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基于实时运输协议RTP的网络音频会议系统的实现 总被引:1,自引:0,他引:1
本文描述了适合实时数据传输的RIP协议,讨论了在网络环境中实现音频会议系统要解决的一些关键问题。并在此基础上,介绍了在Windows平台上的具体实现例子。 相似文献
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Victor F. Boyarinov 《Progress in Nuclear Energy》2004,45(2-4):133-142
The C5G7 MOX benchmark specifying a sixteen-assembly core with asurrounding water reflector was proposed as a basis to measure current transport code abilities in the treatment of reactor core problems without spatial homogenization. Seven-group cross sections for all materials were used as initial information. Just that fact allows to test an accuracy of solving the neutron transport equation excluding additional errors connected with preparing the group cross sections. In this paper, Surface Harmonics Method (SHM) is applied to calculation of the two-dimensional configuration of this benchmark. Different approximations of SHM were applied, both with and without spatial homogenization. Additionally, this fact allowed evaluating the effect of spatial homogenization of cells. Comparisons were carried out for keff and pin powers both with the reference results and between the results calculated by different SHM approximations. 相似文献
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我国交通运输设备制造业科技投入竞争力研究 --以大中型工业企业为案例的分析 总被引:1,自引:0,他引:1
陈昭锋 《机电产品开发与创新》2005,18(1):26-28
交通运输设备制造业的竞争力,在很大程度上代表了一个国家或一个地区制造业的水平。其中科技投入是重要决定因素。本文以大中型工业企业为案例,实证研究了我国交通运输设备制造业科技投入竞争力建设的行业特征、地区特征和存在问题,为我国机电产业科技竞争力提升提供决策依据。 相似文献
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《Ceramics International》2017,43(3):3369-3376
The structural, magnetic and electrical properties of Gd1−xSr1+xFeO4 (0≤ x≤0.4) have been discussed in terms of the mixed valence state of Fe (Fe3+/Fe4+). The Rietveld refinements of powder X-ray diffraction data reveal that all the phases crystallizes with tetragonal unit cell in the space group I4/mmm. The lattice constant a decreases while there is increase in c parameter with increase in x. All the phases are antiferromagnetic and the increase in Weiss constant (θp) with Sr2+ content could be attributed to the generation of the Fe4+ ions which introduces the ferromagnetic double-exchange Fe3+−O2-−Fe4+ interactions. The materials show semiconducting behavior and the electronic conduction in these materials is obtained via hopping of electrons from the occupied sites, Fe3+ ions, to the unoccupied sites, Fe4+ ions. 相似文献
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In 1976, a pressure vessel of a tank wagon burst during gravity shunting. The pressure vessel was filled with cold fluid carbon dioxide and failed by cleavage fracture explosively. Big parts of the vessel were flung up to 300 m, a building was destroyed, and rails as well as the superstructure of the gravity shunting yard were damaged.The initiation sites of the fracture and the orientations of crack propagation were determined by means of the patterns on the fracture surfaces of the broken parts. The initiation sites were located in the heat-affected zone (HAZ) of welds, close to transitions of cross-sections and the starting and end points, respectively, of the welds. The primary initiation of crack propagation was almost certainly on the left side, close to the weld of the fixed bearing connecting the vessel with the carriage.The results of metallographic investigations indicated the development of cold weld cracks during welding. Mechanical behavior assessments on specimens extracted from the failed vessel indicated sufficient strength and ductility in tensile loading. The values of the notched-bar impact energy or toughness were within the limits according to industry rules and standards, except for one metal sheet of the vessel that was welded to the left fixed bearing.During shunting, two tank wagons were inappropriately braked, and began to roll too quickly. One rail brake used for deceleration of the wagons caused impulsive noises and vibrations, resulting in high impulsive loading of the first wagon. The cold weld cracks in the heat-affected zones near the fixed bearing of the pressure vessel were initiation points for unstable crack growth. As the result of very low notched-bar impact toughness, crack propagation was not arrested and unstable cleavage fracture occurred.Due to a second similar accident, happened one year before, a program was started to assess characteristic values of pressure vessel materials and the influence of weld parameters by the manufacturer, the inspecting authority, and BAM. The scientific findings led to modifications of industry rules and standards with regard to using ISO-V specimens and to higher required values for notched-bar impact energy for fine grain structural steels. 相似文献
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《Packaging, Transport, Storage and Security of Radioactive Material》2013,24(4):220-226
AbstractIn a companion PATRAM 2013 paper, C. Bajwa et al. provide an overview of international level efforts that began in 2010 to develop a comprehensive and detailed Technical Basis Document (TecBasDoc) to support the current International Atomic Energy Agency (IAEA) Transport Regulations (SSR-6, 2012) and future revisions thereto. The draft TecBasDoc that has so far resulted from efforts by a large number of IAEA staff and international experts exceeds 300 pages in length using, to the greatest extent possible, historical documents dating as far back as the 1950s as reference material. The intent is to capture, for those Member States new to transport and for future generations, the scientific and technical heritage of the several decades of development that has occurred in transport safety, preserving this knowledge for future reference. The latest effort, in December 2012, involved consultants to the IAEA adapting the draft to reflect guidance from the IAEA’s Transport Safety Standards Committee and delving into the IAEA’s archives searching out many long sought, older supporting documents. This paper elaborates on Chaps. 8–10 of the TecBasDoc, dealing with respectively Classification of Materials, Classification of Packages and Package Design and Testing. Chapter 8 elaborates on the many decisions resulting in an initial nine material classifications, which focused more on the physical and not the radioactive characteristics of the materials, to the current, significantly different classifications that focus more on the material’s radioactive properties. Chapters 9 and 10 combine to provide extensive, detailed elaboration on why decisions were made concerning the various package classifications and the associated design, testing and acceptance requirements associated with each package type. Chapter 10 cites two extensive supporting appendices. These three chapters and two appendices currently cite and elaborate on >200 historical documents. Efforts are underway to make this extensive document base more complete and to make as many documents as possible available electronically. In this paper, each of these three drafted chapters and the two supportive appendices are overviewed, providing insight into key and typical findings that have been uncovered and incorporated into the draft document. The many experts who have contributed to the current draft are appropriately acknowledged. 相似文献