Evaluating Liquefaction Strength of Partially Saturated Sand

A method is presented for evaluating the liquefaction strength of partially saturated sand using the compression wave velocity (P-wave velocity), a new indicator of saturation. Based on laboratory test results, an empirical correlation that relates the liquefaction strength with the pore pressure coefficient B is firstly proposed. The strength is defined as the cyclic stress ratio required to cause liquefaction at a specified number of cycles. With the aid of a theoretical relation between B and the P-wave velocity, an explicit correlation of more interest is then established between the liquefaction strength of sand and its P-wave velocity. A comparison of the predictions using this explicit correlation with laboratory measurements shows a satisfactory agreement. The significance of this method lies in that it makes it possible to evaluate the liquefaction strength of sand as affected by saturation through the measurement of P-wave velocity, which can be made not only in the laboratory but particularly in the field.     

Master sintering curve concepts as applied to the sintering of molybdenum

Sintering experiments with various molybdenum powders are rationalized using a master sintering curve concept that collapses density, grain size, or other parameters onto a single curve. In this case, the integral work of sintering is developed and customized for different green densities. Construction of the master sintering curve is described to show how the curve can be normalized with respect to green density effects. Various grades of molybdenum for metal injection molding and die compaction are included in the analysis, processed over a range of heating cycles. Die-compacted samples of varying green densities are used to illustrate the efficacy of the new, normalized master sintering curve concept. Sintering cycle optimization is one possible outcome from this analysis.     

Structure evolution of conductive polymer composites revealed by solvent vapor induced time-dependent percolation

The authors of this paper synthesized a series of amphiphilic triblock copolymers of polystyrene-b-poly(ethylene glycol)-b-polystyrene (PS-PEG-PS) having different PEG/PS ratios with nearly identical molecular weights of the entire copolymers. The interfacial interactions in the composites consisting of carbon black and the copolymers can thus be tailored. When these conducting composites are exposed to certain solvent vapors, their electrical resistances greatly increase, showing the gas sensitivity. The present work indicated that this switching behavior is controlled by the structural relaxation of the composites because matrix swelling acts as the main mechanism. The response time has been correlated with absolute temperature by Arrhenius equation, and the estimated activation energy reflects mobility of the fillers involved in the solvent induced expansion of the surrounding polymer. Therefore, by using the gas sensibility of the conductive composites, the structure evolution of the composite materials in solid state and the effect of filler/matrix interfacial interaction on the relaxation property of the matrix polymer has been inspected. It was found that lower activation energy represents stronger interfacial interaction in case good solvent of the matrix was used for the test.     

SIDAC双向开关触发器的典型应用

详细介绍了SIDAC作为一种高压双向触发器的工作特点及其典型的应用电路。     

油脂己烷浸出工程进展

油脂己烷浸出工程经过几十年的发展，在工艺、设备、自控、节能、环保等方面都已趋于完善。装置的规模日趋大型化。车间内的工段组合更加科学、合理与多样化，浅料层浸出器，形式多样化的湿粕脱溶系统，湿粕挤压机，废水零排放系统，不同理念的负压蒸发及余热回收系统，蒸汽冷凝水的再利用，简洁实用的全电脑操作系统，分步萃取，混合油过滤，浸出车间内的混合油碱炼、水化脱胶、磷脂干燥等使得当今的油脂浸出向大型化、集约化、自动化、节能环保的方向发展，为客户提供了越来越多的选择。     

Characteristics of nitrogen and phosphorus removal in SBR and SBBR with different ammonium loading rates

Laboratory scale experiments were conducted to study the deterioration of enhanced biological phosphorus removal (EBPR) due to influent ammonium concentration, and to compare the performance of two types of sequencing batch reactor (SBR) systems, a conventional SBR and sequencing batch biofilm reactor (SBBR). Both in SBR and SBBR, the total nitrogen removal efficiency decreased from 100% to 53% and from 87.5% to 54.4%, respectively, with the increase of influent ammonium concentration from 20 mg/l to 80 mg/l. When the influent ammonium concentration was as low as 20 mg/l (C: N: P=200: 20: 15), denitrifying glycogen-accumulating organisms (DGAOs) were successfully grown and activated by using glucose as a sole carbon source in a lab-scale anaerobic-oxic-anoxic (A₂O) SBR. In the SBR, due to the effect of incomplete denitrification and pH drop, the nitrogen and phosphorus removal efficiency decreased from 77% to 33.3% when the influent ammonium concentration increased from 20 mg/l to 80 mg/l. However, in the SBBR, simultaneous nitrification/denitrification (SND) occurred, and the nitrification rate in the aerobic phase did not change remarkably in spite of the increase in influent ammonium concentration. Phosphorus removal was not affected by the increase of influent ammonium concentration.     

保山气田新近系羊邑组二-三段沉积微相

保山盆地为滇西的一个具西断东超箕状断陷结构的新近系小型盆地。为搞清区内保山气田的沉积特征，指导该区油气勘探工作，结合沉积岩（物）与沉积环境之间的辩证关系，通过对沉积岩的岩性特征（颜色、岩石类型、岩石结构、黏土矿物、岩相组合）的分析研究，借助于沉积相在测井和地震剖面上的显著特征，研究并划分了保山气田新近系上新统羊邑组二-三段的沉积微相类型。结果表明，在该研究区主要发育了扇三角洲前缘亚相中的水下分流河道、分流河道间、前缘席状砂、河口坝等沉积微相类型，以及浅湖亚相中的浅湖泥和浅湖漫流席状砂沉积微相。剖析各类骨架微相的沉积特征后指出：水下分流河道、河口坝和前缘席状砂为该区最有利的储集砂体。