Практикум составлен в соответствии с требованиями к коммуникационной подготовки выпускников инновационной образовательной программы
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--------------------------------------------------------------------------------------- Unit Seven Text. COMPUTER SIMULATION IN PRACTICAL CONTEXT Key words: validity of the model, verification of computer simulation, computer games, computer graphics, animation, scientific visualization Computer simulations are used in a wide variety of practical contexts, such as: Analysis of air pollutant dispersion using atmospheric dispersion modeling; Design of complex systems such as aircraft and also logistics systems; Design of noise barriers to effect road noise mitigation, flight simulators; Behavior of structures (buildings, industrial parts) under stress and other conditions; Design of industrial processes (chemical processing plants); Reservoir simulation for the petroleum engineering to model the subsurface reservoir; Strategic management and Organizational Studies; Process Engineering simulation tools; Robot simulators for the design of robots and robot control algorithms. The reliability and the trust people put in computer simulations depends on the validity of the simulation model, therefore verification and validation are of crucial importance in the development of computer simulations. Another important aspect of computer simulations is that of reproducibility of the results, meaning that a simulation model should not provide a different answer for each execution. Although this might seem obvious, this is a special point of attention in stochastic simulations, where random numbers should actually be semi-random numbers. An exception to reproducibility is human in the loop simulations such as flight simulations and computer games. Here a human is part of the simulation and thus influences the outcome in a way that is hard if not impossible to reproduce exactly. Computer graphics can be used to display the results of a computer simulation. Animations can be used to experience a simulation in real-time e.g. in real-time animations can be useful in visualizing the build up of queues training simulations. In some cases animations may also be useful in faster than real-time or even slower than real-time modes. For example, faster than in the simulation of humans evacuating a building. Furthermore, simulation results are often aggregated into static images using various ways of scientific visualization. In debugging, simulating a program execution under test (rather than executing natively) can detect far more errors than the hardware itself can detect and, at the same time, log useful debugging information such as instruction trace, memory alterations and instruction counts. This technique can also detect buffer overflow and similar "hard to detect" errors s well as produce performance information and tuning data.
Activities I. Choose the right answer 1. Computer simulations reliability of depends on … of simulation model a) the type b) simplicity c) the validity. 2. We should take into account the following aspect of computer simulation: a) high level of productivity b) reproducibility of the results c) lack of errors in producing the results 3. Computer graphics is used to: a) output data b) display the results c) provide a numerical value 4. In training simulations we can use: a) graphs b) a matrix format c) animations 5. Simulation results are aggregated into static images using various ways: a) of scientific visualization b) of statistic quantity from a sample of data c) of moving pictures II. Match the terms from the left column with the definitions in the right column
III. Questions for discussion: 1. Give the examples of computer simulation usages in practical contexts. 2. What are the main aspects of computer simulation? 3. What are the cases when computer animation is effectively used? 4. How can the results of computer simulation be reproduced? 5. What technique can detect buffer overflow and errors as well as produce performance information and tuning data? IV. Say what is true and what is false. Correct the false sentences 1.The reliability in computer simulations depends on the stage of the development of computer simulations. 2. A simulation model should provide a different answer for each execution. 3. In stochastic simulations random numbers should actually be semi-random numbers. 4. An exception to reproducibility is human in the loop transmissions such as flight simulations and computer games. 5. Animations may always be useful in faster than real-time or even slower than real-time modes. V. Find the words which can render the main text content. Try to make denotation graph. VI. Write a summary of the text about computer simulation in practical contexts (8-10 sentences) using the key words VII. Read and translate the text. Find and write out the key words Techniques for Sensitivity Estimation Simulation continues to be the primary method by which engineers and managers obtain information about complex stochastic systems, such as telecommunication networks, health service, corporate planning, financial modeling, production assembly lines, and flexible manufacturing systems. These systems are driven by the occurrence of discrete events; and complex interactions of these discrete events occur over time. For most discrete event systems (DES) no analytical methods are available, so DES must be studied via simulation. DES are studied to understand their performance, and to determine the best ways to improve their performance. In particular, one is often interested in how system performance depends on system parameters θ which could be a vector. Stochastic models typically depend upon various uncertain parameters that must be estimated from existing data sets. Statistical question of how input parameters uncertainty propagates through the model into output parameter uncertainty is the so called “what –if” analysis. A good answer to the question often requires sensitivity estimates. Perturbation analysis (PA) computes (roughly) what simulations would have produced, had θ been changed by “small” amount without actually making this change. The intuitive idea behind PA is that a sample path constructed using θ is frequently structurally very similar to the sample path using the perturbed θ. There is a large amount of information that is the same for both of them. It is wasteful to throw this information away and start the simulation from scratch with the perturbed θ. Harmonic analysis is another strategy for estimating the gradient simulation based on the frequency domain method, which differs from the time domain experiments in that the input parameters are deterministically varied in sinusoidal patterns during the simulation run, as opposed to being kept fixed as in the time domain runs. Comprehensive text-related glossary
IX. Pair or group work Make up a number of questions on the text. Pass these questions to your neighbour or a neighbouring group to evaluate and comment on. X. Read the text once more and find the words which can render the main text content. Try to make a denotation graph. ------------------------------------------------------------------------------------------ Unit Eight Text. SOCIAL AND WEB-BASED SIMULATIONS Key words: to model social and economic processes, Web-based simulation, software, social simulation, simulation methods Social scientists have always constructed models of social phenomena. Simulation is an important method for modeling social and economic processes. In particular, it provides a “middle way” between the richness of discursive theorizing and rigorous but restrictive mathematical models. There are different types of computer simulation and their application to social scientific problems. Faster hardware and improved software have made building complex simulation easier. Computer simulation methods can be effective for the development of theories as well as for prediction. For example, macro-economic models have been used to simulate future changes in the economy; and simulations have been used in psychology to study cognitive mechanisms. The field of social simulation seems to be following an interesting line of inquiry. As a general approach in the field a “world” is specified with much computational detail. Then the world is simulated (using computers) to reveal some of the “non-trivial” implications (or emergent properties) of the world. When these “non-trivial” implications are made known (fed back) in world, apparently it constitutes some added value. Artificial Life is an interdisciplinary study enterprise aimed at understanding life-as-it-is and life-as-it-could-be, and at synthesizing life-like phenomena in chemical, electronic, software, and other artificial media. Artificial Life redefines the concepts of artificial and natural, blurring the borders between traditional disciplines and proving new media. Simulation allows the social scientist to experiment with ‘artificial societies’ and explore the implications of theories in ways not otherwise possible. Web-based simulation is quickly emerging as an area of significant interest for both simulation researchers and simulation practitioners. This interest in web-based simulation is a natural outgrowth of the proliferation of the World-Wide Web and its attendant technologies, the surging popularity of, the reliance on, computer simulation as a problem solving and decision support tool. Currently, the researchers in the field of web-based simulation are interested in dealing with topics such as methodologies for web-based model development, collaborative model development over the Internet, Java-based modelling and simulation, distributed modelling and simulation using web technologies and new applications. Comprehensive text-related glossary
Activities I. Read and translate the text and analyze grammatical and lexical problems of the translation. Determine the tense-forms of the verbs. II. Find the equivalents to the words given in box A from box B
III. Questions for discussion: 1. Are there many types of computer simulation in social sphere? 2. What can you say about computer simulation methods to solve social problems? 3. How do you understand the term Artificial Life? 4. What does social simulation allow? 5. How can the interest in Web-based simulation be explained? IV. Group or pair work a) Read the text once more and try to point out the sentences which contain the main idea of the text. b) Compare your sentences with the sentences of your neighbour. Justify your choice. V. Read, translate the text and suggest its title Discrete-event simulation models typically have stochastic components that mimic the probabilistic nature of the system under consideration. Successful input modeling requires a close match between the input model and the true underlying probabilistic mechanism associated with the system. The input data analysis is to model an element (e.g., arrival process, service times) in a discrete-event simulation given a data set collected on the element of interest. This stage performs intensive error checking on the input data including external, policy, random and deterministic variables. Simulation experiment is learning its behavior. Careful planning or designing of simulation experiments is generally a great help, saving time and effort by providing efficient ways to estimate the effects of changes in the model’s inputs on its outputs. Statistical experimental experimental-design methods are mostly used in the context of simulation experiments. Analyzing complex DES often requires computer simulation. In these systems, the objective function may not be expressed as an explicit function of the input parameters; rather, it involves some performance measures of the system whose values can be found only by running the simulation model or by observing the actual system. On the other hand, due to the increasingly large size and inherent complexity of most man-made systems, purely analytical means are often insufficient for optimization. In these cases, one must resort to simulation, with its chief advantage being its applicability, and its primary disadvantage being its cost in terms of time and money. VI. Define the function of the underlined words (whether they are a verb, a participle or a gerund). VII. Make negative forms of the following adjectives Successful, true, external, efficient, actual, sufficient, discrete, careful VIII. Pair or group work a) Make up 6 questions on the text and ask them in the group. b) Try to identify the key ideas in two paragraphs of the text. Give some reasons for your choices. IX. Make up a denotation graph, using the text information and the key ideas of paragraphs from exercise VIII. ------------------------------------------------------------------------------------------ |