159 research outputs found

    Relationship of individual and organizational factors and employee performance : moderating effects of psychological empowerment in the ceramic tile industry (Abstract and Table of content only)

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    The Malaysia ceramic tile industry is facing many challenges which include competition from cheap imported tiles from China, increasing costs to procure raw materials as well as the continual increases in natural gas prices, hence causing the production costs to be very high which will have an impact on the industry’s survival. Therefore, one way to boost productivity in order to reduce the labour costs is to have a team of high performing employees. For this reason, this research was initiated to study the factors that could optimize individual employee performance in this industry. Factors that had an influence on employees’ performance in this research were divided into two categories, the first being the independent variables or organisational factors consisting of rewards, procedural justice, organizational culture and psychological empowerment and the second category were the individual factors or demographic factors consisting of employees’ academic background and their tenure at their organizations. Psychological empowerment was also studied to see if it could moderate the relationship between rewards, employees’ academic background and their tenure at their organizations, and employee performance. Based on the factors above, 10 research hypotheses were developed to study their relationships with employee performance. The respondents, totalling 600 employees, were from the supervisory level as they play a significant role in the success or failure of any organization. Questionnaires were given to all respondents and the response rate was 39 %. The completed questionnaires were analysed using SPSS version 20. The results obtained showed that all the independent variables and demographic factors influenced individual employee performance. However, when all the variables were combined together, rewards and employees’ academic background were unable to influence employee performance. The study also found that psychological empowerment did not moderate the relationship between employees’ tenure and their performance. The theoretical implication of this study was that expectancy and goal setting theories were observed by the respondents. The practical implication to employers is that the respondents highlighted the importance of feeling psychologically empowered in order to perform well on their job. The limitation of this study was that it only looked at the supervisory level in the ceramic tile manufacturing sector. Therefore, future research could consider different levels of management and different industries to determine whether if there is any similarity with the results from this study. Besides, this research considered psychological empowerment as a variable and did not study the impact of the four cognitions separately. [ABSTRACT BY AUTHOR

    Modeling diffusion limitation in solid-oxide fuel cells

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    Effect of surface diffusion on the performance of solid-oxide fuel cell is investigated. A methodical approach for the evaluation of surface diffusion coefficients of various adsorbed species based on bond-order conservation Morse potential (BOC-MP) method is presented. The surface diffusion fluxes are used for the evaluation of temporal changes in surface coverages. Our analysis shows that surface diffusion does not lead to the concentration losses in solid oxide fuel cells. Further analysis is carried out and results are presented to substantiate the significance of interface diffusion on the behavior of voltage at limiting current

    Modeling process intensified catalytic plate reactor for synthesis gas production

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    This paper presents numerical study of co- and counter-flow arrangements for catalytic plate reactors (CPR). CH4 steam reforming coupled with CH4 oxidation is simulated using detailed surface reaction mechanisms. Effect of inlet velocities to the reforming channel, oxidation channel, and material properties of the plate on the resulting plate temperature and CH4 conversions is studied. The simulation results agree very well with an industrial scale reformer unit and calculations are further carried out to evaluate the number of CPRs and stacks required to replace and industrial uni

    Modeling CO2 electrolysis in solid oxide electrolysis cell

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    A modified Butler-Volmer equation for the reduction of CO2 by considering multi-step single-electron transfer reactions is presented. Exchange current density formulations free from arbitrary order dependency on the partial pressures of reactants and products are proposed for Ni and Pt surfaces. Button cell simulations are performed for Ni-YSZ/YSZ/LSM, Pt-YSZ/YSZ/Pt, and Pt/YSZ/Pt systems using two different electrochemical models, and simulation results are compared against experimental observations. The first electrochemical model considers charge transfer reactions occurring at the interface between the electrode and dense electrolyte, and the second model considers the charge transfer reactions occurring throughout the thickness of the cermet electrode. Single-channel simulations are further performed to asses the O2 production capacity of CO2 electrolysis syste

    Computational Fluid Dynamics of Catalytic Reactors

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    Catalytic reactors are generally characterized by the complex interaction of various physical and chemical processes. Monolithic reactors can serve as example, in which particle oxidation and reforming of hydrocarbons, combustion of natural gas, and reduction of pollutant emissions from automobiles are frequently carried out

    Modeling of Solid-Oxide Electrolyser Cells: From H2, CO Electrolysis to Co-Electrolysis

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    In this analysis, we report an in-house model to describe the complex fundamental and functional interactions between various internal physico-chemical phenomena of a SOEC. Electrochemistry at the three-phase boundary is modeled using a modified Butler-Volmer approach that considers H2 and CO, individually, as electrochemically active species. Also, a multi-step elementary heterogeneous reaction mechanism for the thermo-catalytic H2/CO2 electrode chemistry, along with the dusty gas model (DGM) to account for multi-component diffusion of ideal gases through porous media, are used. The model is geometry independent. Results pertaining to detailed chemical processes within the cathode, electrochemical behavior and irreversible losses during SOEC operation are demonstrated

    Sulfur Poisoning of SOFCs: A Model Based Explanation of Polarization Dependent Extent of Poisoning

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    Several experimental studies have shown that, 1) the extent of the poisoning effect due to trace amounts of sulfur compounds in the fuel is lower if a SOFC is operated at a higher current density, and 2) the performance drop due to sulfur poisoning is much lower for Ni-GDC or Ni-ScSZ anodes when compared to Ni-YSZ anodes. This work presents a first principles numerical model that simulates experimental studies of sulfur poisoning on SOFC button cells. The exchange current densities for the electrodes are determined using sulfur-free polarization data for cells fueled by humidified mixtures of H2 and N2. A detailed surface reaction model that predicts the fractional coverage of all adsorbed species at the three phase interface is coupled to the SOFC model and the sulfur coverage is used to alter the anode exchange current density. The resulting model predictions match experimental observations during both galvanostatic and potentiostatic operation. Our analysis shows that the observed lower performance drop at higher current density is due to the non-linear nature of the electrochemical rate equations, and that the lower impact of sulfur poisoning on Ni-GDC and Ni-ScSZ anodes (compared to Ni-YSZ anodes) is due to their higher electrochemical activity

    On the stability of Ni/γ-Al2O3 catalyst and the effect of H2O and O2 during biogas reforming

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    This work systematically studies the effect of process conditions on catalyst stability during biogas reforming to syngas. To study the effect of different oxidizer content and temperature on reforming reactions, appropriate ratios of H2O/CH4, O2/CH4, and operating temperatures are identified using chemical equilibrium analysis. Reactions are performed on 10 wt% Ni/γ-Al2O3 in a fixed bed reactor at different WHSVs. Reactions performed at high WHSV and 600–800 ∘C reveal catalyst deactivation at high steam content. The observed deactivation of the catalyst is due to the loss of active nickel sites because of sintering, carbon deposition, and the formation of inactive spinel. The addition of O2 even in a small quantity improves the catalyst stability. The catalysts are characterized using XRD, FTIR, TPR, BET, TGA, XPS, and TEM

    Numerical study of on-board fuel reforming in a catalytic plate reactor for solid-oxide fuel cells

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    A pseudo-transient numerical model is used for the simulation of a multi-functional catalytic plate reactor (CPR). The work mainly addresses the problems associated with on-board reforming for solid-oxide fuel cells. Heat management is achieved by indirectly coupling partial oxidation with reforming. Water management is achieved by partially recycling the anode stream from a solid-oxide fuel cell. The model uses detailed heterogeneous chemistry for reforming and oxidation reactions occurring on the catalyst beds

    Deactivation and regeneration of Ni catalyst during steam reforming of model biogas: An experimental investigation

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    his paper presents detailed study of biogas reforming. Model biogas with different levels of H2S is subjected to reforming reaction over supported Ni catalyst in a fixed bed reactor at 700 °C and 800 °C. In order to understand the poisoning effects of H2S the reactions have been initially carried out without H2S in the feed stream. Three different H2S concentrations (20, 50 and 100 ppm) have been considered in the study. The H2O to CH4 ratio is maintained in such as way that CO2 also participates in the reforming reaction. After performing the poisoning studies, regeneration of the catalyst has been studied using three different techniques i) removal of H2S from the feed stream ii) temperature enhancement and iii) steam treatment. Poisoning at low temperature is not recoverable just by removal of H 2S from the feed stream. However, poisoning at high temperature is easily reversed just by removal of H2S from the feed stream. Unlike some previous reports by Li et al. (2010) and Rostrup-nielsen (1971) [1,2], catalyst regeneration is achieved in shorter time frames for all the regeneration techniques attempte
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