内蒙古西部水汽总量与地面水汽压关系分析

根据2007-2008年内蒙古西部呼和浩特站,二连浩特站逐日08时地面及探空气象观测资料,计算得出两个站点全年水汽总量与地面水汽压值,对水汽总量与地面水汽压的特征及其关系进行了分析。在此基础上利用最小二乘原理对水汽总量与地面水汽压进行了回归分析,分别建立了两站的w-e回归方程,并对回归方程进行了检验。结果表明：水汽总量与地面水汽压之间存在着良好的线性关系,得出的w-e回归方程相关系数均趋近于1,拟合程度较高。此回归方程为不具有探空条件的气象站点提供了利用地面水汽压计算水汽总量的简便方法,具有良好的实际应用价值。     

打孔盗油支管对输送成品油管内压力分布的影响

本文分析打孔盗油支管的成品油输送管道泄漏过程,建立带有打孔盗油支管的成品油输送管道物理模型,通过简化该物理模型建立了带有打孔盗油支管的成品油输送管道的三维压力场数学模型,利用Fluent软件模拟管道出口和支管的出流量比对带有打孔盗油支管的管道的压力场影响,确定其压力场特征,得到了带有打孔盗油支管的管道的压差二次曲线方程。     

负压灌溉供水器供水速率与供水高度关系研究

该文提出了一种新型的负压灌溉供水器.以土壤水吸力与土壤含水率的关系为依据进行理论分析,建立负压灌溉供水器供水速率与供水高度关系的数学模型;在过水断面面积足够大的条件下,设置三个不同的供水高度,研究负压灌溉供水器供水速率与供水高度的关系.在灌溉过程中,土壤含水量呈非饱和状态,可抑制土表湿润导致的无效蒸发和深层渗漏导致的无效灌溉;不会破坏土壤结构,从而使灌溉水量得到充分利用,同时还可以收集雨水并用于农业灌溉.     

基于声卡的机载温度及压力实时采集控制系统

本文通过分析声卡的结构原理,灵活运用软件,开发了一种基于声卡的机载温度、压力信号采集控制系统。该方法实现简单,性价比高,为低频机载信号的采集和控制提供了一种新思路。     

柴油机喷油器内部空化效应的模拟研究

喷油器中空化流特性直接影响燃油的雾化和燃烧.利用CFD-Fire软件,在针阀运动的情况下模拟了喷油器内部从单相流到超空化的过程以及流动特征.数值模拟发现:气泡首先出现在喷孔进口的拐角处,随着流速增加,空化进一步发展,直至贯穿整个喷油器形成超空化,整个流场成为气液两相流.瞬态条件下,针阀运动致使喷孔进口附近压力波动,部分...     

电子化限重车辆自动筛选系统的设计与实现

道路限重管理对于路面相对脆弱的西藏道路来说是一项艰难工作,因此研究开发电子化限重车辆自动筛选系统显得比较重要。针对西藏路面的实际情况,利用SPCE061A单片机和压力传感器等一系列电子元件通过多次试验,设计出了电子化险种车辆自动筛选系统。电子化限重车辆自动筛选系统能够在无人操作的情况下自动检测车辆重量并发出是否允许该车辆通过该限重路段的信号。     

动压巷道围岩控制研究进展及发展重点

随着我国GDP的快速增长,煤炭的需求量不断增加。目前我国大部分矿井巷道为动压软岩巷道。文章分析了动压巷道围岩的显现特征并对目前动压巷道围岩控制研究进展进行探讨,对今后动压软岩巷道围岩控制研究重点及其发展方向提出了见解。     

Numerical analysis of the two-phase pressure drop and liquid distribution in single-screw expander prototype

In this paper, the numerical simulations have been carried out to evaluate the two-phase pressure drop and liquid distribution in screw channel. The numerical models are validated against the present experimental data with statistical accuracy. The effects of pitch circle diameter （PCD）, inlet velocity and inlet sectional liquid holdup on the pressure drop and liquid distribution characteristics in the screw channel are illustrated. It is found that decreasing the PCD and increasing the inlet sectional liquid holdup can increase the liquid holdup on the outer side in screw channel. The PCD and the inlet sectional liquid holdup need to be considered in evaluating the two-phase frictional pressure drop per unit length in the screw channel. The PCD has an effect on the development of the average pressure in the various cross sections, and the inlet sectional liquid holdup has no visible impact on the changing process of the pressure drop in the screw channel. The correlation developed predicts the two-phase frictional pressure drop in the screw channel with great statistical accuracy.     

Pressure gradient evolution in the near-Earth magnetotail at the arrival of BBFs

Using in situ observations from THEMIS A, D and E during the 2008-2011 tail season, we present a statistical study of the evolution of pressure gradients in the near-Earth tail during bursty bulk flow （BBF） convection. We identified 138 substorm BBFs and 2,197 non-substorm BBFs for this study. We found that both the pressure and the Bz component of the magnetic field were enhanced at the arrival of BBFs at the spacecraft locations. We suggest that the increase of Bz during non-substorm BBFs is associated with flux pile-up. However, the much stronger enhancement of Bz during substorm BBFs implies the occurrence of magnetic field dipolarization which is caused by both the flux pile-up process and near-Earth current disruption. Furthermore, a bow-wave-like high pressure appears to be formed at the arrival of substorm BBFs, which is responsible for the formation of region-1-sense FACs. The azimuthal pressure gradient associated with the arrival of substorm BBFs lasts for about 5 min. The enhanced pressure gradient associated with the bow wave is caused by the braking and diversion of the Earthward flow in the inner plasma sheet. The results from this statistical study suggest that the braking and azimuthal diversion of BBFs may commonly create azimuthal pressure gradients, which are related to the forrnation of the FAC of the substorm current wedge.     

Radiation theory comparison for magnetoacoustic tomography with magnetic induction （MAT-MI）

Based on the principle of Lorentz force induced acoustic vibration, radiation theory comparison between acoustic point and dipole sources was conducted for magnetoacoustic tomography with magnetic induction （MAT-MI）. It is proved that each acoustic source of MAT- MI is produced by the divergence of the magnetically induced Lorentz force, and the detected acoustic pressure is the integral of all diffraction sources inside the object. Wave clusters are produced by abrupt pressure changes at conductivity boundaries, and only the configurations in terms of shape and size of phantom models can be recon- structed. However, different from point source, positive and negative pressures are generated by the radiation pat- tern of dipole sources. Reverse vibration phases of wave clusters in collected waveforms and opposite polarities of borderline stripes in reconstructed images are produced at conductivity boundaries, representing the direction of conductivity changes. The experimentally collected wave- forms and reconstructed images of the aluminum foil cylinder and cylindrical saline gel phantom model agree well with simulated results. The favorable results prove the validity of the radiation theory of acoustic dipole source and provide basis for further investigation of conductivity reconstruction for MAT-MI.