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111.
概述了非线性动力系统分岔理论,介绍了基于MATLAB的电压稳定分析工具箱(Voltage Stability Tool-box,VST)。运用VST对IEEE-5节点系统在几种不同控制参数变化模式下进行了静态和动态分岔点的搜索,获得了比较满意的结果,验证了非线性的分岔理论在电压稳定分析中的相关结论。 相似文献
112.
基于虚拟化技术的信息系统安全防护框架研究 总被引:1,自引:0,他引:1
关键信息系统的安全防护问题一直以来都是研究热点。围绕数据安全和恶意代码攻击等关键安全问题,以虚拟机监视器作为安全防护立足点,充分利用虚拟机监视器的拦截、隔离、I/O数据加解密等机制,构建了一种新的信息系统安全防护构架,详细阐述了安全防护框架的工作原理以及典型安全服务的构建方法。 相似文献
113.
114.
Previous studies have shown that there is potential semantic dependency
between part-of-speech and semantic roles. At the same time, the predicate-argument
structure in a sentence is important information for semantic role labeling task. In this
work, we introduce the auxiliary deep neural network model, which models semantic
dependency between part-of-speech and semantic roles and incorporates the information
of predicate-argument into semantic role labeling. Based on the framework of joint
learning, part-of-speech tagging is used as an auxiliary task to improve the result of the
semantic role labeling. In addition, we introduce the argument recognition layer in the
training process of the main task-semantic role labeling, so the argument-related
structural information selected by the predicate through the attention mechanism is used
to assist the main task. Because the model makes full use of the semantic dependency
between part-of-speech and semantic roles and the structural information of predicateargument, our model achieved the F1 value of 89.0% on the WSJ test set of CoNLL2005,
which is superior to existing state-of-the-art model about 0.8%. 相似文献
115.
Effect of refrigerant flow direction and throttle opening in RAC unit using micro-channel evaporator
Experimental comparisons are made on the performance of a room air conditioner using micro-channel evaporator with the refrigerant flowing in the Upward Flow mode (UF mode, meaning refrigerant flowing upward from the bottom) and Downward Flow mode (DF mode, meaning refrigerant flowing downward from the top). Test results show that UF mode develops a superior refrigerant distribution in the micro-channels to what DF mode does. This is then illustrated by the infrared thermographs at the nominal operating condition. Subsequently, the effect of the width of throttle opening on the sample unit performance is investigated experimentally in the micro-channel evaporator adopting the UF mode. Measurement and calculation results of pressure difference between evaporator inlet and outlet, mean temperature of the evaporator surface, cooling capacity, input power and EER show that the tested unit operates with the best performance with the refrigerant pressure of 993.61 kPa at the inlet of micro-channel evaporator. Infrared thermographs of the working evaporator verify this conclusion. 相似文献
116.
117.
Synthesis of a boron-containing conducting polymer from the anodic oxidation of Tris(pyrrolyl)borane
《Synthetic Metals》2002,129(3):309-314
The electrochemical oxidation of Tris(N-pyrrolyl)borane (1) in THF yielded a conducting polymer film with an electron conductivity of ca. 7×10−4 S cm−1. The coulometric measurements indicated that the three pyrrolyl units were not totally coupled during the electropolymerization reaction. From further UV–VIS and FT-IR spectroscopy data, a structure of poly(1) was then proposed. 相似文献
118.
Paola Bombarda Costante M. Invernizzi Claudio Pietra 《Applied Thermal Engineering》2010,30(2-3):212-219
In the context of heat recovery for electric power generation, Kalina cycle (a thermodynamic cycle using as working fluid a mixture of water and ammonia) and Organic Rankine Cycle (ORC) represent two different eligible technologies. In this work a comparison between the thermodynamic performances of Kalina cycle and an ORC cycle, using hexamethyldisiloxane as working fluid, was conducted for the case of heat recovery from two Diesel engines, each one with an electrical power of 8900 kWe. The maximum net electric power that can be produced exploiting the heat source constituted by the exhaust gases mass flow (35 kg/s for both engines, at 346 °C) was calculated for the two thermodynamic cycles. Owing to the relatively low useful power, for the Kalina cycle a relatively simple plant layout was assumed. Supposing reasonable design parameters and a logarithmic mean temperature difference in the heat recovery exchanger of 50 °C, a net electric power of 1615 kW and of 1603 kW respectively for the Kalina and for the ORC cycle was calculated.Although the obtained useful powers are actually equal in value, the Kalina cycle requires a very high maximum pressure in order to obtain high thermodynamic performances (in our case, 100 bar against about 10 bar for the ORC cycle). So, the adoption of Kalina cycle, at least for low power level and medium–high temperature thermal sources, seems not to be justified because the gain in performance with respect to a properly optimized ORC is very small and must be obtained with a complicated plant scheme, large surface heat exchangers and particular high pressure resistant and no-corrosion materials. 相似文献
119.
表面粗糙度是影响工件性能的一个重要因素,适当减少表面粗糙度值可以改善工件表面的机械特性,为了掌握化学镀后工件表面粗糙度值的变化规律,在同一种Ni-P化学镀镀液中,对经测量具有不同表面粗糙度值的工件,镀上相同厚度的镀层,再测量工件表面粗糙度值,对比两次测量数据,结果发现化学镀后工件表面粗糙度值普遍减小,结合镀层表面微观形状图分析得知,在微观表面的波峰和波谷处存在沉积发生面的面积变化是工件表面粗糙度值普遍减小的原因,再经数学计算得出,表面粗糙度值的减小量随工件原表面粗糙度值增大而增大,减小幅度约为工件原表面粗糙度值的11%. 相似文献
120.