Regulating the Water Molecular in the Solvation Structure for Stable Zinc Metal Batteries

Rechargeable aqueous zinc batteries are promising energy storage devices because of their low cost, high safety, and high energy density. However, their performance is plagued by the unsatisfied cyclability due to the dendrite growth and hydrogen evolution reaction (HER) at the Zn anode. Herein, it is demonstrated that the concentrated hybrid aqueous/non-aqueous ZnCl₂ electrolytes constitute a peculiar chemical environment for not only the Zn-ions but also water molecules. The high concentration of chloride ions substitutes the H₂O molecular in the solvation structure of Zn²⁺, while the acetonitrile further interacts with H₂O to decrease its activity. The hybrid electrolytes both inhibit the dendrite formation and HER, enabling an ultrahigh average Coulombic efficiency of 99.9% in the Zn||Cu half-cell and a highly reversible Zn plating/stripping with a low overpotential of 21 mV. Using this hybrid electrolyte, the Zn||polytriphenylamine (PTPAn) full cell deliveres a high discharge capacity of 110 mAh g⁻¹, a high power density of 9200 W kg⁻¹ at 100 °C and maintains 85% of the capacity for over 6000 cycles at 10 °C. This study provides a deep understanding between the solvation structure and columbic efficiency of Zn anode, thus inspiring the development for stable Zn batteries.     

单路反馈射频功放预失真线性化方法

该文基于记忆多项式模型,提出一种采用单路反馈的射频功放预失真线性化新方法,只需用正交解调后的IQ信号中的一路,就可完成对预失真器模型参数的获取。该方法可消除使用正交解调器所带来的增益和相位不平衡问题,且节省了一路反馈采样电路,在降低成本、简化设计的同时还能提高预失真线性化的性能。仿真和物理实验结果表明,该文提出的方法是正确的,能达到比较好的线性化效果。     

纳秒激光加工石英微通道的实验与理论研究

利用调Q Nd…YAG激光器输出的1064nm纳秒脉冲激光聚焦在石英上,分别采用激光热加工法和激光诱导等离子体法加工微通道。热加工的通道长度可控,通道周围产生热裂纹;诱导等离子体加工的微通道内壁光滑,通道深度可达4mm。研究了激光热加工微通道时的温度场和热应力分布,分析了激光诱导等离子体加工微通道的过程。研究表明,激光热加工时温度场的存在导致热应力的产生,热应力超过石英断裂阈值使石英发生炸裂,导致微通道的形成及热裂纹的产生;激光诱导等离子体法由于等离子体屏蔽效应产生的高温等离子体烧蚀石英形成微通道,避免了热裂纹的产生。     

A MAC-Layer QoS Provisioning Protocol for Cognitive Radio Networks

Due to the proliferation of diverse network devices with multimedia capabilities, there is an increasing need for Quality of Service (QoS) provisioning in wireless networks. The MAC layer protocol with enhanced distributed channel access (EDCA) in the IEEE 802.11-2007 is able to provide differentiated QoS for different traffic types in wireless networks through varying the Arbitration Inter-Frame Spaces (AIFS) and contention window sizes. However, the performance of high priority traffic can be seriously degraded in the presence of strong noise over the wireless channels. Schemes utilizing adaptive modulation and coding (AMC) technique have also been proposed for the provisioning of QoS. They can provide limited protection in the presence of noise but are ineffective in a high noise scenario. Although multiple non-overlapped channels exist in the 2.4 and 5?GHz spectrum, most IEEE 802.11-based multi-hop ad hoc networks today use only a single channel at anytime. As a result, these networks cannot fully exploit the aggregate bandwidth available in the radio spectrum provisioned by the standards. By identifying vacant channels through the use of cognitive radios technique, the noise problem can be mitigated by distributing network traffic across multiple vacant channels to reduce the node density per transmission channel. In this paper, we propose the MAC-Layer QoS Provisioning Protocol (MQPP) for 802.11-based cognitive radio networks (CRNs) which combines adaptive modulation and coding with dynamic spectrum access. Simulation results demonstrate that MQPP can achieve better performance in terms of lower delay and higher throughput.     

Ⅴ/Ⅲ比和生长温度对RF-MBE InN表面形貌的影响

由于生长InN所需平衡氮气压较高,而且InN分解温度比较低,因此在生长InN时In原子很容易在表面聚集形成In滴,使InN外延膜的表面形貌变差,影响InN外延膜质量的提高.通过研究Ⅴ/Ⅲ比和生长温度对RFMBE生长InN外延膜表面形貌的影响,发现Ⅴ/Ⅲ比和生长温度对InN外延膜表面In滴的量有重要影响.通过选择合适的Ⅴ/Ⅲ比和生长温度,得到了表面平整光亮、无In滴的InN外延膜.     

Secrecy sum rate optimization in MISO nonorthogonal multiple access systems with orthogonal space‐time block coding

In this paper, we investigate the secrecy sum rate optimization problem for a multiple‐input single‐output (MISO) nonorthogonal multiple access (NOMA) system with orthogonal space‐time block codes (OSTBC). This system consists of a transmitter, two users, and a potential eavesdropper. The transmitter sends information by orthogonal space‐time block codes. The transmitter's precoder and the power allocation scheme are designed to maximize achievable secrecy sum rate subject to the power constraint at the transmitter and the minimum transmission rate requirement of the weak user. We consider two cases of the eavesdropper's channel condition to obtain positive secrecy sum rate. The first case is the eavesdropper's equivalent channel is the weakest, and the other is the eavesdropper's equivalent channel between the strong user and weak user. For the former case, we employ the constrained concave convex procedure (CCCP)‐based iterative algorithm with one‐dimensional search. While for the latter, we adopt the method of alternating optimization (AO) between precoder and power allocation. We solve a semidefinite programming to optimize the precoder and drive a closed‐form expression of power allocation. The simulation results obtained by our method demonstrate the superiority of our proposed scheme.     

整机柜定制化服务器应用实践研究

整机柜定制化服务器在机柜层面统一了服务器的硬件设计方案,具有更高的集成度和更低的平均能耗。因此,介绍整机柜定制化服务器的发展应用现状,通过某资源池工程的安装部署情况,分析整机柜定制化服务器相对于传统服务器的优点及部署应用时存在的问题,最后结合工程实践提出了后续部署优化建议。     

Dynamic voltage scaling based energy-minimized partial task offloading in fog networks

Wireless Networks - With the dynamic voltage scaling (DVS) technology, the terminal node (TN) can dynamically adjust its computational speed, thus providing a new way to save energy during task...     

基于NDIS技术6rd软终端的设计与实现

简述并分析6rd技术;结合WindowXP平台的协议栈特性设计了6rd软终端的实现方案,并利用NDIS中间层驱动实现了6rd软终端;通过分析数据包结构测试评估了6rd软终端的工作情况。     

光散射聚合物导光板的模拟分析

导光板是液晶显示器背光照明系统的核心组件,导光板的质量优劣直接影响到液晶显示器的显示效果、厚度、使用寿命及成本。文章建立了新型体散射聚合物导光板的数学模型,并应用米散射理论和蒙特卡罗方法对此类导光板进行了模拟分析,研究了掺杂粒子种类、密度、粒径、相对折射率、导光板尺寸等因素对导光板出光效果的影响规律,筛选出了合适的导光板基质和掺杂粒子材料,为实验制作体散射聚合物导光板提供了可靠依据。