排序方式: 共有174条查询结果,搜索用时 15 毫秒
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智能建筑在中国走过了十几个春秋。业内人士对智能建筑的认识由混沌逐步走向清晰,建筑智能化市场也从混沌开始走向有序,政府相关部门对建筑智能化市场的监督力度也在不断地加强。专家指出,我国已经成为全球最大的智能化市场。面对庞大、混乱、超高利润的智能建筑市场,建设各方的注意力已经不仅仅是对智能建筑概念的认识和深化,而是越来越重视如何合理地进行建设这一实质性的问题。按工程学的观点,规范而且科学的建设过程应该包括八个方面。 相似文献
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在我国网络事业不断发展的带动和影响下,我国的通信工程传输技术在长途干线通信和本地通信传送上,都得到了更加广泛的应用. 相似文献
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97式18.4mm防暴枪是我国自行研制的中口径防暴武器。它为我国警用防暴武器又增加了新品种,填补了这一领域里的空白。 研制背景 长期以来,我国警用武器一直是从军用制式武器中选用的,没有一个独立、系统的装备系列,在这个领域,我们远远 相似文献
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王杰峰任军辉张树楠曹洋 《高压电器》2022,(10):196-203
故障电流试验是晶闸管换流阀运行型式试验中重要的试验项目之一,国内外对故障电流施加方式的研究已较为深入,但对电流过零后如何立即施加恢复电压的试验方案则研究较少。通过研究国内外故障电流试验回路的发展现状,文中提出了一种采用工频电压发生器施加恢复电压的试验回路,介绍了其施加预期恢复电压的试验方法,计算确定了试验回路设备的参数,最后通过仿真验证了单波次和多波次故障电流试验中恢复电压施加方案的可行性。文中的研究成果已成功应用于某公司自主建设的晶闸管换流阀故障电流试验系统,并开展了晶闸管换流阀组件的故障电流试验,试验结果满足相关标准的要求。本试验回路兼并考虑了经济性和试验等效性,回路结构简单,控制便捷,是一种理想的等效试验回路。 相似文献
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先进第三代中锰汽车钢具有强塑积高、成本低廉等优点,应用前景广阔,但其焊缝区的淬硬性大,影响后续加工和使用。采用光纤激光器对6 mm厚中锰汽车钢进行焊接,研究了焊接热输入对焊缝成形、组织、冲击韧性和断裂行为的影响。结果表明,当热输入为150~500 J/mm时,激光焊接属于深熔焊,焊缝成形较好;焊缝区的硬度随着热输入的增大呈减小趋势。当热输入较小时,焊缝组织为马氏体,随着热输入的增加,焊缝中有少量的贝氏体组织生成;焊缝在-40℃温度下的冲击韧性随着热输入的增加先增加后降低,当热输入为300 J/mm时,冲击韧性最高,断口呈韧性断裂;中锰钢焊缝组织中原奥氏体晶界、马氏体板条束界和板条块界均对裂纹的扩展起阻碍作用,裂纹扩展功与平均有效晶粒尺寸呈反比关系,与大角度晶界密度呈正比关系。 相似文献
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Numerical research on the mechanism of contaminant release through the porous sediment-overlying water interface 总被引:2,自引:0,他引:2
After the pollutant discharged into the river or lake has been reduced, the release of the contaminant from the sediment to the overlying water may cause the river and lake be contaminated again. On the condition that the overlying water flow does not lead to sediment suspension, numerical researches are carried out for the mechanism of contaminant release through the sedimentoverlying water interface. The overlying water flow is calculated as turbulence. The sediment is regarded as isotropic homogeneous porous medium, therefore the seepage field in the porous sediment layer is obtained by solving Darcy's equations. Coupled two dimensional steady flows of the overlying water and the pore water in the sediment are calculated. Based on the flow fields obtained, the unsteady contaminant solute transportation process in the pore water in the sediment and the overlying water is numerically simulated, as the shapes of the sediment-overlying water interface are flat or periodic triangular respectively. Numerical results show that the exchange of the pore water and the overlying water is an important factor which decides the release flux of the contaminant from the sediment to the overlying water. The pressure distribution produced by the overlying water flow along the sedimentoverlying water interface, as it is not flat, may induce the seepage of the pore water in the sediment and through the sedimentoverlying water interface, which may increase the release flux of the contaminant from the sediment to the overlying water. 相似文献
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