Response time improvement of AlGaN photoconductive detectors by adjusting crystal-nuclei coalescence process in metal organic vapor phase epitaxy

AlGaN photoconductive ultraviolet detectors are fabricated to study their time response characteristics. Persistent photoconductivity,a deterring factor for the detector response time,is found to be strongly related to the grain boundary density in AlGaN epilayers.By improving the crystal-nuclei coalescence process in metal organic vapor phase epitaxy,the grain-boundary density can be reduced,resulting in an-order-of-magnitude decrease in response time.     

线状WSN中基于概率分流的负载均衡路由协议

针对线状无线传感器网络中节点能量消耗不均衡现象,本文提出基于概率分流的负载均衡路由协议,以一定规则建立多条路由路径,通过使负载较轻路径上的节点以一定概率分担负载较重路径上节点的数据传输任务,均衡网络中各个节点的负载。仿真结果表明,本协议能有效地改善各个节点能量消耗的均衡性,延长网络生存时间。     

Reticulate Dual‐Nanowire Aerogel for Multifunctional Applications: a High‐Performance Strain Sensor and a High Areal Capacity Rechargeable Anode

Nanowire aerogels (NWAs) are highly versatile and used in many applications. However, most synthesized NWAs are composed of single components that may produce unsatisfactory aggregated performance in mechanical strength, conductivity, and electrochemistry. To address this issue, a reticulate dual‐nanowire aerogel (rDNWA) composed of FeS₂ nanowires and carbon nanotubes (CNTs) via a simple solvothermal method is synthesized. The rDNWA possesses excellent compressibility (modulus of 1.32 MPa), good conductivity (0.65 S cm^?1), and high porosity (>98%). It can be applied as a high‐performance strain sensor with good sensitivity (Gauge Factor = 1.69) and enhanced stability. It can be densified to yield a high areal capacity of 10.0 mAh cm^?2 and a high mass loading of 14.4 mg cm^?2 after 100 cycles. As a freestanding anode for lithium ion battery (LIB), it exhibits a high specific mass capacity of 1031 mAh g^?1 after 100 cycles at a current density of 100 mA g^?1 and retains it to 729 mAh g^?1 at a current density of 500 mA g^?1 after 400 cycles. The outstanding overall performance of the hybrid aerogel is derived from the synergistic effect of intertwined CNTs and FeS₂ nanowires and can be extended to fabricate NWAs with novel multifunctional capabilities.     

Water‐Soluble Triazolium Ionic‐Liquid‐Induced Surface Self‐Assembly to Enhance the Stability and Efficiency of Perovskite Solar Cells

Despite being a promising candidate for next‐generation photovoltaics, perovskite solar cells (PSCs) exhibit limited stability that hinders their practical application. In order to improve the humidity stability of PSCs, herein, a series of ionic liquids (ILs) “1‐alkyl‐4‐amino‐1,2,4‐triazolium” (termed as RATZ; R represents alkyl chain, and ATZ represents 4‐amino‐1,2,4‐triazolium) as cations are designed and used as additives in methylammonium lead iodide (MAPbI₃) perovskite precursor solution, obtaining triazolium ILs‐modified PSCs for the first time (termed as MA/RATZ PSCs). As opposed to from traditional methods that seek to improve the stability of PSCs by functionalizing perovskite film with hydrophobic molecules, humidity‐stable perovskite films are prepared by exploiting the self‐assembled monolayer (SAM) formation of water‐soluble triazolium ILs on a hydrophilic perovskite surface. The mechanism is validated by experimental and theoretical calculation. This strategy means that the MA/RATZ devices exhibit good humidity stability, maintaining around 80% initial efficiency for 3500 h under 40 ± 5% relative humidity. Meanwhile, the MA/RATZ PSCs exhibit enhanced thermal stability and photostability. Tuning the molecule structure of the ILs additives achieves a maximum power conversion efficiency (PCE) of 20.03%. This work demonstrates the potential of using triazolium ILs as additives and SAM and molecular design to achieve high performance PSCs.     

Treefrog Toe Pad‐Inspired Micropatterning for High‐Power Triboelectric Nanogenerator

Inspired by treefrog's toe pads that show superior frictional properties, herein, an industrially compatible approach is reported to make an efficient dielectric tribosurface design using customizable nonclose‐packed microbead arrays, mimicking the friction pads of treefrogs, in order to significantly enhance electrification performance and reliability of triboelectric nanogenerator (TENG). The approach involves using an engineering polymer to prepare a highly ordered large‐area concave film, and subsequently the molding of a convex patterned triboreplica in which the concave film is exploited as a reusable master mold. A nature‐inspired TENG based on the patterned polydimethylsiloxane (PDMS) paired with flat aluminum (Al) can generate a relatively high power density of 8.1 W m^?2 even if a very small force of ≈6.5 N is applied. Moreover, the convex patterned PDMS‐based TENG possesses exceptional durability and reliability over 25 000 cycles of contact–separation. Considering the significant improvements in power generation of TENG; particularly at very small force, together with cost‐effectiveness and possibility of mass production, the present methodology may pave the way for large‐scale blue energy harvesting and commercialization of TENGs for many practical applications.     

采用解码转发中继策略的多跳自由空间光通信系统性能分析(英文)

This paper investigates the performance of multi-hop Free Space Optical(FSO) communications using serial Decode-and-Forward(DF) relay transmissions.A statistical model for the optical intensity fluctuation at the receiver due to the combined effects of atmospheric turbulence-induced fading,mis alignment fading and pass-loss is presented.Under given weather and mis alignment conditions,a closed-form analytical expression for the end-to-end outage probability of serial Decode-and-Forward(DF) multi-hop FSO com...     

主动学习半监督聚类入侵检测算法

针对聚类的入侵检测算法误报率高的问题,提出一种主动学习半监督聚类入侵检测算法.在半监督聚类过程中应用主动学习策略,主动查询网络中未标记数据与标记数据的约束关系,利用少量的标记数据生成正确的样本模型来指导大量的未标记数据聚类,对聚类后仍未能标记的数据采用改进的K-近邻法进一步确定未标记数据的类型,实现对新攻击类型的检测.实验结果表明了算法的可行性及有效性.     

均匀介质中麦克斯韦方程的无衍射解

在均匀等离子体中麦克斯韦方程的一个严格积分解的基础上给出了若干不同形式的初始光波在其中演化的严格解，包括熟知的平面波解，著名的无衍射波解和三维空间中的球对称无衍射波解。作为一种群速度为零的光束，三维无衍射波的行为是令人惊讶的     

超强激光场中H_2~ 的隧道离解和波包演化

利用超强激光脉冲中分子与场相互作用的多电子态模型，数值模拟了分子波包在高低频超强激光场中的演化过程。结果发现，高频场中分子波包的扩展是渐进的，直到脉冲作用结束，分子才完全离解；而在低频场中，分子波包迅速隧穿到离解态，仅在脉冲的前几个周期，波包便溢出相互作用区。另外还比较了高低频场作用下分子的离解几率和离解碎片的动量分布。     

Assessment of intestinal amino acid availability in cattle by use of the precision-fed cecectomized rooster assay

The digestibilities of amino acids in duodenal digesta of steers were measured using a precision-fed cecectomized rooster assay. Freeze-dried duodenal digesta from steers fed five different diets were utilized. Amino acids present in digesta of steers fed diets supplemented with corn gluten meal were more digestible than those from digesta of steers fed diets supplemented with soybean meal, blood meal, fish meal, or no true protein source. Measurements of amino acid digestibility in the cecectomized rooster were similar to those obtained previously when measured with reference to chromic oxide in steers fitted with duodenal and ileal cannulae, suggesting that the precision-fed cecectomized rooster assay is an appropriate technique for estimating small intestinal digestibility of amino acids in cattle.