管风琴、古钢琴与钢琴的发展及其联系

管风琴、古钢琴与钢琴都属于键盘乐器。根据发音的原理,键盘乐器可以分为靠空气振动发音的管乐性键盘乐器和靠琴弦振动发音的弦乐性键盘乐器。靠空气振动发音的管乐性键盘乐器主要是指管风琴;靠琴弦振动发音的弦乐性键盘乐器包括古钢琴和钢琴。由于在机械结构方面存在着差异,无论在触键、音色方面还是在演奏风格上都有较大的区别。     

有效进行电气施工管理的措施

针对建筑电气安装工程施工的三个特定阶段,从人员素质、质量控制、安全控制、竣工验收、竣工资料整理等方面,系统论述在施工现场如何有效地进行电气施工管理,以确保电气安装工程质量,实现建筑工程使用功能。     

火电厂循环水钢管的程序计算

利用程序对循环水钢管进行稳定性计算、刚度计算、强度计算,不但克服了手工计算繁琐、容易出错等缺点,而且更能适应未来大机组发展的需要,具有很好的应用前景。     

Calibration of pipe roughness coefficient based on manning formula and genetic algorithm

This paper presents a method to calibrate pipe roughness coefficient (i.e., Manning n-factor) with genetic algorithm (GA) under multiple loading conditions. Due to the old pipe age as well as deleting valves and blends in the skeleton of distribution network, most of the pipes in hydraulic model of practical water distribution system (WDS) are rough. The commonly used Hazen-Williams C-factor is therefore replaced by Manning n-factor in calibrating WDS hydraulic model. Adjustment to GA is designed, and the program efficiency is improved. A case study shows that the adjustment can save 60% of the total runtime. About 90% of the relative differences between simulated and observed pressures at monitoring locations are lower than 3%, which suggests that the proposed adjustment to the calibration is efficient and effective.     

高炉炉顶煤气管连接方式的比较

比较了高炉炉顶煤气管三岔管式连接和球式连接的特点,阐明了球式连接的实用性.     

A gravity heat pipe for high voltage vacuum interrupter

To enhance nominal current of high voltage vacuum circuit breakers （VCBs）, a gravity heat pipe was proposed to replace stationary conducting rod of a high voltage vacuum interrupter. The heat pipe is composed of two coaxis tubes： the external tube is made of oxygen-free copper and the inner tube is made of stainless steel. The bottom end of the inner stainless steel tube is connected to the external copper tube by holes. Transient and static thermal performance of the heat pipe was measured, and the thermal resistance of it was compared with that of a solid copper rod with the same dimensions. Experimental results showed that thermal resistance of the heat pipe was about 1/3 of that of the copper rod, and it decreased slightly with the rising of the input heat flux. 3D thermal simulation on a 126 kV/2000 A single break VCB was done to compare the thermal performance between the proposed gravity heat pipe and the copper rod serving as the stationary conducting rod of the vacuum interrupter. Simulation results revealed that in the heat pipe case, the maximum temperature between contacts was 67 ℃ lower than that in the copper rod case.     

汽车低速行驶时排气管冒蓝烟故障诊断

分析了汽车低速行驶时排气管冒蓝烟故障原因、故障现象和故障排除方法。     

异径管开裂失效分析

对抚顺石化三厂白油车间一在役异径接管的开裂进行失效分析,包括开裂部件的断口观察、材质的化学成分分析、金相组织检验和力学性能测试。得出的结论是:异径接管在长期服役中,由于受迫振动而造成疲劳开裂。     

从节能的角度分析给水管材的选用

采用对比分析方法,推得各种管径的给水管材与相应公称直径的镀锌钢管单位长度水头损失的比值K,通过对各种规格管材K值的分析,从节能角度提出选用给水管材的合理化建议.     

建筑节能与管网水力平衡技术

解决采暖供热系统的水力平衡是提高供热品质的首要问题,目前可借助于平衡阀和专用智能仪表来实现.建筑物内部系统竖向失调则可通过设置带散热器温控阀的双管系统来解决.