射线探伤中环焊缝一次透照长度计算的探讨

通过对一次透照长度概念的分析以及对环焊缝内透偏心法(F相似文献   

Optimal linear filter design for systems with correlation in the measurement matrices and noises: recursive algorithm and applications

This paper addresses the optimal least-squares linear estimation problem for a class of discrete-time stochastic systems with random parameter matrices and correlated additive noises. The system presents the following main features: (1) one-step correlated and cross-correlated random parameter matrices in the observation equation are assumed; (2) the process and measurement noises are one-step autocorrelated and two-step cross-correlated. Using an innovation approach and these correlation assumptions, a recursive algorithm with a simple computational procedure is derived for the optimal linear filter. As a significant application of the proposed results, the optimal recursive filtering problem in multi-sensor systems with missing measurements and random delays can be addressed. Numerical simulation examples are used to demonstrate the feasibility of the proposed filtering algorithm, which is also compared with other filters that have been proposed.     

北京市雨水收集利用蓄水池容积计算与分析

基于北京市1984—2013年的日降雨资料,以北京林业大学林业楼及其周边绿地为研究区,设置3种用水情景(冲厕、绿地灌溉及冲厕+绿地灌溉),采用连续模拟法,分别绘制3种用水情景下雨水收集利用工程的雨水截留率、自来水替代率、供水保证率以及效益费用比变化曲线,并通过综合分析这些曲线的变化特征确定雨水蓄水池最佳设计容积(60~82 m3)。同时采用设计暴雨法计算1~5年不同重现期的蓄水池设计容积(77~248 m3)。结果表明,连续模拟法计算过程相对复杂,但可用于综合衡量雨水收集利用工程的雨洪管理效益,以及缓解水资源短缺效益、供水可靠性及经济可行性分析。     

Three-dimensional simulation using fixed coarse-grid thermal-fluid scheme and conduction heat transfer scheme in distinct element method

Three-dimensional simulation using particle-thermal-fluid coupling scheme with a mixed Lagrangian-Eulerian approach is presented and the scheme is described by extending author's previous research [Y. Shimizu, 2004. “Fluid Coupling in PFC2D and PFC3D”, numerical modeling in micromechanics via particle methods—2004, Proceeding of 2nd International PFC Conference, Balkema, 2004, pp. 281-287]. The scheme solves the continuity, Navier-Stokes (N-S) and thermal energy equations numerically in Eulerian Cartesian coordinates, then derives pressure, velocity vectors and temperature for each fixed cell by considering particle existence. On the other hand, driving forces and thermal energy from fluid are applied to the particles as external body forces and a source term in the force-displacement law and the heat transfer calculations, respectively. This paper describes the thermal scheme for both fluid and particles. Results of two- and three-dimensional simulations involving forced convective heat transfer by fluid and conduction heat transfer within particles are presented.     

Off-line optimization and control for real time integration of a three-phase hydrogenation catalytic reactor

In order to develop and test the integration procedure, in this paper a real time process integration involving the optimization and control of the process is presented, in this case, with the two-layer approach. The used optimization algorithms were Levenberg–Marquardt and SQP that solve a non-linear least square problem subject to bounds on the variables. The two-layer approach is a hierarchical control structure where an optimization layer calculates the set points and manipulated variables to the advanced controller, which is based on the dynamic matrix control with constraints (QDMC). The non-isothermal dynamic model of the three-phase slurry catalytic reactor with appropriate solution procedure was utilized in this work (Vasco de Toledo, E. C., Santana, P. L., Maciel, M. R. W., & Maciel Filho, R. (2001). Dynamic modeling of a three-phase catalytic slurry reactor. Chemical Engineering Science, 56, 6055–6061). The model consists on mass and heat balance equations for the catalyst particles as well as for the bulk phases of gas and liquid. The model was used to describe the dynamic behavior of hydrogenation reaction of o-cresol to obtain 2-methil-cyclohexanol, in the presence of a catalyst Ni/SiO₂.     

TD-LTE与TD-SCDMA切换判决机制的探究与仿真

不同网络之间的切换问题是网络间互操作的重要组成部分,尤其是当前备受关注的TD-LTE与TD-SCDMA的切换问题。该文在对常规切换机制剖析的基础上,通过详尽的理论分析,根据现有切换机制的不足,提出了新的切换判决算法机制。新机制中结合了多属性切换判决中的层次分析算法和二维函数收益法,考虑了移动用户的业务喜好,并使用Matlab搭建了网络模型着重针对数据业务进行仿真,根据不同的网络收益值来实现切换的选择,验证了数据业务切换判决算法的有效性。     

A discrete model for non-wetting liquid flow from a point source in a packed bed under the influence of gas flow

A study of non-wetting flow in a packed bed under the influence of gas flow has been carried out. Departing from the usual continuum models, a discrete and deterministic model for liquid flow has been presented to model the liquid flow from single and multiple point sources. Liquid flow is modelled based on force balance approach considering gas drag, bed resistance and gravity forces. Gas flow is modelled using k-ε model for turbulent flow. An X-ray flow visualization technique, developed by our group, is used to study the liquid flow paths in the packed bed. Liquid flow path and velocity has been obtained for various liquid and gas flow rate. Flow paths obtained from the simulation results are in good agreement to those obtained from flow visualization procedure under various conditions. Also, liquid distribution at the bed bottom is reported and compared with the experimental results.     

基于模糊物元模型的区域水资源开发利用评价方法

为客观评价区域的用水水平,采用基于欧式贴近度的模糊物元模型综合评价区域水资源开发利用程度.将灌区用水水平的不同阶段作为物元的事物,将各阶段的评价指标及其模糊量值作为复合模糊物元,通过计算复合模糊物元与标准物元之间的欧式贴近度,综合分析区域水资源的开发利用现状,确定区域用水水平,为水资源的进一步开发利用及合理配置提供决策依据.以宝鸡峡灌区为例,研究结果表明,宝鸡峡灌区的用水水平处于发展阶段,水资源开发利用已具有一定规模但仍有开发潜力.     

基于熵权的郑州市城市生态系统健康评价

城市生态系统是以人工为主导的自然、经济、社会3个子系统的复合生态系统,为使城市生态系统健康发展,根据健康评价指标体系建立原则,构建了一个4层的城市生态系统健康指标评价体系,采用基于熵权的模糊综合评判法,从时间纵向上研究了郑州市城市生态系统的发展趋势.结果表明：从2003年到2007年,反映生态系统结构功能的各要素,表现出了不同的发展趋势;郑州市城市生态系统健康状况呈总体上升的趋势;3个子系统间不能够协调发展,主要是社会子系统存在结构不合理等原因引起,可为制定进一步的城市发展政策借鉴.