Analysis of the Medium Pressure Range in Urban Gas Transmission and Distribution System

According to the analysis of technology and economy about the gas supply with the medium pressure in gas pipeline network of urban gas transmission and distribution system,a more economical and feasible pressure value is obtained.     

Hydraulic Reliability Designing Methods of Gas-Transport Network under High and Medium Pressure

This article analyses the hydraulic reliability of gas -transport network under high andmedium pressure in detail, To increase the hydraulic reliability, it is available to improve the send outpressure in permissible condition.     

Analysis of the Optimal Effect Radius of Regulator Station in Urban Gas Distribution Network with Medium Pressure

In urban gas network with multiple pressure ranges, there is an optimal effect radius, for which the annual calculating cost is minimal. According to the analysis of technology and economy about the gas supply with the medium pressure in urban gas transmission and distribution system, the optimal effect radius of regulator station in medium pressure gas network has been obtained.     

Characteristics of Interference Effects on Local Pressure of Two Square Tall Buildings in Tandem Arrangement

Wind tunnel tests were carried out to study the wind pressure on principal square building adjacent to another one in tandem. The interference effects on local pressure of the principal building were analyzed with different positions and heights of interfering building. It is shown that as height ratio is fixed, mean pressures on windward face are suctions when spacing ratio is less than 3, otherwise they are positive. The magnitudes of mean suctions on the side and leeward faces and fluctuating pressures on each face all get their maximums when spacing ratio is 3. As height ratios change, the magnitudes of mean suction on windward face increase with height ratio, meanwhile, the magnitudes on other faces obtain their minimums as the height ratio is 1.0 and the spacing ratio is less than 3. The fluctuating pressures on the windward and side faces get their maximums and that on the leeward face reaches its minimum as the height ratio is 1.0. When the spacing ratio is greater than 3, mean pressures on each face decrease, while fluctuating pressures on the windward and side faces increase as the height ratio increases, and the fluctuating pressures on the leeward face get the minimum when the height ratio is 1.0.     

Earth Pressure on Retaining Structure of Round Deep Foundation Pit in Sand-cobble Soils

In recent years, the round deep foundation pits engineering gradually appears in Chengdu Plain whose strata are mainly sand-cobble soils. However, there are no proper calculation methods of earth pressure in retaining structure like this and distribution mode of the pressure is unknown. With the use of elastoplastic numerical simulation method involved in interaction between retaining piles and soil, the distribution law of earth pressure of the round deep foundation pit retaining structure is determined. The result shows that distribution of earth pressure on a pile is triangular and the maximum lies in the location of pit bottom, but the average value of the pressure is less than Rankine active earth pressure. Model tests have also been carried out so as to verify the distribution mode. As for the test model, the values obtained by the numerical simulation method are approximately similar to the experimental results in the distribution law as a whole, which to some degree suggests the rationality of the numerical simulation results.     

Effects of Fines Content on Evolutionary Characteristics of Dynamic Pore Water Pressure of Saturated Sands

With the GDS dynamic triaxial system, undrained dynamic triaxial tests on the saturated sand with different fines content are performed, and the effects of fines content on evolutionary characteristics of dynamic pore water pressure of saturated sands in the process of liquefaction are analyzed based on Seed pore water pressure stress model. It is found that fines content has great effect on the dynamic pore water pressure of saturated sands by the parameter θ for Seed model. The relationship between parameter θ and fines content isnt linear. Parameter θ decreases with the increase of fines content at first, and then reaches its smallest value when the critical value of fines content is 30%. After that, parameter θ increases gradually with the rise of fines content. According to the experimental study on effects of fines content on evolutionary characteristics of dynamic pore water pressure of saturated sands, the existence of critical fines content with 30% is further proved in the sandy soil used in the test.     

Calculation and Analysis of Basic Wind Pressure Value Based on Gumbel Distribution

In order to find out the current basic wind pressure in China, the parameters were estimated based on Gumbel distribution by statistically analyzing the annual maximum values of wind speed of 159 typical cities in China between 1951 and 2008. The basic wind pressure values for 10-year, 50-year and 100-year return periods were calculated based on moment method and Gumbel method, respectively. The distribution function was tested by the Kolmogorov criterion. Finally, the calculation results were compared with those in current design codes and the results of the correlative literature. The results show that basic wind pressure values worked out by Gumbel method are better than those by moment method in most cases when the statistic of the annual maximum values of wind speed is conducted and analyzed by Gumbel distribution. There are significant differences between the basic wind pressure values for 10-year, 50-year and 100-year return periods in Loading Code for Design of Building Structures and the results calculated with the annual maximum values of wind speed in recent decades, which shows that the sample data in Loading Code for Design of Building Structures are relatively insufficient and cannot reflect the present true condition in China. Therefore, basic wind pressure value should be revised accordingly.     

高压对食品中蛋白质的影响

由于高压技术能在不影响食品风味和营养的前提下延长制品的贮存期,改善产品的组织结构,所以,近十几年来,高压技术逐渐成为食品工作者研究的热点。高压对蛋白质的作用是高压技术在食品中应用的基础,简单概述了高压对蛋白质作用的热力学因素,以及压力对化学键和蛋白质的结构、凝胶和溶胶的转化等的影响。     

超高压技术及其在食品加工业中的应用

阐述了超高压技术的作用机理及特点,介绍了超高压杀菌的作用机理及影响杀菌效果的因素,分析了超高压处理对食品品质,如脂类、风味物质、蛋白质、淀粉的影响及其在食品加工中的应用。     

Fracture Geometry and Pressure Distribution in Fracture for Hydrofracturing

It is proved first that hydrofracture has a self-similar elliptic extending characteristic which is independent of the praseure distribution in fractures by the theory of fracture me-chanics in this paper.Based on this theory ,the approximative analytic solutions of pressure distribution in fractures have been put forward by fracture mechanics coupled with fluid mechanics.     

超高压技术在食品加工中的应用与研究进展

应用超高压技术加工食品可以致死微生物,影响酶的活性,改变物质间的相互作用。对超高压技术发展的历史与现状及其在食品加工中的应用与研究进展作一阐述,并对超高压技术的发展前景进行了展望。     

超高压技术在食用菌加工中的应用研究

食用菌营养丰富,鲜香味美,是优质的膳食来源。超高压技术是食品加工的尖端技术,不仅有利于保持食物的营养和风味,而且应用领域广泛。阐述了超高压技术在食用菌产品杀菌、钝化酶类、保持产品营养成分与品质、提取生物活性功能成分及破碎孢子等方面的应用研究与进展,并展望了超高压食用菌加工技术研究及新产品开发等方面的前景。     

超高压技术在果汁加工中应用的研究进展

采用超高压技术(Ultra-high pressure,UHP)对果汁进行处理,可以在保鲜的同时更好地保留果汁的营养风味,是果汁加工中重要的灭菌手段.本文从UHP处理影响果汁中微生物灭活效果的工艺参数及其对果汁品质和酶活性的影响三个方面进行了综述,提出了UHP在果汁加工应用中的进一步研究方向,并对其发展前景进行了展望.     

Theoretical and Experimental Analysis on the Pressure Filtration Technology in Slurries Treatment

Treatment of waste drilling slurries has become one of the important problems encountered in urban construction. The application of pressure filtration technology brings significant advantages in slurries treatment. In order to give a better insight into the mechanism of pressure filtration, a model was introduced to analyze the relationship between filtration pressure, time and treatment results. The proposed model was validated using existing data. The parametric studies of the model show that the increase of the filtration pressure can reduce the filtration time and the permeability coefficient of the filter cake, While filtration time decreases very slowly beyond a certain extent. In addition, the relationship among filtration pressure, time and treatment results is further validated by test results.     

Numerical Modeling of Ice Slurry Flow Pressure Drop in Horizontal Pipes

To predict pressure drop of ice slurry flow in horizontal pipes, a mixture CFD model was applied to simulate the two-phase flow without considering ice melting. Based on the specific flow features, the Newtonian and non-Newtonian rheological expressions were employed respectively. It is found that in high speed the Thomas viscosity equation behaves well in representing the mixture fluid viscosity; whereas in low speed the Bingham model is more suitable for describing the mixture fluid rheology. Compared with the published pressure drop correlations, the current numerical model can involve with various factors and has a good balance between precision and suitability. The results of numerical model are in excellent agreement with the experimental data and the relative errors are limited to ±15%.     

Pressure Distribution of LFG in a Landfill with Vertical Extraction System

In present engineering practice of landfill gas pollution control and its recovery, technical parameters such as extraction flow and radius of influence of a extraction well must be determined by field tests. A mathematical model for LFG migration under a vertical extraction well is established, which comprehensively reflects affects of several parameters including LFG generation rate, extraction flow, air permeability, buried depth of a extraction well and features of the cover layer. By using the model, pressure distribution of LFG around a vertical extraction well in a landfill can be calculated, the radius of influence of the well can also be determined.     

Experimental Research on Pressure Elastic Waves Propagating in the Artificial Bile Duct System Model

In this Study, according to theprinciple of similitude, the model of bile duct system (that is BSM)has been simulated by transparent rubber and has been verified. Aspecific oscillator DZ-5 for the biliary system produced the pressure elastic waveswith differentwave shapes, frequency and amplitudes. A microcomputersystem are used to study the principle of the pressure elastic waves propagating in BSM and the function of Oddis sphincter, and then the experiment of removing gallstones on the experimental installation of BSM is carried out. Amechanism for movinggallstonesthat based on the theoreticalanalysis is verified by this study, and then to be perfected. It is suggested to put the one-way valve in T-type tube for patients whose sphincters loseeffectiveness. The optimum parameters of pressure elastic waves and the effect of pulse frequency on the removing gallstones have to be furtherdiscussed.     

Dealing with Thermal Exchange in Temperature Field Simulation in Low Pressure Die-casting Process

The main effort is to develop numerical simulation software of low pressure die casting on Windows platform in Personal Computer, based on the production of aluminum wheel in Die cast wheel manufacture Co. Ltd.. The heat conduction calculation is the basis of solidification simulation. A 3 dimentional model including the refrigeration medium block is set up based on the study of boundary heat exchange. Various calculation method is analyzed for different types of boundary element. A comprehensive calculation model is set up according to practically manipulable parameters in production.