The Experts below are selected from a list of 157503 Experts worldwide ranked by ideXlab platform
Spiliotis Konstantinos - One of the best experts on this subject based on the ideXlab platform.
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Electrical System Architectures for Building-Integrated PV. Multi-scale, Multi-Domain Modeling and Simulation
2020Co-Authors: Spiliotis KonstantinosAbstract:As we are shifting to more sustainable, cleaner and distributed energy systems, building-integrated photovoltaics may be one of the key technologies to help us achieve that. Particularly high rise buildings, may use this technology to cover their energy needs or be a positive net prosumer. In the field of building energy simulations, the Modeling and simulation of buildings is mostly focused on the building-physical and thermal aspects, even when electrical generation and storage are incorporated. This doctoral thesis is focused on the electrical system architecture aspects related to building integrated PV systems. The thesis addresses a number of aspects related to the electrical system that need to be tackled in order to enable an efficient integration. The thesis contributes to a broader Modeling and simulation framework for building-integrated PV. The models of this framework are developed in Modelica, a multi-physics, object-oriented Modeling language that can accurately reflect the multi-Domain nature of integrated PV. The models and simulations described in the manuscript can be used by a number of stakeholders that are involved in the design of such systems, for example, electrical and building engineers. The models and simulations can also be used by power electronic designers interested in the converters performance under certain operating conditions, such as when integrated into an integrated-PV frame. Another contribution of this thesis is the provision of guidelines regarding the integrated PV systems electrical design. Such design guidelines include the following considerations: integration of power converter into integrated PV modules, nanogrid distribution (DC vs AC and voltage level), sizing of electrical components (converters, inverters, etc.) and finally, sizing of battery system.status: accepte
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Electrical System Architectures for Building-Integrated PV. Multi-scale, Multi-Domain Modeling and Simulation
2020Co-Authors: Spiliotis KonstantinosAbstract:As we are shifting to more sustainable, cleaner and distributed energy systems, building-integrated photovoltaics may be one of the key technologies to help us achieve that. Particularly high rise buildings, may use this technology to cover their energy needs or be a positive net prosumer. In the field of building energy simulations, the Modeling and simulation of buildings is mostly focused on the building-physical and thermal aspects, even when electrical generation and storage are incorporated. This doctoral thesis is focused on the electrical system architecture aspects related to building integrated PV systems. The thesis addresses a number of aspects related to the electrical system that need to be tackled in order to enable an efficient integration. The thesis contributes to a broader Modeling and simulation framework for building-integrated PV. The models of this framework are developed in Modelica, a multi-physics, object-oriented Modeling language that can accurately reflect the multi-Domain nature of integrated PV. The models and simulations described in the manuscript can be used by a number of stakeholders that are involved in the design of such systems, for example, electrical and building engineers. The models and simulations can also be used by power electronic designers interested in the converters performance under certain operating conditions, such as when integrated into an integrated-PV frame. Another contribution of this thesis is the provision of guidelines regarding the integrated PV systems electrical design. Such design guidelines include the following considerations: integration of power converter into integrated PV modules, nanogrid distribution (DC vs AC and voltage level), sizing of electrical components (converters, inverters, etc.) and finally, sizing of battery system.status: publishe
George A Lesieutre - One of the best experts on this subject based on the ideXlab platform.
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time Domain Modeling of damping using anelastic displacement fields and fractional calculus
International Journal of Solids and Structures, 1999Co-Authors: Mikael Enelund, George A LesieutreAbstract:Abstract A fractional derivative model of linear viscoelasticity based on the decomposition of the displacement field into an anelastic part and elastic part is developed. The evolution equation for the anelastic part is then a differential equation of fractional order in time. By using a fractional order evolution equation for the anelastic strain the present model becomes very flexible for describing the weak frequency dependence of damping characteristics. To illustrate the Modeling capability, the model parameters are fit to available frequency Domain data for a high damping polymer. By studying the relaxation modulus and the relaxation spectrum the material parameters of the present viscoelastic model are given physical meaning. The use of this viscoelastic model in structural Modeling is discussed and the corresponding finite element equations are outlined, including the treatment of boundary conditions. The anelastic displacement field is mathematically coupled to the total displacement field through a convolution integral with a kernel of Mittag–Leffler function type. Finally a time step algorithm for solving the finite element equations are developed and some numerical examples are presented.
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time Domain Modeling of linear viscoelasticity using anelastic displacement fields
Journal of Vibration and Acoustics, 1995Co-Authors: George A Lesieutre, Emanuele BianchiniAbstract:A time Domain model of linear viscoelasticity is developed based on a decomposition of the total displacement field into two parts: one elastic, the other anelastic. The anelastic displacement field is used to describe that part of the strain that is not instantaneously proportional to stress. General coupled constitutive equations for (1) the total and (2) the anelastic stresses are developed in terms of the total and anelastic strains, and specialized to the case of isotropic materials. A key feature of the model is the absence of explicit time dependence in the constitutive equations. Apparent time-dependent behavior is described instead by differential equations that govern (1) the motion of mass particles and (2) the relaxation of the anelastic displacement field. These coupled governing equations are developed in a parallel fashion, involving the divergence of appropriate stress tensors. Boundary conditions are also treated: the anelastic displacement field is effectively an internal field, as it is driven exclusively through coupling to the total displacement, and cannot be directly affected by applied loads. In order to illustrate the use of the method, model parameters for a commonly-used high damping polymer are developed from available complex modulus data.
Tomasz P. Zielinski - One of the best experts on this subject based on the ideXlab platform.
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Frequency-Domain Modeling of OFDM Transmission with Insufficient Cyclic Prefix Using Toeplitz Matrices
2018 IEEE 88th Vehicular Technology Conference (VTC-Fall), 2018Co-Authors: Grzegorz Cisek, Tomasz P. ZielinskiAbstract:A novel mathematical framework is proposed to model Intersymbol Interference (ISI) phenomenon in wireless communication systems based on Orthogonal Frequency Division Multiplexing (OFDM) with or without cyclic prefix. The framework is based on a new formula to calculate the Fast Fourier Transform (FFT) of a triangular Toeplitz matrix, which is derived and proven in this paper. It is shown that distortion inducted by the ISI from a given subcarrier is the most significant for the closest subcarriers and the contribution decays as the distance between subcarriers grows. According to numerical experiments, knowledge of ISI coefficients concentrated around the diagonal of Channel Frequency Response (CFR) matrix improves the receiver's error floor significantly. The potential use of the framework for real-time frequency Domain channel simulation was also investigated and demonstrated to be more efficient than conventional time Domain Tapped Delay Line (TDL) model when a number of simulated users is high.
J A Kong - One of the best experts on this subject based on the ideXlab platform.
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time Domain Modeling of impedance boundary condition
IEEE Transactions on Microwave Theory and Techniques, 1992Co-Authors: C F Lee, R T Shin, J A KongAbstract:A methodology developed to handle dispersive materials in the time Domain is extended to model the dispersive characteristics of the impedance boundary condition used for a thin-layer coating over perfect conductors. The impedance boundary condition is first approximated as a rational function of frequency. This rational function is then transformed to a time-Domain equation, resulting in a partial differential equation in space and time. Discretization of the time-Domain model to efficiently handle the thin-layer coating is presented in the context of the finite-difference time-Domain (FD-TD) technique. The methodology is verified by solving a one-dimensional problem using the FD-TD technique and comparing with the analytical results. >
Omar M Ramahi - One of the best experts on this subject based on the ideXlab platform.
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Modeling graphene in the finite difference time Domain method using a surface boundary condition
IEEE Transactions on Antennas and Propagation, 2013Co-Authors: Vahid Nayyeri, Mohammad Soleimani, Omar M RamahiAbstract:An effective approach for finite-difference time-Domain Modeling of graphene as a conducting sheet is proposed. First, we present a new technique for implementing a conducting surface boundary condition in the FDTD method; then, the dispersive surface conductivity of graphene is imposed. Numerical examples are presented to show the stability, accuracy, applicability, and advantages of the proposed approach. Validation is achieved by comparison with existing analytic methods.
