Survey of Urban Geographical Environment Research Based on Urban Planning and Land-use

Every city was constructed on a region with special geomorphology. The construction and development of the city was based on it. The relationship between urban geographical environment and urban planning was intimate. This paper gave a brief introduction of the history and development of the urban geological research, urban geographical research, urban geomorphic disasters research and urban geographical environmental quality comprehensive assessment research based on the condition of urban planning and land-use. At last, the problem and the trend of urban geographical environment research were discussed

Intra-annual growing season climate variability drives the community intra-annual stability of a temperate grassland by altering intra-annual species asynchrony and richness in Inner Mongolia, China

Understanding the factors that regulate the functioning of our ecosystems in response to environmental changes can help to maintain the stable provisioning of ecosystem services to mankind. This is especially relevant given the increased variability of environmental conditions due to human activities. In particular, maintaining a stable production and plant biomass during the growing season (intra-annual stability) despite pervasive and directional changes in temperature and precipitation through time can help to secure food supply to wild animals, livestock, and humans. Here, we conducted a 29-year field observational study in a temperate grassland to explore how the intra-annual stability of primary productivity is influenced by biotic and abiotic variables through time. We found that intra-annual precipitation variability in the growing season indirectly influenced the community intra-annual biomass stability by its negative effect on intra-annual species asynchrony. While the intra-annual temperature variability in the growing season indirectly altered community intra-annual biomass stability through affecting the intra-annual species richness. At the same time, although the intra-annual biomass stability of the dominant species and the dominant functional group were insensitive to climate variability, they also promoted the stable community biomass to a certain extent. Our results indicate that ongoing intra-annual climate variability affects community intra-annual biomass stability in the temperate grassland, which has important theoretical significance for us to take active measures to deal with climate change

Species richness and asynchrony maintain the stability of primary productivity against seasonal climatic variability

The stability of grassland communities informs us about the ability of grasslands to provide reliable services despite environmental fluctuations. There is large evidence that higher plant diversity and asynchrony among species stabilizes grassland primary productivity against interannual climate variability. Whether biodiversity and asynchrony among species and functional groups stabilize grassland productivity against seasonal climate variability remains unknown. Here, using 29-year monitoring of a temperate grassland, we found lower community temporal stability with higher seasonal climate variability (temperature and precipitation). This was due to a combination of processes including related species richness, species asynchrony, functional group asynchrony and dominant species stability. Among those processes, functional group asynchrony had the strongest contribution to community compensatory dynamics and community stability. Based on a long-term study spanning 29 years, our results indicate that biodiversity and compensatory dynamics a key for the stable provision of grassland function against increasing seasonal climate variability

A geometric dilution of precision based 3D indoor positioning scheme

A geometric dilution of precision(GDOP) based 3D indoor positioning scheme was proposed for the layout of anchor nodes.Through the proposed scheme,the biconical configuration could be obtained.The performance of the scheme was evaluated by utilizing two different ranging error models.Simulation results indicated that the scheme can be applied to various scenes with different sizes.Furthermore,the proposed scheme had considerable accuracy improvement in the same positioning environment compared with existing layout scheme

Study on position computing in range-based localization system

In the existing range-based position computing algorithm,the localization accuracy is greatly influenced by the error of measured distance.In order to improve the localization accuracy,this paper presents an optimized indoor localization algorithm based on radical center.In the algorithm,firstly,calculating the radical center bases on the measured distance between every three anchor nodes and the target node.Then,percentage of the radical centers in the set which have large localization error are filtered out.Finally,computing the average of the remaining radical centers′ coordinates as the result bases on their weight.The result of simulation showed that compared with the existing range-based position computing algorithm,the presented position computing algorithm reduces the localization error and improves the localization accuracy effectively