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MONOTONE APPROXIMATION TO A SYSTEM WITHOUT MONOTONE NONLINEARITY

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Journal of Computational Mathematics 2000年第2期18卷 207-224页

作者： Yuan-ming Wang ben-yu Guo Department of Mathematics East China Normal UniversityShanghai 200062China School of Mathematical Sciences Shanghai Normal UniversityShanghai 200234China

Presents information on a study which proposed a monotone approximation for a system without monotone nonlinearity. Concept of ordered pair of supersolution and subsolution for the resulting problem; Numerical results.

关键词： monotone approximation systems without monotone nonlinearity

A review of the current state of biofuels production from lignocellulosic biomass using thermochemical conversion routes

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Chinese Journal of Chemical Engineering 2019年第7期27卷 1523-1535页

作者： Paola Ibarra-Gonzalez ben-Guang Rong Department of Chemical Engineering Biotechnology and Environmental Technology University of Southern Denmark

The rapid increase in energy demand,the extensive use of fossil fuels and the urgent need to reduce the carbon dioxide emissions have raised concerns in the transportation *** renewable and sustainable sources have become the ultimate solution to overcome the expected depletion of fossil *** conversion of lignocellulosic biomass to liquid(BtL)transportation fuels seems to be a promising path and presents advantages over first generation biofuels and fossil ***,development of BtL systems is critical to increase the potential of this resource in a sustainable and economic *** of lignocellulosic BtL transportation fuels,such as,gasoline,diesel and jet fuel can be accomplished through various thermochemical processes and processing *** major steps for the production of BtL fuels involve feedstock selection,physical pretreatment,production of bio-oil,upgrading of bio-oil to transportation fuels and recovery of value-added *** present work is aiming to give a comprehensive review of the current process technologies following these major steps and the current scenarios of biomass to liquid facilities for the production of biofuels.

关键词： Biofuels Lignocellulosic biomass Process route Thermochemical conversion Upgrading Separation

Automatic Fall Detection Using Membership Based Histogram Descriptors

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Journal of Computer Science & Technology 2017年第2期32卷 356-367页

作者： Mohamed Maher ben Ismail Ouiem Bchir College of Computer and Information Sciences King Saud University Riyadh 11495 KSA

t We propose a framework for automatic fall detection based on video visual feature extraction. The proposed approach relies on a membership histogram descriptor that encodes the visual properties of the video frames. This descriptor is obtained by mapping the original low-level visual features to a more discriminative descriptor using possibilistic memberships. This mapping can be summarized in two main phases. The first one consists in categorizing the low-level visual features of the video frames arid generating homogeneous clusters in an unsupervised way. The second phase uses the obtained membership degrees generated by the clustering process to compute the membership based histogram descriptor （MHD）. For the testing stage, the proposed fall detection approach categorizes unlabeled videos as ＂Fall＂ or ＂Non-Fall＂ scene using a possibilistic K-nearest neighbors classifier. The proposed approach is assessed using standard videos dataset that simulates patient fall. Also, we compare its performance with that of state-of-the-art fall detection techniques.

关键词： fall detection possibilistic approach feature extraction clustering

Numerical study on shock-accelerated heavy gas cylinderswith diffusive interfaces

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Acta Mechanica Sinica 2019年第4期35卷 750-762页

作者： Dongdong Li ben Guan Ge Wang College of Aerospace and Civil Engineering Harbin Engineering University Harbin 150001 China

Interactions of shock wave and heavy gas cylinders with different diffusive interfaces are numerically investigated. Comparisons among these interfaces are made in terms of cylinder morphology, wave system evolution, fluids mixing, and circulation generation. Navier-Stokes equations are solved in the present work to simulate the complex multi-fluid flow. The fifth-order weighted essentially non-oscillatory scheme is used to compute the numerical flux. The influence of interface diffusion is revealed by the numerical results. The cylinders with similar geometric scale but different diffusion interface have great similarities in the hydrodynamic characteristics, including the interface morphology, shock focusing and molecular mixing, as well as circulation deposition. For the cases with more serious interface diffusion, the cylinder develops into more regular vortex pairs. The diffusive interface greatly mitigates the strength of the reflected shock wave and weakens the shock focusing capability. Some interface structural features are also recorded and analyzed. The diffusive interface brings about slower molecular mixing and less circulation generation. The circulation deposition on different interfaces is quantitatively investigated and compared with the theoretical models. The theoretical models are found to be applicable to the scenarios of diffusive interfaces.

关键词： Shock bubble interaction Interfacial instability Diffusive interface Circulation model

MODELING AND FORECASTING OF STOCK MARKETS UNDER A SYSTEM ADAPTATION FRAMEWORK

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Journal of Systems Science & Complexity 2012年第4期25卷 641-674页

作者： Xiaolian ZHENG ben M.CHEN The Department of Electrical & Computer Engineering The National University of Singapore

This paper adopts the concept of dynamic feedback systems to model the behavior of financial markets, or more specifically, the stock market from a dynamic system point of view. Based on a feedback adaptation scheme, the authors model the movement of a stock market index within a framework that is composed of an internal dynamic model and an adaptive filter. The output-error model is adopted as the internal model whereas the adaptive filter is a time-varying state space model with instrumental variables. Its input-output behavior, and internal as well as external forces are then identified. Special attention has also been paid to the recent financial crisis by examining the movement of Dow Jones Industrial Average （DJIA） as an example to illustrate the advantage of the proposed framework. Supported by time-varying causality tests, five influential factors from economic and sentiment aspects are introduced as the input of this framework. Testing results show that the proposed framework has a much better prediction performance than the existing methods, especially in complicated economic situations. An application of this framework is also presented with focuses on forecasting the turning periods of the market trend. Realizing that a market trend is about to change when the external force begins to exhibit clear patterns in its frequency responses, the authors develop a set of rules to recognize this kind of clear patterns. These rules work well for stock indexes from US, China and Singapore.

关键词： Complex systems financial modeling financial systems market forecasting system economics.

Study of the Inhibitor Scaling Effect of the Agricultural Water by a Phosphate Fertilizer

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Journal of Water Resource and Protection 2015年第15期7卷 1234-1241页

作者： abdallah Hadfi Said ben-Aazza M’barek Belaatar Naima Hafid Ali Driouiche Department of Chemistry Team “Materials and Physical Chemistry of Water” Faculty of Science University Ibn Zohr Agadir Morocco

The localised irrigation or drop by drop system is a technique which makes it possible to save water, because it ensures a balanced and efficient distribution of water and an effective fertilization. However, this ferti-irrigation system is facing a number of problems hindering the agricultural development. The lack of uniformity of the localised irrigation was observed and found out that it is due to chemical clogging of drippers. Considering the complexity of the composition of the natural water used in micro-irrigation, we started our study by examining the effectiveness of the inhibitor on pure calco-carbonic water with 40°F, and then moved to explore the natural water of the agricultural region. The Legrand-Poirier-Leroy method allowed us to determine the position of the irrigation water compared to calco-carbonic balance. LCGE (abbreviation of “Laboratory of Chemistry and Environmental Engineering”) technique, based on the accelerated formation of calcium carbonate deposit under the effect of a degasification of studied water, enabled us to evaluate the scaling power of this water of irrigation either with or without inhibitor. The experimental results showed the following: in the case of pure calco-carbonic water with 40?F and of natural water, the addition respectively of 2 mg/L and 2.25 mg/L of phosphate fertilizer completely inhibits the precipitation of calcium carbonate under the conditions of the experiment.

关键词： Scaling Power Water Irrigation Calcium Carbonate Inhibitor Phosphate Fertilizer

Numerical analysis for impacts of nozzle end-clearances on aerodynamic performance and forced response in a VNT turbine

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Chinese Journal of Aeronautics 2018年第5期31卷 1030-1040页

作者： ben ZHAO Leilei WANG Hongjun HOU Michigan State University East Lansing 48824 USA Hebei University of Engineering Handan 056038 China

It has been well known that nozzle end-clearances in a Variable Nozzle Turbine（VNT）are unfavorable for aerodynamic performance, especially at small openings, and efforts to further decrease size of the clearances are very hard due to thermal expansion. In this paper, both the different sizes of nozzle end-clearances and the various ratios of their distribution at the hub and shroud sides were modelled and investigated by performing 3D Computational Fluid Dynamics（CFD） and Finite Element Analysis（FEA） simulations with a code of transferring the aerodynamic pressure from the CFD results to the FEA calculations. It was found that increasing the size of the nozzle end-clearances divided equally at the hub and shroud sides deteriorates turbine efficiency and turbine wheel reliability, yet increases turbine flow capacity. And, when the total nozzle endclearances remain the same, varying nozzle end-clearances＇ distribution at the hub and shroud sides not only shifts operation point of a VNT turbine, but also affects the turbine wheel vibration *** with nozzle hub clearance, the shroud clearance is more sensitive to both aerodynamic performance and reliability of a VNT turbine. Consequently, a possibility is put forward to improve VNT turbine efficiency meanwhile decrease vibration stress by optimizing nozzle end-clearances＇ distribution.

关键词： Clearance Forced response Mode analysis Performance Reliability Variable Nozzle Turbine(VNT)

MIXED LEGENDRE-HERMITE PSEUDOSPECTRAL METHOD FOR HEAT TRANSFER IN AN INFINITE PLATE

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Journal of Computational Mathematics 2005年第6期23卷 587-602页

作者： Tian-jun Wang ben-yu Guo Department of Mathematics Division of Computational Science of E-institute of Shanghai Universities Shanghai Normal University Shanghai 200234 China

A new mixed Legendre-Hermite interpolation is introduced. Some approximation results are established. Mixed Legendre-Hermite pseudospectral method is proposed for non-isotropic heat transfer in an infinite plate. Its ... 详细信息

关键词： Non-isotropic heat transfer Infinite plate Mixed Legendre-Hermite pseudospectral method

Revisiting the Dirichlet-to-Neumann Solver for Data Completion and Application to Some Inverse Problems

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Revisiting the Dirichlet-to-Neumann Solver for Data Completi...