Papers by Author: Fei Fan Chen

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Authors: Ji Jiao, Fei Fan Chen
Abstract: Based on information pipeline technology, a clock soft synchronization method used in distributed measurement and control system is proposed. Using a separate information pipeline, the synchronization information is broadcasted to nodes in the distributed measurement and control system by synchronization node every message transaction cycle time, and all nodes automatically synchronize the local clock after receiving it. We analyze the theoretical synchronization error and verify this clock soft synchronization method in CAN bus. The theory analysis and experimental results indicate that the synchronization error mainly consists of propagation delay error, drift error and CAN loop delay error, and it increases linearly with the increasing of transmission distance.
Authors: Hui Long Dong, Bo Yu Zheng, Fei Fan Chen
Abstract: A novel peak diffusing measurement method is reported. In this method, a pulsed Gaussian heat source is focused on the material’s surface, and a thermal camera is utilized for detecting the temperature evolution. Specially, the peak temperature time tmax at different distance from the heat source center is extracted using the Singular Spectrum Analysis (SSA). Thermal diffusivity is then calculated by fitting multiple sets of extracted tmax into the derived regression equation. The advantage of this method is that it does not require the high precision time synchronization between the excitation source and detector. Also, the calculation process is very simple, which achieves an efficient in situ measurement of the thermal diffusivity. The measured radial thermal diffusivity of samples prepared from Ti and Ni is in good agreement with the reference data with a 1.8% and a 3.9% error bound.
Authors: Fei Fan Chen, Jing Feng, Ming Hao Wang
Abstract: Sun sensor is one of the key attitude sensors widely used in spacecraft attitude determination. Its accuracy is one of the major technical specifications. In this paper, we propose two methods for accuracy test and evaluation, which have been proved to be efficient and convenient. With these two methods, it is possible to isolate and then, eliminate the rotational error from the rotation table that holds the sun sensor so that the performance of the sun sensor can be evaluated. The proposed two methods can be also applied to test the performance for other angle measuring devices.
Authors: Hong Cai Li, Fei Fan Chen, Yong Gui Dong
Abstract: Local environment control system (LECS) has been widely used in many areas as the necessary guarantee for most precision instruments. A sealed air cooling constant temperature box with dual-chamber structure that can provide constant working condition for precision instruments in-vehicle was developed. According to the heat transfer analysis of the double plate-fins heatsink, the heat radiation area and dimensions were determined based on electrical analogy. The air flow rate and temperature distribution of the system in heat steady-state was simulated by CFD software, and the results are consistent with that of experimental test. In different conditions, the thermal test results indicate that when the heat flow rate in the inner chamber is about 170 W, the temperature difference between inner chamber and environment is no more than 6.5 °C. The thermal design and test methods can be as the reference for the design of other precision instruments in-vehicle.
Authors: Hong Cai Li, Fei Fan Chen, Yong Gui Dong
Abstract: A sealed air cooling local environment control apparatus that can provide constant working environment for precision instruments has been developed. Based on electrical analogy, the thermal network model has been derived, and the parameters of thermal conductance and capacitance in the model were measured in different test conditions. The obtained maximum relative errors between the measured values and the theoretical values are in the range of 0.6% to 6%, which indicates that the proposed theoretical model and the test method are feasible. The obtained parametes can help to understand the heat transfer properties of the apparatus, and the methods can be also as the reference for the test and rapid commissioning of other local environment control apparatus.
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