Formulasi Sediaan Sabun Mandi Padat Ekstrak Etanol Daun Bidara (Ziziphus Mauritiana Lamk.)

Tanaman bidara (Ziziphus mauritiana Lamk) merupakan salah satu tanaman yang digunakan sebagai obat tradisional khususnya bagian daun yang mengandung metabolit sekunder seperti flavonoid dan polifenol yang memiliki aktivitas sebagai antioksidan. Penelitian ini dilakukan bertujuan untuk mendapatkan formula sabun mandi padat ekstrak etanol daun bidara (Ziziphus mauritiana Lamk) yang memenuhi syarat karakteristik sabun mandi padat. Ekstrak daun bidara diperoleh dengan cara maserasi menggunakan pelarut etanol 70% kemudian dipekatkan untuk mendapatkan ekstrak kental. Ekstrak kental daun bidara (Ziziphus mauritiana Lamk) sebanyak 4% kemudian diformulasikan menjadi 3 formula sabun mandi padat yang berbeda. Formula I menggunakan minyak sawit dan zaitun, formula II menggunakan minyak kelapa dan jagung, Formula III menggunakan VCO dan minyak jarak. Pengujian karakteristik sabun dilakukan selama 30 hari meliputi uji organoleptis, homogenitas, kadar air, kadar asam lemak bebas, kadar alkali bebas dan nilai pH. Hasil uji selama 30 hari menunjukkan bahwa Formula I, II dan III hanya memenuhi syarat sabun berupa organoleptis meliputi bentuk, warna dan aroma, kadar asam lemak bebas dan nilai pH serta tidak memenuhi syarat homogenitas, kadar air dan kadar alkali beba

Optimal control of wind farm power extraction in large eddy simulations

In the present work we couple flow simulations performed using Large Eddy Simulations (LES) with gradient based optimization to control individual turbine in a farm, so as to achieve an increase in the total power output. The controls in our optimization problem are the disk-based thrust coefficients C′T,n of individual turbines as function of time. We use a gradient-based algorithm for the optimization and the gradients are computed using the adjoint method; the adjoint equations are formulated directly from the LES equation and the cost functional. We employ a receding-horizon predictive control setting and solve the optimization problem iteratively at each time horizon based on the gradient information obtained from the evolution of the flow field and the adjoint computation. In this paper we further elaborate the optimization techniques, interpret the simulation of adjoint field and present results for the wind-farm boundary layer cases. We find that the extracted farm power increases by approximately 20%, during optimal control. However, the increased power output is also responsible for an increase in turbulent dissipation, and a deceleration of the boundary layer. These issues are further discussed.status: publishe

Optimal Coordinated Control of Power Extraction in LES of a Wind Farm with Entrance Effects

We investigate the use of optimal coordinated control techniques in large eddy simulations of wind farm boundary layer interaction with the aim of increasing the total energy extraction in wind farms. The individual wind turbines are considered as flow actuators, and their energy extraction is dynamically regulated in time, so as to optimally influence the flow field. We extend earlier work on wind farm optimal control in the fully-developed regime (Goit and Meyers 2015, J. Fluid Mech. 768, 5–50) to a ‘finite’ wind farm case, in which entrance effects play an important role. For the optimal control, a receding horizon framework is employed in which turbine thrust coefficients are optimized in time and per turbine. Optimization is performed with a conjugate gradient method, where gradients of the cost functional are obtained using adjoint large eddy simulations. Overall, the energy extraction is increased 7% by the optimal control. This increase in energy extraction is related to faster wake recovery throughout the farm. For the first row of turbines, the optimal control increases turbulence levels and Reynolds stresses in the wake, leading to better wake mixing and an inflow velocity for the second row that is significantly higher than in the uncontrolled case. For downstream rows, the optimal control mainly enhances the sideways mean transport of momentum. This is different from earlier observations by Goit and Meyers (2015) in the fully-developed regime, where mainly vertical transport was enhanced

〈原著論文〉A method for the design of a scaled wind turbine for wind tunnel experiments

The current work introduces a blade element momentum theory-based tool called BEMTurbine for designing and evaluating the performance of wind turbines. BEMTurbine is a python-based open source tool that can be used to optimize blade parameters (chord length and twist angle) for the aerodynamic performance. This tool is then used to design a model wind turbine with a rotor diameter 0.25 m and the optimum tip speed ratio of 5. Rotor of this turbine is manufactured using a 3D printer. The BEM analysis shows that the maximum power coefficient of the model turbine is 0.47, and is attained at the design tip speed ratio of 5.Ⅲ.論文