Advanced Materials Research Vols. 383-390

Abstract: This paper proposes an improved design of micro-machined tuning fork gyroscope (M-TFG) to better decouple the cross talk between the driving and sensing directions and to increase resolution. By employing dual-folds spring suspension, the drive mode and the sense mode are mechanically decoupled. Through careful layout design of the location of the dual-folds spring suspension and the drive combs, the mechanical coupling effect is further decreased by isolating the unwanted excitation from detection. The peripheral circuit is also the important part to realize the function of the gyro system. Since the analog circuit has some inherent shortcomings, which has limited the accuracy of the gyro. In this paper, a digital control system for micro-comb is introduced.

Abstract: This paper introduces an online auto-monitoring instrument which can automatically slice the external insulation cover of the leading wire and accurately measure the wick resistance in the assembly line of the detonator wick resistance. With safety protection circuit, constant current source is employed to measure the resistance, endowing the design with high accuracy, safety protection features and high degree of automation. It is expected to change the traditional production process where manual work has been used to measure and collect statistics, hence could greatly improve labor productivity as well as product quality and produce favorable application and promotion value.

Abstract: SCM control technology be applied to inductively coupled plasma excitation source in this paper. Through controlling thyristor trigger angle control AC voltage regulation, the go through step-up circuit to achieve output power continuously adjustable. It introduces construction and work principle. Grating spectrograph is co-operated with thyristor AC voltage ICP excitation source for performance tested. By means of Ar355.431nm tested power stability≤0.5%. Testing Fe, Cu, Au and other elements shows that the detection limit is 10-9g/ml, precision relative standard deviation RSD≤ 3％. Results show that this voltage regulation technology is stable, reduces the instrument’s size and operates conveniently. It is suitable for ICP excitation source in spectroscopic analysis.

Abstract: Rolling schedule is the core contents of rolling process. A reasonable rolling schedule can make rolling process to obtain optimum state. There are more mathematic models and the constraint conditions to be considered in the rolling schedule, therefore, the optimization becomes a complex problem. In this paper, genetic algorithms based on real number encoding are used to optimize rolling schedule aiming at equating the relative load and optimum plate shape though instance. The optimum result shows that the method is satisfactory and promising.

Abstract: This paper describes Freescale company’s DSP device MC56F8013 implementation of a fridge compressor control system about BLDC motors without position sensors, which includes motor starting and back EMF running. The motor start-up detects the variation of rotor position according to inductance of stator core. Then when the rotor is accelerated to a certain speed, EMF mode is switched. The EMF mode estimates the rotor position by back EMF zero-crossing detection method. The experiment results prove that the proposed system based on MC56F8013 can work normally and efficiently, and guarantee the demand of domestic refrigerator.

Abstract: In order to obtain more stable speed response, this paper designs a compound speed controller for travelling wave ultrasonic motor. The controller uses two variables, frequency and voltage amplitude, as the controlled variables. Among them, the frequency controller finishes the correction of larger speed error, and the voltage amplitude controller is used to accomplish the fine-tuning of speed error. The problems such as the jumping phenomenon in speed response, and saturation of voltage amplitude, are solved by this control strategy. Experiments show that, the control strategy is effective, and the speed control response is good.

Abstract: The pollutant emissions of a four-stroke spark ignition gas engine generator operating on biogas–LPG blends of varying excess air ratios and LPG concentrations were investigated in this paper. Experiments were carried out at a constant engine speed of 1400 rpm and a constant electric power output of 3.5 kW. The experimental results showed that NOx emissions were elevated at an excess air ratio of around 1.2 as the LPG concentration was increased. CO2 emissions decreased as the excess air ratio and LPG concentration increased, due to lean-burn conditions and LPG combustion. These results demonstrated that the addition of LPG to biogas enabled the effective generation of electricity using a gas engine generator through lean-burn combustion. The adding of LPG of 0%, 5%, and 10% in volume is interchangeable. Mixing inert gas such as N2 and CO2 in the end user side to increase the gas MN, thereby increasing its antiknock tendency, furthermore, the measures such as the installation of closed-loop control engine with oxygen sensor in the exhaust and adjust air-fuel ratio accurately and adjusting engine ignition timing, to adapt the changes in gas composition to ensure that the engine working conditions are not significantly affected, to meet the requirements of natural gas interchangeability.

Abstract: In this paper, three-dimensional numerical simulation is conducted on the flow and heat transfer process for elliptical tube heat exchanger with rectangular vortex generators and triangular vortex generator by Fluent software, respectively, and the performance for elliptical tube heat exchanger with plate fin is compared. The results show that the Nusselt number increases with the increase in Reynolds number for the inlet velocity range from 1 to 5m/s, friction coefficient decreases with the increase in Reynolds number; at the same Reynolds number, Nusselt number for fin with Vortex Generators and friction coefficient are higher than that of elliptical tube with plate fin ; the vortex generator shape and angle of attack have a great impact on the comprehensive performance within a simulated attack angle and the velocity, at the same pump power, the comprehensive performance for heat exchanger with the rectangular vortex generator increase up to 10%.

Abstract: A capillary tube air-conditioning system was designed after presenting the design method of the cold and heat source, water system, fresh air system, control system. In the paper, the experimental method was employed to study the change and distribution of indoor-air temperature, and the response of capillary tube mat surface temperature, while the computational method was employed to analysis the tube mat radiant heat transfer and convective heat transfer. It is concluded that, the indoor temperature rose faster and the uniformity of indoor temperature distribution was better when ceiling radiant heating of capillary tube was adopted.

Abstract: Piston ring is one of the most important sealing components that can be easily damaged in reciprocating compressors. The severe non-uniformity of the pressure distribution was suggested to be the essential reason for the premature failure of the piston rings. Therefore, a test rig was set up to measure the pressure distributions as well as the build-up of the dynamic pressure difference, which could reveal the root cause for the non-uniformity of the pressure distributions. The results showed that the build-ups of the pressure differences between different rings were not simultaneous; there existed a threshold pressure, and the latter ring could work only when the pressure before the former ring reached to the threshold value. The pressure distributions were also investigated at the start-up and shut-down of the compressor, which further validated the cause of the premature failure of the first ring.