吸油烟机风量检测中可靠性分析

根据GB/T 17713-2011的要求,对外排式吸油烟机空气性能实验装置的板孔的设计进行了研究,结合板孔系数表,提出了与实际工作点最接近的计算方法,以设计的孔板测量外排式吸油烟机的风量。并根据实际的检测实例,找出了实际影响因素,提高了风量检测的可靠性。     

两种不锈钢在冷却塔冷凝酸液中的耐蚀性能

目的分析304不锈钢和316L不锈钢在电厂冷却塔内海水及烟气形成的模拟冷凝酸液环境中的耐蚀性能。方法利用浸泡试验和电化学试验方法测试两种不锈钢在模拟冷凝酸液中的腐蚀形貌、腐蚀率和极化曲线。结果 304不锈钢在模拟冷凝酸液中的耐蚀性能较差,其腐蚀率及钝态稳定性受冷凝酸液pH值的影响较大;316L不锈钢在模拟冷凝酸液中的耐蚀性能较好,其腐蚀率及钝态稳定性受冷凝酸液pH值的影响较小。结论 316L不锈钢在冷却塔冷凝酸液中的耐蚀性能明显优于304不锈钢。     

泥石流危险范围的模型实验预测法

泥石流危险范围的模型实验预测旨在确定一次泥石流可能堆积泛滥的最大范围.通过泥石流不同冲出量、堆积区坡度和容重的31次模型实验,获取了泥石流堆积面积.最大堆积长度、宽度和厚度的实验数据.采用量纲分析方法,建立了一次泥石流危险范围的预测模型,并由实验资料确定了模型的修正系数.在云南和甘肃的应用实践表明,预测模型精度高,适用范围广,可在我国泥石流危险范围预测预报中使用.     

MIXING INDUCED BY AN INTERNAL HYDRAULIC JUMP1

ABSTRACT The efficiency of an inverted internal hydraulic jump as a mixing and dispersion mechanism in an aquatic environment was examined. The flow considered was a two-dimensional buoyant flow from a shallow channel over a sloping bottom into a deep reservoir. It could be seen that a rapidly varied flow associated with violent turbulent mixing occurred near the point of discharge if specific discharge conditions and downstream controls were met. Downstream from the mixing zone the flow was stably stratified. The main object of the study was to find the conditions under which a turbulent mixing zone occurred and the rate of turbulent entrainment. Energy loss and length of the mixing zone were also investigated. The independent variables were the outlet densimetric Froude number, the density differential between outfall water and receiving water, the relative depths of the upper and lower layers in the stratified flow portion, the total depth, and the slope of the transition. Theoretical calculations had to be confined to a step increase in depth, but experiments in a laboratory flume showed that results obtained with slopes of 23° and 90° were quite similar. Both theory and experiments showed, for example, that dilution (entrainment rates) up to 2:1 (2 parts heated water to one part cold water) can be achieved at very little energy expense and with downstream depths approximately 8 times the outlet depth. Theoretically, any amount of dilution can be obtained, but large depths may be required. Experimental results also indicate that the length of the mixing zone was frequently ten times the value of the outlet densimetric Froude number.     

化学清洗技术在安钢D900风机冷却系统的应用

利用化学清洗技术，对风机循环系统、油冷却系统进行杀灭微生物、除垢、去锈、管壁钝化、预膜处理，既保证了高炉的正常生产，又延长了风机的使用寿命。     

沙堆模型动力学特性与灾害系统演化预测研究

基于自组织临界性的理论框架,针对处于周期区与混沌区之间状态的灾害系统,研究其可预测性及预测方法.通过均匀和非均匀沙堆对比实验,发现两类沙堆模型表现出两种动力学行为--自组织临界性和准周期性.采用时序分析、功率谱分析和R/S分析等多种方法分析了两类系统的演化行为,反映了灾害系统的可预测特征;进一步提出了灾害预测的几个研究方向及方法.最后以极值统计法为例,介绍了其在两类灾害预测中的应用.     

SOLUTE TRANSPORT IN THREE‐DIMENSIONAL SATURATED POROUS MEDIA HAVING SELF‐SIMILAR HYDRAULIC CONDUCTIVITY DISTRIBUTION1

ABSTRACT: Customarily, it has been assumed that hydraulic conductivity is a stationary, homogeneous stochastic process with a finite variance for stochastic analysis of solute transport in the subsurface. That the distribution of hydraulic conductivity may have a fractal behavior with long range correlations was suggested from field data analyses. This motivates us to further investigate how the fractal behavior of permeability distribution impacts solute transport in porous media. This study provides longitudinal and transverse macrodispersivity coefficients and the variance of the solute concentration. Longitudinal and transverse macrodispersivity coefficients are found to depend strongly on the fractal dimension (D) of logarithmic hydraulic conductivity (logK). The longitudinal and transverse macrodispersivity coefficients are the highest when D = 1, and the values decrease monotonically to zero at D = 2. Both coefficients correspond to the characteristic length scale of the logK distribution, thus are scale dependent parameters. The ratio of the transverse to the longitudinal macrodispersivity coefficient is on the order of 10^‐1 to 10^‐4. Concentration variance also decreases with the fractal dimension of logK. There is no spatial spreading of solute for D = 2, and the concentration variance reaches zero for this case.     

细水雾灭油池火时各种影响因素的相对重要度分析

采用实验的方法并与理论分析相结合，对细水雾在扑灭B类火时，占主导地位的灭火机理进行了研究。实验中发现，当液体燃料的闪点相差较大时，其灭火机理往往不尽相同。并且当细水雾的雾特性相差较大时，在灭火中起主导作用的灭火机理常常也各有不同。因而那种单纯以雾滴的粒径分布作为细水雾扑灭燃料闪点较高的油池火时，雾滴的动量分布对细水雾的灭火有效性影响更大。为此，本文还建立了一个简单的模型，试图得到在这种火灾场景下，对细水雾灭火的临界动量要求。     

Evaluating the usability of a commercial cooling vest in the Hong Kong industries

Objective. The provision of appropriate personal cooling vests is recognized as an effective measure to combat heat stress. However, personal cooling vests are not widely implemented in the Hong Kong industries. The current study aims to evaluate the usability of a hybrid cooling vest that is associated with the success of its application in industrial settings. Methods. A self-administrated questionnaire focusing on 10 subjective attributes of cooling effect, ergonomic design and usability of a hybrid cooling vest was administered with 232 occupational workers in the construction, horticultural and cleaning, airport apron services and kitchen and catering industries. Results. A structural equation model estimated by analysis of moment structures was constructed to evaluate the usability of the cooling vest, as influenced by cooling effect and ergonomic design. Results showed that cooling effect (path coefficient?=?0.69, p?p?Conclusions. The structural equation model is feasible to examine the complex nature of the structural relationships among the subjective perceptions of personal cooling vests. The empirical findings furnish sound evidence for further optimization of the hybrid cooling vest in terms of cooling effect and ergonomic design for occupational workers.     

火电厂冷却池热污染治理初探

通过系统的模型试验,以色水为示踪剂模拟热水,探讨排、取水口分列式布置的三维时间连续点源如何采用工程设施转换成无限长二维面源,以利用水面热交换解决火电厂冷却池热污染的治理问题。给出了出流近区流速分布及流量沿程变化的近似计算式。此研究成果对挖掘冷却池散热潜力,增加电厂装机容量具有实用推广价值