Wiped-Film Molecular Distillation Process

Based on the Bhatnagar-Gross-Krook distillation for two components in the presence equation, a new scheme of wiped-film molecular of inert gas is developed. The equations in the scheme are solved numerically by the method of finite difference and iteration. The new scheme is used to simulate the molecular distillation of dibutyl phthalate and dibutyl sebacate （ DBP-DBS ） mixture. The effects of the inert gas pressure, the distance between the evaporation surface and condensation surface, the rotation rate of blade, and the number of blades on the distillation rate and separation factor are discussed.     

Studying on the increasing temperature in IT-SOFC： Effect of heat sources

The dimensions and the materials type limit the performance of fuel cell. The increase of the temperature in electrodes and electrolyte of the cell,is due to the over potential of activation (transfer of load),the over potential Ohmic (resistance of polarization),the over potential of reaction (heat released by the chemical reaction) and the over potential of diffusion. In this paper,we studied the thermo-electrical performance of an intermediate temperature solid oxide fuel cell (IT-SOFC) with electrode supported. The aim of this work is to study this increasing temperature of a single cell of an IT-SOFC under the influence of the following parameters: heat sources,functioning temperature and voltages of the cell,geometric configuration and materials type. The equation of energy in one dimension is numerically resolved by using the method of finite volumes. A computing program (FORTRAN) is developed locally for this purpose in order to obtain fields of temperature in every element of the cell.     

Effect of vacuum degree and aeration rate on sludge dewatering behavior with the aeration-vacuum method

Due to large-scale dredging operations, a large amount of sludge is inevitably produced. Large areas of land are occupied when the dredged sludge is discarded in the disposal site as waste material. The sludge dewatering with aeration-vacuum (SDAV) method is suit for treating the sludge with high water content and high clay content in the disposal site. The water in the sludge can be discharged out. The volume of the sludge can be reduced quickly, and the recycling of the land can be accelerated by this method. Most importantly, this technique is an efficient way to deal with clogging problems when pumping water from high water content, high clay content dredged sludge. Vacuum degree range tests, the aeration rate range tests, and the influencing factors of sludge dewatering behavior tests were conducted with a self-developed SDAV model test device. Sludge samples were taken from the South-to-North Water Diversion East Line Project in Huai’an White-Horse Lake disposal site, Jiangsu Province, China. The optimal range of vacuum degree and aeration rate were obtained through the test results, and the mechanisms for how the two factors work and how they affect the sludge dewatering behavior were analyzed. The suitable vacuum degree range in SDAV is below 50 kPa, and the suitable aeration rate is about 1.0 m3/h. The low-vacuum degree contributes to reduce the ad-sorption effect of micro-channels on soil particles in filter material and to maintain the arch structures. Aeration has the effects of expansion, disturbance, changing Reynolds number, and dynamic sieve separating. The pump quantity of water per meter of filter tube (m) has different change rules as the vacuum degree changes under different aeration rates. The reason is that the formed arch structures’ conformation and permeability differ greatly under different combined-conditions of vacuum degree and aeration rate. The optimal combined-condition for dewatering the sludge is 35 kPa with 1.0 m3/h.     

A study of optimal switching problem in limited-cycle with multiple periods

In a social system or production line,the restrictions of the cost and the due-time exist in each period.Generally,whether these restrictions are satisfied is dependent not only on the risks of this period,but also on the risks generated beforehand.We consider controlling the production process by switching the processing rate to a faster one at a given period.This paper deals with the optimal switching period to minimize the total expected cost of the production process.We first propose the optimal switching period model,and then the mathematic formulation of the total expectation is presented.Finally,the policy of optimal switching period is investigated in detail by numerical experiments.     

Effect of a biological activated carbon filter on particle counts

Due to the importance of biological safety in drinking water quality and the disadvantages which exist in traditional methods of detecting typical microorganisms such as Cryptosporidium and Giardia, it is necessary to develop an alternative. Particle counts is a qualitative measurement of the amount of dissolved solids in water. The removal rate of particle counts was previously used as an indicator of the effectiveness of a biological activated carbon （BAC） filter in removing Cryptosporidium and Giardia. The particle counts in a BAC filter effluent over one operational period and the effects of BAC filter construction and operational parameters were investigated with a 10 m^3/h pilot plant. The results indicated that the maximum particle count in backwash remnant water was as high as 1296 count/ml and it needed about 1.5 h to reduce from the maximum to less than 50 count/ml. During the standard filtration period, particle counts stay constant at less than 50 count/ml for 5 d except when influenced by sand filter backwash remnant water. The removal rates of particle counts in the BAC filter are related to characteristics of the carbon. For example, a columned carbon and a sand bed removed 33.3% and 8.5% of particles, respectively, while the particle counts in effluent from a cracked BAC filter was higher than that of the influent. There is no significant difference among particle removal rates with different filtration rates. High post-ozone dosage （〉2 mg/L） plays an important role in particle count removal; when the dosage was 3 mg/L, the removal rates by carbon layers and sand beds decreased by 17.5% and increased by 9.5%, respectively, compared with a 2 mg/L dosage.     

英格兰——男性穿裙之地(英文)

Most of us are used to the fact that skirts are basically worn by human females. We do not realize that Scotland is the land that has skirts traditionally worn by men and boys. It is, indeed, a practice of the Scottish male not to be embarrassed when he wears the Scottish kilt , which is actually a beautiful skirt.Long ago, in the land, it was common for Scottish men and boys to use skirts. It was mainly male performers that used them. The practice spread far and wide. Later, it gained favour with the Scottish royalty, especially when kilts were used by the Scottish male bagpipers at court. A bagpipe is a blowing instrument.The Scottish kilt is one of the national of Scotland. Therefore, it is not uncommon to see in Scotland a male using it on himself and feeling proud of it.     

An integrated classification method for thematic mapper imagery of plain and highland terrains

The classification of thematic mapper imagery in areas with strong topographic variations has proven problematic in the past using a single classifier, due to the changing sun illumination geometry. This often results in the phenomena of identical object with dissimilar spectrum and different objects with similar spectrum. In this paper, an integrated classification method that combines a decision tree with slope data, tasseled cap transformation indices and maximum likelihood classifier is introduced, to find an optimal classification method for thematic mapper imagery of plain and highland terrains. A Landsat 7 ETM＋ image acquired over Hangzhou Bay, in eastern China was used to test the method. The results indicate that the performance of the integrated classifier is acceptably good in comparison with that of the existing most widely used maximum likelihood classifier. The integrated classifier depends on hypsography （variation in topography） and the characteristics of ground truth objects （plant and soil）. It can greatly reduce the influence of the homogeneous spectrum caused by topographic variation. This integrated classifier might potentially be one of the most accurate classifiers and valuable tool for land cover and land use mapping of plain and highland terrains.     

Investigation on hot deformation behavior of AZ31 madnesium alloy

The hot compressive deformation of extruded AZ31 magnesium alloy with the mass fractions of Al and Zn equal to 3%and 1% respectively is studied by a Gleeble-1500D thermal mechanical simulator over the temperature range from 200℃to 400℃ and the strain rate from 10^-3 s^-1 to 10^0s^-1.The true stress-strain curves of the strain of 65% are tested.The deformation activation energy is obtained and the flow stress model is established by analyzng the effects of strain rate and temperature on the flow stress.Zener-Hollomon parameter is introduced to describe the softening behaviors of AZ31 magnesium alloy resulted from dynamic recrystallization during the hot compressive deformation,whose natural logarithm is linear with the critical strain of dynamic recrystallization.     

Land degradation, government subsidy, and smallholders' conservation decision: the case of the loess plateau in China

Land degradation is one of the severe environmental problems in China. In order to combat land degradation, a soil conservation program was introduced since 2000 to reduce soil erosion by converting slope-cultivated land into forestry and pasture. This paper represents the first systematic attempt to investigate the impact of the soil conservation program on land degradation in the loess plateau. The results indicate that the soil conservation program to convert slope fields into forest or pasture is an effective way to combat soil erosion. However, a subsidy that is higher than profit of land use activity of slope fields before their conversion into forest and pasture is needed to encourage farmers to join the conservation program. A policy measure to encourage and assist farmers to develop sedentary livestock by using crops produced from fields as well as fodder and forage grass from the converted slope fields might contribute to combat soil erosion. Increase in off-farm job opportunities may encourage     

A case study on mathematics anxiety for mathematics of finance course

The DIIA （Diploma in Investment Analysis） students from the FBM （Faculty of Business Management） were required to undertake several MOF （Mathematic of Finance） courses. The passing rates for all of the MOF courses were good except for one course. There are many factors for this low passing rate phenomenon for this particular MOF course. One of the factors is mathematics anxiety as suggested by Richardson in 1971. As a result, this paper is carried out in order to measure the undergraduates＇ level of mathematics anxiety in general and between genders in this one particular course. The outcome is expected to fill in the gap as study of anxiety in MOF is still lacking. A 30-item MARS （Mathematics Anxiety Rating Scale） is adapted and used in this study, because this course is predominant by complex computations. The Ss （samples） of the study are 119 students who undertook this MOF course during the study semester of December 2008 to April 2009 in UiTM （Universiti Teknologi MARA）. It is expected that the findings will show that the Ss have a considerably high mean for mathematics anxiety; and female students have a higher mean of mathematics anxiety as compared to their male counterparts. The study confirms the expectation of the researchers. In terms of the final and overall results, it was expected that the passing percentage be dominated by the male students. However, at the end of the study, the overall performance of the female students was much better compared to their male counterparts.     

同尺寸弯振圆盘辐射声场指向性研究

对薄圆盘的弯曲振动和辐射声场的特性进行了研究,推导出了三种边界条件下圆盘辐射声场指向性的数值表达式,编制程序并研究其声辐射特性。结果表明,相同尺寸不同边界条件下圆盘指向性的尖锐程度不同,固定边界条件下圆盘辐射声场指向性最佳,自由边界条件下较差,并且随着圆盘模式和几何尺寸的增加各边界条件下圆盘的指向性均逐渐变差。     

平板层流边界层的新速度分布函数

采用积分关系式方法求解平板层流边界层问题,在满足基本边界条件的基础上提出以雅克比椭圆正弦函数作为新的近似速度分布函数,用最小二乘法确定函数中的待定系数.分析表明新分布函数精度有明显提高,且形式简单,便于工程应用。     

3D couette flow of dusty fluid with transpiration cooling

INTRODUCTION Transpiration cooling is a very effective process to protect certain structural elements like combustion chamber walls, exhaust nozzles, or gas turbine blades in turbojet and rocket engines, from the influence of hot gases. In view of this, Eckert (1958) obtained an exact solution of the plane couette flow with transpi-ration cooling. The problem remained 2D due to the uniform injection and suction applied at the porous plates. Flow and heat transfer along a plane wall with…     

Study on performance of a packed bed latent heat thermal energy storage unit integrated with solar water heating system

INTRODUCTION Efforts of rational and effective energy man-agement, as well as environmental considerations, increase the interest in using renewable energy sources, especially solar energy. Because of discrep-ancy between the energy supply and demand in solar heating applications, a thermal energy storage (TES) device has to be used for the most effective utilization of the energy source. Energy storage combined with solar collectors and photovoltaic systems have been developed over the…     

换热器对平板型太阳热水系统热性能的影响分析

分析了换热器对集热器效率的影响,确定了换热器对集热器的削弱因子;提出了二次换热平板型太阳热水系统的能量方程。对自然循环二次换热平板型太阳热水系统系统的热性能进行了测试与分析,测试表明,自然循环二次换热平板型太阳热水器的平均日效率低于普通平板型太阳热水器,但高于真空管太阳热水器。     

页岩气钻采井口平板阀的设计

阐述了页岩气钻采井口平板阀的工作原理、结构特点和性能特性。基于API 6A规范设计和平板阀的设计计算公式,该阀采用单阀板浮动阀座结构,使用液压作为阀门开关驱动力,并在阀板和阀座密封副上热喷涂硬质合金涂层,使其具有耐高压、耐磨损、密封性好的特点。     

热阻和回热损失对太阳能驱动的埃里克森热性能的影响

中建立太阳能驱劝的埃里克森热机系统的一般循环模型，探讨回热损失的内不可逆性因素对其循环效率和集热器最佳工作温度的影响，导出系统的最大效率和太阳能集热器的最佳工作温度，所得的结论对此类循环的研究提供新的理论依据。     

U型真空管集热器温度场的模拟分析

建立和分析了U型真空管集热器的热效率的表达式,并在FLUENT中建立动态仿真模型,利用模型分析了U型管的入口流速和结构尺寸、太阳辐照度对真空管内温度场的影响.结果表明:减小入口流速和U型管内径、增加太阳辐射量和U型管的长度都可以使真空管的出口平均温度增高.该分析结果可对U型玻璃真空管的优化设计、参数匹配等方面提供理论支撑.     

EL型电力机车受电弓控制电路的改造

在EL型电力机车的受电弓控制电路中增加了安全升弓装置和安全落弓装置,使受电弓的控制功能得到进一步完善,从而杜绝了由于电弓控制不合理所造成的人身伤亡和设备事故。     

扩散吸收式制冷系统中板式换热器综合传热性能分析

在一种太阳能驱动、采用喷雾吸收器并以板式换热器作为主要换热部件的LiNO3-NH3-He三工质扩散吸收式制冷系统中,根据试验测得的运行参数,以溶液的p-t-x西方程及物性方程、传热基础理论等为依据,提出了计算溶液换热器中溶液流量的方法,并利用综合传热系数k、传热单元数N_TU与换热器效率s研究了板式换热器作为LiN03-NH3-He扩散吸收式制冷系统发生器、冷凝器、溶液热交换器、溶液冷却器时的换热性能．试验与分析表明,板式换热器的换热面积及其内部流道中的流量（流速）对其综合传热性能具有较大影响;在介质流量一定时,板式换热器不宜考虑过大的面积预留量;板式溶液换热器内部流道宜采用多流程布置形式以强化传热、提高换热效率．