先张法预应力桥梁板施工工艺及应用实例

结合太原市向阳店桥梁板施工实例，介绍了采用先张法进行预应力桥梁板施工的过程。阐述了桥梁板的施工工艺，该工艺实现了整体张拉、整体放张，使钢绞线逐根受力均匀，施工速度快，能保证梁端的质量。指出拉杆系统的使用，降低了成本，增加了效益。     

石油测井仪器可靠性指标探讨

在分析常用可靠性指标及其应用现状的基础上，根据可靠性理论及石油测井仪器的特点。提出了石油测井仪器的可靠性模型。在探讨常用可靠性指标对石油测井仪器适用性的同时，提出将平衡稳定工作时间NWTURE和免维修测井井次NOLWNM作为石油测井仪器可靠性指标的思想；探讨了获取可靠性指标的途径。给出了推荐使用的石油测井仪器可靠性指标。     

测定钠中杂质的手动阻塞计的研究

文章介绍了测定钠中杂质浓度的手动阻塞计的原理、装置和实验结果。为了减少测量误差,我们研究了影响准确测定阻塞温度的因素,并且找到了减少测量误差的办法。在同样的杂质饱和温度下,该阻塞计测得的高、低阻塞温度所对应的杂质浓度差是很接近的。对氧其差值为1.03ppm;对氢为0.0763ppm。     

心理因素对分析数据的影响及预防措施

研究了分析人员的心理状态、情绪变化、内在动机等对分析数据的影响,提出了具体的对策和预防措施     

MODELING OF WATER DYNAMICS AND POLLUTANT SPREADING IN THE LUOMAHU RESERVOIR FOR WATER TRANSFER FORM SOUTH TO NORTH OF CHINA

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＷａｔｅｒＴｒａｎｓｆｅｒＦｒｏｍＳｏｕｔｈＴｏＮｏｒｔｈＰｒｏｊｅｃｔ(ＷＴＦＳＴＮＰ)ｉｓａｇｒｅａｔｄｅｃｉｓｉｏｎｔｏｓｏｌｖｅｔｈｅｐｒｏｂｌｅｍｏｆｗａｔｅｒｓｈｏｒｔａｇｅｉｎｔｈｅｎｏｒｔｈａｎｄｃｅｎｔｒａｌｐａｒｔｓｏｆＣｈｉ ｎａ .Ｔｈｉｓｐｒｏｊｅｃｔ ,ｉｎｃｌｕｄｉｎｇＥａｓｔ ,Ｃｅｎｔｒａｌ ａｎｄＷｅｓｔ Ｌｉｎｅ ,ｗｉｌｌｄｒａｗｗａｔｅｒｆｒｏｍｔｈｅＹａｎｇｔｚｅＲｉｖｅｒｔｏｔｈｅｎｏｒｔｈａｎｄｃｅｎｔｅｒｏｆＣｈｉｎａｓｏｔｈａ…     

激光导向伺服系统中满意PID调节器的LMI设计

利用带有图像处理功能的小型激光导向伺服系统,可以大大降低目标坐标测定仪操作手跟踪动态飞行目标的操作难度,从而提高激光回波率.与经典的矩阵分解方法不同,本文以线性矩阵不等式方法,研究了激光导向伺服系统的满意PID调节器设计问题.首先从约束指标的相容性出发,给出满足与给定圆形极点约束相容的输出方差的取值范围.然后,在此取值范围内,得到了求取同时满足上述两种约束的PID调节器参数的方法.靶场试验结果证明了其有效性.     

VLSI Implementation of Forward Error Control Technique for ATM Networks

In asynchronous transfer mode (ATM) networks, fixed length cells of 53 bytes are transmitted. A cell may be discarded during transmission due to buffer overflow or a detection of errors. Cell discarding seriously degrades transmission quality. The quality degradation can be reduced by employing efficient forward error control (FEC) to recover discarded cells. In this paper, we present the design and implementation of decoding equipment for FEC in ATM networks based on a single parity check (SPC) product code using very‐large‐scale integration (VLSI) technology. FEC allows the destination to reconstruct missing data cells by using redundant parity cells that the source adds to each block of data cells. The functionality of the design has been tested using the Model Sim 5.7cXE Simulation Package. The design has been implemented for a 5 ° 5 matrix of data cells in a Virtex‐E XCV 3200E FG1156 device. The simulation and synthesis results show that the decoding function can be completed in 81 clock cycles with an optimum clock of 56.8 MHz. A test bench was written to study the performance of the decoder, and the results are presented.     

Salt-water up-coning during extraction of fresh water from a tropical island

Rainwater can collect in a lens-shaped region within the rock of a tropical island, and may be separated from the underlying salt water by a sharp interface. This paper presents a nonlinear theory for determining the shape of this interface. The island is assumed to be saturated with rain, and provision is made for the outflow of rain-water through the sides of the island. The effect of a bore well on the shape of the interface is investigated, and the problem is solved using a spectral method. An integral-equation method is also presented for the case when the island has infinite width.     

A new stereological principle for test lines in three-dimensional space

A new principle is presented to generate isotropic uniform random (IUR) test lines hitting a geometric structure in three-dimensional space (3D). The principle therefore concerns the estimation of surface area, volume, membrane thickness, etc., of arbitrary structures with piecewise smooth boundary. The principle states that a point-sampled test line on an isotropic plane through a fixed point in 3D is effectively an invariant test line in 3D. Particular attention is devoted to the stereology of particles, where an alternative to the surfactor method is obtained to estimate surface area. An interesting case arises when the particle is convex. The methods are illustrated with synthetic examples.     

On strategies for enforcing interfacial constraints and evaluating jump conditions with the extended finite element method

We consider a problem stemming from recent models of phase transitions in stimulus‐responsive hydrogels, wherein a sharp interface separates swelled and collapsed phases. Extended finite element methods that approximate the local solution with an enriched basis such that the mesh need not explicitly ‘fit’ the interface geometry are emphasized. Attention is focused on the weak enforcement of the normal configurational force balance and various options for evaluating the jump in the normal component of the solute flux at the interface. We show that as the reciprocal interfacial mobility vanishes, it plays the role of a penalty parameter enforcing a pure Dirichlet constraint, eventually triggering oscillations in the interfacial velocity. We also examine alternative formulations employing a Lagrange multiplier to enforce this constraint. It is shown that the most convenient choice of basis for the Lagrange multiplier results in oscillations in the multiplier field and a decrease in accuracy and rate of convergence in local error norms, suggesting a lack of stability in the discrete formulation. Under such conditions, neither the direct evaluation of the gradient of the approximation at the phase interface nor the interpretation of the Lagrange multiplier field provide a robust means to obtain the jump in the normal component of solute flux. Fortunately, the adaptation and use of local, domain‐integral methodologies considerably improves the flux evaluations. Several example problems are presented to compare and contrast the various techniques and methods. Copyright © 2004 John Wiley & Sons, Ltd.