Pulsed Laser Deposition of Si Nanocluster Films

1995 ◽  
Vol 397 ◽  
Author(s):  
W. Marine ◽  
I. Movtchan ◽  
A. Simakine ◽  
L. Patrone ◽  
R. Dreyfus ◽  
...  
Keyword(s):  
Plasma Plume ◽  
Temporal Evolution ◽  
Film Formation ◽  
Laser Wavelength ◽  
Inert Gases ◽  
Preparation Conditions ◽  
Spatio Temporal ◽  
Optical Time ◽  
193 Nm ◽  
Average Cluster

ABSTRACTReactive laser ablation of Si targets by ArF* excimer laser (wavelength 193 nm, pulse width 15 ns (FWHM)) was performed in He, Ar or O2 0.05-1 Torr atmospheres and led to Si-SiOx nanocluster thin film formation within laser-induced plasma plume. Optical spectroscopy and optical Time-of-Flight (TOF) measurements were carried out during ablation-deposition experiments. A number of large weak emission bands in blue and green-yellow spectral branches were observed both in inert gases and in oxygen ambient atmospheres and attributed to the emission from excited nanoparticles in the plasma plume. TOF measurements proved a different spatio-temporal evolution of this emission compare to the emission of monoatomic particles. The films exhibit photoluminescence bands in the UV region (around 290 nm and between 310-370 nm), in the blue (between 420 and 500 nm), and in the green-yellow (at 520-560 nm). The relative intensities of the luminescence bands depend on the average cluster size, which is determined by preparation conditions (nature and pressure of the ambient gas, laser fluence).

Characterization of Laser Induced Plasmas by Fast Imaging for Graphite Target

2011 ◽  
Vol 227 ◽  
pp. 76-79
Author(s):  
Chaouki Siouani ◽  
Samira Abdelli-Messaci ◽  
Tahar Kerdja ◽  
Smail Malek
Keyword(s):  
Plasma Plume ◽  
Light Emission ◽  
Temporal Evolution ◽  
Gas Pressure ◽  
Fast Imaging ◽  
Laser Irradiance ◽  
Graphite Target ◽  
Mean Velocity ◽  
Iccd Camera ◽  
Spatio Temporal

Plume expansion dynamics of an ablated graphite target by the third harmonic of Nd-YAG laser of 355 nm wavelength has been investigated using an ICCD camera fast imaging. This study was carried out into vacuum and methane (CH4) atmosphere at different pressures. Into vacuum, the two dimensional spatio-temporal evolution of plasma plume was performed at a laser irradiance range of 5.5x108 - 6x109 W/cm2. The plasma mean velocity has been estimated and was found to increase with laser power density increases until it reaches a maximum value of 107 cm/s. In presence of gas, the plasma plume dynamics was studied at a fixed irradiance of 4.3x 109 W/cm2 and from 0.05 to 5 mbar CH4 pressures. The plasma spatio-temporal evolution was found to be influenced by the gas pressure. In earlier time the expansion was almost linear independently of the background gas pressure used. However, as time evolves, the plume is decelerated, then presented a stationary behaviour at 1 and 5 mbar. Furthermore, the light emission from the plume very close to the target surface exists until a few microseconds into vacuum and CH4 atmosphere and then vanishes. It appears again around 10 µs following by the emission of particulates as bright incandescent tracks.

Spatio-temporal evolution and dynamic origin of Jurassic-Cretaceous magmatism in the South China Block

2021 ◽  
Vol 217 ◽  
pp. 103605
Author(s):  
Xianzhi Cao ◽  
Nicolas Flament ◽  
Sanzhong Li ◽  
R. Dietmar Müller
Keyword(s):  
South China ◽  
Temporal Evolution ◽  
South China Block ◽  
The South ◽  
Spatio Temporal ◽  
Cretaceous Magmatism

scholarly journals Spatio-temporal evolution and influencing mechanism of the COVID-19 epidemic in Shandong province, China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jinlong Shi ◽  
Xing Gao ◽  
Shuyan Xue ◽  
Fengqing Li ◽  
Qifan Nie ◽  
...  
Keyword(s):  
Prevention And Control ◽  
Temporal Evolution ◽  
Geographical Location ◽  
Shandong Province ◽  
Control Measures ◽  
Middle Aged ◽  
Health Crisis ◽  
Aged People ◽  
Spatio Temporal ◽  
And Control

AbstractThe novel coronavirus pneumonia (COVID-19) outbreak that emerged in late 2019 has posed a severe threat to human health and social and economic development, and thus has become a major public health crisis affecting the world. The spread of COVID-19 in population and regions is a typical geographical process, which is worth discussing from the geographical perspective. This paper focuses on Shandong province, which has a high incidence, though the first Chinese confirmed case was reported from Hubei province. Based on the data of reported confirmed cases and the detailed information of cases collected manually, we used text analysis, mathematical statistics and spatial analysis to reveal the demographic characteristics of confirmed cases and the spatio-temporal evolution process of the epidemic, and to explore the comprehensive mechanism of epidemic evolution and prevention and control. The results show that: (1) the incidence rate of COVID-19 in Shandong is 0.76/100,000. The majority of confirmed cases are old and middle-aged people who are infected by the intra-province diffusion, followed by young and middle-aged people who are infected outside the province. (2) Up to February 5, the number of daily confirmed cases shows a trend of “rapid increase before slowing down”, among which, the changes of age and gender are closely related to population migration, epidemic characteristics and intervention measures. (3) Affected by the regional economy and population, the spatial distribution of the confirmed cases is obviously unbalanced, with the cluster pattern of “high–low” and “low–high”. (4) The evolution of the migration pattern, affected by the geographical location of Wuhan and Chinese traditional culture, is dominated by “cross-provincial” and “intra-provincial” direct flow, and generally shows the trend of “southwest → northeast”. Finally, combined with the targeted countermeasures of “source-flow-sink”, the comprehensive mechanism of COVID-19 epidemic evolution and prevention and control in Shandong is revealed. External and internal prevention and control measures are also figured out.

scholarly journals Adjoint-based direct data assimilation of GNSS time series for optimizing frictional parameters and predicting postseismic deformation following the 2003 Tokachi-oki earthquake

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Masayuki Kano ◽  
Shin’ichi Miyazaki ◽  
Yoichi Ishikawa ◽  
Kazuro Hirahara
Keyword(s):  
Time Series ◽  
Data Assimilation ◽  
Evaluation Method ◽  
Temporal Evolution ◽  
Recovery Process ◽  
Postseismic Deformation ◽  
Coseismic Slip ◽  
Megathrust Earthquakes ◽  
Spatio Temporal ◽  
Gnss Time Series

Abstract Postseismic Global Navigation Satellite System (GNSS) time series followed by megathrust earthquakes can be interpreted as a result of afterslip on the plate interface, especially in its early phase. Afterslip is a stress release process accumulated by adjacent coseismic slip and can be considered a recovery process for future events during earthquake cycles. Spatio-temporal evolution of afterslip often triggers subsequent earthquakes through stress perturbation. Therefore, it is important to quantitatively capture the spatio-temporal evolution of afterslip and related postseismic crustal deformation and to predict their future evolution with a physics-based simulation. We developed an adjoint data assimilation method, which directly assimilates GNSS time series into a physics-based model to optimize the frictional parameters that control the slip behavior on the fault. The developed method was validated with synthetic data. Through the optimization of frictional parameters, the spatial distributions of afterslip could roughly (but not in detail) be reproduced if the observation noise was included. The optimization of frictional parameters reproduced not only the postseismic displacements used for the assimilation, but also improved the prediction skill of the following time series. Then, we applied the developed method to the observed GNSS time series for the first 15 days following the 2003 Tokachi-oki earthquake. The frictional parameters in the afterslip regions were optimized to A–B ~ O(10 kPa), A ~ O(100 kPa), and L ~ O(10 mm). A large afterslip is inferred on the shallower side of the coseismic slip area. The optimized frictional parameters quantitatively predicted the postseismic GNSS time series for the following 15 days. These characteristics can also be detected if the simulation variables can be simultaneously optimized. The developed data assimilation method, which can be directly applied to GNSS time series following megathrust earthquakes, is an effective quantitative evaluation method for assessing risks of subsequent earthquakes and for monitoring the recovery process of megathrust earthquakes.

scholarly journals Glimpse: A Gaze-Based Measure of Temporal Salience

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3099
Author(s):  
V. Javier Traver ◽  
Judith Zorío ◽  
Luis A. Leiva
Keyword(s):  
Visual Attention ◽  
Computational Models ◽  
Temporal Evolution ◽  
Temporal Consistency ◽  
Visual Salience ◽  
Temporal Dimension ◽  
Spatial Perspective ◽  
Spatio Temporal ◽  
Scoring Algorithms ◽  
Over Time

Temporal salience considers how visual attention varies over time. Although visual salience has been widely studied from a spatial perspective, its temporal dimension has been mostly ignored, despite arguably being of utmost importance to understand the temporal evolution of attention on dynamic contents. To address this gap, we proposed Glimpse, a novel measure to compute temporal salience based on the observer-spatio-temporal consistency of raw gaze data. The measure is conceptually simple, training free, and provides a semantically meaningful quantification of visual attention over time. As an extension, we explored scoring algorithms to estimate temporal salience from spatial salience maps predicted with existing computational models. However, these approaches generally fall short when compared with our proposed gaze-based measure. Glimpse could serve as the basis for several downstream tasks such as segmentation or summarization of videos. Glimpse’s software and data are publicly available.

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