National Key Laboratory of CNS ATM

Beijing, China

National Key Laboratory of CNS ATM

Beijing, China
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Cai K.-Q.,Beihang University | Cai K.-Q.,National Key Laboratory of CNS ATM | Yu L.,Beihang University | Yu L.,National Key Laboratory of CNS ATM | And 2 more authors.
Modern Physics Letters B | Year: 2017

In this paper, a hybrid queuing strategy (HQS) is proposed in traffic dynamics model on scale-free networks, where the delivery priority of packets in the queue is related to their distance to destination and the queue length of next jump. We compare the performance of the proposed HQS with that of the traditional first-in-first-out (FIFO) queuing strategy and the shortest-remaining-path-first (SRPF) queuing strategy proposed by Du et al. It is observed that the network traffic efficiency utilizing HQS with suitable value of parameter h can be further improved in the congestion state. Our work provides new insights for the understanding of the networked-traffic systems. © 2017 The Author(s).

DAI W.,Beihang University | ZHANG J.,National Key Laboratory of CNS ATM
Chinese Journal of Aeronautics | Year: 2017

Multi-commodity flow problems (MCFs) can be found in many areas, such as transportation, communication, and logistics. Therefore, such problems have been studied by a multitude of researchers, and a variety of methods have been proposed for solving it. However, most researchers only discuss the properties of different models and algorithms without taking into account the impacts of actual implementation. In fact, the true performance of a method may differ greatly across various implementations. In this paper, several popular optimization solvers for implementations of column generation and Lagrangian relaxation are discussed. In order to test scalability and optimality, three groups of networks with different structures are used as case studies. Results show that column generation outperforms Lagrangian relaxation in most instances, but the latter is better suited to networks with a large number of commodities. © 2017 Chinese Society of Aeronautics and Astronautics.

Jin K.,Aviation Data Communication Corporation | Jin K.,National Key Laboratory of CNS ATM | Zhu Y.,Aviation Data Communication Corporation | Zhu Y.,National Key Laboratory of CNS ATM | And 3 more authors.
Beijing Hangkong Hangtian Daxue Xuebao/Journal of Beijing University of Aeronautics and Astronautics | Year: 2017

Aimed at the accurate evaluation of the altimetry system error for the automatic dependent surveillance-broadcast (ADS-B) height keeping performance monitoring, a data smoothing and fitting analysis method based on the kernel smoothing and mixed-Gaussian distribution was proposed. The kernel smoothing method for improving the resolution of the height data in the ADS-B messages was proposed. The optimal bandwidth of the data smoothing was analyzed. The analysis using real data demonstrates that this error evaluation method of the altimetry system is effective. To solve the problem that the two independent altimetry systems of an aircraft have different height keeping performance distribution characteristics, the fitting method based on the mixed-Gaussian distribution was proposed. The analysis using real data demonstrates that this method can accurately describe the double split peak characteristic of the aircraft altimetry system error. The proposed methods have been used in the analysis of Chinese RVSM aircraft height keeping performance. Evaluation results follow the requirements of International Civil Aviation Organization. © 2017, Editorial Board of JBUAA. All right reserved.

Zhang X.-J.,Beihang University | Zhang X.-J.,National Key Laboratory of CNS ATM | Guan X.-M.,Beihang University | Guan X.-M.,National Key Laboratory of CNS ATM | And 3 more authors.
Communications in Theoretical Physics | Year: 2013

In recent years, the transportation system has been faced by increasing challenge in congestion and inefficiency, and research in traffic network has become a significant area of interest. In this paper, we introduce a dynamic-information-based (DIB) queueing strategy into network traffic model under the efficient routing strategy. DIB makes a packet with higher priority to be delivered if there are less packets travelling along its path from the current node to the destination. It is found that, compared with the traditional first-in-first-out (FIFO) queueing strategy, DIB can effectively balance the traffic load of the system via delaying packets to be delivered to congested nodes. Although the network capacity has no obvious changes, some other indexes which reflect transportation efficiency are efficiently improved in the congestion state. Besides, extensive simulation results and discussions are provided to explain the phenomena. The results may provide novel insights for research on traffic systems. © 2013 Chinese Physical Society and IOP Publishing Ltd.

Wang Y.,National Key Laboratory of CNS ATM | Feng Y.,Queensland University of Technology | Li R.,National Key Laboratory of CNS ATM
24th International Technical Meeting of the Satellite Division of the Institute of Navigation 2011, ION GNSS 2011 | Year: 2011

The paper explores methods and algorithms used to generate, apply and validate covariance matrices of GPS orbits in the context of position solution. In general, the research of satellite orbit error is threefold. The first is covariance matrix generation of satellite orbit error which may include systematic orbit biases or sudden changes in the orbit solution. The next is to determine and test "Bad" satellites which have large orbit error with the highest probability. The third is to validate what integrity benefit can be obtained if orbit covariance matrices are considered in estimation of user positioning solutions. However, the existing integrity studies have not addressed these issues directly yet. The paper starts with a general description of a satellite integrity orbit monitoring problem and computing orbital covariance matrices from different orbital solutions in real time. Next the paper describes covariance propagations in the least square navigation solutions. The method to determine 'bad' satellites is then analyzed preliminarily. Experimental analysis with GPS orbits of several hours and several widely distributed ground GNSS stations are performed to demonstrate the proposed integrity concepts and determination algorithms. The results have shown that the effects of large broadcast orbital errors on the user solutions can indeed be effectively reduced by considering the orbital covariance matrices estimated.

Sun X.,Beihang University | Sun X.,National Key Laboratory of CNS ATM | Wandelt S.,Beihang University | Wandelt S.,National Key Laboratory of CNS ATM | And 2 more authors.
Chinese Control Conference, CCC | Year: 2016

In this study, we perform an empirical analysis of air transportation systems as networks of countries. We build three network variants based on worldwide ticket data from the year 2013 and identify patterns of air passenger flow between countries as induced by network centrality metrics. These metrics, understood as observables about countries, are then exploited to estimate the similarity of countries in the global network. We detect community structures and find that communities largely coincide with the continental division of the world. Our research contributes to a better understanding of international air passenger flow patterns and potential control mechanisms against natural or human intended disruptions. © 2016 TCCT.

Wang T.,Beihang University | Wang T.,National Key Laboratory of CNS ATM | Sun X.,Beihang University | Sun X.,National Key Laboratory of CNS ATM | And 2 more authors.
Chinese Control Conference, CCC | Year: 2016

Many real-world systems can be seen as complex networks, where nodes denote elements in the systems and links denote relationships between elements. Since most of the real-world systems are vulnerable under disruptions, it is necessary to perform research on network robustness. However, finding the optimal attack on networks is a NP-hard problem, thus many methods based on ranking certain network metrics are proposed, for their low computational time complexity. Although strategies can be obtained quickly according to the ranking methods, the quality of the strategies is unsatisfying, because no single metric can represent all the properties of a network. In this paper, we propose a ranking-free method to attack networks. The main idea of our method is to identify components, which are likely to be in the final network after attack. Our research targets a trade-off between expensive optimal attacks and fast ranking-based heuristics. The evaluations, both on random networks and real-world networks, show that our method behaves better than popular ranking methods. © 2016 TCCT.

Lei C.,Beihang University | Lei C.,National Key Laboratory of CNS ATM | Zhang J.,Beihang University | Zhang J.,National Key Laboratory of CNS ATM
Chinese Journal of Aeronautics | Year: 2012

The detection of sparse signals against background noise is considered. Detecting signals of such kind is difficult since only a small portion of the signal carries information. Prior knowledge is usually assumed to ease detection. In this paper, we consider the general unknown and arbitrary sparse signal detection problem when no prior knowledge is available. Under a Neyman-Pearson hypothesis-testing framework, a new detection scheme is proposed by combining a generalized likelihood ratio test (GLRT)-like test statistic and convex programming methods which directly exploit sparsity in an underdetermined system of linear equations. We characterize large sample behavior of the proposed method by analyzing its asymptotic performance. Specifically, we give the condition for the Chernoff-consistent detection which shows that the proposed method is very sensitive to the ℓ 2 norm energy of the sparse signals. Both the false alarm rate and the miss rate tend to zero at vanishing signal-to-noise ratio (SNR), as long as the signal energy grows at least logarithmically with the problem dimension. Next we give a large deviation analysis to characterize the error exponent for the Neyman-Pearson detection. We derive the oracle error exponent assuming signal knowledge. Then we explicitly derive the error exponent of the proposed scheme and compare it with the oracle exponent. We complement our study with numerical experiments, showing that the proposed method performs in the vicinity of the likelihood ratio test (LRT) method in the finite sample scenario and the error probability degrades exponentially with the number of observations. © 2012 Elsevier Ltd. All rights reserved.

Zhang X.J.,Beihang University | Zhang X.J.,National Key Laboratory of CNS ATM | Guan X.M.,Beihang University | Guan X.M.,National Key Laboratory of CNS ATM | And 4 more authors.
Science China Information Sciences | Year: 2013

Conflict resolution (CR) plays a crucial role in safe air traffic management (ATM). In this paper, we propose a new hybrid distributed-centralized tactical CR approach based on cooperative co-evolutionary named the CCDG (cooperative co-evolutionary with dynamic grouping) strategy to overcome the drawbacks of the current two types of approaches, the totally centralized approach and distributed approach. Firstly, aircraft are divided into several sub-groups based on their interdependence. Besides, a dynamic grouping strategy is proposed to group the aircraft to better deal with the tight coupling among them. The sub-groups are adjusted dynamically as new conflicts appear after each iteration. Secondly, a fast genetic algorithm (GA) is used by each sub-group to optimize the paths of the aircraft simultaneously. Thirdly, the aircraft's optimal paths are obtained through cooperation among different sub-groups based on cooperative co-evolutionary (CC). An experimental study on two illustrative scenarios is conducted to compare the CCDG method with some other existing approaches and it is shown that CCDG which can get the optimal solution effectively and efficiently in near real time, outperforms most of the existing approaches including Stratway, the fast GA, a general evolutionary path planner, as well as three well-known cooperative co-evolution algorithms. © 2013 Science China Press and Springer-Verlag Berlin Heidelberg.

Su J.,Beihang University | Su J.,National Key Laboratory of CNS ATM | Zhang X.,Beihang University | Zhang X.,National Key Laboratory of CNS ATM | And 2 more authors.
Lecture Notes in Electrical Engineering | Year: 2013

Conflict resolution becomes a worldwide urgent problem to guarantee the airspace safety. The existing approaches are mostly short-term or middle-term which obtain solutions by local adjustment. 4D-Trajectory conflict resolution (4DTCR), as a long-term method, can give better solutions to all flights in a global view. 4DTCR involved with China air route network and thousands of flight plans is a large and complex problem which is hard to be solved by classical approaches. In this paper, the cooperative coevolution (CC) algorithm with random grouping strategy is presented for its advantage in dealing with large and complex problem. Moreover, a fast Genetic Algorithm (GA) is designed for each subcomponent optimization which is effective and efficient to obtain optimal solution. Experimental studies are conducted to compare it to the genetic algorithm in previous approach and CC algorithm with classic grouping strategy. The results show that our algorithm has a better performance. © 2013 Springer-Verlag.

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