In recent years, ocean has become a place to dispose of industrial and civil waste waters. Hence, there are more and more projects to establish offshore outflow pipes. These underwater pipes should be kept monitored in order to maintain their functions specifically. The purpose of this research was to explore the two outflow pipes in Kaohsiung offshore area, i.e., Chung-chou outflow pipe and Tso-ying outflow pipe, by using an integrated surveying system which includes a side-scan sonar and a sub-bottom profiler. The ultimate objective was to investigate the feasibility of this system in searching and positioning of buried underwater pipelines. Based on this investigation, the offshore section of Chung-chou outflow pipe is about 2.8km in length and extends offshore to the direction of 38o from the west to the south. The water depth at the end of this pipe is about 21m. Among the 2.24km section initiated at the offshore end of the pipe, the buried depths are between 2.2m and 3.2m. There are two disposed gravel zones around the offshore end of the pipe. The first zone is about 130m in length and 10m wide. The second zone is 220m in length and 20m wide. Moreover, based on the side scan sonar images, there are 71 protective concrete blocks located around Chung-chou outflow pipe. The offshore section of Tsao-ying outflow pipe is about 4.76 km in length and extends to the direction of 20o from the west to the south. The water depth at the end of this pipe is about 17m. Among the 3.7km section initiated at the offshore end of the pipe, the buried depths are about 1.0 to 2.5m. A disposed gravel zone with dimensions of 330m in length and 10m wide is located at the end of this pipe. In addition, there are 43 protective blocks located around this outflow pipe. This investigation, incorporated the results conducted on the other three underwater outflow pipes(i.e., Chishui creek outflow pipe, Chinese Petroleum Corporation underwater petroleum pipe off Kaohsiung Harbor and Liuchiuyu water transport pipe), concluded that as far as the buried underwater pipes that are thicker than 1m in diameter are concerned, the integrated system of side scan sonar and sub-bottom profiler provides an useful and trustful tool to get the locations and the buried depth of outflow pipes, as well as the distribution of the protective concrete blocks around these pipes. As to the pipes that are less than 20cm in diameter, the pipes can¡¦t be detected by this equipment. For the pipes that are between 20cm and 1m in diameter, due to limited information collected up to this moment, extensive investigation need to be conducted until a clear understanding can be deduced.

Underwater static targets are objects under the water that can¡¦t move autonomously. Apparatus feasible for detecting underwater static targets includes: optics, acoustics and geophysical instruments. The purpose of this research is discussing the efficiency of applying side-scan sonar, magnetometer, sub-bottom profiler and echo sounder simultaneously to search, detect, identify and locate underwater static targets. Procedures of this research include: 1. Discussing the capabilities of instruments and identification principles on target. 2. Using a real case to groundtruth target identification principles. 3. Assessing the superiority of the methodology. According to the characteristics of these apparatus, the water depth, collected by echo sounder, is capable of expressing the relief of the seabed. Seabed sonographs, recorded by side-scan sonar, show that it is feasible to detect, identify and locate targets on the seabed. Sub-bottom profiler provides the sub-surface sedimentary information which can be used to detect buried targets. Magnetometer can detect environmental magnetic intensities, which can locate and determine the size of ferrous targets. Analysis of the data collected at Hai-Köu Wan, Ping-Dong County yields following conclusions: 1. The water depth data, recorded per 15 meters by the echo sounder, is capable of detecting large targets and concentrated artificial reefs only. 2. Sonographs obtained by side-scan sonar show target¡¦s characteristics and location on seabed. It can be utilized to identifying targets and mapping targets distributions. 3. Sub-bottom profile graphs show the composition and thickness of sub-surface sediments. 4. Magnetic anomalies show that there are evident variations around the battle-ship reef or concentrated electric-pole reefs on the research area. It represents that the magnetometer is capable in detecting underwater ferrous targets. 5. Targets detecting rate and identifying accuracy can be increased by the mutual comparison of various information. By applying the technique established in this research and the survey results at Hai-Köu Wan, targets at the survey site can be identified and located precisely. There are about 1100 units of 2-m concrete reefs, 670 units of electric-pole reefs and a battle-ship reef at Hai-Köu Wan. It can be concluded that, applying echo-sounder, side-scan sonar system, sub-bottom profiler and magnetometer simultaneously can search, detect, identify and locate underwater static targets more effective than applying a single instrument such as side-scan sonar system.

Simpson Bay is a turbid, outwash fjord located in northeastern Prince William Sound, Alaska. A high ratio of watershead:basin surface area combined with high precipitation and an easily erodable catchment create high sediment inputs. Fresh water from heavy precipitation and meltwater from high alpine glaciers enter Simpson Bay through bay head rivers and small shoreline creeks that drain the catchment. Side scan sonar, seismic profiling, and high resolution bathymetry were used to investigate the record of modern sedimentary processes. Four bottom types and two seismic faces were described to delineate the distribution of sediment types and sedimentary processes in Simpson Bay. Sonar images showed areas of high backscatter (coarse grain sediment, bedrock outcrops and shorelines) in shallow areas and areas of low backscatter (estuarine mud) in deeper areas. Seismic profiles showed that high backscatter areas reflected emergent glacial surfaces while low backscatter areas indicated modern estuarine mud deposition. The data show terminal morainal bank systems and grounding line deposits at the mouth of the bay and rocky promontories, relict medial moraines, that extend as terrestrial features through the subtidal and into deeper waters. Tidal currents and mass wasting are the major influences on sediment distribution. Hydrographic data showed high spatial variability in surface and bottom currents throughout the bay. Bottom currents are tide dominated, and are generally weak (5-20 cm s-1) in the open water portions of the bay while faster currents are found associated with shorelines, outcrops, and restrictive sills. Tidal currents alone are not enough to cause the lack of estuarine mud deposition in shallow areas. Bathymetric data showed steep slopes throughout the bay suggesting sediment gravity flows. Central Alaska is a seismically active area, and earthquakes are most likely the triggering mechanism of the gravity flows.

The advantages that a side-scan sonar can offer include large-scale survey areas and high-resolution imagery which can provide the detection and positioning of underwater targets effectively. The purpose of image analysis, classification and positioning in this research was presented by the development of an automated recognition and classification system based on sonographs collected off Kenting area. Major components of the system include gray level co-occurrence matrix method, Baysian classification and cluster analysis. The sonograph classified by the automated recognition and classification system was split into two stages. The first stage divided the seafloor into three categories: (1) Rocky seafloor. (2) Sandy seafloor. (3) Acoustic shadow seafloor. Based on the characteristics of the rocky seafloor, the rocky seafloor was subdivided into five types in the second stage: (1) Flank reef and small independent reef. (2) Smooth reef. (3) Small coral on reef. (4) Coral on independent reef. (5) Large coral on reef. Analysis and proof of the system was conducted by underwater photographs collected off Kenting area in August 4, to 6, 2004. The identification accuracy of the first stage can reach 93% in Shiniuzai area. The characteristic features selected in this research (i.e., entropy and homogeneity) for the classification of various coral reef seafloors was proved adequate and the results was described in map within a Geographic Information System in the second stage. The results of this research illustrated that the rocky area identified in Shiniuzai was 98,863 m2. Due to image resolution restrictions, only 62,199 m2 of the total rocky area could be defined and classified properly. Among them, the flank reef and small independent reef covered an area of 15,954 m2 (26.3%); the smooth reef covered 3,133 m2 (5.0%); the small coral on reef covered 8,021 m2 (12.8%); the coral on independent reef covered 25,504 m2 (40.7%) and the large coral on reef covered 9,587 m2 (15.3%). Key words:side scan sonar,coral reef,gray level co-occurrence matrix

Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (February 17, 2010) Includes bibliographical references (p. 63-67)

Thesis (M.S. in Modeling, Virtual Environments and Simulation (MOVES))--Naval Postgraduate School, March 2004. / Thesis advisor(s): Christian Darken, Curtis Blais. Includes bibliographical references (p. 103-104). Also available online.

This dissertation analyzes the capability of multiple-input, multiple-output (MIMO) radar techniques to improve the image quality and area-coverage rate of synthetic aperture imaging systems. A signal processing architecture for MIMO radar is used to understand the applicability of MIMO for synthetic aperture radar (SAR) and synthetic aperture sonar (SAS) systems. MIMO SAR/SAS is shown to be a natural extension of standard multichannel synthetic aperture imaging techniques to exploit transmit degrees of freedom in addition to those used on receive. Degradation in range sidelobe performance and the associated impact on image quality is identified as a key impediment to MIMO SAR/SAS. A novel mismatched filtering approach is presented to mitigate this issue. New results in sampling theory are derived that allow the aliasing that occurs when a wide-sense stationary random process is non-uniformly sampled to be quantified. These results are applied to the case of recurrent sampling and used to quantify the impact of azimuth ambiguities on MIMO SAR/SAS image contrast.

Beamforming is a signal processing technique used in sensor arrays to direct signal transmission or reception. Beamformer combines input signals in the array to achieve constructive interference at particular angles (beams) and destructive interference for other angles. According to the following facts: 1- Beamforming can be computationally intensive, so real-time sonar beamforming algorithms in sonar devices is important. 2- Parallel computing has become a critical component of computing technology of the 1990s, and it is likely to have as much impact over the next 20 years as microprocessors have had over the past 20 [5]. 3- The high-performance computing community has been developing parallel programs for decades. These programs run on large scale, expensive computers. Only a few elite applications can justify the use of these expensive computers [2]. 4- GPU computing has the ability of parallel computing and it could be available on the personal computers. The objective of this thesis is to use Graphics Processing Unit (GPU) as real-time digital beamformer to accelerate the intensive signal processing.

No description available.

Swath bathymetry sidescan (SBS) sonar and the angle-of-arrival processing that underlies these systems has the capability to produce much higher resolution three dimensional imagery and bathymetry than traditional beamformed approaches. However, the performance of these high resolution systems is limited by signal-to-noise ratio (SNR) and they are also susceptible to multipath interference. This thesis explores two methods for increasing SNR and mitigating multipath interference for SBS systems. The first, binary coded pulse transmission and pulse compression is shown to increase the SNR and in turn provide reduced angle variance in SBS systems. The second, transmit beamforming, and more specifically steering and shading, is shown to increase both acoustic power in the water and directivity of the transmitted acoustic radiation. The transmit beamforming benefits are achieved by making use of the 8-element linear angle-of-arrival array typical in SBS sonars, but previously not utilized for transmit. Both simulations and real world SBS experiments are devised and conducted and it is shown that in practice pulse compression increases the SNR, and that transmit beamforming increases backscatter intensity and reduces the intensity of interfering multipaths. The improvement in achievable SNR and the reduction in multipath interference provided by the contributions in this thesis further strengthens the importance of SBS systems and angle-of-arrival based processing, as an alternative to beamforming, in underwater three dimensional imaging and mapping. / Graduate / 2015-04-15 / 0544 / 0547 / mark.butowski@gmail.com