Time-dependent yield of the hydrated electron in subcritical and supercritical water studied by ultrafast pulse radiolysis and Monte-Carlo simulation

2012 ◽  
Vol 14 (41) ◽  
pp. 14325 ◽  
Author(s):  
Yusa Muroya ◽  
Sunuchakan Sanguanmith ◽  
Jintana Meesungnoen ◽  
Mingzhang Lin ◽  
Yu Yan ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Supercritical Water ◽  
Pulse Radiolysis ◽  
Hydrated Electron ◽  
Time Dependent ◽  
Ultrafast Pulse

Pulse Radiolysis of Supercritical Water. 3. Spectrum and Thermodynamics of the Hydrated Electron

2005 ◽  
Vol 109 (7) ◽  
pp. 1299-1307 ◽  
Author(s):  
David M. Bartels ◽  
Kenji Takahashi ◽  
Jason A. Cline ◽  
Timothy W. Marin ◽  
Charles D. Jonah
Keyword(s):  
Supercritical Water ◽  
Pulse Radiolysis ◽  
Hydrated Electron

Radiolysis of liquid water: An attempt to reconcile Monte-Carlo calculations with new experimental hydrated electron yield data at early times

2002 ◽  
Vol 80 (10) ◽  
pp. 1367-1374 ◽  
Author(s):  
Yusa Muroya ◽  
Jintana Meesungnoen ◽  
Jean-Paul Jay-Gerin ◽  
Abdelali Filali-Mouhim ◽  
Thomas Goulet ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Liquid Water ◽  
Hydrated Electron ◽  
Time Dependent ◽  
Water Radiolysis ◽  
Deterministic Models ◽  
Yield Data ◽  
Simulation Code ◽  
Time Zero ◽  
Electron Yield

A re-examination of our Monte-Carlo modeling of the radiolysis of liquid water by low linear-energy-transfer (LET ~ 0.3 keV µm–1) radiation is undertaken herein in an attempt to reconcile the results of our simulation code with recently revised experimental hydrated electron (e–aq) yield data at early times. The thermalization distance of subexcitation electrons, the recombination cross section of the electrons with their water parent cations prior to thermalization, and the branching ratios of the different competing mechanisms in the dissociative decay of vibrationally excited states of water molecules were taken as adjustable parameters in our simulations. Using a global-fit procedure, we have been unable to find a set of values for those parameters to simultaneously reproduce (i) the revised e–aq yield of 4.0 ± 0.2 molecules per 100 eV at "time zero" (that is, a reduction of ~20% over the hitherto accepted value of 4.8 molecules per 100 eV), (ii) the newly measured e–aq decay kinetic profile from 100 ps to 10 ns, and (iii) the time-dependent yields of the other radiolytic species H•, •OH, H2, and H2O2 (up to ~1 µs). The lowest possible limiting "time-zero" yield of e–aq that we could in fact obtain, while ensuring an acceptable agreement between all computed and experimental yields, was ~4.4 to 4.5 molecules per 100 eV. Under these conditions, the mean values of the electron thermalization distance and of the geminate electron–cation recombination probability, averaged over the subexcitation electron "entry spectrum," are found to be equal to ~139 Å and ~18%, respectively. These values are to be compared with those obtained in our previous simulations of liquid water radiolysis, namely ~88 Å and ~5.5%, respectively. Our average electron thermalization distance is also to be compared with the typical size (~64–80 Å) of the initial hydrated electron distributions estimated in current deterministic models of "spur" chemistry. Finally, our average probability for geminate electron–cation recombination agrees well with an estimated value of ~15% recently reported in the literature. In conclusion, this work shows that an adaptation of our calculations to a lower hydrated electron yield at early times is possible, but also suggests that the topic is not closed. Further measurements of the e–aq yields at very short times are needed. Key words: liquid water, radiolysis, electron–cation geminate recombination, electron thermalization distance, hydrated electron (e–aq), e–aq decay kinetics, time-dependent molecular and radical yields, Monte-Carlo simulations.

Mixed Efficient Global Optimization for Time-Dependent Reliability Analysis

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Zhen Hu ◽  
Xiaoping Du
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Global Optimization ◽  
Reliability Analysis ◽  
Surrogate Model ◽  
Extreme Value ◽  
Time Dependent ◽  
Efficient Global Optimization ◽  
Highly Nonlinear ◽  
Adaptive Kriging

Time-dependent reliability analysis requires the use of the extreme value of a response. The extreme value function is usually highly nonlinear, and traditional reliability methods, such as the first order reliability method (FORM), may produce large errors. The solution to this problem is using a surrogate model of the extreme response. The objective of this work is to improve the efficiency of building such a surrogate model. A mixed efficient global optimization (m-EGO) method is proposed. Different from the current EGO method, which draws samples of random variables and time independently, the m-EGO method draws samples for the two types of samples simultaneously. The m-EGO method employs the adaptive Kriging–Monte Carlo simulation (AK–MCS) so that high accuracy is also achieved. Then, Monte Carlo simulation (MCS) is applied to calculate the time-dependent reliability based on the surrogate model. Good accuracy and efficiency of the m-EGO method are demonstrated by three examples.

Monte Carlo simulation of time-dependent, transport-limited fluorescent boundary measurements in frequency domain

2007 ◽  
Vol 34 (4) ◽  
pp. 1298-1311 ◽  
Author(s):  
Tianshu Pan ◽  
John C. Rasmussen ◽  
Jae Hoon Lee ◽  
Eva M. Sevick-Muraca
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Frequency Domain ◽  
Time Dependent ◽  
Boundary Measurements ◽  
Dependent Transport

Probit-Based Time-Dependent Stochastic User Equilibrium Traffic Assignment Model

2008 ◽  
Vol 2085 (1) ◽  
pp. 86-94 ◽  
Author(s):  
Kuilin Zhang ◽  
Hani S. Mahmassani ◽  
Chung-Cheng Lu
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Spatial Correlation ◽  
Traffic Assignment ◽  
User Equilibrium ◽  
The Other ◽  
Time Dependent ◽  
Stochastic User Equilibrium ◽  
Assignment Model ◽  
Temporal And Spatial

This study presents a time-dependent stochastic user equilibrium (TDSUE) traffic assignment model within a probit-based path choice decision framework that explicitly takes into account temporal and spatial correlation (traveler interactions) in travel disutilities across a set of paths. The TDSUE problem, which aims to find time-dependent SUE path flows, is formulated as a fixed-point problem and solved by a simulation-based method of successive averages algorithm. A mesoscopic traffic simulator is employed to determine (experienced) time-dependent travel disutilities. A time-dependent shortest-path algorithm is applied to generate new paths and augment a grand path set. Two vehicle-based implementation techniques are proposed and compared in order to show their impact on solution quality and computational efficiency. One uses the classical Monte Carlo simulation approach to explicitly compute path choice probabilities, and the other determines probabilities by sampling vehicles’ path travel costs from an assumed perception error distribution (also using a Monte Carlo simulation process). Moreover, two types of variance-covariance error structures are discussed: one considers temporal and spatial path choice correlation (due to path overlapping) in terms of aggregated path travel times, and the other uses experienced (or empirical) path travel times from a sample of individual vehicle trajectories. A set of numerical experiments are conducted to investigate the convergence pattern of the solution algorithms and to examine the impact of temporal and spatial correlation on path choice behavior.

Acetone hydration in supercritical water: 13C-NMR spectroscopy and Monte Carlo simulation

2004 ◽  
Vol 120 (13) ◽  
pp. 6100-6110 ◽  
Author(s):  
Yoshihiro Takebayashi ◽  
Satoshi Yoda ◽  
Tsutomu Sugeta ◽  
Katsuto Otake ◽  
Takeshi Sako ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Nmr Spectroscopy ◽  
Supercritical Water ◽  
13C Nmr ◽  
13C Nmr Spectroscopy
Sign in / Sign up

Export Citation Format

Share Document