Perspectives on management theory’s application in the internet of things research

Information Systems and e-Business Management - The growing use of the internet of things (IoT) has provided businesses with a new opportunity. This study performed a systematic literature review...     

Photocatalytic degradation of methyl tert‐butyl ether (MTBE) in contaminated water by ZnO nanoparticles

BACKGROUND: Over the past several decades methyl tert‐butyl ether (MTBE) as additive to gasoline, intended to either boost ratings of fuel or to reduce air pollution, has been accepted worldwide. Since MTBE has high water solubility, the occurrence of fuel spills or leaks from underground storage tanks or transferring pipeline has led to the contamination of natural waters. In this study the degradation of aqueous MTBE at relatively high concentrations was investigated by a UV‐visible/ZnO/H₂O₂ photocatalytic process. The effects of important operational parameters such as pH, amount of H₂O₂, catalyst loading and irradiation time were also investigated. Concentration of MTBE and intermediates such as tert‐butyl formate and tert‐butyl alcohol were measured. RESULTS: Time required for complete degradation increased from 20 to 150 min when the initial concentration was increased from 10 to 500 mg L^?1. The first‐order rate constants for degradation of MTBE were estimated to be 0.183–0.022 min^?1 as the concentration increased from 10 to 500 mg L^?1. Study of the overall mineralization monitored by total organic carbon analysis showed that at an initial concentration of 100 mg L^?1 MTBE complete mineralization was obtained after 100 min under UV‐visible/ZnO/H₂O₂ photocatalysis. CONCLUSION: The data presented in this paper clearly indicated that UV‐visible/ZnO/O₂ as an advanced oxidation process provides an efficient treatment alternative for the remediation of MTBE‐contaminated waters. Copyright © 2008 Society of Chemical Industry     

Mechanical simulations of SANDIA II tests OECD ISP 48 benchmark

This paper illustrates the work carried out by EDF within the framework of ISP 48 post-test analysis of NUPEC/NRC 1:4-scale model of a prestressed pressure containment vessel of a nuclear power plant [Hessheimer, M.F., Klamerus, E.W., Rightly, G.S., Lambert, L.D., Dameron, R.A., 2003. Overpressurization test of a 1:4-scale prestressed concrete containment vessel model. NUREG/CR-6810, SAND2003-0840P. Sandia National Laboratories, Albuquerque, NM]. EDF as a participant of the International Standard Problem no. 48 [Mathet, E., Hessheimer, M., Ali, S., Tegeler, B., 2005. An international standard problem: analysis of 1:4-scale prestressed concrete containment vessel model under severe accident conditions. Proceedings of 18th International Conference on Structural Mechanics in Reactor Technology. SMiRT 18. Beijing, China] has participated in this program, within the framework of its research and development program on the simulation of non-linear behaviour of nuclear power plant prestressed concrete pressure containment vessels. EDF performed several simulations to determine the ultimate response of the scale model. To determine the most influent parameters in such an analysis several studies were carried out. A full 3D mesh of the entire structure was then created. The mesh was built using a parametric tool to measure the influence of discretization on results. To represent the cracking of concrete, two material laws were then used. The purpose of this paper is to illustrate the ultimate behaviour of SANDIA II model obtained by Code_Aster^® finite element platform, with comparison to tests records, and also to share the lessons learned from the parametric computations and underline precautions that must be taken in such studies.     

Catalytic combustion over platinum group catalysts: fuel-lean versus fuel-rich operation

Performance data are presented for methane oxidation on alumina-supported Pd, Pt, and Rh catalysts under both fuel-rich and fuel-lean conditions. Catalyst activity was measured in a micro-scale isothermal reactor at temperatures between 300 and 800 °C. Non-isothermal (near adiabatic) temperature and reaction data were obtained in a full-length (non-differential) sub-scale reactor operating at high pressure (0.9 MPa) and constant inlet temperature, simulating actual reactor operation in catalytic combustion applications.

Under fuel-lean conditions, Pd catalyst was the most active, although deactivation occurred above 650 °C, with reactivation upon cooling. Rh catalyst also deactivated above 750 °C, but did not reactivate. Pt catalyst was active above 600 °C. Fuel-lean reaction products were CO₂ and H₂O for all three catalysts.

The same catalysts tested under fuel-rich conditions demonstrated much higher activity. In addition, a ‘lightoff’ temperature was found (between 450 and 600 °C), where a stepwise increase in reaction rate was observed. Following ‘lightoff’ partial oxidation products (CO, H₂) appeared in the mixture, and their concentration increased with increasing temperature. All three catalysts exhibited this behavior.

High-pressure (0.9 MPa) sub-scale reactor and combustor data are shown, demonstrating the benefits of fuel-rich operation over the catalyst for ultra-low emissions combustion.     

A pseudo-spectral scheme for the approximate solution of a time-fractional diffusion equation

We consider an initial-boundary-value problem for a time-fractional diffusion equation with initial condition u₀(x) and homogeneous Dirichlet boundary conditions in a bounded interval [0, L]. We study a semidiscrete approximation scheme based on the pseudo-spectral method on Chebyshev–Gauss–Lobatto nodes. In order to preserve the high accuracy of the spectral approximation we use an approach based on the evaluation of the Mittag-Leffler function on matrix arguments for the integration along the time variable. Some examples are presented and numerical experiments illustrate the effectiveness of the proposed approach.     

How to maintain both privacy and authentication in digital libraries

In this paper, we first present a brief overview of two main network security problems related to digital libraries, privacy and authentication, and then we propose practical solutions to these problems which are applicable to digital libraries of any type and arbitrary size. More precisely, we propose a key exchange protocol and an identification scheme whose security is based on the difficulty of computing discrete logarithms and factoring large integers.     

Coupled acoustic-shell model for experimental study of cell stiffness under acoustophoresis

Under the influence of acoustic radiation force, particles can be trapped and deformed at the pressure node in a microfluidic channel. Based on this principle, the elastic modulus of biological cells can be estimated. In this study, a numerical framework, consisting of a boundary element model for acoustic field and an axisymmetric shell model, is developed to simulate the cell deformation under acoustic radiation force. The boundary element model is used to calculate the radiation traction exerted on the cell surface. The cell membrane deformation due to this traction is simulated by using the axisymmetric shell model. The Young’s moduli of algae and red blood cell membranes are then estimated by comparing the experimental observation with the simulated membrane deformation. It is found that the value of Young’s modulus of the red blood cell membrane is lower than that of algae cell membrane. Furthermore, for both cells, the estimated Young’s moduli are negligible compared to the bulk moduli of the cells reported in the previous studies.     

Application of the principles of linear fracture mechanics to the composite materials

Application of the principles of linear fracture mechanics to the orthotropic composite materials is examined. It is shown that fracture toughness of unidirectional composites is independent of crack length but dependent on crack-fiber orientation. For experimental verification of the above principles, uni-directional glass epoxy material (Scotchply 1002) was used. The fracture toughness of Scotchply 1002 for different crack-fiber orientations is obtained by utilizing Solid Sap finite element program and compact tension specimens. An empirical formula relating the fracture toughness of the material for different crack-fiber orientation is found.

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Résumé On examine l'application du principe de la mécanique linéaire de rupture aux matériaux composites orthotropes. On montre que la ténacité à la rupture de composites unidirectionnels est indépendante de la longueur de la fissure mais dépend de l'orientation des fibres par rapport à cette fissure. Pour vérifier de manière expérimentale les principes ci-dessus, on a utilisé un matériau en verre epoxy unidirectionnel (Scotchply 1002). La ténacité à la rupture du Scotchply 1002 pour différentes orientations fibre/fissure a été obtenue en utilisant un programme à élément fini Solid Sap et des éprouvettes de traction compactes. On a trouvé une formule empirique mettant en relation la ténacité à la rupture du matériau pour différentes orientations fibre/fissure.

     

Hydraulic behaviour of a representative structural volume for containment buildings

For particular structures like containment buildings of nuclear power plants, the study of the hydraulic behaviour is of great concern. These structures are indeed the third barrier used to protect the environment in case of accidents. The evolution of the leaking rate through the porous medium is closely related to the changes in the permeability during the ageing process of the structure. It is thus essential to know the relation between concrete degradation and the transfer property when the consequences of a mechanical loading on the hydraulic behaviour have to be evaluated. A chained approach is designed for this purpose. The mechanical behaviour is described by an elastic plastic damage formulation, where damage is responsible for the softening evolution while plasticity accounts for the development of irreversible strains. The drying process is evaluated according to a non-linear equation of diffusion. From the knowledge of the damage and the degree of saturation, a relation is proposed to calculate the permeability of concrete. Finally, the non-homogeneous distribution of the hydraulic conductivity is included in the hydraulic problem which is in fact the association of the mass balance equation for gas phase and Darcy law. From this methodology, it is shown how an indicator for the hydraulic flows can be deduced.     

Effects of silymarin on biochemical and oxidative stress markers in end‐stage renal disease patients undergoing peritoneal dialysis

Introduction End‐stage renal disease (ESRD) patients especially those undergoing dialysis are vulnerable to several complications, in particular those related to oxidative stress. Silymarin is an herbal medicine commonly used as an antioxidant in different pathologies. Methods To evaluate the effect of silymarin on biochemical and oxidative stress markers, 50 ESRD patients undergoing peritoneal dialysis were randomly divided into two groups of silymarin (n = 28) and control (n = 22) and received silymarin (140 mg every 8 hours) or placebo for 2 months, respectively. Ferric reducing antioxidant power and total 8‐iso‐prostaglandin F_2α were measured in plasma, while catalase enzyme activity was measured in erythrocytes of both groups before and after treatment. Findings Ferric reducing antioxidant power values after treatment were significantly decreased in silymarin group compared to before treatment values (17.2 ± 2.9 and 15.9 ± 3.1 µM equivalent of quercetin/dL, respectively, P < 0.05). Conversely, catalase levels were increased 17.3% after silymarin consumption, while it was decreased 9.1% in control group. Further, hemoglobin (from 10.94 ± 2.17 to 11.54 ± 2.03 g/dL, P < 0.05) and albumin levels (from 3.48 ± 0.67 to 3.61 ± 0.53 g/dL, P < 0.05) were significantly increased after silymarin administration. Discussion It is concluded that silymarin could be regarded as a supplementary therapy for ESRD patients undergoing peritoneal dialysis in order to reduce complications.