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Based on the characteristics of 1D waves,the stress uniformity process in specimens under different loading conditions of rectangular and half-sine input waves was analyzed in split Hopkinson pressure bar (SHPB) test.The results show that the times of an elastic wave propa-gating from one end to the other in a specimen to attain stress equilibrium,is related to input wave-forms and relative mechanical impedance between the specimen and the input/output bars.Here-into,with the increae of the relative impedance,the times decreases under rectangular input waves loading,while it increases under half-sine input wave loading.The dimensionless stress value of specimen corresponding to the status of stress equilibrium increases with the increase of the rela-tive mechanical impedance.However,the dimensionless stress value under half-sine input wave loading is significantly lower than the value under rectangular input wave loading for specimen with low mechanical impedance,and the relative differentia of the dimensionless stress values under two loading conditions decreases with the increase of the relative mechanical impedance.In gen-eral,the forced state of specimen with relatively low mechanical impedance under half-sine input wave loading is evidently superior to the state under rectangular input wave loading in SHPB test,and the advantages of forced state under half-sine input wave loading turns weak with the increase of the relative mechanical impedance.  相似文献   
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矿区生态经济系统的动态演化是其经济、资源和环境等诸构成要素之间结构优化和整体协同耦合的过程,离不开自组织机制、需求机制、价格机制等内生性机制和调控机制、保障机制、约束机制等外在性机制的作用,这些内生性机制和外在性机制共同构成了矿区生态经济系统动态演化的动力机制.根据动态演化的不同阶段制定不同的发展策略,从而实现矿区生态经济系统的可持续发展.  相似文献   
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