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2nd International Congress on Ceramics, ICC 2008

作者： Acchar, W. Ramalho, E.G. Souza, F.B.M. Torquato, W.L. Department of Physics Federal University of Rio Grande Do Norte Natal-RN Brazil Pos-graduation Program of Mechanical Engineering Federal University of Rio Grande Do Norte Natal-RN Brazil Pos-graduation Program of Science and Materials Engineering Federal University of Rio Grande Do Norte Natal-RN Brazil

ISBN: (纸本)9788880800842

Ceramic porous structures are specially indicated for filters for molten metals, hot gases, thermal protection systems and heat exchangers, due their high permeability, good retention capacity, low density and high thermal insulation. This work describes the research carried out on mechanical properties of two different types of a commercial porous ceramic material (10 and 40 ppi). The ceramic material was characterized in terms of microstructural aspects, crystalline phases, density, porosity, strength and thermal shock behaviour. The results have indicated that the strength of the material remain practically constant, regardless of the temperature. The fracture analyses indicated that the fracture is normally caused by the presence of microcracks and also by the presence of a large amount of pores in the ceramic filaments.

关键词： Ceramic materials

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Analysis of A 2D cathodic protection system for a buried slender structure with the dual boundary element method

Analysis of A 2D cathodic protection system for a buried sle...

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European Congress on Computational Methods in Applied sciences and engineering, ECCOMAS 2004

作者： De Lacerda, Luiz A. De Oliveira, Paulo A. Lázaris, José Da Silva, José M. LACTEC - Institute of Technology for Development Materials Department Centro Politécnico Cx. P. 19067 Curitiba Brazil PPGMNE - Post-Graduate Program on Numerical Methods in Engineering UFPR - Federal University of Paraná Curitiba Brazil

In this paper a boundary element formulation is developed and used for the analysis of cathodic protection systems of buried slender structures, such as foundations of electric transmission line towers. The foundation is basically a truss structure and the slenderness of the pieces composing it, brings numerical difficulties into the classical boundary element method. To avoid this problem, the dual boundary element method is implemented: combination of standard and hypersingular integral equations to form a mathematically well-posed system. A simple experiment is carried out where a galvanized metallic sheet is buried alongside two Copper electrodes (anodes) in parallel, with the objective of simulating a two-dimensional problem. The soil resistivity properties are measured along the depth and the non-linear polarization curves describing the relation between the current density and the electrochemical potential at the metallic sheet is investigated. Two situations are analysed: a) current is injected into the ground through both electrodes;b) current is injected through only one of the electrodes. In the numerical implementation, the soil is modeled as a homogeneous layered half-space with a different property for each layer. The validity of the proposed dual approach is discussed and compared with the measurements of potential at the ground surface.

关键词： Boundary element method

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Abstracts of papers presented at the 14th conference of the Weed science Society of Israel Abstracts of papers presented at the international conference on controlled atmosphere and fumigation (CAF) in stored products Abstracts of papers presented at the joint international conference of FAOPMA — CEPA on pest control in the 21st century Abstracts of papers presented at the 2nd international Agro-Ecology Symposium on integrated pest management: from the drawing board to the market

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Phytoparasitica 1996年第3期24卷 199-265页

作者： E. Yogev M. Berson Y. Benyamini Y. Sheinboim T. Lev-Ran A. Bahat Y. Barkai Y. Gatti M. Zaidan O. Barazani Y. Boshvize S. Graph U. Luchinsky T. Blumenfeld Y. Kleifeld G. Herzlinger H. Bucsbaum S. Golan T. Chilf R. Aly Y. Ohali A. Ovadia Y. Chachlon H. Yovel Y. Tesler G. Colodney A. Nir S. Zarka A. Tal B. Rubin T. Yaacoby Y. Alon Y. Kedar Orit Ben-Zvi Assaraf O. Shainberg H. D. Rabinowitch E. Tel-Or Y. Goldwasser D. M. Joel D. Plakhine V. Portnoy G. Tzuri N. Katzir Dalia Losner-Goshen A. M. Mayer R. Jacobsohn Z. Tanaami H. Eisenberg Ziva Amsellem Z. Kernyi L. Hornok J. Gressel Adiva Shomer-Ilan Ela Nir Daphna Michaeli V. Kampel A. Warshawsky M. Yogev M. Negbi J. Hershenhorn Y. Lavan T. Hilf M. Horowitz M. Cohen I. Hirsch A. Veneziani S. T. Conyers C. H. Bell Ana C. Sá-Fischer C. S. Adler Ch. Reichmuth P. W. Flinn D. W. Hagstrum G. N. Mbata R. G. Winks Elisabeth A. Hyne M. Q. Chaudhry A. D. MacNicoll N. R. Price M. Schöller J. -F. Dugast R. Plarre S. Navarro E. J. Donahaye R. Diaz Miriam Rindner A. Azrieli P. Trematerra F. Fontana M. Mancini Ailsa D. Hocking Marta H. Taniwaki J. Lacey A. Hamer N. Magan N. Paster F. M. Caliboso D. G. Alvindia G. C. Sabio M. T. dela Cruz Okky Setyawati Dharmaputra A. S. R. Putri M. Sidik Eleni Papademetriou A. Varnava C. Mouskos M. A. Malek B. Parveen K. A. Dzisi W. O. Ellis Ana Maria Estevez Ljubica Galletti T. Fichet E. Oteiza L. A. Lizana M. X. Gonzalez B. Yakobson Y. Slavezky H. Ephrati El-H. Bartaly R. K. Kashyap M. Gupta W. L. Kashyap B. S. Dahiya A. K. Dash J. R. Rangaswamy R. D. Shroff D. S. Jayas W. E. Muir N. D. G. White L Gaye Weller J. E. van S. Graver Wu-Kang Peng M. Bengston E. Alip C. Reed J. G. Leesch G. F. Knapp G. F. Russell L. B. Llewellin Ch. Ulrichs H. J. Banks P. C. Annis R. Allanson R. Tauscher K. Westphal S. Mohan M. Gopalan P. C. Sumdarababu V. V. Sree Narayanan Sabine Prozell G. Ziegleder B. Schartmann R. Matissek J. Kraus D. Gerard S. Rogg W. Raemann R. F. Ryan Ya-Nan Wang R. T. Noyes P. Kenkel J. T. Criswell G. W. Cuperus C. J. Waterford C. P. Whittle L. Be Luxembourg Chemicals and Agriculture Ltd. Tel Aviv Israel Agrochemicals Dept. Milchan Bros. Ltd. Ramat Gan Israel Extension Service Ministry of Agriculture Zefat Mevo Hamma Ramat HaGolan Israel Dept. of Weed Science ARO Newe Ya’ar Research Center Haifa Israel Agrochemicals Department Milchan Bros. Ltd. Ramat Gan Israel Tarsis-Agrichem Tel Aviv Israel Weed Control Co. Ltd. Bet Dagan Israel Dept. of Field Crops Vegetables and Genetics The Hebrew University of Jerusalem Faculty of Agriculture Rehovot Israel Plant Protection and Inspection Services Ministry of Agriculture Bet Dagan 50250 Agan Chemical Manufacturers Ltd. Ashdod Israel Dept. of Field Crops Vegetables and Genetics Rehovot Dept. of Agricultural Botany The Hebrew University of Jerusalem Faculty of Agriculture Rehovot Israel Dept. of Weed Science ARO Newe Ya’ar Research Center Haifa Dept. of Botany The Hebrew University of Jerusalem Jerusalem Israel Dept. of Vegetable Crops ARO The Volcani Center Bet Dagan Israel Dept. of Plant Genetics Weizmann Institute of Science Rehovot Israel Inst. for Plant Science Agricultural Biotechnology Center Gödöllö Hungary Dept. of Botany Tel-Aviv University Tel Aviv Israel Dept. of Plant Genetics The Weizmann Institute of Science Rehovot Israel Dept. of Organic Chemistry The Weizmann Institute of Science Rehovot Israel Dept. of Ornamental Horticulture ARO The Volcani Center Bet Dagan Israel Weed Control Co. Ltd. Bet Dagan Chem-Nir Ltd. Kefar Shemaryahu Tiveon-Chem Co. Haifa Israel Central Science Laboratory Ministry of Agriculture Fisheries and Food Slough Berks UK Federal Biological Research Centre for Agriculture and Forestry Inst. for Stored Product Protection Berlin Germany USDA-ARS Grain Marketing and Production Research Center Manhattan USA School of Biological Sciences Abia State University Uturu Nigeria CSIRO Division of Entomology SCMC Nambour CSIRO Division of Entomology Canberra Australia DowElanco Europe Letcombe Laboratory L

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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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Vulcanization influence on TSD currents and wettability of room temperature vulcanized silicone rubber hv insulator coatings

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European Transactions on Electrical Power 1993年第5期3卷 367-373页

作者： Gubanski, S.M. Wang, M.‐S.E. Dr. Stanislaw Gubanski (1950) received his M.Sc. (High-Voltage Engineering) and Ph.D. (Materials Science) degrees from the Technical University of Wroclaw/Poland in 1973 and 1976 respectively. He has worked as a research fellow at the University College of North Wales at Bangor/UK and then as a senior lecturer at the Technical University of Wroclaw/Poland. In the meantime he spent two years at the Federal University of Technology Bauchi/Nigeria and also worked as a guest researcher at the Chalmers University of Technology Göteborg/Sweden. At present he is Associate Professor at the Department of Electrical Plant Engineering of Royal Institute of Technology at Stockholm/Sweden. His major field of interest includes aging processes in electrical insulation and their diagnostics. (Royal Institute of Technology Department of Electrical Plant Engineering S-10044 Stockholm/Sweden T +468/790 7775 Fax +468/2052 68) Dr. Min-Sheng Edward Wang (1964) is agraduate of Xi'an Jiaotong University/China (B.Sc 1984. M.Eng. 1987 D.Eng. 1991) in Electricai Engineering. He worked as a research engineer in the National Key Laboratory of Electrical Insulation in China from 1987 to 1991 and also as a guest researcher at the Electrical Power Research Centre at the Royal Institute of Technology at Stockholm/Sweden 1991 to 1992. He is currently a post-doc research fellow involved in the field of conducting polymers at the Institute Physics and Chemistry of Silo Carlos University of São Paulo/Brazil. His research interests mainly focus on the influences of structure and morphology on the electrical properties of polymeric dielectrics. (University of São Paulo Instititue of Physics and Chemistry Dept. of Physics and Materials Science Av. Dr. Carlos Botelho 1465 BR-13560 São Paulo/Brazil T +551 62/71 53 65 Fax +551 62/71 36 16)

Thermally Stimulated Depolarization (TSD) current spectra and surface wettabilities, represented by contact angles, i. e. the advancing angle and the receding angle, were measured on two types of high voltage room temperature vulcanized silicone rubber coatings during their vulcanization processes at room (25°C, 80 % RH) and elevated (70°C, 80 % RH) temperatures. Results show increases in the material hydrophobi‐cities with the vulcanization degree until their stabilized values are reached. Compared with the room temperature vulcanization, the elevated temperature speeds up stabilization processes of the contact angles and of the TSD spectra. Variations of the contact angle seem to be closely related with changes of the TSD peaks. In most of the cases, the contact‐angle increase is accompanied by either the TSD peak‐height decrease or the peak‐temperature increase. Copyright © 1993 John Wiley & Sons, Ltd.

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Effects of aging on polyimide: a model for dielectric behavior (of relative humidity sensors)

Effects of aging on polyimide: a model for dielectric behavi...

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International Conference on Solid State Sensors and Actuators (TRANSDUCERS)

作者： A.R.K. Ralston M.C. Buncick D.D. Denton T.E. Boltshauser J.M. Funk H.P. Baltes Department of Electrical and Computer Engineering and Materials Science Program University of Wisconsin Madison Madison WI USA Physical Electronics Laboratory Swiss Federal Institute of Technology Zurich Switzerland

Quantifying the effect of moisture on the electrical properties of thin dielectric films requires the use of a model that takes into account the geometry of the test structure and the dielectric properties of the air layer above the device. Using this approach, it was found that the electrical properties of dry PI (polyimide) do not change substantially after six weeks of aging at 85 degrees C/85% RH (relative humidity). The dielectric permittivity of PI as a function of %RH increased with aging for excitation frequencies between 12 Hz and 100 kHz. This increase is correlated with observed changes in the surface chemistry of the aged PI film. Shifts in ESCA peak intensities indicate oxidation of the PI surface and deimidization with aging. Possible mechanisms for the observed changes in dielectric properties with aging include a change in the morphology of the bulk PI, resulting in a decreased surface to volume ratio, increased water absorption, a change in the interaction of absorbed water with the PI matrix, and dielectric interfacial effects.< >

关键词： Aging Polyimides Surface morphology Water Moisture Dielectric films Solid modeling Geometry Testing Dielectric devices

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FLAMMABILITY AND TOXICITY OF COMPOSITE-materials FOR MARINE VEHICLES

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NAVAL ENGINEERS JOURNAL 1990年第5期102卷 45-54页

作者： SEVART, JL GRIFFIN, OH GURDAL, Z WARNER, GA Jeffrey L. Sevart:is a native of Kansas and a 1985 graduate of Kansas State University with a B.S. in mechanical engineering (magna cum laude). After working as a stress analysis engineer at Boeing Military Airplane Company in Wichita Kans. he attended Virginia Polytechnic Institute and State University and received an M.S. in engineering mechanics in February 1988. He currently resides in Akron Ohio working as a research engineer in tire composites research at The Goodyear Tire and Rubber Company. O. Hayden Griffin Jr.:received his B.S. and M.S. in mechanical engineering from Texas Tech University in 1970 and 1971 respectively. He received his Ph.D. in engineering mechanics from Virginia Polytechnic Institute and State University in 1980. Prior to joining the faculty of Virginia Polytechnic Institute and State University as associate professor of engineering science and mechanics in September 1985 he was employed at the U.S. Naval Surface Warfare Center (Dahlgren Virginia) BF Goodrich Tire Group (Akron Ohio) the Bendix Advanced Technology Center (Columbia Maryland) and the Johns Hopkins University Applied Physics Laboratory (Laurel Maryland). He is currently an associate director of the Virginia Institute for Material Systems. He is a registered professional engineer in Virginia and is a member of the American Society of Mechanical Engineers and the American Society for Composites. Zafer Gürdal:received his M.S. in mechanical and aerospace engineering from Illinois Institute of Technology in 1981 and his Ph.D. in aerospace engineering from Virginia Polytechnic Institute and State University in 1985. He worked as a research associate in the Aerospace and Ocean Engineering Department at Virginia Tech before joining the Engineering Science and Mechanics Department as an assistant professor in September 1985. Professor Gürdal's research interests include: composite structures failure mechanics of composites structural optimization and damage tolerant design. He is a member of the American Institute

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.

关键词： Composite materials

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