scholarly journals A standard test case suite for two-dimensional linear transport on the sphere: results from a collection of state-of-the-art schemes

2014 ◽  
Vol 7 (1) ◽  
pp. 105-145 ◽  
Author(s):  
P. H. Lauritzen ◽  
P. A. Ullrich ◽  
C. Jablonowski ◽  
P. A. Bosler ◽  
D. Calhoun ◽  
...  
Keyword(s):  
State Of The Art ◽  
Model Development ◽  
Finite Volume Methods ◽  
Standard Test ◽  
Ocean Modeling ◽  
Test Case ◽  
Linear Transport ◽  
Computing Platform ◽  
Wide Range ◽  
Cubed Sphere

Abstract. Recently, a standard test case suite for 2-D linear transport on the sphere was proposed to assess important aspects of accuracy in geophysical fluid dynamics with a "minimal" set of idealized model configurations/runs/diagnostics. Here we present results from 19 state-of-the-art transport scheme formulations based on finite-difference/finite-volume methods as well as emerging (in the context of atmospheric/oceanographic sciences) Galerkin methods. Discretization grids range from traditional regular latitude–longitude grids to more isotropic domain discretizations such as icosahedral and cubed-sphere tessellations of the sphere. The schemes are evaluated using a wide range of diagnostics in idealized flow environments. Accuracy is assessed in single- and two-tracer configurations using conventional error norms as well as novel diagnostics designed for climate and climate–chemistry applications. In addition, algorithmic considerations that may be important for computational efficiency are reported on. The latter is inevitably computing platform dependent. The ensemble of results from a wide variety of schemes presented here helps shed light on the ability of the test case suite diagnostics and flow settings to discriminate between algorithms and provide insights into accuracy in the context of global atmospheric/ocean modeling. A library of benchmark results is provided to facilitate scheme intercomparison and model development. Simple software and data sets are made available to facilitate the process of model evaluation and scheme intercomparison.

scholarly journals A standard test case suite for two-dimensional linear transport on the sphere: results from a collection of state-of-the-art schemes

2013 ◽  
Vol 6 (3) ◽  
pp. 4983-5076 ◽  
Author(s):  
P. H. Lauritzen ◽  
P. A. Ullrich ◽  
C. Jablonowski ◽  
P. A. Bosler ◽  
D. Calhoun ◽  
...  
Keyword(s):  
State Of The Art ◽  
Model Development ◽  
Finite Volume Methods ◽  
Standard Test ◽  
Ocean Modeling ◽  
Test Case ◽  
Linear Transport ◽  
Computing Platform ◽  
Wide Range ◽  
Cubed Sphere

Abstract. Recently, a standard test case suite for 2-D linear transport on the sphere was proposed to assess important aspects of accuracy in geophysical fluid dynamics with a "minimal" set of idealized model configurations/runs/diagnostics. Here we present results from 19 state-of-the-art transport scheme formulations based on finite-difference/finite-volume methods as well as emerging (in the context of atmospheric/oceanographic sciences) Galerkin methods. Discretization grids range from traditional regular latitude-longitude grids to more isotropic domain discretizations such as icosahedral and cubed-sphere tessellations of the sphere. The schemes are evaluated using a wide range of diagnostics in idealized flow environments. Accuracy is assessed in single- and two-tracer configurations using conventional error norms as well as novel diagnostics designed for climate and climate-chemistry applications. In addition, algorithmic considerations that may be important for computational efficiency are reported on. The latter is inevitably computing platform dependent, The ensemble of results from a wide variety of schemes presented here helps shed light on the ability of the test case suite diagnostics and flow settings to discriminate between algorithms and provide insights into accuracy in the context of global atmospheric/ocean modeling. A library of benchmark results is provided to facilitate scheme intercomparison and model development. Simple software and data-sets are made available to facilitate the process of model evaluation and scheme intercomparison.

scholarly journals A standard test case suite for two-dimensional linear transport on the sphere

2012 ◽  
Vol 5 (3) ◽  
pp. 887-901 ◽  
Author(s):  
P. H. Lauritzen ◽  
W. C. Skamarock ◽  
M. J. Prather ◽  
M. A. Taylor
Keyword(s):  
Initial Conditions ◽  
Model Development ◽  
Standard Test ◽  
Test Case ◽  
Two Dimensional ◽  
Wind Fields ◽  
True Solution ◽  
Functional Relations ◽  
Set Up ◽  
Cubed Sphere

Abstract. It is the purpose of this paper to propose a standard test case suite for two-dimensional transport schemes on the sphere intended to be used for model development and facilitating scheme intercomparison. The test cases are designed to assess important aspects of accuracy in geophysical fluid dynamics such as numerical order of convergence, "minimal" resolution, the ability of the transport scheme to preserve filaments, transport "rough" distributions, and to preserve pre-existing functional relations between species/tracers under challenging flow conditions. The experiments are designed to be easy to set up. They are specified in terms of two analytical wind fields (one non-divergent and one divergent) and four analytical initial conditions (varying from smooth to discontinuous). Both conventional error norms as well as novel mixing and filament preservation diagnostics are used that are easy to implement. The experiments pose different challenges for the range of transport approaches from Lagrangian to Eulerian. The mixing and filament preservation diagnostics do not require an analytical/reference solution, which is in contrast to standard error norms where a "true" solution is needed. Results using the CSLAM (Conservative Semi-Lagrangian Multi-tracer) scheme on the cubed-sphere are presented for reference and illustrative purposes.

scholarly journals A standard test case suite for two-dimensional linear transport on the sphere

2012 ◽  
Vol 5 (1) ◽  
pp. 189-228 ◽  
Author(s):  
P. H. Lauritzen ◽  
W. C. Skamarock ◽  
M. J. Prather ◽  
M. A. Taylor
Keyword(s):  
Initial Conditions ◽  
Model Development ◽  
Standard Test ◽  
Test Case ◽  
Two Dimensional ◽  
Wind Fields ◽  
True Solution ◽  
Functional Relations ◽  
Set Up ◽  
Cubed Sphere

Abstract. It is the purpose of this paper to propose a standard test case suite for two-dimensional transport schemes on the sphere intended to be used for model development and facilitating scheme intercomparison. The test cases are designed to assess important aspects of accuracy in geophysical fluid dynamics such as numerical order of convergence, "minimal" resolution, the ability of the transport scheme to preserve filaments, transport "rough" distributions, and to preserve pre-existing functional relations between species/tracers under challenging flow conditions. The experiments are designed to be easy to set up. They are specified in terms of two analytical wind fields (one non-divergent and one divergent) and four analytical initial conditions (varying from smooth to discontinuous). Both conventional error norms as well as novel mixing and filament preservation diagnostics are used that are easy to implement. The experiments pose different challenges for the range of transport approaches from Lagrangian to Eulerian. The mixing and filament preservation diagnostics do not require an analytical/reference solution which is in contrast to standard error norms where a "true" solution is needed. Results using the CSLAM (Conservative Semi-Lagrangian Multi-tracer) scheme on the cubed-sphere are presented for reference and illustrative purposes.

CO Prediction in LES of Turbulent Flames With Additional Modeling of the Chemical Source Term

2012 ◽  
Author(s):  
Anja Ketelheun ◽  
Kai Aschmoneit ◽  
Johannes Janicka
Keyword(s):  
Combustion Products ◽  
Standard Test ◽  
Turbulent Flames ◽  
Test Case ◽  
Eddy Simulation ◽  
Tabulated Chemistry ◽  
Wide Range ◽  
Large Eddy ◽  
Combustion Processes ◽  
Fast Chemical

The prediction of combustion processes using Large Eddy Simulation (LES) combined with tabulated chemistry has proven to be very successful and become very popular during the last years in both academia and industry. Technical combustion systems feature a wide range of time and length scales which need to be resolved. The LES describes the rather slow, but turbulent and unsteady flow field very well, while the fast chemical reactions can be represented by tabulated chemistry models like Flamelet Generated Manifolds. Pollutants, being only present at lower concentrations and developing slowly are not easy to capture with the standard manifold defined by the fast major combustion products. Therefore, additional modeling in order to predict the carbon monoxide emissions is presented in this paper. The choice of the reaction progress variable and the solution of an additional transport equation with and without extra modeling for the post flame zone was investigated. These models are applied to a standard test case and compared to experimental data and the standard tabulation approach.

CLINICAL AND FORENSIC ASPECTS OF PHARMACOBEZOARS

2020 ◽  
Vol 12 ◽  
Author(s):  
Francisco Basílio ◽  
Ricardo Jorge Dinis-Oliveira
Keyword(s):  
State Of The Art ◽  
Signs And Symptoms ◽  
Immediate Release ◽  
Diagnosis And Treatment ◽  
Blood Concentrations ◽  
Forensic Practice ◽  
Wide Range ◽  
Therapeutic Doses ◽  
Complete History ◽  
Lethal Blood

Background: Pharmacobezoars are specific types of bezoars formed when medicines, such as tablets, suspensions, and/or drug delivery systems, aggregate and may cause death by occluding airways with tenacious material or by eluting drugs resulting in toxic or lethal blood concentrations. Objective: This work aims to fully review the state-of-the-art regarding pathophysiology, diagnosis, treatment and other relevant clinical and forensic features of pharmacobezoars. Results: patients of a wide range of ages and in both sexes present with signs and symptoms of intoxications or more commonly gastrointestinal obstructions. The exact mechanisms of pharmacobezoar formation are unknown but is likely multifactorial. The diagnosis and treatment depend on the gastrointestinal segment affected and should be personalized to the medication and the underlying factor. A good and complete history, physical examination, image tests, upper endoscopy and surgery through laparotomy of the lower tract are useful for diagnosis and treatment. Conclusion: Pharmacobezoars are rarely seen in clinical and forensic practice. They are related to controlled or immediate-release formulations, liquid or non-digestible substances, in normal or altered digestive motility/anatomy tract, and in overdoses or therapeutic doses, and should be suspected in the presence of risk factors or patients taking drugs which may form pharmacobezoars.

Computers in Geology - 25 Years of Progress

1994 ◽  
Keyword(s):  
Computer Modeling ◽  
Quantitative Methods ◽  
State Of The Art ◽  
International Association ◽  
Mathematical Geology ◽  
25Th Anniversary ◽  
The Earth ◽  
Wide Range ◽  
History Of ◽  
Mapping Techniques

This volume vividly demonstrates the importance and increasing breadth of quantitative methods in the earth sciences. With contributions from an international cast of leading practitioners, chapters cover a wide range of state-of-the-art methods and applications, including computer modeling and mapping techniques. Many chapters also contain reviews and extensive bibliographies which serve to make this an invaluable introduction to the entire field. In addition to its detailed presentations, the book includes chapters on the history of geomathematics and on R.G.V. Eigen, the "father" of mathematical geology. Written to commemorate the 25th anniversary of the International Association for Mathematical Geology, the book will be sought after by both practitioners and researchers in all branches of geology.

scholarly journals Clinically applicable artificial intelligence system for dental diagnosis with CBCT

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matvey Ezhov ◽  
Maxim Gusarev ◽  
Maria Golitsyna ◽  
Julian M. Yates ◽  
Evgeny Kushnerev ◽  
...  
Keyword(s):  
State Of The Art ◽  
Model Development ◽  
Clinical Effectiveness ◽  
Anatomical Landmarks ◽  
Periapical Lesion ◽  
Artificial Intelligence System ◽  
Intelligence System ◽  
Significant Difference ◽  
Diagnostic Capabilities ◽  
Lesion Localization

AbstractIn this study, a novel AI system based on deep learning methods was evaluated to determine its real-time performance of CBCT imaging diagnosis of anatomical landmarks, pathologies, clinical effectiveness, and safety when used by dentists in a clinical setting. The system consists of 5 modules: ROI-localization-module (segmentation of teeth and jaws), tooth-localization and numeration-module, periodontitis-module, caries-localization-module, and periapical-lesion-localization-module. These modules use CNN based on state-of-the-art architectures. In total, 1346 CBCT scans were used to train the modules. After annotation and model development, the AI system was tested for diagnostic capabilities of the Diagnocat AI system. 24 dentists participated in the clinical evaluation of the system. 30 CBCT scans were examined by two groups of dentists, where one group was aided by Diagnocat and the other was unaided. The results for the overall sensitivity and specificity for aided and unaided groups were calculated as an aggregate of all conditions. The sensitivity values for aided and unaided groups were 0.8537 and 0.7672 while specificity was 0.9672 and 0.9616 respectively. There was a statistically significant difference between the groups (p = 0.032). This study showed that the proposed AI system significantly improved the diagnostic capabilities of dentists.

Report on CLEF 2019

2019 ◽  
Vol 53 (2) ◽  
pp. 108-118
Author(s):  
Martin Braschler ◽  
Linda Cappellato ◽  
Fabio Crestani ◽  
Nicola Ferro ◽  
Gundula Heinatz Bürki ◽  
...  
Keyword(s):  
Standard Test ◽  
Future Perspectives ◽  
Research Papers ◽  
Test Collections ◽  
Lessons Learnt ◽  
Wide Range ◽  
The Future ◽  
20Th Anniversary

This is a report on the tenth edition of the Conference and Labs of the Evaluation Forum (CLEF 2019), held from September 9--12, 2019, in Lugano, Switzerland. CLEF was a four day event combining a Conference and an Evaluation Forum. The Conference featured keynotes by Bruce Croft, Yair Neuman, and Miguel Martínez, and presentation of peer reviewed research papers covering a wide range of topics in addition to many posters. The Evaluation Forum consisted to nine Labs: CENTRE, CheckThat, eHealth, eRisk, ImageCLEF, LifeCLEF, PAN, PIR-CLEF, and ProtestNews, addressing a wide range of tasks, media, languages, and ways to go beyond standard test collections. CLEF 2019 marked the 20th anniversary of CLEF, which was celebrated with a dedicated session and a book on the lessons learnt in twenty years of evaluation activities and the future perspectives for CLEF. CLEF 2019 also introduced the Industry Days to further extend the reach and impact of CLEF.

scholarly journals Density Guarantee on Finding Multiple Subgraphs and Subtensors

2021 ◽  
Vol 15 (5) ◽  
pp. 1-32
Author(s):  
Quang-huy Duong ◽  
Heri Ramampiaro ◽  
Kjetil Nørvåg ◽  
Thu-lan Dam
Keyword(s):  
Lower Bound ◽  
State Of The Art ◽  
The State ◽  
The Other ◽  
Exact Methods ◽  
Practical Solution ◽  
Novel Approach ◽  
Wide Range ◽  
Real World Datasets ◽  
Tensor Data

Dense subregion (subgraph & subtensor) detection is a well-studied area, with a wide range of applications, and numerous efficient approaches and algorithms have been proposed. Approximation approaches are commonly used for detecting dense subregions due to the complexity of the exact methods. Existing algorithms are generally efficient for dense subtensor and subgraph detection, and can perform well in many applications. However, most of the existing works utilize the state-or-the-art greedy 2-approximation algorithm to capably provide solutions with a loose theoretical density guarantee. The main drawback of most of these algorithms is that they can estimate only one subtensor, or subgraph, at a time, with a low guarantee on its density. While some methods can, on the other hand, estimate multiple subtensors, they can give a guarantee on the density with respect to the input tensor for the first estimated subsensor only. We address these drawbacks by providing both theoretical and practical solution for estimating multiple dense subtensors in tensor data and giving a higher lower bound of the density. In particular, we guarantee and prove a higher bound of the lower-bound density of the estimated subgraph and subtensors. We also propose a novel approach to show that there are multiple dense subtensors with a guarantee on its density that is greater than the lower bound used in the state-of-the-art algorithms. We evaluate our approach with extensive experiments on several real-world datasets, which demonstrates its efficiency and feasibility.

Semi-Lagrangian exponential time-integration method for the shallow water equations on the cubed sphere grid

2020 ◽  
Vol 35 (6) ◽  
pp. 355-366
Author(s):  
Vladimir V. Shashkin ◽  
Gordey S. Goyman
Keyword(s):  
Shallow Water ◽  
Gravity Waves ◽  
Shallow Water Equations ◽  
Time Integration ◽  
Standard Test ◽  
Integration Scheme ◽  
Test Problems ◽  
Cubed Sphere ◽  
Lagrangian Scheme ◽  
Inertia Gravity Waves

AbstractThis paper proposes the combination of matrix exponential method with the semi-Lagrangian approach for the time integration of shallow water equations on the sphere. The second order accuracy of the developed scheme is shown. Exponential semi-Lagrangian scheme in the combination with spatial approximation on the cubed-sphere grid is verified using the standard test problems for shallow water models. The developed scheme is as good as the conventional semi-implicit semi-Lagrangian scheme in accuracy of slowly varying flow component reproduction and significantly better in the reproduction of the fast inertia-gravity waves. The accuracy of inertia-gravity waves reproduction is close to that of the explicit time-integration scheme. The computational efficiency of the proposed exponential semi-Lagrangian scheme is somewhat lower than the efficiency of semi-implicit semi-Lagrangian scheme, but significantly higher than the efficiency of explicit, semi-implicit, and exponential Eulerian schemes.

Sign in / Sign up

Export Citation Format

Share Document