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Background: COVID-19 has become a global concern as it has ended the lives of lakhs of people. The study done by. Lin proposed the results of an analysis of a theoretical computational model of epidemiology taking into account the crucial components such as response of an individual behavior, measures taken by government, rapid transmission and emigration of fever virus to a huge extent of human population. Simple model framework has been used by them to examine the requirements of essential elements.Problem: We claim the perfect validation of the assumptions stated for the purpose of modeling and its analysis, however, the analytical solution of the presented model is not discussed. And thus have a poor potential to make computational estimates.Methodology adopted: We have tried to present and validate the mathematical/analytic solution of the developed model, considering their assumptions.Conclusion: We have reached to the outcome that the work presented by Q. Lin should be demonstrated adequately with a cautionary advice of not to consider the results and analysis of such numerical models.The current study proposed the results of an analysis of a theoretical computational model of epidemiology taking into account the crucial components such as response of an individual behavior, measures taken by government, rapid transmission and emigration of fever virus to a huge extent of human population. Simple model framework has been used by them to examine the requirements of essential elements. We claim the perfect validation of the assumptions stated for the purpose of modeling and its analysis, however, the analytical solution of the presented model is not discussed. The decision point of this work is to adequately demonstrate along with the cautionary advice of not to use the outcomes and analysis of such numerical models. [ABSTRACT FROM AUTHOR]

In the paper considers a discrete model of SIRD, constructed on the basis of discrete Lotka-Volterra dynamical systems operating in a three-dimensional simplex with a degenerate skew-symmetric matrix. The sets of ignition and the end of the epidemic have been found, and the sets where the population is dying out have been found. The paper also provides a numerical analysis of the proposed model. [ABSTRACT FROM AUTHOR]

A heat sink is a device that removes heat from electronic devices that consume electricity. This heat removal is required to meet the equipment's design requirements. In this paper, different heat sink geometries are designed and simulated using computational fluids dynamic software to compare the temperature distribution and thermal performance. The main objective is to investigate the effect of the fin arrangement, base plate thickness and type of heat sink material on the thermal performance of heat sinks using the Ansys FLUENT 2021. The heat sinks have been analyzed at different heat load supply of 60 W, 70 W and 80 W. Three different fins arrangement of rectangular plates, rectangular pins and separated short plates heat sink are compared of the thermal performance in this study. The effects of heat sink materials on thermal performance were also investigated numerically. In this research work, thermal resistance is the parameter that determines the thermal performance of the heat sinks. The findings revealed that the thermal resistance is lower for the copper rectangular plates heat sink with 5 mm base plate thickness. [ABSTRACT FROM AUTHOR]

The material properties have a significant impact on disc brake performance. Cast iron is a material commonly for brake discs in automobiles right now, owing to its low cost. However, due to the better performance, Aluminum is now being used for disc brakes of some high-end automobiles. Aluminum is lightweight, it has a strong strength to weight ratio, and it cools faster than cast iron. In this study, further research has been conducted by adding varying percentages of fly ash to aluminum metal matrix composite. Fly ash, the residue obtained from coal combustion, is abundant and cheap. It helps improve the properties of the material like wear and abrasion resistance, stiffness, and low thermal conductivity. The six samples with varying amounts of fly ash: 0%, 5%, 10%, 15%, 17%, and 20% were manufactured using stir casting. Tests were undertaken to determine the mechanical properties of the samples and the disc brake was designed based on the test results. The objective of this paper is to perform numerical analysis on the designed brake disc of six samples of aluminum-fly ash metal matrix composite, including static structural analysis, modal analysis, dynamic analysis, wear analysis, computational fluid dynamics (CFD), and transient thermal analysis using the software. [ABSTRACT FROM AUTHOR]

Theoretical analysis to predict the crack propagation of Al 2024 is required and validated by experiment. This theoretical analysis was developed through a mathematical model that is based on the development of the Paris equation. The Paris equation is used to analyze crack propagation against a constant amplitude load. In this paper, a mathematical model based on the Paris equation is developed for the load spectrum, where the effective results are obtained at stage 2 when conditions are stable. The results of the development of this mathematical model are quite promising to be used as a reference for further experiments with the same material [ABSTRACT FROM AUTHOR]

This paper deals with a slat chain conveyor for the transport of rock materials in very severe abrasive conditions. An actual case from practice is discussed and analysed. To clarify the fatigue damage of the chain link material, the finite element method (FEM) is applied. For the experimentally recorded cycle of chain loading, numerical analysis has been performed and data for the damage of the link material are presented. Fatigue analysis is performed by ANSYS nCode DesignLife under different loading cases. FEM results show, that the fatigue crack of the link starts from region with high values of the stresses, established by experiment. [ABSTRACT FROM AUTHOR]

A finite element analysis on crash box of an automotive bumper system is presented in the paper to investigate the energy absorption of the component with and without foam-filled steel sheet metal tubes of different thicknesses for crashing or low-velocity impact analysis. The energy absorption capacity of the crash box for crashing is evaluated for different design changes of the foams-tube structure and compared the results without foam. By changing the different foam materials, various designs are proposed and simulated for maximum energy absorption. Altair Hyperworks is used for preprocessing and post-processing and Radios solver is used to run the analysis. A reasonable agreement is obtained in the results of the analytical and numerical methods. The results indicate that the energy absorption of a foam-filled crash box structure is superior to the crash box without foam. [ABSTRACT FROM AUTHOR]

The main idea of this paper is to give a profound investigation of the aerodynamic properties of a wing for Cessna 172S. The numerical analysis of total drag is developed by using various methods from different references, the 2D and 3D lift curve parameters of the wing Cessna 172S are generated according to the analysis method depending on empirical equations. The first stage of modelling Cessna 172S is evaluated according to the airfoil of Cessna NACA 2412, whereas the second stage of modelling is estimated by using wing planform properties. The maximum lift coefficient, lift curve slope, zero angle of attack, lift at zero angle of attack, and stall angle of attack are calculated by using different empirical equations. [ABSTRACT FROM AUTHOR]

Texture masking has been used as a significant factor in creating perceptual maps that simulates human vision system in observing noise in digital images. In this paper, the possibility of creating texture masks using first and second derivatives is investigated and tested. Results shows that after applying the derivatives, areas of higher texture were highlighted and recognized, which will lead to simple implementation of texture masks using numerical analysis. [ABSTRACT FROM AUTHOR]

The following paper aims to provide a detailed analysis of the effect of different cutting speeds in the face milling of AISI 1045 steel using coated tool. Simulations would aid in solving problems associated with experiments, leading to reduced costs and risks. DEFORM 3D is a commercially used simulation software capable of implementing machining simulations using the theory of finite element modelling. A conventional DEFORM 3D milling model has been prepared for the analysis of cutting forces and chip formation and the simulation has been carried out for two conditions. The temperature and force parameters were analyzed after carrying out the experiment and simulation under the influence of different machining and environmental conditions. The results of the simulation revealed that the predicted values of FEA possess good accuracy. [ABSTRACT FROM AUTHOR]

The present paper analyzes failure observed in polymer rods collided with a steel anvil under the Taylor cylinder impact experiments. The experimental and numerical analysis demonstrates that association of the failure patterns with the loading mode depends on the rod material. Two materials are considered in the paper, specifically, polymethylmethacrylate (PMMA) and polycarbonate (PC). Damage in PMMA rods at the Taylor tests is shown to be dominated by the shear load resulting in plastic deformation. In contrast, the major mechanism of damage in PC rods is governed by omni-directional (pressure) mode of load. Analysis of the damage in sections of the rods associated with the glass transition is also addressed in the present theoretical study. Failure in these polymers follows the traditional fracture wave mechanism for brittle glass-type materials due to load in the corresponding mode. Numerical analysis employs a two-phase model with improved inter-phase thermal balance accounting for the inter-phase mass, momentum, and heat exchanges during the glass phase transition, while damage being accumulated in time. The simulation results demonstrate a good correlation with the experimental results. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of load-bearing capacity and deformability of wood-steel hybrid systems, depending on the selected system constellation, and the possibility of increasing system efficiency and in real conditions by applying pre-stress, in accordance with modern principles of structural conceptual design. The subject of the research is the behaviour of pre-stressed glued laminated beams with external polygonal ropes, different researched constellations, i.e. strut type hybrid systems, in real conditions. The paper is practically divided into three methodological units: theoretical and numerical analysis, and examples of practical applications, and on the theoretical basis of urban transformations of historical units. Theoretical assumptions, as well as the current and own approach to the analysis of parameters, set the theoretical basis for the analysis of these systems and the possibility of applying numerical methods in practice. Parametric analysis of the hybrid system obtained practical expressions and diagrams for use in practice, needed to determine suitable constellations of strut type hybrid system by different geometric characteristics and pre-stressed hybrid system, and for different percentages of wooden girder moisture. In order to compare these systems, the same assumptions were used for the calculation, namely: plane behaviour of the system, and to determine the effective pre-stressing, the condition of annulment of vertical deflection in characteristic cross-sections was used, i.e. achieving the effect of vertical immobility of the struts, from which the measure of pre-stressing of the deformable system was obtained. A hybrid system with a wooden girder, which has bending stiffness, is often used in construction, and the main disadvantage of such a system is the expressed deformability in real operating conditions. The basic thesis of this paper is that by external pre-stressing of glued laminated girder achieves less deformability and increases bearing capacity, while saving base material in real conditions, and is confirmed by our own parametric analysis and laboratory testing of pre-stressed hybrid systems of different constellations. The attached parametric analysis diagrams provide a sufficiently accurate orientation for finding the correct constellations of wood-steel hybrid systems and the possibility of estimating the efficiency of hybrids in real conditions, as well as the necessary pre-stressing applications. The derived expressions of the approximate procedure and the expressions for finding the effective pre-stressing force, assuming the linear behaviour of the system, give sufficiently accurate results for the design of pre-stressed hybrid systems in practice. Also, with this or similar methodology it is possible to qualitatively investigate hybrid systems with different combinations of materials. The presented conceptual solutions for the integration of hybrid systems and modern materials in specific localities represent a contribution to the development of a methodological approach to the transformation of historical urban units. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of load-bearing capacity and deformability of wood-steel hybrid systems, depending on the selected system constellation, and the possibility of increasing system efficiency and in real conditions by applying pre-stress, in accordance with modern principles of structural conceptual design. The subject of the research is the behaviour of pre-stressed glued laminated beams with external polygonal ropes, different researched constellations, i.e. strut type hybrid systems, in real conditions. The paper is practically divided into three methodological units: theoretical and numerical analysis, and examples of practical applications, and on the theoretical basis of urban transformations of historical units. Theoretical assumptions, as well as the current and own approach to the analysis of parameters, set the theoretical basis for the analysis of these systems and the possibility of applying numerical methods in practice. Parametric analysis of the hybrid system obtained practical expressions and diagrams for use in practice, needed to determine suitable constellations of strut type hybrid system by different geometric characteristics and pre-stressed hybrid system, and for different percentages of wooden girder moisture. In order to compare these systems, the same assumptions were used for the calculation, namely: plane behaviour of the system, and to determine the effective pre-stressing, the condition of annulment of vertical deflection in characteristic cross-sections was used, i.e. achieving the effect of vertical immobility of the struts, from which the measure of pre-stressing of the deformable system was obtained. A hybrid system with a wooden girder, which has bending stiffness, is often used in construction, and the main disadvantage of such a system is the expressed deformability in real operating conditions. The basic thesis of this paper is that by external pre-stressing of glued laminated girder achieves less deformability and increases bearing capacity, while saving base material in real conditions, and is confirmed by our own parametric analysis and laboratory testing of pre-stressed hybrid systems of different constellations. The attached parametric analysis diagrams provide a sufficiently accurate orientation for finding the correct constellations of wood-steel hybrid systems and the possibility of estimating the efficiency of hybrids in real conditions, as well as the necessary pre-stressing applications. The derived expressions of the approximate procedure and the expressions for finding the effective pre-stressing force, assuming the linear behaviour of the system, give sufficiently accurate results for the design of pre-stressed hybrid systems in practice. Also, with this or similar methodology it is possible to qualitatively investigate hybrid systems with different combinations of materials. The presented conceptual solutions for the integration of hybrid systems and modern materials in specific localities represent a contribution to the development of a methodological approach to the transformation of historical urban units. [ABSTRACT FROM AUTHOR]

Functionally Graded Materials (FGMs) is a new composite material with gradients of material composition. The FGMs introduce by scientists from Sendai, Japan. The properties of FGMs used in this paper are metal and ceramic. Metal is a material that is resistant to structural flexibility, while ceramic is a material that is resistant to high temperatures. This paper presents the free vibration of FGMs beams using the Mixed Quadratic Beam (MQB) element. This paper begins with the formulation of the MQB element, then followed by numerical analysis of free vibration on FGMs beams problems. Free vibration analysis of FGMs beams is done by solving a simple supported (SS) beam with L/h=5. The results are compared to the reference solution. From the analysis, it can be concluded that the MQB element shows promising results for beams with a large number of elements. [ABSTRACT FROM AUTHOR]

Steel coupling beam is a substantial member in hybrid coupled walls system that greatly enhance the strength and the energy dissipation capacity of the system compared to coupled walls linked by convention reinforced coupling beams and diagonally reinforced coupling beams. To enhance these characteristics even more, a corrugated web may be used instead of the traditional flat web. This paper presents a numerical analysis using finite elements software (ABAQUS) to investigate the nonlinear behavior of both types of steel coupling beams (with flat web and with corrugated web). The effect of initial imperfection on the nonlinear behavior of steel coupling beams was taken into account. The results were compared with the available experimental data of steel coupling beams with the flat web. Good agreement was noticed between the experimental and the numerical results. Among the conclusions drawn in this study is that using a corrugated web as an alternative to a flat web may increase both the strength and the energy dissipation of the steel coupling beams. [ABSTRACT FROM AUTHOR]

Pre-impregnated materials (Prepregs) have greatly impacted many industries that require specific advanced composites, such as aerospace structures for UAVs. Prepreg material aids the structure by reducing weight while increasing strength and allowing for reasonably consistent manufacture. One of the most essential features of these materials is the variation in properties as the orientation of the layer changes. This requires the use of advanced techniques for strength analysis, including numerical modelling and material testing. This paper presents an experimental evaluation approach to estimate the mechanical properties of composite shells, including cutting schemes, specimen preparation, and test procedures. In the next stage, this study discusses the use of ABAQUS FEA to replicate the phenomenon of specimen failure modes. The investigated prepreg specimens in this study were created using XC 130 unidirectional easy composite prepreg. Through this research, the failure mode results of testing and numerical analysis showed a good agreement. [ABSTRACT FROM AUTHOR]

The paper deals with the determination of the rotational stiffness of a timber semi-rigid joint. The rotational stiffness was calculated on the basis of the currently valid standard, experimental test and numerical model. The connection was made of a standard combination of bolts and dowels, which consisted of 10 pieces of fasteners with a diameter of 8 mm. The elements of the connection consisted of facades and two struts with a cross-section of 100x300 mm. The connection was then statically repeatedly loaded and relieved. The loading took place up to the level of the ultimate limit state and the unloading up to 10% of the maximum value. In order to determine the actual mechanical properties of timber and fasteners, partial tests were performed for the needs of numerical modelling. [ABSTRACT FROM AUTHOR]

Members of open double-symmetrical cross-sections are widely used in steel structures. In many cases their webs are subjected to transverse compression resulting from the effect of adjacent members or from the concentrated transverse loads. Resistance of the member web to transverse compression is affected by number of aspects, e.g. structural solution of the joint (welded or bolted with end plate), possible longitudinal normal stress in the member caused by axial load or bending moment, interaction with shear or effect of local buckling of the web. The paper focuses on specific problem of resistance of the web to transverse compression resulting from transverse load applied close to the unstiffened end of the member. The investigation of the resistance of the web to transverse compression is performed using advanced geometrically and materially nonlinear numerical analysis for various distances of the transverse load from the unstiffened end. The influence of this distance on transverse compression resistance is quantified. Rolled and welded cross-sections of various web slenderness are investigated. The results are, where possible, compared with results obtained from available design standards. [ABSTRACT FROM AUTHOR]

In this paper the numerical investigations concerning static response of a different configurations of concrete columns subjected to Euler's load are presented. An original approach of connecting the column and pocket footing via steel cut-off pyramid heads is presented. As shown in other works the main difference between conventional planar ended column and the column ended with cut-off pyramid shape is the axial force redistribution at the connection. In the case of standard connection, the compressive force is transferred onto foundation and consequently from the point of connection that force is distributed outwardly with 45° degrees' incline angle onto the ground. With the presented cut-off pyramid connection, one makes possible to reduce foundation height as a result of transferring on footing and consequently to the ground only a part of the compressive force, whereas remaining amount of force is converted into tensile stress effectively taken over by steel reinforcement. A comparative numerical analysis using SolidWorks FEM based software between standard and proposed solution is performed taking into account columns' critical load and Misses-Hencky stress (MHS) redistribution near the columns' head. On the basis of presented results, both solutions advantages and disadvantages are emphasized. [ABSTRACT FROM AUTHOR]

An application of small aerial vehicles is described in this paper which presents an optimization of the camber position ever-changing using models and numerical analysis. During this study, the mechanics performance of a wing must be investigated over a profile of camber of 20 percent length of the chord from edge. The model was initially modelled using a software package and by adjusting the morphing wing system's modularity and reconfigurability. The angle of attack is also explored following a comparative analysis of the mechanics parameters. A considerable effect of morphing flap camber profiles on mechanics performance is observed in the results. As a supplementary validation, we provide an analysis of wind characteristics through ANSYS; we obtain the pressure coefficients, lift (CL), drag (CD), and lift-to-drag ratio (CL/ CD). The correlation between the CL, (CL/CD) and drag cut back simulations for several preferred shapes is analyzed when getting the results. For that reason forward in optimizing the cambered profile when morphing edges because the mathematical analysis associated with it has been shown improvements in CL from 15% to 30% when morphing edges. [ABSTRACT FROM AUTHOR]

In this paper we study the preservation of Lyapunov functions in the numerical integration of ordinary differential equations. By means of a continuous extension and a projection technique we extend the technique proposed by Grimm and Quispel (BIT 45, 2005), so that it can be applied to other families Runge—Kutta methods such as the well known Dormand and Prince 5(4) pair. [ABSTRACT FROM AUTHOR]

This paper arose from the teaching of Models in Biology to take a new approach to problems they are familiar with, to come up with an articulate verbal model after a mental effort, to express it in rigorous mathematical terms, to solve corre-sponding equations (with the help of computers), and to analyze and interpret experimental data in terms of their (mathematical) models. We will investigate a mathematical model of branching by solving a system of partial equations (PDEs). The results will describe the success or failure of the growth of the fungus species studied, and we used some codes (pplane7, Pdepe) in numerical analysis because direct mathematical solution was difficult. [5] Tip death due to hyphal death, dichotomous branch-ing [ABSTRACT FROM AUTHOR]

The ABC flow for the stationary three dimensional Navier-Stokes equations is considered. The problem is formulated on the full periodic domain. The main object of the paper is the preliminary analysis of the solution curves and location of disconnected solutions from the main branch (stationary trivial solution defined by the forcing term in the ABC problem setup). It is noted that the disconnected solutions exist for two variants of the problem parametrization: A = B = C = 1 and A = B = 1,C = 2. [ABSTRACT FROM AUTHOR]

Members of double-symmetrical open cross-sections are widely used as columns in steel structures. In many cases columns are subjected not only to axial force but also local transverse force due to effect of beams connected to the columns. It results in compression in the column web that should be verified in the structural design. Current standard for design of joints in steel structures provides basic information for verification of this joint component. The design resistance of column web in compression is given as yielding resistance or, based on relative slenderness of the web, buckling resistance which takes into account buckling and crippling of the web that are considered using reduction factor. The complex behaviour of the column web in compression is affected by number of aspects, e.g. structural solution of the joint (bolted, welded, with or without end plate), level of normal stress resulting from axial force or possible interaction with shear. The paper focuses on selected aspects influencing the resistance of the column web in transverse compression and summarizes results of advanced geometrically and materially nonlinear numerical analysis which are compared with results determined using provisions in the standards. The numerical analysis was performed using computation system based on finite element method. As it is considered that the resistance of the column web in transverse compression is influenced also by the geometric properties of the cross-section including geometry of the flange-web transition, both rolled and welded cross-sections with various values of web slenderness were selected for the analysis. Along with evaluation of the results obtained in the frame of the study, suitability of different types of numerical models for investigation of this problem is discussed. [ABSTRACT FROM AUTHOR]

The paper reports a numerical campaign in which two point-supported elements made of laminated glass were investigated with FEM. The first element was a horizontal roof panel 3000×1500 mm2 supported at six locations and subjected to static, uniformly distributed load. The second element was a free-standing glass balustrade 900×1900 mm2 mounted to the structure by four-point supports and subjected to soft body impact. Four types of fixings were investigated: disk fixing, countersunk fixing, bonded disk fixing and countersunk fixing on a single layer. The analysis was aimed at the investigation of the influence of different point supports on the stress in the glass. For a selected connector, a comparative analysis using the FE software and an analytical method presented in DIN 18008-3 was performed. In addition, an analysis of a positive influence of a continuous handrail on the behavior of a row of free-standing glass balustrades was investigated. [ABSTRACT FROM AUTHOR]

Members of double-symmetrical open cross-sections are widely used as columns in steel structures. In many cases columns are subjected not only to axial force but also local transverse force due to effect of beams connected to the columns. It results in compression in the column web that should be verified in the structural design. Current standard for design of joints in steel structures provides basic information for verification of this joint component. The design resistance of column web in compression is given as yielding resistance or, based on relative slenderness of the web, buckling resistance which takes into account buckling and crippling of the web that are considered using reduction factor. The complex behaviour of the column web in compression is affected by number of aspects, e.g. structural solution of the joint (bolted, welded, with or without end plate), level of normal stress resulting from axial force or possible interaction with shear. The paper focuses on selected aspects influencing the resistance of the column web in transverse compression and summarizes results of advanced geometrically and materially nonlinear numerical analysis which are compared with results determined using provisions in the standards. The numerical analysis was performed using computation system based on finite element method. As it is considered that the resistance of the column web in transverse compression is influenced also by the geometric properties of the cross-section including geometry of the flange-web transition, both rolled and welded cross-sections with various values of web slenderness were selected for the analysis. Along with evaluation of the results obtained in the frame of the study, suitability of different types of numerical models for investigation of this problem is discussed. [ABSTRACT FROM AUTHOR]

The paper reports a numerical campaign in which two point-supported elements made of laminated glass were investigated with FEM. The first element was a horizontal roof panel 3000×1500 mm2 supported at six locations and subjected to static, uniformly distributed load. The second element was a free-standing glass balustrade 900×1900 mm2 mounted to the structure by four-point supports and subjected to soft body impact. Four types of fixings were investigated: disk fixing, countersunk fixing, bonded disk fixing and countersunk fixing on a single layer. The analysis was aimed at the investigation of the influence of different point supports on the stress in the glass. For a selected connector, a comparative analysis using the FE software and an analytical method presented in DIN 18008-3 was performed. In addition, an analysis of a positive influence of a continuous handrail on the behavior of a row of free-standing glass balustrades was investigated. [ABSTRACT FROM AUTHOR]

This paper is concerned with a Holling-II stage-structured predator-prey system (in which predators are divided into immature and mature predator) with fear effect. The aim is to explore how parameters factors influence on the bifurcation behavior of the model. The theoretical works showing that transformation rate and maximum attack rate can lead to saddle node bifurcation, and transcritical bifurcation. In addition, fear rate may lead to occurrences a Hopf-bifurcation near positive equilibrium point. Numerical analysis ensures accuracy of the theoretical outcomes and testifies the existence of local bifurcations near the non-trivial equilibrium points. [ABSTRACT FROM AUTHOR]

Crop imagery is categorized into 3 different types, which are near-field images, satellite images and drone-based images. All these image types can be processed to determine crop growth, crop diseases and finally crop yield. Different algorithms have been proposed over the years which determine one or more of these parameters using a series of image segmentation, feature extraction, feature selection, classification and post-processing steps. Each of these steps requires a specialized set of algorithms to be employed to design an effective crop-image processing system. Due to the wide variety of algorithms present in the given field of work, the selection of the most optimum algorithm set for a given application is often ambiguous. For instance, if an application is trying to process satellite imagery, then identification of the best image-fusion methods for effective classification requires a lot of research, and thus increases the delay in designing the system. To reduce this ambiguity, this paper reviews these algorithm sets which identify the best techniques in terms of statistical parameters for a given application. Accuracy and error rates have been compared between different algorithms to give a clear idea about the performance of these algorithms. This comparison also allows researchers to identify best practices in terms of algorithm selection. [ABSTRACT FROM AUTHOR]

The paper deals with numerical modeling of slab in interaction with the subsoil. A 3D computational model and numerical analysis are focused primarily on taking into account physical nonlinearity. The fracture-plastic material model is used, where the parametric study is performed with different input parameters of fracture energy. For nonlinear calculation the Newton-Raphson method was chosen. The performed calculations are compared with the experiment of a fibre-reinforced concrete slab with dimensions of 2000 x 2000 mm. The slab was tested on a specialized testing device, which allowed to evaluate the load - displacement diagram. Calculation results are compared with the experimental data and finally comparison is performed. [ABSTRACT FROM AUTHOR]

The paper deals with numerical analysis of pretensioned experimental beams exposed to loading test. Pretensioned beams were designed as model structural specimens, adjusted to real dimensions of slab bridge beams, made of common concrete and new variant of high performance concrete with compressive strength about 100 MPa. Experimental beams were exposed to loading test for verification of load bearing calculation model, as compressive strength of HPC is on the border or oversteps the validity of current design codes. Numerical analysis was performed using software IDEA statica which enables to determine cogent effect of prestressing with respect to changes in time related to construction stages. Failure and cracking load appointed on the basis of experimental loading and numerical analysis are compared and discussed. [ABSTRACT FROM AUTHOR]

Determination of the current condition, load-bearing capacity, and reliability of the existing structures is often a greatly time-consuming and complex task. There are two main approaches how to evaluate the condition of existing structures and find out the response of the structure under acting loads. The first method is to perform an analytical or numerical analysis of the structure. This method is often used, but the accuracy of the outcomes deeply depends on the input parameters used in the analysis. Alternatively, if the input parameters are not clearly known or the exact behavior of the structure during loading is required, the best way how to evaluate the structure is to perform a full-scale load test. This paper describes the process of preparation, execution, and evaluation of the in situ full-scale load test of the bowstring arch reinforced concrete bridge built between the 1920s and 1930s damaged during the Second World War, repaired in the 1970s with no further maintenance later on. [ABSTRACT FROM AUTHOR]

This paper presents the description of the preparation of aggregate irradiation experiment including the choice of sample types and preliminary numerical prediction of aggregate RIVE and damage under defined conditions for the research reactor LVR-15. Ten different samples from four countries were selected for the experimental investigation. The preliminary numerical analysis was performed for granite as the aggregate with the highest radiation-induced volumetric expansion (RIVE). Based on the prediction, the highest RIVE of 4.54 % at high-dose neutron fluence (0.585·1020 n/cm2, with energy E>10 keV) is expected. Thus, taking into account the sample size, the inner diameter of the irradiated capsule should be about 11 mm. The aggregate samples with the highest RIVE (granite) are expected to be damaged significantly even after irradiation to low-dose neutron fluence (0.208·1020 n/cm2, with energy E>10 keV) which will be captured during the post-irradiation examination. [ABSTRACT FROM AUTHOR]

In our models we assumed that all objects are of good quality. This is possible only under very impractical conditions but actually this is not possible. This paper deals with a two level supply chain Management for fault items. To certify orders, the producer offers some facilities to the retailer such as trade credit for some part of the order, free shipping on the basis of advance payment amount. Enlargement cost is taken as a function of time to keep the fulfillment of the manufacturing system. To find optimum profit we use fuzzy Monsoon demand without shortage. Screening process is also considered to identify whether the formed items are perfect or imperfect. In this paper we derive some useful algorithms to find the optimal solution. Moreover, sensitivity analysis and numerical analysis are made to justify the optimum solution. [ABSTRACT FROM AUTHOR]

The basic function of the gas turbine blades is to rotate the shaft connected to the generator motor. In electricity generation station, because the materials used in manufacturing must resist harsh working conditions, gas turbine blades are subject to high vibration, pressure and temperature. In this paper, the maximum pressure and deformation are caused by the effect of centrifugal force on the gas turbine blades. And to determine the natural frequencies of vibration, which are caused by the rotation speed about 3000 r.p.m under high-temperature conditions. The finite element method (FEM) was used to determine the natural frequency of turbine blade material (GTD-111) applied in the South Baghdad Power Station in Iraq, Baghdad. This paper deals with the structural analysis of gas turbine blades. Analysis was performed to find out the mechanical stresses and radial elongation to which the gas turbine rotor blade is subjected. A solid turbine blade model is constructed using the SOLIDWORKS2018 software. The turbine blade is analyzed for its structural performance due to the loading conditions using ANSYS 19 software to study the stress variation on the GTD-111 alloy gas turbine blades. The results shows that under static load and the stress and strain on the blade, the amplitude of the blade vibration will change at the higher frequencies of 581.42 Hz and 935.84 Hz because the root of the blade is placed on the disk-like cantilever (girder fixed at only one end). [ABSTRACT FROM AUTHOR]

The development of modern society is conditioned by the accelerated pace of development of technological awareness. Our urban environment is increasingly exposed to radical transformations, leaving no room for perception and adoption of the new, almost excluding the feeling of belonging to the transformed environment. Such changes, caused by the expansion of construction activity, often violate the ambient and original values, in the transformed environments of "captured" cultural and historical heritage Objects of cultural and historical heritage possess historical, artistic and aesthetic value, readability in all their historical changes and the symbolic value of the tradition of the society to which they belong. Preservation of spiritual, formal and traditional originality, with all the technical characteristics they carry with them, emphasizing the uniqueness and representativeness of heritage in a modern environment, is an imperative in preserving one's own identity. The constructive characteristics of the historical heritage building were dictated by the degree of technical knowledge, experience and intuitiveness of the builders of that time. The specificity of structural systems and construction techniques have a direct impact on the architectural character of buildings, and thus the approach to structural repair, considering the problem exclusively from the point of view of structure and application of modern methods of numerical analysis and technology, can be a cause of disavowal of these buildings.Thus, questions arise: How sovereign are new knowledge and methods over the old, or is it necessary to awaken the intuitiveness of today's builders? How to achieve compatibility of old and new, where necessary? In this paper, the case study of a specific sample of the cultural and historical heritage of Despic House will provide answers to the questions asked. Despic House, where the first theatre in Sarajevo was founded, is one of the few material evidences of life in the city at the turning point of the Ottoman and Austro-Hungarian periods. Atypical in relation to the local way of building, it is a unique example of a combination of the traditional heritage of the Ottoman period and the " breakthrough of European creativity into the culture of this area". This paper presents a complex research process of establishing the genesis of the Despic House, as well as the consequences of the influence of urban transformations in the spatial framework at the level of the architectural object and the level of the urban-architectural ensemble. On the example of established and implemented measures of structural repair of this building, the importance of a multidisciplinary approach to detailed research and conservation-restoration works for cultural and historical heritage buildings will be confirmed, taking into account its original values. [ABSTRACT FROM AUTHOR]

In this paper an EPQ model is studied for deteriorating items with non linear price and stock dependent demand under the effect of inflation. Most of the inventory model considers holding cost assumed constant but in real situation it depends on time. Therefore holding cost assumed as a function of time. Shortages are taken partially backlogged type with fixed backlogging rate. The main objective of this proposed paper is to obtain the optimal solution. The numerical analysis has been also done to verify the initiated paper. Finally, a sensitivity analysis is also made for different parameters to obtain some useful observations. [ABSTRACT FROM AUTHOR]

In this study, the turbulent flow over symmetrical and unsymmetrical airfoils was investigated numerically at different inlet velocities. The airfoils chosen for the simulation are symmetrical (NACA 0015) and unsymmetrical (NACA 4412), which are the most conventional four-digit and widely used airfoils. These airfoils are vastly used for various applications such as aircraft wings, wind turbine blades, etc. While both of these airfoils were subjected to the same fluid principle, it gave contradictory results in their aerodynamic behavior. In this paper, two different meshing techniques were used for the airfoils and the numerical analysis of NACA 0015 and NACA 4412 was carried out to study their aerodynamic behavior. A 2D steady-state incompressible turbulent flow is used to model the computational issue. The performance of the turbulence model is also reviewed. The lift and drag coefficients of the airfoils were numerically measured using the k − ε turbulence model. This study briefs the aerodynamic flow characteristics of both airfoils and evaluates the pressure and velocity contours, lift force and drag force. [ABSTRACT FROM AUTHOR]

The novel coronavirus disease 2019 (COVID-19) has shown the danger that can be caused by small, airborne and contagious virus particles such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To prevent the mass spreading of such viruses, the use of electromagnetic waves could be used to combat the spreading of the virus. Particularly, the waves could force any virus particles to oscillate in resonance with the frequency of the wave and destroy themselves before the virus would enter the respiratory system. This paper describes the use of numerical simulations to analyze the effects of exposing a SARS-CoV-2 particle to electromagnetic waves at a range of frequencies and to determine which frequencies have the potential of causing resonance within the virus which would yield to the maximum energy absorption. Such technique could be utilized in preventive/protective devices and disinfection equipment. [ABSTRACT FROM AUTHOR]

Castellated beams are well contemporarily ascribable to their structural applications. The Castellated beams are manufactured by fragmenting hot-formed rolled section that is of I shape in then it is welded together. The numerical analysis is performed using ABAQUS software. Consequently flexural, shear behavior of Castellated beams, various size and shape of openings provided, depth of openings, usage of different kinds of stiffeners, columns with and without web openings are the attempts made up in different journal papers and he researchers. It is also found that the Finite element analysis of the beam shows better results. [ABSTRACT FROM AUTHOR]

Currently, the use of spline functions in the development of Science and technology is a topical issue. Spline features the classic interpolation has several advantages in terms of rapprochement from multiples. Based on clearly given experiments, the construction of a local interpolation cubic spline function was analyzed based on a linear combination of parabolas with 2 common points. In this paper, all the properties of the local interpolation cubic spline functions built at each interval at the connection node points are analyzed on the basis of several experimental data and on the basis of numerical processing. The continuity of local interpolation cubic spline functions at all connection nodes was checked using graphs and numerical analysis based on concrete examples. [ABSTRACT FROM AUTHOR]

In this paper, we consider the study of the extreme problem of the fictitious domain method based on the use of the Lagrange functional, with a multiplier defined on the actual boundary and associated with genuine boundary conditions. The theorem of the existence of a generalized solution of the auxiliary FDM problem is proved. The convergence of the solution of the auxiliary FDM problem is shown. For mathematical research, the theory of functional spaces and the technique of obtaining a priori estimates in functional spaces are used. To verify the effectiveness of the developed method, numerical analysis and comparison with other methods of solving the problem were carried out. [ABSTRACT FROM AUTHOR]

In the present paper, a time dependent source of identification p roblem f or a o ne d imensional d elay hyperbolic equation with Dirichlet condition is studied. The first order of accuracy difference scheme for this source identification problem is presented. Numerical analysis and discussions are presented. [ABSTRACT FROM AUTHOR]

The combination of plastic and creep analysis formulation are developed in this paper. The boundary element method and the finite element method are applied in plates in order to do the numerical analysis. This new approach is developed to combine the constitutive equation for time hardening creep and the constitutive equation for plasticity, which is based on the von Mises criterion and the Prandtl-Reuss flow. The implementation of creep strain in the formulation is achieved through domain integrals. The creep phenomenon takes place in the domain which is discretized into quadratic quadrilateral continuous and discontinuous cells. The creep analysis is applied to metals with a power law creep for the secondary creep stage. Results obtained for some models studied are compared to those published in the literature. The uncertainties in both geometric and mechanical properties are considered in order to obtain the structural response. The approach is illustrated in a plate subjected to incremental load, results show that there are high probabilities of exceeding the damage states, w, equal to 0.3, 0.6, 1.2, 1.8 and 2.4 while for values of w equal to 3.0, 3.6, 4.2, 4.8, 5.4 and 6.0 these probabilities are low. The obtained results are in good agreement and evinced that the Boundary Element Method could be a suitable tool to deal with combined nonlinear problems. [ABSTRACT FROM AUTHOR]

In this paper, we discuss the susceptibilities of a bilayer system which is comprised of ferroelectric (FE) and ferromagnetic (FM) material. At the interface between FE and FM, the magnetoelectric (ME) interaction exist, resulting in a ME coupling. The derivation of the susceptibilities of the bilayer system was started by determining the FE and FM energy densities. Then, the entire-cell effective medium method was employed to obtain effective susceptibilities of the bilayer system. As a result of the existence of ME coupling, we obtain not only ferromagnetic and ferroelectric susceptibilities, but also magnetoelectric and electro-magnetic susceptibilities. Here, magnetoelectric susceptibility relates magnetization and electric field while electro-magnetic susceptibility links the electric polarization and magnetic fields. We also found that the ME coupling also shifts the magnetic resonance frequency. [ABSTRACT FROM AUTHOR]

The main objective of the research work is to present the free vibration analysis of plates composed of one of the materials that have good performance and can be applied in many fields like buildings. Material that has such properties is Functionally Graded Material (FGM). FGM consists of a mixture of ceramics and metals through varying volume fractions, ceramic material as a heat barrier at the high-temperature side, and metal material with rigid properties and high conductivity at the low-temperature side. In this paper, the FGM plate is investigated using the finite element method. We use 3-node Triangular Mixed Interpolation of Tensorial Components (MITC3), widely used by researchers or commercial software. The MITC3 element is a triangular element that gives good performance to analyze plate problems, especially isotropic plate problems. We performed the numerical analysis to examine the performance and convergence behavior of the MITC3 FGM plate element in the case of rectangular plates with varying length to width ratios, and the results are compared with the reference solution. [ABSTRACT FROM AUTHOR]

Nowadays, 3-D printing (or additive manufacturing) is a widely used technique in different branches (e.g. public healthcare, consumer goods, weapons development etc.) to produce various objects and products. In the last years, 3-D printing has also begun to be used in the fields of civil engineering. Today, the use of 3-D printing in civil engineering takes different forms. Authors of this paper focus on the use of 3-D printing for the development of plastic formworks for concrete which can substitute steel reinforcement. This technology has its limitations for now, but it is still worthy for the numerical investigation which will be necessary for practical designing of concrete structures with 3-D printed plastic reinforcement in future. For this reason, the numerical investigation of mechanical behavior of concrete element shaped and reinforced by 3-D printed formwork is performed within this paper. The flexural strength test is numerically simulated for this purpose. The result of the best numerical simulation is compared with the result of the practical flexural strength test which was obtained from the former experimental investigation. Based on this comparison, provisional insufficiencies of the used numerical approach are discussed. [ABSTRACT FROM AUTHOR]

Many soft robotic structures are developed using soft fluidic actuators, which are developed using elastomeric materials such as silicon rubber. Due to the complicated geometries and nonlinearity in the soft actuator's design, it becomes very difficult to predict their behavior analytically. Finite Element Method (FEM) analysis is a numerical technique which is utilized to predict the stress, strain, and deformation in such actuators design. In this paper, bending behavior of two soft pneumatic fingers with varying wall thickness are designed and compared. Bending angle configurations of the designed fingers are evaluated at 30 and 40 kPa of actuating pressure. The obtained results show that to achieve a bending angle of 116 degrees, finger 2 requires 40 kPa of actuating pressure whereas finger 1 requires 80 kPa. Due to low stiffness of finger 2 as compared to the finger 1, which is resulted due to thickness variation in the two designed fingers, much higher bending angle configuration can be achieved at very low pressure for the finger 2. [ABSTRACT FROM AUTHOR]

The presence of ducts surrounding wind turbines improves the performance by accelerating the wind at the entrance. The objective is to find a duct that produces improved wind power with low duct drag forces. Numerical analyses were carried out on the flow past a ducted wind turbine using computational software ANSYS Fluent. In this paper, the performance of six different ducts surrounding the wind turbine was compared. The duct geometries considered were S1) E423 aerofoil duct of chord length (L) / (throat diameter) D ratio=0.225 at 37.5 °, S2) duct with leading-edge slot, S3) duct with trailing edge slot, S4) duct with trailing edge flap, S5) duct with converging section and S6) duct with multiple slots. The performance improvement was evaluated using the average velocity in front of the blade plane and power output. The flow characteristics of conventional turbines and six ducted turbines were discussed. It was found that duct with trailing edge flap had shown higher power output with higher drag. The results indicate that the duct with multiple slots in the duct's circumference had equivalent power output to a fully closed duct. [ABSTRACT FROM AUTHOR]

A screw-type centrifugal pump is a kind of non-clog type pump and has been widely used, for instance, for drainage of rainwater as well as slurries and mud in sewage control systems. In order to avoid choking the impeller passage with the congestion of solids, the impeller is designed to have a wide passage which configuration is screw formed by a three-dimensional spiral blade added to a conical hub cone. This paper presents the results of pressure and velocity fields in centrifugal pump with single blade. In the pump tested, a volute with circular cross-section was used. The prediction of radial thrust is important and useful information for the safe operation and design of the bearings. Particularly, the fluctuation of radial thrust in this pump is large because of one blade. The tests were carried out for several flows, including above and below the nominal one. Effects of the time-steady flow in a single-blade pump are investigated by numerical method CFD (Computational Fluid Dynamics), specifically discussing the conditions of internal flow such as velocity and pressure. For a numerical approach the three-dimensional, viscous, unsteady flow field in the pump has been achieved by solving the unsteady Navier-Stokes equations (URANS) with a commercial code. Commercial code ANSYS CFX was used for the calculations. [ABSTRACT FROM AUTHOR]