Larger amount of national and provincial forest eco-compensation funds in China have been distributed to farmers annually,which aims to encourage farmers input more labor and fund in daily forestry management.We selec...Larger amount of national and provincial forest eco-compensation funds in China have been distributed to farmers annually,which aims to encourage farmers input more labor and fund in daily forestry management.We selected 503 household from 50 villages of 10 counties in Jiangxi Province in the paper.Household labor and cash input responded negatively towards forest eco-compensation fund in forestry management.Forest eco-compensation subsidy(FECS)granted to the household in the rural mountain area didn't stimulate the household labor and cash input in forestry management.It implies that it is not a wise way to distribute FECS equally to the rural household,so as to promote the forestry ecological quality.The current forest eco-compensation policy(FECP)need modifying urgently.展开更多
This paper employs a velocity plus displacement（V＋D）-based equivalent force control（EFC） method to solve the velocity/displacement difference equation in a real-time substructure test. This method uses type 2 fee...This paper employs a velocity plus displacement（V＋D）-based equivalent force control（EFC） method to solve the velocity/displacement difference equation in a real-time substructure test. This method uses type 2 feedback control loops to replace mathematical iteration to solve the nonlinear dynamic equation. A spectral radius analysis of the amplification matrix shows that the type 2 EFC-explicit, Newmark-β method has beneficial numerical characteristics for this method. Its stability limit of Ω = 2 remains unchanged regardless of the system damping because the velocity is achieved with very high accuracy during simulation. In contrast, the stability limits of the central difference method using direct velocity prediction and the EFC-average acceleration method with linear interpolation are shown to decrease with an increase in system damping. In fact, the EFC-average acceleration method is shown to change from unconditionally stable to conditionally stable. We also show that if an over-damped system with a damping ratio of 1.05 is considered, the stability limit is reduced to Ω =1.45. Finally, the results from an experiment with a single-degree-of-freedom structure installed with a magneto-rheological（MR） damper are presented. The results demonstrate that the proposed method is able to follow both displacement and velocity commands with moderate accuracy, resulting in improved test performance and accuracy for structures that are sensitive to both velocity and displacement inputs. Although the findings of the study are promising, additional test data and several further improvements will be required to draw general conclusions.展开更多
基金National Natural Science Foundation of China(No.71663027,41701622 and 71840013)Soft Science Program of Jiangxi Province,China(No.20161BBA10008)Humanities and Social Sciences Program of Jiangxi Province,China(No.JD16086)。
文摘Larger amount of national and provincial forest eco-compensation funds in China have been distributed to farmers annually,which aims to encourage farmers input more labor and fund in daily forestry management.We selected 503 household from 50 villages of 10 counties in Jiangxi Province in the paper.Household labor and cash input responded negatively towards forest eco-compensation fund in forestry management.Forest eco-compensation subsidy(FECS)granted to the household in the rural mountain area didn't stimulate the household labor and cash input in forestry management.It implies that it is not a wise way to distribute FECS equally to the rural household,so as to promote the forestry ecological quality.The current forest eco-compensation policy(FECP)need modifying urgently.
基金Scientific Research Fund of the Institute of Engineering Mechanics,CEA under Grant No.2016B09,2017A02 and 2016A06the National Natural Science Foundation of China under Grant No,51378478,51408565,51678538 and 51161120360the National ScienceTechnology Support Plan Projects(2016YFC0701106)
文摘This paper employs a velocity plus displacement（V＋D）-based equivalent force control（EFC） method to solve the velocity/displacement difference equation in a real-time substructure test. This method uses type 2 feedback control loops to replace mathematical iteration to solve the nonlinear dynamic equation. A spectral radius analysis of the amplification matrix shows that the type 2 EFC-explicit, Newmark-β method has beneficial numerical characteristics for this method. Its stability limit of Ω = 2 remains unchanged regardless of the system damping because the velocity is achieved with very high accuracy during simulation. In contrast, the stability limits of the central difference method using direct velocity prediction and the EFC-average acceleration method with linear interpolation are shown to decrease with an increase in system damping. In fact, the EFC-average acceleration method is shown to change from unconditionally stable to conditionally stable. We also show that if an over-damped system with a damping ratio of 1.05 is considered, the stability limit is reduced to Ω =1.45. Finally, the results from an experiment with a single-degree-of-freedom structure installed with a magneto-rheological（MR） damper are presented. The results demonstrate that the proposed method is able to follow both displacement and velocity commands with moderate accuracy, resulting in improved test performance and accuracy for structures that are sensitive to both velocity and displacement inputs. Although the findings of the study are promising, additional test data and several further improvements will be required to draw general conclusions.
