DO浓度对SUFR系统同步硝化反硝化的影响

采用螺旋升流式反应器（SUFR）处理生活污水，考察了好氧反应池中DO浓度对其同步硝化反硝化的影响。结果表明，在好氧反应池上部溶解氧浓度为3．0～3．5mg／L时，发生了明显的同步硝化反硝化现象，其对TN的去除量占SUFR系统对TN去除总量的16％左右；好氧反应池中的同步硝化反硝化反应只发生在池的下部，其中、上部只进行了好氧硝化反应；SUFR系统中好氧反应池上部的最佳溶解氧浓度范围为3．0～3．5mg／L，此时系统的硝化和反硝化效果最佳，好氧反应池中的脱氮效果也较好，系统对TN的去除率〉84％。     

Three-phase induction motor operating from single-phase supply with an electronically controlled capacitor

In this paper the performance of a three-phase induction motor operating from single-phase supply with a new electronically controlled capacitor using an electronic switch in series with a fixed capacitor to achieve a minimum unbalance of the motor phase voltages at all loading conditions is proposed. No mechanical or centrifugal switch is used here. Basic system operation, theoretical analysis, simulated and experimental results in comparison with conventional operation using one and two fixed capacitors are presented in this paper. The optimum effective capacitor value can be on-line adjusted at any operating speed by periodically changing the duty cycle of the controlled switch to achieve minimum unbalance in phase voltages to improve the motor performance at different speeds.     

Characterization of the ceramic–metal brazed interface using ultrasonic technique

Sintered Al₂O₃ is brazed with 304 stainless steel (SS) using 97(Ag28Cu)3Ti active filler alloy at 1000 °C. Electron Probe Micro Analysis (EPMA) studies of the interfaces are carried out. The thickness of the interfaces are measured from the concentration penetration profile. Shear strength of the joint is evaluated. The qualities of the joints are characterized using ultrasonic technique. Mechanical properties of the joints are correlated with the obtained ultrasonic signals during the ultrasonic scanning of the sample.     

Elastic solutions of a cylindrical rod containing periodically distributed inclusions with axisymmetric eigenstrains

Summary. In this paper, we give the elastic solution for a special type of microstructure – a circular cylindrical rod containing periodically distributed inclusions along its axial direction. Each inclusion has the same uniform axisymmetric transformation strain (eigenstrain). Analytical elastic solutions are obtained for the displacements, stresses and elastic strain energy of the rod. The effects of microstructure and its evolution (growth of inclusions) on the elastic stress and strain fields as well as the strain energy of the rod are quantitatively demonstrated. As a result of such microstructure evolution nominal stress-strain relation with strain softening is derived for a rod under uniaxial tension.     

Electronic properties of dehydrogenated nanodiamonds: A first-principles study

First-principles calculations using quantum-mechanical density functional theory (DFT) are carried out to study the geometric structure and electronic properties of dehydrogenated nanodiamonds with diameters varying from 0.8 nm to 1.6 nm. The results show that the electronic properties of dehydrogenated nanodiamond are quite different from those of bulk diamond or hydrogenated nanodiamond. Surface atoms play an important role in the electronic structure, especially the states near the Fermi level, for dehydrogenated nanodiamond. In addition, it has been revealed that the size-dependent feature in the electronic properties for dehydrogenated diamonds is also contributed by the surface effect, in addition to the quantum confinement effect.     

A new finite element formulation based on the velocity of flow for water hammer problems

The primary objective of this paper is to develop a simulation model for the fluid–structure interactions (FSI) that occur in pipeline systems mainly due to transient events such as rapid valve closing. The mathematical formulation is based on waterhammer equations, traditionally used in the literature, coupled with a standard beam formulation for the structure. A new finite element formulation, based on flow velocity, has been developed to deal with the valve closure transient excitation problems. It is shown that depending on the relative time-scales associated with the structure, fluid and excitation forces, there are situations where the structural vibration response increases with FSIs. This is in contrast to what is normally accepted in the literature, i.e. FSI reduces the structural displacements.     

基于算术傅里叶变换的离散Hartley变换的快速算法

离散Hartley变换是一种有用的实值正交变换。文中对其快速算法进行研究,首先介绍利用算术傅里叶变换（AFT）计算离散傅里叶变换（DFT）可使其乘法计算量仅为O（N）,然后文章根据这一特点,分析离散Hartley变换（DHT）的结构特征,通过DFT将AFT和DHT建立了直接联系,提出了一种新的快速DHT算法。算法的计算复杂度能够达到线性O（N）,且算法结构简单,公式统一且易于实现,并与其他快速算法进行了比较,分析可知在数据长度不是2的幂次方时,文中提出的算法的计算时间明显比其他算法的计算时间要小。实验结果也验证了文中算法的有效性,从而为DHT的快速计算开辟了新的思路和途径。     

连锁快餐企业的顾客满意度评价模型

从品牌、产品、服务和环境等方面建立基于证据推理的连锁快餐企业顾客满意度评价模型。为反映不同店面顾客满意度的差异,依据营业额设定店面权重,将各店面的评价结果作为证据集结出总体满意度。抽样调查安徽省某知名连锁快餐企业的七家分店,获取其一周的问卷数据。通过仿真试验,验证了模型的有效性和实用性,对比两种模型的试验结果,并对企业经营提出了一些建议。