Partially symmetrical derivative-free Liu–Storey projection method for convex constrained equations

ABSTRACT

Applying Powell symmetrical technique to the Liu–Storey conjugate gradient method, a partially symmetrical Liu–Storey conjugate gradient method is proposed and extended to solve nonlinear monotone equations with convex constraints, which satisfies the sufficient descent condition without any line search. By using some line searches, the global convergence is proved merely by assuming that the equations are Lipschitz continuous. Moreover, we prove the R-linear convergence rate of the proposed method with an additional assumption. Finally, compared with one existing method, the performance of the proposed method is showed by some numerical experiments on the given test problems.     

普通筋对称配置的部分预应力混凝土梁正截面强度计算

从部分预应力混凝土受弯构件轴力和弯矩的基本平衡条件出发 ,通过理论推导 ,给出了非预应力筋对称配置的部分预应力混凝土梁正截面强度的设计计算公式和设计步骤 ,并给出了设计算例     

Source localization based on symmetrical MUSIC and its statistical performance analysis

In this paper,a new method for fast direction-of-arrival(DOA) estimation with no dependance on array configurations is proposed,which is referred to as the symmetrical multiple signal classification(SMUSIC).Unlike the standard MUSIC,the S-MUSIC spatial spectrum is constructed by the intersection of the noise subspace and the conjugate noise subspace,and it hence generates spectral peaks at the true DOAs and the symmetrical virtual DOAs simultaneously.Such a characteristic allows fast DOA estimation by spectral search over only half of the total angular filed-of-view.Therefore,the new approach has a much lower computational complexity than the standard MUSIC.The statistical performance of S-MUSIC is studied and a close-form expression for the MSEs(mean square errors) of DOA estimation by the proposed estimator is derived.Numerical simulations are conducted to demonstrate the effectiveness of the new algorithm and to verify the theoretical analysis,and it is indicated that S-MUSIC makes a trade-off between MSEs and lower computational complexity as well as an improved resolution for closely-spaced sources as compared to the standard MUSIC.     

基于核对称散布矩阵空间的特征抽取方法

为解决传统Fisher鉴别分析方法中非线性小样本的特征抽取问题,从核线性子空间角度出发,构造一种矩阵变换,得到核空间中类内散布矩阵的另一个对称核子空间,通过对2个核子空间分别求解,从而得到样本的有效鉴别信息。在NUST603和ORL人脸数据库上的实验结果验证了该算法的有效性。     

浅析分组密码分析方法的关联性分析

自从差分分析和线性分析相继被提出以后,许多基于其之上的分析方法陆续出现,各式各样的分析方法通常利用了自算法中所提取的数据的不均匀性来获取密钥的信息。人们在利用这些分析方法对分组密码的安全性进行评估时,经常会发现一些相似的现象,如：某两种区分器的轮数总是相同、两种统计分析方法中所利用的统计量存在数学关系等。所以,在建立新的分析方法的同时,人们渐渐将关注点转移到研究各种已有的分析方法的关联性上。尽管在处理和分析方式有着形式上的不同,但经过仔细分析之后发现许多看似不同的分析方法之间有着一些关联性,研究这种关联性不管是从理论上还是从分析分组密码安全性的角度都是非常有必要的。近几年,各种分析方法之间的关联性逐渐被建立起来。这些关联性的建立一方面有助于我们对已知的分组密码分析方法进行分类,另一方面这些关联性可能会给出分组密码安全性的补充信息。本文中简要介绍了一些已有的分析方法,并总结了已有的分析方法之间的关联性。     

高速串行数据传输链路中固定延时设计

在高能物理实验中,由于需要预测数据传输时间,触发器和高速数据传输系统需要具有固定延时的串行链路.然而,当前嵌入在最新一代可编程逻辑门阵列(FPGA)中的高速收发器通常是不带固定延时能力的.给出了基于LOCic编解码器的固定延时传输设计.讨论了LOCic解码器中帧头位置鉴别寄存器与数据串行传输相位延时间的关系.实验和测试结果表明给出的固定延时设计简单,可靠可行.     

基于改进的单通道对称正交化FastICA的间谐波检测方法

针对电力系统中间谐波检测的问题,提出一种基于改进的单通道对称正交化FastICA的间谐波估算算法.该算法首先对单通道电力系统混合信号进行循环平移,构造出多道观测信号,通过主成分分析法对其进行降维处理;其次利用改进的对称正交化FastICA算法对多个独立成分并行估计,分离出基波、谐波和间谐波信号频率;最后应用最小二乘法对谐波和间谐波幅值和相位进行估计.仿真结果表明,该方法可以较准确地检测出各次谐波和间谐波的频率、幅值和相位,较之FastICA算法,该算法不需任何先验知识,收敛速度快,检测精度高.     

An efficient dual‐band rectenna using symmetrical rectifying circuit and slotted monopole antenna array

In this article, an efficient dual‐band rectenna making use of the newly proposed symmetrical rectifying circuit working at the frequency of 1.8 and 2.45 GHz, is proposed. The proposed dual‐band rectifying circuit is combined with an array of compact wideband planar monopole modified circular slot antenna in order to facilitate the efficient rectenna design. The rectifying circuit employs symmetrical matching network in addition to the symmetrical rectifier thereby facilitating the suppression of the odd order harmonics. This eventually results into the higher output voltage as compared to the conventional rectifier circuits. Moreover, the dual‐band topology of the proposed rectenna increases the overall voltage by harvesting energy from two independent RF sources. The measured results of the fabricated structure show that the maximum RF to dc conversion efficiency of the proposed rectifier circuit reaches up to 70% at 9 dBm input RF power. From application point of view, the proposed rectenna circuit is tested to extract the RF energy from 1.8 GHz cellular and 2.45 GHz Wi‐Fi bands to energize a low‐power LED. The overall rectenna structure is reasonably compact providing good performance, which can potentially be employed for efficient wireless power transmission system.     

建立切除对称“U”型切屑条件的插削工艺方案

分析了传统插削加工的切屑形状与插齿刀磨损的原因,提出通过程序控制附加角位移,建立切除对称"U"型切屑的条件,利用控制切屑形状来减小插齿刀磨损、提高刀具使用寿命,详细阐述了该方法的工作原理和工艺方案。     

Efficient heuristics for energy-aware routing in networks with bundled links

Current networks are typically over-provisioned to ensure low delays, redundancy and reliability. These Quality of Service (QoS) guarantees are typically achieved using high end, high power network equipments. Their use, however, has led to concerns regarding green house gas emissions, which garnered a lot of attention recently and have resulted in a number of global initiatives aim at reducing the carbon footprint of Internet Service Providers (ISPs). These initiatives have motivated ISPs and researchers to design novel network algorithms and hardware that scale the usage or active time of a network according to traffic load. To this end, this paper considers the problem of shutting down a subset of bundled links during off-peak periods in order to minimize energy expenditure. Unfortunately, identifying the cables that minimize this objective is an NP-complete problem. Henceforth, we propose several practical heuristics based on Dijkstra’s algorithm and Yen’s k-shortest paths algorithm. We evaluated our heuristics on the Abilene network – with both real and synthetic traffic matrices and several larger random topologies with various loads. Our results show that the proposed heuristics to be effective and efficient. Moreover, our approaches could potentially reduce the energy usage of cables used in the Abilene network by up to 56.7%, assuming the traffic demands recorded on September 5, 2004.