Artigos de revistas: "Plates (Engineering) Testing Mathematical models"

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Stara, Marie. "Testing of Pre-Stressing Masonry Wall with Using Different Thickness of Anchor Plates". Advanced Materials Research 1082 (dezembro de 2014): 211–15. http://dx.doi.org/10.4028/www.scientific.net/amr.1082.211.

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Contribution deals with experimental measurements of deformations in the place exposed to local load caused by additional pre-stressing. The measurements are made at the masonry brick corner built in the laboratory equipment. The laboratory equipment was designed at Faculty of Civil Engineering VŠB – TU Ostrava for measurement tri-axial stress-strain conditions in masonry. In this brick corner one pre-stressing bar is placed. And on the pre-stressing bar is anchored to the anchor plate which transfer pre-stressing forces to the masonry. The thickness of brick corner is 440mm and anchor plate will be used about thickness 10, 20 and 30mm. Mathematical modelling of brick corner is based on finite element method using software ANSYS and then the results are compared with results of laboratory tests. On the basis of these results it should be possible to improve the models and to approach closer to the accurate and at the same time simple procedure for design of pre-stressed masonry.

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Borkovic, Aleksandar, Dragan Milasinovic, Valentina Golubovic-Bugarski, Ognjen Mijatovic e Manuel Desancic. "Experimental and numerical identification of structural modes for engineering education". Facta universitatis - series: Architecture and Civil Engineering 12, n.º 2 (2014): 161–72. http://dx.doi.org/10.2298/fuace1402161b.

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Development of simple classroom demonstration device and software for visualization of structural normal modes is presented. Device is made of parts of old speaker, controlled with personal computer, where the harmonic motion of solenoid is used as an excitation for beam and plate models. Simple code for finite element free vibration analysis of plates is written in Wolfram Mathematica. Good agreement of results and attractive visual patterns of normal modes attracted attention of students. Results are confirmed using modern modal testing methods. Presented approach is complementary to standard teaching of structural dynamics.

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Gharababaei, H., N. Nariman-zadeh e A. Darvizeh. "A Simple Modelling Method for Deflection of Circular Plates Under Impulsive Loading using Dimensionless Analysis and Singular value Decomposition". Journal of Mechanics 26, n.º 3 (setembro de 2010): 355–61. http://dx.doi.org/10.1017/s1727719100003919.

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AbstractA novel approach of numerical modelling using input-output experimental data pairs is presented for deflection-thickness ratio of circular plates subjected to impulse loading. In this way, singular value decomposition (SVD) method is used in conjunction with dimensionless parameters incorporated in such complex process. The closed-form obtained model shows very good agreement with some testing experimental data pairs which have been unforeseen during the training process. Moreover, two modifications are consequently suggested for some similar models already proposed in previous works. The approach of this paper can generally be applied to model very complex real-world processes using appropriate experimental data.

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Vorobyov, V. S., E. L. Karelina, O. A. Bender e K. V. Katalymova. "STATISTICAL MODELS OF PHYSIC-MECHANICAL CHARACTERISTICS OF ROADS IN THE AREA OF CULVERTS". Vestnik SibADI 15, n.º 4 (12 de setembro de 2018): 560–73. http://dx.doi.org/10.26518/2071-7296-2018-4-560-573.

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Introduction. Increased technical requirements for roads, associated with increasing axial loads, the intensity and speed of vehicles, with the actual technical condition of the roads number, engineering structures, including culverts, activation of federal and regional services to bring the parameters of road surfaces to the world standards, all listed parameters pose the task in developing the mathematical modeling methods of physical-mechanical characteristics of soils in the culverts area. Therefore, such methods allow to reduce economic costs and time for carrying out experimental research of deformations based on the monitoring results of the soil roadbed and pavement.Materials and methods. The order of technical condition of the culverts’ research, pavement and physico-mechanical characteristics of soils, methods of experimental research were discussed in the article. Moreover, the approach to carrying out experimental works on penetration of pits in places of deformations and nearby was approved. Additionally, the evaluation of the soils condition on the roadbed and the annular space of the culverts was made.Results. The schemes of deformation and elasticity, density, humidity, consistency, plasticity number, fluidity, and physical properties of the soil are determined. The engineering-geological elements, mean values of density, humidity and compaction factor are established according to the research aim. Consequently, the values of the strain modules and the modulus of elasticity are calculated on the basis of compression and stamp tests.Discussion and conclusions. The dependence of the pavement on the physic-mechanical characteristics of the soil of the roadbed is proved. The correlation-regression analysis of soil characteristics is performed on the basis of experimental research. As a result, the regression equations are obtained in the annular space of culverts and at the distance of ± 30 m nearby. As could be proved, there are irregularities in the coverage of road clothes caused by drawdown in barrier locations. The physic-mechanical characteristics of the ground and strength characteristics are increased by culverts’ transfer on distance. The application of physic-mechanical characteristics of the soil together with experimental studies makes it possible to reduce labor costs, time and cost of testing.

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Al-Kannoon, Muslim Abdul-Ameer, e Hayder Wafi AL-Thabhawee. "Investigation of flexural and shear failure modes of tapered castellated steel beams using expansion plates". Eastern-European Journal of Enterprise Technologies 4, n.º 7 (118) (30 de agosto de 2022): 6–13. http://dx.doi.org/10.15587/1729-4061.2022.262558.

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Using modern technologies for fabricating steel, I-beams can be easily made by welding, and hot-rolled beams can often be produced at an economical price with slender webs and equal flanges. Experimental and theoretical studies of the behavior of tapered castellated steel beams were carried out. Due to the cost reductions associated with tapered castellated steel beams, they are a feasible alternative to prismatic components. This study assessed the influence of tapered castellation on the bending capacity and flexural stiffness of tapered castellated steel beams (TCBs) with simply supported end conditions experimentally and theoretically. Four three-point bending tests on TCBs with H/h values of 1, 1.2, 1.4 and 1.6 were conducted utilizing a standard parent I-section beam (IPE140) as the control specimen. The test findings include the ultimate load vs. mid-span deflection response curves and failure mechanisms. The testing findings indicated that the TCBs' ultimate load capacity might be up to 140 percent of that of the parent section. The Abaqus program was used to conduct a finite element (FE) analysis of TCB, which allows for material and geometric nonlinearity. The derived finite element models exhibit excellent agreement with the experimental results in terms of ultimate load capacity vs. mid-span deflection response and failure mechanisms. Based on the results of the work, TCBs can be used for increasing the strength and stiffness of the I-section parent beam with adding expansion plates. The maximum load capacity of TCBs can be enhanced when adding expansion plates up to 40 % above that of the parent beam. A TCB has lower ductility than its parent beam. Moreover, a TCB fulfills serviceability requirements since its mid-span depth exceeds that of its parent beam.

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GIORGI, C. "Mathematical models of thin thermoviscoelastic plates". Quarterly Journal of Mechanics and Applied Mathematics 53, n.º 3 (1 de setembro de 2000): 363–74. http://dx.doi.org/10.1093/qjmam/53.3.363.

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Kyvelou, Pinelopi, David A. Nethercot, Nicolas Hadjipantelis, Constantinos Kyprianou e Leroy Gardner. "The Evolving Basis for the Design of Light Gauge Steel Systems". International Journal of Structural Stability and Dynamics 20, n.º 13 (10 de outubro de 2020): 2041008. http://dx.doi.org/10.1142/s0219455420410084.

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The importance of allowing for the many different types of structural interaction that have an effect on the performance of light gauge members when used in practical situations is emphasized. A distinction is drawn between internal interactions involving the various plate elements of the steel profiles and external interactions involving the other components in the system. Although full-scale testing of representative systems can capture this behavior, the costs involved make this an impractical general basis for design; codified methods generally consider only isolated plates within members and isolated members within systems, thereby neglecting the potentially beneficial effects of both forms of interaction. Properly used, modern methods of numerical analysis offer the potential to systematically allow for both forms of interaction — provided the numerical models used have been adequately validated against suitable tests. The use of such an approach is explained and illustrated for three commonly used structural systems: roof purlins, floor beams, and columns in stud walls. In each case, it is shown that, provided sufficient care is taken, the numerical approach can yield accurate predictions of the observed test behavior. The subsequently generated large portfolio of numerical results can then provide clear insights into the exact nature of the various interactions and, thus, form the basis for more realistic design approaches that are both more accurate in their predictions and which lead to more economic designs. Building on this, modifying existing arrangements so as to yield superior performance through specific modifications is now possible. Two such examples, one in which improved interconnection between the components in a system is investigated and a second in which prestressing is shown to provide substantial enhancement for relatively small and simple changes, are presented.

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Kostyleva, Liliya Yu, Oleg V. Loginovskiy, Evgeniya A. Retc e Igor M. Yachikov. "Possibilities of using mathematical models for thermal nondestructive testing of defects in multilayer bimetallic plates". Bulletin of the South Ural State University. Ser. Computer Technologies, Automatic Control & Radioelectronics 22, n.º 1 (janeiro de 2022): 53–64. http://dx.doi.org/10.14529/ctcr220104.

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There is an actual task of delamination detection in multilayer bimetallic materials. Various methods of nondestructive testing (NDT) are used to solve it, including the method of transient thermal NDT. This method consists in remote registration, visualization and analysis of thermal (temperature) fields, which depend on thermophysical and geometric characteristics, thermal effect capacity and internal structure features of the object. The internal structure defects cause the appearance of abnormal temperature zones on the object surface. Their analysis allows us to judge the presence of changes in the material as a whole or in individual areas. It is possible to understand whether there is a defect under the anomalous site, and what its parameters are, if there is an adequate mathematical model that theoretically describes the dependence of the measuring results on the properties of the object and the selected technological modes. This model is a significant component of thermal NDT systems. For the same object or process, a certain set of mathematical models can be compiled, differing in the number of factors taken into account, the assumptions made, the completeness and accuracy of the description of the state of the object or the conditions of the process. The set of factors is determined by the purpose of the study, and in order to unambiguously determine the model of the thermal state, it is necessary to describe the characteristics of the object (geometric shape and thermophysical characteristics of the material) and the heat exchange process (characteristics of heat sources, initial and boundary conditions). Aim. To analyze the existing mathematical models for the research object – a multilayer bimetallic plate with delaminations between the outer and inner layers, and to identify common approaches to modeling the processes of thermal NDT of multilayer objects. Materials and methods. The structure of the mathematical model of the thermal state of the object is determined. An analytical review of mathematical models of thermal NDT of multilayer objects is performed. Results. The requirements, assumptions and limitations for a mathematical model of thermal NDT of a multilayer bimetallic plate with delamination defects are formulated. Conclusion. On the basis of the considered approaches to the mathematical modeling of the thermal state of multilayer objects with ideal layers contact and delamination defects, the necessary factors for the development of a model for the transient thermal NDT processes of the studied objects are determined.

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Prysiazhnyi, Andrii H., Volodymyr V. Kukhar, Vadym Hornostai, Ekaterina Kudinova, Maryna Korenko e Oleksandr S. Anishchenko. "Mathematical Models for Forecasting of 10Mn2VNb Steel Heavy Plates Mechanical Properties". Materials Science Forum 1045 (6 de setembro de 2021): 237–45. http://dx.doi.org/10.4028/www.scientific.net/msf.1045.237.

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The problem urgency for determining the optimal rolling and heat treatment schedules for providing the required indices of heavy plates physical and mechanical properties is shown. The use of statistical mathematical models for solving this problem is substantiated and the methodology for their design is described. Statistical mathematical models were designed using the mathematical statistics methods and Data Mining tools to determine the yield strength, ultimate tensile strength and percent elongation for 10Mn2VNb steel plates rolled under 3600 heavy plate mill conditions. Software for the numerical implementation of these statistical mathematical models has been developed. Applied software has been developed for the numerical implementation of the statistical mathematical models for predicting the heavy plate’s mechanical properties, and high calculation accuracy has been confirmed with the ones help: 95.82% for the yield strength, 96.78% for the ultimate tensile strength, and 91.48% for the percent elongation. The regularities of the influence for finish rolling factual temperature in the finishing stand of 3600 heavy plate mill and the plate thickness on 10Mn2VNb pipe steel physical and mechanical properties were identified by processing the database and using the designed software.

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Feinberg, Alec. "Accelerated Reliability Growth Models". Journal of the IEST 37, n.º 1 (1 de janeiro de 1994): 17–23. http://dx.doi.org/10.17764/jiet.2.37.1.f2u73m8022207868.

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Extending reliability growth so that it can be applied in the area of accelerated testing will enable one to apply all the reliability growth tools and their planning advantages. This paper describes linking these two areas together into what is termed accelerated reliability growth testing (ARGT). Mathematical equations of ARGT for both iso-stress and step-stress accelerated testing are modelled.

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Peeters, Bart, Herman Van der Auweraer e Patrick Guillaume. "Modal Survey Testing and Vibration Qualification Testing: The Integrated Approach". Journal of the IEST 46, n.º 1 (14 de setembro de 2003): 110–18. http://dx.doi.org/10.17764/jiet.46.1.y542012501w0701q.

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In the assessment of the structural integrity and launch-environment survivability of satellite structures, dynamic mathematical models are used for load prediction. These analytical models are test-verified by a modal survey test. Once the vibration environment is specified, the satellite equipment is subjected to shaker excitation in order to reproduce this environment. This paper investigates the possibilities to integrate both the modal survey and the vibration qualification test.

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Luo, F. L., Yun Yu Hu e Z. W. Kang. "Eddy Current Testing Using a Model Based Measurement Method". Key Engineering Materials 295-296 (outubro de 2005): 667–72. http://dx.doi.org/10.4028/www.scientific.net/kem.295-296.667.

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It is important to improve the reliability of the eddy current non-destructive testing. It is generally difficult to reduce the probability of non-detection and the number of false alarms same time. Model Based Measurement (MBM), including estimation of state, failure diagnosis and trend analysis, has excellent results on general estimation. Actual results of MBM vary with the application domain, mathematical model and data processing. The time series model is a description of system in time domain based on equivalent output. The Kalman filter is an efficient method for suppressing the disturbance and improving the state estimation. A new method, called as eddy current testing (ECT) using a model based measurement, is presented. Two time series models are used for the normal status and the abnormal status in ECT. The Kalman filter on these models is applied to give useful information for decision making. Results of the experiment on aluminum plates demonstrate that this method is useful to improve the detection reliability.

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Andjelkovic, Vladimir, Zarko Lazarevic e Velimir Nedovic. "Application of analogous models in civil engineering". Facta universitatis - series: Architecture and Civil Engineering 9, n.º 3 (2011): 395–405. http://dx.doi.org/10.2298/fuace1103395a.

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The paper describes the results of making the mathematical and physical models of the authors, by using analogous methods and materials. There is the mathematical rock mass deformability model as a base for foundation engineering a concrete arch dam and the physical rock slope model which was tested by loading until failure and the results were compared with the calculation procedure. In the first example the correlation is established between the static and the analogous dynamic in situ investigations for creating the mathematical rock mass deformability model. In the second example there is application of the analogous materials for the discontinuity shearing simulation on the physical slope model. The results of the geotechnical in situ investigations and laboratory testing carried out in the Institute for Development of Water Resources "Jaroslav Cerni" in Belgrade were used for making the models.

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Olszak, Artur, Karol Osowski, Zbigniew Kęsy e Andrzej Kęsy. "Modelling and testing of a hydrodynamic clutch filled with electrorheological fluid in varying degree". Journal of Intelligent Material Systems and Structures 30, n.º 4 (6 de janeiro de 2019): 649–60. http://dx.doi.org/10.1177/1045389x18818780.

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The article concerns steady-state characteristics of a hydrodynamic clutch with electrorheological working fluid controlled by changes in strength of electric field and changes in the filling degree. The characteristics were obtained by experimenting, as well as calculations based on one-dimensional mathematical models. While creating the mathematical models, factors taken into consideration included differences between methods controlling the clutch, as well as various ways the working fluid flows in the clutch’s working space, depending on the relation of angular speed of rotors. The resultant mathematical models were verified with experimental research.

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Junevičius, Raimundas, e Marijonas Bogdevičius. "MATHEMATICAL MODELLING OF NETWORK TRAFFIC FLOW". TRANSPORT 24, n.º 4 (31 de dezembro de 2009): 333–38. http://dx.doi.org/10.3846/1648-4142.2009.24.333-338.

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The article describes mathematical models of traffic flows to initiate different traffic flow processes. Separate elements of traffic flow models are made in a way to be connected together to get a single complex model. A model of straight road with different boundary conditions is presented as a separate part of the network traffic flow model. First testing is conducted in case the final point of the whole modelled traffic line is closed and no output from that point is possible. The second test is performed when a constant value of traffic flow speed and traffic flow rate is entered. Mathematical simulation is carried out and the obtained results are listed.

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Сычев, Михаил, Mikhail Sychev, Владимир Минаев, Vladimir Minaev, Александр Фаддеев e Aleksandr Faddeev. "Seismic risk assessment in tourist-recreational areas: mathematical models". Servis Plus 9, n.º 2 (15 de junho de 2015): 25–34. http://dx.doi.org/10.12737/11309.

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The article highlights the problem of evaluation of seismic risks in the tourism and recreational areas. To this end, the grounded and practically being tested mathematical model for evaluating the seismic stability of tourist-recreational area on the example of the Black Sea, the Caspian and the Mediterranean region. This model combines the influences of disturbances associated with the anomalous gravity field (vertical component), and takes into account modern crustal movements (horizontal component), calculated according to the space geodesy. The physical model of the geological environment in the form of a closed homogeneous isotropic elastic space in the form of "plates" with as averaging the values of the density, shear modulus and Young´s modulus is suggested. The geological environment is considered in the framework of Newtonian rheology, that is without taking into account the seismic deformation of energy dissipation. Experimental calculations show good agreement with the results of modeling really occurred in the historically-sky aspect of the catastrophic earthquakes in the study area. Suggested an additional testing model by comparing the orientation of the vectors of the horizontal displacements at the surface, resultingfrom mathematical modeling, containing information on contemporary movements of the earth´s crust according to the space geodesy. The analysis shows that the greatest seismic risk are generally a characteristic of those places of the study area, where the vectors of horizontal displacements in opposite directions, characterized by a helical orientation. The prospects of using the model are describe, if it is considered according to Maxwell rheology of the medium, which allows to take into account the effect of the relaxation of stresses and strains in the rate of accumulation in the subsurface. This approach may allow a quantitative estimation of the seismic deformation energy dissipation, which is very significant in terms of the forecast estimates ofseismicity in the time aspect.

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Changjun, Cheng, e Yang Xiao. "The mathematical models and generalized variational principles of nonlinear analysis for perforated thin plates". Applied Mathematics and Mechanics 17, n.º 2 (fevereiro de 1996): 109–18. http://dx.doi.org/10.1007/bf00122305.

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Cole, I. S., e D. A. Paterson. "Mathematical models of dependence of surface temperatures of exposed metal plates on environmental parameters". Corrosion Engineering, Science and Technology 41, n.º 1 (março de 2006): 67–76. http://dx.doi.org/10.1179/174327806x94045.

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Krysko, A. V., J. Awrejcewicz, K. S. Bodyagina, M. V. Zhigalov e V. A. Krysko. "Mathematical modeling of physically nonlinear 3D beams and plates made of multimodulus materials". Acta Mechanica 232, n.º 9 (26 de junho de 2021): 3441–69. http://dx.doi.org/10.1007/s00707-021-03010-8.

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AbstractIn this work, mathematical models of physically nonlinear plates and beams made from multimodulus materials are constructed. Our considerations are based on the 3D deformation theory of plasticity, the von Mises plasticity criterion and the method of variable parameters of the theory of elasticity developed by Birger. The proposed theory and computational algorithm enable for solving problems of three types of boundary conditions, edge conditions and arbitrary lateral load distribution. The problem is solved by the finite element method (FEM), and its convergence and the reliability of the results are investigated. Based on numerical experiments, the influence of multimodulus characteristics of the material of the beam and the plate on their stress–strain states under the action of transverse loads is illustrated and discussed.

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Koliou, Maria, Andre Filiatrault e Andrei M. Reinhorn. "Seismic Response of High-Voltage Transformer-Bushing Systems Incorporating Flexural Stiffeners II: Experimental Study". Earthquake Spectra 29, n.º 4 (novembro de 2013): 1353–67. http://dx.doi.org/10.1193/072511eqs185m.

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A numerical study conducted on four transformer-bushing models presented in a first companion paper indicated that high-voltage bushings mounted on the cover plates of transformers are more vulnerable to seismic loading than bushings mounted on a rigid base. This would explain why the good performance of bushings mounted on a rigid base observed during shake table testing does not correlate well with their performance in the field. In this second companion paper, the addition of flexural stiffeners on the transformer cover plates as a means to stiffen the base of bushings and mitigate their seismic vulnerability is investigated experimentally. Shake table testing was conducted on a 230 kV porcelain bushing mounted on a support structure incorporating a flexible cover plate and two stiffener configurations. Test results confirmed that stiffening the cover plates is beneficial to the seismic response of high-voltage bushings. Test results are compared to the predictions of finite element analyses.

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Megehee, M. Maria, Ann N. Clarke, Kenton H. Oma e David J. Wilson. "Soil Clean-Up by Surfactant Washing. IV. Modification and Testing of Mathematical Models". Separation Science and Technology 28, n.º 17-18 (dezembro de 1993): 2507–27. http://dx.doi.org/10.1080/01496399308017494.

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Krysko, A. V., J. Awrejcewicz, K. S. Bodyagina e V. A. Krysko. "Mathematical modeling of planar physically nonlinear inhomogeneous plates with rectangular cuts in the three-dimensional formulation". Acta Mechanica 232, n.º 12 (16 de novembro de 2021): 4933–50. http://dx.doi.org/10.1007/s00707-021-03096-0.

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AbstractMathematical models of planar physically nonlinear inhomogeneous plates with rectangular cuts are constructed based on the three-dimensional (3D) theory of elasticity, the Mises plasticity criterion, and Birger’s method of variable parameters. The theory is developed for arbitrary deformation diagrams, boundary conditions, transverse loads, and material inhomogeneities. Additionally, inhomogeneities in the form of holes of any size and shape are considered. The finite element method is employed to solve the problem, and the convergence of this method is examined. Finally, based on numerical experiments, the influence of various inhomogeneities in the plates on their stress–strain states under the action of static mechanical loads is presented and discussed. Results show that these imbalances existing with the plate’s structure lead to increased plastic deformation.

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Mirzakhani, Bahman. "Mathematical Modeling of Flow Behaviour of API-X70 during Hot Torsion Testing". Advanced Materials Research 264-265 (junho de 2011): 60–65. http://dx.doi.org/10.4028/www.scientific.net/amr.264-265.60.

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The flow behaviour of material is strongly influenced by the microstructure evolution during hot deformation processes. In this work, a comprehensive mathematical modelling of heat transfer and plastic deformation was carried out employing finite element analysis based on rigidviscoplastic formulation. Semi-empirical models of dynamic recovery and recrystallization were utilized to develop the microstructure dependent constitutive equations. They were then integrated into the finite element code to simulate stress-strain curve of API-X70 steel during hot deformation process. Hot torsion tests were carried out at various deformation conditions for characterization of microstructure equations and model validation. The good agreement between experimental data and simulation results were achieved. The model predicts work hardening, dynamic recovery and recrystallization simultaneously and it considers their effects on the flow stress of the material during hot deformation.

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Jana, Padrul, Nurchasanah Nurchasanah e Syita Fatih 'Adna. "E-Learning During Pandemic Covid-19 Era: Drill Versus Conventional Models". International Journal of Engineering Pedagogy (iJEP) 11, n.º 3 (20 de maio de 2021): 54. http://dx.doi.org/10.3991/ijep.v11i3.16505.

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Coronavirus Disease 2019 (COVID-19) has been stated by the World Health Organization (WHO) as a pandemic. As a consequence, all teaching and learning processes have been conducted through e-learning. For that reason, this research aims at testing the computer-based drill learning and the conventional learning model through e-learning. The aspect that would be measured is the students’ mathematical reflecting thinking. The research method was the quasi-experimental by employing the pre-test, before the treatment, and the post-test after the treat-ment. The research design employs 2 classes, the 31 students of the control class and 30 ones of experiment class. The result reveals to us that a computer-based drilling learning model would be effective if it is viewed from the perspective of students’ mathematical reflective thinking ability. On the other hand, the conven-tional learning model would not be effectively viewed from the perspective of students’ mathematical reflective thinking.

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Babak, Vitalii, Ihor Bohachev, Artur Zaporozhets, Vladyslav Khaidurov, Valerii Havrysh e Antonina Kalinichenko. "Some Features of Modeling Ultrasound Propagation in Non-Destructive Control of Metal Structures Based on the Magnetostrictive Effect". Electronics 12, n.º 3 (17 de janeiro de 2023): 477. http://dx.doi.org/10.3390/electronics12030477.

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A method and mathematical models of direct and inverse problems of ultrasonic testing and diagnostics of complex metal structures for defects were developed and tested. A prototype of a system for magnetostrictive control of elements of the objects under study was manufactured and experimentally tested. Mathematical simulation of ultrasonic testing processes using MATLAB and the COMSOL Multiphysics software environment was carried out. The adequacy of the mathematical models was verified by the results of their comparison with real physical experiments. Information support and a methodology that implements it was developed, which ensure the functioning of the control facilities for these objects based on the use of small-aperture magnetostrictive transducers. The mathematical identification of the vibration generator in complex building structures was developed, which consists in finding the locations of the generator of ultrasonic vibrations, as well as the characteristics of this vibration generator based on data obtained from sensors in the form of time series.

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van Wees, Daphne A., Chantal den Daas, Mirjam E. E. Kretzschmar e Janneke C. M. Heijne. "Double trouble: modelling the impact of low risk perception and high-risk sexual behaviour on chlamydia transmission". Journal of The Royal Society Interface 15, n.º 141 (abril de 2018): 20170847. http://dx.doi.org/10.1098/rsif.2017.0847.

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Risk perception plays an important role in testing behaviour for sexually transmitted infections, but is rarely included in mathematical models exploring the impact of testing. We explored the impact of incorporating sexual behaviour (SB), risk perception (RP) and differential testing uptake in SB–RP groups on prevalence, using chlamydia as an example. We developed a pair model with a susceptible–infected–susceptible structure representing heterosexuals aged 16–26 years. The effect of testing on chlamydia prevalence was compared between a model with only SB (SB model) and a model with SB and RP (SB–RP model). In the SB–RP model, a scenario without differential testing uptake in SB–RP groups was compared to scenarios with differential testing uptake in SB–RP groups. Introducing testing into the SB–RP model resulted in a slightly smaller reduction in chlamydia prevalence (−38.0%) as compared to the SB model (−40.4%). In the SB–RP model, the scenario without differential testing uptake in SB–RP groups overestimated the reduction in chlamydia prevalence (with 4.8%), especially in the group with high SB and low RP (19.8%). We conclude that mathematical models incorporating RP and differential testing uptake in SB–RP groups improve the impact assessment of testing and treatment on chlamydia prevalence.

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Nguyen, N. T., D. J. Oehlers e M. A. Bradford. "Models for the Flexural Peeling of Angle Plates Adhesively Bonded to R-C Beams". Advances in Structural Engineering 1, n.º 4 (outubro de 1998): 287–300. http://dx.doi.org/10.1177/136943329800100405.

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The strength and stiffness of existing reinforced concrete beams may be enhanced by adhesively bonding angle section members to the soffit/side edges of reinforced concrete (RC) beams. This retrofitting is extremely important in improving the seismic performance of under reinforced RC beams which may suffer ductility problems in earthquakes, or whose strength has deteriorated due to unfavourable environmental factors. This paper develops generic mathematical models for simulating the debonding of angle plates glued to the edges of RC beams as a result of flexural peeling. It is shown that to achieve an accurate model the derivations are quite complex, but the experimental calibration renders the presentation of the model in a simple format. The models have been validated with experimental results.

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INOUE, SHINJI, SHIHO HAYASHIDA e SHIGERU YAMADA. "EXTENDED HAZARD RATE MODELS FOR SOFTWARE RELIABILITY ASSESSMENT WITH EFFECT AT CHANGE-POINT". International Journal of Reliability, Quality and Safety Engineering 20, n.º 02 (abril de 2013): 1350009. http://dx.doi.org/10.1142/s0218539313500095.

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A software hazard rate model is known as one of the important and useful mathematical models for describing the software failure occurrence phenomenon observed in a testing phase. It is difficult to say that the testing environment always constant during a testing phase due to changing the specification and fault target and so forth. Therefore, taking into consideration of the effect of the change in software reliability growth modeling is expected to conduct more accurate software reliability assessment. In this paper, we develop extended software hazard rate models based on well-known Jelinski–Moranda and Moranda models, by considering with a change of testing environment. Especially in this paper, we incorporate the uncertainty of the effect of the change on the software reliability growth process into the software hazard rate modeling. Finally, we show numerical examples for our models and results of model comparisons by using actual data.

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Verdério Júnior, S. A., V. L. Scalon, S. R. Oliveira, P. C. Mioralli e E. Avallone. "DIMENSIONLESS PHYSICAL-MATHEMATICAL MODELING OF TURBULENT NATURAL CONVECTION". Revista de Engenharia Térmica 20, n.º 3 (10 de outubro de 2021): 37. http://dx.doi.org/10.5380/reterm.v20i3.83269.

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Natural convection heat transfer is present in the most diverse applications of Thermal Engineering, such as in electronic equipment, transmission lines, cooling coils, biological systems, etc. The correct physical-mathematical modeling of this phenomenon is crucial in the applied understanding of its fundamentals and the design of thermal systems and related technologies. Dimensionless analyses can be applied in the study of flows to reduce geometric and experimental dependence and facilitate the modeling process and understanding of the main influence physical parameters; besides being used in creating models and prototypes. This work presents a methodology for dimensionless physical-mathematical modeling of natural convection turbulent flows over isothermal plates, located in an “infinite” open environment. A consolidated dimensionless physical-mathematical model was defined for the studied problem situation. The physical influence of the dimensionless numbers of Grashof, Prandtl, and Turbulent Prandtl was demonstrated. The use of the Theory of Dimensional Analysis and Similarity and its application as a tool and numerical device in the process of building and simplifying CFD simulations were discussed.

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Zaoui, Fatima Zohra, Djamel Ouinas, Belkacem Achour, Mabrouk Touahmia, Mustapha Boukendakdji, Enamur R. Latifee, Ahmed A. Alawi Al-Naghi e Jaime Aurelio Viña Olay. "Mathematical Approach for Mechanical Behaviour Analysis of FGM Plates on Elastic Foundation". Mathematics 10, n.º 24 (15 de dezembro de 2022): 4764. http://dx.doi.org/10.3390/math10244764.

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This paper presents the flexural analysis of functionally graded plates resting on elastic foundations using new two-dimensional (2D) and quasi-three-dimensional (quasi-3D) higher order shear deformation theories. The main interesting feature of this theory is that it proposes a new displacement field with undetermined integral variables which involves only five unknown functions, unlike other shear and normal deformation theories, hence making it easier to use. A parabolic transverse shear deformation shape function satisfying the zero shear stress conditions on the plate outer surfaces is considered. The elastic foundation follows the Pasternak mathematical model. The material properties change continuously across the thickness of the FG plate using different distributions: power law, exponential, and Mori–Tanaka models. The governing equations of FG plates subjected to sinusoidal and uniformly distributed loads are established through the principle of virtual works and then solved via Navier’s procedure. In this work, a detailed discussion on the influence of material composition, geometric parameters, stretching effect, and foundation parameters on the deflection, axial displacements, and stresses is given, and the obtained results are compared with those published in previous works to demonstrate the accuracy and the simplicity of the present formulations. The different obtained results were found to be in good agreement with the available solutions of other higher-order theories. The proposed model is able to represent the cross section warping in the deformed shape and to demonstrate the validity and efficiency of the approach, the findings reported herein prove that this theory is capable of predicting displacements and stresses more accurately than other theories, as its results are closer when compared to numerical methods reported in other literatures.

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Haffar, Muhammad Ziad, Balázs Kövesdi e Sándor Adany. "Buckling of compressed plates with closed-section longitudinal stiffeners: Two new mathematical models for resistance prediction". Structures 33 (outubro de 2021): 3526–39. http://dx.doi.org/10.1016/j.istruc.2021.06.083.

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Geng, Ling Xin, Li Juan Zhang e Ren Zhi Wu. "Dynamic Study on Vehicle Hydro-Pneumatic Suspension". Advanced Materials Research 139-141 (outubro de 2010): 2653–57. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.2653.

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The performance of HPS directly influences the comfort of vehicle, dynamic load of wheels and travel distance of suspension. In order to describe and evaluate the performance of HPS, the structure and working principle of main parts of the HPS are introduced and analyzed in this paper firstly. Then the physical model is founded by analyzing and simplifying the structure of HPS. According to the physical model, non-linear mathematical models of HPS with dual gas-accumulators are built up and a special program is composed. The results of computer simulation are carried out through the program. Then a testing rig for HPS is designed and manufactured after rebuilding cylinders and abundant experiments are performed on the testing rig. Comparisons are drawn between the results of simulation and testing, which manifest the mathematical model of HPS built in the thesis is feasible.

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Semenov, Serhii, Zhang Liqiang, Cao Weiling e Viacheslav Davydov. "Development a mathematical model for the software security testing first stage". Eastern-European Journal of Enterprise Technologies 3, n.º 2 (111) (30 de junho de 2021): 24–34. http://dx.doi.org/10.15587/1729-4061.2021.233417.

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This paper reports an analysis of the software (SW) safety testing techniques, as well as the models and methods for identifying vulnerabilities. An issue has been revealed related to the reasoned selection of modeling approaches at different stages of the software safety testing process and the identification of its vulnerabilities, which reduces the accuracy of the modeling results obtained. Two steps in the process of identifying software vulnerabilities have been identified. A mathematical model has been built for the process of preparing security testing, which differs from the known ones by a theoretically sound choice of the moment-generating functions when describing transitions from state to state. In addition, the mathematical model takes into consideration the capabilities and risks of the source code verification phase for cryptographic and other ways to protect data. These features generally improve the accuracy of modeling results and reduce input uncertainty in the second phase of software safety testing. An advanced security compliance algorithm has been developed, with a distinctive feature of the selection of laws and distribution parameters that describe individual state-to-state transitions for individual branches of Graphical Evaluation and Review Technique networks (GERT-networks). A GERT-network has been developed to prepare for security testing. A GERT-network for the process of checking the source code for cryptographic and other data protection methods has been developed. A graphic-analytical GERT model for the first phase of software safety testing has been developed. The expressions reported in this paper could be used to devise preliminary recommendations and possible ways to improve the effectiveness of software safety testing algorithms

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Aidossov, Allayarbek, Galym Aidosov e Saltanat Narbayeva. "Construction of mathematical models of the stressed-strained state of a material with a porous water-saturated base under dynamic load". Eastern-European Journal of Enterprise Technologies 5, n.º 7 (113) (29 de outubro de 2021): 25–35. http://dx.doi.org/10.15587/1729-4061.2021.238978.

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Materials of beams, plates, slabs, strips have been commonly applied in various fields of industry and agriculture as flat elements in the structures for machinery and construction. They are associated with the design of numerous engineering structures and facilities, such as the foundations of various buildings, airfield and road surfaces, floodgates, including underground structures. This paper reports a study into the interaction of the material (of beams, plates, slabs, strips) with the deformable base as a three-dimensional body and in the exact statement of a three-dimensional problem of mathematical physics under dynamic loads. The tasks of studying the interaction of a material (beams, plates, slabs, strips) with a deformable base have been set. A material lying on a porous water-saturated viscoelastic base is considered as a viscoelastic layer of the same geometry. It is assumed that the lower surface of the layer is flat while the upper surface, in a general case, is not flat and is given by some equation. Classical approximate theories of the interaction of a layer with a deformable base, based on the Kirchhoff hypothesis, have been considered. Using the well-known hypothesis by Timoshenko and others, the general three-dimensional problem is reduced to a two-dimensional one relative to the displacement of points of the median plane of the layer, which imposes restrictions on external efforts. In the examined problem, there is no median plane. Therefore, as the desired values, displacements and deformations of the points in the plane have been considered, which, under certain conditions, pass into the median plane of the layer. It is not possible to find a closed analytical solution for most problems while experimental studies often turn out to be time-consuming and dangerous processes

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Koliou, Maria, Andre Filiatrault e Andrei M. Reinhorn. "Seismic Response of High-Voltage Transformer-Bushing Systems Incorporating Flexural Stiffeners I: Numerical Study". Earthquake Spectra 29, n.º 4 (novembro de 2013): 1335–52. http://dx.doi.org/10.1193/072511eqs184m.

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High-voltage bushings have exhibited vulnerability during past earthquakes. The good performance of bushings mounted on a rigid base observed during shake table testing does not correlate well with their performance in the field. It is suspected that the seismic performance of high-voltage bushings is improved when mounted on a rigid base, as opposed to when mounted on more flexible cover plates of transformers. In this first of two companion papers, the seismic response of bushings was investigated numerically for various mounting conditions. The addition of flexural stiffeners on the transformer cover plates was explored as a means to stiffen the base of the bushings and mitigate their seismic vulnerability. Linear dynamic analyses conducted on four transformer-bushing system models showed that the simple approach of stiffening the cover plates of transformers is beneficial to the seismic response of high-voltage bushings.

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Abdallah, Wafaa, Jacqueline Saliba, Ziubir-Mehdi Sbartaï, Marwan Sadek, Fadi Hage Chehade e S. Mohammed ElAchachi. "Reliability analysis of non-destructive testing models within a probabilistic approach". MATEC Web of Conferences 281 (2019): 04003. http://dx.doi.org/10.1051/matecconf/201928104003.

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The diagnosis of reinforced concrete is essential to detect the degradation and thus maintain the structural performance of civil engineering structures. This paper aims to establish a mathematical relationship between the ultrasonic pulse velocity UPV (considered as an observable variable) and two concrete properties indicators (compressive strength fc and water content W) within a probabilistic framework. Synthetic simulations are proposed to derive a conversion model between the statistical properties of the output and the input parameters for a reinforced concrete structure by taking into account spatial variability of concrete.

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Zhao, Chunjuan, Xiangyu Zhao, Shanbo Chen, Jisong Yu e Lei Zhang. "Encapsulation Based Method for Natural Frequency Identification of Deployable Solar Arrays with Multiple Plates". Shock and Vibration 2021 (26 de novembro de 2021): 1–13. http://dx.doi.org/10.1155/2021/7443312.

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The ground modal test is an important approach to the natural frequency of solar arrays to support the attitude control of spacecraft. However, for the batch production of small satellites, the accuracy and efficiency of traditional ground modal testing methods are limited. This shortcoming restricts the development of satellite constellations. Based on the encapsulation method widely used in the computer field, this paper proposed a natural frequency identification method of deployable solar arrays with multiple plates. This method is of high accuracy and efficiency that meets the demand of attitude control and makes sense to accelerate the batch production of small satellites. First, a suspended modal test system with gravity compensation function is designed. Second, the mathematical model of the test system is established. Abstracting parts of the parameters of the test object into an encapsulated entity, the mathematical model is simplified by equivalent variables. Thus, the direct mapping relationship between the ground test result and the true natural frequency is proposed. Finally, to verify the identification accuracy, finite element analysis (FEA) and the ground modal test of a two-folder solar array simulant are carried out. The results show that the relative error of the first-order natural frequency after correction and the theoretical value is less than 3%. Meanwhile, the identification accuracy of the ground modal test is improved by more than 50%. This method improves the availability of ground test results and reduces the calculation amount, so that it is convenient for engineering applications.

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Scholey, Jonathan J., Paul D. Wilcox, C. K. Lee, Michael I. Friswell e M. R. Wisnom. "Acoustic Emission in Wide Composite Specimens". Advanced Materials Research 13-14 (fevereiro de 2006): 325–32. http://dx.doi.org/10.4028/www.scientific.net/amr.13-14.325.

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Acoustic emission (AE) is an attractive technique for the structural health monitoring (SHM) of aerospace systems. To reach its full potential in this role a quantitative approach must be adopted to study damage mechanisms in composite materials. In this paper, some of the practical issues regarding acoustic emission testing in composites are addressed. A model describing Lamb wave propagation through plates is described and used to make phase velocity and attenuation measurements in both aluminium and carbon fibre reinforced plastic plates. Results are then implemented in the frequency domain to conduct an experimental study of normal incidence Lamb wave reflections. Comparisons are made with finite element analysis (FEA) models with good results.

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Ryken, Timothy C., John Kim, Brent D. Owen, Gary E. Christensen e Joseph M. Reinhardt. "Engineering patient-specific drill templates and bioabsorbable posterior cervical plates: a feasibility study". Journal of Neurosurgery: Spine 10, n.º 2 (fevereiro de 2009): 129–32. http://dx.doi.org/10.3171/2008.11.spi0817677.

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Object The authors describe a method of using computer models to generate customized cervical implants. A promising yet challenging technique in cervical spine surgery involves the use of pedicle screws to assist with posterior instrumentation. Surrounding anatomical structures such as the vertebral arteries and cervical nerve roots present challenges for safe screw placement; however, the use of computer-generated templates seems to be a promising method to assist with placement. In this study, the authors explore the use of computer-generated templates and introduce their methods for creating custom, bioabsorbable posterior cervical implants. Methods The cervical spines (C2–T1) from 4 cadavers were scanned with volumetric CT. Using commercially available software, the authors generated volumetric models of a cervical drill template and the mold for a cervical plate spanning a desired number of vertebrae. The computer generated models of the cervical drill template and cervical plate mold were converted into physical models using a rapid prototyping machine. The biopolymer polylactic acid resin was heated to 250°C and resolidified to form thin ~ 5-mm-thick plates. The newly formed plates were reheated to 60°C and cast on the cervical mold. Results The resulting translucent plates were found on visual inspection to have a secure lock-and-key fit on the original cadaver spine, and the techniques used were robust and reproducible. The process described in this brief report provides the background to proceed with development and testing of these patient-absorbable templates. Conclusions The creation and use of patient-specific bioabsorbable posterior cervical plates in conjunction with multilevel drill templates appear promising. Additional feasibility studies are planned, and in vitro studies are required to determine the safety and efficacy of using patient-specific drill templates and converting them into bioabsorbable implants.

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AbdelMeguid, Hossam, Piotr Skworcow e Bogumil Ulanicki. "Mathematical modelling of a hydraulic controller for PRV flow modulation". Journal of Hydroinformatics 13, n.º 3 (6 de janeiro de 2011): 374–89. http://dx.doi.org/10.2166/hydro.2011.024.

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This paper describes the development of mathematical models, which represent static and dynamic properties of the AQUAI-MOD® hydraulic controller coupled with a standard pressure reducing valve (PRV) as well as a new experimental set-up for testing the controller and calibrating and validating the models. The purpose of the AQUAI-MOD® controller is to modulate the PRV outlet pressure according to the valve flow. The controller has been experimentally tested to assess its operation in different conditions and operating ranges and in all cases showed good performance. The mathematical models of the PRV and its controller have been developed and solved using the Mathematica software package to represent both steady state and dynamics conditions. The numerical results of simulation of the mathematical model have been compared with experimental data and showed a good agreement in magnitude and trends. The model can be used to simulate the behaviour of the PRV and the AQUAI-MOD® hydraulic controller in typical network applications. It can also be used at the design stage to size the controller components and to compute the required set points for the minimum and the maximum pressure before installing the controller in the field.

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Resch, M., e R. Scheidl. "A model for fluid stiction of quickly separating circular plates". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, n.º 9 (31 de outubro de 2013): 1540–56. http://dx.doi.org/10.1177/0954406213509613.

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Fluid stiction is a force which is created by the average pressure difference between a fluid-filled, narrow, quickly opening gap and the surrounding pressure. It plays a negative role in compressor valve technology and in fast switching valves, since it hinders an immediate response of the valves to a changing driving force situation. In this paper, the axisymmetric fluid stiction problem is studied by analytical mathematical models and experiments performed on a specific test rig. The study shows that the stiction force in narrow gaps is dominated by the viscous flow as described by the Reynolds equation for lubricating gaps and by cavitation which occurs in a centre region if the gap opening speed exceeds a critical value. The cavitation zone first extends and then shrinks and, finally, gives rise to complex oscillation phenomena due to the impact of the fluid when the cavitation zone collapses. It was found experimentally that fluids can create negative pressure for very short time. Measures to limit the stiction force are a large initial gap height or additional fluid supply channels from the surrounding to the gap.

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Pindado, Santiago, Javier Cubas e Félix Sorribes-Palmer. "On the Analytical Approach to Present Engineering Problems: Photovoltaic Systems Behavior, Wind Speed Sensors Performance, and High-Speed Train Pressure Wave Effects in Tunnels". Mathematical Problems in Engineering 2015 (2015): 1–17. http://dx.doi.org/10.1155/2015/897357.

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At present, engineering problems required quite a sophisticated calculation means. However, analytical models still can prove to be a useful tool for engineers and scientists when dealing with complex physical phenomena. The mathematical models developed to analyze three different engineering problems: photovoltaic devices analysis; cup anemometer performance; and high-speed train pressure wave effects in tunnels are described. In all cases, the results are quite accurate when compared to testing measurements.

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Mao, Qian Jun. "Transfer Heat Mechanism of Oil-Gas-Water Three-Phase Flow in Pipeline". Advanced Materials Research 199-200 (fevereiro de 2011): 1609–12. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.1609.

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It is well known that the oil-gas-water three-phase flow belongs to the field of multiphase flow,transfer heat mechanism of which is very complicated.Transfer heat mechanism is affected not only by different buries in oil gathering pipeline, but also by soil temperature periodicity change. Both domestic and oversea scholars have already studied on the transfer heat mechanisms of oil-gas-water three phase,but they are still in the level of fundamental theory and laboratory.This paper establishes transfer heat models of the oil-gas-water three-phase flow in buried oil gathering pipeline, including the physical model and the mathematical model,and testing in experiment .The purpose of this paper is to analyze value between the calculation and the testing . The results show that the mathematical model of this paper is accurate , and the relative error is ≤ 10%.

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Tran, Minh, Jonathan Binns, Shuhong Chai, Alexander L. Forrest e Hung Nguyen. "A practical approach to the dynamic modelling of an underwater vehicle propeller in all four quadrants of operation". Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 233, n.º 1 (30 de novembro de 2017): 333–44. http://dx.doi.org/10.1177/1475090217744906.

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This article presents the open water propeller characteristics and the four-quadrant propeller models as applied to a torpedo-shaped underwater vehicle. A series of experiments with a Gavia autonomous underwater vehicle propeller were conducted in the towing tank using a rotor testing apparatus. The purpose of these tests was to measure the propeller thrust and torque under varying flow conditions and then to be used as the basis of the developed propeller models. These mathematical models were constructed using two regression models, a polynomial and a Fourier series. Model coefficients were derived using the method of least squares and a comparison analysis was also conducted to test the robustness of the methodology. Results show that the Fourier series models were able to produce a reasonable and accurate approximation of thrust and torque coefficients with a small number of parameters in the examined condition of this study. The obtained four-quadrant open water characteristics of the autonomous underwater vehicle propeller model would be utilised to improve the system mathematical model for more accurate simulation and controller design, to compare the autonomous underwater vehicle performance equipped with different propulsion units, and to validate computational fluid dynamic results.

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Kapski, Denis, Valery Kasyanik, Oleksii Lobashov, Aleksandra Volynets, Oleg Kaptsevich e Andrii Galkin. "Estimating the Parameters of Traffic Flows on the Basis of Processing of Localization Data on the Movement of Vehicles". Communications - Scientific letters of the University of Zilina 21, n.º 2 (24 de maio de 2019): 89–99. http://dx.doi.org/10.26552/com.c.2019.2.89-99.

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The article describes the method of estimating the parameters of transport flows using the two-fluid mathematical model of Herman-Prigogine and developed and based on the proposed method of estimating the parameters of the system on the basis of passive processing of navigation data on the movement of vehicles. The efficiency of the proposed algorithms, mathematical models for estimating the parameters of road traffic flow and system as a whole was confirmed during its testing using a set of tracks on the main highways of Commonwealth of Independent States.

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Vilenskiy, O., S. Dushev, D. Lapshin e Ya Lebedeva. "COMPUTATIONAL ANALYSIS OF THE IMPACT ACTION IN THE DESIGN OF THE TOOLING FOR EQUIPMENT TESTING". PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. SERIES: NUCLEAR AND REACTOR CONSTANTS 2019, n.º 3 (26 de setembro de 2019): 14–29. http://dx.doi.org/10.55176/2414-1038-2019-3-14-29.

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Described are state-of-the-art approaches to solving the problems associated with impact testing of the equipment under development at the design stage. A brief description is provided of an experimental facility that models in different directions the impact loads equivalent to the effect of a blast wave originated near the object. The topicality is emphasized of developing - based upon the calculational mathematical analysis - the safe process tooling that prevents any possibility of accident consequences. The capabilities of ANSYS/LS-DYNA, a state-of-the-art computing system, are elucidated in brief. In ANSYS/LS-DYNA, full-scale mathematical 3D-modeling is implemented that enables a sufficiently deep and detailed analysis of dynamic processes through the use of a finite element method. Described are analytical and experimental methods of studying the deformation models of structural materials under static and dynamic loads, and determined are parameters of the mathematical models (Jonson-Cook models, Allen model, Rule & Jones, Cowper-Symonds model) from the LS-DYNA library. With account of the safety requirements in the regulatory documents, the deformation criteria are employed to assess the dynamic strength of the structural materials used to manufacture the tooling. Following the results of the mathematical analysis of the impact action, the tooling has been designed that enables successful testing at a safe level. The specified parameters have been reached that are in the technical requirements for the developed equipment - the obtained accelerations are maximally close to the calculated ones. Thanks to the integrated approach to the computational analysis that covered the engineering-and-design, physical-mechanical, mathematical and regulatory aspects, an opportunity has come to abandon the excessive conservatism and thus to fit well into the specified overall dimensions of the item and to reduce the specific metal content of the final product. Abandoning the multivariate progressive approximations in the analysis of the tooling at the design stage resulted also in the shortened design time and in the reduced design cost.

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Kwiecień, Sławomir. "Influence of Load Plates Diameters, Shapes of Columns and Columns Spacing on Results of Load Plate Tests of Columns Formed by Dynamic Replacement". Sensors 21, n.º 14 (16 de julho de 2021): 4868. http://dx.doi.org/10.3390/s21144868.

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The dynamic replacement method is used to strengthen the subgrade of objects, usually up to 5 to 6 m thick. After the improvement process, acceptance tests in the form of load testing are carried out. Interpretation of the test results can cause some difficulties. Dynamic replacement results in a situation where columns of different shapes, loaded with plates of diameters usually smaller than the head diameter and in the vicinity of adjacent columns, are subjected to load tests. In order to demonstrate the influence of these factors, a spatial model of soil strengthened by dynamic replacement, comprising four material zones, was calibrated on the basis of load testing. The following models were used in the analysis: linear-elastic, elastic–perfectly plastic (Coulomb–Mohr) and elastic–plastic with isotropic hardening (Modified Cam-Clay). This formed the basis for 105 numerical models, which took into account the actual shapes of the columns made at various spacings, subjected to load tests with plates of various diameters. The analyses of the settlements, calculated moduli and stress distribution in the loaded system showed how the results were significantly influenced by mentioned factors. This implies that the interpretation of the results of load tests should be based on advanced spatial numerical analyses, using appropriate constitutive models and including the considered factors.

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Ashimov, Abdykappar, e Yuriy V. Borovskiy. "Testing one developed model by the parametric control theory methods". Kybernetes 44, n.º 6/7 (1 de junho de 2015): 1094–106. http://dx.doi.org/10.1108/k-01-2015-0006.

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Purpose – The purpose of this paper is to demonstrate an effectiveness of applying a number of the new methods, proposed in the parametric control theory for testing macroeconomic models for the possibility of their practical application. Design/methodology/approach – Approaches of system analysis on building and calibrating the mathematical models; provisions of the parametric control theory for both numerical testing of the calibrated models for the possibility of their practical application and solving the parametric control problems. Findings – First, one global computable general equilibrium model (CGE model) is built and calibrated. Second, in solving the problem of testing this model for the possibility of its practical application the effectiveness of applying two developed numerical algorithms is demonstrated. These algorithms are for estimating stability indicators and estimating stability (in the sense of the theory of smooth mappings stability) of mappings defined by the model. Third, on the base of the tested CGE model there are given the solution results for a number of the parametric control problems aimed at economic growth and decrease of economic disparities of regions. Originality/value – By the example of the developed CGE model, it is demonstrated an approach of the parametric control theory for testing macroeconomic models for the possibility of their practical application.

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Li, Yi, Chao Li, Qiu-Sheng Li, Yong-Gui Li e Fu-Bin Chen. "Refined Mathematical Models for Across-Wind Loads of Rectangular Tall Buildings with Aerodynamic Modifications". International Journal of Structural Stability and Dynamics 21, n.º 09 (20 de maio de 2021): 2150131. http://dx.doi.org/10.1142/s0219455421501315.

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This paper aims to systematically study the across-wind loads of rectangular-shaped tall buildings with aerodynamic modifications and propose refined mathematic models accordingly. This study takes the CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall building as a benchmark model and conducts a series of pressure measurements on the benchmark model and four CAARC models with different round corner rates (5%, 10%, 15% and 20%) in a boundary layer wind tunnel to investigate the across-wind dynamic loads of the typical tall building with different corner modifications. Based on the experimental results of the five models, base moment coefficients, power spectral densities and vertical correlation coefficients of the across-wind loads are compared and discussed. The analyzed results shown that the across-wind aerodynamic performance of the tall buildings can be effectively improved as the rounded corner rate increases. Taking the corner round rate and terrain category as two basic variables, empirical formulas for estimating the across-wind dynamic loads of CAARC standard tall buildings with various rounded corners are proposed on the basis of the wind tunnel testing results. The accuracy and applicability of the proposed formulas are verified by comparisons between the empirical formulas and the experimental results.

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Johnston, D. N., e J. E. Drew. "Measurement of Positive Displacement Pump Flow Ripple and Impedance". Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 210, n.º 1 (fevereiro de 1996): 65–74. http://dx.doi.org/10.1243/pime_proc_1996_210_437_02.

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The secondary source method forms the British Standard for pump fluid-borne noise testing. This is a powerful technique but requires care in order to produce accurate results. This paper describes practical aspects for implementing the method. The requirements for the test rig, data acquisition system and analysis are detailed. The British Standard specifies that either mathematical modelling or linear interpolation is used on the source impedance measurements. A method for smoothing the impedance results is described in this paper, which is shown to give more repeatable results than linear interpolation. Some physically realistic mathematical models of pump impedance are described, and their use in determining the internal flow ripple discussed.

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