基于粒子群优化的数字波束形成算法

波束形成的加权系数求解是一个优化过程,现有算法大多经过多次迭代,计算量大,实现复杂。为降低波束形成算法复杂度,将粒子群优化原理应用于数字波束形成中,提出了基于粒子群优化的自适应数字波束形成算法。该算法将每一组权值作为一个粒子,将阵列加权和的输出信号与干扰噪声比(SINR)作为适应度函数,通过比较各个粒子的适应度值,进行迭代搜索得到最优解。该算法可使天线阵在主波束对准有用信号,同时能有效抑制两个以上的干扰,且对阵列通道误差有较好的稳健性。计算机仿真验证了算法的有效性。     

多输入多输出雷达低旁瓣发射方向图优化算法

提出了一种基于波束域加权的低旁瓣方向图设计方法。综合考虑方向图匹配性能和发射阵元等功率作为约束条件,建立低旁瓣发射方向图优化模型,采用半正定松弛技术将优化模型转化为凸优化问题;对波束加权矩阵施加对偶约束,使得接收信号满足旋转不变性;利用高斯随机化方法对波束加权矩阵进行求解,得到原优化问题的最优解。仿真结果表明,算法能够保持期望主瓣形状并有效降低方向图旁瓣,提高到达角(DOA)的估计精确度和角度分辨力。     

基于扩展贝叶斯滤波的鲁棒波束成形

为提高信号源波达方向存在估计误差或不稳定时的波束成形器性能,提出了基于扩展贝叶斯滤波的鲁棒波束成形算法.将期望信号波达方向看成一组由若干离散样点组成的随机变量,对这些样点的后验概率进行估计并对后验概率低于门限值的样点进行重采样,在样点数有限的情况下获取期望信号附近样点的优化分布.通过对各样点最小方差无畸变响应(MVDR)权值的加权处理得到了优化的波束成形器权值.仿真结果表明,与典型的基于贝叶斯估计的鲁棒波束成形算法相比,文中算法能进一步提高波束成形器的鲁棒性.     

面向毫米波波束跟踪的扩展卡尔曼滤波算法研究

针对移动毫米波通信场景中收发波束存在角度偏差时接收信号质量急剧下降的问题,提出一种联合 迭代优化均方误差和扩展卡尔曼滤波(Extended Kalman Filtering,EKF)的稳健波束跟踪算法。该算法首先采用EKF算法对信道增益和波束角度进行跟踪,然后基于最小均方误差准则(Minimum Mean Square Error,MMSE)对误差进行 平滑处理,以消除EKF 线性近似引入的误差,实现对波束发射角和到达角的动态跟踪。仿真结果表明所提出的算法能够明显降低移动环境中的波束跟踪误差,并具有稳健的波束跟踪能力。     

接收多径相干信号的鲁棒自适应波束形成算法

为有效接收多径相干信号,该文提出一种基于波束主瓣幅度约束的鲁棒自适应波束形成算法。该算法充分利用多径相干信号的来波信息,对接收数据协方差矩阵统计量进行优化,并对多径相干信号波束主瓣进行幅度约束,通过一阶泰勒展开将多径相干信号的优化问题转换为迭代二阶锥规划问题,获得最佳波束形成权矢量。该算法不仅能够有效接收多径相干信号,抑制干扰和噪声,而且能够克服较大导向矢量失配误差,自由控制鲁棒响应区的波束宽度和纹波水平。仿真实验验证了算法的正确性和有效性。      

机载分布式智能蒙皮波束综合算法研究

针对机载智能蒙皮天线孔径共形和分布化的特点,开展了基于Broyden族算法的波束综合优化研究。算法以最小化副瓣电平为优化目标,通过K-S函数连续化处理,实现低副瓣波束赋形。通过不同的加权方式对算法的有效性进行了验证,相与遗传算法(genetic algorithm, GA)等随机优化算法,本文算法收敛速度快,能够避免陷入局部最优,适用于大规模非均匀共形天线阵列,具有较高的工程应用价值。     

QoS约束的协方差矩阵锥度波束成形算法分析

将服务质量(QoS)概念引入鲁棒波束成形分析中,根据下行链路移动用户接收SINR要求进行选择性地移动信号反馈、基站位置跟踪从而进行波达角(DOA)估计;通过协方差矩阵锥度(CMT)算法,在有限快拍输入数据采样条件下,保证了干扰及杂波信号能够得到有效地抑制。文中最后给出了相应的仿真结果。     

基于优化恒模算法的盲波束成形

提出一种基于优化恒模算法的盲波束成形,主要针对统计梯度恒模算法的收敛速度及收敛性能进行分析。采用最优步长策略,给出一般搜索方向下步长的最优值;通过对接收信号的空间分析,对权向量作信号子空间投影优化取值;采用准牛顿法的搜索方向,确保近似海色(Hession)矩阵的正定性。仿真结果表明,优化恒模算法的盲波束成形复杂度较低,收敛准确,收敛速度快和稳定性高。     

一种改进的基于特征空间自适应波束形成算法

在基于特征空间(ESB)自适应波束形成算法的基础上,本文提出一种更稳健的波束形成算法,该算法利用对阵列接收信号相关矩阵特征分解获得的信号子空间,对基于特征空间算法中的约束导向矢量进行校正,并完成波束形成.计算机仿真和分析证实了该算法性能要优于常规ESB算法的性能.     

模式空间矩阵重构波束形成算法研究

该文提出了一种均匀圆阵相干波束形成方法,这里称为模式空间矩阵重构(MODE-TOEP)波束形成算法。该算法在对均匀圆形阵列(UCA)的输出信号进行模式空间转换的此基础上,重新构一个特殊的Toeplitz矩阵,然后进行基于特征空间的波束形成,可以有效地抑制相干干扰。与模式空间平滑ESB算法相比,MODE-TOEP波束形成算法运算量小而且干扰抑制性能更好。计算机仿真表明MODE-TOEP波束形成算法的有效性和优越性。     

Using iterative learning control with basis functions to compensate medium deformation in a wide-format inkjet printer

The increase of paper size and production speed in wide-format inkjet printing systems is limited by significant in-plane deformation of the paper during printing. To increase both the production speed and paper size, the compensation of paper deformation is essential. A potential approach to compensate the paper deformation is actively changing the longitudinal paper position during a lateral pass of the printheads. This paper aims at developing an Iterative Learning Control (ILC) algorithm suited for this compensation strategy. The paper position is measured directly, but in non-real-time using image data obtained with a scanner located at the printheads. The proposed controller is experimentally validated and compared with standard norm-optimal ILC in a reproducible experiment, where a set of benchmark trajectories is used that represents severe paper deformation. The results show that in contrast to standard ILC, the ILC with basis functions achieves good tracking performance for the reference set and is hence a proper candidate algorithm for the compensation strategy.     

中日美移动电子邮件业务比较分析

美国的移动邮件业务是实用主义的商务产品，介绍其双向寻呼移动邮件“黑莓（Blackberry）”。日本的移动邮件是娱乐先锋的载体，它以娱乐为先兼顾商用，介绍了写真邮件（Sha-mail）成功的原因。中国的移动邮件是“彩信”及“彩e ”分别介绍了这两种产品的区别。最后分析了移动邮件的产品定位。     

A secure oblivious transfer protocol from indistinguishability obfuscation

This paper propose a new secure oblivious transfer protocol from indistinguishability obfuscation. The main technical tool in this paper is the candidate indistinguishability obfuscation introduced recently and a dual-mode cryptosystem.. Following their steps, a new k-out-of-l oblivious transfer protocol is presented here, and its realization from DDH is described in this paper, in which we combined indistinguishability obfuscation with the dual-mode cryptosystem. The security of our scheme mainly relies on the indistinguishability of the obf-branches(corresponding to the two modes in dual-mode model). Our paper explores a new way for the application of indistinguishability obfuscation.     

Control of the Reactive Power Supplied by a WECS Based on an Induction Generator Fed by a Matrix Converter

In this paper, a new control system to regulate the reactive power supplied by a variable-speed wind energy conversion system (WECS), based on an induction generator fed by a matrix converter (MC), is presented. The control system discussed in this paper is based on an input current observer, implemented using an estimation of the modulation matrix, and a nonlinear control loop that regulates the displacement angle at the MC input. The reactive power capability of the proposed system is also investigated. The work presented in this paper demonstrates that, for the proposed WECS, the maximum reactive power supplied to the grid is about 40% of the nominal value. Experimental results obtained from an experimental prototype are presented in this paper. The performance of the system using a wind turbine emulator and typical wind profiles is discussed in this paper.      

Power gain in feedback amplifiers, a classic revisited

A tutorial review of a classic paper by Samuel J. Mason (1954) is described. That paper contained the first definition of a unilateral power gain for a linear two-port and the first proof that this grain is invariant with respect to linear lossless reciprocal four-port embeddings, thereby making it useful as a figure of merit intrinsic to the device. In this work, that original paper is brought up to date, a tutorial exposition of its contents is presented in a modern form, and its significance and applications in microwave engineering are discussed. The subsequent advances in the subject area are summarized, so that the original paper can be placed within a broader context and understood with a more general perspective     

基于EDPSO算法实现智能组卷

组卷问题是一个多重约束的组合优化问题,目前已有多种组卷策略、组卷算法都从某一方面或某几方面对智能组卷系统进行了改进和研究,并取得了一定的进展,文中基于分布估计离散粒子群算法进行了组卷.     

In‐Plane Micro‐Supercapacitors for an Integrated Device on One Piece of Paper

Portable and wearable sensors have attracted considerable attention in the healthcare field because they can be worn or implanted into a human body to monitor environmental information. However, sensors cannot work independently and require power. Flexible in‐plane micro‐supercapacitor (MSC) is a suitable power device that can be integrated with sensors on a single chip. Meanwhile, paper is an ideal flexible substrate because it is cheap and disposable and has a porous and rough surface that enhances interface adhesion with electronic devices. In this study, a new strategy to integrate MSCs, which have excellent electrochemical and mechanical performances, with sensors on a single piece of paper is proposed. The integration is achieved by printing Ni circuit on paper without using a precoating underlay. Ink diffusion is also addressed to some degree. Meanwhile, a UV sensor is integrated on a single paper, and the as‐integrated device shows good sensing and self‐powering capabilities. MSCs can also be integrated with a gas sensor on one‐piece paper and can be charged by connecting it to a solar cell. Thus, it is potentially feasible that a flexible paper can be used for integrating MSCs with solar cell and various sensors to generate, store, and use energy.     

Full Sheet Control Using Steerable Nips

This paper describes the mechatronics design, prototype testing, and control of a steerable nips component for paper path mechanisms in high-speed color printers and photocopiers. When placed upstream from the image transfer station along the paper path, this device precisely controls the longitudinal, lateral, and skew directions of papers sheets, as they arrive to the image transfer station. The paper also presents a complete kinematic and dynamic analysis of the paper sheet steering mechanism, which is validated by experimental results. It is shown that the dynamics of a sheet under the control of the steerable nips mechanism are nonlinear and subject to nonholonomic constraints. A feedback linearization control strategy that includes dynamic surface control is developed and implemented to control the sheet's position and angular orientation under the condition that the sheet's speed in the longitudinal direction remains positive at all times. Experimental results verify that the steerable nips mechanism under the proposed feedback linearization control strategy is able to meet or exceed all design performance requirements for deployment as a component of an actual printer paper path control mechanism.      

A Novel Sensor Node Deployment using Low Discrepancy Sequences for WSN

The foremost challenge in designing Wireless Sensor Networks (WSNs) is careful node placement. Sensor Node placement is a one of the powerful optimization technique for accomplishing the anticipated goals. This paper focuses on categories of node deployment in WSN. The paper highlights various problems and identifies the different objectives in sensor node deployment. The paper proposes a novel node deployment strategy based on Quasi- random method of low-discrepancy sequences to increase the lifetime and the coverage of the network. The aim of the paper is to study how the node deployment affects the different QoS parameters such as packet delivery ratio, average energy consumption, delay, etc. with various multi-objective routing algorithms WSN. To validate the proposal simulation, results are presented in this paper. The paper concludes with the future outlook.