Sökning: "threshold dynamics"

Visar resultat 21 - 25 av 119 avhandlingar innehållade orden threshold dynamics.

1. 21. Time-Resolved Diffraction Studies of Structural Dynamics in Solids

   Författare :Xiaocui Wang; Atomfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Time-resolved X-ray diffraction; phonons; photo-acoustic transducer; electron diffusion; pressure wave; non-thermal melting; Fysicumarkivet A:2019:Wang;

   Sammanfattning : Studies of the structural dynamics of solids can improve our understanding of atomic motion in materials, and may thus help in the manufacture of new devices or the development of materials with novel structures and properties. Ultrashort laser pulses, a few tens of femtoseconds long, can deliver high energies (mJ–kJ). LÄS MER

3. 22. Dynamics of some vibro-impacting systems with amplitude constraints

   Författare :Jan-Olov Aidanpää; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hållfasthetslära; Solid Mechanics; Datorstödd maskinkonstruktion; Computer Aided Design;

   Sammanfattning : This thesis concerns the dynamics of some vibro-impacting systems with fixed or moving amplitude constraints. It is based on and includes five papers, marked A to E. Simple models of three different vibro-impacting systems with applications in the fields of impact hammers, granular flow and disk brakes in vehicles are analysed. LÄS MER

4. 23. Dynamics and Extreme Value Problems for Moored Floating Platforms

   Författare :Yungang Liu; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; quasi-static; frequency-domain; extreme value; convolution; floating platform; low-frequency; time-domain; mooring cable; wave-frequency;

   Sammanfattning : This research deals with the dynamic response analyses and extreme value problems of moored floating platforms. It can be divided into three major subjects: first, the analysis of single cables and cable induced mooring damping; second, the dynamic analysis of the moored platforms, with special emphasis on the damping mechanisms and generation of the low-frequency excitation force time series; and third, the extreme wave-frequency responses and the combination of the low-frequency and wave-frequency extreme responses. LÄS MER

5. 24. Quantum nuclear dynamics in  x-ray scattering and lasing

   Författare :Yasen Velkov; Faris Gel'mukhanov; Reinhold Fink; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Theoretical chemistry; Teoretisk kemi;

   Sammanfattning : This thesis presents a theoretical study of the role of nuclear degrees of freedom in the x-ray absorption, x-ray resonant scattering  and some aspects of the interaction of matter with strong laser fields. Most numerical simulations are performed with a time-dependent wave-packet program that have proved its robustness  in previous investigations. LÄS MER

7. 25. Soft X-ray Scattering Dynamics Close to Core Ionization Thresholds in Atoms and Molecules

   Författare :Johan Söderström; Jan-Erik Rubensson; Lorenzo Avaldi; Uppsala universitet; []
   Nyckelord :Physics; Soft X-ray emission; Resonant inelastic X-ray scattering; Double excitations; Helium; X-ray-emission-threshold-electron coincidence; Fysik;

   Sammanfattning : In this Thesis studies of highly excited states in gas-phase atoms and molecules (He, Ne, N2, O2, N2O and CO2) using a variety of synchrotron-radiation based techniques are presented. The three techniques used most frequently are X-ray-emission-threshold-electron coincidence (XETECO), X-ray emission spectroscopy (XES) and X-ray photoelectron spectroscopy (XPS) and they are all given a brief introduction. LÄS MER