方钢管橡胶混凝土短柱的轴压力学性能试验

为了研究钢管橡胶混凝土柱的轴压力学性能,对8个方钢管橡胶混凝土短柱进行轴压试验;探讨橡胶粉体积取代率和橡胶粉粒径对其力学性能的影响,给出了方钢管橡胶混凝土轴压承载力计算公式.结果表明:随着橡胶粉体积取代率的增加,方钢管橡胶混凝土极限承载力和刚度均有下降的趋势;随着橡胶粉粒径的增大,方钢管橡胶混凝土极限承载力和刚度也有所下降;由本文给出的轴压承载力计算公式所得到的计算结果与试验结果总体上较为吻合,可用来预测方钢管橡胶混凝土的截面强度.     

3特征域椭圆曲线群点的快速计算算法

GF(3m)作为小素数扩域GF(Pm)更加特殊的一种类型,定义于其上的椭圆曲线密码算法更加优越.基于有限域GF(3m)特殊性质,详细研究了GF(3m)上椭圆曲线群基本点算术运算,给出并证明了GF(3m)上超奇异和非超奇异椭圆曲线在仿射、射影、雅可比、Chudnovsky雅可比和López Dahab坐标系下普通点加、混...     

柠檬酸对小麦面筋蛋白的脱酰胺作用

以盐酸对小麦面筋蛋白的脱酰胺作用效果为参比,选取氯溶指数、脱酰胺程度为表征指标,利用SDS-PAGE、FTIR和SEM研究柠檬酸脱酰胺改性过程中小麦面筋蛋白分子构象和功能特性的内在关系.试验结果表明:在相同的脱酰氨程度下,柠檬酸脱酰胺改性明显改善小麦面筋蛋白的起泡性,其改性蛋白的起泡性是盐酸脱酰胺改性样品的4倍;当脱酰...     

Stability margin of the quadruped bionic robot with spinning gait

Spinning gait is valuable for quadruped robot, which can be used to avoid obstacles quickly for robot walking in unstructured environment.A kind of bionic flexible body is presented for quadruped robot to perform the spinning gait.The spinning gait can be achieved by coordinated movement of body laterally bending and legs swing, which can improve the mobility of robot walking in the un-structured environments.The coordinated movement relationship between the body and the leg mechanism is presented.The stability of quadruped robot with spinning gait is analyzed based on the center of gravity ( COG) projection method.The effect of different body bending angle on the stabili-ty of quadruped robot with spinning gait is mainly studied.For the quadruped robot walking with spinning gait, during one spinning gait cycle, the supporting polygon and the trajectory of COG pro-jection point under different body bending angle are calculated.Finally, the stability margin of quadruped robot with spinning gait under different body bending angle is determined, which can be used to evaluate reasonableness of spinning gait parameters.     

Microstructure evolution and mechanical properties of a large-sized ingot of Mg-9Gd-3Y-1.5Zn-0.5Zr (wt%) alloy after a lower-temperature homogenization treatment

In this paper, a large-sized ingot of Mg-9Gd-3Y-1.5Zn-0.5Zr (wt%) alloy with a diameter of 600 mm was successfully prepared by the semi-continuous casting method. The alloy was subsequently annealed at a relatively low temperature of 430℃ for 12 h as a homogenization treatment. The microstructure and room-temperature mechanical properties of the alloy were investigated systematically. The results show that the as-cast alloy contained a mass of discontinuous lamellar-shaped 18R long-period stacking ordered (LPSO) phases with a composition of Mg₁₀ZnY and an α-Mg matrix, along with net-shaped Mg₅(Y,Gd) eutectic compounds at the grain boundaries. Most of the eutectic compounds dissolved after the homogenization treatment. Moreover, the amount and dimensions of the lamellar-shaped LPSO phase obviously increased after the homogenization treatment. The structure of the phase transformed into 14H-type LPSO with composition Mg₁₂Zn(Y,Gd). The mechanical properties of the heat-treated large-sized alloy ingot are uniform. The ultimate tensile strength (UTS) and tensile yield strength (TYS) of the alloy reached 207.2 MPa and 134.8 MPa, respectively, and the elongation was 3.4%. The high performances of the large-sized alloy ingot after the homogenization treatment is attributed to the strengthening of the α-Mg solid solution and to the plentiful LPSO phase distributed over the α-Mg matrix.     

MNi4.8Sn0.2（M=La, Nd）-supported multi-walled carbon nanotube composites as hydrogen storage materials

Two composites LaNi4.8Sn0.2/CNTs and NdNi4.8Sn0.2/CNTs were prepared by an impregnation-reduction method. Their hydrogen storage capacity could reach up to 2.96 wt% and 2.88 wt% respectively at room temperature and 1.0 MPa pressure. These values, which might result from the synergetic effect between the alloy nanoparticles and the pretreated CNTs, were three times higher than those of the unsupported MNi4.8Sn0.2 (M=La, Nd) alloys under the same conditions. XRD and TEM revealed that the alloy particles were uniformly dispersed on the CNTs and the average particle size was ca. 30 nm. The composites also showed good stability and the hydrogen storage capacity decreased by less than 6% after 100 adsorption-desorption cycles. Moreover, no noticeable change in crystalline structure was observed for the composites.     

The extremum principle of mass entransy dissipation and its application to decontamination ventilation designs in space station cabins

In terms of the analogy between mass and heat transfer phenomena, a new physical quantity, i.e. mass entransy, is introduced to represent the ability of an object for transferring mass to outside. Meanwhile, the mass entransy dissipation occurs during mass transfer processes as an alternative to measure the mass transfer irreversibility. Then the concepts of mass entransy and its dissipation are used to develop the extremum principle of mass entransy dissipation and the corresponding method for convective mass transfer optimization, based on which an Euler＇s equation has been deduced as the optimization equation for the fluid flow to obtain the best convective mass transfer performance with some specific constraints. As an example, the ventilation process for removing gaseous pollutants in a space station cabin with a uniform air supply system has been optimized to reduce the energy consumption of the ventilation system and decrease the contaminant concentration in the cabin. By solving the optimization equation, an optimal air velocity distribution with the best decontamination performance for a given viscous dissipation is firstly obtained. With the guide of this optimal velocity field, a suitable concentrated air supply system with appropriate air inlet position and width has been designed to replace the uniform air supply system, which leads to the averaged and the maximum contaminant concentrations in the cabin been decreased by 75% and 60%, respectively, and the contaminant concentration near the contaminant source surface been decreased by 50%, while the viscous dissipation been reduced by 30% simultaneously.     

The carbon isotopic compositions of Non-methane Hydrocarbons in atmosphere

Carbon isotopic compositions of atmospheric Non-methane Hydrocarbons(NMHCs) in the urban areas of Taiyuan and Lanzhou in summer were reported and the sources of NMHCs are discussed.Carbon isotopic ratios(δ 13C) of vehicle exhaust,coal-combustion exhaust,fuel volatiles and cooking exhaust were also measured with thermal desorption-gas chromatography-isotope ratio-mass spectrometry(TD-GC-IR-MS).δ 13C values of NMHCs in the urban areas of Lanzhou and Taiyuan range from-32.3‰ to-22.3‰ and from-32.8‰ to-18.1‰.δ ...     

Robust fault detection and diagnosis for uncertain nonlinear systems

This paper considers robust fault detection and diagnosis for input uncertain nonlinear systems. It proposes a multi-objective fault detection criterion so that the fault residual is sensitive to the fault but insensitive to the uncertainty as much as possible. Then the paper solves the proposed criterion by maximizing the smallest singular value of the transformation from faults to fault detection residuals while minimizing the largest singular value of the transformation from input uncertainty to the fault detection residuals. This method is applied to an aircraft which has a fault in the left elevator or rudder. The simulation results show the proposed method can detect the control surface failures rapidly and efficiently.     

含二茂铁基树形两亲性分子的合成及其电化学行为

合成了2, 3, 4-三-（11-二茂铁基）十一烷氧基苯甲酸, 用元素分析、核磁共振谱, 红外及紫外光谱等对产物进行了表征. 利用循环伏安法（CV）, 线性扫描伏安法（LSV）, 常规脉冲伏安法（NPV）, 计时电流法（CA）和计时电量法（CC）研究了该物质的电化学行为, 测定了其电化学参数. 结果表明该二茂铁基两亲性分子在溶液中具有良好的氧化还原可逆性, 是由扩散控制的可逆过程, 且三个二茂铁基团之间没有强相互作用而显示等同的氧化还原性.