Emittance growth in linear induction accelerators

The Dual-Axis Radiographic Hydrotest (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT Axis-II LIA we measure an emittance higher than predicted by theoretical simulations, and even though this axis produces sub-millimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell (PIC) codes, although most of these are discounted based on beam measurements. The most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.Comment: 20th Int. Conf. on High-Power Particle Beams, Washington, DC, May, 201

Efficient Parallel and Distributed Algorithms for GIS Polygon Overlay Processing

Polygon clipping is one of the complex operations in computational geometry. It is used in Geographic Information Systems (GIS), Computer Graphics, and VLSI CAD. For two polygons with n and m vertices, the number of intersections can be O(nm). In this dissertation, we present the first output-sensitive CREW PRAM algorithm, which can perform polygon clipping in O(log n) time using O(n + k + k\u27) processors, where n is the number of vertices, k is the number of intersections, and k\u27 is the additional temporary vertices introduced due to the partitioning of polygons. The current best algorithm by Karinthi, Srinivas, and Almasi does not handle self-intersecting polygons, is not output-sensitive and must employ O(n^2) processors to achieve O(log n) time. The second parallel algorithm is an output-sensitive PRAM algorithm based on Greiner-Hormann algorithm with O(log n) time complexity using O(n + k) processors. This is cost-optimal when compared to the time complexity of the best-known sequential plane-sweep based algorithm for polygon clipping. For self-intersecting polygons, the time complexity is O(((n + k) log n log log n)/p) using p In addition to these parallel algorithms, the other main contributions in this dissertation are 1) multi-core and many-core implementation for clipping a pair of polygons and 2) MPI-GIS and Hadoop Topology Suite for distributed polygon overlay using a cluster of nodes. Nvidia GPU and CUDA are used for the many-core implementation. The MPI based system achieves 44X speedup while processing about 600K polygons in two real-world GIS shapefiles 1) USA Detailed Water Bodies and 2) USA Block Group Boundaries) within 20 seconds on a 32-node (8 cores each) IBM iDataPlex cluster interconnected by InfiniBand technology

Effect of solar heat flux and thermal loading on the flow distribution within the riser pipes of a closed-loop solar thermo-syphon hot water system

Solar energy is one of the main sources of renewable energy that is abundantly available throughout the world. Solar energy can be used for useful purposes through a number of mechanical artefacts. One such artefact is known as Thermo-syphon, which typically contains water as its working fluid. One of the major applications of Thermo-syphon is within the residential and industrial units, where a constant supply of hot water is required. The use of Computational Fluid Dynamics (CFD) based solvers has recently been proven capable of predicting the flow behaviour within thermo-syphons with reasonable accuracy. Hence, the present study focuses on using a commercial CFD based solver to predict the flow behaviour within the riser pipes of a thermo-syphon with varying solar heat flux and thermal loading conditions. In order to qualitatively and quantitatively analyse the flow structure within the riser pipes of the thermo-syphon, velocity magnitude and static temperature distributions within these pipes is analysed in detail. The results depict that the solar heat flux has a significant impact on the velocity magnitude and static temperature profiles within the riser pipes. Furthermore, it has been observed that the thermal loading has negligible effects on the velocity magnitude and static temperature profiles within the riser pipes. The data has also been used to develop novel design correlations

Numerical Investigations on the Effects of Transient Heat Input and Loading Conditions on the Performance of a Single-phase Closed-loop Thermo-syphon

One of the most important sources of renewable energy is solar energy, which is readily available throughout the world. There is a requirement to make the solar energy affordable for everyday use in order to minimise the present reliance on fossil fuels. This would also assist in meeting the requirements of limiting greenhouse-gas effects, and hence conserve the environment from pollution, global warming, ozone layer depletion, etc. Thermo-syphons are systems that capture solar energy using a working fluid. In the present study, Computational Fluid Dynamics based solver has been employed to carry out an extensive investigation on the performance analysis of a thermo-syphon operating under transient conditions. There has been limited research conducted on the transient performance of thermo-syphons. This study focuses on the effects of various heat flux inputs and thermal loading conditions on the performance of a closed-loop solar hot water thermo-syphon system. The study reveals that the effect of heat flux input on heat transfer coefficient is dominant as compared to thermal loading. The results provided here can be used to optimally design thermo-syphon systems. Furthermore, it has been demonstrated that Computational Fluid Dynamics can be used as an effective tool to analyse the performance of a thermo-syphon with reasonable accuracy

Utilizing GIS technology for brownfields redevelopment

Typically, when developers, banks and other organizations have an interest in a piece of property they perform an extensive information search to determine if the site is worth purchasing. This search could consist of tax and title information, the location of utilities and major roadways in the area, information on population demographics and environmental contaminant data. An information search of this type could take days, weeks or even months to compile. With a geographic information system (GIS), this search could take a matter of minutes and is displayed in an easy to understand graphic or map form along with a report. GIS technology is consequently changing the way economic development organizations, states and municipalities communicate with potential purchasers of properties. With GIS technology these organizations can select brownfields or other properties based on ownership, demographics and/or predetermined zoning criteria and market the properties based on the needs of the developer. This thesis will propose development blueprints for Brownfield Pilots to consider when implementing a GIS. These blueprints or recommended strategies will be based on accepted GIS development phases, case studies that involved developing GISs for economic development and environmental applications and on responses to a questionnaire sent to Brownfield Pilots to determine their GIS development techniques and implementation status

Design and Simulation of a Supervisory Control System for Hybrid Manufacturing

The research teams of Dr. Bill Hamel, Dr. Bradley Jared and Dr. Tony Schmitz were tasked by the Office of Naval Research to create a hybrid manufacturing process for a reduced scale model of a naval ship propeller. The base structure of the propeller is created using Wire Arc Additive Manufacturing (WAAM), which is then scanned to compare created geometry to desired geometry. The propeller is then machined down to match the desired geometry. This process is iterated upon until the final product meets design tolerances. Due to the complex nature and numerous industrial machines used in the process, it is desirable to create a control system for Supervisory Control and Data Acquisition (SCADA). This supervisory control system is necessary in order to ensure safe operations and logging of system data to document successful trials. The goal of this thesis is to outline the design and simulation of a supervisory control system for this hybrid manufacturing cell. The design and implementation is focused on a simulation of the control of relevant boolean states of the system. This is accomplished through a Human Machine Interface (HMI) created in LabVIEW accompanied by appropriate data flow diagrams, models and communication specifications between machines. The creation of a digital twin of this hybrid manufacturing system was successful and useful in the implementation of physical components

Effect of solar heat flux and thermal loading on the flow distribution within the riser pipes of a closed-loop solar thermo-syphon hot water system.

Solar energy is one of the main sources of renewable energy that is abundantly available throughout the world. Solar energy can be used for useful purposes through a number of mechanical artefacts. One such artefact is known as Thermo-syphon, which typically contains water as its working fluid. One of the major applications of Thermo-syphon is within the residential and industrial units, where a constant supply of hot water is required. The use of Computational Fluid Dynamics (CFD) based solvers has recently been proven capable of predicting the flow behaviour within thermo-syphons with reasonable accuracy. Hence, the present study focuses on using a commercial CFD based solver to predict the flow behaviour within the riser pipes of a thermo-syphon with varying solar heat flux and thermal loading conditions. In order to qualitatively and quantitatively analyse the flow structure within the riser pipes of the thermo-syphon, velocity magnitude and static temperature distributions within these pipes is analysed in detail. The results depict that the solar heat flux has a significant impact on the velocity magnitude and static temperature profiles within the riser pipes. Furthermore, it has been observed that the thermal loading has negligible effects on the velocity magnitude and static temperature profiles within the riser pipes. The data has also been used to develop novel design correlations

BEYOND ROOTS ALONE: NOVEL METHODOLOGIES FOR ANALYZING COMPLEX SOIL AND MINIRHIZOTRON IMAGERY USING IMAGE PROCESSING AND GIS TOOLS

Quantifying belowground dynamics is critical to our understanding of plant and ecosystem function and belowground carbon cycling, yet currently available tools for complex belowground image analyses are insufficient. We introduce novel techniques combining digital image processing tools and geographic information systems (GIS) analysis to permit semi-automated analysis of complex root and soil dynamics. We illustrate methodologies with imagery from microcosms, minirhizotrons, and a rhizotron, in upland and peatland soils. We provide guidelines for correct image capture, a method that automatically stitches together numerous minirhizotron images into one seamless image, and image analysis using image segmentation and classification in SPRING or change analysis in ArcMap. These methods facilitate spatial and temporal root and soil interaction studies, providing a framework to expand a more comprehensive understanding of belowground dynamics