The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
Joe H. Chow - One of the best experts on this subject based on the ideXlab platform.
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Windfarm Power Optimization Using Yaw Angle Control
IEEE Transactions on Sustainable Energy, 2020Co-Authors: Onkar Sahni, Joe H. ChowAbstract:In this paper, we extend the Park and Jensen wake model to include the effects of yaw angle rotation and wake deflection of wind turbines. We first perform a numerical study to find the optimal values of Induction Factor and yaw angle of wind turbines in a single column of a windfarm for achieving the maximum total power with wake effects. This study shows that the maximum power in a single column is achieved by keeping the Induction Factor at one-third and only changing the yaw angle to deflect the wake. We then propose a dynamic programming formulation to maximize the total power production in a windfarm with a single column of turbines using yaw angle as the control variable. We also extend our expressions to a windfarm with multiple rows and columns of turbines and perform simulations on the 3 $\times$ 3 and 4 $\times$ 4 grid topologies. Our results show that the optimal Induction Factor for most turbines is quite close to one-third and yaw angle acts as the dominant optimization variable.
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Windfarm Power Optimization Using Yaw Angle Control
IEEE Transactions on Sustainable Energy, 2017Co-Authors: Onkar Sahni, Joe H. ChowAbstract:In this paper, we extend the Park and Jensen wake model to include the effects of yaw angle rotation and wake deflection of wind turbines. We first perform a numerical study to find the optimal values of Induction Factor and yaw angle of wind turbines in a single column of a windfarm for achieving the maximum total power with wake effects. This study shows that the maximum power in a single column is achieved by keeping the Induction Factor at one-third and only changing the yaw angle to deflect the wake. We then propose a dynamic programming formulation to maximize the total power production in a windfarm with a single column of turbines using yaw angle as the control variable. We also extend our expressions to a windfarm with multiple rows and columns of turbines and perform simulations on the 3 × 3 and 4 × 4 grid topologies. Our results show that the optimal Induction Factor for most turbines is quite close to one-third and yaw angle acts as the dominant optimization variable.
Onkar Sahni - One of the best experts on this subject based on the ideXlab platform.
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Windfarm Power Optimization Using Yaw Angle Control
IEEE Transactions on Sustainable Energy, 2020Co-Authors: Onkar Sahni, Joe H. ChowAbstract:In this paper, we extend the Park and Jensen wake model to include the effects of yaw angle rotation and wake deflection of wind turbines. We first perform a numerical study to find the optimal values of Induction Factor and yaw angle of wind turbines in a single column of a windfarm for achieving the maximum total power with wake effects. This study shows that the maximum power in a single column is achieved by keeping the Induction Factor at one-third and only changing the yaw angle to deflect the wake. We then propose a dynamic programming formulation to maximize the total power production in a windfarm with a single column of turbines using yaw angle as the control variable. We also extend our expressions to a windfarm with multiple rows and columns of turbines and perform simulations on the 3 $\times$ 3 and 4 $\times$ 4 grid topologies. Our results show that the optimal Induction Factor for most turbines is quite close to one-third and yaw angle acts as the dominant optimization variable.
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Windfarm Power Optimization Using Yaw Angle Control
IEEE Transactions on Sustainable Energy, 2017Co-Authors: Onkar Sahni, Joe H. ChowAbstract:In this paper, we extend the Park and Jensen wake model to include the effects of yaw angle rotation and wake deflection of wind turbines. We first perform a numerical study to find the optimal values of Induction Factor and yaw angle of wind turbines in a single column of a windfarm for achieving the maximum total power with wake effects. This study shows that the maximum power in a single column is achieved by keeping the Induction Factor at one-third and only changing the yaw angle to deflect the wake. We then propose a dynamic programming formulation to maximize the total power production in a windfarm with a single column of turbines using yaw angle as the control variable. We also extend our expressions to a windfarm with multiple rows and columns of turbines and perform simulations on the 3 × 3 and 4 × 4 grid topologies. Our results show that the optimal Induction Factor for most turbines is quite close to one-third and yaw angle acts as the dominant optimization variable.
Wei Cheng Wang - One of the best experts on this subject based on the ideXlab platform.
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Aerodynamic design and analysis of a 10 kW horizontal-axis wind turbine for Tainan, Taiwan
Clean Technologies and Environmental Policy, 2016Co-Authors: Chi Jeng Bai, Bullet Po-wei Chen, Bullet Wei-cheng Wang, Wei Cheng WangAbstract:The purpose of the present study is to develop a small-scale horizontal-axis wind turbine (HAWT) suit-able for the local wind conditions of Tainan, Taiwan. The wind energy potential was first determined through the Weibull wind speed distribution and then was adapted to the design of the turbine blade. Two numerical approaches were adopted in the design and analysis of the HAWT turbine blades. The blade element momentum theory (BEMT) was used to lay out the shape of the turbine blades (S822 and S823 airfoils). The geometry of the root region of the turbine blade was then modified to facilitate inte-gration with a pitch control system. A mathematical model for the prediction of aerodynamic performance of the S822 and S823 airfoils, in which the lift and drag coefficients are calculated using BEMT equations, was then developed. Finally, computational fluid dynamics (CFD) was used to examine the aerodynamic characteristics of the resulting turbine blades. The resulting aerodynamic performance curves obtained from CFD simulation are in agreement with those obtained using BEMT. It is also observed that separation flow occurred at the turbine blade root at the tip speed ratios of 5 and 7. Keywords Horizontal-axis wind turbine (HAWT) Á Wind energy potential Á Weibull wind speed distribution Á Blade element momentum theory (BEMT) Á Aerodynamic performance Á Computational fluid dynamics (CFD) List of symbols a Axial Induction Factor a 0 Angular Induction Factor CP Power coefficient c(r) Chord length (m) C T Thrust coefficient C l Lift coefficient C l,s Lift coefficient at stall angle of attack C l,max Lift coefficient associated with maximum lift– drag ratio C d Drag coefficient C d,s Drag coefficient at stall angle of attack C d,max Drag coefficient depending on aspect ratio C l,3D Lift coefficient with 3D effect C d,3D Drag coefficient with 3D effect F Tip loss Factor F T Thrust (n) N b Number of blades P m Mechanical power (W) P r Rated power (W) r Local radius of blade R Radius of blade (m) R root Radius of blade at root (m) T m Mechanical torque (n m) V Wind speed (m/s) V r Rated wind speed (m/s) DC l Lift coefficient prior to flow separation DC d Drag coefficient prior to flow separation k Tip speed ratio k d Design tip speed ratio u Angle of relative wind (°) q Air density (kg/m 3) r Local solidity x Rotational speed (rpm) h p Pitch angle (°)
Marco Gobbetti - One of the best experts on this subject based on the ideXlab platform.
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The acid-stress response in Lactobacillus sanfranciscensis CB1.
Microbiology (Reading England), 2020Co-Authors: Maria De Angelis, Luca Bini, Vitaliano Pallini, Pier Sandro Cocconcelli, Marco GobbettiAbstract:Lactobacillus sanfranciscensis CB1, an important sourdough lactic acid bacterium, can withstand low pH after initial exposure to sublethal acidic conditions. The sensitivity to low pH varied according to the type of acid used. Treatment of LB: sanfranciscensis CB1 with chloramphenicol during acid adaptation almost completely eliminated the protective effect, suggesting that Induction of protein synthesis was required for the acid-tolerance response. Two constitutively acid-tolerant mutants, CB1-5R and CB1-7R, were isolated using natural selection techniques after sequential exposure to lactic acid (pH 3.2). Two-dimensional gel electrophoresis analysis of protein expression by non-adapted, acid-adapted and acid-tolerant mutant cells of LB: sanfranciscensis showed changes in the levels of 63 proteins. While some of the modifications were common to the acid-adapted and acid-tolerant mutant cells, several differences, especially regarding the induced proteins, were determined. The two mutants showed a very similar level of protein expression. Antibodies were used to identify heat-shock proteins DnaJ, DnaK, GroES and GrpE. Only GrpE showed an increased level of expression in the acid-adapted and acid-tolerant mutants as compared with non-adapted cells. The N-terminal sequence was determined for two proteins, one induced in both the acid-adapted and mutant cells and the other showing the highest Induction Factor of those proteins specifically induced in the acid-adapted cells. This second protein has 60% identity with the N-terminal portion of YhaH, a transmembrane protein of Bacillus subtilis, which has 54 and 47% homology with stress proteins identified in Listeria monocytogenes and Bacillus halodurans. The constitutively acid-tolerant mutants showed other different phenotypic features compared to the parental strain: (i) the aminopeptidase activity of CB1-5R decreased and that of CB1-7R markedly increased, especially in acid conditions; (ii) the growth in culture medium at 10 degrees C and in the presence of 5% NaCl was greater (the same was found for acid-adapted cells); and (iii) the acidification rate during sourdough fermentation in acid conditions was faster and greater.
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The acid-stress response in Lactobacillus sanfranciscensis CB1
Microbiology, 2001Co-Authors: Maria De Angelis, Luca Bini, Vitaliano Pallini, Pier Sandro Cocconcelli, Marco GobbettiAbstract:Lactobacillus sanfranciscensis CB1, an important sourdough lactic acid bacterium, can withstand low pH after initial exposure to sublethal acidic conditions. The sensitivity to low pH varied according to the type of acid used. Treatment of Lb. sanfranciscensis CB1 with chloramphenicol during acid adaptation almost completely eliminated the protective effect, suggesting that Induction of protein synthesis was required for the acid-tolerance response. Two constitutively acid-tolerant mutants, CB1-5R and CB1-7R, were isolated using natural selection techniques after sequential exposure to lactic acid (pH 3·2). Two-dimensional gel electrophoresis analysis of protein expression by non-adapted, acid-adapted and acid-tolerant mutant cells of Lb. sanfranciscensis showed changes in the levels of 63 proteins. While some of the modifications were common to the acid-adapted and acid-tolerant mutant cells, several differences, especially regarding the induced proteins, were determined. The two mutants showed a very similar level of protein expression. Antibodies were used to identify heat-shock proteins DnaJ, DnaK, GroES and GrpE. Only GrpE showed an increased level of expression in the acid-adapted and acid-tolerant mutants as compared with non-adapted cells. The N-terminal sequence was determined for two proteins, one induced in both the acid-adapted and mutant cells and the other showing the highest Induction Factor of those proteins specifically induced in the acid-adapted cells. This second protein has 60% identity with the N-terminal portion of YhaH, a transmembrane protein of Bacillus subtilis, which has 54 and 47% homology with stress proteins identified in Listeria monocytogenes and Bacillus halodurans. The constitutively acid-tolerant mutants showed other different phenotypic features compared to the parental strain: (i) the aminopeptidase activity of CB1-5R decreased and that of CB1-7R markedly increased, especially in acid conditions; (ii) the growth in culture medium at 10 °C and in the presence of 5% NaCl was greater (the same was found for acid-adapted cells); and (iii) the acidification rate during sourdough fermentation in acid conditions was faster and greater.
P A Sharp - One of the best experts on this subject based on the ideXlab platform.
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Purification of the cellular C1 Factor required for the stable recognition of the Oct-1 homeodomain by the herpes simplex virus alpha-trans-Induction Factor (VP16).
Journal of Biological Chemistry, 1993Co-Authors: T M Kristie, P A SharpAbstract:Abstract The assembly of specific multiprotein complexes on the herpes simplex virus alpha/IE (immediate early) enhancer elements requires the interactions of the Oct-1 POU homeodomain, the viral alpha TIF (alpha-trans-Induction Factor) (VP16), and at least one additional cellular Factor, the C1 Factor. The C1 Factor interacts directly with alpha TIF, likely forming an intermediate protein complex that recognizes the Oct-1 homeodomain-DNA complex. The biochemical purification of the mammalian C1 Factor suggests that it is composed of multiple subunits of related, but heterogeneous, polypeptides. The interaction of a subset of these polypeptides with alpha TIF is stimulated by post-translational modifications of the C1 proteins, suggesting that this Factor may be a critical target for the regulation of the herpes simplex virus alpha/IE transcription.