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PERFORMANCE OF A PRIORITIZED ON-BOARD BASEBAND SWITCH FOR A MULTISERVICE MULTIBEAM SATELLITE

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS 1994年第3期12卷 283-297页

作者： BOHM, S ELHAKEEM, AK HACHICHA, M Department of Electrical and Computer Engineering Concordia University 1455 De Maisonneuve Blvd. West Montreal H3A 1M8 Canada Was born in Montreal Canada on 14 September 1966. He received the B. Eng. degree in electrical engineering from Concordia University Montreal Canada in 1989. He is at present completing the M.A.Sc. degree in electrical engineering at Concordia University. (S'75–S'79–M'79–SM'86) received the Ph.D. degree from Southern Methodist University Dallas TX in 1979. He spent the next two years working as a Visiting Professor in Egypt after which he moved to Ottawa Canada in 1982. He assumed teaching and research positions in Carleton and Manitoba Univerities and later moved to Concordia University Montreal Canada in 1983 where he is now a Professor in the Electrical and Computer Engineering Department. He has published numerous papers in IEEE and international journals in the areas of spread spectrum and networking. He is a well-known expert in these areas and serves as a consultant to many companies. His current research interests include wide-band metropolitan networks switching architectures and performance of on-board multibeam satellites acquisitionless CDMA networks code distribution and orthogonalization of CDMA signals responsive congestion control for ATM-based networks ARQ techniques and investigation of the novel SUGAR CDMA systems in fading channels. Dr. Elhakeem is a Senior Member of the Canadian Electrical Engineering Society and Armed Forces Association. He has chaired numerous technical sessions in IEEE Conferences was the Technical Program Chairman for IEEE Montech 1986 Montreal Canada. Dr. Elhakeem is the key guest editor of theIEEE Journal of Selected Areas in Communicationsfor the May June issues 1993 covering CDMA networks. Advanced Technology & Networks VISTAR Telecommunications Inc. Ottawa Ontario K1G 3J4 Canada An Associate Director of Advanced Technology & Networks Group VISTAR Telecommunications Inc. Ottawa Canada. He is also an Adjunct Pr

In this paper, we study the performance of a prioritized on-board baseband switch in conjunction with a multibeam satellite handling integrated services. The services considered for the analysis include voice, video, file transfer and interactive data. The prioritized switch uses both input and output buffering, switch speed-up as well as a two-phase head-of-line resolution algorithm, in order to reduce the buffer loss while maintaining acceptable user delays. The minimum required buffer capacity and switch speed-up for each service in a prioritized environment are found under uniform traffic conditions. It is shown that under uniform traffic conditions, only minimal buffering and switch speed-up are needed even for the lowest priority users. The performance dependence on the switch size is also substantially reduced with head of line resolution and buffering even in a prioritized environment.

关键词： SWITCH ON-BOARD BASEBAND MULTIBEAM PRIORITIZED HEAD-OF-LINE UNIFORM LOAD SPEED-UP

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On the discrepancy between serial and parallel of zero-knowledge protocols 12th

On the discrepancy between serial and parallel of zero-knowl...

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12th Annual International Cryptology Conference, CRYPTO 1992

作者： Sakurai, Kouichi Itoh, Toshiya Computer and Information Systems Laboratory Mitsubishi Electric Corporation 5-1-1 Ofuna Kamakura247 Japan Department of Information Processing Interdisciplinary Graduate School of Science and Engineering Tokyo Institute of Technology 4259 Nagatsuta Midori-ku Yokohama227 Japan

ISBN: (纸本)9783540573401

In this paper, we investigate the discrepancy between a serìal version and a parallel version of zero-knowledge protocols, and clarify the information "leaked" in the parallel version, which is not zero-knowledge unlike the case of the serial version. We consider two sides: one negative and the other positive in the parallel version of zero-knowledge protocols, especially of the Fiat-Sbamir scheme. © Springer-Verlag Berlin Heidelberg 1993.

关键词： computers

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PERFORMANCE TESTING OF SHIPBOARD ELECTRONIC systems

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NAVAL ENGINEERS JOURNAL 1993年第3期105卷 118-124页

作者： HARDER, G MARTIN, RA PE George Harder:is an electronics engineer for Naval Undersea Warfare Center Detachment Norfolk's Electromagnetic Engineering Branch located at the Norfolk Shipboard Electronic Systems Evaluation Facility (SESEF) site. He is responsible for fleet electromagnetic readiness (FEMR) inspections on board Navy ships and provides computer programming support to SESEF. Mr. Harder has a bachelor of science degree in electrical engineering from the University of Florida and has qualified for his professional engineering license in the state of Virginia. Robert A. Martin:is a supervisor electronics engineer employed by the Naval Undersea Warfare Center Detachment Norfolk. He functions as the branch head for the Electromagnetic Engineering Office which is responsible for the operation of the Norfolk Shipboard Electronic Systems Evaluation Facility (SESEF) and the Fleet Electromagnetic Readiness (FEMR) Program. Mr. Martin received a bachelor of science degree in electrical engineering from the University of Akron.

Performance evaluation of shipboard electronic systems entails debugging the systems in a laboratory environment, placing them in service and relving on svstem operators to provide feedback. General testing can be performed at selected sites by system designers, but each site where equipment is to be installed can offer unique problems. It is impossible to predict all the scenarios. Unique problems are more the rule than the exception when equipment is destined for Navy ships. Ship deployments make for difficult logistics when sending test teams to evaluate system failures. So, out of necessity, if newly installed equipment receives the proper inputs and generates the proper outputs, it is accepted and becomes the sailor's responsibilitv to maintain. In cases where documentation is ambiguous or incomplete, it is left to the sailor's ingenuity to continue testing and training on equipment. This is generallv obtained through computer simulations and back-to-back testing which can provide results for ideal conditions, but does not take the dynamics of interference into account. Remote site testing is the only way to get a true representation of equipment performance and training problems. Electronic system operators on board Navy vessels are fortunate, thev have help. There exists an organization available near major naval ports worldwide whose existence is to test electronic systems performance. The testing utilizes electronic systems as they would normally be configured for operations. This organization is the Shipboard Electronic Svstem Evaluation Facility (SESEF).

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Binding Energies of Double-Λ Hypernuclei and ΛΛG-Matrix

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Progress of Theoretical Physics 1993年第1期89卷 109-117页

作者： Himeno, Hiroyuki Sakuda, Toshimi Nagata, Sinobu Yamamoto, Yasuo Graduate School of Science and Technology Niigata University Niigata 950-21 Department of Physics Miyazaki University Miyazaki 889-21 Department of Computer Science and Systems Engineering Miyazaki University Miyazaki 889-21 Institute for Nuclear Study University of Tokyo Tanashi 188 and Physics Section Tsuru University Tsuru 402*)

Binding energies of double-Λ hypernuclei10ΛΛBe,13ΛΛB and6ΛΛHe are calculated on the basis ofG-matrix theory in finite nuclei. The core + Λ+ Λ three-body model is adopted and theG-matrix for ΛΛ interaction is treated consistently with the model space. As the bare interaction the Nijmegen model D and model F are used. It is discussed that the consistency of the interaction with the model space is very important to calculate reliably the binding energies. It is shown that if the new event of double-Λ hypernuclei is interpreted as13ΛΛB, model D reproduces the experimental data very well, whereas model F does not.

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AN OVERVIEW OF IN-SITU AIR SPARGING

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GROUND WATER MONITORING AND REMEDIATION 1993年第4期13卷 127-135页

作者： JOHNSON, RL JOHNSON, PC MCWHORTER, DB HINCHEE, RE GOODMAN, I Dr. Richard L. Johnson is an associate professor in the Department of Environmental Science and Engineering at the Oregon Graduate Institute (P.O. Box 91000 Portland OR 97291). He is also the director of the OGI Center for Groundwater Research and the OGI Large Experimental Aquifer Program. Dr. Paul C. Johnson is a senior research engineer at Shell Development Co. (Westhollow Research Center P.O. Box 1380 Houston TX 77251). Dr. David B. McWhorter is a professor in the Department of Agricultural and Chemical Engineering at Colorado State University (Engineering Research Center Foothills Campus Fort Collins CO 80523). Dr. Robert Hinchee is a research leader in the Environmental Technology Department at Battelle Memorial Institute (505 King Ave. Columbus OH 43201). Iris Goodman is an environmental scientist with the Advanced Monitoring Systems Division at the U.S. EPA Environmental Monitoring Systems Laboratory (P.O. Box 93478 Las Vegas NV 89192).

In situ air sparging (IAS) is becoming a widely used technology for remediating sites contaminated by volatile organic materials such as petroleum hydrocarbons. Published data indicate that the injection of air into subsurface water saturated areas coupled with soil vapor extraction (SVE) can increase removal rates in comparison to SVE alone for cases where hydrocarbons are distributed within the water saturated zone. However, the technology is still in its infancy and has not been subject to adequate research, nor have adequate monitoring methods been employed or even developed. Consequently, most IAS applications are, designed, operated, and monitored based upon the experience of the individual practitioner. The use of in situ air sparging poses risks not generally associated with most practiced remedial technologies: air injection can enhance the undesirable off-site migration of vapors and ground water contamination plumes. Migration of previously immobile liquid hydrocarbons con also be induced. Thus, them is an added incentive to fully understand this technology prior to application. This overview of the current state of the practice of air sparging is a review of available published literature, consultation with practitioners, a range of unpublished data reports, as well as theoretical considerations. Potential strengths and weaknesses of the technology are discussed and recommendations for future investigations given.

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HYDROCARBON VAPOR DIFFUSION IN INTACT CORE SLEEVES

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GROUND WATER MONITORING AND REMEDIATION 1993年第1期13卷 139-150页

作者： OSTENDORF, DW MOYER, EE XIE, YF RAJAN, RV David W. Ostendorf (Civil Engineering Department University of Massachusetts Amherst MA 01003) is an associate professor in the Environmental Engineering Program of the Civil Engineering Department of the University of Massachusetts at Amherst. His research interests include unconfined aquifer contamination hazardous waste site remediation and analytical modeling of problems in environmental fluid mechanics. Ostendorf is a Registered Professional Engineer in Massachusetts and a member of the American Geophysical Union American Society of Civil Engineers Soil Science Society of America Water Pollution Control Federation and Association of Environmental Engineering Professors as well as the National Ground Water Association. Ellen E. Moyer (Civil Engineering Department University of Massachusetts Amherst MA 01003) is a doctoral candidate in the Environmental Engineering Program of the Civil Engineering Department of the University of Massachusetts at Amherst with an M.S. degree in environmental engineering from that institution. Her research interests include subsurface investigation soil venting bioremediation and analytical modeling of subsurface contamination. She has six years of professional experience managing hazardous waste site investigation and cleanup projects and is a member of the National Ground Water Association and the American Society of Civil Engineers. Yuefeng Xie (Civil Engineering Department University of Massachusetts Amherst MA 01003) is a postdoctoral research associate in the Environmental Engineering Program of the Civil Engineering Department of the University of Massachusetts at Amherst. His research interests include environmental analyses drinking water treatment and the chemical characterization and removal of disinfection by-products. A graduate with a Ph.D. and an M.S. in environmental engineering and a B.S. in chemistry and chemical engineeering from Tsinghua University Beijing China Xie is a member of the American Water Works Association and the Water Poll

The diffusion of 2,2,4-trimethylpentane (TMP) and 2,2,5-trimethylhexane (TMH) vapors out of residually contaminated sandy soil from the U.S. Environmental Protection Agency (EPA) field research site at Traverse City, Michigan, was measured and modeled. The headspace of an intact core sleeve sample was swept with nitrogen gas to simulate the diffusive release of hydrocarbon vapors from residual aviation gasoline in and immediately above the capillary fringe to a soil-venting air flow in the unsaturated zone. The resulting steady-state profile was modeled using existing diffusivity and air porosity estimates in a balance of diffusive flux and a first order source term. The source strength, which was calibrated with the observed flux of 2,2,4-TMP leaving the sleeve, varied with the residual gasoline remaining in the core, but was independent of the headspace sweep flow rate. This finding suggested that lower soil-venting air flow rates were in principle as effective as higher air flow rates in venting LNAPL vapors from contaminated soils. The saturated vapor concentration ratio of 2,2,4-TMP to 2,2,5-TMH decreased from 6.6 to 3.5 over the duration of the experiments in an expression of distillation effects. The vertical profile model was tested against sample port data in four separate experiments for both species, yielding mean errors ranging from 0 to -24 percent in magnitude.

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Interactive analysis of propagation in optical fibers

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computer Applications in engineering Education 1993年第3期1卷 197-197页

作者： Aicklen, G.H. Tamil, L.S. Erik Jonsson School of Engineering and Computer Science and Center for Applied Optics The University of Texas at Dallas Richardson 75080 Prior to returning to graduate study in 1987 Mr. Aicklen had industrial experience with the Defense Systems and Electronics Group at Texas Instruments in Dallas. In 1985 he left Texas Instruments to pursue a private venture. In 1987 he joined the staff of The University of Texas at Dallas as a research associate in the Erik Jonsson School of Engineering and Computer Science. Mr. Aicklen's research interests include fiber optics nonlinear guided wave optics integrated optical devices and numerical methods in optics. Dr. Tamil is a member of Sigma Xi Optical Society of America Electromagnetics Academy and is a elected member of Commission B and D of the International Union of Radio Science.

We have developed a set of computer codes that compute the propagation constants and field patterns for the propagating modes of cylindrical optical fibers. From a simple set of finite difference equations, solutions of the scalar Helmholtz wave-equation may be computed across a range of normalized frequencies to generate curves describing the dispersion characteristics of the fiber. Accurate cutoff frequencies for any mode can also be computed. We designed the computer codes around α-index profiles since these profiles have been extensively covered in the literature, but our system also supports arbitrary profiles within the limits of the “small index gradient” and “weakly guiding” approximations. The computer codes are accurate and fast. They may be used interactively to explore dispersion in optical fibers and the effects of finite cladding width on dispersion.

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BEST VALUE CONTRACTING

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NAVAL ENGINEERS JOURNAL 1993年第6期105卷 59-68页

作者： ZACKS, MR DEMAS, TA Michael R. Zacks:attended Massachusetts Maritime Academy and received his bachelor of science in marine engineering degree in 1985. He is currently enrolled at the University of Maryland where he is working on a master's degree in general administration/financial management. Mr. Zacks is the assistant project manager for the Coastal Living Marine Resource Vessels in the National Oceanic Atmospheric Administration's (NOAA) Fleet Modernization and Replacement Program Office. His current responsibilities encompass providing technical and management support for the procurement construction testing and delivery of these ships. His previous jobs included working for the Naval Sea Systems Command's (NavSea) Combat Support Ocean Research and Surveillance Program Office (PMS 383) Ship Design and Engineering Directorate's Surface Launched Weapons Branch (56W3) and Research Analysis and Management (RAM) Corporation. Thomas A. Demas:received a bachelor of science degree in civil engineering from Old Dominion University and a master's degree in business administration from Averett College. He is a recent graduate from the NavSea Commander's Development Program (CDP). Mr. Demas is the assistant project manager for the AGOR-23 24 25 and National Oceanic and Atmospheric Administration's oceanographic research ships in NavSea's Combat Support Ocean Research and Surveillance Program Office. While participating in the CDP Mr. Demas worked in the following offices: OpNav OP321 as a FMP action officer CincPacFlt N43 as a maintenance officer ASN(RD&A) as director of maintenance and modernization and NavSea 56W14 as a branch head of closures and outfitting branch. Prior to the CDP he held a position with the Gas Turbine Surface Combatant Program Office as the West Coast project manager for DD-963 class destroyers. Before working for NavSea Mr. Demas was employed as a junior engineer with TRACOR and C-CUBED Corporation. His responsibilities included providing general systems engineering support to NavSea and the Nava

The best value concept is based on making decisions on an offeror's technical competence, proven past performance, management capability, life-cycle costs, and product quality. The evaluation of these factors should be structured to ensure consideration is given to determine the overall benefit associated with the offered price. This paper advocates using the best value concept as the method for developing and rating proposal evaluation factors for the procurement of new ships. It discusses methods for establishing evaluation factors, developing standards to evaluate, associated documentation, and weighting and scoring the factors. The information for this paper was obtained from personal interviews, hands-on experience developing and evaluating best value proposals, and documentation research. If properly executed, the best value concept will enable the Navy to improve ships while reducing operating costs.

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EPAS APPROACH TO VADOSE ZONE MONITORING AT RCRA FACILITIES

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GROUND WATER MONITORING AND REMEDIATION 1993年第1期13卷 151-158页

作者： DURANT, ND MYERS, VB ECCLES, LA Washington D.C. 20460) has worked as an environmental scientist in the RCRA corrective action program at EPA since 1989. After graduating from Colgate University in 1987 Durant worked for GeoTrans Inc. conducting hydrogeologic investigations at numerous waste disposal sites throughout the northeastern United States. At present Durant is pursuing an M.S. degree in environmental science from The Johns Hopkins University. His research is focused on enhancing in situ biodegradation of aromatic organic compounds in the subsurface. Washington D. C. 20460) graduated from The Johns Hopkins University in 1972 with a B.A. degree in natural sciences. Myers received a Ph.D. in oceanography from Florida State University in 1977. During 1978 he held a post doctoral fellowship at University of Florida in the Department of Environmental Engineering and Science. From 1979 to 1983 Myers was employed by the Florida Department of Environmental Regulation where he worked on environmental restoration projects. Since 1984 Myers has worked at EPA managing RCRA ground water monitoring and corrective action programs. Lawrence A. Eccles (U.S. Environmental Protection Agency Environmental Monitoring Systems Laboratory P.O. Box 93478 Las Vegas NV 89193–3478) is a hydrologist with the EPA Environmental Monitoring Systems Research Laboratory in Las Vegas Nevada. Eccles is responsible for the development of vadose zone and in situ monitoring techniques and guidelines. After graduating from Monmouth College with a B.S. degree in chemistry Eccles performed graduate work in chemical engineering at New Mexico State University. He received formal training in hydrology in 1969 from the U.S. Geological Survey in Denver and worked with that agency before joining EPA at Las Vegas in 1984. One of his co-authored articles was chosen for the Best Paper Award by the journal Ground Water in 1975 and another was the subject of a cover story for Water Well Journal in 1977.

The U.S. Environmental Protection Agency (EPA) recently proposed to amend federal regulations to require vadose zone monitoring at certain hazardous waste facilities. To support this proposal, EPA evaluated previous policy on vadose zone monitoring and examined advances in vadose zone monitoring technology. Changes in EPA vadose zone monitoring policy were driven by demonstrated advances in the available monitoring technology and improvements in understanding of vadose zone processes. When used under the appropriate conditions, currently available direct and indirect monitoring methods can effectively detect contamination that may leak from hazardous waste facilities into the vadose zone. Direct techniques examined include soil-core monitoring and soil-pore liquid monitoring. Indirect techniques examined include soil-gas monitoring, neutron moderation, complex resistivity, ground-penetrating radar, and electrical resistivity. Properly designed vadose zone monitoring networks can act as a complement to saturated zone monitoring networks at numerous hazardous waste facilities. At certain facilities, particularly those in arid climates where the saturated zone is relatively deep, effective vadose zone monitoring may allow a reduction in the scope of saturated zone monitoring programs.

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UNDERWATER INSPECTION FOR WELDING AND OVERHAUL

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NAVAL ENGINEERS JOURNAL 1993年第5期105卷 37-42页

作者： MITTLEMAN, J SWAN, L John Mittleman:is a mechanical engineer at the Naval Surface Warfare Center Dahlgren Division Coastal Systems Station in Panama City Florida. His Primary Responsibilities are in the development of underwater nondestructive testing equipment for use by fleet divers and inspectors. He also performs research in the characterization of metal microstructure through ultrasonic scattering measurements. Mr. Mittleman received his BS from Cornell University in 1969 and science master's in ocean engineering from the Massachusetts Institute of Technology in 1970. His research currently supports doctoral studies with Iowa State University. Mr. Mittleman received the American Society of Naval Engineer's Solberg Award in 1981 for his contributions to underwater ship hull inspection. Mr. Mittleman is a member of ASNE ASNT ASTM IoD Sigma Xi Tau Beta Pi and Phi Kappa Phi. Lisa Swan:is a mechanical engineer at the Naval Surface Warfare Center in Panama City Florida. She is involved in nondestructive testing engineering primarily in the underwater arena. Ms. Swan holds a bachelor of science in materials engineering from North Carolina State University. She is a graduate of the Federal Women's Executive Leadership Program. Ms. Swan is a member of ASNT.

Significant progress has been made in making underwater ultrasonic thickness gauging and magnetic particle inspections available to the fleet. Under sponsorship from the Naval Sea systems Command, Director of Ocean engineering, Underwater Ship Husbandry Division (NavSea 00C5), the Coastal systems Station has developed complete hardware packages supporting these two nondestructive test methods, and has introduced them to military inspectors at a shore intermediate maintenance activity, a destroyer tender, and a naval shipyard. Performance trials conducted prior to taking the systems to the field have been accepted by NavSea, Ships' Concepts Group, Materials Subgroup, Metals Division (NavSea 5142) as evidence that these inspections can reliably be performed underwater. Avenues for certifying specially trained divers and inspectors are being developed;for the first time the Navy will have all of the elements in place for underwater inspections satisfying the requirements of Mil-Std-271 (Requirements for Nondestructive Testing Methods) and the Naval Ships' Technical Manual Chapter 074. Underwater ultrasonic thickness gauging has also been slated for use in the fleet, as data from laboratory and field trials have consistently shown that reliable results can be obtained by a team comprising a certified topside inspector and a diver. In tests performed at the Ship Repair Facility (SRF), Yokosuka, underwater readings were compared to those taken in dry dock by SRF inspectors, and independently by contract inspectors. On the basis of approximately 800 locations, differences between the data sets were found to be randomly distributed, with a standard deviation on the order of 0.02''. This level of accuracy is largely sufficient to distinguish plate which will need replacement during overhaul, or plate which is thick enough to weld on.

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