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Modelling, Volume 3, Issue 4 (December 2022) – 6 articles

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18 pages, 1683 KiB

Open AccessArticle

Empirical Modeling of Transverse Displacements of Single-Sided Transversely Cracked Prismatic Tension Beams

by Matjaž Skrinar

Modelling 2022, 3(4), 481-498; https://doi.org/10.3390/modelling3040031 - 16 Dec 2022

Viewed by 1229

Abstract

While the effects of axial compression on beams have long been known, the effect of tensile axial loads on one-sided transversely cracked beams is less known. The crack namely shifts the position of the resultant of the axial normal stresses deeper into the uncracked part of the cross-section, and the crack tends to open, causing a transverse displacement. Therefore, this paper focuses on empirical modeling of the considered phenomenon for slender prismatic beams in order to establish a suitable 1D computational model based on detailed 3D FE mesh results. This goal can be achieved through the already established simplified model, where the crack is represented by an internal hinge endowed with a rotational spring. Several analyses of various beams differing in geometry, crack locations, and boundary conditions were executed by implementing 3D FE meshes to establish the appropriate model’s bending governing differential equation. After that, the corresponding parameter definitions were calibrated from the database of 3D FE models. By redefining the model’s input parameters, a suitable solution is achieved, offering a good balance between the results’ accuracy and the required computational effort. The functionality of the newly obtained solutions was verified through some comparative case studies that supplement the derivations. Full article

(This article belongs to the Special Issue Modeling Dynamic Fracture of Materials)

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17 pages, 19684 KiB

Open AccessArticle

Efficient Hydrodynamic Modelling of Urban Stormwater Systems for Real-Time Applications

by Henry Baumann, Nanna Høegh Ravn and Alexander Schaum

Modelling 2022, 3(4), 464-480; https://doi.org/10.3390/modelling3040030 - 17 Nov 2022

Cited by 2 | Viewed by 2233

Abstract

Urban water drainage systems represent complex networks with nonlinear dynamics and different types of interactions. This yields an involved modeling problem for which different off-line simulation approaches are available. Nevertheless, these approaches cannot be used for real-time simulations, i.e., running in parallel to weather now- and forecasts and enabling the monitoring and automatic control of urban water drainage systems. Alternative approaches, used commonly for automation purposes, involve parameterized linear delay systems, which can be used in real-time but lack the necessary level of detail, which, in particular, is required for adequate flood risk prognostics. Given this setup, in the present paper, an approach for the effective modeling of detailed water drainage systems for real-time applications implemented with the open-source Storm Water Management Model (SWMM) software is addressed and exemplified for a part of the water drainage system of the city of Flensburg in northern Germany. Additionally, a freely available early-warning system prototype is introduced and used to combine weather forcast information on a 2-h prediction horizon with the developed model and available measurements. This prototype is subsequently used for data assimilation using the ensemble Kalman filter (EnKF) for the considered area in Flensburg. Full article

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19 pages, 951 KiB

Open AccessArticle

Mathematical Modeling of Electrical Circuits and Practical Works of Increasing Difficulty with Classical Spreadsheet Software

by Christophe Sauvey

Modelling 2022, 3(4), 445-463; https://doi.org/10.3390/modelling3040029 - 17 Nov 2022

Cited by 1 | Viewed by 2780

Abstract

This paper presents a modeling practical works project of electrical engineering, proposed to the first-year students of the University Institute of Technology in France, during the COVID-19 pandemic. The objective of this paper is twofold. The first objective is to present to the students the opportunities of modeling and calculation development of a spreadsheet software in their professional lives. The second objective is to create a file that automatically calculates all the current and voltage values at each point of any alternative electrical circuit. The aim of this paper, geared toward students, is to bring them to build their own numerical remote lab, autonomously. Therefore, pedagogical keys are given along the reading of this document to help them to progress, both on electrical circuits conceptual understanding with series and parallel RLC circuits and on their computation in a spreadsheet software. As a conclusion, this paper can be used as a base to develop remote modeling practical works of many and different devices, as well as a database starting point of such analytical models. Full article

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11 pages, 3619 KiB

Open AccessArticle

Numerical Analysis of the Radial Load, Pressure and Velocity Fields of a Single Blade Pump

by Dávid Bleho, Róbert Olšiak, Branislav Knížat and Marek Mlkvik

Modelling 2022, 3(4), 434-444; https://doi.org/10.3390/modelling3040028 - 25 Oct 2022

Viewed by 1898

Abstract

The centrifugal screw-type pump is a type of pump which, due to its hydraulic and mechanical properties, is used in several areas of the industry (e.g., for sludge and rainwater disposal). To avoid impeller passage clogging, the 3D impeller geometry is designed as a helically curved blade added to a conical hub. The passability through the fluid canal of the modelled impeller is 100 mm. In this paper, the magnitude of the radial force on an impeller blade is investigated as a function of the flow rate. The digital model was designed in Catia V5 and calculated using the commercial Ansys CFX software. A numerical computational fluid dynamics (CFD) method was used to investigate the performance characteristics of the pump, specifically discussing internal flow conditions such as velocity, pressure and the radial force mentioned above. Full article

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17 pages, 3380 KiB

Open AccessSystematic Review

Discrete-Event Simulation in Healthcare Settings: A Review

by John J. Forbus and Daniel Berleant

Modelling 2022, 3(4), 417-433; https://doi.org/10.3390/modelling3040027 - 14 Oct 2022

Cited by 11 | Viewed by 4183

Abstract

We review and define the current state of the art as relating to discrete event simulation in healthcare-related systems. A review of published literature over the past five years (2017–2021) was conducted, building upon previously published work. PubMed and EBSCOhost were searched for journal articles on discrete event simulation in healthcare resulting in identification of 933 unique articles. Of these about half were excluded at the title/abstract level and 154 at the full text level, leaving 311 papers to analyze. These were categorized, then analyzed by category and collectively to identify publication volume over time, disease focus, activity levels by country, software systems used, and sizes of healthcare unit under study. A total of 1196 articles were initially identified. This list was narrowed down to 311 for systematic review. Following the schema from prior systematic reviews, the articles fell into four broad categories: health care systems operations (HCSO), disease progression modeling (DPM), screening modeling (SM), and health behavior modeling (HBM). We found that discrete event simulation in healthcare has continued to increase year-over-year, as well as expand into diverse areas of the healthcare system. In addition, this study adds extra bibliometric dimensions to gain more insight into the details and nuances of how and where simulation is being used in healthcare. Full article

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17 pages, 5292 KiB

Open AccessArticle

Derivation of Cyclic Stiffness and Strength Degradation Curves of Sands through Discrete Element Modelling

by Fedor Maksimov and Alessandro Tombari

Modelling 2022, 3(4), 400-416; https://doi.org/10.3390/modelling3040026 - 30 Sep 2022

Cited by 3 | Viewed by 1982

Abstract

Cyclic degradation in fully saturated sands is a liquefaction phenomenon characterized by the progressive variation of the soil strength and stiffness that occurs when the soil is subjected to cyclic loading in undrained conditions. An evaluation of the relationships between the degradation of the soil properties and the number of loading cycles is essential for deriving advanced cyclic constitutive soil models. Generally, the calibration of cyclic damage models can be performed through controlled laboratory tests, such as cyclic triaxial testing. However, the undrained response of soils is dependent on several factors, such as the fabric, sample preparation, initial density, initial stress state, and stress path during loading; hence, a large number of tests would be required. On the other hand, the Discrete Element Method offers an interesting approach to simulating the complex behavior of an assembly of particles, which can be used to perform simulations of geotechnical laboratory testing. In this paper, numerical triaxial analyses of sands with different consistencies, loose and medium-dense states, were performed. First, static triaxial testing was performed to characterize the sand properties and validate the results with the literature data. Then, cyclic undrained triaxial testing was performed to investigate the impact of the number of cycles on the cyclic degradation of the soil stiffness and strength. Laws that can be used in damage soil models were derived. Full article

(This article belongs to the Section Modelling in Engineering Structures)

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