TDMA网络的FH-OFDM同步算法研究

首先对比了FH-OFDM（跳频OFDM）两种组成形式的优缺点,据此选择了其中一种形式构建了TDMA网络的FH-OFDM的系统模型;然后分别讨论了该系统中跳频同步、时分多址（TDMA）网同步和正交频分复用（OFDM）同步的算法以及三者之间的关系;并对OFDM同步算法进行了深入讨论,构造了基于数据辅助估计的FH-OFDM跳帧结构;利用短训练符号进行了OFDM同步的Matlab仿真,分析了影响频偏估计的因素,并提出了一种工程上选择训练符号的参考方法。     

Cyberbullying,cyber aggression and their impact on the victim – The teacher

This paper focuses on the results of the national research of cyberbullying of Czech teachers, which was realized in year 2016 in the entire Czech Republic. The research focused on impact of cyberbullying on teachers – especially in emotional, physiological and behavioural area. The research involved a total of 5136 primary and secondary school teachers from all regions of the Czech Republic. The research has shown that a fifth of respondents (21.73%) has experienced a cyber-attack on their person, however cyberbullying during the last 12 months lasting over 1 week was confirmed only by 3.52% of the total number of respondents.     

无人机在抢险救灾中的优化应用

针对在抢险救灾中的多无人机路径规划问题,文中采用遗传算法通过对无人机群的巡航矩阵进行编码组成染色体,设置不同个体数目和最大遗传代数优化巡航轨迹,同时采用0-1规划和非线性规划建立无人机终端流量传输矩阵,为每一个用户分配恰当的功率,使得无人机完成所有任务的时间总和最短。遗传算法分析结果:当从H 和J两处各派出3架无人机时至少需要11.37 h才能完成对7个重点区域的生命迹象搜索,此时巡航总距离为3 808 km,从H处派出3架无人机携带通信装备,并向灾区内的72个地面终端发送不同内容,至少需要25.81 h才能完成所有任务,此时巡航总距离为1 547 km。     

一种基于ARM的救援探测机器人的设计

本文主要介绍了一种基于ARM内核的S3C44B0救援探测机器人的设计,该机器人由将实时性较高的操作系统Linux移植到S3C44B0的控制系统、多传感器系统、运行与避障电路系统、图像采集处理系统、无线数据收发系统组成.在Linux开发环境下编写应用程序,实现能远程控制救援探测机器人行走与自动避障、温度和湿度以及O2、H2S、C2H4O等几十种可燃和有毒气体含量的检测、现场图像的采集、无线传输与控制的功能,其特点是能够远程无线控制机器人和远程采集信息.     

IEEE 802.11i标准与WLAN安全性分析

详细分析了WLAN(无线局域网)的最新安全标准IEEE 802.11i,包括标准体系结构、接入认证和访问控制以及加密机制;同时,分析了该标准的网络认证与授权、密钥生成与管理和数据加密机制;最后指出了WLAN安全领域需要进一步研究的课题及802.11i目前仍存在的问题.     

TL16C750在异步串行通信中的应用

文中通过扩展异步通信芯片 TL16C750 实现 DSP 和 PC 机之间的异步串行通信,从而增强系统的通信接口控制能力。介绍了 TL16C750 的性能及与通信有关的寄存器,给出了 TL16C750 在 TMS320VC33 与 PC 机串行通信系统中的硬件应用电路及 TMS320VC33 初始化 TL16C750 的软件编程。     

基于MODBUS协议智能控制系统设计

针对工业化生产的实际需求,改变工控仪表和控制器价格较高的现状同时降低成本,设计了基于MODBUS协议的智能控制系统。下位机由AVR单片机实现基于MODBUS协议的数据采集和显示,再通过控制电路控制数据变量;上位机用VC＋＋6.0编写基于MODBUS协议的程序,实现数据在上位机界面显示,并且将采集的数据值保存到SQLsever2000数据库,同时绘制数据的动态曲线图,上下位机通过RS-485总线通讯。系统结构简单,成本低廉,具有一定实用价值。     

光伏InSb探测器R_0A值的测试与分析

对所生产的光伏 In Sb器件 R0 A值进行了测试 ,结面积为2 .9mm的单元器件 R0 A值在 5.71× 1 0 4～ 5.75× 1 0 6Ω cm2之间 ,50× 1 0 0 μm2的线列器件典型 R0 A值为 3× 1 0 4 Ωcm2 ,对测试结果进行了分析。讨论了器件表面漏电对 R0 A值的影响。     

Redundancy Removal during High-Level Synthesis Using Scheduling Don‘t-Cares

Previous work in automata theory has shown how to eliminate sequential redundancy from networks of FSMs by finding sequences of inputs and outputs which are never communicated between components of the network. This paper shows that behavior automata—finite-state machines whose inputs and outputs are incompletely scheduled—exhibit similar properties. Using the behavior FSM (BFSM) as a model for scheduling, we show how to identify and eliminate both input and output scheduling dont-cares. When a scheduling dont-care is eliminated from a network of BFSMs, the register-transfer implementation is guaranteed not to suffer from the corresponding dont-care sequence. A definition of scheduling dont-cares improves our understanding of the foundations of high-level synthesis and the relationship between high-level and sequential optimization. In practice, scheduling dont-care elimination is a powerful tool for eliminating redundancy early in the design process.     

Cryptanalysis of an E0-like Combiner with Memory

In this paper, we study an E0-like combiner with memory as the keystream generator. First, we formulate a systematic and simple method to compute correlations of the FSM output sequences (up to certain bits). An upper bound of the correlations is given, which is useful to the designer. Second, we show how to build either a uni-bias-based or multi-bias-based distinguisher to distinguish the keystream produced by the combiner from a truly random sequence, once correlations are found. The data complexity of both distinguishers is carefully analyzed for performance comparison. We show that the multi-bias-based distinguisher outperforms the uni-bias-based distinguisher only when the patterns of the largest biases are linearly dependent. The keystream distinguisher is then upgraded for use in the key-recovery attack. The latter actually reduces to the well-known Maximum Likelihood Decoding (MLD) problem given the keystream long enough. We devise an algorithm based on Fast Walsh Transform (FWT) to solve the MLD problem for any linear code with dimension L and length n within time O(n+L⋅2 ^L ). Meanwhile, we summarize a design criterion for our E0-like combiner with memory to resist the proposed attacks.