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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.
81

Optimising camera trap density and position to determine medium and large mammal species richness and occupancy on the Cape Peninsula, South Africa

Colyn, Robin January 2016 (has links)
Thesis (MTech (Nature Conservation))--Cape Peninsula University of Technology, 2016. / Largely due to anthropogenic causes, biodiversity and particularly species diversity is changing at an extraordinary rate, with declines in species abundance, community composition and extinction risk being of crucial concern. Monitoring of state variables of biodiversity such as species richness and occupancy are of significant importance in determining the severity of threats placed on species, populations and communities. As a non-invasive monitoring method camera traps are noted as being an effective, accurate and rapid means of compiling species richness estimates of medium to large terrestrial mammals. However, crucial elements of camera trap survey design are rarely empirically addressed, which has questioned the need for a standardised camera trapping protocol. Table Mountain National Park (TMNP) is a protected area that is under serious anthropogenic pressure through urban and peri-urban development. Although it is the last refuge for a number of large mammal species on the Cape Peninsula, current mammalian species richness knowledge within the TMNP are limited. Accurate and current species richness estimates are therefore needed within TMNP and more specifically the Cape of Good Hope (CoGH), which exclusively hosts a number of medium and large mammal species. The aims of this study were to optimise a camera survey protocol for the Peninsula region, with a focus on camera density, placement and survey duration that will enable accurate estimations of medium to large mammal species richness and occupancy.
82

Distributed Cross-layer Monitoring in Wireless Mesh Networks

Panmin, Ye, Yong, January 2009 (has links)
No description available.
83

Tools for environmental statistics : creative visualization and estimating variance from complex surveys

Courbois, Jean-Yves Pip 07 January 2000 (has links)
Environmental monitoring poses two challenges to statistical analysis: complex data and complex survey designs. Monitoring for system health involves measuring physical, chemical, and biological properties that have complex relations. Exploring these relations is an integral part of understanding how systems are changing under stress. How does one explore high dimensional data? Many of our current methods rely on "black-box" mathematical methods. Visualization techniques on the other hand are either restricted to low dimensions or hopelessly out of context. The first topic explored in this dissertation suggests a direct search method for use in projection pursuit guided tours. In Chapter 2 a direct search method for index optimization, the multidirectional pattern search, was explored for use in projection pursuit guided tours. The benefit of this method is that it does not require the projection pursuit index to be continuously differentiable; in contrast to existing methods that require differentiability. Computational comparisons with test data revealed the feasibility and promise of the method. It successfully found hidden structure in 4 of 6 test data sets. The study demonstrates that the direct search method lends itself well to use in guided tours and allows for non-differentiable indices. Evaluating estimators of the population variance is covered in Chapter 3. Good estimates of the population variance are useful when designing a survey. These estimates may come from a pilot project or survey. Often in environmental sampling simple random sampling is not possible;�� instead complex designs are used. In this case there is no clear estimator for the population variance. We propose an estimator that is (1) based on a methods of moments approach and (2) extendible to more complex variance component models. Several other estimators have been proposed in the literature. This study compared our method of moment estimator to other variance estimators. Unfortunately our estimator did not do as well as some of the other estimators that have been suggested implying that these estimators do not perform similarly as the literature suggests they do. Two estimators, the sample variance and a ratio estimator based on the Horvitz-Thompson Theorem and a consistency argument, proved to be favorable. / Graduation date: 2000
84

Distributed Cross-layer Monitoring in Wireless Mesh Networks

Panmin, Ye, Yong, January 2009 (has links)
No description available.
85

A structural health monitoring system for composite pressure vessels

Lung, Bryan C. 11 April 2005
<p>Vehicles that run on compressed natural gas and hydrogen are currently being developed to reduce greenhouse gas emissions and smog. To meet the need for a safe, reliable fuel storage system, a low-cost, acoustic-ultrasonic system has been developed to detect damage in high-pressure storage cylinders made of Carbon Fiber Reinforced Polymers (CFRP). This structural health monitoring system could lead to lighter, lower cost cylinders, and improved safety in automotive applications that utilize hydrogen and natural gas.</p><p>Several Non-Deconstructive Evaluation (NDE) techniques were investigated in the course of this work, and low-cost piezo-film sensors were selected to monitor the cylinder. These sensors were integrated into the carbon fiber structure, resulting in a sensor network that can be used for real-time structural health monitoring of composite cylinders. The system was operated by exciting the piezo-film sensors with an impulse and then the corresponding structural response (or signature) was measured and analyzed. This was compared to a previously measured response and evaluated for changes which can indicate failures in the tank. The analysis reduces the changes in the structural response to a single damage coefficient, which can then be used for malfunction indication and decision making in an automotive on-board microprocessor control system.</p><p>The technology can be deployed at a reasonable cost, and has been designed to accurately detect damage with little or no maintenance required. Thirty cylinders were used in a test matrix to examine all possible failure mechanisms of the tanks, including: fatigue, cuts and gouges, impact and delaminations, stress rupture, heat damage, and combinations of these damage mechanisms. The damage detection system was capable of detecting damage long before a critical condition arose for all cases. However, further development and testing into larger cylinder designs and testing is still required to develop a final commercial product.
86

The influence of thermal effects on structural health monitoring of Attridge Drive overpass

Pham, Tuan Anh 28 October 2009
Structural Health Monitoring (SHM) comprises a wide range of techniques for the condition and damage assessment of an existing structure. Vibration-based damage detection (VBDD) techniques, a class of SHM methods, use changes in the dynamic properties (i.e., natural frequencies, mode shapes and damping characteristics) of structures to detect deterioration or damage. The application of VBDD methods to simple structures in a well-controlled laboratory environment has gained some successful results. However, the practical field application of VBDD still faces significant challenges since vibration measurement is subject to the influences of high levels of uncertainty in environmental, structural and loading conditions. In this thesis, the influence of temperature variations on the application of VBDD methods to an in-service complex structure was experimentally and numerically studied. The structure studied was the Attridge Drive overpass in Saskatoon, Saskatchewan.<p> The main objective of this research was to assess the influence of temperature variation on the dynamic properties (natural frequencies and mode shapes) of the overpass, and on the ability of VBDD methods to detect and locate damage. Field dynamic measurements were made on the bridge on numerous occasions under a wide variety of ambient temperatures, using high sensitivity accelerometers and a temperature sensor. Dynamic excitation was provided solely by ambient traffic loading.<p> Finite element models of the overpass were also created and manually calibrated to measured field data. The models were used to simulate the dynamic behaviour of the bridge at a variety of temperatures and under various states of small-scale damage. Numerical analysis was conducted to study the effect of ambient temperature on structures dynamic characteristics and to differentiate the patterns of mode shape changes caused by damage and ambient temperature. It was concluded that the change of ambient temperature mainly affects the elastic modulus of the construction materials and therefore stiffness of the entire bridge. As a result, the eigenfrequencies and mode shapes of the structure are influenced.<p> The dynamic properties extracted from measured experiment data showed an approximately bilinear relationship between the three first natural frequencies and the ambient temperature. The natural frequencies for all three modes increased when the temperature fell.<p> It was also found that, conceptually, it is possible to distinguish the patterns of mode shape changes caused by small-scale damage from those due to thermal effects, but only if a sufficient number of sensors are used to measure the mode shapes; in addition, those sensors must be located close to the damage location.
87

Monitoring and loggingsystem for home use. : An 8-bit approach.

Peredera, Dmitri January 2011 (has links)
The thesis discusses the creation and implementation of a monitoring and notificationsystem for home use. The topic may have interest during the warm Swedish summer andlong winter nights, when the weather conditions put home flora to the test. The vividimagination together with a life-long experience of the author predicts a total devastation ofgreen plants inside the apartment. A more general approach will allow tracking e.g. of livinghabits and notification of important events like mail arrival.The paper discusses a power management of devices, wireless and wired communicationand data storage on embedded 8-bit microcontroller manufactured by Microchip. A simpleanalysis of price, performance and memory requirements is done. The practicalimplementation of the prototype suffered somewhat from lack of lab space and otherlimitations of the home environment, where the device was assembled.The achieved results suggest the possibility of such realization. However, the realization hasincluded major changes compared to the originally envisioned device, in order to keepwithin the limits brought on by the home environment.The prototype has some design flaws and is a subject to further revision. Nevertheless, thebasic idea and solution have proved to be feasible: A modern 8-bit MCU has the capacity torun the intended kind of monitoring and logging system. However the performance is slightlyless than hoped for and the experienced memory limitations may suggest a migration to a16-bit architecture.
88

A structural health monitoring system for composite pressure vessels

Lung, Bryan C. 11 April 2005 (has links)
<p>Vehicles that run on compressed natural gas and hydrogen are currently being developed to reduce greenhouse gas emissions and smog. To meet the need for a safe, reliable fuel storage system, a low-cost, acoustic-ultrasonic system has been developed to detect damage in high-pressure storage cylinders made of Carbon Fiber Reinforced Polymers (CFRP). This structural health monitoring system could lead to lighter, lower cost cylinders, and improved safety in automotive applications that utilize hydrogen and natural gas.</p><p>Several Non-Deconstructive Evaluation (NDE) techniques were investigated in the course of this work, and low-cost piezo-film sensors were selected to monitor the cylinder. These sensors were integrated into the carbon fiber structure, resulting in a sensor network that can be used for real-time structural health monitoring of composite cylinders. The system was operated by exciting the piezo-film sensors with an impulse and then the corresponding structural response (or signature) was measured and analyzed. This was compared to a previously measured response and evaluated for changes which can indicate failures in the tank. The analysis reduces the changes in the structural response to a single damage coefficient, which can then be used for malfunction indication and decision making in an automotive on-board microprocessor control system.</p><p>The technology can be deployed at a reasonable cost, and has been designed to accurately detect damage with little or no maintenance required. Thirty cylinders were used in a test matrix to examine all possible failure mechanisms of the tanks, including: fatigue, cuts and gouges, impact and delaminations, stress rupture, heat damage, and combinations of these damage mechanisms. The damage detection system was capable of detecting damage long before a critical condition arose for all cases. However, further development and testing into larger cylinder designs and testing is still required to develop a final commercial product.
89

The influence of thermal effects on structural health monitoring of Attridge Drive overpass

Pham, Tuan Anh 28 October 2009 (has links)
Structural Health Monitoring (SHM) comprises a wide range of techniques for the condition and damage assessment of an existing structure. Vibration-based damage detection (VBDD) techniques, a class of SHM methods, use changes in the dynamic properties (i.e., natural frequencies, mode shapes and damping characteristics) of structures to detect deterioration or damage. The application of VBDD methods to simple structures in a well-controlled laboratory environment has gained some successful results. However, the practical field application of VBDD still faces significant challenges since vibration measurement is subject to the influences of high levels of uncertainty in environmental, structural and loading conditions. In this thesis, the influence of temperature variations on the application of VBDD methods to an in-service complex structure was experimentally and numerically studied. The structure studied was the Attridge Drive overpass in Saskatoon, Saskatchewan.<p> The main objective of this research was to assess the influence of temperature variation on the dynamic properties (natural frequencies and mode shapes) of the overpass, and on the ability of VBDD methods to detect and locate damage. Field dynamic measurements were made on the bridge on numerous occasions under a wide variety of ambient temperatures, using high sensitivity accelerometers and a temperature sensor. Dynamic excitation was provided solely by ambient traffic loading.<p> Finite element models of the overpass were also created and manually calibrated to measured field data. The models were used to simulate the dynamic behaviour of the bridge at a variety of temperatures and under various states of small-scale damage. Numerical analysis was conducted to study the effect of ambient temperature on structures dynamic characteristics and to differentiate the patterns of mode shape changes caused by damage and ambient temperature. It was concluded that the change of ambient temperature mainly affects the elastic modulus of the construction materials and therefore stiffness of the entire bridge. As a result, the eigenfrequencies and mode shapes of the structure are influenced.<p> The dynamic properties extracted from measured experiment data showed an approximately bilinear relationship between the three first natural frequencies and the ambient temperature. The natural frequencies for all three modes increased when the temperature fell.<p> It was also found that, conceptually, it is possible to distinguish the patterns of mode shape changes caused by small-scale damage from those due to thermal effects, but only if a sufficient number of sensors are used to measure the mode shapes; in addition, those sensors must be located close to the damage location.
90

Scaling Continuous Query Services for Future Computing Platforms and Applications

Gedik, Bugra 13 June 2006 (has links)
The ever increasing rate of digital information available from on-line sources drives the need for building information monitoring applications to assist users in tracking relevant changes in these sources and accessing information that is of interest to them in a timely manner. Continuous queries (CQs) are standing queries that are continuously evaluated over dynamic sources to track information changes that meet user specified thresholds and notify users of new results in real-time. CQ systems can be considered as powerful middleware for supporting information monitoring applications. A significant challenge in building CQ systems is scalability, caused by the large number of users and queries, and by the large and growing number of information sources with high update rates. In this thesis we use CQs to shepherd through and address the challenges involved in supporting information monitoring applications in future computing platforms. The focus is on P2P web monitoring in Internet systems, location monitoring in mobile systems, and environmental monitoring in sensor systems. Although different computing platforms require different software architectures for building scalable CQ services, there is a common design philosophy that this thesis advocates for making CQ services scalable and efficient. This can be summarized as "move computation close to the places where the data is produced." A common challenge in scaling CQ systems is the resource-intensive nature of query evaluation, which involves continuously checking updates in a large number of data sources and evaluating trigger conditions of a large number of queries over these updates, consuming both cpu and network bandwidth resources. If some part of the query evaluation can be pushed close to the sources where the data is produced, the resulting early filtering of updates will save both bandwidth and cpu resources. In summary, in this thesis we show that distributed CQ architectures that are designed to take advantage of the opportunities provided by ubiquitous computing platforms and pervasive networks, while at the same time recognizing and resolving the challenges posed by these platforms, lead to building scalable and effective CQ systems to better support the demanding information monitoring applications of the future.

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