Characteristics of both thermoplastic and thermoset composite materials as they pertain to marine vehicle applications are discussed. Comparison of various material selection factors such as strength, damage and moist...
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Characteristics of both thermoplastic and thermoset composite materials as they pertain to marine vehicle applications are discussed. Comparison of various material selection factors such as strength, damage and moisture resistance, and flammability and toxicity as well as cost and availability of thermoset and thermoplastic composite materials are presented. Methods for testing and reducing the flammability and toxicity are discussed. Many commercially available composite systems are reported to provide favorable characteristics for marine applications. Although there seems to be a need for improved production technology for thermoplastics, they present potential advantages in physical properties over thermoset composites.
An inexpensive, versatile, and portable system is presented, which facilitates rapid fielddeterminations of redox potentials, ph, conductivity, ferrous and total iron, nitrite, specific conductance, dissolved oxygen,...
An inexpensive, versatile, and portable system is presented, which facilitates rapid fielddeterminations of redox potentials, ph, conductivity, ferrous and total iron, nitrite, specific conductance, dissolved oxygen, and temperature. Accuracy is facilitated by on-site measurements of most parameters using specially constructed flow-through cells and, for several analyses, sealed reagent ampoules, which can be broken anddeveloped inside a flowing stream of ground water. Coupled with laboratory analyses of more stable ground water parameters, this system can provide accurate and relatively inexpensive determinations of redox conditions in ground water.
作者:
BARROWS, LROCCHIO, JELarry Barrows received his M.S. and Ph.D. degrees in geophysics from the Colorado School of Mines in 1973 and 1978
respectively. He has worked as a systems engineer on Skylab remote-sensing experiments and as an exploration geophysicist in frontier areas of Alaska. Since 1979 he has specialized in geophysical surveying for ground water and hazardous waste site investigations first as the project geophysicist on a radioactive waste disposal program and then as a research scientist for the U.S. EPA. In 1988 he joined Earth Science and Engineering Inc. and LaCoste and Romberg Gravity Meters Inc. (4807 Spicewood Springs Rd. Bldg. 2 Austin TX 78759). Current projects include using microgravity to detect solution conduits in karst terrains and using seismicgroundroll to determine near-surface shear moduli. Judith E. Rocchio is the future air resource specialist on the Stanislaus National Forest (1977 Greenley Rd.
Sonora CA 95370). She will obtain the position upon completion of her M.A. degree in air resource management at Colorado State University Department of Natural Resources (1990). She was with Lockheed Engineering Management Services Co. Las Vegas Nevada prior to attending CSU where she was involved in several environmental monitoring programs and coauthored the paper with Dr. Barrows. From 1981 to 1986 Rocchio was a project geologist for Gower Oil Co. and Consolidation Coal Co. Denver Colorado. She received her B.S. in geology (1981) from the University of Nevada Las Vegas.
Field tests were conducted to determine representative total-intensity magnetic anomalies due to the presence of underground storage tanks and 55-gallon steel drums. Three different drums were suspended from a non-mag...
Field tests were conducted to determine representative total-intensity magnetic anomalies due to the presence of underground storage tanks and 55-gallon steel drums. Three different drums were suspended from a non-magnetic tripod and the underlying field surveyed with each drum in an upright and a flipped plus rotated orientation. At drum-to-sensor separations of 11 feet, the anomalies had peak values of around 50 gammas and half-widths about equal to the drum-to-sensor separation. Remanent and induced magnetizations were comparable; crushing one of the drums significantly reduced both. A profile over a single underground storage tank had a 1000-gamma anomaly, which was similar to the modeled anomaly due to an infinitely long cylinder horizontally magnetized perpendicular to its axis. A profile over two adjacent tanks had a smooth 350-gamma single-peak anomaly even though models of two tanks produceddual-peaked anomalies. demagnetization could explain why crushing a drum reduced its induced magnetization and why two adjacent tanks produced a single-peak anomaly. A 40-acre abandoned landfill was surveyed on a 50- by 100-foot rectangular grid and along several detailed profiles. The observed field had broad positive and negative anomalies that were similar to modeled anomalies due to thickness variations in a layer of uniformly magnetized material. It was not comparable to the anomalies due to induced magnetization in multiple, randomly located, randomly sized, independent spheres, suggesting that demagnetization may have limited the effective susceptibility of the landfill material. A different 6-acre site survey conducted on a 10- by 10-foot grid was analyzed to determine the maximum station spacing and line separation that could have been used. Essentially, all of the anomalies at this site would have been resolved by a survey conducted on a 20- by 20-foot grid and the larger anomalies would have been detected by a 50- by 50-foot grid.
This paper summarizes a study to estimate the potential for dry-well drainage of urban runoff to recharge and pollute ground water in Tucson, Arizona. We selected three candidate dry wells for study. At each site we c...
This paper summarizes a study to estimate the potential for dry-well drainage of urban runoff to recharge and pollute ground water in Tucson, Arizona. We selected three candidate dry wells for study. At each site we collected samples of runoff, dry-well sediment, vadose-zone sediment, perched ground water, and ground water. Water content data from vadose-zone samples suggest that dry-well drainage has created a transmission zone for water movement at each site. Volatile organic compounds, while undetected in runoff samples, were present in dry-well sediment, perched ground water at one site, and ground water at two sites. The concentrations of volatile organics (toluene and ethylbenzene) in the water samples were less than the corresponding EPA human health criteria. Pesticides were detected only in runoff anddry-well sediment. Lead and chromium occurred in runoff samples at concentrations above drinking water standards. Nickel, chromium, and zinc concentrations were elevated in vadose-zone samples at the commercial site. Of the metals, only manganese, detected at the residential site, exceeded Secondary drinking Water Standards in ground water. It is concluded that the three dry wells examinedduring this study are currently not a major source of ground water pollution.
The estimation of an absolute life expectancy of a structure is a complex process and the results are expected to have relatively large levels of uncertainty. In this study, a comparative analysis is undertaken betwee...
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The estimation of an absolute life expectancy of a structure is a complex process and the results are expected to have relatively large levels of uncertainty. In this study, a comparative analysis is undertaken between two different patrol boats. This is an approach which results in a higher confidence level because certain factors common to both boats can be eliminated by assuming them to be at constant normal levels. The study is limited to the critical forward bottom plating and takes into account the differences in material, plate dimensions, operational profile, structure and loading of the two vessels. Two failure modes, plastic plate deformation and fatigue, are considered, and a novel approach to plate wastage is included. Many factors affect the structural life of a vessel. They include structural type, operational profile, structural details, loads, inspection and maintenance, design methods, safety factors, corrosion, and environmental factors. There are three types of uncertainty associated with these factors; namely, physical randomness, statistical uncertainties, and model uncertainties. The methoddescribed is designed to address these uncertainties. The objective of the paper is to present the reliability-based structural life assessment method, and then to use it to evaluate and compare the structural performance of the forward bottom plating of the two patrol boats. The results of the evaluation are presented in the form of graphs and tables in order to facilitate the comparative evaluation. The method is performed within a computer-based format which allows parametric sensitivity analysis of several variables including the size of the plating panel, thickness, operational profile and loading. The sensitivity of the structural life expectancy of the forward bottom plating to variations in these parameters is evaluated.
A significant tonnage of HY-100 steel has been used in the structural designs of new ships and submarines for weight reduction, where HT and HY-80 steels had been previously used. A reduction in hull fabrication costs...
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A significant tonnage of HY-100 steel has been used in the structural designs of new ships and submarines for weight reduction, where HT and HY-80 steels had been previously used. A reduction in hull fabrication costs and higher productivity can be achieved by substitution of an HSLA steel for HY-100. The significant factor in cost savings through use of HSLA steel in fabrication is the reduction or elimination of preheat for welding. Based on the success of the HSLA-80 steel system, a program was initiated to develop and certify an HSLA-100 steel as a replacement for HY-100 in order to reduce fabrication costs. The alloy development and evaluation to support the certification of HSLA-100 steel plate and weldments for surface combatant structural and ballistic protection applications are summarized. HSLA-100 development consisted of three phases: (1) laboratory alloy development to formulate an interim specification; (2) trial steel mill plate production; and (3) plate production for the certification program. An interim specification for HSLA-100 steel plate was used as the basis for the commercial production of over 200 tons of HSLA-100 by domestic steel plate mills. The alloy design of HSLA-100 represents a significantly different metallurgy and microstructure than HSLA-80 steel, but retains the wettability of very low carbon steel. The certification program was conducted to establish the properties, welding characteristics, fabricability, and structural performance of HSLA-100 steel plate over a range of gages from 1/4 to 3 3/4 inches. The certification program included the characterization of production HSLA-100 steel plate mechanical, physical, and fracture properties; evaluation of wettability and welding process limits for structures of high restraint; studies of fatigue properties and effects of marine environments on HSLA-100; and the fabrication and evaluation of large scale structural models to validate the laboratory developed welding process parameters
作者:
YACHNIS, MDr. Arthur H. Wu:is a geotechnical engineering consultant
in the Office of the Chief Engineer Naval Facilities Engineering Command Department of the Navy Alexandria Virginia. Dr. Wu received his B.S. and M.S. degrees from the National Cheng Kung University Taiwan in 1956 and 1961 respectively his M.S. degree from Ohio State University in 1964 and his D.Sc. degree from The George Washington University in 1981. He has taught at The George Washington University U.S. Naval Academy and is an adjunct full professor at the University of the District of Columbia. He was selected as the 1985 NavFac Engineer of the Year is a fellow of the American Society of Civil Engineers and is listed in MarquisWho's Who in America. He has provided many complex geotechnical consultation services to the Navy and contributed to the application of the numerical modeling and computational mechanics in the analysis of graving drydock safety. John Cecilio:is the chief engineer for the Naval Facilities Engineering Command
Department of the Navy Alexandria Virginia. Mr. Cecilio received his B.S. degree in 1962 from Merrimack College Massachusetts and M.S. degree in 1971 from Catholic University of America in Washington D.C. As the chief engineer he is supervising twelve multi-discipline engineering consultants who are responsible for providing criteria guidance and technical assistance to resolve complex and unique design and construction problems. Mr. Cecilio is the chairman of the Certification Board for the U.S. Navy's dry-docks. He has over 27 years of experience in design and construction of complex facilities and was selected as the 1986 NavFac Engineer of the Year. He is a member of the Society of American Military Engineers and numerous professional engineering societies. Dr. Robert A. Bayles:is a research scientist at the Naval Research Laboratory (NRL)
Washington D.C. He received his B.S. degree in chemistry and physics from Lynchburg College in 1973. He received his M.S. (1975) and Ph.D. (1979) degrees in mat
Maintenance and safety certification of the Navy's graving drydocks are essential in supporting fleet operation and readiness. Thus, structural analyses of graving drydocks are made regularly by the Naval Faciliti...
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Maintenance and safety certification of the Navy's graving drydocks are essential in supporting fleet operation and readiness. Thus, structural analyses of graving drydocks are made regularly by the Naval Facilities engineering Command using a finite element computer program. An analytical method is implemented to evaluate the structural adequacy of existing drydocks which are subjected to static and earthquake loads. The results of the analyses are used in certifying the safety of drydocks. due to the complexity of the drydock structure, an analysis is begun by setting up structural models which can accurately include structural and geotechnical parameters for finite element numerical analysis. The accuracy of the results can then be checked through a comparison of the different models used in the analysis, and the comparison of field observations made from carefully monitored instrumentation. For example, in order to evaluate a mathematical analysis of the response of a drydock to static and earthquake loads, measurements of the movement of drydock walls in Charleston Naval Shipyard, South Carolina, were made by flooding anddraining the drydock during a docking operation. A dial gauge instrument was used to measure the displacement of a wall and a laser electronic distance measuring instrument (EdM) was used to measure the displacement across the width of the dry-dock. The purpose of this paper is to present the drydock wall stability analysis method and to compare the analytical results with the observed wall displacement. Conclusions were derived from the results of the finite element analysis and the measured wall displacement. The results were useful in the structural analyses and safety certification of the graving drydocks.
作者:
ZITZMAN, LHFALATKO, SMPAPACH, JLDr. Lewis H. Zitzman:is the group supervisor of the Advanced Systems Design Group
Fleet Systems Department The Johns Hopkins University Applied Physics Laboratory (JHU/APL). He has been employed at JHU/APL since 1972 performing applied research in computer science and in investigating and applying advanced computer technologies to Navy shipboard systems. He is currently chairman of Aegis Computer Architecture Data Bus and Fiber Optics Working Group from which many concepts for this paper were generated. Dr. Zitzman received his B.S. degree in physics from Brigham Young University in 1963 and his M.S. and Ph.D. degrees in physics from the University of Illinois in 1967 and 1972 respectively. Stephen M. Falatko:was a senior engineering analyst in the Combat Systems Engineering Department
Comptek Research Incorporated for the majority of this effort. He is currently employed at ManTech Services Corporation. During his eight-year career first at The Johns Hopkins University Applied Physics Laboratory and currently with ManTech Mr. Falatko's work has centered around the development of requirements and specifications for future Navy systems and the application of advanced technology to Navy command and control systems. He is a member of both the Computer Architecture Fiber Optics and Data Bus Working Group and the Aegis Fiber Optics Working Group. Mr. Falatko received his B.S. degree in aerospace engineering with high distinction from the University of Virginia in 1982 and his M.S. degree in applied physics from The Johns Hopkins University in 1985. Mr. Falatko is a member of Tau Beta Pi Sigma Gamma Tau the American Society of Naval Engineers and the U.S. Naval Institute. Janet L. Papach:is a section leader and senior engineering analyst in the Combat Systems Engineering Department
Comptek Research Incorporated. She has ten years' experience as an analyst supporting NavSea Spa War and the U.S. Department of State. She currently participates in working group efforts under Aegis Combat System Doctrin
This paper sets forth computer systems architecture concepts for the combat system of the 2010–2030 timeframe that satisfy the needs of the next generation of surface combatants. It builds upon the current Aegis comp...
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This paper sets forth computer systems architecture concepts for the combat system of the 2010–2030 timeframe that satisfy the needs of the next generation of surface combatants. It builds upon the current Aegis computer systems architecture, expanding that architecture while preserving, and adhering to, the Aegis fundamental principle of thorough systems engineering, dedicated to maintaining a well integrated, highly reliable, and easily operable combat system. The implementation of these proposed computer systems concepts in a coherent architecture would support the future battle force capable combat system and allow the expansion necessary to accommodate evolutionary changes in both the threat environment and the technology then available to effectively counter that threat. Changes to the current Aegis computer architecture must be carefully and effectively managed such that the fleet will retain its combat readiness capability at all times. This paper describes a possible transition approach for evolving the current Aegis computer architecture to a general architecture for the future. The proposed computer systems architecture concepts encompass the use of combinations of physically distributed, microprocessor-based computers, collocated with the equipment they support or embedded within the equipment itself. They draw heavily on widely used and available industry standards, including instruction set architectures (ISAs), backplane busses, microprocessors, computer programming languages anddevelopment environments, and local area networks (LANs). In this proposal, LANs, based on fiber optics, will provide the interconnection to support system expandability, redundancy, and higher data throughput rates. A system of cross connected LANs will support a high level of combat system integration, spanning the major warfare areas, and will facilitate the coordination anddevelopment of a coherent multi-warfare tactical picture supporting the future combatant command st
作者:
KYRTATOS, NPNICHOLAS P. KYRTATOS
PH.D. is associate professor of marine engineering at the National Technical University of Athens Greece. He obtained a 1st Class Hons. B.Sc. degree in marine engineering from the University of Newcastle upon Tyne (1975) and a Ph.D. degree in mechanical engineering from the Imperial College of Science and Technology London University (1979). He was postdoctoral research associate at Imperial College London (1979–1980). He was visiting professor in the Department of Mechanical Engineering McGill University Montreal Canada (1980–1982). He served at the Greek Airforce Research Centre Athens (1982–1984). He was assistant professor of marine engineering at NTUA (1984–1988).
The increasing use of on-board computers will make the utilization of sophisticated engine simulation models within integrated computerized ship propulsion plant management systems possible. These models can be used t...
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The increasing use of on-board computers will make the utilization of sophisticated engine simulation models within integrated computerized ship propulsion plant management systems possible. These models can be used to provide reference performance data for advanced control, performance optimisation, fault diagnosis, and predictive maintenance systems. This paper describes briefly the structure of advanced engine performance prediction models, commenting on the areas which require further development in view of the above applications. An engine simulation model originally developed on a mainframe computer was adapted to run on a microcomputer. Selected results are presented, using the model to predict the performance of a large slow-speed marine diesel engine, simulating various typical fault conditions.
The flow of ponded water into and through the unsaturated zone depends on both the saturated and unsaturated components of the hydraulic conductivity. Recent studies indicate that the ratio of the saturated (K fs ) to...
The flow of ponded water into and through the unsaturated zone depends on both the saturated and unsaturated components of the hydraulic conductivity. Recent studies indicate that the ratio of the saturated (K fs ) to the unsaturated (φ m ) components (K fs /φ m =α*) of flow lies within prescribed bounds for most field soils, i.e., 1m −1 ≤α*≤ 100 m −1 . In addition, the fact that the calculation of K fs and φ m is not strongly dependent on the choice of α*, suggests that a site estimation of α* leads to reasonable “best estimates” of K fs and φ m when using the constant head well permeameter technique. As a consequence, measurement of the steady flow rate using only one ponded head may be all that is necessary for many practical applications. Multiple head measurements or independent measurements of α* or φ m can be used, however, to give more accurate estimates of K fs if required.
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