基于积分方程的阵列信号的反演方法

本文将收敛速度快的变莆玻恩迭代法（ＤＢＩＭ）结合数值模式匹配法（ＮＭＭ）用于实际工程中的阵列感庆成象仪（ＡＩＴ）的测量的反演和剖面成象。在反演迭代过程中，利用ＮＭＭ解的Ｚ向解析性质，避免了双重数值积分，提高了计算效率，同时也提高了反演质量，文 中利用不完备的测量数据对ＡＩＴ进行了反演，表明该方法非常适合实际工程应用。     

基于双感应测井仪低数据量的反演方法研究

将一种迭代方法和双共轭梯度法用于实际工程中常用的双感应测井仪（DIT）的反演和剖面成象。基于目标区内、外电场积分方程,建立DIT的反演积分方程,利用MoM将积分方程高散为矩阵方程。在每次反演迭代过程中,用数值模式匹配法（NMM）求解DIT的感应电动势和格林函数。文中利用沿井轴的DIT不完备的低信息量对地层剖面进行反演,数值模拟结果表明该迭代方法的实际工程应用的潜力。     

NEC推出数字FM激励器HPB-3073

ＮＥＣ推出数字ＦＭ激励器ＨＰＢ－３０７３传统的调频立体声广播用激励器，一直都由模拟电路构成。而日本电气公司（ＮＥＣ）推出的ＨＰＢ－３０７３型数字ＦＭ激励器，从音频输入到音频限制用低通滤波器（ＬＰＦ）、预加重网络、立体声调制和ＦＭ调制部分全都实行数字运...     

NF－M蛋白在神经纤维形态构建上的功能分析

ＮＦ－Ｍ蛋白在神经纤维形态构建上的功能分析陈建国，中川辉良，广川信隆，翟中和（北京大学生命科学学院，北京１００８７１，东京大学医学部）神经纤维（中等纤维）由ＮＦ－Ｌ，ＮＦ－Ｍ和ＭＦ－Ｈ三种蛋白组成，是神经细胞骨架系统的重要组分之一，在树突和轴突中显示...     

电磁脉冲对目标腔体的孔缝耦合效应数值研究

利用时域有限差分（ＦＤ－ＴＤ）方法研究了超宽带电磁脉冲（ＵＷＢ），快上升前沿电磁脉冲（ＦＲＥＭＰ），核电磁脉冲（ＮＥＭＰ）对目标腔体的孔缝耦合效应。研究表明：对于较小尺寸的目标腔体，在孔缝尺寸也较小的情况下，ＦＲＥＭＰ和ＵＷＢ相对于ＮＥＭＰ更容易通过腔体上的孔缝耦合进入目标腔体，而且更容易引起孔腔共振。     

脉冲激光沉积铌酸锶钡铁电薄膜及其性能表征

利用脉冲激光沉积（ＰＬＤ）技术在ＭｇＯ、ＬＳＣＯ／ＭｇＯ衬底上在位制备了铌酸锶钡（ＳＢＮ）铁电薄膜,发现ＳＢＮ薄膜在ＭｇＯ、ＬＳＣＯ／ＭｇＯ衬底上均呈（００１）择优取向。用扫描电子显微镜（ＳＥＭ）和原子力显微镜（ＡＦＭ）表明ＳＢＮ薄膜的晶粒细小致密,铁电微畴尺寸约为２００ｎｍ。ＳＢＮ薄膜的剩余极化强度为１８．６μＣ／ｃｍ２,矫顽场为２２．３ｋＶ／ｃｍ。     

EEPROM单元结构的变革及发展方向

扼要阐述了电可擦除可编程只读存储器（ＥＥＰＲＯＭ）发展史上的各种结构如ＦＡＭＯＳ、ＭＮＯＳ、ＳＩＭＯＳ、ＤＩＦＭＯＳ、ＦＥＴＭＯＳ（ＦＬＯＴＯＸ）等，比较了它们的优缺点，着重论述了ＥＥＰＲＯＭ结构今后的变革方向。     

快上升前沿电磁脉冲的孔缝耦合效应数值研究

本文利用时域有限差分（ＦＤ－ＴＤ）法研究快上升前沿电磁脉冲（ＦＲＥＭＰ）对目标腔体的孔缝耦合效应。并将计算结果与核电磁脉冲（ＮＥＭＰ）的耦合结果进行比对。研究表明：对于较小尺寸的目标腔体,在孔缝尺寸也较小的情况下,ＦＲＥＭＰ相对于ＮＥＭＰ更容易耦合进入目标腔体,且更容易引起孔腔谐振。     

全业务接入网

本文介绍了全业务接入网（ＦＳＡＮ）的网络结构,讨论了其中的关键技术：ＡＴＭ无源光网络（ＡＰＯＮ）设计、ＡＰＯＮ帧结构以及ＷＤＭ和ＥＤＦＡ在网络中的应用,最后提出自己的建议。     

HFC网管对象MIB的研究

概述了在ＨＦＣ网络中电缆设备（电缆调制解调器终端服务器、电缆调制解调器）基于ＤＯＣＳＩＳ／ＳＮＭＰ标准和规范的管理信息库（ＭＩＢ）的定义和扩充,限于篇幅,本文只涉及了其中的ＲＦ接口ＭＩＢ和电缆设备ＭＩＢ两部分,研究和掌握ＨＦＣ网络设备ＭＩＢ对实现ＨＦＣ网络业务和网络管理系统开发的意义是十分重要的。     

用修正玻昂迭代法重建复杂介质结构

着重阐述了将修正玻昂迭代法结合高效的数值模式匹配法用于感应测井中的反演与剖面成象。首先利用玻昂近拟将非线性问题线性比，然后应用吉洪诺夫正则化与迭代方法求解电磁场的积分方程。     

基于积分方程的阵列信号的反演方法

本文将收敛速度快的变形玻恩迭代法(DBIM)结合数值模式匹配法(NMM)用于实际工程中的阵列感应成象仪(AIT)的测量信号的反演和剖面成象。在反演迭代过程中,利用NMM解的z向解析性质,避免了双重数值积分,提高了计算效率,同时也提高了反演质量。文中利用不完备的测量数据对AIT进行了反演,表明该方法非常适合实际工程应用。     

Nonlinear inversion of electrode-type resistivity measurements

Deals with the inversion of low-frequency electrode-type resistivity measurements for the conductivity distribution in a two-dimensional axisymmetric medium. It is well known that the inversion of such transverse magnetic measurements is much more nonlinear than that of transverse electric measurements. The distorted Born iterative method (DBIM) is applied to solve the nonlinear inverse problem. In each iteration of the DBIM, an efficient numerical mode-matching (NMM) method is used as a forward solver. In addition to its efficiency in solving for the predicted data, the NMM method gives a semianalytic expression for the partial derivatives of the Green's function required in the inversion. Several numerical results are presented to demonstrate the applications of the DBIM, and to address several practical issues related to the performance of the nonlinear inversion scheme. Because of the fast forward modeling and semianalytic Green's function available due to the NMM method, the inversion is fast and is practical for the interpretation of measurement data     

基于阵列信息的二维轴对称电导率分布的有效反演方法

本文基于实际工程应用中的阵列感应测井仪（ＡＩＴ）的测量信息,利用变分坡昂迭代法（ＶＢＭ）,在非均匀背景介质中来重构和反演地层的电导率剖面。该方法基于非线性积分方程利用变分方法来建立反演方程,在反演迭代过程中,非均匀剪影介质中的格林函数无须更新,与变形玻昂迭代法（ＤＢＩＭ）相比其计算复杂性大大降低,文中仅利用沿井轴的ＡＩＴ响应对地层电导率进行反演,其胍演结果与起初地层电导率分布吻合的较好。     

Hybrid Born iterative method in low-frequency inverse scatteringproblem

With its fast convergence, the distorted Born iterative method (DBIM) has been widely used in low-frequencg inverse scattering analysis, however its inherent drawback, sensitive-to-noise disturbance, may greatly limit its practical applications. In this paper, the numerical analysis is made to compare the DBIM and the Born iterative method (BIM). Then a hybrid BIM is presented. In this method, the DBIM is employed to speed the solution convergence in the initial several iterations and the BIM is used to improve the solution stability in the later iterations. The switch condition is also given. The simulation results show that the method is valid for the inverse scattering solution     

Reconstruction of two-dimensional permittivity distribution using the distorted Born iterative method

The distorted Born iterative method (DBIM) is used to solve two-dimensional inverse scattering problems, thereby providing another general method to solve the two-dimensional imaging problem when the Born and the Rytov approximations break down. Numerical simulations are performed using the DBIM and the method proposed previously by the authors (Int. J. Imaging Syst. Technol., vol.1, no.1, p.100-8, 1989) called the Born iterative method (BIM) for several cases in which the conditions for the first-order Born approximation are not satisfied. The results show that each method has its advantages; the DBIM shows faster convergence rate compared to the BIM, while the BIM is more robust to noise contamination compared to the DBIM.     

轴对称二维非均匀介质的快速反演方法

首先采用变分原理和非线性积分方程推导出反演方程，然后利用玻恩迭代法对轴对称二维非均匀介质分布进行了反演。通过计算实例表明，该方法的收敛速度比玻恩迭代法快得多，在迭代前期与变形玻恩迭代法相当，而在迭代后期比变形玻恩迭代法的收敛速度更快；同时，每次迭代所需时间虽然多于玻恩迭代法，但明显少于变形玻恩迭代法。该方法同时具备了玻恩和变形玻恩迭代法两者的优点。     

Modeling low-frequency electrode-type resistivity tools in invadedthin beds

The authors formulate and implement a numerical mode-matching (NMM) method to model electrode-type resistivity tools in invaded thin beds. The authors derive the low-frequency approximation of the Maxwell's equations to obtain the partial differential equation for the potential field. The new NMM program is validated by comparing the numerical results with those obtained from other dc programs. It is found that this new program is much faster than the program using the finite-element method (FEM), and hence is useful for routine interpretation of resistivity logs and for inversion     

Tomographic Reconstruction of Three-Dimensional Volumes Using the Distorted Born Iterative Method

Although real imaging problems involve objects that have variations in three dimensions, a majority of work examining inverse scattering methods for ultrasonic tomography considers 2-D imaging problems. Therefore, the study of 3-D inverse scattering methods is necessary for future applications of ultrasonic tomography. In this work, 3-D reconstructions using different arrays of rectangular elements focused on elevation were studied when reconstructing spherical imaging targets by producing a series of 2-D image slices using the 2-D distorted Born iterative method (DBIM). The effects of focal number f/#, speed of sound contrast Deltac, and scatterer size were considered. For comparison, the 3-D wave equation was also inverted using point-like transducers to produce fully 3-D DBIM image reconstructions. In 2-D slicing, blurring in the vertical direction was highly correlated with the transmit/receive elevation point-spread function of the transducers for low Deltac. The eventual appearance of overshoot artifacts in the vertical direction were observed with increasing Deltac. These diffraction-related artifacts were less severe for smaller focal number values and larger spherical target sizes. When using 3-D DBIM, the overshoot artifacts were not observed and spatial resolution was improved. However, results indicate that array configuration in 3-D reconstructions is important for good image reconstruction. Practical arrays were designed and assessed for image reconstruction using 3-D DBIM.     

一种高分辨率组合侧向电极系及其性能分析

为了解决电阻率测井仪的纵向分辨率和径向探测深度的矛盾。介绍了一种新型的高分辨率组合侧向电极系,并对其测井响应及性能进行了高效数值模拟。数值模式匹配方法是一种解析－数值混合方法,它使非均匀介质中的场的二维数值分析简化为一维数值分析和另一维的解析递推,从而大大了数值计算量。