基于激光传感器的智能车设计

以飞思卡尔半导体公司的MC9S12XS128单片机为核心,介绍了智能车的设计思想,硬件及软件设计方案。单片机通过激光传感器采集路径信息,处理后产生PWM信号控制电机转动,采用光电编码器做速度检测,从而实现闭环控制。     

PCB拒焊原因分析和改善应用

引言通常情况下电子器件的表面装连工艺（SMT）中最关键的过程就是焊接,而焊接的三个主要作用它们分别是：     

MC34063A在嵌入式宽电压输入中的应用

电源是电子系统中重要的组成部分,电源的稳定性直接影响到整个系统的性能和使用寿命。嵌入式系统中的核心电压多为+5 V,而使用环境往往不能随时提供+5 V电压。为了使嵌入式系统具有更广泛的适应性,在此根据MC34063A芯片的原理,介绍了一种依据此芯片进行的降压型宽电压输入电源电路的设计。通过计算电路外围器件的参数,完成具体电路的设计;最后对系统的几个重要性能指标进行了测试,测试结果验证了该宽电源输入电路具有良好的稳定性和实用性。相对于其他方式的宽电压,该设计具有更广范的适应性以及精确性。     

A solvent extraction technique for the isotopic measurement of dissolved copper in seawater

Stable copper (Cu) isotope geochemistry provides a new perspective for investigating and understanding Cu speciation and biogeochemical Cu cycling in seawater. In this work, sample preparation for isotopic analysis employed solvent-extraction with amino pyrollidine dithiocarbamate/diethyl dithiocarbamate (APDC/DDC), coupled with a nitric acid back-extraction, to concentrate Cu from seawater. This was followed by Cu-purification using anion-exchange. This straightforward technique is high yielding and fractionation free for Cu and allows precise measurement of the seawater Cu isotopic composition using multi-collector inductively coupled plasma mass-spectrometry. A deep-sea profile measured in the oligotrophic north Tasman Sea shows fractionation in the Cu isotopic signature in the photic zone but is relatively homogenised at depth. A minima in the Cu isotopic profile correlates with the chlorophyll a maximum at the site. These results indicate that a range of processes are likely to fractionate stable Cu isotopes in seawater.     

Adaptive Resource Allocation for MC‐CDMA and OFDMA in Reconfigurable Radio Systems

This paper studies the uplink resource allocation for multiple radio access (MRA) in reconfigurable radio systems, where multiple‐input and multiple‐output (MIMO) multicarrier‐code division multiple access (MC‐CDMA) and MIMO orthogonal frequency‐division multiple access (OFDMA) networks coexist. By assuming multi‐radio user equipment with network‐guided operation, the optimal resource allocation for MRA is analyzed as a cross‐layer optimization framework with and without fairness consideration to maximize the uplink sum‐rate capacity. Numerical results reveal that parallel MRA, which uses MC‐CDMA and OFDMA networks concurrently, outperforms the performance of each MC‐CDMA and OFDMA network by exploiting the multiuser selection diversity.     

移动用户行为模型的研究与应用

中国移动用户对通话质量的要求越来越高,通话区域也日益广泛和复杂。识别用户通话中的具体场景,建立有效的用户行为模型,进行针对性的网络优化,是挽留客户的重要手段。本文研究的内容,首先在Nb/Mc接口以镜像的方式采集信令和媒体,分析数据所包含的用户位置信息;然后运用统计的方法建立不同用户场景的行为模型;最后使用该模型对全网的移动用户进行场景分类,进行通话质量的分析。     

基于MC9S12XS128单片机的多功能智能小车系统设计

利用嵌入式技术和图像处理技术,设计制作了基于MC9S12XS128单片机的多功能智能小车。智能小车可以在包含岔口的路面进行自主择路行进。到达终点后,在显示屏上显示路口选择方案、行进距离、行驶时间、行进速度。该系统通过CMOS摄像头OV5116检测路面信息,使用比较器对图像进行硬件二值化,用于路面识别,通过光电编码器检测智能小车的实时速度,使用PID控制算法调节驱动电机的转速和转向舵机的角度,实现了对智能小车运动速度和运动方向的闭环控制。整个系统的电路结构简单,成本低廉,可靠性高。经实际测试,智能小车各项指标均达到预期的设计目标。     

新型"龙珠"处理器MC9328MX1的功能和应用

ARM系列处理器内核是摩托罗拉公司开发的基于ARM920微处理器的新型“龙珠”MX1嵌入式处理器，它的优势不仅在于其使用了ARW芯片，同时还加入了适用于未来3G应用、支持Bluetooth蓝牙天线技术的平台。文中介绍了MC9328 MXl的功能和结构，同时详细探讨了MXl上蓝牙装置的结构和特点。     

Correlative studies in optical reflectance measurements of cerebral blood oxygenation

A numerical study is made of correlation development for measuring cerebral blood oxygen saturation (StO) noninvasively using optical reflectance ratio of dual wavelengths. The Monte Carlo (MC) method was used for simulating reflectance measurements in a model neck tissue, where the cerebral blood oxygenation was monitored through the blood flows in the common carotid artery (CCA) and jugular vein. Reflectance ratios between two wavelengths at 633 and 800 nm were obtained under different blood vessel conditions. The results revealed a quantifiable correlation between the reflectance ratio and the cerebral StO level. Correlations for each of the blood vessel parameters such as the location, size, and hemoglobin concentration of the CCA or jugular vein (JV) were developed.     

时分多址(TDMA)通信系统频率源的研制

频率合成器是现代电子系统的重要组成部分 ,在通信、雷达、电子对抗、导航、广播电视、遥测遥控、仪器仪表等许多领域都得到广泛的应用。在雷达等通信设备中 ,它为发射机的调制器提供载频信号 ,也为接收机或发射机的混频器提供稳定可靠的本振源。该锁相频率合成器体积小、成本低、通用性强、使用灵活方便 ,频率控制可以通过硬件 (面板 )实现 ,也可以通过软件写入 ,工作频带 :3 80～ 4 40 MHz,频率步进 1 .2 5 MHz,输出功率≥7d Bm,相位噪声≥ -95 d Bc/Hz/1 0 k Hz。该频率合成器双路输出 ,收、发双工工作 ,已成功地用于时分多址 (TD-MA)通信网中