Sökning: "beam characteristics"

Visar resultat 1 - 5 av 146 avhandlingar innehållade orden beam characteristics.

  1. 1. Absorbed Dose Determination and Characteristics of Degraded Electron Beams: Application to Intraoperative Radiation Therapy

    Författare :Peter Björk; Internmedicin - epidemiologi; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Clinical physics; radiology; tomography; medical instrumentation; Klinisk fysiologi; radiologi; tomografi; medicinsk instrumentering; absorbed dose distribution; output factor; stopping-power ratio; beam characteristics; Monte Carlo calculation; electron beam dosimetry; applicator system; radiation therapy; linear accelerator; intraoperative radiotherapy;

    Sammanfattning : The aim of this work was to quantify limitations of and uncertainties in commonly used dosimetric techniques for relative absorbed dose determination in degraded electron beams, such as those encountered in intraoperative radiation therapy (IORT) and small-electron-field radiotherapy. Three different detector types were investigated with regard to measurements of output factors and relative absorbed dose distributions: (1) a parallel-plate ionization chamber, (2) a p-type silicon diode detector and (3) a diamond detector. LÄS MER

  3. 2. Defects and Surfaces and their Impact on Fatigue Behaviour of Powder Bed Fused Ti-6Al-4V : Characteristics and Modelling

    Författare :Viktor Sandell; Marta-Lena Antti; Pia Åkerfeldt; Thomas Hansson; Stefano Beretta; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Defects; Additive Manufacturing; Ti-6Al-4V; Probabilistic Modelling; Fatigue; Extreme Value Statistics; Materialteknik; Engineering Materials;

    Sammanfattning : Additive manufacturing (AM), of metals is gaining popularity as an alternative to conventional manufacturing techniques such as casting and forging. Metal-AM allows for the production of complex part geometries with reduced material waste and shorter lead times. LÄS MER

  4. 3. Beam-to-Beam Contact and Its Application to Micromechanical Simulation of Fiber Networks

    Författare :Hamid Reza Motamedian; Artem Kulachenko; Umberto Perego; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; fiber network; beam-to-beam contact; rotational contact; non-consistent; simulation; finite element; multiscale; microscale; micromechanics; paper; refining; beating; fine; hygroexpansion; shrinkage; drying; Hållfasthetslära; Solid Mechanics;

    Sammanfattning : This doctoral thesis covers the topic of modeling the three-dimensional fiber net- works with the finite element method. It contains the part addressing the numerical aspects of the modeling, namely, the contact formulation and application of the developed methods to the fundamental questions such as the effect of randomness in fiber properties and effect of fines and hygroexpansion. LÄS MER

  5. 4. Ion beam etching of InP based materials

    Författare :Carl-Fredrik Carlström; KTH; []
    Nyckelord :InP; dry etching; ion beam etching; RIBE; CAIBE; hydrocarbon chemistry; trimethylamine; As P exchange reaction; morphology; low damage; AFM; SCM; annealing;

    Sammanfattning : Dry etching is an important technique for pattern transferin fabrication of most opto-electronic devices, since it canprovide good control of both structure size and shape even on asub-micron scale. Unfortunately, this process step may causedamage to the material which is detrimental to deviceperformance. LÄS MER

  7. 5. Location-aided Beam Alignment and Handover in Millimeter-wave Networks

    Författare :Sara Khosravi; Marina Petrova; Jens Zander; Sofie Pollin; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Millimeter wave networks; beam alignment; Handover; Reinforcement learning; Millimetervågnätverk; strålinriktning; överlämning; förstärkningsinlärning;

    Sammanfattning : Ever-increasing data rate demands in mobile networks and the spectrum scarcity at the microwave bands have resulted in the exploration of millimeter-wave (mmWave) frequencies for the next generation of wireless networks. While mmWave frequencies offer large bandwidth, communication at these frequencies is not straightforward due to the challenging propagation characteristics. LÄS MER