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IEEE

OCEANS’16 Shanghai

Student Poster Competition, OCEANS’16 MTS/IEEE SHANGHAI

Philippe Courmontagne, Student Poster Contest Committee Chair,

Photos by Stan Chamberlain

This 38th Student Poster Program of the OCEANS Conferences was held at OCEANS’16 MTS/IEEE Shanghai, at the Shanghai International Convention Center & Oriental Riverside Hotel, from April 10 to April 13. The program was organized by Dr. Ye Li (Shanghai Jiao Tong University) as local coordinator and Philippe Courmontagne, SPC Chair, from IEEE OES.

For this edition, more than 100 abstracts were received and 17 were selected for this contest, not without difficulty given the high quality of the received abstracts, only 14 students were able to attend the conference. Students came from Brazil, Canada, China, France, Japan, Korea, Portugal, Spain, Taiwan and the United States.

The posters were on display in the Exhibition Hall. As for the previous Student Poster Competitions, outstanding posters describe the work that the students were presenting and were particularly appreciated by the attendees of the conference. Moreover, the student participants greatly appreciated the opportunity to display, exchange and describe their research work to the community.

The posters were judged by a team organized by IEEE OES and the local chair. The roster of students and their schools are (in order of appearance of the Program Book):

l Guang Chen, Shanghai Jiao Tong University

l Wei-Kuo Yen, National Taiwan University

l Taijie Luo, South China University of Technology

l Kai Huang, Zhejiang University

l José Melo, Faculty of Engineering, University of Porto

l Oriol Pallares Valls, SARTI-UPC

l Junjun Cao, State Key Laboratory of Ocean Engineering, Institute of Technology, Shanghai Jiao Tong University

l Amanda Duarte, Federal University of Rio Grande

l Jing Hao, Graduate School at Shenzhen, Tsinghua University

l Jonghyun Ahn, Kyushu Institute of Technology

l Redouane Lguensat, Telecom Bretagne

l Yali Wang, Memorial University of Newfoundland

l Jungwook Han, KAIST

l David R. Silver, United States Naval Academy

The judging was completed by noon on Wednesday and the prizes were awarded during the Wednesday’s lunch. Dr. Ye Li opened the awards ceremony and presented, with Philippe Courmontagne, each student with a Certificate of Participation in the OCEANS’16 MTS/IEEE Shanghai. Then, Philippe Courmontagne presented the third place winner to Jungwook Han, from Korea. Next, Andrew Clark, MTS Vice President for Industry and Technology, presented the second prize to Jonghyun Ahn, from Japan. The first price, the “Norman Miller’s Prize”, has been presented by René Garello, IEEE OES President, to Redouane Lguensat, from France, for his poster entitled “Using Archived Datasets for Missing Data Interpolation in Ocean Remote Sensing Observation Series”. In addition, for this contest, three special prizes “the OCEANS’16 Shanghai” prizes, have been put in place: two special third prizes, presented by Ye Li to Oriol Pallares, from Spain and to Yali Wang, from Newfoundland, .and one special second prize, presented by Wen Xu, the Technical Program Chair, to Jolé Melo, from Portugal.

The audience gave the students a big hand following the awards presentations. The session ended with a photograph session.

The awards ceremony

The roster of students and their poster titles are given below with an abstract of their paper.

 

Guang Chen, Shanghai Jiao Tong University

Investigation of free surface flow in wedge water entry problem using Smoothed Particle Hydrodynamics method

Wedge water entry problem is investigated and induced free surface flow problem is studied through Smoothed Particle Hydrodynamics (SPH) method. Firstly, the SPH model is introduced briefly, including numerical approximation, the discretized governing equations, boundary treatment and time stepping algorithm. Then the SPH method is validated by experimental results for further investigations. Afterwards, several wedge water entry cases are tested. The displacement, velocity and dimensionless acceleration of the wedge were quantitatively

analyzed. Furthermore, motion of the free surface is gotten, and results show that water particles on free surface will move near the free surface during the simulation process. Lastly, splashed out particles are examined. It is found that these particles are almost coming from one fixed region, a w-shape like region. It is proven that SPH method is good to simulate free surface flow problems.

 

Wei-Kuo Yen, National Taiwan University

Wall Following Control of a Robotic Fish using Dynamic Pressure

This work controlled a robotic fish swimming alongside a wall. Research shows that fish swimming alongside a wall use lateral lines to obtain nearfield information. This concept is also applicable in man-made underwater vehicles such as robotic fish, which mimic the swimming action of a fish. Pressure sensors on the surface of a robotic fish measure hydrodynamic pressure variation. According to two-dimensional potential flow theory and the image method, the pressure variation caused by a robotic fish swimming near a wall is related to the relative angle and distance between the robot and the wall. Thus, the pressure signals can be used as feedback and inputs for controlling the direction in which the robot swims. The experimental results of this study show that a robotic fish 90 cm long can swim alongside a straight wall approximately 30-40 cm away (0.33-0.44 body length, 1-1.33 tail fin height). This method can also be combined with a well-designed strategy for using a robotic fish to swim next to an underwater structure to inspect details of structure parts.

 

Taijie Luo, South China University of Technology

Cramér-Rao Bounds of Source Localization with Distributed Sensors in Underwater Multipath Environment

In this paper, the Cramér-Rao lower bounds (CRLB) and the maximum likelihood estimator (MLE) are derived for estimating the underwater source location. An underwater source, four distributed underwater receivers with known location and time synchronization between source and receivers are assumed. If the reflecting geometry is known and the multipath is detectable and resolvable, it is shown that with exploiting the multipath information, the accuracy of source location estimation can be improved. Numerical examples are presented to illustrate the behavior of these bounds.

 

Kai Huang, Zhejiang University

Sequential Filtering Applied to Multi-Beam Echo-Sounding

A precise ocean bottom map is often desired for ocean surveying. To meet the demand, the multi-beam echo sounder (MBES) has been developed and commonly used. An MBES usually forms multiple receiving beams across-track first, then determines the bottom echo time for each beam, and finally calculates depth from echo time and direction. In this paper, a sequential filtering approach, exploiting ping to ping data correlation, is proposed, which is capable of realizing fast and accurate estimation and tracking of the seafloor depth. By the employment of this method, when the measurement Signal-Noise-Ratio (SNR) is below 35dB, the root mean square error (RMSE) of depth estimation is much lower than the conventional approach, and nearly reaches the posterior Cramer–Rao lower bound. The results demonstrate that the sequential filtering approach, applied to MBES measurements, could be a promising technique for seafloor topography estimation and tracking.

 

José Melo, Faculty of Engineering, University of Porto

Towards LBL Positioning Systems for Multiple Vehicles

In this article we discuss the use of LBL acoustic networks for operations with multiple AUVs. Differently from standard LBL configurations, we propose to use the One-Way-Travel-Time of acoustic signals to compute the ranges between all the devices. Moreover, we derive the suitable algorithms for both the navigation of multiple vehicles, but also their external tracking. Experimental results are provided that support the evidence that our approach is successful in operations for multiple vehicles.

 

Oriol Pallares Valls, SARTI-UPC

Time Synchronization Accuracy Refinement for Mobile Shallow Water Acoustic Sensor Network

Time synchronization is an important factor to take into account when performing collaborative and distributed tasks along a sensor network. Message exchange based time synchronization algorithms ported to underwater acoustic sensor networks, have to deal with high latency communications, besides frame Doppler scaling and frame detection at the receiver side, which are key points for an accurate synchronization. Furthermore, mobile sensor networks lead to different propagation times in a bidirectional message exchange, such as the ones used to synchronize two sensors. In addition to time synchronization algorithm, a first order kinematic model in conjunction with Doppler estimation can be applied to precise frame time stamping and avoid drift between clocks.

In this paper we present a complete time synchronization scheme optimized for mobile network, tested in simulation and experimented in real tests demonstrating high performance in time synchronization accuracy.

 

Junjun Cao, State Key Laboratory of Ocean Engineering, Institute of Technology, Shanghai Jiao Tong University

Seagull-Designed for Oceanographic Research

Seagull is a small fully functional underwater glider designed for oceanographic research with 1 knot operating speed and six months duration. In this paper, we present the design of this glider and analyze its performance. The Seagull glider uses a piston-based buoyancy engine system with an inexpensive gear pump as the main system actuator. The Seagull’s emergency release system is characterized for low power consumption. Towing experiments are performed to measure the accurate hydrodynamic coefficients of the glider. The operation of Seagull and the results of field trials in Qiandao Lake are reported.

 

Amanda Duarte, Federal University of Rio Grande

A Dataset to Evaluate Underwater Image Restoration Methods

Image restoration methods have been made to repair images that have some kind of degradation. Most of these methods are designed to deal with the degradation caused by the over-land effects. However, when the images was captured in underwater environments, there are different properties that can degrade the image in unusual ways. This work aims to evaluate how the popular image restoration methods behaves when applied in underwater images with the presence of turbidity in the water. For this, we propose a dataset where we are able to control the amount of image degradation due to underwater properties on a scenario with 3D objects that represents the seabed characteristics. After that, we evaluate the restoration of these methods and their behavior through the image degradation due to turbidity.

Jing Hao, Graduate School at Shenzhen, Tsinghua University

Saliency Segmentation and Foreground Extraction of Underwater Image based on Localization

Saliency detection aims at automatically estimating visually salient object regions in an image, saliency segmentation and foreground extraction are two important applications of this. However, it is a challenge for underwater images to estimate salient regions by conventional saliency detection methods because of the low-contrast and poor quality. In this paper, we address this problem by combining the detected object regions rather than the whole image, where Fish Localization is used for proposing candidate regions. We extensively evaluated our method on 780 underwater images, and experimental results show that the performances of saliency detection and segmentation are improved. These saliency segmentation masks are further used to extract the foreground objects of an image. It is well proved that our approach is fast and efficient for underwater images which are low-contrast, poor quality and with multiple salient objects.

 

Jonghyun Ahn, Kyushu Institute of Technology

Image Enhancement and Compression of Deep-Sea Floor Image for Acoustic Transmission

One of the important missions of AUVs is to take deep-sea images and make maps of sea floor to contribute the understanding of deep-sea biology and geology. The sea floor images include lots of information such as distributions of creatures, minerals and so on. The next mission expected for AUVs is to bring the samples back concurrently with taking interesting photos, autonomously. However, this mission is difficult to perform fully-autonomous without the knowledge of biologists or geologists, as the AUVs don’t know which objects are interesting or important for them and it takes long time to teach AUVs all features of target samples. It is necessary for AUVs to work semi-autonomously by collaborating with scientists on the ship and getting commands to indicate the important samples. In this research, we proposed an image enhancement and compression method for acoustic transmission with limited communication density. The proposed method enhances the effect of light attenuation in the deep-sea floor image and reduces the image depth from 24-bit of original images to 4-bit. The method is evaluated by transmission experiment using a new AUV “TUNA-SAND 2”.

 

Redouane Lguensat, Telecom Bretagne

Using Archived Datasets for Missing Data Interpolation in Ocean Remote Sensing Observation Series

The proliferation of data coming in daily from ocean remote sensing observational networks is getting bigger and will likely to get a lot bigger. This fact makes it natural to search for methods and strategies that can make the best use of this wealth of information. In this work, we investigate the utility of historical datasets to missing data interpolation issues. We state missing data interpolation as a data assimilation issue and present a data-driven strategy for the reconstruction of missing data in remote sensing observations series. Our data-driven strategy exploits a Hidden Markov Model (HMM) formulation. We report numerical experiments for simulated geophysical dynamics and real SST observation series, which demonstrate the relevance of the proposed framework.

 

Yali Wang, Memorial University of Newfoundland

Wind Speed Extraction from Rain-contaminated X-band Nautical Radar Data

In this paper, a new method for retrieving wind speeds from rain-contaminated X-band nautical radar images is presented. The method mitigates rain influence by applying the gamma correction to rain-contaminated images, and then relates the average intensities of radar images to the measured wind speeds with a logarithmic function. The method has been tested using X-band nautical radar images and shipborne anemometer data. A comparison with the anemometer data shows that the root mean square error of wind speeds retrieved from rain-contaminated radar images is reduced by 5.4 m/s.

 

Jungwook Han, KAIST

Three-Dimensional Reconstruction of a Semi-Submersible Offshore Platform with an Unmanned Surface Vehicle

This paper addresses the three-dimensional (3D) reconstruction of a floating structure with an unmanned surface vehicle (USV). Onboard lidar and sonar sensors are employed to collect a volumetric point cloud of the structure both above and below the waterline. These measurements are obtained in the vehicle-fixed frame; thus, for successful 3D reconstruction, precision estimation of trajectory and attitude is required. GPS signals are severely deteriorated or unavailable near and under floating structures. Therefore, relative navigation with respect to the planar surfaces of their hull structures is performed in the framework of simultaneous localization and mapping (SLAM). This approach enables high-precision navigation and mapping near and under a large floating structure. A field experiment was performed in a semi-submersible offshore platform environment and the results are presented.

 

David R. Silver, United States Naval Academy

Experimental Analysis of an Array of Oscillating Water Columns (OWCs) to Determine Feasibility of an Offshore Structure that Converts Ocean Wave Energy in Usable Power

This paper will first analyze the effect on power output and relative capture width utilizing experimental data from various configurations of four oscillating water columns in an array. Then, a case study will be performed on the feasibility of constructing an offshore structure that will utilize oscillating water columns (OWCs) with pneumatic wave energy conversion devices to harness and convert the ocean wave energy into useable power and power an offshore structure entirely by renewable resources.

 

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