A5030000439- Nuclear Materials and Properties
- Radioactive element chemistry and processing
- Fusion materials and technologies
- Nuclear materials and radiation effects
- Semiconductor Quantum Structures and Devices
- Nuclear reactor physics and engineering
- Semiconductor materials and devices
- Music Technology and Sound Studies
- GaN-based semiconductor devices and materials
- Hydrogen embrittlement and corrosion behaviors in metals
- Quantum and electron transport phenomena
- Advanced Chemical Physics Studies
- Ion-surface interactions and analysis
- Microstructure and Mechanical Properties of Steels
- Surface and Thin Film Phenomena
- Electronic and Structural Properties of Oxides
- Digital Filter Design and Implementation
- Metal and Thin Film Mechanics
- Advanced Adaptive Filtering Techniques
- Advanced Materials Characterization Techniques
- Welding Techniques and Residual Stresses
- Nuclear Physics and Applications
- Semiconductor materials and interfaces
- Metal Alloys Wear and Properties
- Lignin and Wood Chemistry
VTT Technical Research Centre of Finland
2010-2024
Aalto University
2010-2023
The Ohio State University
2022
Idaho National Laboratory
2022
Studsvik (Sweden)
2020-2021
Belgian Nuclear Research Centre
2014-2020
University of Wisconsin–Madison
2013-2019
Tampere University
2007-2012
University of Turku
2006-2010
Helsinki Institute of Physics
2008-2009
A fundamental question concerning the chemical state of uranium in binary oxides UO2, U4O9, U3O7, U3O8, and UO3 is addressed. By utilizing high energy resolution fluorescence detection X-ray absorption near edge spectroscopy (HERFD-XANES) at M4 edge, a novel technique tender region, we obtain distribution formal oxidation states mixed-valence U3O8. Moreover, clearly identify pivot from U(IV)–U(V) to U(V)–U(VI) charge compensation, corresponding with transition fluorite-type structure (U3O7)...
Abstract Experimental work aimed at understanding the role of dislocation loops in limiting phonon mediated thermal transport ceramics is presented. Faulted loops, having diameters a few nanometers, were introduced by irradiating polycrystalline cerium dioxide sample with 1.6 MeV protons 700°C. XRD analysis indicated that irradiated samples retained their crystalline structure and exhibit very little lattice expansion suggesting low concentration point defects. Further microstructure...
Sputtering of gold nanoparticles and nanometer-thin films under 25 keV gallium-ion bombardment is shown, using molecular-dynamics simulations, to be significantly enhanced compared bulk. The highest yield, about three times that bulk gold, occurs for particles 8 nm in diameter. For thin films, the maximal yield obtained roughly 3 thick films. A model based on work Sigmund presented explain size-dependence.
The nanostructure and phase evolution in low-temperature oxidized (40–250 °C), fine UO2 powders (<200 nm) have been investigated by X-ray diffraction (XRD) high-resolution transmission electron microscopy (HR-TEM). extent of oxidation was also measured via situ thermogravimetric analysis. found to proceed differently as compared coarse-grained UO2. No discrete surface oxide layer observed no U3O8 formed, despite the high degree (up O/U = 2.45). Instead, nanosized (5–15 amorphous nuclei...
Virtual analog modeling is needed when simulating classic circuitry by DSP, for example emulating sound synthesis and reproduction systems. In this paper we show how wave digital filters (WDFs) can be applied to efficient real-time simulation of vacuum-tube amplifier stages, typical in professional guitar amplifiers, which pose nonlinear behavior desired distortion effects
Polycrystalline U3O7 powder was synthesized by oxidation of UO2 under controlled conditions using in situ thermal analysis, and heat treatment a tubular furnace. The O/U ratio the phase measured as 2.34 ± 0.01. crystal structure assessed from X-ray diffraction (XRD) selected-area electron (SAED) data. Similar to U4O9-ε (more precisely U64O143), exhibits long-range ordered structure, which is closely related fluorite-type arrangement UO2. Cations remain arranged identical that fluorite excess...
Electric circuits containing vacuum tubes form an integral part of various audio equipment, such as guitar amplifiers, certain equalizers, microphone preamplifiers, and dynamic range compressors. Although most signal processing operations are straightforward to implement with modern computers, real-time digital simulation poses a significant challenge due the nonlinearities tube circuits. Most current vacuum-tube emulators model unidirectional path circuit using linear filters nonlinear...
We have studied beryllium defects in GaAs and GaAsN from first principles, concentrating on the nitrogen effect defect formation alloying properties. Due to small size of both species complexes clusters take an important role. In particular, we consider role (Be-N) split interstitials near substitutional beryllium. These are found be responsible for charge-carrier compensation Be-doped GaAsN. Also, any tied is unable contribute conventional alloy also briefly comment implications diffusion.