Search results for " method"
showing 10 items of 10455 documents
Combination of finite impulse response neural network technique with FDTD method for simulation of electromagnetic problems
1996
The finite difference time domain (FDTD) method requires long computation times for simulating resonant or high-Q structures. The authors incorporate the finite impulse response neural network technique as a predictor in order to save time in FDTD simulations. The applicability of the technique is demonstrated by carrying out an analysis of a waveguide filter.
Fast and accurate analysis and design of substrate integrated waveguide (SIW) filters
2007
This paper describes the application of the boundary integral-resonant mode expansion (BI-RME) method to the accurate modelling of substrate integrated waveguides (SIW). The new formulation fully exploits the particular geometry of this class of structures, thus providing a very efficient analysis method to be used within CAD tools of SIW filters. The advantages of this method have been proved with the successful design of two filters operating in the microwave and millimeter-wave bands.
Light-Scattering and -Absorption of Nanoparticles
2012
To understand the optical response of nanoparticles to the incident light, a theoretical description is needed, which is given in this chapter. In a first approximation, these optical properties can be described using a quasi-static model, which assumes a particle-size much smaller than the wavelength of the light. The derivation of the polarizability of a sphere, which describes its optical properties, and further extensions for spheroidal, rod-shaped and coated particles are given in Sect. 2.2.
A multiscale method for gamma/h discrimination in extensive air showers
2011
We present a new method for the identification of extensive air showers initiated by different primaries. The method uses the multiscale concept and is based on the analysis of multifractal behaviour and lacunarity of secondary particle distributions together with a properly designed and trained artificial neural network. The separation technique is particularly suited for being applied when the topology of the particle distribution in the shower front is as largely detailed as possible. Here, our method is discussed and applied to a set of fully simulated vertical showers in the experimental framework of ARGO-YBJ, taking advantage of both the space and time distribution of the detected sec…
Testing Soil Encasing Materials for Measuring Hydraulic Conductivity of a Sandy-Loam Soil by the Cube Methods
2008
The Cube Method (CM) and the Modified Cube Method (MCM) were developed for measuring vertical (K v ) and horizontal (K h ) saturated hydraulic conductivity of a single soil sample. By these methods, a cube of soil is carved out in situ and a suitable material is applied to enclose the cube in a tightly fitting casing before moving the sample to the laboratory. Problems may be associated with the use of gypsum, originally used to encase soil. The suitability of molten wax and expandable polyurethane foam to encase a soil cube was tested for a sandy-loam soil. Wax-treated samples yielded lower conductivity results than untreated samples by a maximum factor of 3.7. The observed discrepancies w…
Constructing Knowledge through a Role-Play in a Web-Based Learning Environment
2003
This study aimed to find out how and on what level the students of two separate secondary schools shared and constructed knowledge on imperialism by interacting through historical role characters in a Web-based environment. Furthermore, the study aimed to find out how social and contextual features affected the nature of knowledge sharing and construction. The data about the history project were gathered by various means in order to validate the findings of the case study. The results demonstrated that the level of the Web-based messages remained quite low. Also the use of the Web-based environment in terms of shared knowledge construction was rather weak. In comparison, different instruct…
Identifying legitimate Web users and bots with different traffic profiles — an Information Bottleneck approach
2020
Abstract Recent studies reported that about half of Web users nowadays are intelligent agents (Web bots). Many bots are impersonators operating at a very high sophistication level, trying to emulate navigational behaviors of legitimate users (humans). Moreover, bot technology continues to evolve which makes bot detection even harder. To deal with this problem, many advanced methods for differentiating bots from humans have been proposed, a large part of which relies on supervised machine learning techniques. In this paper, we propose a novel approach to identify various profiles of bots and humans which combines feature selection and unsupervised learning of HTTP-level traffic patterns to d…
Analysis of different key behavioral patterns to score in elite taekwondoists according to the weight category and gender
2021
Traditionally, research in taekwondo has focused on athletes' overall performance considering the entire sample of the tournament or analyzed selected bouts while ignoring behavioral differences of athletes according to their gender and weight category. Thus, the aim of this study was to analyze the behavioral patterns used to score points in the London Olympic Games according to gender and weight category [fin (FW), feather (FTW), light (LW), and heavy (HW)] of the athletes. A total of 24,940 actions were analyzed by using observational methodology, a mixed method methodology where lag sequential and polar coordinate analysis were applied. Different patterns could be seen in the actions pe…
Revista complutense de educación
2015
The incorporation of the European Credit Transfer System (ECTS) will pay off soon with the release of the first labor market new-plan graduates. In this study an initial assessment of the results is done by analyzing whether the curriculum (new-plan degree or old-plan degree) and the use of new teaching methodologies have led to significant differences in academic performance or if, on the contrary, they did not. These results suggest that this performance is higher for old-plan graduates, and also for those who have benefited from a new pedagogical tool (students from both the old and new plan). Data used corresponds to that from two different classes, one of them from an old-plan double d…
Fast nonstationary preconditioned iterative methods for ill-posed problems, with application to image deblurring
2013
We introduce a new iterative scheme for solving linear ill-posed problems, similar to nonstationary iterated Tikhonov regularization, but with an approximation of the underlying operator to be used for the Tikhonov equations. For image deblurring problems, such an approximation can be a discrete deconvolution that operates entirely in the Fourier domain. We provide a theoretical analysis of the new scheme, using regularization parameters that are chosen by a certain adaptive strategy. The numerical performance of this method turns out to be superior to state-of-the-art iterative methods, including the conjugate gradient iteration for the normal equation, with and without additional precondi…