Matching Items (519)
Description
The increase of transmission line thermal ratings by reconductoring with high temperature low sag conductors is a comparatively new technology introduced for transmission expansion. A special design permits high temperature low sag conductors to operate at higher temperatures, therefore allowing passage of higher current and, thus, increasing the thermal rating of the transmission line. The comparatively high cost of high temperature low sag conductors may be an obstacle to its large-scale implementation. This article evaluates the expenditures for transmission line reconductoring using high temperature low sag, the consequent benefits obtained from the potential decrease in operating cost for thermally limited power transmission systems. Estimates of the “payback period” are used to evaluate the cost effectiveness of reconductoring with high temperature low sag. The evaluation is performed using a 225 bus equivalent of the 2012 summer peak Arizona portion of the Western Electricity Coordinating Council. The method is offered for transmission expansion analysis in which an economic benefit is calculated to assist in the transmission expansion decision.
ContributorsTokombayev, Askhat (Author) / Heydt, Gerald (Author) / Ira A. Fulton Schools of Engineering (Contributor) / School of Electrical, Computer and Energy Engineering (Contributor)
Created2015-02-07
Description
Eigenvalues of the 3D critical point equation (∇u)ν = λν are normally computed numerically. In the letter, we present analytic solutions for 3D swirling strength in both compressible and incompressible flows. The solutions expose functional dependencies that cannot be seen in numerical solutions. To illustrate, we study the difference between using fluctuating and total velocity gradient tensors for vortex identification. Results show that mean shear influences vortex detection and that distortion can occur, depending on the strength of mean shear relative to the vorticity at the vortex center.
ContributorsChen, Huai (Author) / Adrian, Ronald (Author) / Zhong, Qiang (Author) / Wang, Xingkui (Author) / Ira A. Fulton Schools of Engineering (Contributor) / School for the Engineering of Matter, Transport and Energy (Contributor)
Created2014-08-01
Description
The flexural behavior of epoxies was investigated by performing mechanical tests and applying statistical Weibull theory and analytical methods to the results. The effects of loading systems and environmental conditions were also considered. Three kinds of epoxies were studied: Epon E863, PRI 2002, and PR520. In total, 53 three-point-bending (3PB) Epon E863 samples and 26 3PB PR520 were tested immediately after curing, together with 26 four-point-bending (4PB) PRI2002 samples stored at 60°C and 90% Rh for 48 weeks. The Weibull parameters were estimated using both linear regression and the moments method. The statistical character of the Weibull model leads to uncertainty in the evaluated parameters, even for a large number of experiments. This study analyzed the ratio of flexural strength to tensile strength in bulk epoxy resin polymers. An analytical method previously developed by the authors to study the relationship between uniaxial tension/compression stress-strain curves and flexural load-deflection response was used to obtain the ratio. The results show that the Weibull model overpredicted the aforementioned ratio in different load arrangements.
ContributorsYekani Fard, Masoud (Author) / Raji, B. (Author) / Chattopadhyay, Aditi (Author) / Ira A. Fulton Schools of Engineering (Contributor) / School for the Engineering of Matter, Transport and Energy (Contributor)
Created2014-12-01
Description
Identification of early damage in polymer composites is of great importance. We have incorporated cyclobutane-containing cross-linked polymers into an epoxy matrix, studied the effect on thermal and mechanical properties, and, more importantly, demonstrated early damage detection through mechanically induced fluorescence generation. Two cinnamate derivatives, 1,1,1-tris(cinnamoyloxymethyl) ethane (TCE) and poly(vinyl cinnamate) (PVCi), were photoirradiated to produce cyclobutane-containing polymer. The effects on the thermal and mechanical properties with the addition of cyclobutane-containing polymer into epoxy matrix were investigated. The emergence of cracks was detected by fluorescence at a strain level just beyond the yield point of the polymer blends, and the fluorescence intensified with accumulation of strain. Overall, the results show that damage can be detected through fluorescence generation along crack propagation.
ContributorsZou, Jin (Author) / Liu, Yingtao (Author) / Shan, Bohan (Author) / Chattopadhyay, Aditi (Author) / Dai, Lenore (Author) / Ira A. Fulton Schools of Engineering (Contributor) / School for the Engineering of Matter, Transport and Energy (Contributor)
Created2014-09-01
Description
The impact of increasing penetration of converter control-based generators (CCBGs) in a large-scale power system is assessed through a model based small signal stability analysis. Three test bed cases for the years 2010, 2020, and 2022 of the Western Electricity Coordinating Council (WECC) in the United States are used for the analysis. Increasing penetration of wind-based Type 3 and wind-based Type 4 and PV Solar CCBGs is used in the tests. The participation and interaction of CCBGs and synchronous generators in traditional electromechanical interarea modes is analyzed. Two new types of modes dominated by CCBGs are identified. The characteristics of these new modes are described and compared to electromechanical modes in the frequency domain. An examination of the mechanism of the interaction between the CCBG control states and the synchronous generator control states is presented and validated through dynamic simulations. Actual system and forecast load data are used throughout.
ContributorsQuintero, Jaime (Author) / Vittal, Vijay (Author) / Heydt, Gerald (Author) / Zhang, Hui (Author) / Ira A. Fulton Schools of Engineering (Contributor) / School of Electrical, Computer and Energy Engineering (Contributor)
Created2014-09-01
Description
The Physics and Chemistry of Surfaces and Interfaces conference has maintained a focus on the interfacial and surface properties of materials since its initiation in 1974. The conference continues to be a major force in this field, bringing together scientists from a variety of disciplines to focus upon the science of interfaces and surfaces. Here, a historical view of the development of the conference and a discussion of some of the themes that have been focal points for many years are presented.
ContributorsFerry, David (Author) / Ira A. Fulton Schools of Engineering (Contributor) / School of Electrical, Computer and Energy Engineering (Contributor)
Created2013
Description
The purpose of this thesis creative project was to create an educational video to present research findings on the increasingly important issue of human biospecimen preanalytic variables. When a human biospecimen, such as blood, urine, or tissue, is removed from the body, it is subjected to a plethora of variables that are not recorded or regulated in a vast majority of cases. Frequently, these samples arrive at the research or pathology lab with an unknown history, then undergo analysis for translational research purposes, or to guide clinical management decisions. Thus, compromised specimen quality caused by preanalytic variables has substantial, and potentially devastating, downstream effects. To identify the preanalytic variables with the greatest impact on blood and tissue specimen quality, 45 articles were gathered using PubMed and Google Scholar databases and cited. Based on the articles, the top five variables with the most detrimental effects were identified for both blood and tissue samples. Multiple sets of parameters ensuring specimen fitness were compared for each of the five variables for each specimen type. Then, specific parameters guaranteeing the fitness of the greatest number of analytes were verified. To present the research findings in greater detail, a paper was written that focused on identifying the top variables and key parameters to ensure analyte fitness. To present the overall issue in an easy-to-digest format, a storyboard and script were created as a guideline for a final video project. Ultimately, two alternate versions of the video were created to pertain to the audience of choice (one version for patients, one version for professionals). It is the hope that these videos will be used as educational tools to continue efforts to standardize and enforce human biospecimen preanalytic variable parameters. This is a necessary step to improve the accuracy of our biomedical research data and the healthcare of patients worldwide.
ContributorsAzcarate, Heather (Author) / Compton, Carolyn (Thesis director) / LaBaer, Joshua (Committee member) / Borges, Chad (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor)
Created2018-12
Description
Cleavage and polyadenylation is a step in mRNA processing in which the 3’UTR is cleaved and a polyA tail is added to create a final mature transcript. This process relies on RNA sequence elements that guide a large multimeric protein complex named the Cleavage and Polyadenylation Complex to dock on the 3’UTR and execute the cleavage reaction. Interactions of the complex with the RNA and specific dynamics of complex recruitment and formation still remain largely uncharacterized. In our lab we have identified an Adenosine residue as the nucleotide most often present at the cleavage site, although it is unclear whether this specific element is a required instructor of cleavage and polyadenylation. To address whether the Adenosine residue is necessary and sufficient for the cleavage and polyadenylation reaction, we mutated this nucleotide at the cleavage site in three C. elegans protein coding genes, forcing the expression of these wt and mutant 3’UTRs, and studied how the cleavage and polyadenylation machinery process these genes in vivo. We found that interrupting the wt sequence elements found at the cleavage site interferes with the cleavage and polyadenylation reaction, suggesting that the sequence close to the end of the transcript plays a role in modulating the site of the RNA cleavage. This activity is also gene-specific. Genes such as ges-1 showed little disruption in the cleavage of the transcript, with similar location occurring in both the wt and mutant 3’UTRs. On the other hand, mutation of the cleavage site in genes such as Y106G6H.9 caused the activation of new cryptic cleavage sites within the transcript. Taken together, my experiments suggest that the sequence elements at the cleavage site somehow participate in the reaction to guide the cleavage reaction to occur at an exact site. This work will help to better understand the mechanisms of transcription termination in vivo and will push forward research aimed to study post-transcriptional gene regulation in eukaryotes.
ContributorsSteber, Hannah Suzanne (Author) / Mangone, Marco (Thesis director) / Harris, Robin (Committee member) / LaBaer, Joshua (Committee member) / School of Life Sciences (Contributor, Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
The issue of wild horse management in the American West has become prevalent in the media recently and management strategies are often criticized and opposed by the public. Horses have been a core feature of American history and culture nearly since the colonization of the western frontier, and popular media such as television and movies paint a romantic but often unrealistic picture of wild horses. Land management agencies must balance limited resources with an ever-growing wild horse population in order to properly manage public land so that it retains its ecological integrity and is still able to be used by multiple stakeholders, and they also must endure public criticism throughout the process. I used a photo elicitation survey to gather responses to photographic images of wild horses and determine how the public feels about wild horse management, given that horses are seen as a symbol of freedom and the American West. It was revealed that people who are unfamiliar with the issue still have opinions about how the horses should be managed, and these opinions often mirror what can be found in popular media.
ContributorsDuran, Kiana Alexis (Author) / Minteer, Ben (Thesis director) / Schoon, Michael (Thesis director) / Murphree, Julie (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
As human populations continue to expand, interactions with wildlife are expected to increase due to destruction of land and global climate change threatening native habitats. Established areas of protection are becoming essential to species survival and biodiversity protection. National Parks (NP) are a globally ubiquitous method employed to protect wildlife and habitats. Often NPs are mosaics of relatively small protected areas in a “sea” of human-dominated landscapes, and these remaining habitat “islands” are becoming essential to preventing species extinction. However, the establishment of a NP can lead to increased human-wildlife conflicts (HWC) and disenfranchisement of local communities, particularly along their borders. We conducted semi-structured interviews in six different countries to better understand the nature of HWCs at the borders of major NPs: (1) Khao Yai NP, Thailand; (2) Myall Lakes NP, Australia; (3) Chitwan NP, Nepal; (4) Kruger NP, South Africa; (5) Chingaza NP, Colombia, and (6) Yellowstone NP, United States. We evaluated affinity to wildlife, perception of conflicts, management success, and potential solutions at each park to better understand the global nature of HWCs.We also evaluated these data in relationship to the Human Development Index (HDI) to determine if there was a correlation between development and conflict issues. We found the intrinsic value of wildlife to not markedly differ between countries. Conflict was perceived as higher in the United States and Australia but was known to be of greater intensity in Nepal and South Africa. Management of NPs was well-regarded with a slight decrease from less-developed countries to more-developed countries, with solutions that were creative and unique to each region. Results appeared to be related to shifting baselines between countries and also to equivalency in a cross-cultural assessment. When these theories are taken into account, the complexity of HWCs globally is better understood. As our world continues to expand and NPs become some of the only contiguous native habitat and refuges for wildlife, it is important to understand the complex relationships occurring at the interface between natural and human communities and to explore effective solutions to these problems.
ContributorsRagan, Kinley Ann (Author) / Schoon, Michael (Thesis director) / Schipper, Jan (Committee member) / Senko, Jesse (Committee member) / School of Life Sciences (Contributor, Contributor) / School of Geographical Sciences and Urban Planning (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05