A semantic-level component-based scheduling method for customized manufacturing

To meet the increasingly complex needs of customers, scheduling faces challenges of the high uncertainty of product arrival in customized manufacturing (CM). This paper proposes a semantic-level component-based scheduling method to solve the uncertainty via the integration of the information model and the computation model. In our proposal, we first construct a component-based framework to illustrate the composition and execution mechanism of a component. Then we present a semantic-enriched information model to obtain the state of the shop floor through automatic semantic reasoning. Additionally, we build a computation model to abstract the stochastic scheduling process of CM. Finally, we design an iteration algorithm to solve the computation model through the interaction between the information model and computation model. In experiments, we show that for random arrivals of products, our proposal can ensure the timeliness of the learning and decision-making, and the task assignment performance is the best compared with the other two methods.     

对大中型钢结构企业生产管理体系的研究分析

以某大型钢结构制造企业为例,通过对产量分布、质量控制、劳动效率等基本数据的分析,研判外协生产管理体系方面存在的问题,从组织形态、管理模式、职能管理等多个维度提出了可行性建议,可为同类型钢结构制造企业提供经验借鉴。     

预压力对压电驱动履带移动系统的性能影响

为了提高夹心式压电驱动移动系统的机械输出性能，提出了一种U型预压力调节机构，并开展了预压力对夹心式压电驱动履带移动系统输出性能影响关系的实验研究。首先，针对U型预压力调节机构的安装对夹心式压电振子的振动特性影响关系开展了有限元仿真分析，发现U型预压力调节机构始终处在夹心式压电振子的两相工作模态振动节点位置；其次，开展了夹心式压电驱动履带移动系统的原理样机的预压力调节测试实验，确定了系统的最大输出牵引力及其所对应的最佳预压力；最后，在最佳预压力工作状态下，开展了原理样机的牵引力特性、越障性能以及模拟月壤环境下的运动特性实验。研究结果表明，在最佳预压力工作状态下，夹心式压电驱动履带移动系统的机械输出性能最佳，为其进一步在月面巡视器上的应用提供了技术支持和试验基础。     

Elasticity solution for the casing under linear crustal stress

The integrity of the casing is crucial for oil and gas well. Based on stress function method, a three-dimensional model of the casing-cement sheath-formation system subjected to linear crustal stress is proposed. And then an analytical solution of the model was obtained. In the process of calculation, the casing and cement sheath are simplified as the perfect cylinder. The cement sheath is closely bonded with the casing and formation. The formation is considered to be an isotropic material without the layer-block structure. And the crustal stress is assumed to be linearly increasing with the depth of the well. The analytical solution strictly meets the stress and displacement continuity condition and boundary condition, and exhibits good agreement with finite element method. The results imply that an analytical method to capture the stress and displacement field of the casing under linear crustal stress along the axis is presented. Next, a benchmark for numerical and approximate solutions is provided. In addition, a new idea about solving the casing under the non-linear loads along the axis in some special stratum (such as heterogeneity stratum, salt rock) is proposed. Finally, our understanding for the casing under complex loads will be deepened.     

Effect of cerium oxide prepared under different hydrothermal time on electrocatalytic performance of Pt-based anode catalysts

In this paper,CeO_2 with a pore size of 2-4 nm was synthesized by hydrothermal method.The CeO_2 modified graphene-supported Pt catalyst was prepared by the microwave-assisted ethylene glycol reduction chloroplatinic acid method,and the effect of the addition of CeO_2 prepared by different hydrothermal reaction time on the catalytic performance of Pt-based catalysts was investigated.The microstructures of CeO_2 and catalysts were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),specific surface area and pore size analyzer(BET),scanning electron microscopy(SEM) and electron spectroscopy(EDAX),transmission electron microscopy(TEM),and the catalysts electrochemical performance was tested by electrochemical workstation.The results show that the catalytic performance of the four catalysts with CeO_2 is better than that of the catalyst without CeO_2.Adding CeO_2 with a specific surface area of 120.15 m~2/g prepared by hydrothermal reaction time of 39 h to Pt/C synthesis catalyst,its electrocatalytic performance,stability and resistance to poisoning are the best.The electrochemical active surface area is 102.83 m~2/g,the peak current density of ethanol oxidation is 757.17 A/g and steady-state current density of 1100 s is 108.17 A/g which shows the lowest activation energy for ethanol oxidation reaction.When the cyclic voltammogram is scanned for 500 cycles,the oxidation peak current density retention rate is 87.74%.     

Fabrication of dense Al2O3-FeAl composites by using solid-state sintering

Highly densified alumina-iron aluminide (Al₂O₃-FeAl) composites consisting of ubiquitous elements were fabricated by using pulse current sintering technique under a certain uni-axial pressure. The solid-state sintering without melting FeAl was the highlight in this study. The mechanical properties of the Al₂O₃-FeAl composites were much greater than previously reported ones fabricated by reaction sintering technique. The poor wettability of FeAl against Al₂O₃ strongly influenced the mechanical properties and made it difficult to be highly densified Al₂O₃-FeAl composites by liquid phase sintering especially when volume fraction of FeAl to Al₂O₃-FeAl was high (>30.5 vol%). However, highly densified Al₂O₃-FeAl composites were obtained by solid-state sintering with control of Al₂O₃ grain size and sintering temperatures. It was concluded that highly controlled powder metallurgy made it possible to fabricate dense ceramic-metal (intermetallic) composites from the combination of materials having poor wettability.     

Efficient cathode contacts through Ag-doping in multifunctional strong nucleophilic electron transport layer for high performance inverted OLEDs

This paper presents an efficient and stable green inverted organic light emitting diode (IOLED) using multifunctional and strong nucleophilic quality electron transport material (1,3-bis(2-phenyl-1,10-phenanthrolin-4-yl)benzene (m-bPPhenB)) with silver (Ag) as an n-dopant. By the energy level alignment study using in-situ ultraviolet photoelectron spectroscopy measurement, negligible electron injection barrier between indium tin oxide (ITO) and Ag-doped m-bPPhenB (Φ_e ≈ 0.03 eV) is observed and the electrons can be easily tunneled from ITO into Ag-doped m-bPPhenB layer. Also, Ag dopant forms coordination bonds with phenanthroline based unit, which improves electron injection from ITO. Fabricated IOLED devices using an Ag-doped m-bPPhenB have an extremely low driving voltage of 3.6 V and external quantum efficiency of 29.0%. Such good performances of IOLED are attributed to negligible electron injection barrier at the interface between ITO and Ag-doped m-bPPhenB. The Ag-doped IOLED device also shows a good air stability owing to the stable Ag n-dopant. The doping of Ag into special electron transport layer in the IOLED structure could be applicable to various displays and lighting applications.     

基于数据驱动建模的核电站一回路管道劣化趋势研究

提出一种基于管道状态数据的分析方法，可得到管道劣化趋势，有助于预防管道劣化引起的泄漏。具体方法是通过融合主观专家经验层次分析法和客观大数据分析熵权法的优点，定量地构建一回路管道的改进马氏距离健康度模型，进而应用融合卷积神经网络和长短期记忆神经网络的组合预测模型，对一回路管道未来的劣化泄漏情况做出趋势分析和预判。仿真结果表明，构建的健康度模型能够较好的反映出一回路管道的真实健康状态；组合 预测模型可以有效地预测一回路管道劣化泄漏的趋势，为保障设备的安全稳定运行提供 参考。     

Fatigue behaviour of WC-Co hard metal under stress ratio and effectively loaded volume relevant to metalworking tool failure

WC-Co hard metals have proven to be excellent tool materials capable of coping with the elevated cyclic load levels that arise in e.g. metalworking tool application. The design of cyclically loaded tools requires reliable information on the fatigue behaviour of hard metals, also as a function of the acting mean stress. Since hard metals show defect controlled fracture behaviour, the nature of defects and their size distribution in the volume of given loaded structures is relevant to their fatigue behaviour. The concept of effectively loaded volume V_eff allows for the comparison of the fracture probability of loaded structures with different kinds of stress distributions. To date, V_eff of laboratory test setups and metalworking tools and its influence on the fatigue behaviour was not considered in the respective design processes. Instrumented milling experiments in combination with finite element based load analysis were used in the current work to provide information on typical values of stress ratio and V_eff for end milling tools. A newly developed non-conventional type of a six point bending test setup was designed to induce values of V_eff and mean stress which were found to be representative for the metalworking tool. The shape of the used central specimen support structures was designed to avoid contact damage to the specimen at the sites of load transfer. The knowledge-based design of the six point bending test setup assures that a region of the hard metal's bimodal defect size distribution is probed that leads to fatigue limits relevant to the failure behaviour of end milling tools.