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RISS 인기검색어
- 검색키워드
- 저자 : Herbert Martins Gomes (검색결과 3 건)
- 무료
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Design Optimization of Tapered Steel Wind Turbine Towers by QPSO Algorithm
Augusto Furlanetto,Herbert Martins Gomes,Felipe Schaedler de Almeida 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.5
Wind energy has become one of the most widely used alternative energy sources in recent years due to its clean and renewable character. In the context of increasing demand for new facilities, the cost of a wind turbine is a key factor for the success of new wind farms. The reduction of the amount of material used to build the wind turbine tower is one way to reduce the project cost. This work presents a methodology for the minimization of the weight of the tubular steel towers of wind turbines using a metaheuristic optimization algorithm. The diameters of the cross-section at the base and the top of the conical tower are considered as continuous design variables. Due to constructional aspects, the tower is manufactured in many segments, which wall thicknesses are taken as discrete design variables. Besides the dead load, the design considers the action of wind load, which is taken as an equivalent static force determined using the Brazilian standard NBR6123. The design constraints considered in this work are the maximum admissible displacements at the top of the tower under service condition, the tower’s lowest natural frequency and the safety criteria for steel structures defi ned by the Brazilian standard NBR8800. The mixed-integer nonlinear optimization problem formulated for the structural design in this work is solved using the quantum particle swarm optimization algorithm (QPSO). On average, the QPSO solution was 12% lighter than designs based on other well-established algorithms in a comparative study. Nonetheless, no signifi cant improvement was observed concerning the standard particle swarm optimization.
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Time and Frequency Domain Analysis of Wind Turbine Towers Under Spatially Correlated Wind Field
Dodani Renan de Morais,Lucas Carminatti Foschiera,Herbert Martins Gomes 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.6
This work proposes a methodology to evaluate the dynamic behavior of Wind Turbine Towers (WTT) taking into account the eff ects of wind on its structural components (tower, nacelle, and blades). A model to generate wind velocity signals that are correlated in time and space is adopted, following a usual von Kármán Power Spectral Density (PSD) which has parameters such as turbulence intensities and standard deviations of the wind speed fl uctuations in the three directions, velocity profi le with height, and decay coeffi cients of the coherence with the distance between the points of simulation. It is investigated whether the time domain (TD) or frequency domain (FD) analysis is adequate in terms of simulation time, accuracy and computational costs for the evaluation of RMS values of acceleration and displacement signals at specifi c points of the WTT as well as base reactions. In FD the direct integration of specifi c PSD (displacements, accelerations, etc.) is employed. Results for a typical simulation are investigated and compared in diff erent situations of wind speed and wind parameters for the simulation of the dynamic behavior of the WTT. The results present the importance of the spatial simulation of wind velocity correlation to account for important fi nal structural behavior.
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Renata Araujo e Amariz,Italo Herbert Lucena Cavalcant,Antonio Gustavo de Luna Souto,Rogerio dos Santos Martins,Fernando Antonio Lima Gomes,Adriana da Silva Santos,Walber Felix dos Santos,Monica Cristi 한국원예학회 2023 원예과학기술지 Vol.41 No.6
Suitable mango rootstock selection has directly influenced plant mineral composition and vigor in the field. However, little is known about this in relation to mango cultivars in the São Francisco Valley region of Brazil. Thus, this study aimed to evaluate the dry matter accumulation and nutritional status of three Israeli mango seedling types (‘Shelly’, ‘Omer’, and ‘Agam’) grafted onto ‘Coquinho’ and ‘Espada’ rootstocks. The experiment was carried out between December of 2020 and April of 2021 in a nursery on the Agricultural Sciences Campus of the Federal University of São Francisco. It utilized a 3 × 2 factorial scheme, corresponding to the three Israeli mango cultivars as a scion and two rootstocks. Treatments were distributed in randomized blocks, with three replications and ten plants per plot. At 135 days after grafting, the dry matter and leaf nutritional status of the macronutrients, micronutrients, and sodium were evaluated. Seedlings with the Espada/Agam and Espada/Omer combinations showed greater vigor for transplanting in the field. The nutritional status of Israeli cultivars is not influenced only by the rootstock but also by the rootstock/rootstock combination, with higher nutritional concentrations for ‘Espada’ with ‘Agam’ and ‘Omer’, as well as ‘Coquinho’ with ‘Shelly’. Properly choosing the rootstock and scion for Israeli mango seedling formation can improve management in the field, mainly in terms of plant nutritional needs.
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