2,542 research outputs found
Rod Korns
No full textPhoto showing J. Roderic ("Rod") Korns, a historian of western trails and author of "West from Fort Bridger
Proposta de controle de operação de poços com bombeio mecânico através da pressão de fundo
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Engenharia de Automação e SistemasNeste trabalho sobre o sistema de elevação artificial por bombeio mecânico é avaliada a contribuição que a pressão de fundo pode aportar ao sistema de controle de unidades de bombeio. Com o desenvolvimento de uma nova classe de sensores de fundo baseados em tecnologia de fibra óptica e custo reduzido surge a possibilidade de aplicar novas estratégias de controle, e neste trabalho, é proposto o controle VSD (Variable Speed Drive) com sintonia através de gain-scheduling para o controle dinâmico do nível no anular, o qual tem forte influência sobre a produção de óleo. Como proposta final utilizam-se em conjunto as informações da carta e pressão de fundo para o controle sobre unidades de bombeio mecânico, o que possibilita trabalhar em um ponto ótimo de operação e diminuir os gastos com manutenção. Para a simulação dos algoritmos de controle foi desenvolvido um simulador para o processo de bombeio mecânico que faz parte de uma plataforma de trabalho que conta também com um CLP (onde estão implementados os algoritmos de controle) conectados através de tecnologia OPC, caracterizando assim, uma situação com condições semelhantes aos campos de produção. \noindent In this work the sucker-rod pumping system is evaluated in order to evaluate the downhole pressure contribution in the pump unit control. With the development of a new class of low cost downhole sensors based in optical-fiber technology, new control strategies could bee applied, and, a control framework using the downhole pressure combined with a Variable Speed Drive (VSD) structure and gain-scheduling tunning is proposed to the dynamic level control of the annular, which has high influence on the oil production. The final proposal used the downhole pressure and dynamometer cards informations to the unit pump control, making possible to operate in the optimized operational point and to reduce the maintenance costs. A hardware in the loop platform was developed for the controlled system simulation, composed by a process simulator (where the dynamic simulator for the sucker-rod pump system is placed) and a CLP (where the control algorithms are placed) conected by OPC technology, which characterizes a situation with similar conditions to the production fields
A rod-linear cascade model for emulating rotor-stator interaction noise in turbofans: A numerical study
No full textThis manuscript presents a rod-linear cascade model for emulating rotor-stator interaction noise. The model is intended as a test platform for studying noise mitigation techniques for a turbofan fan stage, while it also extends the classical rod-airfoil configuration by considering a row of blades based on realistic geometrical details. The rod-linear cascade model consists of a rod positioned upstream of a 7-blade linear cascade, such that the rod wake impinges onto the central blade. The rod is scaled to obtain a fundamental shedding frequency equal to the first blade passing frequency of the NASA-Glenn Source Diagnostics Test (SDT)fan stage at approach condition. The cascade blade profile is also based on the OGV of the SDT sampled at 90% of the radial span. Subsequently, numerical simulations are performed using lattice-Boltzmann Method on a computational setup comprised of a contraction and a test section enclosing the rod-linear cascade model. The integral length scales of the rod wake and the mean loading of the central blade have been found to be in good agreement with the trends observed in the SDT fan stage. The primary noise sources are localized at the central blade leading edge, although noise propagation to the far-field is influenced by additional diffraction by the other blades. Furthermore, the acoustic-blade row interaction causes intense pressure fluctuation within the inter-blade channels, including in those that are not directly affected by the rod wake.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Wind Energ
Molecular Mechanisms of Migraine: Prospects for Pharmacogenomics
No full textMigraine is a common complex disorder that affects a large portion of the population and thus incurs a substantial economic burden on society. The disorder is characterized by recurrent headaches that are unilateral and usually accompanied by nausea, vomiting, photophobia, and phonophobia. The range of clinical characteristics is broad and there is evidence of comorbidity with other neurological diseases, complicating both the diagnosis and management of the disorder. Although the class of drugs known as the triptans (serotonin 5-HT1B/1D agonists) has been shown to be effective in treating a significant number of patients with migraine, treatment may in the future be further enhanced by identifying drugs that selectively target molecular mechanisms causing susceptibility to the disease. Genetically, migraine is a complex familial disorder in which the severity and susceptibility of individuals is most likely governed by several genes that may be different among families. Identification of the genomic variants involved in genetic predisposition to migraine should facilitate the development of more effective diagnostic and therapeutic applications. Genetic profiling, combined with our knowledge of therapeutic response to drugs, should enable the development of specific, individually-tailored treatment.No Full Tex
The effects of vitamin supplementation and MTHFR (C677T) genotype on homocysteine-lowering and migraine disability
No full textBackground Migraine is a prevalent and debilitating disease that may, in part, arise because of disruption in neurovascular endothelia caused by elevated homocysteine. This study examined the homocysteine-lowering effects of vitamin supplementation on migraine disability, frequency and severity and whether MTHFRC677T genotype influenced treatment response. Methods This was a randomized, double-blind placebo, controlled trial of 6 months of daily vitamin supplementation (i.e. 2mg of folic acid, 25mg vitamin B6, and 400 lg of vitamin B12) in 52 patients diagnosed with migraine with aura. Findings Vitamin supplementation reduced homocysteine by 39% (approximately 4 lmol/l) compared with baseline, a reduction that was greater then placebo (P = 0.001). Vitamin supplementation also reduced the prevalence of migraine disability from 60% at baseline to 30% after 6 months (P = 0.01), whereas no reduction was observed for the placebo group (P> 0.1). Headache frequency and pain severity were also reduced (P < 0.05), whereas there was no reduction in the placebo group (P > 0.1). In this patient group the treatment effect on both homocysteine levels and migraine disability was associated with MTHFRC677T genotype whereby carriers of the C allele experienced a greater response compared with TT genotypes (P < 0.05). Interpretation This study provides some early evidence that lowering homocysteine through vitamin supplementation reduces migraine disability in a subgroup of patients. Larger trials are now warranted to establish whether vitamin therapy is a safe, inexpensive and effective prophylactic option for treatment of migraine and whether efficacy is dependant on MTHFRC677T genotype.Griffith Health, School of Medical ScienceFull Tex
Development of the Rodsim numerical simulator for the study of a sucker rod pump, comparing the Gibbs (1963) and Lea (1990) models
No full textIt is of great importance to be fully cognizant of the sucker rod pump system in order to make reliable production forecasts and to evaluate potential strategies for optimizing production processes. A frequently employed methodology in such circumstances is numerical simulation. A numerical sucker road pump simulator can provide valuable insights into production performance by generating dynamometric charts that represent the efficiency of this activity. Since the rod column behaves like a thin rod, it is possible to represent the mathematical model by a one-dimensional wave equation that describes the forces acting on this rod column. Lea (1990), proposing an improvement of the work of Gibbs (1963), considers the effects of the viscosity of the fluid produced in a vertical well without heat exchange, the piston diameter, the production column and the rods to obtain the damping factor, thus being more complete and producing a more accurate result in the dynamometric charts. Both models are implemented and discussed herein.
The equations are discretized and solved in the Matlab® environment. The code includes a graphical user interface that generates the internal Rodsim application. The application is used to solve a typical case of a sucker rod pump and to obtain the surface and downhole dynamometric plots for certain scenarios
Supplementary_Revised_Table_2_Clean - Targeted next generation sequencing identifies a genetic spectrum of DNA variants in patients with hemiplegic migraine
No full textSupplementary_Revised_Table_2_Clean for Targeted next generation sequencing identifies a genetic spectrum of DNA variants in patients with hemiplegic migraine by Neven Maksemous, Robert A Smith, Heidi G Sutherland, Bridget H Maher, Omar Ibrahim, Garth A Nicholson, Elisabeth P Carpenter, Rod A Lea, M Zameel Cader and Lyn R Griffiths in Cephalalgia Reports</p
Supplementary_Revised_Table_1 - Targeted next generation sequencing identifies a genetic spectrum of DNA variants in patients with hemiplegic migraine
No full textSupplementary_Revised_Table_1 for Targeted next generation sequencing identifies a genetic spectrum of DNA variants in patients with hemiplegic migraine by Neven Maksemous, Robert A Smith, Heidi G Sutherland, Bridget H Maher, Omar Ibrahim, Garth A Nicholson, Elisabeth P Carpenter, Rod A Lea, M Zameel Cader and Lyn R Griffiths in Cephalalgia Reports</p
Supplementary_Figure_1_(1) - Targeted next generation sequencing identifies a genetic spectrum of DNA variants in patients with hemiplegic migraine
No full textSupplementary_Figure_1_(1) for Targeted next generation sequencing identifies a genetic spectrum of DNA variants in patients with hemiplegic migraine by Neven Maksemous, Robert A Smith, Heidi G Sutherland, Bridget H Maher, Omar Ibrahim, Garth A Nicholson, Elisabeth P Carpenter, Rod A Lea, M Zameel Cader and Lyn R Griffiths in Cephalalgia Reports</p
The role of the MTHFR gene in migraine
No full textMigraine is a common neurological disorder and is characterized by debilitating head pain and an assortment of additional symptoms which can include nausea, emesis, photophobia, phonophobia, and occasionally, visual sensory disturbances. A number of genes have been implicated in the pathogenesis of this disease, including genes involved in regulating the vascular system. Of particular importance are the methylenetetrahydrofolate reductase (MTHFR) gene and the role it plays in migraine with aura. Migraine with aura has previously been shown to have a significant comorbidity with stroke, making the vascular class of genes a priority for migraine studies. In this report, we outline the importance of the MTHFR gene in migraine and also discuss the use of a genetic isolate to investigate MTHFR genetic variants. From this study, 3 MTHFR single nucleotide polymorphisms showing association with migraine in the Norfolk Island population have been identified, thus reinforcing the potential role of MTHFR in migraine susceptibility. Further studies will continue to build a gene profile of variants involved in the complex disease migraine and improve understanding of the underlying genetic causes of this disorder.Griffith Health, School of Medical ScienceFull Tex
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