Indicators for choosing an optimal mix of major working postures

North American workers usually stand while working, and prolonged standing is associated with discomfort and cardiovascular problems. Since prolonged sitting is also associated with health problems, and standing postures differ as to mobility and access to seating, it is desirable to identify an optimal mix of postures. As a step towards this identification, it is desirable to develop indicators of potential health effects that respond to changes in work requirements. We observed 65 subjects who usually stood at work, in four types of workplaces. Pressure-pain threshold (PPT) recorded on the plantar surface was used as an indicator of discomfort and arterial blood pressure was used as an indicator of cardiovascular effects. PPT after work was significantly lower than that before work. Sitting for even a small part of the day appeared to be protective. The effects of static vs. dynamic work on PPT and arterial blood pressure may differ.     

涤纶长丝纺丝组件更换周期探索

通过生产实践和统计分析 ,提出涤纶长丝纺丝组件的使用周期可从原 3个月延长至 5～ 6个月。生产不同品种组件使用周期可通过上机试验来确认     

高强度堵水剂裂缝细管模型堵水模拟实验

在裂缝性致密储层中,裂缝既是油流通道又是水驱窜流通道,在注水开发中由于裂缝的存在导致水驱波及效率低,从而形成无效注水开发。此外,裂缝性储层的封堵又存在大裂缝封堵效果差、有效期短等问题。鉴于此研制了水溶性酚醛树脂冻胶和单体地层聚合高强度堵剂体系,测定了堵剂在70℃下的成胶性能、稳定性以及封堵强度等。通过细管模拟裂缝研究了不同因素对堵剂突破压力的影响;通过可视化细管研究了堵剂在管中的突破方式以及影响因素。研究结果表明,水溶性酚醛树脂冻胶的突破压力随着冻胶强度的增加而增加,随着管径的增加而减小,随着注水速度的增加先减小、后增加,最后稳定;单体地层聚合堵剂的突破压力随着堵剂强度的增加而增加,随着管径的增加先增大、后减小。在可视化细管实验中,堵剂突破时并不完全沿细管中心突破,其堵剂的强度与黏附性等因素有关。     

新型自封带旁通阀回油过滤器基本模型介绍

针对箱侧、箱底回油过滤器的特点,提出一种较传统结构更简单、使用起来更方便的结构模型。     

Transport properties of nonelectrolyte liquid mixtures—IV. Viscosity coefficients for benzene,perdeuterobenzene, hexafluorobenzene,and an equimolar mixture of benzene + hexafluorobenzene from 25 to 100°c at pressures up to the freezing pressure

Viscosity coefficient measurements made with an estimated accuracy of ±2% using a self-centering falling body viscometer are reported for benzene, perdeuterobenzene, hexafluorobenzene and an equimolar mixture of benzene + hexafluorobenzene at 25, 50, 75 and 100°C at pressures up to the freezing pressure. The data for each liquid at different temperatures and pressures are correlated very satisfactorily by a graphical method based on plots of 9.118×10⁷ V ^2/3/(MRT)^1/2 versus logV, and are reproduced to within the experimental uncertainty by a free-volume form of equation. Application of the empirical Grunberg and Nissan equation to the mixture viscosity coefficient data shows that the characteristic constant G is practically temperature- and pressure-independent for this system.     

Thermal conductivity and heat capacity of solid AgCl under pressure

Using the transient hot-wire method, measurements were made for solid AgCl of both the thermal conductivity, , and the heat capacity per unit volume, c _p, where is the mass density. Measurements were made in the temperature range 100 to 400 K, and at pressures up to 2 GPa. c _p(P, T) could be adequately described if the acoustic modes were represented by a Debye model and the optic modes by an Einstein model. Analysis of (T) showed that only the acoustic modes needed to be taken into account up to 300 K, but that the optic modes were increasingly effective in carrying heat at higher temperatures. (P) was adequately described by the Lawson formula, but not by the Leibfried-Schlömann formula, to which it is formally equivalent. Agreement with experiment could be achieved by two different modifications of the Leibfried-Schlömann formula, although neither has a firm theoretical basis.     

海盐水溶液渗透压计算的探讨

在反渗透脱盐装置的设计中,渗透压是必不可少的设计参数。考虑在水处理过程中遇到的混合电解质水溶液绝大多数的离子强度都不高,据此作者提出一近似计算公式。在盐溶液浓度为1000～50000 ppm 范围内,用该式计算所得渗透压值与实测值及Stoughton 式计算值相比,相对误差在2.5%以内。     

易拉罐内壁涂装技术

介绍了影响易拉罐内壁涂层质量的因素及相应的处理方法。     

橡胶注射充模过程的数值分析

借鉴塑料熔融注射技术，研究了胶料粘弹性引起的入口附加压力降和固体壁面滑移速度对充模过程的影响，从而建立了橡胶在薄矩形模腔内充模流动的数学模型。采用有限单元和有限差分混合方法求数值解。通过计算程序预测了充模过程中前锋线的移动及流动场，并根据模拟计算结果，分析讨论了各因素对充模压力的影响。     

低压长袋脉冲袋式除尘器设计与应用

以工业原料尤里卡沥青(EP)为对象，详细论述了低压长袋脉冲袋式除尘器的主要设计环节，着重分析了新型脉冲阀技术。指出了该技术在化肥行业原料干燥、风扫制备等方面的推广应用和发展趋势。