Optimization of Al_2O_3/SiN_x stacked antireflection structures for N-type surface-passivated crystalline silicon solar cells

In the case of N-type solar cells,the anti-reflection property,as one of the important factors to further improve the energy-conversion efficiency,has been optimized using a stacked Al₂O₃/SiN_x layer.The effect of SiN_x layer thickness on the surface reflection property was systematically studied in terms of both experimental and theoretical measurement.In the stacked Al₂O₃/SiN_x layers,results demonstrated that the surface reflection property can be effectively optimized by adding a SiN_x layer,leading to the improvement in the final photovoltaic characteristic of the N-type solar cells.     

Least squares estimation for a class of non-uniformly sampled systems based on the hierarchical identification principle

This paper presents a novel hierarchical least squares algorithm for a class of non-uniformly sampled systems. Based on the hierarchical identification principle, the identification model with a high dimensional parameter vector is decomposed into a group of submodels with lower dimensional parameter vectors. By using the least squares method to identify the submodels and taking a coordinated measure to address the associated items between the submodels, all the system parameters can be estimated. The proposed algorithm can save the computation cost. The performance analysis indicates that parameter estimates converge to their true values. The simulation tests confirm the convergence results.     

Aluminum/MoO3 anode thin films:an effective anode structure for high-performance flexible organic optoelectronics

正We report AI/MoO_3 thin film used as a complex anode in high-performance OLEDs.The unique efficacy of the device was found to result from the enhanced injection of holes into the commonly used hole-transporting molecules due to a large reduction in the interface dipole at the anode/organic interface.The superior optical characteristics are attributed to a strong cavity effect.Due to the ease of processing Al/M0O_3 we successfully demonstrated large-area flexible OLEDs on plastic substrates with uniform emission.     

无线传感网络中基于非抗窜扰智能卡的双因素认证协议

智能卡是最为常见的密码设备之一,因其抗窜扰特性,智能卡常常被用于电子商务、医疗健康以及物联网等高安全需求的领域中为安全提供服务。随着侧信道攻击、逆向工程等技术的发展,研究表明智能卡内保存的参数可恢复,使其不再具有抗窜扰特性,因而,基于非抗窜扰智能卡假设的多因素认证协议设计得到了广泛的关注。为此,研究了在无线传感网络中典型的多因素协议,指出其不能抵抗离线口令猜测攻击和中间人攻击、无法实现双向认证,以及不能抵抗离线口令猜测攻击、无法实现用户匿名性等问题。为克服这些缺陷,在非抗窜扰智能卡假设下,结合哈希链技术提出了一类面向无线传感器网络的双因素认证协议,并在随机预言机模型中给出了严格的安全证明。与现有无线传感网络环境下多因素认证协议相比,该协议在保持较低计算开销的同时,实现了更高的安全性,适于资源受限的无线传感器网络环境。     

Energy Efficient Cluster Based Routing Protocol for WSN Using Firefly Algorithm and Ant Colony Optimization

Maximizing network lifetime is the main goal of designing a wireless sensor network. Clustering and routing can effectively balance network energy consumption and prolong network lifetime. This paper presents a novel cluster-based routing protocol called EECRAIFA. In order to select the optimal cluster heads, Self-Organizing Map neural network is used to perform preliminary clustering on the network nodes, and then the relative reasonable level of the cluster, the cluster head energy, the average distance within the cluster and other factors are introduced into the firefly algorithm (FA) to optimize the network clustering. In addition, the concept of decision domain is introduced into the FA to further disperse cluster heads and form reasonable clusters. In the inter-cluster routing stage, the inter-cluster routing is established by an improved ant colony optimization (ACO). Considering factors such as the angle, distance and energy of the node, the heuristic function is improved to make the selection of the next hop more targeted. In addition, the coefficient of variation in statistics is introduced into the process of updating pheromones, and the path is optimized by combining energy and distance. In order to further improve the network throughput, a polling control mechanism based on busy/idle nodes is introduced during the intra-cluster communication phase. The simulation experiment results prove that under different application scenarios, EECRAIFA can effectively balance the network energy consumption, extend the network lifetime, and improve network throughput.

     

新型光伏材料Ag2ZnGeS(Se)4的第一性原理研究

通过基于密度泛函理论的第一性原理对新型光伏 材料Ag₂ZnGeS(Se)₄(AZGS(Se))的结 构稳定性、电子结构、和光学性质进行了研究。计算结果表明该类型化合物与Cu₂ZnSnS(S e)₄(CZTS(Se))一样具有锌黄锡矿的晶格结构;通过计算弹性常数和声子谱发现AZGS(Se) 的结 构稳定性也与CZTS(Se)相近。杂化泛函计算表明AZGS(Se)为直接带隙半导体;通过改变S和S e原子的比例,其禁带宽度可在1.27 eV 的较宽范围内调节。进一步计算光学性质,得 到AZGS(Se)的光吸收系数具有10⁴量级。计算结果表明AZGS(Se)符合太阳电池光吸收层的 需求。     

特种加工线切割机床智能渐进式走丝控制方案及控制器硬件电路设计

针对特种加工设备中走丝线切割机床升级改造需求大,成本高的问题,提出了一种低成本的设备改造方案。在不增加硬件投资的前提下,提出了精粗加工渐进使用电极丝的改造方案,并设计出智能渐进走丝控制器的硬件电路原理图和PCB板。通过与相关厂家的合作改造表明,该智能渐进走丝控制方案和硬件电路能够最大限度的降低改造成本,并能提升机床的加工精度、表面光洁度和加工的一致性。     

锥形图形衬底上氮化镓薄膜生长和表征

GaN films are grown on cone-shaped patterned sapphire substrates(CPSSs)by metal-organic chemical vapor deposition,and the influence of the temperature during the middle stage of GaN growth on the threading dislocation(TD)density of GaN is investigated.High-resolution X-ray diffraction(XRD)and cathodeluminescence(CL)wereusedtocharacterizetheGaNfilms.TheXRDresultsshowedthattheedge-typedislocation density of GaN grown on CPSS is remarkably reduced compared to that of GaN grown on conventional sapphire substrates(CSSs).Furthermore,whenthegrowthtemperatureinthemiddlestageofGaNgrownonCPSSdecreases,the full width at half maximum of the asymmetry(102)plane of GaN is reduced.This reduction is attributed to the enhancement of vertical growth in the middle stage with a more triangular-like shape and the bending of TDs.The CL intensity spatial mapping results also showed the superior optical properties of GaN grown on CPSS to those of GaN on CSS,and that the density of dark spots of GaN grown on CPSS induced by nonradiative recombination is reduced when the growth temperature in the middle stage decreases.     

Low-complexity iterative equalization for EDGE with bidirectional processing

We present a new and simple iterative equalization scheme for the enhanced data rates for global evolution (EDGE) wireless system. This scheme can significantly reduce the number of trellis states in a maximum a posteriori probability (MAP) equalizer via delayed decision-feedback (DDF) approach. Relying on the mechanism of decision feedback in the DDF trellis, bidirectional processing can be applied to exploit the time diversity of the received signal bursts for a more reliable equalizer output. With mild increase in computational complexity over the more traditional single-directional (Si) DDF turbo equalizer, the bidirectional turbo equalizer can achieve a significant performance gain.     

周期极化钽酸锂倍频窄谱线全光纤连续激光放大器特性

通过准相位匹配技术,采用1μm波段高功率窄谱线连续光纤激光放大器抽运高二次谐波转换效率周期性极化晶体,是实现高光束质量、小型化、高功率连续绿光激光器的一个非常有前途的方向。实验自主研发了高效率主振荡功率放大(MOPA)全光纤保偏放大模块,获得中心波长为1064.25nm,线宽为0.035nm的30 W连续线偏振激光,并以此作为基频光抽运国产周期极化钽酸锂(PPSLT)晶体进行了外腔单通倍频实验。保持PPSLT晶体的控制温度为145.6℃,在抽运光功率为21.5W时得到了2.1W的绿光输出。实验分析了温度、基频光功率密度和Boyd-Kleinman聚焦因子对倍频光转换效率的影响。实验过程中没有出现饱和现象,进一步提高抽运功率有望获得更高功率的绿光。