无线mesh网中费用最小且QoS约束的网关部署算法研究

基于图的支配集理论,提出图的有限支配集的概念应用于满足QOS约束的无线mesh网网关优化部署,以获取费用最小网关部署方案,进而把QoS约束的费用最小网关部署问题归结为图的最小权有限支配集的问题.为求解图的最小权有限支配集,提出了贪婪算法GREEDY_LDS,该算法以网关的部署性价比作为启发信息,依次挑选部署性价比高的节点加入有限支配集,最后得到权值较小的有限支配集;为得到更加优化的解,利用粒子群优化算法的全局寻优优势,提出粒子群优化算法PSO_LDS,该算法通过阻止粒子在狭小区域运动来防止算法陷入早熟收敛.模拟实验表明,GREEDY_LDS算法执行速度快,当网关候选节点数超过总节点数的17%时,能得到比其他算法更好的结果;PSO_LDS算法以增加执行时间为代价,与GREEDY_LDS和OPEN/CLOSE算法相比,得到的网关部署方案的费用分别减少约15%和9%.     

移动混合传感网中节点自主部署算法

针对节点感知半径不均衡的移动传感网络节点的部署问题,论文提出一种基于VL(Voronoi Laguerre)图分割的节点自主部署算法(Autonomous Deployment Algorithm, ADA)。ADA先对目标区域做VL图划分,将目标区域的覆盖任务在各个传感器节点之间进行分配。分配到覆盖子区间任务的节点通过构造VL受控多边形来确定下一轮候选目标位置。未分配到覆盖子区间的节点则根据自身与邻居节点感知圆及目标区域边界的几何位置关系计算所受虚拟力,最终确定下一轮目标点坐标。网络各个节点通过逐轮更新自身位置,从而提高网络覆盖。仿真结果表明,ADA算法在网络覆盖率、节点部署速度和节点分布均匀性等方面具有明显的优势。     

一种大规模传感器网络节点分布式定位算法

针对大规模无线传感器网络(WSN)中节点难以定位的问题,该文提出一种基于改进牛顿法的分布式定位算法。该算法包括网络划分和分布式算法。首先,根据节点位置和节点之间直接相连的距离信息,将无线传感器网络划分为若干个重叠的子区域,并将子区域的定位问题归结为无约束优化问题,每个子区域可以独立计算;然后,使用分布式算法估计子区域中的节点位置并进行局部融合。实验结果表明,与已有算法相比,该算法具有良好的扩展性,在大规模网络中定位精度更高,能满足大规模无线传感器网络中节点定位需求。     

基于L-hop路由策略的无线mesh网络的吞吐量

无线mesh网络是最后一英里宽带互联网的可选技术之一。类似于ad hoe网络。在mesh网络中，每个用户节点既是通信终端又提供路由功能；用户节点以ad hoe多跳方式实现与网关的链接，通过网关可以访问因特网。无线mesh网络的吞吐量受到网关带宽的限制。为了捷高mesh网络网关频带的利用效率，现提出基于节点组织ad hoe通信方式和L-hop路由策略。在新的路由策略下，将给出对mesh网络的吞吐量的研究。     

一种能耗均衡的无线传感器网络路由算法

为了延长采用电池供电的无线传感器网络的生命周期,提出了一种综合考虑单个节点能耗和节点传输信息至汇集节点所需总能耗的路由算法.该算法首先根据网络中节点到汇集节点从小到大的距离顺序选择待规划节点,然后计算各对应候选节点的评价参数,该参数由单节点能耗和节点传输信息至汇集节点所需总能耗加权得到,最后选择评价参数最小的候选节点作为待规划节点的中继节点.仿真结果表明,该算法的生命周期明显长于LEACH(Low Energy Adaptive Clustering Hier-archy)算法.     

基于T—Hop的无线传感器网络定位方法

在无线传感器网络中,在传感器节点部署不规则的情况下邻居节点对之间的距离有很大差别,用DV-Hop算法定位通常会产生很大误差。为此,文章提出一种改进的T-Hop定位算法,即在未知节点到锚节点的路径中,考虑局部邻居节点部署对节点的影响,根据节点同阶邻居节点,引入节点上下游邻居节点个数来计算节点间距离。仿真结果显示,改进的算法提高了节点的定位精度。     

基于干涉效应的无线传感器节点定位方法

针对无线传感器网络中节点定位的需求,提出了一种基于干涉效应的传感器节点定位算法。该方法仅需要利用节点的硬件设备,不需要增加额外的测量设备,各个节点独立进行自身位置估计,实现分布式定位。首先在传感器网络中设置若干个位置已知的网关锚节点和参考接收节点,不同位置两个网关锚节点在某个时隙内发射单音信号,就会在整个定位区域内形成一个干涉效应场。而各个待定位节点通过测量接收的到的干涉信号振动周期数就可以得到自身与各个网关节点距离差。通过多组锚节点分时隙发射单音信号,并配合参考接收节点,通过双曲线定位算法得到自身的坐标。通过对算法进行仿真分析,验证了算法的可行性。     

联合最小路径和能量调配的路由算法的实现

基于最小耗能路径和路由能量信息的结合,提出了一个新型算法,在节点生命周期上做出改善,同时延长整个无线传感器网络的生存周期.对节点的能量信息划分了等级,相应的等级都匹配对应相应的信息传递概率,并且还对网络进行了分块分层划分.在节点生命周期上有了很大的改善,并且延长了整个无线传感器网络的生存周期,网络节点之间以及网关和节点间的依赖关系更加明显,最佳路径以及结合路径的能量调配得以实现,提高了整个网络效率.所以算法达到了提高网络性能的要求,并且很合理.     

一种有效的稀疏无线传感器网络路由方案

稀疏无线传感器网络中节点之间距离过远,使得移动代理节点成为最有效的数据收集方式,然而移动代理节点由于能量限制无法在一次数据收集中到达网络所有节点进行数据收集.为保证在能量受限的移动代理节点总路由路径最短,给出了一种稀疏无线传感器网络能量受限移动代理节点的路由方案.首先构建移动代理节点的路由数学模型,然后根据移动代理节点初始能量将无线传感器网络划分成不同的子集,最后采用旅行商人问题的模拟退火算法计算出每个子集最短路由,全部子路由的集合即最优路由.仿真及其分析结果表明:随着网络节点个数增多和移动代理节点能量增大,所给方案的总路由能够比较接近于理想情况,在实际应用中比较有效且适于推广.     

无线传感器网络中移动sink节点的路径规划

在无线传感器网络中,大量感知数据汇集到sink节点的采集方法会导致sink节点附近的节点能量耗尽,造成能量空洞。针对该问题,利用移动的sink节点进行数据收集是一种解决方法,其中移动sink的路径规划成为一个重要的问题。提出了一个移动sink路径规划算法,将无线传感器中随机分布的节点划分为不同的子区域,寻找sink节点移动的最佳转向点,最终得到最优的移动路径,以实现无线传感器网络生命周期最大化。仿真实验表明,与现有方案相比,该算法能显著延长网络的生命周期。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Call for Papers

正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its