多工质小型制冷装置动态仿真

本文根据“制冷系统热动力学”的观点，对采用不同工质的小型制冷装置进行了理论与实验研究。仿真结果与有关实验数据较为吻合，验证了理论模型的通用性和准确性。根据研究结果分析和讨论了采用新工质后对系统的影响和要求。

应用多工质朗肯循环提高火电厂效率

由于水蒸汽的热力性质所限制,常规火力发电厂应用的水蒸汽朗肯循环效率大大地低于同温差下的卡诺循环效率。在现代技术条件下;其效率一般在42%以下,而采用钾-联苯—水蒸汽三工质朗肯循环,或采用钾-水蒸汽二工质朗肯循环可使火电厂热效率提高到50%以上,能节约燃料35%左右,同时也大大地减轻了火力发电厂对环境的各种污染。在多工质朗肯循环中,必须根据各工质的热力学性质优化选择各工质的参数,充分发挥循环特性接近卡诺循环的作用,同时应解决好泄漏问题和选用合适的耐高温材料。在燃料价格及年运行小时较高时,多工质朗肯循环还是有较好的经济性。

多工质高温高速套装转子优化设计

文章论述了一种用于第四代核电钍基熔盐堆的高温透平转子评估过程,该转子需同时满足氦气、氮气、空气等多种不同工质的运行要求,从氦气、氮气、空气不同工况下的多种状态进行详细说明,并对转子结构优化进行评估,以满足设备运行要求。

结构和工质对ECR离子源引出束流的影响规律研究

提高离子源引出束流是提高电子回旋共振离子推力器(ECRIT)性能的重要途径,而离子迁移距离、磁路结构和气体工质等因素对引出束流有着密切的影响。利用具有不同栅极安装位置和磁体长度的离子源,通过实验研究,分析磁路、离子的迁移距离以及工质对引出束流的影响。实验结果表明:磁体长度过短会引起ECR区的不连续分布从而造成离子源性能大幅度下降,增加磁体长度在高流量下有利于提高栅极引出束流,低流量下会使束流降低;栅极安装环长度对引出束流的影响规律与离子源的磁路结构和工作状态有关,在气体流量较低时,更长的安装环有利于提高引出束流,高气体流量条件下,不同的磁路结构会使栅极安装环对引出束流产生不同的影响规律;氙工质可以明显提高低流量条件下离子源的引出束流和放电稳定性,但在高流量下受进气位置影响,中性粒子过于聚集而造成自由电子能量积累受到影响,从而会出现束流下降的现象。

Preparation of Nd-doped gadolinium-gallium garnet laser ceramic powder by sol-gel method

Preparation of Nd3+:Gd3Ga5O12 polycrystalline material by sol-gel method was preparated in this paper.The structure and the pattern of the sample were analyzed by thermogravimetric analysis and differential thermal analysis（TG-DTA）,Infrared spectrum,XRD,TEM and electron spectrum,which indicated that the powder with good characteristics of 70-100 nm can be obtained by sintering at 1 000℃.It was shown that the chemical composition of the sample was agreed with experimental requirements by electron spectrum analysis.

Model test of the overburden deformation and failure law in close distance multi-seam mining

Based on characteristic of the associated mining of multi-coal seam and the engineering geological characteristics of overburden,the mining impact pattern of multi- seam mining and the dynamic fracture mechanism of overburden were characterized by applying the engineering geological mechanical model test.The related strata movement parameters and influence area of multi-seam mining were obtained,the strike boundary angle is 61°,the full extraction coefficient is 0.93,the greatest subsidence angle is 81°,the horizontal movement factor is 0.38,the deviation of inflection point/mining deep is 0.11. The development height of caving zone and water flowing fractured zone of multi-seam mining were calculated,is 32 m and 81.5 m separatly.The assess of influence degree of coal layer safety mining is that,there exists the possibility of water and sand inflow when mining,some messures for mine water prevention and control should be used,and the mining thickness should be local strictly limit.

Shortcut Procedure for Inverted Batch Distillation Column (I) Multicomponent Ideal System

Inverted batch distillation column(stripper) is opposed to a conventional batch distillation col-umn(rectifier). It has a storage vessel at the top and products leave the column at the bottom. The batch stripper is favourable to separate mixtures with a small amount of light components by removing the heavy components as bottom products. In this paper, we are presenting a shortcut procedure based on our earlier work for design and simulation of the inverted batch distillation column, which is equivalent to the Fenske-Underwood-Gilliland procedure for continuous distillation. Given a separation task, we propose to compute the minimum number of stages(Nbmin) and the minimum reboil ratio(Rbmin) required in a batch stripper,which are the stages and reboil ratio required in a hypothetical inverted batch distillation column operating in total reboil ratio or having an infinite number of stages, respectively. Then, it is shown that the performance of inverted batch columns with a finite number of stages and reboil ratios could be correlated in Gilliland coordinates with the minimum stages Nbmin and the minimum reboil ratio Rbmin.

Influence of ginseng cultivation under larch plantations on plant diversity and soil properties in Liaoning Province,Northeast China

Currently, transforming the mode of forest management and developing multiple forest management practices are actively encouraged in China. As one forest management type, ginseng cultivation under larch plantations has been developed significantly in the east of Liaoning Province. However, research on the influence of the ecological environment for this mode of production is still deficient. Based on this, our study compares the plant diversity and soil properties in the ginseng cultivation under larch plantations(LG) with larch plantations(LP) and natural secondary forests(SF). First, we randomly selected three plots for each of the three stand types which have similar stand characteristics; then, we carried out a plant diversity survey and soil sampling in each of the nine plots. The results show that no significant difference was found in plant diversity between LG and LP, but theevenness of herbs was significantly lower in LG than LP. No obvious changes in soil physical properties were found in LG, but a significant decrease in most of the soil nutrient content was presented in LG. Furthermore, we found a correlation between plant diversity(H') and soil properties in the three kinds of stand types, especially between herbaceous plant diversity and soil properties. We conclude that ginseng cultivation under larch plantations has no obvious effect on plant diversity, except the herbaceous evenness. Soil fertility can be depleted significantly in LG, but physical structures are not affected. Moreover, maintaining the diversity of herbaceous plants and controlling the density of ginseng cultivation in LG by farmers are important for the ecological environment. Based on this study and its good comprehensive benefits and with the support of policy, we think this forest management type should be promoted moderately in the region.

Intelligent compaction theory of high roller compacted concrete dam

The concept and realization process of intelligent compaction for the construction of high roller compacted concrete dam were presented, as well as the theory of monitoring and intelligent feedback control. Based on the real-time analysis of the compaction index, a multiple regression model of the dam compactness was established and a realime estimation method of compaction quality for the entire work area of roller compacted concrete dam was proposed finally. The adaptive adjustment of the roiling process parameters was achieved, with the speed, the exciting force, the roller pass and the compaction thickness meeting the standards during the whole construction process. As a result, the compaction quality and construction efficiency can be improved. The research provides a new way for the construction quality control of roller compacted concrete dam.

Study on Standardized Work Suitable for Smaller Enterprises

Many smaller manufacturers utilize production systems such as ＂individual production＂ and the ＂production of many models in small quantities.＂ In the processes for the ＂production of many models in small quantities＂ by multi-skilled workers, a manufacturer cannot make good use of the management method with standardized work tables used by large enterprises. Thus, it is necessary to develop ways to f＇md standardized work that is suitable for smaller enterprises. Therefore, we investigated two kinds of factories that utilized flexible manufacturing procedures for the ＂production of many models in small quantities,＂ and considered their work instructions, work contents, changeover methods, workers＇ abilities, etc. One of the compared processes was a case where there was defined standardized work, which was not observed. In the other, a QA （quality assurance） network was created to guarantee the quality. Based on the investigation results, we formulated improvement plans, had the supervisors review them, and clarified the characteristics of their problems. The results revealed areas where much attention was required to find standardized work for such processes. In addition, we made it possible to support the specification of difficult tasks and the renewal of standardized work by extending a standardized work table for the entry of workers＇ actions. This paper reports a method to define and make good use of standardized work tables and standardized work combination tables, i.e., a way to find and use standardized work based on the results of the previously mentioned factory investigation.

Regional diversity of agricultural labor productivity and its driving force in east China

China＇s eastern area is at middle and later stage of industrialization during which the relation between urban and rural areas, industry, and agriculture appears maladjusted. The main problems are shrinkage in agricultural comparative earning and lack of driving force of agricultural development. Based on calculating agricultural labor productivity in east China from 1996 to 2005, this paper analyzes contributing degree of motive forces of agriculture develop in ten provinces and cities of east China applying GCA （Grey correlative analysis）. The results show that there is no absolute correspondence between the level of industrialization and agricultural labor productivity in China＇s eastern area. There is no synchronous development between industry and agricultural labor productiviry in some areas. Fertilizer and agricultural machinery input had high contributing degree for ten years; however; contributing degree in land and irrigation work input was low. Non-materialization inputs became the leading role in most provinces and cities＇ increase of agricultural labor productivity. Modern agricultural development need non-materialization inputs as primary motive force, at the same time, direct material input and facility input as guaranteed function. For some reasons, agricultural development is characterized by ＂more direct material input, less facility input ＂ in east China now. Optimal driving.force model of future agricultural development in east China is that non-materialization inputs are dominant, that perfected facility input arc guarantee, and that certain substance inputs are necessary

Development of Porous Spherical Cellulose Bead Production from Corn Cob as an Exfoliating Agent for Cosmetic Industries

The aim of this research was to develop the porous spherical cellulose production from corn cob as an exfoliating agent for cosmetic industries. In process development of the porous spherical cellulose production from corn cob, it was found that alkaline extraction with 10% sodiumhydroxide gave 85.86% purity of cellulose and the crystallinity index of the pulp of 76.08%. Then, the obtained pulp was extracted with acid sodium chlorite. It was found that the acid sodium chlorite extraction increased the cellulose from 85.86% to 91.86%. The obtained pulp was hydrolyse dwithdilute hydrochloric solution. The result shows that the crystallinity increased from 71.13% to 86.31% with smaller crystallite size compared to that obtained acid sodium chlorite extraction. The hydrolysis pulp was used to prepare porous spherical cellulose which has homogeneous and rough surface. The porosity and pore volume of the porous spherical cellulose increased when the amount of calcium carbonate as porogen was increased. The porous spherical cellulose was prepared from the optimized conditions and the physical and chemical properties were analysed and compared with standard commercial beads （Sephadex G-25）. It was found that the porous spherical cellulose had particle size and pH value similar to the standard value. Hazardous substances such as arsenic, lead and mercury were not found in the obtained porous spherical cellulose. The consumers test shows that 87~/＇0 of consumers accepted the product and the overall complacency was great.

Comprehensive Approach for Porous Materials Analysis Using a Dedicated Preprocessing Tool for Mass and Heat Transfer Modeling

The paper presents a comprehensive, newly developed software – poROSE(poROus materials examination SoftwarE) for the qualitative and quantitative assessment of porous materials and analysis methodologies developed by the authors as a solution for emerging challenges. A low porosity rock sample was analyzed and thanks to the developed and implemented methodologies in poROSE software, the main geometrical properties were calculated. A tool was also used in preprocessing part of the computational analysis to prepare a geometrical representation of the porous material. The basic functions as elimination of blind pores in the geometrical model were completed and the geometrical model was exported for CFD software. As a result, it was possible to carry out calculations of the basic properties of the analyzed porous material sample. The developed tool allows to carry out quantitative and qualitative analysis to determine the most important properties characterized porous materials. In presented tool the input data can be images from X-ray computed tomography(CT), scanning electron microscope(SEM) or focused ion beam with scanning electron microscope(FIB-SEM) in grey level. A geometric model developed in the proper format can be used as an input to modeling mass, momentum and heat transfer, as well as, in strength or thermo-strength analysis of any porous materials. In this example, thermal analysis was carried out on the skeleton of rock sample. Moreover, thermal conductivity was estimated using empirical equations.

Analysis of 2D Flow and Heat Transfer Modeling in Fracture of Porous Media

Heat and mass transfer between porous media and fluid is a complex coupling process, which is widely used in various fields of engineering applications, especially for natural and artificial fractures in oil and gas extraction. In this study, a new method is proposed to deal with the flow and heat transfer problem of steady flow in a fracture. The fluid flow in a fracture was described using the same method as Mohais, who considered a fracture as a channel with porous wall, and the perturbation method was used to solve the mathematical model. Unlike previous studies, the shear jump boundary condition proposed by Ochoa-Tapia and Whitaker was used at the interface between the fluid and porous media. The main methods were perturbation analysis and the application of shear jump boundary conditions. The influence of permeability, channel width, shear jump degree and effective dynamic viscosity on the flow and heat transfer in the channel was studied by analysing the analytical solution. The distribution of axial velocity in the channel with the change of the typical parameters and the sensitivity of the heat transfer was obtained.

Polycyclic aromatic hydrocarbons in the centralized wastewater treatment plant of a chemical industry zone:Removal,mass balance and source analysis

Increased attention has been given to the fate of pollutants such as polycyclic aromatic hydrocarbons (PAHs) introduced to the wastewater treatment plants.Dissolved and adsorbed PAHs were detected in the centralized wastewater treatment plant of a chemical industry zone in Zhejiang Province,China.The most abundant PAHs were the low molecular weight PAHs (e.g.,Acy,Ace,Flu and Phe),accounting for more than 80% of the total 16 PAHs in each treatment stage.Phase partitioning suggested that the removal of PAHs in every treatment stage was influenced greater by the sorption of particles or microorganisms.The removal efficiencies of individual PAHs ranged between 4% and 87% in the primary sedimentation stage,between 1% and 42% in anaerobic hydrolysis stage,between <1% and 70% in aerobic bio-process stage,between 1.5% and 80% in high-density clarifier stage,and between 44% and 97% in the whole treatment process.Mass balance calculations in primary stage showed significant losses for low molecular weight PAHs and relatively good agreements for high molecular weight PAHs as well as in anaerobic hydrolysis,high-density clarifier stage and sludge stream for most PAHs.Great gains of 60%-150% were obtained for high molecular weight PAHs in aerobic bio-process stage due to biosorption and bioaccumulation.Our investigations found that PAHs entering the wastewater treatment plant (WWTP) could be derived from the dyeing chemical processes as the byproducts,and the contribution supported by the largest dyeing chemical group was up to 48%.