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Chinese Physics b 2018年第10期27卷 231-239页

作者： J P Singh V T Pham T Hayat S Jafari F e Alsaadi b K Roy Department of electrical engineering National Institute of Technology Silchar 788010 India School of electronics and Telecommunications Hanoi University of Science and Technology 01 Dai Co Viet Hanoi Viet Nam Department of Mathematics Faculty of Science King Abdulaziz University Jeddah 21589 Saudi Arabia Department of Mathematics Quaid-I-Azam University Islamabad 44000 Pakistan Ambikar University of Technology Tehran 15875-4413Iran Department of Information Technology Faculty of Computing and IT King Abdulaziz University Jeddah Saudi Arabia

This paper reports a new simple four-dimensional（4 D） hyperjerk chaotic system. The proposed system has only one stable equilibrium point. Hence, its strange attractor belongs to the category of hidden attractors. The proposed system exhibits various dynamical behaviors including chaotic, periodic, stable nature, and coexistence of various attractors. Numerous theoretical and numerical methods are used for the analyses of this system. The chaotic behavior of the new system is validated using circuit implementation. Further, the synchronization of the proposed systems is shown by designing an adaptive integrator backstepping controller. Numerical simulation validates the synchronization strategy.

关键词： new hyperjerk chaotic system stable equilibrium hidden attractors adaptive backstepping control synchronization

evaluation of stress intensity factors for bi-material interface cracks using displacement jump methods

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Acta Mechanica Sinica 2017年第6期33卷 1051-1064页

作者： K. C. Nehar b. e. Hachi F. Cazes M. Haboussi Laboratoire de développement en mécanique et matériaux (LDMM) Université de Djelfa PB 3117 Djelfa Algeria Laboratoire des Sciences des Procédés et des Matériaux (LSPM) UPR 3407 CNRS Université Paris 13 Paris France

The aim of the present work is to investigate the numerical modeling of interfacial cracks that may appear at the interface between two isotropic elastic materials. The extended finite element method is employed to analyze brittle and bi-material interfacial fatigue crack growth by computing the mixed mode stress intensity factors(SIF). Three different approaches are introduced to compute the SIFs. In the first one, mixed mode SIF is deduced from the computation of the contour integral as per the classical J-integral method,whereas a displacement method is used to evaluate the SIF by using either one or two displacement jumps located along the crack path in the second and third approaches. The displacement jump method is rather classical for mono-materials,but has to our knowledge not been used up to now for a bimaterial. Hence, use of displacement jump for characterizing bi-material cracks constitutes the main contribution of the present study. Several benchmark tests including parametric studies are performed to show the effectiveness of these computational methodologies for SIF considering static and fatigue problems of bi-material structures. It is found that results based on the displacement jump methods are in a very good agreement with those of exact solutions, such as for the J-integral method, but with a larger domain of applicability and a better numerical efficiency(less time consuming and less spurious boundary effect).

关键词： bi-material interface crack Mixed mode stress intensity factor Displacement jump X-FeM Fatigue crack growth

Recent progress in fatigue behavior of Mg alloys in air and aqueous media: A review

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Journal of Materials Science & Technology 2017年第10期33卷 1075-1086页

作者： b.J.Wang S.D.Wang D.K.Xu e.H.Han School of environmental and Chemical engineering Shenyang Ligong University CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences

Due to the interactions between mechanics and chemistry, Mg alloys are inevitably subjected to the combined effect of corrosion attack and cyclic loading, which eventually leads to corrosion fatigue failure. In this paper, fundamental aspects regarding the fatigue behavior of Mg alloys have been reviewed,including：（1） fatigue behavior of Mg alloys in air and aqueous media; and（2） the influence of microstructure, anodic dissolution, hydrogen embrittlement（He）, heat treatment and surface protection on fatigue behavior of Mg alloys. Moreover, some remaining unresolved issues and future targets to deeply understand the failure mechanism of corrosion fatigue have been described.

关键词： Magnesium alloys Fatigue Corrosion fatigue Crack initiation Hydrogen embrittlement

Progress in carbon dioxide separation and capture: A review

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Journal of environmental Sciences 2008年第1期20卷 14-27页

作者： Hongqun Yang Zhenghe Xu Maohong Fan Rajender Gupta Rachid b Slimane Alan e bland Ian Wright Department of Chemical and Materials engineering University of Alberta EdmontonABT6G2G6 Canada School of Materials Science and Technology Georgia Institute of Technology Atlanta GA 30332 USA Gas Technology Institute Des Plaines IL 60018 USA Western Research Institute Laramie Wyoming 82072 USA Oak Ridge National Laboratory P.O. Box 2008 Oak Ridge TN 37831 USA

This article reviews the progress made in CO2 separation and capture research and engineering. Various technologies, such as absorption, adsorption, and membrane separation, are thoroughly discussed. New concepts such as chemical-looping combustion and hydrate-based separation are also introduced briefly. Future directions are suggested. Sequestration methods, such as forestation, ocean fertilization and mineral carbonation techniques are also covered. Underground injection and direct ocean dump are not covered.

关键词： coal flue gas carbon dioxide sorbent absorption adsorption membrane separation sequestration

experimental and Theoretical Study of the effect of Moisture on Methane Adsorption and Desorption by Activated Carbon at 273.5 K

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Journal of Natural Gas Chemistry 2007年第1期16卷 22-30页

作者： S.Farzad V.Taghikhani C.Ghotbi b.Aminshahidi e.Nemati Lay Department of Chemical and Petroleum engineering Sharif University of TechnologyTehranIran

Adsorption and desorption of methane by activated carbon （AC） at constant temperature and at various pressures were investigated. The effect of moisture was also studied. A volumetric method was used, up to 40 bar, at a temperature of 273.5 K. Results of a dry AC sample were compared with those obtained from a moist sample and two different ACs with different physical and surface properties were used. As expected, the results showed that the existence of moisture, trapped in the AC pores, could lead to a decrease in the amount of methane adsorbed and a decrease in the amount of methane delivered during desorption. To model the experimental results, a large variety of adsorption isotherms were used. The regressed parameters for the adsorption isotherms were obtained using the experimental data generated in the present study. The accuracy of the results obtained from the different adsorption isotherms was favorably compared.

关键词： activated carbon adsorption adsorption properties thermodynamic analysis

Giant magnetocaloric effect in Tb_5Ge_(2-x)Si_(2-x)Mn_(2x) compounds

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Chinese Physics b 2010年第5期19卷 542-548页

作者： e.Yzak b.emre Y.elerman A.Ycel Department of engineering Physics Faculty of EngineeringAnkara University06100 BesevlerAnkaraTurkey Faculty of Science and Letters Physics DepartmentMugla UniversityKtekli 48000 MuglaTurkey

The crystal structure, magnetic and magnetocaloric characteristics of the pseduo ternary compounds of TbsGe2-xSi2-xMn2x （0 ≤ 2x ≤ 0.1） were investigated by x-ray powder diffraction and magnetization measurements. The x-ray powder diffraction results show that all compounds preserve the monoclinic phase as the majority phase and all the synthesized compounds were observed to be ferromagnetic from magnetization measurements. Magnetic phase transitions were interpreted in terms of Landau theory. Maximum isothermal magnetic entropy change value （20.84 J-kg-1 -K-1） was found for Tb5Ge1.95Si1.95Mn0.1 at around 123 K in the magnetic field change of 5T.

关键词： magnetic properties magnetocaloric effect isothermal magnetic entropy change

Computational simulation of convective flow in the earth crust under consideration of dynamic crust-mantle interactions

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Journal of Central South University 2011年第6期18卷 2080-2084页

作者：赵崇斌彭省临刘亮明 b.e.HObbS A.ORD Computational Geosciences Research Centre Central South University School of earth and environment The University of Western Australia

The finite element method was used to solve fluid dynamic interaction problems between the crust and mantle of the earth. To consider different mechanical behaviours, the lithosphere consisting of the crust and upper mantle was simulated as fluid-saturated porous rocks, while the upper aesthenospheric part of the mantle was simulated as viscous fluids. Since the whole lithosphere was computationally simulated, the dynamic interaction between the crust and the upper mantle was appropriately considered. In particular, the mixing of mantle fluids and crustal fluids was simulated in the corresponding computational model. The related computational simulation results from an example problem demonstrate that the mantle fluids can flow into the crust and mix with the crustal fluids due to the resulting convective flows in the crust-mantle system. Likewise, the crustal fluids can also flow into the upper mantle and mix with the mantle fluids. This kind of fluids mixing and exchange is very important to the better understanding of the governing processes that control the ore body formation and mineralization in the upper crust of the earth.

关键词： computational simulation crustal fluids mantle fluids fluid dynamic interaction

Retention and Mobility of Copper and Lead in Soils as Influenced by Soil Horizon Properties

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Pedosphere 2011年第5期21卷 603-614页

作者： b.CeRQUeIRA e.F.COVeLO M.L.ANDRADe F.A.VeGA Department of Plant biology and Soil Science University of Vigo

The mobility and bioavailability of heavy metals in soils is largely governed by sorption and desorption ***2+ and Pb2+ are among the most potentially toxic heavy metals and they are present,often concomitantly,in many polluting spills and in *** objective was to assess and compare the competitive sorption and desorption capacities and sorption hysteresis of Cu2+ and Pb2+,as well as their migration through the profiles of four natural soils:a Humic Umbrisol,an Umbric Cambisol,an endoleptic Luvisol and a Humic *** all horizons Pb2+ was invariably sorbed and retained to a greater extent than Cu2+.The sorption and retention of Cu2+ were most in?uenced by pH,e?ective cation exchange capacity(CeCe) and Mn oxide *** the other hand,the fixation capacity of Pb2+ was most in?uenced by pH,CeCe,and Mn oxide and organic matter *** and CeCe were the individual soil properties most markedly in?uencing Cu2+ and Pb2+ sorption and *** all the horizons Pb2+ exhibited greater hysteresis than Cu2+.In each soil the hysteresis in the A horizon was greater than that in the b horizon,except in the bt horizon of the endoleptic Luvisol,due to its high pH and vermiculite *** on migration indices,Pb2+ was less mobile than Cu2+ in the studied soils.

关键词： desorption heavy metal hysteresis migration sorption

Sewage pollution in Negril, Jamaica: effects on nutrition and ecology of coral reef macroalgae

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Chinese Journal of Oceanology and Limnology 2011年第4期29卷 775-789页

作者： b. e. LAPOINTe K. THACKeR C. HANSON L. GeTTeN Harbor branch Oceanographic Institute at Florida Atlantic University 5600 US 1 North Ft. Pierce FL 34946 USA Negril Coral Reef Preservation Society P. O. Box 2563 Negril Jamaica West Indies

Coral reefs in the Negril Marine Park （NMP）, Jamaica, have been increasingly impacted by nutrient pollution and macroalgal blooms following decades of intensive development as a major tourist destination. A baseline survey of DIN and SRP concentrations, C：N：P and stable nitrogen isotope ratios （δ^15N） of abundant reef macroalgae on shallow and deep reefs of the NMP in 1998 showed strong P-limitation and evidence of increasing sewage pollution. In 1999, a sewage collection and treatment project began diverting wastewater from the resort and urban areas to a pond system that discharged partially-treated effluent into the South Negril River （SNR）. These sewage discharges significantly increased concentrations of NH2 and SRP （N：P -13） in the SNR, which flows into Long bay and around Negril＇s ＂West end＂. Concentrations of SRP, the primary limiting nutrient, were higher on shallow reefs of the West end in 2001 compared to 1998. Stable nitrogen isotope ratios （δ^15N） of abundant reef macroalgae on both shallow and deep reefs of the West end in 2002 were significantly higher than baseline values in 1998, indicating an escalating impact of sewage nitrogen pollution over this timeframe. The increased nutrient concentrations and δ^15N enrichment of reef macroalgae correlated with blooms of the chlorophyte Chaetornorpha linum in shallow waters of Long bay and Codium isthrnocladum and Caulerpa cupressoides on deep reefs of the West end. Sewage treatment systems adjacent to coral reefs must include nutrient removal to ensure that DIN and SRP concentrations, after dilution, are below the low thresholds noted for these oligotrophic ecosystems.

关键词： macroalgae sewage carbon nitrogen phosphorus stable nitrogen isotopes eutrophication

Potential mechanisms of pore-fluid movement from continental lithospheric mantle into upper continental crust

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Journal of Central South University of Technology 2008年第1期15卷 81-88页

作者：赵崇斌彭省临刘亮明 b. e. HObbS A. ORD Computational Geosciences Research Centre Central South University CSIRO Division of exploration and Mining P. O. Box 1130 Bentley WA 6102 Australia

Through integrating the state of the art scientific knowledge in different research fields, some potential mechanisms of large-scale movements of underground pore-fluids such as H2O and CO2 in the continental lithosphere were presented and discussed. The results show that the generation and propagation of porosity waves are important mechanisms to transport mass and heat fluxes from the continental lithospheric mantle into the lower continental crust; the generation and propagation of porosity waves, pore-fluid flow focusing through lower and middle crustal faults, advection of pore-fluids through the lower and middle crust, and whole-crust convection in some particular cases are important mechanisms to transport mass and heat fluxes from the lower into the upper continental crust; heat and mass transport through convective pore-fluid flow is the most effective mechanism of ore body formation and mineralization in hydrothermal systems; due to heat and mass exchange at the interface between the earth surface, hydrosphere and atmosphere, it is very important to consider the hydro-geological effect of the deep earth pore-fluids such as H2O and CO2 on the global warming and climate change in future investigations.

关键词： underground pore-fluid porosity wave continental crust heat and mass transport