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Liu Y.,Shanghai Maritime University | Yang C.,National Research Council Canada | Yang Y.,Nanjing University | Lin F.,Athabasca University | And 2 more authors.
Applied Intelligence | Year: 2012

With the rapid development of case-based reasoning (CBR) techniques, CBR has been widely applied to real-world applications such as collision avoidance systems. A successful CBR-based system relies on a high-quality case base, and a case creation technique for generating such a case base is highly required. In this paper, we propose an automated case learning method for CBR-based collision avoidance systems. Building on techniques from CBR and natural language processing, we developed a methodology for learning cases from maritime affair records. After giving an overview on the developed systems, we present the methodology and the experiments conducted in case creation and case evaluation. The experimental results demonstrated the usefulness and applicability of the case learning approach for generating cases from the historic maritime affair records. © Springer Science+Business Media, LLC 2010.

Fang Z.-M.,Hefei University of Technology | Song W.-G.,Hefei University of Technology | Liu X.,China Academy of Building Research | Lv W.,Hefei University of Technology | And 2 more authors.
Physica A: Statistical Mechanics and its Applications | Year: 2012

A good evacuation model should be good to predict actual macroscopic and microscopic characteristics of pedestrian movement. In order to explore pedestrian movement behavior, we conducted controlled experiments of the single-file pedestrian movement, extracted the motion data by using a mean-shift digital image processing algorithm and analyzed the movement characteristics of pedestrians. It is found that both the pedestrian step length and frequency decreases with the increasing global pedestrian density. Furthermore, there is linear relationship between the step frequency and the distance headway of a pedestrian. Based on the characteristics observed from our experiments, we built a continuous distance model (CDM) for the single-file pedestrian movement. Two new insights were taken into account in the movement algorithm. The first one is that, the continuous step length is adopted to avoid unreasonable results caused by the simplification of the step length in traditional discrete models. The second one is that the dependency between the transition probability and the distance headway is introduced for the reason that the transition probability is correlated with the actual step frequency. Simulation results indicated that there is a close agreement on the flow-density and velocitydensity relations between the experiments and modeling. Moreover, it is found that the CDM model is capable of reproducing microscopic features for the scenario with high density. © 2011 Elsevier B.V. All rights reserved.

Fang Z.-M.,Anhui University of Science and Technology | Song W.-G.,Anhui University of Science and Technology | Li Z.-J.,Yin Chuan Municipal Fire Brigade of Chinese Peoples Armed Police Force | Tian W.,Anhui University of Science and Technology | And 3 more authors.
Building and Environment | Year: 2012

One of the most important emergency accesses in a multi-layer or high-rise building is stairwell, through which people can escape from the building in case of fire. Much attention has been paid to evacuation study in the stairwell by means of experiments or modeling. In this study, an evacuation experiment was conducted in a stairwell of an 8-layer high-rise building. The evacuation process in the stairwell was recorded by video cameras. Some typical movement characteristics and parameters were extracted based on the recording data. The results demonstrate that the downward velocity is determined by three aspects: merging behavior in the entrance buffer of the stairwell, strength of participants and visibility in the stairwell. The downward velocity measured in our experiment, about 0.81 m/s, is similar to that in the previous study. The relationship between velocity and density in our study agrees well with the function indicated in SFPE handbook. © 2011 Elsevier Ltd.

Teng Y.,Key Laboratory of Science and Technology on Underwater Acoustic Antagonizing | Fan W.,Shanghai Marine Electronic Equipment Research Institute
Proceedings - 5th International Conference on Instrumentation and Measurement, Computer, Communication, and Control, IMCCC 2015 | Year: 2015

The characteristics of ship wake and a bubbles distribution model in ship wake were researched. According to the features of a vessel, a bubble distribution model in the vessel wake were simulated and then applied to predict sound propagation attenuation in ship wakes. Simultaneously, the vessel's wake was measured on a lake at range of frequency from 4kHz to 20kHz, which were analyzed to explore the performance of the presented model. The comparison results show that the void fraction of bubbles in the vessel's wake reach1.14×10-6, and the difference between the predicted attenuation and the measurements of sound propagation attenuation in the wake are less than 5dB/km, which agree well with experiment results. Thus, the bubble distribution model of ship wake can be used to research the acoustical characteristics in ship wake to overcome the data incompleteness. © 2015 IEEE.

Li Y.-Q.,Shanghai Marine Electronic Equipment Research Institute | Zheng Y.-K.,Shanghai Marine Electronic Equipment Research Institute | Du X.-M.,Shanghai Marine Electronic Equipment Research Institute
2016 IEEE/OES China Ocean Acoustics Symposium, COA 2016 | Year: 2016

This paper describes the definition of the weak signal that is frequently encountered in the field of underwater acoustics. It describes the basic methods of hydro-acoustic weak signal detection techniques and improved methods, such as narrow band filtering, the method of correlation detection, sampling integration, for an improved phase-lock amplifier. We give a detailed explanation of the beamforming theory of sonar, and the weak signal detection theory of stochastic resonance, frequency-domain harmonic wavelet extraction and chaotic oscillator weak signal detecting. Finally, we give a brief description of how we compared all the typical methods. This paper aims to enable readers to understand the past and present hydro-acoustic weak signal processing methods of the field, and contribute to the development of underwater acoustic signal processing. © 2016 IEEE.

Yangze D.,Shanghai Marine Electronic Equipment Research Institute | Liu P.,Shanghai Marine Electronic Equipment Research Institute
OCEANS 2013 MTS/IEEE Bergen: The Challenges of the Northern Dimension | Year: 2013

Owing to the severe environment, underwater communication is far difficult to realize than in other media. Thus limits many applications, such as real time information transmission. Fortunately, there is some other compensation to be performed to accomplish the work. This paper introduces an underwater acoustic image on demand system, in which data compression technique is used to realize real time image transmission. In the system, binary images are transmitted on demand. Though the images are binary with only black pixels, it is hard to transmit all data in real time. ISO standard JBIG-1 is selected to perform data compression. Simulations are accomplished to verify the feasibility of compression. © 2013 IEEE.

Dong Y.,Shanghai Marine Electronic Equipment Research Institute | Liu P.,Shanghai Marine Electronic Equipment Research Institute
2011 IEEE International Conference on Information and Automation, ICIA 2011 | Year: 2011

Security is one of the ultimate goals of Underwater Acoustic Networks. The security considerations must be carried out during the construction of the network. But at the worst conditions, the network may be destroyed by adverse attacks. It must be restored in some extents for continuous usage. © 2011 IEEE.

Li S.,Shanghai Marine Electronic Equipment Research Institute
Proceedings - 2011 2nd International Conference on Innovations in Bio-Inspired Computing and Applications, IBICA 2011 | Year: 2011

Sparse arrays are popular in sonar, ultrasonic imaging and other acoustic equipment. For inter-element spacing larger than one wave length, there will be grate lobes for ordinary sparse array. Using genetic algorithm to optimize array with randomly spaced elements to suppress the grate lobes is introduced in this paper. Fitness function design and variable choosing method for genetic algorithms application in this kind of objects are presented. A single object fitness function instead of multi objects fitness function usually used for array design is proposed. © 2011 IEEE.

Li S.W.,Shanghai marine electronic equipment research institute
Applied Mechanics and Materials | Year: 2014

Parametric acoustic receiving array has the advantage of achieving high directional index for low frequency signals with very simple sensor arrangement. This characteristic is suitable for vehicle radiated noise measurement in costal area and in the far field of the target vehicle. This paper gives a design for such application of parametric acoustic receiving array with the calculation of possible ability that can be achieved. © (2014) Trans Tech Publications, Switzerland.

He X.,Science and Technology on Underwater Acoustic Antagonizing Laboratory | He X.,Shanghai Marine Electronic Equipment Research Institute
AIP Conference Proceedings | Year: 2012

The interior acoustic field of a dome is focused as a column below the domes when the source is located at half of the radius of the dome. This paper investigates the sound field reflected by a concave spherical surface from a source which on the axis of the spherical surface. The formula for calculating the field have been given, which the sound beam constrict to a point which locate at the centre of the concave when θmax=90°, and There would be a sound beam while the θmax<90°, but it works nearly. © 2012 American Institute of Physics.

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