Relay with deflection routing for effective throughput improvement in Gbps millimeter-wave WPAN systems

In this paper, we propose a deflection routing scheme that improves effective throughput (defined as the successfully transmitted bits over the duration between two available sequential time slots) of millimeter-wave wireless personal area network (mmWave WPAN) systems. The upcoming mmWave WPAN is based on dynamic time division multiple access (TDMA) and designed to guarantee Gbps-order transmission capability for high definition TV (HDTV) transmission, high speed wireless docking and gaming, etc. The decode-and-forward (DF) type of relay offers a simple solution to the issues of mmWave WPAN systems, such as limited coverage range and unexpected blockage. However, due to the required extra time, DF relay on the other hand decreases the effective throughput, and may not be sufficient to satisfy the requirement of the above data-rate-greedy applications. Inspired by the fact that the significant path loss of a millimeter-wave environment can provide good space isolation, we propose a deflection routing scheme to improve the effective throughput by sharing time slots for direct path with relay path. Based on the sub-exhaustive search, a routing algorithm, named as best fit deflection routing (BFDR), has been developed to find the relay path with the least interference that maximizes the system throughput. To reduce the computational complexity of the BFDR, we have also developed a sub-optimal algorithm named as random fit deflection routing (RFDR). The RFDR algorithm finds the sub-optimized relay path, where the interference may not be the least but is sufficiently low to guarantee the concurrent transmissions. Computer simulations show that, in realistic 60 GHz environments, the effective system throughput can be improved up to 28% under grid topology and 35% under random topology. RFDR achieves almost the same order of throughput improvement with only 10% of the computational complexity of BFDR.     

Cross-layer sequential sensing with effective throughput maximization in time-slotted cognitive networks

This paper studies slotted cognitive networks which include multiple spectrum bands and time is divided into slots. In order to increase the opportunity to use idle band, we consider that a secondary user sequentially senses multiple bands within a time slot. To maximize effective throughput excluding sensing overhead, transmission overhead and useless transmission while interference is guaranteed, we shall determine sensing time, frame size, and which band a secondary user sends frames in. We study two sequential sensing policies, namely forward sensing and recall sensing, which determine which band to transmit; the former policy forwardly senses bands one by one, and the latter policy senses a band and records the related information which is used to return back to the band if the effective throughput of other being sensed bands is lower than that of the band. Analyses verified by simulations are developed for the sensing policies; based on the analysis, we find optimal sensing time in physical layer, frame size in medium access control layer. We compare the forward and recall sensing policies with a sequential sensing merely with information in physical layer. Numerical results show that (i) the forward and recall sensing policies outperform the compared sequential sensing policy and (ii) the recall sensing policy outperforms the forward sensing policy at light load. In addition, the effects of sensing time and frame on the forward and recall sensing are extensively studied.     

Automated camerawork for capturing desktop presentations

A novel automated camera control method for capturing desktop presentations is introduced. Typical features and the camerawork of shots that appear frequently in TV programs are discussed. To realise those features in this automated video capturing system, the purpose of camerawork is classified from two points of view: target and aspect-of-target. Then, the correspondence between the classification and typical shots and camerawork is considered. A virtual-frame control algorithm based on this idea is proposed, and its implementation in a video production system. Results are shown that verify this method through two kinds of experiments, virtual video capturing using CG animations and real video capturing of real presentations.     

中温热补偿MLC陶瓷

本文研究了ＢａＯ－ＴｉＯ２－Ｎｄ２Ｏ３（ＢＴＮ）系陶瓷的结构和介电性质。在该系统中加入适量的玻璃和添加剂，获得了一系列中温热补偿独石电容器（ＭＬＣ）陶瓷，实验结果证实：当Ｔｉ／Ｂａ＝１．００３时，ＢＴＮ系陶瓷的居里温度（Ｔｃ）随Ｎｄ２Ｏ３含量的增大而产生逐步漂移。用ＸＲＤ确定了陶瓷的主晶相，ＳＥＭ照片显示出晶粒尺寸对Ｎｄ＾３＋含量的依赖关系，分析了Ｔｉ／Ｂａ比对陶瓷介电系数温度系数（ａｅ）的影响。     

The battle for the desktop [network computers]

This article describes how, with a new type of machine called the network computer, or NC, a group of upstarts wants to muscle in on the personal computer's turf. The author examines whether this type of computer, designed from the outset to work on a network, can topple the PC's dominance of the workplace and details how the masterminds behind the PC are fighting back-with the even newer NetPC     

阿朗为桌面电话带来全新应用体验

日前,阿尔卡特朗讯宣布面向多种通信平台推出创新型"智能桌面电话"。阿尔卡特朗讯OmniTouch 8082 My ICPhone将整合至阿尔卡特朗讯OpenTouch系列通信平台中,并将在第二季度整合至面向酒店行业的阿尔卡特朗讯OmniPCXEnterprise平台中。按照计划,该产品将于第三季度整合至阿尔卡特朗讯OmniPCX Office平台。     

Competing for throughput in the local loop

The voice-grade telephone channel is the communication medium most widely available throughout the world. Its limitations, a relatively narrow bandwidth and a moderate SNR figure, have challenged telecommunication researchers and engineers over several decades to develop technologies able to pass higher and higher data rates. The sophisticated combination of trellis coding and quadrature amplitude modulation increases the bandwidth utilization close to the Shannon limit of 10 b/s/Hz for the 3.1 kHz bandwidth voice channel. However, the resultant data rate of about 30 kb/s does not even begin to approach the throughput needed by multimedia applications. Fortunately, twisted pair bandwidth reaches up to several megahertz, so multilevel signaling implemented as in the xDSF family of modems enables data rates of several megabits per second to be reached. Standard ADSL modems are able to deliver 8 Mb/s to a subscriber in the best case. VDSL modems can deliver 52 Mb/s, but only up to 300 m, so their mass implementation will only become possible when fiber migrates into an access network closer to the user premises. Both broadband xDSL solutions approach the Shannon limit and the related spectral efficiency as well, so there is not much room left for a transmission improvement     

台式电源的模块设计概念

现今，技术领先的电源公司在系统设计阶段就采用“模块设计方法”。某些医疗设备，包括数字和视频图像、数字Ｘ光机器、心电图监视器等都使用了模块电源设计概念。其优点在于加快面市时间，降低固定设备成本和降低电源单元的成本。     

用于色散补偿的非线性啁啾光纤光栅

提出了采用可调谐的非线性啁啾光纤光栅来补偿光通信系统中动态的非线性色散。分析了非线性啁啾光纤光栅的光谱及时延特性 ,并对其进行了数值仿真。设计了二类 PZT制作非啁啾光纤光栅的方案     

空时处理信号失真的一种补偿方法

在GPS抗干扰领域,联合空时处理相比单纯的时域或单纯的空域处理,可以有效的消除更多的干扰。但是由于空时处理包含有时间延迟线结构,因而会对期望信号相关函数的相关峰产生畸变,影响定位精度,有时甚至导致期望信号无法利用。本文利用确定性最小二乘逆滤波器对失真信号进行补偿。并推导出复序列参数下最小二乘逆滤波器解的形式。仿真结果表明,这种补偿方法可行、有效。     

Compensating combustion forces for automotive electromagnetic valves

Electromagnetic actuators show considerable promise in replacing camshafts in automotive combustion engines. Most research published to date focuses on reducing valve seating velocity. This is usually achieved using a current feed-forward controller during most of the valve travel and a trajectory controller with a fixed trajectory close to the end of travel. Such systems face considerable challenges in the presence of varying combustion forces, since the feed-forward strategy cannot ensure constant starting conditions for the tracking controller. The work shown here replaces the feed-forward controller with an energy based feedback controller. For the tracking controller with feedback linearization at the end of the valve travel, real-time trajectories that adapt to different starting conditions are derived. The algorithms can adapt to large changes in combustion pressure without relying on a priori combustion information. The algorithms are validated using simulations and on an experimental test bed.     

Test throughput for mixed-signal devices

People encounter mixed-signal system-on-a-chip (SOC) devices in our daily lives in a broad range of products. Consumer products like PDAs, automobiles, and appliances all contain microcontrollers, battery management, and power chips; these can be mixed-signal devices. They use broadband products such as set-top boxes, cable modems, DSL, and DVD players that contain mixed-signal devices. Wireless products, cordless phones, cellular phones, WLAN, Bluetooth, GPS receivers, and cable tuners also contain mixed-signal SOC devices. The content of the mixed-signal SOC device is characterized by different types of cores. They may be analog cores or digital cores. Many applications include mixed analog and digital cores such as digital-to-analog converters (DACs) and analog-to-digital converters (ADCs). These devices can provide complete system functionality on a single chip. One of the important principles to improving test economics is to ensure that test times are as low as possible. When testing, it is important that the test system is not adding overhead time. Beyond fast test software, the device-limited test speed is approached when tester operations execute in parallel with device operation. The architecture of the test system is key when approaching test times that are device limited. This can be achieved with a test system architecture that controls instrumentation precisely in device clock time. Mixed-signal device testing has adopted the use of DSP techniques to obtain a set of test measurements from large data sets. Each core within the device can produce data simultaneously. In the case of the device described earlier, there may be three video converters and five audio converters, all producing large amounts of data.     

Subnanosecond-jitter laser-triggered switching at moderate repetition rates

A 50-kV laser-triggered spark gap operated at repetition rates to 50 pps is described. Jitter of delay time as low as ± 0.1 ns was demonstrated. Dependence of delay and jitter was investigated as a function of gas mixture, pressure, laser power, and electrode material. Subnanosecond jitter was obtained with as little as 0.17 mJ in a 6-ns giant pulse from a Nd⁺³in a YAG laser. The dielectric gases used included a high proportion of Ar mixed with N2or SF6.     

消磁电源电磁干扰补偿技术

舰船临时线圈消磁是消除舰艇固定磁场，提高舰艇反磁探反磁性武器能力的重要措施。由于消磁工艺的特殊性，对于挂接于电网输出大功率电流脉冲的消磁电源有可能给电网造成极大的电磁污染，导致电网电压畸变。本文从探讨电网电压畸变的成因出发，着重研究了电压畸变的补偿问题，以期改善消磁电源的电磁兼容性能。     

一种求解目标内谐振时散射截面的有效方法

众所周知,在内谐振频率点上,用矩量法求解电场或磁场表面积分方程将得到不正确的表面电流。文中应用奇异值分解和正交化方法对由电场积分方程计算出的表面电流进行修正,从而得到目标表面上产生散射场的真实电流分布。文中计算了一无限长理想导体圆柱内谐振时的散射截面,所得结果与解析解一致,并对一无限长理想导体正方柱的后向散射截面进行了计算,结果表明本文方法是有效和准确的。     

Methods for Compensating for Variable Electrode Contact in EIT

Electrical impedance tomography (EIT) is an imaging modality that currently shows promise for the detection and characterization of breast cancer. A very significant problem in EIT imaging is the proper modeling of the interface between the body and the electrodes. We have found empirically that it is very difficult, in a clinical setting, to assure that all electrodes make satisfactory contact with the body. In addition, we have observed a capacitive effect at the skin/electrode boundary that is spatially heterogeneous. To compensate for these problems, we have developed a hybrid nonlinear–linear reconstruction algorithm using the complete electrode model in which we first estimate electrode surface impedances, by means of a Levenberg–Marquardt iterative optimization procedure with an analytically computed Jacobian matrix. We, subsequently, use a linearized algorithm to perform a 3-D reconstruction of perturbations in both contact impedances, and in the spatial distributions of conductivity and permittivity. Results show that, with this procedure, artifacts due to electrodes making poor contact can be greatly reduced. If the experimental apparatus physically applies voltages and measures currents, we show that it is preferable to compute the reconstruction with respect to the Dirichlet-to-Neumann map rather than the Neumann-to-Dirichlet map if there is a significant possibility that electrodes will be fully disconnected. Finally, we test our electrode compensation algorithms for a set of clinical data, showing that we can significantly improve the fit of our model to the measurements by allowing the electrode surface impedances to vary.      

基于云桌面的分布式堡垒研究

本文通过分析现有堡垒机的应用实践和技术瓶颈,提出了在云桌面环境下的分布式云堡垒技术,阐述了分布式云堡垒的原理、设计方法和实际效果.以解决现有堡垒机计算资源消耗过大,延时严重的应用问题,并增强访问过程控制能力,细化日志审计粒度,增强企业内控水平.     

Multi-channel input-queueing for high throughput switches

If input queued switches can be designed to maintain two or more separate queues per input line, with each queue associated with a subset of the output addresses, throughputs exceeding the well known limit of 58.6% due to head-of-line (HOL) blocking effects can be obtained. The switch complexity is only O(N), not O(N²) as in some recent proposals. The author proposes three switching rules and presents simulation results which indicate that all three do better than the performance of a familiar theoretical baseline model