The Relevance of Fluid and Porous Media Properties for DNAPL Migration and Entrapment: A Numerical Evaluation of Laboratory Experiments

2020 ◽  
Author(s):  
Christian Engelmann ◽  
Kaveh Sookhak Lari ◽  
Marc Walther
Keyword(s):  
Porous Media ◽  
Chlorinated Solvents ◽  
Measurement Data ◽  
Size Fraction ◽  
Source Zone ◽  
Base Case ◽  
Contaminant Plume ◽  
Groundwater Abstraction ◽  
Case Scenario ◽  
Zone Formation

<p>A large number of sites worldwide are subjected to contamination by dense non-aqueous phase liquids (DNAPLs). This group of typically highly persistent chemicals arise tremendous threats to ecosystems and humankind, especially for groundwater abstraction and usage. In particular, chlorinated solvents have great risk profiles due to their toxic and carcinogenic properties, posing essential needs for appropriate risk assessment and site management strategies. Once released into the subsurface, DNAPLs form so-called source zone geometries (SZGs), i.e., physical shapes containing multiple phases, which represent long-term sources for contamination of downstream groundwater. The complex geometrical and chemical properties of such sources are, together with subsurface characteristics and hydraulic conditions of the aquifer, the most sensitive factors in controlling contaminant plume propagation. As locations of DNAPL sources are widely unknown and subsurface phase exploration methods are limited by technical and financial constraints, in most site assessments, dissolved contaminant plumes are detected only. This fact has led to numerous sites where remediation efforts have been inefficient or even failed, or exceeded economical pre-calculations. Here, improved knowledge on factors controlling source zone formation would lead to better predictions for corresponding SZGs and, therefore, better estimations of contaminant plume evolution and prediction.</p><p>A quasi-two-dimensional tank setup formed the basis for generating experimental measurement data of DNAPL migration and entrapment at a Darcy scale under defined laboratory conditions. Three different types of single-size fraction materials (glass beads, filtering glass, and natural sand) were used as homogeneous porous media. DNAPL release into the initially fully water-saturated tank was realized by means of a falling-head boundary condition. Both the aqueous and non-wetting phases were marked for better optical visibility using colorization tracers. All experimental scenarios were conducted under equal ambient conditions (e.g., constant temperature, homogeneous light source). Raw data collection was performed by serial image acquisition from one tank side. A set of customized image analysis and processing approaches was used for the automatized calculation of DNAPL saturation distributions, which served as experimental data for calibrating the base case model scenarios.</p><p>For each base case scenario, a representative numerical multiphase flow model was set up using the software codes TMVOC and OpenGeoSys. Starting parameters for calibration were selected based on the tank layout, technical data sheets and hydraulic characterization of the porous media. Each model setup was then run with a specified range of variation for each parameter after successful calibration, whereby parameter ranges were chosen to coincide with physically plausible values at laboratory scale. Through this semi-automatized parameter sensitivity analysis, controlling factors of source zone formation could be identified and ranked along their strength of impact on SZGs. Furthermore, the comparison between results of each software code could identify strengths and weaknesses of each one.</p>

scholarly journals Modelling and mitigating dose to firefighters from inhalation of radionuclides in wildland fire smoke

2015 ◽  
Vol 24 (5) ◽  
pp. 723 ◽  
Author(s):  
Brian J. Viner ◽  
Tim Jannik ◽  
Daniel Stone ◽  
Allan Hepworth ◽  
Luke Naeher ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Wildland Fire ◽  
Radioactive Material ◽  
Fuel Load ◽  
Base Case ◽  
Published Data ◽  
Case Scenario ◽  
Base Case Scenario ◽  
Fuel Loads ◽  
Radiological Dose

Firefighters responding to wildland fires where surface litter and vegetation contain radiological contamination will receive a radiological dose by inhaling resuspended radioactive material in the smoke. This may increase their lifetime risk of contracting certain types of cancer. Using published data, we modelled hypothetical radionuclide emissions, dispersion and dose for 70th and 97th percentile environmental conditions and for average and high fuel loads at the Savannah River Site. We predicted downwind concentration and potential dose to firefighters for radionuclides of interest (137Cs, 238Pu, 90Sr and 210Po). Predicted concentrations exceeded dose guidelines in the base case scenario emissions of 1.0 × 107 Bq ha–1 for 238Pu at 70th percentile environmental conditions and average fuel load levels for both 4- and 14-h shifts. Under 97th percentile environmental conditions and high fuel loads, dose guidelines were exceeded for several reported cases for 90Sr, 238Pu and 210Po. The potential for exceeding dose guidelines was mitigated by including plume rise (>2 m s–1) or moving a small distance from the fire owing to large concentration gradients near the edge of the fire. This approach can quickly estimate potential dose from airborne radionuclides in wildland fire and assist decision-making to reduce firefighter exposure.

scholarly journals Impact of changes in the methodology of external price referencing on medicine prices: discrete-event simulation

2020 ◽  
Author(s):  
Sabine Vogler ◽  
Peter Schneider ◽  
Lena Lepuschütz
Keyword(s):  
Cost Containment ◽  
Discrete Event ◽  
Real Life ◽  
Base Case ◽  
Case Scenario ◽  
Medicine Price ◽  
Base Case Scenario ◽  
The Real ◽  
Methodological Choices ◽  
Medicine Prices

Abstract Background: Several governments apply the policy of external price referencing (EPR), which considers the prices of a medicine in one or more other countries for the purpose of setting the price in the own country. Different methodological choices can be taken to design EPR. The study aimed to analyse whether, or not, and how changes in the methodology of EPR can impact medicine prices.Methods: The real-life EPR methodology as of Q1/2015 was surveyed in all European Union Member States (where applicable), Iceland, Norway and Switzerland through a questionnaire responded by national pricing authorities. Different scenarios were developed related to the parameters of the EPR methodology. Discrete-event simulations of fictitious prices in the 28 countries of the study that had EPR were run over 10 years. The continuation of the real-life EPR methodology in the countries as surveyed in 2015, without any change, served as base case.Results: In most scenarios, after ten years, medicine prices in all or most surveyed countries were – sometimes considerably – lower than in the base case scenario. But in a few scenarios medicine prices increased in some countries. Consideration of discounts (an assumed 20% discount in five large economies and the mandatory discount in Germany, Greece and Ireland) and determining the reference price based on the lowest price in the country basket would result in higher price reductions (on average -47.2% and -34.2% compared to the base case). An adjustment of medicine price data of the reference countries by purchasing power parities would lead to higher prices in some more affluent countries (e.g. Switzerland, Norway) and lower prices in lower-income economies (Bulgaria, Romania, Hungary, Poland). Regular price revisions and changes in the basket of reference countries would also impact medicine prices, however to a lesser extent.Conclusions: EPR has some potential for cost-containment. Medicine prices could be decreased if certain parameters of the EPR methodology were changed. If public payers aim to apply EPR to keep medicine prices at more affordable levels, they are encouraged to explore the cost-containment potential of this policy by taking appropriate methodological choices in the EPR design.

scholarly journals Skenario Pengembangan Untuk Meningkatkan Recovery Factor Pada Lapangan TR Lapisan X Dengan Menggunakan Simulasi Reservoir

PETRO ◽  
2018 ◽  
Vol 4 (4) ◽  
Author(s):  
Muhamad Taufan Azhari
Keyword(s):  
Reservoir Simulation ◽  
History Matching ◽  
Control Volume ◽  
Base Case ◽  
Case Scenario ◽  
Injection Wells ◽  
Base Case Scenario ◽  
Development Scenarios ◽  
Production Wells ◽  
Grid Construction

<p>Reservoir simulation is an area of reservoir engineering in which computer models are used to predict the flow of fluids through porous media. Reservoir simulation process starts with several steps; data preparation, model and grid construction, initialization, history matching and prediction. Initialization process is done for matching OOIP or total initial hydrocarbon which fill reservoir with hydrocarbon control volume with volumetric method.</p><p>To aim the best encouraging optimum data, these development scenarios of TR Field Layer X will be predicted for 30 years (from 2014 until January 2044). Development scenarios in this study consist of 4 scenarios : Scenario 1 (Base Case), Scenario 2 (Base Case + Reopening non-active wells), Scenario 3 (scenario 2 + infill production wells), Scenario 4 (Scenario 2 + 5 spot pattern of infill injection wells).</p>

Abstract T MP100: Improving Encounter Frequency, Physician Prescribing, or Patient Adherence - What Works Best for Controlling Blood Pressure? Results From a Validated Micro-Simulation Model

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Valy Fontil ◽  
Kirsten Bibbins-Domingo ◽  
Dhruv Kazi ◽  
Pamela Coxson ◽  
Steve Sidney ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Clinical Trial ◽  
Patient Adherence ◽  
The United States ◽  
Control Model ◽  
Uncontrolled Hypertension ◽  
Base Case ◽  
Treatment Intensification ◽  
Case Scenario ◽  
Base Case Scenario

Background: Only half of hypertensive adults achieve blood pressure (BP) control in the United States. Methods: We developed the BP Control Model to simulate physician- and patient-level processes relevant in achieving BP control. We validated the model by simulating the intervention arm of a recent multicenter clinical trial and used the validated model to examine the effects of isolated improvements in three modifiable processes on BP control. Data from national surveys, cohort studies, and trials were used to parameterize the model. We simulated 5,000 hypothetical adult patients with uncontrolled hypertension (systolic BP≥ 140) using probability sampling of participants from the 2009-2010 National Health and Nutrition Examination Survey. We modeled 50% improvements and ideal scenarios for each process parameter. Outcome: We reported outcomes in terms of BP control (% with SBP < 140 mmHg), and average change in BP at 52 weeks. Results: In our validation analysis, the model-predicted BP control was similar to what was achieved in the VIPER-BP clinical trial (63.5% vs. 63.8%). In our base case scenario, 24% of the NHANES-derived cohort achieved BP control at 52 weeks. In scenarios with 50% improvements, the model predicted small increases in BP control, but substantially larger and more variable effects when processes were idealized (Table). Control was reached in 77% with ideal treatment intensification, 44% with ideal encounter frequency, only 32% with ideal adherence, and 97% when all three processes were idealized. Conclusion: While improving patient adherence to medications would improve BP control, healthcare systems can achieve similar or greater success by focusing on increasing the frequency of clinical encounters and improving physicians’ prescribing behavior. The BP Control Model can be used to predict how much improvement to expect from such interventions.

Optimizing Strategies for Chlamydia trachomatis and Neisseria gonorrhoeae Screening in Men Who Have Sex With Men: A Modeling Study

2019 ◽  
Vol 70 (9) ◽  
pp. 1966-1972
Author(s):  
Nicolas Voirin ◽  
Camille Allam ◽  
Caroline Charre ◽  
Christine Fernandez ◽  
Matthieu Godinot ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Neisseria Gonorrhoeae ◽  
Screening Strategy ◽  
Unprotected Sex ◽  
Base Case ◽  
Case Scenario ◽  
Base Case Scenario ◽  
Systematic Screening ◽  
Ct Screening ◽  
Sex With Men

Abstract Background International guidelines recommend the systematic screening for Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) infections in all men who have sex with men (MSM) who have engaged in unprotected sex. However, the optimal screening strategy remains unclear. We developed a modeling approach to optimize NG/CT screening strategy in MSM. Methods A compartmental model of NG/CT screening and infection was implemented. NG/CT anal, pharyngeal, and urine (APU) samples from MSM attending the sexually transmitted infections clinic were used to estimate the screening rate, prevalence, and incidence in a base case scenario. Different screening strategies (scenarios; S) were then evaluated: APU samples every 12 months (S1); APU samples every 3 months (S2); APU samples every 6 months (S3); anal and pharyngeal (AP) samples every 6 months (S4); and AP samples every 3 months (S5). Results We analyzed 2973 triplet APU samples from 1255 patients. We observed 485 NG and 379 CT diagnoses. NG/CT prevalence and incidence estimates were 12.0/11.1% and 40/29 per 100 person-years, respectively, in the base case scenario. As compared to S2, the reference strategy, the proportions of missed NG/CT diagnoses were 42.0/41.2% with S1, 21.8/22.5% with S3, 25.6/28.3% with S4, and 6.3/10.5% with S5, respectively. As compared to S2, S1 reduced the cost of the analysis by 74%, S3 by 50%, S4 by 66%, and S5 by 33%. The numbers needed to screen for catching up the missed NG/CT diagnoses were 49/67 with S1, 62/82 with S3, 71/87 with S4, and 143/118 with S5. Conclusions S5 appears to be the best strategy, missing only 6.3/10.5% of NG/CT diagnoses, for a cost reduction of 33%.

scholarly journals Cost-effectiveness of a Contact Intervention and a Psychotherapeutic Program for Post-discharge Suicide Prevention: Rentabilité D’une Intervention de Contact et d’un Programme de Psychothérapie Pour la Prévention du Suicide Après le Congé de L’hôpital

2020 ◽  
pp. 070674372098013
Author(s):  
Gonzalo Martínez-Alés ◽  
José B. Cruz Rodríguez ◽  
Pablo Lázaro ◽  
Arce Domingo-Relloso ◽  
María Luisa Barrigón ◽  
...  
Keyword(s):  
Health Care ◽  
Cost Effectiveness ◽  
Suicide Prevention ◽  
Cost Effective ◽  
Cost Data ◽  
Base Case ◽  
Case Scenario ◽  
Post Discharge ◽  
Base Case Scenario ◽  
Augmentation Strategies

Objective: To determine the cost-effectiveness of 2 strategies for post-discharge suicide prevention, an Enhanced Contact intervention based on repeated in-person and telephone contacts, and an individual 2-month long problem-solving Psychotherapy program, in comparison to facilitated access to outpatient care following a suicide attempt. Methods: We conducted a cost-effectiveness analysis based on a decision tree between January and December 2019. Comparative effectiveness estimates were obtained from an observational study conducted between 2013 and 2017 in Madrid, Spain. Electronic health care records documented resource use (including extra-hospital emergency care, mortality, inpatient admission, and disability leave). Direct cost data were derived from Madrid’s official list of public health care prices. Indirect cost data were derived from Spain’s National Institute of Statistics. Results: Both augmentation strategies were more cost-effective than a single priority outpatient appointment considering reasonable thresholds of willingness to pay. Under the base-case scenario, Enhanced Contact and Psychotherapy incurred, respectively, €2,340 and 6,260 per averted attempt, compared to a single priority appointment. Deterministic and probabilistic sensitivity analyses showed both augmentation strategies to remain cost-effective under several scenarios. Enhanced Contact was slightly cost minimizing in comparison to Psychotherapy (base-case scenario: €−196 per averted attempt). Conclusions: Two post-discharge suicide prevention strategies based on Enhanced Contact and Psychotherapy were cost-effective in comparison to a single priority appointment. Increasing contacts between suicide attempters and mental health-care providers was slightly cost minimizing compared to psychotherapy.

scholarly journals Influence of aquifer and streambed heterogeneity on the distribution of groundwater discharge

2009 ◽  
Vol 13 (1) ◽  
pp. 69-77 ◽  
Author(s):  
E. Kalbus ◽  
C. Schmidt ◽  
J. W. Molson ◽  
F. Reinstorf ◽  
M. Schirmer
Keyword(s):  
Groundwater Flow ◽  
Transport Model ◽  
Regional Scale ◽  
Base Case ◽  
Case Scenario ◽  
Base Case Scenario ◽  
Heterogeneous Distribution ◽  
Heterogeneous Aquifer ◽  
The Impact ◽  
Low K

Abstract. The spatial distribution of groundwater fluxes through a streambed can be highly variable, most often resulting from a heterogeneous distribution of aquifer and streambed permeabilities along the flow pathways. Using a groundwater flow and heat transport model, we defined four scenarios of aquifer and streambed permeability distributions to simulate and assess the impact of subsurface heterogeneity on the distribution of groundwater fluxes through the streambed: (a) a homogeneous low-K streambed within a heterogeneous aquifer; (b) a heterogeneous streambed within a homogeneous aquifer; (c) a well connected heterogeneous low-K streambed within a heterogeneous aquifer; and (d) a poorly connected heterogeneous low-K streambed within a heterogeneous aquifer. The simulation results were compared with a base case scenario, in which the streambed had the same properties as the aquifer, and with observed data. The results indicated that the aquifer has a stronger influence on the distribution of groundwater fluxes through the streambed than the streambed itself. However, a homogeneous low-K streambed, a case often implemented in regional-scale groundwater flow models, resulted in a strong homogenization of fluxes, which may have important implications for the estimation of peak mass flows. The flux distributions simulated with heterogeneous low-K streambeds were similar to the flux distributions of the base case scenario, despite the lower permeability. The representation of heterogeneous distributions of aquifer and streambed properties in the model has been proven to be beneficial for the accuracy of flow simulations.

Fatigue Assessment of SLWR Riser in Brazilian Pre-Salt: The Impact of Slope Changing Point in SN Curve

2019 ◽  
Author(s):  
Stael F. Senra ◽  
Ludimar L. Aguiar ◽  
Eduardo Hippert ◽  
Alexandre G. Garmbis ◽  
Marcelo Dos Santos ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Limit State ◽  
Base Case ◽  
Load Spectrum ◽  
Internal Wall ◽  
Case Scenario ◽  
Fatigue Assessment ◽  
Variable Amplitude ◽  
Riser Design ◽  
The Impact

Abstract One of the main challenges in rigid riser design for Brazilian Pre-salt is the fatigue limit state. At this new production frontier, some key points are imposed as a challenge for riser designers, mainly due to the high level of motions imposed by the FPSO at the riser top in a coupled system with water depth around 2200 meters, and thicker riser’s thermal insulation demanded for flow assurance (which worsens the dynamic response of production risers). Additionally, high contaminant levels in the fluid (CO2 & H2S) demands CRA materials. Within this context, Petrobras has been considering Steel Lazy Wave Riser (SLWR) configuration as a base case scenario for rigid riser projects, since this configuration is able to absorb part of the FPSO motions that would reach the touch down zone (TDZ) and, consequently, making this region much less demanded when compared against Steel Catenary Risers (SCR). In its pioneer deepwater SLWR [1], Petrobras adopted a conservative approach for fatigue assessment that involved degenerated SN curves from DNV-RP-C203, i.e. D curve in cathodic protection with the slope changing point (SCP) shifted to 5 × 106 for external wall and F1 curve in air with SCP at 5 × 107 for internal wall. More recently, both DNVGL and BSI have reviewed their fatigue assessment codes and no longer holds parity between SN curves. BS-7608 Ed. 2014 introduced different SCPs in order to account for a possible non-conservativeness in the assessment of low stresses under variable amplitude in the loading spectra. DNVGL-RP-C203 Ed. 2016 now presents three different bilinear SN curves for the internal wall of pipelines and risers that depends on weld misalignment, while it keeps SCP unchanged. This paper presents a recent case study for a typical SLWR configuration in pre-salt, in order to evaluate the impact of the changes proposed by the new versions of these design codes in the fatigue life of riser girth welds. Results of this work showed that the impact of different positioning of slope changing points in SN curves can have a great importance for riser design, since typical load spectrum lies around this region. Fatigue life could be increased up to twice or three times if one of these codes are adopted instead of the Shifted SN curves. However, the effect of low stresses under variable amplitude loading spectra is still a concern and it should be further investigated.

scholarly journals An evaluation of public truck terminal implementation and truck ban policy in a medium-size city of Thailand: a case study of Khon Kaen city

2018 ◽  
Vol 192 ◽  
pp. 02060
Author(s):  
Vuchlung Chhorn ◽  
Jaruwit Prabnasak ◽  
Chow Chompoo-Inwai
Keyword(s):  
Medium Size ◽  
Base Case ◽  
Case Scenario ◽  
Base Case Scenario ◽  
Traffic Condition ◽  
The Public ◽  
Policy Adaptation ◽  
Network Cost ◽  
Step Model ◽  
Khon Kaen

This study aims at investigation the potential impacts of a public truck terminal implementation along with truck ban policy adaptation in Khon Kaen City, Thailand. A four-step model is developed and used for examining traffic condition changes due to the terminal relocation. Three different terminal locations are set. Truck traffic of each scenario are estimated and converted to total network cost, and then compared with the base-case scenario. The most suitable truck terminal location is suggested. Also, several concerns regarding the public truck terminal and truck ban policy in the study area are given.

Sign in / Sign up

Export Citation Format

Share Document