Reasons for drop in shell-and-tube condenser performance when replacing R22 with zeotropic mixtures. Part 1. Analysis of experimental findings

An experimental and theoretical investigation was made to find out the reasons for the drop in shell-and-tube condenser performance when replacing R22 with a zeotropic mixture R407C. Measurements show that at lower condenser loads the reduction in performance can be as large as 70% compared to the full condenser load. Calculation results are compared with experimental results for two different condensers, one with micro-finned tubes and one with 3-D finned tubes. Calculations show that the degree of mixing of the newly formed condensate on a tube and the drained condensate is a factor influential enough to explain the performance drop. 3-D finned tubes seem to have better mixing in the condensate than integral finned tubes.     

离心试验中基于目标摄像的位移量测技术

采用目标摄像技术在离心试验中进行土体位移测量.通过摄像机拍摄跟踪土中目标点,运用中心定位方法确定目标点的坐标.用两时间点的坐标可得该时间段内的位移矢量.介绍了测量系统和相应的纠错方法.通过一组标定试验,得出该量测方法的精度和准确度为1 mm.且在同一个离心试验中,测定土体位移与其他传感器结果一致,证明该方法运用于离心机试验有效.     

小板坯连铸机浸入式水口结构优化的模拟研究

采用物理模拟方法,以鞍钢第二炼钢厂小板坯连铸机为原型,进行浸入式水口结构参数优化实验,得到了适合鞍钢第二炼钢厂生产需要的浸入式水口结构参数,并分析了浸入式水口的结构参数对结晶器内钢液流动状况的影响。     

基于支持向量机的电力客户信用评价

结合我国电力客户基本情况,建立了电力客户信用评价指标体系。首先对定量指标进行无量纲化处理,用梯形模糊数表示描述定性指标的语言变量,并用梯形模糊数的μ-期望值将其明确化为确定的非模糊价值量。最后运用支持向量机对电力客户信用进行评价,借助于支持向量机工具箱OSU_SVM3.00,在Matlab6.5中予以实现。实验结果表明该方法是用于电力客户信用评价的有效方法。     

Temperature of the Limiter Surface Measured by IR Camera in HT-7 Tokamak

Temperature measurement by IR （infrared） camera was performed oll HT-T tokamak. particularly during long pulse discharges, during which the temperature of the hot spots on the belt limiter exceeded 1000℃. The heat load on the surface of the movable limiter could be obtained through ANSYS with the temperature measured by IR-camera. This work could be important for the temperature measurement and heat load study on the first wall of EAST device.     

基于Zigbee技术的无线抄表系统的设计

为了改善原有抄表系统存在的诸多不足,文章以ZigBee技术为核心,用C8051F021单片机作为网络终端节点和网络协调器的MCU,采用CC2420为射频芯片,搭建基于Zigbee技术的无线抄表系统.主控MCU通过SPI接口与无线收发模块的CC2420芯片进行通信,给出采集器的收发流程和抄表系统的无线通信流程.该抄表系统具有结构简单、可靠性高、实用性好的特点.     

微胶囊技术在啤酒生产中的应用研究

介绍了微胶囊固定化啤酒酵母细胞的原理以及研究了影响微胶囊稳定性的几个关键因素,阐述了微胶囊技术在啤酒连续生产应用中的可行性,结果表明连续发酵生产的啤酒与分批发酵相比,风味、口感都比较接近.     

Australian project time‐cost analysis: Statistical analysis of intertemporal trends

In statistical analysis of intertemporal movements in time–cost relationships via the Bromilow model it is shown that for Ng et al.’s (2001) Australian data, the K value is not significantly different from unity. This is utilized to develop a new and simpler ratio measure of the time–cost relationship, which has the advantage of being obtainable for each project. A scatter plot and a statistical analysis of the project ratios indicate significant yearly fluctuations but no underlying trend. Assuming similar characteristics of the data from previous studies, equivalent average ratios are estimated and plotted, confirming Ng et al.’s visual appearance of a possible downward trend. However, the statistical analysis is inconclusive on the issue, there being insufficient data (six points) for a full analysis.     

200kt/a甲醇精馏系统的优化设计

以粗甲醇为原料,采用四塔精馏工艺,基于Aspen Plus工艺模拟软件,对甲醇精馏系统进行模拟优化设计及塔器水力学计算;运用EDR换热器设计软件,对本装置的换热器进行选型计算。模拟计算结果表明,精甲醇产品纯度为99.99%(wt)、甲醇收率为99.67%、蒸汽单耗为1.09t、循环冷却水单耗为83.24t,产品质量符合GB 338-2011国标优等品及美国联邦AA级标准质量要求,装置能耗水平达到国内先进水平。