New and perhaps unexpected progress in rate-independent elastoplastic modeling is reported with a unified approach toward simulating widely ranging non-elastic effects of various advanced engineering materials such as...New and perhaps unexpected progress in rate-independent elastoplastic modeling is reported with a unified approach toward simulating widely ranging non-elastic effects of various advanced engineering materials such as metals,shape memory alloys,granular materials,fiber-reinforced composites,as well as crystalline solids,etc.This progress originates from a simple idea of bypassing inherent limitations of usual elastoplastic formulations centered on the notion of yielding.With no reference to any yield criteria,the plastic strain-rate should be induced at all stress levels in a more realistic sense that it is small for stresses within a classical yield surface and becomes appreciable for stresses close to and on this surface.A new and unified flow rule for the plastic strain-rate is then proposed of the same smooth form for all cases of both the stress level and the stress rate.Without imposing the ad hoc simplified conditions introduced in usual Prandtl-Reuss equations,new elastoplastic equations are then established by incorporating such small deviations from realistic behaviors as neglected just by postulating these conditions.It turns out that the new equations are not only essentially simpler in both conceptual and structural formulations,but can automatically as inherent response features incorporate significant effects excluded from usual Prandtl-Reuss equations,such as the yielding and unloading behaviors with smooth transitions,the pseudo-elastic effect with hysteresis loops,the non-elastic recovery during unloading as well as failure effects under either monotone or cyclic loading conditions,etc.Since such effects not only go beyond the scope of usual elastoplastic equations but can be only partially simulated even if augmented constitutive equations are postulated toward further characterizing damaging and fracturing effects resulting from evolving micro-defects and macro-cracks,it may be probably surprising that now the new equations of essentially simpler structure not only can in a unified manner simulate all these effects but also can bypass numerical complexities in integrating various rate constitutive equations of complex structures.New results in treating long-standing issues in a few respects are presented,including(i)the yielding and the unloading behaviors with smooth transitions,(ii)the non-elastic recovery during unloading,(iii)the pseudo-elastic effect as extraordinary Bauschinger effect,(iv)failure effects under monotone and cyclic loading,(v)anisotropic multi-mode failure effects of unidirectional composites,(vi)new formulation of crystal elastoplasticity without involving non-uniqueness and singularity issues,(vii)non-normality effects for non-proportional multi-axial loading cases,and(viii)high efficiency algorithms for simulating multi-axial fatigue effects.展开更多
Chinese vice premier calls for consolidation of poverty alleviation workChinese Vice Premier Liu Guozhong on June 5 called for unremitting work to consolidate and expand China’s poverty alleviation achievements,and t...Chinese vice premier calls for consolidation of poverty alleviation workChinese Vice Premier Liu Guozhong on June 5 called for unremitting work to consolidate and expand China’s poverty alleviation achievements,and to guarantee a smooth transition to assisting rural areas on a regular basis.展开更多
Impedance measurement is an effective solution for evaluating stability of a power system with high penetration of renewable sources.In this paper,the impedance measurement is achieved by a typical high-power impedanc...Impedance measurement is an effective solution for evaluating stability of a power system with high penetration of renewable sources.In this paper,the impedance measurement is achieved by a typical high-power impedance measuring converter(HPIM-converter)with chirp signal injection.The modulation saturation phenomenon of the HPIM-converter is revealed,and the frequency sweep boundary is analyzed in detail.To expand the rated frequency range of the HPIM-converter,a spread frequency band control scheme based on an over-modulation technique is proposed in this paper.The proposed control method enlarges the rated frequency band and can inject a disturbance voltage into the system under test with consistent amplitude in the rated frequency band.Also,a smooth transition strategy between linear modulation mode and over-modulation mode is proposed for suppressing signal fluctuation.Finally,the effectiveness of the proposed method is verified by simulation tests.展开更多
Discrete Level of Detail (LOD) strategy is an effective solution for balancing the inherentcontradiction between quality and speed in computer graphics. However, application ofthis strategy requires both the appropria...Discrete Level of Detail (LOD) strategy is an effective solution for balancing the inherentcontradiction between quality and speed in computer graphics. However, application ofthis strategy requires both the appropriate selection approach and the visually comfortable transition procedure to reduce the popping effects introduced by switching betweendifferent levels. In this paper, a novel automatic LOD selection method based on viewpoint entropy was proposed. Firstly, the traditional calculation method of viewpointentropy contained in a scene was improved for the preprocessing of LOD models. Then,the runtime rendering scheme combined with our selection method was designed forbalance of frame rate during real-time rendering, and a novel smoothing LOD transitionstrategy based on Alternate Frame Rendered (ALR) was put forward for eliminationof popping effects. Finally, an example of complex scene combined with our proposalwas researched to verify its real-time performance and ability in holding continuity ofrendered images. Experimental studies show the effectiveness for stabilizing frame rateand improvements in reducing loss of continuity.展开更多
Since the 1980s, the Chinese economy has developed rapidly, with an av- erage annual growth rate around 10%. Energy consumption in China has greatly in- creased as well. This paper investigates the relationship betwee...Since the 1980s, the Chinese economy has developed rapidly, with an av- erage annual growth rate around 10%. Energy consumption in China has greatly in- creased as well. This paper investigates the relationship between energy consumption, economic development and temperature in China by adopting provincial panel data from 1990 to 2011. Different from existing studies, in this paper, we use a panel smooth transition regression （PSTR） model to estimate the non-linearity relationship. Four different threshold variables including two lagged endogenous variables and two important exogenous variables have been considered. We find that energy intensity and the ratio of gross capital formation are suitable for the non-linearity model. The estimated elasticities of time dynamic indicate that energy consumption is income in- elastic and temperature inelastic. Elasticities of real income at first increase and then decrease, however, elasticities of temperature gradually increase after the year 1993. Last of all, we propose some policy implications.展开更多
基金the German Science Foundation(DFG)for supportFuyao University of Science and Technology of Fujian,China+1 种基金supported by the National Natural Science Foundation of China(Grant Nos.12172149 and 12172151)the Ministry of Science and Technology of China(Grant No.G20221990122)。
文摘New and perhaps unexpected progress in rate-independent elastoplastic modeling is reported with a unified approach toward simulating widely ranging non-elastic effects of various advanced engineering materials such as metals,shape memory alloys,granular materials,fiber-reinforced composites,as well as crystalline solids,etc.This progress originates from a simple idea of bypassing inherent limitations of usual elastoplastic formulations centered on the notion of yielding.With no reference to any yield criteria,the plastic strain-rate should be induced at all stress levels in a more realistic sense that it is small for stresses within a classical yield surface and becomes appreciable for stresses close to and on this surface.A new and unified flow rule for the plastic strain-rate is then proposed of the same smooth form for all cases of both the stress level and the stress rate.Without imposing the ad hoc simplified conditions introduced in usual Prandtl-Reuss equations,new elastoplastic equations are then established by incorporating such small deviations from realistic behaviors as neglected just by postulating these conditions.It turns out that the new equations are not only essentially simpler in both conceptual and structural formulations,but can automatically as inherent response features incorporate significant effects excluded from usual Prandtl-Reuss equations,such as the yielding and unloading behaviors with smooth transitions,the pseudo-elastic effect with hysteresis loops,the non-elastic recovery during unloading as well as failure effects under either monotone or cyclic loading conditions,etc.Since such effects not only go beyond the scope of usual elastoplastic equations but can be only partially simulated even if augmented constitutive equations are postulated toward further characterizing damaging and fracturing effects resulting from evolving micro-defects and macro-cracks,it may be probably surprising that now the new equations of essentially simpler structure not only can in a unified manner simulate all these effects but also can bypass numerical complexities in integrating various rate constitutive equations of complex structures.New results in treating long-standing issues in a few respects are presented,including(i)the yielding and the unloading behaviors with smooth transitions,(ii)the non-elastic recovery during unloading,(iii)the pseudo-elastic effect as extraordinary Bauschinger effect,(iv)failure effects under monotone and cyclic loading,(v)anisotropic multi-mode failure effects of unidirectional composites,(vi)new formulation of crystal elastoplasticity without involving non-uniqueness and singularity issues,(vii)non-normality effects for non-proportional multi-axial loading cases,and(viii)high efficiency algorithms for simulating multi-axial fatigue effects.
文摘Chinese vice premier calls for consolidation of poverty alleviation workChinese Vice Premier Liu Guozhong on June 5 called for unremitting work to consolidate and expand China’s poverty alleviation achievements,and to guarantee a smooth transition to assisting rural areas on a regular basis.
文摘Impedance measurement is an effective solution for evaluating stability of a power system with high penetration of renewable sources.In this paper,the impedance measurement is achieved by a typical high-power impedance measuring converter(HPIM-converter)with chirp signal injection.The modulation saturation phenomenon of the HPIM-converter is revealed,and the frequency sweep boundary is analyzed in detail.To expand the rated frequency range of the HPIM-converter,a spread frequency band control scheme based on an over-modulation technique is proposed in this paper.The proposed control method enlarges the rated frequency band and can inject a disturbance voltage into the system under test with consistent amplitude in the rated frequency band.Also,a smooth transition strategy between linear modulation mode and over-modulation mode is proposed for suppressing signal fluctuation.Finally,the effectiveness of the proposed method is verified by simulation tests.
文摘Discrete Level of Detail (LOD) strategy is an effective solution for balancing the inherentcontradiction between quality and speed in computer graphics. However, application ofthis strategy requires both the appropriate selection approach and the visually comfortable transition procedure to reduce the popping effects introduced by switching betweendifferent levels. In this paper, a novel automatic LOD selection method based on viewpoint entropy was proposed. Firstly, the traditional calculation method of viewpointentropy contained in a scene was improved for the preprocessing of LOD models. Then,the runtime rendering scheme combined with our selection method was designed forbalance of frame rate during real-time rendering, and a novel smoothing LOD transitionstrategy based on Alternate Frame Rendered (ALR) was put forward for eliminationof popping effects. Finally, an example of complex scene combined with our proposalwas researched to verify its real-time performance and ability in holding continuity ofrendered images. Experimental studies show the effectiveness for stabilizing frame rateand improvements in reducing loss of continuity.
基金The authors thank the reviewers for their careful reading and provid- ing some pertinent suggestions. The research is supported by the National Natural Science Foundation of China （No. 71073009 ）, Chinese science and technology supporting program （No. 2012BAC20B08） and Tianjin City High School Science ＆ Technology Fund Planning Project （No. 20130823）.
文摘Since the 1980s, the Chinese economy has developed rapidly, with an av- erage annual growth rate around 10%. Energy consumption in China has greatly in- creased as well. This paper investigates the relationship between energy consumption, economic development and temperature in China by adopting provincial panel data from 1990 to 2011. Different from existing studies, in this paper, we use a panel smooth transition regression （PSTR） model to estimate the non-linearity relationship. Four different threshold variables including two lagged endogenous variables and two important exogenous variables have been considered. We find that energy intensity and the ratio of gross capital formation are suitable for the non-linearity model. The estimated elasticities of time dynamic indicate that energy consumption is income in- elastic and temperature inelastic. Elasticities of real income at first increase and then decrease, however, elasticities of temperature gradually increase after the year 1993. Last of all, we propose some policy implications.
