WSNs布局的粒子进化的多粒子群优化策略

在粒子进化的多粒子群算法基础上,提出了一种无线传感网络节点布局的优化策略.该策略通过多个粒子群彼此独立地搜索解空间,提高了算法的寻优能力,有效地避免了"早熟"问题,提高了算法的稳定性.仿真实验表明,与传统的粒子群算法相比,该算法有效覆盖率由75.36%提高到80.96%,收敛速度提高了19.4%.因此粒子进化的多粒子群优化策略具有比传统的粒子群算法更好的优化效果.     

Improving PAPR performance of filtered OFDM for 5G communications using PTS

The filtered orthogonal frequency division multiplexing (F-OFDM) system has been recommended as a waveform candidate for fifth-generation (5G) communications. The suppression of out-of-band emission (OOBE) and asynchronous transmission are the distinctive features of the filtering-based waveform frameworks. Meanwhile, the high peak-to-average power ratio (PAPR) is still a challenge for the new waveform candidates. Partial transmit sequence (PTS) is an effective technique for mitigating the trend of high PAPR in multicarrier systems. In this study, the PTS technique is employed to reduce the high PAPR value of an F-OFDM system. Then, this system is compared with the OFDM system. In addition, the other related parameters such as frequency localization, bit error rate (BER), and computational complexity are evaluated and analyzed for both systems with and without PTS. The simulation results indicate that the F-OFDM based on PTS achieves higher levels of PAPR, BER, and OOBE performances compared with OFDM. Moreover, the BER performance of F-OFDM is uninfluenced by the use of the PTS technique.     

高速数据通信及其差错控制研究

提出一种基于嵌入式时钟的高速数据通信方案及其差错控制编译码算法,并分析了性能。采用信道编码调制技术将时钟信息嵌入到高速串行数据流中,实现自同步传输,突破了外同步方式下传输距离和传输速率的上限,使远程传输带宽达3Gbps以上。针对高速调制信道的特点,在经典汉明码基础上引入交织技术,把可能存在的连续误码转为单个随机错误,简化了差错控制算法的复杂度,提高了编码效率和纠错性能。其编译码电路延时小、易实现、码率易控,方便高速数据通信系统应用,且能显著改善低信噪比条件下传输的可靠性。     

A Facile Microwave Avenue to Electrochemiluminescent Two‐Color Graphene Quantum Dots

With the assistance of microwave irradiation, greenish‐yellow luminescent graphene quantum dots (gGQDs) with a quantum yield (QY) up to 11.7% are successfully prepared via cleaving graphene oxide (GO) under acid conditions. The cleaving and reduction processes are accomplished simultaneously using microwave treatment without additional reducing agent. When the gGQDs are further reduced with NaBH₄, bright blue luminescent graphene quantum dots (bGQDs) are obtained with a QY as high as 22.9%. Both GQDs show well‐known excitation‐dependent PL behavior, which could be ascribed to the transition from the lowest unoccupied molecular orbital (LUMO) to the highest occupied molecular orbital (HOMO) with a carbene‐like triplet ground state. Electrochemiluminescence (ECL) is observed from the graphene quantum dots for the first time, suggesting promising applications in ECL biosensing and imaging. The ECL mechanism is investigated in detail. Furthermore, a novel sensor for Cd²⁺ is proposed based on Cd²⁺ induced ECL quenching with cysteine (Cys) as the masking agent.     

Image Independent Driving Power Reduction for High Frame Rate LCD Televisions

In this letter, the constant driving power reduction ratio has been achieved for column drivers regardless of the input image by incorporating a new static power reduction scheme into the previous dynamic power reduction method. The measured power reduction ratio is around 50% for a 120 Hz liquid crystal display panel in such cases of still input video and fallback.     

基于小波变换的MSK信号码速率盲估计

针对最小频移键控调制信号的码速率估计问题,提出一种基于Haar小波变换的MSK信号码速率盲估计方法。首先对接收信号作傅里叶变换得到信号频谱,对频谱频点分析粗估计信号的码速率,接着通过粗估计的码速率选取短时傅里叶变换窗函数长度和3个小波尺度,利用短时傅里叶变换得到信号瞬时频率变化,再利用小波的边缘检测特性对信号瞬时频率序列相位跳变点检测,最后对检测结果作频谱分析,估计频率得到MSK信号的码速率。仿真结果表明,高于信噪比门限时本算法可以对MSK信号码速率有效估计。     

基于北斗可穿戴式老人心率检测仪

为了实时检测老人在户外的心率健康状况,设计了一种基于北斗的心率检测仪.当老人心率异常时,可以通过穿戴式检测设备及时通知老人的监护人和医护人员,并告知确切的位置,以获得最快的医治.系统由心率信号采集与处理、GSM模块通信、北斗定位、STM32F405组成,实现对心率信号实时采集与处理,远程监护老人心率健康与定位,对北斗民用化在便携式医疗中的应用有一定的参考意义.     

基于PSO-LSSVM的过电压识别

为了获得理想的过电压识别结果,提出了粒子群优化算法优化最小二乘支持向量机参数的过电压识别方法。首先采用小波变换对过电压原始信号进行分解,提取过电压信号的特征量,然后将过电压信号的特征量作为最小二乘支持向量机的输入,建立过电压识别分类器,并采用粒子群优化算法估计最小二乘支持向量机的参数,最后采用实测的过电压数据进行仿真实验,测试其可行性。结果表明,本文方法可以对各种类型的过电压信号进行准确分类和识别,识别结果稳定,且过电压识别率要高于其它方法。     

数字电视技术的内涵及发展趋势

以有线电视为重点介绍了电视信号的数字化概念、优点及数字电视发展的趋势     

多维Turbo码研究

介绍了多维Turbo的编码原理,并提出了一种基于MAP算法的多维Turbo码译码器结构。研究了多维Turbo码的性能及优点,并通过仿真与二维的Turbo码进行了比较。分析表明,多维Turbo码可以获得更好的性能。