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The Similarity Transformation of Regularizing Functionals and Simularity Property of Their Fourier Transformations
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作者 祝同江 《Journal of Beijing Institute of Technology》 EI CAS 1995年第2期105+99-105,共8页
Let and denote respectively the functionswhere λ≥1, The author discusses the similarity transformation of the regularizing functionals of these functions and the similar property of their Fourier transformation.
关键词 Fourier transform generalized functions/similarity transformation regularizing functionals
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ANALYSIS OF REMOTE SENSING ARCHAEOLOGY ON TRAFFIC FUNCTION TRANSFORMATION OF TONGJI GRAND CANAL IN SUI AND TANG DYNASTIES 被引量:5
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作者 WANG Xin-yuan HE Hui +2 位作者 ZHOU Ying-qiu GAO Chao HAN Shuang-wang 《Chinese Geographical Science》 SCIE CSCD 2006年第2期95-101,共7页
In China, most directions of river flowing are from west to east. During historic period, since the water traffic played an important role, it was very important to form a cross-horizontal net of water carriage route.... In China, most directions of river flowing are from west to east. During historic period, since the water traffic played an important role, it was very important to form a cross-horizontal net of water carriage route. Canals should be dug so as to make up the lack of north-south river. Tongji Grand Canal, dug in the first year of Daye (605 A.D.) in the Sui Dynasty, was the important component of north-south system of Grand Canals in China. It promoted economic and social development of the Sui, Tang and Song dynasties (605 A.D.-1279 A.D.). As Tongji Canal (i.e. Tongji Grand Canal) flowed across the Huaibei Plain, which is aggraded by abundant mud and sand deposit resulted from the Huanghe (Yellow) River flooding, many traces (such as old channel) and human culture heritages were buried under mud-sand. Tongji Canal was silted up, and disappeared in the Jin Dynasty (1115 A.D.-1234 A.D.). From then on, there were many different stories about the flowing route of the canal in historical literature. Based on space-bone and air-bone remote sensing imagery, we attempt to search the old channel of Tongji Canal, and supplement historical record. The paper discusses transformation process of Tongji Canal’s traffic function, and resumptively summarizes the reasons of the transformation, which results from synthetic function of physical geographical, political, economic, and social conditions. 展开更多
关键词 Tongji Canal Traffic Geography functional transformation remote sensing archaeology
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Comprehensive Reliability Allocation Method for CNC Lathes Based on Cubic Transformed Functions of Failure Mode and Effects Analysis 被引量:8
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作者 YANG Zhou ZHU Yunpeng +1 位作者 REN Hongrui ZHANG Yimin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第2期315-324,共10页
Reliability allocation of computerized numerical controlled(CNC)lathes is very important in industry.Traditional allocation methods only focus on high-failure rate components rather than moderate failure rate compon... Reliability allocation of computerized numerical controlled(CNC)lathes is very important in industry.Traditional allocation methods only focus on high-failure rate components rather than moderate failure rate components,which is not applicable in some conditions.Aiming at solving the problem of CNC lathes reliability allocating,a comprehensive reliability allocation method based on cubic transformed functions of failure modes and effects analysis(FMEA)is presented.Firstly,conventional reliability allocation methods are introduced.Then the limitations of direct combination of comprehensive allocation method with the exponential transformed FMEA method are investigated.Subsequently,a cubic transformed function is established in order to overcome these limitations.Properties of the new transformed functions are discussed by considering the failure severity and the failure occurrence.Designers can choose appropriate transform amplitudes according to their requirements.Finally,a CNC lathe and a spindle system are used as an example to verify the new allocation method.Seven criteria are considered to compare the results of the new method with traditional methods.The allocation results indicate that the new method is more flexible than traditional methods.By employing the new cubic transformed function,the method covers a wider range of problems in CNC reliability allocation without losing the advantages of traditional methods. 展开更多
关键词 CNC lathes reliability failure modes and effects analysis(FMEA) cubic transformed function comprehensive allocation
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An extended functional transformation method and its application in some evolution equations 被引量:2
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作者 丁海勇 徐西祥 杨宏祥 《Chinese Physics B》 SCIE EI CAS CSCD 2005年第9期1687-1690,共4页
In this paper, an extended functional transformation is given to solve some nonlinear evolution equations. This function, in fact, is a solution of the famous KdV equation, so this transformation gives a transformatio... In this paper, an extended functional transformation is given to solve some nonlinear evolution equations. This function, in fact, is a solution of the famous KdV equation, so this transformation gives a transformation between KdV equation and other soliton equations. Then many new exact solutions can be given by virtue of the solutions of KdV equation. 展开更多
关键词 extended functional transformation exact solution KdV equation
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结合坐标Transformer的轻量级人体姿态估计算法 被引量:1
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作者 黄友文 林志钦 +1 位作者 章劲 陈俊宽 《图学学报》 CSCD 北大核心 2024年第3期516-527,共12页
针对现有的大多数自底向上人体姿态估计算法存在模型规模大、计算成本高及对边缘设备不友好等问题,提出了一种基于YOLOv5s6-Pose的轻量级多人姿态估计网络模型YOLOv5s6-Pose-CT。该模型在颈部网络中引入空间和通道重建卷积,以减少空间... 针对现有的大多数自底向上人体姿态估计算法存在模型规模大、计算成本高及对边缘设备不友好等问题,提出了一种基于YOLOv5s6-Pose的轻量级多人姿态估计网络模型YOLOv5s6-Pose-CT。该模型在颈部网络中引入空间和通道重建卷积,以减少空间和通道维度上的特征冗余。同时,提出了一种坐标Transformer嵌入于主干网络中,使模型专注于长距离依赖和拥有高效的局部特征提取能力。其次,通过使用无偏特征位置对齐来解决多尺度融合过程中出现的特征错位问题。最后,使用损失函数MPDIoU对边界框的回归损失重新定义。在COCO 2017数据集上的实验结果表明,本文优化的网络模型与主流的轻量级网络EfficientHRNet-H1模型相比,在保持相同精度的同时,参数量和计算量分别减少16.2%和66.1%。相比于基准模型YOLOv5s6-Pose,参数量减少11.2%,计算量降低5.8%,平均检测精度和平均召回率分别提升2.5%和2.6%。 展开更多
关键词 人体姿态估计 轻量级 坐标transformer 无偏特征位置对齐 损失函数
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A whole-space transform formula of cylindrical wave functions for scattering problems 被引量:1
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作者 Yuan Xiaoming 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2014年第1期23-28,共6页
The theory of elastic wave scattering is a fundamental concept in the study of elastic dynamics and wave motion,and the wave function expansion technique has been widely used in many subjects.To supply the essential t... The theory of elastic wave scattering is a fundamental concept in the study of elastic dynamics and wave motion,and the wave function expansion technique has been widely used in many subjects.To supply the essential tools for solving wave scattering problems induced by an eccentric source or multi-sources as well as multi-scatters,a whole-space transform formula of cylindrical wave functions is presented and its applicability to some simple cases is demonstrated in this study.The transforms of wave functions in cylindrical coordinates can be classifi ed into two basic types: interior transform and exterior transform,and the existing Graf’s addition theorem is only suitable for the former.By performing a new replacement between the two coordinates,the exterior transform formula is fi rst deduced.It is then combined with Graf’s addition theorem to establish a whole-space transform formula.By using the whole-space transform formula,the scattering solutions by the sources outside and inside a cylindrical cavity are constructed as examples of its application.The effectiveness and advantages of the whole-space transform formula is illustrated by comparison with the approximate model based on a large cycle method.The whole-space transform formula presented herein can be used to perform the transform between two different cylindrical coordinates in the whole space.In addition,its concept and principle are universal and can be further extended to establish the coordinate transform formula of wave functions in other coordinate systems. 展开更多
关键词 scattering transform of wave functions whole-space transform eccentric source multi-sources multi-scatters
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Analysis of Ocean Wave Characteristic Distributions Modeled by Two Different Transformed Functions 被引量:2
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作者 Duanfeng Han Ting Cui +3 位作者 Yingfei Zan Lihao Yuan Song Ding Zhigang Li 《Journal of Marine Science and Application》 CSCD 2019年第3期247-259,共13页
The probability distributions of wave characteristics from three groups of sampled ocean data with different significant wave heights have been analyzed using two transformation functions estimated by non-parametric a... The probability distributions of wave characteristics from three groups of sampled ocean data with different significant wave heights have been analyzed using two transformation functions estimated by non-parametric and parametric methods. The marginal wave characteristic distribution and the joint density of wave properties have been calculated using the two transformations, with the results and accuracy of both transformations presented here. The two transformations deviate slightly between each other for the calculation of the crest and trough height marginal wave distributions, as well as the joint densities of wave amplitude with other wave properties. The transformation methods for the calculation of the wave crest and trough height distributions are shown to provide good agreement with real ocean data. Our work will help in the determination of the most appropriate transformation procedure for the prediction of extreme values. 展开更多
关键词 Wave characteristic DISTRIBUTIONS transformed GAUSSIAN process transformed function PARAMETRIC METHOD NON-PARAMETRIC METHOD Crossing-density function
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基于双向稀疏Transformer的多变量时序分类模型
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作者 王慧强 陈楚皓 +1 位作者 吕宏武 米海林 《小型微型计算机系统》 CSCD 北大核心 2024年第3期555-561,共7页
针对多变量时序(Multivariate Time Series,MTS)分类中长序列数据难以捕捉时序特征的问题,提出一种基于双向稀疏Transformer的时序分类模型BST(Bidirectional Sparse Transformer),提高了MTS分类任务的准确度.BST模型使用Transformer框... 针对多变量时序(Multivariate Time Series,MTS)分类中长序列数据难以捕捉时序特征的问题,提出一种基于双向稀疏Transformer的时序分类模型BST(Bidirectional Sparse Transformer),提高了MTS分类任务的准确度.BST模型使用Transformer框架,构建了一种基于活跃度得分的双向稀疏注意力机制.基于KL散度构建活跃度评价函数,并将评价函数的非对称问题转变为对称权重问题.据此,对原有查询矩阵、键值矩阵进行双向稀疏化,从而降低原Transformer模型中自注意力机制运算的时间复杂度.实验结果显示,BST模型在9个长序列数据集上取得最高平均排名,在临界差异图中领先第2名35.7%,对于具有强时序性的乙醇浓度数据集(Ethanol Concentration,EC),分类准确率提高30.9%. 展开更多
关键词 多变量时序分类 transformER 双向稀疏机制 活跃度评价函数
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Steganography based on wavelet transform and modulus function 被引量:1
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作者 Kang Zhiwei Liu Jing He Yigang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2007年第3期628-632,共5页
In order to provide larger capacity of the hidden secret data while maintaining a good visual quality of stego-image, in accordance with the visual property that human eyes are less sensitive to strong texture, a nove... In order to provide larger capacity of the hidden secret data while maintaining a good visual quality of stego-image, in accordance with the visual property that human eyes are less sensitive to strong texture, a novel steganographic method based on wavelet and modulus function is presented. First, an image is divided into blocks of prescribed size, and every block is decomposed into one-level wavelet. Then, the capacity of the hidden secret data is decided with the number of wavelet coefficients of larger magnitude. Finally, secret information is embedded by steganography based on modulus function. From the experimental results, the proposed method hides much more information and maintains a good visual quality of stego-image. Besides, the embedded data can be extracted from the stego-image without referencing the original image. 展开更多
关键词 STEGANOGRAPHY capacity wavelet transform modulus function HVS.
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Relation between Fresnel transform of input light field and the two-parameter Radon transform of Wigner function of the field 被引量:1
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作者 范洪义 胡利云 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第2期611-615,共5页
This paper proves a new theorem on the relationship between optical field Wigner function's two-parameter Radon transform and optical Fresnel transform of the field, i.e., when an input field ψ (x') propagates th... This paper proves a new theorem on the relationship between optical field Wigner function's two-parameter Radon transform and optical Fresnel transform of the field, i.e., when an input field ψ (x') propagates through an optical [D (-B) (-C) A] system, the energy density of the output field is equal to the Radon transform of the Wigner function of the input field, where the Radon transform parameters are D, B. It prove this theorem in both spatial-domain and frequency-domain, in the latter case the Radon transform parameters are A, C. 展开更多
关键词 Fresnel transform two-parameter Radon transform Wigner function
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On the Approximation of an Analytic Function Represented by Laplace-Stieltjes Transformation 被引量:1
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作者 Chhaya Singhal G.S.Srivastava 《Analysis in Theory and Applications》 CSCD 2015年第4期407-420,共14页
In the present paper,we have considered the approximation of analytic functions represented by Laplace-Stieltjes transformations using sequence of definite integrals. We have characterized their order and type in term... In the present paper,we have considered the approximation of analytic functions represented by Laplace-Stieltjes transformations using sequence of definite integrals. We have characterized their order and type in terms of the rate of decrease of E;(F,β) where E;(F,β) is the error in approximating of the function F(s) by definite integral polynomials in the half plane Res≤β<α. 展开更多
关键词 Laplace-Stieltjes transformation analytic function order TYPE approximation error
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结合Transformer与生成对抗网络的水下图像增强算法
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作者 袁红春 张波 程心 《红外技术》 CSCD 北大核心 2024年第9期975-983,共9页
由于水下环境的多样性和光在水中受到的散射及选择性吸收作用,采集到的水下图像通常会产生严重的质量退化问题,如颜色偏差、清晰度低和亮度低等,为解决以上问题,本文提出了一种基于Transformer和生成对抗网络的水下图像增强算法。以生... 由于水下环境的多样性和光在水中受到的散射及选择性吸收作用,采集到的水下图像通常会产生严重的质量退化问题,如颜色偏差、清晰度低和亮度低等,为解决以上问题,本文提出了一种基于Transformer和生成对抗网络的水下图像增强算法。以生成对抗网络为基础架构,结合编码解码结构、基于空间自注意力机制的全局特征建模Transformer模块和通道级多尺度特征融合Transformer模块构建了TGAN(generative adversarial network with transformer)网络增强模型,重点关注水下图像衰减更严重的颜色通道和空间区域,有效增强了图像细节并解决了颜色偏差问题。此外,设计了一种结合RGB和LAB颜色空间的多项损失函数,约束网络增强模型的对抗训练。实验结果表明,与CLAHE(contrast limited adaptive histogram equalization)、UDCP(underwater dark channel prior)、UWCNN(underwater based on convolutional neural network)、FUnIE-GAN(fast underwater image enhancement for improved visual perception)等典型水下图像增强算法相比,所提算法增强后的水下图像在清晰度、细节纹理和色彩表现等方面都有所提升,客观评价指标如峰值信噪比、结构相似性和水下图像质量度量的平均值分别提升了5.8%、1.8%和3.6%,有效地提升了水下图像的视觉感知效果。 展开更多
关键词 图像处理 水下图像增强 transformER 生成对抗网络 多项损失函数
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Local Extrema of Periodic Function’s Wavelet Transform 被引量:3
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作者 FAN Qi-bin SONG Xiao-yan 《Wuhan University Journal of Natural Sciences》 EI CAS 2005年第6期949-952,共4页
The theory of detecling ridges in the modulus of the continuous wavelet transform is presented as well as reconstructing signal by using information on ridges,To periodic signal we suppose Morlet wavelet as basic wave... The theory of detecling ridges in the modulus of the continuous wavelet transform is presented as well as reconstructing signal by using information on ridges,To periodic signal we suppose Morlet wavelet as basic wavelet, and research the local extreme point and extrema of the wavelet transform on periodic function for the collection of signal' s instantaneous amplitude and period. 展开更多
关键词 extrema periodic function wavelet transform time-frequency analysis
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Thermodynamic Functions and Phase Transformation of Metal Nanocrystals 被引量:2
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作者 Jinping GAO, Xiaoyan SONG , Jiuxing ZHANG, Keyong YANG and Xuemei LIUCollege of Materials Science and Engineering, the Key Laboratory of Advanced Functional Materials of the Education Ministry,Beijing University of Technology, Beijing 100022, China 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2005年第5期705-709,共5页
A model to calculate the thermodynamic functions of the pure metal nanocrystals has been developed, with the consideration of the effects of both the interfaces and the crystal in the nano-grain interior. As an exampl... A model to calculate the thermodynamic functions of the pure metal nanocrystals has been developed, with the consideration of the effects of both the interfaces and the crystal in the nano-grain interior. As an example, the enthalpy, entropy and Gibbs free energy, as functions of the excess free volume at interfaces, temperature and grain size, are calculated for the Co nanocrystals. Furthermore, the characteristics of β-Co→α-Co phase transformation are studied, and the transformation temperatures at different levels of grain size, as well as the critical grain sizes at different temperatures, are predicted. The calculation results show that, the nano-grained β-Co (fcc) is thermodynamically stable at temperatures much lower than that for the conventional coarse-grained materials, and may also stably exist at room temperature when the grain size is reduced to be small enough. The present model is verified by comparisons between the experimental findings and the theoretical predictions. 展开更多
关键词 Thermodynamic function Nanocrystal Phase transformation
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Characteristic Functional Structure of Infinitesimal Symmetry Transformations for Nonholonomic System 被引量:1
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作者 张宏彬 陈立群 《Journal of Shanghai University(English Edition)》 CAS 2005年第2期134-138,共5页
It was proved that velocity-dependent infinitesima l symmetry transformations of nonholonomic systems have a characteristic functio nal structure, which could be formulated by means of an auxiliary symmetry tra nsform... It was proved that velocity-dependent infinitesima l symmetry transformations of nonholonomic systems have a characteristic functio nal structure, which could be formulated by means of an auxiliary symmetry tra nsformation function and is manifestly dependent upon constants of motion of th e system. An example was given to illustrate the applicability of the results. 展开更多
关键词 analytical mechanics nonholonomic system velocity-dependent infinitesimal symmetry transformation characteristic functional structure constant of motion.
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Transfer Function Based Recognition of Resonance Overvoltages Transformer Windings 被引量:1
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作者 M. Florkowski J. Furgal 《高电压技术》 EI CAS CSCD 北大核心 2008年第12期2558-2563,共6页
Power transformer insulation systems are subjected to many stresses during normal operation due to lightning and switching.If the spectrum of incoming surge voltage matches the winding one,the corresponding resonance ... Power transformer insulation systems are subjected to many stresses during normal operation due to lightning and switching.If the spectrum of incoming surge voltage matches the winding one,the corresponding resonance will be excited.Therefore external transients occurring in power systems might trigger internal overvoltages with large maximum value in transformer windings.Overvoltages having such characteristic have been the root cause of many power transformer failures.The paper presents an approach to the identification of sensitive zones in the transformer windings based on the measurements of overvoltages inside windings and frequency dependences of admittance of the power transformer.The frequency characteristic of the transformer winding may determine those regions in the frequency spectrum.The presented approach might be used both for design optimization and diagnostics of distribution and power transformers. 展开更多
关键词 变压器 绕组 谐振 过电压识别 传输函数
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基于改进Transformer时序算法的区域经济预测
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作者 刘海宏 刘敏 朱岸青 《南京师大学报(自然科学版)》 CAS 北大核心 2024年第4期118-125,共8页
现有的区域经济预测模型指标变量存在冗余,且忽略了行业、区域等静态变量对预测结果的影响,导致预测效率不高.针对上述问题,提出了基于改进Transformer时序算法的区域经济预测模型.首先利用Copula函数对传统Transformer模型进行优化(Cof... 现有的区域经济预测模型指标变量存在冗余,且忽略了行业、区域等静态变量对预测结果的影响,导致预测效率不高.针对上述问题,提出了基于改进Transformer时序算法的区域经济预测模型.首先利用Copula函数对传统Transformer模型进行优化(Coformer);其次选取区域经济的影响指标,对其进行主成分分析,去除冗余信息;然后将降维后的指标变量和静态变量作为Coformer的输入,对变量进行编码,并通过多头注意力机制增强重要信息,最后用解码器对编码的变量解码,利用Softmax输出区域历年生产总值序列的预测结果.实验结果表明,所提模型的预测准确率为0.908,比另外三种模型分别提高了15.9%、12.3%和6.7%,表现出了优异的预测性能. 展开更多
关键词 区域经济预测 transformER COPULA函数 主成分分析 多头注意力
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THE WAVELET TRANSFORM OF PERIODIC FUNCTION AND NONSTATIONARY PERIODIC FUNCTION
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作者 刘海峰 周炜星 +2 位作者 王辅臣 龚欣 于遵宏 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2002年第9期1062-1070,共9页
Some properties of the wavelet transform of trigonometric Junction, periodic function and nonstationary periodic function have been investigated. The results show that the peak height and width in wavelet energy spect... Some properties of the wavelet transform of trigonometric Junction, periodic function and nonstationary periodic function have been investigated. The results show that the peak height and width in wavelet energy spectrum of a periodic function are in proportion to its period. At the same time, a new equation, which can truly reconstruct a trigonometric function with only one scale wavelet coefficient, is presented. The reconstructed wave shape of a periodic function with the equation is better than any term of its Fourier series. And the reconstructed wave shape of a class of nonstationary periodic function with this equation agrees well with the function. 展开更多
关键词 wavelet transform periodic function nonstationary periodic function Fourier transform
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Changes in Transformation of Soil Organic C and Functional Diversity of Soil Microbial Community Under Different Land Uses 被引量:22
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作者 LI Zhong-pei WU Xiao-chen CHEN Bi-yun 《Agricultural Sciences in China》 CAS CSCD 2007年第10期1235-1245,共11页
Changes in soil biological and biochemical properties under different land uses in the subtropical region of China were investigated in order to develop rational cultivation and fertilization management. A small water... Changes in soil biological and biochemical properties under different land uses in the subtropical region of China were investigated in order to develop rational cultivation and fertilization management. A small watershed of subtropical region of China was selected for this study. Land uses covered paddy fields, vegetable farming, fruit trees, upland crops, bamboo stands, and forestry. Soil biological and biochemical properties included soil organic C and nutrient contents, mineralization of soil organic C, and soil microbial biomass and community functional diversity. Soil organic C and total N contents, microbial biomass C and N, and respiration intensity under different land uses were changed in the following order: paddy fields (and vegetable farming) 〉 bamboo stands 〉 fruit trccs (and upland). The top surface (0-15 cm) paddy fields (and vegetable farming) were 76.4 and 80.8% higher in soil organic C and total N contents than fruit trees (and upland) soils, respectively. Subsurface paddy soils (15-30 cm) were 59.8 and 67.3% higher in organic C and total N than upland soils, respectively. Soil microbial C, N and respiration intensity in paddy soils (0-15 cm) were 6.36, 3.63 and 3.20 times those in fruit tree (and upland) soils respectively. Soil microbial metabolic quotient was in the order: fruit trees (and upland) 〉 forestry 〉 paddy fields. Metabolic quotient in paddy soils was only 47.7% of that in fruit tree (and upland) soils. Rates of soil organic C mineralization during incubation changed in the order: paddy fields 〉 bamboo stands 〉 fruit trees (and upland) and soil bacteria population: paddy fields 〉 fruit trees (and upland) 〉 forestry. No significant difference was found for fungi and actinomycetes populations. BIOLOG analysis indicated a changing order of paddy fields 〉 fruit trees (and upland) 〉 forestry in values of the average well cell development (AWCD) and functional diversity indexes of microbial community. Results also showed that the conversion from paddy fields to vegetable farming for 5 years resulted in a dramatic increase in soil available phosphorus content while insignificant changes in soil organic C and total N content due to a large inputs of phosphate fertilizers. This conversion caused 53, 41.5, and 41.3% decreases in soil microbial biomass C, N, and respiration intensity, respectively, while 23.6% increase in metabolic quotient and a decrease in soil organic C mineralization rate. Moreover, soil bacteria and actinomycetes populations were increased slightly, while fungi population increased dramatically. Functional diversity indexes of soil microbial community decreased significantly. It was concluded that land uses in the subtropical region of China strongly affected soil biological and biochemical properties. Soil organic C and nutrient contents, mineralization of organic C and functional diversity of microbial community in paddy fields were higher than those in upland and forestry. Overuse of chemical fertilizers in paddy fields with high fertility might degrade soil biological properties and biochemical function, resulting in deterioration of soil biological quality. 展开更多
关键词 land use patterns transformation of soil organic carbon functional diversity of soil microbial community
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Mechanisms of Transforming CH_x to CO on Ni(111) Surface by Density Functional Theory 被引量:1
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作者 Yingzhe Yu Hao Lei +1 位作者 Lingguang Wang Minhua Zhang 《Transactions of Tianjin University》 EI CAS 2019年第4期330-339,共10页
To elucidate feasible routes of producing CO from CH 3 and unravel the eff ect of adsorbed O on CH x transformation, the reactivity of CH x ( x = 1-3) with and without the assistance of adsorbed atomic O on Ni(111) wa... To elucidate feasible routes of producing CO from CH 3 and unravel the eff ect of adsorbed O on CH x transformation, the reactivity of CH x ( x = 1-3) with and without the assistance of adsorbed atomic O on Ni(111) was explored using density functional theory calculations. The adsorption energies of CH x ( x = 0-3) were found to be signifi cantly reduced on an O-preadsorbed Ni(111) surface compared to a pure surface. Furthermore, O-assisted one-step dehydrogenation of CH x ( x = 1-3) features energy barriers and thus is diffi cult to proceed. In terms of energy, the direct dissociation of CH 3 is favorable, except for the last CH dehydrogenation, which is energy intensive. Interestingly, in O-assisted two-step CH transformation to CO via CHO intermediate, the barrier is dramatically lowered. The successive dehydrogenations of CH x O ( x = 1-3) were also found to be a route for CO formation. Finally, two possible pathways from CH 3 to CO are proposed:(a) CH 3 → CH 2 → CH → CHO → CO;(b) CH 3 → CH 3 O → CH 2 O → CHO → CO. 展开更多
关键词 Density functional theory CH X transformation CO Ni(111)
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