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Scientific Research

click:   time:2020-11-19

SAST is a research-oriented school targeting at conducting frontier research in the field of aerospace science and technology. Our research solves problems arisen in the exploration of the near and deep space environment. The research domain encompasses the aircraft measurement and control, advanced navigation control, as well as multi-source detection and guidance. Our research expands the breadth and depth of the knowledge and understanding of the aerospace field. The long term goal is to push forward the cutting edge of the aerospace technology, build up a research team of high quality in space information area, and gradually form the research achievements in fundamental theories and key technologies. Combining engineering applications, the school focuses on constructing an experimental basis that cultivates the creative and research-oriented talents. As a result, the development of the space science and technology can be gradually elevated.

The current research condition and laboratories of SAST can well support its high level research works. SAST has established the long term and strategic corporation relationships with many renowned research institutions all over China, e.g., AVIC I The First Aircraft Institute, Beijing Institute of Telemetry (704 Research Institute), State Key Hsue-Shen Tsien Laboratory and Xi’an Branch Institute of China Academy of Space Technology (CAST), 20 Research Institute of China Electronics Technology Group Corporation (CETC), as well as 771 Research Institute of China Aerospace Science and Technology Corporation (CASC). The corporation mainly focuses on the joint talent training, high level talent exchange, and jointly tackling the technical problems.

All faculty staffs of SAST have the experiences of hosting or participating in the state key research projects. In the latest 3 years, SAST has hosted 1 national 973 projects, 7 major national science and technology projects, 3 national 863 projects and 7 national natural science foundation projects. SAST is also granted 27 national invention patents.

Backed by the supports from the university and funds from the research projects, the construction of the research platforms follows the idea of “joint development, resource sharing, and mutually benefit”. SAST further strengthens its corporation with the research institutes in jointly constructing the laboratories, applying the state major technological projects, and promoting the work-study combination.

Some acadimic research activities and achievements:

Plasma Sheath Simulation and Continuous Radio Blackout Reproducing System: We built a novel plasma generator that offers large scale, continuous, non-magnetized plasma with a 30-cm-diameter hollow structure, which provides a path for an electromagnetic wave. The plasma is excited by a low-pressure glow discharge, with varying electron density range from 10e9 to 2.510e11 cm-3. It can reproduce a continuous radio blackout in UHF, L- and S-bands. The results are consistent with theoretical expectations. This system is suitable in simulating a plasma sheath, and researching communications, navigation, electromagnetic mitigations, and antenna compensation in plasma sheaths.

Energy Harvesting Technology: We have prototyped several low-power wireless sensors powered by environment energy, such as thermo energy, radio broadcast energy, or vibrations. The critical technologies include exploration of novel energy sources, high efficient energy converting, and ultra low voltage boost circuits. The testing results indicated that the harvested energy in most daily surroundings is sufficient to drive a basic wireless sensor operating in sleep/wakeup mode, and the stability and continuity of harvested energy may superior to solar energy.

Heavy Duty Wireless Power Transmitting Technology: We have proposed a novel wireless power transmitting structure that offers heavy power (more than 1kW) while maintaining slim(less than 1cm) and small in size. The total efficient reaches up to 90%, supporting stitching and curved shape installation. This technology can be widely applied in powering heavy duty moving parts, such as drive shaft, robot, oil drilling .

Image processing based on visual perception: The integration modeling theory of biological visual system was proposed. Under this framework, a series of novel content representation and feature extraction algorithms were designed and successfully applied in small target recognition and tracking, image retrieval and coding, electronic image stabilization, multimedia secure communication, data fusion and panoramic image mosaicing, etc. Experiments show our work has basically solved the specific target detecting and efficient coding problems in complex environment.

Computation intelligence and parallel optimization algorithms: Novel multi-sub-swarm swarm intelligence framework was proposed. Under this framework, ecological r/K selection inspired optimization algorithm and Lotka-Volterra Model based optimization algorithm were designed and successfully applied in super-resolution imaging, image retrieval, robot path planning and large-scale medical image analysis, etc. A series of optimal parameter selection method were given for engineering problems, which can improve the solution quality significantly.

Computational imaging and non-invasive measurement technology: Computational imaging framework based on electronic and optical characteristics was established. Electric resistance tomography and electric capacitance tomography are two kinds of non-invasive measurement technology mainly studied. Using parallel computing technology and intelligent optimization technology, we succeeded in the quantitative measurement of the industrial two-phase flow. Our work can provide new solutions for detection of buried objects and exploration of the oil and gas resources.

X-ray Pulsar-based Technologies and Its Applications on the Autonomous Navigation Positioning: Aiming at solving the critical and burning problems emerged in the BeiDou Navigation Satellite System and the deep space exploration, we conducted a pulsar photon stream simulation based on the semi-conductor laser unit and designed a navigation experimental system. We proposed three novel methods, i.e., a high precision time of arrival (TOA) method for measuring the weak signal, a rapid X-ray pulsar-based navigation method for reducing the ambiguity in the whole cycle, and a method for detecting the weak pulsar signal in real time. Based on the technologies of FPGA real time detection and the multi-feature augmentation, we designed and implemented the X-ray pulsar-based autonomous navigation system. Our research on this area reached the international advanced level and our achievement is of great application significance to the field of the deep space exploration and the interplanetary autonomous navigation. Our achievements are honored by the second class prize of Shannxi Provincial Science and Technology Progress Award in 2013.

Technologies of Target Detection, Target Tracking and Data Fusion: Supported by the research grants from dozens of research projects including the pre-research project, the demonstration verification project, the innovation funds and the engineering application project, a video-based multi-sensor data fusion method is proposed and has been applied to the information fusion system in a maneuvering multi-platform environment. In China, we are the first one proposing the theory and its implementations on utilizing the multi-resolution theory for the multi-target tracking and the data fusion. We have also applied the theory to the field of modern radar engineering. Furthermore, we have combined the system simulation with the data fusion technology in the practical command and control system. To optimally distribute and manage the sensor resources in a heterogeneous multi-sensor environment, we proposed a novel information fusion method and designed a target threat estimation algorithm based on the application scenarios such as radar, infrared, ESM, laser alarm, target tracking and target pointing. All of our proposed techniques have been applied into practice successfully. Compared with other state-of-the-art technologies (both domestic and international) focusing on the same research field, our work maintains its superiority and has a great potential for future sensor applications.

High Sensitivity Satellite Navigation Signal Capturing in the Multi-Mode and Anti-Interference Environment: To satisfy the urgent requirement for capturing the multi-mode satellite signal with high sensitivity under the complex electromagnetism surroundings such as indoor, city and battlefield, two frequency deviation estimation methods with high precision are proposed. The proposed methods are utilized in the joint acquisition of the code phase and the Doppler frequency deviation. The methods established a detection performance model to analyze the joint acquisition of the code and Doppler in theory. Based on the Discrete Cosine Transform (DCT), a transform domain filtering method for the code acquisition is proposed. Both the analytical and simulation results show that, our proposed methods can significantly increase the detection probability. Furthermore, an interference cancellation algorithm with low computational complexity is proposed. The design of the algorithm is based on the fact that in canceling the interference of weak signal, only the frequency deviation around the integer kHz needs to considered. The algorithm can effectively increase the probability to detect the weak signal. To capture the radio frequency signal with high sensitivity, we designed a receiver based on the discrete elements and developed the corresponding multi-mode GNSS receiver. Finally, we designed the multi-array-source compatible high-gain antenna. We also developed a platform for signal receiving and processing in a general navigation system. So far, part of our research findings has already been applied to the teaching experiments and the engineering projects. The results have proved that our proposed technologies perform well in practice.