Current situation and prospects of the studies of ecological industries and ecological products in eco-fragile areas.

The current industrial structure of eco-fragile areas fails to reverse the trend of the deterioration of the ecological environment and severely affects the sustainable development of eco-fragile areas, so conducting scientific and technological studies of ecological industries and ecological products helps eco-fragile areas recover their degraded ecosystem. The results of a statistical analysis of 159 related documents show: (1) the number of documents published rises wave upon wave in time series, which indicates that this area of study is still at the stage of rising; (2) research contents concentrate on five dimensions-theoretical research, technology research and development, model building, demonstration and promotion, and efficiency analysis, among which theoretical research chiefly discusses environmental costs and effects of ecological industries, regional organizational layout, industrial chain construction, market supply and demand of biological products, discrimination of the nature of biological products, and value assessment and realization of biological products; (3) study areas are largely distributed in the Loess Plateau area in the north and karst areas in the south in China, which suggests that studies of biological industries and biological products in eco-fragile areas concentrate on arid and semi-arid areas and engineered arid areas. Furthermore, from five aspects-theoretical study, technology research and development, model building, experiment and demonstration, and monitoring and evaluation, this study reveals cutting-edge theories about ecological industries and ecological products in eco-fragile areas. At last, it is found that comprehensive theoretical research of the market circulation of ecological products in eco-fragile areas and the research and development of key technologies to enhance the value of ecological products lag behind, and it is necessary to deepen the studies about the whole industry chain development for ecological industries, the valuation of ecological effect, the standardization of ecological industry management, the circulation mechanism of ecological products, brand building and other aspects.

Effect of Internal Microstructure Distribution on Quasi-Static Compression Behavior and Energy Absorption of Hollow Truss Structures.

In this work, hollow truss structures with different internal microstructure distributions, i.e., basic hollow truss structure (specimen HT), hollow truss structure with internal microstructure at joints (specimen HTSJ), and hollow truss structure with internal microstructure on tube walls (specimen HTSW), were designed and manufactured using a selective laser melting technique. The effect of internal microstructure distribution on quasi-static compressive behavior and energy absorption was investigated by experimental tests and numerical simulations. The experimental results show that compressive strength and specific compressive strength of specimen HTSW increase by nearly 50% and 14% compared to specimen HT, and its energy absorption per volume and mass also increase by 52% and 15% at a strain of 0.5, respectively. However, the parameters of specimen HTSJ exhibit limited improvement or even a decrease in different degrees in comparison to specimen HT. The numerical simulation indicates that internal microstructures change the bearing capacity and structural weaknesses of the cells, resulting in the different mechanical properties and energy absorptions of the specimens. Based on the internal microstructure design in this study, adding microstructures into the internal weaknesses of the cells parallel to the loading direction is an effective way to improve the compressive properties, energy absorption and compressive stability of hollow truss structures.