Computable explicit bounds for the discretization error of variable stepsize multistep methods

This paper deals with the achievement of explicit computable bounds for the global discretization error of variable stepsize multistep methods which are perturbation of strongly stable fixed stepsize methods. The approach is based on the study of the growth of solutions of certain variable coefficient difference equations satisfied by the global discretization error.     

A combinatorial characterization of regular anonymous perfect threshold schemes

The notion of a regular anonymous perfect threshold scheme is introduced, and a combinatorial characterization for such a (2,w)-threshold scheme in terms of a regular difference family is given.     

不稳定流条件下油井地层压力与分层压力关系的一个差分模型

本建立了多油层径向单相不稳定流条件下油井地层压力计算的差分模型，实例计算表明，各分层压力的平均值能较好的逼近全井地层压力，其相对误差为０．１％左右。     

A general time-varying estimation and control problem

This paper solves two problems raised in [HSK]. The first is a uniform norm time-varying linear estimation problem and the second is a general time-varying linear control problem.     

基于相关配准的帧间差分算法

针对帧间差分法在摄像头运动时受动态背景严重干扰的问题,提出了一种基于图像配准的运动目标检测算法。首先将中值滤波后的连续两帧图像配准,配准时先在前一帧图像中选取背景,即背景图像,用区域相关法将后一帧图像与背景图像配准;接着将配准后的2帧图像差分得到帧间差分图像,即帧差图像,再用数学形态学的开运算去掉帧差图像中的一些细小噪声;最后将连续两帧去噪后的帧差图像逻辑与运算,得到运动目标检测结果。实验结果表明,在摄像头运动时的动态背景下,该算法有效地抑制了动态背景的干扰,准确地检测出了运动目标的边界,提高了运动目标检测在动态背景下的应用价值。     

Nest-like structures of Sr doped Bi2WO6: Synthesis and enhanced photocatalytic properties

A series of Sr-doped Bi₂WO₆ with three-dimensional (3D) nest-like structures were synthesized through simple hydrothermal route and characterized by XRD, FESEM, TEM, XPS, UV-vis DRS, etc. Morphology observation revealed that the as-synthesized Bi₂WO₆ were self-assembled three-dimensional (3D) nest-like structures, which were constructed from nanoplates. UV-vis diffuse reflectance spectra indicated that the samples had absorption in both UV and visible light areas. Their photocatalytic activities were evaluated by photodegradation of rhodamine B (RhB) under UV and visible light irradiation (λ > 420 nm). The photocatalytic properties were enhanced after Sr doping. Samples subsequently thermal treated at 500 °C showed higher photocatalytic activities. The reasons for the differences in the photocatalytic activities of these nest-like Bi₂WO₆ microstructures were further investigated.     

四川超深井长封固水泥浆性能研究与应用

针对深井一次性注水泥实现长段封固时高温水泥浆在中低温条件下长时间不凝固的难题,研究出了能抗70～160℃(井底静止温度)大温差的水泥浆,并对其性能进行了研究.结果证明,该水泥浆能保证水泥浆柱顶部水泥石在24 h内具有一定的抗压强度,且浆体稳定,流动性、稠化性能与防气窜性能良好,具有失水量低、不收缩、纤维增韧等特性.现场试验3井次,固井质量良好,该水泥浆能满足高温复杂深井长封固段注水泥的要求.     

围岩温度场及调热圈半径的半显式差分法解算

 建立了解算巷道围岩温度场分布、调热圈半径的数学模型及优于一般差分格式的解算围岩温度场的异步长半显式差分格式,编制了解算围岩温度场分布及调热圈半径的计算机程序,解算出了围岩温度分布规律;并通过实测数据与解算结果的对比,证明了异步长半显式差分格式的正确性及高精度。     

移动网智能管道发展的挑战和应对

探讨了移动智能管道的定义和内涵,分析目前移动网智能管道发展的架构、能力完善和协同、管道价值挖掘、运营机制优化这4个方面的挑战,并给出了应对策略。     

引起阻焊膜色差的关键因素分析

在PCB阻焊外观品质控制中,阻焊的颜色是比较重要的一项控制点,对于使用同一型号阻焊油墨的一款生产板,板面阻焊出现明显的色差,客户一般不接受,目前业内对于引起阻焊色差的深层原因罕见报道。本文主要针对阻焊色差问题,研究了阻焊厚度、预烘时间、曝光能量、热固化温度时间等对阻焊颜色的影响,尝试从光学角度和阻焊的微观结构来解释引起阻焊色差的根本原因,同时研究了阻焊膜的色差所带来的可靠性问题,从结合力和其耐化学性方面做深入探讨。