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Numerical modelling of resonance mechanisms in jointed rocks using transfer functions

Journal of Rock Mechanics and Geotechnical Engineering 2023年第5期15卷 1076-1089页

作者： Harry Holmes Chrysothemis Paraskevopoulou Mark Hildyard Krishna Neaupane David P.Connolly School of Earth and Environment University of LeedsLeedsLS29JTUK AECOM Ltd. ChesterfieldS417SLUK

Resonance effects in parallel jointed rocks subject to stress waves are investigated using transfer functions,derived from signals generated through numerical *** is important for a range of engineering situations as it identifies the frequency of waves which will be favourably *** different numerical methods are used for this study,adopting the finite difference method and the combined discrete element-finite difference *** numerical models are validated by replicating results from previous *** two methods are found to behave similarly and show the same resonance effects;one operating at low frequency and the other operating at relatively high *** resonance effects are interpreted in terms of simple physical systems and analytical equations are derived to predict the resonant frequencies of complex rock *** frequency resonance is shown to be generated by a system synonymous with masses between springs,described as spring resonance,with an equal number of resonant frequencies as the number of *** frequency resonance is generated through superposition of multiple reflected waves developing standing waves within intact blocks,described as superposition *** resonance through superposition has previously been identified,resonance based on masses between springs has not been previously identified in jointed *** findings of this study have implications for future analysis of multiple jointed rock masses,showing that a wave travelling through such materials can induce other modes of propagation of waves,*** resonance.

关键词： Resonance Jointed rocks Finite difference method Discrete element transfer functions Wave propagation

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Modern pollen distributions in Qinghai-Tibetan Plateau and the development of transfer functions for reconstructing Holocene environmental changes

Modern pollen distributions in Qinghai-Tibetan Plateau and t...

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中国科学院地质与地球物理研究所第11届（2011年度）学术年会

作者： Houyuan Lu~(a,*),Naiqin Wu~a,Kam-biu Liu~b,Liping Zhu~c,Xiangdong Yang~d,Tandong Yao~c,Luo Wang~a, Quan Li~a,Xingqi Liu~d,Caiming Shen~e,Xiaoqiang Li~f,Guobang Tong~g,Hui Jiang~h aKey Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China b Department of Oceanography and Coastal Sciences,Louisiana State University,Baton Rouge,LA 70803,USA cInstitute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100085,China d State Key Laboratory of Lake Science and Environment,Nanjing Institute of Limnology and Geography,Chinese Academy of Sciences,Nanjing 210008,China e Atmospheric Sciences Research Center,State University of New York,Albany,NY 12203,USA f Institute of Vertebrate Paleontology and Paleoanthropology,Chinese Academy of Sciences,Beijing 100044,China g Institute of Hydrology and Geology,Chinese Academy of Geological Sciences,Zhengding 050803,China h State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 200062,China

This study investigates the distribution of modern pollen assemblages in the Qjnghai-Tibetan Plateau, China,based on surface soil samples collected at 1202 sites along an altitudinal gradient of 10 -5500 m asl,where mean annual precipitation(MAP) ranges from 12 to 1840 mm and mean annual temperature(MAT) from -1 to 21.5℃.A total of 153 pollen taxa were found with relative abundances greater than 1%in at least two *** correspondence analysis(CCA) was used to determine the main environmental variables influencing pollen *** results reveal that MAP is the most significant dominant ***,MAT,altitude(ALT),July temperature(MT7),and relative humidity(HHH) are also significant variables that clearly follow the gradients in the CCA ordination, suggesting that pollen assemblages probably not only reflect a single climatic parameter,but also a variety of other climatic inter-related parameters. transfer functions,based on locally weighted weighted averaging(LWWA),were developed for MAP (R-boot = 0.89,RMSEP = 109 mm),MAT(R-boot = *** = 2.3℃),ALT(R-boot = 0.73, RMSEP = 597 m),HHH(R-boot = 0.82,RMSEP = 4.5%),and July mean precipitation(MP7)(R- boot = 0.87,RMSEP = 23 ram).Overall,our results confirm that pollen can provide reliable estimates of the primary climatic *** application of the LWWA model to the fossil records of Chen Co Lake allowed quantitative inferences to be made about Holocene climatic changes in the southern Tibetan Plateau,suggesting that LWWA is a robust calibration method for quantitative palaeo-environ-mental reconstruction based on pollen data in the regions.

关键词： Qinghai-Tibetan plateau Vegetation Pollen transfer functions Holocene Climatic changes

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Nullors, and Nullor Circuits;There Applications in Symbolic Circuit Analysis and Design

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Applied Mathematics 2024年第1期15卷 33-45页

作者： Reza Hashemian Reza Hashemian Northern Illinois University Dekalb USA

The objective in this presentation is to introduce some of the unique properties and applications of nullors in active circuit analysis and designs. The emphasis is to discuss the role nullors can play in symbolic representation of transfer functions. To show this we adopt the topological platform for the circuit analysis and use a recently developed Admittance Method (AM) to achieve the Sum of Tree Products (STP), replacing the determinant and cofactors of the Nodal Admittance Matrix (NAM) of the circuit. To construct a transfer function, we start with a given active circuit and convert all its controlled sources and I/O-ports to nullors. Now, with a solid nullor circuit (passive elements and nullors) we first eliminate the passive elements through AM operations. This produces the STPs. Second, the all-nullor circuit is then used to find the signs or the STPs. Finally, the transfer function (in symbolic, if chosen) is obtained from the ratio between the STPs.

关键词： Admittance Method Analog Circuits Nullors Nullor Circuits Sum of Tree Products transfer functions

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A 2nd-Order Noise Shaping SAR ADC Realizing NTF Zero-Pole Optimization Based on IIR-FIR Filter

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Chinese Journal of Electronics 2022年第1期31卷 33-39页

作者： ZHANG Yanbo LIU Shubin LIANG Yuhua ZHU Zhangming School of Microelectronics Xidian University

This paper reports a successive approximation register(SAR) analog-to-digital converters(ADCs) with the 2 nd-order and optimized noise shaping(NS) scheme. Based on the feed-forward structure, both noise transfer function(NTF) zero and pole optimization have been achieved simultaneously utilizing a cascaded IIR-FIR(infinite impulse response and finite impulse response) filter. The analysis shows that the proposed structure provides a better NS efficiency than prior arts. The efficiency of the proposed NS scheme and the ADC performance are verified by simulation achieving a 14.2 effective number of bits with an 8-bit SAR ADC architecture at an over sampling rate of 8 sampled at 100 MS/*** advantage of the NTF zero-pole optimization, a low resolution SAR ADC is allowed under the same quantization noise budget in this structure.

关键词： 2nd-order noise shaping SAR ADC architecture quantization noise budget optimisation infinite impulse response NTF zero-pole optimization cascaded IIR-FIR filter transfer functions FIR filters analogue-digital conversion NS scheme noise transfer function zero feedforward structure analog-to-digital converters IIR filters finite impulse response

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New tracking-differentiator design and analysis of its stability and convergence

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Journal of Systems Engineering and Electronics 2004年第4期15卷 780-787页

作者： QiGuoyuan ChenZengqiang YuanZhuzhi DepartmentofAutomation TianjinUniversityofScience&TechnologyTianjin300222P.R.China//DepartmentofAutomationNankaiUniversityTianjin300071P.R.China DepartmentofAutomation NankaiUniversityTianjin300071P.R.China

A new simple linear tracking-differentiator (T-D) is presented. Stability and convergence of the T-D are thoroughly proved, which avoids inconvenience of stability proof for nonlinear T-D with switch function. Through error analysis, the presented T-D can extract differential of any piecewise smooth nonlinear signals to reach a high accuracy. Compared with the nonlinear T-D with switch function, shaking phenomenon is avoided at the switching point of the function. By further modifying the linear T-D, it can effectively restrain differential impulses produced by initial errors of signals or by signals suddenly changing. Finally, analysis of several simulation examples shows the effectiveness of the proposed theory.

关键词： Convergence Stability analysis transfer functions Error analysis Accuracy Asymptotic stability Switches

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Design of an Interpolated Controller for Stabilization of a Plant with Variable Operating Condition

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Journal of Systems Engineering and Electronics 2000年第2期11卷 39-47页

作者： Yuan, Xiangyang Shi, Songjiao Ikeda, Masao Shanghai Jiaotong Univ Shanghai China

In this paper, the stabilization of a linear SISO plant with variable operating condition is considered. The plant is described by a linear interpolation of proper stable co-prime factorizations of the transfer functions at two representative operating points. An interpolation of the stabilizing controllers for the representative models is designed to stabilize the plant, and the necessary and sufficient condition for the plant to be stabilized by the proposed controller is presented using the Nevanlinna-Pick interpolation theory. It is shown that the class of stabilization plants via the proposed controller in the paper is larger than that by the controller in reference. An example is also given to illustrate this fact.

关键词： Closed loop control systems Control system analysis Interpolation System stability transfer functions

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Optimal closed-loop identification test design for internal model control

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Journal of Systems Engineering and Electronics 2004年第4期15卷 615-619页

作者： ZhangLiqun ShaoHuihe DaiDan DepartmentofAutomation ShanghaiJiaotongUniversityShanghai413130P.R.China

In this paper, optimal closed-loop test design for control is studied. The identified model is used for controller design. The control scheme used is internal model control (IMC) and the design constraint is the power of the process output or that of the reference signal. The measure of performance is the variance of the error between the output of the ideal closed-loop system (with the ideal controller) and that of the actual closed-loop system (with the controller computed from the identified model). Optimal spectrum formulae can be used to determine the PRBS signal in industrious identification.

关键词： Process control Computational modeling Predictive models transfer functions System identification Power generation

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Stability Improvement for One Cycle Controlled Boost Converters Based on Energy Balance Principle

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Chinese Journal of Electronics 2023年第6期32卷 1293-1303页

作者： WANG Lei WU Qinghua MA Wei TANG Wenhu Guangzhou Maritime University South China University of Technology (SCUT) Chongqing University of Science and Technology

Boost converters with one cycle control(OCC) are prone to exhibit oscillations as the Hopf bifurcation, which may degrade performances and limit the parameter stable region of converters. This work proposed a novel control strategy for suppressing such bifurcations and enlarging the parameter stability region of the boost system on the basis of the principle of energy balance in the circuit. Through analyzing of the stability and bifurcation condition, the results reflect that, the energybased OCC can adjust the poles of the system transfer function, which ensures the stable operation of the system in an extended range of circuit parameters. Moreover,the orders of the transfer function will not be increased by such adjustments, thus the computational complexity of the transfer function will be increased. The theoretical analysis demonstrates the ability of the energy-based OCC for suppressing the bifurcations and enlarging the stable region of the system parameters. The results by simulation and experiment further prove the effectiveness of the proposed control strategy.

关键词： transfer functions Bifurcation Stability analysis Circuit stability Computational complexity Oscillators

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A preliminary study of the quantitative couplingbetween loess-paleosol sequences and summermon soon changes

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Journal of Geographical Sciences 1999年第4期9卷 394-401页

作者： HAO Yong-ping FANGXiao-min LIJi-jun(LREIS, Institute of Geography, CAS, Beijing 100101 China: Dept. of Geography, LanzhouUniversity, Lanzhou 730000, China)

The Loess Plateau-Northeastern Tibetan Plateau in China is famous for its deep andcontmuous distributed loess, in which soils (developed from loess) vary gradually with differentbiological climates changing from subhumid to arid, which provide a natural proving ground forstUd}' the coupling of loess-paleosol and climatic changes quantitatively. Thirty-two sections weresampled (collected) for measuring chemical element contents, clay content (and other items) and 60sections were collected for carbonate analysis to establish transfer functions between pedogenesisand climate. Finally, we estimated the paleoclAnate (P/T) in the region with transfer functions,It isrevealed that the variation of paleocldriate reflected by transfer functions accorded closely with theclimatic pattern resulted from recent work. Specifically, it was about 140 ha BP that summermonsoon reached Lanzhou or further, paleosol S1 (equaling to MIS 5 in deep sea records) developedstrongly in a large scale, even touching upon northeanstern Tibetan Plateau. And, the estimated P/Tinformation also indicated the cold and humid period during 50-30 ka BP, mean annual Precipitationwas about 400-500 nun in Angutan recorded by mega-interstadial paleosol Sm.

关键词： Loess Plateau, northeastern Tibetan Plateau pedogedsis loess-paleosol sequences,summer monsoon transfer functions

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基于个体张量分解与模态的头相关传输函数重构

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声学学报 2023年第1期48卷 215-224页

作者：赵童谢菠荪朱俊梁林达华南理工大学物理与光电学院声学研究所

远场头相关传输函数(HRTF)随声源方向、频率以及个体变化。完整HRTF的数据量很大,且测量或计算每个人的高方向分辨率HRTF是很困难的。本文提出一种从少量方向的测量或计算重构高方向分辨率HRTF的方法。基于HRTF张量分解,远场HRTF可分解... 详细信息

远场头相关传输函数(HRTF)随声源方向、频率以及个体变化。完整HRTF的数据量很大,且测量或计算每个人的高方向分辨率HRTF是很困难的。本文提出一种从少量方向的测量或计算重构高方向分辨率HRTF的方法。基于HRTF张量分解,远场HRTF可分解为方向模态、频率模态和少量个体模态的张量组合。通过对已有的基线HRTF数据库进行统计分析,可得到与个体无关的方向模态矩阵和频率模态矩阵。而对于任何新的个体,只要少量方向的测量或计算HRTF即可估计出个体模态的变化,并重构出高方向分辨率的HRTF数据。对两个HRTF数据库的计算表明,采用11个个体模态即可表示超过98%的个体相关的HRTF能量变化,并从大约30个方向的测量或计算HRTF重构出高方向分辨率的HRTF幅度。心理声学实验验证了提出的方法。该方法可用于简化个性化HRTF的测量或计算。

关键词： transfer functions

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