Characteristics of oxygen consumption of coal at programmed temperatures

Oxygen consumption is an important index of coal oxidation.In order to explore the coal-oxygen reaction,we developed an experimental system of coal spontaneous combustion and tested oxygen consumption of differently ranked coals at programmed temperatures.The size of coal samples ranged from 0.18~0.42 mm and the system heat-rate was 0.8℃/min.The results show that,for high ranked coals,oxygen consumption rises with coal temperature as a piecewise non-linear process.The critical coal temperature is about 50%.Below this temperature,oxygen consumption decreases with rising coal temperatures and reached a minimum at 50℃,approximately.Subsequently,it begins to increase and the rate of growth clearly increased with temperature.For low ranked coals,this characteristic is inconspicuous or even non-existent.The difference in oxygen consumption at the same temperatures varies for differently ranked coals.The results show the difference in oxygen consumption of the coals tested in our study reached 78.6% at 100 ℃.Based on the theory of coal-oxygen reaction,these phenomena were analyzed from the point of view of physical and chemical characteristics,as well as the appearance of the coal-oxygen complex.From theoretical analyses and our experiments,we conclude that the oxygen consumption at programmed temperatures reflects the oxidation ability of coals perfectly.     

楔条形阳极位置灵敏探测器图像非线性研究

基于楔条形阳极位置灵敏探测器的成像原理和二维傅里叶变换理论,提出了一种建立该类探测器成像模型的方法,进而模拟了探测器的成像效果,仿真了成像的几何非线性,仿真图像与实际图像基本符合。仿真结果表明:在阳极面板半径多出微通道板半径2P(P为阳极周期宽度)和电子云分布半宽度D为1.3P时,该类探测器的成像线性良好;电子云过小即D5P时,电子云超出楔条形阳极工作区域,成像边缘扭曲十分明显。     

具有孤立子的非线性微分方程的反散射及一些变换

在具有孤立子的非线性微分方程中,引致了反散射和相似、Backlund、Hopf-Cole等变换,并提出了它们的一些功效及应用。     

地震作用下的剪力墙结构分析

对地震条件下的建筑结构进行了非线性分析,研究了建筑一层结构的性能,建筑一层安装剪力墙可以增强结构一层的刚度,同时减少柱与柱连接的应力.研究结果表明,地震动力下结构的薄弱部位为柱的横截面.     

一种格缩减辅助MIMO检测的非线性量化算法

针对格缩减辅助MIMO检测中,采用格缩减技术后导致星座畸变,引起变换域信号非线性联合量化复杂度高的问题,提出了一种排序反馈的非线性量化算法。该算法同时考虑了变换星座的边界和各元素之间的相关性,且根据量化误差的大小选择信号元素量化判决的顺序,依次量化判决信号的各个元素。仿真证明,基于该算法的格缩减辅助MIMO检测其性能要优于无排序反馈量化和逐元素独立量化的格缩减辅助MIMO检测,且能很好的逼近最大似然检测的性能,在平坦块衰落信道下,算法复杂度为多项式复杂度。     

磁浮车辆空气弹簧垂向刚度特性分析

对磁浮车辆上采用的自由模式空气弹簧,在对其结构特点进行详细分析的基础上,通过有限元软件实现了空气弹簧的建模.在充分考虑了空气弹簧的几何非线性、材料非线性,以及状态非线性等特性的基础上,对影响空气弹簧刚度特性的主要参数进行了分析,并以垂向刚度为例,准确计算出空气弹簧在静态工况下的垂向刚度,为磁浮车辆的国产化设计提供相关的技术支持.     

影响蜂窝状钢骨混凝土L形柱性能的参数分析

针对钢骨混凝土L形柱,提出了一种新型的钢骨形式.为了掌握该构件的受力特性,通过ANSYS软件,对腹板开洞率、配钢率、加载角、偏心距等影响因素进行理论分析.结果表明,在相对偏心距较大的情况下构件承载力会急剧下降,而且存在不利荷载角的问题;腹板开洞能有效地减少钢骨与混凝土之间的滑移,但对承载力的削弱有限,并就该构件的最佳配钢率提出建议.     

The time dependent strain potential function for a polymeric glass

Torsion and normal force measurements were made during single step stress relaxation experiments on a polymeric glass (PMMA). Isochronal data were analysed using an approach adapted from that developed by Penn and Kearsley¹ (for incompressible elastic materials) to determine the derivatives $\text{?W}\text{?I}{}_1$, and $\text{?W}\text{?I}{}_2$ of the time dependent strain potential function. $\text{?W}\text{?I}{}_1$ and $\text{?W}\text{?I}{}_2$ are determined from existing solution to the torsion of an incompressible cylinder. A special solution to the torsion of a compressible cylinder is presented and it is shown that the values of $\text{?W}\text{?I}{}_1$ and $\text{?W}\text{?I}{}_2$ obtained using this solution to analyse the data do not differ greatly from those obtained using the incompressible solution. It is found from both solutions that $\text{?W}\text{?I}{}_1$ is negative and increases towards zero with increasing time and deformation while $\text{?W}\text{?I}{}_2$ is positive, greater in magnitude than $\text{?W}\text{?I}{}_1$ and decreases towards zero with increasing time and deformation. These results were unexpected and a full understanding of their meaning has yet to be reached.     

基于KSVM决策树法的人脸检测与定位

传统的SVM直接在线性条件下训练SVM分类器完成人脸与非人脸的分类,分类器训练困难,计算量大且速度慢.为构造一个复杂背景下人脸检测与定位的新方法,本文用核函数把SVM推广到非线性SVM,再与二叉树相结合,可以解决多类识别问题,此即KSVM决策树人脸检测方法.在此基础上,人脸面部特征被进一步确认.本文提出了改进的四边界Prewitt边缘算子提取人眼,进而定位五官.实验结果表明该方法检测率较高,虚警率较低,定位准确.     

Maintenance planning using continuous-state partially observable Markov decision processes and non-linear action models

The signs of deterioration in worldwide infrastructure and the associated socio-economic and environmental losses call for sustainable resource management and policy-making. To this end, this work presents an enhanced variant of partially observable Markov decision processes (POMDPs) for the life cycle assessment and maintenance planning of infrastructure. POMDPs comprise a method, commonly employed in the field of robotics, for decision-making on the basis of uncertain observations. In the work presented herein, a continuous-state POMDP formulation is presented which is adapted to the problem of decision-making for optimal management of civil structures. The aforementioned problem may comprise non-linear and non-deterministic action and observation models. The continuous-state POMDP is herein coupled with a normalised unscented transform (NUT) in order to deliver a framework able to tackle non-linearities that likely characterise action models. The capabilities of this enhanced framework and its applicability to the maintenance planning problem are presented via two applications. In a first illustrative example, the use of the NUT is demonstrated within the framework of the value iteration algorithm. Next, the proposed continuous-state framework is compared against a discrete-state formulation for implementation on a life cycle assessment problem.