The concept of block-effective macrodispersivity and a unified approach for grid-scale- and plume-scale-dependent transport

We present a new approach for modelling macrodispersivity in spatially variable velocity fields, such as exist in geologically heterogeneous formations. Considering a spectral representation of the velocity, it is recognized that numerical models usually capture low-wavenumber effects, while the large-wavenumber effects, associated with subgrid block variability, are suppressed. While this suppression is avoidable if the heterogeneity is captured at minute detail, that goal is impossible to achieve in all but the most trivial cases. Representing the effects of the suppressed variability in the models is made possible using the proposed concept of block-effective macrodispersivity. A tensor is developed, which we refer to as the block-effective macrodispersivity tensor, whose terms are functions of the characteristic length scales of heterogeneity, as well as the length scales of the model's homogenized areas, or numerical grid blocks. Closed-form expressions are developed for small variability in the log-conductivity and unidirectional mean flow, and are tested numerically. The use of the block-effective macrodispersivities allows conditioning of the velocity field on the measurements on the one hand, while accounting for the effects of unmodelled heterogeneity on the other, in a numerically reasonable set-up. It is shown that the effects of the grid scale are similar to those of the plume scale in terms of filtering out the effects of portions of the velocity spectrum. Hence it is easy to expand the concept of the block-effective dispersivity to account for the scale of the solute body and the pore-scale dispersion.

Download Full-text

Assessment of Radius of Investigation of Pressure Transient Analysis in Highly Heterogeneous Reservoirs

10.2118/206165-ms ◽

2021 ◽

Author(s):

Murat Zeybek ◽

Lei Jiang ◽

Hadrien Dumont

Keyword(s):

Transient Analysis ◽

Numerical Models ◽

Heterogeneous Systems ◽

Layered Systems ◽

Pressure Transient ◽

Heterogeneous Reservoirs ◽

Geological Features ◽

Heterogeneous Formations ◽

Set Up ◽

New Generation

Abstract The radius of investigation (ROI) of pressure transient analyses has been traditionally assessed using analytical formulations with basic reservoir parameters for homogenous systems. Numerous studies aimed to improve ROI formulations to incorporate all reservoir and testing parameters such as gauge resolution and rate for more accurate ROI assessments. However, new generation wireline formation testers aim to improve deep transient tests with significant developments in gauge resolution and increasing rate. Challenges still remain in heterogeneous formations such as shaly sands and carbonate reservoirs. In this study, detailed conceptual high-resolution numerical models are set up, including comprehensive reservoir and measurement parameters, to investigate more realistic ROI assessments in layered heterogeneous systems without and with hydraulic communication. Several conceptual examples are presented in layered systems with permeability contrasts. In addition, deviation from infinite-acting radial flow (IAFR) and pressure propagation in highly heterogeneous layered systems are investigated to detect the presence of geological features, including closed boundary systems and the presence of a fault in the proximity of wellbore.

Download Full-text

Few-Layer Graphene from Mechanical Exfoliation of Graphite-Based Materials: Structure-Dependent Characteristics

ChemEngineering ◽

10.3390/chemengineering3020037 ◽

2019 ◽

Vol 3 (2) ◽

pp. 37

Author(s):

Azhar Pirzado ◽

François Le Normand ◽

Thierry Romero ◽

Sandra Paszkiewicz ◽

Vasiliki Papaefthimiou ◽

...

Keyword(s):

Barrier Properties ◽

Nuclear Reaction Analysis ◽

Gas Barrier ◽

New Approach ◽

Elongation At Break ◽

Mechanical Exfoliation ◽

Layer Graphene ◽

Set Up ◽

The One ◽

Few Layer Graphene

We present a high-scale method to produce few-layer graphene (FLG) based on the mechanical exfoliation of graphite and compare the obtained FLG with the one reported earlier arising from pencil lead ablation. Several elements were modified and improved in the new approach. The purification and the ablation set-up were simplified, and the morphology of the FLG was modified and improved in view of some applications. The morphology-dependent properties of FLGs, lead-FLG, and graphite-FLG as conductive layers and in nanocomposites were investigated. The newly obtained FLG had a higher aspect ratio (high lateral size vs thickness/higher 2D aspect), which is reflected by enhanced transparency–conductivity features of the layer (film) and elongation-at-break behavior of the polymer composites. On the contrary, the nanocomposite containing lead-FLG showed, for instance, excellent gas barrier properties due to the multi-step structure of the lead-FLG flakes. Such structure exhibited less 2D and more 3D character, which can be highly suitable for applications where the presence of active/reactive edges is beneficial, e.g., in catalysis or supercapacitors’ electrodes. Nuclear reaction analysis was employed to investigate the morphology of graphite-FLG film.

Download Full-text

Constant deceleration approaches for penetration analysis of rigid projectile into concrete: Revisited

International Journal of Protective Structures ◽

10.1177/2041419620914646 ◽

2020 ◽

Vol 11 (4) ◽

pp. 515-532

Author(s):

David Z Yankelevsky ◽

Vladimir R Feldgun

Keyword(s):

Numerical Models ◽

Experimental Studies ◽

Theoretical Models ◽

New Approach ◽

Simplified Approach ◽

Strength Concrete ◽

One Stage ◽

Rigid Projectile ◽

Concrete Materials ◽

The One

A new approach of constant deceleration penetration into concrete targets has been presented recently. It is based on observations from two-dimensional numerical simulations of penetration into aluminum targets, showing a rather constant deceleration during the tunneling stage, which leads to conjecturing a general simple constant deceleration approach to represent constant resistance during penetration. This approach has been extended to concrete materials despite their entirely different behavior. This article reviews the one-stage constant deceleration approach and compares it with test data and with analytical and numerical models. This study clearly shows that concrete penetration cannot be presented by the proposed constant deceleration approach. The constant deceleration approach assigns constant deceleration to the projectile from its impact with the target and ignores the entrance stage. This study shows that a two-stage simplified approach shows superior results compared to the one-stage approach. Experimental studies with instrumented projectiles show that although at low-strength concrete the deceleration variation with time is moderate, its variation with time at higher strength concrete is significant. The variable deceleration–time records are confirmed by theoretical models using the material constitutive relationships. It has been found that the proposed constant deceleration is merely a calibration constant to the measured penetration depth and does not represent a physical deceleration of the penetrating projectile. It is concluded that there cannot exist a simplified approach with a constant deceleration or even an arbitrarily predefined another shape of the deceleration curve that may properly represent different penetration scenarios in concrete targets.

Download Full-text

Deployment automation of hydrological forecasting systems on a global scale.

10.5194/egusphere-egu21-3011 ◽

2021 ◽

Author(s):

Arianna Onate-Paladines ◽

Bart van Osnabrugge ◽

Jan Verkade ◽

Albrecht Weerts

Keyword(s):

Global Scale ◽

Weather Data ◽

Hydrological Models ◽

New Approach ◽

Weather Forecasts ◽

Hydrological Forecasting ◽

System Maintenance ◽

Set Up ◽

The One ◽

Main Components

Hydrological forecasting systems represent an important decision-making tool for water and risk management. In this context, there is increasing development and implementation of such systems worldwide, which are commonly tailor-made: designed and configured according to the information and hydrological models available for a specific location and/or extent to answer to precise needs. Therefore, the concepts of setup automation and replicability of configuration of such systems are often overlooked, especially when they follow a model-centric approach.However, in a global forecasting context such as the one adopted by Deltares&#8217; GLOFFIS (den Toom et al. 2020), the automation of hydrological forecasting systems&#8217; set up becomes an essential part for the development, as it enables the fast forward and constant addition of local specialized models where available in the system on a global extent, as well as by using local regional weather forecasts, reanalysis models or satellite data as forcing to produce estimates of various hydrological parameters, instead of focusing on a single model or NWP source.In that sense, a prototype of a configuration production system for GLOFFIS was developed, which comprises two main components: (1) an external relational database holding the information regarding the set of hydrological models to be incorporated and weather data products used and, (2) a set of python scripts, that query the database and generate the configuration XML files needed for the system (as GLOFFIS is based on Delft-FEWS) to accomplish an automated deployment.This new approach for system&#8217;s configuration boosts the potential related to system maintenance, expansion, and replicability, which could be beneficial not only when developing large hydrological forecasting systems, but also for local systems developed using Delft-FEWS, as well as to encourage the distribution of forecasting systems worldwide.&#160;References:den Toom, M., Verkade, J., Weerts, A., and Schotmeijer, G.-J.: Development of the Deltares global fluvial flood forecast system, EGU General Assembly 2020, Online, 4&#8211;8 May 2020, EGU2020-22344, https://doi.org/10.5194/egusphere-egu2020-22344, 2020.

Download Full-text

A new approach to bracket prediction in the NCAA Men’s Basketball Tournament based on a dual-proportion likelihood

Journal of Quantitative Analysis in Sports ◽

10.1515/jqas-2014-0047 ◽

2015 ◽

Vol 11 (1) ◽

Cited By ~ 2

Author(s):

Ajay Andrew Gupta

Keyword(s):

National Collegiate Athletic Association ◽

Expert Knowledge ◽

Probability Model ◽

Expected Value ◽

Division I ◽

Prediction System ◽

New Approach ◽

Men's Basketball ◽

Popular Interest ◽

The One

AbstractThe widespread proliferation of and interest in bracket pools that accompany the National Collegiate Athletic Association Division I Men’s Basketball Tournament have created a need to produce a set of predicted winners for each tournament game by people without expert knowledge of college basketball. Previous research has addressed bracket prediction to some degree, but not nearly on the level of the popular interest in the topic. This paper reviews relevant previous research, and then introduces a rating system for teams using game data from that season prior to the tournament. The ratings from this system are used within a novel, four-predictor probability model to produce sets of bracket predictions for each tournament from 2009 to 2014. This dual-proportion probability model is built around the constraint of two teams with a combined 100% probability of winning a given game. This paper also performs Monte Carlo simulation to investigate whether modifications are necessary from an expected value-based prediction system such as the one introduced in the paper, in order to have the maximum bracket score within a defined group. The findings are that selecting one high-probability “upset” team for one to three late rounds games is likely to outperform other strategies, including one with no modifications to the expected value, as long as the upset choice overlaps a large minority of competing brackets while leaving the bracket some distinguishing characteristics in late rounds.

Download Full-text

Telephone-based consultation in an acute eye clinic service: A patient satisfaction survey

European Journal of Ophthalmology ◽

10.1177/11206721211030774 ◽

2021 ◽

pp. 112067212110307

Author(s):

Julia Sieberer ◽

Patrick Hughes ◽

Indy Sian

Keyword(s):

Healthcare Professionals ◽

Medical Specialties ◽

New Approach ◽

High Satisfaction ◽

Negative Comments ◽

Patient Responses ◽

Set Up ◽

Strongly Agree ◽

The Impact ◽

Park Hospital

Objectives: The coronavirus pandemic has forced healthcare staff across all medical specialties to adapt new and different ways of working. A new approach has been set up in the Acute Referral Clinic (ARC) at Musgrove Park Hospital and a survey has been conducted to measure the impact of the new method on patient and healthcare professionals’ satisfaction with the new service. Methods: A telephone-based consultation was introduced in ARC at Musgrove Park Hospital in March 2020 and patients were instructed to fill out a questionnaire containing eight items using a Likert Scale 1 (‘very poor/disagree’) to 4 (‘very good/strongly agree’) plus two boxes for open positive and negative comments respectively. Likewise a questionnaire was designed in order to assess the healthcare professionals’ satisfaction using the new approach. Data collection took place over a two month period between the end of March 2020 and end of May 2020. The data underwent quality control and was analysed using descriptive statistics. Results: Patient responses illustrated high satisfaction scores with an overall rating of very good (89.4%). The healthcare professionals’ rating of the service was good (28.6% – ‘very good/strongly agree’, 57.1% – ‘good/agree’). The safety rating of the new approach was overall rated ‘very good’ with 90.4% and 71.4% of patients and healthcare professionals respectively. Conclusions: The telephone consultations introduced in the wake of COVID-19 are well accepted by both patients and doctors. There are some limitations of the approach, foremost being consultation time and clinic space but these do not outweigh the general benefit of this format amidst a pandemic setting.

Download Full-text

The Swiss National Park

Oryx ◽

10.1017/s0030605300038217 ◽

1955 ◽

Vol 3 (2) ◽

pp. 64-70

Author(s):

G. N. Zimmerli

Keyword(s):

National Park ◽

Swiss Society ◽

Large Area ◽

Nature Protection ◽

Swiss National Park ◽

Plant Life ◽

Eastern Border ◽

Set Up ◽

The One ◽

Protection Commission

The idea of a Swiss national park originated with the Swiss Society for Nature Research and this Society played the leading part in its realization. In 1906 the Society set up as part of its own organization a Swiss Nature Protection Commission and charged it to search for an area in Switzerland suitable for establishment as a reserve, in which all the animal and plant life could be protected against interference by man and so could be left entirely to the play of natural forces. It was not easy to find in Switzerland a suitably large area which still retained its original characteristics, was virtually free from human settlement, and contained some wealth of fauna and flora. After a careful survey of the whole country it became clear that the most suitable region was the Lower Engadine, with its isolated valleys on the eastern border of the country. The district in which, at the beginning of the century, bears had still lived was the one in which primitive nature could be found in its truest state.

Download Full-text

Leakage Flow Investigations on a Through-Wall Crack Related to Thermal Fatigue of Nuclear Power Plant Piping

Volume 6: Thermal-Hydraulics ◽

10.1115/icone25-67188 ◽

2017 ◽

Cited By ~ 1

Author(s):

Stefan Schmid ◽

Rudi Kulenovic ◽

Eckart Laurien

Keyword(s):

Experimental Data ◽

Nuclear Power ◽

Numerical Models ◽

Measurement Techniques ◽

Experimental Investigations ◽

Leakage Flow ◽

Test Rig ◽

Reduced Pressure ◽

Flow Rates ◽

Set Up

For the validation of empirical models to calculate leakage flow rates in through-wall cracks of piping, reliable experimental data are essential. In this context, the Leakage Flow (LF) test rig was built up at the IKE for measurements of leakage flow rates with reduced pressure (maximum 1 MPA) and temperature (maximum 170 °C) compared to real plant conditions. The design of the test rig enables experimental investigations of through-wall cracks with different geometries and orientations by means of circular blank sheets with integrated cracks which are installed in the tubular test section of the test rig. In the paper, the experimental LF set-up and used measurement techniques are explained in detail. Furthermore, first leakage flow measurement results for one through-wall crack geometry and different imposed fluid pressures at ambient temperature conditions are presented and discussed. As an additional aspect the experimental data are used for the determination of the flow resistance of the investigated leak channel. Finally, the experimental results are compared with numerical results of WinLeck calculations to prove specifically in WinLeck implemented numerical models.

Download Full-text

The origins and evolution of Cypriot glazed ware productions during the thirteenth to seventeenth centuries CE

Archaeological and Anthropological Sciences ◽

10.1007/s12520-020-01270-4 ◽

2021 ◽

Vol 13 (2) ◽

Author(s):

Carmen Ting ◽

Thilo Rehren ◽

Athanasios Vionis ◽

Vasiliki Kassianidou

Keyword(s):

Eastern Mediterranean ◽

Medieval Period ◽

Late Medieval ◽

New Approach ◽

Commercial Activities ◽

Late Medieval Period ◽

Thin Section Petrography ◽

Set Up ◽

Economic Developments ◽

Full Consideration

AbstractThis paper challenges the conventional characterisation of glazed ware productions in the eastern Mediterranean, especially the ones which did not feature the use of opaque or tin-glazed technology, as technologically stagnant and unsusceptible to broader socio-economic developments from the late medieval period onwards. Focusing on the Cypriot example, we devise a new approach that combines scientific analyses (thin-section petrography and SEM-EDS) and a full consideration of the chaîne opératoire in context to highlight the changes in technology and craft organisation of glazed ware productions concentrating in the Paphos, Famagusta and Lapithos region during the thirteenth to seventeenth centuries CE. Our results indicate that the Paphos production was short-lived, lasting from the establishment of Frankish rule in Cyprus in the thirteenth century to the aftermath of the fall of the Crusader campaigns in the fourteenth century. However, glazed ware production continued in Famagusta and Lapithos from the late thirteenth/fourteenth centuries through to the seventeenth century, using technical practices that were evidently different from the Paphos production. It is possible that these productions were set up to serve the new, local demands deriving from an intensification of commercial activities on the island. Further changes occurred to the technical practices of the Famagusta and Lapithos productions around the 16th/17th centuries, coinciding with the displacement of populations and socio-political organisation brought by the Ottoman rule.

Download Full-text