A new algorithm is proposed in this paper to recognize and classify underwater acoustic signals including underwater acoustic communication signals, active sonar signals, ship-radiating noise and burst ocean ambient n...
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A new algorithm is proposed in this paper to recognize and classify underwater acoustic signals including underwater acoustic communication signals, active sonar signals, ship-radiating noise and burst ocean ambient noise. The paper firstly analyzed the features of underwater acoustic signals in time domain, frequency domain and cyclostationarity domain. At the same time, the way of extracting features about these signals is researched. This algorithm combines the features above and chooses a decision tree classifier to realize the recognition and classification of different underwater acoustic signals. Finally, the effectiveness in different multipath channels is evaluated by simulation. The results have shown that this algorithm is capable of recognizing and classifying different underwater acoustic signals with better performance than algorithms using features in only one domain; and, its performance is robust in a multipath fading environment.
The tree-like structure is a common structure, which is used in many projects. Queries based on tree's attributes and queries based on node's attributes are the two frequently used query's patterns. Howeve...
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ISBN:
(纸本)9781509047963
The tree-like structure is a common structure, which is used in many projects. Queries based on tree's attributes and queries based on node's attributes are the two frequently used query's patterns. However, the existing storage models don't support both of them efficiently. In this paper, we propose a hybrid storage model, which stores nodes and relations between nodes separately, and we also build the inverted index between nodes and trees. The experiment results show that the hybrid storage model is more efficient than the existing models.
The electrodynamic properties of a symmetric slot line with a dielectric insert are investigated. A numerical analysis of the transmission line is performed using the finite element method. The dispersion matrix eleme...
The electrodynamic properties of a symmetric slot line with a dielectric insert are investigated. A numerical analysis of the transmission line is performed using the finite element method. The dispersion matrix elements of the transmission line are presented. It is shown that the model of a symmetric slot line with a dielectric insert can extend the operating frequency band more than 2 times.
Using high precision laser ephemeris as reference, the precision of orbit prediction is analyzed of an analytical model which is formulated by quasi-analytical average method. The result shows that: the orbit predicti...
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ISBN:
(纸本)9781510830363
Using high precision laser ephemeris as reference, the precision of orbit prediction is analyzed of an analytical model which is formulated by quasi-analytical average method. The result shows that: the orbit prediction accuracy of MEO and LEO satellites is several hundred meters in 1 day and not more than 10 km in 7 days. The position error changes quickly over time. The calculation speed is fast using the analytical model. It can be used for precise orbit determination for a short term about 1 or 2 days. And it also can be used for the general accuracy of the long-term orbit prediction. But if the prediction time is too long, the accuracy will drop sharply.
This paper focus on the subgraph isomorphism (SI) problem. We present an improved genetic algorithm, a heuristic method to search the optimal solution. The contribution of this paper is that we design a dedicated cros...
This paper focus on the subgraph isomorphism (SI) problem. We present an improved genetic algorithm, a heuristic method to search the optimal solution. The contribution of this paper is that we design a dedicated crossover algorithm and a new fitness function to measure the evolution process. Experiments show our improved genetic algorithm performs better than other heuristic methods. For a large graph, such as a subgraph of 40 nodes, our algorithm outperforms the traditional tree search algorithms. We find that the performance of our improved genetic algorithm does not decrease as the number of nodes in prototype graphs.
This paper presents two algorithms to recover LDPC codes in an error-free environment. Both algorithms reconstruct the sparse parity-check matrices of LDPC codes based on elementary row transformation, and are equival...
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The spatial correlation of target echoes is important to jointly process signals received at each radar substation in distributed radar system. On the background of space surveillance with two independent monostatic r...
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ISBN:
(纸本)9781785610387
The spatial correlation of target echoes is important to jointly process signals received at each radar substation in distributed radar system. On the background of space surveillance with two independent monostatic radars, a three-dimensional cylinder target scattering model and echo signal model are built combined the orbital motion. The echoes spatial correlation is analysed and correlation coefficient which varies with the included angle between two radars and target is derived. The reasonableness of target scattering model and validity of theoretical analysis are proved via simulation examples.
Distributed passive radar imaging has been an emerging topic in radar imaging society because of its low-cost, increased-survivability and robustness. In the inverse problem of distributed passive imaging, location of...
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Distributed passive radar imaging has been an emerging topic in radar imaging society because of its low-cost, increased-survivability and robustness. In the inverse problem of distributed passive imaging, location of receivers affects imaging quality a lot, while illuminators of opportunity remain to be uncontrollable. Therefore, we investigate the problem of receiver disposition optimization and propose the optimal scheme to locate those receivers by combining genetic algorithm(GA) with compressive sensing(CS) based imaging technique. Simulation results validate the effectiveness of the proposed algorithm.
Recently, multidimensional scaling (MDS) algorithms have been verified to be robust for the emitter localization. However, the traditional MDS algorithms are based on single one kind of measurement. In this paper, a n...
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This paper presents the Cramer-Rao Bound (CRB) of time-difference-of-Arrival (TDOA) estimation for frequency-hopping (FH) signals, which has still not been reported in the open literature. The CRBs are derived in clos...
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