篇一：计算机系——外文翻译(中英对照,3000汉字左右)
毕业设计(论文)外文资料翻译
系 别计算机信息与技术系
专 业计算机科学与技术
班 级
姓 名学 号
外文出处
附 件 1. 原文； 2. 译文
2012年3月
History of computing
Main article: History of computing hardware
The first use of the word "computer" was recorded in 1613, referring to a person who carried out calculations, or computations, and the word continued with the same meaning until the middle of the 20th century. From the end of the 19th century the word began to take on its more familiar meaning, a machine that carries out computations.
Limited-function early computers
The Jacquard loom, on display at the Museum of Science and Industry in Manchester, England, was one of the first programmable devices.
The history of the modern computer begins with two separate technologies, automated calculation and programmability, but no single device can be identified as the earliest computer, partly because of the inconsistent application of that term. A few devices are worth mentioning though, like some mechanical aids to computing, which were very successful and survived for centuries until the advent of the electronic calculator, like the Sumerian abacus, designed around 2500 BC of which a descendant won a speed competition against a modern desk calculating machine in Japan in 1946, the slide rules, invented in the 1620s, which were carried on five Apollo space missions, including to the moon and arguably the astrolabe and the Antikythera mechanism, an ancient astronomical computer built by the Greeks around 80 BC. The Greek mathematician Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when. This is the essence of programmability.
Around the end of the 10th century, the French monk Gerbert d'Aurillac brought back from Spain the drawings of a machine invented by the Moors that answered either Yes or No to the questions it was asked. Again in the 13th century, the monks Albertus Magnus and Roger Bacon built talking androids without any further development.
In 1642, the Renaissance saw the invention of the mechanical calculator, a device that could perform all four arithmetic operations without relying on human intelligence. The mechanical calculator was at the root of the development of
computers in two separate ways. Initially, it was in trying to develop more powerful and more flexible calculators that the computer was first theorized by Charles Babbage and then developed. Secondly, development of a low-cost electronic calculator, successor to the mechanical calculator, resulted in the development by Intel of the first commercially available microprocessor integrated circuit.
First general-purpose computers
In 1801, Joseph Marie Jacquard made an improvement to the textile loom by introducing a series of punched paper cards as a template which allowed his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability.
In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer, his analytical engine. Limited finances and Babbage's inability to resist tinkering with the design meant that the device was never completed ; nevertheless his son, Hey Babbage, completed a simplified version of the analytical engine's computing unit (the mill) in 1888. He gave a successful demonstration of its use in computing tables in 1906. This machine was given to the Science museum in South Kensington in 1910.
In the late 1880s, Herman Hollerith invented the recording of data on a machine-readable medium. Earlier uses of machine-readable media had been for control, not data. "After some initial trials with paper tape, he settled on punched cards ..." To process these punched cards he invented the tabulator, and the keypunch machines. These three inventions were the foundation of the modern information processing industry. Large-scale automated data processing of punched cards was performed for the 1890 United States Census by Hollerith's company, which later became the core of IBM. By the end of the 19th century a number of ideas and technologies, that would later prove useful in the realization of practical computers, had begun to appear: Boolean algebra, the vacuum tube (thermionic valve), punched cards and tape, and the teleprinter.
During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digital
computers.
Alan Turing is widely regarded as the father of modern computer science. In 1936 Turing provided an influential formalisation of the concept of the algorithm and computation with the Turing machine, providing a blueprint for the electronic digital computer. Of his role in the creation of the modern computer, Time magazine in naming Turing one of the 100 most influential people of the 20th century, states: "The fact remains that everyone who taps at a keyboard, opening a spreadsheet or a word-processing program, is working on an incarnation of a Turing machine".
EDSAC was one of the first computers to implement the stored-program (von Neumann) architecture.
Die of an Intel 80486DX2 microprocessor (actual size: 12×6.75 mm) in its packaging.
The Atanasoff–Berry Computer (ABC) was the world's first electronic digital computer, albeit not programmable. Atanasoff is considered to be one of the fathers of the computer.Conceived in 1937 by Iowa State College physics professor John Atanasoff, and built with the assistance of graduate student Clifford Berry, the machine was not programmable, being designed only to solve systems of linear equations. The computer did employ parallel computation. A 1973 court ruling in a patent dispute found that the patent for the 1946 ENIAC computer derived from the Atanasoff–Berry Computer.
The first program-controlled computer was invented by Koad Zuse, who built the Z3, an electromechanical computing machine, in 1941. The first programmable electronic computer was the Colossus, built in 1943 by Tommy Flowers.
George Stibitz is internationally recognized as a father of the modern digital computer. While working at Bell Labs in November 1937, Stibitz invented and built a relay-based calculator he dubbed the "Model K" (for "kitchen table", on which he had assembled it), which was the first to use binary circuits to perform an arithmetic operation. Later models added greater sophistication including complex arithmetic and programmability.
A succession of steadily more powerful and flexible computing devices were constructed in the 1930s and 1940s, gradually adding the key features that are seen in modern computers. The use of digital electronics (largely invented by Claude Shannon in 1937) and more flexible programmability were vitally important steps, but defining one point along this road as "the first digital electronic computer" is difficult.
Notable achievements include. Koad Zuse's electromechanical "Z machines". The Z3 (1941) was the first working machine featuring binary arithmetic, including floating point arithmetic and a measure of programmability. In 1998 the Z3 was proved to be Turing complete, therefore being the world's first operational computer.
The non-programmable Atanasoff–Berry Computer (commenced in 1937, completed in 1941) which used vacuum tube based computation, binary numbers, and regenerative capacitor memory. The use of regenerative memory allowed it to be much more compact than its peers (being approximately the size of a large desk or workbench), since intermediate results could be stored and then fed back into the same set of computation elements.
The secret British Colossus computers (1943), which had limited programmability but demonstrated that a device using thousands of tubes could be reasonably reliable and electronically reprogrammable. It was used for breaking German wartime codes.
The Harvard Mark I (1944), a large-scale electromechanical computer with limited programmability.
The U.S. Army's Ballistic Research Laboratory ENIAC (1946), which used decimal arithmetic and is sometimes called the first general purpose electronic computer (since Koad Zuse's Z3 of 1941 used electromagnets instead of electronics). Initially, however, ENIAC had an inflexible architecture which essentially required rewiring to change its programming.
Stored-program architecture
Replica of the Small-Scale Experimental Machine (SSEM), the world's first stored-program computer, at the Museum of Science and Industry in Manchester, England
Several developers of ENIAC, recognizing its flaws, came up with a far more flexible and elegant design, which came to be known as the "stored-program architecture" or von Neumann architecture. This design was first formally described by John von Neumann in the paper First Draft of a Report on the EDVAC, distributed in 1945. A number of projects to develop computers based on the stored-program architecture commenced around this time, the first of which was completed in 1948 at the University of Manchester in England, the Manchester Small-Scale Experimental Machine (SSEM or "Baby"). The Electronic Delay Storage Automatic Calculator
篇二：安卓系统的操作与应用外文文献翻译2014年译文3000字
文献出处：Philippe Nier, The operation and application of Android system [J]. International Journal on Computer Science & Engineering, 2014，13（05）：15-26
（声明：本译文归百度文库所有，完整译文请到百度文库。）
原文
The Operation and Application of Android System
Philippe·Nier
I. INTRODUCTION
Android is a software stack for mobile devices which includes an operating system, middleware and key applications. Since its official public release, Android has captured the interest from companies, developers and the general audience. From that time up to now, this software platform has been constantly improved either in terms of features or supported hardware and, at the same time, extended to new types of devices different from the originally intended mobile ones. Google entered into the mobile market not as a handset manufacturer, but by launching mobile platform called as “Android” for mobile devices such as Smart phones, PDA and net books on 5th November 2007. Google has a vision that Android based cell phone will have all the functions available in the latest PC. In order to make this effort possible, Google launched the Open Handset Alliance. Google introduced Android as an OS which runs the powerful applications and gives the users a choice to select their applications and their carriers. The Android platform is made by keeping in mind various sets of users who can use the available capacity within Android at different levels. Android is gaining strength both in the mobile industry and in other industries with different hardware architectures.
The increasing interest from the industry arises from two core aspects: its open-source nature and its architectural model. Being an open-source project, Android allows us to fully analyze and understand it, which enables feature comprehension, bug fixing, further improvements regarding new functionalities and finally, porting to new hardware. On the other hand, its Linux kernel-based architecture model also adds the use of Linux to the mobile industry, allowing to take advantage of the knowledge and
features offered by Linux. The Android platform consists of several layers which provide a complete software stack.
Android applications are Java-based and this factor entails the use of a virtual machine VM environment, with its advantages. Android uses its own VM called Dalvik, which interprets and executes portable Java-style byte code after transforming it, which is optimized to operate on the mobile platform. All of these aspects make Android an appealing target to be used in other type of environments.
The remainder of this paper is organized as follows: Section II briefly describes the Android’s background including architecture, features & programming framework. Section III presents detailed analysis of Android market including comparison with Symbian & Windows Mobile. Finally Section IV concludes this paper.
II. ANDROID BACKGROUND
A . Android Architecture
Android Architecture is shown in fig1, which consist of number of layers as Applications, Application framework, Libraries, Android runtime & Linux kernel [1]. Application layer is the uppermost layer which provides a set of core applications including an email, SMS program, calendar, maps, browser, contacts, and others. All applications are written using the Java programming language. It should be mentioned that applications can be run simultaneously; it is possible to hear music and read an email at the same time. The Application Framework is a software framework that is used to implement a standard structure of an application for a specific operating system. With the help of managers, content providers and other services programmers it can reassemble functions used by other existing applications.
Layer which is present below Application framework consist of two parts as Libraries which are all written in C/C++. They will be called through a Java interface. This includes the Surface Manager, 2D and 3D graphics, Media Codecs like MPEG-4 and MP3, the SQL database SQLite and the web browser engine WebKit. Second part is Android Runtime which includes a set of core libraries that provides most of the functionality available in the core libraries of the Java programming language. Every Android application runs in its own process, with its own instance of the Dalvik
virtual machine. The Dalvik VM executes files in the Dalvik Executable (.dex) format which is optimized for minimal memory footprint. The lowest layer is Linux Kernel, Android basically relies on Linux version 2.6 for core system services such as security, memory management, process management, network stack, and driver model. The kernel also acts as an abstraction layer between the hardware and the rest of the software stack.
B. Features of Android
Google Android has many features which make it special, but one important feature is Dalvik virtual machine (DVM) [5]. Which is a major component of Android platform. It is optimized for low memory requirements and is designed to allow multiple VM instances to run at the same time. The DVM runs Java applications. However, it is different from standard Java virtual machine in some ways. First, most virtual machines use a stack-based architecture, but Dalvik is a register-based architecture. Second, Dalvik runs Java applications which have been transformed into the Dalvik Executable (.dex) format which is optimized for minimal memory footprint The Dalvik VM relies on the Linux kernel for underlying functionality such as threading and low-level memory management. Java virtual machine tool interface (JVM TI) is a native programming interface on Java virtual machine. The interface provides functionalities to inspect the state of a virtual machine, gather information during run time, and also control the execution of applications running on the Java virtual machine. Android has built in integrated browser based on the open source WebKit engine & built in powerful SQL database engine called SQLite, use for structured data storage. Android support for common audio, video, and still image formats such as AAC, MPEG4, H.264, MP3, AMR, & contains Rich development environment including a device emulator, tools for debugging, & a plug-in for the Eclipse.
C. Android Programming Framework
The environment requires to develop application for Android consists of the Android SDK, the Eclipse IDE and the Java Development Kit (JDK) which has to be preinstalled for the installation of both, Android SDK and Eclipse. The following versions of the tools mentioned above are used & presented in figure below.
1) Android Software Development Kit: The Android SDK includes a comprehensive set of development tools. These include libraries, a handset emulator, documentation, sample code, tutorials & tools such as dx - Dalvik Cross-Assembler, aapt – Android Asset Packaging Tool & adb– Android Debug Bridge. Applications are written using the Java programming language and run on Dalvik, a custom virtual machine designed for embedded use which runs on top of a Linux kernel. The officially supported integrated development environment (IDE) is Eclipse (3.2 or later)
2) Android Emulator: The Android SDK includes a mobile device emulator -- a virtual mobile device that runs on your computer. The emulator lets you prototype, develop, and test Android applications without using a physical device. The Android emulator mimics all of the hardware and software features of a typical mobile device, except that it cannot receive or place actual phone calls. It provides a variety of navigation and control keys, which you can "press" using your mouse or keyboard to generate events for your application. It also provides a screen in which your application is displayed, together with any other Android applications running. To let you model and test your application more easily, the emulator supports Android Virtual Device (AVD) configurations. AVDs let you specify the Android platform that you want to run on the emulator, as well as the hardware options and emulator skin files that you want to use.
III. ANDROID MARKET ANALYSIS
A. Android Market
The Android Market, an online software store, is developed by Google for Android devices. It was made available to users on October 22, 2008. Most of the Android devices come with preinstalled “Market” application which allows users to browse, buy, download, and rate different available applications and other content for mobile phones equipped with the open-source operating system. Unlike with the iPhone App Store, there is no requirement that Android apps should be acquired from Android Market [2]. Android apps may be obtained from any source including a developer's own website. Also, Android developers can create their own application market. Google does not have a strict requirement for the application to show up on the
Android Market compared to the process used by Apple. Lastly, the Android Market follows a 70/30 revenue-sharing model for applications developed by developers. The developers of priced applications receive 70% of the application price and remaining 30% distributes. As of May 04, 2010, Android apps hit around 49,000 applications which were around 12,500 in August 2009 and 20,000 in December 2009. The global smart phone sell in second quarter of 2009 & 2010 are shown bellow.
B. Android vs. Symbian vs. Windows Mobile
Comparison is based on main criteria as follows.
1) Portability: Portability is a very important assessment criterion. Symbian OS has many references in this area and having standardized architecture and the openness to software. But the fact that Symbian mostly runs on Nokia cell phones and that it is not Java based lets it fall behind Android. Unfortunately Windows Mobile also has several applications that are specific to certain hardware platforms and therefore are not portable. The Android Mobile platform is a Linux & Java based which allow us to use it on many different platforms unlike Symbian & Win Mobile. As a result Android gets one point, Symbian OS gets half a point and Windows Mobile zero points.
译文
安卓系统的操作与应用
菲利普·尼埃
1引言
安卓是一个包括操作系统和关键应用程序的移动软件堆栈设备。自谷歌官方公开发布该系统以来，安卓吸引了公司、开发人员和大众的兴趣。从那时到现在，这一软件平台不断的得到改善，支持更多的硬件，同时扩展到许多新类型的设备上。从此，谷歌进入了手机市场而不是作为一个手机制造商，不过谷歌于2007年11月5日推出自己的“Android”的智能手机、PDA等移动设备。谷歌的愿景是安装Android系统的手机将能够拥有与最新的电脑一样的所有功能。为了使这
篇三：计算机外文文献翻译
外文文献：
Core Java? Volume II–Advanced Features
When Java technology first appeared on the scene, the excitement was not about a well-crafted programming language but about the possibility of safely executing applets that are delivered over the Internet (see Volume I, Chapter 10 for more information about applets). Obviously, delivering executable applets is practical only when the recipients are sure that the code can't wreak havoc on their machines. For this reason, security was and is a major concern of both the designers and the users of Java technology. This means that unlike other languages and systems, where security was implemented as an afterthought or a reaction to break-ins, security mechanisms are an integral part of Java technology.
Three mechanisms help ensure safety:
? Language design features (bounds checking on arrays, no unchecked type conversions, no pointer arithmetic, and so on).
? An access control mechanism that controls what the code can do (such as file access, network access, and so on).
? Code signing, whereby code authors can use standard cryptographic algorithms to authenticate Java code. Then, the users of the code can determine exactly who created the code and whether the code has been altered after it was signed.
Below, you'll see the cryptographic algorithms supplied in the java.security package, which allow for code signing and user authentication.
As we said earlier, applets were what started the craze over the Java platform. In practice, people discovered that although they could write animated applets like the famous "nervous text" applet, applets could not do a whole lot of useful stuff in the JDK 1.0 security model. For example, because applets under JDK 1.0 were so closely supervised, they couldn't do much good on a corporate intranet, even though relatively little risk attaches to executing an applet from your company's secure intranet. It quickly became clear to Sun that for applets to become truly useful, it was important for users to be able to assign different levels of security, depending on where the applet originated. If an applet comes from a trusted supplier and it has not been tampered with,
the user of that applet can then decide whether to give the applet more privileges.
To give more trust to an applet, we need to know two things:
? Where did the applet come from?
? Was the code corrupted in transit?
In the past 50 years, mathematicians and computer scientists have developed sophisticated algorithms for ensuring the integrity of data and for electronic signatures. The java.security package contains implementations of many of these algorithms. Fortunately, you don't need to understand the underlying mathematics to use the algorithms in the java.security package. In the next sections, we show you how message digests can detect changes in data files and how digital signatures can prove the identity of the signer.
A message digest is a digital fingerprint of a block of data. For example, the so-called SHA1 (secure hash algorithm #1) condenses any data block, no matter how long, into a sequence of 160 bits (20 bytes). As with real fingerprints, one hopes that no two messages have the same SHA1 fingerprint. Of course, that cannot be true—there are only 2160 SHA1 fingerprints, so there must be some messages with the same fingerprint. But 2160 is so large that the probability of duplication occurring is negligible. How negligible? According to James Walsh in True Odds: How Risks Affect Your Everyday Life (Merritt Publishing 1996), the chance that you will die from being struck by lightning is about one in 30,000. Now, think of nine other people, for example, your nine least favorite managers or professors. The chance that you and all of them will die from lightning strikes is higher than that of a forged message having the same SHA1 fingerprint as the original. (Of course, more than ten people, none of whom you are likely to know, will die from lightning strikes. However, we are talking about the far slimmer chance that your particular choice of people will be wiped out.)
A message digest has two essential properties:
? If one bit or several bits of the data are changed, then the message digest also changes. ? A forger who is in possession of a given message cannot construct a fake message that has the same message digest as the original.
The second property is again a matter of probabilities, of course. Consider the following message by the billionaire father:"Upon my death, my property shall be divided equally among my children; however, my son George shall receive nothing."
That message has an SHA1 fingerprint of
2D 8B 35 F3 BF 49 CD B1 94 04 E0 66 21 2B 5E 57 70 49 E1 7E
The distrustful father has deposited the message with one attorney and the fingerprint with another. Now, suppose George can bribe the lawyer holding the message. He wants to change the message so that Bill gets nothing. Of course, that changes the fingerprint to a completely different bit pattern:
2A 33 0B 4B B3 FE CC 1C 9D 5C 01 A7 09 51 0B 49 AC 8F 98 92
Can George find some other wording that matches the fingerprint? If he had been the proud owner of a billion computers from the time the Earth was formed, each computing a million messages a second, he would not yet have found a message he could substitute.
A number of algorithms have been designed to compute these message digests. The two best-known are SHA1, the secure hash algorithm developed by the National Institute of Standards and Technology, and MD5, an algorithm invented by Ronald Rivest of MIT. Both algorithms scramble the bits of a message in ingenious ways. For details about these algorithms, see, for example, Cryptography and Network Security, 4th ed., by William Stallings (Prentice Hall 2005). Note that recently, subtle regularities have been discovered in both algorithms. At this point, most cryptographers recommend avoiding MD5 and using SHA1 until a stronger alternative becomes available. (See /rsalabs/node.asp?id=2834 for more information.)
The Java programming language implements both SHA1 and MD5. The MessageDigest class is a factory for creating objects that encapsulate the fingerprinting algorithms. It has a static method, called getInstance, that returns an object of a class that extends the MessageDigest class. This means the MessageDigest class serves double duty:
? As a factory class
? As the superclass for all message digest algorithms
For example, here is how you obtain an object that can compute SHA fingerprints:
MessageDigest alg = MessageDigest.getInstance("SHA-1");
(To get an object that can compute MD5, use the string "MD5" as the argument to getInstance.)
After you have obtained a MessageDigest object, you feed it all the bytes in the message by repeatedly calling the update method. For example, the following code passes all bytes in a file to
the alg object just created to do the fingerprinting：
InputStream in = . . .
int ch;
while ((ch = in.read()) != -1)
alg.update((byte) ch);
Alternatively, if you have the bytes in an array, you can update the entire array at once:
byte[] bytes = . . .;
alg.update(bytes);
When you are done, call the digest method. This method pads the input—as required by the fingerprinting algorithm—does the computation, and returns the digest as an array of bytes.
byte[] hash = alg.digest();
The program in Listing 9-15 computes a message digest, using either SHA or MD5. You can load the data to be digested from a file, or you can type a message in the text area.
Message Signing
In the last section, you saw how to compute a message digest, a fingerprint for the original message. If the message is altered, then the fingerprint of the altered message will not match the fingerprint of the original. If the message and its fingerprint are delivered separately, then the recipient can check whether the message has been tampered with. However, if both the message and the fingerprint were intercepted, it is an easy matter to modify the message and then recompute the fingerprint. After all, the message digest algorithms are publicly known, and they don't require secret keys. In that case, the recipient of the forged message and the recomputed fingerprint would never know that the message has been altered. Digital signatures solve this problem.
To help you understand how digital signatures work, we explain a few concepts from the field called public key cryptography. Public key cryptography is based on the notion of a public key and private key. The idea is that you tell everyone in the world your public key. However, only you hold the private key, and it is important that you safeguard it and don't release it to anyone else. The keys are matched by mathematical relationships, but the exact nature of these relationships is not important for us. (If you are interested, you can look it up in The Handbook of Applied Cryptography at http://www.cacr.math.uwaterloo.ca/hac/.)
The keys are quite long and complex. For example, here is a matching pair of public and private Digital Signature Algorithm (DSA) keys.
Public key:
Code View:
p:
fca682ce8e12caba26efccf7110e526db078b05edecbcd1eb4a208f3ae1617ae01f35b91a47e6df63413c5e12ed0899bcd132acd50d99151bdc43ee737592e17
q: 962eddcc369cba8ebb260ee6b6a126d9346e38c5
g:678471b27a9cf44ee91a49c5147db1a9aaf244f05a434d6486931d2d14271b9e35030b71fd73da179069b32e2935630e1c2062354d0da20a6c416e50be794ca4
y:
c0b6e67b4ac098eb1a32c5f8c4c1f0e7e6fb9d832532e27d0bdab9ca2d2a8123ce5a8018b8161a760480fadd040b927281ddb22cb9bc4df596d7de4d1b977d50
Private key:
Code View:
p:
fca682ce8e12caba26efccf7110e526db078b05edecbcd1eb4a208f3ae1617ae01f35b91a47e6df63413c5e12ed0899bcd132acd50d99151bdc43ee737592e17
q: 962eddcc369cba8ebb260ee6b6a126d9346e38c5
g:
678471b27a9cf44ee91a49c5147db1a9aaf244f05a434d6486931d2d14271b9e35030b71fd73da179069b32e2935630e1c2062354d0da20a6c416e50be794ca4
x: 146c09f881656cc6c51f27ea6c3a91b85ed1d70a
It is believed to be practically impossible to compute one key from the other. That is, even though everyone knows your public key, they can't compute your private key in your lifetime, no matter how many computing resources they have available.
It might seem difficult to believe that nobody can compute the private key from the public keys, but nobody has ever found an algorithm to do this for the encryption algorithms that are in common use today. If the keys are sufficiently long, brute force—simply trying all possible keys—would require more computers than can be built from all the atoms in the solar system,
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