climate change in groundwater resource has become a new area for hydrogeological research. 4depleted in K and SO4 井的出水量与含水层的渗透系数成正比。 Well water yield is proportional to the transmissivity of a aquifer. 1、分布在这个深层碳酸岩含水层中的地下热水的温度是60℃-90℃。 2、Temperature of the thermal groundwater in the deep-seated carbonate aquifer occurring in this area ranges from 60℃ 3、所有观测井水位的季节性波动可以用研究区降水量的季节性变化来解 4、Seasonal fluctuations in water table in observation wells are interpreted by seasonal changes of/in precipitation in study areas.
科普版英语六年级下册课文及翻译 (直接打印版)
Lesson 1 I’m not feeling well. Let’s talk （M=Mom, T= Tom） M: What,'s the matter, Tom T: I'm not feeling well, Mom M: Do you have a cold T: Yes, I think so. Could you give me some water, please M: Here you are. T: Thank you, Mom. M: Tom, you must go and see a doctor. T: OK, Mom. M: It's cold outside. You must wear your coat. T: OK, Mom. Could you pass me my coat,please M: Here you are. T: Thank you, Mom M: Tell me your teacher's number. I'll call him and tell him you are sick. T: OK. Here it is. 译文 (M=妈妈,T=汤姆) 妈妈:怎么了,汤姆 汤姆:我感觉不舒服,妈妈。 妈妈:你感冒了吗 汤姆:是的,我想是这样的。您能给我一些水吗 妈妈:给你。 汤姆:谢谢您,妈妈。 妈妈:汤姆,你必须去看医生. 汤姆:好的,妈妈。 妈妈:外面很冷。你必须穿你的外套。 汤姆:好的,妈妈。您能把我的外套递给我吗 妈妈:给你。 汤姆:谢谢您,妈妈。 妈妈:告诉我你老师的电话号码。我将给他打电话告诉他你生病了。
英语翻译专业必翻经典文章英文原文参考译文
文档简介 一，英语翻译经典文章之英文原稿二，中文翻译：这篇英语文章的最好翻译版本！不是俺说的，是俺老师说哒！！ 英文原稿Brian It seems my only request (“please, let me sleep”) is not clear enough, so I made this simple table that can help you when you’re in doubt. Especially during the night
中文翻译小子： 我只想好好地睡觉，你不明白吗？！所以，我做了这个简表。当你不知道怎么办时，特 别是在晚上的时候，你可以看看它。 具体情况行动指南 1，我正在睡觉禁止进入 2，你不确定我是否睡觉，你想搞清楚管你“鸟”事；禁止进入 3，你嗑了药，想奔向我的床你他妈的滚远点 4，你在youtube上看了一个超赞的视频，禁止进入；在脸书上把链接发给我想让我看看 5，就算第三次世界大战开始了管我屁事，他妈的别进来 6，你和你的基友们想和我“玩玩”抱歉，直男一枚。不要碰我的任何东西，门都别碰 7，你想整理我的房间我谢谢你了！我自己会打扫 8，普京宣布同性婚姻合法化终于等到“它”！还好你没放弃！还是不要来我房里！ 9，我不在家进我房间，想都别想 10，白天，我在家。你敲了门，我说“请进” 你可以进来了 福利放送！！
如果你已经看到了这里，那么说明你应该是英文爱好者哦。 下面有一些非常实用，我精心整理的英文资料，你一定用得到！快去看看吧！ 一，最常用英语翻译政治文体句型总结大全完美版 二，英文合同翻译最常用句型总结专业版 三，英语毕业论文提纲模板优秀完整详细无敌版
土木工程专业英语课文原文及对照翻译
土木工程专业英语课文原 文及对照翻译 Newly compiled on November 23, 2020
Civil Engineering Civil engineering, the oldest of the engineering specialties, is the planning, design, construction, and management of the built environment. This environment includes all structures built according to scientific principles, from irrigation and drainage systems to rocket-launching facilities. 土木工程学作为最老的工程技术学科，是指规划，设计，施工及对建筑环境的管理。此处的环境包括建筑符合科学规范的所有结构，从灌溉和排水系统到火箭发射设施。 Civil engineers build roads, bridges, tunnels, dams, harbors, power plants, water and sewage systems, hospitals, schools, mass transit, and other public facilities essential to modern society and large population concentrations. They also build privately owned facilities such as airports, railroads, pipelines, skyscrapers, and other large structures designed for industrial, commercial, or residential use. In addition, civil engineers plan, design, and build complete cities and towns, and more recently have been planning and designing space platforms to house self-contained communities. 土木工程师建造道路，桥梁，管道，大坝，海港，发电厂，给排水系统，医院，学校，公共交通和其他现代社会和大量人口集中地区的基础公共设施。他们也建造私有设施，比如飞机场，铁路，管线，摩天大楼，以及其他设计用作工业，商业和住宅途径的大型结构。此外，土木工程师还规划设计及建造完整的城市和乡镇，并且最近一直在规划设计容纳设施齐全的社区的空间平台。 The word civil derives from the Latin for citizen. In 1782, Englishman John Smeaton used the term to differentiate his nonmilitary engineering work from that of the military engineers who predominated at the time. Since then, the term civil engineering has often been used to refer to engineers who build public facilities, although the field is much broader 土木一词来源于拉丁文词“公民”。在1782年，英国人John Smeaton为了把他的非军事工程工作区别于当时占优势地位的军事工程师的工作而采用的名词。自从那时起，土木工程学被用于提及从事公共设施建设的工程师，尽管其包含的领域更为广阔。 Scope. Because it is so broad, civil engineering is subdivided into a number of technical specialties. Depending on the type of project, the skills of many kinds of civil engineer specialists may be needed. When a project begins, the site is surveyed and mapped by civil engineers who locate utility placement—water, sewer, and power lines. Geotechnical specialists perform soil experiments to determine if the earth can bear the weight of the project. Environmental specialists study the project’s impact on the local area: the potential for air and
英文翻译原文
南京师范大学泰州学院 英文翻译原文 年级： 2011级学号：12110330 姓名：申佳佳 系部：信息工程学院 专业：通信工程 题目：基于C51的数字测速仪设计与仿真 指导教师：焦蓬蓬 2015 年 4 月 5 日
Linux - Operating system of cybertimes Though for a lot of people , regard Linux as the main operating system to make u p huge work station group, finish special effects of " Titanic " make , already can be re garded as and show talent fully. But for Linux, this only numerous news one of. Rece ntly, the manufacturers concerned have announced that support the news of Linux to i ncrease day by day, users' enthusiasm to Linux runs high unprecedentedly too. Then, Linux only have operating system not free more than on earth on 7 year this piece wh at glamour, get the favors of such numerous important software and hardware manufa cturers as the masses of users and Orac le , Informix , HP , Sybase , Corel , Intel , Net scape , Dell ,etc. , OK? 1.The background of Linux and characteristic Linux is a kind of " free (Free ) software ": What is called free, mean users can o btain the procedure and source code freely , and can use them freely , including revise or copy etc.. It is a result of cybertimes, numerous technical staff finish its research a nd development together through Inte rnet, countless user is it test and except fault , c an add user expansion function that oneself make conveniently to participate in. As th e most outstanding one in free software, Linux has characteristic o f the following: (1)Totally follow POSLX standard, expand the network operating system of sup porting all AT&T and BSD Unix characteristic. Because of inheritting Unix outstandi ng design philosophy , and there are clean , stalwart , high-efficient and steady kernels , their all key codes are finished by Li nus Torvalds and other outstanding programmer s, without any Unix code of AT&T or Berkeley, so Linu x is not Unix, but Linux and Unix are totally compatible. (2)Real many tasks, multi-user's system, the built-in n etwork supports, can be with such seamless links as NetWare , Windows NT , OS/2 , Unix ,etc.. Network in various kinds of Unix it tests to be fastest in comparing and ass ess efficiency. Support such many kinds of files systems as FAT16 , FAT32 , NTFS , E x t2FS , ISO9600 ,etc. at the same time .