Characteristics of ultracapacitor and classic model have been introduced in this paper. Due to its superior performance, ultracapacitor is used for hybrid energy storage system with lead-acid battery. The performance and potential application of hybrid energy storage system have been elaborated, which make some contribution to the promotion and application of energy storage technology.
The main objective of this work is to characterise the prop-rotor of V/STOL (Vertical/short-take-off and landing) aircraft in various operating conditions, especially in transition flight. To this end, a BET (Blade element theory) based analytic model/tool with a low computational cost has been built to predict the aerodynamic performance of the prop-rotor. This BET-based model can predict prop-rotor thrust, torque, normal force, and yaw moment as well as their corresponding 1P load (once-per-revolution load on the single blade) regarding oblique flow. This model is verified and shows good consistency with the wind tunnel experimental data and CFD simulation results. Furthermore, by using this BET model/tool, the effects of axial advance ratio, tilt angle and collective pitch angle on these component loads on the prop-rotor are explored. Moreover, the effects of these variables on the vibratory amplitudes of the 1P load on the single blade and 3P harmonic loads on the prop-rotor due to inclined flow are presented as well.
In order to study the creep properties of coal or rock containing gas, the creep properties of coal or rock without gas were studied firstly. Through analyzing the previous creep experiment results of coal or rock, one nonlinear damage creep model of coal or rock was founded based on the general Kelvin model. In this model, assumed that the damage is a function of stress level and time, and introduced one nonlinear hardened function into the general Kelvin model, the nonlinear damage fading creep equation and the nonlinear damage creep whole process equation were obtained. Besides this model, considering the composite structure of coal or rock, gas and gas absorption layer, and assuming that this structure has the stick-slip property under the outside load, so a stick-slip module was added in the general Kelvin model and a new nonlinear damage creep model of coal or rock containing gas was founded. Given the value of the material parameters in the two equations, the creep curves varied with the time were drawn under different axial compression. Through the theoretical curves, the nonlinear damage creep model in this paper was proved to be rational.
With the development of networks, the relationships between networks have also been increasingly intimate. It is envisioned that these interdependent networks are more vulnerable. In order to study the robustness of interdependent networks, in this paper, we characterize a load redistribution model based on distance and cascading failure model about interdependent communication network and power network. The failure model joined the load factor on the basis of the penetration model. We analyze the influence of different distribution distance threshold to interdependent networks. The simulation shows that global redistribution yields better performance and enough capacity cannot prevent cascading failure completely.
This paper presents a general view of the target tracking in Wireless Sensor Networks (WSN) with proper deployment of it. Target tracking task in WSN can be more accurately and efficiently accomplished, given the circumstance where the WSN is more proper deployed, for example, the coverage with clearer border and less holes, sensors with less movement, and connectivity well preserved. To prove this thought, several protocols of target tracking and various aspects of deployment in WSN are investigated.
In order to promote the development of wind power and accelerate the efficient use of new energy sources, countries have brought energy storage systems into grid-connected wind farms to achieve efficient and stable operation of the wind power plant. This paper recounts the latest development status and trend of wind power at home and abroad, and introduces the principle of power conversion between energy storage system and wind farm. Based on the existing research results, it analyses power system stability related to wind power, low voltage ride-through ability of wind turbine, wind power penetration limit, as well as power quality issues. It also describes the new ideas about how to use energy storage technologies to solve the problems faced by the wind power.
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