technology trends in today's cooperative design environments are making it more and more important to monitor the network performance and ensure the network security. This paper describes the design and implementa...
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ISBN:
(纸本)184000025
technology trends in today's cooperative design environments are making it more and more important to monitor the network performance and ensure the network security. This paper describes the design and implementation of a distributed network traffic monitoring system based on embedded NetFlow hardware and software engines. The system architecture and design principles were introduced in the paper, some discussions were also presented about the NetFlow-based network monitoring technologies. The system had been successfully used to monitor highspeed campus networks at full wire speed without packet sampling in scenarios where commercial NetFlow collectors could not be used due to their limitations. Results show that this is an effective mechanism to identify, diagnose, and determine controls for network activities in CSCW environments and other network-based applications.
In 2003, a joint research project entitled "Nano and graded thermoelectric materials/Photovoltaic-thermoelectric-wind power generation" is established in cooperation among research institutes from Japan and ...
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ISBN:
(纸本)0878499709
In 2003, a joint research project entitled "Nano and graded thermoelectric materials/Photovoltaic-thermoelectric-wind power generation" is established in cooperation among research institutes from Japan and China. The major research institutes include statekeylaboratory of advancedtechnology for materialssynthesis and processing (Wuhan University of technology, China), Shanghai Institute of Ceramics (Chinese Academy of Sciences, China), statekeylaboratory of New Ceramics and Fine processing (Tsinghua University, China), Japan Aerospace Exploration Agency (JAXA, Japan) and Foundation for Promotion of Japanese Aerospace technology (JAST, Japan). The main aim of this project is to develop a photovoltaic-thermoelectric-wind power generation system with high efficiency solar energy conversion. The key works of the project include: (1) fabrication of high efficiency nano thermoelectric materials with a maximum figure of merit Z≥ 1.3;(2) design and fabrication of nano graded thermoelectric material/component with efficiency conversion larger than 12% for wide temperature range and (3) design and construction of photovoltaic- thermoelectric coupled power generation system. The recent progress about the joint research project is reported in this paper. Emphasis is put on the mechanism, design and fabrication of high efficiency nano graded thermoelectric materials. The future research plan is also mentioned in brief.
The influences of sintering temperature, soaking time and annealing time on the quality factor of Ba(Mg/13Nb2/3)O3 microwave dielectric ceramic were investigated. The result showed that Qf value increased as the sinte...
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The influences of sintering temperature, soaking time and annealing time on the quality factor of Ba(Mg/13Nb2/3)O3 microwave dielectric ceramic were investigated. The result showed that Qf value increased as the sintering temperature increasing. It was ascribed to the increasing of the relative density and ordering parameter S. The maximum value of Qf, 49500 GHz, was gained at 1550°C. With soaking time increasing, Qf value increased. The increasing of B-site 1:2 ordering degree and grain size should be responsible for the improvement of Qf value. When soaking time was 16 h, Qf value reached 58000 GHz. Annealing time had great effect on Qf value. With annealing time increasing, Qf value increased quickly. This was because of the improvement of B-site 1:2 ordering caused by annealing. A high Qf value, 71500 GHz, was acquired when annealing time was 48 h.
Among the preparing methods of ceramic particles reinforced metal matrix composites, the in-situ reaction synthesistechnology has many technical and economical advantages over other traditional methods obviously. Sev...
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Among the preparing methods of ceramic particles reinforced metal matrix composites, the in-situ reaction synthesistechnology has many technical and economical advantages over other traditional methods obviously. Several principal techniques to prepare metal matrix composites by in-situ reactive synthesis method were analyzed in this paper. Based on the analysis, a kind of preparing by using SHS and HP technique which was combustion and in-situ reaction synthesis of dual-phase ceramic reinforced copper-based composites was given. The impact of preparing condition on the structure and the behavior of the material were also researched. At last, some fundamental characteristics of the copper-based composite were studied, compared with the pure copper this kind of copper-based composite kept the electric conductivity and thermal conductivity above 80 percent, at the same time the wear resistance improved 6 times.
In this paper, transparent Li2O-Al2O 3-SiO2 system glass-ceramic with low expansion was prepared by melting method, using SiO2, Al2O3 Li2CO3 as raw materials, a small amount of alkaline-earth metal oxide, clarify addi...
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In this paper, transparent Li2O-Al2O 3-SiO2 system glass-ceramic with low expansion was prepared by melting method, using SiO2, Al2O3 Li2CO3 as raw materials, a small amount of alkaline-earth metal oxide, clarify additive and nucleating agent (TiO2, ZrO 2). The glass-ceramic was nucleated and crystallized under different temperature and time, according to the DTA. The results show that the glass-ceramic of Li2O-Al2O2-SiO2 system could be obtained by being nucleated at 550°C for 2 hours and crystallized at 550°C for 1 hour. The system was fully compact. The crystal size in the glass-ceramics was small and homogenous, and its main crystalloid was β-quartz. The expansion coefficient of the glass-ceramics was 2.262×10-7/°C(0 [similar to] 900°C)and the density was 2.5 g/cm3.
Poly-2-acrylamido-2-methyl propane sulfonic acid( PAMPS) proton exchange membrane and cross-linking PAMPS were prepared for PEM fuel cell. The water content, dimensional change, mechanical property, high temperature w...
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Poly-2-acrylamido-2-methyl propane sulfonic acid( PAMPS) proton exchange membrane and cross-linking PAMPS were prepared for PEM fuel cell. The water content, dimensional change, mechanical property, high temperature water retentivity and proton conductivity of the membranes were investigated. It was found that the PAMPS membrane had high proton conductivity (0.32 S/cm), but high dimensional change and low mechanical property. After cross-linking, the membranes had high water retentivity in high temperature and high proton conductivity (3% MBA, 0.076 S/cm), but low dimensional change and high mechanical property(3% MBA, 23.6 MPa).
The mechanical properties, thermal properties, electrical properties and oxidation behavior at high temperature of Ti3SiC2 with solute Al synthesized by hot pressing the mixture powder with the molar ratio 2TiC/Ti/Si/...
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The mechanical properties, thermal properties, electrical properties and oxidation behavior at high temperature of Ti3SiC2 with solute Al synthesized by hot pressing the mixture powder with the molar ratio 2TiC/Ti/Si/0.2Al were studied in this paper. The compressive strength, flexural strength, fracture toughness and Vicker's hardness were 854 MPa, 420 MPa, 5.8 MPa·m1/2 and 3.5-5.0 GPa;at 25°C and 800°C, the electrical conductivities were 4.3 × 106 S/m and 1.0 × 106 S/m, respectively. The thermal expound coefficient was 9.0 × 10-6 /K. The solute Al altered the oxidation mechanism of Ti3SiC2-The oxide layers consisted of a mass of α-Al2O3 formed by the outward diffusion of Al, instead of the outward diffusion of Ti, were observed on oxidized samples as a dense and adhesive protect scale. The oxidation mechanism varied with the additive aluminum, which greatly improved the oxidation resistance of Ti3SiC2.
The nano particles of angelica were prepared by high-speed centrifugal sheering (HSCS) pulverizer. The particles were characterized by ZetaPALS light scattering granulometric analyzer, optical microscope and SEM. HPLC...
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The nano particles of angelica were prepared by high-speed centrifugal sheering (HSCS) pulverizer. The particles were characterized by ZetaPALS light scattering granulometric analyzer, optical microscope and SEM. HPLC was employed to determine the content of ferulic acid, which is the indes ingredient of angelica. Experimental results showed that the average size of solid particle was 76.5 nm after nano-pulverization. The great majority of the plant cell was broken. After nano-pulverization, extraction percent of ferulic acid was increased by 12.95%.
A numerical study is presented that simulates small punch creep (SP-C) tests using a finite-element method (FEM). The objective of the present study is to develop a miniaturized testing methodology for high-temperatur...
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Water management of PEMFC is a key factor for its successful operation. Based on the microstructure model of the catalyst layer, the transfer manner of the water produced in the electrochemical reaction is analysed. A...
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Water management of PEMFC is a key factor for its successful operation. Based on the microstructure model of the catalyst layer, the transfer manner of the water produced in the electrochemical reaction is analysed. According to the hydrophilic and the hydrophobic characteristics of the porous medium of the catalyst layer, sub-diffusion layer and the diffusion layer, the effect of the diameter of the pore in the porous medium on the saturation water vapour pressure is calculated, and hence conclusion is made that the produced water by the electrochemical reaction can be either vapour or liquid, depending upon the environment where it exists. Hydrophilicity, hydrophobicity and the diameter of the pore in the porous medium have great effect on the saturation water vapour pressure;when water phase change and two-phase flow is studied in pore level, the factors mentioned above must be considered.
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