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71.
Jorge Mario Jáuregui 《Architectural Design》2011,81(3):58-63
Jorge Mario Jáuregui of Metrópolis Projetos Urbanos (MPU) has been responsible for more than 20 projects for the Favela-Barrio (slum-to-neighbourhood) Programme implemented by the Rio de Janeiro city government, and two large-scale urban redevelopment projects for President Lula's PAC (Growth Acceleration Programme). Here Jáuregui describes the strategies behind his work and specifically the transformation of public space that was undertaken at the Complexo de Manguinhos in northern Rio as part of the PAC scheme. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
72.
针对管线钢L245钢在太钢炼钢二厂北区3号宽板坯铸机生产时铸坯角部经常出现横裂纹,造成其热轧后卷板边部存在裂纹缺陷,利用Gleeble-3800型热/力学模拟试验机对管线钢L245钢进行了高温面塑率及高温强度的测试,并用扫描电镜对测试试样断口形貌进行观察.从试验结果分析认为:管线钢1245钢的化学成分设计决定其对裂纹的敏感性,由于第Ⅲ区脆性温度区间的高温面塑率低导致其在连铸过程铸坯冷却或受力不均衡情况下铸坯角部裂纹的发生.为要避免铸坯角部横裂纹的产生,在连铸坯矫直时,其角部温度应避开第Ⅲ区脆性温度区间. 相似文献
73.
针对2.4 GHz频段内的IEEE 802.15.4,研究其与无线局域网共存时的抗干扰性。实验设定了多种场景并测试了实际应用环境中IEEE 802.15.4的通信质量。实验数据表明,WLAN干扰可使IEEE 802.15.4数据丢包率高达94%。通过实验数据分析得到了IEEE 802.15.4通信节点丢包率与WLAN信道、节点发送功率以及RSSI的相关性,为研究WSN的同频抗干扰技术提供了有价值的实验依据。 相似文献
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75.
Jean-Michel Thomassin Christine Jérôme Thomas Pardoen Christian Bailly Isabelle Huynen Christophe Detrembleur 《Materials Science and Engineering: R: Reports》2013,74(7):211-232
The extensive development of electronic systems and telecommunications has lead to major concerns regarding electromagnetic pollution. Motivated by environmental questions and by a wide variety of applications, the quest for materials with high efficiency to mitigate electromagnetic interferences (EMI) pollution has become a mainstream field of research. This paper reviews the state-of-the-art research in the design and characterization of polymer/carbon based composites as EMI shielding materials. After a brief introduction, in Section 1, the electromagnetic theory will be briefly discussed in Section 2 setting the foundations of the strategies to be employed to design efficient EMI shielding materials. These materials will be classified in the next section by the type of carbon fillers, involving carbon black, carbon fiber, carbon nanotubes and graphene. The importance of the dispersion method into the polymer matrix (melt-blending, solution processing, etc.) on the final material properties will be discussed. The combination of carbon fillers with other constituents such as metallic nanoparticles or conductive polymers will be the topic of Section 4. The final section will address advanced complex architectures that are currently studied to improve the performances of EMI materials and, in some cases, to impart additional properties such as thermal management and mechanical resistance. In all these studies, we will discuss the efficiency of the composites/devices to absorb and/or reflect the EMI radiation. 相似文献
76.
《Journal of Nuclear Science and Technology》2013,50(10):1072-1085
Critical and subcritical masses were calculated for a sphere of five curium isotopes from 243Cm to 247Cm in metal and in metal-water mixtures considering three reflector conditions: bare, with a water reflector or a stainless steel reflector. The calculation were made mainly with a combination of a continuous energy Monte Carlo neutron transport calculation code, MCNP, and the Japanese Evaluated Nuclear Data Library, JENDL-3.2. Other evaluated nuclear data files, ENDF/B-VI and JEF-2.2, were also applied to find differences in calculation results of the neutron multiplication factor originated from different nuclear data files. A large dependence on the evaluated nuclear data files was found in the calculation results: more than 10%Δk/k relative differences in the neutron multiplication factor for a homogeneous mixture of 243Cm metal and water when JENDL-3.2 was replaced with ENDF/B-VI and JEF-2.2, respectively; and a 44% reduction in the critical mass by changing from JENDL-3.2 to ENDF/B-VI for 246Cm metal. The present study supplied basic information to the ANSI/ANS-8.15 Working Group for revision of the standard for nuclear criticality control of special actinide elements. The new or revised values of the subcritical mass limits for curium isotopes accepted by the ANSI/ANS-8.15 Working Group were finally summarized. 相似文献
77.
60 GHz无线通信技术具有非常宽的带宽,可以应用于超高速无线数据传输,已经成为第四代无线通信的重要组成部分,学术界和工业界对此投入了持续的关注。对60 GHz频段微带波导转换结构进行了设计,结果显示在57 GHz~64 GHz通信频率范围内,插入损耗小于1 dB,回波损耗小于-15 dB,达到了实用化要求。并利用MMIC芯片完成了60 GHz毫米波通信系统T/R模块的集成设计,对QPSK通信体制下的调制和解调信号进行了分析,验证了系统的可行性。 相似文献
78.
79.
无线传感器网络的性能很大程度上受限于无线信道的特性。随着物联网事业飞速发展,近水面环境下2.4 GHz信号传播路径损耗模型的研究已成为无线传感器网络研究的重要课题之一。在近水面的环境下,针对基于IEEE802.15.4标准的2.4 GHz信号传播特性进行了实测研究,并利用最小二乘法对双射线模型进行拟合分析得到经验公式。研究结果表明:校正后的经验公式更符合实际环境中的信号传播路径损耗特点,这也为未来大规模铺设近水面无线传感器网络提供理论指导作用。 相似文献
80.