Xiao Feng Meng

Combined Accelerations Produced by Vibrafuge

Various environmental factors will adversely influence accelerometers working in the field. Mixed inputs, including external causes and the intended acceleration, are important contributors to the problem. As a consequence, calibrating accelerometers with multiple accelerations is required by manufacturers and customers. We introduce a multi-component mechanical system called vibrafuge to provide multiple accelerations. In this paper, we deduce a general model of the accelerations reproduced by an ideal vibrafuge with homogeneous transformation of matrix. Based on the model, we have an elementary analysis of the components of the output acceleration and point out two byproducts. Investigation in this paper could lay the groundwork for vibrafuge testing of accelerometers.

Telemetry data processing flow model: a case study

Purpose – The purpose of this paper is to develop the model of telemetry data processing flow (TDPF) for TDPF development and the TDPF run-time infrastructure to improve the spacecraft health monitoring capability. Design/methodology/approach – This research tries to develop the TDPF by flow-based programming (FBP) method and the component-based telemetry data processing software. Findings – The result from the case study is positive, thus reflecting the appropriateness of the suggested method. Practical implications – Application of the proposed TDPF model and the component-based telemetry data processing software may result in improved development efficiency and less development costs. Originality/value – This paper provides an effective way to develop TDPF without recompiling the software. It greatly facilitates the TDPF development that hopefully will save the TDPF development cost.

Research on the Efficiency Improvement of Design for Testability Using Test Point Allocation

Traditional design for testability (DFT) is arduous and time-consuming because of the iterative process of testability assessment and design modification. To improve the DFT efficiency, a DFT process based on test point allocation is proposed. In this process, the set of optimal test points will be automatically allocated according to the signal reachability under the constraints of testability criteria. Thus, the iterative DFT process will be completed by computer and the test engineers will be released to concentrate on the system design rather than the repetitive modification process. To perform test point allocation, the dependency matrix of signal to potential test point (SP-matrix) is defined based on multi-signal flow graph. Then, genetic algorithm (GA) is adopted to search for the optimal test point allocation solution based on the SP-matrix. At last, experiment is carried out to evaluate the effectiveness of the algorithm.

Study on Transient Temperature Generator and Dynamic Compensation Technology

According to the problem of dynamic calibration of the thermocouple, especially impossible to evaluate the rise time and to unify the calibration method, a new method of thermocouple calibration is proposed. Based on the method rise time of the input signal of thermocouple and step amplitude could evaluate accurately. The practical process of calibration shows that the method is effective.

Design of a Heat Exchanger and Temperature Homogenization Device for Airflow in Chamber

Traditional heat-exchanger can ensure the air in chamber a specific bulk temperature, but cannot guarantee the temperature distribution is even. A heat exchanger and temperature homogenization device was designed to precisely adjust the temperature and temperature uniformity of airflow. The device was made up of several parallel processing units. Each unit was an independent heat exchanger with temperature homogenization function. To improve the design of the device, evaluation indexes were proposed for both heat transfer capability and temperature uniformity of the airflow field. Analysis and comparison of 3D numerical simulations using FLUENT were made to figure out the optimal way. The model proposed can provide guidance for practical applications. The final results indicate field synergy principle can be used to analyze the temperature homogenization of airflow.

Optimum Test Point Selection Based on MADM for Analog Fault Dictionary Techniques

a new graph-search algorithm based on multi-attribute decision making (MADM) is proposed. Firstly, A* algorithm is used for graph-search, but when cost functions of two nodes are equal, three attributes describing a node are introduced. Secondly, a multi-attribute decision based on maximum deviation principle is used for nodes evaluation in order to select the best node for expanding. The proposed algorithm could overcome deviation brought by node evaluation based on information theory metrics only, which results in high accuracy. The outcome of simulation verification at the end of this paper manifests that this algorithm has excellent accuracy as the exhaustive algorithm, and is more quickly for large scale computation.

A multi-attribute decision based optimum test point selection for analog fault dictionary techniques

The optimal test point selection is an important problem in testability analysis and diagnosis. In this paper, a new algorithm based on graph-search and multi-attribute decision is proposed. Firstly, A* algorithm is used for graph-search, but when cost functions ƒ(x) of two nodes are equal, three attributes describing a node are introduced, that is, information entropy, the number of un-isolated faults, the number of available test points for expanding. Secondly, a multi-attribute decision based on maximum deviation principle is used for nodes evaluation in order to select the best node for expanding. The proposed algorithm could overcome deviation brought by node evaluation based on information theory metrics only, which results in high accuracy. The outcome of simulation verification at the end of this paper manifests that this algorithm has excellent accuracy as the exhaustive algorithm, and is more quickly for large scale computation.