Two-Stage Resource Allocation Scheme for Three-Tier Ultra-Dense Network

In 5 G Ultra-dense Network(UDN), resource allocation is an efficient method to manage inter-small-cell interference. In this paper, a two-stage resource allocation scheme is proposed to supervise interference and resource allocation while establishing a realistic scenario of three-tier heterogeneous network architecture. The scheme consists of two stages: in stage I, a two-level sub-channel allocation algorithm and a power control method based on the logarithmic function are applied to allocate resource for Macrocell and Picocells, guaranteeing the minimum system capacity by considering the power limitation and interference coordination; in stage II, an interference management approach based on K-means clustering is introduced to divide Femtocells into different clusters. Then, a prior sub-channel allocation algorithm is employed for Femtocells in diverse clusters to mitigate the interference and promote system performance. Simulation results show that the proposed scheme contributes to the enhancement of system throughput and spectrum efficiency while ensuring the system energy efficiency.

Classification of plant functional types based on the nutrition traits： a case study on alpine meadow community in the Zoigê Plateau

The ecological concept of Plant Functional Types（PFTs）, which refers to the assemblage of plants with certain functional traits, has been introduced for the study of plant responses to the environment change and human disturbance. Taking the alpine meadow community in the Zoigê Plateau as a study case, this paper classified PFTs in terms of plant nutrition traits. The sequential results are as follows.（1） The main herbages in the Zoigê Plateau included 16 species in 5 families. Among the five families, Cyperaceae vegetation accounted for 81.37%of herbage area in total, while the remaining 4families occupied less than 20%. As for the species,Kobresia setchwanensis Hand.-Maizz. was dominant,accounting for 48.74% of the total area; while the remaining 51.26% was comprised of Polygonum viviparum L., Anaphalis fiavescens Hand.-Mazz.,Stipa aliena Keng and other species.（2） By using the Principal Component Analysis（PCA）, the assessment of herbages nutrition was carried out based on the comprehensive multi-index evaluation model.Polygonum viviparum L. had the highest nutritional value score（1.43）, and Stipa aliena Keng had the lowest（-1.40）. Nutritional value of herbage species had a significantly positive correlation with altitude（P＆lt;0.01） in the Zoigê Plateau.（3） Based on the nutritional values, herbages in the Zoigê Plateau could be grouped into 3 nutrition PFTs（high, medium and low） by using the Natural Breaks（Jenks） method.

Resource selection of moose(Alces alces cameloides) and their response to human disturbances in the northwestern slope of Lesser Khingan Mountains, northeastern China

Moose （Alces alces cameloides） is typically representative of the fauna of the frigid temperate zone and has been put on the Chinese second priority list of protected animals. The moose of northeast China is on the southern most edge of its distribution in Asia. To study resource selection characteristics of moose and their response to human distur- bances and forest resource variables, the field work was conducted in Heilongiiang Provincial Shengshan Forestry Farm, which is located in the northwestern slope of Lesser Khingan Mountains, northeastern China, from January to March in both 2006 and 2007. A total of 428 plots were examined within the study area. Signs of moose use were found in 19 plots. Based on the analysis of resource selection function, we found that moose selected areas with higher densities of mixed deciduous broadleaf patch and mixed coniferous and broad leaf patch, and a higher NDVI value. Moose avoided settlement 6 km away and remained low probability of occurrence within 3 km from roads,

Evaluation on the Essentiality Grades of Water Conserving in Tibet, China

Taking Tibet as an example, the functional essentiality degrees of water resources conserving of regions were discussed in this paper. At first, based on the status of regional vegetation, whether the region has the function of water conserving was made certain. And then, according to the impacted objects of water resources conserving, taking into account the demands for water and regional supply capacities of water and the requirement of environmental protection, the functional grades of regional water resources conserving of Tibet were evaluated in this paper.

Consistent habitat preference underpins the geographically divergent autumn migration of individual Mongolian common shelducks

While many avian populations follow narrow,well-defined"migratory corridors,"individuals from other populations undertake highly divergent individual migration routes,using widely dispersed stopover sites en route between breeding and wintering areas,although the reasons for these differences are rarely investigated.We combined individual GPS-tracked migration data from Mongolian-breeding common shelduck Tadorna tadorna and remote sensing datasets,to in-vestigate habitat selection at inland stopover sites used by these birds during dispersed autumn migration,to explain their divergent migration patterns.We used generalized linear mixed models to investigate population-level resource selection,and generalized linear models to investigate stopover-sit-level resource selection.The population-level model showed that water recurrence had the strongest positive effect on determining birds'occupancy at staging sites,while cultivated land and grassland land cover type had strongest negative effects;effects of other land cover types were negative but weaker,particularly effects of wwater seasonality and presence of a human foot-print,which were positive but weak or non-significant,respectively.Although stopover-site-level models showed variable resource selection patterns,the variance partitioning and cross-prediction AUC scores corroborated high inter-individual consistency in habitat selection at inland stopover sites during the dispersed autumn migration.These results suggest that the geographically wide-spread distribution(and generally rarity)of suitable habitats explained the spatially divergent autumn migrations of Mongolian breeding common shelduck,rather than the species showing flexible autumn staging habitat occupancy.