Applied Mechanics and Materials Vols. 496-500

Abstract: During Hot Blast Stove (HBS) combustion, NO_x forms rapidly when the flame temperature above 1420°C. In order to restrain the amount of NO_x formation during combustion of HBS, the formation mechanism of NO_x is investigated, and the NO_x formation rate and amount in HBS are calculated by means of thermodynamic model. A new type of dome combustion HBS is developed based on high temperature air combustion (HTAC) technology. A comparison on the combustion process and characteristic of conventional HBS and HTAC HBS is performed by application of Computational Fluid Dynamics (CFD) simulation model. Temperature and concentration distribution, flame shape and NO_x concentration distribution of two kinds of stove are calculated. The result shows quite symmetrical HTAC stove temperature distribution. Under the same dome temperature, NO_x amount is 80ppm only, reduced by approximate 76% in comparison with conventional stove.

Abstract: According to the principle of the train longitudinal dynamics, the heavy haul longitudinal dynamics nonlinear model is established to analyze the influences of the load distribution pattern and the locomotive position on train longitudinal dynamics. The study of this paper is divided into two parts. The first, train model is composed by a locomotive and six trailers, researching the influences of the load distribution pattern on train longitudinal dynamics, the analysis results show that, the best load distribution pattern is the descending from head to tail of the train, in this case, the coupler force is minimum, and the train longitudinal dynamics is best; the second, train model is composed by two locomotives and five trailers, researching the influences of the position of the locomotive on train longitudinal dynamics. The analysis results show that, if the first locomotive is at the head of the train, then the second locomotives best position is at the end of the train, in this case, the coupler is minimum. But the train longitudinal dynamics performance is the worst with two locomotives are located in the head.

Abstract: For a certain type of small unmanned aerial vehicles (SUAV), using the vortex lattice method (VLM) estimated the aerodynamic derivatives, establishing linear small-perturbation equations based on level and non-sideslipping flight. Analyzed the static stability and mode characteristics based on the dimensionless derivative and matlab simulation. Early in the design, by mechanism modeling and performance analysis for the UAV through pneumatic calculations could get a lot of valuable reference data of the UAV. This has some practical significance for system performance analysis and flight control system design.

Abstract: Inductive pulse power supplies attract interests since their energy densities are one order of magnitude higher than those of capacitive ones at the same power output capacity. STRETCH meat grinder was put forward by IAT (Institute of Advanced Technology). Energy Recovery circuit was developed to improve the energy efficiency and reduce the energy loss of the whole circuit. The residual energy can be recovered by triggering the related thyristors. Simulation results show that the topology with energy recovery circuit can recover most of the residual energy by triggering thyristors and has potential applications for high energy systems in the future.

Abstract: Neutral-point (NP)-clamped three-level converter is a widely used topology in the research fields of the multilevel converters, which suffers from the NP voltage drift as its main technical drawback. In theory, it is based on the fact that the virtual space vector modulation approach could completely control the balance of neutral-point potential, so this paper introduces a improved control strategy of neutral-point potential balancing in three-level converter, which combines the space vector modulation approach based on virtual vectors with the algorithm of modifying small vectors pairs distribution time accurately. Relative to the traditional proposed algorithm of setting voltage tolerance range to modify small vectors pairs distribution time,the performance of algorithm of capacitor charge balancing is better and its accuracy of control is more precise. The feasibility of the proposed control approach has been verified via experiment results.

Abstract: In light of the difficulty including the complicacy of heat transfer process with hot natural gas injected in gas lift annulus, regular temperature prediction methods are commonly used to consider the tubing fluid temperature for the heat transfer from tubing to annulus, actually the tubing fluid will not be the external heat transfer but it will be heated by annulus when the gas temperature in annulus is higher than the tubing fluid temperature, as well as especially the prediction of tubing wellhead temperature in terms of fluid temperature distribution traits in annulus and tubing, regular temperature prediction methods manifest limitation due to their applicability. Based on the fairly comprehensive tubing fluid temperature distribution prediction model with consideration of Thomson effect and such factors as kinetic energy, annular convection heat transfer and phase change etc. developed by the predecessors, and according to the basic principle of conservation of energy and heat transfer, the actual heat transfer process with hot natural gas injected in gas lift annulus was considered as a plus in this paper. The models for actual heat transfer and tubing fluid modified temperature prediction were established and eventually, the models were verified via multiple field tests. The reliability, capable of satisfying the requirements of engineering precision, in terms of temperature distribution of model prediction was proved.

Abstract: The application of Lagrange equation to establish the dynamic precision CNC machine tool-box foundation - soil system model. By applying the boundary conditions. Analyzed the dynamic of three different soil system under the action of impact response, Laid the theoretical foundation for the optimization design system.

Abstract: The design of lathe saddle depends on the designer experience mostly. To solve this problem, the 3D model is established to analyze the mode frequency base on parameterization design and the modal sensitivity of design parameters of lathe saddle is analyzed. According to the results of modal analysis, the sensitivity curves of important design parameters that have great influence on modal frequency are found out. These results are vital reference for the design of lathe saddle.

Abstract: With the increase of power system load, the demand for reactive power is also increasing. In order to ensure the power quality and improve equipment utilization, transmission of reactive power in power grid can lead to network loss and the voltage of the electricity. Installing reactive power compensation device in power grid is the essential means to meet the demand of power grid reactive power [1].The parallel capacitor reactive power compensation device is equipped in the coal mine 3.3 kV system reactive power compensation [2]. Introducing the parallel capacitor reactive power compensation principle and related problems, analysis of the current commonly uses contactor, relay and thyristor switch device, chooses the contactor and breaks pipe parallel composite switch which can have contact and non-contact switch to solve their problems [3]. Using software EMTP simulation composite switch voltage zero input, the result is very good to restrain the impact flow; Compound switch off after current zero avoids the contactor breaking arc, the simulation thyristor compound switch and diode in parallel.

Abstract: Particle image velocimetry was applied to measure the velocity field during the flocculation process under the conditions that the flocs compounded with kaolin and polyaluminium chloride were used as seed particles without any other special seed particle during the flocculation process. The results indicated that the flocs formed in the flocculation process can be used as seed particles to measure the instantaneous velocity maps of the flow field with good performance during the flocculation process by PIV. At the same time, the experimental results proved that PIV can be exploited as a useful tool in the synchronism measurement the velocity field and flocculation processes.