文档库 最新最全的文档下载
当前位置:文档库 › 机械毕业设计外文文献翻译--认识曲柄摇臂机构设计的最优传动方法

机械毕业设计外文文献翻译--认识曲柄摇臂机构设计的最优传动方法

机械毕业设计外文文献翻译--认识曲柄摇臂机构设计的最优传动方法
机械毕业设计外文文献翻译--认识曲柄摇臂机构设计的最优传动方法

文献翻译

英文原文:

NOVEL METHOD OF REALIZING THE OPTIMAL TRANSMISSION OF THE CRANK-AND-ROCKER MECHANISM DESIGN Abstract: A novel method of realizing the optimal transmission of the crank-and-rocker mechanism is presented. The optimal combination design is made by finding the related optimal transmission parameters. The diagram of the optimal transmission is drawn. In the diagram, the relation among minimum transmission angle, the coefficient of travel speed variation, the oscillating angle of the rocker and the length of the bars is shown, concisely, conveniently and directly. The method possesses the main characteristic. That it is to achieve the optimal transmission parameters under the transmission angle by directly choosing in the diagram, according to the given requirements. The characteristics of the mechanical transmission can be improved to gain the optimal transmission effect by the method. Especially, the method is simple and convenient in practical use.

Keywords:Crank-and-rocker mechanism, Optimal transmission angle, Coefficient of travel speed variation

INTRODUCTION

By conventional method of the crank-and-rocker design, it is very difficult to realize the optimal combination between the various parameters for optimal transmission. The figure-table design method introduced in this paper can help achieve this goal. With given conditions, we can, by only consulting the designing figures and tables, get the relations between every parameter and another of the designed crank-and-rocker mechanism. Thus the optimal transmission can be realized.

The concerned designing theory and method, as well as the real cases of its application will be introduced later respectively.

1ESTABLISHMENT OF DIAGRAM FOR OPTIMAL TRANSMISSION DESIGN

It is always one of the most important indexes that designers pursue to improve the efficiency and property of the transmission. The crank-and-rocker mechanism is widely used in the mechanical transmission. How to improve work ability and reduce unnecessary power losses is directly related to the coefficient of travel speed variation, the oscillating angle of the rocker and the ratio of the crank and rocker. The reasonable combination of these parameters takes an important effect on the efficiency and property of the mechanism, which mainly indicates in the evaluation of the minimum transmission angle.

The aim realizing the optimal transmission of the mechanism is how to find the

maximum of the minimum transmission angle. The design parameters are reasonably combined by the method of lessening constraints gradually and optimizing separately. Consequently, the complete constraint field realizing the optimal transmission is established.

The following steps are taken in the usual design method. Firstly, the initial values of the length of rocker 3l and the oscillating angle of rocker ? are given. Then the value of the coefficient of travel speed variation K is chosen in the permitted range. Meanwhile, the coordinate of the fixed hinge of crank A po realized is calculated corresponding to value K .

1.1 Length of bars of crank and rocker mechanism

As shown in Fig.1, left arc G C 2 is the permitted field of point A . The

coordinates of point A are chosen by small step from point 2C to point G .

The coordinates of point A are 02h y y c A -= (1)

22A A y R x -= (2)

where 0h , the step, is increased by small increment within range(0,H ). If the smaller the chosen step is, the higher the computational precision will be. R is the radius of the design circle. d is the distance from 2C to G .

2c o s )2c o s (22c o s 33?θ????

????--+=l R l d (3) Calculating the length of arc 1AC and 2AC , the length of the bars of the

mechanism corresponding to point A is obtained [1,2].

1.2 Minimum transmission angle m in γ

Minimum transmission angle m in γ(see Fig.2) is determined by the equations [3]

3

22

142322m i n 2)(c o s l l l l l l --+=γ (4) 3

22

142322m a x 2)(c o s l l l l l l +-+=γ (5) m a x m i n 180γγ-?=' (6)

where 1l ——Length of crank(mm)

2l ——Length of connecting bar(mm)

3l ——Length of rocker(mm)

4l ——

Length of machine frame(mm)

Firstly, we choose minimum comparing m in γ with m

in γ'. And then we record all values of m in γ greater than or equal to ?40 and choose the maximum of them.

Secondly, we find the maximum of m in γ corresponding to any oscillating angle ? which is chosen by small step in the permitted range (maximum of m in γ is different oscillating angle ? and the coefficient of travel speed variation K ).

Finally, we change the length of rocker

l by small step similarly. Thus we

3

γcorresponding to the different length of bars, may obtain the maximum of

m in

different oscillating angle ?and the coefficient of travel speed variation K.

Fig.3 is accomplished from Table for the purpose of diagram design.

It is worth pointing out that whatever the length of rocker 3l is evaluated, the location that the maximum of m in γ arises is only related to the ratio of the length of rocker and the length of machine frame 3l /4l , while independent of 3l .

2 DESIGN METHOD

2.1 Realizing the optimal transmission design given the coefficient of travel

speed variation and the maximum oscillating angle of the rocker

The design procedure is as follows.

(1) According to given K and ?, taken account to the formula the extreme included angle θ is found. The corresponding ratio of the length of bars 3l /4l is obtained consulting Fig.3.

??+-=1801

1K K θ (7) (2) Choose the length of rocker 3l according to the work requirement, the length of the machine frame is obtained from the ratio 3l /4l .

(3) Choose the centre of fixed hinge D as the vertex arbitrarily, and plot an isosceles triangle, the side of which is equal to the length of rocker 3l (see Fig.4), and

?=∠21DC C . Then plot 212C C M C ⊥, draw N C 1, and make angle

θ-?=∠9012N C C . Thus the point of intersection of M C 2 and N C 1 is gained. Finally, draw the circumcircle of triangle 21C PC ?.

(4) Plot an arc with point D as the centre of the circle, 4l as the radius. The arc intersections arc G C 2 at point A . Point A is just the centre of the fixed hinge of the crank.

Therefore, from the length of the crank

2/)(211AC AC l -= (8)

and the length of the connecting bar

112l AC l -= (9)

we will obtain the crank and rocker mechanism consisted of 1l , 2l , 3l , and 4l .Thus the optimal transmission property is realized under given conditions.

2.2 Realizing the optimal transmission design given the length of the rocker (or the length of the machine frame) and the coefficient of travel speed variation

We take the following steps.

(1) The appropriate ratio of the bars 3l /4l can be chosen according to given K . Furthermore, we find the length of machine frame 4l (the length of rocker 3l ).

(2) The corresponding oscillating angle of the rocker can be obtained consulting Fig.3. And we calculate the extreme included angle θ.

Then repeat (3) and (4) in section 2.1

3 DESIGN EXAMPLE

The known conditions are that the coefficient of travel speed variation

1818.1=K and maximum oscillating angle ?=40?. The crankandrocker

mechanism realizing the optimal transmission is designed by the diagram solution method presented above.

First, with Eq.(7), we can calculate the extreme included angle ?=15θ. Then, we find 93.0/43=l l consulting Fig.3 according to the values of θ and ?.

If evaluate 503=l mm, then we will obtain 76.5393.0/504==l mm. Next, draw sketch(omitted).

As result, the length of bars is 161=l mm,462=l mm,503=l mm,76.534=l mm.

The minimum transmission angle is

?=--+=3698.462)(arccos 3

22142322min l l l l l l γ The results obtained by computer are 2227.161=l mm, 5093.442=l mm, 0000.503=l mm, 8986.534=l mm.

Provided that the figure design is carried under the condition of the Auto CAD circumstances, very precise design results can be achieved.

4 CONCLUSIONS

A novel approach of diagram solution can realize the optimal transmission of the crank-and-rocker mechanism. The method is simple and convenient in the practical use. In conventional design of mechanism, taking 0.1 mm as the value of effective the precision of the component sizes will be enough.

译文:

认识曲柄摇臂机构设计的最优传动方法

摘要:一种曲柄摇臂机构设计的最优传动的方法被提出。这种优化组合设计被用来找出最优的传递参数。得出最优传递图。在图中,在极小的传动角度之间, 滑移速度变化系数,摇臂的摆动角度和杆的长度被直观地显示。这是这种方法拥有的主要特征。根据指定的要求,它将传动角度之下的最优传动参数直接地表达在图上。通过这种方法,机械传动的特性能用以获取最优传动效果。特别是,这种方法是简单和实用的。

关键字:曲柄摇臂机构最优传动角度滑移速度变化系数

0 介绍

由曲柄摇臂机构设计的常规方法, 在各种各样的参量之间很难找出优化组合的最优传动。通过本文介绍的图面设计方法可以帮助达到这个目的。在指定的情况下,通过观查设计图面, 我们就能得到每个参量和另外一个曲柄摇臂机构设计之间的联系。由因认识最优传动。

具体的设计的理论和方法,以及它们各自的应用事例将在以下介绍。

1 优化传动设计的建立

优化传动的设计一直是设计师改进传输效率和追求产量的最重要的索引的当中一个。曲柄摇臂机构被广泛应用在机械传动中。如何改进工作效率和减少多余的功率损失直接地与滑移速度变化系数,摇臂的摆动角度和曲柄摇臂的比率有关系。这些参数的合理组合采用对机械效率和产量有重要作用, 这些主要体现在极小的传输角度上。

认识机械优化传动目的是找到极小的传输角度的最大值。设计参数是适度地减少限制而且分开的合理优化方法的结合。因此,完全限制领域的优化传动建立了。

以下步骤被采用在通常的设计方法。首先,测量出摇臂的长度3l和摇臂的

摆动角度 的初始值。然后滑移速度变化系数K的值被定在允许的范围内。同

时,曲柄固定的铰接座标A可能被认为是任意值K。

1.1 曲柄摇臂机构杆的长度

由图Fig.1,左弧G

C到点

C2是点A被允许的领域。点A的座标的选择从点2

G。

点A 的座标是 02h y y c A -= (1)

22A A y R x -= (2)

当0h ,高度,在range(0 ,H ) 被逐渐增加。如果选的越小,计算精度将越高。R 是设计圆的半径。d 是从2C 到G 的距离。

2c o s )2c o s (22c o s 33?θ????

????--+=l R l d (3) 计算弧1AC 和2AC 的长度,机械杆对应于点A 的长度是obtained[1,2 ] 。

1.2 极小的传动角度m in γ

极小的传动角度m in γ (参见Fig.2) 由equations[3]确定

3

22

142322m i n 2)(c o s l l l l l l --+=γ (4) 3

22

142322m a x 2)(c o s l l l l l l +-+=γ (5) m a x m i n 180γγ-?=' (6)

由于1l ——曲柄的长度(毫米)

2l ——连杆的长度(毫米)

3l ——摇臂的长度(毫米)

4l ——机器的长度(毫米)

首先, 我们比较极小值m in γ和m

in γ'。 并且我们记录所有m in γ的值大于或等于?40,然后选择他们之间的最大值。

第二, 我们发现最大值min γ对应于一个逐渐变小的范围的任一个摆动的角度? (最大值m in γ是不同于摆动的角度和滑移速度变化系数K ) 。

最后, 我们相似地慢慢缩小摇臂3l 的长度。 因而我们能获得最大值m in γ对应于杆的不同长度, 另外摆动的角度?和滑移速度变化系数K 。

Fig.3成功的表达设计的目的。

它确定了无论是摇臂的长度3l ,最大值m in γ出现的地点,只与摇臂的长度和机械的长度的比率3l /4l 有关, 当确定3l 时。

2 设计方法

2.1 认识最优传动设计下滑移速度变化系数和摇臂的最大摆动的角度

设计步骤如下。

(1) 根据所给的K 和?, 通常采取对发现极限角度θ的解释。 杆的长度的对应的比率3l /4l 是从图Fig.3获得的 。

??+-=1801

1K K θ (7) (2) 根据工作要求选择摇臂的长度3l , 机械的长度是从比率3l /4l 获得的。

(3) 任意地选择固定的铰接的中心D 作为端点,并且做一个等腰三角形,令一条边与摇臂的长度3l 相等 (参见Fig.4),令?=∠21DC C 。 然后做212C C M C ⊥, 连接N C 1,并且做角度θ-?=∠9012N C C 。 因而增加了交点M C 2和N C 1。 最后, 画三角形21C PC ?。

(4)以点D 作为圆的中心,4l 为半径画圆弧。 弧G C 2交点在A 点。 点A 是曲柄的固定铰接的中心。

所以, 从曲柄的长度

2/)(211AC AC l -= (8) 并且连杆的长度

112l AC l -= (9) 我们将获得曲柄摇臂机构包括1l ,2l ,3l 和4l 。因而优化传动加工会在指定的情

况下进行。

2.2 认识优化传动设计下摇臂的长度(或机械的长度) 和滑移速度变化系数

我们采取以下步骤。

(1)根据选择的K 确定杆的适当比率3l /4l 。 此外,我们得出机械 4l (摇臂的长度3l ) 。

(2) 摇臂对应的摆动的角度可以从图Fig.3 获得。 并且我们计算出极限角度。

然后根据2.1重覆(3) 和(4)

3 设计例子

已知的条件是, 滑移速度变化系数1818.1=K 和最大摆动角度?=40?。 提出曲柄摇臂机械优化传动图方法设计方案。

首先, 通过公式(7),我们能计算出极限角度?=15θ。 然后,我们通过表格Fig.3 查出93.0/43=l l 以及θ和?的值。

假设503=l mm, 然后我们将得出76.5393.0/504==l mm 。

然后, 做sketch(omitted) 。

最后, 算出杆的长度分别是161=l mm,462=l mm,503=l mm,76.534=l mm.

极小传动角度是

?=--+=3698.462)(arccos 3

22142322min l l l l l l γ

结果由计算可得2227.161=l mm , 5093.442=l mm , 0000.503=l mm , 8986.534=l mm 。

在运用Auto CAD 制图设计的情况, 可达到非常精确设计结果。 4结论

认识图解法解答曲柄摇臂机构的最优传动。这种方法是简单和实用的。通常在机械设计中, 将0.1 毫米作为最小有效精度是足够的。

冲压模具技术外文翻译(含外文文献)

前言 在目前激烈的市场竞争中,产品投入市场的迟早往往是成败的关键。模具是高质量、高效率的产品生产工具,模具开发周期占整个产品开发周期的主要部分。因此客户对模具开发周期要求越来越短,不少客户把模具的交货期放在第一位置,然后才是质量和价格。因此,如何在保证质量、控制成本的前提下加工模具是值得认真考虑的问题。模具加工工艺是一项先进的制造工艺,已成为重要发展方向,在航空航天、汽车、机械等各行业得到越来越广泛的应用。模具加工技术,可以提高制造业的综合效益和竞争力。研究和建立模具工艺数据库,为生产企业提供迫切需要的高速切削加工数据,对推广高速切削加工技术具有非常重要的意义。本文的主要目标就是构建一个冲压模具工艺过程,将模具制造企业在实际生产中结合刀具、工件、机床与企业自身的实际情况积累得高速切削加工实例、工艺参数和经验等数据有选择地存储到高速切削数据库中,不但可以节省大量的人力、物力、财力,而且可以指导高速加工生产实践,达到提高加工效率,降低刀具费用,获得更高的经济效益。 1.冲压的概念、特点及应用 冲压是利用安装在冲压设备(主要是压力机)上的模具对材料施加压力,使其产生分离或塑性变形,从而获得所需零件(俗称冲压或冲压件)的一种压力加工方法。冲压通常是在常温下对材料进行冷变形加工,且主要采用板料来加工成所需零件,所以也叫冷冲压或板料冲压。冲压是材料压力加工或塑性加工的主要方法之一,隶属于材料成型工程术。 冲压所使用的模具称为冲压模具,简称冲模。冲模是将材料(金属或非金属)批量加工成所需冲件的专用工具。冲模在冲压中至关重要,没有符合要求的冲模,批量冲压生产就难以进行;没有先进的冲模,先进的冲压工艺就无法实现。冲压工艺与模具、冲压设备和冲压材料构成冲压加工的三要素,只有它们相互结合才能得出冲压件。 与机械加工及塑性加工的其它方法相比,冲压加工无论在技术方面还是经济方面都具有许多独特的优点,主要表现如下; (1) 冲压加工的生产效率高,且操作方便,易于实现机械化与自动化。这是

机械设计设计外文文献翻译、中英文翻译、外文翻译

机械设计 摘要:机器是由机械装置和其它组件组成的。它是一种用来转换或传递能量的装置,例如:发动机、涡轮机、车辆、起重机、印刷机、洗衣机、照相机和摄影机等。许多原则和设计方法不但适用于机器的设计,也适用于非机器的设计。术语中的“机械装置设计”的含义要比“机械设计”的含义更为广泛一些,机械装置设计包括机械设计。在分析运动及设计结构时,要把产品外型以及以后的保养也要考虑在机械设计中。在机械工程领域中,以及其它工程领域中,所有这些都需要机械设备,比如:开关、凸轮、阀门、船舶以及搅拌机等。 关键词:设计流程设计规则机械设计 设计流程 设计开始之前就要想到机器的实际性,现存的机器需要在耐用性、效率、重量、速度,或者成本上得到改善。新的机器必需具有以前机器所能执行的功能。 在设计的初始阶段,应该允许设计人员充分发挥创造性,不要受到任何约束。即使产生了许多不切实际的想法,也会在设计的早期,即在绘制图纸之前被改正掉。只有这样,才不致于阻断创新的思路。通常,还要提出几套设计方案,然后加以比较。很有可能在这个计划最后决定中,使用了某些不在计划之内的一些设想。 一般的当外型特点和组件部分的尺寸特点分析得透彻时,就可以全面的设计和分析。接着还要客观的分析机器性能的优越性,以及它的安全、重量、耐用性,并且竞争力的成本也要考虑在分析结果之内。每一个至关重要的部分要优化它的比例和尺寸,同时也要保持与其它组成部分相协调。 也要选择原材料和处理原材料的方法。通过力学原理来分析和实现这些重要的特性,如那些静态反应的能量和摩擦力的最佳利用,像动力惯性、加速动力和能量;包括弹性材料的强度、应力和刚度等材料的物理特性,以及流体润滑和驱动器的流体力学。设计的过程是重复和合作的过程,无论是正式或非正式的进行,对设计者来说每个阶段都很重要。 最后,以图样为设计的标准,并建立将来的模型。如果它的测试是符合事先要

机械类外文文献

附:外文翻译 外文原文: Fundamentals of Mechanical Design Mechanical design means the design of things and systems of a mechanical nature—machines, products, structures, devices, and instruments. For the most part mechanical design utilizes mathematics, the materials sciences, and the engineering-mechanics sciences. The total design process is of interest to us. How does it begin? Does the engineer simply sit down at his desk with a blank sheet of paper? And, as he jots down some ideas, what happens next? What factors influence or control the decisions which have to be made? Finally, then, how does this design process end? Sometimes, but not always, design begins when an engineer recognizes a need and decides to do something about it. Recognition of the need and phrasing it in so many words often constitute a highly creative act because the need may be only a vague discontent, a feeling of uneasiness, of a sensing that something is not right. The need is usually not evident at all. For example, the need to do something about a food-packaging machine may be indicated by the noise level, by the variations in package weight, and by slight but perceptible variations in the quality of the packaging or wrap. There is a distinct difference between the statement of the need and the identification of the problem. Which follows this statement? The problem is more specific. If the need is for cleaner air, the problem might be that of reducing the dust discharge from power-plant stacks, or reducing the quantity of irritants from automotive exhausts. Definition of the problem must include all the specifications for the thing that is to be designed. The specifications are the input and output quantities, the characteristics of the space the thing must occupy and all the limitations on t hese quantities. We can regard the thing to be designed as something in a black box. In this case we must specify the inputs and outputs of the box together with their characteristics and limitations. The specifications define the cost, the number to be manufactured, the expected life, the range, the operating temperature, and the reliability. There are many implied specifications which result either from the designer's particular environment or from the nature of the problem itself. The manufacturing processes which are available, together with the facilities of a certain plant, constitute restrictions on a designer's freedom, and hence are a part of the implied specifications. A small plant, for instance, may not own cold-working machinery. Knowing this, the designer selects other metal-processing methods which can be performed in the plant. The labor skills available and the competitive situation also constitute implied specifications. After the problem has been defined and a set of written and implied specifications has been obtained, the next step in design is the synthesis of an optimum solution. Now synthesis cannot take place without both analysis and optimization because the system under design must be analyzed to determine whether the performance complies with the specifications. The design is an iterative process in which we proceed through several steps, evaluate the results, and then return to an earlier phase of the procedure. Thus we may synthesize several components of a system, analyze and optimize them, and return to synthesis to see what effect this has on the remaining parts of the system. Both analysis and optimization require that we construct or devise abstract models of the system which will admit some form of mathematical analysis. We call these models

机械外文文献翻译

机械外文文献翻译 Overall position of Agricultural Mechanization in Turkey Agricultural equipment and machinery are the indispensable part of agricultural activities. If these instruments, which are used in various stages of production, are not used properly, there may be some problems. So, how can we use them properly ? As the proverb goes, “It is the want of care that makes the field bare”. They return the money and efforts invested in them if they are maintained well. Ploughs, which were being used in our country up until recently, resemble those ploughs of the various tribes that lived in Anatolia long time ago. It is because one society gets use of societies that lived before. Some of the black ploughs that were being used up until recently resemble the ploughs that had been used in the ancient Rome. The first agricultural school was established in the Ottoman Empire in 1846. The first domestic heavy ploughs was manufactured i n Izmir 90 years ago, and tractor was introduced 80 years ago. However, it was only the foundation of the Republic that the tractor began to be used in agricultural activities. Agricultural mobilization began with modern agricultural practices in the Atatürk Forest Farm, which was founded by the Great Atatürk. Use of modern agricultura l equipment was encouraged,

毕业设计外文翻译-中文版

本科生毕业设计(论文)外文科技文献译文 译文题目(外文题目)学院(系)Socket网络编程的设计与实现A Design and Implementation of Active Network Socket Programming 机械与能源工程学院 专学业 号 机械设计制造及其自动化 071895 学生姓名李杰林 日期2012年5月27日指导教师签名日期

摘要:编程节点和活跃网络的概念将可编程性引入到通信网络中,并且代码和数据可以在发送过程中进行修改。最近,多个研究小组已经设计和实现了自己的设计平台。每个设计都有其自己的优点和缺点,但是在不同平台之间都存在着互操作性问题。因此,我们引入一个类似网络socket编程的概念。我们建立一组针对应用程序进行编程的简单接口,这组被称为活跃网络Socket编程(ANSP)的接口,将在所有执行环境下工作。因此,ANSP 提供一个类似于“一次性编写,无限制运行”的开放编程模型,它可以工作在所有的可执行环境下。它解决了活跃网络中的异构性,当应用程序需要访问异构网络内的所有地区,在临界点部署特殊服务或监视整个网络的性能时显得相当重要。我们的方案是在现有的环境中,所有应用程序可以很容易地安装上一个薄薄的透明层而不是引入一个新的平台。 关键词:活跃网络;应用程序编程接口;活跃网络socket编程

1 导言 1990年,为了在互联网上引入新的网络协议,克拉克和藤农豪斯[1]提出了一种新的设 计框架。自公布这一标志性文件,活跃网络设计框架[2,3,10]已经慢慢在20世纪90 年代末成形。活跃网络允许程序代码和数据可以同时在互联网上提供积极的网络范式,此外,他们可以在传送到目的地的过程中得到执行和修改。ABone作为一个全球性的骨干网络,开 始进行活跃网络实验。除执行平台的不成熟,商业上活跃网络在互联网上的部署也成为主要障碍。例如,一个供应商可能不乐意让网络路由器运行一些可能影响其预期路由性能的未知程序,。因此,作为替代提出了允许活跃网络在互联网上运作的概念,如欧洲研究课题组提出的应用层活跃网络(ALAN)项目[4]。 在ALAN项目中,活跃服务器系统位于网络的不同地址,并且这些应用程序都可以运行在活跃系统的网络应用层上。另一个潜在的方法是网络服务提供商提供更优质的活跃网络服务类。这个服务类应该提供最优质的服务质量(QOS),并允许路由器对计算机的访问。通过这种方法,网络服务提供商可以创建一个新的收入来源。 对活跃网络的研究已取得稳步进展。由于活跃网络在互联网上推出了可编程性,相应 地应建立供应用程序工作的可执行平台。这些操作系统平台执行环境(EES),其中一些已 被创建,例如,活跃信号协议(ASP)[12]和活跃网络传输系统(ANTS)[11]。因此,不 同的应用程序可以实现对活跃网络概念的测试。 在这些EES 环境下,已经开展了一系列验证活跃网络概念的实验,例如,移动网络[5],网页代理[6],多播路由器[7]。活跃网络引进了很多在网络上兼有灵活性和可扩展性的方案。几个研究小组已经提出了各种可通过路由器进行网络计算的可执行环境。他们的成果和现有基础设施的潜在好处正在被评估[8,9]。不幸的是,他们很少关心互操作性问题,活跃网络由多个执行环境组成,例如,在ABone 中存在三个EES,专为一个EES编写的应用程序不能在其他平台上运行。这就出现了一种资源划分为不同运行环境的问题。此外,总是有一些关键的网络应用需要跨环境运行,如信息收集和关键点部署监测网络的服务。 在本文中,被称为活跃网络Socket编程(ANSP)的框架模型,可以在所有EES下运行。它提供了以下主要目标: ??通过单一编程接口编写应用程序。 由于ANSP提供的编程接口,使得EES的设计与ANSP 独立。这使得未来执行环境的发展和提高更加透明。

Manufacturing Engineering and Technology(机械类英文文献+翻译)

Manufacturing Engineering and Technology—Machining Serope kalpakjian;Steven R.Schmid 机械工业出版社2004年3月第1版 20.9 MACHINABILITY The machinability of a material usually defined in terms of four factors: 1、Surface finish and integrity of the machined part; 2、Tool life obtained; 3、Force and power requirements; 4、Chip control. Thus, good machinability good surface finish and integrity, long tool life, and low force And power requirements. As for chip control, long and thin (stringy) cured chips, if not broken up, can severely interfere with the cutting operation by becoming entangled in the cutting zone. Because of the complex nature of cutting operations, it is difficult to establish relationships that quantitatively define the machinability of a material. In manufacturing plants, tool life and surface roughness are generally considered to be the most important factors in machinability. Although not used much any more, approximate machinability ratings are available in the example below. 20.9.1 Machinability Of Steels Because steels are among the most important engineering materials (as noted in Chapter 5), their machinability has been studied extensively. The machinability of steels has been mainly improved by adding lead and sulfur to obtain so-called free-machining steels. Resulfurized and Rephosphorized steels. Sulfur in steels forms manganese sulfide inclusions (second-phase particles), which act as stress raisers in the primary shear zone. As a result, the chips produced break up easily and are small; this improves machinability. The size, shape, distribution, and concentration of these inclusions significantly influence machinability. Elements such as tellurium and selenium, which are both chemically similar to sulfur, act as inclusion modifiers in

毕业设计外文翻译原文

编号: 毕业设计(论文)外文翻译 (原文) 院(系):应用科技学院 专业:机械设计制造及其自动化 学生姓名:邓瑜 学号:0501120501 指导教师单位:应用科技学院 姓名:黄小能 职称: 2009年 5 月20 日

The Injection Molding The Introduction of Molds The mold is at the core of a plastic manufacturing process because its cavity gives a part its shape. This makes the mold at least as critical-and many cases more so-for the quality of the end product as, for example, the plasticiting unit or other components of the processing equipment. Mold Material Depending on the processing parameters for the various processing methods as well as the length of the production run, the number of finished products to be produced, molds for plastics processing must satisfy a great variety of requirements. It is therefore not surprising that molds can be made from a very broad spectrum of materials, including-from a technical standpoint-such exotic materials as paper matched and plaster. However, because most processes require high pressures, often combined with high temperatures, metals still represent by far the most important material group, with steel being the predominant metal. It is interesting in this regard that, in many cases, the selection of the mold material is not only a question of material properties and an optimum price-to-performance ratio but also that the methods used to produce the mold, and thus the entire design, can be influenced. A typical example can be seen in the choice between cast metal molds, with their very different cooling systems, compared to machined molds. In addition, the production technique can also have an effect; for instance, it is often reported that, for the sake of simplicity, a prototype mold is frequently machined from solid stock with the aid of the latest technology such as computer-aided (CAD) and computer-integrated manufacturing (CIM). In contrast to the previously used methods based on the use of patterns, the use of CAD and CAM often represents the more economical solution today, not only because this production capability is available pin-house but also because with any other technique an order would have to be placed with an outside supplier. Overall, although high-grade materials are often used, as a rule standard materials are used in mold making. New, state-of-the art (high-performance) materials, such as ceramics, for instance, are almost completely absent. This may be related to the fact that their desirable characteristics, such as constant properties up to very high temperatures, are not required on molds, whereas their negative characteristics, e. g. low tensile strength and poor thermal conductivity, have a clearly related to ceramics, such as sintered material, is found in mild making only to a limited degree. This refers less to the modern materials and components

抛光瓷砖毕业设计外文文献翻译

毕业设计外文资料翻译 题目POLISHING OF CERAMIC TILES 抛光瓷砖 学院材料科学与工程 专业复合材料与工程 班级 学生 学号 指导教师 二〇一二年三月二十八日

MATERIALS AND MANUFACTURING PROCESSES, 17(3), 401–413 (2002) POLISHING OF CERAMIC TILES C. Y. Wang,* X. Wei, and H. Yuan Institute of Manufacturing Technology, Guangdong University ofTechnology, Guangzhou 510090, P.R. China ABSTRACT Grinding and polishing are important steps in the production of decorative vitreous ceramic tiles. Different combinations of finishing wheels and polishing wheels are tested to optimize their selection. The results show that the surface glossiness depends not only on the surface quality before machining, but also on the characteristics of the ceramic tiles as well as the performance of grinding and polishing wheels. The performance of the polishing wheel is the key for a good final surface quality. The surface glossiness after finishing must be above 208 in order to get higher polishing quality because finishing will limit the maximum surface glossiness by polishing. The optimized combination of grinding and polishing wheels for all the steps will achieve shorter machining times and better surface quality. No obvious relationships are found between the hardness of ceramic tiles and surface quality or the wear of grinding wheels; therefore, the hardness of the ceramic tile cannot be used for evaluating its machinability. Key Words: Ceramic tiles; Grinding wheel; Polishing wheel

汽车制动系统(机械、车辆工程毕业论文英文文献及翻译)

Automobile Brake System汽车制动系统 The braking system is the most important system in cars. If the brakes fail, the result can be disastrous. Brakes are actually energy conversion devices, which convert the kinetic energy (momentum) of the vehicle into thermal energy (heat).When stepping on the brakes, the driver commands a stopping force ten times as powerful as the force that puts the car in motion. The braking system can exert thousands of pounds of pressure on each of the four brakes. Two complete independent braking systems are used on the car. They are the service brake and the parking brake. The service brake acts to slow, stop, or hold the vehicle during normal driving. They are foot-operated by the driver depressing and releasing the brake pedal. The primary purpose of the brake is to hold the vehicle stationary while it is unattended. The parking brake is mechanically operated by when a separate parking brake foot pedal or hand lever is set. The brake system is composed of the following basic components: the “master cylinder” which is located under the hood, and is directly connected to the brake pedal, converts driver foot’s mechanical pressure into hydraulic pressure. Steel “brake lines” and flexible “brake hoses” connect the master cylinder to the “slave cylinders” located at each wheel. Brake fluid, specially designed to work in extreme conditions, fills the system. “Shoes” and “pads” are pushed by the slave cylinders to contact the “drums” and “rotors” thus causing drag, which (hopefully) slows the c ar. The typical brake system consists of disk brakes in front and either disk or drum brakes in the rear connected by a system of tubes and hoses that link the brake at each wheel to the master cylinder (Figure). Basically, all car brakes are friction brakes. When the driver applies the brake, the control device forces brake shoes, or pads, against the rotating brake drum or disks at wheel. Friction between the shoes or pads and the drums or disks then slows or stops the wheel so that the car is braked.

本科毕业设计外文文献翻译

( 本科毕业设计外文文献翻译 学校代码: 10128 学 号: 题 目:Shear wall structural design of high-level framework 学生姓名: 学 院:土木工程学院 系 别:建筑工程系 专 业:土木工程专业(建筑工程方向) 班 级:土木08-(5)班 指导教师: (副教授)

Shear wall structural design of high-level framework Wu Jicheng Abstract: In this paper the basic concepts of manpower from the frame shear wall structure, analysis of the structural design of the content of the frame shear wall, including the seismic wall shear span ratio design, and a concrete structure in the most commonly used frame shear wall structure the design of points to note. Keywords: concrete; frame shear wall structure; high-rise buildings The wall is a modern high-rise buildings is an important building content, the size of the frame shear wall must comply with building regulations. The principle is that the larger size but the thickness must be smaller geometric features should be presented to the plate, the force is close to cylindrical. The wall shear wall structure is a flat component. Its exposure to the force along the plane level of the role of shear and moment, must also take into account the vertical pressure. Operate under the combined action of bending moments and axial force and shear force by the cantilever deep beam under the action of the force level to look into the bottom mounted on the basis of. Shear wall is divided into a whole wall and the associated shear wall in the actual project, a whole wall for example, such as general housing construction in the gable or fish bone structure film walls and small openings wall. Coupled Shear walls are connected by the coupling beam shear wall. But because the

(完整版)PLC毕业设计的外文文献(及翻译)

PLC technique discussion and future development T.J.byers Electronic Test Equipment-principles and Applications Princeton University .America Along with the development of the ages, the technique that is nowadays is also gradually perfect, the competition plays more strong; the operation that list depends the artificial has already can't satisfied with the current manufacturing industry foreground, also can't guarantee the request of the higher quantity and high new the image of the technique business enterprise. The people see in produce practice, automate brought the tremendous convenience and the product quantities for people up of assurance, also eased the personnel's labor strength, reduce the establishment on the personnel. The target control of the hard realization in many complicated production lines, whole and excellent turn, the best decision etc, well-trained operation work, technical personnel or expert, governor but can judge and operate easily, can acquire the satisfied result. The research target of the artificial intelligence makes use of the calculator exactly to carry out, imitate these intelligences behavior, moderating the work through person's brain and calculators, with the mode that person's machine combine, for resolve the very complicated problem to look for the best path. We come in sight of the control that links after the electric appliances in various situation, that is already the that time generation past, now of after use in the mold a perhaps simple equipments of grass-roots control that the electric appliances can do for the low level only; And the PLC emergence also became the epoch-making topic, adding the vivid software control through a very and stable hardware, making the automation head for the new high tide. The PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculations of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but the exportation equipments

相关文档
相关文档 最新文档