双星时差频差无源定位系统定位算法工程指标分析

通过计算时差、频差测量精度,以及卫星运动引起的时差、频差变化率,提出双星时差频 差无源定位系统的信号最佳采样时间为10～100 ms。进一步推导了工程可实现的定位精 度,仿真结果表明双星系统工程可实现的定位精度约为1～3 km。研究和结论对双 星定位系统定位精度指标的论证与分解具有借鉴意义。     

利用随机共振解调微弱MFSK信号

采用随机共振解调微弱MFSK信号解决了传统解调方法误码率高的问题。 根据大噪声环境下信号能借助噪声能量发生随机共振这一理论,先将微弱MFSK信号通过双稳 态随机共振系统以提高其信噪比,对随机共振系统的输出信号用FFT来区分每段信号的载波 频率,最后依据判决准则解调MFSK信号。当信噪比较高时,可向信号中人为添加白噪 声来使之适用于该解调方法。MATLAB仿真结果表明,该方法能成功解调信噪比最低为 -23 dB的2FSK信号和-25 dB的8FSK信号,而这是传统相干解调方法所无法达到的。     

采用闭环双口RAM实现深空动态模拟源的设计

深空探测具有时延长、运动速度大以及信号强度低的技术难点。在对上述技术难点进 行分析的基础上,提出了对深空动态模拟的解决办法：通过利用闭环双口RAM来解决模拟时 延较长的问题;改变读出双口RAM数据的速率来模拟卫星的运动速度;控制数控衰减器来模 拟深空的信号强度。实际的工程应用证明上述实现方法有效可行。     

基于AD5545的可编程宽带直流信号放大器

设计了一种增益可手动数字设置或程控设置且无调节电位器的宽带直流放大器。该放大器主要以单片机MSP430和继电器组作为电路的主要控制部分,由使用D/A转换器AD5545控制的放大电路、前级信号调理电路、后级功率放大电路和滤波器组成,实现了增益连续可调的功能。该放大器在0～60dB范围内连续可调,输出信号无明显失真,在0～5MHz范围内信号可放大60dB,最大输出电压为8V。     

国内和欧美手机银行业务发展的实践与创新

结合手机银行发展的新趋势,本文选取了美国银行等3家欧美银行和工商银行等4家国内银行为研究样本,围绕服务模式、产品功能、安全性和业务发展等纬度进行对比分析.跟欧美同业相比,国内手机银行针对智能手机的特色服务体系尚待进一步完善,但产品功能更丰富,安全防范层级更高,即将进入快速成长期.因此,国内手机银行应充分把握发展机遇,大...     

The effect of shopping goals and in-store mobile device use on purchase outcomes in brick-and-mortar stores

The present study examines the effect of using a mobile device on search and evaluation by a shopper in a brick-and-mortar store. A conceptual model that proposes inter-relationships between shopping goals, the amount and type of in-store mobile device use, and purchase outcomes is developed. Data from a national quota sample of 1034 mobile shoppers is used to test hypotheses derived from the proposed model. The findings provide several new insights into the impact of in-store mobile device use on the consumer decision journey in a brick-and-mortar store. Depending upon the shopping goals of the consumer, the use of a mobile device by shoppers in a brick-and-mortar store can either decrease or increase search, lead to more deferred purchases or in-store-now purchases, and more online or physical store purchases. The study is among the first to model the pathway to purchase for mobile device assisted shoppers in brick-and-mortar stores.     

基于MATLAB的数字信号处理实践教学研究

数字信号处理是一门理论性较强的专业课程,公式推导多,学生对某些理论知识点理解困难。本文将MATLAB引入实践教学当中,对课堂教学、实验教学、课程设计等方面的实施实例进行阐述。本文提出的实践教学研究思路能对提高教学效果、提升学生的动手能力起到很好的促进作用。     

移动通信网络优化现状及发展趋势

移动通信网络始终处于动态变化中,并且其用户群体庞大、移动性高、话务密度甚是不均匀,由此造成用户手机与基站的信号连接不顺畅,致使通信质量下降的现象。而移动网络优化技术可以有效的改善此局面,提高通信质量。文章介绍了移动通信网络优化的基本概念、存在现状,并对其发展趋势及方向做了总结预测。     

Profiling mobile TV adopters in college student populations of Korea

By profiling demographic characteristics, perceived general adoption attributes, perceived value-based adoption attributes, motivational needs, mass media use, and content interest, this exploratory study examines the nature of four categories of mobile TV adopters — current, potential, continuous non-, and discontinuous user groups. Despite the limited sample size (N = 214), there are some meaningful findings. First of all, the non-adoption rate of mobile TV of the continuous non-, and discontinuous user groups is higher than the adoption rate of the current and potential user groups. Less than half of the respondents (N = 34) who had used TV on a mobile device were unwilling to use it again in the next twelve months, and almost half of those (N = 102) did not have the intention of using it within the coming year. The results suggest that the discontinuous group seems to have been dissatisfied with the actual mobile TV use when compared with their expectations and evaluations, while the potential user group is more likely to have high expectations and positive evaluations before the adoption and use of mobile TV. All user groups were unwilling to pay the fee, despite the current and potential user groups perceiving the exceptional values. No differences were found in the personality trait of innovativeness and mass media use behaviors among the four groups.     

立井钢丝绳卡绳器移动装置的设计与应用

针对煤矿立井安装、拆除钢丝绳卡绳器时费时费力、易发生挤手碰脚现象和滑落井筒的危险,设计了卡绳器移动装置。不仅省时省力,工作效率提高2倍,安全性能大大提高。