基于多参数加权分数阶傅里叶变换的星座预编码系统研究与实现

针对当前多参数加权分数阶傅里叶变换(Multiple Parameters Weighted-type FRactional Fourier Transform, MP-WFRFT)星座特征缺乏定量研究的缺限,该文提出一种新型的星座叠加数学模型。通过分别研究信号的时域及频域分量,给出了星座模糊及裂变的定性及定量分析结论,并搭建了基于MP-WFRFT的星座预编码系统。通过构建相关混合整数优化模型,并利用遗传算法进行模型优化,进而设计出符合预期通信需求的预编码系统。经仿真分析,验证了所提出的星座叠加数学模型及优化方案的正确性;同时通过USRP硬件平台测试表明了所搭建的基于MP-WFRFT星座预编码系统的可行性。     

16 Gbit/s all-optical demultiplexing using four-wave mixing

A novel, purely optical technique for demultiplexing high-speed time-division multiplexed data is proposed and demonstrated. The technique uses optical fibre nonlinearity induced four-wave mixing with a data signal and a probe signal located at different wavelengths. Using only semiconductor laser light sources, 1:4 demultiplexing of 20 ps long, subpicojoule, 2/sup 15/-1 RZ pulses at a data rate of 16 Gbit/s with less than 1 dB penalty is demonstrated.<>     

一种最小电压应力的软开关无桥PFC技术研究

针对传统桥式整流升压功率因数校正(PFC)电路效率较低的缺点,提出了一种最小电压应力的软开关无桥PFC电路拓扑.在理论分析和仿真验证的基础上,研制了一台300 W的实验样机.结果表明,改进的无桥PFC电路拓扑具有通态损耗低、电流采样简单,能实现开关管零电压关断和零电流开通,同时实现整流二极管零电压导通和接近零电流软关断...     

基于DSP的舰载搜索雷达稳定平台交流伺服系统的设计

给出了一种基于DSP的舰载搜索雷达交流伺服控制系统的设计方法。采用高速数字信号处理芯片TMS320LF2407A作控制主体,交流变频器和交流无刷电机作驱动,采用先进的数字PID控制算法,组成全数字交流伺服系统,保证系统具有很高的精度、可靠的稳定性和良好的可扩展性。仿真试验表明该设计满足舰载雷达伺服控制系统的要求。     

The disk loaded monopole antenna

The method of moments (MoM) is used to analyze the disk loaded monopole (DLM) antenna. Results were validated by comparison with mode-matching and wire-model methods as well as with measurements covering a wide range of electrical sizes. A quasistatic treatment is shown to be both rapid and accurate for the electrically small case. Equivalent circuits are obtained for predicting communication system performance. Parameters defining the fundamental limitations of electrically small antennas are extracted and shown to be accurate for system analysis and useful as design tools.     

基于软件无线电的GNSS干扰和多径监测系统设计

针对干扰和多径导致全球导航卫星系统(GNSS)不能精确、安全和可靠地提供位置、速度和时间服务等问题,分析了研制GNSS干扰和多径监测系统的意义,介绍了当前干扰和多径常用的检测方法,设计了一套针对当前四大导航系统(美国GPS、俄罗斯GLONASS、欧盟Galileo和中国BDS)各信号带内以及附近频率的干扰和多径监测系统.系统基于软件无线电(SDR)思想,采用模块化设计,具有良好的功能扩展性和配置灵活性.根据不同干扰的特点,结合实际应用改进了其检测算法:采用能量阈值法检测不同形式的压制式干扰,采用基于捕获多相关峰法判别欺骗式干扰,采取基于最大似然准则的多径估计延迟锁定环(MEDLL)技术估计多径信号的参数.实验结果表明系统能够有效检测各种干扰和多径信号的存在,使用户获取其特征参数,为干扰源的定位、查处、排除、规避以及多径信号的抑制提供决策依据.     

The impact of the Internet in banking: observations and evidence from developed and emerging markets

This paper investigates the risk, efficiency and rate of progress in the implementation of electronic commerce (e-commerce) in a sample of banks from a developed country (the US), and a sample of banks from developing and emerging markets. The results confirm that the US is very advanced in its electronic-banking (e-banking) actuation. There is evidence suggesting that e-banking is driven largely by the prospects of operating costs minimisation and operating revenue maximisation. Costs are lower and revenues higher when banking services are delivered through a branch network. The results also suggest that perceptions of banking risk may be partially driven by similar factors. Using a basic risk-scoring model, bank risk scores (reflecting a bank's ability to repay depositors) are regressed against operating efficiency measures.     

单倍型异基因造血干细胞-脐带间充质干细胞联合移植治疗1例急性白血病

目的研究急性粒细胞白血病异基因造血干细胞-人脐带源间充质干细胞（hUG—MSC）联合移植效果。方法急性髓性白血病-M2,供者为其胞兄,HLA单倍型相合,移植物为经粒细胞集落刺激因子（Granulocyte Clony—Stimulating Factor,G—CSF）动员的骨髓以及外周血造血干细胞,加入分离、扩增的hUC—MSC。移植物抗宿主病（Graft—Versus—Host Disease,GVHD）预防采用环孢菌素A＋ATG^＋霉酚酸酯＋短程甲氨喋呤和CD25单抗。结果输注供者的MSC总数和CD34细胞数分别为7．92&#215;10^8/L和3．78&#215;10^6／L。中性粒细胞大于0．5&#215;10^9／L和血小板大于20&#215;10^9／L的时间分别为14d和15d。24d嵌合体100％,40d左右出现Ⅰ度aGVHD,治疗后好转,未出现其他严重并发症。结论异基因造血干细胞-人脐带源间充质干细胞（hUC—MSC）联合移植安全简便,可加速造血功能恢复。     

Codelivery of NOD2 and TLR9 Ligands via Nanoengineered Protein Antigen Particles for Improving and Tuning Immune Responses

Vaccine adjuvants that can induce robust protective immunity are highly sought after for the development of safer and more effective vaccines. Vaccine formulation parameters that govern efficacy are still far from clear, such as the diverse impacts of codelivering agonist molecules for innate cell receptors (e.g., pattern recognition receptors). In this study, a mesoporous silica‐templating approach is used to fabricate protein antigen (ovalbumin) particles covalently functionalized with agonists for NOD‐like receptor 2 (NOD2) and Toll‐like receptor 9 (TLR9). Particle‐induced combinatorial NOD2/TLR9 signaling results in synergistic inflammatory cytokine secretion by mouse macrophages (RAW 264.7). Administration of NOD2/TLR9 particles in mice results in adaptive immune responses that are both quantitatively and qualitatively different than those resulting from administration of particles conjugated with either NOD2 or TLR9 agonists alone. While delivery of NOD2 agonists alone activates T helper 2 (Th2)‐type responses (and no CD8+ T cell activation) and delivery of TLR9 agonists alone activates CD8+ T cell and T helper 1 (Th1)‐type responses, codelivery of NOD2 and TLR9 agonists enhances Th1‐type responses and abrogates CD8+ T cell activation. The results illustrate that in the particle‐based system, NOD2 activation plays different roles in polarizing adaptive immune responses depending on coactivation of TLR9.     

New synchronisation method for satellite-switched time-division multiple-access systems

A new synchronisation method for satellite-switched time-division multiple-access systems is described. It is shown that this method has some significant system benefits, and involves a small increase in satellite hardware complexity.