10-GHz ultralow-noise optical sampling stream from a semiconductordiode ring laser

We report, what is to our knowledge, the lowest-noise pulsetrain produced to date with an actively mode-locked external-cavity semiconductor diode laser. Operating characteristics at 10 GHz include dispersion-compensated pulsewidths as short as 1.2 ps, amplitude noise as low as 0.12% rms, and residual phase noise as low as 43-fs rms. Potential application of such a laser in a next-generation optical analog-to-digital converter would theoretically provide as much as 8.6 bits of resolution, while sampling a 5-GHz waveform at the Nyquist frequency     

Enhanced Resource Blocks Management in D2D based Communication for 5G Networks

D2D based communication holds a promising future for 5G networks as they are efficient and can yield high data rates, good signal to noise interference ratio, improved resource-block uploading time, minimized delay from one end to the other and conserved power for transmission. The traditional system of cellular type contains cell edge clients who need a larger resource blocks count as well as time to upload data. Hence the quality of service will be reduced. The relay scheme in the proposal for cooperative type D2D networks is pivoted on the value of channel gain as well as transmission link distance. For bringing down the resource blocks’ count as well as uploading time, the paper is proposing a capable scheme of selection of relays that employs communication of D2D in the situations of uplinking. To begin with, in a cell modeling is done. It contains D2D pairs of multiple types as well as cellular clients. Next, the analysis related to issues of allocating resources as well as control of power is done. In order to lessen the resource blocks as well as their uploading time, the paper in proposal suggests a better blocks management mechanism that uses D2D based communication. Simulated output infers that the method in the proposal is superior to the present methods as far as time to upload contents; resource blocks, SINR, throughput as well as rates of data and Energy Consumption are concerned. Added to that, the stated method conserves 43% of the Energy Consumption of the network clients and while doing that the time to upload the contents is not affected.

     

桐乡市广电IP城域网系统配置优化探析

以CISCO系列交换设备组网为例,着重从生成树优化、OSPF路由优化、系统管理VLAN设置、网络时间校准以及设备配置标准模板等方面,简述了中小型广电IP城域网系统配置的优化思路以及几个参考实例。     

基于不经意传输的拓扑隐藏广播协议设

为了保护消息广播中节点关系、地理位置等敏感信息,将高效的NTRU(Number Theory Re―search Unit)公钥加密算法与不经意传输协议相结合,通过引入不可信的第三方以保证广播的中间过程无法被任意节点所获知,从而实现了隐藏网络拓扑结构的目标.该协议可认为是拓扑隐藏广播的具体实现,解决了现有概念性方案中尚未涉及的秘钥重构、相邻节点身份隐藏及网络动态变化等问题.安全性分析表明,在半诚实攻击模型下该方案能够保证网络中任何一部分节点被攻破均不会导致其他节点拓扑信息泄露.此外,通过与相关概念性协议进行实验对比分析,该方案除安全性外还可充分体现计算、通信开销与节点平均度数无关的优势.     

MIMO systems with full and reduced hardware complexity

MIMO (multiple-input-multiple-output) systems propose enormous gains in the capacity of wireless systems without requiring more spectral resources. This paper first gives an overview of the use of MIMO for diversity and spatial multiplexing, and the use of channel state information in MIMO systems. It then explores the use of antenna selection as a means for the reduction of the hardware complexity. It is shown that the performance in a spatial-multiplexing application is almost as good as that of full-complexity systems as long as the number of RF chains is at least as large as the number of data streams.     

New low-loss broadband SAW filter using unidirectional IDTs with U-shaped MSCs

A new low-loss broadband SAW filter is presented. A new configuration using one pair of electrically connected IDTs with an optimum number of fingers, as well as unidirectional IDTs with U-shaped MSCs, is described. Experimental results with bandwidth as wide as 10% and loss as low as 3 dB are achieved. Very accurate computer-aided design of a low-loss filter with MSCs is obtained.     

Mechanical Derivation of Fused Multiply–Add Algorithms for Linear Transforms

Several computer architectures offer fused multiply-add (FMA), also called multiply-and-accumulate (MAC) instructions, that are as fast as a single addition or multiplication. For the efficient implementation of linear transforms, such as the discrete Fourier transform or discrete cosine transforms, this poses a challenge to algorithm developers as standard transform algorithms have to be manipulated into FMA algorithms that make optimal use of FMA instructions. We present a general method to convert any transform algorithm into an FMA algorithm. The method works with both algorithms given as directed acyclic graphs (DAGs) and algorithms given as structured matrix factorizations. We prove bounds on the efficiency of the method. In particular, we show that it removes all single multiplications except at most as many as the transform has outputs. We implemented the DAG-based version of the method and show that we can generate many of the best-known hand-derived FMA algorithms from the literature as well as a few novel FMA algorithms.     

Characterization of mass-transported p-substrate GaInAsP/InPburied-heterostructure lasers with analytical solutions for electricaland thermal resistances

Studies have been carried out to evaluate mass-transported p-substrate GaInAsP/InP buried-heterostructure lasers, which have a number of potential advantages over the more conventional n-substrate lasers. Devices have been fabricated with series resistances as low as 3 Ω, in good agreement with the p-substrate spreading resistance calculated using conformal mapping. A further development of this theory yields simple formulas of thermal resistances of heat generated both in the active region and in the p-InP. The presently fabricated p-substrate lasers also showed CW threshold currents as low as 4.5 mA, differential quantum efficiencies as high as 34% per facet, output powers as high as 33 mW per facet, and a maximum total electrical-to-optical power conversion efficiency of 36%     

金刚石薄膜的结构特征与电导率的相关性

讨论了ＣＶＤ金刚石薄膜作为半导体材料的一些基本特性，主要叙述了金刚石薄膜的生长习性和结构特征对其电性能的影响，即其电导率的“尺度交 ”和“晶面效应”，以及这些效应对由金刚薄膜制备的半导体器件性能的影响。     

Vertical cavity surface-emitting semiconductor laser with CWinjection laser pumping

Room-temperature CW operation of a GaAs/AlGaAs vertical cavity surface-emitting laser with a resonant periodic gain medium, using a GaAs/AlGaAs diode laser array as a pump source, is discussed. Pumping thresholds as low as 11 mW at 730 nm, output powers as high as 10 mW at 856 nm, and external quantum efficiencies as high as 70% are obtained, with considerably improved temporal and spatial coherence properties compared to the pump laser. This is the first reported operation of such a laser with an efficient, compact pump source, demonstrating its suitability for efficient integration     

基于中红外DFB-ICL的氨气传感器设计

氨气是主要恶臭物质之一,为了实现工业环境污染源中氨气排放的连续监测,研制了中红外激光气体传感器,与传统近红外氨气传感器受干扰气体影响较大不同的是,该传感器采用中红外分布反馈结构的带间级联激光器(distributed feedback inter-band cascade laser, DFB-ICL)为光源,工作波长在3 μm附近,避免了水和CO2干扰气体的影响,同时以空芯光波导（芯径1 mm、长度5 m）做气体池,采用自制多通道数字锁相放大器,同时解调1f和2f谐波信号,实现免校准测量,获得了传感器的梯度实验结果,线性度高达0.99917,不确定度高达0.9%。Allan方差评价结果显示其稳定性非常出色,在最佳积分时间167 s时,本传感器的检测限低至9.7 ppb。     

Forecasting Research on the Wireless Mesh Network Throughput Based on the Support Vector Machine

Wireless Personal Communications - Parameters such as network busy rate, number of nodes as well as packet size that affected the wireless mesh network (WMN) throughput were selected as the driving...     

无线云网络可靠性建设：一种新的健壮且节能的网络拓扑控制方法

The future Wireless Cloud Networks (WCNs ) are required to satisfy both extremely high levels of service resilience and security assurance (i. e., Blue criteria ) by overproviding backup network resources and cryptographic protection on wireless communication respectively, as well as minimizing energy consumption (i.e., Green criteria) by switching off unnecessary resources as much as possible. There is a contradiction to satisfy both Blue and Green design criteria simultaneously. In this paper, we propose a new BlueGreen topological control scheme to leverage the wireless link connectivity for WCNs using an adaptive encryption key allocation mechanism, named as Shared Backup Path Keys (SBPK). The BlueGreen SBPK can take into account the network dependable requirements such as service resilience, security assurance and energy efficiency as a whole, so as trading off between them to find an optimal solution. Actually, this challenging problem can be modeled as a global optimization problem, where the network working and backup elements such as nodes , links , encryption keys and their energy consumption are considered as a resource, and their utilization should be minimized. The case studies confirm that there is a tradeoff optimal solution between the capacity efficiency and energy efficiency to achieve the dependable WCNs .     

Bitaper star couplers with up to 100 fibre channels

Biconically tapered fibre-optic star couplers with up to 100 fibre channels are reported which have excess insertion losses as low as ?0.56 dB and normalised standard deviations of output poers as low as 4.4%     

Optical properties of AlGaAs/GaAs nipi superlattices and theirapplication in asymmetric cavity spatial light modulators

Homo-nipi and hetero-nipi superlattices incorporated into asymmetric Fabry-Perot cavity structures are compared and evaluated for possible use as bit plane optical memory elements in terms of the magnitude of their optical nonlinearities, on-off contrast ratio, insertion loss, carrier lifetimes, and power required to change the state of the structure. Changes in superlattice absorption coefficient as high as 1500 cm^-1 and 1300 cm^-1 have been achieved in type I and type II AlGaAs/GaAs hetero-nipi structures, respectively. When normalized to the GaAs quantum well layer thicknesses, the change in absorption coefficient in the type I superlattice was as high as 12000 cm^-1. In asymmetric cavity modulator structures, on-off reflection contrast ratios as high as 60:1, carrier lifetimes as long as 4 ms, and on-state reflectivities as high as 0.62 have been observed. A 54:1 contrast ratio and an insertion loss of 8.5 dB were achieved simultaneously in a planar Fabry-Perot cavity structure excited with a pump beam power of 3.8 mW. The effective carrier lifetime in this case was 25 μs     

板线平衡器在八木天线中的应用

文中提出了用于八木天线的新型馈电结构———板线平衡器。给出了详细的板线平衡器和八木天线的设计过程及仿真和试验结果。在仿真设计的基础上制作了试验模型,并对其进行了测量。实验结果表明：板线平衡器具有设计灵活、耐高功率等特点。该天线既可当常规天线使用又可作为高功率宽频带阵列天线单元。     

基于FPGA的并行数据转SPI接口设计

在进行不同设备间的数据传输时,最基本的要求是连线尽可能少、数据传输速率尽可能快、误码率尽可能低。对此进行了并行数据转换为串行数据的接口电路研究,提出了同步并行传输速率的n倍改进SPI传输方案。其特点是传输速率高、时钟独立、可与并行接口端和SPI串行接口端进行双向通信。测试结果显示系统达到预定功能,其接口电路的实现方法可为数据的高速接口提供新的借鉴。     

Three-stage time-division switching network with pulse-shifting junctor as alternate route

The configuration of a 3-stage time-division switching network which has pulse-shifting junctors as the alternate route as well as direct junctors is proposed. A computer simulation to estimate the blocking probability of the system is performed, and proves the system to be nearly as efficient as the switching network without time-slot mismatch loss.     

A fast 7.5 ns access 1K-bit RAM for cache-memory systems

A 1024-bit ECL RAM with greatly improved speed performances was developed. Typical access time and write cycle time are as short as 7.5 and 10 ns, respectively, under 784 mW of power dissipation, achieving a power and access-time product as small as 5.7 pJ/bit. Novel ECL circuit techniques, especially in address decoder circuits, as well as improved process technologies enabled realizing these high-speed characteristics. The device uses a V-groove isolation process and a shallow emitter diffusion technology with doped polysilicon. It has a memory organization of 256-words by 4-bits where its main use is as a cache memory. Besides this basic organization, it has flexibility to also operate as a 512-word by 2-bit and 1024-word by 1-bit memory.     

Visual literacy in corporate communication: some implications forinformation design

A model for the design of information products is presented. The model serves as a resource to diagnose ineffective designs as well as a guide for the construction of effective displays. It accommodates many factors affecting the reader's processing of visual displays, including cognitive and perceptual processing, ergonomic factors, and the influence of cultural differences. Because the disciplines employed in this paper are incomplete and often depend upon speculation, the model should not be viewed as complete or comprehensive. However, the model can be modified as information design matures as a discipline