离心轧辊毛坯浇铸过程中的温度监测及温度查询方法

离心轧辊毛坯浇铸过程是轧辊生产过程中的一道重要工序,而过程中的铁水实时测温又很重要,只有实时测温并控制好铁水的温度,调整好铁水的成份,才能生产出一支优质的轧辊毛坯。采用VB编程的方法,开发了一套测温软件,并配以适当的测温器件,来对毛坯浇铸的各个阶段的温度进行有效的测量、显示、存储及查询、调用等。用来对浇铸过程中的工艺参数有一个客观、实际的记录,并可作为日后工作中的工艺参考数据。     

Static pull-in analysis of microcantilevers based on the modified couple stress theory

This paper investigates the deflection and static pull-in voltage of microcantilevers based on the modified couple stress theory, a non-classic continuum theory capable to predict the size effects for structures in micron and sub-micron scales. It is shown that the couple stress theory can remove the gap between the experimental observations and the classical theory based simulations for the static pull-in voltage.     

Interdiffusion behaviors and mechanical properties of Zn–Cr system

Diffusion couple technique has been utilized to study the interdiffusional behaviors of Zn–Cr system. Two intermetallic compounds (Zn₁₃Cr, Zn₁₇Cr) have been found in the diffusion zone between 598 K and 653 K. For the existence of Zn₁₃Cr phase, the incremental diffusion couple has been used to confirm, and the results show that the Zn₁₃Cr phase can be determined in the present work. However, the thickness of Zn₁₃Cr is very thinner than that of Zn₁₇Cr, which indicate the growth of Zn₁₃Cr is very slow. The thickness of Zn₁₇Cr satisfied the parabolic growth law. EPMA was used to obtain the composition profiles and the interdiffusion coefficients of Zn₁₃Cr, Zn₁₇Cr and Zn (hcp) have been extracted by forward simulation analysis embedded in ‘Pydiffusion’ code. The mechanical properties of Zn₁₇Cr were also determined by nanoindentation technique, and the hardness and Young's modulus of Zn₁₇Cr is 3.01 GPa and 165.78 GPa, respectively.     

A novel compact planar ultra‐wideband antenna with dual band‐notched characteristics

A novel planar ultrawideband monopole antenna with dual notched bands is presented. The antenna mainly consists of a radiation patch and a modified ground plane. To realize dual band‐notched characteristics, a U‐shaped stub embedded in the rectangular slot of the radiation patch and a novel coupled open‐/shorted‐circuit stub resonator are used on the backside of the substrate. The bandwidth of the dual notched bands can be controllable by adjusting some key parameters. The simulated and measured results indicate that the proposed antenna offers a very wide bandwidth from 2.6 to 18 GHz with Voltage Standing Wave Ratio (VSWR) < 2, except the dual notched bands of 3.3–3.7 GHz (World Interoperability for Microwave Access [WiMAX]) and 5.15–5.825 GHz (Wireless Local Area Network [WLAN]). Furthermore, good group delay and stable gains can be achieved over the operating frequencies. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:48–55, 2015.     

在裂纹尖端引入奇异单元的偶应力有限元法

针对在微观状态下结构力学行为会受尺度效应影响的问题,在偶应力理论中考虑微观结构的旋转梯度可以较好解释结构的尺度效应.建立基于一般偶应力理论的有限元法的基本方程,并在裂纹尖端引入奇异单元,计算受单向拉伸的中心斜裂纹板裂纹尖端场的应力强度因子(Stress Intensity Factor,SIF),分析特征长度变化对SIF的影响,对比偶应力理论下的结果与经典理论下的结果.结果表明：在裂纹尖端引入奇异单元可以提高计算精度和稳定性;偶应力使得裂纹尖端SIF比经典理论下的值小,并且SIF随着特征长度增大而减小.     

一种新型多变量模糊自适应控制系统的研究

针对多变量非线性系统,提出了一种基于动态耦合特性的两级串联结构的模糊自校正控制器,并提出了基于动态灵敏度矩阵和在线测量的自学习算法．同时利用一种智能梯度法确定自校正学习迭代步长．仿真结果表明,算法的收敛性和系统的稳定性均有所改善．利用这些控制策略,可以较好地解决化工反应器等复杂对象的过程控制问题     

飞机余度舵机系统鲁棒故障诊断

提出一种利用特征结构配置与状态反馈解耦相结合设计观测器的方法,实现余度伺服系统的鲁棒故障诊断,利用特征结构方法,可以实现残差与结构性干扰解耦;利用对偶原理,进行解耦观测器设计,可使残差不受交联作用影响,利用这两种方法中参数设计的自由度,使其互相逼近,做到在干扰解耦的基础上,故障最大程度地实现通道解耦,该方法不仅适用于突变故障,而且也适用于渐变故障和多故障的诊断。     

基于CCD技术的自举式光学水平基准测量方法

提出了一种以CCD器件为传感器的光学水平基准的测量方法 ,具体介绍了以单片机 89C5 1为核心处理器的水平基准测量电路的软硬件设计。     

新型方波-直流电压信号的转换方法

围绕CCD(电荷耦合器件 )线阵在控制电路中的应用的难点 (如何将CCD输出的原始信号经过初步处理后所得的方波信号转换成直流电压信号 )进行了讨论和分析。首先介绍了两种传统的转换方法 ,并对这两种方法的优缺点进行了分析和比较。最后提出了一种新颖的转换方法 :基于滤波思想的方波 -直流电压信号的转换方法。经实验验证 ,这种方法所得的直流电压信号确实稳定、可靠     

Diffusion behaviors and atomic mobilities in Mg–Sc hcp and bcc alloys: Investigation via single-phase and multi-phase diffusion couples

Diffusion behaviors in Mg–Sc hcp and bcc solid solutions between 773 and 873 K were investigated using both single-phase and multi-phase diffusion couple techniques. The EPMA detected composition-distance profiles were smoothed and fitted using the error function expansion (ERFEX). The interdiffusion coefficients were extracted using Sauer–Freise integral. The interdiffusion coefficients in hcp phase showed a slightly parabolic composition dependence at the Mg-rich part and the maximum value was around 2–3 at. % Sc. However, the interdiffusion coefficients in the bcc phase monotonously decreased with the increase of solubility of Sc. The determined inter- and impurity diffusion coefficients in the hcp Mg–Sc alloys were assessed to develop the atomic mobility database, and their validity was justified by reproducing the composition profiles and diffusion fluxes obtained in this diffusion couple experiment. Meanwhile, the development of bcc atomic mobility was realized via the Maclaurin approximation, extrapolation, and optimization. The results make up for the missing data of Mg–Sc diffusion kinetics.