An Introduction to the Approximation of Functions

The problem considered is that of minimizing a positive definite quadratic form subject to linear constraints. Mantel has conjectured that the constrained minimum must lie on that boundary which is farthest from the unconstrained minimum, where distance is measured by means of the given quadratic form. A counter-example is given.     

基于神经营销学的音乐与颜色相关性

采纳认知科学的研究方法,通过对12位被试的脑电进行事件相关电位分析（ERP）,对音乐与颜色的相关性进行了研究。研究结果表明,音乐与颜色存在相关性,由于音乐的加入,被试对于颜色的识别效率降低。而在校园歌曲的背景下,被试对于绿色的识别效率与其他颜色相比存在显著差异。有鉴于此,在广告设计、网页展示中,应采纳相关度较高的音乐与颜色组合,发挥两者的组合效应,提升营销效果。     

Optimal placement of training symbols for frequency acquisition: a Crame/spl acute/r-rao bound approach

We consider the problem of training symbol placement for timing acquisition in digital magnetic recording systems that can be modeled as band-limited, baud-rate sampled systems with intersymbol interference and frequency offset. The conventional approach is to place known symbols at the start of the sector and use these at the detector to run a trained phase-locked loop (PLL). We introduce an additional degree of freedom by allowing arbitrary locations for the training symbols. We first consider a simplified system model where only the training symbols are written, or equivalently, the unknown data is assumed to be zero. We derive the modified Cramer-Rao bound (CRB) on the timing estimation error variance as a function of the training symbol locations and then derive the optimal training symbol placement strategy to minimize the CRB. The optimal strategy, called the split-preamble strategy, is to split the known symbols into two halves and place these at the beginning and at the end of the sector. Simulations with a proposed PLL-based method show that the split-preamble arrangement leads to a reduced frequency estimation error variance and also greatly reduces the occurrence of lost or added symbols, i.e., cycle slips. Finally, we present a simplified analysis of the problem when both known and unknown data are present, and show that the same arrangement also minimizes the CRB in this case.     

Exact dynamic stiffness matrix for a thin‐walled beam of doubly asymmetric cross‐section filled with shear sensitive material

An exact dynamic stiffness matrix is developed for the flexural motion of a three‐dimensional, bi‐material beam of doubly asymmetric cross‐section. The beam comprises a thin walled outer layer that encloses and works compositely with its shear sensitive core material. The outer layer may have the form of an open or closed section and provides flexural, warping and Saint‐Venant rigidity, while the core material provides Saint‐Venant and shear rigidity. The uniform distribution of mass in the member is accounted for exactly and thus necessitates the solution of a transcendental eigenvalue problem. This is accomplished using the Wittrick–Williams algorithm, which enables the required natural frequencies to be converged upon to any required accuracy with the certain knowledge that none have been missed. Such a formulation enables the powerful modelling features associated with the finite element technique to be utilized when establishing structural models. Three examples are included to validate and illustrate the method. The work also holds considerable potential in its application to the approximate analysis of asymmetric, multi‐storey, three‐dimensional wall‐frame structures. Copyright © 2006 John Wiley & Sons, Ltd.     

Enhanced analysis of poly(ethylene glycols) and peptides using thermospray mass spectrometry

The effects of a needle-tip repeller electrode on thermospray mass spectra of poly(ethylene glycols) and peptide samples have been studied. A significant increase in ion current was observed for increased repeller potentials in the low-mass region (m/z 300 to m/z 1100) and the high-mass region (m/z 1100 to m/z 1900). The change in ion current is due to a change in ion extraction efficiency because of increased ion diffusion rates. The amount of peptide sample needed for direct injection studies was decreased 1 to 2 orders of magnitude by using an ion source with both a needle-tip repeller electrode and a restricted vaporizer probe tip.     

滚动轴承故障诊断的多重超阶分析方法

多重分形去趋势波动分析(MF-DFA)可以获得能够表征信号内在动力学机制的多重分形谱,但是在提取滚动轴承振动信号故障特征时存在参数接近、状态混叠等问题,导致分析结果易受信号噪声等因素干扰,影响分类精度。为解决此问题,提出了多重超阶分析(MF-SOA)的方法。该方法将极值增量方法引入了多重去趋势波动分析中,对时间序列进行取极值操作;然后计算并分析获得的极值增量序列的重分形特征,通过MF-SOA方法获得的特征可以更清晰地表现出序列的内部动力学机制。最后将所提出的方法应用于滚动轴承的故障诊断中。试验数据分析结果表明,该方法对于信号的不规则程度十分敏感,并且有效改善了MF-DFA方法的缺陷,对于模式相近的故障类型有更优的区分度,提高了滚动轴承故障诊断的精度。     

Some questions of stability of the plane form of deformation of filaments of finite rigidity beyond the elastic limits

A method of calculating the stabilty of the plane form of bending of elastoplastic filaments of finite rigidity is presented on the basis of the theory of plastic flow. It is shown that this problem reduces to relationships similar to Kirchhoff's equations for an elastic case of working. Dependences containing equations of beam theory as a particular case are obtained for determining the reduced rigidity characteristics of the cross section of a filament with plastic regions. The article investigates the effect of size of the plastic regions on the interface between the plastic-deformation and load relief zones and also on the cross section of the filament. Graphically represented results of calculations are analyzed.Translated from Problemy Prochnosti, No. 10, pp. 37–44, October, 1992.     

Perceiving and remembering speech depend on multifractal nonlinearity in movements producing and exploring speech

Speech perception and memory for speech require active engagement. Gestural theories have emphasized mainly the effect of speaker''s movements on speech perception. They fail to address the effects of listener movement, focusing on communication as a boundary condition constraining movement among interlocutors. The present work attempts to break new ground by using multifractal geometry of physical movement as a common currency for supporting both sides of the speaker–listener dyads. Participants self-paced their listening to a narrative, after which they completed a test of memory querying their narrative comprehension and their ability to recognize words from the story. The multifractal evidence of nonlinear interactions across timescales predicted the fluency of speech perception. Self-pacing movements that enabled listeners to control the presentation of speech sounds constituted a rich exploratory process. The multifractal nonlinearity of this exploration supported several aspects of memory for the perceived spoken language. These findings extend the role of multifractal geometry in the speaker''s movements to the narrative case of speech perception. In addition to posing novel basic research questions, these findings make a compelling case for calibrating multifractal structure in text-to-speech synthesizers for better perception and memory of speech.     

Modelling and control of broad band traffic using multiplicative multifractal cascades

We present the results on the modelling and synthesis of broad-band traffic processes namely ethernet inter-arrival times using the VVGM (variable variance gaussian multiplier) multiplicative multifractal model. This model is shown to be more appropriate for modelling network traffic which possess time varying scaling/self-similarity and burstiness. The model gives a simple and efficient technique to synthesise Ethernet inter-arrival times. The results of the detailed statistical and multifractal analysis performed on the original and the synthesised traces are presented and the performance is compared with other models in the literature, such as the Poisson process, and the Multifractal Wavelet Model (MWM) process. It is also shown empirically that a single server queue preserves the multifractal character of the process by analysing its inter-departure process when fed with the multifractal traces. The result of the existence of a global-scaling exponent for multifractal cascades and its application in queueing theory are discussed. We propose tracking and control algorithms for controlling network congestion with bursty traffic modelled by multifractal cascade processes, characterised by the Holder exponents, the value of which at an interval indicates the burstiness in the traffic at that point. This value has to be estimated and used for the estimation of the congestion and predictive control of the traffic in broadband networks. The estimation can be done by employing wavelet transforms and a Kalman filter based predictor for predicting the burstiness of the traffic.     

Torsion of an infinite composite elastic cylindrical shell

Summary The problem considered is that of the torsion of a semi-infinite composite elastic cylindrical shell composed of two materials of different rigidity modulus. It is assumed that there is perfect bonding at the common cylindrical surface. The problem is solved by means of the use of Fourier transforms.     

Steady convection in porous media—II. The case of low rayleigh numbers and asymptotic expansions

In [6] we have proved that for sufficiently low Rayleigh numbers uniqueness holds; here we show that this only solution is analytic and regular with respect to the Rayleigh number. In connection with these general results, we study by the perturbation method the case of the domain confined between two concentric spheres which are maintained at different but uniform temperatures. Using the first three terms of the asymptotic expansions, two special values of the Rayleigh number are pointed out; they separate different types of flows—with one, two or three cells.     

A Lie-Group Adaptive Method for Imaging a Space-Dependent Rigidity Coefficient in an Inverse Scattering Problem of Wave Propagation

We are concerned with the reconstruction of an unknown space-dependent rigidity coefficient in a wave equation. This problem is known as one of the inverse scattering problems. Based on a two-point Lie-group equation we develop a Lie-group adaptive method (LGAM) to solve this inverse scattering problem through iterations, which possesses a special character that by using onlytwo boundary conditions and two initial conditions, as those used in the direct problem, we can effectively reconstruct the unknown rigidity function by aself-adaption between the local in time differential governing equation and the global in time algebraic Lie-group equation. The accuracy and efficiency of the present LGAM are assessed by comparing the imaged results with some postulated exact solutions. By means of LGAM, it is quite versatile to handle the wave inverse scattering problem for the image of the rigidity coefficient without needing any extra information from the wave motion.     

Adaptive wavelet-based multifractal model applied to the effective bandwidth estimation of network traffic flows

The authors investigate effective bandwidth estimation and Quality of Service (QoS) aware bandwidth provisioning for multifractal network traffic flows. They develop a novel adaptive wavelet-based multifractal model (AWMM) by using properties of the wavelet coefficients of multifractal cascade processes. The proposed AWMM has real-time updating capability and proves to be efficient in capturing multifractal network traffic characteristics. In addition, the authors derive an analytical expression for the effective bandwidth estimation of AWMM traffic flows, capable of being used to meet desired byte loss probabilities. Finally, they present an online effective bandwidth estimation algorithm that is incorporated into an adaptive bandwidth provisioning scheme and comparatively evaluated against some other bandwidth allocation methods.     

Rayleigh-Bénard对流的多分形及其谱特征

首先简单介绍了分形和多分形的概念,以及用WTMM方法计算多分形谱的步骤,然后分别从理论上和WTMM方法计算了标准2-6-2分Cantor集的多分形谱图,得出了多分形谱的一般物理意义。在此基础上,利用基于小波的WTMM方法计算了Rayleigh-Bénard对流多分形谱及其随流场结构变化的特征。研究结果表明:基于小波的WTMM方法研究多分形谱是可行的;Rayleigh-Bénard对流温度信号的多分形谱结构在由流场的中心向侧壁边缘的过渡中,其多分形谱态也是渐变的。     

Enhanced analysis of sulfonated azo dyes using liquid chromatography/thermospray mass spectrometry

Modifications to a thermospray vaporizer probe and ion source have been made that enhance ion evaporation resulting in increased sample ion current. These modifications include restricting the thermospray vaporizer exit orifice and the addition of a needle-tip repeller electrode to the thermospray ion source. The interaction and effect of probe-tip size, repeller voltage, and flow rate on sulfonated azo dye detection are reported. An increase in signal response for sulfonated azo dyes was observed. An efficient chromatographic separation procedure for sulfonated azo dyes, which is compatible with thermospray mass spectrometric detection, is also presented. Five disulfonated azo dyes were separated and detected by using selected ion monitoring. Mass spectra of disulfonated dyes show a number of molecular ions and adduct ions that provide unequivocal molecular weight information.     

基于感兴趣区域检测的条码定位技术研究

针对自然环境中受到各种污损干扰的二维条码的检测问题,提出了一种基于感兴趣区域检测的DataMatrix二维条码自动定位方法,解决了现有方法中由于条码保护区受损而导致提取失败的问题。该方法首先对图像进行预处理,然后进行区域分割和特征四边形提取,再进行条码检测和定位。实验表明,只要能得到满足分辨率要求的条码图像,对存在变形、模糊、反光、线条覆盖、细划痕等干扰下的条码能有效地识读,并能同时识读一副图像中的多个条码。     

导向信息传递的精准性研究

从图形符号的二维、三维表现形式上对信息传递的准确高效性进行研究,在分析图形符号直观简洁性优势的同时发现其现实运用的视角局限性,进而通过分析论述三维表现形式的多样性、强烈视觉冲击力及多维可视性的特点优势,指出了将直观简洁的平面符号以立体表现形式展现,更有利于导向信息传递的精准性和高效性。     

Generalized Model of Blood Flow in a Vertical Tube with Suspension of Gold Nanomaterials: Applications in the Cancer Therapy

Gold metallic nanoparticles are generally used within a lab as a tracer, to uncover on the presence of specific proteins or DNA in a sample, as well as for the recognition of various antibiotics. They are bio companionable and have properties to carry thermal energy to tumor cells by utilizing different clinical approaches. As the cancer cells are very smaller so for the infiltration, the properly sized nanoparticles have been injected in the blood. For this reason, gold nanoparticles are very effective. Keeping in mind the above applications, in the present work a generalized model of blood flow containing gold nanoparticles is considered in this work. The blood motion is considered in a cylindrical tube under the oscillating pressure gradient and magnetic field. The problem formulation is done using two types of fractional approaches namely CF (Caputo Fabrizio) and AB (Atangana-Baleanue) derivatives, whereas blood is considered as a counter-example of Casson fluid. Exact solutions of the problem are obtained using joint Laplace and Hankel transforms, and a comparative analysis is made between CF and AB. Results are computed in tables and shown in various plots for embedded parameters and discussed. It is found that adding 0.04-unit gold nanoparticles to blood, increase its heat transfer rate by 4 percent compared to regular blood. It is also noted that the heat transfer can be enhanced in the blood with memory.1     

Fractal processing of AFM images of rough ZnO films

Fractal image processing has been applied to characterize the surface roughness of ZnO films as measured by atomic force microscopy. The simple fractal analysis suggests that the fractal dimension D can be used to describe the change of the whole grain morphology along the growth direction. Multifractal analysis shows that the scaling range is close to three orders of magnitude, which is larger than that of a simple fractal and most empirical fractals. The width of the multifractal spectrum can be used to characterize the roughness of the film surface quantitatively and the shape of multifractal spectrum can describe the ratio between the number of the lowest valleys and the highest peaks statistically.