微注塑成型流动中熔体壁面滑移的研究

基于宏观熔体流动的基本理论及其流动过程中壁面滑移机理的分析,针对微注塑成型模具中熔体充模流动时的壁面滑移行为,建立了微小通道中高聚物熔体流动的壁面滑移理论模型。并用数值模拟方法,对不同滑移系数时微小通道中熔体的壁面滑移对流动速度、熔体压力等的影响进行了研究。结果表明,微小通道中的壁面滑移可使壁面处熔体的流动速度增加,压力损失减小,有利于熔体的充模流动。     

中空纤维微滤膜组件过滤酱油时的流体力学特性的研究

采用最小二乘法拟合得到对中空纤维微滤膜组件处理酱油时有效阻力系数Ｃｆ与通道中流体雷诺数Ｒｅ之间的数学关系式,并且对不同过滤量时膜通道中宏观压力的变化进行了研究．     

金属有机骨架/聚酰亚胺复合膜材料的制备及脱硫特性

采用相分离方法制备了新型金属有机骨架(MOFs)/聚酰亚胺(PI)复合膜,考察了膜的形态结构、吸附通道与吸附行为的关系。结果表明:功能膜具有发达的孔结构,功能颗粒镶嵌于基膜的三维网络通道中;膜的断面形态结构随凝固浴的不同而有显著区别,以水、乙醇、异丙醇的顺序,断面形态从指状孔结构逐渐向海绵状孔过渡;膜的吸附行为与膜三维通道结构、金属有机骨架的独特网兜结构及络合吸附作用密切相关;膜具有良好的热稳定性,膜吸附容量可达18mg/g。该复合膜在有机物吸附分离、膜分离等领域中具有潜在的用途。     

PVDF膜接触器吸收二氧化碳过程中延缓膜润湿的研究

采用二乙醇胺水溶液为吸收剂于聚偏氟乙烯(PVDF)中空纤维膜组件中吸收CO_2,研究了膜吸收过程中延缓膜润湿的方法.实验分别考察了气相压力的加压方式、加压时长以及液相添加无机盐对膜浸润的影响,并对膜浸润进行了理论分析.实验结果表明,随着气相间歇加压的压力增大,膜浸润百分数最多下降33%,气相间歇加压存在最优的加压时长和合理的加压程序.保持气相压力持续为高压态,并不能有效地延缓膜润湿.通过向吸收剂中添加无机盐成分,可以减少自发浸润的进行,在吸收过程中膜浸润率下降16.7%.     

亲/疏水纳米结构表面微通道内流体的流动行为

在毛细管微通道内壁沉积二氧化硅微球并加以亲/疏水改性,以此来构建亲/疏水纳米结构表面微通道,考察了一定粘度的羧甲基纤维素钠水溶液在光滑亲/疏水微通道和粗糙亲/疏水微通道中的流动行为。结果表明,保持压力恒定,光滑毛细管(基材)中的液体流量随着粘度和管长的增加而减小;粘度一定,压力增加,无论壁面光滑或粗糙,疏水管中的流量均大于亲水管,且粗糙管中疏水/亲水流量斜率比大于光滑管;在低压时亲水管流量大于疏水管,而高压时恰好相反。采用滑移理论和牛顿运动定律对上述现象进行了解释,本研究以期为合理地操控微通道内的流体流动提供有价值的指导。     

中空纤维膜萃取器的子通道模型

选用５０％ＴＢＰ（煤油）－－苯酚－－水为实验体系，在三种不同装填因子的中空纤维膜器中进行了膜萃取实验研究，对实验数据和经验公式的偏差进行了深研究，提出了壳程流动的不均匀性，基于壳程子通道模型，对中空纤维膜器的放大效应进行了有益的探讨，经子通道模型修正的计算值与实验值误差均在±２０％以内。     

中空纤维式减压膜蒸馏组件的温度压力分布及通量特性研究

为了研究减压膜蒸馏过程中膜管内的温度，压力分布及传质通量特性，分别建立膜蒸馏过程的传热，传质数学模型，对其中的温度，压力分布和蒸馏量进行了理论分析和数值模拟，推导了计算膜蒸馏通量的新方法－－对数平均压差法，并分别比较了对数平均压差法和算术平均压差法计算通量的特点。结果表明，采用对数平均压差法计算总蒸馏通量，其误差在1．2％以内，当膜管进，出口内外压差之比△p‘／△p“≤1．6时，采用算术平均压差法来计算通量可将误差控制在＋2％内，而当△p‘／△p“较大时，不能采用算术平均压差法计算膜管内外平均压差及蒸馏通量。     

天然气膜法脱碳过程中节流降温行为的研究

采用实验室自制的聚酰亚胺(PI)中空纤维膜组件，通过气体节流渗透降温实验装置，系统考察了天然气中主要气体组分、膜渗透速率、组件填充率、操作压力以及放空比等参数对于膜法脱碳过程中气体节流渗透降温规律的影响.实验结果表明，CO₂气体表现出最为显著的节流渗透降温现象；膜渗透速率、组件填充率、操作压力等参数的提高会加剧组件内CO₂气体节流渗透降温程度，即降温速率变快且降温程度更严重；操作压力为1.5 MPa、进气温度为24.0℃时，膜组件内产生近20℃温降；放空比的提高在一定程度上有利于缓解组件内的温降现象.这些结果揭示了相关参数对膜组件内CO₂节流渗透降温行为规律性的影响，为天然气膜法脱碳过程中CO₂节流渗透降温行为的预判提供了科学有效的理论依据.     

明胶-海藻酸钠半互穿聚合物网络膜及其电刺激响应行为的研究

制备了明胶-海藻酸钠半互穿聚合物网络膜，研究了膜的溶胀吸水率及其电刺激响应行为。结果表明海藻酸钠的引入可大大提高明胶的吸水率，在NaCl溶液中，该半互穿聚合物网络水凝胶膜在非接触直流电场作用下向电场负极弯曲，其弯曲速度及弯曲偏转量受外加电场强度和膜中聚离子浓度的影响。在循环电场作用下，膜的弯曲响应行为具有良好的可逆性。通过聚电解质凝胶弯曲理论初步解释了其弯曲机理。     

窄通道强化沸腾换热的方法综述

利用通道强化沸腾换热是一种既经济又有效地强化传热方法。从核沸腾传热的微液膜蒸发机理出发，通过分析认为；利用窄通道强化沸腾换热，实质是对液膜蒸发过程的强化，并指出扩大微膜面积可强化沸腾换热。针对窄通道沸腾换热临界热负荷小的事实，提出了可通过及时补液的克服方法。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.