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Simulation of multi-scale heterogeneity of porous media and parameter sensitivity analysis

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Science China(Technological Sciences) 2003年第5期46卷 459-474页

作者： ZHANg Yong (张勇) g.e. Fogg Hydrologic Science University of California Davis CA 95616-8627 USA Hydrologic Science University of California Davis CA 95616-8627 USA

Because of the inherent multi-scale heterogeneity of porous media and the limitation of single-subject observed data, we propose to combine deterministic and stochastic techniques to simulate heterogeneity. We select a coastal plain sediment system as an example to demonstrate and verify this approach. Firstly, we apply transition probability matrix to determine and delineate the nonstationary unconformity, and combine hydro-stratigraphy analyses to establish the field/large-scale, deterministic stratigraphy model. Secondly, we apply fence diagrams and CPT data to infer the horizontal mean length of hydrofacies, and then build Markov chain models for each depositional system and simulate the local/intermediate-scale, stochastic hydrofacies model. Finally, we combine the stratigraphy and hydrofacies models to get a multi-scale heterogeneous model embedded with quantitative and qualitative observed data, with both deterministic and stochastic characteristics. In order to study the influence of uncertainty in model parameters on solute transport, we build multiple realizations of two types of heterogeneous model and use them to simulate groundwater flow and solute transport. The parameter sensitivity analysis shows the 1st and 2nd spatial moments of the contaminant plume increase with the lateral average length of hydrofacies.

关键词： heterogeneity, scale, Markov-chain, mean-length.

Kinetic Study on CO_2 Reforming of Methane

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Chinese Journal of Chemical engineering 2001年第2期9卷 190-195页

作者： C.e.Quincoces M.g.gonzález CINDeCA Ctr Invest & Desarrollo Proc Catal RA-1900 La Plata Argentina

The kinetics of CO2 reforming of methane has been studied at 976－1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio ＞ 2. The Hougen-Watson rate models were fitted to experimental data assuming the disso ciative adsorption of methane as the rate-determining step. The reaction rate showed an effective reaction order of about unity for CH4. The apparent activity energy was found to be 104 kJ·mol-1. Therefore the kinetic reaction parameters were determined and a possible reaction mechanism was proposed.

关键词： CH4 reforming Ni catalysts syngas

Hierarchical closed form solutions for plates bent by localized transverse loadings

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2007年第7期8卷 1026-1037页

作者： CARReRA e. gIUNTA g. BRISCHeTTO S. Aeronautical and Space Department Politecnico di Torino c.so Duca degli Abruzzi 24 10129 Torino Italy

3D and 2D closed form plate models are here applied to static analysis of simply supported square isotropic plates. 2D theories are hierarchically classified on the basis of the accuracy of the displacements and stresses obtained by comparison to the 3D exact results that could be assumed by the reader as benchmark for further analyses. Attention is mainly paid on localized loading conditions, that is, piecewise constant load. Also bi-sinusoidal and uniformly distributed loadings are taken into account. All of those configurations are considered in order to investigate the behavior of the 2D models in the case of continu- ous/uncontinuous, centric or off-centric loading conditions. The ratio between the side length a and the plate thickness h has been assumed as analysis parameter. Higher order 2D models yield accurate results for any considered load condition in the case of moderately thick plates, a/h=10. In the case of thick plates, a/h=5, and continuous/uncontinuous centric loading conditions high accuracy is also obtained. For the considered off-centric load condition and thick plates good results are provided for some output quantities. A better solution could be achieved by simply increasing the polynomial approximation order of the axiomatic 2D displacement field.

关键词： exact 3D model Hierarchical 2D models Principle of Virtual Displacements (PVD) Localized loading Simply supported square isotropic plate

effects of V and Cr Addition on the Structural and Sensing Properties of Titania

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稀有金属材料与工程 2006年第A03期35卷 113-115页

作者： e.Comini I.Alessandri g.Faglia e.Bontempi L.e.Depero g.Sberveglieri Sensor Laboratory INFMUniversita'di Brescia25133 BRESCIAItaly Laboratorio di Chimica perle Tecnoiogie Universita'di Brescia25133 BRESCIAItaly

We have comparatively studied the addition of Cr and V in *** and V content were changed by means of insets placed in the Ti ***,compositional and electrical analyses of different series of thin films,made by XRF, XRD,are *** characterization not only showed that Cr doped layers were very sensitive to ethanol within a useful range for applications,but also allowed to verify that the electrical behaviour is dependent on the structure of film. Finally,the Cr and V concentrations that gives the best results in terms of sensing performances has been determined and a correlation between structural and electrical measurement has been evidenced.

关键词： titania V Cr ethanol sensors thin films

Modelling Mobile-X Architecture for Offloading in Mobile edge Computing

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Intelligent Automation & Soft Computing 2023年第4期36卷 617-632页

作者： g.Pandiyan e.Sasikala Department of Data Science and Business System SRM Institute of Science and TechnologyChennaiIndia

Mobile edge Computing(MeC)assists clouds to handle enormous tasks from mobile devices in close *** edge servers are not allocated efﬁciently according to the dynamic nature of the *** leads to processing delay,and the tasks are dropped due to time *** researchersﬁnd it difﬁcult and complex to determine the ofﬂoading decision because of uncertain load dynamic condition over the edge *** challenge relies on the ofﬂoad-ing decision on selection of edge nodes for ofﬂoading in a centralized *** study focuses on minimizing task-processing time while simultaneously increasing the success rate of service provided by edge ***,a task-ofﬂoading problem needs to be formulated based on the communication and *** ofﬂoading decision problem is solved by deep analysis on taskﬂow in the network and feedback from the devices on edge *** signiﬁcance of the model is improved with the modelling of Deep Mobile-X architecture and bi-directional Long Short Term Memory(b-LSTM).The simulation is done in the edgecloudsim environment,and the outcomes show the signiﬁcance of the proposed *** processing time of the anticipated model is 6.6 *** following perfor-mance metrics,improved server utilization,the ratio of the dropped task,and number of ofﬂoading tasks are evaluated and compared with existing learning *** proposed model shows a better trade-off compared to existing approaches.

关键词： Mobile edge computing cloud ofﬂoading delay task drop reinforcement learning mobile-X architecture

CSI and CSI7 Current Source Inverters for Modular Transformerless PV Inverters

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Chinese Journal of electrical engineering 2019年第2期5卷 32-42页

作者： e.Lorenzani g.Migliazza F.Immovilli g.Buticchi DISMI-Department of Science and Methods for engineering University of Modena and Reggio EmiliaReggio Emilia Italy Key Laboratory of More electric Aircraft Technology of Zhejiang Province University of Nottingham Ningbo ChinaNingbo 315100China

Current source inverter(CSI)is a class of power electronic converters that,thanks to the inherent boost capability and ease of control,is investigated for grid-tied photovoltaic power conversion *** CSI and CSI7 topologies are here analyzed and compared with two kind of space vector modulation strategies mainly in terms of ground leakage current both in simulations and ***,THD of the injected grid current and the computation of conduction and switching semiconductor power losses are also carried out in numerical *** topology comparison is carried out with the use of a different number of PV modules,to analyze the robustness of the topologies to different size of the PV *** and experimental results show that the CSI7 topology,with respect to conventional CSI,allows to strongly reduce ground leakage current,phase current THD and semicondutor power losses,at the price of an additional power device.

关键词： Current source inverter photo-voltaic power systems ground leakage current renewable energy sources

The Fourier space restricted Hartree-Fock method for the electronic structure calculation of linear poly(tetrafluoroethylene)

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Science China Chemistry 2014年第10期57卷 1355-1362页

作者： FRIPIAT Joseph g. HARRIS Frank e. Laboratoire de Chimie Théorique Unité de chimie physique théorique et structurale University of NamurRue de Bruxelles Department of Physics University of Utah Quantum Theory Project University of Florida

Building on the pioneering work of Jean-Marie Andre and working in the laboratory he founded, the authors have developed a code called FT-1D to make Hartree-Fock electronic structure computations for stereoregular polymers using ewald-type con- vergence acceleration methods. That code also takes full advantage of all line-group symmetries to calculate only the minimal set of two-electron integrals and to optimize the computation of the Fock matrix. The present communication reports a bench- mark study of the FT-1D code using polytetrafluoroethylene （PTFe） as a test case. Our results not only confirm the algorith- mic correctness of the code through agreement with other studies where they are applicable, but also show that the use of con- vergence acceleration enables accurate results to be obtained in situations where other widely-used codes （e.g., PLH and Crys- tal） fail. It is also found that full attention to the line-group symmetry of the PTFe polymer leads to an increase of between one and two orders of magnitude in the speed of computation. The new code can therefore be viewed as extending the range of electronic-structure computations for stereoregular polymers beyond the present scope of the successful and valuable code Crystal.

关键词： poly(tetrafluoroethylene) band structure Fourier-space Hartree-Fock lattice sum ewaid

Bell Polynomial Approach for the Solutions of Fredholm Integro- Differential equations with Variable Coefficients

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Computer Modeling in engineering & Sciences 2020年第6期123卷 973-993页

作者： gökçe Yıldız gültekin Tınaztepe Mehmet Sezer Department of Mathematics Faculty of ScienceManisa Celal Bayar UniversityManisaTurkey Vocational School of Technical Sciences Akdeniz UniversityAntalyaTurkey

In this article,we approximate the solution of high order linear Fredholm integro-differential equations with a variable coefficient under the initial-boundary conditions by Bell *** collocation points and treating the solution as a linear combination of Bell polynomials,the problem is reduced to linear system of equations whose unknown variables are Bell *** solution to this algebraic system determines the approximate *** estimation of approximate solution is *** examples are provided to illustrate the performance of the *** numerical results are compared with the collocation method based on Legendre polynomials and the other two methods based on Taylor *** is observed that the method is better than Legendre collocation method and as accurate as the methods involving Taylor polynomials.

关键词： Bell polynomials collocation points matrix method Fredholm integrodifferential equations.

Differences in reproductive endocrinology between Asian men and Caucasian men——a literature review

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Asian Journal of Andrology 2000年第1期2卷 13-20页

作者： M.e.vanHouten LouisJ.g.gooren Andrology Unit of the Department of endocrinology Hospital of the Vrije Universiteit Amsterdam the NetherlandsAndrology Unit of the Department of Endocrinology Hospital of the Vrije Universiteit Amsterdam the Netherlands

This review provides an overview of the literature on aspects of reproductive endocrinology wherein Asian menmay differ from Caucasian, notably, prostatic nioplasm and the sensivity to pharmacological regimens of male contra-ception. Both genetic and environmental factors, such as nutrition, might be relevant. Asian men residing in Asia seemto be relatively protected from clinical prostatic nioplasm while the prevalence of preclinical prostatic nioplasm is notdifferent. Migration to an area with a higher prevalence reduces this difference but does not undo it. With regard toprostatic nioplasm the following factors have been considered as relevant in Asian men: 1) a reduction in 5α-reductaselevel, 2) decreased levels of androgenic ketosteroid precursors of 5α-reduced androgen metabolites, 3) the decreasedpresence of a P53 mutation, 4) a higher CAg-repeat length of the androgen receptor, 5) a possible higher level ofphysical activity, 6) differences in sexual activity. Furthermore, Asian men respond to a higher degree with azoosper-mia in response to contraceptive steroids. Possible explanations offered for the more pronounced response to contracep-tive steroids are: 1) differences in testicular structure and decreased spermatogenic potential, 2) an earlier and moremarked suppression in LH secretion by exogenous androgens. The differences may be due to genetical and/or environ-mental factors influencing the peripheral testosterone metabolism. Dietary factors such as the higher intake of phytoe-strogens in Asians might exert effects on 5α-reductase activity and/or on sex hormone binding globulin (SHBg) levels,thus having an impact on the biological efficay of circulating androgens. ( Asian J Androl 2000; 2: 13 - 20)

关键词： ethnology Asian men Caucasian men prostatic neoplasms endocrinology male contraceptive agents androgen