Analysis of electrical performances of planar active phased array antennas with distorted array plane

The influence of the distorted plane of the active phased array antenna on the electromagnetic performance is of great significance to the research on and development of the high-performance antennas. On the bent and bowl-shape distortion, the model is established of the relationship between the electromagnetic performance and the position error of the radiated elements. The method is presented of analyzing the far-field pattern of the distorted rectangular active phased array antenna. The analysis results of a planar phased array antenna with different distortions grades prove the validity of the model. Therefore, by the method, the antenna designers may set the reasonable requirement on the structural tolerance in manufacturing antenna.

Fault Tolerant Suffix Trees

Classical algorithms and data structures assume that the underlying memory is reliable,and the data remain safe during or after processing.However,the assumption is perilous as several studies have shown that large and inexpensive memories are vulnerable to bit flips.Thus,the correctness of output of a classical algorithm can be threatened by a few memory faults.Fault tolerant data structures and resilient algorithms are developed to tolerate a limited number of faults and provide a correct output based on the uncorrupted part of the data.Suffix tree is one of the important data structures that has widespread applications including substring search,super string problem and data compression.The fault tolerant version of the suffix tree presented in the literature uses complex techniques of encodable and decodable error-correcting codes,blocked data structures and fault-resistant tries.In this work,we use the natural approach of data replication to develop a fault tolerant suffix tree based on the faulty memory random access machine model.The proposed data structure stores copies of the indices to sustain memory faults injected by an adversary.We develop a resilient version of the Ukkonen’s algorithm for constructing the fault tolerant suffix tree and derive an upper bound on the number of corrupt suffixes.

Research on a six-phase permanent magnet synchronous motor system at dual-redundant and fault tolerant modes in aviation application

With the development of more/all electrical aircraft technology, an electro-mechanical actuator（EMA） is more and more used in an aircraft actuation system. The motor system, as the crucial part of an EMA, usually adopts the redundancy technology or fault tolerance technology to improve the reliability. To compare the performances of these two motor systems, a 10-pole/12-slot six-phase permanent magnet synchronous motor（PMSM） is designed with the concentrated single-layer winding, which is able to operate at dual-redundant and fault tolerant modes.Furthermore, the position servo performances of the six-phase PMSM at dual-redundant and fault tolerant modes are analyzed, including the normal and fault conditions. In addition, a variable structure proportional-integral-derivative（PID） control strategy is proposed to solve the performance degradation problem caused by phase current saturation. Simulation and experimental results show that the fault tolerant PMSM has a better position servo performance than the dual-redundant PMSM, and the variable structure PID control strategy is able to improve the performance due to phase current saturation.