Close-to-nature forest management has been proposed as an effective method for improving the quality of plantation forests. Knowledge of spatial distribution patterns, structure, and succession trajectories in natural...Close-to-nature forest management has been proposed as an effective method for improving the quality of plantation forests. Knowledge of spatial distribution patterns, structure, and succession trajectories in natural forests can provide guidelines for the establishment of close-to-nature forest plantations. Such knowledge is lacking in natural spruce(Picea crassifolia) forests in the Qilian Mountains of China, impeding the establishment of production forests. We conducted a case study in the Qilian Mountains to analyze the relationships between the naturally-formed forest patches and terrain factors, spatial heterogeneity of stand characteristics, and stand structure following harvesting disturbance. Our results suggested that spruce plantations will be effective on the N, NE, and NW slopes, at elevations between 2700 and 3300 m, and on slopes ranging from 15° to 45°. Further, planted forest patches should occupy 64% of the slope area on semi-shady slopes(NE, NW). Spatial patterns in the studied forest exhibited a strong scale-effect, and an area of 0.25 ha could be used as the most efficient plot scale for the management of spruce plantations. Partial logging is an effective method for the conversion of spruce planted forests into nearnatural forests, and the intensity of partial logging can be determined from the negative exponential function relationship between stand density and DBH. Our results provided critical information for the development of spruce plantations and conversion of existing plantations.展开更多
This paper concerns the theme of the universal accessibility to urban spaces, proposing the contribution of configurational approach to their inclusive design. Born in the first Nineties on the roots of the efforts an...This paper concerns the theme of the universal accessibility to urban spaces, proposing the contribution of configurational approach to their inclusive design. Born in the first Nineties on the roots of the efforts and the studies for reducing material and architectural barriers for disabled people, such discipline extends its sphere and purposes so as to mitigate the effects of spatial exclusion of a wider and wider variety of human categories, up to virtually include any potential urban user. Several questions persuade that a merely functional approach, essentially based on the position of the located activities, cannot be said satisfying： only a configurational approach can account for the effects of the grid configuration on the actual accessibility of its spaces. Our research focuses on Italian urban settlements, which appear as ideal case studies, due to the typical consistency of their urban spaces, which, especially in the inner historical cores, are densely build, geometrically irregular and hence generally far from actually providing a universal material accessibility. Here the impedance of space is much more than a theoretical hypothesis and concrete interventions are generally requested to eliminate or reduce its barriers and to make space actually and safely usable. Rather than at indicating the technical solution of single urban problems, which of course are strongly different each other, the research aims at defining a method suitable for any local context. Such method, integrating into a reliable tool the configurational vision with the functional and interactional approach, will provide a hierarchy of urban spaces with reference to the necessity of their universal accessibility.展开更多
Let Pt denote the tubular hypersurface of radius t around a given compatible submanifold in a symmetric space of arbitrary rank. The authors will obtain some relations between the integrated mean curvatures of P, and ...Let Pt denote the tubular hypersurface of radius t around a given compatible submanifold in a symmetric space of arbitrary rank. The authors will obtain some relations between the integrated mean curvatures of P, and their derivatives with respect to f. Moreover, the authors will emphasize the differences between the results obtained for rank one and arbitrary rank symmetric spaces.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.41522102,41701296,and 41601051)the CAS“Light of West China”Program
文摘Close-to-nature forest management has been proposed as an effective method for improving the quality of plantation forests. Knowledge of spatial distribution patterns, structure, and succession trajectories in natural forests can provide guidelines for the establishment of close-to-nature forest plantations. Such knowledge is lacking in natural spruce(Picea crassifolia) forests in the Qilian Mountains of China, impeding the establishment of production forests. We conducted a case study in the Qilian Mountains to analyze the relationships between the naturally-formed forest patches and terrain factors, spatial heterogeneity of stand characteristics, and stand structure following harvesting disturbance. Our results suggested that spruce plantations will be effective on the N, NE, and NW slopes, at elevations between 2700 and 3300 m, and on slopes ranging from 15° to 45°. Further, planted forest patches should occupy 64% of the slope area on semi-shady slopes(NE, NW). Spatial patterns in the studied forest exhibited a strong scale-effect, and an area of 0.25 ha could be used as the most efficient plot scale for the management of spruce plantations. Partial logging is an effective method for the conversion of spruce planted forests into nearnatural forests, and the intensity of partial logging can be determined from the negative exponential function relationship between stand density and DBH. Our results provided critical information for the development of spruce plantations and conversion of existing plantations.
文摘This paper concerns the theme of the universal accessibility to urban spaces, proposing the contribution of configurational approach to their inclusive design. Born in the first Nineties on the roots of the efforts and the studies for reducing material and architectural barriers for disabled people, such discipline extends its sphere and purposes so as to mitigate the effects of spatial exclusion of a wider and wider variety of human categories, up to virtually include any potential urban user. Several questions persuade that a merely functional approach, essentially based on the position of the located activities, cannot be said satisfying： only a configurational approach can account for the effects of the grid configuration on the actual accessibility of its spaces. Our research focuses on Italian urban settlements, which appear as ideal case studies, due to the typical consistency of their urban spaces, which, especially in the inner historical cores, are densely build, geometrically irregular and hence generally far from actually providing a universal material accessibility. Here the impedance of space is much more than a theoretical hypothesis and concrete interventions are generally requested to eliminate or reduce its barriers and to make space actually and safely usable. Rather than at indicating the technical solution of single urban problems, which of course are strongly different each other, the research aims at defining a method suitable for any local context. Such method, integrating into a reliable tool the configurational vision with the functional and interactional approach, will provide a hierarchy of urban spaces with reference to the necessity of their universal accessibility.
文摘Let Pt denote the tubular hypersurface of radius t around a given compatible submanifold in a symmetric space of arbitrary rank. The authors will obtain some relations between the integrated mean curvatures of P, and their derivatives with respect to f. Moreover, the authors will emphasize the differences between the results obtained for rank one and arbitrary rank symmetric spaces.
