Fixed-time sliding mode control based plant/controller co-design of dual-motor driving system

A fixed-time sliding mode controller based plant/controller co-design scheme is developed for dual-motor driving systems. The proposed controller is fixed-time stable subject to unknown disturbances which guarantees the robustness of the proposed control scheme and a less conservative solution can be ensured by comparing with the conventional fixed-time convergence technique. Due to the existence of couplings between the plant and the controller, traditional design procedures in which the plant and the controller are designed sequentially and separately cannot guarantee the overall optimum of control systems. A co-design scheme based on the nested optimisation strategy is developed in this paper. With the nested optimisation strategy, the co-design solution can be achieved efficiently and reliably. A combined cost function considering both the plant and the controller is developed so that the largest load can be achieved without degrading the control performance. The fixed-time convergent controller is employed and considered into the co-design scheme. The gravitational search algorithm is adopted to optimise controller parameters in the co-design scheme. With the presented co-design method, the largest load of the studied system can be achieved with the satisfactory control performance. Contrastive Simulation and experimental results demonstrate the efficacy of the proposed controller and co-design scheme.     

局域网IP电话系统中下位机软件的设计与实现

针对目前纯软件实现的IP电话存在的使用不方便等缺陷,设计并实现了一种局域网IP电话系统。文章详细描述了该系统中下位机软件的设计及实现方法,并说明了软件设计中应注意的事项。     

一维驱动二维跟踪太阳自动跟踪系统设计

本文从对太阳方位变化规律的分析计算入手,利用天文时间来提供准确可靠的自动跟踪信号,并采用一维驱动实现二维精密跟踪的新技术。依此所设计的新型太阳能聚光器自动跟踪系统与同类产品相比,具有准确可靠、抗干扰能力强、成本低、方便实用等特点;这对于通过聚光方式推动太阳能应用具有重大的现实意义。     

Values of the mass transfer coefficient of the linear driving force model for VOC adsorption on activated carbons

Modelling of activated carbon cartridges is essential in personal protective equipments against toxic gases in order to know the duration of protection. The linear driving force model seems to be more adapted than the actual Wheeler–Jonas model because it has more physical significance. The difficulty is that the mass transfer coefficient can not be calculated a priori. Values of the LDF mass transfer coefficient are disseminated in the literature and thus there is no overview of the range and variations with different adsorbents, adsorbates and concentrations. The object of this paper is thus twofold: obtaining values of the mass transfer coefficient at different concentrations and adsorbates in order to have a comprehensive view of variations and appreciating the validity of the LDF constant pattern model.     

沿空掘巷工作面停采期煤自燃防治技术

为有效防治沿空掘巷工作面回采期间煤自燃,在实验室测试并分析了32煤层自燃指标气体及临界值;采用UDEC软件对沿空掘巷遗留小煤柱的稳定性进行了分析,得出煤柱受到的最大垂直应力为12 MPa,垂直方向和水平方向最大位移分别为2.076、0.547 l m;采用Fluent软件分析了受压小煤柱易自燃区域情况,得出小煤柱采空区侧方向25 ～ 75 m属于自燃氧化带的范围.根据分析结果采取了降低风量、指标气体监测点优化及安全预警临界值量化、采空区和小煤柱易自燃区域内埋管注三相泡沫为一体的煤炭自燃防治措施,工作面停采半年期间其上隅角支架后CO体积分数稳定在20×10-6左右,O2体积分数保持在18％,取得了较好的自燃防治效果.     

营运驾驶员驾驶风格研究

目的探索了解我国营运驾驶员的驾驶风格特点,以及驾驶风格与交通违规之间的关系。方法在辽宁省沈阳、大连两个城市现场选取170名营运驾驶员完成中文版驾驶风格量表。结果驾驶风格的性别差异显著。男性驾驶风格以冒险型和愤怒型为主,女性驾驶风格以焦虑型为主。驾驶员在感觉寻求、愤怒、分心维度上的得分随着年龄的增长而下降。有交通违规记录的驾驶员在愤怒、冒险、分心和焦虑维度上的得分均高于无违规记录的驾驶员,且差异显著。结论驾驶员的驾驶风格越倾向于冒险型、愤怒型和焦虑型,他们的交通违规次数也越多,应当针对危险驾驶行为采取适当有效的预防和干预措施。     

论造型线采用的几种驱动方式

对造型线常用的几种驱动方式（气压驱动、液压驱动和电机驱动）进行了历史回顾，介绍了各驱动方式的特点及适用范围，指出了各驱动方式在实际使用中存在的一些问题，并提出了在造型线设计中选用驱动方式的几点建议，对造型线设计有一定参考价值。     

进给爬行时临界驱动速度的计算与分析

讨论了机床进给系统中因驱动件运动速度低,因而产生爬行现象的自激振动机理。通过对进给系统建立运动模型,导出了产生爬行现象的最低临界驱动速度的计算公式,对生产实践具有一定的指导意义。     

不同组配P91钢焊接接头断裂性能分析

作为马氏体耐热钢，P91钢具有很强的抗氧化和抗高温蒸汽腐蚀性能，在大功率火力发电设备中得到广泛应用，而其接头的断裂性能对该材料的推广及应用至关重要。采用数值分析及实验的方法，讨论裂纹位于焊接接头的不同位置时，组配发生变化的焊接接头的断裂驱动力和断裂抵抗力。结果表明，材料组配的不同会对焊接接头的断裂驱动力产生一定的影响。从断裂阻力的角度来看，低组配焊接接头的断裂抵抗力要高于高组配。实际工程结构应采用低组配接头形式，以提高焊接接头的抗断性能。     

650轧机用重型减速机使用实践与分析

本文针对我厂650×3中型轧钢机用主减速机当前的工作条件和轧制负荷情况,该减速机的设计特点、传动布置力学原则、使用维护经验等几个方面进行系统分析,并结合其运动现状和工作情况趋向,以探讨该减速机良好的工作可靠性和长期使用寿命的成因。