- document
-
Nutter, John (author), Qi, Jiahui (author), Farahani, H. (author), Rainforth, W. Mark (author), van der Zwaag, S. (author)The current study reports in situ TEM observations of the growth of bainitic ferrite in an Fe-0.3C-3Mn-1.5Si-0.15Mo steel held isothermally at 300 °C with a higher spatio-temporal resolution than in previous studies. Significant variations were found in the lengthening rate, with the highest being in excess of 30,000 nm.s<sup>−1</sup> while...journal article 2023
- document
-
Abraham Mathews, J. (author), Farahani, H. (author), Sietsma, J. (author), Petrov, R.H. (author), Mecozzi, M.G. (author), Santofimia, Maria Jesus (author)The influence of carbon concentration variations on pearlite formation (20 h at 600 °C) in a case-carburized steel is investigated. The resultant microstructure shows three distinct regions: carburized case, a transition region, and the original core. The microstructural transition from the case to the core regions is observed to be...journal article 2023
- document
-
Hidalgo Garcia, J. (author), Vittorietti, M. (author), Farahani, H. (author), Vercruysse, F. (author), Petrov, R.H. (author), Sietsma, J. (author)Understanding the local strain enhancement and lattice distortion resulting from different microstructure features in metal alloys is crucial in many engineering processes. The development of heterogeneous strain not only plays an important role in the work hardening of the material but also in other processes such as recrystallization and...journal article 2020
- document
-
Farahani, H. (author), Xu, W. (author), van der Zwaag, S. (author)Controlling the kinetics of austenite decomposition by controlled partitioning of alloying elements, in particular carbon and manganese, is the key factor for optimizing the microstructures of advanced high-strength steels. In this study, a systematic set of computational and experimental cyclic partial phase transformations in low to medium...journal article 2019
- document
-
Farahani, H. (author), Zijlstra, Gerrit (author), Mecozzi, M.G. (author), Ocelík, Václav (author), De Hosson, Jeff Th M. (author), van der Zwaag, S. (author)In this research, in situ high-temperature electron backscattered diffraction (EBSD) mapping is applied to record and analyze the migration of the α/3 interfaces during cyclic austenite-ferrite phase transformations in a medium manganese steel. The experimental study is supplemented with related 3D phase field (PF) simulations to better...journal article 2019
- document
-
Slobbe, D.C. (author), Klees, R. (author), Farahani, H. (author), Huisman, L. (author), Alberts, Bas (author), Voet, Pierre (author), Doncker, Filip De (author)We present a local quasi-geoid (QG) model which combines a satellite-only global gravity model with local data sets using weighted least squares. The QG is computed for an area comprising the Netherlands, Belgium, and the southern North Sea. It uses a two-scale spherical radial basis function model complemented by bias parameters to account...journal article 2019
- document
-
Nutter, J. (author), Farahani, H. (author), Rainforth, W. M. (author), van der Zwaag, S. (author)The kinetic behaviour of austenite/ferrite interfaces in a low carbon – 0.5 mass% Mn containing steel during Cyclic Partial Phase Transformation (CPPT) experiments has been investigated using hot stage Transmission Electron Microscopy (TEM). Individual interfaces were observed to display behaviour typical of CPPT experiments as recorded in...journal article 2019
- document
-
Farahani, H. (author), Zurob, Hatem (author), Hutchinson, Christopher R. (author), van der Zwaag, S. (author)Investigating the partitioning effect of substitutional and interstitial elements on the migration of transformation interfaces during austenite-ferrite phase transformation in steels with the conventional experimental method is extremely challenging due to interaction between the solute atoms and the transformation interfaces. Additionally,...journal article 2018
- document
-
Klees, R. (author), Slobbe, D.C. (author), Farahani, H. (author)The posed question arises for instance in regional gravity field modelling using weighted least-squares techniques if the gravity field functionals are synthesised from the spherical harmonic coefficients of a satellite-only global gravity model (GGM), and are used as one of the noisy datasets. The associated noise covariance matrix, appeared...journal article 2018
- document
-
Slobbe, D.C. (author), Klees, R. (author), Verlaan, M. (author), Zijl, F. (author), Alberts, BA (author), Farahani, H. (author)We present an efficient and flexible alternative method to connect islands and offshore tide gauges with the height system on land. The method uses a regional, high-resolution hydrodynamic model that provides total water levels. From the model, we obtain the differences in mean water level (MWL) between tide gauges at the mainland and at the...journal article 2018
- document
-
Farahani, H. (author), Xu, W. (author), van der Zwaag, S. (author)Formation of the microstructural ferrite/pearlite bands in medium Mn steels is an undesirable phenomenon commonly addressed through fast cooling treatments. In this study, a novel approach using the cyclic partial phase transformation concept is applied successfully to prevent microstructural band formation in a micro-chemically banded Fe-C...journal article 2018
- document
-
Klees, R. (author), Slobbe, D.C. (author), Farahani, H. (author)The paper is about a methodology to combine a noisy satellite-only global gravity field model (GGM) with other noisy datasets to estimate a local quasi-geoid model using weighted least-squares techniques. In this way, we attempt to improve the quality of the estimated quasi-geoid model and to complement it with a full noise covariance matrix...journal article 2018
- document
-
Sainis, Salil (author), Farahani, H. (author), Gamsjäger, Ernst (author), van der Zwaag, S. (author)Direct microscopic observation of the isothermal bainite evolution in terms of nucleation events, the location of the nuclei, as well as their growth is very valuable for the refinement of models predicting the kinetics of bainite transformation. To this aim, the microstructural evolution in a Fe-0.2C-1.5Mn-2.0Cr alloy during isothermal...journal article 2018
- document
-
Farahani, H. (author), Xu, W. (author), van der Zwaag, S. (author)Predicting the effect of alloying elements on the degree of incomplete austenite to bainite transformation in low carbon steels is of great industrial importance. This study introduces an extended Gibbs energy balance model which makes use of an additive approach to calculate the coupled effect of Mn, Si and Mo on the fraction of bainitic...journal article 2018
- document
-
Farahani, H. (author), Klees, R. (author), Slobbe, D.C. (author)We assess the surface gravity data requirements for a 5-mm quasi-geoid model for the Netherlands mainland and continental shelf in terms of omission and commission errors. The omission error critically depends on the roughness of the topography and bathymetry. For the Netherlands continental shelf, Central and Northern Netherlands, the...journal article 2017
- document
-
Guo, X. (author), Ditmar, P.G. (author), Zhao, Q (author), Klees, R. (author), Farahani, H. (author)GPS data collected by satellite gravity missions can be used for extracting the long-wavelength part of the Earth’s gravity field. We propose a new data processing method which makes use of the ‘average acceleration’ approach to gravity field modelling. In this method, satellite accelerations are directly derived from GPS carrier phase...journal article 2017
- document
-
Farahani, H. (author), Slobbe, D.C. (author), Klees, R. (author), Seitz, Kurt (author)We study the impact of an accurate computation and incorporation of coloured noise in radar altimeter data when computing a regional quasi-geoid model using least-squares techniques. Our test area comprises the Southern North Sea including the Netherlands, Belgium, and parts of France, Germany, and the UK. We perform the study by modelling...journal article 2017
- document
-
Ran, J. (author), Ditmar, P.G. (author), Klees, R. (author), Farahani, H. (author)We present an improved mascon approach to transform monthly spherical harmonic solutions based on GRACE satellite data into mass anomaly estimates in Greenland. The GRACE-based spherical harmonic coefficients are used to synthesize gravity anomalies at satellite altitude, which are then inverted into mass anomalies per mascon. The limited...journal article 2017
- document
-
Farahani, H. (author), Xu, W. (author), Van der Zwaag, S. (author)In this research, the effects of Mn and Si concentration and that of the isothermal intercritical holding temperature on the austenite-to-ferrite (? ? ?) and the martensite-to-austenite (?? ? ?) phase transformations are studied for a series of Fe-C-Mn-Si steels with up to 7 wt pct Mn. The model is based on the local equilibrium (LE) concept....journal article 2015
- document
-
Siemes, C. (author), Ditmar, P. (author), Riva, E.M. (author), Slobbe, D.C. (author), Liu, X.L. (author), Farahani, H. (author)The Gravity Recovery and Climate Experiment (GRACE) satellite mission measures the Earth’s gravity field since March 2002. We propose a new filtering procedure for post-processing GRACE-based monthly gravity field solutions provided in the form of spherical harmonic coefficients. The procedure is tuned for the optimal estimation of linear trends...journal article 2012