Search results for "T method"
showing 10 items of 1254 documents
An affine scaling method using a class of differential barrier functions: primal approach
2020
International audience; In this paper we propose a family of affine scaling interior point algorithms, called galpv4, using a primal approach, based on a large class of differential barrier functions. We show that these algorithms are in fact an extension and generalization of the classical affine scaling algorithm based on the well-known log barrier function. After carrying out a complete convergence analysis, we select some of these algorithms for comparison with the classical affine scaling algorithm, performed with the help of the familiar Netlib test set.
Comparison of numerical modelling techniques for impact investigation on a wind turbine blade
2019
Wind turbine blades are exposed to numerous impact risks throughout their lifetimes. The impact risks range from bird collisions during operation to impacts with surrounding structures at the time of transportation and installation. Impact loads on the fibre composite blades can induce several complex, simultaneously interacting and visually undetectable damage modes and have a high potential to reduce the local and global blade stiffness. An assessment of such impact-induced damages is therefore necessary and usually involves high computational costs using numerical procedures, especially when analysing large composite components. To minimise this computational expense, different numerical…
Numerical investigation of rain droplet impact on offshore wind turbine blades under different rainfall conditions: A parametric study
2020
The leading edge of a fiber composite wind turbine blade (WTB) is prone to erosion damages due to repeated rain droplet impact during its service life. Such damages are critical to the blade's aerodynamic as well as structural performance, ultimately resulting in substantial repair costs. An effective design of a coating material for WTB is necessary and its analysis must include variables associated with erosive rain droplets such as (1) droplet diameter, (2) impact velocity, and (3) droplet impact angle. The present paper develops and validates a coupled fluid structure interaction (FSI) computational model for simulating rain droplet impact on WTBs, where the structure domain is modelled…
Nonlinear scaled models in 3D calculation of transformer magnetic circuits
2006
PurposeTo make easier and faster the designing of transformers using scale models.Design/methodology/approachThe scale modeling in designing of transformers is included. Both computer and physical models of high leakage reactance (HLR) and 3‐phase (TP3C) transformers have been considered. The 3D field computations have been executed for the scaled models, and the results were recalculated to the full‐scaled ones.FindingsIt is possible to calculate the scale coefficients for nonlinear models of transformers using finite element method (FEM) software. Obtained coefficients are useful in the designing process. Measurements confirm correctness of the scaling laws.Research limitations/implicatio…
Air gap fringing flux reduction in a high frequency inductor for a solar inverter
2013
In a gapped inductor, air gap fringing flux induces eddy currents in conductors in the vicinity of the air gap producing unwanted power loss and heat in the coil. This paper presents a detailed analysis to evaluate the performance changes of a high frequency inductor used in a solar inverter by new arrangement scheme of the air gap locations. The effect of air gap positioning in the core and the ac-resistance and leakage inductance of the high frequency inductor used in a solar inverter is investigated by using the 2-D finite element analysis. The simulation results show that a significant improvement can be achieved with limited changes in the air gap locations.
A comparison of numerical surface topography calculations in geodynamic modelling: an evaluation of the ‘sticky air’ method
2012
SUMMARY Calculating surface topography in geodynamic models is a common numerical problem. Besides other approaches, the so-called ‘sticky air’ approach has gained interest as a free-surface proxy at the top boundary. The often used free slip condition is thereby vertically extended by introducing a low density, low viscosityfluid layer. This allows the air/crust interface to behave in a similar manner to a true free surface. We present here a theoretical analysis that provides the physical conditions under which the sticky air approach is a valid approximation of a true free surface. Two cases are evaluated that characterize the evolution of topography on different timescales: (1) isostati…
Image boundaries detection: from thresholding to implicit curve evolution
2014
The development of high dimensional large-scale imaging devices increases the need of fast, robust and accurate image segmentation methods. Due to its intrinsic advantages such as the ability to extract complex boundaries, while handling topological changes automatically, the level set method (LSM) has been widely used in boundaries detection. Nevertheless, their computational complexity limits their use for real time systems. Furthermore, most of the LSMs share the limit of leading very often to a local minimum, while the effectiveness of many computer vision applications depends on the whole image boundaries. In this paper, using the image thresholding and the implicit curve evolution fra…
Architecture-Driven Level Set Optimization: From Clustering to Sub-pixel Image Segmentation
2016
Thanks to their effectiveness, active contour models (ACMs) are of great interest for computer vision scientists. The level set methods (LSMs) refer to the class of geometric active contours. Comparing with the other ACMs, in addition to subpixel accuracy, it has the intrinsic ability to automatically handle topological changes. Nevertheless, the LSMs are computationally expensive. A solution for their time consumption problem can be hardware acceleration using some massively parallel devices such as graphics processing units (GPUs). But the question is: which accuracy can we reach while still maintaining an adequate algorithm to massively parallel architecture? In this paper, we attempt to…
A local level set method for liver segmentation in functional MR imaging
2011
Functional Magnetic Resonance (fMR) is a medical image technique in which a contrast is injected in the vascular system so that blood diffusion along it can be observed as variations of the signal intensity. The uptake variations of the contrast agent are used in early detection of tumorous tissue. For the diagnostic to be accurate, successive volumes must be correctly registered. For binary registration prior segmentation of the 3D fMR data is required. Here we present a local 3D level-set segmentation method which preserves details and edges, along with its multi-scale version which has the advantage of a great acceleration with respect to the single-scale version. Results of liver segmen…
Leverage Control and Quantitative Management: The Analysis of Amplification Effect on Financial System
2021
Maintaining the stability of financial leverage is a task in macro-economic management and also a challenge to be faced. Financial amplification characteristics dominate financial leverage system with low risk of capabilities, and the efficiency of this ability has two-sides results and proposes a lot of risks, however, most researchers have not found the best ways to solve this problem. Therefore, taking positive measures to strengthen the management of the financial system leverage feature becomes very important. In this paper, authors use comparative study and data analysis to illustrate the main problems of financial system leverage, the effect of leverage amplification characteristics,…