微波效应实验最小样本量估计分析

 为规范微波效应实验最小样本量,采用区间估计的统计推断方法,开展了样本作用概率与总体作用概率对应关系的分析和研究工作,对满足一定置信度和一定总体作用概率下所需要的最小样本量进行估计。研究结果表明,实验最小样本量确定为10是较为合理的。在80％的置信度下,当10支样本量样本作用概率达到70％时,总体作用概率置信下限约为51.6％。通过该方法能够将所获取的微波效应数据通过同一指标“总体作用概率置信下限”进行有效整理。     

物理实验数据处理中的一些问题的探讨

针对当前大学物理实验教学中关于数据处理的一些问题进行了探讨。提出了测量值与测量结果这两个词的不同。对于有效数字位数的保留进行了系统性的分析。指出了数据修约中所存在的一些不恰当之处。认为实验教学中宜考虑测量次数对实验结果的影响。简述了置信概率、概率型式、标准不确定度及扩展不确定度等问题的相互联系。     

参数估计的置信密度方法

在分析参数估计的贝叶斯验后密度方法和非贝叶斯置信区间方法的基础上,由置信区间引出置信密度的概念和计算公式.置信密度分布是非贝叶斯参数估计结果的完整描述,它有明确的概率意义.以推断荷电粒子质量为例说明置信密度在高能物理实验数据处理中的应用.     

基于光谱与空间特征结合的改进高光谱数据分类算法

针对仅利用光谱信息进行分类未充分利用高光谱数据图谱合一特性的问题,提出了基于马尔可夫随机场的改进分类模型,利用基于最大后验概率的马尔科夫随机场模型进行光谱与空间信息的融合应用,采用基于光谱信息的概率支持向量机方法提高马尔科夫随机场模型中光谱能量函数项的类条件概率估计精度,设计基于信息传播策略、信息更新策略、多尺度传播策略的多重加速策略的高效置信传播优化算法,解决了马尔科夫随机场模型中全局能量最小化优化过程中计算复杂度高、计算耗时等问题。利用航空可见-近红外成像光谱仪AVIRIS对美国印第安纳州西北部的农业示范区数据进行应用分析,并与迭代条件模型、模拟退火、置信传播等方法进行性能比较,试验结果表明：该方法能够达到总体分类精度95.78%、Kappa系数0.933 4,优于现有马尔科夫随机场分类算法,并且计算效率比置信传播优化算法提高了3倍以上。     

舰炮武器系统光电传感器与雷达数据融合及应用

目标参数的质量直接影响武器系统的命中概率,因此,光电、雷达传感器数据的选优尤为重要,数据融合解决了这一问题。针对舰炮武器系统雷达及光电传感器的数据融合,建立了数学模型,并根据所建立的模型提出工程实践,提高了武器系统的命中率。     

随机误差条件下置信区间与置信概率的函数关系

通过对随机误差分布规律的理论分析,利用数理统计和数值计算方法,得到了置信区间与置信概率的函数关系,给出了实用的计算数据。     

用等偏法与Spss研究灵敏电流计的特性

针对测试灵敏电流计特性的实验装置,以灵敏电流计的灵敏度及内阻为研究对象,用等偏法测量实验数据,引入Spss的曲线估计功能分析实验数据,得到电阻复合量与电阻比、光标偏转格数、电压的综合量的定标曲线,并验证出复合量与综合量具存在线性关系,由此标出灵敏电流计的灵敏度及内阻,用置信概率为95%的不确定度,对测量数据和实验结果进行分析和评价,最终得到更为可靠合理的实验结果。     

ADS-B时间延迟对ADS-B/WAM数据关联的影响研究

针对广播式自动相关监视(ADS-B)报文的时间延迟对ADS-B/广域多点相关(WAM)数据关联跟踪精度的影响问题,在ADS-B时间延迟条件下对最近邻数据关联(NNDA)和概率数据关联(PDA)两种经典的数据关联方法的跟踪性能进行比较分析。采用MATLAB仿真计算存在ADS-B时间延迟时,ADS-B报告位置与跟踪预测值的平均马氏距离及关联结果的位置误差均方根,对比两种数据关联方法在上述两个统计平均值的关系。分析结果表明：存在ADS-B时间延迟时,PDA方法在跟踪误差和稳健性上优于NNDA方法,同时ADS-B时间延迟会增加跟踪测量误差。     

囚禁单离子的量子阻尼运动

用包含偶极和四极虚势能项的非厄米哈密顿算符来描述Paul阱中囚禁阻尼单离子在静电场下的量子运动.通过导出和分析系统的精确解,得到在PT对称和不对称情形下的不同实能谱与稳定量子态,以及PT不对称情形的虚能谱和衰减量子态,同时给出相应于不同态的参数区域和存活概率.结果发现该非厄米系统外场参数能惟一确定量子稳定态并导致波函数形态变化,据此提出非相干操控相应量子跃迁的方法.让量子态衰减导致的离子位置期待值的衰减与经典阻尼谐振子的衰减一致,得到虚势能参数与经典阻尼参数的对应关系.所得结果将进一步丰富具有广泛应用背景的囚禁离子动力学.     

基于数据融合的风电机组噪声预测

根据风电机组噪声信号检测复杂的情况,研究风电机组非声学参数的信息熵特征,对机组噪声进行多源数据融合预测。分析基于信息熵的非声学参数的特征提取方法,并对传统的基于遗传算法的支持向量机回归(GA-SVR)的缺陷提出改进,结合实际应用的非声学参数的信息熵特点平衡遗传算法(GA)的终止条件。通过统计分析完成了输入变量的筛选,去除了对预测影响较大的共线性因素,并实现了输入降维提高预测精度和速率。最后应用数据的信息熵特征,训练改进的GA-SVR建立最终的多源数据特征级融合预测模型。通过对比表明基于多源数据融合的预测方法精度最高,预测结果的相对误差平均值为0.7757%,具有实际可行性。     

系统可靠度置信下限估计方法及其应用

针对寿命服从指数分布的随机截尾样本，研究单元及系统可靠度的评估方法，给出了系统可靠度置信下限估计方法，该方法同样适用于工程中常见的定时截尾样本与定数截尾样本的系统可靠度评估问题。首先通过分位数填充算法将随机截尾数据补充成虚拟完全样本，然后基于信仰推断，给出系统内每个单元失效率的信仰分布，最后根据指数分布的特点，从失效率角度出发，采用蒙特卡罗法对单元失效率进行随机抽样，结合系统可靠性模型得到系统失效率的分布，在给定置信水平下即可得到系统失效率上限，进而得到工程上特别关注的系统可靠度置信下限。     

Efficient parametric uncertainty analysis within the hybrid Finite Element/Statistical Energy Analysis method

This paper is concerned with the development of efficient algorithms for propagating parametric uncertainty within the context of the hybrid Finite Element/Statistical Energy Analysis (FE/SEA) approach to the analysis of complex vibro-acoustic systems. This approach models the system as a combination of SEA subsystems and FE components; it is assumed that the FE components have fully deterministic properties, while the SEA subsystems have a high degree of randomness. The method has been recently generalised by allowing the FE components to possess parametric uncertainty, leading to two ensembles of uncertainty: a non-parametric one (SEA subsystems) and a parametric one (FE components). The SEA subsystems ensemble is dealt with analytically, while the effect of the additional FE components ensemble can be dealt with by Monte Carlo Simulations. However, this approach can be computationally intensive when applied to complex engineering systems having many uncertain parameters. Two different strategies are proposed: (i) the combination of the hybrid FE/SEA method with the First Order Reliability Method which allows the probability of the non-parametric ensemble average of a response variable exceeding a barrier to be calculated and (ii) the combination of the hybrid FE/SEA method with Laplace's method which allows the evaluation of the probability of a response variable exceeding a limit value. The proposed approaches are illustrated using two built-up plate systems with uncertain properties and the results are validated against direct integration, Monte Carlo simulations of the FE and of the hybrid FE/SEA models.     

Determination of uncertainty in environmental noise measurements by bootstrap method

An effective method for real-time evaluation of confidence intervals associated to quantile (L_q) and equivalent (L_eq) levels in environmental noise measurements is presented. The non-parametric surrogate data (or bootstrap) method, is described here in its basic form, valid for independent and identically distributed data, but is readily extendible to the treatment of dependent data. Application to actual measurements are shown which illustrate the practical effectiveness of real-time error evaluation during environmental monitoring.     

Investigation of changes in the order parameters near antiphase boundaries in the Cu<Subscript>3</Subscript>Au alloy

Investigation of the specific features of order-disorder structural phase transitions in ordering alloys in the presence of antiphase boundaries of conservative and nonconservative types has been performed in a computer experiment by the example of the model Cu₃Au alloy. The distributions of the long-range and short-range order parameters in the planes parallel to antiphase boundaries have been obtained by the Monte Carlo method for different temperatures. The mechanisms of disordering near conservative and nonconservative boundaries in ordering alloys are revealed. It is shown that the effect of diffusion of superstructural parameters is significant near nonconservative antiphase boundaries in comparison with conservative boundaries. Obviously, nonconservative boundaries can make a relatively large contribution to the effect of positive temperature dependence of the yield strength of ordering alloys with the L1₂ superstructure.     

Radiation dose measurement for patients undergoing common spine medical x-ray examinations and proposed local diagnostic reference levels

The main purposes of this study were to investigate patient dose in Spine radiographic examinations, as high dose procedures and propose the first LDRLs (Local Diagnostic Reference Levels) in Khuzestan region, southwest of Iran. ESD (Entrance Skin Dose) values of patients who underwent six spine radiographic procedures containing cervical (AP/LAT), thoracic (AP/LAT) and lumbar (AP/LAT), as high dose procedures, were evaluated. Patient doses were calculated from patient's individual anatomical data (weight, height and organ thickness) and exposure parameters (kVp, mAs, FFD and projection) based on the IAEA (International Atomic Energy Agency) Technical Report Series No.457. Indirect dosimetry method was conducted on 412 standard patients (57% men and 43% women) at seven high-patient-load hospitals. This survey reveals significant variations in the radiological practice. Despite large discrepancies found in the tube loadings (3–128 for lumbar AP and 3–200 for lumbar LAT), ESDs in all examinations were lower than the IAEA and EC (European Commission) DRLs (Diagnostic Reference Levels), 1.30, 1.65, 2.29, 3.09, 5, 7.5 mGy for cervical AP, cervical LAT, thoracic AP, lumbar AP, thoracic LAT and lumbar LAT respectively. Optimization of radiological practice could be accelerated by updating clinical audits and patient dose considerations, adequate training of students, implementation of systematic QA and QC programs and the use of qualified diagnostic medical physicists in the imaging sections. It is advisable that DRLs obtained in this study can be used as local DRL and dose surveys must be performed in all regions to establish NDRLs (National Diagnostic Reference Levels) in Iran. Also, national authorities must review periodically reference levels to ensure that it remains appropriate.     

Zero-temperature ordering in the two-dimensional quantum XY model

We have calculated the probability distribution for the staggered magnetization at T=0 for the 2D antiferromagnetic quantum XY model on finite lattices. For the ground state, the distribution shows evidence of isotropic magnetization ordering on the xy-plane. Based on data on seven lattices up to 26 sites, the extrapolated value of the staggered magnetization is 0.448±0.003 in the thermodynamic limit.     

Statistics of Persistent Events in the Binomial Random Walk: Will the Drunken Sailor Hit the Sober Man?

The statistics of persistent events, recently introduced in the context of phase ordering dynamics, is investigated in the case of the one-dimensional lattice random walk in discrete time. We determine the survival probability of the random walker in the presence of an obstacle moving ballistically with velocity v, i.e., the probability that the random walker remains up to time n on the left of the obstacle. Three regimes are to be considered for the long-time behavior of this probability, according to the sign of the difference between v and the drift velocity V¯ of the random walker. In one of these regimes (v>V¯), the survival probability has a nontrivial limit at long times which is discontinuous at all rational values of v. An algebraic approach allows us to compute these discontinuities as well as several related quantities. The mathematical structure underlying the solvability of this model combines elementary number theory, algebraic functions, and algebraic curves defined over the rationals.     

基于社交网络的观点传播动力学研究

社交网络和微博是重要的Web2.0应用模式, 其观点传播模式与其他网络媒体以及传统媒体相比有很大差异. 本文提出一种基于在线社交网络的观点传播模型, 研究社交网络中舆论观点扩散的形式与特征. 仿真结果表明: 模型中信息传播的速度与六度分割理论的结论十分符合; 一个带强烈倾向性的观点在固有观点均匀分布的网络中传播的情况下, 稳定时网络中不会出现相反的观点; 稳定时的观点分布与源节点的度和回溯深度有关, 并不受信任界限的限制, 这与Deffuant模型和Hegselmann-Krause模型不同. 同时, 本文还分析了传播意愿、观点变更率和信任界限对弛豫时间的影响.     

A method of cauchy integral equation for non-coherent transfer in half-space

A technique is presented which allows easy construction of solutions for various half-space problems arising in non-coherent radiative transfer with complete redistribution. By use of an inverse Laplace transform method, Wiener-Hopf integral equations are reduced to Cauchy-type singular integral equations. The factorization technique used by Case and Zweifel for coherent scattering can then be carried over to non-coherent transfer. The method is applied to the inhomogeneous integral equation for the source function of a two-level atom, previously solved by Ivanov. It is also applied to the conservative, homogeneous case and to singular Wiener-Hopf equations arising from asymptotic expansions in the limit of vanishing probability of collisional destruction ?. Consequences for the scaling laws in a finite slab are examined in a companion paper.