Blind Adaptive Multiuser Detection for the MC‐CDMA Systems Using Orthogonalized Subspace Tracking

In this paper, we study the performance of subspace‐based multiuser detection techniques for multicarrier code‐division multiple access (MC‐CDMA) systems. We propose an improvement in the PASTd algorithm by cascading it with the classical Gram‐Schmidt procedure to orthonormalize the eigenvectors after their sequential extraction. The tracking of signal subspace using this algorithm, which we call OPASTd, has a faster convergence as the eigenvectors are orthonormalized at each discrete time sample. This improved PASTd algorithm is then used to implement the subspace blind adaptive multiuser detection for MC‐CDMA. We also show that, for multiuser detection, the complexity of the proposed scheme is lower than that of many other orthogonalization schemes found in the literature. Extensive simulation results are presented and discussed to demonstrate the performance of the proposed scheme.     

基于S12X单片机智能小车控制系统设计

本文介绍基于16位微控制器MC9S12XSl28的智能小车控制系统设计,通过随动舵机激光传感器阵列实时检测道路信息,驱动轮光电编码器检测小车运动速度,应用软件开发平台Codewarrior 实现路径循迹控制算法,达到对智能小车方向和运动速度的协调与准确控制。     

基于MC37i模块的GSM移动通信终端的硬件设计

随着通讯技术的发展,基于GSM的移动通信终端已得到越来越广泛的应用。本文提出了基于MC37i模块的GSM移动终端设计方案,采用微控制器ATmega8L控制移动通信芯片MC37i,实现短信息的发送、接收。本设计完成了移动通信模块的启动电路、关闭电路、SIM卡电路、稳压电源电路以及控制电路的设计工作。     

Performance analysis of Doppler shift effects on OFDM‐based and MC‐CDMA‐based cognitive radios

The present development of high data rate wireless applications has led to extra bandwidth demands. However, finding a new spectrum bandwidth to accommodate these applications and services is a challenging task because of the scarcity of spectrum resources. In fact, the spectrum is utilized inefficiently for conventional spectrum allocation, so Federal Communications Commission has proposed dynamic spectrum access mechanism in cognitive radio, where unlicensed users can opportunistically borrow unused licensed spectrum, which is a challenge to obtain contiguous frequency spectrum block. This also has a significant impact on multicarrier transmission systems such as orthogonal frequency division multiplexing (OFDM) and multicarrier code division multiple access (MC‐CDMA). As a solution, this paper develops non‐contiguous OFDM (NC‐OFDM) and non‐contiguous MC‐CDMA (NC‐MC‐CDMA) cognitive system. The implementation of NC‐OFDM and NC‐MC‐CDMA systems provides high data rate via a large number of non‐contiguous subcarriers without interfering with the existing transmissions. The system performance evaluates NC‐OFDM and NC‐MC‐CDMA for mobile scenario where each propagation path will experience Doppler frequency shift because of the relative motion between the transmitter and receiver. The simulation results of this paper proved that NC‐OFDM system is a superior candidate than NC‐MC‐CDMA system considering the mobility for cognitive users. Copyright © 2013 John Wiley & Sons, Ltd.     

基于MC13193的ZigBee无线传感网络设计

集成了传感技术、计算机技术、通信技术的无线传感网络成为无线通信领域研究的热点,低速率、低功耗的Zig-Bee技术的出现为其发展提供了契机。介绍了ZigBee网络的结构,分析了2.4 GHz的射频收发芯片MC13193的特点和性能,并应用MC13193及相关微控制器、传感器件设计了ZigBee无线传感网络。     

In vitro Biological Effects of Ti2448 Alloy Modified by Micro-arc Oxidation and Alkali Heatment

The purpose of this study was to test the hypothesis that the combination of micro-arc oxidation and alkali heatment (MAH) would improve the cytocompatibility of a newly designed Ti-24Nb-4Zr-8Sn alloy.In this study,commercially pure titanium (cp Ti) and Ti-24Nb-4Zr-8Sn were used.Surface modification of Ti-24Nb4Zr-8Sn by a two-step treatment of micro-arc oxidation (MAO) and alkali heatment was reported.Surface characterizations were performed by scanning electron microscopy (SEM),thin film X-ray diffraction (TF-XRD) and X-ray photoelectron spectroscopy (XPS).The MAH layer consisted of finer crystals and possessed a higher degree of crystallity and stability than the MAO layer.A biocompatibility study on treated and untreated Ti24Nb-4Zr-8Sn in comparison with cp Ti was carried out to investigate the effect of the different surfaces on the bone integration property in vitro.The cellular assays revealed that the MAO and MAH layer favored the initial adhesion of MC3T3-E1 cells and that the growth rate of MC3T3-E1 cells on MAH layer was significantly higher than that on the conventional MAO-treated layer after 3-day and 5-day incubation,demonstrating the greater potential of the hybrid treatment of micro-arc oxidation followed with alkali heatment as a novel surface modification method for implanting materials.     

Kinetics of swelling/shrinking rearrangement of a self-aggregated nanohydrogel at solid/liquid interfaces

The hydrogel nanoparticles (nanohydrogels) have great potentials in numerous biomedical applications. Biomembrane-mimetic self-assemble nanohydrogel MC _n (n repeated 2-methacryloyloyloxyethyl phosphoryl choline grafted cholesteryl group-bearing pullulan) was designed. In order to mimic the interfacial responses of fibrinogen at the hydrophobic/hydrophilic surfaces, MC _n molecules were controlled by the chain length of the decorated MPC in term(s) of n?=?0, 6.2, 14.3 and 180, respectively. The dynamic rearrangements of MC _n hydrogel molecular layer on the hydrophobic highly ordered pyrolytic graphite surface were observed by the atomic force microscopy. The results showed that there were biphasic transitions at the liquid/solid interfaces from the initial solute state to metastable state to the equilibrium state. The length of MPC branches, n, governed the changes of layer thickness to the equilibrium state appearing as swelling or shrinking. The time evolution of the thickness was fitted by a single exponential model, and the kinetics parameters of surface rearrangements to the equilibrium state were obtained.     

SR电机在转子位置检测中的应用

连续变速驱动的最新设计能够提高产品性能和系统效率.可以从数字控制中受益的一类电机是开关磁阻电机.相比其他类型的调速驱动,SR电机以其简单的机械构造,高效率和高功率密度,体现出成本和可靠性优势.本文通过对SR电机的原理分析,利用MC56F8006数字信号控制器和专利算法,实现转子位置的检测.     

基于MC1322x的ZigBee应用技术

引入片上集成了ZigBee无线收发器和微控制器的MC1322x,描述了基于MC1322x的ZigBee无线系统的构建技术和应用方法,给出了一种外围元件极少的无线控制器节点的精简硬件设计电路。基于MC1322x的ZigBee无线连接构造方案可以进一步满足应用中的低功耗、低成本、小尺寸、高性能等要求。     

基于MC13213的Zigbee技术无线抄表系统设计

采用Freescale公司的MC13213芯片,将ZigBee技术应用于无线抄表系统.介绍无线抄表系统结构,ZigBee网络节点的硬件设计和软件流程.ZigBee网络节点实现了无线抄表系统的低功耗、低成本, 并具有高度的灵活性和可扩展性.