Sökning: "first order perturbation"

Visar resultat 1 - 5 av 13 uppsatser innehållade orden first order perturbation.

1. 1. Time-resolved x-ray diffraction study of longitudinal optical phonons in zincblende semiconductors

   Master-uppsats, Lunds universitet/Atomfysik; Lunds universitet/Fysiska institutionen

   Författare :Lassi Linnala; [2022]
   Nyckelord :femtosecond THz radiation; ultrafast x-ray diffraction; pump-probe; longitudinal optical phonons; zincblende semiconductors; anharmonic decay; density functional perturbation theory; Physics and Astronomy;

   Sammanfattning : Anharmonic decay of longitudinal optical (LO) phonons in zincblende semiconductors is not at present well characterized due to the polar and many-body nature of the problem. Femtosecond THz radiation offers a novel route to this study, as the interaction of this radiation is directly with the phonon lattice and these THz excited phonons do not have enough energy to excite electrons over the band gap. LÄS MER

3. 2. Deep Reinforcement Learning for Temperature Control in Buildings and Adversarial Attacks

   Master-uppsats, KTH/Skolan för elektroteknik och datavetenskap (EECS)

   Författare :Kevin Ammouri; [2021]
   Nyckelord :Deep Reinforcement Learning; Adversarial Attacks; Optimal Attacks; Building Control; Optimal Control; Energy Efficiency; Djup förstärkande inlärning; Adversarial Attacker; Optimala Attacker; Byggnadskontroll; Optimal Kontroll; Energieffektivitet;

   Sammanfattning : Heating, Ventilation and Air Conditioning (HVAC) systems in buildings are energy consuming and traditional methods used for building control results in energy losses. The methods cannot account for non-linear dependencies in the thermal behaviour. LÄS MER

4. 3. Adversarial Example Transferabilty to Quantized Models

   Master-uppsats, Linköpings universitet/Medie- och Informationsteknik; Linköpings universitet/Tekniska fakulteten

   Författare :Ludvig Kratzert; [2021]
   Nyckelord :convolutional; neural; network; quantization; adversarial; perturbation; compression; machine; learning; security;

   Sammanfattning : Deep learning has proven to be a major leap in machine learning, allowing completely new problems to be solved. While flexible and powerful, neural networks have the disadvantage of being large and demanding high performance from the devices on which they are run. LÄS MER

5. 4. Microscopic and Macroscopic Samples of Atoms in Superposition States Studied by Attosecond Pulses

   Magister-uppsats, Lunds universitet/Matematisk fysik; Lunds universitet/Fysiska institutionen

   Författare :Axel Stenquist; [2021]
   Nyckelord :Mathematical physics; Theoretical physics; Atomic physics; Attosecond physics; Ultra-fast physics; Numerical simulations; Microscopic; Mesoscopic; Macroscopic; Superposition; Light matter interaction; Quantum mechanics; Electromagnetism; Semiclassical; Attosecond transient absorption spectroscopy; ATAS; Förster resonance; FRET; Two-atom model; Inter-atomic interaction; Dipole-dipole interaction; Many-atom model; Collective coherent effects; Time-dependent configuration-interaction singles; TDCIS; Physics and Astronomy;

   Sammanfattning : In the present thesis, the interaction between atoms in superposition states and attosecond pulses is studied from the microscopic to the macroscopic regime. Using a semi-classical framework, three different models have been explored in order to investigate attosecond light--matter interaction processes. LÄS MER

7. 5. Detection of in-plane orbital manoeuvres from a catalogue of geostationary objects

   Master-uppsats, Luleå tekniska universitet/Rymdteknik

   Författare :Phuong Linh Ngo; [2020]
   Nyckelord :manoeuvre detection; geostationary orbit; perturbations; filters; Two-line elements; station keeping;

   Sammanfattning : The number of man-made space objects is dramatically growing nowadays. The continuous monitoring and studying of these objects are necessary to keep their number under control and ensure safe space operations. LÄS MER