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 eq...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.展开更多
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 on...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.展开更多
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...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.展开更多
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 c...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.展开更多
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.T...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.展开更多
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 ...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.展开更多
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 mapp...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.展开更多
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. Bas...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<sub>1</sub> plane and z<sub>2</sub> 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.展开更多
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 a...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.展开更多
基金Supported by the Doctorate Station Foundation of State Educational Commission of China。
文摘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.
基金This study is supported by National Natural Science Foundation of China。
文摘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.
基金The project supported by the National Natural Science Foundation of China (K19672007)
文摘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.
基金Supported by Doctorate Station Foundation of State Educational Commission of China。
文摘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.
基金Supported by National Natural Science Foundation of China。
文摘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.
基金financially supported by the National Natural Science Foundation of China(NSFC)(No.51172018)the National High Technical Research and Development Programme of China(No.2009BAE74B00)+1 种基金the National Basic Research Program of China(No.2006CB605207)MOE Program for Changjiang Scholars and Innovative Research Team in University of China(No.I2P407)
文摘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.
基金Acknowledgements Work at Beijing Institute of Technology was supported by the National Natural Science Foundation of China （Nos. 23171023 and 50972017） and Doctoral Program of the Ministry of Education of China （No. 20101101110026） Work at Peking University was supported by the NSFC-RGC Joint Research Scheme （No. 51361165201）, the National Natural Science Foundation of China （Nos. 51125001 and 51172005）, Beijing Natural Science Foundation （No. 2122022） and Doctoral Program of the Ministry of Education of China （No. 20120001110078）. Deanship of Scientific Research at King Saud University through Prolific Research Group Project （No. PRG-1436-25）.
文摘为氧和氢进化反应(OER/HER ) 的催化剂在精力采购例如切开的水的可更新的绿色的心。尽管不可思议的努力被作了为 OER 和她开发有效催化剂，大挑战在 bifunctional 催化剂的发展尚待。这里，我们报导公司 <sub>3</sub 的一个新奇混血儿 > 在 graphitic 碳氮化物(GCN ) 的管状的 nanostructures 嵌入并且在低温度通过一个灵巧的、大规模化学方法综合了的 O <sub>4</sub> 。在公司 <sub>3</sub 之间的强壮的 synergistic 效果 > O <sub>4</sub> 和 GCN 为 OER 和她作为 bifunctional 催化剂导致了优秀性能。混血儿的高表面区域，唯一的管状的 nanostructure，和作文为催化作用使所有氧化还原作用地点容易可得到并且提供了更快的离子、电子的传导。公司 <sub>3</sub > O <sub>4</sub>@GCN 管状的 nanostructured (TNS ) 混血儿展出了最低过电位(0.12 V ) 和优秀当前的密度(在 OER 的 147 妈 / 厘米 <sup>2</sup>) ，比基准 IrO <sub>2</sub> 和 RuO <sub>2</sub>, 并且与在碱的媒介的优异耐久性好。而且，公司 <sub>3</sub > O <sub>4</sub>@GCN TNS 混血儿在她表明了优秀性能与低得多的发作和过电位，并且稳定的当前的密度。这被期望公司 <sub>3</sub > 在这研究开发的 O <sub>4</sub>@GCN TNS 混血儿将是在大规模水切开和燃料房间的高贵金属催化剂的一种吸引人的选择。
基金Project supported by the National Natural Science Foundation of China.
文摘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.
基金Project supported by the National Natural Science Foundation of China
文摘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<sub>1</sub> plane and z<sub>2</sub> 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.
基金supported by Higher Education Commission (HEC), Islamabad, Pakistan under PhD indigenous-5000 Fellowship Program
文摘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.
