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121.
并行作业特征分析是负载分析的重要基础。作业记账日志是开展作业特征分析的重要数据源。由于作业记账日志中没有记录应用名称,现有工具无法按应用名称开展作业特征分析。提出基于关键字模糊匹配的作业记账日志标记方法,设计通用的作业数据模型和柔性可扩展软件架构,集成实现并行作业特征分析工具JobCAT。通过某超级计算机系统百万量级作业记账日志数据测试验证,JobCAT的作业记账日志标记率大于95%。JobCAT支持7个插件、29项统计报表,可一键生成应用的作业特征分析报告,对负载分析研究具有实用价值。 相似文献
122.
为研究PID调节下H桥式逆变器的非线性行为,选取逆变器输入电压为分岔参数,利用频闪映射法推导出PID调节下H桥式逆变器的离散数学模型.使用Matlab编程得到系统输出电流随输入电压变化的动态分岔图,通过数值仿真验证了离散数学模型的正确性.仿真结果表明频闪映射法适用于建立H桥式逆变器的离散数学模型;PID调节下H桥式逆变器存在分岔行为.研究结果可为建立PID调节下H桥式逆变器的离散数学模型提供参考. 相似文献
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125.
In this paper, the kerosene/air rotating detonation engines(RDE) are numerically investigated, and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE including the initiation, instabilities, and propulsive performance. A hybrid MPI + OpenMP parallel computing model is applied and it is proved to be able to obtain a more effective parallel performance on high performance computing(HPC) systems. A series of cases with the total pressure of 1 MPa, 1.5 MPa, 2 MPa, and the equivalence ratio of 0.9, 1, 1.4 are simulated. On one hand, the total pressure shows a significant impact on the instabilities of rotating detonation waves. The instability phenomenon is observed in cases with low total pressure (1 MPa) and weakened with the increase of the total pressure. The total pressure has a small impact on the detonation wave velocity and the specific impulse. On the other hand, the equivalence ratio shows a negligible influence on the instabilities, while it affects the ignition process and accounts for the detonation velocity deficit. It is more difficult to initiate rotating detonation waves directly in the lean fuel operation condition. Little difference was observed in the thrust with different equivalence ratios of 0.9, 1, and 1.4. The highest specific impulse was obtained in the lean fuel cases, which is around 2700 s. The findings could provide insights into the understanding of the operation characteristics of kerosene/air RDE. 相似文献
126.
Zhi Yang Ke Wang Peng Zhu Peng Liu Qiu Zhang Cong Xu Hao-tian Jian Rui-qi Shen 《防务技术》2021,17(4):1572-1578
Triggered spark-gap switch is a popular discharge switch for pulse power systems. Previous studies have focused on planarizing this switch using thin film techniques in order to meet the requirements of compact size in the systems. Such switches are one-shot due to electrodes being too thin to sufficiently resist spark-erosion. Additionally, these switches did not employ any structures in securing internal gas composition, resulting in inconsistent performance under harsh atmospheres. In this work, a novel planar triggered spark-gap switch (PTS) with a hermetically sealed cavity was batched-prepared with printed circuit board (PCB) technology, to achieve reusability with low cost. The proposed PTS was inspected by micro-computed tomography to ensure PCB techniques meet the requirements of machining precision. The results from electrical experiments demonstrated that PCB PTS were consistent and reusable with lifespan over 20 times. The calculated switch voltage and circuit current were consistent with those derived from real-world measurements. Finally, PCB PTS was used to introduce hexanitrostilbene (HNS) pellets in a pulse power system to verify its performance. 相似文献
127.
In order to improve the energy level of fuel air explosive(FAE) with delayed secondary igniters, high energetic metal powders were added to liquid fuels mainly composed of ether and isopropyl nitrate. Metal powders' explosive properties and reaction mechanisms in FAE were studied by high-speed video, pressure test system, and infrared thermal imager. The results show that compared with pure liquid fuels, the shock wave overpressure, maximum surface fireball temperature and high temperature duration of the mixture were significantly increased after adding high energetic metal powder. The overpressure values of the liquid-solid mixture at all measuring points were higher than that of the pure liquid fuels. And the maximum temperature of the fireball was up to 1700 ℃, which was higher than that of the pure liquid fuels. After replacing 30%of aluminum powder with boron or magnesium hydride, the shock wave pressure of the mixture was further increased. The high heat of combustion of boron and the hydrogen released by magnesium hydride could effectively increase the blast effect of the mixture. The improvement of the explosion performance of boron was better than magnesium hydride. It shows that adding high energetic metal powder to liquid fuels can effectively improve the explosion performance of FAE. 相似文献
128.
Min Zhu Sheng-ao Wang Huang Huang Gui Huang Fei Wu Shao-hua Sun Biao Li Zi-jian Xu 《防务技术》2021,17(4):1444-1452
The response characteristics of the warhead under thermal stimuli conditions are important to the safety improvement. The goal of this study is to obtain data on the warhead in the fast cook-off process. In this paper, a numerical calculation method is proposed, whose reliability is supported by comparison with experimental results. Through the numerical calculation, the temperature distribution, temperature change, and ignition time are acquired. The numerical results show that the ignition time is 76 s after the warhead started to burn and that the maximum temperature of the explosive's outer surface is 238.3 C at the ignition time. The fast cook-off experiment of the warhead is implemented so as to get the flame temperature and reaction grades that are not available through numerical calculation. The experimental results show that the overpressure fails to reach the preset minimum value which is equivalent to 6 kg of TNT and that the reaction grade is deflagration. The research results have reference value for the design of the warhead and the reduction of detonation risks. 相似文献
129.
Cheng-ai Wang Jian-bing Xu Yun Shen Yue-ting Wang Teng-long Yang Ze-hua Zhang Fu-wei Li Rui-qi Shen Ying-hua Ye 《防务技术》2021,17(3):741-747
The storage stability of energetic materials is important for its application. Here, the storage stability of Al/CuO nanothermite, which was prepared by electrospray method and stored with different storage time, was systematically researched. The activation energy of Al/CuO nanothermite was calculated by differential scanning calorimetry (DSC). The ignition temperature and the curve pressure history of Al/CuO nanothermite was measured using ignition temperature measuring device and constant-volume pressurization tests, respectively. Further, the thermites were characterized by X-ray Diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Transmission electron microscopy (TEM). The results show that the morphology of the thermites did not change significantly. The activation energy was decreased from 254.1 kJ/mol to 181.8 kJ/mol after storage for 13 months. When stored for 0, 7 and 13 months, the peak pressures of Al/CuO nanothermite were 685.8 kPa, 626.3 kPa and 625.5 kPa, respectively. In addition to the ignition temperature, it was 775 ℃, 739 ℃ and 754 ℃, respectively. This result indicated that the ignition and combustion properties of Al/CuO nano-thermite are obviously reduced when stored for a long time, at room temperature. 相似文献
130.
Xing-liang Wu Sen Xu Ai-min Pang Wei-guo Cao Da-bin Liu Xin-yu Zhu Fei-yang Xu Xu Wang 《防务技术》2021,17(4):1262-1268
MgH2, TiH2, and ZrH2 are three typical metal hydrides that have been gradually applied to composite explosives and propellants as additives in recent years. To evaluate ignition sensitivity and explosion severity, the Hartmann device and spherical pressure vessel were used to test ignition energy and ex-plosion pressure, respectively. The results showed that the ignition sensitivity of ZrH2, TiH2 and MgH2 gradually increased. When the concentration of MgH2 is 83.0 g/m3 in Hartmann device, the ignition energy attained a minimum of 10.0 mJ. The explosion pressure of MgH2 were 1.44 times and 1.76 times that of TiH2 and ZrH2, respectively, and the explosion pressure rising rate were 3.97 times and 9.96 times that of TiH2 and ZrH2, respectively, through the spherical pressure vessel. It indicated that the reaction reactivity and reaction rate of MgH2 were higher than that of TiH2 and ZrH2. In addition, to conduct in-depth theoretical analysis of ignition sensitivity and explosion severity, gas production and combus-tion heat per unit mass of ZrH2, TiH2 and MgH2 were tested by mercury manometer and oxygen bomb calorimetry. The experimental results revealed that MgH2 had a relatively high gas production per unit mass (5.15 mL/g), while TiH2 and ZrH2 both had a gas production of less than 2.0 mL/g. Their thermal stability gradually increased, leading to a gradual increase in ignition energy. Furthermore, compared with theoretical combustion heat, the combustion ratio of MgH2, TiH2 and ZrH2 was more than 96.0%, with combustion heat value of 29.96, 20.94 and 12.22 MJ/kg, respectively, which was consistent with the explosion pressure and explosion severity test results. 相似文献