SnO2薄膜气敏光学特性的气敏机理模型

本文作者利用表面态建立一个气敏光学机理模型。较好地解释了SnO_2薄膜的气敏效应,气敏透射光谱,气敏透过率与气体浓度的指数关系,以及饱和现象等。     

多媒体通信中智能化媒体内同步机制

本文提出了一种智能化视频流量的预测和同步机制（ＩＦＳＭ）,它由ＢＰ神经网络流量预测器（ＢＰＮＮ）、输出缓冲区和基于模糊神经网络（ＦＮＮ）的输出速率决策器所组成。ＢＰＮＮ采用一种在线训练的ＢＰ神经网络预测在将来的一定时间间隔（ＦＩ）内的平均分组速率,ＦＮＮ决策器根据预测的流量特性和缓冲区中的分组数动态地调节下一个分组输出的时间。仿真结果表明：与窗口机制相比,ＩＦＳＭ能够使视频流量取得较高的连续性和较低的时延,并且由于ＦＮＮ的学习能力,ＩＦＳＭ可以自适应地调节相应参数以满足不同的服务质量的要求。     

Internet的移动接入

为了满足移动式计算机用户对Ｉｎｔｅｒｎｅｔ移动接入需求的急剧增长,Ｉｎｔｅｒｎｅｔ工程任务组设计了移动ＩＰ。本文介绍了移动ＩＰ协议的基本特点、工作原理、路由优化及安全性,并对移动ＩＰｖ６和基于ＡＴＭ的移动ＩＰ作了简单的分析。     

Analysis of nonblocking ATM switches with multiple input queues

An analytical model for the performance analysis of a multiple input queued asynchronous transfer mode (ATM) switch is presented. The interconnection network of the ATM switch is internally nonblocking and each input port maintains a separate queue of cells for each output port. The switch uses parallel iterative matching (PIM) to find the maximal matching between the input and output ports of the switch. A closed-form solution for the maximum throughput of the switch under saturated conditions is derived. It is found that the maximum throughput of the switch exceeds 99% with just four iterations of the PIM algorithm. Using the tagged input queue approach, an analytical model for evaluating the switch performance under an independent identically distributed Bernoulli traffic with the cell destinations uniformly distributed over all output ports is developed. The switch throughput, mean cell delay, and cell loss probability are computed from the analytical model. The accuracy of the analytical model is verified using simulation     

IEEE802.15.4协议的性能分析与仿真

IEEE 802.15.4是一个自组织的无线网络标准,其中制定了PHY层和MAC层规范,主要应用场合为低成本、低功耗、低复杂度的无线个域网.许多参数在IEEE 802.15.4标准中仅给出取值范围而并未给出确定的值,虽然这些值对系统性能有着较为显著的影响.个域网中的设备大量采用电池供电,因此实现更低的能量消耗是该网络标...     

一种ECC加密芯片抗功耗攻击研究

设计了随机掩码在ECC加密算法中的应用方法,为了降低加密芯片的功耗和面积,提高运算性能,研究设计了关键步固定值掩码算法,实验证明提出的方法在资源增加非常有限的情况下可以有效抵抗一阶差分功耗攻击.同时,其他加密算法也可参考此关键步固定值掩码算法来高效设计抗功耗攻击加密芯片.     

基于一维测量的多传感器多目标数据关联

本文在S-D分配算法的基础上,提出一种基于一维测量数据的多基地雷达多目标数据关联的方法.在每个传感器仅能给出目标的一维距离和量测信息,并且同时存在虚警的条件下,该方法首先利用4维组合的冗余信息对各传感器的量测值进行组合筛选,然后由4维分配算法进行多目标的数据关联,仿真结果表明该方法可以有效提高多目标的正确关联概率.     

Data consistency based rigid motion artifact reduction in fan-beam CT

It is well known that a rigid in-plane motion can be decomposed into a translation and a rotation around an origin. Based on our previous work, we first extend the Helgason-Ludwig consistency condition (HLCC) to cover a general rigid motion in fan-beam geometry. Then, we model the general motion by several parameters, and develop an iterative scheme for estimation of the in-plane motion parameters. This scheme determines the motion parameters by numerically minimizing an objective function constructed based on the HLCC. After the motion parameters are estimated, image reconstruction can be performed to compensate for the motion effects. Finally, we implement the algorithm and evaluate its performance in numerical simulations.     

Energy Transfer Induced by TADF Polymer Enables the Recycling of Excitons in Perovskite Solar Cells

Formamidinium lead triiodide (FAPbI₃) has been demonstrated as the most efficient perovskite system to date, due to its excellent thermal stability and an ideal bandgap approaching the Shockley-Queisser limit. Whereas, there are intrinsic quantum confinement effects in FAPbI₃, which lead to unwanted non-radiative recombination. Additionally, the black α-phase of FAPbI₃ is unstable under room temperature due to the significant residual tensile stress in the film. To simultaneously address the above issues, a thermally-activated delayed fluorescence polymer P1 is designed in the study to modify the FAPbI₃ film. Owing to the spectral overlap between the photoluminescence of P1 and absorption of the above-bandgap quantum wells of FAPbI₃, the Förster energy transfer occurs at the P1/FAPbI₃ interface, which further triggers the Dexter energy transfer within FAPbI₃. The exciton “recycling” can thus be realized, which reduces the non-radiative recombination losses in perovskite solar cells (PSCs). Moreover, P1 is found to introduce compressive stress into FAPbI₃, which relieves the tensile stress in perovskite. Consequently, the PSCs with P1 treatment achieve an outstanding power conversion efficiency (PCE) of 23.51%. Moreover, with the alleviation of stress in the perovskite film, flexible PSCs (f-PSCs) also deliver a high PCE of 21.40%.     

RBSiC陶瓷素坯连接研究

将碳化硅(Si C)微粉、酚醛树脂和炭黑等均匀混合,配置成连接浆料,真空除泡后连接Si C陶瓷素坯,高温反应烧结后得到反应烧结Si C(RBSi C)连接镜坯。讨论了浆料配方对焊缝显微结构的影响,测试了RBSi C连接坯体的力学性能和线膨胀系数。研究表明:连接浆料中加入聚乙二醇200(PEG200)和聚乙烯醇吡咯烷酮(PVP),能够有效分散炭黑,保证反应烧结过程中炭黑与硅完全反应,无残余碳存在,实现焊缝与基材之间显微结构的一致性;Si C连接坯体素坯和反应烧结后的抗弯强度值分别24.9 MPa和322.9 MPa,而且断裂位置在基材上;在-100~400℃范围内,RBSi C连接坯体与基体线膨胀系数差异仅为0.011 4 ppm。