借助DDS的精密频率的一种替代方法毕业论文外文文献翻译及原文

毕业设计（论文）外文文献翻译

文献、资料中文题目：借助DDS的精密频率的一种替代方法文献、资料英文题目：

文献、资料来源：

文献、资料发表（出版）日期：

院（部）：

专业：

班级：

姓名：

学号：

指导教师：

翻译日期： 2017.02.14

An alternative method of precise frequency by the aid of a DDS

Contents

A method of frequency measurement based on a closed loop composed mainly of a Frequency Comparator (FC) and a Direct Digital Synthesizer (DDS) is presented in this paper. The DDS serves as reference sinewave signal generator acting at one of the FC's inputs. The FC accepts the hard-limited waveform of the DDS as well as the unknown frequency. From the comparison of the two signals a logic output that controls an up/down counter is produced. The counter's output acting as the Frequency Setting Word (FSW) instructs the DDS to produce a new sinewave closer in frequency to the unknown one. When the loop settles, the FSW gives the digital estimate of the unknown frequency. Advantage is taken from the inherent high resolution of the DDS and noise immunity of the loop, to design an equally precise and immune frequency meter. All the additional associated stages up to the instrument's display are presented.

1 Introduction

The most commonly used frequency measurement technique adopts counters that count the pulses of the unknown frequency during a predefined time window (aperture). Apart from this, techniques where the pulses of a reference frequency are counted during one or more periods of the unknown one are also common. In the latter case, the period instead of the frequency is estimated .Some papers in [1] in the literature deal with the problem of low frequency measurement and are focusing in the frequency range of cardiac (heart) signals (a few hertz) or in the mains frequency (50-60 Hz).These techniques are actually measuring the period of the signals and use some way to calculate its reciprocal, the frequency. In [2], the frequency is calculated by the method of look-up tables. Others [4-6] are microprocessor or microcontroller based.

The above methods can be characterized as open-loop methods i.e. digital counters are used to count during a predefined tinle interval and calculate the result afterwards. Its closed-loop form characterizes the proposed method in this paper. By the term "closed-loop" we denote some sort of feedback. A waveform with a known (controlled) frequency is produced within the circuit and is fed back to the frequency comparison stage which consecutively forces it to approximate the unknown (input) frequency. The device that produces the above mentioned waveform of controlled frequency is a Direct Digital Synthesizer.

2 Direct Digital Synthesis

A typical Direct Digital Synthesizer consists of a RAM containing samples of a sinewave (sine look-up table, LUT). These samples are swept in a controlled manner by the aid of a Frequency Setting Word (FSW), which determines the phase step. A typical FSW is 32-bit wide, but 48-bit synthesizers leading in higher frequency resolution are also available. A phase accumulator produces the successive addresses of the sine look-up table and generates a digitized sine wave output. The digital part of the DDS, the phase accumulator and the LUT, is called Numerically Controlled Oscillator (NCO). The final stage, which in contrast to the previous one is mostly analog, consists of a D/A converter followed by a filter. The filter smoothes the digitized sinewave, producing a continuous output signal. In the applications where a square wave output is needed, this is obtained by a hard limiter after the filter. It is not equivalent to use e.g. the MS

B of the accumulator's output instead of the filtered and hard limited waveform because significant jitter will be encountered.

The frequency of the output signal for an n-bit system is calculated in the following way; If the phase step is equal to one, the accumulator will count by ones, taking2n clock cycles to

address the entire LUT and to generate one cycle of the output sinewave. This is the lowest frequency that the system can generate and is also its frequency resolution. Setting the FSW equal to two, results in the accumulator counting by twos, taking 1

2n - clock cycles to complete one

cycle of the output sinewave. It can easily be shown that for any integer m, where m<12n -, the

number of clock cycles taken to generate one cycle of the output sine wave is 2n /m, and the

output frequency (f DDS ) and the frequency resolution (fres) are given by the following formulas ： f DDS =

2n

m fclk ? fres= fclk/2n For n = 32 and having a clock frequency of fclk = 33 MHz, the frequency resolution is 7.68 mHz. If n is increased to 48, with the same clock frequency, a resolution of 120 nHz is possible. 3 The proposed frequency measurement technique The idea that led to our present design came from the extremely high frequency resolution of the DDS devices and is enforced by the noise immunity of its closed loop form. A (known) frequency source, the DDS, is employed in a closed loop and is forced progressively to produce an output with a frequency equal to the unknown input . A rule of thumb in the DDS systems is that the maximum acceptable synthesized frequency is about 25% of the clock frequency (well below the Nyquist limit). According to this, our prototype that uses a 33 MHz clock would effectively count up to 8 MHz. Looking at the GaAs products, we can see that recently available DDS devises can operate at clock frequencies up to the extent of 400 MHz. Therefore, by the present method, frequency counters working up to 100 MHz can be designed. The resolution will depend on the number of FSW bits and the clock frequency. The clock frequency fclk of the DDS is very critical because as it decreases, the resolution of the proposed method (defined as fclk/2n ) becomes finer i.e. it improves. The impact of the clock frequency decrease is the subsequent decrease of its maximum output frequency that limits the counter's maximum count. The major blocks have been shown . Among them are the Frequency Comparator and the DDS. To overcome some disadvantages of the specific frequency comparator a correction stage has been incorporated. This stage is also used for the measurement extraction in order to display the correct reading.

3.1 Operation of the circuit

The circuit operates in such a way that at the beginning of a new measurement the DDS output frequency would be controlled in a successive approximation way. The initial DDS frequency would be half of it's maximum. In addition, the frequency step of the approximation would equal the 1/4 of the DDS maximum frequency. On every approximation the frequency step is divided by two and added or subtracted to the FSW of the DDS, depending on the output of the Frequency Comparator. The approximation procedure stops when the step size decreases to one. After that, an up/down counter substitutes the approximation mechanism.

The digital FSW, after the appropriate correction and decoding, is presented in an output device i.e. an LCD display or any other suitable means. Alternatively, it can be digitally recorded or it can be read by a computer. As conclusion of this initial approach we could say that the proposed method is based on a Digital Controlled Synthesizer which is forced to produce a frequency almost equal to the unknown one.

3.2 Frequency comparison

The frequency comparator seems to be the most critical stage of the design. The

implementation is based on a modified phase/frequency comparator proposed by Philips in the 74HC4046 PLL device. It consists primarily of two binary counters, counting up to two and an RS flip-flop.

The function of the frequency comparator is based on the principle that the lower frequency, i.e. larger period, includes (embraces) at least one or more full periods of the higher frequency (smaller period). This means that two or more rising edges of the higher frequency waveform are included within the lower frequency period. Considering the above, the circuit operates as follows: When the first counter (#1) encounters two rising edges of the unknown frequency in one period of the DDS, it sets the output of the RS flip-flop. The logic "1" of the RS flip-flop acting at the U/D control input of the Up/Down counter forces the DDS to rise its output frequency. On the contrary, when the second counter (#2) counts two rising edges of the DDS output within a period of the unknown frequency it resets the RS flip-flop's output. This action decreases the frequency of the DDS.

At a first glance one could think that the synthesized frequency could reach the measured one (fin) and then the operation of the counter stops. Unfortunately this is not the case. A dynamic mechanism takes place instead. The circuit needs some time to realize the correct frequency relation. We will refer to this time as "hysteresis". Hysteresis depends on the initial timing relation of the DDS output and on the unknown frequency. Initially, during the hysteresis period, the indication regarding the larger frequency is ambiguous i.e. it can be erroneous. The ambiguity settles when two rising edges of the higher frequency waveform occur during one period of the lower one. If we consider the case of the DDS frequency to be equal to the unknown one, we will find that the comparator's output will toggle, indicating alternatively that the DDS frequency is higher or lower than the unknown. This is actually an acceptable and expected condition, because (as in a voltage comparator) an equality indication could not exist. In our case this is not a problem because the circuit is embedded in a closed loop. The loop will act in a manner that after some short time, the hysteresis, the situation will be reversed and so on. The duration of hysteresis is variable. This situation is controlled, as will be explained later. Although an analog implementation of the frequency comparator would look more robust to noise we insisted to the digital implementation for three reasons: ease of implementation in VLSI or Programmable Logic Devices (PLDs) with no need of analog components, wide frequency range of operation and shorter response time.

3.3 Interaction between frequency comparator and digital synthesizer

After the successive approximation of the unknown frequency the Frequency Comparator "realizes" that the synthesized frequency is higher (lower) than the unknown one and produces a logic 0 (1) at the output which commands the up/down counter to count in the down (up) direction. As previously mentioned, the output of this counter is considered to be the FSW to the DDS stage. In the case when the DDS frequency was initially lower, the synthesized frequency will increase progressively to reach the unknown one. This will not be "realized" by the frequency comparator and the synthesized frequency will keep on increasing for some clock cycles, until the comparator detects the correct relation of it's two input frequencies, the unknown one and the DDS output. The same phenomenon will be observed for the opposite (decreasing) case also. This is due to hysteresis that was mentioned earlier.

When DDS output (f DDS) has approached fin, due to hysteresis, no specific frequency is synthesized. Instead, it swings between f1 and f2, where f1 and f2are the two extreme values of the

frequency swing lying symmetrically around fin. The DDS output can be considered as a frequency modulated carrier by a triangular waveform. The triangular waveform is the analog representation of the FSW applied to the DDS. lower trace shows a typical output of the Frequency Comparator. In the same figure, upper trace, is shown in analog form the FSW variation as it is trying to approach the correct value. This waveform has been captured using an auxiliary hardware circuit: A digital-to-analog converter (DAC) was connected to the output of the U/D counter (MSBs) in order to study the operation. This DAC is not shown in the block diagram of the circuit. Stated differently, the lower trace is the U/D command (input) to the counter while the upper trace is a hypothetical "frequency modulating" waveform. It is obvious that the term "hypothetical" is used because there is not such a waveform available somewhere in the circuit (except for the auxiliary DAC). Instead, its numerical equivalent exists. The magnitude of the slope of the elements of the triangular waveform is constant for constant input frequency and depends on the clock of the U/D counter (horizontal axis) and the voltage reference of the DAC (vertical axis). This slope is k ? fin.

3.4 Description of the prototype hardware

For evaluation purposes two prototypes have been built and tested in the laboratory. The first approach was a low frequency instrument (operating up to 15 KHz) . The purpose of this implementation was to study the principles of operation of the proposed method. Next, a higher frequency prototype was built which will be described in more detail here. In order to implement the digital part of the prototype, (Frequency Comparator, Successive Counter, Correction Stage) two PLD devices from Altera (EPF 8064LC68-12) were used. These devices are interconnected with the DDS, which is the Q2240I-3S1 from Qualcomm. The DDS has a 32-bit input and a 12-bit output for the sine lookup table (LUT). The 12-bit output of the LUT is fed into the D/A converter, the AD9713B from Analog Devices. Its analog output is connected to an I/V amplifier (current-to-voltage converter).

The generated sinewave has upper harmonics, due to the DAC operation. These harmonics are removed from the filters that follow the DAC. The correction stage is implemented partially on the PLDs and partially on the microcontroller. Based on the up-down command of the frequency comparator we store the two extreme values, FSW1 and FSW2, which are then transferred into the micro-controller (Atmel AT89C52), transformed into numerical representation and fed to the LCD Display. The micro-controller also controls the whole operation of the prototype.

The behaviour of the instrument was according to the expected and was alike to a conventional bench frequency counter. The speed of measurement was checked using lower trace, obtained by the aid of a digital oscilloscope. Each state, high or low, of this waveform corresponds to the time required for one measurement.

4 Conclusion

In this paper an alternative method of frequency measurement has been proposed. It has been pointed out that in most cases this method is faster than conventional methods for the same frequency resolution. On the other hand, the precision of the method can be very high due to the inherent high frequency resolution characteristic of the DDS that is employed. This synthesizer, which can be thought as an oscillator, is driven to "oscillate" in the region of the unknown input frequency. A comparison with conventional methods has been given and two prototypes have been built and tested in the laboratory.

The second major advantage of this method is that if repetitive frequency measurements are

to be taken, the instrument remains locked and the frequency measurement does not restart from the beginning, but instead is automatically driven to lower or higher values. In other words, the loop has the capability to follow the changes in the frequency of the input signal. In the conventional counting techniques the counting procedure is repeated (restarted) for each new measurement.

Another important advantage is the noise immunity of the system, due to its closed loop nature. A detailed study of the noise behavior has not been carried out in this paper. This is mainly because the aim of this text is to present an alternative principle of frequency measurement. Moreover, the final output of the system is taken after some further processing (measurement correction) which also contributes to the noise immunity.

借助DDS的精密频率的一种替代方法

内容

频率测量的方法基于闭环组成,主要是一个频率比较器(FC)和直接数字合成器(DDS),对此在本文中进行了介绍。DDS作为标准信号发生器在FC的投入之中扮演一定的角色。FC接受了DDS的硬限幅波形以及未知的频率。从比较两个信号的输出，控制逻辑向上/向下计数器产生了。计数器的输出频率设定字（FSW）代理指示的DDS产生一个新的正弦波频率接近未知之一。当循环沉淀，频率设定字给出了未知的高频数字估计。优势是从DDS固有的高分辨率和环路噪声免疫力而来，从而设计同样精确和不受影响的频率计。所有额外相关的阶段都被仪器的显示器显示出来。

1简介

最常用的测频技术采用计数在预定的时间窗口（光圈）的未知频率的脉冲的计数器。此外，凡任何参考频率的脉冲在一个或多个未知一期计算方法也很常见。在后一种情况下，代替频率的周期只是估计的。本文献的第[1]部分的某些文件处理了低频率的测量问题并集中在心脏（心脏）信号的频率范围（几赫兹）或在电源频率（50-60赫兹）。这些技术实际上是在测量讯号的时间，并使用一些方法来计算它的倒数，即频率。在第[2]中，频率由查找表的方法计算。其他[4-6]的内容是关于微处理器或以微控制器为基础的。

上述方法的特点是开环方法，即数字计数器来计数在预定tinle间隔，之后计算结果。其闭环形式刻画了本文提出的方法。这个术语“闭环”我们用来记一些反馈排序。一个已知（控制）的频率波形在电路中产生，并反馈到强制它来接近未知的（输入）的频率的频率比较阶段。产生上述提及的受控的频率波形是一个直接数字合成器。

2直接数字频率合成器

一个典型的直接数字频率合成器包含一个正弦波（正弦查找表LUT）样品的RAM。在限定相位跳跃的频率设置字的控制方式下来搜寻这些样本。一个典型

1外文文献翻译原文及译文汇总

华北电力大学科技学院 毕业设计（论文）附件 外文文献翻译 学号：121912020115姓名：彭钰钊 所在系别：动力工程系专业班级：测控技术与仪器12K1指导教师：李冰 原文标题：Infrared Remote Control System Abstract 2016 年 4 月 19 日

红外遥控系统 摘要 红外数据通信技术是目前在世界范围内被广泛使用的一种无线连接技术，被众多的硬件和软件平台所支持。红外收发器产品具有成本低，小型化，传输速率快，点对点安全传输，不受电磁干扰等特点，可以实现信息在不同产品之间快速、方便、安全地交换与传送，在短距离无线传输方面拥有十分明显的优势。红外遥控收发系统的设计在具有很高的实用价值，目前红外收发器产品在可携式产品中的应用潜力很大。全世界约有1亿5千万台设备采用红外技术，在电子产品和工业设备、医疗设备等领域广泛使用。绝大多数笔记本电脑和手机都配置红外收发器接口。随着红外数据传输技术更加成熟、成本下降，红外收发器在短距离通讯领域必将得到更广泛的应用。 本系统的设计目的是用红外线作为传输媒质来传输用户的操作信息并由接收电路解调出原始信号，主要用到编码芯片和解码芯片对信号进行调制与解调，其中编码芯片用的是台湾生产的PT2262，解码芯片是PT2272。主要工作原理是：利用编码键盘可以为PT2262提供的输入信息，PT2262对输入的信息进行编码并加载到38KHZ的载波上并调制红外发射二极管并辐射到空间，然后再由接收系统接收到发射的信号并解调出原始信息，由PT2272对原信号进行解码以驱动相应的电路完成用户的操作要求。 关键字：红外线；编码；解码；LM386；红外收发器。 1 绪论

快速外文文献翻译

快速外文文献翻译 在科研过程中阅读翻译外文文献是一个非常重要的环节，许多领域高水平的文献都是外文文献，借鉴一些外文文献翻译的经验是非常必要的。由于特殊原因我翻译外文文献的机会比较多，慢慢地就发现了外文文献翻译过程中的三大利器：Google“翻译”频道、金山词霸（完整版本）和CNKI“翻译助手"。 具体操作过程如下： 1.先打开金山词霸自动取词功能，然后阅读文献； 2.遇到无法理解的长句时，可以交给Google处理，处理后的结果猛一看，不堪入目，可是经过大脑的再处理后句子的意思基本就明了了； 3.如果通过Google仍然无法理解，感觉就是不同，那肯定是对其中某个“常用单词”理解有误，因为某些单词看似很简单，但是在文献中有特殊的意思，这时就可以通过CNKI的“翻译助手”来查询相关单词的意思，由于CNKI的单词意思都是来源与大量的文献，所以它的吻合率很高。 另外，在翻译过程中最好以“段落”或者“长句”作为翻译的基本单位，这样才不会造成“只见树木，不见森林”的误导。 注： 1、Google翻译：https://www.sodocs.net/doc/0c17793511.html,/language_tools google，众所周知，谷歌里面的英文文献和资料还算是比较详实的。我利用它是这样的。一方面可以用它查询英文论文，当然这方面的帖子很多，大家可以搜索，在此不赘述。回到我自己说的翻译上来。下面给大家举个例子来说明如何用吧比如说“电磁感应透明效应”这个词汇你不知道他怎么翻译， 首先你可以在CNKI里查中文的，根据它们的关键词中英文对照来做，一般比较准确。 在此主要是说在google里怎么知道这个翻译意思。大家应该都有词典吧，按中国人的办法，把一个一个词分着查出来，敲到google里，你的这种翻译一般不太准，当然你需要验证是否准确了，这下看着吧，把你的那支离破碎的翻译在google里搜索，你能看到许多相关的文献或资料，大家都不是笨蛋，看看，也就能找到最精确的翻译了，纯西式的！我就是这么用的。 2、CNKI翻译：https://www.sodocs.net/doc/0c17793511.html, CNKI翻译助手，这个网站不需要介绍太多，可能有些人也知道的。主要说说它的有点，你进去看看就能发现：搜索的肯定是专业词汇，而且它翻译结果下面有文章与之对应（因为它是CNKI检索提供的，它的翻译是从文献里抽出来的），很实用的一个网站。估计别的写文章的人不是傻子吧，它们的东西我们可以直接拿来用，当然省事了。网址告诉大家，有兴趣的进去看看，你们就会发现其乐无穷！还是很值得用的。https://www.sodocs.net/doc/0c17793511.html, 3、网路版金山词霸（不到1M）：https://www.sodocs.net/doc/0c17793511.html,/6946901637944806 翻译时的速度： 这里我谈的是电子版和打印版的翻译速度，按个人翻译速度看，打印版的快些，因为看电子版本一是费眼睛，二是如果我们用电脑，可能还经常时不时玩点游戏，或者整点别的，导致最终SPPEED变慢，再之电脑上一些词典（金山词霸等）在专业翻译方面也不是特别好，所以翻译效果不佳。在此本人建议大家购买清华大

概率论毕业论文外文翻译

Statistical hypothesis testing Adriana Albu，Loredana Ungureanu Politehnica University Timisoara,adrianaa@aut.utt.ro Politehnica University Timisoara,loredanau@aut.utt.ro Abstract In this article,we present a Bayesian statistical hypothesis testing inspection, testing theory and the process Mentioned hypothesis testing in the real world and the importance of, and successful test of the Notes. Key words Bayesian hypothesis testing; Bayesian inference;Test of significance Introduction A statistical hypothesis test is a method of making decisions using data, whether from a controlled experiment or an observational study (not controlled). In statistics, a result is called statistically significant if it is unlikely to have occurred by chance alone, according to a pre-determined threshold probability, the significance level. The phrase "test of significance" was coined by Ronald Fisher: "Critical tests of this kind may be called tests of significance, and when such tests are available we may discover whether a second sample is or is not significantly different from the first."[1] Hypothesis testing is sometimes called confirmatory data analysis, in contrast to exploratory data analysis. In frequency probability,these decisions are almost always made using null-hypothesis tests. These are tests that answer the question Assuming that the null hypothesis is true, what is the probability of observing a value for the test statistic that is at [] least as extreme as the value that was actually observed?) 2 More formally, they represent answers to the question, posed before undertaking an experiment,of what outcomes of the experiment would lead to rejection of the null hypothesis for a pre-specified probability of an incorrect rejection. One use of hypothesis testing is deciding whether experimental results contain enough information to cast doubt on conventional wisdom. Statistical hypothesis testing is a key technique of frequentist statistical inference. The Bayesian approach to hypothesis testing is to base rejection of the hypothesis on the posterior probability.[3][4]Other approaches to reaching a decision based on data are available via decision theory and optimal decisions. The critical region of a hypothesis test is the set of all outcomes which cause the null hypothesis to be rejected in favor of the alternative hypothesis. The critical region is usually denoted by the letter C. One-sample tests are appropriate when a sample is being compared to the population from a hypothesis. The population characteristics are known from theory or are calculated from the population.

毕业论文英文参考文献与译文

Inventory management Inventory Control On the so-called "inventory control", many people will interpret it as a "storage management", which is actually a big distortion. The traditional narrow view, mainly for warehouse inventory control of materials for inventory, data processing, storage, distribution, etc., through the implementation of anti-corrosion, temperature and humidity control means, to make the custody of the physical inventory to maintain optimum purposes. This is just a form of inventory control, or can be defined as the physical inventory control. How, then, from a broad perspective to understand inventory control? Inventory control should be related to the company's financial and operational objectives, in particular operating cash flow by optimizing the entire demand and supply chain management processes (DSCM), a reasonable set of ERP control strategy, and supported by appropriate information processing tools, tools to achieved in ensuring the timely delivery of the premise, as far as possible to reduce inventory levels, reducing inventory and obsolescence, the risk of devaluation. In this sense, the physical inventory control to achieve financial goals is just a means to control the entire inventory or just a necessary part; from the perspective of organizational functions, physical inventory control, warehouse management is mainly the responsibility of The broad inventory control is the demand and supply chain management, and the whole company's responsibility. Why until now many people's understanding of inventory control, limited physical inventory control? The following two reasons can not be ignored: First, our enterprises do not attach importance to inventory control. Especially those who benefit relatively good business, as long as there is money on the few people to consider the problem of inventory turnover. Inventory control is simply interpreted as warehouse management, unless the time to spend money, it may have been to see the inventory problem, and see the results are often very simple procurement to buy more, or did not do warehouse departments . Second, ERP misleading. Invoicing software is simple audacity to call it ERP, companies on their so-called ERP can reduce the number of inventory, inventory control, seems to rely on their small software can get. Even as SAP, BAAN ERP world, the field of

人力资源管理外文文献翻译

文献信息： 文献标题：Challenges and opportunities affecting the future of human resource management（影响人力资源管理未来的挑战和机遇） 国外作者：Dianna L. Stone，Diana L. Deadrick 文献出处：《Human Resource Management Review》, 2015, 25(2):139-145 字数统计：英文3725单词，21193字符；中文6933汉字 外文文献： Challenges and opportunities affecting the future of human resource management Abstract Today, the field of Human Resource Management (HR) is experiencing numerous pressures for change. Shifts in the economy, globalization, domestic diversity, and technology have created new demands for organizations, and propelled the field in some completely new directions. However, we believe that these challenges also create numerous opportunities for HR and organizations as a whole. Thus, the primary purposes of this article are to examine some of the challenges and opportunities that should influence the future of HR. We also consider implications for future research and practice in the field. Keywords: Future of human resource management, Globalization, Knowledge economy Diversity, Technology 1.Change from a manufacturing to a service or knowledge economy One of the major challenges influencing the future of HR processes is the change from a manufacturing to a service or knowledgebased economy. This new economy is characterized by a decline in manufacturing and a growth in service or knowledge as the core of the economic base. A service economy can be defined as a system based on buying and selling of services or providing something for others (Oxford

外文文献及翻译

文献翻译 原文 Combining JSP and Servlets The technology of JSP and Servlet is the most important technology which use Java technology to exploit request of server, and it is also the standard which exploit business application .Java developers prefer to use it for a variety of reasons, one of which is already familiar with the Java language for the development of this technology are easy to learn Java to the other is "a preparation, run everywhere" to bring the concept of Web applications, To achieve a "one-prepared everywhere realized." And more importantly, if followed some of the principles of good design, it can be said of separating and content to create high-quality, reusable, easy to maintain and modify the application. For example, if the document in HTML embedded Java code too much (script), will lead the developed application is extremely complex, difficult to read, it is not easy reuse, but also for future maintenance and modification will also cause difficulties. In fact, CSDN the JSP / Servlet forum, can often see some questions, the code is very long, can logic is not very clear, a large number of HTML and Java code mixed together. This is the random development of the defects. Early dynamic pages mainly CGI (Common Gateway Interface, public Gateway Interface) technology, you can use different languages of the CGI programs, such as VB, C / C + + or Delphi, and so on. Though the technology of CGI is developed and powerful, because of difficulties in programming, and low efficiency, modify complex shortcomings, it is gradually being replaced by the trend. Of all the new technology, JSP / Servlet with more efficient and easy to program, more powerful, more secure and has a good portability, they have been many people believe that the future is the most dynamic site of the future development of technology. Similar to CGI, Servlet support request / response model. When a customer submit a request to the server, the server presented the request Servlet, Servlet responsible for handling requests and generate a response, and then gave the server, and then from the server sent to

英文文献翻译

中等分辨率制备分离的 快速色谱技术 W. Clark Still,* Michael K a h n , and Abhijit Mitra Departm(7nt o/ Chemistry, Columbia Uniuersity,1Veu York, Neu; York 10027 ReceiLied January 26, 1978 我们希望找到一种简单的吸附色谱技术用于有机化合物的常规净化。这种技术是适于传统的有机物大规模制备分离，该技术需使用长柱色谱法。尽管这种技术得到的效果非常好，但是其需要消耗大量的时间，并且由于频带拖尾经常出现低复原率。当分离的样本剂量大于1或者2g时，这些问题显得更加突出。近年来，几种制备系统已经进行了改进，能将分离时间减少到1-3h，并允许各成分的分辨率ΔR f≥（使用薄层色谱分析进行分析）。在这些方法中，在我们的实验室中，媒介压力色谱法1和短柱色谱法2是最成功的。最近，我们发现一种可以将分离速度大幅度提升的技术，可用于反应产物的常规提纯，我们将这种技术称为急骤色谱法。虽然这种技术的分辨率只是中等（ΔR f≥），而且构建这个系统花费非常低，并且能在10-15min内分离重量在的样本。4 急骤色谱法是以空气压力驱动的混合介质压力以及短柱色谱法为基础，专门针对快速分离，介质压力以及短柱色谱已经进行了优化。优化实验是在一组标准条件5下进行的，优化实验使用苯甲醇作为样本，放在一个20mm*5in.的硅胶柱60内，使用Tracor 970紫外检测器监测圆柱的输出。分辨率通过持续时间（r）和峰宽（w,w/2）的比率进行测定的（Figure 1），结果如图2-4所示，图2-4分别放映分辨率随着硅胶颗粒大小、洗脱液流速和样本大小的变化。

毕业论文外文翻译模版

吉林化工学院理学院 毕业论文外文翻译English Title（Times New Roman ，三号） 学生学号：08810219 学生姓名：袁庚文 专业班级：信息与计算科学0802 指导教师：赵瑛 职称副教授 起止日期：2012.2.27～2012.3.14 吉林化工学院 Jilin Institute of Chemical Technology

1 外文翻译的基本内容 应选择与本课题密切相关的外文文献（学术期刊网上的），译成中文，与原文装订在一起并独立成册。在毕业答辩前，同论文一起上交。译文字数不应少于3000个汉字。 2 书写规范 2.1 外文翻译的正文格式 正文版心设置为：上边距：3.5厘米，下边距：2.5厘米，左边距：3.5厘米，右边距：2厘米，页眉：2.5厘米，页脚：2厘米。 中文部分正文选用模板中的样式所定义的“正文”，每段落首行缩进2字；或者手动设置成每段落首行缩进2字，字体：宋体，字号：小四，行距：多倍行距1.3，间距：前段、后段均为0行。 这部分工作模板中已经自动设置为缺省值。 2.2标题格式 特别注意：各级标题的具体形式可参照外文原文确定。 1．第一级标题（如：第1章绪论）选用模板中的样式所定义的“标题1”，居左；或者手动设置成字体：黑体，居左，字号：三号，1.5倍行距，段后11磅，段前为11磅。 2．第二级标题（如：1.2 摘要与关键词）选用模板中的样式所定义的“标题2”，居左；或者手动设置成字体：黑体，居左，字号：四号，1.5倍行距，段后为0，段前0.5行。 3．第三级标题（如：1.2.1 摘要）选用模板中的样式所定义的“标题3”，居左；或者手动设置成字体：黑体，居左，字号：小四，1.5倍行距，段后为0，段前0.5行。 标题和后面文字之间空一格（半角）。 3 图表及公式等的格式说明 图表、公式、参考文献等的格式详见《吉林化工学院本科学生毕业设计说明书（论文）撰写规范及标准模版》中相关的说明。

大学毕业论文---软件专业外文文献中英文翻译

软件专业毕业论文外文文献中英文翻译 Object landscapes and lifetimes Tech nically, OOP is just about abstract data typing, in herita nee, and polymorphism, but other issues can be at least as importa nt. The rema in der of this sect ion will cover these issues. One of the most importa nt factors is the way objects are created and destroyed. Where is the data for an object and how is the lifetime of the object con trolled? There are differe nt philosophies at work here. C++ takes the approach that con trol of efficie ncy is the most importa nt issue, so it gives the programmer a choice. For maximum run-time speed, the storage and lifetime can be determined while the program is being written, by placing the objects on the stack (these are sometimes called automatic or scoped variables) or in the static storage area. This places a priority on the speed of storage allocatio n and release, and con trol of these can be very valuable in some situati ons. However, you sacrifice flexibility because you must know the exact qua ntity, lifetime, and type of objects while you're writing the program. If you are trying to solve a more general problem such as computer-aided desig n, warehouse man ageme nt, or air-traffic con trol, this is too restrictive. The sec ond approach is to create objects dyn amically in a pool of memory called the heap. In this approach, you don't know un til run-time how many objects you n eed, what their lifetime is, or what their exact type is. Those are determined at the spur of the moment while the program is runnin g. If you n eed a new object, you simply make it on the heap at the point that you n eed it. Because the storage is man aged dyn amically, at run-time, the amount of time required to allocate storage on the heap is sig ni fica ntly Ion ger tha n the time to create storage on the stack. (Creat ing storage on the stack is ofte n a si ngle assembly in structio n to move the stack poin ter dow n, and ano ther to move it back up.) The dyn amic approach makes the gen erally logical assumpti on that objects tend to be complicated, so the extra overhead of finding storage and releas ing that storage will not have an importa nt impact on the creati on of an object .In additi on, the greater flexibility is esse ntial to solve the gen eral program ming problem. Java uses the sec ond approach, exclusive". Every time you want to create an object, you use the new keyword to build a dyn amic in sta nee of that object. There's ano ther issue, however, and that's the lifetime of an object. With Ian guages that allow objects to be created on the stack, the compiler determines how long the object lasts and can automatically destroy it. However, if you create it on the heap the compiler has no kno wledge of its lifetime. In a Ianguage like C++, you must determine programmatically when to destroy the

客户关系管理外文文献翻译(2017)

XXX学院 毕业设计(论文)外文资料翻译 学院：计算机与软件工程学院 专业：计算机科学技术(软件工程方向) 姓名： 学号： 外文出处：GoyKakus.THE RESEARCH OFCUSTOMER RELATIONSHIP MANAGEMENT STRATEGY [J]. International Journal of Management Research & Review, 2017, 1(9): 624-635. 附件： 1.外文资料翻译译文；2.外文原文。 注：请将该封面与附件装订成册。

附件1：外文资料翻译译文 客户关系管理战略研究 Goy Kakus 摘要 客户关系管理解决方案，通过为你提供客户业务数据来帮助你提供客户想要的服务或产品,提供更好的客户服务、交叉销售和更有效的销售,达成交易,保留现有客户并更好地理解你的客户是谁。本文探讨了客户关系管理模型在获得、保持与发展策略方面的优势。然而,我们对其定义和意义还存在一些困惑。本文通过考察关系营销和其他学科方面的相关文献，解释了客户关系管理的概念基础,从而对客户关系管理的知识作出了贡献。 关键词:客户关系管理模型, 客户关系管理的博弈改变者与关键策略 引言 CRM 是客户关系管理的简称。它的特征在于公司与客户的沟通,无论是销售还是服务相关的。客户关系管理这一术语经常用来解释企业客户关系,客户关系管理系统也以同样的方式被用来处理商业联系, 赢得客户,达成合同和赢得销售。 客户关系管理通常被考虑作为一个业务策略，从而使企业能够: *了解客户 *通过更好的客户体验留住客户 *吸引新客户 *赢得新客户和达成合同 *提高盈利 *减少客户管理成本 *通过服务台等工具软件,电子邮件组织者和不同类型的企业应用程序，企业业务经常寻求个性化的在线体验。 设计精良的客户关系管理包括以下特征: 1．客户关系管理是一种以顾客为中心并以客户投入为基础的服务响应，一对一的解决客户的必需品, 买家和卖家服务中心直接在线互动,帮助客户解决他

文献翻译英文原文

https://www.sodocs.net/doc/0c17793511.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

第三方物流外文文献(原文与翻译)

我国第三方物流中存在的问题、原因及战略选择 熊卫 【摘要】我国物流业发展刚刚起步，第三方物流的理论和实践等方面都比较薄弱。本文指出我国第三方物流存在的问题在于国内外第三方物流企业差距、物流效率不高、缺乏系统性管理、物流平台构筑滞后、物流管理观念落后等。分析了产生上述问题的原因，并提出了精益物流、中小型第三方物流企业价值链联盟、大型第三方物流企业虚拟化战略等三种可供选择的第三方物流企业发展战略。 【关键词】第三方物流；精益物流战略；价值链联盟；虚拟化战略 1引言 长期以来，我国国内企业对采购、运输、仓储、代理、包装、加工、配送等环节控制能力不强，在“采购黑洞”、“物流陷井”中造成的损失浪费难以计算。因此，对第三方物流的研究，对于促进我国经济整体效益的提高有着非常重要的理论和实践意义。本文试图对我国策三方物流存在的问题及原因进行分析探讨，并提出第三方物流几种可行的战略选择。 2我国第三方物流业存在的主要问题 (一)我国策三方物流企业与国外第三方物流企业的差距较大，具体表现在以下几个方面： 1、规模经济及资本差距明显。由于国外的大型第三方物流企业从全球经营的战略出发，其规模和资本优势是毫无疑问的，尤其初创时期的我国策三方物流业，本身的规模就很小，国外巨头雄厚的资本令国内企业相形见绌。 2、我国策三方物流业企业提供的物流服务水准及质量控制远不如国外同行。当国内一些企业还在把物流理解成“卡车加仓库“的时候，国外的物流企业早已完成了一系列标准化的改造。同时，国外的物流组织能力非常强大，例如德国一家第三方物流公司，公司各方面的物流专家遍布欧洲各地。如果有客户的货物需要经达不同的国家，那么欧洲各地的这些专家就在网上设计出一个最佳的物流解决方案。这种提供解决方案的能力就是这第三方物流公司的核心能力，而不像国内公司号称拥有多少条船，多少辆车。 3、我国加入WTO后物流产业的门槛降低。在物流服务业方面：我国承诺所有的服务行业，在经过合理过渡期后，取消大部分外国股权限制，不限制外国服务供应商进入