Performance comparison of six numerical methods in estimating Weibull parameters for wind energy application

Comparison of seven numerical methods for determining Weibull parameters for wind energy generation in the northeast region of Brazil

Against the background of steadily increasing wind power generation worldwide, wind turbine manufacturers are continuing to develop a range of configurations with different combinations of pitch control, rotor speeds, gearboxes, generators and converters. This paper categorizes the main designs, focusing on their reliability by bringing together and comparing data from a selection of major studies in the literature. These are not particularly consistent but plotting failure rates against hours lost per failure reveals that problems with blades and gearboxes tend to lead to the greatest downtimes. New, larger wind turbines tend to fail more frequently than smaller ones so condition monitoring will become increasingly necessary if levels of reliability are to be improved.

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Wind turbine reliability analysis

Assessing different parameters estimation methods of Weibull distribution to compute wind power density

Power curve of a wind turbine depicts the relationship between output power and hub height wind speed and is an important characteristic of the turbine. Power curve aids in energy assessment, warranty formulations, and performance monitoring of the turbines. With the growth of wind industry, turbines are being installed in diverse climatic conditions, onshore and offshore, and in complex terrains causing significant departure of these curves from the warranted values. Accurate models of power curves can play an important role in improving the performance of wind energy based systems. This paper presents a detailed review of different approaches for modelling of the wind turbine power curve. The methodology of modelling depends upon the purpose of modelling, availability of data, and the desired accuracy. The objectives of modelling, various issues involved therein, and the standard procedure for power performance measurement with its limitations have therefore been discussed here. Modelling methods described here use data from manufacturers’ specifications and actual data from the wind farms. Classification of modelling methods, various modelling techniques available in the literature, model evaluation criteria, and application of soft computing methods for modelling are then reviewed in detail. The drawbacks of the existing methods and future scope of research are also identified.

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A Critical Review on Wind Turbine Power Curve Modelling Techniques and Their Applications in Wind Based Energy Systems

A new method to estimate Weibull parameters for wind energy applications

Necessary and sufficient conditions for the linearization of the one-dimensional Ito stochastic differential equations driven by fractional Brownian motion (fBm) are given Stochastic integrating factor has been introduced A modified Milstein method has been developed to obtain numerical solutions Analytical solutions have been compared with the numerical solutions for linearizable equations

Exact linearization of one dimensional Itô equations driven by fBm: Analytical and numerical solutions


 Pipettes with nano-sized openings, also known as nanopipettes, are frequently used in biotechnology as sensors, intracellular injectors or probes for microscopy. Their small tips in nano-scale conical geometry and easy fabrication make nanopipettes a preferred and alternative tool for sensor applications. In this review, we start with a brief introduction on fabrication and characterization of nanopipettes as well as sensing paradigms. Then we provide up-to-date publications mostly focusing on recent developments and examples of sensor applications of nanopipettes.An additional part is dedicated for probe and electrode applications of nanopipettes because of their increasing use in various areas. The majority of applications included in this review covers single molecule detection, nanoparticle detection and selective sensing experiments.

Review—Nanopipette Applications as Sensors, Electrodes, and Probes: A Study on Recent Developments

Extended Abstract The breakdown of the momentum transfer at a fluid-solid contact has been known in micro/nanofluidics for many years. Influence of the surface shape (i.e. convex/concave) has been investigated in gas-phase flows [1-2]. On the other hand, thermal boundary resistance is a known phenomenon, which reduces the heat transfer between heterogeneous materials and affects overall thermal performance, has not been investigated sufficiently well at curved interfaces. The present study runs non-equilibrium molecular dynamics (NEMD) simulations and considers a thin heated cylindrical shell, which is located in the middle of the gap between two coaxial stationary cylinders, in order to investigate the thermal boundary resistance. In contrast to previous molecular dynamics simulations [3-4], realistic walls are created to examine the interfacial heat transfer related to the surface curvature over rough and smooth surfaces. The results show the existence of the opposing effect of curvature. This effect demonstrates itself by increasing heat transfer from a hot concave surface to the fluid with curvature, while, in contrast, by decreasing heat transfer from a hot convex surface. At identical curvature and surface area, the present results show that the thermal resistance between a hot convex silver surface and liquid argon is larger than the thermal resistance between a hot concave silver surface and liquid argon. In addition,

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Thermal Resistance Of A Liquid-Solid Interface on Curved Smooth and Rough Walls

In this study, near wall solution of a hypersonic flow with high enthalpy gradient is obtained numerically. Since there are high temperature gradients, the governing equations of motion are modified with additional terms containing the derivatives of velocity and enthalpy. The finite difference is used in discretization of the equations. The resulting algebraic equations are solved with block elimination or with the Block Krylov technique. The domain decomposition method is implemented for the parallel solution. At the interfaces, the matching and overlapping nodes are used. In order to reduce the number of iterations Aitken’s acceleration is implemented at the interfaces. With the aid of this acceleration, almost 90% parallel efficiency is achieved with 64 processors running on MPI.

Ali Dinler

Papers

A new method to estimate Weibull parameters for wind energy applications

Exact linearization of one dimensional Itô equations driven by fBm: Analytical and numerical solutions

Review—Nanopipette Applications as Sensors, Electrodes, and Probes: A Study on Recent Developments

Thermal Resistance Of A Liquid-Solid Interface on Curved Smooth and Rough Walls

Parallel solution of flows with high velocity and/or enthalpy gradients