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As urbanization and industrialization have advanced in leaps and bounds, the territorial spatial pattern of Qinghai has experienced profound transformation and reconstruction, which has been directly reflected in land-use changes ...
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As urbanization and industrialization have advanced in leaps and bounds, the territorial spatial pattern of Qinghai has experienced profound transformation and reconstruction, which has been directly reflected in land-use changes and affected the eco-environment. In this context, we constructed a functional classification system of “production-living-ecological” (PLE), used remote sensing data for six periods from 1980 to 2020, and employed the land transfer matrix, eco-environmental quality index, ecological contribution rate of land-use transformation and geographical detectors to analyze the changes in the territorial spatial patterns, eco-environmental effects and driving forces of eco-environmental quality. The results revealed that (1) the spatial distribution of the province was characterized by the relative agglomeration of the production and living spaces and the absolute dominance of ecological spaces; (2) The eco-environmental quality of the region portrayed a steady improvement, with a significant reduction in the medium–low and low-quality areas; and (3) the annual average precipitation, proportion of non-agricultural area, and socio-economic factors had a significant impact on the eco-environmental quality of the region, meanwhile, national economy and ecological policies are important indirect driving forces of eco-environmental quality. Our findings will provide guidelines for territorial spatial management and serve as a reference for eco-environmental protection in Qinghai.
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Previous studies pay little attention to the role of technological progress in measuring urban land use efficiency, and ignore the interactions among total factor productivity, technological progress, pure technical efficiency and...
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Previous studies pay little attention to the role of technological progress in measuring urban land use efficiency, and ignore the interactions among total factor productivity, technological progress, pure technical efficiency and scale efficiency in the process of urban land use. To narrow the gaps, this research uses the Malmquist index approach to measure and decompose urban land use total factor productivity and a panel vector autoregressive model (PVAR) to investigate the interactions among urban land use total factor productivity, technological progress, pure technical efficiency, and scale efficiency in China from 2003 to 2016. This study shows that the overall urban land use efficiency increased at an annual growth rate of 0.7% in China from 2003 to 2016 while the growth rate of urban land use efficiency has generally decreased, which is reflected by the total factor productivity of urban land use. The total factor productivity fluctuates between 0.952 and 1.083 with a downward trend in 2003-2016. Technological progress, pure technical efficiency and scale efficiency all have positive effects on the improvement of urban land use efficiency, and there are differences in the order and degree of promotion. The improvement of scale efficiency is the most important measure to ensure the efficient use of urban land resources in the future.
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Automatic built-up areas detection from remote sensing images has attracted considerable research interest, due to its crucial roles in various applications. As far as built-up areas detection, the corner density map to predict th...
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Automatic built-up areas detection from remote sensing images has attracted considerable research interest, due to its crucial roles in various applications. As far as built-up areas detection, the corner density map to predict the presence of the built-up areas has been widely adopted, but the calculation is generally time-consuming. In addition, the density map is just segmented by a statistical threshold, resulting in that the accurate boundaries of the built-up areas are unachievable. In order to address these issues, this paper proposes a novel built-up areas detection approach. Instead of pixel units, our approach takes the superpixel-based image partitions as the primary calculation units, which benefits to improve the computational efficiency and visual organization performance. Based on the superpixel-based units, this paper first proposes a sparse corner voting method for accelerating the production of corner density map. Then, Cauchy graph embedding optimization is presented to cope with the problem of segmenting the density map, which can preserve the well-defined boundaries of built-up areas. A diverse and representative test set including 2.1-m resolution ZY3 imagery, 2.0-m resolution GF1 imagery, 1.0-m resolution IKONOS imagery, and 0.61-m resolution QUICKBIRD imagery is collected. Experimental results on these test images show that our proposed approach is robust to sensor and resolution variation, and can outperform state-of-the-art approaches remarkably.
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Ecological compensation affects farmers’ livelihoods, as well as sustainability and social equity. Yulin City is the core area of the energy “Golden Triangle” in China. The farmers livelihood strategy model was used to analyse ...
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Ecological compensation affects farmers’ livelihoods, as well as sustainability and social equity. Yulin City is the core area of the energy “Golden Triangle” in China. The farmers livelihood strategy model was used to analyse data from a household survey and interviews with selected farmers. The paper analyses the current livelihood strategies of farmers and impact of ecological compensation from the perspective of participation and income. The results showed that (1) the significant difference between the coal resource development and oil and gas resource development was agricultural planting. Migrant work and non-agricultural self-employment in the coal resource development region were higher than that of the oil and gas resource development region. (2) The income from agricultural planting in the coal resource development region was significantly lower than that of the oil and gas resource development region. The labour, non-agricultural self-employment, and transfer incomes were higher in the coal resource development region than that in the oil and gas resource development region. (3) Ecological compensation has a significant negative effect on participation and income from agricultural planting, as well as a positive effect on participation and income from non-agricultural self-employment. We have proposed measures to strengthen ecological compensation mechanisms and improve the farmers’ livelihoods, in order to inform decision-making and high-quality sustainable development in energy development region.
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The friction coefficient is one of the key parameters in the tribological performance of mechanical systems. In the condition of light normal load and low rotation speed, the friction coefficients of ball-on-disc with rough surfac...
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The friction coefficient is one of the key parameters in the tribological performance of mechanical systems. In the condition of light normal load and low rotation speed, the friction coefficients of ball-on-disc with rough surface in dry sliding contact are experimentally investigated. Friction tests are carried out under normal load 2–9 N, rotation speed 20–48 rpm at room temperature, and surface roughness 0.245–1.010 μm produced by grinding, milling, and turning. Results show that the friction coefficient increases first and then becomes stable, in which the running-in and steady-state periods are included. With the growth of normal load and rotation speed, or the decline of surface roughness, the duration and fluctuation of the running-in period verge to reduce. The whole rising slope of the friction coefficient in the running-in period goes up more quickly with the increment of rotation speed, and it ascends more slowly as normal load enlarges. In terms of the steady-state period, the deviation of the friction coefficient shows a dwindling trend when normal load or rotation speed grows, or surface roughness descends. As normal load or rotation speed rises, the value of the friction coefficient rises first and then drops. Additionally, the mean value of the friction coefficient in steady-state is approximately independent of surface roughness.
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Objective . To investigate the main pharmacological basis and mechanism of action of Gujiansan in the treatment of steroid-induced avascular necrosis of the femoral head (SANFH). Methods . The active constituents and targets of Gu...
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Objective . To investigate the main pharmacological basis and mechanism of action of Gujiansan in the treatment of steroid-induced avascular necrosis of the femoral head (SANFH). Methods . The active constituents and targets of Gujiansan were screened by using TCMSP and other databases, and relevant disease targets were obtained by analyzing the microarray of SANFH in the GEO database. The intersection of the two was taken to obtain the potential targets of Gujiansan for the treatment of SANFH, and key active constituents were screened with the “active constituent-target” network constructed by the Cytoscape software; then, the STRING database was used to construct the protein interaction network to screen the key targets. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses of key targets were performed by the DAVID database, and the relationship between the “key active constituent-key target-key signaling pathway” was explored. Finally, the molecular docking between key active constituents and key targets was verified. In addition, qPCR detection technology was used to evaluate the preventive and therapeutic effects of key active constituents of Gujiansan in a rat osteoblast model of SANFH to verify the possible mechanism of the effect of Gujiansan in the treatment of SANFH. Results . (1) 106 active constituents and 55 targets were obtained for the treatment of SANFH. (2) Quercetin, luteolin, kaempferol, cryptotanshinone, and naringenin were the key active constituents for the treatment of SANFH. (3) IL1B, STAT3, CAT, PTGS2, and MAPK3 were the key targets for the treatment of SANFH. (4) IL1B, STAT3, CAT, PTGS2, MAPK3, and HMOX1 are key targets in the protein interaction network. (5) DAVID enrichment analysis mainly covers the regulation of DNA-binding transcription factor activity, positive regulation of cytokine production, and response to oxidative stress and other biological processes, involving IL-17, AGE-RAGE, C-type lectin receptor, and other signaling pathways. (6) Gujiansan is a multitarget and multisignaling pathway for the treatment of SANFH. (7) Good binding activity exists between key active constituents and key targets. Conclusion . This study analyzes the potential mechanism of action of Gujiansan in the treatment of SANFH with network pharmacology, which can provide a reference for the further study of its pharmacological basis and targets.
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Misalignment errors (MEs) in multiple degrees of freedom (multi-DOFs) at the mesh position will lead to a change in the time-varying mesh stiffness (TVMS) and then affect the dynamic behaviour of gear pairs. Therefore, a new, more...
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Misalignment errors (MEs) in multiple degrees of freedom (multi-DOFs) at the mesh position will lead to a change in the time-varying mesh stiffness (TVMS) and then affect the dynamic behaviour of gear pairs. Therefore, a new, more rapid, three-dimensional analytical model for TVMS calculation for gear pairs with three rotational and three translational MEs is established in this paper, and a new solution method based on potential energy theory is presented. In addition, the correctness of the new model is verified by the finite element method (FEM). Moreover, the effective contact line, uneven distribution of mesh force on the contact line, and mesh position change are taken into account. Finally, the TVMS under different ME conditions is calculated with the new analytical model. The results showed that the different MEs have dissimilar effects on the TVMS, and the relationship between the ME and TVMS is nonlinear. In addition, the region of single-pair and double-pair teeth in contact would also change with ME.
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In order to improve the stable walking ability of quadruped robot in uneven terrain, the discontinuous gait of quadruped robot is designed based on the stability margin calculated by the pressure center method. Gait planning inclu...
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In order to improve the stable walking ability of quadruped robot in uneven terrain, the discontinuous gait of quadruped robot is designed based on the stability margin calculated by the pressure center method. Gait planning includes body centre of gravity trajectory planning and swing foot end trajectory planning. Sine acceleration curve is used to plan the body centre of gravity trajectory to ensure the continuity of the whole movement process. Aiming at the robot with the ability of environment perception, a kind of rectangular swinging foot end trajectory is designed, which has both flexible adaptability and moving speed. The simulation results show that the quadruped robot can pass through the uneven terrain area in real time and stably using the proposed static gait planning method.
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The composites beta(2)-SiW11/GO and beta(2)-SiW11/PANI/GO were prepared by using graphene oxide as a carrier. Properties of the composites were characterized by UV-visible spectroscopy (UV-vis), infrared spectroscopy (FT-IR), X-ra...
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The composites beta(2)-SiW11/GO and beta(2)-SiW11/PANI/GO were prepared by using graphene oxide as a carrier. Properties of the composites were characterized by UV-visible spectroscopy (UV-vis), infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM-EDS), transmission electron microscopy (TEM), N-2 adsorption desorption and thermal gravimetric analysis. Properties of the composites were investigated by using methyl violet simulated industrial wastewater. The results showed that this composite had photocatalytic activities for many dyes, and the activity was higher than that of Degussa P25(TiO2). The photocatalytic performance of beta(2)-SiW11/PANI/GO had a higher activity than that of PANI, beta(2)-SiW11 and beta(2)-SiW11/GO, with photodegradation reaching 95.98% under 30 W ultraviolet light for 150 min. The reaction kinetics for photocatalytic degradation of methyl violet followed a first-order process. The prepared composite was recyclable and the performance remained good. The possible mechanism of photocatalytic activity of dopant material is discussed and schematized.
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Development of the Brahmaputra River, which links China, India and Bangladesh, has been hindered by significant challenges, particularly political challenges. News reports can mirror the perceptions of political actors, but are, o...
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Development of the Brahmaputra River, which links China, India and Bangladesh, has been hindered by significant challenges, particularly political challenges. News reports can mirror the perceptions of political actors, but are, owing to the complexity of the issue, complicated and unstructured. We present a comparative content analysis of the overall framing in news reports of the Brahmaputra River development from major English news media. A structural topic model is established to discover latent topics in the corpus of 1,569 news articles published in 34 countries or regions. We find that politics, including domestic and international politics, dominates the news narratives. Environmental issues, such as glacier status and climate change impacts, are secondarily discussed. Technology and economy issues are less frequently presented in the media coverage. Advantages of upstream countries and dependences of downstream countries are reflected in news reporting and explicitly emerge in the structural topic model. These findings and implications are important for promoting mutual understanding and cooperation among riparian countries in developing the Brahmaputra River. The proposed approach is expected to be widely used as a methodological strategy in future water policy studies.
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