SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Lundengård Karl 1987 ) "

Sökning: WFRF:(Lundengård Karl 1987 )

  • Resultat 1-25 av 41
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Boulougari, Andromachi, et al. (författare)
  • Application of a power-exponential function-based model to mortality rates forecasting
  • 2019
  • Ingår i: Communications in Statistics: Case Studies, Data Analysis and Applications. - : Informa UK Limited. - 2373-7484. - 9786185180270 - 9786185180294 ; 5:1, s. 3-10
  • Tidskriftsartikel (refereegranskat)abstract
    • There are many models for mortality rates. A well-known problem that complicates modeling of human mortality rates is the “accident hump” occurring in early adulthood. Here, two models of mortality rate based on power-exponential functions are presented and compared to a few other models. The models will be fitted to known data of measured death rates from several different countries using numerical techniques for curve-fitting with the nonlinear least-squares method. The properties of the model with respect to forecasting with the Lee–Carter method will be discussed.
  •  
2.
  • Elchinger, Olivier, et al. (författare)
  • Brackets with (τ,σ)-derivations and (p,q)-deformations of Witt and Virasoro algebras
  • 2016
  • Ingår i: Forum mathematicum. - : Walter de Gruyter GmbH. - 0933-7741 .- 1435-5337. ; 28:4, s. 657-673
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this paper is to study some brackets defined on (τ,σ)-derivations satisfying quasi-Lie identities. Moreover, we provide examples of (p, q)-deformations of Witt and Virasoro algebras as well as sl(2) algebra. These constructions generalize the results obtained by Hartwig, Larsson and Silvestrov on σ-derivations, arising in connection with discretizations and deformations of algebras of vector fields.
  •  
3.
  • Foskolos, Georgios, 1976-, et al. (författare)
  • The impact of aggregation interval on current harmonic simulation of aggregated electric vehicle loads
  • 2020
  • Ingår i: Proceedings of International Conference on Harmonics and Quality of Power, ICHQP. - : IEEE Computer Society. - 9781728136974
  • Konferensbidrag (refereegranskat)abstract
    • Electric vehicles (EVs) poses new challenges for the Distribution System Operator (DSO). For example, EVs uses power electronic-based rectifiers for charging their batteries, an operation that could significantly impact Power Quality (PQ) in terms of harmonic distortion. The DSO responsibilities include ensuring grid code compliance confirmed by PQ metering. In general, 10 min rms values are sufficient. However, the large scale integration of non-linear loads, like EVs, could lead to new dynamic phenomena, possibly lost in the process of time aggregation.This paper presents an analysis of the impact on time aggregation (3 s-, 1min-and 10 min rms), when modelling current harmonics of aggregated EV loads, using power exponential functions. The results indicate that, while3 s rms and 1 min rms marginally affect the outcome, 10 min rms aggregation will lead to a significant deviation (>30%) in terms of maximum current harmonic magnitude. 
  •  
4.
  • Javor, V., et al. (författare)
  • A Study on Frequency Spectrum of Electrostatic Discharge Currents and Lightning Currents
  • 2019
  • Ingår i: 2019 14th International Conference on Advanced Technologies, Systems and Services in Telecommunications, TELSIKS 2019 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728108780 ; , s. 198-201
  • Konferensbidrag (refereegranskat)abstract
    • Electrostatic discharges (ESD) consequences are not only damages, but also very fast transients in electric circuits and devices, as well as in large power systems. This paper presents frequency spectrum analysis of the IEC 61000-4-2 standard current approximated by multi-peaked analytically extended function (MP-AEF) and of typical lightning currents according to the IEC 62305 standard. This analysis is important for the choice of protective devices and frequency range of measurement equipment used in experiments. A comparison of the measured and theoretical results is also given.
  •  
5.
  • Javor, Vesna, et al. (författare)
  • Analytical Representation of Measured Lightning Currents and Its Application to Electromagnetic Field Estimation
  • 2018
  • Ingår i: IEEE transactions on electromagnetic compatibility (Print). - : IEEE. - 0018-9375 .- 1558-187X. ; 60:5, s. 1415-1426
  • Tidskriftsartikel (refereegranskat)abstract
    • Lightning discharge currents waveshapes and their derivatives with multiple peaks are measured in artificially triggered lightning experiments and at instrumented tall towers. Such waveshapes are represented in this paper by the N-peaked analytically extended function (NP-AEF) and Marquardt least-squares method is applied for the estimation of its nonlinear parameters. Typical channel-base currents of the first negative, subsequent negative strokes, and positive strokes, based on comprehensive measurements by Berger et al. at Monte San Salvatore in Switzerland, are approximated by NP-AEFs and used in the computation of lightning electromagnetic fields. A new attenuation factor introducing nonlinear current attenuation along the channel is applied within the modified transmission line model (MTLSIN). A lightning return stroke is assumed to have a vertical discharge channel at the perfectly conducting ground. In order to validate this model, calculated lightning electromagnetic fields are compared with the typical, as measured by Lin et al. at various distances from the discharges. Lightning currents and their derivatives measured at the tall towers are also approximated by NP-AEFs. For the measured artificially triggered lightning currents, MTLSIN is applied for the calculation of their electromagnetic fields. These are compared with the measured fields of specific lightning strokes, so as to results of other models.
  •  
6.
  • Javor, Vesna, et al. (författare)
  • Application of Genetic Algorithm to Estimation of Function Parameters in Lightning Currents Approximations
  • 2017
  • Ingår i: International Journal of Antennas and Propagation. - : Hindawi Limited. - 1687-5869 .- 1687-5877. ; 2017
  • Tidskriftsartikel (refereegranskat)abstract
    • Genetic algorithm (GA) is applied for the estimation of two-peaked analytically extended function (2P-AEF) parameters in this paper. 2P-AEF is used for approximation of measured and typical lightning discharge currents. Lightning discharge channel is often modeled as thin-wire vertical antenna at perfectly conducting ground. Engineering lightning stroke models assume that the current along that channel is related to the channel-base current which may be measured at the instrumented tall towers and in triggered lightning experiments. Mathematical modeling of lightning currents is important in verification of lightning strokes models based on simultaneously measured electromagnetic fields at various distances, so as in lightning protection studies, computation of lightning induced effects and simulation of overvoltages in power systems. Typical lightning discharge currents of the first positive, first negative, and subsequent negative strokes are defined by IEC 62305 Standard based on comprehensive measurements. Parameters of 2P-AEF’s approximation of the typical negative first stroke current are determined by GA and compared to approximations obtained by other functions. Measured currents at Monte San Salvatore in Switzerland, at Morro de Cachimbo Station in Brazil, and in rocket-triggered lightning experiments at Camp Blanding in Florida are approximated by 2P-AEFs, and good agreement with experimentally measured waveshapes is obtained.
  •  
7.
  • Javor, Vesna, et al. (författare)
  • Electrostatic discharge currents and their derivatives' approximation by piecewise power-exponential functions
  • 2018
  • Ingår i: Turkish Journal of Electrical Engineering and Computer Sciences. - : The Scientific and Technological Research Council of Turkey (TUBITAK-ULAKBIM) - DIGITAL COMMONS JOURNALS. - 1300-0632 .- 1303-6203. ; 26:2, s. 1093-1102
  • Tidskriftsartikel (refereegranskat)abstract
    • An analytically extended function based on power-exponential functions is used in this paper for approxi- mation of electrostatic discharge (ESD) currents and their derivatives. The Marquardt least-squares method (MLSM) is applied for obtaining nonlinear function parameters. IEC 61000-4-2 Standard ESD current is approximated, as well as some measured ESD currents' wave shapes. Power-exponential terms are extended at the local maxima and minima of the represented wave shape, so that this approximation is done from peak to peak. ESD current derivative is approxi- mated using the same procedure in order to obtain the continuous second order derivative of the current, as all piecewise functions are of differentiability class C1L . Currents and their derivatives are often measured in ESD experiments so that their analytical representation is needed for simulation of ESD phenomena, better definition of standard requirements, and computation of the transient fields and induced effects.
  •  
8.
  • Javor, Vesna, et al. (författare)
  • Modeling of Artificially-Triggered Lightning Currents by Multi-Peaked Analytically Extended Functions
  • 2018
  • Ingår i: Compel. - : Emerald Group Publishing Limited. - 0332-1649. ; 37:4, s. 1354-1365
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: This paper aims to present the approximation of lightning currents waveshapes by the multi-peaked analytically extended function (MP-AEF) for the experimentally measured channel-base currents in the artificially triggered lightning discharges. Modified transmission line model of lightning return strokes having the channel current both linearly decaying and sinusoidally changing with height (MTLSIN) is used to calculate the lightning electromagnetic field.Design/methodology/approach: MP-AEF’s parameters for the artificially triggered lightning channel-base currents are calculated by using Marquardt least squares method (MLSM). Lightning electromagnetic fields are calculated based on electromagnetic theory relations, thin-wire antenna model of the vertical lightning channel and the assumption of the perfectly conducting ground. MTLSIN model as an engineering model of lightning strokes is used to obtain the electric field results as these are simultaneously measured in rocket-triggered lightning experiments together with the channel-base currents. Findings: MP-AEF approximates multi-peaked pulse waveshapes. Some important function parameters are chosen prior to the approximation procedure, such as current peaks and the corresponding time moments of those peaks, which presents an advantage in comparison to other functions. The desired accuracy of approximation is obtained by choosing an adequate number of function terms. MLSM is used for the estimation of unknown parameters. Using MTLSIN model, the influence of the channel height and return stroke speed on the lightning electromagnetic field waveshape is analyzed in this paper. Research limitations/implications: MP-AEF may be used for approximation of various multi-peaked waveshapes. It has no errors in the points of maxima which is important for the lightning protection systems design. MTLSIN model may be validated by using simultaneously measured lightning electromagnetic fields at various distances from the channel and for channel heights estimated in the experiments. It is also possible to approximate measured current derivatives by MP-AEF and use them for further computation. Originality/value: MTLSIN model is proposed in this paper for the evaluation of lightning electromagnetic fields induced by artificially triggered lightning discharges. The procedure is based on the approximation of lightning channel-base currents by the multi-peaked analytically extended function previously proposed by the authors. This function may be used not only for representing lightning currents but also for other waveshapes as current derivatives, electric and magnetic fields and their derivatives, which are all important for the lightning protection design. MTLSIN gives lightning electromagnetic fields results which are in better agreement with measured fields than those obtained by other models from literature.
  •  
9.
  • Javor, V., et al. (författare)
  • Modelling of measured lightning discharge currents to tall towers
  • 2017
  • Ingår i: Conference Proceedings - 2017 17th IEEE International Conference on Environment and Electrical Engineering and 2017 1st IEEE Industrial and Commercial Power Systems Europe, EEEIC / I and CPS Europe 2017. - : Institute of Electrical and Electronics Engineers Inc.. - 9781538639160
  • Konferensbidrag (refereegranskat)abstract
    • Lightning discharge currents and their derivatives have been measured at instrumented tall towers for a few decades already. Results of those measurements are used for lightning research purposes, modelling of lightning discharges and making improvements in lightning protection. Some of the measured lightning currents are represented in this paper by the multi-peaked analytically extended function (MP-AEF). The same function may be used for lightning current derivatives, thus providing their analytical integration. 
  •  
10.
  •  
11.
  • Lundengård, Karl, 1987-, et al. (författare)
  • An Examination of the Multi-Peaked Analytically Extended Function for Approximation of Lightning Channel-Base Currents
  • 2015
  • Ingår i: 12TH INTERNATIONAL CONFERENCE ON APPLIED ELECTROMAGNETICS PES2015. - : Faculty of Electronic Engineering (Niš). - 9788661251443
  • Konferensbidrag (refereegranskat)abstract
    • A multi-peaked version of the analytically extendedfunction (AEF) intended for approximation of multi-peaked light-ning current waveforms will be presented along with some of itsbasic properties. A general framework for estimating the parame-ters of the AEF using the Marquardt least-squares method(MLSM) for a waveform with an arbitrary (finite) number ofpeaks as well as a given charge transfer and specific energy willalso be described. This framework is used to find parameters forsome common single-peak wave-forms and some advantages anddisadvantages of the approach will be discussed.
  •  
12.
  • Lundengård, Karl, 1987-, et al. (författare)
  • Asian Options, Jump-Diffusion Processes on a Lattice, and Vandermonde Matrices
  • 2014
  • Ingår i: Modern Problems in Insurance Mathematics. - Cham : Springer International Publishing. - 9783319066523 - 9783319066530 ; , s. 335-363
  • Bokkapitel (refereegranskat)abstract
    • Asian options are options whose value depends on the average asset price during its lifetime. They are useful because they are less subject to price manipulations. We consider Asian option pricing on a lattice where the underlying asset follows the Merton–Bates jump-diffusion model. We describe the construction of the lattice using the moment matching technique which results in an equation system described by a Vandermonde matrix. Using some properties of Vandermonde matrices we calculate the jump probabilities of the resulting system. Some conditions on the possible jump sizes in the lattice are also given.
  •  
13.
  • Lundengård, Karl, 1987-, et al. (författare)
  • Construction of moment-matching multinomial lattices using Vandermonde matrices and Gröbner bases
  • 2017
  • Ingår i: AIP Conference Proceedings. - : American Institute of Physics (AIP). - 0094-243X. - 9780735414648 ; , s. 020094-1-020094-7
  • Konferensbidrag (refereegranskat)abstract
    • In order to describe and analyze the quantitative behavior of stochastic processes, such as the process followed by a financial asset, various discretization methods are used. One such set of methods are lattice models where a time interval is divided into equal time steps and the rate of change for the process is restricted to a particular set of values in each time step. The well-known binomial- and trinomial models are the most commonly used in applications, although several kinds of higher order models have also been examined. Here we will examine various ways of designing higher order lattice schemes with different node placements in order to guarantee moment-matching with the process. 
  •  
14.
  • Lundengård, Karl, 1987-, et al. (författare)
  • Electrostatic discharge current modelling using multi-peaked analytically extended function
  • 2017
  • Ingår i: Proceedings of 2nd International Multidisciplinary Conference on Computer and Energy Science (SpliTech). - : IEEE conference proceedings. - 9789532900712 ; , s. 272-277
  • Konferensbidrag (refereegranskat)abstract
    • In order to establish realistic requirements for ESD generators used in equipment and device testing, as well as to ensure and improve the repeatability of tests, an analytical expression of real electrostatic discharge (ESD) currents is sought for. It should be adoptable to various test levels, test set-ups and procedures, and also various ESD conditions (approach speeds, types of electrodes, relative arc length, humidity, etc). A mathematical function is necessary for computer simulation of such phenomena, for verification of test generators and for improving standard waveshape definition.
  •  
15.
  • Lundengård, Karl, 1987-, et al. (författare)
  • Electrostatic discharge currents representation using the analytically extended function with P peaks by interpolation on a D-optimal design
  • 2019
  • Ingår i: Facta Universitatis Series: Electronics and Energetics. - : UNIV NIS. - 0353-3670 .- 2217-5997. ; 32:1, s. 25-49
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper the Analytically Extended Function (AEF) with p peaks is used for representation of the electrostatic discharge (ESD) currents and lightning discharge currents. The fitting to data is achieved by interpolation of certain data points. In order to minimize unstable behaviour, the exponents of the AEF are chosen from a certain arithmetic sequence and the interpolated points are chosen according to a D-optimal design. The method is illustrated using several examples of currents taken from standards and measurements.
  •  
16.
  • Lundengård, Karl, 1987-, et al. (författare)
  • Electrostatic Discharge Currents Representation using the Multi-Peaked Analytically Extended Function by Interpolation on a D-Optimal Design
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Multi-peaked analytically extended function (AEF), previously applied by the authors to modelling of lightning discharge currents, is used in this paper for representation of the electrostatic discharge (ESD) currents. The fitting to data is achieved by interpolation of certain data points. In order to minimize unstable behaviour, the exponents of the AEF are chosen from a certain arithmetic sequence and the interpolated points are chosen according to a D-optimal design. ESD currents' modelling is illustrated through two examples: one corresponding to an approximation of the IEC Standard 61000-4-2 waveshape, and the other to representation of some measured ESD current.
  •  
17.
  • Lundengård, Karl, 1987-, et al. (författare)
  • Estimation of Parameters for the Multi-peaked AEF Current Functions
  • 2015
  • Ingår i: ASMDA 2015 Proceedings. - : ISAST: International Society for the Advancement of Science and Technology. - 9786185180058 ; , s. 623-636
  • Konferensbidrag (refereegranskat)abstract
    • Examination of how the analytically extended function (AEF) can be used to approximate multi-peaked lightning current waveforms, is performed in the paper. A general framework for estimating the parameters of the AEF using the Marquardt least-squares method (MLSM) for a waveform with an arbitrary (finite) number of peaks is presented. This framework is used to find parameters for some common waveforms with a single peak, such as one-peaked Standard IEC 62305 lightning currents.
  •  
18.
  • Lundengård, Karl, 1987- (författare)
  • Extreme points of the Vandermonde determinant and phenomenological modelling with power exponential functions
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis discusses two topics, finding the extreme points of the Vandermonde determinant on various surfaces and phenomenological modelling using power-exponential functions. The relation between these two problems is that they are both related to methods for curve-fitting. Two applications of the mathematical models and methods are also discussed, modelling of electrostatic discharge currents for use in electromagnetic compatibility and modelling of mortality rates for humans. Both the construction and evaluation of models is discussed.In the first chapter the basic theory for later chapters is introduced. First the Vandermonde matrix, a matrix whose rows (or columns) consists of monomials of sequential powers, its history and some of its properties are discussed. Next, some considerations and typical methods for a common class of curve fitting problems are presented, as well as how to analyse and evaluate the resulting fit. In preparation for the later parts of the thesis the topics of electromagnetic compatibility and mortality rate modelling are briefly introduced.The second chapter discusses some techniques for finding the extreme points for the determinant of the Vandermonde matrix on various surfaces including spheres, ellipsoids and cylinders. The discussion focuses on low dimensions, but some results are given for arbitrary (finite) dimensions.In the third chapter a particular model called the p-peaked Analytically Extended Function (AEF) is introduced and fitted to data taken either from a standard for electromagnetic compatibility or experimental measurements. The discussion here is entirely focused on currents originating from lightning or electrostatic discharges.The fourth chapter consists of a comparison of several different methods for modelling mortality rates, including a model constructed in a similar way to the AEF found in the third chapter. The models are compared with respect to how well they can be fitted to estimated mortality rate for several countries and several years and the results when using the fitted models for mortality rate forecasting is also compared.
  •  
19.
  • Lundengård, Karl, 1987-, et al. (författare)
  • Extreme points of the Vandermonde determinant on the sphere and some limits involving the generalized Vandermonde determinant
  • 2020
  • Ingår i: Algebraic Structures and Applications. - Cham : Springer Nature. - 9783030418496 - 9783030418502 ; , s. 761-789
  • Bokkapitel (refereegranskat)abstract
    • The values of the determinant of Vandermonde matrices with real elements are analyzed both visually and analytically over the unit sphere in various dimensions. For three dimensions some generalized Vandermonde matrices are analyzed visually. The extreme points of the ordinary Vandermonde determinant on finite-dimensional unit spheres are given as the roots of rescaled Hermite polynomials and a recursion relation is provided for the polynomial coefficients. Analytical expressions for these roots are also given for dimension three to seven. A transformation of the optimization problem is provided and some relations between the ordinary and generalized Vandermonde matrices involving limits are discussed.
  •  
20.
  • Lundengård, Karl, 1987- (författare)
  • Generalized Vandermonde matrices and determinants in electromagnetic compatibility
  • 2017
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Matrices whose rows (or columns) consists of monomials of sequential powers are called Vandermonde matrices and can be used to describe several useful concepts and have properties that can be helpful for solving many kinds of problems. In this thesis we will discuss this matrix and some of its properties as well as a generalization of it and how it can be applied to curve fitting discharge current for the purpose of ensuring electromagnetic compatibility.In the first chapter the basic theory for later chapters is introduced. This includes the Vandermonde matrix and some of its properties, history, applications and generalizations, interpolation and regression problems, optimal experiment design and modelling of electrostatic discharge currents with the purpose to ensure electromagnetic compatibility.The second chapter focuses on finding the extreme points for the determinant for the Vandermonde matrix on various surfaces including spheres, ellipsoids, cylinders and tori. The extreme points are analysed in three dimensions or more.The third chapter discusses fitting a particular model called the p-peaked Analytically Extended Function (AEF) to data taken either from a standard for electromagnetic compatibility or experimental measurements. More specifically the AEF will be fitted to discharge currents from the IEC 62305-1 and IEC 61000-4-2 standards for lightning protection and electrostatic discharge immunity as well as some experimentally measured data of similar phenomena.
  •  
21.
  • Lundengård, Karl, 1987-, et al. (författare)
  • Modelling mortality rates using the powerexponential function
  • 2017
  • Ingår i: Booklet of abstracts of SPAS2017 - International Conference on Stochastic Processes and Algebraic Structures– From Theory Towards Applications.
  • Konferensbidrag (refereegranskat)abstract
    • There are many models for the mortality rates of humans and other organisms. A phenomenon that complicates the modelling of human mortality rates is a rapid increase in mortality rate for young adults (in western Europe this is especially pronounced at the age of 25). We will examine models for mortality rates based on power-exponential functions, compare them to empirical data for mortality rates and other models.
  •  
22.
  • Lundengård, Karl, 1987-, et al. (författare)
  • Moment-matching multinomial lattices using Vandermonde matrices for option pricing
  • 2016
  • Ingår i: Stochastic and Data Analysis Methods and Applications in Statistics and Demography. - : ISAST. - 9786185180188 - 9786185180195 ; , s. 15-29
  • Konferensbidrag (refereegranskat)abstract
    • Lattice models are discretization methods that divide the life of a financial option into time steps of equal length and model the underlying asset movement at each time step. A financial option of American or European style can be evaluated conveniently via backward induction using a lattice model. The most common lattice models are the well-known binomial- and trinomial lattice models, although severalkinds of higher order models have also been examined in the literature. In the presentpaper we present an explicit scheme for creating a lattice model of arbitrary order and use the Vandermonde matrix to determine suitable parameters. Some selected models created using this scheme are examined with regard to their suitability for option pricing
  •  
23.
  • Lundengård, Karl, 1987-, et al. (författare)
  • Multi-Peaked Analytically Extended Function Representing Electrostatic Discharge (ESD) Currents
  • 2017
  • Ingår i: AIP Conference Proceedings, Volume 1798. - : American Institute of Physics (AIP). - 9780735414648 ; , s. 020093-1-020093-10
  • Konferensbidrag (refereegranskat)abstract
    • A multi-peaked analytically extended function (AEF), previously applied by the authors to modeling of lightning dischargecurrents, is used in this paper for representation of the electrostatic discharge (ESD) currents. In order to estimate itsnon-linear parameters, the Marquardt least-squares method (MLSM) is used. ESD currents’ modelling is illustrated through anessential example corresponding to approximation of the IEC Standard 61000-4-2 waveshape.
  •  
24.
  • Lundengård, Karl, 1987-, et al. (författare)
  • Novel Approach to Modelling of Lightning Current Derivative
  • 2017
  • Ingår i: Facta Universitatis Series. - Nis, Serbia. - 0353-3670 .- 2217-5997. ; 30:2, s. 245-256
  • Tidskriftsartikel (refereegranskat)abstract
    • A new approach to mathematical modelling of lightning current derivative is proposed in this paper. It builds on the methodology, previously developed by the authors, for representing lightning currents and electrostatic discharge (ESD) currents waveshapes. It considers usage of a multi-peaked form of the analytically extended function (AEF) for approximation of current derivative waveshapes. The AEF function parameters are estimated using the Marquardt least-squares method (MLSM) and the framework for fitting the multi-peaked AEF to a waveshape with an arbitrary number of peaks is briefly described. This procedure is validated performing a few numerical experiments, including fitting the AEF to single- and multi-peaked waveshapes corresponding to measured current derivatives.
  •  
25.
  • Lundengård, Karl, 1987-, et al. (författare)
  • On Some Properties of the Multi-Peaked Analytically Extended Function for Approximation of Lightning Discharge Currents
  • 2016
  • Ingår i: Engineering Mathematics I. - Heidelberg : Springer. - 9783319420820 - 9783319420813 ; , s. 151-172
  • Bokkapitel (refereegranskat)abstract
    • According to experimental results for lightning discharge currents, they are classified in the IEC 62305 Standard into waveshapes representing the first positive, first and subsequent negative strokes, and long-strokes. These waveshapes, especially shot-term pulses, are approximated with a few mathematical functions in literature, in order to be used in lightning discharge models for calculations of electromagnetic field and lightning induced effects. An analytically extended function (AEF) is presented in this paper and used for lightning currents modeling. The basic properties of this function with a finite number of peaks are examined. A general framework for estimating the parameters of the AEF using the Marquardt least-squares method (MLSM) for a waveform with an arbitrary (finite) number of peaks as well as for the given charge transfer and specific energy is described. This framework is used to find parameters for some common single-peak wave-forms and some advantages and disadvantages of the approach are also discussed.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-25 av 41

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy