Computer modelling devices

A variety of studies can be found in the literature for the solution of the convection heat transfer problem in micro-channels. Some of the analytical methods are very powerful, computationally very fast, and provide highly accurate results. Usually, their application is shown only for those channels and thermal boundary conditions for which solutions already exist, such as circular tube and parallel plates for constant heat flux or constant temperature thermal boundary conditions. The majority of experimental investigations are carried out under other thermal boundary conditions (e.g., experiments in rectangular and trapezoidal channels were conducted with heating only the bottom and/or the top of the channel). These experiments should be compared to solutions obtained for a given channel geometry at the same thermal boundary conditions. Results obtained in devices that are built up from a number of parallel micro-channels should account for heat flux and temperature distribution not only due to heat conduction in the streamwise direction but also conduction across the experimental set-up, and new computational models should be elaborated to compare the measurements with theory. 

Notwithstanding the intellectual challenges posed by the subject, the main impetus behind the development of computational models for turbulent reacting flows has been the increasing awareness of the impact of such flows on the environment. For example, incomplete combustion of hydrocarbons in internal combustion engines is a major source of air pollution. Likewise, in the chemical process and pharmaceutical industries, inadequate control of product yields and selectivities can produce a host of undesirable byproducts. Even if such byproducts could all be successfully separated out and treated so that they are not released into the environment, the economic cost of doing so is often prohibitive. Hence, there is an ever-increasing incentive to improve industrial processes and devices in order for them to remain competitive in the marketplace. 

Figure 1.1 Overview of the basic philosophy used in the development of perceptual audio quality measurement techniques. A computer model of the subject is used to compare the output of the device under test (e.g. a speech codec or a music codec) with the ideal, using any audio signal. If the device under test must be transparent then the ideal is equal to the input.

This computer model depicts a molecular bearing that performs the same functions as a macroscopic scale bearing, the only difference being the number of atoms contained within the device. (Alfred Pasieka/Photo Researchers, Inc.)... 

At present, we are somewhere in-between these points the barrier to utilizing GPU hardware for general purpose computation has been reduced by the introduction of general purpose GPU programming models such as NVIDIA s Compute Unified Device Architecture (CUDA) [15] and AMD s Stream [20]. However, algorithmic paradigm shifts are often required in existing codes to maximize such performance offered by the massively parallel GPU hardware. 

Pardhanani, A.L. and Carey, G.F. (2000) Multidimensional Semiconductor Device and Micro-scale Thermal Modeling Using the PROPHET Simulator with Dial-an-Operator Framework. Comput. Model. Eng. Sci., 1, 141-150. 

The oxidative deterioration of most commercial polymers when exposed to sunlight has restricted their use in outdoor applications. A novel approach to the problem of predicting 20-year performance for such materials in solar photovoltaic devices has been developed in our laboratories. The process of photooxidation has been described by a qualitative model, in terms of elementary reactions with corresponding rates. A numerical integration procedure on the computer provides the predicted values of all species concentration terms over time, without any further assumptions. In principle, once the model has been verified with experimental data from accelerated and/or outdoor exposures of appropriate materials, we can have some confidence in the necessary numerical extrapolation of the solutions to very extended time periods. Moreover, manipulation of this computer model affords a novel and relatively simple means of testing common theories related to photooxidation and stabilization. The computations are derived from a chosen input block based on the literature where data are available and on experience gained from other studies of polymer photochemical reactions. Despite the problems associated with a somewhat arbitrary choice of rate constants for certain reactions, it is hoped that the study can unravel some of the complexity of the process, resolve some of the contentious issues and point the way for further experimentation. 

We should develop a better understanding of the basic fluid dynamics of gaseous flow through various meters through the development of computer models that can be verified by non-intmsive devices. The computer models could result in an entirely new generation of measurement devices. 

Biologists use a variety of tools and technologies to perform tests, collect and display data, and analyze relationships at the organismal and ecosystem level. Examples of commonly used tools include computer-linked probes, computerized tracking devices, computer models and databases, and spreadsheets. 

The risk of failure or the fear of malpractice often precludes the design and evaluation of controllers in live humans, so that devices and treatments are often tested on computer and animal models first. In the past, animals have been the preferred choice, but this approach is continually being reevaluated. Whereas most researchers readily agree that animal experimentation has been and will continue to be necessary for the advancement of medical science, most would welcome methods and procedures that might reduce or even eliminate the use of animals. Furthermore, animals are rarely perfect models of human diseases and conditions. Thus, there has been and wiU continue to be a demand for alternative models and procedures. Tissue cultures are beginning to fill some of this need, and it is hfcely that computer modeling and simulation may also fill this need. 

Desktop patients, if used to complement animal studies, can actually increase the reliability and applicability of certain animal tests, while also reducing the number of required experiments. In certain instances, computer modeling may be the only way to test a device prior to human use, since some human conditions are extremely difficult if not impossible to reproduce in animals. Indeed, as computers become more powerful and models become better, it may be that some day computers will be used in place of certain animal and human trials. Meanwhile, computer models can be used to (1) demonstrate feasibility, (2) increase confidence in controller designs by complementing animal studies, (3) help design better animal and clinical experiments, and (4) reduce the number of required animal and human experiments. 

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