Piezoelectric sensor array-based spatial filter technology is a new promising method presented in research area of structural health monitoring （SHM） in the recent years. To apply this method to composite structures...Piezoelectric sensor array-based spatial filter technology is a new promising method presented in research area of structural health monitoring （SHM） in the recent years. To apply this method to composite structures and give the actual position of damage, this paper proposes a spatial filter-based damage imaging method improved by complex Shannon wavelet transform. The basic principle of spatial filter is analyzed first. Then, this paper proposes a method of using complex Shannon wavelet transform to construct analytic signals of time domain signals of PZT sensors array. The analytic signals are synthesized depending on the principle of the spatial filter to give a damage imaging in the form of angle-time. A method of converting the damage imaging to the form of angle-distance is discussed. Finally, an aircraft composite oil tank is adopted to validate the damage imaging method. The validating results show that this method can recognize angle and distance of damage successfully.展开更多
The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a ...The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the Structural Complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced Structural Complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural complexity.展开更多
The existence of many anions in wastewater reduces the removal efficiency of phosphate by adsorbents under realistic conditions.Facing this challenge,the study reports on an insistent and stable composite adsorbent of...The existence of many anions in wastewater reduces the removal efficiency of phosphate by adsorbents under realistic conditions.Facing this challenge,the study reports on an insistent and stable composite adsorbent of molybdate complexes Fe-(MoO_(x))embedded in a macroporous anion exchange resin(D-201).[Fe(MoO_(x))]-D-201 shows 93.7%adsorption capacity(28.3 mg/g)for phosphate even when the molar concentration of coexisting ions is 5 times higher than phosphate.The capacity of adsorbent is maintained more than 84.2%after five regeneration cycles to remove phosphate in the wastewater containing coexisting ions.The ability of highly selective removal of phosphate is maintained during the regeneration cycles explained by the change of the binding of molybdate clusters with phosphate,which is due to the different structures of molybdate clusters depending on various pH.In general,this work puts forward a new idea for the development of phosphorus removal adsorbents for the treatment of wastewater containing coexisting ions.展开更多
Low-dimensional materials have attracted increasing attention due to their guiding significance for material preparation and potential wide-ranging applications.Through the controllable synthesis and suitably designed...Low-dimensional materials have attracted increasing attention due to their guiding significance for material preparation and potential wide-ranging applications.Through the controllable synthesis and suitably designed fusion of lowdimensional materials into ordered complex superstructures,it has become an effective way to explore new properties of materials and construct structures meeting new application needs.Based on low-dimensional materials such as metal oxides,copolymers,metal-organic complexes,and organic crystals,great efforts have been devoted to the design and construction of complex superstructures with regular repeatability.A series of unique cases including multi-block,core/multi-shell,hyperbranched and network structures have been reported,which has promoted the development of the field of material preparation.Herein,we summarize representative progress of low-dimensional complex superstructures in a reasonable structure classification manner.Ultimately,the existing challenges are discussed,and an outlook is given for future study of precise construction of superstructures as well as exploitation of potential applications.展开更多
基金National Natural Science Foundation of China (50830201,10872217)Aeronautical Science Foundation of China (20090952015)+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education(20103218110005)National Science Foundation of the General Program of Jiangsu Higher Education Institutions (09KJD520005)
文摘Piezoelectric sensor array-based spatial filter technology is a new promising method presented in research area of structural health monitoring （SHM） in the recent years. To apply this method to composite structures and give the actual position of damage, this paper proposes a spatial filter-based damage imaging method improved by complex Shannon wavelet transform. The basic principle of spatial filter is analyzed first. Then, this paper proposes a method of using complex Shannon wavelet transform to construct analytic signals of time domain signals of PZT sensors array. The analytic signals are synthesized depending on the principle of the spatial filter to give a damage imaging in the form of angle-time. A method of converting the damage imaging to the form of angle-distance is discussed. Finally, an aircraft composite oil tank is adopted to validate the damage imaging method. The validating results show that this method can recognize angle and distance of damage successfully.
基金the Advisory Group on Inter-national Agricultural Research(BEAF)at the German Agency for International Cooperation(GIZ)within the German Ministry for Economic Cooperation(BMZ)for funding this research(project number 08.7860.3-001.00“Making the Mekong Con-nected”-MMC).
文摘The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the Structural Complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced Structural Complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural complexity.
基金supported by the National Natural Science Foundation of China(Nos.52070100,51978341)the Natural Science Foundation of Jiangsu Province of China(No.BK20190087).
文摘The existence of many anions in wastewater reduces the removal efficiency of phosphate by adsorbents under realistic conditions.Facing this challenge,the study reports on an insistent and stable composite adsorbent of molybdate complexes Fe-(MoO_(x))embedded in a macroporous anion exchange resin(D-201).[Fe(MoO_(x))]-D-201 shows 93.7%adsorption capacity(28.3 mg/g)for phosphate even when the molar concentration of coexisting ions is 5 times higher than phosphate.The capacity of adsorbent is maintained more than 84.2%after five regeneration cycles to remove phosphate in the wastewater containing coexisting ions.The ability of highly selective removal of phosphate is maintained during the regeneration cycles explained by the change of the binding of molybdate clusters with phosphate,which is due to the different structures of molybdate clusters depending on various pH.In general,this work puts forward a new idea for the development of phosphorus removal adsorbents for the treatment of wastewater containing coexisting ions.
基金supported by the National Natural Science Foundation of China(52173177,21971185 and 51821002)the Collaborative Innovation Center of Suzhou Nano Science and Technology(CIC-Nano)the“111”Project of the State Administration of Foreign Experts Affairs of China
文摘Low-dimensional materials have attracted increasing attention due to their guiding significance for material preparation and potential wide-ranging applications.Through the controllable synthesis and suitably designed fusion of lowdimensional materials into ordered complex superstructures,it has become an effective way to explore new properties of materials and construct structures meeting new application needs.Based on low-dimensional materials such as metal oxides,copolymers,metal-organic complexes,and organic crystals,great efforts have been devoted to the design and construction of complex superstructures with regular repeatability.A series of unique cases including multi-block,core/multi-shell,hyperbranched and network structures have been reported,which has promoted the development of the field of material preparation.Herein,we summarize representative progress of low-dimensional complex superstructures in a reasonable structure classification manner.Ultimately,the existing challenges are discussed,and an outlook is given for future study of precise construction of superstructures as well as exploitation of potential applications.
