| 1. |
- Hargreaves, D., et al.
(författare)
-
- 2004
-
Rapport (refereegranskat)
|
|
| 2. |
- Özeren, Hüsamettin Deniz
(författare)
-
Prediction of Real Tensile Properties using Extrapolations from Atomistic Simulations: An Assessment on Thermoplastic Starch
- 2021
-
Ingår i: Polymer. - : Elsevier BV. - 0032-3861 .- 1873-2291. ; 228:123919
-
Tidskriftsartikel (refereegranskat)abstract
- Atomistic molecular dynamics (MD) simulations can be used to predict mechanical properties, such as stiffness and strength, for polymers. A concern is unavoidably high strain rates in simulations compared with those in physical experiments. To quantitatively capture the mechanical properties of the ‘real’ material, i.e., to predict absolute values rather than just qualitative trends, extrapolation to realistic strain rates is required. In this study, different strain-rate extrapolation strategies involving time-temperature shifting with the Williams-Landel-Ferry equation (above Tg) and the Eyring equation (below Tg) were evaluated, using thermoplastic starch as an example. MD simulations were first used to compute the stiffness and strength at three (high) strain rates over a wide range of temperatures. The mechanical MD data were then horizontally time-temperature shifted, resulting in master curves with strain-rate (x-axis) versus mechanical properties (y-axis). The precision in the prediction of experimental data was quite good in several cases, but was dependent on the extrapolation method and the specific thermoplastic starch system. A notable finding was that the simulations could be simplified using fewer simulation strain rates and temperatures. The extrapolation techniques used here are expected to be valid for other polymer systems, but this remains to be validated.
|
|
| 3. |
- Özkirimli, Umut
(författare)
-
Nationalism
- 2019
-
Ingår i: Oxford Bibliographies.
-
Tidskriftsartikel (refereegranskat)
|
|
| 4. |
- Aad, G., et al.
(författare)
-
- 2013
-
Tidskriftsartikel (refereegranskat)
|
|
| 5. |
- Aad, G., et al.
(författare)
-
- 2012
-
Tidskriftsartikel (refereegranskat)
|
|
| 6. |
- Aad, G., et al.
(författare)
-
- 2015
-
Tidskriftsartikel (refereegranskat)
|
|
| 7. |
- ÖZEN, MUSTAFA, 1984, et al.
(författare)
-
Combiner synthesis for active load-modulationbased power amplifiers
- 2019
-
Ingår i: Radio Frequency and Microwave Power Amplifiers: Efficiency and Linearity Enhancement Techniques. ; , s. 225-253
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter discusses the fundamental operation of Doherty and outphasing Pas. Rather than using the original combiner topologies as a starting point, our focus will be on the desired transistor operation. Based on the active loadmodulation conditions that the Doherty and outphasing Pas dictate, we will therefore instead derive the combiners that present the desired behavior. The original solutions will thus appear as special cases when ideal operation is assumed. For any other case, new solutions will appear. We will show how this approach can give both new insights, extended design spaces and improved performance. In the first part of this chapter, we will establish a theoretical framework for Doherty and outphasing combiner synthesis from the conditions that guarantee efficient operation. This will thereafter be applied and practically demonstrated, first in a Doherty design context and then in an outphasing design context. The chapter will be concluded with a brief summary and suggestions for future work.
|
|
| 8. |
- Özgünoglu, Mehmet, 1989
(författare)
-
Numerical Analysis of Cavitation-Induced Erosion in High-Pressure Fuel Injectors: under static and dynamic lift conditions
- 2024
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fuel injection systems are crucial for all modern combustion engines. These systems often operate under very high pressures to ensure fast spray breakup for optimal fuel air mixing leading to efficient combustion in order to meet strict emission standards. However, this high-pressure environment, combined with complicated geometries, can lead to sudden velocity and pressure changes within the fuel injector, making it susceptible to cavitation – a phenomenon where local pressure drops below the vapor pressure and the liquid fuel suddenly evaporates. Cavitation-induced erosion in fuel injectors affects combustion efficiency and system durability, presenting a challenge for analysis. This study explores the numerical assessment of cavitation-induced erosion in high-pressure fuel injectors using computational fluid dynamics (CFD). Reynolds-averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) are employed with specific sub-models. Cavitation is modeled using the mixture transport of modified Zwart-Gerber-Belamri approach. The investigation starts with low and high lift static needle positions, comparing the results with experimental data to gain insight into erosion behaviour in an industrial heavy duty injector. To examine the effect of the surface deviations to erosion patterns, static high lift condition is modeled with CAD and Tomography Scan separately. Finally, the effect of the needle motion is carried out by implementing “wobbling” and “lift only” motion profiles using RANS.
|
|
| 9. |
- Özkan, Emre, et al.
(författare)
-
Online EM algorithm for joint state and mixture measurement noise estimation
- 2012
-
Ingår i: 15th International Conference on Information Fusion (FUSION), 2012. - : IEEE. - 9781467304177 - 9780982443842 ; , s. 1935-1940
-
Konferensbidrag (refereegranskat)abstract
- In this study, we aim to estimate the unknown multi-modal measurement noise distribution of nonlinear state space models. The unknown noise distribution is modeled as a mixture of exponential family of distributions. We use the Expectation-Maximization (EM) method in order to jointly estimate the unknown parameters as well as the states. The online version of the EM algorithm is implemented by using particle filtering techniques. The resulting algorithm is a noise adaptive particle filter which is applicable to many sensor models having multi-modal noise distributions with unknown parameters.
|
|
| 10. |
|
|
