检索结果-南通市图书馆

An Efficient Approach for the Numerical Identification of R and L Parameters of High Frequency Multi-winding Transformers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy and Power Engineering 2011年第7期5卷 641-650页

作者： Z. De Greve o. Deblecker J. Lobry Power Electrical Engineering Department Faculty of Engineering University of Mons Mons 7000 Belgium Belgian Fund for Researeh F.R.S/FNRS Brussels 1000 Belgium

In this paper, equivalent circuits for high frequency multi-winding magnetic components are derived from finite element （FE） computations. Lumped parameter models are first presented, based on previously published work. All parameters of these circuits can be interpreted as the results of open and short-circuit tests on the transformer. Based on this consideration, numerical procedures are then proposed to derive frequency-dependent lumped parameters from FE simulations. By using an adequate formulation, parameters are directly obtained from the FE model degrees of freedom, without performing any volume integration in post-processing, which can be source of numerical errors. In this contribution, attention is paid on the modeling of magnetic coupling using inductances, and dissipative effects （winding and core losses） using resistances. The impact of conductor eddy currents on the circuit parameters is moreover studied in details. Instead of an analysis of the impact conductor eddy currents may have on the circuit parameters is moreover carried through.

关键词： Multi-winding transformer finite elements lumped parameter circuits.

从国际视角看我国的药品定价、补偿和可及性问题

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国医院管理 2007年第5期27卷 10-12页

作者：陈英耀 Stuart o.Schweitzer 复旦大学公共卫生学院上海200032 加州大学洛杉矶分校公共卫生学院

随着药品费用的快速增长,药品政策在我国显得愈发重要。药品政策出台的目的是有效控制药品费用,而截至目前为止,这些政策的实施效果仍不尽如人意。通过比较研究的方法,对我国药品定价、补偿和可及性等问题提出一些政策建议。这些建议不... 详细信息

随着药品费用的快速增长,药品政策在我国显得愈发重要。药品政策出台的目的是有效控制药品费用,而截至目前为止,这些政策的实施效果仍不尽如人意。通过比较研究的方法,对我国药品定价、补偿和可及性等问题提出一些政策建议。这些建议不仅是针对药品费用问题,更多的是针对正在不断增长的卫生费用问题。

关键词：药品定价补偿可及

Performance Evaluation of Waste Stabilisation Ponds

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Water Resource and Protection 2018年第11期10卷 1129-1147页

作者： o. P. Gopolang M. W. Letshwenyo Department of Civil and Environmental Engineering Faculty of Engineering and Technology Botswana International University of Science and Technology Palapye Botswana

Waste stabilisation pond system has been used more especially in developing countries for sewage treatment. The objective of this study was to investigate the hydraulic and performance efficiency of Palapye waste stabilisation ponds. The hydraulic efficiency was evaluated through drogue, pond geometry and sludge accumulation assessment. The performance efficiency was evaluated through periodic sampling and analysis of physiochemical and bacteriological parameters of individual units and of the system as a whole. Except for the maturation ponds, the depth of the anaerobic pond had reduced from 4 m to 0.45 m, for facultative ponds from 2.0 m to a range of 0.52 m - 0.91 m. The design hydraulic retention time of the system had reduced from 20 days to 7.1 days. The concentration of some physiochemical parameters in the effluent was 305 mg·L-1, 277 Nephelometric Turbidity Units (NTU), 204 mg·L-1, 156 mg·L-1, 110 mg·L-1, and 15 mg·L-1 being total suspended solids, turbidity, nitrates, chemical oxygen demand, biochemical oxygen demand and phosphate respectively. These values were more than the standard limits of the country. Effluent total coliforms concentration was 3.6 log units and within the threshold of 4.3 log units, faecal coliforms concentration was 3.5 log units, slightly higher than the threshold of 3 log units. Though Escherichia coli have no limits for discharge into other environments, the concentration in the effluent was reasonable at 2.5 log units and also within irrigation limit of 3 log counts. Palapye wastewater treatment system hydraulic efficiency is lower than the design criterion. The system was overall poor in physiochemical parameters removal but better in bacteriological removal.

关键词： Hydraulic Efficiency Waste Stabilisation Ponds Length to Width Ratio Pond Geometry

Adsorption，oxidation and Complexation of Water－So－Inble organic Snbstances in Soils

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 1995年第2期5卷 171-178页

作者： DING CHANG-PUInstitute of Sozl Sczence, Academza Sznica, P. o. Boz 82i, Nalzjzng 210008 (China) )

A greater part of water-solnble organic substances, accounting for 6070To of the total, could be adsorbedby soils, which included strongly and weekly reducing substances, positively and negatively charged substancesand substances containing amido. There existed a tendency of decrease in adsorption of the negativelycharged organic substances by the soil from South China to North China, with expression as Coulombianadsorption. A simultaneous reduction of iron and manganese appeared with clear voltammetric behavioursupon oxidation of water-soluble organic substances. Complexation of organic ligands with ferrons iron andmanganous manganese was proved by differential pulse voltammetric method, with disappearance of oxidationpeaks of ferrous iron and manganous manganese at 0.00 V and 0.35 V and occurrence of Fe`+-complex andMn￣2+ -complex at 0.75 V and 1.2 V respectively, whose peak potentials shifted backward.

关键词： adsorption complexation oxidation voltammetric behaviour water-solube organic substances

A Malicious and Malfunctioning Node Detection Scheme for Wireless Sensor Networks

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Wireless Sensor Network 2012年第3期4卷 84-90页

作者： Seo Hyun oh Chan o. Hong Yoon Hwa Choi Department of Computer Engineering Hongik University Seoul Korea

Wireless sensor networks are often used to monitor physical and environmental conditions in various regions where human access is limited. Due to limited resources and deployment in hostile environment, they are vulnerable to faults and malicious attacks. The sensor nodes affected or compromised can send erroneous data or misleading reports to base station. Hence identifying malicious and faulty nodes in an accurate and timely manner is important to provide reliable functioning of the networks. In this paper, we present a malicious and malfunctioning node detection scheme using dual-weighted trust evaluation in a hierarchical sensor network. Malicious nodes are effectively detected in the presence of natural faults and noise without sacrificing fault-free nodes. Simulation results show that the proposed scheme outperforms some existing schemes in terms of mis-detection rate and event detection accuracy, while maintaining comparable performance in malicious node detection rate and false alarm rate.

关键词： Wireless Sensor Networks Fault Detection Malicious Node Detection

Protection against Chemical Warfare Agents and Biological Threats Using Metal−organic Frameworks as Active Layers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Accounts of Materials Research 2023年第2期4卷 168-179页

作者： Kaikai Ma Yuk Ha Cheung Kent o.Kirlikovali Xiaoliang Wang Timur Islamoglu John H.Xin omar K.Farha International Institute for Nanotechnology Institute for Sustainability and Energy at Northwesternand Department of ChemistryNorthwestern UniversityEvanstonIllinois 60208United States Research Centre for Smart Wearable Technology School of Fashion and TextilesThe Hong Kong Polytechnic UniversityKowloon 999077 Hong Kong SARP.R.China

The SARS-CoV-2 pandemic outbreak and the unfortunate misuse of toxic chemical warfare agents(CWAs)highlight the importance of developing functional materials to protect against these chemical and pathogen ***−organic frameworks(MoFs),which comprise a tunable class of crystalline porous materials built from inorganic nodes and organic linkers,have emerged as a class of heterogeneous catalysts capable of rapid detoxification of multiple classes of these harmful chemical or biological *** particular,zirconium-based MoFs(Zr-MoFs)feature Lewis acidic nodes that serve as active sites for a wide range of catalytic reactions,including the hydrolysis of organophosphorus nerve agents within seconds in basic aqueous *** addition,postsynthetic modification of Zr-MoFs enables the release of active species capable of reacting with and deactivating harmful *** this impressive performance,utilizing Zr-MoFs in powder form is not practical for application in masks or protective *** address this challenge,our team sought to develop MoF/fiber composite systems that could be adapted for use under realistic operating conditions to protect civilians,military personnel,and first responders from harmful pathogens and chemical warfare *** the last several years,our group has designed and fabricated reactive and biocidal MoF/fiber composites that effectively capture and deactivate these toxic *** this Account,we describe the evolution of these porous and reactive MoF/fiber composites and focus on key design challenges and ***,we devised a scalable method for the integration of Zr-MoFs onto textile substrates using aqueous precursor solutions and without using pretreated textiles,highlighting the potential scalability of this *** beyond standard textiles,we also developed a microbial synthesis strategy to prepare hierarchically porous MoF/bacterial cellulose nanofiber composite sponges that can both captu

关键词： composites protective porous

The Refractive Effect of k-Factor on Radio Propagation over Lokoja, Nigeria

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Electronic & Information Systems 2023年第1期5卷 45-50页

作者： Akinsanmi Akinbolati Florence N.Ikechiamaka Akogwu o.Isaiah Department of Physics Federal University Dutsin-Ma821101Nigeria

The effective earth radius factor(k-factor)has a refractive propagation effect on transmitted radio signals thus making its study necessary for the proper planning of terrestrial radio links and power *** study was carried out over the city of Lokoja,Nigeria,using ten years(2011 to 2020)atmospheric data of temperature,pressure and humidity both at the surface(12 m)and at 100 m *** data were retrieved from European Centre for Medium-Range Weather Forecasts(ECMWF)*** k-factor yearly variation follows the same trend with minimum and maximum values obtained during dry and wet season months *** addition,the highest mean value of 1.00042 was recorded in the month of August while the lowest value of 1.00040 was recorded in the month of January with an overall mean value of *** value is less than the recommended standard of 1.33 by *** propagation effect corresponding to kon of this on radio wave propagation,especially terrestrial communications is that transmitted wireless signal is prone to *** can be mitigated through an effective power budget:Choice of transmitting antenna’s height and gain,so as to improve the Quality of Service over the study area.

关键词： Effective earth radius factor(k-factor) Refractive effect Terrestrial radio link Radio signal Power budget

Fekete-Szego Estimate for a Class of Starlike Functions Involving Certain Analytic Multiplier Transform

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Applied Mathematics and Physics 2020年第3期8卷 519-526页

作者： Deborah olufunmialyo Makinde A.S.oyekunle T.o.opoola Department of Mathematics Obafemi Awolowo UniversityIle-IfeNigeria Department of Mathematics University of IlorinIlorinNigeria

In this paper, we investigated the coefficient estimates and the Fekete-Szegö?problem for the subclass of analytic univalent functions involving the linear transformation Dsα,β,γf for the normalized analytic functi... 详细信息

关键词： Analytic Univalent Starlike Linear Transformation Coefficient Estimates Fekete-Szego Inequality

A model of the formation and development of ocean shear wave

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta oceanologica Sinica 1994年第3期13卷 345-359页

作者： Qiao Fangli and Zhang Qinghua(First Institute of oceanography,state oceanic Administration,P.o.Box 98,Qingdao 266003,China)

From quasi-geostrophic vorticity equation, we simulate the formation of ocean shear wave in western boundary strong current area with the pseudospectral method, and idealize the initial velocity into hyperbolictangent velocity profile, with the unsteady little perturbation developed by means of getting energy from meanmotion. The change of isovorticity shows two vortexes merging or splitting between them. The evolving processof material lines reflects cold water's invading and warm water's turning, which is agreeable to satellite *** effect makes a new energy distribution in all kinds of motion scale. one important phenomenon is that Reynolds stress will change its sign when the perturbation amplitude is large enough.

关键词： Shear wave pseudospectral method large eddy simulation