Sharpening polycrystalline phase boundary for potassium sodium niobate ceramics with MnF2 modification

The influence of anion on structure and performance is unclear in potassium sodium niobate ((K,Na)NbO₃; KNN)-based ceramics, while cation doping has been widely researched. Here, the phase structure and electrical properties are explored in MnF₂-doped KNN ceramics. Significantly, sharp rhombohedral–orthorhombic (R–O) and orthorhombic–tetragonal (O–T) phase boundary as well as reduced diffusion degree is exhibited in the ceramics along with little changed phase transition temperatures due to the optimized F⁻ content at O site, which is different from that of cation replacement for A and B sites. Notably, the domain wall motion is facilitated due to the increased A vacancy and decreased O vacancy along with strengthened polarity, originating from the higher valence state and electronegativity of F⁻ with respect to O²⁻. And then, enhanced ferroelectricity is realized via MnF₂ modification, the piezoelectricity is elevated in turn. This work presents a new idea of anion doping for controlling structure and properties in perovskite materials.     

A New Clearance Design Method for Reciprocating Fuel Pumps of Medium-Speed Diesel Engines

A new clearance design method is proposed for a reciprocating fuel pump. Structural and hydrodynamic lubrication analyses were conducted to design the clearance of the pump, and the former was used to evaluate the clearance reduction due to the deformation that results from applying maximum supply pressure. The reduction in the maximum clearance was used as the limit of the design, and the two-dimensional Reynolds equation is used to evaluate the lubrication characteristics of the pump with variations in the viscosity and clearance. The optimal clearance in the pump must be separately designed in both the stem and the head because the lubrication characteristics and the deformation patterns of the two parts are different. The validity of the numerical model was then verified by determining that the position of the wear was also similar to that of the minimum film thickness. Moreover, a rig test system was also used to verify the clearance of the proposed design method.     

移动学习App在客观题备考中的应用研究

移动学习app是一种新兴的教育技术,客观题是标准化考试的一种主要形式。本文以参加高级职业资格证考试的本校学生为实验对象,通过云班课app设计测验、头脑风暴、投票问卷等40余项多元化备考活动,研究了移动学习app在客观题备考中的应用方法及应用效果。实践数据分析表明,移动学习app满足了学生不受时空限制的个性化学习的需求,提高学生学习客观题的积极性和学习效率,并大幅提高了学习成绩和考试合格率。     

Comparison of ablative and compressive mechanical behavior of several PICA-like ablative materials

It is significant to compare the ablative and compressive mechanical behavior of different PICA-like materials in the engineering applications. The plasma wind tunnel ablation tests with high-entropy air and CO_2 atmospheres, and compressive experiments in the ambient and 150℃, were conducted for three kinds of PICA-like materials(CF/PR-Si, CBCF/PR-SiOC and NQF/PR-Si composites). The traditional carbon/phenolic(C/PR) braided composites were also used for comparison. PICA-like materials have the better thermal insulation than traditional C/PR composite, especially for CBCF/PR-SiOC composite. The ablation behavior of CF/PR-Si and CBCF/PR-SiOC PICA-like materials in the CO_2 atmosphere can produce a large amount of SiO_2 in the form of coatings, oxide layers and skeletons on the ablated surface, which are greatly different from that in the air atmosphere.The compressive behavior of PICA-like material is greatly depended on the fiber fabrics, and exhibits the large discrete characteristics. The longer fiber in the PICA-like materials plays the role in maintaining the material integrity, while it may increase the thermal conductivity.     

Generation of simultaneous H+ and He+ band EMIC waves in the nightside radiation belt

Science China Technological Sciences - Previous studies have shown that EMIC waves occur preferentially in the afternoon sector of the magnetosphere. Here we report obliquely propagating H+ and He+...     

AT1200型斜天井钻机的研制与改进

为了解决倾斜矿体开采中斜天井掘进问题，我院新开发了我国第一代斜天井钻机产品。本文较详细地介绍了其设计思想，并对工业试验情况进行了分析。经过三个阶段的反复试验和改进后，使该设备具有优良的技术性能和使用效果。     

影响砂金矿资源可靠性的因素及改进措施

近些年砂金生产企业相继出现重大投资失误，造成严重经济损失，这都是因为地质资源不可靠所造成的。造成地质资源不可靠的原因既有技术方面的，也有人为方面的．对这两方面的原因进行了分析、阐述，并针对性地提出了改进措施：修改现行砂金矿勘探技术规范、实行小规模试验性开采、业主提前介入监督。     

Biomolecular Structure and Dynamics with Neutrons: The View from Simulation

The characterization of the structure and internal dynamics of biomolecules is essential to understanding their biological function. Neutron scattering probes similar time- and length-scales to molecular dynamics simulation. Hence, simulation models of biomolecules have become invaluable in the interpretation of experimental neutron data. Here, we report on advances in the application of simulation in developing neutron scattering to investigate internal protein motions and, as an example of industrial relevance, in the derivation of physical models of use in biofuel renewable energy research.     

Pipelining image compositing in heterogeneous networking environments

Because of intensive inter‐node communications, image compositing has always been a bottleneck in parallel visualization systems. In a heterogeneous networking environment, the variation of link bandwidth and latency adds more uncertainty to the system performance. In this paper, we present a pipelining image compositing algorithm in heterogeneous networking environments, which is able to rearrange the direction of data flow of a compositing pipeline under strict ordering constraint. We introduce a novel directional image compositing operator that specifies not only the color and α channels of the output but also the direction of data flow when performing compositing. Based on this new operator, we thoroughly study the properties of image compositing pipelines in heterogeneous environments. We develop an optimization algorithm that could find the optimal pipeline from an exponentially large searching space in polynomial time. We conducted a comprehensive evaluation on the ns‐3 network simulator. Experimental results demonstrate the efficiency of our method. Copyright © 2016 John Wiley & Sons, Ltd.