Nitrate levels in the ground water of the Central Valley of Costa Rica have increased in relation to the past. Previous studies determined that the unsewered sanitation systems in the recharge areas are the main sourc...
Nitrate levels in the ground water of the Central Valley of Costa Rica have increased in relation to the past. Previous studies determined that the unsewered sanitation systems in the recharge areas are the main source of nitrogen. Calculations are made in this study to estimate the maximum population density allowable without improved sewage systems in order to keep the nitrogen levels in ground water below the World Health Organization (WHO) criteria. Results were achieved employing a mass balance that involved the concentration and rate of domestic effluents and the flow rate in the aquifer, as well as an estimation of the effects caused by the agricultural activity. It was concluded that, in general terms, the population density must not exceed 45 inhabitants per hectare. Otherwise, sewage systems and treatment plants are necessary. These conclusions provide a basis for urban growth planning, which will protect ground water quality. The method used in this case should apply to similar situations.
作者：
SIMS, RCSIMS, JLUtah State University
Department of Civil and Environmental Engineering and Utah Water Research Laboratory Logan UT 84322 Professor and Head of the Division of Environmental Engineering at Utah State University. He holds degrees in biology (B.S.)
environmental chemistry and biology (M.S.) environmental engineering (M.S.) and biological and agricultural engineering (Ph.D). He has worked as Director of the International Program in Industrial Development Chapel Hill NC as Supervisor of the Environmental Control Laboratory for Mobay Chemical Corporation Charleston SC and as environmental engineer with Research Triangle Institute NC. Dr. Sims currently is involved in teaching research and technology transfer in the area of contaminated soil characterization and remediation. Research Assistant Professor in the Division of Environmental Engineering at Utah State University. She holds degrees in biology (B.S.)
environmental chemistry and biology (M.S.) and soil science (M.S.). She has held positions as an Associate in a private consulting firm in Raleigh NC and as Chairperson of the on-site wastewater disposal committee of the State of Utah. Judith Sims is currently involved in teaching research and technology transfer in the area of contaminated soil characterization and remediation.
This study presents a general two-part analysis procedure for the investigation of snap load behavior of marine cable systems in regular seas. A simple dynamic model of a package suspended from a multi-cable configura...
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This study presents a general two-part analysis procedure for the investigation of snap load behavior of marine cable systems in regular seas. A simple dynamic model of a package suspended from a multi-cable configuration is presented. It is used as the basis to develop dimensionless curves which are useful for the preliminary assessment of the susceptibility of a design to snap load behavior. For cases where this model indicates a strong possibility of snap load behavior, the designer must use a more complex dynamic model. A deepwater marine cable system, similar to that designed for scientific coring studies of the Mid-Atlantic Ridge, is used as the basis for the illustrative examples. The packages to be placed on the seafloor had complicated geometrical shapes with openings through which fluid could pass. Experiments to determine the hydrodynamic added-mass were performed and the results compared to common hydrodynamic approximations. The numerical examples illustrate the sensitivity of these dynamic response predictions to hydrodynamic approximations, ship heading and design wave conditions. They also show that it may be possible to avoid snap loading through proper design, and that if snap loading occurs it is possible to mitigate its effects without complete failure of the system.
ABSTRACT: The production of a documentary video in a graduate seminar offers advantages over the traditional term paper. These advantages derive from the nature of the videotape medium. The most distinct difference be...
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engineering processes, for the integration of topside electromagnetic environment and EM subsystems performance engineering into the mainstream of surface ship engineering, are presented and discussed in this paper. T...
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engineering processes, for the integration of topside electromagnetic environment and EM subsystems performance engineering into the mainstream of surface ship engineering, are presented and discussed in this paper. The engineering procedures and tasks pertaining to ship EM systems engineering must be tailored to the several stages of the life cycle, but all contain a core of activities covering performance-based EM suite selection and topside arrangement design, which is based on EM environment and performance vs. requirements analysis. These core activities are presented and discussed as they apply to all life cycle design stages. Several recent fleet EMI problems are briefly discussed for the insight they provide relative to the EM portions of the current design process, and conclusions regarding how the proposed procedures address current deficiencies are included.
The structural design of a ship's section is a complicated, repetitive and time consuming task. With the advent of new technology, high speed computers have enabled the ship designer to accomplish in a matter of s...
The structural design of a ship's section is a complicated, repetitive and time consuming task. With the advent of new technology, high speed computers have enabled the ship designer to accomplish in a matter of seconds what would formerly take days to accomplish by hand. The Structural Synthesis Design program (SSDP) is a N avy developed computer-aided design tool which is used to design (or to analyze) the longitudinal scantlings for a variety of ship cross sections, consisting of any practical combinations of decks, platforms, bulkheads and materials, i.e., various steel and aluminum alloys. The final hull section design will have the lowest practical weight for the chosen geometric configuration, structural arrangements, and imposed loadings. The scantling developed by the program will satisfy all U.S. N avy ship structural design criteria. An explanation of the objective and design elements of N avy ship structures is included. The rationale behind the SSDP design philosophy is developed along with the significant program capabilities. In an attempt to highlight the influence of automated design procedures on the current naval ship design process, the effect of the SSDP on the DDG 51 destroyer structural development is addressed.
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