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11.
A systematic and straightforward procedure is developed for the synthesis and analysis of transformer-isolated power converters. The procedure can be used to determine the ranges of duty-ratio over which the transformer-isolated power converters of a given class can be operated without transformer saturation. The procedure can also be used to study the dependence of the power converter switch stresses on duty-ratios. This information is useful in the selection of the transformer-isolated power converter most suitable for a given application and in the design of this power converter with minimum switch stresses, high power density, and low cost 相似文献
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Zirconium(IV) tungstoiodophosphate has been synthesized under a variety of conditions. The most chemically and thermally stable
sample is prepared by adding a mixture of aqueous solutions of 0·5 mol L−1 sodium tungstate, potassium iodate and 1 mol L−1 orthophosphoric acid to aqueous solution of 0·1 mol L−1 zirconium(IV) oxychloride. Its ion exchange capacity for Na+ and K+ was found to be 2·20 and 2·35 meq g−1 dry exchanger, respectively. The material has been characterized on the basis of chemical composition, pH titration, Fourier
transform infrared spectroscopy (FTIR) and thermogravimetric analysis. The effect on the exchange capacity of drying the exchanger
at different temperatures has been studied. The analytical importance of the material has been established by quantitative
separation of Pb2+ from other metal ions. 相似文献
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Comparison evaluation of the methods of treatment was based on the analysis of the results of management of 347 patients with general purulent decompensated peritonitis with polyorganic insufficiency. The efficacy of closed drainage in 98 patients, continuous flow irrigation (dialysis) in 126, stage programmed irrigation and inspection of the abdominal cavity in 99, and open drainage in 24 patients was compared. The causes of peritonitis were: complications after acute surgical diseases (in 156 cases), in planned operations (59), and in obstetrical and gynecological diseases (132). Most of the patients were brought to the clinic from other hospitals because of unsuccessful treatment of peritonitis and absence of means for performing hemodialysis and management of polyorganic insufficiency. The incidence of the last-named reached 71.0 to 91.0% in the different groups of patients. In monotypic complex treatment, stage programmed irrigation was marked by a much lesser number of abscesses and other complications and a lower mortality (20.2%) as compared to flow irrigation (30.0%, closed drainage (27.5%), and open (laparostomy) treatment (37.5%). Despite the very serious contingent of patients, total mortality (27.0%) in the application of the indicated methods was quite low. 相似文献
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A rare case associated with congenital hematometrocolpos in a circumcised 13 years old Somalian girl is presented. Emphasis on proper history is highlighted. Mutilation caused by bad cultural practice of female circumcision which is although not a problem in Pakistan, is brought into notice for those who may be unaware of perineal appearance of a circumcised female and stitched over vagina. 相似文献
19.
H.U. Khan K.M. Agrawal M. Anwar S.P. Nautiyal B.S. Rawat 《Petroleum Science and Technology》1998,16(1):145-166
Lubricating oil base stocks differ greatly in their chemical composition and consequently in their physical properties and applications. Influence of waxes and various hydrocarbon type constituents viz saturates and aromatic components on the viscosity and shear stress as a function of temperature in different lube oil base stocks has been studied in the present paper. 相似文献
20.