Cetane number effect on the energetic and exergetic efficiency of a diesel engine fuelled with biodiesel

This study presents the energy, exergy and heat release analysis of a John Deere 4045 T 4.5 L, four-stroke, four-cylinder, turbocharged diesel engine. The engine was run with four different types of fuel: yellow grease methyl ester (YGME); soybean oil methyl ester (SME); and soybean oil methyl ester containing either 0.75 or 1.5 w/w % of the cetane improver 2-ethylhexyl nitrate (SME-0.75%EHN and SME-1.5%EHN, respectively). The engine was tested at 1400 1/min under a full load of 352 Nm. For reliability, the fuels were tested three times, and the mean values were compared using different statistical techniques. The objective in this study was to determine the effect of cetane number and ignition delay on the energy and exergy efficiencies of an internal combustion engine and to compare the results for the types of fuel stated earlier. The average thermal efficiency was approximately 40.5%, and the exergetic efficiency was approximately 37.3%. The mean exergetic efficiencies of the fuels were in the order ψ_SME > ψ_SME-0.75%EHN > ψ_SME-1.5%EHN > ψ_YGME. There were significant differences among the mean values according to Student's t-tests. It is concluded that a lower cetane number, a longer ignition delay period and a higher level of premixed combustion may increase the exergetic efficiency of a diesel engine.     

特性曲线在螺杆泵井工况诊断中的应用

介绍了螺杆泵油井泵工作区域的划分及工况的类型。结合某采油厂两口井,运用所编制的程序软件对其进行了特性曲线的绘制,便于提早发现泵的工作状况,采取相应技术措施,减少经济损失。     

基于综合效率的高层公租房建筑设计研究

建设高层公租房住宅是中国政府现阶段解决中低收入阶层居住问题的一个重要途径.影响高层公租房建筑综合效率的因素有很多,本文主要从单体设计层面出发,分析标准层的平面规模、公共交通空间配置以及套型灵活度这三个重要的影响因素.在当下公租房大量建设的时期,希望通过研究高层公租房建筑设计的综合效率的要点和原则,分析存在问题、总结设计经验、归纳设计方法,为其设计提供参考.     

大型公共建筑中央空调能耗优化控制系统的方案应用与节能测试

本文针对舟山市岱山县行政中心的中央空调运行状况,根据业主提出的设备节能与高可靠性运行等需求定制解决方案,通过能耗优化控制系统提高中央空调的整体运行效率,在节能对比测试中证明了预定的节能目标,最后就此系统的应用和节能测试进行了总结,希望有利于推动大型公共建筑中央空调的节能改造业务发展。     

非正方形四叉树变换系数能量分布模型及其扫描方式改进

传统的非正方形四叉树变换(NSQT)系数的扫描方式并不能很好地适应系数的能量分布,这将降低熵编码的编码效率。为了提高编码效率,该文提出非正方形四叉树变换系数能量分布模型,并改进了其系数扫描方式。首先推导了非正方形变换块的空间频率域位置分布,基于推导的分布,从理论上提出了其能量分布模型,并用实验进行了证实,发现能量从左上角到右下角逐渐递减,而左下角的能量与右上角的能量接近,根据该能量分布模型,重建了非正方形四叉树变换中量化系数的扫描模式,以适应熵编码,而熵编码中的系数扫描方式倾向于系数上的降序。实验结果显示,相比NSQT中已有的系数扫描方式,该文方法提出的扫描方式在编码计算复杂度和客观视频质量损失可忽略的前提下,平均下降了1.32%~3.74%的比特率,对于非正方形变换块,下降了9.05%~13.19%的比特率。     

Observation of an FEL efficiency increase caused by magnetic field tapering of the undulator

The aim of the present work is to investigate the influence of a tapered undulator on the main parameters of an free electron laser (FEL). The experiments were carried out at the Darmstadt FEL at an electron beam energy of 31 MeV and a wavelength of 7 μm. The effect of tapering depth on various important free electron laser characteristics such as the wavelength corresponding to the peak of the spectral distribution, the spectral width, the small signal gain and the electron energy extraction efficiency has been experimentally observed and quantitatively understood. It is shown for example that the wavelength shift is well described taking into account short pulse effects. Furthermore, for the first time, it has been found that for some values of the tapering depth the FEL efficiency exceeds that of the uniform undulator by more than 35% and 18% for negative and positive tapering, respectively. The experimental data of the spectral distributions for different tapering values are compared with predictions based on simulations for the interaction processes in the tapered undulator and with the experimental results recently obtained at the IR DEMO FEL at the Thomas Jefferson National Accelerator Facility.     

α－Si：H磷掺杂固相效率和相关分配系数

证明了分配系数ｄ是气相浓度Ｘｐ（ｇ）的解析函数，其系数由α－Ｓｉ：Ｈ生长期间界面上固／气相平衡反应常数决定。ｄ这种性质导致磷掺杂固相效率可藉助Ｘｐ（ｇ）进行解析计算。     

Cost Savings in the Ozone Treatment of Paper Mill Effluents Achieved By a Closed-Loop Ozone Control System

Control strategies were created to reduce the operating costs of ozone stages of effluent treatment plants in paper mills as well as to improve the quality of the effluent. Biologically treated effluents from five mills were subjected to laboratory and pilot tests. All COD target values could be reached and maintained with SAC-based control strategies. Disturbing events were compensated with a deviation of only 2% within maximum 3.1 volume exchanges, depending on the kind of event. The SAC (spectral absorption coefficient) was found to be highly suitable for controlling the ozone dosage. In a SME paper mill, 20% of the operating costs of an ozone plant can be saved. The return on investment for such a system is thus about 8 months.     

用^252Cf自发裂变中子源刻度中子探测器效率

使用标准的Ｍｏｎｔｅ－Ｃａｒｌｏ程序计算了几种闪烁中子探测器的效率曲线，同时又用＾２５２Ｃｆ自发裂变中子源中子对效率曲线的低能部分进行了实验刻度。通过实验值对计算值归一把刻度点与计算曲线结合起来，按照实验点的走向修正了计算效率曲线的近阈部分。文章着重叙述实验刻度的技术。     

高效深磨的最新发展与技术分析

分析了超高速条件下高效深磨的理论基础，概述了国外在高效深磨技术方面的发展状况，对高效深磨的相关技术进行了探讨并指出我国开展此技术研究的潜力。