聚氨酯与铁电陶瓷粉复合物的电致感应性能研究

利用双辊制备了一系列热塑性弹性体聚氨酯 (PU )和铁电钛酸锆酸铅盐 (PZT)的电致感应PZT/PU复合物。X -衍射和SEM扫描电镜结果显示 ,复合物中 ,在铁电相中PZT陶瓷粉呈现结晶态并且均匀分布在PU基体中。复合物的弹性模量和相对电容率随着复合物中PZT体积分数增加而升高。在高压电场下 ,低PZT含量的复合物呈现负的电致伸缩应力 ,当PZT体积分数增加到 6 %以上时 ,在某个临界电场下 ,复合物呈现出电致伸缩应力反转的特性 ,即电致伸缩应力从负转变为正 ,并且发生应力反转的临界电场随着复合物中PZT体积分数的增加而降低。PU的电致伸缩特性与PZT在高电场下极化反转效应结合 ,导致了PZT/PU复合物这种有趣的性能。

集成位移传感功能的磁流变阻尼器自感应性能磁场分析

介绍了一种集成位移传感功能的新型磁流变阻尼器结构及其工作原理.采用ANSYS有限元仿真软件分析了与阻尼器动力性能相关的静态磁场,结果表明对激励线圈施加电流值越大,其磁感应强度也越大.同时对阻尼器的自感应性能进行了谐波磁场仿真分析,仿真结果表明自感应电动势幅值与活塞相对位移成线性比例关系;另外,静态拉伸实验结果也表明自感应电动势幅值与位移保持线性变化,实验测量值与理论值偏差整体在10%以内.仿真和实验结果表明所设计的磁流变阻尼器除了具备常规阻尼力可控功能外,还具有位移自感应性能.

一个新的边端效应系数及其对直线感应电动机性能影响的研究

结合 Gieras 纵向边端效应系数和 Nasar 品质因数,给出了一个新的边端效应系数.新的边端效应系数综合考虑纵向边端效应,横向边端效应,气隙漏磁及次级集肤效应等因素,可以方便地用来分析和计算直线感应电动机的性能.

提高阳光感应性能的Fe—Si—Cr铁芯

日本动力感应公司在阳光感应线圈MDPK5050上采用添加Ni和Mn的Fe—Si—Cr金属材料，取代原先的铁氧体，使其直流叠加特性，即每个制品的电流流动性提高了1．7倍。

高性能感应电机的参数计算及动态仿真分析

针对感应电机轻载运行时功率因数低的问题,提出一种高性能感应电机,这种电机通过改变电机起动和运行时绕组线圈的数量,使电机既能满足重载起动要求又具有良好的轻载运行性能。通过与同类型常规感应电机对比,计算两种电机在起动和运行时的主要性能参数,确认高性能感应电机的主要性能指标可达到预期目标。最后,基于电机状态方程编写了高性能感应电机动态起动过程仿真程序。借助M ATLA B软件仿真平台,对高性能电机绕组切换过程进行动态仿真分析,仿真结果证明了高性能感应电机绕组切换是可行的。

基于不同金属氧化物的甲醛气体传感器的研究进展

甲醛是一种致癌、致基因突变的有毒污染物,会对人类的身体健康造成严重威胁。近年来,甲醛监测技术不断创新,基于SnO_(2)、In_(2)O_(3)、ZnO等金属氧化物的甲醛传感器,因其响应快、工作稳定、成本低、制造简单等优点而得到广泛的研究与关注。综述了近些年基于不同金属氧化物的甲醛气体传感器的发展现状,讨论了不同传感器的制备方法、感应性能及存在问题,并展望了金属氧化物甲醛传感器的发展趋势,为将来甲醛传感器的研制提供了思路。

Uniaxial compressive behavior of equal channel angular pressing Al at wide temperature and strain rate range

Uniaxial compressive experiments of ultrafine-grained Al fabricated by equal channel angular pressing(ECAP) method were performed at wide temperature and strain rate range. The influence of temperature on flow stress, strain hardening rate and strain rate sensitivity was investigated experimentally. The results show that both the effect of temperature on flow stress and its strain rate sensitivity of ECAPed Al is much larger than those of the coarse-grained Al. The temperature sensitivity of ultrafine-grained Al is comparatively weaker than that of the coarse-grained Al. Based on the experimental results, the apparent activation volume was estimated at different temperatures and strain rates. The forest dislocation interactions is the dominant thermally activated mechanism for ECAPed Al compressed at quasi-static strain rates, while the viscous drag plays an important role at high strain rates.

始终开启（（A1ways-On））6轴惯性运动传感器

新系列6轴传感器具有优异的感应性能，可检测屏幕方向和手势，为应用开发人员和消费者提供更精密复杂的功能。只要缓慢地旋转手机即可拍照360°的全景图，或者挥一下胳膊即可滑动地图屏幕。

心掌控追逐 RIDE 8

关于跑鞋的减重，大幅的减配并不能称得上优质，而是要在全画提升的同时争取重量的降低，Saucony这款最新打造的Ride 8中性运动鞋将高性能训练鞋以跑者为灵感，与跑鞋的超凡感应性能相结合。

为触控应用优化的低功耗8位微控制器

低功耗的ATtiny10／20／40微控制器系列专门针对按键、滑块和滑轮等触控感应应用予以优化，具有低功耗特点和极佳的触控感应性能。该系列产品以高性能的AVRMCU为基础，包括一个RISC控制器架构、优化的触控电路，

可自然降解的高灵敏度传感器

目前，生物相容性微传感器的生产还是一个非常耗时和昂贵的过程，现有的传感器或是感应性能十分有限，或是生物相容性还未经证明。英国《自然·电子学》杂志在线发表的美国退伍军人事务部佩吉·福克斯、斯坦福大学鲍哲南研究小组报告的一种完全由生物可相容材料构成的、可移植、可伸展的应变及压力传感器，可以在有效使用期结束后自然降解，其灵敏度分别达到0．4％和12Pa.

Energy consumption in rock fragmentation at intermediate strain rate

In order to determine the relationship among energy consumption of rock and its fragmentation, dynamic strength and strain rate, granite, sandstone and limestone specimens were chosen and tested on large-diameter split Hopkinson pressure bar (SHPB) equipment with half-sine waveform loading at the strain rates ranging from 40 to 150 s- 1. With recorded signals, the energy consumption, strain rate and dynamic strength were analyzed. And the fragmentation behaviors of specimens were investigated. The experimental results show that the energy consumption density of rock increases linearly with the total incident energy. The energy consumption density is of an exponent relationship with the average size of rock fragments. The higher the energy consumption density, the more serious the fragmentation, and the better the gradation of fragments. The energy consumption density takes a good logarithm relationship with the dynamic strength of rock. The dynamic strength of rock increases with the increase of strain rate, indicating higher strain rate sensitivity.

Influence of pre-stretching on quench sensitive effect of high-strength Al-Zn-Mg-Cu-Zr alloy sheet

The influence of pre-stretching on quench sensitive effect of high strength Al-Zn-Mg-Cu-Zr alloy AA 7085 sheet was investigated by tensile testing at room temperature,transmission electron microscopy(TEM)and differential scanning calorimetry(DSC).The water-cooled and aged alloy exhibits higher strength than the air-cooled and aged alloy;2.5%pre-stretching of tensile deformation exerts little effect on strength of water-cooled and aged alloy but increases that of air-cooled and aged one,and therefore the yield strength reduction rate due to slow quenching decreases from about 3.8%to about 1.0%,reducing quench sensitive effect.For the air-cooled alloy,pre-stretching increases the sizes ofη'strengthening precipitates but also increases their quantity and the ratio of diameter to thickness,resulting in enhanced strengthening and higher strength after aging.The reason has been discussed based on microstructure examination by TEM and DSC.

Effect of vacuum degree in VIM furnace on mechanical properties of Ni-Fe-Cr based alloy

In order to investigate the effect of the vacuum degree in vacuum induction melting （VIM） furnace on the mechanical properties of Ni-Fe-Cr based alloy, four samples were prepared under different conditions. The chemical analysis results show that under the argon atmosphere, there is more dissipation in Al and Ti, whereas it is reduced by establishing the vacuum atmosphere. The gas analysis results show that the oxygen and nitrogen contents of the samples decrease with increasing vacuum degree. However, there is no dissipation in the gas content of the samples in higher degree of vacuum. In addition, the thermodynamic calculations show that the probability of TiO2 and Al2O3 formation is high due to the small value of the equilibrium oxygen. Higher vacuum degree reduces the tensile and yield strength of the alloys, while it enhances the elongation and reduction of area values due to the lower amount of the inclusions and evaporation of Al and Ti under higher vacuum. On the other hand, increasing vacuum degree changes the fracture mode from brittle to ductile.

Specific Heat and Charge Density of Quasi-One-Dimensional Interchain Coupling Organic Ferromagnets

On the basis of a generalized SSH model, an organic polymer ferromagnet theory is proposed at the finite temperature in the self-consistent mean field approximation, and the specific heat and charge density of the quasione-dimensional interehain coupling organic ferromagnets are presented. We find that an obvious feature is to present itself the round peak for the specific heat with the temperature. This indicates unambiguously the presence of the phase transition in the system. The transition temperature plays down with increasing of the interchain coupling t2 or decreasing of the electron repulsion u. The curves of charge density with the temperature debase monotonously. This result illustrates that the higher the temperature is, the more electrons are excited.

Electrical properties of carbon nanotubes in flowing vapor

Electric potentials were generated from carbon nanotubes immersed in flowing vapors. The nanomaterials used in this study were multiwall carbon nanotubes（MWCNTs） and silver nanopowders. These nanomaterials were dispersed and densely packed on a substrate and immersed in flowing vapors generated from solution such as water, ethanol and KCI. The potentials generated from these samples were measured by a voltmeter. Experimental results showed that the electric potentials were produced at the surface of the MWCNT samlpes, and strongly dependent on the pretreatment of MWCNT and properties of the flowing vapors. The mechanism of vapor-flow induced potentials may be ascribed to ions in the flowing vapors. This property of MWCNTs can advantage their application to nanoscale sensors, detectors and power cells.

Effect of processing parameters on flow behaviors and microstructure during high temperature deformation of GH4586 superalloy

The apparent activation energy for deformation(Q)and strain rate sensitivity(m)of GH4586 superalloy are calculated and the variation trend is reasonably explained by the microstructure observations.Constitutive modelling of this superalloy is established and the processing maps at different strains are constructed.The results show that the Q value is in the range of 751.22−878.29 kJ/mol.At a temperature of 1060°C,strain rate of 0.001 s^(−1),and strain of 0.65,the m value of GH4586 superalloy reaches a maximum of 0.42.The optimal processing parameter of GH4586 superalloy is at a deformation temperature of 1050°C and a strain rate of 0.001 s^(−1).The domains of flow instability notably expand with increasing strain during high temperature deformation of GH4586 superalloy.

Effects of induction heat treatment on mechanical properties of TiAl-based alloy

The effects of rapid heating cyclic heat treatment on mechanical properties of a TiAl based alloy (Ti 33Al 3Cr) were studied by means of an induction heating machine. The results show that: 1) fine fully lamellar microstructure with colony size of about 50 μm and lamellar spacing of about 0.12 μm can be obtained; 2) the compression mechanical properties can be improved to a large extent and the best comprehensive compression mechanical properties can reach the yield stress 745 MPa, the large flow stress 1 672 MPa and the compression ratio 19.4%; and 3) the compression fracture at room temperature after induction heat treatment and aging is still typical cleavage fracture.

Understanding the Effect of the Exchange-Correlation Functionals on Methane and Ethane Formation over Ruthenium Catalysts

Density functional theory(DFT)has been established as a powerful research tool for heterogeneous catalysis research in obtaining key thermodynamic and/or kinetic parameters like adsorption energies,enthalpies of reaction,activation barriers,and rate constants.Understanding of density functional exchangecorrelation approximations is essential to reveal the mechanism and performance of a catalyst.In the present work,we reported the influence of six exchange-correlation density functionals,including PBE,RPBE,BEEF+vdW,optB86b+vdW,SCAN,and SCAN+rVV10,on the adsorption energies,reaction energies and activation barriers of carbon hydrogenation and carbon-carbon couplings during the formation of methane and ethane over Ru(0001)and Ru(1011)surfaces.We found the calculated reaction energies are strongly dependent on exchange-correlation density functionals due to the difference in coordination number between reactants and products on surfaces.The deviation of the calculated elementary reaction energies can be accumulated to a large value for chemical reaction involving multiple steps and vary considerably with different exchange-correlation density functionals calculations.The different exchange-correlation density functionals are found to influence considerably the selectivity of Ru(0001)surface for methane,ethylene,and ethane formation determined by the adsorption energies of intermediates involved.However,the influence on the barriers of the elementary surface reactions and the structural sensitivity of Ru(0001)and Ru(1011)are modest.Our work highlights the limitation of exchange-correlation density functionals on computational catalysis and the importance of choosing a proper exchange-correlation density functional in correctly evaluating the activity and selectivity of a catalyst.