scholarly journals Including operational data in QMRA model: development and impact of model inputs

2008 ◽  
Vol 7 (1) ◽  
pp. 77-95 ◽  
Author(s):  
Kenza Jaidi ◽  
Benoit Barbeau ◽  
Annie Carrière ◽  
Raymond Desjardins ◽  
Michèle Prévost
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Model ◽  
Model Development ◽  
Microbial Risk ◽  
Relative Risks ◽  
The Mean ◽  
Log Normal ◽  
Simplified Calculation ◽  
The Impact ◽  
Selection Of

A Monte Carlo model, based on the Quantitative Microbial Risk Analysis approach (QMRA), has been developed to assess the relative risks of infection associated with the presence of Cryptosporidium and Giardia in drinking water. The impact of various approaches for modelling the initial parameters of the model on the final risk assessments is evaluated. The Monte Carlo simulations that we performed showed that the occurrence of parasites in raw water was best described by a mixed distribution: log-Normal for concentrations > detection limit (DL), and a uniform distribution for concentrations < DL. The selection of process performance distributions for modelling the performance of treatment (filtration and ozonation) influences the estimated risks significantly. The mean annual risks for conventional treatment are: 1.97E−03 (removal credit adjusted by log parasite = log spores), 1.58E−05 (log parasite = 1.7 × log spores) or 9.33E−03 (regulatory credits based on the turbidity measurement in filtered water). Using full scale validated SCADA data, the simplified calculation of CT performed at the plant was shown to largely underestimate the risk relative to a more detailed CT calculation, which takes into consideration the downtime and system failure events identified at the plant (1.46E−03 vs. 3.93E−02 for the mean risk).

Model Development and the Assessment of Competing Models

1974 ◽  
Vol 18 (4) ◽  
pp. 425-428
Author(s):  
Mark G. Pfeiffer ◽  
Arthur I. Siegel
Keyword(s):  
Monte Carlo ◽  
Real World ◽  
Utility Theory ◽  
Practical Problem ◽  
Monte Carlo Model ◽  
Model Development ◽  
Multiattribute Utility ◽  
Levels Of Abstraction ◽  
Multiattribute Utility Theory ◽  
Competing Models

The paper describes the process of model development and applies multiattribute utility theory to the practical problem of optimizing the selection among competing models designed for the same purpose. As an example, two models (Human Interactive and Monte Carlo) are compared which differ on the basis of their existing levels of abstraction, or their degree of remoteness from the real world. The slight superiority of the Monte Carlo Model resulted largely because it had higher utilities for the more important attributes of models such as repeatability of output, degree of error/low variability, and feasibility of use and application.

scholarly journals Application of Monte Carlo techniques with delay-time analysis to assess maintenance and inspection policies for marine systems

2016 ◽  
Vol 231 (2) ◽  
pp. 89-106 ◽  
Author(s):  
D McNamara ◽  
A Cunningham ◽  
R Riahi ◽  
I Jenkinson ◽  
J Wang
Keyword(s):  
Monte Carlo ◽  
Delay Time ◽  
Monte Carlo Model ◽  
Spare Part ◽  
Time Analysis ◽  
Factors Affecting ◽  
Monte Carlo Techniques ◽  
Marine System ◽  
Maintenance And Inspection ◽  
The Impact

This paper presents a novel methodology applying Monte Carlo methods with delay-time analysis to test the effects of scheduled maintenance and inspection actions on factors affecting the operational efficiency of a marine system which is subject to degradation. The aim is to demonstrate how a Monte Carlo model incorporated into delay-time analysis can be used to predict the transition behaviour of a system under analysis. The model presented in this paper focuses on the effects on system failure probability and downtime of various maintenance and inspection policies. The impact on spare part requirements is also investigated.

scholarly journals Monte Carlo Study of UAV-Measurable Albedo over Arctic Sea Ice

2018 ◽  
Vol 35 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Igor Podgorny ◽  
Dan Lubin ◽  
Donald K. Perovich
Keyword(s):  
Monte Carlo ◽  
Sea Ice ◽  
Energy Budget ◽  
Monte Carlo Model ◽  
Lower Troposphere ◽  
Monte Carlo Study ◽  
Open Water ◽  
Arctic Sea Ice ◽  
Inhomogeneous Surface ◽  
The Impact

AbstractIn anticipation that unmanned aerial vehicles (UAVs) will have a useful role in atmospheric energy budget studies over sea ice, a Monte Carlo model is used to investigate three-dimensional radiative transfer over a highly inhomogeneous surface albedo involving open water, sea ice, and melt ponds. The model simulates the spatial variability in 550-nm downwelling irradiance and albedo that a UAV would measure above this surface and underneath an optically thick, horizontally homogeneous cloud. At flight altitudes higher than 100 m above the surface, an airborne radiometer will sample irradiances that are greatly smoothed horizontally as a result of photon multiple reflection. If one is interested in sampling the local energy budget contrasts between specific surface types, then the UAV must fly at a low altitude, typically within 20 m of the surface. Spatial upwelling irradiance variability in larger open water features, on the order of 1000 m wide, will remain apparent as high as 500 m above the surface. To fully investigate the impact of surface feature variability on the energy budget of the lower troposphere ice–ocean system, a UAV needs to fly at a variety of altitudes to determine how individual features contribute to the area-average albedo.

scholarly journals Evaluation of a Disinfectant Wipe Intervention on Fomite-to-Finger Microbial Transfer

2014 ◽  
Vol 80 (10) ◽  
pp. 3113-3118 ◽  
Author(s):  
Gerardo U. Lopez ◽  
Masaaki Kitajima ◽  
Aaron Havas ◽  
Charles P. Gerba ◽  
Kelly A. Reynolds
Keyword(s):  
Escherichia Coli ◽  
Respiratory Pathogens ◽  
Quantitative Microbial Risk Assessment ◽  
Content Type ◽  
Microbial Risk Assessment ◽  
Surface Disinfection ◽  
Microbial Risk ◽  
Risk Assessment Models ◽  
The Mean ◽  
The Impact

ABSTRACTInanimate surfaces, or fomites, can serve as routes of transmission of enteric and respiratory pathogens. No previous studies have evaluated the impact of surface disinfection on the level of pathogen transfer from fomites to fingers. Thus, the present study investigated the change in microbial transfer from contaminated fomites to fingers following disinfecting wipe use.Escherichia coli(108to 109CFU/ml),Staphylococcus aureus(109CFU/ml),Bacillus thuringiensisspores (107to 108CFU/ml), and poliovirus 1 (108PFU/ml) were seeded on ceramic tile, laminate, and granite in 10-μl drops and allowed to dry for 30 min at a relative humidity of 15 to 32%. The seeded fomites were treated with a disinfectant wipe and allowed to dry for an additional 10 min. Fomite-to-finger transfer trials were conducted to measure concentrations of transferred microorganisms on the fingers after the disinfectant wipe intervention. The mean log10reduction of the test microorganisms on fomites by the disinfectant wipe treatment varied from 1.9 to 5.0, depending on the microorganism and the fomite. Microbial transfer from disinfectant-wipe-treated fomites was lower (up to <0.1% on average) than from nontreated surfaces (up to 36.3% on average, reported in our previous study) for all types of microorganisms and fomites. This is the first study quantifying microbial transfer from contaminated fomites to fingers after the use of disinfectant wipe intervention. The data generated in the present study can be used in quantitative microbial risk assessment models to predict the effect of disinfectant wipes in reducing microbial exposure.

scholarly journals The impact of aerosols on polarized sky radiance: model development, validation, and applications

2009 ◽  
Vol 9 (4) ◽  
pp. 17753-17791 ◽  
Author(s):  
C. Emde ◽  
R. Buras ◽  
B. Mayer ◽  
M. Blumthaler
Keyword(s):  
Monte Carlo ◽  
Polarization State ◽  
Model Development ◽  
Wavelength Region ◽  
High Sensitivity ◽  
Radiative Transfer Model ◽  
Degree Of Polarization ◽  
Transfer Model ◽  
Monte Carlo Code ◽  
The Impact

Abstract. Although solar radiation initially is unpolarized when entering the Earth's atmosphere, it is polarized by scattering processes with molecules, water droplets, ice crystals, and aerosols. Hence, measurements of the polarization state of radiation can be used to improve remote sensing of aerosols and clouds. The analysis of polarized radiance measurements requires an accurate radiative transfer model. To this end, a new efficient and flexible three-dimensional Monte Carlo code to compute polarized radiances has been developed and implemented into MYSTIC (Monte Carlo code for the phYSically correct Tracing of photons In Cloudy atmospheres). Unlike discrete ordinate methods the Monte Carlo approach allows to handle the scattering phase matrices of aerosol and cloud particles accurately, i.e. without any approximations except the inherent statistical noise. The study presented in this paper shows that this is important, especially in order to simulate scattering by aerosols and cloud droplets in the ultraviolet wavelength region. The commonly used Delta-M approximation may cause large errors not only in the calculated intensity but also in the degree of polarization. The polarized downwelling radiation field is calculated for various aerosol types showing the high sensitivity of polarized ultraviolet radiances to the particle microphysics. Model simulations are compared to ground based measurements and found to be generally in good agreement. This comparison shows that there is a high potential to retrieve information about the aerosol type from polarized radiance measurements.

scholarly journals Optimization of the PNG Law for a Dual-Spin Mortar with Fixed Canards

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Pengfei Liu ◽  
Hongsong Cao ◽  
Shunshan Feng ◽  
Hengzhu Liu ◽  
Lifei Cao
Keyword(s):  
Empirical Method ◽  
Impact Point ◽  
Gravity Compensation ◽  
Proportional Navigation ◽  
Squared Error ◽  
Intelligent Optimization Algorithm ◽  
The Mean ◽  
Optimization Schemes ◽  
The Impact ◽  
Selection Of

The limited instantaneous overload available and the curved trajectory lead to adaptivity problems for the proportional navigation guidance (PNG) of a guided mortar with a fixed-canard trajectory correction fuze. In this paper, the optimization of a PNG law with gravity compensation is established. Instead of using the traditional empirical method, the selection of the proportional navigation constants is formulated as an optimization problem, which is solved using an intelligent optimization algorithm. Two optimization schemes are proposed for constructing corresponding optimization models. In schemes 1 and 2, the sum squared error between the impact point and target and the circular error probability (CEP), respectively, are taken as the objective function. Monte Carlo simulations are conducted to verify the effectiveness of the two optimization schemes, and their guidance performance is compared through trajectory simulations. The simulation results show that the impact point dispersion can be efficiently reduced under both proposed schemes. Scheme 2 achieves a lower CEP, which is approximately 2.9 m and 2.4 times smaller than that achieved by scheme 1. Moreover, the mean impact point is closer to the target.

scholarly journals High-end climate change impact on European water availability and stress: exploring the presence of biases

2015 ◽  
Vol 12 (7) ◽  
pp. 7267-7325 ◽  
Author(s):  
L. V. Papadimitriou ◽  
A. G. Koutroulis ◽  
M. G. Grillakis ◽  
I. K. Tsanis
Keyword(s):  
Global Warming ◽  
Bias Correction ◽  
Climate Models ◽  
Climate Model ◽  
Water Cycle ◽  
Order Of Magnitude ◽  
Change Impact ◽  
The Mean ◽  
The Impact ◽  
Selection Of

Abstract. Climate models project a much more substantial warming than the 2 °C target making higher end scenarios increasingly plausible. Freshwater availability under such conditions is a key issue of concern. In this study, an ensemble of Euro-CORDEX projections under RCP8.5 is used to assess the mean and low hydrological states under +4 °C of global warming for the European region. Five major European catchments were analyzed in terms of future drought climatology and the impact of +2 vs. +4 °C global warming was investigated. The effect of bias correction of the climate model outputs and the observations used for this adjustment was also quantified. Projections indicate an intensification of the water cycle at higher levels of warming. Even for areas where the average state may not considerably be affected, low flows are expected to reduce leading to changes in the number of dry days and thus drought climatology. The identified increasing or decreasing runoff trends are substantially intensified when moving from the +2 to the +4 °C of global warming. Bias correction resulted in an improved representation of the historical hydrology. It is also found that the selection of the observational dataset for the application of the bias correction has an impact on the projected signal that could be of the same order of magnitude to the selection of the RCM.

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