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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.
11

Analysis of a novel low-cost solar concentrator using lunar flux mapping techniques and ray-tracing models

Roosendaal, Casey January 2020 (has links)
Concentrated solar power is a growing but expensive alternative energy resource. One of the most common issues faced when it comes to solar dish design is the complex trade-off between cost and optical quality. A novel solar dish reflector setup that makes use of low-cost, commercial television satellite dishes to support aluminised plastic membranes in a multifaceted vacuum-membrane concentrator was investigated in this work. The design aims to reduce costs while maintaining high optical accuracy with the added benefit of optical adjustability. The flux distribution of the novel solar dish reflector setup had to be determined to make recommendations on the feasibility of the design. This research presents a method to determine the expected solar flux distribution from lunar tests using a Canon EOS 700D camera. Experimental tests and different pollution treatment methods were conducted using lunar flux mapping techniques. A numerical model of the experimental setup, based on photogrammetry results of the membrane surface, was also developed in SolTrace to ascertain the sources of error and allow for further design improvements. Preliminary testing proved that JPEG image formats yielded insufficient accuracy in capturing the incident flux when compared to RAW images. Based on the flux ratio maps, the intercept factor for a large multifaceted dish setup was calculated as 88.6% for an aperture size of 0.25 m × 0.25 m, with a maximum solar flux of 1 395 kW/m2 for a 1 000 W/m2 test case. / Dissertation (MSc (Mechanical Engineering))--University of Pretoria, 2020. / National Research Foundation (NRF) / Mechanical and Aeronautical Engineering / MSc (Mechanical Engineering) / Unrestricted
12

The role of antemortem images of diffuse idiopathic skeletal hyperostosis (DISH) in positive identification

Zamora, Alyssa C. 14 February 2022 (has links)
The present study aimed to test the accuracy of using diffuse idiopathic skeletal hyperostosis (DISH) to make positive identifications using the method of antemortem and postmortem radiographic comparison. An online survey was developed to evaluate whether DISH is a feature of the skeleton that can be used in radiographic image comparison. Three digital radiographic images from 51 individuals were gathered for use in this study: one image taken at a baseline date (Group A), one image taken within 2 years from baseline (Group B), and one image taken greater than 4.5 years from baseline (Group C). A total of 40 survey participants were tasked with comparing between a simulated “antemortem” image and a “postmortem” image from living patients and identifying which image pair represented the same individual at different time intervals. Information about survey participants’ field, degree, experience working with radiographs, and familiarity with DISH were also recorded. Accuracy, sensitivity, and specificity were measured. Series 1 compared Group A images to Group B images and resulted in an accuracy of 87.3%, sensitivity of 46.9%, and specificity of 94.3%. Series 2 compared Group A images to Group C images and resulted in an accuracy of 83.4%, sensitivity of 34.3%, and specificity of 95.8%. The study concluded that the characteristics of DISH did not prove reliable for making positive identifications but established that DISH could be used to narrow down potential matches.
13

Back to the beginning: identifying lesions of diffuse idiopathic skeletal hyperostosis before vertebral ankylosis

Castells Navarro, Laura, Buckberry, Jo 06 January 2020 (has links)
Yes / Objective: To better understand the pathogenesis of DISH, identifying early or pre-DISH lesions in the spine and investigating the relationship between spinal and extra-spinal manifestations of DISH. Material: 44 skeletonized individuals with DISH from the WM Bass Donated Skeletal Collection. Methods: For each vertebra, location, extension, point of origin and appearance of vertebral outgrowths were recorded. The size of the enthesophytes at the olecranon process, patella and calcaneal tuberosity was measured with digital callipers. Results: At either end of the DISH-ankylosed segment, isolated vertical outgrowths arising from the central third of the anterior aspect of the vertebral body can usually be observed. These bone outgrowths show a well-organized external cortical layer, an internal structure of trabecular bone and usually are unaccompanied by or show minimal associated endplate degeneration. Analysis of the relationship between spinal and extra-spinal manifestations (ESM) suggests great inter-individual variability. No correlation between any ESM and the stage of spinal DISH was found. Conclusions: Small isolated outgrowths represent the earliest stages of the spinal manifestations of DISH. The use of ESM as an indicator of DISH should be undertaken with great caution until the relationship between these two features is understood. Significance: Improved accuracy of paleopathological diagnostic criteria of DISH. Limitations: Small sample comprised of only individuals with DISH. Future research: micro-CT analysis to investigate the internal structure of the spinal lesions. Analysis of extra-spinal enthesophytes in individuals with and without DISH to understand their pathogenesis and association with the spinal lesions in individuals with DISH. / Institute of Life Sciences Research Studentship awarded by the University of Bradford, Bradford, UK.
14

An isotope signature for diffuse idiopathic skeletal hyperostosis?

Castells Navarro, Laura, Buckberry, Jo, Beaumont, Julia 14 March 2022 (has links)
Yes / Objectives: Diffuse idiopathic skeletal hyperostosis (DISH) has recurrently been associated with a rich diet (high in protein and higher trophic level foods); however, very few studies have investigated this link using carbon and nitrogen (δ13C and δ15N) stable isotope analysis. This paper explores the relationship between DISH and diet in two Roman urban communities by analyzing individuals with and without DISH. Materials and methods: δ13C and δ15N analysis carried out on collagen from 33 rib samples (No DISH: 27; early DISH: 4; DISH: 2) selected from individuals buried at the Romano-British site of Baldock (UK), 41 rib samples (No DISH: 38; early DISH: 3) from individuals from the Catalan Roman site of Santa Caterina (Barcelona, Spain). Additionally, six faunal samples from Baldock and seven from Santa Caterina were analyzed. Results: Standardized human isotope data from Santa Caterina show high δ15N probably associated to a diet combining terrestrial resources and freshwater fish. In contrast, isotope results from Baldock suggest a terrestrial-based diet. Individuals with DISH do not show isotopic ratios indicative of rich diet and there is no correlation between stage of DISH development and δ13C and δ15N. Conclusion: The results of this study suggest that individuals with DISH followed a similar or isotopically similar diet as those individuals without DISH in Baldock and in Santa Caterina and therefore, while DISH may have been influenced by individual's dietary habits, this is not reflected in their isotopic signature. / Institute of Life Sciences Research Studentship, University of Bradford, Bradford, UK
15

A Problem Solving Approach to Enterprise FileVault 2 Management and Integration

Cobb, Nicholas 01 December 2013 (has links)
Consumer technology adoption into large enterprise environments is occurring at an unprecedented rate. Employees require the flexibility and efficiency of using operating systems, computers, and mobility products they are familiar with and that enable their productivity. Due to this industry phenomenon, one large shipping enterprise must work to create solutions to integrate Apple’s OS X operating system into its traditional Windows-based operating environment. This level of integration must take place carefully to enable usability and foster the continued data security of enterprise assets. This paper describes the steps and methodology taken, as well as the rationale used, to accomplish the task of integrating Apple’s FileVault 2 full disk encryption technology into existing McAfee management infrastructure and traditional deployment and support workflows. Using a combination of industry and community solutions and techniques, a low-cost software solution named EscrowToEPO is created to facilitate the secure and user-friendly adoption of FileVault 2 as a full disk encryption solution. This paper also includes the success/failure rate of adoption and implications as to how the adoption of similar solutions can occur to support future operating systems or other environments.
16

Volumetric Solar Receiver for a Parabolic Dish and Micro-Gas Turbine system : Design, modelling and validation using Multi-Objective Optimization

Mancini, Roberta January 2015 (has links)
Concentrated Solar Power (CSP) constitutes one suitable solution for exploiting solar resources for power generation. In this context, parabolic dish systems concentrate the solar radiation onto a point focusing receiver for small-scale power production. Given the modularity feature of such system, the scale-up is a feasible option; however, they offer a suitable solution for small scale off-grid electrification of rural areas. These systems are usually used with Stirling engines, nevertheless the coupling with micro-gas turbines presents a number of advantages, related to the reliability of the system and the lower level of maintenance required. The OMSoP project, funded by the European Union, aims at the demonstration of a parabolic dish coupled with an air-driven Brayton cycle. By looking at the integrated system, a key-role is played by the solar receiver, whose function is the absorption of the concentrated solar radiation and its transfer to the heat transfer fluid. Volumetric solar receivers constitute a novel and promising solution for such applications; the use of a porous matrix for the solar radiation absorption allows reaching higher temperature within a compact volume, while reducing the heat transfer losses between the fluid and the absorption medium. The aim of the present work is to deliver a set of optimal design specifications for a volumetric solar receiver for the OMSoP project. The work is based on a Multi-Objective Optimization algorithm, with the objective of the enhancement of the receiver thermal efficiency and of the reduction of the pressure drop. The optimization routine is coupled with a detailed analysis of the component, based on a Computational Fluid Dynamics model and a Mechanical Stress Analysis. The boundary conditions are given by the OMSoP project, in terms of dish specifications and power cycle, whilst the solar radiation boundary is modelled by means of a Ray Tracing routine. The outcome of the analysis is the assessment of the impact on the receiver performance of some key design parameters, namely the porous material properties and the receiver geometrical dimensions. From the results, it is observed a general low pressure drop related to the nominal air mass flow, with several points respecting the materials limitations. One design point is chosen among the optimal points, which respects the OMSoP project requirements for the design objectives, i.e. a minimum value of efficiency of 70%, and pressure losses below 1%. The final receiver configuration performs with an efficiency value of 86%, with relative pressure drop of 0.5%, and it is based on a ceramic foam absorber made of silicon carbide, with porosity value of 0.94.  Moreover, the detailed analysis of one volumetric receiver configuration to be integrated in the OMSoP project shows promising results for experimental testing and for its actual integration in the system.
17

Multicentric osteosarcoma associated with DISH, in a 19th Century burial from England.

Ortner, D.J., Ponce, P., Ogden, Alan R., Buckberry, Jo January 2010 (has links)
No / Osteosarcoma is a rare type of malignant neoplasm that is most frequent in adolescents and young adults although it can develop at any age. It can metastasize from a primary site in bone to other bones and soft tissues. Usually the disorder causes a single bone-forming lesion (unicentric) but some cases have multicentric, bone-forming lesions. Some of these lesions develop at different sites at different times. In a second variant of multicentric osteosarcoma, synchronous bone-forming lesions develop at multiple sites. Distinguishing between these two types of multicentric osteosarcoma is challenging in a clinical context and the criteria for doing so are unlikely to be met in an archaeological burial. Wolverhampton burial HB 39 was excavated from an early-nineteenth century cemetery site in England. It consists of the incomplete skeleton of an adult male of at least 45 years of age with multicentric osteosarcoma. The individual represented by this burial also had diffuse idiopathic skeletal hyperostosis (DISH). Three of the bone-forming lesions associated with osteosarcoma developed on the bony outgrowths related to DISH.
18

Real-Time Dish Detection and Counting System for School Dining Halls Using Embedded CNNs

Mohamad, Baker, Habeb, Mustafa January 2024 (has links)
School cafeterias face significant challenges in maintaining operational efficiency while minimizing food waste within the educational sector. Currently, the methods available for counting dishes are predominantly manual or semi-manual. Accurately counting served plates is crucial for evaluating meal portions and planning food preparation, yet these methods frequently result in inaccuracies and inefficiencies. To address these challenges, this project introduces an innovative automated system for counting washed dishes used in the school’s dining hall. The system employs embedded systems equipped with a proper machine learning model to detect dishes placed in trays and count them at the washing station in the kitchens of schools. By automating the dish counting process, the system improves operational efficiency, reduces food waste, and provides precise data for meal planning, inventory management, and budget planning. Initial results show promising accuracy and efficiency, with the best model achieving an average precision of 0.71, a precision of 95.2%, and a recall of 70.5% using Google Cloud’s AutoML platform. However, further optimization is needed for real-world deployment. This project is constrained by limited time for labeling images and a budget of 300$. This project represents a collaboration between Linnaeus University, Kalmar Municipality, and SensIot Company, reflecting a shared commitment to sustainability through reduced food waste in educational institutions.
19

Modeling, simulation, and analysis of grid connected dish-stirling solar power plants

Howard, Dustin F. 07 July 2010 (has links)
The percentage of renewable energy within the global electric power generation portfolio is expected to increase rapidly over the next few decades due to increasing concerns about climate change, fossil fuel costs, and energy security. Solar thermal energy, also known as concentrating solar power (CSP), is emerging as an important solution to new demands for clean, renewable electricity generation. Dish-Stirling (DS) technology, a form of CSP, is a relatively new player in the renewable energy market, although research in the technology has been ongoing now for nearly thirty years. The first large plant utilizing DS technology, rated at 1.5 MW, came online in January 2010 in Peoria, AZ, and plants rated for several hundred MW are in the planning stages. Increasing capacity of this technology within the utility grid requires extensive dynamic simulation studies to ensure that the power system maintains its safety and reliability in spite of the technological challenges that DS technology presents, particularly related to the intermittency of the energy source and its use of a non-conventional asynchronous generator. The research presented in this thesis attempts to fill in the gaps between the well established research on Stirling engines in the world of thermodynamics and the use of DS systems in electric power system applications, a topic which has received scant attention in publications since the emergence of this technology. DS technology uses a paraboloidal shaped dish of mirrors to concentrate sunlight to a single point. The high temperatures achieved at the focal point of the mirrors is used as a heat source for the Stirling engine, which is a closed-cycle, external heat engine. Invented by the Scottish clergyman Robert Stirling in 1816, the Stirling engine is capable of high efficiency and releases no emissions, making it highly compatible with concentrated solar energy. The Stirling engine turns a squirrel-cage induction generator, where electricity is delivered through underground cables from thousands of independent, autonomous 10-25 kW rated DS units in a large solar farm. A dynamic model of the DS system is presented in this thesis, including models of the Stirling engine working gas and mechanical dynamics. Custom FORTRAN code is written to model the Stirling engine dynamics within PSCAD/EMTDC. The Stirling engine and various other components of the DS system are incorporated into an electrical network, including first a single-machine, infinite bus network, and then a larger 12-bus network including conventional generators, loads, and transmission lines. An analysis of the DS control systems is presented, and simulation results are provided to demonstrate the system's steady state and dynamic behavior within these electric power networks. Potential grid interconnection requirements are discussed, including issues with power factor correction and low voltage ride-through, and simulation results are provided to illustrate the dish-Stirling system's capability for meeting such requirements.
20

Lužní tóny - dekorovaná keramika inspirovaná krajinnými motivy / Floodplain tones - decorated ceramics inspired by landscape motives

HODONSKÁ, Jana January 2010 (has links)
This thesis deals with the issue of collection of ceramic solitary dishes, which are decorated with colour pigments with landscape motives. Five individual objects, variable in shape, which form one complete set. These are five records of floodplain landscape, vineyards and fluvial forests. This thesis aims at connection between wall painting and ceramic material, connection of utility and free creation. The introduction is devoted to the theoretical knowledge; the second part develops technological and practical skills.

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