Volatile organic compounds (VOCs) can be removed from contaminated ground water and subsurface media by surfactant-enhanced remediation processes. For the process to be economically competitive it is necessary to reco...
Volatile organic compounds (VOCs) can be removed from contaminated ground water and subsurface media by surfactant-enhanced remediation processes. For the process to be economically competitive it is necessary to recover and reuse the surfactant from this concentrated solution. The VOC can be removed from this concentrated solution by flash vacuum stripping, leaving the surfactant solution for reuse. In this study, the flash vacuum stripping of trichloroethylene (TCE) from an anionic surfactant solution in a co-current packed column was studied under rough vacuum conditions. The presence of surfactants lead to a reduction in the overall liquidphase volumetric mass transfer coefficient (MTC) of 40 to 95%, depending on flow rate and surfactant concentration at 50 degrees C and 16 kPa. At liquid loading rates of less than 13 cm(3)/cm(2)min, the MTC of TCE decreases rapidly with an increase in liquid loading rate, and at liquid loading rates above that, the MTC decreases slightly with an increase in the liquid loading rate. This trend may have been due to foaming. At surfactant concentrations above the critical micelle concentration, the effect of surfactant concentration was not significant at liquid loading rates less than 13 cm(3)/cm(2)min. However, beyond that rate, the MTC of TCE decreaseddrastically with an increase in surfactant concentration. The MTC of TCE increased with an increase in temperature. A large pressure drop (3 to 4 kPa/m) was observed across the packed beddue to foaming.
The article describes a modification to the usual procedures for training of critic and action neural networks in the dual heuristic programming (dHP) method (d. Prokhorov andd. Wunsch, 1996; R. Santiago, 1995; P. We...
详细信息
The article describes a modification to the usual procedures for training of critic and action neural networks in the dual heuristic programming (dHP) method (d. Prokhorov andd. Wunsch, 1996; R. Santiago, 1995; P. Werbos, 1994). This modification entails updating both the critic and the action networks at each computational cycle, rather than only one at a time. The distinction lies in the introduction of a (real) second copy of the critic network whose weights are adjusted less often and the "desired value" for training the other critic is obtained from this critic copy. Previously (G. Lendaris and C. Paintz, 1997), the proposed modified training strategy was demonstrated on the pole cart controller problem: the full 6 dimensional state vector was input to the critic and action NNs, however, the utility function only involved pole angle, not distance along the track (x). For the first set of results presented here, the 3 states associated with the x variable were eliminated from the inputs to the NNs, keeping the same utility function previously defined. This resulted in improved learning and controller performance. From this point, the method is applied to two additional problems, each of increasing complexity: for the first, an x-related term is added to the utility function for the pole cart problem, and simultaneously, the x-related states were added back in to the NNs (i.e., increase number of state variables used from 3 to 6); the second relates to steering a vehicle with independent drive motors on each wheel. The problem contexts and experimental results are provided.
despite the limits inherent within linearized frequency-domain ship motion and wave load computer codes, strip theory has been found to provide the design community with a fairly robust, practical design tool with rea...
详细信息
despite the limits inherent within linearized frequency-domain ship motion and wave load computer codes, strip theory has been found to provide the design community with a fairly robust, practical design tool with reasonable accuracy for most conventional displacement monohulls. However, the advent of new design concepts including multi-hulls and application of new materials as well as the push to incorporate reliability methods within surface ship structural design criteria has highlighted the need for more rigorous methods of developing a lifetime load spectrum. In this paper, a multilevel computation system for predicting ship motions and wave loads, up through and including extreme sea conditions, is presented. This system includes a traditional strip theory approach and newly developed linear and nonlinear three-dimensional time-domain methods. The new nonlinear methods are currently in the process of being validated by the U.S. Navy. The status of the current development is presented. Sample numerical results from the new nonlinear methods are compared with both linear frequency domain predictions and model tests.
The tropism system cognitive architecture provides an intuitive formalism for colonies of agents, either hardware or software. We present a fine-grained implementation of the architecture on a colony of software agent...
详细信息
The tropism system cognitive architecture provides an intuitive formalism for colonies of agents, either hardware or software. We present a fine-grained implementation of the architecture on a colony of software agents for the interpretation of human tactile gestures for robotic trajectory specification and modification. The fine-grained nature of the architecture and the use of the port-based object framework for agent instantiation allows the manual construction of a capable agent set that is reconfigurable and reusable across different gesture-based interaction tasks.
作者:
Atua, KAyyub, BMKhaled l. Atua:is a graduate student at the Reliability Engi-neering Program at the University of Maryland at College Park. He completed his B.S. degree in naval architecture and marine engineering in 1988
and completed his M.S. degree in naval architecture and marine engineering in 1992 at Alexandtia University. He is also a visiting scholar in the Civil Engineering Department at the University ofMaryland at Colkge Park. He is conducting research with Dc Bilal M. Ayyub in the area of develupment of reliability-based design of ship structures and systems. He is a member ofASNE and SNAME. He has authored or coauthored several papers and reports. Bilal M. Ayyub:
Ph.D. RE. is aprofssor of civil engineer-ing at the University of Maryland at College Park. He is also a researcher and consultant in the areas of structural engineering inspection methods and practices reliability and risk analysis. Dc Ayyub completed his B.S. degree in civil engineering in 1980 and completed both his M.S. (1981) and Ph.D. (1983) degrees in civil engineering at the Georgia Institute of Echnol-OD. Dc Ayyub has an extensive background in uncertainty modeling and analysis risk-based analysis and design simula-ion and marine structural reliability. He is engaged in research work involving structural reliability marine structures uncer-tainty modeling and analysis and mathematical modeling using the theories of probability statistics and fuzzy sets. He has completed several research projects that were funded by the National Science Foundation the U S. Coast Guard the U.S. Navy the U.S. Department of Defense the U.S. Army crops of Engineers the Maryland State Highway Administration the American Society ofMechanica1 Engineers and several engi-neering companies. Dc Ayyub served the engineering communio in various capacities through societies that include ASNE ASCE ASME SNAME IEEE-CS and NMIPS. He is a member ofthe ASME Research Committee of Risk Ethnology and the ASME Committee on Human Factors. Currently he is the chai
An introduction to a rational development of transverse stability criteria for surface ships is presented in this paper. The development is based on a probabilistic analysis of the uncertainties associated with the de...
详细信息
An introduction to a rational development of transverse stability criteria for surface ships is presented in this paper. The development is based on a probabilistic analysis of the uncertainties associated with the design parameters involved in determining the transverse stability. Reliability methods are used for assessing anddetermining transverse stability of ships. These reliability methods address the uncertainties associated with the basic design variables that are involved in stability assessment anddesign. The sources of uncertainty in stability variables are presented, uncertainties associated with these basic random variables are summarized, different reliability assessment methods are described, a case study that shows the computation procedure using some of these methods is discussed for illustration purposes, and finally, conclusions and recommendations for further work in this area are presented.
作者:
McCormick, MEBhattacharyya, RMouring, SEDr. Michael E. McCormick:is a research professor of civil engineering at The Johns Hopkins University. Before joining the Hopkins faculty in 1994
he was a professor of ocean engineering for twenty-five years at the U.S. Naval Academy. In addition he has held full-time faculty positions at Swarthmore College Trinity College (Hartford) and the Catholic University of America. He was also a hydrodynamicist at the David Taylor Model Basin for more than four years. Prof. McCormick received his undergraduate degree in mathematics and physics from AmericanUniversity a masters degree in applied mechanics and a Ph.D. in mechanical engineering from Catholic University a Ph.D. in civil engineering and a Sc.D. in engineering science from Trinity College in Dublin Ireland. He has over 100 publications including two books in the areas of ocean engineering wave mechanics and ocean wave energy conversion. He has also edited two books dealing with ocean engineering. In addition he is co-editor of both the journal Ocean Engineering and the Elsevier book series in ocean engineering. Dr. Rameswar Bhattacharyya:is professor of naval architecture at the U.S. Naval Academy
where he has served for twenty-six years and adjunct professor of mechanical engineering at The Johns Hopkins University. Prior to joining the Naval Academy faculty he was a faculty member in the Department of Naval Architecture and Marine Engineering at the University of Michigan. His research experience includes ten years at both the Lubecker Flender-Werke and the Hamburg Ship Model Basin in Germany. His research has led to numerous publications including two books one in the area of ship dynamics and the other in the area of computer-aided ship design. Prof. Bhattacharyya received his undergraduate degree in naval architecture from the Indian Institute of Technology and his doctorate in engineering from the Technical University of Hanover Germany. In addition he holds an honorary doctorate from the University of Veracruz. With Prof. McCormick he co
Panels and all other structural components of surface ships and submarines vibrate when the vessel is underway. The vibratory motions are primarily excited by the power plant. At operational (design) speeds, panels vi...
详细信息
Panels and all other structural components of surface ships and submarines vibrate when the vessel is underway. The vibratory motions are primarily excited by the power plant. At operational (design) speeds, panels vibrate in their fundamental modes and those associated with their higher harmonic frequencies. The panel motions have rather well-defined energy spectra, which depend on both the structural design, position of the panel and the rotational speed of the single or multiple power plants. The panel motions will interact with the vortices in the adjacent turbulent boundary layer. The interaction can result in either an increase in the frictional drag or a decrease. Because of this, the argument is made that the designs of the panels and their support systems should include considerations of this hydroelastic effect.
A prototype concurrent engineering tool has been developed for the preliminary design of composite topside structures for modern navy warships. This tool, named GELS for the Concurrent engineering of Layered Structure...
详细信息
A prototype concurrent engineering tool has been developed for the preliminary design of composite topside structures for modern navy warships. This tool, named GELS for the Concurrent engineering of Layered Structures, provides designers with an immediate assessment of the impacts of their decisions on several disciplines which are important to the performance of a modern naval topside structure, including electromagnetic interference effects (EMI), radar cross section (RCS), structural integrity, cost, and weight. Preliminary analysis modules in each of these disciplines are integrated to operate from a common set of design variables and a common materials database. Performance in each discipline and an overall fitness function for the concept are then evaluated. A graphical user interface (GUI) is used to define requirements and to display the results from the technical analysis modules. Optimization techniques, including feasible sequential quadratic programming (FSQP) and exhaustive search are used to modify the design variables to satisfy all requirements simultaneously. The development of this tool, the technical modules, and their integration are discussed noting the decisions and compromises required to develop and integrate the modules into a prototype conceptual design tool.
作者:
Hafner, ANArnold N. Hafner
Ph.D.:is founder and president of Information Systems Research (ISR). He has twenty-five years of experience in systems development and is published in the field of systems development management. He served as corporate research scientist at Systems Exploration Inc. from 1988 to 1991 program director at Computer Science Corporation from 1983 to 1988director of operations at Republic Management Systems Corporation from 1981 to 1983
and program manager at Computer Science Corporation from 1972 to 1981. A 1962 graduate of the US. Naval Academy he holds a doctoral degree in human behavior and engineering degrees in electronics and communications. He has taught courses on information systems and systems management at most of the colleges in the San Diego area. Dr. Hafner has presented fourteen refereed research papers while publishing sixteen articles and a book A Manager's Guide to Software System Development.
Evaluating complex systems is the subject of this paper, the third in a series investigating prototyping. It provides an interesting and helpful overview of how to evaluate systems prototypes and outlines the iterativ...
详细信息
Evaluating complex systems is the subject of this paper, the third in a series investigating prototyping. It provides an interesting and helpful overview of how to evaluate systems prototypes and outlines the iterative stream of developer-user interactions that is replacing older approaches to testing and evaluating new military systems, which promise to reduce the time required to develop and field future military capabilities. Changes to the acquisition process, such as those the paper sketches, will facilitate the nation's rapid transit through its current revolution in military affairs.
暂无评论