Coherence-based performance analysis of the generalized orthogonal matching pursuit algorithm

The performance guarantees of generalized orthogonal matching pursuit( gOMP) are considered in the framework of mutual coherence. The gOMP algorithmis an extension of the well-known OMP greed algorithmfor compressed sensing. It identifies multiple N indices per iteration to reconstruct sparse signals.The gOMP with N≥2 can perfectly reconstruct any K-sparse signals frommeasurement y = Φx if K 1/N(1/μ-1) +1,where μ is coherence parameter of measurement matrix Φ. Furthermore,the performance of the gOMP in the case of y = Φx + e with bounded noise ‖e‖2≤ε is analyzed and the sufficient condition ensuring identification of correct indices of sparse signals via the gOMP is derived,i. e.,K 1/N(1/μ-1)+1-(2ε/Nμxmin) ,where x min denotes the minimummagnitude of the nonzero elements of x. Similarly,the sufficient condition in the case of G aussian noise is also given.     

Electroencephalogram characters of parallax stereo watching asthenopia

The electroencephalogram(EEG)characters value of observers can be deduced by collecting brain electrical information when the observers are watching parallax stereo video.The characters value will change clearly when watching asthenopia appear.To investigate the characters of parallax stereo watching asthenopia,the EEG of observers were recorded through the whole watching process of parallax stereo films until watching asthenopia appeared.The recorded EEG data of observers belongs to time-domain information.Fourier transform can process these data to frequency spectrum information.Theαandβwaves average power can be got by Newton-Cotes equation from the information.The ratio ofβpower to the sum ofαandβpower,CV,can be defined as EEG characters value of parallax stereo watching asthenopia and used to estimate the asthenopia degree of observers.Our experiments show that the smaller the CVis,the more serious the asthenopia is.     

Nonlinear symbolic LFT model for UAV

A nonlinear modeling framework is presented for an oceanographic unmanned aerial vehicle(UAV)by using symbolic modeling and linear fractional transformation(LFT)techniques.Consequently,an exact nonlinear symbolic LFT model of the UAV is derived in a standard M-Δform where M represents the nominal,known,part of the system andΔcontains the time-varying,uncertain and nonlinear components.The advantages of the proposed modeling approach are that:it not only provides an ideal starting point to obtain various final design-oriented models through subsequent assumptions and simplifications,but also it facilitates the control system analysis with models of different levels of fidelity/complexity.Furthermore,a linearized symbolic LFT model of the UAV is proposed based on the LFT differentiation,which is amenable directly to a sophisticated linear robust control strategy such asμsynthesis/analysis.Both of the derived LFT models are validated with the original nonlinear model in time domain.Simulation results show the effectiveness of the proposed algorithm.     

Thermal efficiency characteristics of hydrogen internal combustion engine

To study the economic advantages of hydrogen internal combustion engine,an experimental study was carried out using a 2.0Lport fuel-injected(PFI)hydrogen internal combustion engine.Influences of fuel-air equivalence ratioΦ,speed,and ignition advance angle on heat efficiency were determined.Test results showed that indicated thermal efficiency(ITE)firstly increased with fuel-air equivalence ratio,achieved the maximum value of 40.4%(Φ=0.3),and then decreased whenΦ was more than 0.3.ITE increased as speed rises.Mechanical efficiency increased as fuel-air equivalence ratio increased,whereas mechanical efficiency decreased as speed increased,with maximum mechanical efficiency reaching 90%.Brake thermal efficiency(BTE)was influenced by ITE and mechanical efficiency,at the maximum value of 35%(Φ=0.5,2 000r/min).The optimal ignition advance angle of each condition resulting in the maximum BTE was also studied.With increasing fuel-air equivalence ratio,the optimal ignition angle became closer to the top dead center(TDC).The test results and the conclusions exhibited a guiding role on hydrogen internal combustion engine optimization.     

坝基岩体岩石质量指标、波速和透水率的关系——以青海玛沁地区玛尔挡水电站为例

坝基岩体质量分级指标包括岩石质量指标(RQD,Q)、纵波波速(V)以及透水率(ω)等。他们相互之间存在一定关系,并随深度(h)的变化而变化。以青海玛沁地区玛尔挡水电站河床坝基6个钻孔的实测数据为基础,对上述指标随深度的变化规律及相互关系进行研究。结果表明:同一深度的岩石质量指标差异较大,但整体上随深度的增加呈线性带状增大,上、下限的线性关系分别为Q=0.488h+67.886与Q=0.309h+2.319;透水率与深度具有较好的相关性,随深度增大,透水率呈幂函数曲线下降趋势,即ω=1 329.192h^-1.599;岩石质量指标、透水率和深度的拟合度较高;随着岩石质量指标的增加,纵波波速整体上呈线性带状增大的趋势,上、下限的线性关系分别为V＝40.493Q+3 612.9和V＝32.458Q+1 822.6,而透水率的几何平均值呈下降趋势,与岩石质量指标的算术平均值具有很好的相关性,即ω=6.378-3.708×10^-7Q^3.832。     

滇西腾冲地块勐连花岗岩及暗色包体锆石U-Pb年龄、地球化学和Sr-Nd-Pb同位素特征

滇西腾冲地块是东特提斯构造带的重要组成部分,广泛发育中生代和新生代岩浆作用。出露于腾冲地块东南部的勐连花岗岩及暗色包体的锆石U-Pb定年显示,勐连花岗岩形成时代为(127±2)Ma,暗色包体为(125±2)Ma。勐连花岗岩主要岩石类型为石英二长岩、花岗闪长岩和黑云母二长花岗岩,属于高钾钙碱性Ⅰ型花岗岩,兼具部分S型花岗岩的过铝质特征。虽然暗色包体与花岗岩形成时代基本一致,但是暗色包体的矿物粒度更小,稀土元素总质量分数((305.2～322.8)×10^-6)更高,同时具有较高的w(Nb)/w(Ta)值(18.2～19.5)、较低的Pb同位素组成和更亏损的ε_Nd(t)值,表明勐连花岗岩内暗色包体应为异源包体,可能是基性岩浆侵入酸性岩浆中淬冷的产物。勐连花岗岩的全岩Sr-Nd同位素随SiO₂并没有明显的变化趋势,暗示地壳物质混染作用并不显著。Ba-Sr图解显示勐连花岗岩主要经历了斜长石和钾长石的分离结晶过程。二阶段Nd模式年龄(1.37～1.58 Ga)和上地壳类似的Pb同位素组成暗示中元古代高黎贡山群是勐连花岗岩的主要物质源区。但与高黎贡山花岗岩相比,更亏损的ε_Nd(t)值暗示勐连花岗岩源区中存在亏损地幔物质的加入。整体上,全岩初始N(⁸⁷Sr)/N(⁸⁶Sr)值(0.710 020～0.712 001)和ε_Nd(t)值(-4.6~-2.1)暗示勐连花岗岩与拉萨地块北部岩浆带具有类似的形成环境。结合岛弧特征的构造环境和高w(Nb)/w(Ta)值的异源暗色包体,认为勐连花岗岩及暗色包体的形成可能是中特提斯洋俯冲-碰撞-闭合过程的产物。     

鞍山—本溪地区前寒武纪条带状铁建造铁矿时代、物质来源与形成环境

前寒武纪条带状铁建造(BIFs)蕴含丰富的铁矿石资源,记录了早期地球演化的重要信息。鞍山—本溪地区发育巨量的太古宙BIFs。鞍山—本溪地区BIFs由互层的硅铁条带组成,金属矿物以磁铁矿为主,含少量赤铁矿、黄铁矿及菱铁矿等。围岩与BIFs呈整合接触,具有变火山岩的岩石学特征及地球化学特征,表明BIFs属于阿尔戈玛型,其变火山岩围岩年龄可大致代表BIFs沉积时代。锆石U-Pb年代学显示,鞍山—本溪地区至少发育约3.10Ga及约2.55Ga两期BIFs沉积成矿事件,后者在华北克拉通广泛发育.鞍山—本溪地区BIFs地球化学具有以下特征:①低的TiO₂与Al₂O₃含量及高场强元素负异常,表明沉积过程中陆源碎屑物质加入量很少;②PAAS标准化REE配分模式显示重稀土元素富集,La、Y 及Eu正异常,暗示BIFs沉积自海水与海底高温热液的混合溶液;③接近同时代亏损地幔的ε_Nd(t)值(3.0~4.7),表明Fe可能来源于海底热液活动淋滤洋壳;④BIFs中仅发育少量黄铁矿,基本不显示Ce负异常且富集铁的重同位素(δ(⁵⁷Fe)值为(0.13~2.73)×10^-3),暗示古海洋整体处于低硫、缺氧环境,BIFs的沉淀可能与富Fe²⁺溶液遭遇环境突变有关。元素地球化学分析表明,大孤山与陈台沟围岩具有弧火山岩特征,南芬与歪头山围岩类似于弧后盆地玄武岩,因此,鞍山—本溪地区BIFs沉积于火山弧相关构造背景。     

Diversity of supramolecular architecture of H2 salpn coordination compounds based on its flexibility

Two complexes,[Cu（salpn） ]·NH（ CH₃）₂（ 1） and [Ni（ salpn）·H₂O]（ 2）（ H₂salpn= N,N-bis（ salicylidene）-propane-1,3-diamine） were characterized by IR,element analysis and single crystal X-ray diffraction analysis. Crystal data for complex 1 : monoclinic,P2₁/ C,a = 1.0974 × 10^-7cm,b = 1.4806 × 10^-7cm,c = 1.0315 × 10^-7cm,β = 94.43（ 3） °. The Cu（ II）ion in complex 1 is four coordinated with distorted square planar coordination geometry. The crystal structure of complex 1 consists of [Cu（ salpn） ] coordination complex and a guest molecule NH（ CH₃）₂that can act as both H-bonding donor and acceptor and plays an important role in constructing supramolecular architecture. Crystal structure data for complex 2 : orthorhombic,Pnma,a = 8.6763× 10^-8cm,b = 2.4145 × 10^-7cm,c = 7.5388 × 10^-8cm. The Ni（ II） ion in complex 2 is fivecoordinated with a butterfly coordination geometry. The coordinated water molecule plays a key role in hydrogen-bonded networks.     

内蒙古巴林右旗晚侏罗世巴彦琥硕花岗岩地球化学特征、锆石U-Pb年龄及Hf同位素组成

巴彦琥硕花岗岩采自内蒙古巴林右旗北部,其主要岩性为中细粒花岗岩、细粒二长花岗岩。通过地球化学、锆石U-Pb定年及Hf同位素分析研究,探讨巴彦琥硕花岗岩成因及其地质意义。锆石U-Pb年代学研究结果表明,巴彦琥硕花岗岩锆石U-Pb年龄为150 Ma,形成于晚侏罗世。岩石学和地球化学研究表明:SiO₂质量分数不低于71.3%,Al₂O₃不低于12.15%,w(K₂O)+w(Na₂O)值为7.74%~8.29%,w(K₂O)/w(Na₂O)值为0.88~1.57,Sr质量分数为(61.7~197.5)×10^-6,Y为(17.3~33.2)×10^-6,w(Sr)/w(Y)值低,为1.77~3.56,巴彦琥硕花岗岩属低锶高钇型岩石;岩石轻、重稀土元素分馏明显,w(La)_N/w(Yb)_N值为3.06~10.89,显示出明显的Eu负异常。锆石Hf同位素分析显示ε_Hf(t)值介于6.1~12.3之间,显示源区亏损的特征。考虑到侏罗世—白垩世期间太平洋板块对中国东部边缘的俯冲作用,巴林右旗北部晚侏罗世巴彦琥硕花岗岩的形成受太平洋板块俯冲作用影响,形成于挤压向伸展体制转换的过渡期。     

面向入侵检测的Aho-Corasick算法内存消耗研究

多模式匹配算法在网络入侵检测系统中有着广泛的应用,目前的研究主要集中在如何提高算法的匹配速度上,对于算法的内存消耗研究较少。对于基于硬件实现的嵌入式入侵检测而言,如何降低多模式匹配算法的内存消耗也是一个值得关注的问题。Aho-Corasick(AC)算法是一个基于有限状态机的多模式匹配算法,该算法具有O(n)的时间复杂度,但是由于状态表存储开销较大使其难以应用到嵌入式入侵检测系统中。对AC算法的内存消耗进行了深入地研究,分析了几种可行的AC有限状态机存储策略,提出了一种改进的Banded-Row格式的AC有限状态机存储策略。实验结果表明,该策略能够在较小地影响AC算法匹配速度的前提下,更加有效地降低其内存消耗。     

相关准循环码字集方法攻击McEliece密码体制

Focusing on the security of McEliece public key cryptosystem based on the QC-LDPC code, a new attack algorithm based on the correlative quasi-cyclic(QC) code word is proposed. As the code word in the QC code set is shifted cyclically which is equivalent to information retransmission, the algorithm's effect is better. Performance is analyzed from probability of the correct decipher and computational complexity. Simulation results show that the proposed algorithm possesses a higher probability of the correct decipher (0.999) and a lower work factor (2^40.7).     

用于电源/地网络分析的随机行走算法改进

为了克服用于芯片上电源/地(P/G)网络分析的一般随机行走算法在求解整个网络时效率比较低下、求解时间与理想电压源节点(VDD)所占比例成反比变化，以及求解wire-bond类型的P/G网络时运算时间与网络规模呈超线性复杂度等缺点，提出了一种改进的随机行走算法.该算法充分利用一次行走所获得的信息，将节点的一次行走分解为所经过节点的若干次随机行走，每到达一个未知电压值节点等效为该节点一次随机行走的开始.仿真结果表明，在可以忽略的误差范围内，改进后算法的求解速度比一般随机行走算法求解速度要快十多倍，求解时间不随VDD所占比例而变化，且对于wire-bond类型的P/G网络具有线性时间复杂度.     

关于AOE网中关键路径求解算法的研究

介绍AOE网中关键路径的相关概念,通过算法描述和实例,探讨基于拓扑排序求解、P矩阵的求解和广度优先搜索遍历（BFS）方法三种算法,求解AOE网中关键路径的实现过程,并进一步从算法的时间复杂度、数据结构形式及实现的容易程度等几方面分析三种求关键路径算法的优劣。     

西天山阿吾拉勒东南部晚石炭世—中二叠世中酸性小岩体成因及地质意义

西天山阿吾拉勒东南部艾肯达坂花岗岩和2752高地闪长玢岩浅成小岩体侵入于石炭系火山 沉积岩中,岩石无变形,呈均一块状,具斑状/似斑状结构,属准铝质到弱过铝质高钾钙碱性花岗岩类,富集Rb、Th、U、K和Pb等大离子亲石元素,贫Zr、Hf等高场强元素,显示中等到弱的负Eu异常,亏损Nb、Ta、P、Ti和Sr等元素,具壳源岛弧区岩浆作用的地球化学特征。这两个岩体锆石均为正ε_Hf(t)值和新元古代Hf陆壳模式年龄,指示其主要源自新元古代陆壳物质的部分熔融,个别锆石ε_Hf(t)值明显高表明岩体形成过程还有幔源岩浆物质的加入。LA-ICP-MS锆石U-Pb定年分别获得2752高地闪长玢岩307 Ma和艾肯达坂花岗岩282 Ma的形成年龄,与区域上同期小岩体一同对应于西天山大规模壳-幔花岗岩浆活动末期,证明在晚石炭世—中二叠世期间,伴随着西天山大规模花岗岩浆活动的减弱,出现一期重要的小规模中酸性岩浆活动。综合分析西天山晩石炭世—中二叠世各类岩浆作用,该时期中酸性小岩体为后碰撞向陆内伸展拉张过渡阶段岩浆活动的产物,指示西天山晚石炭世晚期深部动力学背景和构造环境发生了重要转折。     

增强型Quine-McCluskey算法及其实验

传统的Quine-McCluskey算法第一步多从只拥有最小项的真值表开始,而真值表中的最小项数目是算法时间复杂度的最重要因素,数目越大,算法完成需要的时间越多.采用增强Quine-McCluskey算法,对真值表大小进行控制,利用更多归约规则,从而减少算法执行时间.     

Recurrent formula of Bernoulli numbers and the relationships among the coefficients of beam, Bernoulli numbers and Euler numbers

Based on the differential equation of the deflection curve for the beam,the equation of the deflection curve for the simple beamis obtained by integral. The equation of the deflection curve for the simple beamcarrying the linear load is generalized,and then it is expanded into the corresponding Fourier series.With the obtained summation results of the infinite series,it is found that they are related to Bernoulli num-bers and π. The recurrent formula of Bernoulli numbers is presented. The relationships among the coefficients of the beam,Bernoulli numbers and Euler numbers are found,and the relative mathematical formulas are presented.     

并行E／T的一个工程算法

并行加工系统是典型的生产环境,以用Ｅ／Ｔ为目标的并行加工系统调度具有ＮＰ完备性。本文基于局部－整体较优来分析目标函数,提出一种启发式算法,该算法具有操作简单,主要是矩阵计算和数值排序,复杂性低,能达到一定的优化水平,易于计算机实现的特点,适合工程实用。     

基于遗传算法的3-SAT问题判定

通过对遗传算法的改进,引入了聚类排序选择算子,将一个3-SAT的判定性问题转换成一个3-SAT的验证性问题,同时加快了算法的收敛程度,最后给出了基本的求解算法,并分析了该算法的复杂性．实验数据表明,该算法的可靠性有较大地提高,性能明显优于其他同类算法．     

四川泸定地区新元古代火山岩地球化学特征及其大陆动力学意义

四川泸定地区火山岩属于扬子地块西缘岩浆岩带,是“康滇地轴”北段的重要组成部分,出露在现今龙门山断裂带与鲜水河断裂带的交汇部位。该火山岩形成年龄为(772.4±5.5)Ma,属于新元古代火山岩。岩石SiO₂质量分数介于59.18％～72.44％,为一套典型的岩浆弧成因亚碱性高钾钙碱系列安山岩-英安岩-流纹岩组合。岩石微量及稀土元素具典型的岛弧火山岩特征,Nb和Ta强烈亏损,w(Nb)/w(Th)值为0.72～1.77,w(La)/w(Nb)值为3.12～7.36,w(Ta)/w(Yb)值为0.13～0.29,w(Th)/w(Yb)值为1.06～5.21,明显不同于大陆裂谷型火山岩组合以及与地幔柱相关的火山岩组合。岩石N(⁸⁷Sr)/N(⁸⁶Sr)值为0.737 169～0.743 441,N(¹⁴³Nd)/N(¹⁴⁴Nd)值为0.512 091～0.512 549,N(²⁰⁶Pb)/N(²⁰⁴Pb)值为18.670 1～18.882 3,N(²⁰⁷Pb)/N(²⁰⁴Pb) 值为15.663 3～15.677 4,N(²⁰⁸Pb)/N(²⁰⁴Pb) 值为38.717 2～39.177 4,ε_Nd(t)值为-2.76～6.00,这充分表明在新元古代时期本区的构造背景为岛弧系统。由俯冲作用导致的地幔物质上涌,引起大陆边缘弧地壳熔融,形成了泸定地区这套陆缘弧中酸性火山岩组合。     

西天山备战铁矿石炭纪火山岩地球化学特征及岩石成因

选取西天山阿吾拉勒东段备战铁矿区出露的石炭纪火山岩为研究对象。通过对岩相学与主量、微量元素地球化学等方面的研究来约束其构造环境与岩浆源区性质。分析测试显示该地区火山岩多属中高钾钙碱性及橄榄玄粗岩系列,富集轻稀土元素及大离子亲石元素(Rb、Th、K等),亏损高场强元素(Nb、Ta、Ti等)。岩石组合及地球化学特征表明:该地区火山岩形成于活动大陆弧环境,其形成与早石炭世末期北天山洋盆向位于其南部的伊犁地块之下发生B型俯冲作用有关。另外,火山岩ε_Nd(t)值介于0.73~4.33之间,显示岩浆源区具亏损地幔的属性,且母岩浆在演化过程中还经历有结晶分异作用以及陆壳物质混染作用。