Three Dimensional Numerical Predicton of Icing Related Power and Energy Losses on a Wind Turbine

RÉSUMÉ Plusieurs régions du Canada sont soumises à des conditions hivernales difficiles qui persistent pendant plusieurs mois. En conséquence, les éoliennes situées dans ces régions sont exposées aux effets du froid, à l'accumulation de glace et à leurs effets négatifs qui se manifestent de la perte de puissance temporaire jusqu’à l’arrêt complet de la machine. Dans certains sites au Canada, la perte de production annuelle d'une turbine éolienne peut atteindre jusqu'à 16% de sa valeur nominale et l'estimation de ces pertes avant la construction d'un parc éolien devient essentielle pour les développeurs et investisseurs. La revue de la littérature montre que la plupart des logiciels de prévision de givrage ont été développés pour les avions, et sont, en majorité, la propriété d’entreprises et inaccessibles aux chercheurs oeuvrant dans d'autres domaines. En plus, le givrage des avions est différent de celui de l'éolienne. Les éoliennes sont exposées à des conditions de givrage pour des périodes beaucoup plus longues que les avions, peut-être pour plusieurs jours dans un climat rude, alors que la durée maximale de l'exposition d'un avion est d'environ 3-4 heures. En outre, les pales d'éoliennes fonctionnent à des vitesses subsoniques, à des nombres de Reynolds inférieurs à ceux des avions, et leurs caractéristiques physiques sont différentes. Quelques logiciels ont été cependant développés pour le givrage des éoliennes. Toutefois, ils sont soit en 2D et ne considèrent pas les caractéristiques 3D du champ d'écoulement, ou se concentrent sur la simulation de chaque rotation d'une manière dépendante du temps, ce qui n'est pas pratique pour le calcul de longues heures de l'accumulation de glace. Dans ce contexte, notre objectif dans cette thèse est de développer une méthodologie numérique 3D pour prédire la forme de givre et la perte de puissance d'une éolienne en fonction des conditions météorologiques. En plus, nous calculons la production énergétique annuelle d'une turbine typique pour des conditions normales d’exploitation et en tenant compte des évènements givrants. Les calculs sont effectués en utilisant une éolienne pour laquelle des nombreuses données sont disponibles, l'éolienne NREL Phase VI et les conditions météorologiques d'un parc éolien en Suède pour lequel les évènements de givrage sont enregistrés et publiés. La méthode proposée est basée sur le calcul et la validation de la performance de l'éolienne propre, le calcul de la forme de givre et de la performance de la pale givré, pour des conditions de givrage typiques.----------ABSTRACT Regions of Canada experience harsh winter conditions that may persist for several months. Consequently, wind turbines located in these regions are exposed to ice accretion and its adverse effects, from loss of power to ceasing to function altogether. Since the weather-related annual energy production loss of a turbine may be as high as 16% of the nominal production for Canada, estimating these losses before the construction of a wind farm is essential for investors. A literature survey shows that most icing prediction methods and codes are developed for aircraft, and, as this information is mostly considered corporate intellectual property, it is not accessible to researchers in other domains. Moreover, aircraft icing is quite different from wind turbine icing. Wind turbines are exposed to icing conditions for much longer periods than aircraft, perhaps for several days in a harsh climate, whereas the maximum length of exposure of an aircraft is about 3-4 hours. In addition, wind turbine blades operate at subsonic speeds, at lower Reynolds numbers than aircraft, and their physical characteristics are different. A few icing codes have been developed for wind turbine icing nevertheless. However, they are either in 2D, which does not consider the 3D characteristics of the flow field, or they focus on simulating each rotation in a time-dependent manner, which is not practical for computing long hours of ice accretion. Our objective in this thesis is to develop a 3D numerical methodology to predict rime ice shape and the power loss of a wind turbine as a function of wind farm icing conditions. In addition, we compute the Annual Energy Production of a sample turbine under both clean and icing conditions. The sample turbine we have selected is the NREL Phase VI experimental wind turbine installed on a wind farm in Sweden, the icing events at which have been recorded and published. The proposed method is based on computing and validating the clean performance of the turbine, and then computing the ice shape and iced blade performance, under icing conditions. The first step is to compute the performance of the NREL Phase VI using the commercial ANSYS-FLUENT computational fluid dynamics (CFD) tool. In order to reduce the computational cost, we use a rotating reference frame model which computes the flow properties as time-averaged quantities

Saving Lives: The Principle of Distinction and the Realities of Modern War

WOS: 000332942700005PubMed ID: 24778561In this study, we assessed the feasibility of fetal RhD genotyping by analysis of cell-free fetal DNA(cffDNA) extracted from plasma samples of Rhesus (Rh) D-negative pregnant women by using real-time polymerase chain reaction (PCR). Fetal genotyping was performed on 30 RhD-negative women between 9 and 39 weeks of gestation who were referred to us for invasive testing [amniocentesis/chorionic villi sampling (CVS)]. The fetal RHD genotype was determined based on real-time PCR method. Exons 7 and 10 of the RHD and SRY genes were targeted. Among the pregnant women, 12 were carrying male and 17 were carrying female fetuses. Out of 29 pregnant women, 21 had RhD-positive and nine had RhD-negative fetuses. One sample) case 12, whose blood group was found to be AB Rh [+] (was excluded due to controversial results from repeated serological analyses. All prenatal results were in concordance with postnatal RhD status and fetal sex without false-positive or -negative results. Performing real-time PCR on cffDNA showed accurate, efficient and reliable results, allowing rapid and high throughput non invasive determination of fetal sex and RhD status in clinical samples

Prognostic value of the morphological features of postperfusion liver biopsies in liver transplantation

Purpose: The aim of this study was to show the potential prognostic effects of morphological findings for the graft function, rejection and survival by evaluating the postperfusion liver biopsies. Materials and Methods: Sixty six cases who underwent cadaveric liver transplantation between 2006-2010 were included. The representative slides of postperfusion subcapsular wedge biopsies were evaluated for intrasinusoidal neutrophilic infiltration, microvesicular steatosis, hepatocyte swelling, hepatocellular necrosis, endothelial swelling, bile duct epithelial changes, cholangiolar proliferation and sinusoidal congestion/hemorrhage. The associations between the histopathological features and early allograft dysfunction, mortality rate and rejection status were statistically analysed. Results: Intrasinusoidal neutrophilic infiltration was grade 1 in 40 (60%), grade 2 in 24 (36%), and grade 3 in 2 cases (4%). The presence of grade 2-3 intrasinusoidal neutrophils was found to be significantly associated with mortality rate. The presence of sinusiodal congestion/hemorrhage was statistically related to the rejection. The presence of sinusiodal congestion/hemorrhage was significantly associated with shorter overall survival. Conclusion: Intrasinusoidal neutrophilic infiltration is promising to be a possible histopathological predictor for mortality. In addition, the presence of sinusoidal congestion can be a candidate as a prognostic factor both for rejection and overall survival based on our study.Amaç: Bu çalışmada, perfüzyon sonrası karaciğer biyopsileri değerlendirilerek morfolojik bulguların greft fonksiyonu, rejeksiyon durumu ve sağkalım üzerindeki potansiyel prognostik etkilerinin gösterilmesi amaçlanmıştır. Gereç ve Yöntem: 2006-2010 yılları arasında kadavradan karaciğer nakli yapılan 66 olgu çalışmaya dahil edildi. Postperfüzyon kama biyopsilerine ait kesitler, intrasinüzoidal nötrofilik infiltrasyon, mikroveziküler steatoz, hepatosit şişmesi, hepatoselüler nekroz, endotelyal şişme, safra kanalı epitel değişiklikleri, kolanjiyolar proliferasyon ve sinüzoidal konjesyon/hemoraji açısından değerlendirildi. Histopatolojik özellikler ile erken allogreft disfonksiyonu, mortalite oranı ve rejeksiyon durumu arasındaki ilişkiler istatistiksel olarak analiz edildi. Bulgular: İntrasinüzoidal nötrofilik infiltrasyon 40 olguda (%60) derece 1, 24 olguda (%36) derece 2 ve 2 olguda (%4) derece 3 idi. Derece 2-3 intrasinüzoidal nötrofil varlığının mortalite oranı ile, sinüzoidal konjesyon/kanama varlığının rejeksiyon ile istatistiksel olarak anlamlı şekilde ilişkili olduğu saptandı. Ayrıca sinüzoidal konjesyon/hemoraji varlığının, daha kısa sağkalım süresi ile istatistiksel olarak anlamlı şekilde ilişkili olduğu bulundu. Sonuç: İntrasinüzoidal nötrofilik infiltrasyon, mortaliteyi öngörmek için olası bir histopatolojik belirleyici olma umudu taşımaktadır. Ayrıca çalışmamıza göre sinüzoidal konjesyon varlığı hem rejeksiyon hem de sağkalım için prognostik faktör olarak aday olabilir

Successful Treatment of Herpes Esophagitis With Ganciclovir in a Liver Transplant Patient

The presence of Herpes Simplex Virüs-1 (HSV-1) esophagitis in patients with liver transplantation has been reported rarely. Among the reports that are accessible in the literature, none could have shown tissue positivity for Herpes virus-1 DNA via Polymerase Chain Reaction (PCR) in patients with liver transplantation. This case is presented as the patient was diagnosed with herpes esophagitis based on the histopathological findings and HSV-1 DNA positivity (detected by PCR) in the biopsy material and was treated with Ganciclovir. Due to the specific action of Ganciclovir against CMV infections, it is natural that the drug cannot use in the treatment of HSV infections. However it is reported that ganciclovir has been reduced the incidence of symptomatic HSV infections after liver transplantation. We report on a patient after liver transplantation with HSV-1 esophagitis, who was successfully treated with Ganciclovir. We assume that most transplant centers according to their protocols use ganciclovir for CMV prophylaxis, which may contribute to avoid HSV infection

Electric-Field Breakdown of Absolute Negative Conductivity and Supersonic Streams in Two-Dimensional Electron Systems with Zero Resistance/Conductance States

We calculate the current-voltage characteristic of a two-dimensional electron system (2DES) subjected to a magnetic field at strong electric fields. The interaction of electrons with piezoelectric acoustic phonons is considered as a major scattering mechanism governing the current-voltage characteristic. It is shown that at a sufficiently strong electric field corresponding to the Hall drift velocity exceeding the velocity of sound, the dissipative current exhibits an overshoot. The overshoot of the dissipative current can result in a breakdown of the absolute negative conductivity caused by microwave irradiation and, therefore, substantially effect the formation of the domain structures with the zero-resistance and zero-conductance states and supersonic electron streams.Comment: 5 pages, 4 figure

Alfabetización académica, informacional y digital: trabajo conjunto e integración curricular en el desarrollo de competencias en la comunidad universitaria : El caso de la Universidad Nacional de Lanús

Desde 1997, año de comienzo de las actividades académicas de la UNLa, los espacios de Biblioteca y Pedagogía, ambos dependientes de la Secretaría Académica, han planificado y producido acciones conjuntas que evidencian el entramado de las diferentes alfabetizaciones que tienen lugar en el mundo académico y que requiere de los estudiantes competencias, habilidades, destrezas en la búsqueda y tratamiento de la información, aprovechamiento de las herramientas digitales y estrategias de lectura y escritura de los textos propios del estudio en la universidad. Al mismo tiempo, estas acciones conjuntas se han articulado con distintas propuestas curriculares, con carreras como la Licenciatura en Informática Educativa que con la revisión curricular realizada entre 2013 y 2015 modificó su denominación pasando a llamarse Ciclo de Licenciatura en Tecnologías Digitales para la Educación. También con espacios al interior de las carreras y con la propuesta de Informática para todos los estudiantes de la universidad.Eje 3: Tecnologías digitales y entornos virtuales de la enseñanza universitaria: perspectivas actuales y escenarios futuros. Experiencias de enseñanza universitaria en entornos virtualesSecretaría de Asuntos Académico

Genome-Wide Transcriptional Reorganization Associated with Senescence-to-Immortality Switch during Human Hepatocellular Carcinogenesis

Cataloged from PDF version of article.Senescence is a permanent proliferation arrest in response to cell stress such as DNA damage. It contributes strongly to tissue aging and serves as a major barrier against tumor development. Most tumor cells are believed to bypass the senescence barrier (become "immortal") by inactivating growth control genes such as TP53 and CDKN2A. They also reactivate telomerase reverse transcriptase. Senescence-to-immortality transition is accompanied by major phenotypic and biochemical changes mediated by genome-wide transcriptional modifications. This appears to happen during hepatocellular carcinoma (HCC) development in patients with liver cirrhosis, however, the accompanying transcriptional changes are virtually unknown. We investigated genome-wide transcriptional changes related to the senescence-to-immortality switch during hepatocellular carcinogenesis. Initially, we performed transcriptome analysis of senescent and immortal clones of Huh7 HCC cell line, and identified genes with significant differential expression to establish a senescence-related gene list. Through the analysis of senescence-related gene expression in different liver tissues we showed that cirrhosis and HCC display expression patterns compatible with senescent and immortal phenotypes, respectively; dysplasia being a transitional state. Gene set enrichment analysis revealed that cirrhosis/senescence-associated genes were preferentially expressed in non-tumor tissues, less malignant tumors, and differentiated or senescent cells. In contrast, HCC/immortality genes were up-regulated in tumor tissues, or more malignant tumors and progenitor cells. In HCC tumors and immortal cells genes involved in DNA repair, cell cycle, telomere extension and branched chain amino acid metabolism were up-regulated, whereas genes involved in cell signaling, as well as in drug, lipid, retinoid and glycolytic metabolism were down-regulated. Based on these distinctive gene expression features we developed a 15-gene hepatocellular immortality signature test that discriminated HCC from cirrhosis with high accuracy. Our findings demonstrate that senescence bypass plays a central role in hepatocellular carcinogenesis engendering systematic changes in the transcription of genes regulating DNA repair, proliferation, differentiation and metabolism

Telomerase and Apoptosis in the Placental Trophoblasts of Growth Discordant Twins

In an effort to investigate the molecular basis of growth discordance in embryos that experience the same uterine environment, we compared telomerase activity and apoptosis in placental trophoblasts obtained from growth discordant twins. Between January 2003 and February 2005, placental tissue from twenty pairs of twins was obtained within thirty minutes of delivery. Eleven cases were classified as growth discordant, with birth weight discordance greater than 20%. Nine cases comprised the control group, with less than 20% discordance. Telomerase and apoptotic activities in placental trophoblasts were analyzed by ELISA and immunoblot. Statistical significance was analyzed by a paired t-test, chisquared test, and ANOVA (SPSS ver 11.0). The average growth discordance was 26.8% in the growth discordant group and 14.4% in the control group. There were no significant differences in maternal age, week of gestation at delivery, parity, or chorionisity between the two groups. In the growth discordant group, the larger twin showed significantly higher telomerase activity (p < 0.01), whereas no significant difference was observed in the control group (p = 0.36). In addition, there was no definitive correlation between telomerase activity and the degree of growth discordance in the larger or smaller twins (R = -0.521 and -0.399, p = 0.15 and 0.25, respectively). The apoptosis proteins Bax and Bcl 2 were detected in both the larger and smaller twins in the growth discordant and control groups. There was no statistically significant difference in Bax expression between the larger and smaller twins (p = 0.25 and 0.92, respectively) for either the growth discordant or the control groups. Bcl 2 expression also showed no significant difference between groups. In conclusion, a tendency toward reduced telomerase activity and increased apoptosis was discovered in placental trophoblasts of the smaller growth-discordant twin, possibility resulting in delayed fetal growth

Angiogenesis in urinary bladder carcinoma as defined by microvessel density (MVD) after immunohistochemical staining for Factor VIII and CD31

Background: Among the patients with bladder cancer, a group is still at risk of disease recurrence, progression, and death from their cancer after curative treatment. Angiogenesis is a crucial pathogenic mechanism for this type of urothelial carcinoma and is a potential therapeutic target. Objectives: To quantify tumor angiogenesis in bladder cancer and determine whether it correlates with tumor stage and grade. Patients and methods: A series of 42 archival samples from carcinomas of the urinary bladder were graded, staged, and analyzed for microvessel density (MVD) by a double immunohistochemical technique using Factor VIII (FVIII) and CD31 antibodies. The correlation between MVD and histopathological grade and tumor stage was evaluated. Results: FVIII and CD31 immunoreactivity was observed in 100% of cases and more intensely with CD31. Significantly higher MVD was determined in invasive tumors than in superficial tumors (p&#60;0.05). MVD increased with tumor grade and stage (p&#60;0.05); MVD was not affected by age or sex of the patients. Conclusion: These data demonstrate that MVD in bladder carcinoma correlates with the tumor grade and stage. Quantification of tumor angiogenesis may allow selection of the type of treatment for bladder cancer patients

An implementation of an aeroacoustic prediction model for broadband noise from a vertical axis wind turbine using a CFD informed methodology

This paper presents an enhanced method for predicting aerodynamically generated broadband noise produced by a Vertical Axis Wind Turbine (VAWT). The method improves on existing work for VAWT noise prediction and incorporates recently developed airfoil noise prediction models. Inflow-turbulence and airfoil self-noise mechanisms are both considered. Airfoil noise predictions are dependent on aerodynamic input data and time dependent Computational Fluid Dynamics (CFD) calculations are carried out to solve for the aerodynamic solution. Analytical ow methods are also benchmarked against the CFD informed noise prediction results to quantify errors in the former approach. Comparisons to experimental noise measurements for an existing turbine are encouraging. A parameter study is performed and shows the sensitivity of overall noise levels to changes in inflow velocity and inflow turbulence. Noise sources are characterised and the location and mechanism of the primary sources is determined, inflow-turbulence noise is seen to be the dominant source. The use of CFD calculations is seen to improve the accuracy of noise predictions when compared to the analytic ow solution as well as showing that, for inflow-turbulence noise sources, blade generated turbulence dominates the atmospheric inflow turbulence