Applied Mechanics and Materials Vol. 737

Abstract: Through the Merlot wavelet periodic analysis and Mann-Kendall mutation analysis about the maximum wind speed of 14 weather station in Hexi corridor over the past 41 years,the evolution characteristic of the maximum wind speed can be gotten:the Hexi corridor has about 28-29 years main period and 8-12 years secondary period,presenting sinusoidal curve,and the transformation energy cycled from small to big to small to big;After 1980,there were abrupt changes and decline in Anxi,Jiuquan,Zhangye and Wuwei.The Hexi corridor is in the wind speed environment of same climate conditions,and the inter-annual change feature becomes balanced; but in internal local areas,due to the influence of environment, terrain and urban heat island effect,the secondary period is different,presenting abrupt changes and decreasing tendency in 1980s.

Abstract: With the wind farm data from the southeast coast this paper builds a two-stage combination forecasting model of output power based on data preprocessing which include filling up missing data and pre-decomposition. The first stage is a composite prediction of decomposed power sequence in which a time series and optimized BP neural network predict the general trend and the correlation of various factors respectively. The second stage is BP neural network with its input is the results of first stage. The effectiveness and accuracy of the two-stage combination model are verified by comparing the mean square error of the combination model and other models.

Abstract: The fast pyrolysis of corn straw in the fluidized bed reactor to produce bio-oil, the preliminary qualitative research on the composition of the bio-oil was analyzed by GC-MS to provide the basis for their purification, refining and long-term stability studies. The result shows that: the bio-oil producted by corn straw pyrolysis contains 66 components, mainly containing phenol, furan, acetic acid, propanoic acid, ethanone, vanillin, aldehyde, bio-oil water content is 33% and pH is 3.1, which has a great significance to improve the quality of bio-oil.

Abstract: In order to break through the bottleneck of solar photovoltaic power generation, and off-season vegetables problems in Hainan island, we arrange photovoltaic panels above farm land to generate electricity. By novel and ingenious arrangement on panels, we can make farmland temperature distribution more uniform, decrease temperature differences between shading and lighting area significantly, also reduce wind resistance significantly. The influence of solar panel shading on Chinese cabbage was detected by photosynthetic measurement instrument LI-6400. The system was suitable for general farmers to implement in hot climate areas. By using this system, famers can produce cops and electricity at the same time, sell extra electricity, and get double income.

Abstract: Based on mathematical models and output characteristics of photovoltaic cells, the simulation model for engineering application is established. By the model, the output characteristics of photovoltaic cells with different environmental factors can be analyzed. In MATLAB/SIMULINK environment, the model of the PV maximum power point tracking control is constructed. The simulation results demonstrate that PV can run at the maximum power point with the change of environment factors.

Abstract: At present, the efficiency of livestock manure and crop residues is low in our country compared with international level. A massive array of automatic methane pond system is presented with controlled temperature and pressure. A single chip Micyoco( SCM) is the control unit. The motor is connected to the SCM; the transmission mechanism connected with the motor, the transmission chain is surrounded by a ring-shaped motor drive; loading of raw materials like iron grid mesh cage, rotates with the transmission chain.

Abstract: A process was designed for etherification of glycerol with isobutene based on latest results of kinetic and thermodynamic study. A continuous stirred tank reactor was employed to carry out the reaction. Fresh glycerol was used to extract mono-ethers (ME) of glycerol in the reaction product and then returned to the reactor. Residual glycerol and ME were recovered by water washing and distillation. Isobutene and isobutene dimers were separated from high-ethers in a side draw distillation column. The new process was optimized, and a product yield of 97 wt% was obtained.

Abstract: With dry woody particles as fuel and air-steam as gasification agent, the higher heating value biomass gas gasifier used software to simulate the height position h of the steam from the entrance in the gasifier, the steam inlet flow rate V_s and the air inlet flow rate V₀. These three parameters impact on the volume concentration of CO, H₂ and CH₄ and its gas calorific value were analyzed. The orthogonal test were used for design parameters h, V_s and V₀, the optimization values of these three parameters were carried out, and test its volume concentration and gas calorific values. Numerical simulation and experimental results showed that when the height position h=180mm, air inlet flow rate V₀=0.94m³/h, and steam inlet flow rate V_s=1.30m³/h, the combustion of biomass gas calorific value arrives its top, the value is Q=10.98MJ/m³, which is 114.87% higher than when single gas agent is used.

Abstract: In this work, the angular dependence of optical losses through gaps, constructed by truncating reflectors near the absorbers, of CPCs with one-sided flat absorber was presented, and the annul radiation loss through gaps of east-west aligned CPCs is theoretically investigated. Results show that the optical losses are mainly resulted from direct radiation loss through gaps due to direct irradiation on gaps, and the loss of radiation that arrive on gaps from reflectors after multiple reflections is considerable small and can be neglected in solar calculations especially for truncated CPCs. Results also show that the annual direct radiation loss is dependent on geometric parameters of CPCs but seems independent on solar resource in sites where CPCs are used, and the annual radiation loss of full CPCs oriented in east-west direction with the tilt-angle of aperture being yearly fixed is almost identical to average optical loss of the CPC over its acceptance angle.