Background Tropical floodplain wetlands are among the most disturbed and intensively harvested ecosystems.Their sustainable management is often hindered due to the lack of comprehensive,coherent,and standardized asses...Background Tropical floodplain wetlands are among the most disturbed and intensively harvested ecosystems.Their sustainable management is often hindered due to the lack of comprehensive,coherent,and standardized assessment frameworks of wetland ecological health(WEH).In this study,a set of appropriate criteria and indicators(C&I)of WEH assessment was developed and tested on seven wetlands of River Ichhamati,eastern India.Methods Based on the pressure-state-response(PSR)approach,evaluation indicators representing ecological,socio-economic,and institutional sustainability issues of floodplain wetland systems were either selected or formulated through literature survey and stakeholder consensus.Weights of indicators were assigned by the entropy weighting method and then used in the Technique for Order of Preference by Similarity to Ideal Solution model to determine the Euclidean distances of each wetland from the positive ideal solution and negative ideal solution.Subsequently,a comprehensive wetland ecological health index(CWEHI)was constructed from these distances to portray the condition of any PSR system component in a wetland under a fivefold classification scheme,namely‘excellent health’(CWEHI≥0.81),‘good health’(0.61-0.80),‘moderate health’(0.41-0.60),‘weak health’(0.21-0.40),and‘morbid’(≤0.20).Results The developed C&I set contains 8 criteria and 38 indicators under pressure component,7 criteria and 49 indicators under state component,as well as 4 criteria and 18 indicators under response component.When applied in 2016 and 2022,it was found that the Panchita and Aromdanga wetlands were continuously in weak and morbid health status,while the Madhabpur wetland always showed an excellent or good status for all components.Health of other wetlands oscillated between moderate and morbid health across assessment years and system components.Conclusions The developed C&I set was found to be a flexible,holistic,and refined framework that could be applied elsewhere in similar assessments with mi展开更多
Interactions among different landforms and varied complicated physical processes cause sediment transport in coastal regions being the interest of ocean management planning studies. In coastal zones, the derivation of...Interactions among different landforms and varied complicated physical processes cause sediment transport in coastal regions being the interest of ocean management planning studies. In coastal zones, the derivation of the bedload sediment transport rate and the flow velocity distribution is done by entropy theory which assumes the modified spatiotemporal disorder power index(MSTDPI) and the time-averaged flow velocity(as a random variable). Studying the deposition trend of bedload sediment transport rate for the sand particle(BLSTRS) and estimating the coastal erosion rate as a case study, the Makran coast is selected. To analyze the spatiotemporal patterns, the disorder power index(entropy-power) method is applied in this study where the monthly data of six Makran coastal sections from January 1970 to December 2015 are used. The studied data are mainly focused on the correlation of the flow rate of the sediment from the Makran River, and the spatiotemporal patterns of BLSTRS.Despite their meaningful spatiotemporal variability, it is not very easy to explain how the abovementioned variables perform together;the entropy-power index allows a better understanding of the combined performance of such parameters as the flow velocity and sediment transport by showing clearer signals for the assessment of coastal engineering issues at very large(coastal) scales.展开更多
Dynamic mechanical relaxation is a fundamental tool to understand the mechanical and physical properties of viscoelastic materials like glasses.Mechanical spectroscopy shows that the high-entropy bulk metallic glass(L...Dynamic mechanical relaxation is a fundamental tool to understand the mechanical and physical properties of viscoelastic materials like glasses.Mechanical spectroscopy shows that the high-entropy bulk metallic glass(La_(30)Ce_(30)Ni_(10)Al_(20)Co_(10))exhibits a distinctβ-relaxation feature.In the present research,dynamic mechanical analysis and thermal creep were performed using this bulk metallic glass material at a temperature domain around theβrelaxation.The components of total strain,including ideal elastic strain,anelastic strain,and viscous-plastic strain,were analyzed based on the model of shear transformation zones(STZs).The stochastic activation of STZ contributes to the anelastic strain.When the temperature or external stress is high enough or the timescale is long enough,the interaction between STZs induces viscous-plastic strain.When all the spectrum of STZs is activated,the quasi-steady-state creep is achieved.展开更多
The power-law relationship between creep rate decay and time is one of the intrinsic characteristics of metallic glasses.In the current work,a La_(30)Ce_(30)Ni_(10)Al_(20)Co_(10) high-entropy metallic glass was select...The power-law relationship between creep rate decay and time is one of the intrinsic characteristics of metallic glasses.In the current work,a La_(30)Ce_(30)Ni_(10)Al_(20)Co_(10) high-entropy metallic glass was selected as the model alloy to test the influences of physical aging and cyclic loading on the power-law creep mechanism,which was probed by the dynamic mechanical analysis in terms of the stochastic activation,and contiguous interplay and permeation of shear transformation zones.It is demonstrated that a notable discrepancy appears between thermal treatment and mechanical treatment on the power-law creep mechanism of this high-entropy metallic glass.On the one hand,physical aging below the glass transition temperature introduces the annihilation of potential shear transformation zones which contribute to creep.On the other hand,cyclic loading can tailor the“forward”jump operations competing with the“backward”ones of shear transformation zones by controlling the interval time(recovery time).The current research offers a new pathway towards understanding the creep mechanism of high-entropy metallic glasses.展开更多
基金supported by the University Grants Commission,India,under Minor Research Project scheme(Memo No.F.PHW-2009/15-16(ERO))to the first author.
文摘Background Tropical floodplain wetlands are among the most disturbed and intensively harvested ecosystems.Their sustainable management is often hindered due to the lack of comprehensive,coherent,and standardized assessment frameworks of wetland ecological health(WEH).In this study,a set of appropriate criteria and indicators(C&I)of WEH assessment was developed and tested on seven wetlands of River Ichhamati,eastern India.Methods Based on the pressure-state-response(PSR)approach,evaluation indicators representing ecological,socio-economic,and institutional sustainability issues of floodplain wetland systems were either selected or formulated through literature survey and stakeholder consensus.Weights of indicators were assigned by the entropy weighting method and then used in the Technique for Order of Preference by Similarity to Ideal Solution model to determine the Euclidean distances of each wetland from the positive ideal solution and negative ideal solution.Subsequently,a comprehensive wetland ecological health index(CWEHI)was constructed from these distances to portray the condition of any PSR system component in a wetland under a fivefold classification scheme,namely‘excellent health’(CWEHI≥0.81),‘good health’(0.61-0.80),‘moderate health’(0.41-0.60),‘weak health’(0.21-0.40),and‘morbid’(≤0.20).Results The developed C&I set contains 8 criteria and 38 indicators under pressure component,7 criteria and 49 indicators under state component,as well as 4 criteria and 18 indicators under response component.When applied in 2016 and 2022,it was found that the Panchita and Aromdanga wetlands were continuously in weak and morbid health status,while the Madhabpur wetland always showed an excellent or good status for all components.Health of other wetlands oscillated between moderate and morbid health across assessment years and system components.Conclusions The developed C&I set was found to be a flexible,holistic,and refined framework that could be applied elsewhere in similar assessments with mi
文摘Interactions among different landforms and varied complicated physical processes cause sediment transport in coastal regions being the interest of ocean management planning studies. In coastal zones, the derivation of the bedload sediment transport rate and the flow velocity distribution is done by entropy theory which assumes the modified spatiotemporal disorder power index(MSTDPI) and the time-averaged flow velocity(as a random variable). Studying the deposition trend of bedload sediment transport rate for the sand particle(BLSTRS) and estimating the coastal erosion rate as a case study, the Makran coast is selected. To analyze the spatiotemporal patterns, the disorder power index(entropy-power) method is applied in this study where the monthly data of six Makran coastal sections from January 1970 to December 2015 are used. The studied data are mainly focused on the correlation of the flow rate of the sediment from the Makran River, and the spatiotemporal patterns of BLSTRS.Despite their meaningful spatiotemporal variability, it is not very easy to explain how the abovementioned variables perform together;the entropy-power index allows a better understanding of the combined performance of such parameters as the flow velocity and sediment transport by showing clearer signals for the assessment of coastal engineering issues at very large(coastal) scales.
基金supported by the National Natural Science Foundation of China (Grant No. 51971178)the Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province (Grant No. 2021JC-12)+2 种基金financial support from MICINN(Grant No. FIS2017-82625-P)Generalitat de Catalunya (Grant No.2017SGR0042)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(Grant No. CX2021015)financially supported by the National Natural Science Foundation of China (Grant No. 12072344)
文摘Dynamic mechanical relaxation is a fundamental tool to understand the mechanical and physical properties of viscoelastic materials like glasses.Mechanical spectroscopy shows that the high-entropy bulk metallic glass(La_(30)Ce_(30)Ni_(10)Al_(20)Co_(10))exhibits a distinctβ-relaxation feature.In the present research,dynamic mechanical analysis and thermal creep were performed using this bulk metallic glass material at a temperature domain around theβrelaxation.The components of total strain,including ideal elastic strain,anelastic strain,and viscous-plastic strain,were analyzed based on the model of shear transformation zones(STZs).The stochastic activation of STZ contributes to the anelastic strain.When the temperature or external stress is high enough or the timescale is long enough,the interaction between STZs induces viscous-plastic strain.When all the spectrum of STZs is activated,the quasi-steady-state creep is achieved.
基金the National Natural Science Foundation of China(NSFC,No.51971178)the Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province(No.2021JC-12)+3 种基金the Natural Science Foundation of Chongqing(No.cstc2020jcyj-jq X0001)sponsored by Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(No.CX2021015)financial support from MICINN(grant PID2020112975GB-I00)Generalitat de Catalunya(grant 2017SGR0042)。
文摘The power-law relationship between creep rate decay and time is one of the intrinsic characteristics of metallic glasses.In the current work,a La_(30)Ce_(30)Ni_(10)Al_(20)Co_(10) high-entropy metallic glass was selected as the model alloy to test the influences of physical aging and cyclic loading on the power-law creep mechanism,which was probed by the dynamic mechanical analysis in terms of the stochastic activation,and contiguous interplay and permeation of shear transformation zones.It is demonstrated that a notable discrepancy appears between thermal treatment and mechanical treatment on the power-law creep mechanism of this high-entropy metallic glass.On the one hand,physical aging below the glass transition temperature introduces the annihilation of potential shear transformation zones which contribute to creep.On the other hand,cyclic loading can tailor the“forward”jump operations competing with the“backward”ones of shear transformation zones by controlling the interval time(recovery time).The current research offers a new pathway towards understanding the creep mechanism of high-entropy metallic glasses.
