煤矿综采工作面“三机”中部断面配套研究

介绍了煤矿综采工作面"三机"配套的重要性,对煤矿综采工作面"三机"(刮板输送机、采煤机、液压支架)的中部断面配套进行系统研究,对"三机"中部断面配套尺寸的确定进行了理论分析。     

刮板输送机链传动系统动力学建模与仿真分析

为研究刮板输送机链传动系统的动力学性能,建立了链传动系统的动力学模型。该模型主要考虑了链轮、链环、槽和刮板等主要零部件的质量、惯量和几何参数,并采用接触副描述各零部件之间的相互作用关系。在额定输出功率工况下利用所建模型进行动力学仿真,得到了链轮和链环的动态载荷,为链轮齿形优化、关键零部件强度校核及疲劳寿命预测提供了准确的边界条件。     

软件功能测试管理模型在上海轨道交通AFC系统中的应用

上海轨道交通的线路数逐年递增,随之自动售检票系统的规模越来越大,如何管理由于自动售检票系统的应用软件版本不断升级带来的软件功能测试的管理问题亟待解决本文借鉴ITIL思想,提出一个针对软件功能测试的管理模型应用表明,该模型在上海轨道交通自动售检票系统的测试管理中是成功和有效的     

自动售检票系统自动报故障系统的开发与应用

自动售检票系统(AFC系统)广泛应用在城市轨道交通中,它直接服务于乘客,设备的状态直接影响着城市轨道交通的服务水平和乘客满意度。目前广州地铁已开通的八条线路有5 000多台AFC设备,由于AFC设备的使用量大,操作用户较广,针对设备的故障数量较多,为提高维修响应的效率,减少工作人员的工作量,专业组技术人员开发了一套AFC设备的自动报故障系统,实现设备自动向维修人员报送故障提醒信息的功能。维修人员和维修调度能及时了解设备故障情况,在故障处理中占据主动,对提高AFC系统故障处理效率起到重要作用,进一步提高设备服务水平。     

Geometrically Non-Linear Bending Analysis of Piezoelectric Fiber-Reinforced Composite (MFC/AFC) Cross-Ply Plate Under Hygrothermal Environment

A finite element formulation for geometrically non-linear bending behavior of smart structures integrated with piezoelectric fiber-reinforced composite (AFC/MFC) layer acting as distributed actuator is presented in this article. The formulation of this hygro-thermo-electro-mechanical coupled problem is based on the first-order shear deformation theory (FSDT) and the von Kármán type geometric non-linearity. Resulting non-linear algebraic governing equations are linearized by Newton–Raphson iterative method. A developed finite element formulation is initially solved for validation and comparison with existing results. A wide variety of numerical examples considering cross-ply laminated substrates subjected to combined mechanical, hygrothermal and electrical loads are presented. The effect of piezoelectric fiber orientation in an actuator to counteract non-linear deflections is analyzed.     

Two types of a passive safety containment for a near future BWR with active and passive safety systems

The paper presents two types of a passive safety containment for a near future BWR. They are named Mark S and Mark X containment. One of their common merits is very low peak pressure at severe accidents without venting the containment atmosphere to the environment. The PCV pressure can be moderated within the design pressure. Another merit is the capability to submerge the PCV and the RPV above the core level. The third merit is robustness against external events such as a large commercial airplane crash. Both the containments have a passive cooling core catcher that has radial cooling channels. The Mark S containment is made of reinforced concrete and applicable to a large power BWR up to 1830 MWe. The Mark X containment has the steel secondary containment and can be cooled by natural circulation of outside air. It can accommodate a medium power BWR up to 1380 MWe. In both cases the plants have active and passive safety systems constituting in-depth hybrid safety (IDHS). The IDHS provides not only hardware diversity between active and passive safety systems but also more importantly diversity of the ultimate heat sinks between the atmosphere and the sea water. Although the plant concept discussed in the paper uses well-established technology, plant performance including economy is innovatively and evolutionally improved. Nothing is new in the hardware but everything is new in the performance.     

Sample Dimensionality Effects on d′ and Proportion of Correct Responses in Discrimination Testing

Products in the food and beverage industry have varying levels of dimensionality ranging from pure water to multicomponent food products, which can modify sensory perception and possibly influence discrimination testing results. The objectives of the study were to determine the impact of (1) sample dimensionality and (2) complex formulation changes on the d′ and proportion of correct response of the 3‐AFC and triangle methods. Two experiments were conducted using 47 prescreened subjects who performed either triangle or 3‐AFC test procedures. In Experiment I, subjects performed 3‐AFC and triangle tests using model solutions with different levels of dimensionality. Samples increased in dimensionality from 1‐dimensional sucrose in water solution to 3‐dimensional sucrose, citric acid, and flavor in water solution. In Experiment II, subjects performed 3‐AFC and triangle tests using 3‐dimensional solutions. Sample pairs differed in all 3 dimensions simultaneously to represent complex formulation changes. Two forms of complexity were compared: dilution, where all dimensions decreased in the same ratio, and compensation, where a dimension was increased to compensate for a reduction in another. The proportion of correct responses decreased for both methods when the dimensionality was increased from 1‐ to 2‐dimensional samples. No reduction in correct responses was observed from 2‐ to 3‐dimensional samples. No significant differences in d′ were demonstrated between the 2 methods when samples with complex formulation changes were tested. Results reveal an impact on proportion of correct responses due to sample dimensionality and should be explored further using a wide range of sample formulations.     

Aeroelastic analysis of smart composite structures in hygro-thermal environment

Aeroelastic performances of smart composite plates under aerodynamic loads are investigated in hygro-thermal environment. The active fiber composite (AFC) which is more effective and adaptive than conventional monolithic piezoelectric material is used in the present analysis to control the undesirable response due to hygrothermal effect. In the presence of hygrothermal load the composite structure becomes weak. But the structure can regain its stiffness in hygro-thermal environment when the AFC layer is activated with the help of applied voltage. The AFC is also effective to enhance the flutter boundary of present aeroelastic structure in hygro-thermal environment.     

Performance assessment of concentrated solar power plants based on carbon and hydrogen fuel cells

In spite of the recent success on the implementation of Concentrating Solar Power (CSP), still this technology needs a substantial enhancement to achieve competitiveness. This paper provides thorough insight after previous analyses on an alternative concept for higher efficiency CSP systems based on the replacement of the power block by an electrochemical conversion system. Concentrating solar energy is herewith used to decompose methane into hydrogen and carbon, which are used in hydrogen and carbon fuel cells for electricity generation. This approach envisages modular, efficient and flexible generation plants. Dispatchability can be achieved by storing the solid carbon. Solar-to-electricity efficiency was calculated assuming thermodynamic equilibrium composition and experimental data available from literature, and compared with those of conventional power generation systems and commercial CSP plants. It is concluded that this new-generation CSP concept is potentially able to produce power more efficiently than the current state-of-the art solar thermal power plants.