Essays about: "Approximation"

Showing result 11 - 15 of 723 essays containing the word Approximation.

  1. 11. Wavelength-dependent limb darkeningin the analysis oftransit spectroscopy of exoplanets

    University essay from Uppsala universitet/Institutionen för fysik och astronomi

    Author : Alberto García Ribas; [2023]
    Keywords : ;

    Abstract : Limb darkening, an optical effect characteristic of stars, where the limb (edge) seemsto be darker than the centre of the stellar body; plays an important role in our under-standing of exoplanetary transits, as it is fundamental for developing light curve modelsthat can help to undercover extrasolar companions. To recover atmospheric featuresfrom exoplanets, a principal component analysis method is typically used. READ MORE

  3. 12. A Conjugate Residual Solver with Kernel Fusion for massive MIMO Detection

    University essay from Högskolan i Halmstad/Centrum för forskning om tillämpade intelligenta system (CAISR)

    Author : Ioannis Broumas; [2023]
    Keywords : MIMO; massive MIMO; GPU; CUDA; Software Defined Radio; SDR; MMSE; ZF; zero-forcing; parallel detection; iterative methods; conjugate residual; parallel computing; kernel fusion;

    Abstract : This thesis presents a comparison of a GPU implementation of the Conjugate Residual method as a sequence of generic library kernels against implementations ofthe method with custom kernels to expose the performance gains of a keyoptimization strategy, kernel fusion, for memory-bound operations which is to makeefficient reuse of the processed data. For massive MIMO the iterative solver is to be employed at the linear detection stageto overcome the computational bottleneck of the matrix inversion required in theequalization process, which is 𝒪(𝑛3) for direct solvers. READ MORE

  4. 13. Ray-Tracing Modeling of Grating Lobe Level Reduction by Using a Dielectric Dome Antenna

    University essay from KTH/Skolan för elektroteknik och datavetenskap (EECS)

    Author : Lukas Jonasson; [2023]
    Keywords : Array antenna; Dielectric dome; Ray-Tracing; Grating lobe; Particle Swarm optimization; Gruppantenn; Dielektrisk kupol; Strålspårning; Gallerlob; Particle Swarm optimering;

    Abstract : With the newly deployed fifth-generation telecommunications system and upcoming sixth-generation, high-gain antennas with hemispherical scanning capabilities are of high interest. Phased array antennas allow for fast scanning capabilities with electronic beam-steering. READ MORE

  5. 14. Numerical Simulations of Resonant Tunnelling Diodes

    University essay from KTH/Skolan för teknikvetenskap (SCI)

    Author : Love Sundström; Alexander Holmström Janeld; [2023]
    Keywords : Quantum mechanics; numerical methods; resonant tunnelling diode;

    Abstract : In this thesis, four different numerical techniques are implemented for the purpose of simulating resonant tunnelling diodes (RTDs). The chosen methods were: piecewise constant transfer matrix (TMM-C), piecewise linear transfer matrix (TMM-L), quantum transmitting boundary method (QTBM), and the Crank-Nicolson method (CN). READ MORE

  6. 15. First principles investigation of the thermal conductivity of Zr, ZrC, and ZrN

    University essay from KTH/Fysik

    Author : Daniel Karlsson; [2023]
    Keywords : Electron-phonon interaction; Density functional theory; Boltzmann transport equation; first-principles; thermal conductivity; electrical resistivity; Abinit; Phono3py; Elektron-fononväxelverkan; täthetsfunktionalteori; Boltzmanns transportekvation; värmeledningsförmåga; elektrisk resistivitet; Abinit; Phono3py;

    Abstract : The thermal conductivity and electrical resistivity of Zr, ZrC, and ZrN were calculated using first-principles density functional theory (DFT) and the Boltzmann transport equation. The electron-phonon scattering was modeled via the self-energy relaxation time approximation (SERTA), and the phonon-phonon scattering via the analogous single-mode relaxation time approximation (SMRTA). READ MORE