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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Preserving Texture Boundaries for SAR Sea Ice Segmentation

Jobanputra, Rishi January 2004 (has links)
Texture analysis has been used extensively in the computer-assisted interpretation of SAR sea ice imagery. Provision of maps which distinguish relevant ice types is significant for monitoring global warming and ship navigation. Due to the abundance of SAR imagery available, there exists a need to develop an automated approach for SAR sea ice interpretation. Grey level co-occurrence probability (<i>GLCP</i>) texture features are very popular for SAR sea ice classification. Although these features are used extensively in the literature, they have a tendency to erode and misclassify texture boundaries. Proposed is an advancement to the <i>GLCP</i> method which will preserve texture boundaries during image segmentation. This method exploits the relationship a pixel has with its closest neighbors and weights the texture measurement accordingly. These texture features are referred to as <i>WGLCP</i> (weighted <i>GLCP</i>) texture features. In this research, the <i>WGLCP</i> and <i>GLCP</i> feature sets are compared in terms of boundary preservation, unsupervised segmentation ability, robustness to increasing boundary density and computation time. The <i>WGLCP</i> method outperforms the <i>GLCP</i> method in all aspects except for computation time, where it suffers. From the comparative analysis, an inconsistency with the <i>GLCP</i> correlation statistic was observed, which motivated an investigative study into using this statistic for image segmentation. As the overall goal of the thesis is to improve SAR sea ice segmentation accuracy, the concepts developed from the study are applied to the image segmentation problem. The results indicate that for images with high contrast boundaries, the <i>GLCP</i> correlation statistical feature decreases segmentation accuracy. When comparing <i>WGLCP</i> and <i>GLCP</i> features for segmentation, the <i>WGLCP</i> features provide higher segmentation accuracy.
92

Födosammansättning hos gråsäl (Halichoerus grypus) samt test av flotte för insamling av sälfekalier.

Lagström, Christian January 2008 (has links)
During the 1960´s and 1970´s the number of grey seals in the Baltic Sea was decreasing rapidly, mostly due to hunting and toxic substances like DDT and PCB. When hunting became less intense and toxic substances decreased in the environment the grey seal population started to increase. Today grey seals are found common in the Baltic Sea and have started to become a big treat and a problem to the fishing industry. The grey seal destroys and enters fishing traps and consumes large quantities of the fish that have been caught. The knowledge of the grey seal, like abundance and food preferences, is today limited. It is also important to define the position of the grey seal in the ecosystem in the Baltic Sea and to be able to predict changes that could occur if the population would rapidly decrease or increase. This project was therefore started in an attempt to increase the knowledge about the grey seals food preferences. The study was made in tree separate parts. Part one contained analyses of prey remains from stomachs and digestive tract from fourteen individuals put down in two geographically separate areas. The collected material from the seal digestive tract was cleaned and otoliths (hearing stones from fish), scales and back vertebra from fish eaten by the grey seal were sorted out. With the help of hard parts collected from the intestines the food preferences of the seals could be estimated. Eight different species of prey was found. The species were herring (Clupea harengus membras), sprat (Sprattus sprattus), common whitefish (Coregonus spp), perch (Perca fluviatilis), salmon (Salmo salar), trout (Salmo trutta) and roach (Rutilus rutilus). In two of the digestive tracts several individuals of the isopod Saduria entomon were found. No earlier studies describe the isopod as a food source for the grey seals in the Baltic Sea. The findings are therefore unique information. The results showed that during summer the main part of the grey seal diet in the gulf of Sundsvall and in the surrounding coastal area of Hårte was herring and sprat. No significant difference in food preferences was shown between the investigated seals from the gulf of Sundsvall and seals from the surrounding coastal area of Hårte. The second part was made to investigate if it was possible to build a floating platform that would work as a resting place for the grey seal. The surface of the platform was covered by a layer that keeps the seal scats on the platform so that it could be collected. Otoliths from herring and common whitefish were found on the floating platform. Because the platform could not be under surveillance during the whole study some uncertainties about whether the otoliths found came from grey seal or from resting cormorants or other fish eating birds. However, the otolit size is linearly related to the fish size and this relationship can be used to track the predator. Otoliths from herring taken by grey seals and otoliths found on the platform were significantly bigger than the otoliths originating from the prey of cormorants. The results indicated that the common whitefish size was too big for a full grown cormorant bird to consume. The common whitefish size showed that it probably not had been cormorants that had deposited the otoliths on the platform. The platform method was concluded promising but it needs to be modified in order to work more effective in the future. In the third part scats were collected from the area of Österåsen to increase the amount of information about the grey seals food preferences. The knowledge of the grey seals diet in the Baltic Sea is today limited and few similar study’s have earlier been made. The collected scats and otoliths in this project are therefore unique. 2008:Bi 2
93

Automatic Recognition of Artificial Objects in Side-scan Sonar Imerage

Li, Ying-Zhang 02 August 2011 (has links)
Abstract The interpretation and identification of information from the side-scan sonar imagery are mainly depended on visual observation and personal experiences. Recent studies tended to increase the identification efficiency by using numerical analysis methods. This can reduce the error that cause by the differences of observer¡¦s experience as well as by extended time observation. The position around the center line of the slant range corrected side-scan sonar imagery might result in the degradation of the ability of numerical methods to successfully detect artificial objects. Theoretically, this problem could be solved by using a specific characteristic function to identify the existence of concrete reefs, and then filtering the noise of the central line area with a threshold value. This study was intended to develop fully automatic sonar imagery processing system for the identification of cubic concrete and cross-type protective artificial reefs in Taiwan offshore area. The procedures of the automatic sonar imagery processing system are as follows: (1) Image Acquisition¡G500kHz with slant range of 75m. (2) Feature Extraction¡Ggrey level co-occurrence matrix (i.e., Entropy, Homogeneity and Mean) (3) Classification¡Gunsupervised Bayesian classifier. (4) Object Identification¡Gby characteristic feature (i.e., Entropy). (5) Object¡¦s Status Analysis¡Gobject¡¦s circumference¡Barea¡Bcenter of mass and quantity. This study used the sonar images collected at Chey-Ding artificial reef site in Kaohsiung City as a case study, aiming to verify the automatic sonar imagery processing system and find out the optimum window size. The image characteristic functions include one set of first order parameter (i.e., mean) and two sets of second order parameter (i.e., entropy and homogeneity). Eight(8) sonar images with 1-8 sets of cubic concrete and cross-type protective artificial reefs where used in this step. The identification efficiency of the system, in terms of the produce¡¦s accuracy, is 79.41%. The results illustrated that there were 16~28 sets of artificial reefs being detected in this case which is comparable with the actual amount of 17 sets. Based on this investigation, the optimum window size was concluded to be 12¡Ñ12 pixels with sliding size of 4 pixel. Imagery collected at Fang-Liau artificial reef site of Pingtung County was tested. For the purpose of applicability, the original imagery (2048¡Ñ2800 pixels) was divided into 8 consecutive smaller sized imagery frames(2048¡Ñ350 pixels). The influence of using a two-fold classification procedure and a central filtering method to reduce the noise that caused by slant range correction were discussed. The results showed that central line filtering method is applicable. The results of object¡¦s status analysis showed that there are 156-236 sets of reefs existed. Automatic determination of the target using the characteristic function of entropy is feasible. If the value is larger than 1.45, it represents positive identification of concrete artificial reefs. It can be classified as muddy sand seabed type if the value is smaller than 1.35. If the value is between 1.35~1.45, it illustrates the existence of a transition zone where objects of smaller in dimensions might exist. To achieve the purpose of automatic operation, firstly, we have to identify the existence of the concrete reefs by using the specific characteristic function. Based on the result of existing concrete reefs, suture line filtering method will hence be used to filter the noise from the image information. For that all of the procedures are automatically operated without human intervention. Key word: side-scan sonar ; characteristic function ; gray level co-occurrence matrix ; Bayesian classification ;entropy ; homogeneity ; mean
94

A Research on the Assessment of Vessel Traffic Operators¡¦ Performance by Grey Analysis

Chen, Hsi-ching 20 August 2012 (has links)
The performance of Vessel Traffic Service (VTS) depends upon not only the facilities but the training and operational competence of the VTS operators. In this research, the current status and training scheme of four major VTS ports are reviewed. A fuzzy Analytic Hierarchy Process (AHP) model is subsequently developed to evaluate the training effectiveness of the VTS operators. The approach proposed enables experts to linguistically express opinions with degrees of truth of which the relationships are continuous. This solves the mapping problems between linguistic terms and discrete numerals resulting from traditional AHP methods. Four hierarchies comprising the factors of goals, competence, modules and subjects are constructed. The weights and priority of the elements for each hierarchy are acquired. The Grey Interval Measure method is also applied to analyze the training effectiveness and competence of the VTS operators by calculating the upper and lower bounds of the VTS-operator evaluations. The operational competence of VTS operators is judged by the experts invited. Finally, the interrelationships between the performance and the background indices are appreciated and the alternatives enhancing the performance of the VTS operators are identified. The measures include the recruitment of personnel with higher educational and professional backgrounds and enhancement of the professional trainings for the existing employees. The subjects of the training are also identified in this study. The contents and course hours should be appropriately organized and more attentions should be paid to the topics with higher weights. If the consistency with regard to the training schemes for the four VTS ports can be enhanced to a certain level, the quality of the VTS performance in Taiwanese waters will be increased. The marine safety will also be improved and marine environmental pollutions will be reduced.
95

Emergencey Operation Strategy for Power System Restoration with Artificial Neural Network and Grey Relational Analysis

Chen, Chine-Ming 23 January 2006 (has links)
Power system protection is important for service reliability and quality assurance. Various faults may occur due to natural and artificial calamity. Dispatchers are use the changed statuses of protection devices from the Supervisory Control and Data Acquisition (SCADA) system to identify the fault. To reduce the outage duration and promptly restore power services, fault section detection has to be done effectively and accurately with fault alarms. In this thesis, artificial neural networks (ANN) and Grey Relational Analysis (GRA) are used to develop the restoration schemes for emergency operation in a power system including fault section detection (FSD), restoration strategy(RS), and voltage correction(VC). The optimal power flow (OPF) is responsible for verifying the proposed schemes by off-line analysis. With a IEEE 30-Bus power system, computer simulations were conducted to show the effectiveness of the proposed restoration schemes.
96

Development of A Sun Track Solar Energy System with Artificial Intelligence

Lay, Jong-Jinn 24 June 2008 (has links)
Factors of very rapidly rising oil prices, the running out time limits on continued use of fossil fuels, as well as elements of the Kyoto Protocol, have greatly arouses the increasing emphasis on natural and renewable energy sources. 40 minutes of total solar radiation on earth could provide enough power to meet the energy needs of all human beings for approximately one year. The potential of solar energy is virtually limitedless. Moreover, by means of solar powered batteries, solar energy can be directly converted to electric power. Since it neither pollutes the environment or ecology, solar is an extremely clean source of energy. The life-span of solar cell is very long, possibly 20 years or more. The capability of solar batteries to provide energy is approximately proportional to the intensity of the sunlight. This thesis proposes the use of Artificial intelligence for "Sun Track Solar Energy System". This system employs Fuzzy Logic Control Theory, combined with Grey Relational Analysis, for tracking the angle of the sun, and further control the motor to adjust the angle for tracking, so direct sunlight could be acquired to increase power output. As a result of the experiment, comparing the electricity generated from the fix angle solar battery with the AI-based Sun Track Solar Energy System, the latter one has an efficiency increase up to 23% for the same amount of sunlight.
97

Physicochemical Characteristics and Source Allocation of Asian Dusts Sampled in Penghu Islands

Liu, Yi-chi 25 August 2008 (has links)
In recent years, the Asian dust storms occurred frequently. It was estimated that approximately eight hundred million metric tons of Asian dusts transported to the atmosphere yearly. During the dust storm period, Asian dusts not only induce poor air quality, but also reduce atmospheric visibility and influence human health. In order to investigate the physicochemical characteristics and source allocation of Asian dusts, this study collect the Asian dusts in the Pescadores Islands during the years of 2002~2006. In addition, this study collected top soils in three regions of Inner Mongolia and resuspended the soil samples in a resuspension chamber to analyze their chemical composition. Moreover, this study applied enrichment factor analysis (EF) and grey relational analysis to allocate the potential sources of Asian dusts and compare them with the transportation routes obtained from backward trajectory. During Asian dust storm periods, the concentration of atmospheric particulate matter (PM10) in the Pescadores Islands increased significantly, probably is 3~6 times of PM10 during non-dust storm periods. Among them, coarse particles (PM2.5-10) particularly rose from 10~30 £gg/m3 to 80~130 £gg/m3 and the size distribution changed from bi-modal distribution to single modal distribution of coarse particles during Asian dust storm periods. This study further analyzed the chemical composition of Asian dusts, including water-soluble ionic species, carbon contents, and metallic contents. For fine particles (PM2.5), the order of water-soluble ionic species was SO42- > NH4+ > NO3- > Cl- > Ca2+ > Na+ > K+ > Mg2+ > F-. For coarse particles (PM2.5-10), the order of water-soluble ionic species was Cl- > SO42- > NO3- > Na+ > Ca2+ > NH4+ > Mg2+ > K+ > F-. The carbon contents distributes mainly in fine particles. The major contents of both fine and coarse particles were crustal elements (i.e. Al, Fe, Na, Mg, K, Ca, and Sr). In addition to the analysis of physicochemical characteristics of Asian dusts, this study applied HYSPLIT MODEL to figure out their transportation routes by backward trajectory. According to the backward trajectories, this study compartmentalized Asian dusts storm transportation routes into three categories: Eastward Transportation and Retraced (ETR), Southeasterly Transportation and Circumrotated (STC), and Straight Southeasterly Transportation (SST). Analyzing the spatial and temporary background variables to investigate the influence of transportation routes on Asian dusts¡¦ physicochemical characteristic. This study revealed that the physicochemical characteristics were very similar for same category of Asian dust storms, which can be used to allocate the source regions of Asian dust storms. This study resuspended the soil samples collected in Inner Mongolia inside a resuspension chamber and collected the suspended particles (PM2.5, PM2.5-10) for chemical analysis. Chemical analysis results indicated that the fingerprints of chemical composition for different regions were similar but still distinguishable, which can be used to identify the source areas of Asian dusts. This study further compare and correlate the Asian dusts collected at the Pescadores Islands during Asian dust storm periods with the soils collected in Inner Mongolia chemically by enrichment factor and grey relational analysis. This study further compared the source allocation of Asian dust storms obtained from enrichment factor, grey relational analysis, and backward trajectory and found the results of these three methods were quite similar. For enrichment factor analysis, 88% of similarity was obtained by using two separate reference elements (Al and Fe). The similarity of backward trajectory and grey relational analysis reached as high as 83%. Moreover, the backward trajectory and enrichment factor were similar up to 75%, while the grey relational analysis and enrichment factor were similar up to 69%. Overall, two out of three aforementioned methods can effectively allocate the source regions of Asian dusts by 94%, while all three methods can successfully allocate the source regions of Asian dusts by 56%. Comparison of three aforementioned methods showed that they can be applied to allocate the source regions of Asian dusts.
98

The Effect of Methamphetamine Abuse on Brain Structure and Function

Clavenstam, Isabell January 2009 (has links)
<p>The great amount of METH abuse all over the world causes enormous social and criminal justice problems. In the human brain the abuse of METH causes implications on both structures and functions given rise to acute as well as long term symptoms. In this essay the effects of METH abuse is described in the manner of the drug mechanism such as the impact on neurotransmitters, structural deficits with decreased and increased volumes and the implication on attention, memory, decision  making and emotions. Results from studies showing brain structural and cognitive impairments in METH abusers and in prenatal METH exposed children.</p>
99

A mail survey to assess the incidence and impact of drug shortages within Texas Non - Government Acute Care Hospitals

Rajab, Tawfik Rajab 25 March 2014 (has links)
A Mail Survey to Assess the Incidence and Impact of Drug Shortages within Texas Non – Government Acute Care Hospitals Tawfik Rajab Rajab, M.S.Phr. The University of Texas at Austin, 2013 Supervisor: Marvin D. Shepherd The objective of this study was to explore the incidence and impact of drug shortages within Texas Non-Government Acute Care Hospitals. A self-administered mail survey instrument was used to collect data. A convenience sample of 321 pharmacy directors of non-government acute care hospitals in the state of Texas was selected from the Texas Department of State Health Services (DSHS) Hospital List for 2012. A total of 125 completed surveys were received by mail and 8 surveys were returned as undelivered, resulting in a response rate of 39.84% (125/313). A total of 56 (45.5%) respondents reported 11 or more drug shortages for the month of April 2013. There was a significant association between the number of drug shortages experienced and hospital size (p = 0.003), inpatient medication budget (p = 0.001) and hospital location (p=0.015). Of the 124 respondents, 78 (62.9%) spent four to 12 hours a week on managing drug shortage situations. There was a significant association between the number of hours spent per week by hospital pharmacy personnel when managing drug shortages controlling for hospital size (p < 0.001), number of drug shortages experienced (p < 0.001), number of pharmacist FTEs (p < 0.001), and number of pharmacy technician FTEs (p < 0.001). A total of 107 (85.6%) reported that grey market vendors have contacted hospital pharmacy personnel in the month of April, 2013. A total of 96 (76.8%) ‘strongly agreed’ that grey market vendors are more likely to contact health care facility when drug shortage exists, 110 (88%) ‘strongly agreed’ that grey market vendors sell drugs in short supply at inflated prices and 70 (56%) ‘strongly agreed’ that the practice of buying drug products from grey market vendors should be eliminated. In summary, all surveyed hospitals experienced at least one drug shortage for the month of April 2013, pharmacy personnel devoted a significant amount of time managing drug shortages and the majority of the hospitals were contacted by grey market vendors with the aim of selling drugs in short supply. / text
100

Understanding trans-basin floods in Germany : data, information and knowledge

Uhlemann, Steffi January 2013 (has links)
Large Central European flood events of the past have demonstrated that flooding can affect several river basins at the same time leading to catastrophic economic and humanitarian losses that can stretch emergency resources beyond planned levels of service. For Germany, the spatial coherence of flooding, the contributing processes and the role of trans-basin floods for a national risk assessment is largely unknown and analysis is limited by a lack of systematic data, information and knowledge on past events. This study investigates the frequency and intensity of trans-basin flood events in Germany. It evaluates the data and information basis on which knowledge about trans-basin floods can be generated in order to improve any future flood risk assessment. In particu-lar, the study assesses whether flood documentations and related reports can provide a valuable data source for understanding trans-basin floods. An adaptive algorithm was developed that systematically captures trans-basin floods using series of mean daily discharge at a large number of sites of even time series length (1952-2002). It identifies the simultaneous occurrence of flood peaks based on the exceedance of an initial threshold of a 10 year flood at one location and consecutively pools all causally related, spatially and temporally lagged peak recordings at the other locations. A weighted cumulative index was developed that accounts for the spatial extent and the individual flood magnitudes within an event and allows quantifying the overall event severity. The parameters of the method were tested in a sensitivity analysis. An intensive study on sources and ways of information dissemination of flood-relevant publications in Germany was conducted. Based on the method of systematic reviews a strategic search approach was developed to identify relevant documentations for each of the 40 strongest trans-basin flood events. A novel framework for assessing the quality of event specific flood reports from a user’s perspective was developed and validated by independent peers. The framework was designed to be generally applicable for any natural hazard type and assesses the quality of a document addressing accessibility as well as representational, contextual, and intrinsic dimensions of quality. The analysis of time-series of mean daily discharge resulted in the identification of 80 trans-basin flood events within the period 1952-2002 in Germany. The set is dominated by events that were recorded in the hydrological winter (64%); 36% occurred during the summer months. The occurrence of floods is characterised by a distinct clustering in time. Dividing the study period into two sub-periods, we find an increase in the percentage of winter events from 58% in the first to 70.5% in the second sub-period. Accordingly, we find a significant increase in the number of extreme trans-basin floods in the second sub-period. A large body of 186 flood relevant documentations was identified. For 87.5% of the 40 strongest trans-basin floods in Germany at least one report has been found and for the most severe floods a substantial amount of documentation could be obtained. 80% of the material can be considered grey literature (i.e. literature not controlled by commercial publishers). The results of the quality assessment show that the majority of flood event specific reports are of a good quality, i.e. they are well enough drafted, largely accurate and objective, and contain a substantial amount of information on the sources, pathways and receptors/consequences of the floods. The inclusion of this information in the process of knowledge building for flood risk assessment is recommended. Both the results as well as the data produced in this study are openly accessible and can be used for further research. The results of this study contribute to an improved spatial risk assessment in Germany. The identified set of trans-basin floods provides the basis for an assessment of the chance that flooding occurs simultaneously at a number of sites. The information obtained from flood event documentation can usefully supplement the analysis of the processes that govern flood risk. / Abschätzungen zum Hochwasserrisiko beschränken sich zumeist auf die Analyse innerhalb eines Einzugsgebietes bzw. eines bestimmten Ortes. Die Zusammenhänge in größeren Regionen und vor allem Korrelationen zwischen verschiedenen Einzugsgebieten werden nur selten betrachtet. Solche einzugsgebietsübergreifenden Analysen sind jedoch sowohl für die Versicherungswirtschaft, den Katastrophenschutz sowie für großräumige strategische Hochwasserplanungen notwendig. Allerdings stehen nur für eine geringe Auswahl historischer Ereignisse Daten zur Verfügung und systematische Ansätze zu ihrer Erfassung wurden für Deutschland bisher nicht entwickelt. Die vorliegende Studie untersucht zum ersten die Häufigkeit und Intensität von flussgebietsübergreifenden Hochwasserereignissen in Deutschland anhand von gemessenen Abflüssen an einer Vielzahl von Stationen. Es können insgesamt 80 Hochwasserereignisse in Deutschland im Zeitraum von 1952-2002 nachgewiesen werden. Davon treten die meisten Ereignissen im hydrologischen Winterhalbjahr auf (64%). Wir können nachweisen, dass die Häufigkeit des Auftretens in verschiedenen Perioden unterschiedlich ist, und dass im Untersuchungszeitraum eine signifikante Zunahme von Winterereignissen und damit vor allem von sehr schweren flussgebietsübergreifenden Hochwasserereignissen zu verzeichnen ist. Die Studie hatte des Weiteren zum Ziel, die verfügbare Daten- und Informationsgrundlage zur Hochwasseranalyse zu erkunden. Im speziellen wird untersucht, inwieweit Hochwasserereignisdokumentationen und verwandte Berichte als eine weitere Datenquelle für ein verbessertes Prozessverständnis genutzt werden können. Im Rahmen einer systematischen Suche konnten für die 40 größten Hochwasserereignisse in Deutschland 186 relevante Berichte identifiziert werden. 80% des Materials kann als Grauliteratur eingestuft werden, d.h. als Veröffentlichungen welche nicht durch kommerzielle Verleger publiziert wird. Die sich daraus ergebende Frage nach der Qualität der Dokumente und ihres Informationsgehaltes wurde durch die Entwicklung und Anwendung eines Qualitätsbewertungsschemas beantwortet. Die Ergebnisse der Qualitätsbewertung zeigen, dass die Mehrheit der ereignisspezifischen Hochwasserberichte von guter Qualität ist, d.h. die Berichte sind in ausreichender Qualität verfasst, größtenteils korrekt und objektiv und beinhalten eine substantielle Menge an Informationen zu den Ursachen, Verläufen, betroffenen Objekten und Schäden eines Ereignisses. Es wird empfohlen diese Informationen in die Wissenssynthese für die Hochwasserrisikobewertung einfließen zu lassen. Sowohl Ergebnisse als auch Daten dieser Studie sind so publiziert, dass sie öffentlich zugänglich sind und für weitere Forschungsfragen genutzt werden können.

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