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CONTENTS
Volume 4, Number 2, June 2015
 

Abstract
The energy crisis involving depletion of fossil fuel resource is not the sole driving force for developing renewable energy technologies. Another driving force is the ever increasing concerns on the air quality of our planet, associated with the continuous and dramatic increase of the concentration of greenhouse gas (mainly carbon dioxide) emissions. The internal combustion engine is a major source of distributed CO2 emissions caused by combustion of gasoline derived largely from fossil fuel. Another major source of CO2 is the combustion of fossil fuels to produce electricity. New technologies for generating electricity from sources that do not emit CO2, such as water, solar, wind, and nuclear, together with the advent of plug-in hybrid electric vehicles (PHEV) and even all-electric vehicles (EVs), offer the potential of alleviating our present problem. Therefore, the relevant technologies in LiFePO4 as cathode material for Li-ion batteries suitable to the friendly environment are reviewed aim to provide the vital information about the growing field for energies to minimize the potential environmental risks.

Key Words
LiFePO4; cathode material; Li-ion batteries; nanotechnology

Address
Kelvii Wei Guo

Abstract
The influence of rare earth lanthanum (La) on solidification cooling range, microstructure of aluminum-magnesium (Al-Mg) alloy and mechanical properties were investigated. Five kinds of Al-Mg alloys with rare earth content of La (i.e., 0, 0.5, 1.0, 1.5 and 2.0 wt.%) were prepared. Samples were either slowly cooled in furnace or water cooled. Results indicate that the addition of the rare earth (RE) La can significantly influence the solidification range, the resultant microstructure, and tensile strength. RE La can extend the alloy solidification range, increase the solidification time, and also greatly improve the flow performance. The addition of La takes a metamorphism effect on Al-Mg alloy, resulting in that the finer the grain is obtained, the rounder the morphology becomes. RE La can significantly increase the mechanical properties for its metamorphism and reinforcement. When the La content is about 1.5 wt.%, the tensile strength of Al-Mg alloy reaches its maximum value of 314 MPa.

Key Words
Al-Mg alloy; rare earth lanthanum (La); solidification curve; microstructure; extrusion; tensile strength

Address
Shikun Xie, Rongxi Yi, Xiuyan Guo, Xiaoliang Pan and Xiang Xia

Abstract
In this paper, three-dimensional finite element method is used to analyze the J integral for repaired cracks in plates with bonded composite patch and stiffeners. For elastic the effect of cracks, the thickness of the patch (er) and properties of the patch are presented for calculating the J integral. For elastic-plastic a several calculations have been realized to extract the plasticized elements around the crack tip of repaired and un-repaired crack. The obtained results show that the presence of the composite patch and stiffener reduces considerably the size of the plastic zone ahead of the crack. The effects of crack size and the inter-distance of repaired cracks were analysed.

Key Words
composite; finite element method; crack; J integral; fracture mechanic; elastic-plastic

Address
Mokadem Salem, Belabbes Bachir Bouiadjra, Belaïd Mechab
and Khacem Kaddouri: LMPM, Department of Mechanical Engineering, University of Sidi Bel Abbes, BP 89 Cite Ben M\'hidi 22000, Sidi Bel Abbes, Algeria

Abstract
Polypropylene short fiber (PP)-clay particulate-epoxy ternary composites were prepared by reinforcing PP short fiber and clay particles in the range of 0.1 phr to 0.7 phr into epoxy resin. Prepared hybrid composites were characterized for their mechanical, thermal and flame retardant properties. The obtained results indicated an increase in impact resistance, tensile strength, flexural strength and Young

Key Words
hybrid; synergistic effect; flame retardance; mechanical properties; thermal properties

Address
T. Niranjana Prabhu: Department of Chemistry, M.S. Ramaiah University of Applied Sciences, Bangalore-560058, Karnataka, India
T. Demappa: Department of Studies and Research in Polymer Science, Sir M.V. Postgraduate Centre,
University of Mysore, Tubinakere, Mandya-571402, Karnataka, India
V. Harish: Department of Physics, Government First Grade College, Shimoga-577201, Karnataka, India
K. Prashantha: Ecole des Mines de Douai., Department of Polymers and Composites Technology & Mechanical Engineering, 941 rue Charles Bourseul, BP 10838, F-59508 Douai Cedex, France

Abstract
The phenomena of high-voltage polarization and conductivity in oriented vinylidenefluoride and tetrafluoroethylene copolymer films have been investigated. It was shown that under certain electric fields, injection of carriers from the material of electrodes appears The barrier for holes injection in the copolymer was found to be lower than that for electrons. It results in more effective screening of the external field near the anode than near cathode. Electrones, ejected from cathode, creating negative charge by trapping on the surface. It is shown that the electrons injected from cathodes create a negative homocharge on the copolymer surface and then become captured on the surface shallow traps. Their nature has been studied by the x-ray photoelectron spectroscopy. It was shown that these traps may consist of chemical defects in the form of new functional groups formed by reactions of surface macromolecules with sputtered atoms of aluminum. The asymmetric shape of hysteresis curves was explained by the difference in mobility of injected holes and electrons. These factors caused appearance of

Key Words
crystalline polymers; ferroelectricity; conductivity; injection of charges; dielectric hysteresis; x-ray photoelectron spectroscopy

Address
V.V. Kochervinskii, A.S. Pavlov and N.I. Pakuro: Karpov Institute of Physical Chemistry, ul. Vorontsovo pole 10, Moscow, 105064, Russia
E.V. Chubunova and Y.Y. Lebedinskii: Moscow Engineering Physics Institute, National Nuclear Research University,
Kashirskoe sh. 31, Moscow, 115409, Russia


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