Evaluación Del Perfil de Velocidades Media para una Simulación de Capa Límite Atmosférica en un Túnel de Viento

A avaliação do escoamento turbulento simulado no túnel devento se realiza medindo as velocidades médias e os parâmetros turbulentos.Neste trabalho são apresentadas as distribuições de velocidademédia e intensidade de turbulência, para uma simulação parcial em condição de estabilidade neutra da camada limite atmosférica. As mediçõesde velocidades médias e flutuantes foram realizadas com um sistemaanemométrico para duas velocidades de operação. Encontraram-se diferenças significativas entre os expoentes da lei potencial e os parâmetrosda lei logarítmica nas simulações a baixa e alta velocidade. Também seapresenta uma comparação com os resultados obtidos no outro túnel devento

Flow in the wake of wind turbines : turbulance spectral analysis by wind tunnel test

The interaction between the incident wind and wind turbines in a wind farm causes mean velocity deficit and increased levels of turbulence in the wake. The turbulent flow is characterized by the superposition of wind turbine wakes. In this work, the technique of turbulence spectral evaluation for reduced scale models in a boundary layer wind tunnel is presented, and different measurements of velocity fluctuations are analysed. The results allow evaluating the spectrum for different frequency ranges and the differences of the spectral behaviour between the incident wind and the turbine wake flow

Análise experimental no túnel de vento dos processos de difusão de gases poluentes na atmosfera

The objective of this work is the study of atmospheric pollutants dispersion problems in wind tunnels. The use of a reduced scale model provides the ability to analyze the process of dispersion in complex models. It also allows the study of different situations and alternatives in the source design. The wind tunnel pollutants dispersion simulation requires two sets of similarity criteria; the first established that the wind tunnel flow must be similar to natural wind in the atmospheric boundary layer, and the second, that the model source characteristics must be similar to prototype. In this work, the similarity criteria of the atmospheric flow and the emission source are studied to reproduce dispersion processes and develop a first approach to the experimental study of this phenomenon. Firstly, the results of a visualization dispersion process test performed at the wind tunnel of the Facultad de Ingeniería de la Universidad Nacional del Nordeste, using smoke as a tracer and considering three operation velocities are presented. The study of the plume evolution was made by image digital processing and the plume rise is also discussed by comparison of measurements with theoretical values. Finally, preliminary experiments results are presented to evaluate concentration field from an isolated point emission source using a light gas and reduced scale model.Keywords: atmospheric dispersion, similarity, wind tunnel.O objetivo deste trabalho é o estudo de problemas de dispersão de poluentes na atmosfera em túneis de vento. A utilização de um modelo em escala reduzida fornece a capacidade de analisar o processo de dispersão em situações complexas. Também permite a avaliação de diferentes alternativas para o projeto da fonte de emissão. A simulação do processo de dispersão de poluentes no túnel de vento requer dois conjuntos de critérios de similaridade, o primeiro estabelece que o escoamento no interior do túnel de vento deve ser semelhante ao vento natural na camada limite atmosférica, e o segundo que as características da fonte no modelo devem ser semelhantes às do protótipo. Neste trabalho, são estudados os critérios de semelhança do escoamento atmosférico e a fonte de emissão para reproduzir o processo de dispersão, e fazer uma primeira abordagem ao estudo experimental deste fenômeno. Na primeira parte, são apresentados os resultados de um estudo de visualização de um processo de dispersão realizado no túnel de vento da Facultad de Ingeniería de la Universidad Nacional del Nordeste, utilizando fumaça e considerando três velocidades de operação. O estudo da evolução da pluma simulada foi realizado a partir do processamento digital de imagens obtidas durante o teste. Analisa-se também a elevação da pluma comparando as medições com valores teóricos. Finalmente, são apresentados resultados de medições preliminares de experimentos para avaliar o campo de concentração de uma emissão de gás muito leve, utilizando um modelo em escala reduzida.Palavras-chave: dispersão atmosférica, semelhança, túnel de vento

Employing wind tunnel data to evaluate a turbulent spectral model

In this study, spectra obtained from wind tunnel data are compared with a model that describes observed atmospheric neutral spectra. The investigation points out that there is a good conformity between both spectra for the whole turbulent frequency domain. This result is significative since that the spectral model was obtained using only turbulent quantities measured in the planetary boundary layer. This similitude occurring with wind tunnel and atmospheric data furnishes a way to obtain connections between wind tunnel and atmospheric turbulent observations. The results, presented in this analysis, confirm the hypothesis that turbulence parameters observed in wind tunnel, can simulate real wind data measured in atmosphere

Diseño y construcción del modelo a escala de un aerogenerador de eje horizontal para estudios experimentales

En los últimos años, en nuestra región, fundamentalmente Brasil, Chile, Uruguay y Argentina han impulsado fuertemente el desarrollo e instalación de aprovechamientos eólicos, debido a que generan un menor impacto ambiental si se compara con otras fuentes de energía. Con el objeto de optimizar el funcionamiento de los aerogeneradores individualmente o en un parque eólico, es fundamental el estudio de la interacción de la estructura de los mismos y la capa límite atmosférica. Una de las formas de estudiar este comportamiento es mediante ensayos experimentales en túneles de viento utilizando modelos a escala reducida. En este trabajo se describen las etapas de diseño y construcción del modelo a escala de un generador eólico de tres palas de eje horizontal. A partir de los aspectos aerodinámicos vinculados a este tipo de dispositivo, se diseñaron los componentes del aerogenerador y se evaluaron un conjunto de parámetros relacionados al funcionamiento y eficiencia del modelo. El modelo fue construido usando la técnica de impresión 3D de las componentes e incluye un dispositivo para el posicionamiento relativo de las palas con relación a la dirección del viento incidente. Finalmente, el modelo fue montado en el túnel de viento “Jacek Gorecki" de la UNNE y se realizaron ensayos que permitieron una primera evaluación de las características de funcionamiento del aerogenerador a través de la medición de RPM, potencia y torque. Los ensayos se realizaron con viento incidente uniforme considerando dos velocidades distintas; 5,26 m/s y 6,76 m/s. El ángulo que determina la posición de las palas con respecto al viento incidente ha sido modificado para obtener los valores de los parámetros respectivos correspondientes a cada situación.Fil: Milich, Franco G.. Universidad Nacional del NordesteFil: Alvarez y Alvarez, Gisela M. . Universidad Nacional del NordesteFil: Chuaire, Mauricio L.. Universidad Nacional del NordesteFil: Veroli, Cesar G. . Universidad Nacional del NordesteFil: Wittwer, Adrián R.. Universidad Nacional del Nordest

Base-pair neutral homozygotes can be discriminated by calibrated high-resolution melting of small amplicons

Genotyping by high-resolution melting analysis of small amplicons is homogeneous and simple. However, this approach can be limited by physical and chemical components of the system that contribute to intersample melting variation. It is challenging for this method to distinguish homozygous G::C from C::G or A::T from T::A base-pair neutral variants, which comprise ∼16% of all human single nucleotide polymorphisms (SNPs). We used internal oligonucleotide calibrators and custom analysis software to improve small amplicon (42–86 bp) genotyping on the LightScanner®. Three G/C (PAH c.1155C>G, CHK2 c.1-3850G>C and candidate gene BX647987 c.261+22,290C>G) and three T/A (CPS1 c.3405-29A>T, OTC c.299-8T>A and MSH2 c.1511-9A>T) human single nucleotide variants were analyzed. Calibration improved homozygote genotyping accuracy from 91.7 to 99.7% across 1105 amplicons from 141 samples for five of the six targets. The average Tm standard deviations of these targets decreased from 0.067°C before calibration to 0.022°C after calibration. We were unable to generate a small amplicon that could discriminate the BX647987 c.261+22,290C>G (rs1869458) SNP, despite reducing standard deviations from 0.086°C to 0.032°C. Two of the sites contained symmetric nearest neighbors adjacent to the SNPs. Unexpectedly, we were able to distinguish these homozygotes by Tm even though current nearest neighbor models predict that the two homozygous alleles would be identical

Mixture models for analysis of melting temperature data

<p>Abstract</p> <p>Background</p> <p>In addition to their use in detecting undesired real-time PCR products, melting temperatures are useful for detecting variations in the desired target sequences. Methodological improvements in recent years allow the generation of high-resolution melting-temperature (T_m) data. However, there is currently no convention on how to statistically analyze such high-resolution T_mdata.</p> <p>Results</p> <p>Mixture model analysis was applied to T_mdata. Models were selected based on Akaike's information criterion. Mixture model analysis correctly identified categories in T_mdata obtained for known plasmid targets. Using simulated data, we investigated the number of observations required for model construction. The precision of the reported mixing proportions from data fitted to a preconstructed model was also evaluated.</p> <p>Conclusion</p> <p>Mixture model analysis of T_mdata allows the minimum number of different sequences in a set of amplicons and their relative frequencies to be determined. This approach allows T_mdata to be analyzed, classified, and compared in an unbiased manner.</p

Estudio experimental del campo de velocidades del viento en torno al modelo reducido de una vivienda

Este trabajo trata del relevamiento experimental del campo de velocidades del escurrimiento alrededor de una vivienda, baja, aislada y cerrada. El análisis se realiza utilizando un túnel de viento de pequeñas dimensiones sobre un modelo reducido construido con una escala 1/40 con relación a la vivienda. Se utilizó un flujo turbulento con distribución uniforme de velocidades medias del orden de los 16 m/s en la zona de ensayo. Los resultados obtenidos permiten caracterizar el campo de velocidades y la turbulencia para condiciones estacionarias, permitiendo identificar zonas con fenómenos aerodinámicos característicos que se generan en las inmediaciones de este tipo de estructuras (bajas y con aristas vivas). De esta manera se realizó la caracterización en diversos sectores, cercanos al recinto, de la componente longitudinal de altas frecuencias de las fluctuaciones de velocidad del escurrimiento medio (espectro micrometeorológico), pero debe advertirse que estos resultados no consideran las variaciones de las componentes de baja frecuencia (medias horarias, etc.).This work is about the experimental measurement of the velocities field of the flow surrounding an isolated, cladding low-rise house. The analysis is performed on a reduced model built in a scale of 1/40 in regard with the house using a small wind tunnel. A turbulent flow with uniform mean velocity distribution, which was in an order of 16 m/s, was used in the test section. The obtained results allow characterizing the velocities field and the turbulence for stationary conditions, allowing the identification of areas with characteristic aerodynamic phenomena that are generated in the neighbourhood of this kind of structures (low-rise building with sharp edges). Therefore, it was characterized in each area the high frequency component of the velocity fluctuations (micrometeorology spectrum), though it must be noted that these results do not consider the low frequency variations (hourly means, etc.).Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

TmPrime: fast, flexible oligonucleotide design software for gene synthesis

Herein we present TmPrime, a computer program to design oligonucleotide sets for gene assembly by both ligase chain reaction (LCR) and polymerase chain reaction (PCR). TmPrime offers much flexibility with no constraints on the gene and oligonucleotide lengths. The program divides the long input DNA sequence based on the input desired melting temperature, and dynamically optimizes the length of oligonucleotides to achieve homologous melting temperatures. The output reports the melting temperatures, oligonucleotide sequences and potential formation of secondary structures. Our program also provides functions on sequence pooling to separate long genes into smaller pieces for multi-pool assembly and codon optimization for expression. The software has been successfully used in the design and synthesis of green fluorescent protein fragment (GFPuv) (760 bp), human protein kinase B-2 (PKB2) (1446 bp) and the promoter of human calcium-binding protein A4 (S100A4) (752 bp) using real-time PCR assembly with LCGreen I, which offers a novel approach to compare the efficiency of gene synthesis. The purity of assembled products is successfully estimated with the use of melting curve analysis, which would potentially eliminate the necessity for agarose gel electrophoresis. This program is freely available at http://prime.ibn.a-star.edu.sg