AVSDRM标准在IPTV中的应用研究

数字版权管理（DRM）技术是IPTV系统中的一项关键技术,它能有效地保护IPTV系统的安全和媒体内容版权的安全。AVS数字媒体版权管理标准（AVSDRM）致力于保护数字媒体内容的版权,AVSDRM标准针对IPTV平台专门提出了网络电视档。就AVSDRM标准在IPTV中的应用进行分析研究,以AVSDRM网络电视档参考模型为基础结合IPTV的平台特点以及业务特点提出了IPTVDRM系统架构,并详细描述了IPTVDRM系统模块、密钥体系及工作流程。     

一种用于ADC减少插值误差的预放大器

在分析折叠内插ADC预放大电路非线性误差的基础上,设计了一种适用于折叠内插ADC的新型预放大器,有利于减少插值非线性。采用0.35μmCMOS工艺,在3.3V电源电压下进行仿真。结果表明,在0.85V到2.45V输入范围内,预放大器过零点对应的输出电压保持在2.6V,0.1%的容差范围内,建立时间为4.2ns,有利于提高插值精度。     

量子噪声和非线性色抽运噪声共同驱动下单模激光的锁相

建立了一个由量子噪声和非线性色抽运噪声共同驱动下的单模激光立方模型,并将其在极坐标下分解为场幅和相位的朗之万方程(LE)。采用近似福克-普朗克方程的方法处理相位朗之万方程中的色噪声,使其马尔科夫化。将马尔科夫化后的相位朗之万方程与锁相条件相结合,得到稳定锁相值。详细讨论了量子噪声实虚部间的关联和抽运噪声实虚部间的关联对激光锁相的影响。结果表明激光锁相由量子噪声实虚部之间的关联引起,而抽运噪声实虚部间的关联和量子噪声实虚部间的关联均可改变这一锁相。     

HDFS一致性管理的研究

HDFS是开源云计算项目Hadoop的存储系统,具有良好的容错性和扩展性,但是HDFS原有的一致性模型不能适用于实时性要求高,数据完整性要求不严格的任务。为了让HDFS能够满足云存储不同应用场景,在已有HDFS的总体架构和读写流程基础上,从数据一致性的角度剖析HDFS的局限和不足,提出解决方案,把NWR模型引入HDFS当中,并且将文件系统的读写锁机制改进为多粒度的锁机制。实验结果证明：通过以上措施,使用户可以根据自身需要配置云存储系统,平衡一致性和可用性。     

基于MCU的直流纹波测试数据分析系统设计

提出一种基于MCU单片机的纹波电压采集分析系统,为了达到从微观上对纹波电压分析的目的,采用以STC89C54为控制核心,以Matlab为分析工具,应用层次化、模块化主导思想,融入了数据采集、数据交换、数据处理等多种关键技术,完成纹波信号的采集试验,得到系统分析所需研究数据,对未知纹波信号进行还原,并通过后期数据处理,了解纹波电压的存在情况,实现对纹波信号的测试与分析。该系统在以往单一测试或分析的基础上,把测试与分析融为一体,使纹波的研究工作又向前迈进一步。     

Engineering Surface Atomic Architecture of NiTe Nanocrystals Toward Efficient Electrochemical N2 Fixation

Efficient N₂ fixation at ambient condition through electrochemical processes has been regarded as a promising alternative to traditional Haber–Bosch technology. Engineering surface atomic architecture of the catalysts to generate desirable active sites is important to facilitate electrochemical nitrogen reduction reaction (NRR) while suppressing the competitive hydrogen evolution reaction. Herein, nickel telluride nanocrystals with selectively exposed {001} and {010} facets are synthesized by a simple process, realizing the manipulation of surface chemistry at the atomic level. It is found that the catalysts expose the {001} facets coupled with desirable Ni sites, which possess high Faraday efficiency of 17.38 ± 0.36% and NH₃ yield rate of 33.34 ± 0.70 μg h^?1 mg^?1 at ‐0.1 V vs RHE, outperforming other samples enclosed by {010} facets (8.56 ± 0.22%, 12.78 ± 0.43 μg h^?1 mg^?1). Both experimental results and computational simulations reveal that {001} facets, with selectively exposed Ni sites, guarantee the adsorption and activation of N₂ and weaken the binding for *H species. Moreover, the enhanced reduction capacity and accelerated charge transfer kinetics also contribute the superior NRR performance of {001} facets. This work presents a novel strategy in designing nonprecious NRR electrocatalyst with exposed favorable active sites.     

Terminal location method with NLOS exclusion based on unsupervised learning in 5G‐LEO satellite communication systems

We investigate the terminal location method in 5G‐Low Earth Orbit (5G‐LEO) satellite communication systems. To overcome the dependence on the external Global Navigation Satellite System (GNSS), we propose to use a single LEO satellite in 5G‐LEO satellite communication systems for terminal location and utilize the downlink synchronization detection for pseudorange differential measurement. Then, a data clustering method of unsupervised machine learning is proposed to classify the measured data into line‐of‐sight (LOS) and non‐line‐of‐sight (NLOS) signals. Furthermore, the NLOS data are excluded, and the Taylor series expansion iteration method is used to calculate the terminal coordinates. Simulation results show that the proposed method can effectively reduce the influence of NLOS error on measurement results and improve the accuracy of terminal location. In simulated urban scenario, the average location accuracy is improved from 10 km by traditional methods to 0.7 km and the convergence time is reduced from 400 to 250s.     

Tunable dual-wavelength actively mode-locked fiber laser with anF-P semiconductor modulator

A novel actively mode-locked fiber laser for generating dual-wavelength picosecond pulses is proposed by using a Fabry-Perot laser diode as the modulator in the ring cavity. A linear chirped fiber grating was used as a wavelength selector and produces temporal-spectral multiplexing of the pulses in the gain medium to reduce gain cross-saturation effects. About 2-GHz stable dual-wavelength pulses with a wavelength spacing of 0.92 nm at room temperature were experimentally demonstrated and the wavelengths could be tuned in a range of about 3 nm     

RS485通信最优波特率研究

在RS485总线中,主机和从机通常使用固定的波特率进行通信;而在实际应用中,波特率的大小和传输的距离是成反比的,波特率越高传输的距离越短,误码率增加越大。为避免波特率过高通信不可靠的问题,根据硬件波特率自适应的机制,文章采用从机数量来计算最优的波特率的方式进行主从机通信。经过实验验证,可提高RS485通信系统的稳定性。     

基于微信小程序的通达交流墙设计

近年来,随着高校学生们的情感需求愈发强烈,学生们也愈来愈需要平台来释放。由此,"表白墙"作为虚拟社区开始迅猛发展。而微信小程序经过数年的发展,已经相当完善,可以充当各行各业的工具与平台。微信小程序的轻应用、低成本等优点契合"表白墙"所需要的特性。因此,文章基于微信小程序,使用MINA框架开发出一款适合在校大学生的"表白墙"微信小程序。