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A high-order full-discretization method using Hermite interpolation for periodic time-delayed differential equations

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Acta Mechanica Sinica 2015年第3期31卷 406-415页

作者： Yilong Liu Achim Fischer Peter eberhard Baohai Wu Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Northwestern Polytechnical University Institute of Engineering and Computational Mechanics University of Stuttgart

A high-order full-discretization method （FDM） using Hermite interpolation （HFDM） is proposed and implemented for periodic systems with time delay. Both Lagrange interpolation and Hermite interpolation are used to approximate state values and delayed state values in each discretization step. The transition matrix over a single period is determined and used for stability analysis. The proposed method increases the approximation order of the semidiscretization method and the FDM without increasing the computational time. The convergence, precision, and efficiency of the proposed method are investigated using several Mathieu equations and a complex turning model as examples. Comparison shows that the proposed HFDM converges faster and uses less computational time than existing methods.

关键词： Full-discretization method Time delay -Stability Chatter

Sperm crisis： what crisis？

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Asian Journal of Andrology 2013年第2期15卷 184-186,I0005页

作者： eberhard Nieschlag Alexander Lerchl Centre of Reproductive Medicine and Andrology University of MOnster MOnster 48129 Germany School of Engineering and Science Jacobs University Bremen Bremen 28759 Germany

For 20 years the so-called ＂sperm crisis＂ caused unrest among the public as well as the scientific community. Studies precipitated by this virtual crisis have refuted its existence, but have also illuminated hitherto neglected aspects of male reproductive function and indicated a need for prospective, long-term monitoring systems.

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An Indian Quasi-Fregean Theory of Number

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Fudan Journal of the Humanities and Social Sciences 2019年第3期12卷 329-351页

作者： eberhard Guhe Fudan University Shanghai China

A very interesting account of the reference of number words in classical Indian philosophy was given by Mahesa Chandra (1836 -1906) in his Brief Notes on the Modern Nyaya System of Philosophy and its Technical Terms (BN), a primer on NavyaNyaya terminology and doctrines. Despite its English title, BN is a Sanskrit work. The section on"number"(samkhya) provides an exposition of a theory of number which can account for both the adjectival and the substantival use of number words in Sanskrit. According to D. H. H. Ingalls (19161999), some ideas about the reference of number words in BN are close to the FregeRussell theory of natural number. Ingalls's comparison refers to a concept of number in Navya-Nyaya which is related to the things numbered via the SO called"circumtaining relation"(paryapti). Although there is no theory of sets in Navya-Nyaya, Navya-Naiyayikas do have a realist theory of properties (dharma) and their theory of number is a theory of properties as constituents of empirical reality, anchored to their system of ontological categories. As shown by George Bealer, properties can serve the same purpose as sets in the Frege -Russell theory of natural number. In the present paper, we attempt a formal reconstruction of Mahesa Chandra's exposition of the Navya-Nyaya theory of number, which accounts for its affinity to George Bealer's neo-Fregean analysis. As part of our appraisal of the momentousness and robustness of the"circumtaining"concept of number, we show that it can be cast into a precise recursive definition of natural number and we prove property versions of Peano's axioms from this definition.

关键词： Navya-Nyaya Natural numbers Frege Property theories Peano's axioms

Modelling of dust emissions induced by flow over stockpiles and through packed beds

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Particuology 2021年第6期19卷 55-63页

作者： Daniel Schulz Nadja Schwindt eberhard Schmidt Harald Kruggel-Emden Technische Universitat Berlin Chair of Mechanical Process Engineering and Solids ProcessingEmst-Reuter-Platz 1D-10587 BerlinGermany University of Wuppertal Institute of Particle TechnologyRainer-Gruenter-StrGeb.FFD-42119 WuppertalGermany

Dust emissions during storage of non-moving bulk materials are studied with a numerical *** model relies on a contact-model-free Discrete Element Method(DEM)to model the bulk particle-fluid interaction and the dust removal coupled with Computational Fluid Dynamics(CFD)to model the gas and the dust phase in a multiphase ***,two storage scenarios are considered:a flown through packed bed and a flown over *** the first,the performed simulations reveal that the dust discharge can be correlated with the passing fluid pressure *** the second,a parameter study of factors influencing the dust emissions is *** parameters discussed are the stockpile size,the gas velocity,the slope angle,the particle diameter and the shape of the stockpile,taking into account conical and truncated conical *** release correlations are obtained for both scenarios,which reflect very well the obtained numerical results.

关键词： Computational Fluid Dynamics(CFD) Discrete Element Method(DEM) Dust release correlations Stockpile emissions Packed bed emissions

Liver transplantation and non-alcoholic fatty liver disease

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World Journal of Gastroenterology 2014年第42期20卷 15532-15538页

作者： Petros Zezos eberhard L Renner Liver Transplant Program/Multi-Organ Transplant Program University Health Network/Toronto General Hospital University of Toronto

Non-alcoholic fatty liver disease(NAFLD) is an important health problem worldwide. NAFLD encompasses a histological spectrum ranging from bland liver steatosis to severe steatohepatitis(nonalcoholic steatohepatitis, NASH) with the potential of progressing to cirrhosis and its associated morbidity and mortality. NAFLD is thought to be the hepatic manifestation of insulin resistance(or the metabolic syndrome); its prevalence is increasing worldwide in parallel with the obesity epidemic. In many developed countries, NAFLD is the most common cause of liver disease and NASH related cirrhosis is currently the third most common indication for liver transplantation. NASH related cirrhosis is anticipated to become the leading indication for liver transplantation within the next one or two decades. In this review, we discuss how liver transplantation is affected by NAFLD, specifically the following:(1) the increasing need for liver transplantation due to NASH;(2) the impact of the increasing prevalence of NAFLD in the general population on the quality of deceased and live donor livers available for transplantation;(3) the long term graft and patient outcomes after liver transplantation forNASH,and finally;and(4)the de novo occurrence of NAFLD/NASH after liver transplantation and its impact on graft and patient outcomes.

关键词： Liver transplantation Non-alcoholic fatty liver disease Hepatic steatosis Steatohepatitis Liver cirrhosis Metabolic syndrome Insulin resistance Obesity

A-posteriori error estimation for second order mechanical systems

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Acta Mechanica Sinica 2012年第3期28卷 854-862页

作者： Thomas Ruiner Jrg Fehr Bernard Haasdonk Peter eberhard Institute of Engineering and Computational Mechanics University of StuttgartPfaffenwaldring 970569 StuttgartGermany Institute of Applied Analysis and Numerical Simulation University of StuttgartPfaffenwaldring 5770569 StuttgartGermany

One important issue for the simulation of flexible multibody systems is the reduction of the flexible bodies de- grees of freedom. As far as safety questions are concerned knowledge about the error introduced by the reduction of the flexible degrees of freedom is helpful and very important. In this work, an a-posteriori error estimator for linear first order systems is extended for error estimation of me- chanical second order systems. Due to the special second order structure of mechanical systems, an improvement of the a-posteriori error estimator is achieved. A major advan- tage of the a-posteriori error estimator is that the estimator is independent of the used reduction technique. Therefore, it can be used for moment-matching based, Gramian matrices based or modal based model reduction techniques. The capability of the proposed technique is demon- strated by the a-posteriori error estimation of a mechanical system, and a sensitivity analysis of the parameters involved in the error estimation process is conducted.

关键词： A-posteriori error estimator. Flexible multibodysystems Model reduction

Stability analysis of a thin-walled cylinder in turning operation using the semi-discretization method

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Acta Mechanica Sinica 2014年第2期30卷 214-222页

作者： Arnab Chanda Achim Fischer Peter eberhard Santosha Kumar Dwivedy Institute of Engineering and Computational Mechanics University of Stuttgart

In this work, the stability of a flexible thin cylindrical workpiece in turning is analyzed. A process model is derived based on a finite element representation of the workpiece flexibility and a nonlinear cutting force law. Repeated cutting of the same surface due to overlapping cuts is modeled with the help of a time delay. The stability of the so obtained system of periodic delay differential equations is then determined using an approximation as a time-discrete system and Floquet theory. The time-discrete system is obtained using the semi-discretization method. The method is implemented to analyze the stability of two different workpiece models of different thicknesses for different tool positions with respect to the jaw end. It is shown that the stability chart depends on the tool position as well as on the thickness.

关键词： Machine tools Stability Chatter

An LSTM‐based approach to precise landing of a UAV on a moving platform

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International Journal of Mechanical System Dynamics 2022年第1期2卷 99-107页

作者： Wei Luo Henrik Ebel Peter eberhard Institute of Engineering and Computational Mechanics University of StuttgartStuttgartGermany

A machine learning‐based method for the precise landing of an unmanned aerial vehicle on a moving mobile platform is *** proposed approach attempts to predict the mobile platform's future trajectory based on the past states of the mobile *** that end,it combines a long short‐term memory‐based neural network with a Kalman ***,it aims at combining the advantages of a machine learning method with those of a state estimation method from established control *** on the predicted trajectory,the unmanned aerial vehicle attempts to land precisely on the moving mobile *** experiment is conducted in the Gazebo simulation platform with a quadrotor and an omni-directional mobile robot,and the proposed method is compared with the single‐method approaches of using only either the Kalman filter or the machine learning method alone.

关键词： Kalman filter long short‐term memory(LSTM) trajectory prediction unmanned aerial vehicle(UAV)

Physics of Interplanetary Dust

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紫金山天文台台刊 1996年第3期15卷 32-51页

作者： eberhard Grun Max-Pi anck-Institut fur Kernphysik 69117 Heidel berg.Germany

Zodiacal light is a promient light phenomenon to the human eye in the morning andevening sky in non-polluted areas. Already in 1683 Cassini presented the correct explanation ofthis phenomenon: it is sun light scattered by dust particles orbiting the sun. The reistion toother "dusty" interplanetary phenomena,like comets was soon suspected. Comets shed

关键词：山砂加压山岭血肠沙州比面加力山口日场衡山