System Engineering Research Institute
System Engineering Research Institute
Chen Y.,Beijing Institute of Technology |
Zheng M.,Beijing Institute of Technology |
Liu X.,Beijing Institute of Technology |
Bi Y.,CAS Beijing Institute of Acoustics |
And 4 more authors.
Physical Review B | Year: 2017
The application of transformation theory to underwater acoustics has been a challenging task because highly anisotropic density is unachievable in water. A possible strategy is to exploit the anisotropic modulus rather than density, although it has not been experimentally demonstrated. We present an annular underwater acoustic cloak designed from particular graded solid microstructures. The geometry tailored microstructures mimic metafluid with highly anisotropic modulus through substantially suppressed shear waves. Transient wave experiments are conducted with the cloak in a designed two-dimensional underwater waveguide system and proved excellent cloaking performance for an enclosed target over broadband frequencies 9-15 kHz. This finding paves the way for controlling underwater acoustics using the structured anisotropic modulus metafluid. © 2017 American Physical Society.
Xu T.,System Engineering Research Institute |
Yang C.,System Engineering Research Institute |
Cai B.,System Engineering Research Institute |
Zhu Y.,System Engineering Research Institute
2016 IEEE International Conference on Signal and Image Processing, ICSIP 2016 | Year: 2017
Landing aerial crafts, such as helicopters, on the board of naval vessels of small or medium size is a difficult and risky task for pilots since the tonnages are not large enough which makes the ships always swinging along with ocean waves. Thus the landing areas are moving all the way with six degrees of freedom randomly. Even, this mission will become dangerous and deadly when the weather is stormy. Here, we design a real-time and automatic position sensing system to track, locate and help a helicopter to land on deck safely under all weather conditions. For the sake of practical application, we have not only adopted some ready and mature computational technologies from image processing, photogrammetry and computer vision, but also chosen some simple but effective optical elements to reduce the computational complexity. The system is composed of camera units, image-processing unit, controlling system and fiber optical communication unit. Experimental results show our system is capable of all-weather, real-time, robust and automatic landing mission. © 2016 IEEE.
Deng Y.,System Engineering Research Institute |
Wang X.,Tsinghua University |
Wang J.,Tsinghua University |
Wang J.,Tsinghua National Laboratory for Information Sciences and Technology
IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, BMSB | Year: 2016
Recently, some orthogonal multiple access schemes are utilized in return channels. However, in the field of wireless communication, as the number of users increases, the orthogonal resources are difficult to meet the explosive demand of access. For this reason, some non-orthogonal multiple access (NOMA) schemes have been proposed to solve the key problem of massive connectivity. In this paper, we adopt the low-density spreading orthogonal frequency division multiplexing (LDS-OFDM) scheme, in which message passing algorithm (MPA) based multi-user detection (MUD) has been utilized to eliminate the interference between different subcarriers belong to different users. Then we propose an optimal reference signal design scheme based on compressive sensing methods for user activity detection. In simulation, we analyze the mean square error (MSE) and bit error rate (BER) performance of the proposed optimal reference signal and a random reference signal. The simulation results demonstrate that the proposed scheme performs better than the random one. © 2016 IEEE.
Jia X.,Beihang University |
Wu S.,Beihang University |
Sun J.,System Engineering Research Institute
Chinese Control Conference, CCC | Year: 2014
Over the past few years, multi-agent coordination and control solutions have been applied to many challenging civilian and defense applications: surveillance, search and rescue, and fire monitoring. The existing multi-UAV dynamic task allocation method needs long computation time and does not apply to hard real-time and uncertain environment conditions. A relatively simple coordination mechanism was designed in this paper in an attempt to solve the problem that exists in the multi-agent systems method. Only with three times of information exchanges, the UAVs can enter their own flight modes, and this avoids the frequent communication problems between the UAVs. What's more, the UAV guidance law was designed, and the task allocation strategy and vehicle's coupling and temporal correlation are combined in this paper in order to verify the feasibility of the dynamic task allocation strategies in a dynamic process. Digital simulation was performed in two scales of UAV formation in order to compare the new task allocation method with the existing methods. © 2014 TCCT, CAA.
Feng Y.,Tsinghua University |
Fan W.,Tsinghua University |
Qin Y.,System Engineering Research Institute
Communications in Computer and Information Science | Year: 2013
In this paper, we built simulation model of the production line from one car engine parts plant in Beijing, in order to find proper solutions to raise productivity. The method of Discrete Event Simulation was used to construct the simulation model on account of the fact that production line was a typical discrete event system. Besides, worker heterogeneity, stochastic environment and the effect of worker learning and forgetting were introduced into simulation model to make it closer to reality. We proposed different schedule policies to manage the running of production line with the verification from simulation experiments. Then, by taking advantage of the simulation results obtained previous, we built the optimization model by applying Markov Decision Process (MDP) to seek for the best policy promoting the productivity of production line. © Springer-Verlag Berlin Heidelberg 2013.
Zhang L.,California Institute of Technology |
Zhang L.,Tsinghua University |
Zhang L.,System Engineering Research Institute |
Cui T.,California Institute of Technology |
And 2 more authors.
Signal Processing | Year: 2010
This paper considers the optimal power scheduling for the distributed estimation of a source parameter using quantized samples of noisy sensor observations in a wireless sensor network (WSN). Repetition codes are used to transmit quantization bits of sensor observations to achieve unequal error protection, and a quasi-best linear unbiased estimate is constructed to estimate the source parameter at the fusion center (FC). Based on the adopted distributed estimation scheme (DES), we optimize the power scheduling among sensors to minimize the L1-norm of the power vector subject to the desired tolerance, which implies minimizing the total transmission power. Since the optimization problem is not convex, we propose a low-complexity alternative, which minimizes the L2-norm of the power vector while insuring the desired tolerance. We derive the closed form solution of the L2-norm power scheduling scheme. Simulation results show that the total power consumption of the L2-norm power scheduling scheme is close to that of the L1-norm power scheduling scheme, while complexity analysis demonstrates that the L2-norm power scheduling scheme has very low complexity. © 2009.
Zhang X.,Xi'an Jiaotong University |
Chen X.,Xi'an Jiaotong University |
You S.,System Engineering Research Institute |
He Z.,Xi'an Jiaotong University |
Li B.,Xi'an Jiaotong University
Sensors | Year: 2012
In general, mechanical equipment such as cars, airplanes, and machine tools all operate with constant frequency characteristics. These constant working characteristics should be controlled if the dynamic performance of the equipment demands improvement or the dynamic characteristics is intended to change with different working conditions. Active control is a stable and beneficial method for this, but current active control methods mainly focus on vibration control for reducing the vibration amplitudes in the time domain or frequency domain. In this paper, a new method of dynamic frequency characteristics active control (DFCAC) is presented for a flat plate, which can not only accomplish vibration control but also arbitrarily change the dynamic characteristics of the equipment. The proposed DFCAC algorithm is based on a neural network including two parts of the identification implement and the controller. The effectiveness of the DFCAC method is verified by several simulation and experiments, which provide desirable results. © 2012 by the authors; licensee MDPI, Basel, Switzerland.
Yang J.,System Engineering Research Institute |
Li H.,System Engineering Research Institute
Proceedings of the 2012 4th International Conference on Intelligent Human-Machine Systems and Cybernetics, IHMSC 2012 | Year: 2012
In this paper, an Unmanned Aerial Vehicle (UAV) hardware-in-the-loop (HIL) simulation system based on a right-angle robot is proposed. It can verify the dynamic control, object detection, object tracking, object localization and image mosaic algorithms of the optical loads in experimental environment. With this simulation system the researchers can depend less on real UAV system and reduce the developing cost and risk greatly. The simulation results also can provide instructions to the real application. Copyright © 2012 by The Institute of Electrical and Electronics Engineers, Inc.
Yan G.-M.,Northwestern Polytechnical University |
Guo K.,System Engineering Research Institute |
Weng J.,Northwestern Polytechnical University |
Bai L.,Northwestern Polytechnical University
Zhongguo Guanxing Jishu Xuebao/Journal of Chinese Inertial Technology | Year: 2011
In traditional level-damped navigation system, an outside velocity measurement is taken as its reference. To avoid the noise's increasing in calculating velocity using differential position signal, some new gyrocompass control principles based on position error are deduced for the situation that position information is the only available data. Moreover, by combining with strapdown attitude equations, the position-damped strapdown inertial navigation algorithm is obtained. The proposed algorithm has the advantages of low computation burden and high stability. By contrasting to Kalman filtering for integrated navigation, its special application conditions and insufficiencies are pointed out. The vehicular test is carried out using GPS and laser SINS, and the results verify the effectiveness of this algorithm.
Liu Y.,Harbin Engineering University |
He Y.,Harbin Engineering University |
He Y.,System Engineering Research Institute |
Shang D.,Harbin Engineering University |
Sun C.,Harbin Engineering University
Shengxue Xuebao/Acta Acustica | Year: 2013
A high-resolution and high precision spherical array beamforming method for sound sources localization based on virtual sources algorithm is proposed. By means of the spherical array beam scanning, the focused spatial spectrum of actual sound sources can be obtained and each scanning point is assumed to be the virtual sound source. The actual sources focused spectrum is the result of focused beam output by the entire virtual sources, and then high precision sound source localization can be realized by calculating the contribution of each virtual source to the sound field. Compared with the conventional methods, the performance of the proposed method under some influence factors, such as frequency, array aperture, sound field mode orders and ratio of signal to noise is analyzed. The simulation results show that this method is not limited by frequency and aperture of array, effectively reducing the spatial aliasing. The focused spatial spectrum indicates the higher resolution sound sources location and the stronger ability to suppress the fluctuation of the background noise.