A computer-aided system for scaling topside ionograms

A computer-aided data-interpretation system is described that combines the abilities of a human operator for pattern recognition and decision making with those of a digital computer for rapid computation. It is designed for the specific task of converting ionograms to electron density N(h) profiles, but is sufficiently flexible in design and concept to be used, in principle, with any type of complex datum. The system consists of a small computer with an associated cathode-ray tube display, a human operator, and a large main computer. The small computer is used to digitize and store the ionogram tape and maintain the CRT display. The operator scales a trace representing one of the magnetoionic modes of the displayed ionogram, and commands the main computer to calculate the corresponding N(h) profile and the ionogram that would result from the computed profile. The operator then compares the remaining traces of the original and computed ionogram via the display, and either verifies the scaling or rescales the ionogram until the desired agreement has been achieved. The system permits the scaling, for N(h) analysis, of complex ionograms which otherwise could not be used for this purpose without great labor.     

基于小波变换的电能质量暂态分析

随着国家工业规模的扩大和科学技术的发展,电的使用越来越广泛,电力负荷迅速增加,对电网运行状态进行高效而准确的检测分析具有重大意义。相对于稳态分析,暂态分析的难点在于快速、及时地捕获信号突变和进行准确、稳定的分析。对于暂态信号突变的检测,该文从微分算子可以监测突变的特性出发,发现了小波滤波器Ⅳ阶消失矩和Ⅳ次卷积微分算子的等价关系,并对小波滤波器的检测能力做出了分析。     

An adaptive morphological filter for image processing

Novel types of opening operator (NOP) and closing operator (NCP) are proposed. An adaptive morphological filter is then constructed on the basis of the NOP and NCP. The filter can remove any details consisting of fewer pixels than a given number N, while preserving the other details. Efficient algorithms are also developed for the implementation of the NOP and NCP.     

非简谐振子湮没算符高次幂本征态的反聚束效应

研究了非简谐振子湮没算符高次幂本征态的反聚束效应,并用数值计算方法研究了非谐振项的大小对它们的影响.结果表明,非简谐振子湮没算符高次幂本征态的反聚束效应与谐振子的情况明显地不同,非简谐振子湮没算符高次幂本征态在非谐振子强度X=|β|2的若干取值区间内均可多次交替地呈现反聚束效应。随着非谐振项的变大,呈现反聚束效应的区间也变大。     

From differential equations to the construction of new wavelet-like bases

In this paper, an approach is introduced based on differential operators to construct wavelet-like basis functions. Given a differential operator L with rational transfer function, elementary building blocks are obtained that are shifted replicates of the Green's function of L. It is shown that these can be used to specify a sequence of embedded spline spaces that admit a hierarchical exponential B-spline representation. The corresponding B-splines are entirely specified by their poles and zeros; they are compactly supported, have an explicit analytical form, and generate multiresolution Riesz bases. Moreover, they satisfy generalized refinement equations with a scale-dependent filter and lead to a representation that is dense in L/sub 2/. This allows us to specify a corresponding family of semi-orthogonal exponential spline wavelets, which provides a major extension of earlier polynomial spline constructions. These wavelets are completely characterized, and it is proven that they satisfy the following remarkable properties: 1) they are orthogonal across scales and generate Riesz bases at each resolution level; 2) they yield unconditional bases of L/sub 2/-either compactly supported (B-spline-type) or with exponential decay (orthogonal or dual-type); 3) they have N vanishing exponential moments, where N is the order of the differential operator; 4) they behave like multiresolution versions of the operator L from which they are derived; and 5) their order of approximation is (N-M), where N and M give the number of poles and zeros, respectively. Last but not least, the new wavelet-like decompositions are as computationally efficient as the classical ones. They are computed using an adapted version of Mallat's filter bank algorithm, where the filters depend on the decomposition level.     

N antennas and their applications in portable handsets

A new antenna, the N antenna, is proposed for use in mobile communication systems. Detailed investigations are presented through the results obtained using numerical simulations and measurements. The newly proposed antenna has many attractive features such as a wide bandwidth, stable radiation patterns, and a compact structure. The application of the N antenna is exemplified through portable handsets. It is shown that in the presence of an operator, the efficiency of the antenna system of a portable handset increases and the maximum specific absorption rate (SAR) is significantly reduced by using the N antenna     

Analyse de composants plan-E symétriques en guides d’onde àsection rectangulaire

A differential method is presented for the efficient calculation of the modal scattering matrix of E- plane junctions in rectangular waveguides. This formalism is based on the Maxwell’s equations written in a non- orthogonal coordinates system. In a first approach, it requires 2N numerical integrations in order to obtain a (2N X 2N)- dimensional scattering matrix. We prove that the number of integrations can be divided by half. Moreover, the differential operator contains the structure geometry. Electromagnetic effects of symmetries can be easily deduced and the system size reduced and a saving in computation time obtained.     

Visual and quantitative evaluation of selected image combination schemes in ultrasound spatial compound scanning

Multi-angle spatial compound images are normally generated by averaging the recorded single-angle images (SAIs). To exploit possible advantages associated with alternative combination schemes, this paper investigates both the effect of number of angles (N/sub /spl theta//) as well as operator (mean, median, mean-excluding-maximum (mem), root-mean-square (rms), geometric mean and maximum) on image quality (tissue delineation and artifacts), speckle signal-to-noise ratio (SNR/sub s/) and contrast. The evaluation is based on in vitro SAI (/spl plusmn/21/spl deg/ in steps of /spl Delta//spl theta/=7/spl deg/) of formalin fixed porcine tissue containing adipose, connective and muscular tissue. Image quality increased with number of angles up to /spl plusmn/14/spl deg/ after which the improvements became debatable. The mem and median operators, which try to render the images more quantitatively correct by suppressing strong echoes from specular reflectors, provide some improvement in this regard. When combining the SAI with the mean operator, the SNR/sub s/ increases-in general-with N/sub /spl theta//. For N/sub /spl theta//=2, the SNR/sub s/ increases with /spl Delta//spl theta/ as expected. When N/sub /spl theta//=7, the highest SNR/sub s/ is obtained for the mem, rms, and geometric mean operators, while the lowest SNR/sub s/ is obtained for the maximum operator. When comparing SNR/sub s/ for adipose and fibrous tissue, the level is close to 1.91 for adipose tissue but only 1.7 for fibrous tissue which contain relatively few organized scattering structures.     

线性和非线性寄存器系统的并行化技术

并行化技术可降低电路工作速率、延时和功耗,广泛应用于通信处理中.对线性寄存器系统,通过对系统状态方程和输出方程的讨论提出一般性的(1,N)并行化方法,其对任意并行路数N均有统一计算方法;并对某些情况下的(M,N)并行提出一种新实现方法.对非线性寄存器系统,给出其定义,对其状态转移进行线性化,提出线性化矩阵法的并行方法;并对其特例——非线性移位寄存器的并行化提出推广延时因子法.     

光纤放大器的放大及噪声特性的量子分析

本文利用热库理论推导出N个稀土离子和单模场相互作用的约化密度算符的主方程,从而得了光纤放大器的光子放大方程,同时,对集总式光纤放大器的量子噪声也进行了研究,发现理想的光纤放大器可以达到了量子噪声极限。若考虑探测器中光电子的离散特性,最小的噪声因子为2,即3dB。     

基于Grover硬币算子的量子行走在商图上的演化算子

商图是利用图的对称性分析量子行走算法的一种重要数学工具.量子行走在商图上的演化算子由移位算子和硬币算子构成.本文以构造的方式给出了Grover硬币算子在超立方体的商图上对应的矩阵形式,并给出了其正确性证明.由于商图上的移位算子可由原图上的移位算子直接导出,从而确定了使用Grover算子作为硬币的量子行走在商图上的演化算子.     

A nonseparable VLSI architecture for two-dimensional discreteperiodized wavelet transform

A modified two-dimensional (2-D) discrete periodized wavelet transform (DPWT) based on the homeomorphic high-pass filter and the 2-D operator correlation algorithm is developed in this paper. The advantages of this modified 2-D DPWT are that it can reduce the multiplication counts and the complexity of boundary data processing in comparison to other conventional 2-D DPWT for perfect reconstruction. In addition, a parallel-pipeline architecture of the nonseparable computation algorithm is also proposed to implement this modified 2-D DPWT. This architecture has properties of noninterleaving input data, short bus width request, and short latency. The analysis of the finite precision performance shows that nearly half of the bit length can be saved by using this nonseparable computation algorithm. The operation of the boundary data processing is also described in detail. In the three-stage decomposition of an N×N image, the latency is found to be N²+2N+18     

图像边缘检测算法研究

边缘检测是图像处理中很重要的组成部分,其效果直接影响到后面的图像分析。在此介绍Roberts算子、Prewitt算子、Sobel算子、LOG算子和Canny算子等经典边缘检测算子,对其性能和算法特点进行分析。运用Matlab进行算法的仿真,并对其检测结果进行分析和比较,得出Canny算子的边缘连接程度最佳,景物的细节表现得最明晰,轮廓边缘提取得很完备。     

Optimum sufficient conditions for the stability of linear multivariable systems

By invoking a fixed-point theorem of functional analysis. Freeman has developed a stability criterion for linear multivariable systems. The criterion is derived by using an operator perturbation technique to try to ensure that the operator in the transformed system equation is a contraction. It is clearly desirable to be able to choose the perturbation operator so that the transformed open-loop operator is as small as possible in some sense. In the letter, we determine that perturbation operator, from the class of diagonal linear operators, that gives the smallest contraction for the transformed open-loop system operator.     

On construction of coprime factorizations for nonlinear feedback control systems

In this paper we describe a family of operators for constructing nontrivial left and right coprime factorizations under rather weak conditions for a large class of nonlinear feedback control systems that has a stabilizable or unstabilizable plant, using a common criterion of input-output stability. The proposed sufficiency and construction method are based on a generalization of the nonlinear Lipschitz operator theory formulated by us for such systems. This class of generalized nonlinear Lipschitz operators constitutes a very large family (an infinite-dimensional Banach space) of bounded nonlinear operators that describe (part of) the underlying systems. One of the main difficulties in constructing coprine factorizations for nonlinear feedback systems has been in taking care of the nonlinear composite and inverse operators that appear in the closed-loop configuration such that the overall feedback system is well defined in the sense of stability, causality, and uniqueness of the internal signals and such that the coprime factorizations can be achieved. In this paper we show how these difficult issues can be handled nicely under our framework of generalized nonlinear Lipschitz operator theory, at least for a very large class of nonlinear control systems. We give a simple illustrative example to show how these coprime factorizations can actually be characterized and constructed to yield explicit closed-form solutions.This work was supported in part by ONR Contract No. N00014-88-K-0127.     

Measurement of Time-Variant Linear Channels

The goal of channel measurement or operator identification is to obtain complete knowledge of a channel operator by observing the image of a finite number of input signals. In this paper, it is shown that the spreading support of the operator (that is, the support of the symplectic Fourier transform of the Kohn-Nirenberg symbol of the operator) has area less than one then the operator is identifiable. If the spreading support is larger than one, then the operator is not identifiable. The shape of the support region is essentially arbitrary thereby proving a conjecture of Bello. The input signal considered is a weighted delta train where the weights are the window function of a finite Gabor system whose elements satisfy a certain robust completeness property     

Characterization of Catheter Dynamics During Percutaneous Transluminal Catheter Procedures

Remote catheter navigation systems are being developed to reduce the occupational risk of the intervening physician. Despite the success of such systems, development has occurred with little fundamental knowledge of the catheter dynamics applied by the interventionalist. This paper characterizes the kinematics of a catheter during manipulation, the minimum applied force/torque during interventional procedures, and the maximum force/torque applied by an operator to overcome vasculature friction. Ten operators manipulated a 6F catheter inside a specialized catheter movement sensor to determine the velocities and accelerations of catheter motion. A mass-spring apparatus was constructed to measure the forces and torques required to overcome introducer sheath and vasculature friction. Results showed the catheter was manipulated at peak velocities and accelerations of (muplusmnsigma) : 360 plusmn 180 mmldrs^-1 and 22200 plusmn 14000 mmldrs^-2, and 19 plusmn 7 radldrs^-1 and 900 plusmn 510 radldrs^-2, for axial and radial directions of motion, respectively. A minimum force of 0.29 plusmn 0.06 N and a torque of 1.15 plusmn0.3 mNldrm was required to move the catheter through the introducer sheath; while the observed maximum applied torque was 15 mNldrm to overcome vasculature friction. The implications of these results for future design optimization of an intuitive remote catheter navigation system are considered.     

Operator dependence of 3-D ultrasound-based computational fluid dynamics for the carotid bifurcation

The association between vascular wall shear stress (WSS) and the local development of atherosclerotic plaque makes estimation of in vivo WSS of considerable interest. Three-dimensional ultrasound (3DUS) combined with computational fluid dynamics (CFD) provides a potentially valuable tool for acquiring subject-specific WSS, but the interoperator and intraoperator variability associated with WSS calculations using this method is not known. Here, the accuracy, reproducibility and operator dependence of 3DUS-based computational fluid dynamics were examined through a phantom and in vivo studies. A carotid phantom was scanned and reconstructed by two operators. In the in vivo study, four operators scanned a healthy subject a total of 11 times, and their scan data were processed by three individuals. The study showed that with some basic training, operators could acquire accurate carotid geometry for flow reconstructions. The variability of measured cross-sectional area and predicted shear stress was 8.17% and 0.193 N/m/sup 2/ respectively for the in vivo study. It was shown that the variability of the examined parameters was more dependent on the scan operators than the image processing operator. The range of variability of geometrical and flow parameters reported here can be used as a reference for future in vivo studies using the 3DUS-based CFD approach.     

弱磁场对N=3的自旋链上量子信息传输的影响

基于单比特量子信息在自旋链上的完美传输理论,研究了2种不随时变化的弱磁场对N=3的自旋链上单比特量子信息完美传输的影响。对包含磁场体系的哈密顿量进行对角化,并考虑演化算子的作用,结果表明：空间均匀且不随时变化的恒定弱磁场不会对信息传输的保真度产生影响;大小关于中心对称方向相反的弱磁场直接影响了实现量子信息完美传输的条件, 磁场越强实现完美传输的时间越短。     

A geometrical stability criterion, similar to the Popov criterion, for time-varying, nonlinear, continuous systems

A stability criterion, applicable in the analysis of a class of single-loop control systems, is derived. The loop of a system from this class of systems consists of a tandem connection of a time-varying gain; a memoryless, time-invariant, nonlinear operator; and an operator which satisfies an inner product inequality. When the operator, satisfying the inner product inequality is a linear, causal, time-invariant, convolution operator, a geometrical interpretation similar to the Popov criterion can be obtained.