巨厚覆盖层无套管裸壁钻进综合技术

地质勘查向深部拓展是大势所趋,而深部钻探复杂性和难度各具特点,其中,软弱不稳定复杂地层钻进本是钻探工程一大难点.千米巨厚松散覆盖层无套管全裸壁钻进技术是一种大胆探索,成功了即可创建比有套管支护更安全、更经济的钻进方法.     

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.     

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.     

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。     

卷接机回丝量与卷烟卷制质量的相关性研究

为提高卷烟在制品卷制质量,文章针对PROTOS70卷接机不同回丝量情况下的烟支重量标准偏差、端部落丝量、含末率及空头剔除率等指标的相关性进行研究,并针对不同回丝量进行试验。结果表明,在试验范围内,回丝量的变化对烟支重量标准偏差及空头剔除率有较明显的影响,回丝量与烟支重量标准偏差及空头剔除率具有较强的负相关关系,回丝量在...     

实验室电源和接地

高质量的电源和良好的接地系统是实验室仪器高效运行的保证．本文试就笔者的实践经验对电源的稳压及正确安装、接地的配置和注意事项谈一些看法．     

Classrooms as installations: a conceptual framework for analysing classroom photographs from the past

This paper suggests a new way of working with and analysing school photographs in history of education research, especially photographs of school classrooms. It advances a new methodological approach for inquiring into the spatiality and materiality of schooling. This approach is located in the practice of installation art and draws from the theory of relational aesthetics and postproduction. As demonstrated in the paper, thinking about school spaces and places as installations, and place‐making practices as a form of installation making, presents opportunities for posing new and different types of research questions. It also provides opportunities for generating new inquiry and representational practices in educational research. Conceptualising school spaces and places as installations that demand spectator participation to function as intended requires educational researchers to think critically about the spatial dimensions of educational experiences and the experiences of place in educational contexts.     

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