Stabilization Methods for Spectral Element Computations of Incompressible Flows

A stabilization method for the spectral element computation of incompressible flow problems is investigated. It is based on a filtering procedure which consists in filtering the velocity field by a spectral vanishing Helmholtz-type operator at each time step. Relationship between this filtering procedure and SVV-stabilization method, introduced recently in [JCP, 2004, 196(2), p680], is established. A number of numerical examples are presented to show the accuracy and stabilization capability of the method.     

Two-Dimensional Physical and Numerical Modeling of a Pile-Supported Earth Platform over Soft Soil

This paper focuses on the mechanisms occurring in a granular earth platform over soft ground improved by rigid piles. Two-dimensional physical model experiments were performed using the Schneebeli’s analogical soil to investigate the load transfer mechanisms by arching and the settlement reduction and homogenization. Experimental outputs are compared to results obtained on a numerical model using a plane strain continuum approach. The impact of the constitutive model complexity to simulate the platform material behavior was first assessed, but no large difference was recorded. As far as the proposed model, which takes the main features of the observed behavior satisfactorily into account, the numerical procedure could be validated and the parametric studies extended numerically. Both approaches of this study underlined the main geometrical and geotechnical parameters which should inevitably be taken into account in a simplified design method, namely the capping ratio, the platform height, and the platform material shear strength.     

安徽省长江干堤的几种加固措施

安徽省境内765km的长江干堤，由于均是在原来旧堤的基础上经逐年加高培厚的，修筑时均未按设计要求施工，致使堤身密实度不够，新老堤土之间结合不牢，在汛期高水位时易产生渗漏。20世纪70年代以来，安徽省高度重视对长江干堤渗漏隐患的处理，经过长期的实践，逐渐摸索出一套行之有效的除险加固方法，如锥探灌浆、灭杀白蚁、冲抓套吉、垂直铺塑防渗、粘土铺盖及压渗盖重等处理措施。使长江干堤的渗漏隐患得以基本消除，其具体作法可供类似工程借鉴。     

半导体激光器用铷D2线光电流谱稳频

本文报导了用铷原子７８００Ａ光电流谱来稳定半导体激光器的工作，在光电流谱线的中部发现了有利于稳频的凹陷，将半导体激光器频率锁定在凹陷的中央，估算的频率稳定度为１ＭＨｚ。     

轻便型γ能谱测井仪几个关键技术问题的探讨

为研制性能好，功能强，微机化学程度高的轻便型γ能谱测井仪，针对非油气测井工作的井口径小（〈φ６０ｍｍ）井身浅（〈１０００ｍ）等特点，探讨了γ能谱测井仪的轻便化，测量精度，信号传输技术，稳谱技术及微机化等关键技术问题。     

Transient analysis of an advanced static var compensator using quad-series voltage-source PAM inverters

This paper deals with an advanced static Var compensator (ASVC) using quad-series voltage-source PAM inverters. The ASVC consists of four three-phase voltage-source inverters with a common dc capacitor and four three-phase transformers, each primary winding of which is connected in series with each other. Each inverter outputs a square-wave voltage, while the synthesized output voltage of the ASVC has a 24-step wave shape. This results not only in a great reduction of harmonic currents and dc voltage ripples but also in fewer switching and snubbing losses. In this paper, transient analysis is performed with the focus on the response of reactive power and the resonance between the dc capacitor and ac reactors. Experimental results obtained from a small-rated laboratory model of 10 kVA are also shown to verify analytical results based on the p-q transformation. The analytical results help in the design of system parameters such as the capacity of the dc capacitor and feedback gains.     

锁相技术在电子束曝光机工件台稳速控制中的应用

采用锁相技术，对电子束曝光机工件台运动实现速度环的全数字控制。设计了数字差频积分回路和数字差频比例控制器，能有效消除速度的静态误差和改善系统的动态特性。     

Influence of synergists: The influence of hydroperoxide decomposers on phenolic inhibitors consumption in oxidized polypropylene

The influence of sulphur‐ and phosphorum‐containing substances (hydroperoxide decomposers) on the kinetics of the consumption of two phenolic antioxidants in polypropylene (PP) was studied. The induction periods of PP autoxidation at 130°C were measured in the presence of inhibiting compositions that consisted of phenolic inhibitors and decomposers of hydroperoxide. Obtained results indicated that the influence of the hydroperoxide decomposer became significant when the concentration of the phenolic antioxidant became close to critical value. It also was shown that the efficiency of the hydroperoxide decomposer significantly depended on the mechanism of the transformation of the phenolic inhibitor; and first of all on the nature of its transformation products. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2239–2243, 2002     

G104-5P42分支水平井钻井液工艺技术

G104-5P42井是在高尚堡G104-5区块构造较高部位部署的一口重点开发井，也是冀东油田第一口鱼骨型水平分支井，钻探目的是开发高浅北区Ng12油层，挖掘高浅北区井间剩余油潜力。该井主井眼斜深为2388m，水平位移为736．42m，水平段长243m，第一分支斜深为2342m，水平段长120．25m，水平位移为682．14m，第二分支斜深为2421m，水平段长117m，水平位移为761．73m。三开选用无固相甲酸盐聚合醇钻井液，在钻进油气层前加入GN-YBJ-I保护剂。应用结果表明，无固相甲酸盐聚合醇钻井液具有好的防塌能力和润滑减阻效果，性能稳定、黏度、切力较低，有利于减少环空压力损耗；在油气层段密度控制在1．08g／cm^3以内，为近年来同区块密度使用最低井，减小了有害固相及滤液对储层的伤害密度，经测试该井获高产油流；该井全井平均机械钻速为15．09m／h，钻井周期比原设计提前15d。该体系的配制及维护成本较高，适宜在目的层井段使用，但可回收再利用。