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Simulation （仿真）
Simulation: in industry, science, and education, a research or teaching technique that reproduces actual events and processes under test conditions. Developing a simulation is often a highly complex mathematical process. Initially a set of rules, relationships, and operating procedures are specified, along with other variables. The interaction of these phenomena create new situations, even new rules, which further evolve as the simulation proceeds. Simulation implements range from paper-and-pencil and board-game reproductions of situations to complex computer-aided interactive systems.
Simulation techniques for experimentation permit researchers to perform exotic “dry lab” experiments or demonstrations without using rare materials or expensive equipment. In the automotive industry, proposed automobile designs undergo simulated wind-tunnel tests in computer simulations, thus saving hundreds of hours formerly devoted to prototype building and testing. Time compression is another cost-saving feature of simulation technology. Events that can take anywhere from hours to eons in real time can be simulated in a few minutes.
Medical researchers, for example, often must isolate organs and keep them alive by artificial means, grow cultures, inject chemicals, and wait for results. When the normal functions of a selected organ can be simulated accurately, however, researchers can observe in a few minutes the effects of a broad range of events on that functioning. Likewise, astronomers using computer simulations of galactic movements can demonstrate events that take millions of years to complete—such as the collision of two galaxies—to test the validity of theoretical descriptions.
As a technique for instruction, simulation allows students to deal in a realistic way with matters of vital concern but without dire consequences should they make wrong choices. The technique has proven especially useful in medical training, as, for example, in the University of Alberta Medical School, where the computer simulates patients in critical condition who will die without proper care. Aspiring doctors are asked to make swift diagnoses and prescribe treatments in an effort to keep the patient alive. Aircraft-pilot trainees also are exposed to realistic emergency situations by means of such sophisticated simulation devices as the Link trainer (see flight simulator).
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Simulations enable students to understand complex interactions of physical or social environment factors. Dartmouth College students, for example, play a simulation game in which they strive to grow a good rice crop under the constant threat of pests, fire, and flooding. The Graduate School of Management at Northwestern University has programmed its computer to simulate a micro-model of the American economy. Using portable terminals and television monitors, students propose solutions to economic problems and compare the predictions they yield with data taken from the model.
From Encyclopedia Britannica （引自大英百科全书）
5 Design Methodology （设计方法学）
Is design an art form only to be practiced by those gifted with its talents, or is it a regimented discipline that can be learned? Virtually everything that humans do involves altering the environment around us, which is essentially what design is all about; thus every individual possesses the ability to design to some extent.
Systematic methods of analysis and synthesis can be formulated to aid in development of ideas; however, these methods have often been blamed for stifling creativity. A good design engineer often uses systematic methods of analysis and synthesis in order to help evaluate wild and crazy conceptual ideas generated during the initial creative phase of problem solving.
A design engineer must also become good at identifying problems. Once a problem is identified, it will usually yield to an unending barrage of creative thought and analysis. High-priced consultants do not necessarily solve detailed problems; they identify the problems for others to solve. Identifying a problem requires careful detective work. In addition to solving and identifying problems, the design engineer must also learn to identify what the customer really needs, which is not necessarily what the customer thinks that he or she needs. This requires interaction with marketing research groups, customers, and manufacturing personnel on a continuing personal basis.
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Five Basic Steps of Design:
(1) Task definition (2) Conceptual design (3) Layout design (4) Detail design
（设计的五个基本步骤） （任务定义） （概念设计） （布局设计） （详细设计）
(5) Design follow-up （设计后续工作）
Task definition often starts with the customer or sales representative requesting the design department to provide a study regarding the feasibility, cost, and potential availability of a design to perform a specific function. In response to this request, the company’s best design engineers get together to sketch out concepts.
It is in the conceptual design phase that the functional relationships of components and the physical structure are usually defined.
Once a few select conceptual designs are chosen, they are expanded in detail through layout design where preliminary sizing of components and calculations are made in order to produce rough assembly drawings of the conceptual designs. This enables more accurate feasibility and cost estimates to be developed. After modifying the required specifications and conceptual designs, the project’s feasibility can be determined, usually resulting in one design being chosen for detailing.
The detail design phase is everything that follows in order to bring the design to life. Design follow-up involves activities such as the development of a maintenance plan and documentation, which often cause many design engineers to run and hide. However, if the design is not maintained, or if nobody can figure out how to use it, the design will not be used and design effort will have been wasted.
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Examples of 3D Model （三维模型实例）
6-1 Handle （手柄）
6-2 Frame
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（机架）