高温预析出对Al-Zn-Mg-Cu铝合金显微组织、强度和应力腐蚀抗力的影响

通过改变固溶条件 ,对Al Zn Mg Cu高强铝合金采用先高温后低温的两步固溶处理 (高温预析出 )来改善晶内和晶界的析出状态 ,研究了高温预析出对Al Zn Mg Cu铝合金的金相组织、强度和应力腐蚀性能的影响。结果表明 ,4 6 5℃高温预析出在保持较高强度和塑性的同时 ,可以改善合金的抗应力腐蚀性能     

Investigation into the thermo-viscoplastic finite element analysis of square die extrusion of square section with Lagrangian description

An analysis of three-dimensional hot extrusion through landless square dies is carried out as a nonsteady-state problem. In the problem, difficulties arise from the severe distortion and die interference of elements at the aperture rim of the die, even with a small punch travel. Finite element simulation is impossible without intermittent remeshing procedures. To overcome these difficulties, an automatic remeshing technique is proposed by employing a modular conceptual mesh structure. In the analysis of temperature distribution, conduction, convection and radiation are considered in connection with a deformation analysis of a visco-plastic material. The effect of the mesh structure on the present scheme as well as material properties and temperatures associated with punch travel is discussed. As an example, an extrusion of a square section is simulated. In order to confirm the present scheme, experiments are carved out using aluminium at the elevated temperature.     

时效对接触线用Cu-Ag-Cr合金性能的影响

分析了固溶温度、时效及时效前冷变形量对Cu - 0 1 %Ag - 0 1 %Cr接触线用合金性能的影响 ,结果表明 :经 870℃固溶、 40 %～ 5 0 %冷变形及 480℃× 1 5h时效处理后 ,合金可获得良好的综合性能。     

当前我国在学位价值取向上的错位现象及其原因透视

学位具有学术价值、教育价值、管理价值等本体性价值，也具有个体价值与社会价值、工具性价值和目的性价值等派生性价值。当前人们在学位价值取向上存在着一些明显的错位和偏差。其具体表现有四点：一是重学位的“派生”性价值，轻学位的“本体”性价值；二是过分强调学位的教育价值和管理价值，而缺乏对学术价值应有地位的肯定；三是重学位的社会价值，轻学位的个体价值；四是重学位的工具性价值而忽视学位的目的性价值。导致这种错位现象产生的原因，不仅有教育系统内部因素，而且也与中国传统文化价值观和当前社会对人才的选拔、聘用政策有着直接的关系。     

基于Excel VBA的职称评审专家抽取系统的设计与实现

通过对职称评定过程中专家抽取流程和原则的分析,针对人工抽取的弊端,使用Excel及VBA设计实现了一个操作简单、维护方便的专家抽取系统。实践证明该系统运行可靠性强,有效提高了工作效率,真正实现了专家抽取的公开、公正和公平性。     

机器视觉在水稻空壳率统计中的应用研究

针对水稻空壳率的自动化检测问题,采用机器视觉技术,设计一种实验设备,利用稻谷的透光性,使用普通可见光照射,对获得的图像进行分析处理,并比较采用灰度特征以及YUV颜色模型两种方法进行统计的结果,表明该设备和相关图像处理算法完全可以胜任空壳率的自动统计工作,为后续发展实际的应用设备奠定基础。     

An energy-efficient real-time scheduling scheme on dual-channel networks

The recent evolution of wireless sensor networks have yielded a demand to improve energy-efficient scheduling algorithms and energy-efficient medium access protocols. This paper proposes an energy-efficient real-time scheduling scheme that reduces power consumption and network errors on dual channel networks. The proposed scheme is based on a dynamic modulation scaling scheme which can scale the number of bits per symbol and a switching scheme which can swap the polling schedule between channels. Built on top of EDF scheduling policy, the proposed scheme enhances the power performance without violating the constraints of real-time streams. The simulation results show that the proposed scheme enhances fault-tolerance and reduces power consumption.     

An automatic docking method for large-scale sections based on real-time pose measuring and assembly deviation control

Aiming at the problem of poor accuracy consistency of large sections’ docking assembly, an automatic docking method using multiple laser trackers to measure the position and posture of the docking sections in real time was proposed. In the solution of the pose of the docking section, real-time pose measurement of the docking section was realized by establishing a global coordinate system and a coordinate fusion method of three or more laser trackers. In the automatic control of the docking process, the real-time communication protocol and the circular negative feedback control strategy of measurement-adjustment-re-measurement are adopted, and the fully-automated docking of large sections is realized. Finally, an experimental verification system was set up, and the docking of the large-scale section reduction models was realized under the requirements of docking accuracy, and the effectiveness of the automatic docking scheme was successfully verified.     

Small Changes,Big Impact: Tungsten Bronzes with Extremely Large Second Harmonic Generation Achieved by the Transition Metal Doping on the B-Site

Two novel transition metal-doped tungsten bronze oxides, Pb_2.15Li_0.85Nb_4.85Ti_0.15O₁₅ (PLNT) and Pb_2.15Li_0.55Nb_4.85W_0.15O₁₅ (PLNW), are synthesized by high-temperature solid-state reactions. The Rietveld method using the high-resolution synchrotron radiation indicates that PLNT and PLNW crystallize in the orthorhombic polar noncentrosymmetric space group, Pmn2₁ (no. 31). As a class of tungsten bronze oxide, PLNT and PLNW retain a unique rigid framework composed of d⁰ transition metal cation (Ti⁴⁺ or W⁶⁺)-doped highly distorted NbO₆ octahedra along with the subsequently generated Pb/LiO₁₂ and PbO₁₅ polyhedra. Interestingly, the d⁰ transition metal-doped tungsten bronzes, PLNT and PLNW, exhibit extremely large second-harmonic generation (SHG) responses of 56 and 67 × KH₂PO₄, respectively. The observed immeasurably strong SHG is mainly attributed to a net polarization originating from the alignment of highly distorted NbO₆ octahedra with doped transition metals in the frameworks. It is believed that doping transition metal cations at the B-site of the tungsten bronze structures should be an innovative strategy to develop novel high-performance nonlinear optical materials.     

Relational attention-based Markov logic network for visual navigation

The Journal of Supercomputing - We argue the agent’s low generalization problem for searching target object in challenging visual navigation could be solved by "how" and...