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外文資料
Introduction to Mechanical Design
Mechanical design is the application of science and technology to devise new or improved products for the purpose of satisfying human needs. It is a vast field of engineering technology which not only concerns itself with the original conception of the product in terms of its size, shape and construction details, but also considers the various factors involved in the manufacture, marketing and use of the product.
People who perform the various functions of mechanical design are typically called designers, or design engineers. Mechanical design is basically a creative activity. However, in addition to being innovative, a design engineer must also have a solid background in the areas of mechanical drawing, kinematics, dynamics, materials engineering, strength of materials and manufacturing processes.
As stated previously, the purpose of mechanical design is to produce a product which will serve a need for man. Inventions, discoveries and scientific knowledge by themselves do not necessarily benefit people; only if they are incorporated into a designed product will a benefit be derived. It should be recognized, therefore, that a human need must be identified before a particular product is designed.
Mechanical design should be considered to be an opportunity to use innovative talents to envision a design of a product, to analyze the system and then make sound judgments on how the product is to be manufactured. It is important to understand the fundamentals of engineering rather than memorize mere facts and equations. There are no facts or equations which alone can be used to provide all the correct decisions required to produce a good design. On the other hand, any calculation made must be done with the utmost care and precision. For example, if a decimal point is misplaced, a otherwise acceptable design may mot function.
Good designs require trying mew ideas and being willing to take a certain amount of risk, knowing that if the mew idea does not work the existing method can be reinstated. Thus a designer must have patience, since there is no assurance of success for the time and effort expended. Creating a completely new design generally requires that many old and well-established methods be thrust aside. This is not easy since many people cling to familiar ideas, techniques and attitudes. A design engineer should constantly search for ways to improve an existing product and must decide what old, proven concepts should be used and what new, untried ideas should be incorporated.
New designs generally have “bugs” or unforeseen which must be worked out before the superior characteristics of the new designs can be enjoyed. Thus there is a chance for a superior product, but only at higher risk. It should be emphasized that, if a design does not warrant radical new methods, such methods should not be applied merely for the sake of change.
During the beginning stages of design, creativity should be allowed to flourish without a great number of constraints. Even though many impractical ideas may arise, it is usually easy to eliminate then in the early stages of design before firm details are required by manufacturing. In this way, Innovative ideas are not inhibited. Quite often, more than one design is developed, up to the point where they can be compared against each other. It is entirely possible that the design which is ultimately accepted will use ideas existing in one of the rejected designs that did not show as much overall promise.
Psychologists frequently talk about trying to fit people to the machines they operate. It is essentially the responsibility of the engineer to strive to fit machines to people. This is not an easy task, since there is really no average person for which certain operating dimensions and procedures are optimum.
Another important point which should be recognized is that a design engineer must be able to communicate ideas to other people if they ate to be incorporated. Communicating the design to others is the final, vital step in the design process. Undoubtedly many great designs, inventions, and creative works have been lost to mankind simply because the originators were unable or unable or unwilling to explain their accomplishments to others. Presentation is a selling job. The engineer when presenting a new solution to administrative, management, or supervisory persons, is attempting to sell or to prove to them that this solution is a better one. Unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted.
Basically, there ate only three means of communication available to us. These are the written, the oral, and the graphical forms. Therefore the successful engineer will be technically competent and versatile in all three forms of communication. A technically competent person who lacks ability in any one of these forms is severely handicapped. If ability in all three forms is lacking, no one will ever know how competent that person is!
The competent engineer should not be afraid of the possibility of not succeeding in a presentation. In fact, occasional failure should be expected because failure or criticism seems to accompany every really creative idea. There is a great deal to learn from a failure, and the greatest gains ate obtained by those wiling to risk defeat. In the final analysis, the real failure would lie in decoding not to make the presentation at all. To communicate effectively, the following questions must be answered:
1、Does the design really serve a human need?
2、Will it be competitive with existing products of rival companies?
3、It is economical to profit?
4、Can it be readily maintained?
5、Will it sell and make a profit?
Only time will provide the true answers to the preceding questions, but the product should be designed, manufactured and marketed only with initial affirmative answers. The design engineer also must communicate the finalized design to manufacturing through the use of detail and assembly drawings.
Quite often, a problem will occur during the manufacturing cycle. It may be that a exchange is required in the dimensioning or tolerancing of a part so that it can be more readily produced. This falls in the category of engineering changes which must be approved by the design engineer so that the product function will not be adversely affected. In other cases, a deficiency in the design may appear during assembly or testing just prior to shipping.
Engineering design is a systematic process by which solutions to the needs of humankind are obtained. The process is applied to problems (needs) of varying complexity. For example, mechanical engineers will use the design process to find an effective, efficient method to convert reciprocating motion to circular motion for the drive train in an internal combustion engine; electrical engineers will use the process to design electrical generating systems using falling water as the power source; and materials engineers use the process to design ablative materials which enable astronauts to safely the earth’s atmosphere.
The vast majority of complex problems in today’s high technology society depend for solution not on a single engineering discipline, but on teams of engineers, scientists, environmentalists, economists, sociologists, and legal personnel. Solutions are not only dependent upon the appropriate applications of technology but also upon public sentiment, government regulations and political influence. As engineers we are empowered with the technical expertise to develop new and improved products and systems, but at the same time we must be increasingly aware of the impact of our actions on society and the environment in general and work conscientiously toward the best solution in view of all relevant factors.
Design is the culmination of the engineering educational process; it is the salient feature that distinguishes engineering from other professions.
A formal definition of engineering design is found in the curriculum guidelines of the Accreditation Board for Engineering and Technology (AENT). ABEN accredits curricula in engineering schools and derives its membership from the various engineering professional societies. Each accredited curriculum has a well-deigned design component which falls within the ABEN guideline. The ABEN statement on design reads as follows:
Engineering design is the process of devising a system, component, or process to meet desired needs. It is a decision making process (often iterative ), in which the basic sciences, mathematic, and engineering sciences are applied to convert resources optimally to meet a stated objective. Among the fundamental elements of the design process are the establishment of objectives and criteria, synthesis, analysis, construction, testing, and evaluation. The engineering design component of a curriculum must include most of the following features: development of student creativity, use of open-ended problems, development and use of modern design theory mad methodology, formulation of design problem statements and specifications, consideration of alternative solutions, feasibility considerations, production processes, concurrent engineering design, and detailed system descriptions. Further, it is essential to include a variety of realistic constraints such as economic factors, safety, reliability, aesthetics, ethics, and social impact.
If anything can be said about the last half of the twentieth century, it is that we have had an explosion of information. The amount of data that can be uncovered on most subjects is overwhelming. People in the upper levels of most organizations have assistants who condense most of the things that they must read, hear, or watch. When you begin a search for information, be prepared to scan many of your sources and document their location so that you can find them easily if the date subsequently appear to be important.
Some of the sources that are available include the following:
1、 Exiting solutions. Much can be learned from the current status of solutions to a specific need if actual products can be located, studied and, in some cases, purchased for detailed analysis. An improved solution or an innovative new solution new solution cannot be found unless the existing solutions are thoroughly understood.
2、 Your library. Many universities have courses that teach you how to use your library. Such courses are easy when you compare them with those in chemistry and calculus, but their importance should not be underestimated. There are many sources in the library that can lead you to the information that you are seeking. You may find what you need in an index such as the Engineering Index. There are many other indexes that provide specialized information. The nature of your problem will direct which ones may be helpful to you. Don’t hesitate to ask for assistance from the librarian. You should use to advantage the computer databases found in libraries and often available through CD-ROM technology.
3、Professional organizations. The American Society of Mechanical Engineers is a technical society that will be of interest to students majoring in mechanical engineering. Each major in your college is associated with not one but often several such societies. The National Society of Professional Engineers is an organization that most engineering students well eventually join, as well as at least one technical society such as the society of manufacturing engineers, the American Society of civil engineers (ASCE), or any one of dozens that serve the technical interests of the host of specialties with which professional practices seem most closely associated. May engineers are members of several associations and societies.
4、Trade journals. They are published by the hundreds, usually specializing in certain classes of products and services. Money and economics are part of engineering design and decision making. We live in a society that is based on economics and competition. It is no doubt true that many good ideas never get tried because they are deemed to be economically infeasible. Most of us have been aware of this condition in our daily lives. We started with our parents explaining why we could not have some item that we wanted because it cost too much. Likewise, we will not put some very desirable component into our designs because the value gained will not return enough profit in relation to its cost.
Industry is continually looking for new products of all types. Some are desired because the current product is not competing well in the marketplace. Others are tried simply because it appears that people will buy them. How do manufacturers know that a new product will be popular? They seldom know with certainty. Statistics is an important consideration in market analysis. Most of you will find that probability and statistics are an integral part of your chosen engineering curriculum. The techniques of this area of mathematics allow us to make inferences about how large groups of people react based on the reactions of a few.
中文翻譯
機(jī)械設(shè)計(jì)簡(jiǎn)介
機(jī)械設(shè)計(jì)領(lǐng)域是為了滿(mǎn)足人類(lèi)需要而制定出的新產(chǎn)品或者改進(jìn)舊產(chǎn)品時(shí)對(duì)科學(xué)與技術(shù)的應(yīng)用。 它是工程技術(shù)的一個(gè)巨大領(lǐng)域,這個(gè)不僅關(guān)注原先這種產(chǎn)品的尺寸，形狀以及構(gòu)造方式， 而且考慮涉及這種產(chǎn)品的制造，銷(xiāo)售和使用的其它各方面的因素。
進(jìn)行機(jī)械設(shè)計(jì)的各種各功能的人們被通常叫為設(shè)計(jì)者或者設(shè)計(jì)工程師。 機(jī)械設(shè)計(jì)基本上是一次創(chuàng)造活動(dòng)。 然而， 除富有創(chuàng)新精神之外， 一位設(shè)計(jì)工程師也必須在機(jī)械制圖，運(yùn)動(dòng)學(xué)，力學(xué)，材料工程，材料強(qiáng)度和制造工藝有一定的背景知識(shí)。
精確的說(shuō)，機(jī)械設(shè)計(jì)的目的就是為了滿(mǎn)足人們的需求。 發(fā)明，創(chuàng)造和科學(xué)知識(shí)它們自己可能不能讓人獲益； 但是只要他們合并在一起并設(shè)計(jì)產(chǎn)品，其益處就會(huì)被得到。因此，在一種特別的產(chǎn)品被設(shè)計(jì)之前，人的需求必須被鑒定，這一點(diǎn)應(yīng)該被認(rèn)識(shí)到。
機(jī)械設(shè)計(jì)應(yīng)被視為一個(gè)機(jī)會(huì)，利用創(chuàng)新人才的設(shè)想設(shè)計(jì)一個(gè)產(chǎn)品，分析系統(tǒng)，然后就如何制造產(chǎn)品作出正確的判斷。對(duì)工程基礎(chǔ)的理解而不是僅僅記住事實(shí)和方程式，這一點(diǎn)是很重要的。 沒(méi)有哪個(gè)事實(shí)或方程式能單獨(dú)提供要求生產(chǎn)一種好設(shè)計(jì)的全部的正確的決定。 另一方面，任何計(jì)算必須得最大限度小心和精密。 例如，一個(gè)小數(shù)點(diǎn)放錯(cuò)，就有可能得不到所要設(shè)計(jì)得到的結(jié)果。
好的設(shè)計(jì)應(yīng)該需要嘗試新的方法并且愿意承擔(dān)一定的風(fēng)險(xiǎn)，知道如果新想法不起作用，這種現(xiàn)有的方法可能被重新使用。由于為了成功所付出的時(shí)間以及努力是不能保證的，因此一個(gè)設(shè)計(jì)者必須要有耐心。創(chuàng)造一個(gè)完全新的設(shè)計(jì)一般要求很多舊的以及被建立起來(lái)的方法來(lái)推動(dòng)。這并不容易因?yàn)楹芏嗳藞?jiān)持舊的想法，技術(shù)和態(tài)度。設(shè)計(jì)工程師要不斷尋找方法，以改善現(xiàn)有的產(chǎn)品，并且決定哪些舊的、已被證明的概念須要采納，哪些新的、未曾嘗試的想法應(yīng)該被包刮進(jìn)來(lái)。
在那些新設(shè)計(jì)的優(yōu)勢(shì)特性可以被享有之前,新設(shè)計(jì)一般有"缺陷"或者一些未預(yù)見(jiàn)的缺點(diǎn)。因此，有機(jī)會(huì)，提供優(yōu)異的產(chǎn)品，但只有在較高的風(fēng)險(xiǎn)下。應(yīng)該強(qiáng)調(diào)指出，如果一個(gè)設(shè)計(jì)并不需要激進(jìn)的新方法，這種方法不應(yīng)適用而僅僅是為了改變。
在設(shè)計(jì)的開(kāi)始階段，創(chuàng)造性應(yīng)該被提倡而沒(méi)有許多限制條件。 即使很多不實(shí)用的想法可能出現(xiàn)，在穩(wěn)定的細(xì)節(jié)生產(chǎn)被要求之前，這些在設(shè)計(jì)早期通常是容易消除的。以這種方法，富創(chuàng)新精神的想法不被抑制。 經(jīng)常，不止一種設(shè)計(jì)被提出，甚至到他們可能對(duì)彼此被進(jìn)行比較的方面。 這是完全可能的：最終被接受的設(shè)計(jì)將可能使用被拒絕的設(shè)計(jì)之中的一個(gè)想法。
心理學(xué)家經(jīng)常談?wù)撆κ顾麄儾僮鞯哪切C(jī)器適合人。努力使機(jī)器適應(yīng)人基本上是工程師的責(zé)任。這不是一項(xiàng)容易的任務(wù),因?yàn)檎娴臎](méi)有人能夠把某一個(gè)生產(chǎn)尺寸加工到最優(yōu)化的程度。
另一個(gè)要點(diǎn)是：一位設(shè)計(jì)工程師必須能把想法傳達(dá)給其他人，當(dāng)他們的想法可以被采納時(shí)。 把設(shè)計(jì)思想傳達(dá)給其它人是最后環(huán)節(jié)，也是在設(shè)計(jì)過(guò)程里的至關(guān)重要的步驟。無(wú)疑很多重要的設(shè)計(jì)，發(fā)明和有創(chuàng)造性的作品被人們所不認(rèn)同，僅僅是因?yàn)槟切﹦?chuàng)始人不能或者不愿意對(duì)其它人解釋他們的成就。 贈(zèng)送是一個(gè)出售的工作。 當(dāng)提出一個(gè)新的解決方案，管理或者監(jiān)督的人的方法時(shí)，工程師， 正試圖出售或者向他們證明這個(gè)解決辦法是更好的。 除非這能被成功操作，否則關(guān)于獲得這個(gè)解決辦法所花費(fèi)的時(shí)間和努力基本上是浪費(fèi)的。
基本上，那里只有我們可用的3個(gè)通信手段。 它們是寫(xiě)，口頭，以及圖表的形式。 因此成功的工程師將精通這3 種交際方式的能力。缺乏其中任何一個(gè)交際能力的一個(gè)技術(shù)人員就相當(dāng)于嚴(yán)重殘疾。如果全部3個(gè)交際能力都缺乏的話(huà)，沒(méi)有人知道此人是多么有能力！
有能力的工程師不應(yīng)該害怕推薦自己不成功的可能性。實(shí)際上，偶然的失敗應(yīng)該被期望，因?yàn)槭』蛘吲u(píng)好像伴隨每個(gè)真的有創(chuàng)造性的想法。 有許多都是從失敗中獲悉，巨大收獲都是從那些冒險(xiǎn)獲得的。歸根到底，真正的失敗將在于根本不會(huì)做推薦自己。 為了有效地交流，下列問(wèn)題必須被回答：
(1)這設(shè)計(jì)真的能服務(wù)人需要嗎？
(2)它將與現(xiàn)有的競(jìng)爭(zhēng)公司的產(chǎn)品競(jìng)爭(zhēng)嗎？
(3)獲益是實(shí)惠的嗎？
(4)它能被比較容易的保持嗎？
(5)它將能被出售并且贏利嗎？
只有時(shí)間能提供上述問(wèn)題的正確的答案，但是產(chǎn)品應(yīng)該被設(shè)計(jì)，只用最初肯定的答案生產(chǎn)并且銷(xiāo)售。設(shè)計(jì)工程師也必須通過(guò)使用細(xì)節(jié)和裝配圖多溝通定稿設(shè)計(jì)到生產(chǎn)。
經(jīng)常，一個(gè)問(wèn)題將在生產(chǎn)的循環(huán)期間產(chǎn)生。這可能是在一個(gè)部分的定尺寸或者加工過(guò)程中所要求一次交換，以便它能夠被更容易生產(chǎn)。這在被設(shè)計(jì)工程師批準(zhǔn)的工程變化的種類(lèi)方面下降，以便產(chǎn)品功能將不被相反影響。 在其他情況里，在設(shè)計(jì)過(guò)程中的一種缺陷可能在裝運(yùn)之前的裝配或檢測(cè)測(cè)試期間出現(xiàn)。
工程設(shè)計(jì)是一個(gè)系統(tǒng)的過(guò)程，其中的解決方案是為了滿(mǎn)足人類(lèi)需要而得到的。進(jìn)程是不同的復(fù)雜性的問(wèn)題（需求）的應(yīng)用。例如，機(jī)械工程師，將利用設(shè)計(jì)過(guò)程中，以找到一個(gè)有效率的方式轉(zhuǎn)換成往復(fù)運(yùn)動(dòng)，在一個(gè)內(nèi)部?jī)?nèi)燃機(jī)以圓周運(yùn)動(dòng)來(lái)驅(qū)動(dòng)列車(chē);電氣工程師在使用過(guò)程中，以設(shè)計(jì)電動(dòng)發(fā)電機(jī)系統(tǒng)使用，水位下降為能源;材料工程師使用過(guò)程中，以設(shè)計(jì)燒蝕材料，使宇航員平安返回地球的大氣層。
在今天的高科技社會(huì),絕大多數(shù)的復(fù)雜問(wèn)題賴(lài)以解決的方案不僅僅取決于單一的工程學(xué)科，而且還取決于團(tuán)隊(duì)的工程師，科學(xué)家，環(huán)境學(xué)家，經(jīng)濟(jì)學(xué)家，社會(huì)學(xué)家，法律人員。解決方案不僅取決于適當(dāng)技術(shù)的應(yīng)用而且還取決于公眾情緒，政府規(guī)章和政治影響力。作為工程師，我們有權(quán)與技術(shù)專(zhuān)家發(fā)展和改進(jìn)新的產(chǎn)品和系統(tǒng)，但同時(shí)我們必須意識(shí)到我們行動(dòng)的影響：對(duì)社會(huì)和環(huán)境的總體工作，認(rèn)真對(duì)待最好的解決辦法，鑒于對(duì)所有的相關(guān)因素。
??? 設(shè)計(jì)是經(jīng)過(guò)工程教育的過(guò)程，這是區(qū)別其他工程專(zhuān)業(yè)的顯著的特點(diǎn)。
它的一個(gè)正式的定義是：工程設(shè)計(jì)是有工程與技術(shù)評(píng)審委員會(huì)（ AENT ）的指引下建立的 。 AENT委派的課程，在工程學(xué)校和源于其成員來(lái)自各工程專(zhuān)業(yè)社團(tuán)。各派駐課程已有一套完善的設(shè)計(jì)部分，其中屬于ABEN的指引。該AENT聲明，對(duì)設(shè)計(jì)內(nèi)容如下：
???工程設(shè)計(jì)是，制訂一個(gè)系統(tǒng)，組件的過(guò)程，以應(yīng)付預(yù)期的需求。同時(shí)它也是一個(gè)決策過(guò)程（通常迭代） ，其中基礎(chǔ)科學(xué)，數(shù)學(xué)，科學(xué)和工程科學(xué)的應(yīng)用轉(zhuǎn)換成資源，以最大限度地滿(mǎn)足目標(biāo)。其中基本要素的設(shè)計(jì)過(guò)程中，是設(shè)立目標(biāo)和標(biāo)準(zhǔn)，合成，分析，構(gòu)造，測(cè)試和評(píng)價(jià)。工程設(shè)計(jì)組成的一個(gè)課程必須具有以下大部分特點(diǎn)：發(fā)展學(xué)生的創(chuàng)造力，利用不限名額問(wèn)題，開(kāi)發(fā)和利用現(xiàn)代設(shè)計(jì)理論的方法，配方設(shè)計(jì)問(wèn)題，報(bào)表和規(guī)格，考慮其他的解決辦法，可行性的考慮，生產(chǎn)進(jìn)程，并行工程設(shè)計(jì)，以及詳細(xì)的系統(tǒng)說(shuō)明。此外，它必須包括各種現(xiàn)實(shí)的制約因素，如經(jīng)濟(jì)因素，安全性，可靠性，美學(xué)，倫理學(xué)和社會(huì)的影響。
關(guān)于最近二十世紀(jì)下半葉，其最大的特點(diǎn)，那就是：我們處在一個(gè)資訊爆炸時(shí)代。可發(fā)現(xiàn)的數(shù)據(jù)量大部分的科目是壓倒性的。在上級(jí)的大多數(shù)組織的人們已經(jīng)幫助凝聚在他們必須讀，聽(tīng)，或看的大部分的事情。當(dāng)你開(kāi)始尋找資料，準(zhǔn)備以瀏覽你的許多消息來(lái)源，并記錄其位置，如果有日期就能方便你能夠輕松的找到。
一些消息的來(lái)源也可以包括以下幾個(gè)方面：
1、飛離解決方案。在某些情況下，根據(jù)具體需要從目前的現(xiàn)狀解決辦法，如果實(shí)際的產(chǎn)品可以研究，購(gòu)買(mǎi)詳細(xì)的分析，我們可以從中學(xué)到很多東西。一種改進(jìn)的解決辦法或是一個(gè)嶄新的解決方案均不能被找到，除非現(xiàn)有的解決方案是徹底的了解。
2、你的圖書(shū)館。許多大學(xué)有課程，教你如何使用你的圖書(shū)館。此類(lèi)課程的目的是很容易當(dāng)你比較他們與那些在化學(xué)和微積分，但其重要性是不可低估的。在圖書(shū)館有許多來(lái)源，這些來(lái)源可以把你帶到你想要尋找的資料。你可以找到你所需要的一個(gè)指標(biāo)，如工程索引。還有很多其他的指標(biāo)，提供專(zhuān)門(mén)的信息。你的問(wèn)題的性質(zhì)，將直接哪些是可以幫助你。不要再猶豫向館員請(qǐng)求幫助。你應(yīng)該使用，以圖書(shū)館建立的電腦數(shù)據(jù)庫(kù)，而且往往可以通過(guò)光盤(pán)技術(shù)。
3、專(zhuān)業(yè)組織。美國(guó)機(jī)械工程師學(xué)會(huì)是一個(gè)技術(shù)性的社會(huì)，這將是學(xué)生感興趣的主修機(jī)械工程。在你的大學(xué)里，每項(xiàng)重大的項(xiàng)目往往都是幾個(gè)社團(tuán)一起協(xié)助的而不是一個(gè)。國(guó)家專(zhuān)業(yè)工程師協(xié)會(huì)，是一個(gè)大多數(shù)工程系學(xué)生都想加入的組織，以及技術(shù)協(xié)會(huì)如社會(huì)制造工程師，美國(guó)土木工程師協(xié)會(huì)（ASCE ） ，或任何一個(gè)幾十項(xiàng)服務(wù)技術(shù)東道國(guó)的利益的組織，專(zhuān)業(yè)與專(zhuān)業(yè)的做法似乎有最密切聯(lián)系在一起的。 5月工程師協(xié)會(huì)成員也是其它幾個(gè)社團(tuán)和協(xié)會(huì)的成員。
4、貿(mào)易雜志。公布這些數(shù)據(jù)是由數(shù)百個(gè)團(tuán)體，這些團(tuán)體通常是專(zhuān)門(mén)從事某些類(lèi)別的產(chǎn)品和服務(wù)。金錢(qián)和經(jīng)濟(jì)學(xué)是工程設(shè)計(jì)與決策的一部分。我們生活在一個(gè)基于經(jīng)濟(jì)及競(jìng)爭(zhēng)的社會(huì)中。毫無(wú)疑問(wèn)確實(shí)有很多好的想法從來(lái)沒(méi)有得到通過(guò)，是因?yàn)樗麄儽徽J(rèn)為在經(jīng)濟(jì)上不可行。我們大部分人已經(jīng)意識(shí)到我們?nèi)粘Ｉ畹倪@種狀況。我們開(kāi)始與我們的父母解釋為什么我們不能有我們所希望的一些項(xiàng)目，因?yàn)樗某杀咎吡恕Ｍ瑯?，我們將不?huì)把一些非?？扇〉某煞秩谌胛覀兊脑O(shè)計(jì)中，因?yàn)閮r(jià)值上漲將不會(huì)獲得足夠的利潤(rùn)，相對(duì)于其成本。
工業(yè)正不斷尋求所有種類(lèi)的新的產(chǎn)品。有些是可取的，因?yàn)樵谑袌?chǎng)上目前的產(chǎn)品不能與之相互競(jìng)爭(zhēng)。而其它的都試圖簡(jiǎn)單，因?yàn)樵谒磥?lái)，人們會(huì)購(gòu)買(mǎi)他們。制造商怎么知道一個(gè)新的產(chǎn)品將受歡迎呢？他們很少確定。在市場(chǎng)分析中統(tǒng)計(jì)是一項(xiàng)重要的考慮因素。你們中的大部分人會(huì)發(fā)覺(jué)：概率統(tǒng)計(jì)是一個(gè)不可分割的組成部分，在你所選擇的工程課程中。該技術(shù)在本領(lǐng)域的數(shù)學(xué)，使我們作出的推論：對(duì)如何大群體的人的反應(yīng)的基礎(chǔ)上的反應(yīng)數(shù)。
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