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941.
甲烷和乙烷可以同时在W-Mn/SiO2催化剂上得到活化生成乙烯。原料乙烷和甲烷体积比在0.11~0.25的范围内,当甲烷转化率为20%左右时,共进料反应产物中乙烯体积浓度为8%~12%,达到炼油厂催化裂化干气中乙烯的浓度。 相似文献
942.
Monitoring Power Dissipation for Fault Detection 总被引:1,自引:0,他引:1
Bapiraju Vinnakota 《Journal of Electronic Testing》1997,11(2):173-181
In this paper, we suggest that the dynamic power dissipation of acircuit can be used for fault detection. Even those faults which do notaffect static power dissipation can be detected by monitoring dynamic powerdissipation. We discuss how stuck-at, stuck-open, and redundant faults maybe detected by monitoring dynamic power dissipation. In many cases, theFourier spectra of the supply currents in the good and faulty circuits willalso be very different. Further, specific tests can be applied so as toimprove fault coverage. Power monitoring is verified using simulation, andalso experimentally, for example circuits. 相似文献
943.
944.
945.
三角高程测量的不同方法比较分析 总被引:4,自引:0,他引:4
在工程施工中,经常涉及到高程测量.传统的测量方法为水准测量和三角高程测量,它们都存在着不同的优缺点.为了寻找一种能够快速测量高程,并且精度较高的方法,比较分析两种不同三角高程测量是否可行. 相似文献
946.
传统的干燥控制系统思维方式是把干燥流程看成是一个大的惯性场,以惯性的形态看待与过程相关的数据,对输入参数的过程实时性很少研究,这样的结果就是控制准确性、精确度与实际过程的吻合程度较差。拟从干燥系统输入体系的结构入手,采用时序分析的手法对入粮到干燥的传输时序进行解析,推理出动态实时数据模型。 相似文献
947.
In 1675, English scientist Robert Hooke discovered “the true... ...manner of arches for building,” which he summarized with
a single phrase: “As hangs the flexible line, so but inverted will stand the rigid arch.” In the centuries that followed,
Hooke’s simple idea has been used to understand and design numerous important works. Recent research at MIT on the interactive
analysis of structural forces provides new graphical tools for the understanding of arch behavior, which are useful for relating
the forces and geometry of masonry structures. The key mathematical principle is the use of graphical analysis to determine
possible equilibrium states. 相似文献
948.
赖永凯 《数字社区&智能家居》2006,(14)
对目前常见网络考试分析系统的功能和特点进行了对比分析,然后提出改进方案,建立相应的系统模型,并明确作为检验网络教学效果的重要手段之一,设计一套完善的测试结果分析工具是非常必要的。 相似文献
949.
Manabu Ishitobi Takeshi Myoi Koji Soshin Eiji Hiraki Mutsuo Nakaoka 《Electrical Engineering in Japan》2005,153(3):79-87
This paper presents a single lossless inductive snubber‐assisted ZCS‐PFM series resonant DC‐DC power converter with a high‐frequency high‐voltage transformer link for industrial‐use high‐power magnetron drive. The current flowing through the active power switches rises gradually at a turned‐on transient state with the aid of a single lossless snubber inductor, and ZCS turn‐on commutation based on overlapping current can be achieved via the wide range pulse frequency modulation control scheme. The high‐frequency high‐voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high‐frequency high‐voltage transformer and the magnetizing inductance of the high‐frequency high‐voltage transformer. As a result, this high‐voltage power converter circuit for the magnetron can achieve a complete zero current soft switching under the condition of broad width gate voltage signals. Furthermore, this high‐voltage DC‐DC power converter circuit can regulate the output power from zero to full over audible frequency range via the two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 79–87, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20126 相似文献
950.
Use of climate scenarios to aid in decision analysis for interannual water supply planning 总被引:1,自引:0,他引:1
This work addresses the issue of climate change in the context of water resource planning on the time scale of a few years.
Planning on this time scale generally ignores the role of climate change. However, where the climate of a region has already
shifted, the use of historical data for planning purposes may be misleading. In order to test this, a case study is conducted
for a region, the Australian Capital Territory, where long term drought is raising concerns of a possible climate shift. The
issue is cast in terms of a particular planning decision; the option to augment water supply in the next few years to hedge
against the drought persisting. A set of climate scenarios are constructed for the region corresponding to the historical
climate regime and to regimes where progressively greater levels of change are assumed to have already taken place (5%, 10%,
20% reductions in mean rainfall). Probabilities of the drought persisting are calculated for each of the scenarios. The results
show substantial increases in the probability of the drought persisting for even moderate reductions in mean rainfall. The
sensitivity of the decision to augment supply to the scenario results depends ultimately on the planners tolerable thresholds
for the probability of the drought persisting. The use of different scenarios enables planners to explore the sensitivity
of the decision in terms of their risk tolerance to ongoing drought and to their degree of belief in each of the scenarios
tested. 相似文献