STUDY ON NONLINEAR DYNAMIC CHARACTERISTICS OF DRIVING SYSTEM OF SHEARER CUTTING MACHINE WITH CLEARANCE

In order to study the nonlinear dynamic characteristics of the cutting system of the shearer with gap,a dynamic model of the gear system of the shearer cutting machine is established,and the function of meshing stiffness and damping in the model is established. The influence of the tooth clearance on the meshing force of the gears of the shearer’s drive system is studied by using the runge-Kuatt method. The results show that the gears are increased by the gears The change of the meshing force and the amplitude of the frequency multiplication of the meshing frequency. Increasing the amplitude of the tooth side increases the fluctuation range of the engaging force,causing a large impact force in the transmission process,accelerating the wear of the tooth surface,The gears are broken in gear due to overload. Improve the stability and service life of the gear train of the shearer cutting section,and reduce the torsional vibration degree and reduce the tooth clearance. This study provides a theoretical basis for the optimal design and research of gear transmission system

Simulation and Regulation of Market Operation in Hydro-Dominated Environment: The Yunnan Case

This paper presents an integrated method to obtain optimal market operation and regulation with the objective of reducing the market price and increasing the electricity consumption in hydro-dominated electricity markets, in which giant cascaded hydropower facilities along different rivers are main power suppliers. To this end, a comprehensive indicator composed of market prices and electricity consumption is proposed to evaluate the situation of hydro-dominated market operation. Moreover, an iterative algorithm is proposed to investigate the strategic behaviors of power suppliers and to simulate the operation of the market. Furthermore, an integrated solution methodology based on a multi-core parallel tabu genetic algorithm (MPTGA) is proposed to provide the optimal assignment of bilateral contracts, considering the market simulation, in order to achieve the optimal market regulation. The results from the case study, with real data based on Yunnan’s electricity market, demonstrate that the proposed indicator and method are effective and efficient to simulate and regulate the market operation, and the effects of MPTGA are discussed last

Market Equilibrium and Impact of Market Mechanism Parameters on the Electricity Price in Yunnan’s Electricity Market

In this paper, a two-dimensional Cournot model is proposed to study generation companies’ (GENCO’s) strategic quantity-setting behaviors in the newly established Yunnan’s electricity market. A hybrid pricing mechanism is introduced to Yunnan’s electricity market with the aim to stimulate electricity demand. Market equilibrium is obtained by iteratively solving each GENCO’s profit maximization problem and finding their optimal bidding outputs. As the market mechanism is a key element of the electricity market, impacts of different market mechanism parameters on electricity price and power generation in market equilibrium state should be fully assessed. Therefore, based on the proposed model, we precisely explore the impacts on market equilibrium of varying parameters such as the number of GENCOs, the quantity of ex-ante obligatory-use electricity contracts (EOECs) and the elasticity of demand. Numerical analysis results of Yunnan’s electricity market show that these parameters have notable but different effects on electricity price. A larger number of GENCOs or less EOEC contracted with GENCOs will have positive effects on reducing the price. With the increase of demand elasticity, the price falls first and then rises. Comparison of different mechanisms and relationship between different parameters are also analyzed. These results should be of practical interest to market participants or market designers in Yunnan’s or other similar markets

Characterization of human enterovirus71 virus-like particles used for vaccine antigens.

Human enterovirus 71 (EV71) is a major causative pathogen of hand, foot and mouth disease (HFMD) and has caused outbreaks with significant mortality among young children in the Asia-Pacific region in recent years. Towards developing a vaccine for this disease, we have expressed and purified EV71 virus-like particles (VLPs), which resemble the authentic virus in appearance, capsid structure and protein sequence, from insect cells (Sf9) using a multistep chromatography process. We demonstrated intracellular localization of the VLPs in host cells by in situ immunogold detection, electron microscopy and immunofluorescence. Characteristics of these EV71 VLPs were studied using a variety of immunological and physicochemical techniques, which aimed to reveal that the purified EV71 VLPs have good morphology and structure consistent with natural EV71 empty capsids. Results of the amino acid analysis, SDS-PAGE, Western blotting and high-performance liquid chromatography confirmed the high purity of the EV71 VLPs. However the sedimentation coefficient of the VLPs showed that they were smaller than that of secreted EV71 VLPs purified by discontinuous cesium chloride density gradients, they were similar to the empty capsids of natural EV71 virions reported previously. Combined with the previous study that EV71 VLPs purified by a multistep chromatography process were able to elicit strong humoral immune responses in mice, our results further supported the conclusion that our EV71 VLPs had well-preserved molecular and structural characteristics. The EV71 VLPs produced from the baculovirus expression system and purified by a multistep chromatography process displayed key structural and immunological features, which would contribute to their efficacy as a HFMD vaccine