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齿轮齿厚四种测量方法公差的微分转换 被引量:1
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作者 陈艳 《水利电力机械》 2001年第4期30-32,共3页
用微分法导出了分度圆弦齿厚、公法线长度、固定弦齿厚、圆棒测量跨距 4种方法测量齿厚公差的转换公式。
关键词 齿厚 公法线 公差 渐开线齿轮 微分转换
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微分转换电阻率测深法研究
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作者 卢巧媛 岑雄鹰 《中南矿冶学院学报》 CSCD 1994年第A05期116-120,共5页
本文介绍微分转换电阻率测深法的原理,并通过计算所得曲线,分析其性质,指出其应用时应注意的问题。
关键词 电测深 微分转换 电阻率
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基于改进可微分域转换的双域锥束计算机断层扫描重建网络用于锥角伪影校正 被引量:1
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作者 彭声旺 王永波 +2 位作者 边兆英 马建华 黄静 《南方医科大学学报》 CAS CSCD 北大核心 2024年第6期1188-1197,共10页
目的 提出一种基于改进可微分域转换的双域锥束计算机断层扫描(CBCT)重建框架DualCBR-Net用于锥角伪影校正。方法 所提出的双域CBCT重建框架DualCBR-Net包含3个模块:投影域预处理、可微分域转换和图像后处理。投影域预处理模块首先对投... 目的 提出一种基于改进可微分域转换的双域锥束计算机断层扫描(CBCT)重建框架DualCBR-Net用于锥角伪影校正。方法 所提出的双域CBCT重建框架DualCBR-Net包含3个模块:投影域预处理、可微分域转换和图像后处理。投影域预处理模块首先对投影数据进行排方向扩充,使被扫描物体能够被X射线完全覆盖。可微分域转换模块引入重建和前投影算子去完成双域网络的前向和梯度回传过程,其中几何参数对应扩大的数据维度,扩大几何在网络前向过程中提供了重要先验信息,在反向过程中保证了回传梯度的精度,使得锥角区域的数据学习更为精准。图像域后处理模块对域转换后的图像进一步微调以去除残留伪影和噪声。结果 在Mayo公开的胸部数据集上进行的验证实验结果显示,本研究提出的DualCBR-Net在伪影去除和结构细节保持方面均优于其他竞争方法;定量上,这种DualCBR-Net方法在PSNR和SSIM上相对于最新方法分别提高了0.6479和0.0074。结论 本研究提出的基于改进可微分域转换的双域CBCT重建框架DualCBR-Net用于锥角伪影校正方法使有效联合训练CBCT双域网络成为可能,尤其是对于大锥角区域。 展开更多
关键词 CBCT 锥角伪影 微分转换
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自动微分转换系统及其应用 被引量:1
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作者 程强 王斌 马再忠 《数值计算与计算机应用》 CSCD 北大核心 2003年第4期276-284,共9页
§1.引言 计算微分大致经历了从差商微分,符号微分,手写代码到自动微分几个阶段,与其它几种微分方法相比,自动微分具有代码简练、计算精度高及投入人力少等优点.自动微分实现的基本出发点是:一个数据相对独立的程序对象(模式、过程... §1.引言 计算微分大致经历了从差商微分,符号微分,手写代码到自动微分几个阶段,与其它几种微分方法相比,自动微分具有代码简练、计算精度高及投入人力少等优点.自动微分实现的基本出发点是:一个数据相对独立的程序对象(模式、过程、程序段、数值语句乃至数值表达式)无论多么复杂,总可以分解为一系列有限数目的基本函数(如sin,exp,log)和基本运算操作(加、减、乘、除、乘方)的有序复合.对所有这些基本函数及基本运算操作,重复使用链式求导法则,将得到的中间结果自上而下地做正向积分就可以建立起对应的切线性模式,自下而上地做反向积分就可以建立起对应的伴随模式[1].基于自动微分方法得到的切线性模式和伴随模式,在变分资料同化[2]、系统建模与参数辨识[3]、参数的敏感性分析[4]、非线性最优化以及数值模式的可预测性分析[5]等问题中有着十分广泛的应用. 展开更多
关键词 自动微分转换系统 可靠性 有效性 二元归约法 DFT系统
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推导弹性力学极坐标中平衡微分方程和几何方程的解析法 被引量:2
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作者 陈彦 陈丰 邵红才 《力学与实践》 北大核心 2020年第6期794-796,共3页
根据直角坐标和极坐标中偏微分算子的转换式、应力和应变分量的坐标变换式以及基矢量变换矩阵,提出了推导极坐标中平衡微分方程和几何方程的解析法,不需要作图,可以从直角坐标中的平衡微分方程和几何方程直接导出极坐标中的方程形式,丰... 根据直角坐标和极坐标中偏微分算子的转换式、应力和应变分量的坐标变换式以及基矢量变换矩阵,提出了推导极坐标中平衡微分方程和几何方程的解析法,不需要作图,可以从直角坐标中的平衡微分方程和几何方程直接导出极坐标中的方程形式,丰富了弹性力学课程教学内容。 展开更多
关键词 微分算子转换 应力分量坐标变换式 应变分量坐标变换式 基矢量变换矩阵
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A numerical analysis to the non-linear fin problem 被引量:1
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作者 Rafael CORTELL 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第5期648-653,共6页
In this paper a numerical analysis is carried out to obtain the temperature distribution within a single fin. It is assumed that the heat transfer coefficient depends on the temperature. The complete highly non-linear... In this paper a numerical analysis is carried out to obtain the temperature distribution within a single fin. It is assumed that the heat transfer coefficient depends on the temperature. The complete highly non-linear problem is solved numerically and the variations of both, dimensionless surface temperature and dimensionless surface temperature gradient as well as heat transfer characteristics with the governing non-dimensional parameters of the problem are graphed and tabulated. 展开更多
关键词 FINS Ordinary differential equations (ODEs) Numerical solution Heat transfer
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Relationship Between Differential Interference Angle and Parameter of Experiment in Molecular Beam 被引量:1
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作者 LI Yong-Qing LI Jian MA Feng-Cai 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第2X期294-296,共3页
Collisional quantum interference (CQI) was observed in the intramolecular rotational energy transfer in the experiment of the static cell, and the integral interference angles were measured. To observe more precise ... Collisional quantum interference (CQI) was observed in the intramolecular rotational energy transfer in the experiment of the static cell, and the integral interference angles were measured. To observe more precise information, the experiment in the molecular beam should be taken,from which the relationship between the differential interference angle and the scattering angle can be obtained. In this paper, the theoretical model of CQI is described in an atom-diatom system in the condition of the molecular beam, based on the first-Born approximation of time-dependent perturbation theory, taking into accounts the long-range interaction potential. The method of observing and measuring correctly the differential interference angle is presented. The changing tendency of the differential interference angle with the impact parameter and relative velocity is discussed. The changing tendencies of the differential interference angle with the parameter of experiment in the molecular beam, including the impact parameter and the velocity are discussed. This theoretical model is important to understand or perform the experiment in the molecular beam. 展开更多
关键词 differential interference angle quantum interference rotational energy transfer
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On Mutual Transform Between Number-Difference State and Phase State Corresponding to Operational Phase Operator
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作者 FAN Hong-Yi HU Hai-Peng 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第3X期537-540,共4页
In the mutual transform between the number-difference state and the phase state corresponding to the operational phase operator we find that there exists an end-point ambiguousness. This problem can be avoided by Ligh... In the mutual transform between the number-difference state and the phase state corresponding to the operational phase operator we find that there exists an end-point ambiguousness. This problem can be avoided by Lighthill's method. 展开更多
关键词 operational phase operator phase state end-point ambiguousness
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TIME DOMAIN ANALYSIS OF TRANSIENT PROPAGATION IN INHOMOGENEOUS MAGNETIZED PLASMA USING Z-TRANSFORMS
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作者 Huang Shoujiang Li Fang 《Journal of Electronics(China)》 2006年第1期113-116,共4页
The electromagnetic propagation through an inhomogeneous magnetized plasma slab is studied using the Z-transform formulation of the Finite-Difference Time-Domain(FDTD) method. The direction of electromagnetic propagat... The electromagnetic propagation through an inhomogeneous magnetized plasma slab is studied using the Z-transform formulation of the Finite-Difference Time-Domain(FDTD) method. The direction of electromagnetic propagation is parallel to the biasing magnetic filed. To validate the Z-transform algorithm, the reflection and transmission coefficients for the right-hand circularly polarized wave of the homogeneous magnetized plasma slab are computed by means of discrete Fourier transform. The comparison between the reflection and transmission coefficients of the homogeneous plasma slab and analytical values indicates that Z-transform algorithm is very accurate. When the plasma frequency varies according to the square root and parabolic relations, the reflection and transmission coefficients of the inhomogeneous magnetized plasma slab are computed. 展开更多
关键词 Finite-Difference Time-Domain (FDTD) Z-TRANSFORM Magnetized plasma
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Extended Mapping Transformation Method and Its Applications to Nonlinear Partial Differential Equation(s)
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作者 ZHAO Hong BAI Cheng-Lin 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第3X期473-478,共6页
In this paper, we extend the mapping transformation method through introducing variable coefficients.By means of the extended mapping transformation method, many explicit and exact general solutions with arbitrary fun... In this paper, we extend the mapping transformation method through introducing variable coefficients.By means of the extended mapping transformation method, many explicit and exact general solutions with arbitrary functions for some nonlinear partial differential equations, which contain solitary wave solutions, trigonometric function solutions, and rational solutions, are obtained. 展开更多
关键词 nonlinear partial differential equations extended mapping transformation method exact solutions
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10-Bit Single-Slope ADC with Error Calibration for TDI CMOS Image Sensor
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作者 高岑 姚素英 +2 位作者 杨志勋 高静 徐江涛 《Transactions of Tianjin University》 EI CAS 2013年第4期300-306,共7页
A 10-bit single-slope analog-to-digital converter (ADC) for time-delay-integration CMOS image sensor was proposed. A programmable ramp generator was applied to accomplish the error calibration and improve the linearit... A 10-bit single-slope analog-to-digital converter (ADC) for time-delay-integration CMOS image sensor was proposed. A programmable ramp generator was applied to accomplish the error calibration and improve the linearity. The ADC was fabricated in a 180 nm 1P4M CMOS process. Experimental results indicate that the differential nonlinearity and integral nonlinearity were 0.51/-0.53 LSB and 0.63/-0.71 LSB, respectively. The sampling rate of the ADC was 32 kHz. 展开更多
关键词 single-slope ADC error calibration CMOS image sensor
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Analytic solution to the magnetotelluric response over anisotropic medium and its discussion 被引量:3
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作者 QIN LinJiang YANG ChangFu CHEN Kun 《Science China Earth Sciences》 SCIE EI CAS 2013年第9期1607-1615,共9页
In the present paper,from the second order partial differential equations for solving the magnetotelluric(MT) fields of general anisotropic medium,we first obtained the second order partial differential equations for ... In the present paper,from the second order partial differential equations for solving the magnetotelluric(MT) fields of general anisotropic medium,we first obtained the second order partial differential equations for some anisotropic media with special conductivity(e.g.diagonal anisotropy,transverse anisotropy,azimuthal anisotropy,etc.) by simplifying the electrical conductivity tensor of anisotropic medium.And then we obtained the analytic solutions to MT fields for the case of transverse and azimuthal anisotropy through converting the conductivity parameter based on that of diagonal anisotropy.We further discussed the influence of the selection of integral limit and step length on precision in solving the analytic solutions for MT fields of isotropic medium.Finally,we presented the MT responses of two transverse and azimuthal anisotropic media as well as some applications of the analytic solutions to MT fields of anisotropic medium. 展开更多
关键词 Analytic solution to the magnetotelluric response over anisotropic medium and its discussion
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VARIABILITY SETS AND HAMILTON SEQUENCES
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作者 SUN NA WU SHENGJIAN 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2005年第4期543-550,共8页
This paper studies extremal quasiconformal mappings. Some properties of the variability set are obtained and the Hamilton sequences which are induced by point shift differentials are also discussed.
关键词 Quasiconformal mapping Point shift differentials Hamilton sequence Extremal mapping
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