Use Of Physical Models Research Articles

Real-time Wells turbine simulation on an oscillating-water-column wave energy converter physical model

Due to its simplicity and low cost, the Wells turbine is the most common choice for driving oscillating-water-column (OWC) wave energy converters (WECs) power take-off system. This turbine is characterized by a flow rate that is a linear function of the pressure head and inversely proportional to the rotational speed before the onset of hard stall conditions. The Wells turbine has been simulated in wave tanks using porous plugs, where the flow rate exhibits linear behaviour. However, numerical and experimental results have shown that rotational speed variations significantly influence the performance of OWC WECs. This work aims to develop a novel real-time simulator of a Wells turbine for use in physical models of OWC power plants. The proposed simulator consists of a diaphragm whose diameter is adjusted in real-time as a function of the pressure head measured in the laboratory and the rotational speed calculated by a hardware-in-the-loop model. In this way, it is possible to reproduce the full behaviour of the Wells turbine before and after a hard stall. Experimental results demonstrate the effectiveness of the simulator. A performance analysis was conducted to understand the device’s potential and compare the damping that Wells and impulse turbines introduce.

Evaluating scanning electron microscopy for the measurement of small-scale topography

For predicting surface performance, multiscale topography analysis consistently outperforms standard roughness metrics; however, surface-characterization tools limit the range of sizes that can be measured. Therefore, we evaluate the use of scanning electron microscopy (SEM) to systematically measure small-scale topography. While others have employed SEM for similar purposes, the novelty of this investigation lies in the development and validation of a simple, flexible procedure that can be applied to a wide range of materials and geometries. First, we established four different options that can be used for sample preparation, and we measured quantitative topography of each using the SEM. Then the power spectral density (PSD) was used to compare topography among the four preparations, and against other techniques. A statistical comparison of PSDs demonstrated that SEM topography measurements outperformed AFM measurements at scales below 100 nm and were statistically indistinguishable from (highly labor-intensive) TEM measurements down to 16 nm. The limitations of SEM-based topography were quantified and discussed. Overall, the results show a simple generalizable method for revealing small-scale topography. When combined with traditional stylus profilometry, this technique characterizes surface topography across almost seven orders of magnitude, from 1 cm down to 16 nm, facilitating the use of physical models to predict performance.

MODELING OF GROUND WATER DYNAMICS AND ITS POLLUTION

Problem statement. Large accumulators of liquid waste (e.g., mine water ponds, tailing ponds, etc.) are long-term sources that change the hydrological regime. A negative consequence of this process is flooding of the territory. In addition, the infiltration of contaminated water from such hazardous sources changes the quality of groundwater. Therefore, it is important to analyze the impact of such anthropogenic sources on the process of flooding and deterioration of groundwater quality. To solve this problem, it is very important to use the method of mathematical modeling as an effective mean of researching problems of this class, since the use of physical modeling is practically impossible within the scope of problems of this class. The purpose of the article. Development of numerical models for predicting changes in the hydrological regime (flooding of the territory) and groundwater quality under the influence of anthropogenic pollution sources. Methodology. To assess the dynamics of changes in the hydrological regime, a two-dimensional equation of filtration of a non-pressure groundwater flow is used. A two-dimensional geomigration equation (planned model) is used to analyze changes in groundwater quality during infiltration of contaminated water from the settling pond. This equation takes into account the convective transfer of contaminants in the filtration flow, dispersion, and the intensity of contaminant infiltration into the groundwater flow. The method of total approximation is used for numerical integration of the filtration equation. For the numerical integration of the geomigration equation, an implicit splitting scheme is used. Scientific novelty. Effective numerical models for rapid assessment of changes in groundwater dynamics and quality under the influence of anthropogenic sources that change the hydrological regime are proposed. The constructed numerical models take into account a set of important physical factors that affect the process of geomigration and flooding of the territory, namely: filtration coefficient, variable depth of free-flowing groundwater, dispersion, intensity of the source of impurity emission into the groundwater flow. This makes it possible to obtain a comprehensive assessment of the process of flooding and groundwater pollution.. Practical significance. A computer code has been created that allows practical usage of the developed numerical models. This code is an effective tool for theoretical study of non-stationary processes of territory flooding and anthropogenic groundwater pollution. Conclusions. A numerical model for calculating groundwater dynamics has been developed. The model allows to predict the level of groundwater rise under the influence of a man-made source of wastewater infiltration from a settling pond. A numerical model for calculating the process of geomigration from an anthropogenic source of emissions has been developed. The model makes it possible to predict the dynamics of contamination zone formation in a non-pressure groundwater flow. The developed numerical models take into account the most important parameters that affect the formation of flooding zones and groundwater contamination.

Temperature Prediction of a Temperature-Controlled Container with Cold Energy Storage System Based on Long Short-Term Memory Neural Network

Temperature prediction is important for controlling the environment in the preservation of fresh products. The phase change materials for cold storage make the heat transfer process complex, and the use of physical models for characterization and temperature prediction can be challenging. In order to predict the variation of the thermal environment in a temperature-controlled container with a cold energy storage system, we propose an LSTM model based on historical temperature data in which the trends of temperature variations of the fresh-keeping area, the phase change material (PCM), and the fresh products can be predicted immediately without considering the complex heat transfer process. An experimental platform of a temperature-controlled container with a cold energy storage system is built to obtain the experimental data for the prediction model’s construction and validation. The prediction results based on the LSTM model are compared to the results of a physical model. In order to optimize the input data for better prediction performance, the proportion of input samples from the dataset is set to 80%, 50%, 20%, and 10%. The prediction results from different input groups are compared and analyzed. The results show that the LSTM model is able to accurately predict temperature variations of the fresh-keeping area and products, and the predicted values are in agreement with the actual values. The LSTM-based prediction model has a higher accuracy compared to the physical-based prediction model; the RMSE, MAE, and MAPE are 0.105, 0.103, and 0.010, respectively, and the relative error for the prediction of effective control hours of environmental temperature is 0.92%. It is suggested to use the initial 20% of the historical temperature data as the input to predict the future temperature variation for better prediction performance. The results of this paper offer valuable insights for accurate temperature prediction in the fresh-keeping environment with a cold energy storage system.

Automated system of monitoring professional skills development of food production operators based on a computer simulator

Research is devoted to the development of a computer simulator complex (CSC) to develop the professional skills of food production operators. The structure (conceptual model) of CSC for training of food production operators is developed, the distinctive features of which for solving the problem of professional training of operators is the integration of the simulator, which allows to reproduce real technological processes of food production for training purposes, with the automated information system (AIS) of control over the formation of professional skills in the course of exercise courses on CSC. The sets of parameters that determine: the structure and properties of the technological operation modeled in the exercise on CSC for the generation of individual exercise variants; the actions performed by the trainee in the exercise depending on the features of the simulated technological operation with the use of physical models of real equipment or elements of virtual and augmented reality (VR/AR); evaluation of the process and results of the exercise in the virtual automated training environment CSC are described. The application of CSC in the training process allows to flexibly customize exercises for professional training of operators of different branches of food industry (meat, dairy, bakery, confectionery, etc.), which helps to improve the quality of training results, as well as to reduce the labor intensity of creating and controlling the implementation of training courses in CSC by operators.

Estimation of efficiency of technical solutions of an active road train by means of physical modelling

Introduction (problem statement and relevance). The article describes a physical model of a road train with active drive of semi-trailer wheels. The results of research tests of the physical model are given, with the help of which the adequacy of the mathematical models of dynamics of the road train as a part of a truck tractor and semi-trailer with active wheel drive is evaluated. The purpose of the study is estimation of efficiency of the technical solutions aimed at increase of vehicle passability and maneuverability.Methodology and research methods. In the course of the study the method of analysis of results of tests of the operating active road train scaled mock-up, the method of comparative analysis of the results of mathematical and physical modelling have been used. Scientific novelty and results. The performed studies confirmed correlation of the physical and mathematical modelling results, as well as indicated that the use of physical modelling serves as an efficient method to obtain an objective assessment of operational properties of the designed road train. The article considers constraints and limitations of using a scalable vehicle to study its dynamics. Matters of model parameters validity, conditions for dynamic similarity, and physical modelling results for active road train dynamics are given.Practical significance. Physical modelling of a (full-)scale sample using a scaled model reduces the costs and time when developing an active road train with new technical solutions, and increases reliability of the results obtained through the mathematical and physical modelling.

Physical modeling and numerical investigation of fluid flow and solidification behavior in a slab caster mold using hexa‐furcated nozzle

AbstractSlag entrapment from metal–slag interface during continuous casting operations has been a major area of concern for steelmakers globally. The presence of inactive regions in the upper region of the mold poses another challenge. Proper flow behavior of the molten metal coming out of the nozzle in the mold is required to overcome these challenges. Nozzle design greatly affects the flow pattern of the molten steel inside the mold. The present investigation is an attempt to study the flow and solidification behavior in a slab caster mold with the use of a novel‐designed hexa‐furcated nozzle using numerical investigation results. The casting speed and submerged entry nozzle (SEN) depth are varied to study the effect of these parameters on minimizing the inactive zones in the mold and the steel/slag interface fluctuations. The results show that the interface fluctuation increases at higher casting speed and lower SEN depth. The residence time distribution (RTD) analysis was also performed for different cases to investigate the flow behavior. The validation of the fluid flow and RTD curve inside the computational domain is carried out with the use of physical modeling.

An Error Estimation System for Close-Range Photogrammetric Systems and Algorithms.

Close-range photogrammetry methods are widely used for non-contact and accurate measurements of surface shapes. These methods are based on calculating the three-dimensional coordinates of an object from two-dimensional images using special digital processing algorithms. Due to the relatively complex measurement principle, the accurate estimation of the photogrammetric measurement error is a non-trivial task. Typically, theoretical estimations or computer modelling are used to solve this problem. However, these approaches cannot provide an accurate estimate because it is impossible to consider all factors that influence the measurement results. To solve this problem, we propose the use of physical modelling. The measurement results from the photogrammetric system under test were compared with the results of a more accurate reference measurement method. This comparison allowed the error to be estimated under controlled conditions. The test object was a flexible surface whose shape could vary smoothly over a wide range. The estimation of the measurement accuracy for a large number of different surface shapes allows us to obtain new results that are difficult to obtain using standard approaches. To implement the proposed approach, a laboratory system for the error estimation of close-range photogrammetric measurements was developed. The paper contains a detailed description of the developed system and the proposed technique for a comparison of the measurement results. The error in the reference method, which was chosen to be phasogrammetry, was evaluated experimentally. Experimental testing of the stereo photogrammetric system was performed according to the proposed technique. The obtained results show that the proposed technique can reveal dependencies that may not be detected by standard approaches.

Movement of Water on The Soil: Teaching by the Use of Physical Models

Dams, embankments, roads, and other structures are subject to stress changes due to pore pressure, which can lead to instability and even failure. Considering the need to understand the processes that act on these structures and the difficulty often encountered by students in visualizing the action of water and its movement in the soil, this paper aims to present the practical activities developed in the Soil Mechanics Department of the Civil Engineering Course of the State University of Minas Gerais - João Monlevade, Brazil, which dealt with the movement of water in soil structures and discussed the design and stability aspects of these. One of objectives was to develop the student's protagonism through direct involvement in the design and execution of the physical model of earth and tailing dams. This topic is crucial for geotechnical engineering and even more so for the region where João Monlevade is located, as several iron mining companies use tailings dams and earth structures. The execution of the model by the students was preceded by theoretical discussions on aspects such as the Darcy´s law, hydraulic head, the types and characterization of soil and tailings, pore pressure and your influence of the safety factor. These activities were developed in 2018, 2019, 2022 and 2023. As a result, a learning gain was achieved because the models were developed on a small scale by the students, who personally checked the variation of the parameters of the materials and water in the experiments.

Geotechnical variability: in the ground and throughout a career

This paper presents three aspects of geotechnical engineering research that have been conducted throughout the author’s career and concludes with a brief treatment of the use of physical models in teaching. The first research topic deals with quantifying the large-scale spatial variability of the Keswick Clay in Adelaide by means of undrained shear strength data acquired from several private consulting companies and government departments, incorporating a large number of site investigations. The mathematical technique of geostatistics is used, and it is observed that kriging with a spherical model, with a range of influence of 1000 m, a nugget of 1500 kPa2, and a sill of 2500 kPa2, is able to generate good estimates of the undrained shear strength of the Keswick Clay that can be used for preliminary design purposes. Secondly, the ground improvement technique of rolling dynamic compaction (RDC) is examined in the field and in the laboratory, and numerically by means of artificial neural networks (ANNs). It is observed that RDC is able to improve the ground to depths in excess of 3 m, and the use of transparent soils in the laboratory provides useful insights regarding the influence of RDC on the subsurface profile. In addition, ANNs facilitate the development of reliable models for the prediction of the level of ground improvement due to RDC. The third and final research topic presented involves ground improvement on the Moon. It is a work-in-progress, and early results are presented in this fascinating and exciting endeavour. The paper concludes with a brief treatment of the use of three different physical models used in teaching. It is observed that incorporating demonstrations involving physical models in teaching is helpful for enhancing student learning and engagement.

Development of digital twin model for mechanical application

The notion of digital twin technology is one that is just starting to gain traction in industry or business and more recently, academia. A virtual depiction of a real process or thing is called a “digital twin.” that may gather data from the real environment in order to represent, validate and simulate the physical twins. For artificial intelligence, the internet of things (IoT), and digital twins, the problems, applications, and enabling technologies are discussed. Particularly in the industrial sector, the development of Industry 4.0 principles has aided in its expansion. In order to adapt the idea to production. It is simulation technology that, by making full use of physical models, sensor data, and operation histories, blends interdisciplinary, multi-physical quantity, multiscale, and multi-probability. Utilizing cutting-edge analytical, monitoring, and predictive capabilities to test digital twin processes and services. It eliminates the expensive failure of physical items. It is a crucial facilitator of object lifecycle management, product validation and simulation, complex systems monitoring, and data-driven decision-making. Using a machine learning technique, this paper examines fault detection and develops a digital replica of the conveyor system of quality analysis of gear.

Calibration of the limit equilibrium pillar failure model using physical models

The limit equilibrium model, used in displacement discontinuity codes, is a popular method to simulate pillar failure. This paper investigates the use of physical modelling to calibrate this model. For the experiments, an artificial pillar material was prepared and cubes were poured using the standard 100 mm χ 100 mm civil engineering concrete moulds. The friction angle between the cubes and the platens of the testing machine was varied by using soap and sandpaper. Different modes of failure were observed depending on the friction angle. Of interest is that significant loadshedding was recorded for some specimens which visually remained mostly intact. This highlights the difficulty of classifying pillars as failed or intact in underground stopes where spalling is observed. The laboratory models enabled a more precise calibration of the limit equilibrium model compared to previous attempts. Guidelines to assist with calibration of the model are given in the paper. The limit equilibrium model appears to be a useful approximation of the pillar failure as it could simulate the stress-strain behaviour of the laboratory models.

Physical modelling as a conceptual device for climate responsive architecture: investigating pedagogy for theoretical discourses

Concepts remain the point of origin for creativity in design activity. For a comprehensive exploration of concepts it is imperative to assign adequate time and significance in architectural education and pedagogy towards their understanding. Physical modelling is one of the key techniques that helps in the critical analysis and conceptual comprehension in design. The current research considers the use of physical modelling as a conceptual device in the learning of theoretical discourse with specific focus on climate-responsive architecture. In the delivery of theories in architecture to students, such conceptual devices enhance and establish the knowledge imparted. While presenting the use of physical modelling as a conceptual device, the current research work acts as an illustrative exercise that can be carried out during the coursework for Climate and Built Environment that in turn can enrich the learning of thermal comfort principles in architecture. The research lists the learning outcomes of the classroom exercise and evaluates them against the learning theories postulated by the International Bureau of Education. The exercises resulted in the development of 3D physical models that illustrated the understanding gained by the students. It was observed that application of theory imparted during over the course of lectures was applied. The students also drew from their intuition and internal aesthetic sense. It was noted that the theory covered in class had been tested and explored and there was a strong rationale behind each model, proving that the exercise had taken the understanding of the theme beyond the scope of theoretical knowledge. The observations also revealed that the core principles of the learning theories propounded by the International Bureau of Education were in alignment with the learning outcomes from the modeling exercises that were executed by the authors, especially that of the Experiential Learning Theory. It may be concluded that these exercises can be effectively used in lecture classes that discuss architectural theories, including sustainability and climate response in buildings to expand the aesthetic and sustainable sensitivity of the learner. Consequently productivity in the design studio is vastly enriched. Apart from enrichment stemming from the listed learning outcomes, students are able to analyse design problems with climate in mind, thereby, familiarizing them with concepts of sustainability in the design studio.

FROM DATA TO TANGIBLE MODELS: CASE STUDY OF A VAULT IN THE ROYAL RESIDENCE OF VENARIA REALE

Abstract. Framed on a wider research project that investigates Geometry as a cultural substrate and shared language for the comprehension of Architecture and its shapes, the presented research focuses on the geometric analysis and dissemination actions of a vault of the Royal Residence of Venaria Reale, designed by Benedetto Alfieri in the XVIII century. The vault is the only one offering to visitors’ sight both its intrados and extrados surfaces. We propose an interdisciplinary approach that uses Geometry both as qualifying intangible heritage of the built shapes and as a language transversal to observation and survey, return of data and their interpretation from a dissemination point of view. To achieve this, we propose an innovative use of physical models, both in their meaning of object to be explored and in that of their design, between prototyping and seriality. Interaction between public and physical models becomes a way to promote critical shape-reading activities and to enhance spatial visualization abilities by their haptic/visual exploration, to recognize 3D built geometry and to explore architecture from different a point of view, getting closer to its shapes.

A Study of the Usefulness of Physical Models and Digital Models for Teaching Science to Prospective Primary School Teachers

This study focuses on the impact of the use of teaching resources on future teachers in different formats, physical and digital. We worked with a single task dealing with nutrition in humans with two groups of students, but one group worked with a version of the task that used physical resources, and the other group used digital resources as tools. Analyzing the work carried out and the answers given by the future teachers, it has been possible to observe the advantage of using digital resources over physical ones, although it did not generate significant differences between the two groups of participating students. This study shows how convenient it is to increase the use of digital models because of their lower cost, greater availability and ease of use. In short, they argue that the teaching of scientific knowledge should be complemented by the use of resources and models that facilitate learning, regardless of the format of the resource used.

Proposta de uso de novos métodos de desenho e construção de modelos físicos de fundo movél: o caso da barragem do Salto do Paraopeba

ABSTRACT The study of the interaction between hydraulic structures in mobile bed river systems is complex because it involves sediment transport and dynamic changes in the boundary conditions, requiring the use of physical models. This article presents the procedure for the design and construction of a physical model of the reservoir and dam of the Small Hydroelectric Power Plant (SHPP) of Salto Paraopeba. In the design phase, computational modelling of sediment transport was used to reconstitute the primitive geometry of the river, and simulations of the flow regime and the transport capacity along the course of the river were also carried out; both results allowed to delimit the model extension. Considering the choice of scale and the similarity criteria between the model and the prototype, the use of a new alternative material was proposed, composed of crushed tire rubber particles, with a lower specific mass and a larger diameter than the prototype's sediment. In the construction phase, a new constructive method of the physical model was applied using fiberglass, the method presents constructive advantages, such as better representation of the morphology, lower weight, simple installation and uninstallation through modules, and simple and fast repairs, among others.

Predicting surface solar radiation using a hybrid radiative Transfer–Machine learning model

Solar radiation is one of the cleanest sources of renewable energy, and it affects the carbon sink functions of terrestrial ecosystems. Although efforts have been made to establish solar radiation observation stations around the world, their coverage remains limited. Hence, the development of a wide variety of models and techniques is indispensable for obtaining effective solar radiation data. The aim of this study is to develop hybrid models with high computational speed and high accuracy to estimate global solar radiation (GSR) and quantify the uncertainty in GSR simulations caused by uncertainty in the measurements of atmospheric and surface parameters. The radiative transfer model (RTM) library for radiative transfer (LibRadtran) was coupled with six machine learning models: extreme gradient boosting (XGBoost), random forest (RF), multivariate adaptive regression splines (MARS), multilayer perceptron (MLP), deep neural networks (DNNs), and light gradient boosting machine (LightGBM). The estimated GSR was first compared to the inversion values of the GSR provided by the Aerosol Robotic Network (AERONET) and then validated using ground-based measurements at three locations in China from 2005 to 2018. The results showed that the RTM-RF is superior in terms of computational efficiency and performance, with a mean absolute errors (MAE) and coefficients of determination (R2) of 15.57 W m−2 and 0.98, respectively. Under clear sky conditions, aerosol optical depth (AOD) contributed the most to the accuracy of GSR estimates, with an average contribution of 57.95%. The measurement uncertainty due to the asymmetry factor, AOD, single-scattering albedo, and land surface albedo (LSA) can explain the differences in GSR between RTM estimates and GSR observations at the Lulin (20.33 vs. 20.91 W m−2), Wuhan (−1.40 vs. 14.58 W m−2), and Xianghe (7.28 vs. 14.32 W m−2) sites. Our study supports the use of physical models combined with machine learning models to estimate GSR and provides valuable scientific information for large-area solar radiation estimations.

Models in the Construction of Accounting Informatization Transformation Based on Digital Twin

The construction of accounting informatization is an effective tool for enterprises to transform from focusing on financial accounting to focusing on group management and decision support. Digital twins make full use of physical models, sensor updates and other data, integrate interdisciplinary and multi-scale modeling processes, and perform complete mapping in virtual space, which can reflect the process of the entire life cycle of the corresponding physical equipment. Based on the technology of digital twin, this paper solved the related problems in the transformation and construction of accounting informatization, and proposed a clustering analysis algorithm. Company A was taken as the experimental object, companies B and C were taken as the experimental control group, combined with data analysis, among the accountants of company A, 179 people have a supportive attitude towards the transformation of accounting information, 16 people have a neutral attitude, and 5 people have an opposing attitude, accounting for 89.5%, 8% and 2.5% respectively. However, among companies B and C, 196 and 199 people hold a favorable attitude, accounting for 98% and 99.5% respectively. The experimental results showed that the acceptance of the accounting informatization transformation is still relatively high among the employees of the enterprise.

The use of physical models in preventive medicine

Mathematical and Physical models have great potential when it comes to graphing in medicine. In this paper we have overviewed and concluded results from various papers which are under the topics of mathematical and physics models in preventive medicine. We have discussed models on the H1N1 influenza A, as well as on SARS-Cov 19 and have introduced and analyzed models suggested by other authors.

The influence of digital twins on the methods of film and television creation

All walks of life in the world have entered the "big data era", and China's film and television industry is also developing rapidly. Digital twins can also have a huge impact on how film and television are created. This paper aims to study the theoretical knowledge of digital twins and film and television creation methods, and propose an image and video super-resolution reconstruction algorithm based on video computing and reconstruction. Both algorithms make perfect sense in digital twins. This paper proposes how to study the impact of digital twins on the way of film and television creation. It can be seen from the data in Table 1 of the experiment in this paper that the director's attention to the way of film and television creation has increased from 54% in 2013 to 70% in 2019. It can be seen that the decoding quality of the two reconstruction algorithms is higher than that of the traditional reconstruction algorithm. It can be seen that it is very meaningful to explore the impact of digital twins on the way of film and television creation.Digital twin is a multi-disciplinary, multi-physical, multi-scale, multi-probability simulation process that makes full use of physical models, sensor updates, and operating history to complete the mapping in virtual space, thereby reflecting the full life cycle of the corresponding physical equipment. process. A digital twin is a concept beyond reality that can be viewed as a digital mapping system of one or more important, interdependent equipment systems.