Capacity Analysis for Dynamic Space Networks

To evaluate transmission rate of highly dynamic space networks,a new method for studying space network capacity is proposed in this paper. Using graph theory,network capacity is defined as the maximum amount of flows ground stations can receive per unit time. Combined with a hybrid constellation model,network capacity is calculated and further analyzed for practical cases. Simulation results show that network capacity will increase to different extents as link capacity,minimum ground elevation constraint and satellite onboard processing capability change. Considering the efficiency and reliability of communication networks,how to scientifically design satellite networks is also discussed.

Suitability evaluation and spatial capacity analysis for complex topography construction land area in southwest China:a case study of Tongzi county in Guizhou province

In the background of a new round reform and western development strategy, making suitability evaluation of construction land complex topography area in southwest China scientifically and accurately has an important guiding significance on the construction of local urban and rural development. We selected economic factor of construction, safety factor of construction, factor of the present situation of land use and ecological protection factor in Tongzi county as evaluation indexes, and ascertained the weight of each elastic indicator using the analytic hierarchy process method. By the support of GIS and RS technology, we combined the single-factor qualitative classification with the multi-factor weighted overlay analysis to make comprehensive suitability evaluation of construction land on the whole study area. And five different types of construction land were divided, namely, ‘excellent', ‘very good', ‘good', ‘moderate' and ‘poor'. The result shows that the area of ‘excellent' construction land is 30.47 km^2(0.95%), 101.46 km^2(3.16%) of ‘very good', 550.34 km^2(17.16%) of ‘good', and 664.69 km^2(20.72%) and 1 860.65 km^2(58.01%) of ‘moderate' and ‘poor', respectively. The land space bearing capacity is a population of 791 600, and the remaining population capacity is 170 900 persons.

Investigation of the Behavior of a Photovoltaic Cell under Concentration as a Function of the Temperature of the Base and a Variable External Magnetic Field in 3D Approximation

The photovoltaic (PV) cell performances are connected to the base photogenerated carriers charge. Some studies showed that the quantity of the photogenerated carriers charge increases with the increase of the solar illumination. This situation explains the choice of concentration PV cell (C = 50 suns) in this study. However, the strong photogeneration of the carriers charge causes a high heat production by thermalization, collision and carriers charge braking due to the electric field induced by concentration gradient. This heat brings the heating of the PV cell base. That imposes the taking into account of the temperature influence in the concentrator PV cell operation. Moreover, with the proliferation of the magnetic field sources in the life space, it is important to consider its effect on the PV cell performances. Thus, when magnetic field and base temperature increase simultaneously, we observe a deterioration of the photovoltage, the electric power, the space charge region capacity, the fill factor and the conversion efficiency. However the photocurrent increases when the base temperature increases and the magnetic field strength decreases. It appears an inversion phenomenon in the evolution of the electrical parameters as a function of magnetic field for the values of magnetic field B> 4×10-4 T.