176 research outputs found
Aeroelastic simulation of a wind turbine under turbulent and sheared conditions
No full textThe simulation of turbulence introduced in Chap. 29 is extended in this chapter by adding a sheared inflow, also modelled using vortex particles. The chapter starts by discussing the representation of shear in vortex methods. The notions of frozen shear and unfrozen shear are introduced and the vorticity equations are developed for these situations. It is shown that vortex methods tend to omit a term witch is non-negligible when sheared-inflow simulations are performed. The methods perform frozen shear simulation in an erroneous way, which implies that the turbine wake is deflected upward. The numerical implementation of unfrozen shear is discussed and a solution referred to as a Neumann-to-Dirichlet map (or external map) is used to account for the infinite support of the vorticity and the finite computational domain. The method is then applied for full-blown aeroelastic simulations of a wind turbine with shear and turbulence. The possibility to perform aeroelastic simulations of wind turbine under sheared and turbulent conditions using vortex methods is demonstrated. The modelling of turbulence is described in Chap. 29. The elasticity is handled by performing a coupling of the aerodynamic vortex code with the aero-servo-elastic solver HAWC2. The large eddy simulations (LES) performed with the vortex code confirms that the wake should not follow an upward motion when the shear is unfrozen. Results from this chapter are published in the article titled “Aeroelastic large eddy simulations using vortex methods: unfrozen turbulent and sheared inflow” (Branlard et al., J. Phys. Conf. Ser. 625, 2015, [2])
Yaw-modelling using a skewed vortex cylinder
No full textThe cylindrical vortex wake model presented in Chap. 17 for the case of uniform inflow is extended in the current chapter to the case of yawed inflow. Generalities regarding yaw are presented in Sect. 6.1 and only the skewed cylindrical vortex model is presented in this chapter. The chapter starts with a literature review on the topic of yaw-models and vorticity-based methods. The description of the model follows. The novelty of the current model is that the assumption of infinite tip-speed ratio is relaxed. The bound vorticity is assumed to be identical to the case of uniform inflow but the vortex cylinder and the root vortex are skewed with respect to the normal of the rotor disk. Closed form formulae for the induced velocities are provided. They can only be evaluated analytically for a limited part of the domain. A numerical integration is required to obtain the velocity everywhere in the domain. The numerical integration poses no difficulty for modern computers. Semi-empirical models are established to obtain the velocity at the rotor disk. The contribution from each vorticity components to the induced velocity at the rotor disk is investigated. The content of this chapter is based on the publication of the author titled “Cylindrical vortex wake model: skewed cylinder, application to yawed or tilted rotors� (Branlard, Gaunaa, Wind Energy, 2015, [1]). Details on the mathematical derivations used in this chapter are provided in Chap. 38. Results from this chapter are applied in Chap. 22 to derive a new yaw-model applicable to a BEM code. The induction zone in front of a yawed wind turbine or rotor is investigated in Chap. 24 based on the results from the current chapter. A Matlab source code to evaluate the induced velocity field in the entire domain due to the main vorticity component is provided in Sect. 38.1.4
Genotypic and environmental effects on wheat technological and nutritional quality
No full textTechnological (processing performance and end-product) and nutritional quality of wheat is in principle determined by a number of compounds within the wheat grain, including proteins, polysaccharides, lipids, minerals, heavy metals, vitamins and phytochemicals, effecting these characters. The genotype and environment is of similar importance for the determination of the content and composition of these compounds. Furthermore, the interaction between genotypes and the cultivation environment may play a significant role. Many studies have evaluated whether the genotype or the environment plays the major role in determining the content of the mentioned compounds. An overall conclusion of these studies is that except for compounds encoded by single major genes, importance of certain factors mainly depend on how wide environments and how diverse cultivars are within these comparative studies. Comparing environments all over, e.g. across Latin America, ends up with a high significance of the environment while large studies including genotypes of wide genetic background result in a significant role for the genotype. In addition, for some technological properties and components, genotype has a higher effect (e.g. grain hardness and gluten proteins), while environment influences stronger on others (e.g. protein and mineral content). Content and concentration of proteins, but also to some extent of starch, some non-starch polysaccharides and lipids, are essential in determining the technological quality of a wheat flour. For nutritional quality of the flour, the majority of the compounds are together the important determinant. Thus an increased understanding of environmental effects is essential. As to how the environment is influencing the content of the compounds, there are some differences. The protein content and composition is strongly affected by environmental factors influencing nitrogen availability and cultivar development time. However, these two factors are impacted by a range of environmental (temperature, precipitation, humidity/sun hours, etc.) and agronomic (soil properties, crop management practices such as seeding density, nitrogen fertilizer application timing and amount, etc.) components. Thus, to understand the interplay between the various environmental and agronomic factors impacting the technological quality of a wheat flour, modeling is a useful tool. Several other compounds, including minerals and heavy metals, are to a higher extent determined by site specific variation, resulting in similar rankings of entries across locations, although the total content is varying among years. The bioactive compounds and vitamins are a part of the defense mechanisms of plants and thus there is a variation in these compounds depending on prevailing biotic and abiotic stresses (heat, drought, excess rainfall, nutrition, diseases and pests). Thus, even for nutritional quality of wheat, incorporating all compounds of relevance in the evaluation would benefit from modeling tools
Comparison of low molecular weight glutenin subunits identified by SDS-PAGE, 2-DE, MALDI-TOF-MS and PCR in common wheat
No full textLow-molecular-weight glutenin subunits (LMW-GS) play a crucial role in determining end-use quality of common wheat by influencing the viscoelastic properties of dough. Four different methods - sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional gel electrophoresis (2-DE, IEF × SDS-PAGE), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and polymerase chain reaction (PCR), were used to characterize the LMW-GS composition in 103 cultivars from 12 countries
A brief introduction to vortex methods
No full textThe current chapter presents some general considerations related to vortex methods and provides key references on the topic. The chapter begins by briefly introducing vortex methods. The second part of the chapter provides a list of pros and cons of vortex methods. The third part attempts to list the major historical achievements in vortex methods. The fourth part presents different aspects according to which vortex methods can be classified. Specific details for each of these aspects are given in Chap. 41. The last part provides references to existing vortex codes and examples of applications in the field of wind energy. Wind energy applications of vortex methods by the author are discussed in Part V. More details about vortex methods are found in the book of Cottet and Koumoustakos [18], Katz and Plotkin [36] and Lewis [44]
Proteomic analysis of the effect of heat stress on hexaploid wheat grain: characterization of heat-responsive proteins from total endosperm
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Flow induced by a skewed vortex cylinder
No full textThe velocity field induced by a skewed vortex cylinder of longitudinal and tangential vorticity is derived in this chapter by direct integration of the Biot– Savart law. The derivation steps are provided in details. The results of Castles and Durham for the skewed semi-infinite cylinder of tangential vorticity are presented first. The results are then extended so that all the velocity components induced by the tangential vorticity are expressed. The derivation of Coleman et al. which focused on the velocity induced on the base axis is then detailed. The result of Coleman is relevant for the implementation of yaw-models in BEM codes (see e.g. Chap. 21, Sects. 6.1 and 10.3.3). A Matlab source code to evaluate the induced velocity field in the entire domain is provided. Results for semi-infinite and infinite skewed cylinders with longitudinal vorticity are provided in the next section of the articles. Properties for the infinite cylinder of longitudinal vorticity are essential for the understanding of the properties of the semi-finite cylinder. In particular, it is shown that the velocity is zero inside of the infinite cylinder, and the stream-lines are confocal ellipse outside of the cylinder. The content of this chapter is based on the publication of the author entitled "Cylindrical vortex wake model: skewed cylinder, application to yawed or tilted rotors" [1]. Results from this chapter are applied: in Chap. 21 to model a wind turbine (or rotor) in yaw, in Chap. 22 to derive a new yaw-model applicable to a BEM code and in Chap. 24 to study the induction zone in front of a yawed wind turbine (or rotor)
Detection of QTLs for bread-making quality in wheat using a recombinant inbred line population
No full textWhereas gluten fraction accounts for 30-60% of the variation in wheat bread-making quality, there remains substantial variation determined by non-gluten factors. The objective of this study was to detect new loci for wheat quality. The genetics of sodium dodecyl sulphate-sedimentation volume (Ssd), grain hardness (GH), grain protein content, wet gluten content (WGC) and water absorption (Abs) in a set of 198 recombinant inbred lines derived from two commercial varieties was studied by quantitative trait loci (QTL) analysis. A genetic map based on 255 marker loci, consisting of 250 simple sequence repeat markers and five glutenin loci, Glu-A1, Glu-B1, Glu-D1, Glu-B3 and Glu-D3, was constructed. A total of 73 QTLs were detected for all traits. A major QTL for GH was detected on chromosome 1B and its relative contribution to phenotypic variation was 27.7%. A major QTL for Abs on chromosome 5D explained more than 30% of the phenotypic variation. Variations in Ssd were explained by four kinds of genes. Some QTLs for correlated traits mapped to the same regions forming QTL clusters or indicated pleiotropic effects
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