Effect of Strain Rate on Discontinuous Flow and Mechanical Characteristics of High-Nitrogenous Steel

Experimental study on the effect of strain rate on discontinuous flow and mechanical characteristics of the high-nitrogenous steel Kh23AG19F has been performed. Within the range of strain rates from 4.62 · 10^-5 to 1.85 · 10 ^-4 s^-1, discontinuous flow, reflected by serration on the tensile diagram, is chiefly determined by intergranular deformation mechanisms. Under strain rates over 1.85 · 10^-2 s^-1, combined deformation modes prevail, which cause a change in the character of discontinuous flow and transform a serrated tensile diagram into a wavy graph, with the yield stress of steel increased significantly.     

能源实时监控与信息管理系统出现的问题及解决的方法

中国石化北京燕化石油化工股份有限公司动力事业部二供水车间电气改造完成后，能源实时监控与信息管理系统出现线路名称不统一、电流互感系数变比不起作用、数据查询功能及统计报表数据的准确性等问题，严重地影响系统的使用。通过对比分析，找到了出现问题的实质，对源代码进行修改，问题得到了解决。同时也成功地解决了其他部门遇到相类似的问题。     

七里北地区钻井工程地质特征及提高钻速的技术途径

七里北潜伏构造南邻渡口河、北邻铁山坡,这些构造均在飞仙关鲕滩钻获良好的天然气,具有很好的勘探前景。七里北1井钻探表明,该井在飞仙关地层获天然气80×104m3,但储层埋藏深度达5600m,且侏罗系地层的钻井工程地质条件与相邻构造有显著差异,钻井速度低和钻具事故多这两大问题突出,严重制约了探井钻井速度。认真分析了七里北1井的钻井工程地质特征,有针对性地提出提高飞仙关探井钻井速度的技术途径,有利于解决钻井工程面临的突出问题,对加快该地区飞仙关鲕滩气藏的勘探速度有着重要意义。     

反凝析现象对雅克拉凝析气处理工艺的影响

雅克拉凝析气田位于塔里木盆地北部，地处新疆维吾尔自治区阿克苏地区境内，它是中国石化集团公司西北分公司探明并投入开发的最大凝析气田，采用衰竭式开采。通过对井口物流的相态研究，认识了凝析气的反凝析规律，采取了提高凝析气中C^＋₃收率的方法，以确保外输干气的烃露点达到管输要求，并提高该气田开发的经济效益。在工艺方案设计过程中，通过多种工艺方案比选，确定选用膨胀机进口压力为6.0 MPa的膨胀机制冷工艺， C^＋₃收率达到92％以上，外输干气烃露点满足管输要求。     

国产风机盘管空调系统常见问题分析

分析了国产风机盘管使用中常见的问题,指出机组因风量不足、冷量风量匹配不合理以及风机盘管某些设备故障,导致了风机盘管精度低、舒适性差、能耗高等一系列问题。指出应引起空调设计和运行维护人员的注意。     

Wireless video streaming with TCP and simultaneous MAC packet transmission (SMPT)

Video streaming is expected to account for a large portion of the traffic in future networks, including wireless networks. It is widely accepted that the user datagram protocol (UDP) is the preferred transport protocol for video streaming and that the transmission control protocol (TCP) is unsuitable for streaming. The widespread use of UDP, however, has a number of drawbacks, such as unfairness and possible congestion collapse, which are avoided by TCP. In this paper we investigate the use of TCP as the transport layer protocol for streaming video in a multi‐code CDMA cellular wireless system. Our approach is to stabilize the TCP throughput over the wireless links by employing a recently developed simultaneous MAC packet transmission (SMPT) approach at the link layer. We study the capacity, i.e. the number of customers per cell, and the quality of service for streaming video in the uplink direction. Our extensive simulations indicate that streaming over TCP in conjunction with SMPT gives good performance for video encoded in a closed loop, i.e. with rate control. We have also found that TCP is unsuitable (even in conjunction with SMPT) for streaming the more variable open‐loop encoded video. Copyright © 2004 John Wiley & Sons, Ltd.     

Vapor absorption by LiBr aqueous solution in vertical smooth tubes

Heat and mass transfer in a falling film vertical in-tube absorber was studied experimentally with LiBr aqueous solution. The presented results include the effect of solution flow rate, solution subcooling and cooling water temperature on the absorption in a smooth copper tube 16.05 mm I.D. and 400 mm long. The experimental data in the previous report for a 1200-mm-long tube was also re-examined and compared. It was demonstrated by the observation of the flow in the tube that the break down of the liquid film into rivulets leads to deterioration of heat and mass transfer at lower film Reynolds number or in longer tubes. An attempt to evaluate physically acceptable heat and mass transfer coefficients that are defined with estimated temperature and concentration at the vapor–liquid interface was also presented.     

Determining the Instantaneous Effective Energy of x-Ray Tube Bremsstrahlung

A method is described for determining the instantaneous effective energy of x-ray tube brehmsstrahlung by means of two semiconductor detectors employing epitaxial GaAs structures and a measurement circuit, which together determine the effective energy with an error of 5% in the range 20–80 keV in the presence of nonlinearity in the detector response.     

提高深井硬地层钻井速度技术难点及对策

乌龙1井地层为南方海相沉积,地层古老、岩石硬度大、研磨性强、可钻性差、地层倾角大(最大为80°)井斜难以控制、蹩跳钻严重,制约了该地区深井钻井速度。文章介绍了解决提高钻井速度这一瓶颈问题,从深井优快钻井及其配套技术、硬地层钻进的钻头优选、优化钻井参数、引用新技术、新工艺、新工具等方面进行了探索,钻井速度有了大幅度地提高,对类似井具有一定的借鉴作用。     

应用时频分析方法辨识时变系统的模态参数

应用Gabor展开及Hilbert变换进行时变线性系统模态参数的辨识。利用非平稳信号的Gabor变换将结构响应信号表示在时频面上，并通过Gabor展开重构分离模态分量，建立每一阶模态的时变线性模型。对单模态时变线性模型应用Hilbert变换来辨识随时间变化的模态频率和阻尼。通过对刚度和阻尼慢变的两自由度系统模态参数的仿真辨识验证辨识方法的有效性。仿真结果表明：本文方法为时变线性系统的模态参数辨识提供了一条新的途径。