DSP的数学原理及在实时系统的应用

制造系统里所用的微处理器中，单片机只能做逻辑处理和简单数学计算，而数字信号处理器（DSP）可进行相当复杂的数学处理。本文概述DSP的数学原理及其技术特点，介绍了基于DSP智能控制器在制造业中实时测控系统的应用实例。     

模拟月壤研制的初步设想

模拟月壤是月球样品的地球化学复制品，作者总结世界上已有的5种模拟月壤JSC-1，MLS．1，MLS-2，MKS-1和FJS-1的研制过程、方法与基本理化性质，认为系列化模拟月壤研制对中国首次月球探测有重要意义，在此基础上，作者提出系列化模拟月壤研制的基本思路．     

线阵CCD平场校正及FPGA实现的研究

为了消除由于照明光源的非均匀性、镜头渐晕及CCD传感器噪声对图像质量造成的不良影响,首先从理论上分析了线阵CCD固定模式噪声和像素光电响应非均匀性的数学模型和产生的原因;对像素光电响应非均匀性这一主要影响因素,根据其光电响应模型提出了CCD像素光电响应非均匀性的两点校正方法,即求解出各个像素光电响应不均匀性的校正因子和暗偏置量系数,进而用以计算各个像素的校正量,实现逐点校正;针对校正算法大数据量、实时计算的要求,设计了基于现场可编程逻辑门阵列FPGA快速实现校正算法的硬件处理结构。最后,通过仿真和实验表明,两点校正方法可以有效地减小CCD像素光电响应不均匀性的图像噪声,提高图像质量,以便做后续精确处理。     

Multi-mode optimal fuzzy active vibration control of composite beams laminated with photostrictive actuators

Firstly, a multi-field coupling finite element formulation of composited beam laminated with the photostrictive actuators is developed in this paper. Moreover, an optimal fuzzy active control algorithm is also proposed on the basis of the combination of optimal control and fuzzy one.This method opens a new avenue to resolve the contradiction between the linear system control method and nonlinear actuating characteristics of photostrictive actuators. The desired control for suppressing multi-modal vibration of photoelectric laminated beam is firstly obtained through optimal control and then the fuzzy control is used to approach the desired mechanical strain induced by photostrictive actuators. Thus, the multi-mode vibration control of beam is realized.In the design process of optimal fuzzy controller, the design of fuzzy control is independent of optimal control. The simulation results demonstrate that the proposed control method can effectively realize multi-modal vibration control of photoelectric laminated beams, and the control effect of optimal fuzzy control is better than that of optimal state feedback control.     

Crystal orientation and morphology of a lamellae in wrought titanium alloys: On the role of microstructure evolution in b processing

To obtain high-quality aviation forgings of titanium alloys, b forging is an essential processing step which must be considered throughout a production process. In this work, the effect of b forging on the crystal orientation and morphology of lamellar a was experimentally investigated in a two-phase titanium alloy. Strong dynamic recovery during b working resulted in the formation of low-angle grain boundary(LAGBb) inside b grains. The lamellar a can penetrate through the LAGBb, leading to similar intra a LAGBs on subgrain boundaries. Deformation banding occurs at high strain rates, and both diffusive and sharp boundaries of deformation bands can be observed.A continuous change of the b orientation in diffusive boundaries results in the formation of fine and disordered a lamellae without intra-lamellar boundary to hold the Burgers orientation relationship(OR). On sharp boundaries, it is prone to producing continuous grain boundary a(aGB) with a highly similar orientation along the boundaries. Meanwhile, there may exist several lower-angle boundaries within the grain boundary a for a smoother orientation change on the b grain boundary.     

A comprehensive study of the 2016 Mw 6.0 Italy earthquake based on high-rate (10 Hz) GPS data

The 2016 M_w 6.0 Italy earthquake is successfully recorded by the near-field 10?Hz GPS and 200?Hz Strong Motion (SM) stations, providing valuable data for this study. A comprehensive study of this earthquake is carried out based on GPS data, which contains coseismic deformations analysis, noise analysis, seismic wave picking, and magnitude determination. The noise of most GPS-derived displacement waveforms can be described as a combination of white noise, flicker noise, and random walk noise after the earthquake occurrence, and the spectral indices vary significantly for most stations, implying that the seismic signals have affected the noise characteristic of GPS-derived displacement waveforms. S-transform is employed to assess the GPS capability to detect the seismic arrival time. The SM station AMT and the GPS station AMAT are in good agreement in seismic wave picking, and the difference is only 1.2?s in the north component, suggesting that the outcome of seismic wave picking using GPS data is reliable. Then, a classic empirical formula is employed to determine the moment magnitude. A robust moment magnitude (Mw 5.90) can be estimated by the nine GPS stations with about 23.9?s. If four GPS stations near the epicenter is chosen to determine the magnitude, it only take 13.0?s to retrieve a reliable preliminary (Mw 5.82) magnitude, which is 5.4?s ahead of nine stations. In addition, Cross Wavelet Transform (XWT) is adopted to measuring the correlation and phase relationship between GPS and SM records. The result of XWT analysis indicates 10?Hz GPS is capable of capturing reliable and accurate coseismic dynamic deformations, as evidenced by the XWT-based semblance being close to 1 between GPS and SM records. The above results confirm the capability of 10?Hz GPS to capture coseismic dynamic deformations, detect seismic arrival time, and determine earthquake magnitude. Moreover, rapid magnitude determination based on 10?Hz GPS data can be regarded as an important supplement to Earthquake Early Warning (EEW).     

高超声速圆锥边界层失稳条纹结构实验研究

边界层转捩的准确预测是高超声速飞行面临的关键气动问题之一。为研究高超声速边界层失稳和转捩机理,以前缘半径1.6mm、半锥角7°的圆锥模型为研究对象,在FD-07高超声速风洞中采用红外热图技术开展边界层转捩实验测量。通过与工程计算结果对比,确认模型表面边界层流态。实验结果表明:有迎角条件下,模型表面中后段出现条纹结构,条纹结构的起始位置随着周向角的增加而向上游移动;随着迎角的增加,条纹起始位置向上游移动,条纹强度差异和条纹与模型中心线的夹角越来越大。实验获得的条纹结构与不同频率扰动波相互作用直接数值模拟获得的条纹结构现象一致。通过对比分析,认为边界层内不同频率扰动波相互作用是产生条纹结构的一种机制。     

PBT弹性体力学性能及低温脆性研究

采用一步法制备了热固性3,3-双(叠氮甲基)环氧丁烷-四氢呋喃共聚醚(PBT)弹性体,并对其氢键结构、应力-应变关系和动态力学性能及低温脆性进行了研究。结果表明,合成的PBT弹性体拉伸强度和断裂伸长率在DEG羟基含量为35%、R=0.97时,可达2.51 MPa和1 274%,玻璃化温度为-34.5℃。高DEG含量的PBT弹性体脆化参数较低,与常温力学性能变化规律相反。因此,引入低温脆化参数,对PBT弹性体的性能优化具有积极意义。