The variability of influent and effluent concentrations of trace contaminants at a full-scale municipal sewage treatment plant (STP) was measured by intensive sampling at two hour intervals for eight consecutive days....
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The variability of influent and effluent concentrations of trace contaminants at a full-scale municipal sewage treatment plant (STP) was measured by intensive sampling at two hour intervals for eight consecutive days. From these data, the technique of time series analysis was used to generate predictive models describing the process response. The data indicated that municipal STPs are capable of efficient trace contaminant removal and significantly attenuate the variability of these contaminants in the raw influent. Significant correlations were identified between influent characteristics and effluent concentrations for selected contaminants. For three metals and three trace contaminants, adequate time series models were developed. Such models are valuable tools for the development of strategies to control trace contaminants in discharges from municipal STPs.
The trend towards high density chip packaging of printed circuit boards, and the use of application-specific semiconductors in control applications has resulted in ever increasing cooling requirements for electronic s...
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The trend towards high density chip packaging of printed circuit boards, and the use of application-specific semiconductors in control applications has resulted in ever increasing cooling requirements for electronic systems. One response to this cooling problem is to mount the semiconductor chip directly to a high conductivity substrate to assist in the cooling capabilities. The design of direct mount chip attach systems requires proper balancing of two design issues to ensure a satisfactory system: (i) adequate cooling of the electronic chip assemblies, and (ii) thermal expansion match between the chip assemblies and the substrate to ensure structural integrity during operation. Techniques using the ADINA-T thermal analysis program which have been found to provide suitable thermal modeling of direct chip attach systems are discussed. Correlation between model and experimental data is provided, and guidance on which direct mount systems can be adequately modeled is described. Several studies of direct chip mount systems are detailed, and examples of the evaluations which can be performed using ADINA-T are discussed. Finally, the technology required to extend the range of electronic systems which can be effectively modeled is discussed.
This paper presents a system using knowledge-based techniques for producing idealized models from engineering data models with functional, geometric and attribute descriptions. The idealization techniques of geometric...
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This paper presents a system using knowledge-based techniques for producing idealized models from engineering data models with functional, geometric and attribute descriptions. The idealization techniques of geometric simplification and dimensional reduction as appropriate for structural analysis are discussed, and an implementation which controls the idealization process is presented. The role of the idealization expert system in the context of a design modeling system for engineering idealizations is also described.
The development of analytically simple, mathematically tractable video source models for the analysis of packet networks is described. As the bit-rate is not a constant, it is necessary to develop statistical models t...
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The development of analytically simple, mathematically tractable video source models for the analysis of packet networks is described. As the bit-rate is not a constant, it is necessary to develop statistical models to measure the characteristics of the coded bit-rate sequence. Since model development and validation rely on the availability of appropriate experimental data, a complete system was set up for data collection. The bit rate profiles and the basic statistics of 30 independent video sources with various activity levels were collected. On a subframe basis, the autocovariance function of each of the 30 sequences shows a pseudoperiodic property. The actual shape of each function, however, depends on the scenes in that particular video segment. A finite-state machine representation was proposed to describe the probabilistic behavior of the aggregate packet-rate process when video sources are statistically multiplexed. With appropriate parameters, the model matches the empirical data very well and can be used for the development of protocols and control schemes for ATM (asynchronous transfer mode) networks.
A general mechanism for decentralized control based on an object-oriented view of CAD (computer-aided design) tools is described. At the heart of this view of an open control mechanism for a CAD design framework is th...
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A general mechanism for decentralized control based on an object-oriented view of CAD (computer-aided design) tools is described. At the heart of this view of an open control mechanism for a CAD design framework is the CAD Tool Knowledge Object (CTKO). This approach simplifies CAD tool control within a design framework, making the framework more general, easier to use, and more capable of supporting a large population of CAD tools. This approach has been implemented in the Cadweld design framework, which includes an interactive user interface, interprocessor communication, intelligent CAD tool argument modeling, an object editor, and a backtracking system. At present, over 25 CAD tools have been incorporated into Cadweld and eventually 100 tools will be added to the framework. The tools currently in use range from PLA (programmable logic array) synthesis to layout editing, IC process fabrication, circuit simulation, and dataanalysis. By organizing the CAD tools to work with a more powerful design representation and allowing them to be automatically executed when necessary, the designer is freed from the more tedious aspects of design.
The authors outline a method of modeling a data communications network. This network serves military command, control, and communications applications. The model is based on the process-oriented framework of Simulatio...
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The authors outline a method of modeling a data communications network. This network serves military command, control, and communications applications. The model is based on the process-oriented framework of Simulation Language for Alternative modeling (SLAM ii). The model is highly modularized to provide the flexibility needed to add new requirements. The model was used to perform network performance analysis of the underlying DOSSNet (Defense Satellite Communications System Operational Support System Network). It is noted that the results of simulation may lead to useful practical conclusions pertaining to network design and optimal allocation of resources.< >
The key concepts and requirements for a process mechanism and the state change architecture (SCA) protocols are presented. The SCA is thought to solve many of the processmodeling problems associated with conventional...
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The key concepts and requirements for a process mechanism and the state change architecture (SCA) protocols are presented. The SCA is thought to solve many of the processmodeling problems associated with conventional languages and methods. It integrates object-oriented programming, a common repository for the logical view of data, and logic programming.< >
The use of linear-quadratic stochastic control designs for a ground-based tracking system is investigated. The design approach is motivated by the facts that: (i) the power spectral density of the atmospheric turbulen...
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The use of linear-quadratic stochastic control designs for a ground-based tracking system is investigated. The design approach is motivated by the facts that: (i) the power spectral density of the atmospheric turbulence-induced tilt is known, and can be accurately modeled; and (ii) the angular anisoplanatism effect can be expressed in terms of its temporal correlation. The former generates a stochastic dynamic model that best describes the atmospheric turbulence-induced tilt, and the latter introduces a future state or a delay state depending upon the problem formulation. It is demonstrated that how a design philosophy, taking into account the above available information in its control design, can lead to a closed-loop system with a better tracking performance. For a simple case study, the analysis shows that with the proposed control design, the system could track a much weaker target (has at least 2.5 times less brightness) as compared to the system using the classical control design.
This tutorial will present an approach to conducting a simulation project that will aid in avoiding many common problems and pitfalls. The presentation will provide recommendations on how to scope the project, develop...
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This tutorial will present an approach to conducting a simulation project that will aid in avoiding many common problems and pitfalls. The presentation will provide recommendations on how to scope the project, develop a functional specification, formulate and construct the model, verify and validate, collect data, document the work and perform the required analysis. The intent is to provide the novice simulation modeler with proven techniques for conducting a successful simulation project. A variety of case studies will be presented during the tutorial to illustrate both the right and wrong ways to conduct a project.
A state-estimation-based external power network modeling approach is proposed. The proposed approach is designed to improve the numerical stability and provide an external network model for online security analysis. A...
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A state-estimation-based external power network modeling approach is proposed. The proposed approach is designed to improve the numerical stability and provide an external network model for online security analysis. An initial load flow study that provides a preliminary solution for the external network is followed by a state estimation using pseudo-measurements and proper weighting factors. Methods for handling multiple observable islands in the external network modelingprocess are described, and simulation tests are carried out on a practical system with realistic complexity. The proposed method provides a way of dispersing external data errors to the remote portions of the external network. Information for error detection and identification is available from the proposed method. It is believed that continual update of the external network model using real-time data available from neighboring utilities in conjunction with the identification and removal of erroneous data assumptions could lead to a more accurate and realistic external network for use during online contingency analysis.< >
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