Growth -Front Modulation in Lamp Zone Melting of Si on SiO2

1986 ◽  
Vol 74 ◽  
Author(s):  
D. Dutartre ◽  
D. Bensahel ◽  
M. Haond
Keyword(s):  
Solidification Front ◽  
Growth Front ◽  
Zone Melting ◽  
Silicon On Insulator ◽  
Polysilicon Film ◽  
Defect Localization ◽  
In Situ Observations ◽  
Periodical Variation

AbstractWe present 3 techniques of defect localization we have studied in order to produce Silicon On Insulator films obtained by Lamp Zone Melting. They consist in a periodical variation of the thickness of either the oxide cap, or the polysilicon film, or the underlying oxide layer. We compare the crystallographic quality of the resulting films and in-situ observations of the solidification front for each structure.

scholarly journals The extreme runoff index for flood early warning in Europe

2014 ◽  
Vol 14 (6) ◽  
pp. 1505-1515 ◽  
Author(s):  
L. Alfieri ◽  
F. Pappenberger ◽  
F. Wetterhall
Keyword(s):  
Early Warning ◽  
Input Data ◽  
Weather Forecasting ◽  
Spatial Inhomogeneity ◽  
Optimal Timing ◽  
Numerical Predictions ◽  
In Situ Observations

Abstract. Systems for the early detection of floods over continental and global domains have a key role in providing a quick overview of areas at risk, raise the awareness and prompt higher detail analyses as the events approach. However, the reliability of these systems is prone to spatial inhomogeneity, depending on the quality of the underlying input data and local calibration. This work proposes a simple approach for flood early warning based on ensemble numerical predictions of surface runoff provided by weather forecasting centers. The system is based on a novel indicator, referred to as an extreme runoff index (ERI), which is calculated from the input data through a statistical analysis. It is designed for use in large or poorly gauged domains, as no local knowledge or in situ observations are needed for its setup. Daily runs over 32 months are evaluated against calibrated hydrological simulations for all of Europe. Results show skillful flood early warning capabilities up to a 10-day lead time. A dedicated analysis is performed to investigate the optimal timing of forecasts to maximize the detection of extreme events. A case study for the central European floods of June 2013 is presented and forecasts are compared to the output of a hydro-meteorological ensemble model.

scholarly journals Investigating tool engagement in groundwood pulping: finite element modelling and in-situ observations at the microscale

Holzforschung ◽  
2020 ◽  
Vol 74 (5) ◽  
pp. 477-487 ◽  
Author(s):  
Jenny Carlsson ◽  
Magnus Heldin ◽  
Per Isaksson ◽  
Urban Wiklund
Keyword(s):  
Finite Element ◽  
Numerical Models ◽  
X Ray ◽  
Tool Geometries ◽  
Commercial Use ◽  
X Ray Computed ◽  
In Situ Observations ◽  
Underlying Mechanisms

AbstractWith industrial groundwood pulping processes relying on carefully designed grit surfaces being developed for commercial use, it is increasingly important to understand the mechanisms occurring in the contact between wood and tool. We present a methodology to experimentally and numerically analyse the effect of different tool geometries on the groundwood pulping defibration process. Using a combination of high-resolution experimental and numerical methods, including finite element (FE) models, digital volume correlation (DVC) of synchrotron radiation-based X-ray computed tomography (CT) of initial grinding and lab-scale grinding experiments, this paper aims to study such mechanisms. Three different asperity geometries were studied in FE simulations and in grinding of wood from Norway spruce. We found a good correlation between strains obtained from FE models and strains calculated using DVC from stacks of CT images of initial grinding. We also correlate the strains obtained from numerical models to the integrity of the separated fibres in lab-scale grinding experiments. In conclusion, we found that, by modifying the asperity geometries, it is, to some extent, possible to control the underlying mechanisms, enabling development of better tools in terms of efficiency, quality of the fibres and stability of the groundwood pulping process.

Melting and Solidification Dynamics in Zone Melting of Si Films.

1987 ◽  
Vol 107 ◽  
Author(s):  
D. Dutartre
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Zone Melting ◽  
Silicon On Insulator ◽  
Experimental Conditions ◽  
Melting Front ◽  
Physical Mechanisms ◽  
Si Films ◽  
Melting And Solidification

AbstractWe discuss the physics involved in the melting and solidification of Silicon On Insulator thin films (SOI) using lamp or graphite strip heaters. The melting front, called “explosive melting”, controls to a large part the final morphological quality of the SOI film. It exhibits instabilities which can (i) nucleate the dewetting of the film, (ii) cause voids, and (iii) produce a poor surface morphology. The morphologies of the solidification fronts are analyzed. We show that, depending on the experimental conditions, different physical mechanisms are responsible for the front breakdown. Thus we propose that the variety of front morphologies results from the variety of the mechanisms involved, and of their combinations with the “faceting effects”.

Liquid-Solid Interface Morphologies and Defect Structures in Zone-Melting-Recrystallized Silicon-On-Insulator Films

1987 ◽  
Vol 107 ◽  
Author(s):  
J. S. Im ◽  
C. K. Chen ◽  
C. V. Thompson ◽  
M. W. Geis ◽  
H. Tomita
Keyword(s):  
Zone Melting ◽  
Silicon On Insulator ◽  
Radiative Heating ◽  
Interfacial Region ◽  
Defect Structures ◽  
Interface Morphology ◽  
Experimental Conditions ◽  
Solid Interface ◽  
Free Films

AbstractIn-situ optical microscopy has been used to observe liquid-solid interface morphologies during zone-melting recrystallization of silicon-on-insulator films. These morphologies have been correlated with the defect morphologies of the recrystallized films. Stable cellular solidification fronts, which are obtained at low zone velocities if the radiation intensity gradient in the interfacial region is small, yield subboundary free films. We suggest that under these experimental conditions the interface morphology is primarily the result of radiative heating rather than constitutional supercooling.

Sanctions and the Scientific Community of Iran

2020 ◽  
Vol 8 (2) ◽  
pp. 225-264
Author(s):  
Parviz Tarikhi
Keyword(s):  
Scientific Community ◽  
Scientific Production ◽  
In Situ Observations ◽  
The Impact

Sanctions on the scientific community of Iran go back to the days following the victory of the 1979 revolution when the severe pressures on the country commenced. Although it is still difficult to estimate quantitatively the impacts of sanctions on the Iranian scientific community, the qualitative estimations and in situ observations bolster the idea that sanctions, particularly those in recent decades, have led to an obvious decrease in the quality of Iranian scientific production. It has led to further cosmopolitanism of the Iranian scientific community in diaspora, and has strengthened extremism and predomination of hardliner attitudes domestically. This paper demonstrates the impact of foreign sanctions on the scientific community of Iran in addition to the already deplorable pressure initiated by the post-revolutionary ruling system and its administration.

scholarly journals Creation and Validation of a Comprehensive 1° by 1° Daily Gridded North American Dataset for 1900–2009: Snowfall

2016 ◽  
Vol 33 (5) ◽  
pp. 857-871 ◽  
Author(s):  
Daria Kluver ◽  
Tom Mote ◽  
Daniel Leathers ◽  
Gina R. Henderson ◽  
Weihan Chan ◽  
...  
Keyword(s):  
North America ◽  
North American ◽  
Independent Set ◽  
Measurement Sensitivity ◽  
The North ◽  
In Situ Observations ◽  
Point Data ◽  
Fold Cross Validation

AbstractThis study details the creation of a gridded snowfall dataset for North America, with focus on the quality of the interpolated product. Daily snowfall amounts from National Weather Service Cooperative Observer Program stations and Meteorological Service of Canada surface stations are interpolated to 1° by 1° grids from 1900 to 2009 and examined for data record length and quality. The interpolation is validated spatially and temporally through the use of stratified sampling and k-fold cross-validation analyses. Interpolation errors average around 0.5 cm and range from less than 0.01 to greater than 2.5 cm. For most locations, this is within the measurement sensitivity. Grid cells with large variations in elevation experience higher errors and should be used with caution. A new gridded snowfall climatology is presented based on in situ observations that capture seasonal and interannual variability in monthly snowfall over most of the North American land area from 1949 to 2009. The Community Collaborative Rain, Hail and Snow Network is used as an independent set of point data that is compared to the gridded product. Errors are mainly in the form of the gridded data underestimating snowfall compared to the point data. The spatial extent, temporal length, and resolution of the dataset are unprecedented with regard to observational snowfall products and will present new opportunities for examining snowfall across North America.

Microscopy of Thin Si Films During Lamp Zone Melting

1985 ◽  
Vol 53 ◽  
Author(s):  
D. Dutartre ◽  
M. Haond ◽  
D. Bensahel
Keyword(s):  
Zone Melting ◽  
Silicon On Insulator ◽  
Spatial Modulation ◽  
Freezing Front ◽  
Melting Front ◽  
Scan Speed ◽  
Entrainment Effect ◽  
Si Films ◽  
Melting And Solidification

ABSTRACTThe melting and solidification fronts of thin Silicon On Insulator (SOI) films have been observed in-situ. The melting front does not advance continuously but by bursts. This so called “explosive melting” allows to explain the appearance of defects (such as voids and surface roughness) observed in the recrystallized film. The freezing front is observed in the case where a pattern for the entrainment of the defects has been etched in the underlying oxide: we show that the entrainment effect is due to the spatial modulation of the solidification front by the structure. Furthermore, the scan speed influences the morphology of the liquid/solid interface and the defect entrainment efficiency.

scholarly journals The extreme runoff index for flood early warning in Europe

2013 ◽  
Vol 1 (6) ◽  
pp. 7517-7548
Author(s):  
L. Alfieri ◽  
F. Pappenberger ◽  
F. Wetterhall
Keyword(s):  
Early Warning ◽  
Input Data ◽  
Weather Forecasting ◽  
Spatial Inhomogeneity ◽  
Optimal Timing ◽  
Numerical Predictions ◽  
In Situ Observations

Abstract. Systems for the early detection of floods over continental and global domains have a key role in providing a quick overview of areas at risk, raise the awareness and prompt higher detail analyses as the events approach. However, the reliability of these systems is prone to spatial inhomogeneity, depending on the quality of the underlying input data and local calibration. This work proposes a simple approach for flood early warning based on ensemble numerical predictions of surface runoff, provided by weather forecasting centers. The system is based on a novel indicator, referred to as Extreme Runoff Index, which is calculated from the input data through a statistical analysis. It is designed for use in large or poorly gauged domains, as no local knowledge or in situ observations are needed for its setup. Daily runs over 32 months are evaluated against calibrated hydrological simulations for the entire Europe. Results show skillful flood early warning capabilities up to a 10 day lead time. A dedicated analysis is performed to investigate the optimal timing of forecasts to maximize the detection of extreme events. A case study for the Central Europe floods in June 2013 is presented and forecasts compared to the output of a hydro-meteorological ensemble model.

Metadata from WMO Publication No. 47 and an Assessment of Voluntary Observing Ship Observation Heights in ICOADS

2007 ◽  
Vol 24 (2) ◽  
pp. 214-234 ◽  
Author(s):  
Elizabeth C. Kent ◽  
Scott D. Woodruff ◽  
David I. Berry
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Measurement Methods ◽  
Data Set ◽  
Climate Record ◽  
Ocean Atmosphere ◽  
In Situ Observations ◽  
Climate Studies

Abstract It is increasingly recognized that metadata can significantly improve the quality of scientific analyses and that the availability of metadata is particularly important for the study of climate variability. The International Comprehensive Ocean–Atmosphere Data Set (ICOADS) contains in situ observations frequently used in climate studies, and this paper describes the ship metadata that are available to complement ICOADS. This paper highlights the metadata available in World Meteorological Organization Publication No. 47 that include information on measurement methods and observation heights. Changing measurement methods and heights are known to be a cause of spurious change in the climate record. Here the authors focus on identifying measurement heights for air temperature and wind speed and also give information on SST measurement depths.

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