Time filter

Source Type

Jiang X.,Dalian University of Technology | Jiang X.,Shenyang Aerospace University | Duan F.,Dalian University of Technology | Tian H.,Dalian University of Technology | Wei X.,AVIC Xian Flight Automatic Control Research Institute
Reliability Engineering and System Safety

The goal of this study is to propose a reliability centered predictive maintenance scheme for a complex structure Inertial Navigation System (INS) with several redundant components. GO Methodology is applied to build the INS reliability analysis model - GO chart. Components Remaining Useful Life (RUL) and system reliability are updated dynamically based on the combination of components lifetime distribution function, stress samples, and the system GO chart. Considering the redundant design in INS, maintenance time is based not only on components RUL, but also (and mainly) on the timing of when system reliability fails to meet the set threshold. The definition of components maintenance priority balances three factors: components importance to system, risk degree, and detection difficulty. Maintenance Priority Number (MPN) is introduced, which may provide quantitative maintenance priority results for all components. A maintenance unit time cost model is built based on components MPN, components RUL predictive model and maintenance intervals for the optimization of maintenance scope. The proposed scheme can be applied to serve as the reference for INS maintenance. Finally, three numerical examples prove the proposed predictive maintenance scheme is feasible and effective. © 2015 Elsevier Ltd. All rights reserved. Source

Li B.,Institute of Space Technology | Ding Y.,AVIC Xian Flight Automatic Control Research Institute | Yin Y.-Z.,Xidian University
International Journal of Antennas and Propagation

A coplanar waveguide fed dual-band circularly polarized rectangular slot antenna is presented. The proposed antenna consists of a rectangular metal frame acting as a ground and an S-shaped monopole as a radiator. The spatial distribution of the surface current density is employed to demonstrate that the circular polarization is generated by the S-shaped monopole which controls the path of the surface currents. An antenna prototype, having overall dimension 37 × 37 × 1 mm3, has been fabricated on FR4 substrate with dielectric constant 4.4. The proposed antenna achieves 10 dB return loss bandwidths and 3 dB axial ratio (AR) in the frequency bands 2.39-2.81 GHz and 5.42-5.92 GHz, respectively. Both these characteristics are suitable for WLAN and WiMAX applications. © 2016 Biao Li et al. Source

Chen Z.-J.,Beihang University | Zhang R.-L.,AVIC Xian Flight Automatic Control Research Institute | Zhang P.,Beihang University | Zhou R.,Beihang University
Zidonghua Xuebao/Acta Automatica Sinica

The development of flight control is facing unprecedented opportunities and challenges. According to the new demands and new technological features of future flight vehicles, the opportunities and challenges of flight control are analyzed from the following five aspects: 1) new characteristics of flight vehicles; 2) information-oriented environment; 3) autonomous of unmanned systems; 4) high-reliable reconfigurable fault-tolerant systems; 5) assessment and validation of flight control systems. To exploit the opportunities and meet the challenges, the following five research aspects should be strengthened: 1) new concepts, theories and methods with respect to new characteristics of flight vehicles; 2) information-oriented integration of control, computing and communication, and integration of control, decision-making and management; 3) high level autonomous unmanned systems; 4) high-reliable and reconfigurable fault-tolerant flight control system; 5) high-efficient, high-reliable assessment and validation on flight control systems. Source

Ding X.F.,Beihang University | Li Z.,AVIC Xian Flight Automatic Control Research Institute
Applied Mechanics and Materials

Interior permanent magnet synchronous motor (IPMSM) systems are vulnerable to uncontrolled generation (UCG) when the inverter switches loss their drive signals suddenly during flied weakening high speed operation. At this point, uncontrolled rectifier is composed by freewheel diodes in the inverter, the current comes from the motor through the rectifier, and then charges the battery. This paper develops a simple analytical model of this system firstly, and then carries out the simulation of UCG transient process to investigate the impact of the motor speed, battery capacity and other factors on UCG and feedback-power obtained throughout the process. Moreover, circuit improvement is presented in order to avoid destruction risk of the battery, motor, inverter and other relevant components during UCG. © (2014) Trans Tech Publications, Switzerland. Source

Guo S.,Northwestern Polytechnical University | Song Y.,AVIC Xian Flight Automatic Control Research Institute | Gao Y.,Northwestern Polytechnical University | Han Q.,Northwestern Polytechnical University
China Communications

Performance of the Adaptive Coding and Modulation (ACM) strongly depends on the retrieved Channel State Information (CSI), which can be obtained using the channel estimation techniques relying on pilot symbol transmission. Earlier analysis of methods of pilot-aided channel estimation for ACM systems were relatively little. In this paper, we investigate the performance of CSI prediction using the Minimum Mean Square Error (MMSE) channel estimator for an ACM system. To solve the two problems of MMSE: high computational operations and oversimplified assumption, we then propose the Low-Complexity schemes (LC-MMSE and Recursion LC-MMSE (R-LC-MMSE)). Computational complexity and Mean Square Error (MSE) are presented to evaluate the efficiency of the proposed algorithm. Both analysis and numerical results show that LC-MMSE performs close to the well-known MMSE estimator with much lower complexity and R-LC-MMSE improves the application of MMSE estimation to specific circumstances. © 2013 IEEE. Source

Discover hidden collaborations