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American Control Conference (ACC)

作者： M.R. Napolitano G. Molinaro M. Innocenti B. Seanor D. Martinelli Department of Mechanical and Aerospace Engineering West Virginia University Morgantown WV USA Department of Electrical Systems and Automation University of Pisa Pisa Italy Department of Civil and Environmental Engineering West Virginia University Morgantown WV USA

This paper shows the results of a research effort focused on demonstrating the capabilities of hardware based online learning parallel neural networks for a fault-tolerant flight control system. Particularly, for a given aircraft mathematical model, two different fault-tolerant schemes have been implemented in different neural networks embedded on a mother-board with 4 TMS320C40 DSPs. The first scheme provides sensor failure detection, identification, and accommodation (SFDIA) for different types of sensor failures within a flight control system assumed to be without physical redundancy in the sensory capabilities. The second scheme provides actuator failure detection, identification and accommodation (AFDIA) for different actuator failures. Emphasis has been placed to ensure real-time capabilities as well as an efficient integration between the AFDIA and the SFDIA schemes without degradation of performance in terms of false alarm rates and incorrect failure identification. The results of the simulation following different types of failures are reported.

关键词： Packaging Fault tolerance Aerospace control Neural networks Sensor systems Actuators Neural network hardware Fault tolerant systems Aircraft Mathematical model

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Behavior of CFT column-WF beam moment connections under seismic loading

Behavior of CFT column-WF beam moment connections under seis...

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Hybrid and Composite Structures

作者： Ricles, James M. Lu, Le W. Sooi, Took Kwong Lehigh University United States Department of Civil and Environmental Engineering Lehigh University United States Center for Advanced Technology for Large Structural Systems Lehigh University United States

ISBN: (纸本)9780870316739

This paper describes research associated with the seismic behavior of moment connections for concrete filled tube (CFf) column-to-wide flange (WF) steel beam framing systems. The objective of this multiphase research program is to assess the force transfer mechanism in these connections, examining the effect various structural details have on this mechanism, as well as on the connection's strength, stiffness, and ductility. The first phase of the program was devoted to assessing the shear capacity of the panel zone in a CFf column-to-beam connection under simulated seismic lateral load conditions. The results from tests show that a CFf panel zone possesses exceptional ductility, including connections without interior diaphragms. In addition, a capacity equation based on the superposition of the shear strength contribution of the steel tube and concrete core within the panel zone provides a prediction that agrees reasonably well with specimen strength. The second phase of the research program involves full-scale structural connection subassemblage tests. Results from tests show that specimens in which the beams are designed to dissipate energy can have exceptional cyclic ductility. However, connections· must be properly detailed to avoid strain concentrations which could lead to fracture. Measured deformations in the column show that a CFf column's initial stiffness is well estimated by transformed section theory. However, interstory drift deformations beyond 0.5% of the story height tend to reduce the stiffness after concrete cracking and debonding of the concrete from the steel tube. © 1998 American Concrete Institute. All rights reserved.

关键词： Ductility

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Coherent vortex structures in deforming granular materials

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Mechanics of Cohesive-frictional Materials 1998年第3期2卷

作者： John R. Williams Nabha Rege Intelligent Engineering Systems Laboratory (IESL) Department of Civil and Environmental Engineering Massachusetts Institute of Technology Cambridge MA 02139 U.S.A.

Discrete element models are used to investigate the formation of coherent structures within a deforming granular material. The numerical models predict the formation of coherent vortex-like structures, even when the boundary deformations introduce zero vorticity. We name these structures circulation cells because the particles instantaneously translate and rotate as a rigid body about a common centre. They occur for all the particle shapes and material properties tested. The size of these coherent structures range from approximately 20 to 600 particles, with the largest structures being limited by the test boundaries. Circulation cells are seen to play an important role in granular deformations including the formation of shear bands. © 1997 John Wiley & Sons, Ltd.

关键词： granular materials vortices discrete element method coherent structures proper orthogonal decomposition

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The development of circulation cell structures in granular materials undergoing compression

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POWDER TECHNOLOGY 1997年第3期90卷 187-194页

作者： Williams, JR Rege, N Intelligent Engineering Systems Laboratory Department of Civil and Environmental Engineering Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 USA

This paper predicts the formation of microstructures within a granular material undergoing biaxial compression. Using the discrete element method we have tested ensembles of particles of varying geometric shape and size. The tests predict that the motion of the particles deviates significantly from that predicted by continuum theory. The particles form localized coherent structures (here called circulation cells) in which groups of particles instantaneously behave as a rigid body. These circulation cells migrate and coalesce to form larger structures. Eventually a global shear band forms at the boundary of two or more of the circulation cells.

关键词： circulation cell structures biaxial compression granular material particle shape particle motion

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Augmenting design patterns with design rationale

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AI EDAM-ARTIFICIAL INTELLIGENCE FOR engineering DESIGN ANALYSIS AND MANUFACTURING 1997年第2期11卷 93-108页

作者： PenaMora, F Vadhavkar, S Intelligent Engineering Systems Laboratory Department of Civil Environmental Engineering Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 U.S.A.

Present-day software applications are increasingly required to be ''reuse-conscious'' in terms of the operating platforms, topology, and evolutionary requirements. Traditionally, there has been much difficulty in communicating specialized knowledge like design intents, design recommendations, and design justifications in the discipline of software engineering. This paper presents a methodology based on the combination of design rationale and design patterns to design reusable software systems. Design rationale is the representation of the reasoning behind the design of an artifact. Design patterns are descriptions of communicating objects and classes that are customized to solve a general design problem in a particular context. The paper details the use of an explicit software development process to capture and disseminate the specialized knowledge (i.e., intents, recommendations, and justifications) that augments the description of the cases in a library (i.e., design patterns) during the development of software applications by heterogeneous groups. The importance of preserving and using this specialized knowledge has become apparent with the growing trend of combining the software development process with the product (i.e., software code). The importance of codifying corporate memory in this regard is also important considering the changing nature of the workplace, where more people are on contract. The information on how and why a software code was developed becomes essential for efficient and smooth continuity of the present software project as well as for reusing the code in future projects. It has become essential to capture the design rationale to develop and design software systems efficiently and reliably. The software prototype developed using the combined methodology will be used as a part of an integrated design environment for reusable software design. This environment supports collaborative development of software applications by a group of software sp

关键词： design rationale design patterns component-based software product/process modeling software reusability

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Metal and acid recovery options for the plating industry

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RESOURCES CONSERVATION AND RECYCLING 1997年第1期19卷 55-71页

作者： Morgan, SM Lee, CM Department of Civil Engineering Southern Illinois University at Edwardsville Campus Box 1800 Edwardsville IL 62026-1800 USA Department of Environmental Systems Engineering Clemson University Clemson SC 29634-0919 USA

The metal plating and finishing industry loses large amounts of raw materials, and while pollution prevention (P2) techniques and technologies are being used, there appears to be a disparity among platers in the extent of implementation. Surveys and interviews of South Carolina metal platers and finishers were conducted to explore the reasons for the lack of implementation of P2, to assess the extent of metal and acid recovery practiced, and to determine interest in various options for increasing recovery. Both standard recovery options (in-house recovery and centralized recovery facilities for sludge, spent solutions, and equipment rental) and innovative recovery options (rotating or shared recovery equipment and plating-industry specific and integrated industrial parks) were examined. All recovery options were compared with conventional treatment and each other based on technical, economic, and institutional factors. Although all the recovery options examined are conceptually feasible and have similar benefits, they are not all economically and institutionally feasible at this time for South Carolina platers. Based on the results of this research. it is recommended that platers, regulators, trade associations, and other parties in South Carolina focus on in-house recovery, including encouraging departments within captive plating shops to share recovery equipment. Platers in other regions as well as other industries win also find this research applicable. The two main variables that could change the results are geographic location, which affects transportation costs, and the political climate, which affects the desire to attract industry and the flexibility of the regulatory agencies. Copyright (C) 1997 Elsevier Science B.V.

关键词： pollution prevention metal and acid recovery recycling industrial waste

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Innovative recovery options for metal finishers

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Metal Finishing 1997年第4期95卷 20-20页

作者： Morgan, S.M. Department of Civil Engineering Southern Illinois University at Edwardsville Edwardsville Ill. USA Department of Environmental Systems Engineering Clemson University Clemson S.C. USA Department of Environmental Engineering Manhattan College Riverdale N.Y. USA

Although the current use of metal and acid recovery among South Carolina metal finishers is typical of that reported for the United States as a whole, overall, the results of this research indicate that metal finishers are willing to consider innovative technological and nontechnological methods to move toward proactive (rather than reactive) management of their environmental issues. They are interested in nontechnological methods, such as encouraging partnerships between chemical suppliers and metal finishers, as well as innovative technological methods, such as sharing recovery equipment, using a rotating recovery equipment company, and locating in enhanced-recovery industrial parks. The apparent disparity between perceptions of who can best encourage metal and acid recovery - in-house personnel, government, or suppliers - indicates that metal finishers are not yet sure where to commit resources;however, any of the innovative recovery methods presented in this article may be useful to decrease the risks and the costs associated with metal and acid recovery. This would increase the successful use of metal and acid recovery among metal finishers and would possibly increase the use of other proactive environmental management methods. © Copyright Elsevier Science Inc.

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Horizontal and vertical well comparison for in situ air sparging

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GROUND WATER MONITORING AND REMEDIATION 1997年第1期17卷 91-96页

作者： Plummer, CR Nelson, JD Zumwalt, GS Charles R. Plummer holds a B.S. in civil engineering and an M.S. in environmental engineering and water resources from Louisiana Tech University. Plummer is employed by Perry Pyron & McCown Consultants Inc. in Monroe Louisiana (2.508 Ticheli Rd. Monroe LA 71202) where he is responsible for remediation systems design and analysis and environmental application research. Before entering Louisiana Tech in 1989 Plummer served eight years as a drilling supervisor for an oil and gas exploration company. After receiving his B.S. degree in 1993 he worked as a graduate assistant for the Trenchless Technology Center under the guidance of Dr. Tom Iseley and Dr. James Nelson. James D. Nelson is associate dean for academic affairs College of Engineering and professor of civil engineering at Louisiana Tech University (Dept. of Civil Engineering LTV Ruston LA 71270). He received his Ph.D. from Colorado State University and his research interests are in ground water model-ing and remediation. Gary S. Zumwalt is associate professor of geosciences at Louisiana Tech University (Dept. of Geosciences LTU Ruston LA 71270). He received his Ph.D. from the University of California-Davis and his research interests are environmental geology and ground water remediation.

A laboratory study was conducted to determine the effectiveness of vertical and horizontal well configurations for ground water remediation using in situ air sparging. A lexan tank was designed and constructed to allow both the visualization of air flow and quantitative measurement of the distribution of air flow. Two media, sand and glass beads, were tested with both vertical and horizontal air sources. In each case, most of the air traveled through preferential channels as continuous flow rather than as discrete bubbles as reported in other studies. Even though glass beads were selected to have the same grain-size distribution as the sand, air flow was quite different through the two media. Results show that glass beads are not a suitable material for modeling air flow through natural sediments. In this study, the horizontal well proved to be more effective than the vertical well by impacting more of the media with a uniform distribution of air through-out the media. The vertical well resulted in a nonuniform distribution of air flow with most of the air concentrated directly above the well.

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Modelling drainage performance in an Indian catchment

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Water and Environment Journal 1997年第1期11卷 31-38页

作者： Heywood, G.M. Kolsky, P.J. Butler, D. Engineering Analyst Tynemarch Systems Engineering Ltd. Dorking United Kingdom Tropical Public Health Engineering London School of Hygiene and Tropical Medicine London United Kingdom Environmental Engineering Department of Civil Engineering Imperial College of Science Technology and Medicine London United Kingdom

Surface-water flooding occurs frequently in low-income urban settlements of developing countries, with impacts on public health and the local economy. In many locations, drainage systems are neither appropriate nor sustainable. A computer model of a small surface-water drainage catchment has been developed within a slum improvement programme in Indore, India. The model was calibrated and verified against flow-survey data, and was used to study the effects on performance of maintenance (as reflected in solids build-up in pipes) and site grading. The results confirm the critical importance of maintenance in drainage performance and the need for construction engineers to consider drainage carefully before changing site-grading plans. The results also suggest some general trends in drainage performance during floods. © 1997 Blackwell Publishing Ltd.

关键词： Flooding Health Low-income communities Performance evaluation Sediment Solids Surface-water drainage

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Modelling and Control Design for Open Top Chambers used in Plant Physiology Climate Change Experiments

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IFAC Proceedings Volumes 1997年第2期30卷 325-330页

作者： M.J. Lees J. Taylor P.C. Young A. Chotai Civil Engineering Department Imperial College of Science. Technology and Medicine. London. SW7 2BU UK Centre for Research on Environmental Systems and Statistics. Lancaster University. Lancaster LA1 4YQ UK

The paper describes the identification of a control model for carbon dioxide concentration in an Open-Top Chamber (OTC) used in plant physiology climate change experiments. This model is used to design an advanced, model-based, gain-scheduled controller using the Proportional-Integral-Plus (PIP) control design methodology developed by Young et al . (1987). Prior to implementation, the controller is evaluated by simulation, utilising realistic disturbance data

关键词： Biological Control True Digital Control Non-Minimum State-Space Proportional-Integral-Plus Scheduling

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