Energy‐efficient scheduling for sustainable manufacturing systems with renewable energy resources

Environmentally friendly energy resources open a new opportunity to tackle the problem of energy security and climate change arising from wide use of fossil fuels. This paper focuses on optimizing the allocation of the energy generated by the renewable energy system to minimize the total electricity cost for sustainable manufacturing systems under time‐of‐use tariff by clipping the peak demand. A rolling horizon approach is adopted to handle the uncertainty caused by the weather change. A nonlinear mathematical programming model is established for each decision epoch based on the predicted energy generation and the probability distribution of power demand in the manufacturing plant. The objective function of the model is shown to be convex, Lipchitz‐continuous, and subdifferentiable. A generalized benders decomposition method based on the primal‐dual subgradient descent algorithm is proposed to solve the model. A series of numerical experiments is conducted to show the effectiveness of the solution approach and the significant benefits of using the renewable energy resources.     

Cell structure of microcellular combustible object foamed by supercritical carbon dioxide

In order to solve the issue that the combustible objects for cased telescoped ammunition (CTA) didn't burn completely during the combustion process, the microcellular combustible objects were foamed with numerous cells in the micron order to improve the combustion performance by the supercritical carbon dioxide (SCCO₂) foaming technology. As the cell structure determined the combustion properties of microcellular combustible objects, the solubility of SCCO₂ dissolved into the combustible objects was obtained from the gravimetric method, and scanning electron microscope (SEM) was applied to characterize the cell structure under various process conditions of solubility, foaming temperature and foaming time. SEM images indicate that the cell diameter of microcellular combustible objects is in the level of 1 μm and the cell density is about 10¹¹ cell⋅cm⁻³. The microcellular combustible objects fabricated by the SCCO₂ foaming technology are smooth and uniform, and the high specific surface area of cell structure can lead to the significant combustion performance of microcellular combustible object for CTA in the future.     

卡塞格林结构式平行光管衍射分辨率的研究

对常规结构式平行光管和卡塞格林结构式平行光管的衍射分辨率进行了对比分析。计算了在衍射分辨率的限制下卡塞格林结构式平行光管中间遮挡孔径尺寸与系统整体长度之间的关系。为卡塞格林结构式平行光管的研究、设计提供了必要的依据。     

变结构控制器的仿真模型研究

变结构控制器集中了非线性控制与线性控制的优点,既保证了系统的快速性,又具有良好的跟踪精度。运用控制理论及牛顿运动规律,阐述了变结构控制器的建模机理,重点研究在MATLAB/SIMULINK动态系统仿真环境下,利用已有模块搭建变结构控制器的仿真模型。该仿真模型已被成功地应用于某型自行高炮随动系统的仿真研究中。     

1420cs铝锂合金型材力学特性测试

用电测的方法 ,得到了材料的应力与纵向应变曲线及横向应变与纵向应变曲线 ,判读出σ0 2 、σb、E、μ ,测试结果表明 :过比例伸长应力后 ,横向变形有明显跳动 ,这种特性有别于其他材料 ,使用中应予注意 ;测试了表面裂纹的断裂韧度。     

变速传动轴承传动原理分析与研究

变速传动轴承是一种既具有支承功能又具有变速功能的新型特种轴承 ,其机构设计新颖紧凑 ,效率高 ,承载能力强。通过研究变速传动轴承的内部机构和传动原理 ,对其传动比做了深入系统的分析 ,得出了内齿圈齿数、活齿数与传动比之间的理论关系 ,并从理论上提出了高效率、低磨损的传动比优选方案 ,认为在推杆活齿传动机构设计时 ,应该使活齿数大于内齿圈齿数 ,即Z2 >Z1。包括变速传动轴承在内 ,对于采用了推杆活齿机构的各种活齿传动形式的结构设计 ,这个结论都具有重要的指导意义。     

一类不确定大系统的分散变结构模型跟随控制

针对一类具有不确定参数和外界扰动的非线性大系统 ,在子系统互连项上界具有多项式形式的条件下 ,提出了一种分散变结构模型跟随控制器设计方案。该控制器不需要未知参数变化、外界扰动以及子系统互连上界的先验信息 ,能够通过自适应率对上述信息进行在线估计。在保证闭环大系统渐近稳定的条件下 ,同时实现了各个子系统滑动模态的存在性和可达性。理论分析和仿真结果验证了本文所提方案的有效性     

正弦波型直流无刷电动机位置伺服系统的变结构控制

在分析正弦波型直流无刷电动机数学模型的基础上,采用比例等速变速控制策略(PCV)设计控制器,应用于正弦波型直流无刷电动机位置伺服系统.仿真结果表明:与传统PI控制器比较,PCV控制策略可以明显改善系统的品质,并增强系统的鲁棒性.     

试论我国高校就业指导体系的建构问题

从二十世纪八十年代开始,我国对普通高校教育体制进行改革,并取得很大成绩,使高等教育的规模有了跨越式的发展,质量与效益也同时大幅度提高。1999年开始的连续几年高校扩招使我国的高等教育从"精英化高等教育"快速步入"大众化高等教育"时代,但同时也使扩招后毕业生的就业成为亟待解决的问题。高校毕业生就业率成为对高校培养人才质量的检验指标,以及对高校社会适应性的检验指标,与学校的生存与发展紧密相连。面对产业结构的调整和高校毕业生大幅度增加的双重压力,高校就业指导工作日显重要,建立一支高水准,高效率的就业指导队伍成为高校建设中应优先解决的问题之一。