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A Study on the Recognition of Seabed Environments Employing Sonar Images
Get PDF九州工業大学博士学位論文 学位記番号:工博甲第364号 学位授与年月日:平成26年3月25日Chapter 1 Introduction||Chapter 2 Underwater acoustics||Chapter 3 Detection of underwater objects based on machine learning||Chapter 4 Automatic classification of seabed sediments using HLAC||Chapter 5 ConclusionThe ocean accounts for approximately 70% of the area on the earth, and the water as well as coastal areas sustain many species including humans. Ocean resources are used for fish farming, land reclamation, and a variety of other purposes. Seabed resources such as oil, natural gas methane hydrates, and manganese nodules are still largely unexploited on the bottom of the sea. Maps are critical to development activities such as construction, mining, offshore drilling, marine traffic control, security, environmental protection, and tourism. Accordingly, more topographic and others types of mapping information are needed for marine and submarine investigations. Both waterborne and airborne survey techniques show promise for collecting data on marine and submarine environments, and these techniques can be classified into four main categories. First, remote sensing by satellites or aircraft is a widely used technique that can yield important data such as information on sea levels and coastal sediment transport. Second, investigations may collect direct information by remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs), and divers. While the quality of data obtained from these techniques is high, the data obtained are often limited to relatively shallow and small geographic areas. Third, sediment profile imagery can be used to collect photographs that contain detailed information about the seabed. Lastly, acoustic investigations that use sonar are popular in marine mapping studies, especially in coastal areas. In particular, acoustic investigations that employ ultrasound technology can yield rich information about variations in bathymetry. Unlike air, water has physical properties that make it difficult for light or electromagnetic waves to pass through. However, sound waves propagate readily in water. Therefore, sound waves are used in a wide range of technical applications to detect underwater structures that are difficult to observe with light-based techniques. In the dark depths of the ocean, the use of acoustic technology is essential. The development of marine acoustic technology is expanding in modern times. In addition to the basic physics related to acoustic waves, much research has been dedicated to other basic and applied fields such as electronics, physical oceanography, signal processing, and biology. The realization of new sonar systems that utilize advanced detection algorithms can be expected to contribute to major breakthroughs in oceanographic research that require deployment to novel marine environments and other areas of natural resource interest. In this study, the author focuses on side-scan sonar, which is one of the imaging technologies that employs sound to determine the seabed state, to conduct research on imaging algorithms for discrimination. The proposed method for discrimination was coupled to a high-speed detection method for installed reefs on the seabed. This method is also capable of detecting unknown objects with Haar-like features during object recognition of rectangular regions of a certain size via machine learning by AdaBoost and fast elimination of non-object regions on the cascade structure. Side-scan and forward looking sonars are some of the most widely used imaging systems for obtaining large-scale images of the seafloor, and their application continues to expand rapidly with their increasing deployment on AUVs. However, it can be difficult to extract quantitative information from the images generated from these processes, in particular, for the detection and extraction of information on the objects within these images. Hence, this study analyzes features that are common to most undersea objects projected in side-scan sonar images to improve information processing. By using a technique based on the k-means method to determine the Haar-like features, the number of patterns of Haar-like features was minimized and the proposed method was capable of detecting undersea objects faster than current methodology. This study demonstrates the effectiveness of this method by applying it to the detection of real objects imaged on the seabed (i.e., sandy ground and muddy ground). Attempts are made as well to automate the proposed method for discriminating objects lying on the seafloor from surficial sediments. During undersea exploration, a thorough understanding of the state of the seafloor surrounding objects of interest is important. Therefore, a method is proposed in this study to automatically determine seabed sediment characteristics. In traditional methods, a variety of techniques have been used to collect information about seabed sediments including depth measurements, bathymetry evaluations, and seabed image analyses using the co-occurrence direction of the gray values of the image. Unfortunately, such data cannot be estimated from the object image itself and it can take a long time to obtain the required information. Therefore, these techniques are not currently suitable for real-time identification of objects on the seafloor. For practical purposes, automatic techniques that are developed should follow a simple procedure that results in highly precise and accurate classifications. The technique proposed here uses the subspace method, which is a method that has been used for supervised pattern recognition and analyses of higher-order local autocorrelation features. The most important feature of this method is that it uses only acoustic images obtained from the side-scan sonar. This feature opens up the possibility of installing this technology in unmanned small digital devices. In this study, the classification accuracy of the proposed automation method is compared to the accuracy of traditional methods in order to show the usefulness of the technology. In addition, the proposed method is applied to real-world images of the seabed to evaluate its effectiveness in marine surveys. The thesis is organized as follows. In Chapter 1, the purpose of this study is presented and previous studies relevant to this research are reviewed. In Chapter 2, an overview of underwater sound is given and key principles of sound wave technology are explained. In Chapter 3, a new method for detecting and discriminating objects on the seafloor is proposed. In Chapter 4, the possibility of automating the discrimination method is explored. Finally, Chapter 5 summarizes the findings of this study and proposes new avenues for future research
可能性分子相の界面機能に関する研究
Get PDF九州工業大学博士学位論文 学位記番号:生工博甲第212号 学位授与年月日:平成26年3月25日第1章 序論||第2章 金ナノ粒子表面に形成したペプチド分子相の特性解析と医薬スクリーニング手法への応用||第3章 可動性を持つ固定化酵素の分子相形成とその特性解析||第4章 分子相の可動性変化による光励起電流応答の解析||第5章 結
高Siフェライト基地球状黒鉛鋳鉄の機械的性質及び溶接部の組織形成に関する研究
Get PDF九州工業大学博士学位論文 学位記番号:生工博甲第215号 学位授与年月日:平成26年3月25日第1章 緒論||第2章 高Siフェライト基地球状黒鉛鋳鉄の強度特性||第3章 溶接熱影響部の組織形成||第4章 溶接ボンド部近傍の部分溶融・凝固組織形成||第5章 球状黒鉛鋳鉄アーク溶接部の静的強度特性||第6章 総
Comparing effectiveness of feature detectors in obstacles detection from video
Get PDFWe have already proposed an obstacles detection method using a video taken by a vehicle-mounted monocular camera. In this method, correct obstacles detection depends on whether we can accurately detect and match feature points. In order to improve the accuracy of obstacles detection, in this paper, we make comparison among four most commonly used feature detectors; Harris, SIFT, SURF and FAST detectors. The experiments are done using our obstacles detection method. The experimental results are compared and discussed, and then we find the most suitable feature point detector for our obstacles detection method
A Visualization System of Scaler Stroke Motion
Get PDFPeriodontitis is a dental disease from which many people suffer. The most effective treatment with it is to remove dental plaque and scale periodically by a scaler. For this purpose, those who wish to be a dentist or a hygienist must take training of scaling and root planing using a jaw model and a scaler. It is, however, difficult for a trainer to evaluate the scaler stroke motion of a trainee, since the end of the scaler in a mouth cannot be observed directly from out of the mouth. This paper proposes a novel method of visualizing the scaler stroke motion in the mouth three-dimensionally by the employment of a camera and a computer. The system is described and an experimental result is shown
Load Short-Circuit Protection with Detecting the Gate Voltage and Gate Charge of an IGBT
Get PDF半導体電力変換／モータドライブ合同研究会, 1月24日25日, 2014年, 神戸大学 六甲台キャンパス 滝川記念学術交流会館大会議室, 神戸市This paper proposes a new load short-circuit protection method for an IGBT. The proposed method is characterized by detecting not only gate charge but also gate voltage of the IGBT. This results in a shorter protection time, compared to the previous method that detects only the gate charge. A real-time monitoring system using an FPGA, AD converters, and DA converters, is used for the proposed protection method. Experimental results verify that the proposed method achieves a protection time of 390 ns, which is reduced by 68% compared to the previous method
Structure Oriented Compact Model for Advanced Trench IGBTs without Fitting Parameters for Extreme Condition: Part II
Get PDFESREF 2014, 25th EUROPEAN SYMPOSIUM ON RELIABILITY OF ELECTRON DEVICES,
FAILURE PHYSICS AND ANALYSIS, Sep 29–Oct 3, 2014, Technische Universität BerlinCompact model for expressing turn-off waveform for advanced trench gate IGBTs is proposed even under high current density condition. The model is analytically formulated only with device structure parameters so that no fitting parameters are required. The validity of the model is confirmed with TCAD simulation for 1.2 kV to 6.5 kV class IGBTs. The proposed turn-off model is sufficiently accurate to calculate trade-off curve between turn-off loss and saturation collector voltage under extremely high current conduction, so that the model can be used for system design with the advanced trench gate IGBTs
Correction of positioning and angular errors for ball screw feed unit
Get PDFIn the present study, we developed a new feed correction mechanism which corrected not only a positioning error (i.e., feed deviation) but also an angular error (i.e., yaw of a table). A correction mechanism including two piezoelectric actuators was constructed and installed between double nuts. The correction mechanism corrects positioning error if both piezoelectric actuators are expanded to the same length, and corrects angular error if one piezoelectric actuator is expanded and the other is contracted. First, the positioning and angular errors correction functions were investigated separately. A load was applied to one side of the table in order to simulate a counter force during machining. In the positioning error correction, a low-frequency component of positioning error was corrected effectively under the condition that the load for the table was set to at least 50 N. In the angular error correction, the correction capability was comparable to that of the positioning error correction up to the maximum load torque to the table, 1.4 Nm. The load torque was limited to 1.4 Nm because both piezoelectric actuators reached their saturation voltage. Finally, simultaneous correction of positioning error and angular error was examined, and the simultaneous correction capability was confirmed to be equivalent to the separate correction capabilities
マウス茸状乳頭味蕾細胞の電気生理学的性質とその細胞型依存性
Get PDF九州工業大学博士学位論文 学位記番号:生工博甲第222号 学位授与年月日:平成26年3月25日第一章 研究の背景と目的||第二章 味蕾細胞の免疫組織化学的同定||第三章 味蕾細胞の電気生理学的性質と細胞型との関係||第四章 味蕾細胞の電気生理学的性質と生理的機能との関係||総