Advanced Materials Research Vols. 562-564

Abstract: The DC motor has good characteristics of large starting torque and good traction and strong overload capacity, traditional battery motor vehicle often adopts DC motor drives as driving system and uses the series resistance to adjust speed. However, in actual coal production, since motor vehicles are often placed in wet, explosive and dusty environment, the speed control system of motor vehicle has strict proof and moisture requirements, however, the inherent characteristics of the DC motor make it a serious shortcoming in the coal mine production, there is an urgent need to improve the structure to meet today's actual demand for coal mine automated production. This article is in this context, to compare the DC motor speed control system with AC speed control system of the mine car, discussing today's mainstream technical programs of AC speed control system, focus on the analysis of the great differences over performance and economic efficiency of the speed control system of mine motor vehicle after adopting AC speed control system.

Abstract: In hybrid electric vehicles, there is a set of electricity generating system. This system was modified to meet requirements of vehicle-mounted power plant. The new system is mainly composed of engine, generator, planetary gears, motor, battery, transfer case, control system and etc. and the planetary gears mechanism has two sets of planetary, control system includes vehicle controller, engine controller, motor controller, and inventor. This system can perform the functions which include vehicle driving, generating with vehicle ruining and generating with vehicle stopping. It can meet requirements of special purse vehicles.

Abstract: In this paper a test set has been established and the effect on the dynamic characteristic of the frame tower by the joint clearance between the frame and tower has been studied experimentally. Experimental results show that the frame with clearance has no influence on the natural frequencies of a single tower, while it has constraint for the single tower’s displacement. Included in this study are the discussions on the influence of support position on the dynamic characteristics of the frame tower with a clearance. The analysis shows that the damping ratio increases and maximum amplitude descends with the increase of height of the support position.

Abstract: A new type continuous variable damper based on solenoid valve is studied in this paper. The structure and principle of continuous variable damper based on solenoid valve are analysed. The hydraulic model and mathmatic model of rebounce stroke and compress stroke are established. Then the damping characteristic is simulated in matlab software and is provided a theoretical reference for product development of the damper based on solenoid valve.

Abstract: In order to study how to deal with the load changes of the wind turbine transmission system that high-frequency wind caused, this paper used the mathematic model of combined type wind speed. This model simulated the actual wind speed precisely using the speed data obtained from Dalateqi wind farm. In this paper, several wind speed and direction which referred in the Wind turbine generator system-Design requirements were analyzed. We drew the velocity curve of different time which used the combined simulation model according to the referred model. Error analysis proved that the combined model simulated the actual wind speed with high precision. The high-frequency wind model simulation had practical significance on the engineering application.

Abstract: In order to establish the three-dimensional model of the crankshaft piston group, the application of characteristic modeling method was proposed directly through the designer to extract features from the BULL operations, and finally form a part model of the design and definition. Analysis of the expression of the crankshaft features and characteristics of the link, use Pro-E to build a diesel engine crankshaft and the piston rod group of feature modeling. a new three-dimensional assembly drawings was built. It provide a new design ideas for reserachers.

Abstract: Heat pump is widely used in many fields, and it has advantages of energy-saving, environment-friendly and good economy, etc. Coal mine drainage, cooling water from cooling tower of power plant and exhaust air in coal mine have stable temperature throughout the year, and they are good heat (cold) source for heat pump. By analyzing technical and economic performance of heat pump, several ways and purposes of heat pump used in coal mine are proposed, and the technical processes are given. Application of heat pump to recycle energy from coal mine drainage, cooling water and exhaust air is beneficial to improving economic efficiency and achieving sustainable development for coal mine.

Abstract: Nitrogen oxides (NOx) are one of the pollutants generating from coal combustion in stoker boilers, and they are very harmful to human health and environment. It is necessary to study NOx emissions control technology for stoker boilers. By explaining the formation mechanism and control methods of thermal NOx, fuel NOx and prompt NOx, NOx emissions control technologies applied in stoker boilers are introduced and research advances are given, some advice for NOx emissions control in stoker boilers is put forward.

Abstract: Fault detection and diagnosis of a wind turbine gearbox are important to ensure the reliability and useful life of the wind turbine system. In this paper, an experimental test in wind turbine gearboxes is carried out to obtain faulted information which consists of response random non-stationary noise and the additional response due to failure. An approach, using wavelet de-noising method, is proposed for removing non-stationary noise from the recorded signals. The time domain analysis and frequency analysis are used to diagnose the fault location of the machine accurately. It is shown that wavelet de-noising method provides a better correction than conventional method in order to remove non-stationary noise. Diagnosis results indicate that the high-speed shaft of wind turbine gearboxes has a serious imbalance.

Abstract: The pressure drop in a helical-coil heat exchanger is studied. The helically coiled tube with a coil pitch of 1080 mm and coil diameter of 950 mm is fabricated by bending a stainless steel tube of 8m length and 15.6 mm inner diameter. The total height of the helix tube is 2.8 m. The concerned range of mass flow rate for two-phase flow is 25-100 kg/m2s. Computational fluid dynamics (CFD) simulation analysis of pressure drop in the vertical helical-coil heat exchanger is carried out.