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Sökning: WFRF:(Anderson Johan 1973)

  • Resultat 1-10 av 76
  • [1]234567...8Nästa
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1.
  • Andrae, Anders, 1973, et al. (författare)
  • Uncertainty estimation by Monte Carlo Simulation applied to Life Cycle Inventory of Cordless Phones and Microscale Metallization Processes
  • 2004
  • Ingår i: IEEE Transactions on Electronics Packaging Manufacturing. ; 27:4, s. 233-245
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper focuses on uncertainty analysis, that is, how the input data uncertainty affects the output data uncertainty in small but realistic product systems is modeled. The motivation for the study is to apply the Monte Carlo simulation for uncertainty estimation in life cycle inventory and environmental assessment of microelectronics applications. This paper addresses the question whether there is an environmental advantage of using DECT phones instead of GSM phones in offices. The paper also addresses the environmental compatibility of Electrochemical Pattern Replication (ECPR) compared to classical photolithography based microscale metallization (CL) for pattern transfer. Both environmental assessments in this paper consider electricity consumption and CO2 emissions. The projects undertaken are two comparative studies of DECT phone/GSM phone and ECPR/CL respectively. The research method used was probabilistic uncertainty modelling with a limited number of inventory parameters used in the MATLAB tool. For the DECT/GSM study the results reflects the longer DECT technical life which is an environmental advantage. For the Electrochemical Pattern Replication (ECPR)/classical photolithography based microscale metallization (CL) study the results reflects the fewer number of process steps and the lower electricity consumption needed by the ECPR to reach the functional unit. The difference in results is large enough to be able to draw conclusions, as the processes with the highest electricity consumption within the system boundaries have been determined. Based on earlier work a straightforward method to include uncertainty for input life cycle inventory data is used to quantify the influence of realistic errors for input data in two microelectronic applications. The conclusion is that the ECPR technology is more electricity efficient than CL in producing one layer of copper on a silicon wafer having a diameter of 20.32 cm. The conclusion is that the longer technical life of a cordless DECT phone is reflected in an electricity/CO2 comparison with a GSM phone, if use in an office is considered. Reasonable uncertainty intervals used for the input life cycle inventory data for the studied DECT/GSM and ECPR/CL system does affect the outcome of calculation of emission of CO2 but not to the degree that conclusions are not valid.Different uncertainty intervals and probability distributions could apply for different types of data and the interrelated input data dependence should be investigated. Today there exist very few life cycle inventory (LCI) data with the range of uncertainty for input and output elements. It must be emphasized that the upcoming LCI databases should have standard deviation characterized LCI data just as the Swiss ecoinvent LCI database.More inventory parameters and probability distributions characteristic for microsystems could be included and error analysis should be applied to future life inventory methodology, especially for future packaging concepts such as System-In-a-Package and System-On-a-Chip comparisons.
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2.
  • Anderson, Johan, 1973-, et al. (författare)
  • Assessment of Self-Heating in Wood Pellets by FE Modelling
  • 2017
  • Konferensbidrag (refereegranskat)abstract
    • The self-heating process in a laboratory scale experiment has been modelled using the Comsol Multiphysics software. In the simulations the gas flow and air movement in the volume and heat diffusion in the bulk were taken into account however only one reaction in the pellets bulk is considered. The input data is found from measurements of the reaction chemistry and the heat transfer properties. It is found that all relevant physics is needed in order to obtain reasonable predictions in particular the heat transfer between the bulk and the gas is important but also condensation and evaporation of moisture.   
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4.
  • Mo, Zhimin, et al. (författare)
  • Integrating nano carbon tubes with microchannel cooler
  • 2004
  • Ingår i: Proceedings of The 6th IEEE CPMT International Symposium on High Density Packaging and Component Failure Anlaysis (HDP'4). ; 04:EX905, s. pp 373-376
  • Konferensbidrag (refereegranskat)
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5.
  • Anderson, Johan, 1973, et al. (författare)
  • A comparison of drift wave stability in stellarator and tokamak geometry
  • 2002
  • Ingår i: Physics of Plasmas. ; 9:5, s. 1629-
  • Tidskriftsartikel (refereegranskat)abstract
    • The influence of plasma geometry on the linear stability of electrostatic ion-temperature-gradient driven drift modes (ITG modes) is investigated. An advanced fluid model is used for the ions together with Boltzmann distributed electrons. The derived eigenvalue equation is solved numerically. A comparison is made between an H – 1NF [Fusion Technol. 17, 123 (1990)] like stellarator equilibrium, a numerical tokamak equilibrium and the analytical s - alpha equilibrium. The numerical and the analytical tokamak are found to be in good agreement in the low inverse aspect ratio limit. The growth rates of the tokamak and stellarator are comparable whereas the modulus of the real frequency is substantially larger in the stellarator. The threshold in Ln/LT for the stellarator is found to be somewhat larger. In addition, a stronger stabilization of the ITG mode growth is found for large L n / R in the stellarator case.
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6.
  • Anderson, Johan, 1973, et al. (författare)
  • A fractional Fokker-Planck model for anomalous diffusion
  • 2014
  • Ingår i: Physics of Plasmas. - 1089-7674 .- 1070-664X. ; 21:12, s. aricle no: 122109-
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we present a study of anomalous diffusion using a Fokker-Planck description withfractional velocity derivatives. The distribution functions are found using numerical means forvarying degree of fractionality of the stable Lévy distribution. The statistical properties of thedistribution functions are assessed by a generalized normalized expectation measure and entropyin terms of Tsallis statistical mechanics. We find that the ratio of the generalized entropy andexpectation is increasing with decreasing fractionality towards the well known so-called sub-diffusivedomain, indicating a self-organising behavior.
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7.
  • Anderson, Johan, 1973, et al. (författare)
  • Anomalous diffusion by the fractional Fokker-Planck equation and Levy stable processes
  • 2018
  • Ingår i: Fractional Dynamics and Anomalous Transport in Plasma Science. ; , s. 1-16
  • Bokkapitel (övrigt vetenskapligt)abstract
    • The work presented here is a review of current developments in modelling anomalous diffusion using a Fokker-Planck description with fractional velocity derivatives and Langevin dynamics where L´evy fluctuations are introduced to model the effect of non-local transport due to fractional diffusion in velocity space. Distribution functions are found using numerical means for varying degree of fractionality of the stable L´evy distribution as solutions to the Fokker-Planck equation and is compared to results from Langevin simulations. The statistical properties of the distribution functions are assessed by a generalized normalized expectation measure and entropy in terms of Tsallis statistical mechanics.
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8.
  • Anderson, Johan, 1973, et al. (författare)
  • Derivation and quantitative analysis of the differential self-interrogation Feynman-alpha method
  • 2012
  • Ingår i: European Physical Journal Plus. - 2190-5444. ; 127:2, s. 1-6
  • Tidskriftsartikel (refereegranskat)abstract
    • A stochastic theory for a branching process in a neutron population with two energy levels is used to assess the applicability of the differential self-interrogation Feynman-alpha method by numerically estimated reaction intensities from Monte Carlo simulations. More specifically, the variance to mean or Feynman-alpha formula is applied to investigate the appearing exponentials using the numerically obtained reaction intensities.
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9.
  • Anderson, Johan, 1973, et al. (författare)
  • Derivation and quantitative analysis of the differential self-interrogation Feynman-alpha method
  • 2011
  • Ingår i: Proceedings 52nd INMM Conference 17-21 July, Palm Desert, CA, USA (2011).
  • Konferensbidrag (refereegranskat)abstract
    • A stochastic theory for a branching process in a neutronpopulation with two energy levels is used to assess theapplicability of the differential self-interrogation Feynman-alpha method by numerically estimated reaction intensities from Monte Carlo simulations. More specifically, the variance to mean or Feynman-alpha formula is applied to investigate the appearing exponentials using the numerically obtained reaction intensities.
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10.
  • Anderson, Johan, 1973 (författare)
  • Drift Waves in General Toroidal Equilibria
  • 2002
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • One of the main concerns in fusion research is to understand the anomalously high transport in magnetically confined plasmas. In recent years, substantial progress in the understanding of transport in terms of drift waves in fusion plasmas has been achieved. It is at present an important issue to investigate the stability of drift waves in realistic toroidal geometries. Among the drift wave candidates for explaining the anomalous transport are the toroidal ITG-modes in the core and the resistive ITG-modes and the resistive ballooning modes in the edge. The effects of plasma shaping on magneto-hydrodynamic (MHD) modes have been thoroughly studied. However, the effects of plasma shaping on the drift waves are not well known. Empirically it is found that the overall effects of elongation on the energy confinement time is favorable with ~ kappa^0.5. In this thesis, the ITG-mode and the resistive edge mode stability in a non-circular tokamak geometry are studied. In particular, the effects of elongation and Shafranov shift are studied. In the core plasma a destabilization of the ITG-mode with increasing elongation is found whereas a stabilization is found in the edge region (or rather for peaked density profiles). Moreover, a comparison of the ITG-mode growth rates in the tokamak and stellarator equilibria is made. The growth rates for the tokamak and stellarator cases are comparable whereas the modulus of the real frequency is substantially larger in the stellarator. In addition, a stronger stabilization of the ITG mode growth is found for large Ln/R in the stellarator case. Finally, an analytical estimation of zonal flow generation including effects of elongation is presented. The results suggest that a strong excitation of zonal flows is obtained for peaked density profiles and close to marginal stability. However, in order draw more detailed conclusions of the effects of elongation on the global confinement time, a more extensive study using predictive transport simulations, which treats the edge and core transport processes self-consistently will be needed.
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  • Resultat 1-10 av 76
  • [1]234567...8Nästa

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