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Optimal Grading Policies in the Online Acquisition of Used Products

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Journal of Systems Science and Systems Engineering 2021年第1期30卷 29-43页

作者： Xiang Chu zhong wen Jian Chen School of Maritime Economics and Management Dalian Maritime UniversityDalian116026China International Business School Beijing Foreign Studies UniversityBeijing100089China School of Economics and Management Tsinghua UniversityBeijing100084China

Although online reverse commerce(recommerce)is convenient and efficient,it is not without *** limits recommerce firms’flexibility to offer personalized prices and may cause mismatched grading between the firms and sellers of used *** study examines a recommerce firm’s decision on grading criteria and *** find that the firm’s optimal policy exhibits two distinctly different patterns depending on the trade value of the *** demonstrate that sellers’overestimate and underestimate errors have qualitatively different effects on firm profitability,and the effects crucially rely on the type of optimal *** findings can apprise firms on how to preset sorting criteria and prices as well as reduce grading errors.

关键词： Closed-loop supply chains used-product acquisition management recommerce grading error grading policy

Expression of Nogo-A on the retina in rat model with chronic ocular hypertension

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International Journal of Ophthalmology(English edition) 2010年第2期3卷 112-113页

作者： Qing-Zhu Nie, dian-wen Gao Department of Ophthalmology Shengjing Hospital Affiliated to China Medical University Shenyang 110004 Liaoning Province China Heilongjiang Eye Hospital Harbin 150001 Heilongjiang Province China

AIMTo study the expressive variation of Nogo-A on rat retina in the process of chronic ocular hypertension.

关键词： retina chronic hypertension Nogo-A retinal ganglion cell

Coupling potential and viscous flow models with domain decomposition for wave propagations

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Journal of Hydrodynamics 2022年第5期34卷 826-848页

作者： wen-jie zhong wen-tao Wang De-cheng Wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China China Ship Scientific Research Center Wuxi214082China

Either potential flow or viscous flow based model may be flawed for numerical wave *** two-way coupling of potential and viscous flow models with the domain decomposition utilizing respective strengths has been a trending research *** contrast to existing literatures in which closed source potential models were used,the widely used open source OceanWave3D,OpenFOAM-v2012 are used in the present *** innovative overlapping two-way coupling strategy is developed utilizing the ghost points in *** guarantee computational stability,a relaxation zone used both for outlet damping and data transfer is built over the overlapping region in *** free surface elevation in the relaxation zone is directly probed in OpenFOAM while the velocity potential is indirectly built upon its temporal variation which is calculated by the free surface boundary condition using the probed *** coupling is achieved based on the fourth-order Runge-Kutta(RK)*** two-and three-dimensional tests including linear,nonlinear,irregular,and multi-directional irregular waves,are *** effectiveness of the coupling procedure in bidirectional data transfer is fully demonstrated,and the model is validated to be accurate and efficient,thus providing a competitive alternative for ocean wave simulations.

关键词： Domain decomposition numerical wave tank potential/viscous flow coupling irregular waves wave-structure interaction

Effect of Intergranular Precipitation on the Internal Oxidation Behavior of Cr–Mn–N Austenitic Stainless Steels

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Acta Metallurgica Sinica(English Letters) 2015年第8期28卷 1008-1014页

作者： Lei-Gang Zheng Xiao-Qiang Hu Xiu-Hong Kang dian-zhong Li Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

The effect of intergranular precipitation on the internal oxidation behavior of Cr–Mn–N austenitic steels at 1000 °C in dry air atmosphere was investigated using scanning electron microscope, transmission electron microscope, and X-ray diffraction analysis. The results show that intergranular M23C6 carbide morphologies play an important role on the internal oxidation behavior of Cr–Mn–N steels. During the period of the oxidation, both discontinuous chain-shaped and continuous film-shaped intergranular M23C6 carbides precipitated along the grain boundaries. Internal oxides of silica preferentially intruded into the matrix along grain boundaries with discontinuous M23C6 carbide particles, while silica was obviously restricted at the interfaces between the external scale and matrix on the occasion of continuous film-shaped M23C6 carbides. It is seemed that reasonable microstructure could improve the oxidation resistance of Cr–Mn–N steels.

关键词： M23C6 precipitation Internal oxidation Cr–Mn–N austenitic steel

Adaptive threading strategy based on rolling characteristics analysis in hot strip rolling

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Journal of Central South University 2017年第7期24卷 1560-1572页

作者： PENG wen CHEN Shu-zong GONG dian-yao LIU Zi-ying ZHANG dian-hua State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Research Institute of Technology Shougang GroupBeijing 100041China

In order to improve the threading stability and the head thickness precision in tandem hot rolling process, an adaptive threading strategy was proposed. The proposed strategy was realized by the rolling characteristics analysis, and factors which affect the rolling force and the final thickness were determined and analyzed based on the influence coefficients calculation process. An objective function consisting of the influenced factors was founded, and the disturbance quantity was obtained by minimizing the function with the Nelder-Mead simplex method, and the proposed adaptive threading strategy was realized based on the calculation results. The adaptive threading strategy has been applied to one 7-stand hot tandem mill successfully, actual statistics data show that the predicted rolling force prediction in the range of +/- 5.0% is improved to 97.8%, the head thickness precision in the range of +/- 35 mu m is improved to 98.5%, and the threading stability and the head thickness precision are enhanced to a high level.

关键词： hot strip rolling adaptive threading rolling characteristics analysis influence coefficients method simplex algorithm

Strong Coupling of Light with Extremely Thin Non-Close-Packing Colloidal Crystals:Experimental and Theoretical Studies

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Chinese Physics Letters 2013年第4期30卷 217-220页

作者： HUANG zhong DONG wen Department of Physics and Jiangsu Key Laboratory of Thin Films Soochow UniversitySuzhou 215006

Single and double layers of non-close-packing silica colloidal crystals are prepared using the self-assembly and chemical etching methods.A modulation of size reduction of 21%of silica particles is reported while sustaining the ordering of the *** a result of the coupling between light and the two-dimensional(2D)photonic structures,several dips are clearly observed in the measured optical transmission *** decreasing the dielectric particle size,the transmission dips undergo blue shifts and simultaneously become *** measured transmission spectra are in good agreement with the theoretical calculations by taking the energy dissipation of the semi-infinite dielectric substrate for the 2D photonic crystals.

关键词： spectra. methods. dielectric

Wideband angle of arrival estimation of chirp signals using virtual Wignerville distribution

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Journal of Systems Engineering and Electronics 2007年第2期18卷 243-248页

作者： wen zhong Li Liping Zhang Xixiang School of Electronic Engineering Univ. of Electronic Science and Technology of ChinaChengdu 610054 P. R. China

To estimate the angle of arrivals （AOA） of wideband chirp sources, a new timo-frequency algorithm is proposed. In this method, virtual sensors are constructed based on the fact that the steering vectors of wideband chirp signals are linear and vary with time. And the randon Wignersville distribution （RWVD） of real sensors and virtual sensors are calculated to yield the new time-invariable steering vectors, furthermore, the noise and cross terms are suppressed. In addition, the multiple chirp signals are selected by their time-frequency points. The cost of computation is lower than the common AOA estimation methods of wideband sources due to nonrequirement of frequency focusing, interpolating and matrix decomposition, including subspace decomposition. Under the lower signal noise ratio （SNR） condition, the proposed method exhibits better precision than the method of frequency focusing （FF）. The proposed method can be further applied to nonuniform linear array （NLA） since it is not confined to the array geometry. Simulation results illustrate the efficacy of the proposed method.

关键词： Array signal processing Angle of arrivals Wignerville distribution Wideband chirp signal.

Recent Advances in High‑Efficiency Electrocatalytic Water Splitting Systems

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Electrochemical Energy Reviews 2023年第1期6卷 1-38页

作者： Xian‑Wei Lv wen‑wen Tian zhong‑Yong Yuan Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) School of Materials Science and EngineeringNankai UniversityTianjin 300350China

Electrocatalytic water splitting driven by renewable energy input to produce clean hydrogen(H_(2))has been widely considered a prospective approach for a future hydrogen-based ***,the development of industrial alkaline water electrolyzers is hindered due to their unfavorable thermodynamics with high overpotential for delivering the whole process,caused by sluggish kinetics involving four-electron *** exploration of water electrolysis with low energy consumption and high efficiency is urgently required to meet the ever-growing energy storage and portfolio *** review emphasizes the strategies proposed thus far to pursue high-efficiency water electrolysis systems,including from the aspects of electro-catalysts(from monofunctional to bifunctional),electrode engineering(from powdery to self-supported),energy sources(from nonrenewable to renewable),electrolytes(from pure to hybrid),and cell configurations(from integrated to decoupled).Critical appraisals of the pivotal electrochemistry are highlighted to address the challenges in elevating the overall efficiency of water ***,valuable insights for the future development directions and bottlenecks of advanced,sustainable,and high-efficiency water splitting systems are outlined.

关键词： Electrocatalytic water splitting Hydrogen-based society Electrode engineering Cell configurations Challenges and perspectives

Ion adsorption components in liquid/solid systems

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Journal of Environmental Sciences 2006年第6期18卷 1167-1175页

作者： WU Xiao-fu HU Yue-li ZHAO Fang HUANG zhong-zi LEI dian College of Resource and Environment Central South University of Forestry and Technology Changsha 410004 China

Experiments on Zn^2＋ and Cd^2＋ adsorptions on vermiculite in aqueous solutions were conducted to investigate the widely observed adsorbent concentration effect on the traditionally defined adsorption isotherm in the adsorbate range 25--500 mg/L and adsorbent range 10--150 g/L. The results showed that the equilibrium ion adsorption density did not correspond to a unique equilibrium ion concentration in liquid phase. Three adsorbate/adsorbent ratios, the equilibrium adsorption density, the ratio of equilibrium adsorbate concentration in liquid phase to adsorbent concentration, and the ratio of initial adsorbate concentration to adsorbent concentration, were found to be related with unique values in the tested range. Based on the assumption that the equilibrium state of a liquid/solid adsorption system is determined by four mutually related components： adsorbate in liquid phase, adsorbate in solid phase, uncovered adsorption site and covered adsorption site, and that the equilibrium chemical potentials of these components should be equalized, a new model was presented for describing ion adsorption isotherm in liquid/solid systems. The proposed model fit well the experimental data obtained from the examined samples.

关键词： adsorbent effect adsorbate/adsorbent ratio adsorption component chemical potential Zn^2+ Cd^2+ vermiculite