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1
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.
Testo completoAbstract (sommario):
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.
2
Gao, Feng, Gui Ling Liu e Qing Guo Huang. "Ultrasonic Non-Destruction Detecting Method for Concrete Compression Strength". Advanced Materials Research 724-725 (agosto 2013): 1585–88. http://dx.doi.org/10.4028/www.scientific.net/amr.724-725.1585.
Testo completoAbstract (sommario):
Regional materials and mixing ratio of Datong area are used to make the concrete testing blocks. The rebounding and ultrasonic non-destruction detecting testing for concrete strength were done by using the six types of strength grades concrete standard specimens according to the technical regulation. On the basis of regression analysis with least squares technique, the mathematical models between rebounding values, ultrasonic velocity values, rebounding-ultrasonic method values and concrete compression strength were set up by three kinds of functions’ regression analysis. The error analysis showed that the rebounding-ultrasonic non-destruction detecting testing method has higher precision results and the practical value.
3
Gao, Feng, Gui Ling Liu e Feng Xian Wang. "Concrete Compression Strength Non-Destruction Detecting with Rebounding and Ultrasonic Synthesis Method". Applied Mechanics and Materials 357-360 (agosto 2013): 1488–91. http://dx.doi.org/10.4028/www.scientific.net/amm.357-360.1488.
Testo completoAbstract (sommario):
Regional materials and mixing ratio in Datong region are used to make the concrete testing blocks. The rebounding and ultrasonic non-destruction detecting testing for concrete compression strength were done by using the six types of strength grades concrete standard specimens according to the technical regulation. By using the common software Matlab7.0, the mathematical models between rebounding values, ultrasonic velocity values, rebounding- ultrasonic method values and concrete compression strength were set up by three kinds of functions’ regression analysis. The error analysis showed that the rebounding-ultrasonic non-destruction detecting testing method had higher precision results and was used firstly when the conditions were permitted, compared with the rebounding testing method or the ultrasonic testing method.
4
Sarsam, Saad I. "Modeling the Thermal Behavior of the Viscoelastic Properties of Asphalt Concrete". Britain International of Exact Sciences (BIoEx) Journal 4, n. 2 (2 settembre 2022): 79–91. http://dx.doi.org/10.33258/bioex.v4i2.729.
Testo completoAbstract (sommario):
The viscoelastic properties of asphalt concrete are susceptible to the variation in the pavement temperature. In the present work, asphalt concrete beam specimens were prepared at optimum binder content and tested under repeated flexural stresses for fatigue life. Three testing temperature were implemented (5, 20, and 30) ℃. The variation in the phase angle, dissipated energy, flexural stiffness, and permanent deformation due to the testing temperatures were monitored and modeled. It was concluded that the viscoelastic properties of asphalt concrete are highly sensitive to the variation in testing temperature. The phase angle and the permanent deformation increases sharply as the testing temperature rises. However, the dissipated energy and the flexural stiffness declines as the testing temperature rise. Mathematical models were obtained which can be implemented in identifying the thermal behavior of the viscoelastic properties of asphalt concrete.
5
Andjelkovic, Vladimir, Zarko Lazarevic e Velimir Nedovic. "Application of analogous models in civil engineering". Facta universitatis - series: Architecture and Civil Engineering 9, n. 3 (2011): 395–405. http://dx.doi.org/10.2298/fuace1103395a.
Testo completoAbstract (sommario):
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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Zainal, S. M. Iqbal S., Farzad Hejazi, Farah N. A. Abd Aziz e Mohd Saleh Jaafar. "Constitutive Modeling of New Synthetic Hybrid Fibers Reinforced Concrete from Experimental Testing in Uniaxial Compression and Tension". Crystals 10, n. 10 (1 ottobre 2020): 885. http://dx.doi.org/10.3390/cryst10100885.
Testo completoAbstract (sommario):
Hybridization of fibers in concrete yields a variety of applications due to its benefits compared to conventional concrete or concrete with single type-fiber. However, the Finite Element (FE) modeling of these new materials for numerical analyses are very challenging due to the lack of analytical data for these specific materials. Therefore, an attempt has been made to develop Hybrid Fiber Reinforced Concrete (HyFRC) materials with High Range Water-Reducing Admixture (HRWRA) during the concrete mixing process and conduct experimental study to evaluate the behavior of the proposed materials. Constitutive models for each of the materials are formulated to be used as analytical models in numerical analyses. The acquired data are then used to formulate mathematical equations, governing the stress–strain behavior of the proposed HyFRC materials to measure the accuracy of the proposed models. The experimental testing indicated that the Ferro with Ferro mix-combination improved the performance of concrete in the elastic stage while the Ferro with Ultra-Net combination has the highest compressive strain surplus in the plastic stage. In tension, the Ferro with Ferro mix displayed the highest elastic behavior improvement while the Ferro with Ultra-Net designs proved superior in the plastic range, providing additional toughness to conventional concrete.
7
Bouaanani, Najib, Patrick Paultre e Jean Proulx. "Dynamic response of a concrete dam impounding an ice-covered reservoir: Part I. Mathematical modelling". Canadian Journal of Civil Engineering 31, n. 6 (1 dicembre 2004): 956–64. http://dx.doi.org/10.1139/l04-075.
Testo completoAbstract (sommario):
This paper examines the dynamic response of a concrete dam impounding an ice-covered reservoir and subjected to forced-vibration testing. The analytical research presented is a follow-up to an extensive dynamic testing program carried out on a 84-m high concrete gravity dam located in northeastern Quebec, Canada, under harsh winter conditions, including a 1.0- to 1.5-m-thick ice sheet covering the reservoir. One of the major challenges encountered when analyzing ice-dam-reservoir-foundation interaction is modelling the complex nature of the ice and the boundary conditions governing reservoir motion. The problem is further complicated because there are little or no appropriate experimental data and observational evidence relevant to ice-dam interaction processes. Some of these challenges are addressed herein using a two-dimensional analytical approach, which investigates the effects due to ice cover, water compressibility, and reservoir bottom absorption. A frequency-domain substructure method technique is used and a new boundary condition along the ice-cover-reservoir interface is proposed. The technique developed is implemented in a finite element code specialized in the seismic analysis of concrete dams. Numerical results are discussed in the companion paper in this issue. Key words: gravity dams, concrete dams, ice, reservoirs, mathematical models, ice-structure interaction, fluid-structure interaction, forced-vibration testing, finite elements modelling.
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Amin, Muhammad Nasir, Kaffayatullah Khan, Fahid Aslam, Muhammad Izhar Shah, Muhammad Faisal Javed, Muhammad Ali Musarat e Kseniia Usanova. "Multigene Expression Programming Based Forecasting the Hardened Properties of Sustainable Bagasse Ash Concrete". Materials 14, n. 19 (28 settembre 2021): 5659. http://dx.doi.org/10.3390/ma14195659.
Testo completoAbstract (sommario):
The application of multiphysics models and soft computing techniques is gaining enormous attention in the construction sector due to the development of various types of concrete. In this research, an improved form of supervised machine learning, i.e., multigene expression programming (MEP), has been used to propose models for the compressive strength (fc′), splitting tensile strength (fSTS), and flexural strength (fFS) of sustainable bagasse ash concrete (BAC). The training and testing of the proposed models have been accomplished by developing a reliable and comprehensive database from published literature. Concrete specimens with varying proportions of sugarcane bagasse ash (BA), as a partial replacement of cement, were prepared, and the developed models were validated by utilizing the results obtained from the tested BAC. Different statistical tests evaluated the accurateness of the models, and the results were cross-validated employing a k-fold algorithm. The modeling results achieve correlation coefficient (R) and Nash-Sutcliffe efficiency (NSE) above 0.8 each with relative root mean squared error (RRMSE) and objective function (OF) less than 10 and 0.2, respectively. The MEP model leads in providing reliable mathematical expression for the estimation of fc′, fSTS and fFS of BA concrete, which can reduce the experimental workload in assessing the strength properties. The study’s findings indicated that MEP-based modeling integrated with experimental testing of BA concrete and further cross-validation is effective in predicting the strength parameters of BA concrete.
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Souza, L. A. F. de, e R. D. Machado. "Numerical-computational analysis of reinforced concrete structures considering the damage, fracture and failure criterion". Revista IBRACON de Estruturas e Materiais 6, n. 1 (febbraio 2013): 101–20. http://dx.doi.org/10.1590/s1983-41952013000100006.
Testo completoAbstract (sommario):
The experimental results of testing structures or structural parts are limited and, sometimes, difficult to interpret. Thus, the development of mathematical-numerical models is needed to complement the experimental analysis and allow the generalization of results for different structures and types of loading. This article makes two computational studies of reinforced concrete structures problems found in the literature, using the Finite Element Method. In these analyses, the concrete is simulated with the damage classical model proposed by Mazars and the steel by a bilinear elastoplastic constitutive model. Numerical results show the validity of the application of constitutive models which consider the coupling of theories with the technique of finite element discretization in the simulation of linear and two-dimensional reinforced concrete structures.
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Meruane, Viviana, Sergio J. Yanez, Leonel Quinteros e Erick I. Saavedra Flores. "Damage Detection in Steel–Concrete Composite Structures by Impact Hammer Modal Testing and Experimental Validation". Sensors 22, n. 10 (20 maggio 2022): 3874. http://dx.doi.org/10.3390/s22103874.
Testo completoAbstract (sommario):
Steel–concrete composite systems are an efficient alternative to mid- and high-rise building structures because of their high strength-to-weight ratio when compared to traditional concrete or steel constructive systems. Nevertheless, composite structural systems are susceptible to damage due to, for example, deficient construction processes, errors in design and detailing, steel corrosion, and the drying shrinkage of concrete. As a consequence, the overall strength of the structure may be significantly decreased. In view of the relevance of this subject, the present paper addresses the damage detection problem in a steel–concrete composite structure with an impact-hammer-based modal testing procedure. The mathematical formulation adopted in this work allows for the identification of regions where stiffness varies with respect to an initial virgin state without the need for theoretical models of the undamaged structure (such as finite element models). Since mode shape curvatures change due to the loss of stiffness at the presence of cracks, a change in curvature was adopted as a criterion to quantify stiffness reduction. A stiffness variability index based on two-dimensional mode shape curvatures is generated for several points on the structure, resulting in a damage distribution pattern. Our numerical predictions were compared with experimentally measured data in a full-scale steel–concrete composite beam subjected to bending and were successfully validated. The present damage detection strategy provides further insight into the failure mechanisms of steel–concrete composite structures, and promotes the future development of safer and more reliable infrastructures.
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Sococol, Ion, Petru Mihai, Ionuţ-Ovidiu Toma, Ioana Olteanudonţov e Vasile-Mircea Venghiac. "Stress-Strain Relation Laws for Concrete and Steel Reinforcement Used in Non-Linear Static Analytical Studies of the Moment Resisting Reinforced Concrete (RC) Frame Models". Bulletin of the Polytechnic Institute of Iași. Construction. Architecture Section 67, n. 1 (1 marzo 2021): 17–29. http://dx.doi.org/10.2478/bipca-2021-0002.
Testo completoAbstract (sommario):
Abstract Following the previous analytical studies performed with ATENA software for a series of RC moment resisting frame models, it were used in the pre-processing stage the stress-strain relation laws for concrete and steel reinforcement. These mathematical and graphical relations represent a necessity in the current conditions of numerical analysis and imply a correct knowledge of the deformation mode of the „reinforced concrete” which is a composite material. Thus, it is desired through this research paper the theoretical exposition of: equivalent uniaxial law for concrete, biaxial compressive failure and tensile failure consideration laws for concrete, bilinear with hardening law for steel reinforcement, cycling steel reinforcement model and steel reinforcement bond model. Finally, it will be possible to validate the correctness of the analytical RC frame systems through the experimental results of the optimal RC frame model after seismic platform testing.
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Dey, Alinda, Akshay Vijay Vastrad, Mattia Francesco Bado, Aleksandr Sokolov e Gintaris Kaklauskas. "Long-Term Concrete Shrinkage Influence on the Performance of Reinforced Concrete Structures". Materials 14, n. 2 (6 gennaio 2021): 254. http://dx.doi.org/10.3390/ma14020254.
Testo completoAbstract (sommario):
The contribution of concrete to the tensile stiffness (tension stiffening) of a reinforced concrete (RC) member is a key governing factor for structural serviceability analyses. However, among the current tension stiffening models, few consider the effect brought forth by concrete shrinkage, and none studies take account of the effect for very long-term shrinkage. The present work intends to tackle this exact issue by testing multiple RC tensile elements (with different bar diameters and reinforcement ratios) after a five-year shrinking time period. The experimental deformative and tension stiffening responses were subjected to a mathematical process of shrinkage removal aimed at assessing its effect on the former. The results showed shrinkage distinctly lowered the cracking load of the RC members and caused an apparent tension stiffening reduction. Furthermore, both of these effects were exacerbated in the members with higher reinforcement ratios. The experimental and shrinkage-free behaviors of the RC elements were finally compared to the values predicted by the CEB-fib Model Code 2010 and the Euro Code 2. Interestingly, as a consequence of the long-term shrinkage, the codes expressed a smaller relative error when compared to the shrinkage-free curves versus the experimental ones.
13
Bolborea, Bogdan, Sorin Dan, Cornelia Baeră, Aurelian Gruin, Felicia Enache e Ion Aurel Perianu. "Study Regarding the Evaluation of Prediction Models for Determining the Concrete Compressive Strength Using Non-Destructive Testing (NDT) Data: Validation Stage". Solid State Phenomena 332 (30 maggio 2022): 173–81. http://dx.doi.org/10.4028/p-5w046c.
Testo completoAbstract (sommario):
In the evaluation of an existing reinforced concrete structure, a fundamental issue is determining the concrete compressive strength as accurately as possible. This process can be conducted by using destructive and non-destructive methods. The destructive method presumes a limited number of cores extracted from the concrete structure. A higher number of cores would affect the structural safety and is time and resource consuming. Therefore, the conclusions drawn using exclusively this method can also generate errors in correctly estimating the load bearing capacity of a structure, thus leading to the possibility of implementing deficient measures in order to ensure a structural safety. Data obtained via non-destructive methods are more comprehensive. Due to their non-destructive nature, there are no limitations regarding the number of elements investigated and are fast in delivering results. One of the main concerns of researchers in this field is developing a direct relationship between the measured indicators through non-destructive testing (NDT) methods and concrete compressive strength. Over the years different equations with different mathematical structure (linear, polynomial, power, exponential and logarithmic) were developed with the main purpose of delivering fast and accurate results concerning concrete compressive strength by the means of NDT. The aim of this paper is to validate some of the most important prediction models using an original set of data. The database consists in a number of 96 concrete cores that were subjected to Ultrasonic Pulse Velocity (UPV) and Schmidt Rebound Hammer (SRH) testing. The accuracy of the results was determined by using two statistical parameters the mean absolute error (MAE) and mean absolute percentage error (MAPE). The proposed equations have been analyzed in terms of prediction and dispersion of values. It was noticed that some of the formulations predict values that are higher than the ones obtained destructively, others provide a larger dissipation of values, while some equations deliver a compact distribution of results with higher rate in terms of accuracy. This study proposes a data validation of some of the most popular empirical equations, used for the estimation of the concrete compressive strength, elaborated through the years, using a new set of data.
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Murashkin, Vasily G. "Features of Nonlinear Deformation of Concrete". Scientific journal “ACADEMIA. ARCHITECTURE AND CONSTRUCTION”, n. 1 (18 marzo 2019): 128–32. http://dx.doi.org/10.22337/2077-9038-2019-1-128-132.
Testo completoAbstract (sommario):
In most studies, when the problem of determining a nonlinear model of deformation of structural concrete in normal environment, or experienced a variety of destructive (aggressive, temperature, etc.) exposure, using individual mathematical apparatus and software. The main criterion in these works for the construction of the deformation model of concrete was a unique relationship "strength - modulus of elasticity". Apply the developed model for another type of concrete or experienced a destructive impact was erroneous. However, not all features of concrete deformation in the construction of models were taken into account. In particular, the gentle nature of deformation in the initial stage of loading was not taken into account. Similarly, models of nonlinear deformation of concrete in normative materials of different countries are constructed. Especially there are problems in the inspection of structures operated for along time. It is not rational to create individual models based on the algorithm created earlier. In recent studies, a number of works have noted the need to take into account the features of the initial stage ofloading of concrete and the fact that concrete from the beginning ofloading has macro and micro cracks and structural defects. But even in these works the possibility of creating a nonlinear deformation model based on experimentally obtained data when testing prototypes of generalized model was not considered. This article discusses the possibility of constructing a concrete extracted from the structure. The possibility of replacing the individual deformation models with the proposed one is shown. In the generalized model of deformation "strength and modulus of elasticity" may not coincide with the normative characteristics and it can serve as a basis for determining the stress state in the survey of operated structures and, if necessary, for the design of new ones.
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Buchta, Vojtech. "Experimental Testing the Interaction of Fiber-Concrete Foundation Slab and Subsoil and Compare the Results with Numerical Models". Advanced Materials Research 1020 (ottobre 2014): 227–32. http://dx.doi.org/10.4028/www.scientific.net/amr.1020.227.
Testo completoAbstract (sommario):
We solve interaction between the foundation base and the subsoil in civil engineering quite often. For the determination of stress in foundation structure is needed to determine the influence of the stiffness respectively pliability of subsoil to structural internal forces, and vice versa, how the stiffness of the foundation structure affects the resulting subsidence. It is necessary to compare the mathematical models with the actual behavior of the real structure. In 2013 was realised static load on testing equipment in the campus of Faculty of Civil Engineering, VSB–TU Ostrava. Dimensions of test element was 2000 x 2000 x 170 mm and the concrete slab was reinforced with steel fiber type DRAMIX 3D 65/60B6. During measurements were performed and recorded: tensometrical measurement on the surface of the slab, tensometrical measurement inside the slab, measuring the vertical load, measurement of the vertical deformation, measuring the stress on the interface of the slab and soil. Were also developed numerical models of this test in program Nexis. Comparison the test results with numerical models are presented in this paper. [1,9]
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Zambon, Ivan, Anja Vidović e Alfred Strauss. "Reliability of Existing Concrete Structures Determined with Physical Models - Carbonation Induced Corrosion". Solid State Phenomena 259 (maggio 2017): 255–60. http://dx.doi.org/10.4028/www.scientific.net/ssp.259.255.
Testo completoAbstract (sommario):
The main goal of transportation infrastructure management is to optimize the use of infrastructure in the most beneficiary way while respecting the predefined requirements. One of the crucial parts in management strategy is the prediction of behaviour of vital transportation elements. Used prediction models should accurately describe the process of degradation and allow forecasting of structural condition by considering environment, usage and maintenance actions. Deterioration models can be divided into mathematical (statistical), physical and empirical models. Statistical models are based on data that describe condition of structure, such as for example condition rating. Physical models describe damage-causing processes and empirical models are experience based. The focus of this paper is to present the physical model of carbonation in assessment of performance of existing reinforced concrete structures in transportation networks. Assessment is done through determining the probability of limit state of depassivation. In order to determine the carbonation without testing, a special attention has to be given to environmental and material parameter identification. Herein, the identification takes into account weather specifics and construction practice in Austria. Finally, the reliability of existing reinforced concrete structures for combination of different exposure classes and material characteristics is analysed. Based on the analysis of reliability, the carbonation nomogram for engineering use is presented, showing the reliability indices β for the service life of 50 years.
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Mohamad, Baylasan, Soleman Alamoudi e Abd alrahman Issa. "Prediction of Mechanical Properties of Local Concrete in Compression Using Artificial Neural Networks". Association of Arab Universities Journal of Engineering Sciences 27, n. 1 (31 marzo 2020): 105–21. http://dx.doi.org/10.33261/jaaru.2019.27.1.012.
Testo completoAbstract (sommario):
Mechanical properties of concrete are highly dependent on the local materials used in its preparation. experiments on ready mix concrete in our region illustrate the actual behavior of concrete produced by local materials. Six standard cylinders (D=150mm, H=300mm) were casted of most ready mix concrete in central area in Syria (13 of them) covering a wide range of compressive strength . Tests were carried out using a testing machine which gives the applied force values and the corresponding displacement simultaneously until failure. The mean curves representing the (stress-strain) relationship of concrete in compression are drawn, from which the mechanical properties of each mixture were derived, such modulus of elasticity compressive strength , and the corresponding strain . Artificial neural networks were trained on experimental test results (using MATLAB). The laws of concrete behaviour were well assimilated by Artificial neural networks, which is possible to be used as an alternative method of available models of stress-strain relationship, by predicting the curve directly for various concrete mixtures prepared using local materials with different mixing ratios, or a complementary method through the adoption of an appropriate mathematical model and then predict its parameters ( ، ، ). ANNs proved their ability to predict mechanical properties of concrete better than linear regression equations, which promises a more accurate and comprehensive prediction.
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Bouaanani, Najib, Patrick Paultre e Jean Proulx. "Dynamic response of a concrete dam impounding an ice-covered reservoir: Part II. Parametric and numerical study". Canadian Journal of Civil Engineering 31, n. 6 (1 dicembre 2004): 965–76. http://dx.doi.org/10.1139/l04-076.
Testo completoAbstract (sommario):
This paper presents a numerical and parametric study of the effect of an ice cover on the dynamic response of a concrete dam using the approach proposed in the companion paper in this issue. The method was programmed and implemented in a finite element code specialized for the seismic analysis of concrete dams. The 84-m-high Outardes 3 concrete gravity dam in northeastern Quebec was chosen as a model for this research. Some basic aspects of the numerical model are established in this paper and we show that the ice cover affects the dynamic response of the ice–dam–reservoir system. Main features of this influence are emphasized and discussed in a parametric study through the analysis of: (i) acceleration frequency response curves at the dam crest, (ii) hydrodynamic frequency response curves inside the reservoir, and (iii) the hydrodynamic pressure distribution on the upstream face of the dam. Key words: gravity dams, concrete dams, ice, reservoirs, mathematical models, ice–structure interaction, fluid–structure interaction, forced-vibration testing, finite elements modelling.
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Serbenyuk, Symon. "On Some Aspects of the Examination in Econometrics". Journal of Vasyl Stefanyk Precarpathian National University 8, n. 3 (3 novembre 2021): 7–16. http://dx.doi.org/10.15330/jpnu.8.3.7-16.
Testo completoAbstract (sommario):
Teaching econometrics has been studied by a number of researchers, however, there is little information available on the quality of examination and on simplification of tests for demonstration the high-quality knowledge by students in concrete topics of econometrics or mathematical economics.One can note the following main goals of studying the basics of mathematical economics or econometrics by students: forming the notions of mathematical model and of modeling economic processes and phenomena; understanding a role of using mathematical models for economics research and obtaining scientific results; formatting skills for constructing mathematical models in economics, for solving economics problems by mathematical modeling.The main goal of this paper is to simplify test tasks, is to help to students to demonstrate the high-quality knowledge in certain areas of mathematical economics, and also is to construct a system of testing tasks, in which the emphasis was placed on the knowledge and understanding of an algorithm of solving the problem.In the present paper, to quality examine the student knowledge in the basics of mathematical economics, a certain system of tests was constructed and is considered. The main attention is also given to algorithms and techniques of solving some tasks (problems) of mathematical economics. The following topics of mathematical economics are viewed: constructing mathematical models of linear programming, the input-output model, the Monge-Kantorovich transportation problem, the simplex method of linear programming, the graphic method of linear and nonlinear programming, the method of Lagrange multipliers in mathematical optimization. Some primary basic results of studying linear programming, nonlinear programming, and the input-output model are noted.A new system of tests that satisfies the aim of this paper is modeled. The described tests require less time for solving than usual tasks. Here we do not focus on the repetition of auxiliary mathematical knowledge and arithmetic skills. These tests are simplified versions of standard tasks and help students to demonstrate knowledge in the mentioned topics of mathematical economics. The tasks are focused only on the knowledge of basic formulas, techniques, and connections between mathematical objects, economic systems, and their elements.
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Ďurinová, Michaela, e Matúš Kozel. "Non-Destructive Evaluation of Asphalt Concrete Materials Performance During their Life Cycle Based on Accelerated Pavement Testing". Civil and Environmental Engineering 17, n. 2 (1 dicembre 2021): 621–28. http://dx.doi.org/10.2478/cee-2021-0062.
Testo completoAbstract (sommario):
Abstract The characteristics of asphalt concrete materials (ACM) composing the surfacing layer of a bituminous pavement must fulfil a requirement to maintain a level of operational capability demanded by national standards of a given country. ACM’s are a subject to significant stress caused by traffic load and climate conditions, this leads to changes in their physico-mechanical properties. The loss of physico-mechanical properties causes deterioration of road surface characteristics. Since these changes occur throughout the ACM’s life cycle, it is necessary to know the deterioration curves related to loading and time in mathematical terms, i.e. functions describing the initiation and progression of pavement’s defect in time. Pavement Performance Models (PPM) ascertained by non-destructive testing are used to objectively express the surface properties of pavements and their deterioration. The methodology consists of an analytical method to ascertain physico-mechanical characteristics of ACM’s and the use of experimental accelerated pavement testing (APT) facilities.
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Bekheet, Wael, Yasser Hassan e AO Abd El Halim. "Modelling in situ shear strength testing of asphalt concrete pavements using the finite element method". Canadian Journal of Civil Engineering 28, n. 3 (1 giugno 2001): 541–44. http://dx.doi.org/10.1139/l01-011.
Testo completoAbstract (sommario):
Rutting is one of the well-recognized road surface distresses in asphalt concrete pavements that can affect the pavement service life and traffic safety. Previous studies have shown that the shear strength of asphalt concrete pavements is a fundamental property in resisting rutting. Laboratory investigation has shown that improving the shear strength of the asphalt concrete mix can reduce surface rutting by more than 30%, and the SUPERPAVE mix design method has acknowledged the importance of the shear resistance of asphalt mixes as a fundamental property in resisting deformation of the pavement. An in situ shear strength testing facility was developed at Carleton University, and a more advanced version of this facility is currently under development in cooperation with the Transportation Research Board and the Ontario Ministry of Transportation. In using this facility, a circular area of the pavement surface is forced to rotate about a normal axis by applying a torque on a circular plate bonded to the surface. The pavement shear strength is then related to the maximum torque. This problem has been solved mathematically in the literature for a linear, homogeneous, and isotropic material. However, the models for other material properties are mathematically complicated and are not applicable to all cases of material properties. Therefore, developing a model that can accurately analyze the behaviour of asphalt concrete pavements during the in situ shear test has proven pivotal. This paper presents the development of a three-dimensional finite element model that can simulate the forces applied while measuring the shear strength of the asphalt concrete pavement. A comparison between the model results and those obtained from available analytical models and field measurements proved the accuracy of the developed model.Key words: shear strength, in situ testing, finite element, asphalt, pavement, modelling.
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Epure, Dănuţ-Tiberius, Adrian Micu, Irina Susanu e Angela-Eliza Micu. "Model for implementing a reengineering solution of the production process in a printing house". Analele Universitatii "Ovidius" Constanta - Seria Matematica 21, n. 1 (1 marzo 2013): 83–99. http://dx.doi.org/10.2478/auom-2013-0005.
Testo completoAbstract (sommario):
Abstract The main objective of the present paper is to highlight the importance and impact of the concept of reengineering, both by identifying certain opportunities to improve the performance of Romanian printing companies and some strategies of total redesign of the production process based on highlighting some of their effective combinations as well as the integration of some proper mathematical models. First of all, this study will focus on achieving results that are based on identifying some specific problems that companies have faced at a certain point and on concrete problem solving solutions. Second, there should be emphasized that reengineering works in almost any situation related to a big or small company or the production area or NGOs. Specific objectives: designing and testing a mathematical model that can be adapted to the specific activities of the printing organization, providing the best solution of variable allocation to increase performance.
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Xing, Feng, Xiang Yong Guo, Fa Guang Leng, Kun He Fang e Ren Yu Zhang. "Study on Distribution Feature of Fracture Toughness of Interface between Coarse Aggregate and Hardened Cement Mortar in Concrete". Key Engineering Materials 302-303 (gennaio 2006): 514–20. http://dx.doi.org/10.4028/www.scientific.net/kem.302-303.514.
Testo completoAbstract (sommario):
Based on available test data and fracture criterion, by using probability fracture mechanics and mathematical statistical method, the distribution feature of fracture toughness, IC K , of interface between coarse aggregate and hardened cement mortar is analyzed, and a method of defining the least number of specimens for testing fracture toughness is provided. Weibull distribution or lognormal distribution is often used to analyze lifetime problem, so the two models are preferentially considered. The analysis shows that the fracture toughness conforms to lognormal distribution with degree of confidence g =0.9, relative deviation d =0.05 and the least number of specimens of 13. The study results can be used in the probability fracture analysis and construction quality control of interface between coarse aggregate and hardened cement mortar.
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Gribanova, Ekaterina. "Elaboration of an Algorithm for Solving Hierarchical Inverse Problems in Applied Economics". Mathematics 10, n. 15 (5 agosto 2022): 2779. http://dx.doi.org/10.3390/math10152779.
Testo completoAbstract (sommario):
One of the key tools in an organization’s performance management is the goal tree, which is used for solving both direct and inverse problems. This research deals with goal setting based on a model of the future by presenting the goal and subgoal in the form of concrete quantitative and qualitative characteristics and stepwise formation of factors. A stepwise solution to a factor generation problem is considered on the basis of mathematical symmetry. This paper displays an algorithm for solving hierarchical inverse problems with constraints, which is based on recursively traversing the vertices that constitute the separate characteristics. Iterative methods, modified for the case of nonlinear models and the calculation of constraints, were used to generate solutions to the subproblems. To realize the algorithm, the object-oriented architecture, which simplifies the creation and modification of software, was elaborated. Computational experiments with five types of models were conducted, and the solution to a problem related to fast-food restaurant profit generation was reviewed. The metrics of remoteness from set values and t-statistics were calculated for the purpose of testing the received results, and solutions to the subproblems, with the help of a mathematical package using optimization models and a method of inverse calculations, were also provided. The results of computational experiments speak to the compliance of the received results with set constraints and the solution of separate subproblems with the usage of the mathematical package. The cases with the highest solution accuracy reached are specified.
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Martynov, V., O. Martynova, S. Makarova e O. Vietokh. "METHOD FOR CALCULATING THE COMPOSITION OF CELLULAR CONCRETE". Bulletin of Odessa State Academy of Civil Engineering and Architecture, n. 83 (4 giugno 2021): 77–85. http://dx.doi.org/10.31650/2415-377x-2021-83-77-85.
Testo completoAbstract (sommario):
The analysis of existing methods for calculating concrete compositions was carried out. The characteristics and sequence of the calculation-experimental and experimental-calculation methods for the selection of concrete compositions are provided. The advantages and disadvantages of each of the methods are described. These methods are generalized by the general systemic cycle PDCA (Deming cycle), which is determined by the sequence of actions: P (plan) ‒ D (do) ‒ C (check) ‒ A (Action). It was established that for calculating the compositions of the cellular method there is no universal method, which would ensure the achievement of the required strength and average density at the same time. Based on the above, the aim of the thesis was formulated. The aim of the thesis is to develop a method for calculating the composition of cellular concrete, based on experimental-statistical models, which would ensure the production of concrete with the required properties while minimizing the cost of raw materials. A calculation algorithm, a block diagram and a computer program for designing cellular concrete compositions based on experimental-statistical modeling were developed. Using the example of the specified block diagram for calculating concrete compositions, the sequence of calculations is described in detail. The essence of the calculations is that the three-factor mathematical model of the property parameter of cellular concrete, which is supposed to be guaranteed, leads to a second order equation. After that, the roots of the equation are determined. They are substituted into a mathematical model and the composition of concrete is determined in natural values of variable factors. After that, the cost of the composition is determined, which is entered into the data array. Then one of the factors changes, according to the set step and the cycle repeats. At the last stage, the formed data array is processed and the composition with the minimum cost of materials is determined. Testing of the developed software was carried out by processing and calculating a three factor experiment. As a result, the composition of cellular concrete which provides the required strength of foam concrete with a minimum cost of materials, was determined.
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Yukun, Hu, Yao Jitao, Ma Pengfei, Cheng Zhengjie e Zhang Luyang. "Comment and Improvement on the Methods for Deriving Structural Resistance Design Value". Mathematical Problems in Engineering 2022 (7 ottobre 2022): 1–13. http://dx.doi.org/10.1155/2022/2198299.
Testo completoAbstract (sommario):
With the increasing emphasis on sustainability, more and more environmentally friendly new materials and structures are developed, but they are difficult to be applied in engineering practice due to the lack of mature force resistance models. The design assisted by the testing method proposed by ISO2394:2015 and EN1990:2002 can solve this problem effectively. The aim of this paper was to analyze the characteristics of the method from a mathematical and statistical point of view based on the data and to suggest improvements. The resistance of each concrete member was derived by the design assisted by testing methods. The derivation results showed that the p values, the number of tests n , the coefficient of variation θ , and the coefficient of variation of resistance V R known or unknown have a large impact on the derived results. Also, the derivation by the Bayesian procedure or interval estimation methods might be negative. This indicates that the theory of the method is not rigorous and has some disadvantages.
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Krus, Yurii. "CONNECTION BETWEEN STRESSES AND STRAINS OF CONCRETE UNDER DIFFERENT FORCE MODES OF SHORT-TERM AXIAL COMPRESSION". Technical Sciences and Technologies, n. 1(27) (2022): 184–98. http://dx.doi.org/10.25140/2411-5363-2022-1(27)-184-198.
Testo completoAbstract (sommario):
Modern design of bended reinforced concrete constructions uses analytical methods of calculation involving deformative models, the main tool of which is the actual diagram of concrete state, which establishes the connection between its stressesband relative strains bin compressed and tensile zones of the cross-section. Currently, there is no a unified methodics of establishing such a diagram, and researchers obtain it by indirect methods that differ from each other. That is why the graph-analytical building and mathematical description of the functional dependence of the diagram of concrete state based on clearand accurate physical representations we consider as an important and urgent problem.The lackof a unifiedmethodics for obtaining a diagram of concrete state cast doubt the reliability of the results of the calculations carried out, does not allow to compare, explain and link into a unifiedwhole the many experimental and theoret-ical data accumulated by generations of researchers.In a number of scientific publications, an opinion is expressed that a diagram of concrete state can be obtained by simultaneous using of diagrams of concrete deforming under different force modes of short-term axial compression –«soft» and «rigid», testing standard concrete specimens to failure at a constant rate of stress and strains growth respectively. If the «soft» force mode without unnecessary difficulties can be realized on traditional hydraulic presses, the creation of «rigid» mode requires the manufacture of different from standard special presses or auxiliary devices, capable of taking efforts and unloading concrete after reaching the maximum of compressive stresses. The lack of a unified approach to obtaining diagrams of deforming under rigid-mode loadings leads to contradictory results.Insufficiently investigated in the general problem are the issues of theoretical justification, development and approbation of diagram of concrete rigid-mode deforming bb~, complex application of which simultaneously with the diagram of de-forming bb~in conditions of «soft»force mode will allow to obtain a reliable and convincing diagram of concrete state.The main purpose of the research is a graph-analytical building and mathematical description of the dependence bb~, based on clear and accurate physical representations, which experimental obtaining causes serious technical difficulties and eco-nomic costs, and the accuracy of measurements made and the reliability of the results obtained causes big doubts.The article develops the criteria to which the dependence bb~should correspond, based on modern ideas about the nature of strength and deforming and following from the essence of physical and mechanical processes in concrete; the ade-quate structure of the functional connection has been established; the boundary conditions have been drawn up and constant coefficients have been determined; a comparative analysis of the calculation results using the proposed dependence with the corresponding experimental data was performed.As a result, an easy-to-use and mathematical processing of an approximate function of the diagram of deforming is proposed, which reflects the dependence between stresses and strains of concrete under the «rigid» mode of homogeneous compression. Its simultaneous use with the previously obtained diagram for soft-mode loading makes it possible to graphically build and mathematically describe a stable and free from excessive influencing factors the diagram of concrete state, suitable for based on the deformative model of cross-sections of modern calculations of bended reinforced concrete constructions for all groups of limiting states and assessment of the heterogeneous stress-strain state of constructional cross-sections at any stage of loading up to fracture.
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Krantovska, Olena, Mykola Petrov, Liubov Ksonshkevych, Matija Orešković, Sergii Synii e Nelli Іsmailovа. "Numerical simulation of the stress-strain state of complex-reinforced elements". Tehnički glasnik 13, n. 2 (17 giugno 2019): 110–15. http://dx.doi.org/10.31803/tg-20190417112619.
Testo completoAbstract (sommario):
The article describes a developed technique of a numerical simulation of the stress-strain state of complex-reinforced elements, which allows you to create models of double-span continuous. The performed experimental and theoretical studies allowed us to carry out the testing of the developed design model and to justify the reliability of the proposed numerical simulation methodology. The results of the experimental studies were compared with those of the theoretical studies. The theoretical calculus algorithm was developed by using the finite element method. Theoretical calculations were performed by using the mathematical-graphical environment software system LIRA-SOFT and the mathematical and computer program MATLAB. On the basis of the experimental research, the iso-fields of displacements and stresses in the materials of an eccentrically compressed beam with a small bend of the slab were constructed, which collapse behind the inclined narrow strip of concrete and displacements and stresses in the materials of the eccentrically stretched beam, which is destroyed due to the yield of the upper mounting armature.
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Al-Abdaly, Nadia Moneem, Salwa R. Al-Taai, Hamza Imran e Majed Ibrahim. "Development of prediction model of steel fiber-reinforced concrete compressive strength using random forest algorithm combined with hyperparameter tuning and k-fold cross-validation". Eastern-European Journal of Enterprise Technologies 5, n. 7 (113) (29 ottobre 2021): 59–65. http://dx.doi.org/10.15587/1729-4061.2021.242986.
Testo completoAbstract (sommario):
Because of the incorporation of discontinuous fibers, steel fiber-reinforced concrete (SFRC) outperforms regular concrete. However, due to its complexity and limited available data, the development of SFRC strength prediction techniques is still in its infancy when compared to that of standard concrete. In this paper, the compressive strength of steel fiber-reinforced concrete was predicted from different variables using the Random forest model. Case studies of 133 samples were used for this aim. To design and validate the models, we generated training and testing datasets. The proposed models were developed using ten important material parameters for steel fiber-reinforced concrete characterization. To minimize training and testing split bias, the approach used in this study was validated using the 10-fold Cross-Validation procedure. To determine the optimal hyperparameters for the Random Forest algorithm, the Grid Search Cross-Validation approach was utilized. The root mean square error (RMSE), coefficient of determination (R2), and mean absolute error (MAE) between measured and estimated values were used to validate and compare the models. The prediction performance with RMSE=5.66, R2=0.88 and MAE=3.80 for the Random forest model. Compared with the traditional linear regression model, the outcomes showed that the Random forest model is able to produce enhanced predictive results of the compressive strength of steel fiber-reinforced concrete. The findings show that hyperparameter tuning with grid search and cross-validation is an efficient way to find the optimal parameters for the RF method. Also, RF produces good results and gives an alternate way for anticipating the compressive strength of SFRC
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Khan, Kaffayatullah, Mudassir Iqbal, Muhammad Raheel, Muhammad Nasir Amin, Anas Abdulalim Alabdullah, Abdullah M. Abu-Arab e Fazal E. Jalal. "Prediction of Axial Capacity of Concrete Filled Steel Tubes Using Gene Expression Programming". Materials 15, n. 19 (7 ottobre 2022): 6969. http://dx.doi.org/10.3390/ma15196969.
Testo completoAbstract (sommario):
The safety and economy of an infrastructure project depends on the material and design equations used to simulate the performance of a particular member. A variety of materials can be used in conjunction to achieve a composite action, such as a hollow steel section filled with concrete, which can be successfully utilized in the form of an axially loaded member. This study aims to model the ultimate compressive strength (Pu) of concrete-filled hollow steel sections (CFSS) by formulating a mathematical expression using gene expression programming (GEP). A total of 149 datapoints were obtained from the literature, considering ten input parameters, including the outer diameter of steel tube (D), wall thickness of steel tube, compressive strength of concrete (fc’), elastic modulus of concrete (Ec), yield strength of steel (fv), elastic modulus of steel (Es), length of the column (L), confinement factor (ζ), ratio of D to thickness of column, and the ratio of length to D of column. The performance of the developed models was assessed using coefficient of regression R2, root mean squared error RMSE, mean absolute error MAE and comparison of regression slopes. It was found that the optimal GEP Model T3, having number of chromosomes Nc = 100, head size Hs = 8 and number of genes Ng = 3, outperformed all the other models. For this particular model, R2overall equaled 0.99, RMSE values were 133.4 and 162.2, and MAE = 92.4 and 108.7, for training (TR) and testing (TS) phases, respectively. Similarly, the comparison of regression slopes analysis revealed that the Model T3 exhibited the highest R2 of 0.99 with m = 1, in both the TR and TS stages, respectively. Finally, parametric analysis showed that the Pu of composite steel columns increased linearly with the value of D, t and fy.
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NETESA, M. I., A. V. KRASNYUK, A. M. NETESA e N. A. NIKIFOROVA. "OPTIMIZATION OF CONCRETE COMPOSITIONS WITH SECONDARY INDUSTRIAL PRODUCTS". Bridges and tunnels: Theory, Research, Practice, n. 19 (27 luglio 2021): 51–61. http://dx.doi.org/10.15802/bttrp2021/233874.
Testo completoAbstract (sommario):
Purpose. Analyze scientific publications on the existing problems of environmental pollution by secondary industrial products. Search for ways to solve these issues through the rational use of concrete in construction with additives of secondary industrial products, especially fine-grained ones. Determination of rational compositions of medium-strength concrete with the minimum required consumption of cement and filler from iron ore dressing wastes of mining and processing plants. Methodology. To achieve this goal, the experience of improving the structure and properties of concrete by introducing complex additives based on secondary industrial products into its composition is analyzed. The following materials were used for the research: Portland cement CEM 41.7 from Krivoy Rog; as a large aggregate – crushed granite with a maximum grain size of 20 mm; fine aggregate – river quartz sand; mineral additives – products of concentration of iron ores of the Southern Mining and Processing Plant. The experiment was carried out on certified equipment. Control specimens with a side of 10 cm were formed. The compressive strength of concrete was determined according to a standard procedure. Based on the results of the mathematical analysis, graphical dependences of the change in the optimized characteristics on the variable parameters – the consumption of cement, the products of concentration of iron ores and the plasticizer – were built. Findings. Based on the results of testing the samples, the calculation of mathematical models of the experiment was carried out and polynomials of the third degree were obtained for the optimized parameters – the average strength of the samples and the coefficient of efficiency of using cement. The following patterns can be distinguished. The strength of concrete depends to the greatest extent on the consumption of cement in the composition of the concrete mixture and increases significantly with an increase in its content within the studied limits. With an increase in the filler content in the studied range, the strength of concrete, and, accordingly, the coefficient of efficiency of using cement increases with a decrease in the content of cement in the composition of the concrete mixture. Originality. The studies carried out make it possible to determine the main regularities of increasing the efficiency of cement use when utilizing local secondary industrial products in concrete, namely, the introduction of iron ore dressing waste from mining and processing plants as a fine-grained additive in concrete. It was found that it is possible to obtain the required low concrete strength with a significantly lower cement consumption by ensuring a rational grain size composition of the concrete mixture components. Practical value. When designing concrete compositions with a high coefficient of cement utilization, it is necessary to use the obtained research results, providing cement savings and utilizing a significant amount of fine-grained secondary industrial products.
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Vandamme, Matthieu. "Two models based on local microscopic relaxations to explain long-term basic creep of concrete". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, n. 2220 (dicembre 2018): 20180477. http://dx.doi.org/10.1098/rspa.2018.0477.
Testo completoAbstract (sommario):
In this study, we propose an exhaustion model and an adapted work-hardening model to explain the long-term basic creep of concrete. In both models, the macroscopic creep strain originates from local microscopic relaxations. The two models differ in how the activation energies of those relaxations are distributed and evolve during the creep process. With those models, at least up to a few dozen MPa, the applied stress must not modify the rate at which those relaxations occur, but only enables the manifestation of each local microscopic relaxation into an infinitesimal increment of basic creep strain. The two models capture equally well several phenomenological features of the basic creep of concrete. They also make it possible to explain why the indentation technique enables the quantitative characterization of the long-term kinetics of logarithmic creep of cement-based materials orders of magnitude faster than by macroscopic testing. The models hint at a physical origin for the relaxations that is related to disjoining pressures.
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Khan, Kaffayatullah, Babatunde Abiodun Salami, Arshad Jamal, Muhammad Nasir Amin, Muhammad Usman, Majdi Adel Al-Faiad, Abdullah M. Abu-Arab e Mudassir Iqbal. "Prediction Models for Estimating Compressive Strength of Concrete Made of Manufactured Sand Using Gene Expression Programming Model". Materials 15, n. 17 (24 agosto 2022): 5823. http://dx.doi.org/10.3390/ma15175823.
Testo completoAbstract (sommario):
The depletion of natural resources of river sand and its availability issues as a construction material compelled the researchers to use manufactured sand. This study investigates the compressive strength of concrete made of manufactured sand as a partial replacement of normal sand. The prediction model, i.e., gene expression programming (GEP), was used to estimate the compressive strength of manufactured sand concrete (MSC). A database comprising 275 experimental results based on 11 input variables and 1 target variable was used to train and validate the developed models. For this purpose, the compressive strength of cement, tensile strength of cement, curing age, Dmax of crushed stone, stone powder content, fineness modulus of the sand, water-to-binder ratio, water-to-cement ratio, water content, sand ratio, and slump were taken as input variables. The investigation of a varying number of genetic characteristics, such as chromosomal number, head size, and gene number, resulted in the creation of 11 alternative models (M1-M11). The M5 model outperformed other created models for the training and testing stages, with values of (4.538, 3.216, 0.919) and (4.953, 3.348, 0.906), respectively, according to the results of the accuracy evaluation parameters root mean square error (RMSE), mean absolute error (MAE), and coefficient of determination (R2). The R2 and error indices values revealed that the experimental and projected findings are in extremely close agreement. The best model has 200 chromosomes, 8 head sizes, and 3 genes. The mathematical expression achieved from the GEP model revealed that six parameters, namely the compressive and tensile strength of cement, curing period, water–binder ratio, water–cement ratio, and stone powder content contributed effectively among the 11 input variables. The sensitivity analysis showed that water–cement ratio (46.22%), curing period (25.43%), and stone powder content (13.55%) were revealed as the most influential variables, in descending order. The sensitivity of the remaining variables was recorded as w/b (11.37%) > fce (2.35%) > fct (1.35%).
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Matteini, Irene, Paul Noyce e Gina Crevello. "ASR: Practical investigative techniques and field monitoring systems used to assess ASR for service life modeling." MATEC Web of Conferences 289 (2019): 08004. http://dx.doi.org/10.1051/matecconf/201928908004.
Testo completoAbstract (sommario):
Alkali Silica Reaction (ASR) is a common deterioration mechanism affecting many concrete structures of any type and age. Initially identified more than 60 years ago (Stanton, 1930), this mechanism is based on the chemical reactions between certain siliceous minerals present in the aggregate and the alkalinity of the concrete in the presence of moisture (internal RH). While certain deterioration patterns are clearly associated with ASR, such as gel exudation, aggregate expansion, and characteristic cracking, the material degradation can often be misdiagnosed to the untrained eye. In addition, certain elements of a structure can be severely affected while neighboring elements of the same batch/ mix design do not bear signs of deterioration or impact. Thus far, in situ field monitoring of ASR affected structures is related to moisture measurements, electrical resistivity, expansion, service life models are based on fracture mechanics of the aggregate. The impact to the concrete is loss of integrity, decreased compressive strength, shear and tensile strength. Some observed structures have split, with such force, that the concrete structure had cracks greater than 25mm where steel retention bands have split. The authors of this paper were engaged in two instances to provide service life assessments for ‘corrosion related degradation’ on ASR affected structures. In all instances the elements which were assessed were structural, load bearing elements, which if failed could pose a significant risk to owner, user, or end recipient. The need to develop an assessment technique for monitoring and service life assessments which are practical and efficient is being developed. The paper will discuss the development of the approach, from visual indicators identifying condition hierarchies, to long term condition monitoring for various concrete parameters combined with laboratory testing (expansion and residual alkalis) and mathematical modeling. Three case studies will be presented to illustrate conditions and process.
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Aniskin, Nikolai A., e Alexey M. Shaytanov. "A full-scale study on the thermal emissivity of concrete and application of its findings to verify ANSYS software package". Vestnik MGSU, n. 6 (giugno 2022): 727–37. http://dx.doi.org/10.22227/1997-0935.2022.6.727-737.
Testo completoAbstract (sommario):
Introduction. One of the most popular and complex areas in the design of massive concrete structures is the analysis of their thermal behaviour and thermal stress state. Hence, we can identify tasks related to the phased construction of massive concrete structures, such as gravity dams, massive foundations, bridge supports, etc. A large number of factors, influencing the thermal process, varying over time and depending, among other things, on temperature, determine the complexity of such tasks. The main factor, determining the thermal behaviour of mass concrete in the process of construction, is the exothermic heating of concrete, depending on the type and amount of cement used, as well as several process specifications. Today, such problems can be best solved using the numerical finite element method, implemented in numerous software products. One of them is ANSYS software package, which is widely used to analyze constructions and structures in respect of a full range of actual loadings and impacts. This paper presents the results of the field studies conducted to obtain the initial parameters and verify the precision of results obtained using mathematical modeling techniques of the ANSYS software package.
Materials and methods. The authors describe a full-scale experiment that entails the concreting of a concrete testing block. During concrete placing and curing, temperature sensors time tested a temperature change inside the block and in the outside air. Also, studies were conducted using the numerical finite element method employed by the ANSYS software package.
Results. The findings of a full-scale experiment were compared with the thermal behaviour analysis made by the ANSYS software package. The comparison has proven highly precise results. The maximum temperature difference at the selected points of the full-scale and numerical models does not exceed 0.6 %.
Conclusions. The ANSYS software package solves complex tasks with high accuracy; it determines the thermal behaviour of massive concrete structures, taking into account the thermal emissivity during cement hydration.
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Zhukov, Alexey, Ekaterina Bobrova, Ivan Popov e Demissie Bekele Аrega. "SYSTEM ANALYSIS OF TECHNOLOGICAL PROCESSES". International Journal for Computational Civil and Structural Engineering 17, n. 4 (26 dicembre 2021): 73–82. http://dx.doi.org/10.22337/2587-9618-2021-17-4-73-82.
Testo completoAbstract (sommario):
The article discusses ways to solve engineering problems in the study of technological processes using methods of system analysis. The essence of this method is to study the technology as a cybernetic system with an assessment of the" reactions” of this system to external influences formed during an active experiment. At the same time, optimization problems are solved analytically. Analytical optimization is based on two main principles. The regression equations obtained as a result of processing experimental data and testing statistical hypotheses are models that adequately describe real processes. Each of these equations is an algebraic function of several variables, to which methods of mathematical analysis are applicable, including the study of extremums of functions in partial derivatives. The next step is to develop a process algorithm and develop computer programs that allow you to select the composition and predict the properties of the product. As an engineering interpretation, it is possible to construct optimized nomograms that allow solving both direct and inverse problems; that is, predicting the result or selecting technological factors. The research methods described in the article are implemented in the study of technologies of cellular concrete, foam concrete, cement-polymer concrete and products made of mineral wool and foam glass. As an example, the article considers the optimization of the selection of the composition of fine-grained concrete reinforced with chopped glass fiber. The implementation of the developed method allowed us to determine the optimal value of the determining parameters, including the consumption of fiber and plasticizer, as well as to form a method for studying the properties of products.
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Islam, Md Monirul, Md Belal Hossain, Md Nasim Akhtar, Mohammad Ali Moni e Khondokar Fida Hasan. "CNN Based on Transfer Learning Models Using Data Augmentation and Transformation for Detection of Concrete Crack". Algorithms 15, n. 8 (15 agosto 2022): 287. http://dx.doi.org/10.3390/a15080287.
Testo completoAbstract (sommario):
Cracks in concrete cause initial structural damage to civil infrastructures such as buildings, bridges, and highways, which in turn causes further damage and is thus regarded as a serious safety concern. Early detection of it can assist in preventing further damage and can enable safety in advance by avoiding any possible accident caused while using those infrastructures. Machine learning-based detection is gaining favor over time-consuming classical detection approaches that can only fulfill the objective of early detection. To identify concrete surface cracks from images, this research developed a transfer learning approach (TL) based on Convolutional Neural Networks (CNN). This work employs the transfer learning strategy by leveraging four existing deep learning (DL) models named VGG16, ResNet18, DenseNet161, and AlexNet with pre-trained (trained on ImageNet) weights. To validate the performance of each model, four performance indicators are used: accuracy, recall, precision, and F1-score. Using the publicly available CCIC dataset, the suggested technique on AlexNet outperforms existing models with a testing accuracy of 99.90%, precision of 99.92%, recall of 99.80%, and F1-score of 99.86% for crack class. Our approach is further validated by using an external dataset, BWCI, available on Kaggle. Using BWCI, models VGG16, ResNet18, DenseNet161, and AlexNet achieved the accuracy of 99.90%, 99.60%, 99.80%, and 99.90% respectively. This proposed transfer learning-based method, which is based on the CNN method, is demonstrated to be more effective at detecting cracks in concrete structures and is also applicable to other detection tasks.
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Su, Chao, e Wenjun Wang. "Concrete Cracks Detection Using Convolutional NeuralNetwork Based on Transfer Learning". Mathematical Problems in Engineering 2020 (17 ottobre 2020): 1–10. http://dx.doi.org/10.1155/2020/7240129.
Testo completoAbstract (sommario):
Crack plays a critical role in the field of evaluating the quality of concrete structures, which affects the safety, applicability, and durability of the structure. Due to its excellent performance in image processing, the convolutional neural network is becoming the mainstream choice to replace manual crack detection. In this paper, we improve the EfficientNetB0 to realize the detection of concrete surface cracks using the transfer learning method. The model is designed by neural architecture search technology. The weights are pretrained on the ImageNet. Supervised learning uses Adam optimizer to update network parameters. In the testing process, crack images from different locations were used to further test the generalization capability of the model. By comparing the detection results with the MobileNetV2, DenseNet201, and InceptionV3 models, the results show that our model greatly reduces the number of parameters while achieving high accuracy (0.9911) and has good generalization capability. Our model is an efficient detection model, which provides a new option for crack detection in areas with limited computing resources.
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Kurbatov, Yuri E., e Galina G. Kashevarova. "Determination of elastic characteristics of cement stone to predict the fatigue life of concrete". Vestnik MGSU, n. 4 (aprile 2022): 476–86. http://dx.doi.org/10.22227/1997-0935.2022.4.476-486.
Testo completoAbstract (sommario):
Introduction. The problem of fatigue failure of concrete is one of the least studied in computational practice. The lack of reliable data on the actual processes of accumulation of fatigue damage occurring in the structure of this material during cyclic exposure does not allow us to form a methodology for calculating concrete structures that perceive such loads. To develop the above methodology, it is proposed to use structural simulation modeling. For this purpose, mathematical models of concrete damage under the influence of cyclic loading are considered. The purpose of the study is to determine the elastic and strength characteristics of cement stone for further development of a methodology for predicting the fatigue life of concrete, taking into account the nonlinear kinetics of damage accumulation.
Materials and methods. The strength limits of cement stone during bending and compression were determined by conducting a full-scale experiment on a testing machine and a hydraulic press. Elastic characteristics of cement stone were obtained as a result of static tests of cement stone samples of various shapes on the universal electromechanical system with the joint use of the digital optical system for analysis of deformation and displacement fields and the acoustic emission signal recording system.
Results. During the tests of cement samples for bending and compression, the values of the corresponding bending and compression strength limits were obtained, which made it possible to confirm the design strength class of cement 32.5 N. Inhomogeneous fields of longitudinal and transverse deformations were obtained using a digital optical system to further determine the basic elastic characteristics of the material. Obtaining acoustic emission signals during the experiment made it possible to reflect the dependences of various acoustic emission parameters on time.
Conclusions. The first stage of the proposed methodology for predicting the fatigue life of concrete is performed, taking into account the nonlinear kinetics of damage accumulation, as a result of which the modulus of elasticity and the Poisson’s ratio for cement stone are determined. The obtained data can be used to create a numerical model of the concrete structure, and the use of acoustic emission signals allows us to estimate the kinetics of damage accumulation in the material.
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Kostić, V. Dj, V. P. Stankov Jovanović, T. M. Sekulić e Dj B. Takači. "Visualization of problem solving related to the quantitative composition of solutions in the dynamic GeoGebra environment". Chemistry Education Research and Practice 17, n. 1 (2016): 120–38. http://dx.doi.org/10.1039/c5rp00156k.
Testo completoAbstract (sommario):
Problem solving in the field of quantitative composition of solutions (QCS), expressed as mass share and molar concentration, is essential for chemistry students. Since successful chemistry education is based on different mathematical contents, it is important to be proficient in both mathematical and chemistry concepts as well as interconnections between them. One of the main objectives of this study was to create dynamic worksheets, applying softwareGeoGebra, which makes a strong link between real life problems from the field of QCS and their visual representations. The created models offer interactive connection within triangle –numerical data, concrete and abstract visual representations of the problem. The other important issue was to investigate if application of this novel teaching approach will lead to improvement of students' achievements in QCS problem solving. Ninety students of the first, second and third year of the bachelor chemistry study program, were subjects of the research. The students were classified into experimental and control groups based on the results of the initial test. Both groups were trained in the same pool of problems from the QCS field. In the control group the traditional approach based on algebraic methods was applied. The new didactic approach to the graphical method based on the dynamic properties ofGeoGebrawas presented to the experimental group. After two months, the final testing of all students was conducted. The students' answers were analysed and it is shown that the results of the experimental group were significantly better than the results of students in the control group. The results of these research studies confirmed that the students' learning achievement in solving QCS problems is better when they are familiar with theGeoGebraenvironment.
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Nizar, Achmad, Siti Maghfirotun Amin e Agung Lukito. "A Learning Trajectory of Indonesian 12-years Old Students Understanding of Division of Fractions". Southeast Asian Mathematics Education Journal 7, n. 2 (29 dicembre 2017): 41–52. http://dx.doi.org/10.46517/seamej.v7i2.52.
Testo completoAbstract (sommario):
The purpose of this study was to describe mathematical hands-on activities that can support students to gain better understanding of dividing fractions. This preliminary research phase was started by testing, analyzing, and refining the initial hypothetical learning trajectory (HLT), then in the pilot experimental phase the revised HLT was implemented, and ended with the teaching experimental phase by developing a learning trajectory for 12-year old students in understanding division of fractions. In developing the trajectory, a design research methodology was employed by using four contextual-based learning series (sharing biscuit, sharing remaining chocolate bar, arranging bedroom mats, and running around school yard), including providing some concrete materials or pictorial models as manipulative tools. Seven mathematics experts and twenty five 12-year old students were involved during the research. The four designed learning goals were determining the quotient of division of integer by proper fraction, proper fraction by integer, two proper fractions, and two fractions. Students succeeded in demonstrating their understanding and stated that 16:1/2 = 32; 25/36:5 = 5/36; 24/64:1/2 = 6/8; and 15/2:3/4 = 10 respectively at the end of each designed activity. The interesting results of this study are not a proof, so that a much larger study is needed to determine if the results are due to this approach or due to the teachers’ enthusiasm or what is known as the Hawthorne Effect.
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de-Prado-Gil, Jesús, Osama Zaid, Covadonga Palencia e Rebeca Martínez-García. "Prediction of Splitting Tensile Strength of Self-Compacting Recycled Aggregate Concrete Using Novel Deep Learning Methods". Mathematics 10, n. 13 (27 giugno 2022): 2245. http://dx.doi.org/10.3390/math10132245.
Testo completoAbstract (sommario):
The composition of self-compacting concrete (SCC) contains 60–70% coarse and fine aggregates, which are replaced by construction waste, such as recycled aggregates (RA). However, the complexity of its structure requires a time-consuming mixed design. Currently, many researchers are studying the prediction of concrete properties using soft computing techniques, which will eventually reduce environmental degradation and other material waste. There have been very limited and contradicting studies regarding prediction using different ANN algorithms. This paper aimed to predict the 28-day splitting tensile strength of SCC with RA using the artificial neural network technique by comparing the following algorithms: Levenberg–Marquardt (LM), Bayesian regularization (BR), and Scaled Conjugate Gradient Backpropagation (SCGB). There have been very limited and contradicting studies regarding prediction by using and comparing different ANN algorithms, so a total of 381 samples were collected from various published journals. The input variables were cement, admixture, water, fine and coarse aggregates, and superplasticizer; the data were randomly divided into three sets—training (60%), validation (10%), and testing (30%)—with 10 neurons in the hidden layer. The models were evaluated by the mean squared error (MSE) and correlation coefficient (R). The results indicated that all three models have optimal accuracy; still, BR gave the best performance (R = 0.91 and MSE = 0.2087) compared with LM and SCG. BR was the best model for predicting TS at 28 days for SCC with RA. The sensitivity analysis indicated that cement (30.07%) was the variable that contributed the most to the prediction of TS at 28 days for SCC with RA, and water (2.39%) contributed the least.
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Khan, Kaffayatullah, Fazal E. Jalal, Mudassir Iqbal, Muhammad Imran Khan, Muhammad Nasir Amin e Majdi Adel Al-Faiad. "Predictive Modeling of Compression Strength of Waste PET/SCM Blended Cementitious Grout Using Gene Expression Programming". Materials 15, n. 9 (23 aprile 2022): 3077. http://dx.doi.org/10.3390/ma15093077.
Testo completoAbstract (sommario):
The central aim of this study is to evaluate the effect of polyethylene terephthalate (PET) alongside two supplementary cementitious materials (SCMs)—i.e., fly ash (FA) and silica fume (SF)—on the 28-day compressive strength (CS28d) of cementitious grouts by using. For the gene expression programming (GEP) approach, a total of 156 samples were prepared in the laboratory using variable percentages of PET and SCM (0–10%, each). To achieve the best hyper parameter setting of the optimized GEP model, 10 trials were undertaken by varying the genetic parameters while observing the models’ performance in terms of statistical indices, i.e., correlation coefficient (R), root mean squared error (RMSE), mean absolute error (MAE), comparison of regression slopes, and predicted to experimental ratios (ρ). Sensitivity analysis and parametric study were performed on the best GEP model (obtained at; chromosomes = 50, head size = 9, and genes = 3) to evaluate the effect of contributing input parameters. The sensitivity analysis showed that: CS7d (30.47%) > CS1d (28.89%) > SCM (18.88%) > Flow (18.53%) > PET (3.23%). The finally selected GEP model exhibited optimal statistical indices (R = 0.977 and 0.975, RMSE = 2.423 and 2.531, MAE = 1.918 and 2.055) for training and validation datasets, respectively. The role of PET/SCM has no negative influence on the CS28d of cementitious grouts, which renders the PET a suitable alternative toward achieving sustainable and green concrete. Hence, the simple mathematical expression of GEP is efficacious, which leads to saving time and reducing labor costs of testing in civil engineering projects.
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Rezvani Sharif, Mostafa, e Seyed Mohammad Reza Sadri Tabaei Zavareh. "Numerical analysis of the shear strength of circular reinforced concrete columns subjected to cyclic lateral loads using linear genetic programming". Engineering Computations 37, n. 7 (18 marzo 2020): 2517–37. http://dx.doi.org/10.1108/ec-10-2018-0453.
Testo completoAbstract (sommario):
Purpose The shear strength of reinforced concrete (RC) columns under cyclic lateral loading is a crucial concern, particularly, in the seismic design of RC structures. Considering the costly procedure of testing methods for measuring the real value of the shear strength factor and the existence of several parameters impacting the system behavior, numerical modeling techniques have been very much appreciated by engineers and researchers. This study aims to propose a new model for estimation of the shear strength of cyclically loaded circular RC columns through a robust computational intelligence approach, namely, linear genetic programming (LGP). Design/methodology/approach LGP is a data-driven self-adaptive algorithm recently used for classification, pattern recognition and numerical modeling of engineering problems. A reliable database consisting of 64 experimental data is collected for the development of shear strength LGP models here. The obtained models are evaluated from both engineering and accuracy perspectives by means of several indicators and supplementary studies and the optimal model is presented for further purposes. Additionally, the capability of LGP is examined to be used as an alternative approach for the numerical analysis of engineering problems. Findings A new predictive model is proposed for the estimation of the shear strength of cyclically loaded circular RC columns using the LGP approach. To demonstrate the capability of the proposed model, the analysis results are compared to those obtained by some well-known models recommended in the existing literature. The results confirm the potential of the LGP approach for numerical analysis of engineering problems in addition to the fact that the obtained LGP model outperforms existing models in estimation and predictability. Originality/value This paper mainly represents the capability of the LGP approach as a robust alternative approach among existing analytical and numerical methods for modeling and analysis of relevant engineering approximation and estimation problems. The authors are confident that the shear strength model proposed can be used for design and pre-design aims. The authors also declare that they have no conflict of interest.
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Bažant, Zdeněk P. "Concrete fracture models: testing and practice". Engineering Fracture Mechanics 69, n. 2 (gennaio 2002): 165–205. http://dx.doi.org/10.1016/s0013-7944(01)00084-4.
Testo completo
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Meena, Ayush, S. D. Bharti e P. V. Ramana. "Mathematical Models Viability for Bi-Material Forte Appraisal". Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, n. 1 (19 dicembre 2022): 1647–52. http://dx.doi.org/10.38208/acp.v1.701.
Testo completoAbstract (sommario):
This study examines the mechanical traits of bi-material concrete containing polypropylene fiber. This analysis aims to establish a relationship between bi-material concrete’s compressive strength (CS), split tensile strength (STS), and flexural strength (FS). M25 grade of bi-material concrete is designed, and polypropylene fiber is added to half of the concrete. Polypropylene fiber (PPF) was included in concrete with 0.20, 0.35, 0.50, 0.75, 1.00, and 1.50% by the weight of cement. Different test (CS, FS, STS) was performed over the bi-material concrete after 28 days of the curing period. Mathematical models were made by performing regression analysis over the experiment data and matched with the other models in the previous studies. Mechanical properties of the definite increase when the polypropylene fiber increases up to 0.5% compared to conventional concrete. It is seen that the empirical values fall within reach of expected values when the predicted values are compared to the experimental results. In this study, the existing analytical models and the relationship between mechanical traits of bi-material concrete are evaluated and matched with the models present in previous studies, and a new model is proposed.
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Tutiareni, Teni, Budi Hendrawan e Muhammad Fahmi Nugraha. "PENGARUH PENDEKATAN MATEMATIKA REALISTIK TERHADAP HASIL BELAJAR SISWA SEKOLAH DASAR". Jurnal PGSD 7, n. 2 (28 dicembre 2021): 12–19. http://dx.doi.org/10.32534/jps.v7i2.2441.
Testo completoAbstract (sommario):
Abstrak
Penelitian ini bertujuan untuk meningkatkan hasil belajar matematika dalam pembelajaran operasi hitung bilangan pecahan pada siswa kelas V SDN 2 Tuguraja, Cihideung, Kota Tasikmalaya. Dalam penelitian ini pembelajaran dengan pendekatan matematika realistik yang akan dilaksanakan yaitu menggunakan tahap matematika konkret dengan bantuan media benda nyata dan model alat peraga berupa play-doh dan kertas origami. Penelitian ini termasuk penelitian eksperimen semu (quasi eksperimen) menggunakan desain Pretest-Posttest Nonequivalent control group design. Populasi dalam penelitian ini adalah seluruh siswa kelas V SDN 2 Tuguraja, dengan jumlah 18 siswa. Pengambilan sampel dengan menggunakan teknik Sampling Jenuh, cara pengambilan sempelnya secara random, yang menghasilkan 9 siswa kelas eksperimen dan 9 siswa kelas kontrol. Obyek penelitian adalah hasil belajar operasi hitung bilangan pecahan menggunakan pembelajaran matematika realistik. Untuk menguji validitas instrumen dalam penelitian ini menggunakan validitas konstrak dengan menggunakan pendapat ahli (experts jugdement) dan validitas isi dengan mengujicobakan ke sekolah yang berbeda. Data hasil penelitian diperoleh dari tes hasil belajar, dan dianalisis secara deskriptif kuantitatif. Hasil penelitian menunjukkan bahwa bahwa t hitung sebesar 2.456 dengan probabililitas signifikansi (two tailed) 0,000, karena signifikansi (two tailed) < 1/2 a (0,05), maka Ho ditolak dan Ha diterima, berarti terdapat pengaruh pendekatan pembelajaran matematika realistik terhadap hasil belajar siswa kelas V SDN 2 Tuguraja pada materi soal cerita pecahan. Hal itu juga didukung oleh nilai rata-rata posttest kelas eksperimen sebesar 77,56 lebih besar daripada kelas kontrol yaitu sebesar 62,78.
Kata Kunci: Hasil belajar, Matematika, Pembelajaran Matematika Realistik.
Abstract
This study aims to improve mathematics learning outcomes in learning arithmetic operations for fifth grade students at SDN 2 Tuguraja, Cihideung, Tasikmalaya City. In this study, learning with a realistic mathematical approach that will be carried out is using a concrete mathematical stage with the help of real object media and teaching aid models in the form of play-doh and origami paper. This research is a quasi-experimental research (quasi-experimental) using the Pretest-Posttest Nonequivalent control group design. The population in this study were all fifth grade students of SDN 2 Tuguraja, with 18 students. Sampling using the Saturated Sampling technique, the sampling method was random, which resulted in 9 students in the experimental class and 9 students in the control class. The object of research is the result of learning arithmetic operations using realistic mathematics learning. To test the validity of the instrument in this study using construct validity using expert opinion (experts judgment) and content validity by testing it with different schools. The research data were obtained from learning outcomes tests, and were analyzed descriptively quantitatively. The results show that t count is 2.456 with a significance probability (two tailed) 0.000, because the significance (two tailed) < 1/2 a (0.05), then Ho is rejected and Ha is accepted, meaning that there is an effect of realistic mathematics learning approach on the results. 5th grade students of SDN 2 Tuguraja learn about story problems. This is also supported by the posttest average value of the experimental class which is 77.56, which is greater than the control class, which is 62.78.
Keywords: Learning Outcomes, Mathematics, Realistic Mathematics Learning.
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Wac-Wlodarczyk, A., R. Goleman, D. Czerwinski e T. Gizewski. "Mathematical models applied in inductive non-destructive testing". Journal of Magnetism and Magnetic Materials 320, n. 20 (ottobre 2008): e1044-e1048. http://dx.doi.org/10.1016/j.jmmm.2008.04.179.
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Ledenev, Andrey A., Viktor T. Pertsev, Oleg B. Rudakov e Dmitriy E. Ваrabash. "Development of Ideas About the Rheological Behaviour of Building Mixtures Taking into Account Fractal-Cluster Processes in Their Structure Formation". Kondensirovannye sredy i mezhfaznye granitsy = Condensed Matter and Interphases 22, n. 4 (26 novembre 2020): 473–80. http://dx.doi.org/10.17308/kcmf.2020.22/3059.
Testo completoAbstract (sommario):
Development of theoretical ideas about the mechanism of the rheological behaviour of building mixtures and the experimental assessment of their rheological properties is a relevant area of physiochemical research of materials. To assess the changes in rheological properties when varying the component composition of building mixtures, it is important to use quantitative indicators characterising the microstructure of the mixtures. Revealing the regularities of the formation of heterogeneous microstructures makes it possible to assess their correlation with the rheological properties of buildingmixtures at the macro level. The aim of the paper is to discuss the results of the implementation of methodological approaches, theoretical modelling, and experimental assessment of the quantitative indicators of the rheological properties of typical building mixtures.The experimental research methodology is based on the assessment of the rheological properties of heterogeneous dispersed systems (HDS), taking into account fractal-cluster manifestations in their microheterogeneous component. The experiment was carried out using model HDS containing the components of building mixtures. Their rheological properties were determined by rotational viscometry with different compositions of HDS. The fractal dimension D was used for a quantitativeassessment of the structural and rheological properties and identification of the patterns of their change depending on the composition of mixtures. The value was determined by mathematical modelling.We analysed model concepts of the rheological behaviour of building mixtures. It was shown that the existing rheological models of an elastic-viscous-plastic medium did not give a complete description of the processes of formation and destruction of the microstructure of concentrated HDS (building mixtures). We carried out an experimental assessment of the effect of the properties of solid phase particles on the change in the structural and rheological characteristics of HDS, taking into account the fractal-cluster principles of their structure formation.We specified the ideas about the mechanism of rheological behaviour of building mixtures. They take into consideration the processes of the formation and destruction of fractal-cluster formations in the microstructure of HDS. It was shown that the fractal dimension D can be one of the quantitative characteristics of the structural and rheological properties. We determined the correlation between the fractal dimension D and other experimental rheological characteristics: the ultimateshear stress and effective viscosity. The obtained results can be used to regulate rheological properties and optimise the technological processes for the manufacture of building materials and products.
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Meena, Ayush, Tushar Sharma, Mohit Patodiya e P. V. Ramana. "Evaluation of Morsel Rubber Mathematical Models in Seismic Areas". Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, n. 1 (19 dicembre 2022): 1185–91. http://dx.doi.org/10.38208/acp.v1.638.
Testo completoAbstract (sommario):
Reinforced concrete is the most consumed material in the world, followed by air and water. As the demand for reinforced concrete as a building material increases, so makes the demand for Portland cement and ordinary cement. On the other hand, environmental protection has become a significant issue due to climate change caused by global warming. This is due to emissions of greenhouse gases such as CO2 from human activities. Of all greenhouse gases, CO2 is responsible for approximately 65% ??of global warming. The cement industry also contributes to releasing CO2 into the atmosphere by producing large amounts of Portland cement and releasing large amounts of CO2. One can need to protect the environment by preventing the uncontrolled disposal of waste. Several efforts have been made to solve this problem. These include using additional cementitious materials such as fly ash, silica fume, granular blast furnace slag, rice husk ash, grass, metakaolin, and alternative binders to Portland cement. Consumption of morsel rubber concrete can reduce the environmental impact in the cement industry. From the perspective of global warming, the technology of self-compacting morsel rubber concrete can significantly reduce the emission of CO2 into the atmosphere. This report presents the analysis and test results of the properties of class 40 self-compacting Morsel rubber concrete using various new approaches.