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Flight testing is a necessary procession which gathers information and data from the airplane when flying. The airborne distributed analog data acquisition system is used to collect, store and display the analog data of the airplane in the flight test, which provide data support for further aircraft state estimating, performance test and fault diagnosis. The essence of it is a wild-distributed data acquisition system which gathers large numbers of analog parameters with high time synchronization accuracy Traditional airborne data acquisition system is based on PCM architecture which has advantages in system time synchronization stability, however, as planes become more sophisticated, a large number of parameters with a wild spatial distribution needs to be collected, the routing needs to be more concise as long as the time synchronization accuracy is highly demanded. As a result, the existing PCM architecture may not fully meets the requirements of the latest flight test. In this paper a hierarchical distributed airborne analog data acquisition system is designed and developed. In order to enhance the system expansibility and achieve high bandwidth, an easy-routing distributed architecture which combines Ethernet with the RS-485 bus was proposed. A RS-485 frame based time synchronization is applied to achieve high time synchronization accuracy. It is verifiable that the developed prototype can synchronously collect analog signals under high time synchronization accuracy, which fully meet the requirements of China self-developed large airplane and boost the development of China aviation industry.

Aiming at the defect non-destructive testing problem for one-dimensional rod-like structure, a time reversal based defect signal multi-modal propagation model is developed and a new one-dimensional structure non-destructive testing method based on time-reversal and multi-modal is proposed. Through analyzing the dispersion effect of guide waves in steel leading to signal distortion which means a single mode waveguide is changed to multi-modal, a multi-modal transfer function of the structure is formatted which theoretically verifies the feasibility of time reversal for one-dimensional structure defect testing. The simulation results show that time reversal method can be applied well in one-dimension structure to eliminate the multi-modal of guided wave and emphasis defect signal.

Idle listening is one of the most main sources of energy waste in WSN and many low power protocols(LPPs) have been proposed based on duty cycling to reduce this cost. The research of LPPs can effectively save energy and prolong network lifetime. Therefore, a thorough experimental evaluation system of LPPs is mandatory. This motivated us to build a testbed — TELPP that automates LPPs evaluation by analyzing schedule of node's power and state transition. Our testbed includes (i.) wireless nodes, (ii.) framework for IEEE1588 synchronization clock unit and data acquisition unit and (iii.) software system for experimental control, data storage and analysis. To demonstrate the efficiency of TELPP, we carried out the study of testbed itself and a set of well-known LPPs.

In view of the drawback of traditional bridge 4-quadrant converters which need higher dc-side operating voltage, a new type quasi-buck topology of converters is proposed whose dc-side voltage is reduced by approaching 50%, thus appropriate for lower voltage applications. This paper presents the modeling with the state space averaging method, and steady state theoretical analyses of the converter. The validity of the topology and its model along with the theory is confirmed by both MATLAB numerical simulations and experiment results.