Applied Mechanics and Materials Vol. 387

Abstract: Compared with the closed screw conveyor, the discharging performance of open-type screw structure has a certain degree of uncertainty. The design of open-type screw structure is firstly presented in this paper. A novel open-type screw discharging structure is developed on the base of the requirement of industry, and structural parameters and operation parameters of screw are given. Based on the discrete element method, the simulation model of spiral discharging performance is built. The influence of the angular velocity of on open-type screw discharging performance is discussed. The analysis results show that the angular velocity of screw has a great influence on the discharge performance in the condition that other parameters remain unchanged. The presented method has an important guiding role and theoretical reference value to design of open-type screw discharging structure.

Abstract: In order to improve the safety level of aircraft anti-collision, an anti-collision risk assessment methods based on Relevance Vector Machine (RVM) is proposed. First, RVM learning under Bayesian framework is introduced as well as its basic principle and modeling process, and then on the basis of system point of view an anti-collision risk assessment index system is established, finally, on this basis, RVM assessment model for aircraft anti-collision risk is constructed. It can adaptively adjust the weights of influence factors without analyzing the relationship between various factors in the system. Examples show that, for anti-collision risk assessment, RVM has a novel structure and convenient application, and the result can reflect the actual safety situation.

Abstract: Based on the idea of single cavity trapped vortex combustor, a advanced vortex combustor which is constitute by three blunt bodies and double concave cavity is proposed. And the interior combustor flow characteristics are analyzed. The results shows that the flow field characteristics changed a lot before and after combustor modification, and D2=20mm, D3=4mm are respectively the best modification scheme on the second and third blunt body.

Abstract: The design focus of precision corn planting device of furrow seeder with vertical dropping with whole plastic-film mulching on double ridges is to optimize its compensatory cam, and it aims to make compensation for the horizontal velocity of soil opener when the whole machine is moving forward. Under the precondition of ensuring sowing with vertical dropping by soil opener, the structure of compensatory cam shall also meet the requirements of smooth transition, space and cost saving. In order to achieve the above-mentioned design goals, the forward speed of machines and tools, the horizontal distance between the supporting point of amplification mechanism and the centering point of crank rotation, and the horizontal distance between cam and the centering point of crank rotation are taken as the experimental factors, offset circle radius, small-curvature radius and mass are regarded as the experimental indicators, therefore three factors and three levels orthogonal experiment is carried out, it is obtained that the optimal combination is A₁B₂C₁ by analyzing the results of experiment.

Abstract: Frequency meter as a kind of electronic measuring instruments, have been widely applied in the field of Mechanical and Electrical automation. The design of a frequency meter based on EDA technology, is implemented in EDA software platform of Quartus II, using hardware description language (HDL) editor can also be seasonal schematic, design, system hardware circuit compiler, simulation, system is divided into five modules: frequency module, control module, counting module, range switching module and display module, the hardware design requires a download chip EPM7128S and input and output circuit.

Abstract: In this paper, the high speed motor hybrids with a radial-axial 3 degree of freedom hybrid magnetic bearing unit and BPMSM unit is proposed. The radial suspension force and magnetic field distributions with different magnetized mode are calculated. The losses are calculated and compared using time-stepping finite element method. The research results have shown that the high-speed BPMSM with Halbach array permanent magnet rotor has sinusoidal air-gap magnetic field, minimum losses.

Abstract: This paper focus on the instability of asynchronous motor direct torque control system which caused by PID parameter changes. In order to improve the self-tuning capabilitiy of PID countroller, enhance the speed and stability of control system. fuzzy adaptive method was adapted to optimize PID parameter. Simulation results show that: this strategy improved the performance of direct torque control system significantly.

Abstract: this paper use the stepper motor as driver, designed the structure of a digital pressure relief valve of water-based hydraulic, and establishment mathematical model of the valve element cavitation flow field, simulated and analyzed the different the valve element cavity volume and rounded of water pressure relief valves cavitation flow field by use Fluent software. The results showed that: It can suppressed cavitation that appropriate increases cavity volume and reduced the spool fillet.

Abstract: High-efficiency, energy-saving and environment-protection have become the current consensus of the world. The basic requirement of energy-saving for domestic appliances and electronic products has been accomplished to reduce the power on standby. The key point of energy-saving is to decrease the loss damaged in the switch. Boost converter (DC/DC) is a lower-loss, higher-efficiency module with the 90% conversion rate.