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Proceedings of the Third International Conference on Discrete Element Methods;Numerical Modeling of Discontinua

作者： Boutt, David McPherson, Brian Dept. of Earth and Environ. Sci. Hydrology Program New Mexico Tech 801 Leroy Place Socorro NM 87801 United States

The role of particle packing in modelling rock mechanical behavior using discrete elements was discussed. A common approach to calibrate discrete element models of rock is to hold particle packing constant while contact parameters are changed to match observed macroscopic mechanical behavior. Therefore, the mechanical properties of the DEM assembly depend on the packing method.

关键词： Finite difference method

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The challenge of faecal sludge management in urban areas - Strategies, regulations and treatment options

The challenge of faecal sludge management in urban areas - S...

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作者： Ingallinella, A.M. Sanguinetti, G. Koottatep, T. Montangero, A. Strauss, M. 2000 Rosario Santa Fé Argentina Urban Environ. Eng./Mgmt. Program Sch. of Environ. Res. and Devmt. Asian Institute of Technology P.O. Box 4 Klong Laung Pathumthani 12120 Thailand Swiss Fed. Inst. for Environ. Sci. Dept. of Water and Sanitation Dev. P.O. Box 611 CH-Duebendorf Switzerland

In urban centres of industrialising countries, the majority of houses are served by on-site sanitation systems such as septic tanks and unsewered toilets. The faecal sludges (FS) collected from these systems are usually discharged untreated into the urban and peri-urban environ.ent, posing great risks to water resources and to public health. Contrary to wastewater management, the development of strategies to cope with faecal sludges, adapted to the conditions prevailing in developing countries, have long been neglected. The authors described the current situation and discuss selected issues of FS management. A proposal is made for a rational setting of sludge quality or treatment standards in economically emerging countries. The authors stipulate that regulatory setting should take into account local economic, institutional and technical conditions. Defining suitable treatment options as critical control points in securing adequate sludge quality is better than setting and relying on numerical sludge quality standards. A separate section is devoted to the practice and to regulatory aspects of (faecal) sludge use in Argentina. An overview of treatment options, which may prove sustainable in less industrialized countries is provided. Planted sludge drying beds are one of these options. It has been piloted in Thailand for four years and details on its performance and operation are presented along with data on the hygienic quality of treated biosolids.

关键词： Wastewater treatment

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Transport and transformation processes affecting organophosphorus insecticide loads in surface runoff

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ACS Symposium Series 2002年 806卷 164-185页

作者： Pedersen, Joel A. Suffet, I.H. Environ. Sci. and Eng. Program University of California Los Angeles CA 90095 United States

Surface runoff from agricultural fields represents an important route for the introduction of organophosphorus insecticides into aquatic ecosystems. Concentrations in surface runoff reflect the summation of numerous physical, chemical and microbial processes that alter the amount of organophosphorus compounds available for transport in overland flow and shallow interflow. Volatilization and transformation processes serve to reduce the amount of parent compound available for transport in runoff. Sorption of organophosphorus insecticides to inorganic and organic soil components determines their rate of transfer from soil solution to overland flow and their mode of transport in surface runoff. Dissolved insecticides are transferred into overland flow by molecular diffusion, raindrop impact induced turbulent diffusion and shear stress induced mass transfer. Sorbed insecticides are mobilized and transported by soil erosion processes. Processes controlling insecticide flux from the soil matrix into overland flow influence the magnitude and temporal variability of organophosphorus insecticide loads in surface runoff from cultivated lands.

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An Application of Semiconductor Sensors to Real Time, In-Situ Rain Gauges

An Application of Semiconductor Sensors to Real Time, In-Sit...

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Hydraulic Measurements and Experimental Methods 2002

作者： Lee, Sangsuk Schwartz, Franklin W. Kim, Jun Young Moon, Jong H. Environ. Science Graduate Program Ohio State University Department of Mechanical Engineering University of Illinois Urbana-Champaign Dept. of Mat. Sci. and Engineering Chonnam National University Kwangju Korea Republic of 223 Mendenhall Laboratory 125 S. Oval Mall Columbus OH 43210

ISBN: (纸本)0784406553

This paper presents results in an effort to develop an improved semiconductor rain gauge. A key feature of the rain gauge described herein is the use of piezoelectric ceramic elements to produce real time and direct signals. Another feature of the device is the ability to use the piezoelectric elements as sensors. A methodology is presented for analyzing the feasibility of using a semiconductor device as a key component of the rain gauge. A piezoelectric semiconductor, lead zirconate titanate (PZT) ceramic device, was investigated for the potential application. PZT discs were prepared through a modified sintering method to provide the optimal thickness and diameter for the device, which are key factors in controlling the resonance frequency. The microstructure of the device was determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The device was examined for its optimal resonance frequency using a laser scanning vibrometer in the time domain. The voltages induced by water drops were measured at the optimal resonance frequency with a spectrum analyzer. The voltage fluctuated according to the size of the water drops. This result suggests the PZT device could function as an alternative to the current rain gauges. The experimental results also indicate that even a single rain drop could be measured in real time using the PZT device. Separation of overlapping signals induced by rain drops falling within the relaxation time (10 ms) of the device is a problem that we are now examining, along with practical issues of the remote use of the device with a data logger.

关键词： Semiconductor devices

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Evaluation of the adsorption process for the removal of methyl tert-butyl ether from drinking water

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ACS Symposium Series 2002年 799卷 208-225页

作者： Shih, Tom C. Wangpaichitr, Medhi Suffet, Mel Environ. Sci. and Eng. Program School of Public Health Univ. of California at Los Angeles Los Angeles CA 90095-1772 United States Dept. of Environ. Health Sciences School of Public Health Univ. of California at Los Angeles Los Angeles CA 90095-1772 United States

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Laptops in the classroom: Do they make a difference?

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Journal of engineering Education 2002年第4期91卷 397-401页

作者： Kolar, Randall L. Sabatini, David A. Fink, L. Dee Sch. of Civ. Eng. and Environ. Sci. University of Oklahoma Instructional Development Program Department of Geography University of Oklahoma Civ. and Environ. Eng. Science University of Oklahoma 202 W. Boyd St. Norman OK 73019-1024 Instructional Development Program University of Oklahoma Hester Hall Norman OK 73019

In 1996 the College of engineering at the University of Oklahoma started to require all incoming students to have a laptop computer equipped with a wireless Internet card. Because of a pilot study and a voluntary phase-in over the first two years, two groups of students moved through the curriculum - those with and those without laptops. During 1998 and 1999, when these students entered their junior year, we offered two sections of a third-year water resources course: one for students who owned laptops and one "traditional" section for those who did not own laptops. We assessed student performance to evaluate if the laptops helped improve student learning. Although not a perfectly controlled experiment (i.e., the student groups were different), the two sections were uniform in terms of course content and assignments. Because of their inherently large standard deviations, class metrics (grades) are not conclusive, but they do indicate that the laptop students performed slightly better than the non-laptop students, even though their composite grade point average entering the course was lower. Evaluations do clearly show that, when the technology is used properly and when class time is not spent resolving technical problems, the laptop students had a more positive learning experience.

关键词： Laptop computers

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environ.ental health criteria 227: Fluorides

Environmental Health Criteria

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environ.ental Health Criteria 2002年第227期 i-xx+1-268页

作者： Liteplo, R. Howe, P. Malcolm, Heath Aggett, Peter Belmar, Roberto Bucher, John Camargo, Julio Cauley, Jane Ekstrand, Jan Howe, Paul Karthikeyan, Gopalakrishnan Kierdorf, Uwe Kurttio, Päivi Liteplo, Robert Nishikawa, Akiyoshi Stevens, Daryl Vineis, Paolo Yinlong, Jin Health Canada Ottawa Ont. Canada Centre for Ecology and Hydrology Cambridgeshire United Kingdom Lancashire Postgrad. Sch. Med./Hlth. University of Central Lancashire Preston Lancashire United Kingdom Environmental Health Division Ministry of Health Santiago Chile Environmental Toxicology Program Natl. Inst. of Environ. Hlth. Sci. National Institutes of Health Research Triangle Park NC United States Ecology Department Faculty of Science University of Alcalá Madrid Spain Department of Epidemiology University of Pittsburgh Pittsburgh PA United States Department of Basic Oral Sciences Karolinska Institute Stockholm Sweden Centre for Ecology and Hydrology Monks Wood Abbots Ripton Huntingdon Cambridgeshire United Kingdom Department of Chemistry Gandhigram Rural Institute Gandhigram Tamil Nadu India Inst. of Gen. and Systematic Zoology Justus-Liebig-University of Giessen Giessen Germany Radiat. and Nuclear Safety Authority Helsinki Finland Existing Substances Division Bureau of Environmental Contaminants Health Canada Ottawa Ont. Canada Natl. Institute of Health Sciences Tokyo Japan Land/Water Cmw. Sci. Indust. R. O. Adelaide SA Australia Dept. Biomed. Sci. and Hum. Oncol. University of Torino Torino Italy Inst. of Environ. Hlth. and Eng. Chinese Acad. of Preventive Medicine Beijing China

This document focuses on environ.ental exposure to fluoride derived mostly from inorganic sources and its effects on humans, animals and other biota. Data on hydrogen fluoride, calcium fluoride, sodium fluoride, sulfur hexafluoride and silicofluorides are covered, as these compounds are considered to be the most relevant of the inorganic fluorides on the basis of quantities released to the environ.ent, environ.ental concentrations and toxicological effects on living organisms. 1.1 Identity, physical and chemical properties and analytical methods Hydrogen fluoride (HF) is a colourless, pungent liquid or gas that is highly soluble in organic solvents and in water, in which it forms hydrofluoric acid. Calcium fluoride (CaF2) is a colourless solid that is relatively insoluble in water and dilute acids and bases. Sodium fluoride (NaF) is a colourless to white solid that is moderately soluble in water. Sulfur hexafluoride (SF6) is a colourless, odourless, inert gas that is slightly soluble in water and readily soluble in ethanol and bases. The most common procedure used to quantify free fluoride anion is the fluoride ion-selective electrode. Microdiffusion techniques are considered to be the most accurate methods of sample preparation (i.e., liberation of free ionic fluoride from organic and inorganic complexes). 1.2 Sources of human and environ.ental exposure Fluorides are released into the environ.ent naturally through the weathering and dissolution of minerals, in emissions from volcanoes and in marine aerosols. Fluorides are also released into the environ.ent via coal combustion and process waters and waste from various industrial processes, including steel manufacture, primary aluminium, copper and nickel production, phosphate ore processing, phosphate fertilizer production and use, glass, brick and ceramic manufacturing, and glue and adhesive production. The use of fluoride-containing pesticides as well as the controlled fluoridation of drinking-water supplies also

关键词： Fluorine compounds

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Highly sensitive assay for anticholinesterase compounds using 96 well plate format

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ACS Symposium Series 2002年 806卷 289-305页

作者： Mishra, Nirankar N. Pedersen, Joel A. Rogers, Kim R. U.S. Environmental Protection Agency Natl. Exposure Research Laboratory Las Vegas NV 89119 United States U.S. Environmental Protection Agency San Francisco CA 94105-3901 United States Environ. Sci. and Eng. Program University of California Los Angeles CA 90095 United States

The rapid and sensitive detection of organophosphorus insecticides using a 96 well plate format is reported. Several features of this assay make it attractive for development as a laboratory-based or field screening assay. Acetylcholinesterase (AChE) was stabilized in a gelatin film. The remarkable properties of the dry immobilized AChE preparation include its stability to prolonged storage at room temperature as well as its stability to short term elevated temperatures (60 °C). The enzyme could be maintained in dry gel form for 365 days at room temperature without substantial loss of activity. The absorbance assay used to measure enzyme activity was evaluated using several solvent systems including water, phosphate buffer, hexane, methanol and ethanol. The microwell assay includes a procedure to oxidize less potent P=S organophosphorus compounds to their more inhibitory oxon forms. The use of this assay to analyze field samples contaminated with mixtures of organophosphorus insecticides is also reported.

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Energy burdens of conventional wholesale and retail portions of product life cycles

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Journal of Industrial Ecology 2002年第2期6卷 59-69页

作者： Norris, Gregory A. Della Croce, Filippo Jolliet, Olivier Harvard School of Public Health 401 Park Drive Boston MA 02115 United States Sylvatica North Berwick ME United States Environ. Sci./Engineering Program Harvard Univ. Sch. of Public Health Boston MA United States Complex Systems Research Center University of New Hampshire Durham NH United States Harvard Univ. Sch. of Public Health Boston MA United States EPFL Ecl. Polytech. Federale de Lausanne Lausanne Switzerland

E-commerce is often cited as offering the potential to reduce wholesale and retail burdens within product life cycles;however its potential impacts upon transport may be positive or negative. But the relative environ.ental importance of wholesale and retail trade and their intervening transportation links within product life cycles has not been generally characterized. The objective of this research was to assess the upstream (preusage) life-cycle energy burden shares associated with retail trade and wholesale trade using input-output life-cycle assessment (IO LCA) with a special focus on the electronic computers sector. According to our results, the physical transfers of products within the distribution phase play a minor role in terms of energy consumption compared with wholesaling and retailing. On the other hand, the supply chains of the wholesale and retail trade sectors can lead to energy consumption that is a significant share of the total preconsumer energy consumption for many products. Thus, where e-commerce circumvents wholesale and/or retail trade, it can have a major impact on total preconsumer energy consumption. As an example, for the electronic computers sector, retailing and wholesaling as a portion of distribution are responsible for 38% of the total energy consumption from production until purchase (cradle to gate), whereas transportation within the distribution phase corresponds to only 9%. Our analysis of more than 400 commodities in the United States showed that for the large majority of them, retailing and wholesaling account for appreciable shares of the total preconsumer energy burdens. Wholesaling and retailing should be included in LCA, and IO LCA is an effective tool for doing so.

关键词： Life cycle

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Developing and implementing an innovative first year program for 1000 students

Developing and implementing an innovative first year program...

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2001 ASEE Annual Conference and Exposition: Peppers, Papers, Pueblos and Professors

作者： Fentiman, Audeen W. Demel, John T. Freuler, Richard J. Gustafson, Robert J. Merrill, John A. College of Engineering Ohio State University Department of Engineering Graphics TX Department of Civil Engineering Outreach and Special Programs College of Engineering Interdisc. Environ. Sci. Grad. Prog. Aerosp. Eng. and Aviation Department College of Engineering Ohio State University Department of Food Engineering Introduction to Engineering Program Ohio State University

In the past decade, learning experiences for first year engineering students at Ohio State have evolved. This article provides an overview of that evolution with emphasis on the student experience in 2000. It will cover course topics, teaching staff, facilities, faculty development, assessment and feedback methodologies, and results to date. Two important factors in bringing about change were Ohio State's participation in the NSF-funded Gateway engineering Education Coalition and substantial support from the Dean's office. Many subjects briefly discussed in this paper will be covered in more detail in separate papers presented at this and other conferences.

关键词： Students

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