New Method for Solving Elasticity Problems of Some Planar Quasicrystals and Solutions

A new method for solving elasticity problems of some planar quasicrystals is presented.The set of partial differential equations for the phonon and phason displacement components is reduced to a single higher-order equation by introducing a displacement function.A general solution formulation is suggested.As an example,the elastic field caused by a dislocation in planar quasicrystals of point groups 5 m,10,and 10mm is calculated.

EXACT SOLUTIONS OF SEMI-INFINITE CRACK IN A STRIP

This study presents a procedure for solving semi-infinite crack which is a very useful model in geophysics,seismology and engineering.With the help of conformal transformation mapping.the region in a physical plane onto the interior of a unit circle in a plane,any case of this kind of problems can be solved unifiedly,and some exact solutions are obtained.

Analytic Solution of an Asymmetrical Crack in a Strip

We present the analytic solution of an asymmetrical crack in a strip from which the stress intensity factors are determined.The results have important application in earthquake source physics and provide information concerning the instability of faults and the detection of earthquake precursors.

CONVOLUTION OF THE IMPACT THREE-DIMENSIONAL ELASTO-DYNAMICS AND DYNAMIC STRESS INTENSITY FACTOR FOR AN ELLIPTIC CRACK

This paper presents a formulation for three-dimensional elasto-dynamics with an elliptic crack based on the Laplace and Fourier transforms and the convolution theorem. The dynamic stress intensity factor for the crack is determined by solving a Fredholm integral equation of the first kind. The results of this paper are very close to those given by the two-dimensional dual integral equation method.

PROPAGATING CRACK IN A STRIP AND ITS EXACT SOLUTION

This letter reports some results on propagating crack in a strip,which are exact solutions with closed form and reduced to the exact solutions in static case given by the author before,as crack speed V tends to zero.These results are significant in the research of seismology,materials science,and engineering.

Improvement of a High Velocity Compaction Technique for Iron Powder

Water atomized pure iron powder was compacted by high velocity compaction （HVC） with and without upper relaxation assist （URA） device. The influence of URA device on green density, spring back, green strength and hardness was studied. Morphological characteristics of the samples were observed by scanning electron microscope （SEM）. Green strength of the samples was measured by computer controlled universal testing machine. The results show that as stroke length increases, the green density, green strength and hardness of the compacts increase gradually. At the identical stroke length, the green density of the compacts pressed with URA devise was 2% higher than the compacts pressed without URA device. The green strength and hardness of the compacts pressed with URA device were higher than the compacts pressed without URA device. Furthermore, the radial spring back of the compacts decreased gradually with the increment in stroke length, whilst that of compacts prepared with URA device was lower.

Bifunctional catalysts of Co3O4@GCN tubular nanostructured （TNS） hybrids for oxygen and hydrogen evolution reactions

Catalysts for oxygen and hydrogen evolution reactions （OER/HER） are at the heart of renewable green energy sources such as water splitting. Although incredible efforts have been made to develop efficient catalysts for OER and HER, great challenges still remain in the development of bifunctional catalysts. Here, we report a novel hybrid of Co3O4 embedded in tubular nanostructures of graphitic carbon nitride （GCN） and synthesized through a facile, large-scale chemical method at low temperature. Strong synergistic effects between Co3O4 and GCN resulted in excellent performance as a bifunctional catalyst for OER and HER. The high surface area, unique tubular nanostructure, and composition of the hybrid made all redox sites easily available for catalysis and provided faster ionic and electronic conduction. The Co3O4@GCN tubular nanostructured （TNS） hybrid exhibited the lowest overpotential （0.12 V） and excellent current density （147 mA/cm^2） in OER, better than benchmarks IrO2 and RuO2, and with superior durability in alkaline media. Furthermore, the Co3O4@GCN TNS hybrid demonstrated excellent performance in HER, with a much lower onset and overpotential, and a stable current density. It is expected that the Co3O4@GCN TNS hybrid developed in this study will be an attractive alternative to noble metals catalysts in large scale water splitting and fuel cells.

Mathematical modelling on instability of shear fault

A study on mathematical modelling on instability of fault is reported.The fracture mechanics and fracture dynamics as a basis of the discussion,and the method of complex variable function (including the conformal mapping and approximate conformal mapping) are employed,and some analytic solutions of the problem in closed form are found.The fault body concept is emphasized and the characteristic size of fault body is introduced.The effect of finite size of the fault body and the effect of the fault propagating speed (especially the effect of the high speed) and their influence on the fault instability are discussed.These results further explain the low-stress drop phenomena observed in earthquake source.

EXACT ANALYTIC SOLUTIONS OF STATIONARY AND FAST PROPAGATING CRACKS IN A STRIP

The stress boundary-value problem of a semi-infinite crack in a strip has been thorough-ly solved in terms of conformal mapping. Subsequently a more difficult problem, propa-gating crack in a strip, is considered. Based on the formulation developed by the author, byusing conformal transformation mapping regions in z_1 plane and z_2 plane onto the interiorof the unit circle in ζ plane, the rather complicated boundary-value problem of the waveequations is also solved thoroughly. The exact analytic solutions in closed form are achiev-ed, and the dynamic solutions reduce to the static ones when crack speed V→0.

Synthesis of Nanostructured Mg-Ni Alloy and Its Hydrogen Storage Properties

Nanostructured Mg–Ni alloy with the particle size in the range of 40–50 nm was synthesized by the thermal decomposition of bipyridyl complexes of Mg and Ni metals at 773 K for 24 h under dry argon gas ambient. The as-prepared nano-alloy was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM） for compositional and structural analysis. The alloy exhibited superior hydrogen absorption and desorption behavior with 3.2 wt% absorption within 1 min at 573 K and about 3 wt% desorption within 5–10 min at 573 K. This favorable behavior of Mg–Ni compound for the hydrogen storage is due to the specific nanostructure of the material. The low activation energy values and favorable thermodynamics indicate that the prepared Mg–Ni alloy is an attracting material for hydrogen storage applications.

Atypical BiOCl/Bi_2S_3 hetero-structures exhibiting remarkable photo-catalyst response

We demonstrate the fabrication of BiOCl/Bi_2S_3 which is well defined at a large scale. The BiOCl/Bi_2S_3 heterostructures exhibit an enhanced photo-catalytic degradation of methyl orange（MO） compared to BiOCl and Bi_2S_3, attributed to the interface between Bi_2S_3 and BiOCl, which effectively separate the photo-induced electron-hole pairs and suppress their recombination.