The objectives of Human engineering (HE) are generally viewed as increasing human performance, reducing human error, enhancing personnel and equipment safety, and reducing training and related personnel costs. There a...
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The objectives of Human engineering (HE) are generally viewed as increasing human performance, reducing human error, enhancing personnel and equipment safety, and reducing training and related personnel costs. There are other benefits that are thoroughly consistent with the direction of the Navy of the future, chief among these is reduction of required numbers of personnel to operate and maintain Navy ships. The Naval Research Advisory Committee (NRAC) report on Man-Machine Technology in the Navy estimated that one of the benefits from increased application of man-machine technology to Navy ship design is personnel reduction as well as improving system availability, effectiveness, and safety The objective of this paper is to discuss aspects of the human engineering design of ships and systems that affect manning requirements, and impact human-performance and safety The paper will also discuss how the application of human engineering leads to improved performance, and crew safety, and reduced workload, all of which influence manning levels. Finally, the paper presents a discussion of tools and case studies of good human engineering design practices which reduce manning.
We present a mathematical model for scheduling a computer assisted gang-rip saw system. Such systems are typically used within the furniture manufacturing industry for processing (ripping) lumber. This model uses the ...
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We present a mathematical model for scheduling a computer assisted gang-rip saw system. Such systems are typically used within the furniture manufacturing industry for processing (ripping) lumber. This model uses the concept of column generation of linear programming to design appropriate saw arbors, and to select a set of arbors with their corresponding run time, in order to process a given stream of incoming lumber according to a demand schedule for finished cut widths. Results of a limited computational experiment with this model are discussed.
作者:
Calvano, CNRiedel, JSProfessor Charles N. Calvano
Capt. USN (Ret.): of the Naval Postgraduate School is responsible for a program in Total Ship Systems Engineering. He is a graduate of the Naval Academy who served as a surface warfare officer. After completion of his graduate education at MIT he became an Engineering Duty Officer and served at Boston Naval Shipyard in several capacities. He was the Repair Facilities Advisor to the Vietnamese Navy the Project Officer for construction of nuclear powered guided missile cruisers (CGNs) at the Supervisor of Shipbuilding
Newport News Virginia and served on the staff of the Commander
Naval Surface Forces U.S. Atlantic Fleet and later at the Supervisor of Shipbuilding in Portsmouth Virginia in maintenance and overhaul management positions. He was Officer in Charge of the Annapolis Laboratory of the David Taylor Research Center and Commanding Officer of the Engineering Duty Officer School. He retired from active duty in October 1991 after serving in the Naval Sea Systems Command as the Director of the Ship Design Group and of the Advanced Concepts and Technology Group. Lt. Jeffrey S. Riedel
USN:is an Engineering Duty Officer currently assigned to the Supervisor of Shipbuilding Bath Maine. He obtained his B.S. degree in Marine Engineering from Maine Maritime Academy in 1986 and his M.S. degree in Mechanical Engineering plus a Mechanical Engineer's degree from the Naval Postgraduate School in 1993. Lt. Riedel's naval career has included duty aboaqrd USS Wainwright (CG 28) as auxiliaries officer damage control assistant and main machinery officer. Currently he serves as the assistant production officer at SUPSHIP Bath in charge of DDG 51 class construction and delivery.
This paper describes the design of a Regional Deterrence Ship (RDS 2010) for the 2010 timeframe. The requirements for the design were for a ship to operate in littoral areas of the world with a mission of deterring re...
This paper describes the design of a Regional Deterrence Ship (RDS 2010) for the 2010 timeframe. The requirements for the design were for a ship to operate in littoral areas of the world with a mission of deterring regional conflicts and of hampering the efforts of the aggressor in such a conflict. In addition the ship's mission included the evacuation of friendly personnel as hostilities become likely. The problem countering the littoral threat during times of constrained budgets is addressed. Top level requirements for the design, generated in parallel with ''.... From the Sea'' [1], were used to set the design goals. The paper describes the manner in which littoral warfare changes the nature of the challenges faced by Navy surface combatants, including a ship such as the RDS 2010. A number of factors become more crucial design concerns than for blue water ships, including reduced reaction times, likelihood of attack from hidden land sites, shallow water mines and shallow water USW Certain other factors become less critical in littoral areas and this also has ship design impacts. While some present ship designs can perform some of the tasks needed in a littoral warfare/regional conflict environment, none represents a completely integrated design (hull, mechanical & electrical;combat systems;fiscal and manning constraints;reduced vulnerability;robust self-defense etc.) for a vessel stationed in waters that, without warning, can become hostile. After describing the mission requirements to which the RDS 2010 was designed, the paper discusses the controlling design philosophy and decisions and describes the process used to assess threats to the ship. The process of combat system selection, against the backdrop of expected threat scenarios, is described and the intended approach to integration of the combat system is discussed. In recognition that decreased reaction times and surprise attacks are likely to threaten a ship engaged in regional deterrence, discussions oi
Cavitation of superplastic metal matrix (6061Al alloy) composite reinforced by 20% volume fraction of Si3N4, particulate and Si3N4, whisker has been investigated. A constant stress tention test was carried out at temp...
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Cavitation of superplastic metal matrix (6061Al alloy) composite reinforced by 20% volume fraction of Si3N4, particulate and Si3N4, whisker has been investigated. A constant stress tention test was carried out at temperature of 818K and stress of 8MPa for the composite containing Si3N4, particulate, and at 833K, 10MPa for the composite containing Si3N4, whisker. Volume of cavity in the Si3N4p/6061Al composite was larger than that in the Si3N4w/6061Al composite at a range of strain up to 1.5. Both composites already included the volume of cavity of 0.6-0.8% at a strain of 0.2. Cavity volume fraction exponentially increased with increasing strain. Most cavities of both composites were nucleated at the interface of matrix and reinforcements. Cavities in the Si3N4p/6061Al composite were almost granular and those in the Si3N4w/6061Al composite were either granular or flat.
The Si3N4 particulate reinforced 6061Al(Al-Mg-Si) matrix composite, which included 20% or 30% volume fraction of reinforcement, denoted as the 20%Vf and the 30%Vf respectively, has been produced by powder metallurgica...
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The Si3N4 particulate reinforced 6061Al(Al-Mg-Si) matrix composite, which included 20% or 30% volume fraction of reinforcement, denoted as the 20%Vf and the 30%Vf respectively, has been produced by powder metallurgical processing followed by hot extrusion at 773K with a reduction ratio of 100. The composites exhibited a typical superplastic behavior at a temperature of 848K for the 20%Vf and 823K for the 30%Vf, and a maximum elongation of 380% was obtained for the 20%Vf at a constant stress of 5MPa and 734% was obtained for the 30%Vf at a stress of 8MPa respectively. It has been clarified that these composites exhibited cavitation after a superplastic deformation. Cavity volume fractions exponentially increased with increasing strain in both composites. The cavity volume fraction of the 20%Vf specimen was less than that of the 30%Vf specimen at a strain up to 1.2. The maximum cavity volume fraction throughout the experiments was 2% at a strain of 1.5 for the 30%Vf specimen. SEM obsevation showed that cavities had always formed at interface between matrix and reinforcements, and the size of most cavities was less than 1μm. However, a few large cavities of more than 1μm in a mean diameter also appeared in both specimens in an early stage of straining. The larger cavities were grown rapidly and elongated parallel to the tensile axis with increasing strain which may cause the fracture.
The long-term reliability of surface mount (SM) interconnections remains an important issue in many electronics packaging technologies. Strain-reliefs with sufficient compliance can minimize the cyclic loads impressed...
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The long-term reliability of surface mount (SM) interconnections remains an important issue in many electronics packaging technologies. Strain-reliefs with sufficient compliance can minimize the cyclic loads impressed on SM solder connections during operational temperature excursions, appreciably increasing the margin for long-term attachment reliability. Compliance evaluation was performed for an inter-board strain-relief, or bond-strap, in a commercial Low-Noise Amplifier (LNA) used in various AT&T wireless transmission systems. The bond-strap compliance was optimized, within practical forming and assembly constraints, to provide robust SM interconnection during the expected product service life.
Contents and implementation of a computer laboratory for undergraduate electromagnetics are described. The laboratory consists of four 3-hour sessions covering vector calculus, Maxwell's equations (integral and di...
Contents and implementation of a computer laboratory for undergraduate electromagnetics are described. The laboratory consists of four 3-hour sessions covering vector calculus, Maxwell's equations (integral and differential forms), wave propagation in materials, and wave behavior at planar interfaces. Each session contains theory (in the Help file), animations (where relevant) and a quiz. The program runs on IBM compatible 486-based PCs in a Windows environment and uses the Borland C ++ 4.0 compiler.
作者:
DAVIS, CBMCNICHOLS, RJCharles B. Davis is principal statistician with Environmet- rics & Statistics Ltd. (EnviroStat
1853 Wellington Court Henderson NV 89014). After receiving his M.S. in mathematics and statistics and Ph.D. in statistics from the University of New Mexico he joined the Mathematics Department of the University of Toledo to establish its graduate program in statistics with emphasis on consulting and applications. He and McNichols became involved in consulting and research related to statistical issues arising in RCRA ground water monitoring regulation in 1985 and formed EnviroStat in 1990. Davis left academia in 1992 to concentrate on environmental statistics. Roger J. McNichols is professor and chairman of the Industrial Engineering Department at The University of Toledo
(Toledo OH 43606). After receiving his Ph.D. in industrial engineering from The Ohio State University he joined the faculty of Texas A and M University where he directed the Maintainability Engineering Graduate Program at Red River Army Depot. At University of Toledo he is also chairman of the Systems Doctoral Program and has served as associate dean of engineering. His research and consulting interests include reliability quality control manufacturing environmental monitoring mathematical modeling and applied statistics.
Current federal ground water monitoring statistical regulation dates from the revised RCRA Subtitle C Final Rule of 1988. That rule was a considerable advance over previous RCRA statistical rules. However, two major p...
Current federal ground water monitoring statistical regulation dates from the revised RCRA Subtitle C Final Rule of 1988. That rule was a considerable advance over previous RCRA statistical rules. However, two major problem areas remained: facility-wide false positive rate (FWFPR) control and spatial variability. Progress has been made in the 1991 Subtitle D Final Rule and in guidance;the 1992 Addendum to Interim Final Guidance in particular includes a substantial conceptual advance toward resolving the FWFPR problem. Other areas of improvement include normality testing and distribution assumptions, dropping the four independent samples per monitoring period requirement, allowing a preliminary evaluation short of a 40 CFR Part 258 Appendix II assessment upon finding a statistically significant increase, and suggesting superior alternatives to analyses of variance (ANOVAs) and tests of proportions. The problem of dealing with natural spatial variability remains. Although certain techniques listed in the regulations can control for inherent spatial variability and the performance standards require doing so ''when necessary,'' little attention has been paid to the ubiquity of such spatial variation. Moreover, regulatory traditions favoring upgradient-downgradient comparisons often make control of natural spatial variation difficult and ineffective. With new, lined facilities easily implemented statistical solutions are available;however, dealing with the several existing solid waste facilities which will now be regulated under Subtitle D will present major challenges. In short, the 1988 revision of the Subtitle C rules made it more possible to provide statistically sound monitoring programs, and there has been steady progress since then. Challenges remain, however. These vary from state to state, particularly with regard to controlling false positives and false negatives in the presence of natural spatial variability.
The problem of sequencing units on a mixed-model assembly line can be viewed with several objectives in mind. Past research has focused mainly on two separate performance measures: (1) minimizing the length of the lin...
The problem of sequencing units on a mixed-model assembly line can be viewed with several objectives in mind. Past research has focused mainly on two separate performance measures: (1) minimizing the length of the line (which is equivalent to minimizing the risk of stopping the conveyor when system variability is present and the station lengths are fixed);or (2) maintaining a rate of assembly equal to the demand rate for each model type in the production schedule. The latter is the more appropriate in a just-in-time environment. We present a bicriteria formulation of the problem that can be used to examine the tradeoffs between line length and parts usage. The resultant model takes the form of a mixed integer nonlinear program and is solved with a combination of heuristics and branch and bound. Results are reported for a wide range of problem sizes, as defined by the number of stations on the line, the number of different model types, and the total number of units to be assembled. In almost all cases, at least one of the heuristics found either the optimum or the best available solution. Computation times were quite reasonable for the heuristics, but grew exponentially for branch and bound. In general, it was only possible to verify optimality on problems with less-than-or-equal-to 20 units.
Computer-Aided Design and Computer-Aided Manufacturing technology is being implemented in the U.S. Navy's Arleigh Burke (DDG-51) Class Aegis Destroyer program. Under the Navy's direction, the DDG-51 class cons...
Computer-Aided Design and Computer-Aided Manufacturing technology is being implemented in the U.S. Navy's Arleigh Burke (DDG-51) Class Aegis Destroyer program. Under the Navy's direction, the DDG-51 class construction yards are aggressively pursuing the transition to CAD-based design, construction and life cycle support. Through the CAD initiative, acquisition costs can be reduced without reduction of ships' capability. Building a three dimensional (3D) computer generated model of the ship prior to construction will facilitate the identification and resolution of interference and interface problems that would otherwise remain undetected until actual ship construction. The 3D database contains geometry and design data to support system design and concurrent engineering and is exchanged electronically between the construction yards. Detailed design drawings, fabrication sketches, and numerical control (NC) data are extracted directly from the database to support construction. At the completion of ship construction, as-built models will be provided to the planning yard for life cycle support.
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