Advanced Materials Research Vols. 512-515

Abstract: This paper presents a new strategy in wind speed prediction based on AR model and wavelet transform.The model uses the adjacent data for short-term wind speed forecasting and the data of the same moment in earlier days for long-term wind speed prediction at that moment,taking the similarity of wind speed at the same moment every day into account.Using the new model to analyze the wind speed of An-xi,China in April,2010,this paper concludes that the model is effective for that the correlation coefficient between the predicted value and the original data is larger than 0.8 when the prediction is less than 48 hours;while the prediction time is long ahead (48-120h),the error is acceptable (within 40%),which demonstrates that the new method is a novel and good idea for prediction on wind speed.

Abstract: From the basic equation of dynamics, the precise expression of the relationship ,which is between the horizontal natural frequency and pressure load of the cantilever beam with quality attached to the free end subjecting to vertical pressures, is obtained. The approximate expression derives from the variational method. By comparing the precise numerical solution and the approximate solution of the cantilever beam with quality attached to the free end and subjecting to the vertical pressures, the conclusion of approximate linear relationship that is between the square of the natural frequency and axial force of the cantilever beam with quality attached to the free end subjecting to the vertical pressures is got. Through the comparing of theoretical results and finite element solutions, the difference between the approximate solution and the precise numerical solution is small, which can meet the requirements of accuracy on engineering. On this basis, as long as the natural frequencies of the structure at two load conditions are measured by experimental methods, elastic buckling load of the compressed beam can be identified. So the no damage test method to identify the elastic buckling load of the structures is given.

Abstract: With the global warming and other environmental problem, the development of renewable energy has great significance. Wind energy, the world’s fastest growing energy source, is a clean, safe and renewable source of energy. Development of wind energy resources has a positive effect to alleviate the shortage of resources and controls environmental pollution. At present, China's wind energy resources industry develops rapid, but still has some problems. This paper discusses the development of the wind energy from the view of the wind energy policy. The Government should formulate relevant economic policies and law regulations, and encourage investment on wind energy industry.

Abstract: The paper analyzed on failure mechanism of key components (blades, gearboxes) of wind turbine. Then, that introduced the development about the methods of condition monitoring of the key components. It also described that in recent years the development of methods with location of fault, fault diagnosis and failure distribution respectively. According to the present problems of condition monitoring of wind turbine, the text summed up the problems in four aspects for the future: research of the fault mechanism and failure criterion, vibration signal processing and the method of feature extraction research, study on coupling of wind turbine system, development of on-line monitoring systems.

Abstract: This paper has a brief description of technical difficulties and common quality problems during reactor internals manufacturing of PWR. Combining with the specific example, this paper has analyzed the cause of problem, and the corrective action which can be adopted. This paper can provide reference for the following project.

Abstract: The distribution of sulfur forms in the products of low temperature pyrolysis of Carboniferous high sulfur coal from Northwest China was investigated. The typical method of Gray-King assay was used to carry out the low temperature pyrolysis experiments. GC-MS analysis was used to investigate the composition of sulfur compounds in the coal tar. The results show that sulfur mainly remained in the semi-coke and accounted for 80.97% of the total sulfur. Pyrites decomposed and transformed into sulfates and organic sulfur. 5 sulfur containing compounds were detected in the coal tar and they are dibenzothiophene, benzonaphthothiophene and their substituted homologs.

Abstract: Since Japan's nuclear leakage accident, the basic policy of nuclear power is changed into promoting nuclear power steadily instead of developing nuclear power actively in primary, and speed is delayed. Therefore, it has great significance for development of China’s nuclear power to conduct a study on how to promote the competitiveness of nuclear power enterprise. The diamond theory and the analysis method of SWOT are applied to state the influence factors about competitiveness of nuclear power enterprise and make a comprehensive evaluation. According to these characteristics, some suggestions and measures are proposed to improve their competitiveness. It can lay a theoretical foundation for the steady development of nuclear power in China, which has some reference value.

Abstract: The Niutuozhen geothermal system, located in North China, is composed of the Jixian system dolomite reservoir and a Neogene sandstone reservoir. A three-dimensional model with 5437 elements and seven layers based on the geological and geothermal data was built using the AQUA3D package designed for solving flow and heat transport problems. Production history of forty five wells and pressure monitoring data from six wells were used for calibration. The calibrated model was then used to predict the geothermal system response of the geothermal field. The maximum predicted drawdown after 20 years of production without any reinjection ranged from 30 to 120 m in the north and south, respectively. The rate of drawdown was predicted to be kept at a lower level if 50% of the produced water was reinjected into the system. Cones of depression were predicted to gradually enlarge due to an increased production rate without reinjection, but were effectively limited and even diminished with a reinjection ratio of 50%. A maximum temperature decrease of 2.75°C was predicted to occur in production well A34, located near the reinjection well R3, for a production rate of 162 l/s with 50% reinjection. The maximum temperature decrease of 24.81°C was predicted to occur in the southern reinjection well R2. Prediction of temperature response indicated that the reinjection rate, the temperature of the reinjected water and the distance between the reinjection and production wells are the three factors affecting the reservoir temperature change. Reinjection is a indispensible measure for maintaining pressure of the reservoir. However, reservoir cooling induced by reinjection of the cold water should be considered carefully.

Abstract: Constant geothermal temperature is necessary to the long-term efficient operation of the ground source heat pump. SGSHP (Solar-Ground Source Heat Pump) system adopts solar energy as assistant heat source to maintain the geothermal temperature in cold regions. A design method based on equilibrium geothermal temperature was illustrated with an example of a villa in Beijing, China. Flowchart and control strategy of the combined system were introduced. Average heat collection efficiency and necessary area of the solar collector were derived on the basis of energy balance equation. Geothermal temperature variation was also researched to test if the solar energy and geothermal energy were reasonably matched. Results show that the combined system can maintain a constant geothermal temperature if it is well designed. The solar-ground source heat pump system is efficient, reliable and energy-saving.

Abstract: Water-rod is introduced into Supercritical Water Cooled Reactor (SCWR) to guarantee the homogeneous distribution of core axial power, and there could be many types of flow in water-rod. Based on three types of water-rod and flow, which named S type, D1 type, and D2 type, choosing different values of structural parameters and material thermal conductivity, the distributions of moderator density and average density in each case are obtained through making program to associated-calculate the fuel rod, coolant and moderator. The results indicate that considering only moderator density, the D2 type double water-rod which has smaller thermal conductivity and bigger outer length of inner water-rod is the best choice; considering average density, both the S type single water-rod and the D2 type double water-rod which have smaller thermal conductivity and smaller outer length of inner water-rod is the best choice; the thermal performance of D1 type double water-rod is inferior because of its inherent defect, so it is not suitable for use.