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Letteratura scientifica selezionata sul tema "Concrete Testing Mathematical models"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 29 gennaio 2023

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Articoli di riviste sul tema "Concrete Testing Mathematical models"

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

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

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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.

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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.

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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.

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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.

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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.

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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.

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

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

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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.

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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.

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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.

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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.

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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.

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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.

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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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Più fonti

Tesi sul tema "Concrete Testing Mathematical models"

Lanzas, Lourdes Eneida 1962. "A parametric study on the behavior of slender reinforced concrete frames". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276945.

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By using a nonlinear computer analysis, a parametric study is developed in order to examine the accuracy of the Moment Magnifier Method of the American Concrete Institute Code (ACI 318-83). The variables used in the parametric study are: axial load intensity, P/Po; column reinforcement ratio, rho; slenderness ratio, klu; shape of column cross section, flexural stiffness ratio, and distribution of axial loads. In the parametric study, 216 cases of single bay fixed-base portal frames are examined. The higher moment for each one of these frames at failure are then compared with the design moment predicted by the Moment Magnifier Method of the American Concrete Institute Code (ACI 318-83). The Moment Magnifier Method proved to be very conservative when the columns are subjected to high level of axial loads and when the slenderness ratio is increased.

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Lam, Wai-yin, e 林慧賢. "Plate-reinforced composite coupling beams: experimental and numerical studies". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37311797.

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Chan, Ka-ho Enoch, e 陳家灝. "Experimental and numerical studies of concrete beams prestressed with unbonded tendons". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40988004.

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Lokuge, W. P. (Weena Priyanganie) 1967. "Stress-strain behaviour of confined high strength concrete under monotonically increasing and cyclic loadings". Monash University, Dept. of Civil Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/9425.

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Tasnimi, A. A. "Prediction of forces within prestressed sections : The behavior of simply supported prestressed concrete beams with boned and unbonded tendons predicted by mathematical model and investigated by testing to destruction using two point load". Thesis, University of Bradford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384298.

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Thölken, Denise. "Efeito da rigidez de pilar parede no comportamento sísmico de edifício de concreto armado". Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/962.

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Este trabalho tem como objeto o estudo do efeito da rigidez de pilar parede no comportamento estrutural de edifícios de concreto armado submetidos a sismos. Foram consideradas as premissas da norma brasileira ABNT NBR15421:2006, que apresenta os critérios para projeto de estruturas resistentes a sismo. A análise linear com emprego dos métodos da norma - método das forças horizontais equivalentes, método espectral e histórico de aceleração no tempo - foi aplicada em edifícios com dois tipos de sistemas estruturais, sendo eles pórtico de concreto e sistema dual pórtico de concreto e pilar parede. Os resultados foram analisados nos pórticos de extremidade das estruturas nos sentidos longitudinal (x) e transversal (y), comparando-se os deslocamentos de cada pavimento e esforços cortantes, momento fletor e normal nas bases dos pilares. A comparação foi realizada entre os três métodos aplicados e os sistemas estruturais analisados.
The aim of this work is to study the stiffness effect of wall columns on structural behavior of reinforced concrete buildings subjected to seismic action. The premises of the Brazilian standard ABNT NBR14521:2006 were considered, which presents criteria for earthquake resistant design of structures. The linear analysis employed the methods of the Brazilian standard - equivalent static load method, response spectrum analysis and time history method - were applied to buildings with two types of structural systems, namely concrete frame and dual system concrete frame and wall columns. The results were analyzed in edge frames structures in the longitudinal and transverse directions, comparing the displacement of each floor and shear, bending moment and axial forces on the bases of the columns. A comparison was made between the three methods applied and the structural systems analyzed.

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Ng, Ah Book. "Physical models in fire study of concrete structures". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64055.

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Pessôa, José Renato de Castro. "Análise numérico-experimental de estruturas de concreto com utilização da energia de fraturamento". Universidade do Estado do Rio de Janeiro, 2007. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=780.

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A evolução dos concretos utilizados nas últimas décadas deu origem ao Concreto de Alto Desempenho (CAD), que tem, entre suas características, alta resistência à compressão e baixa permeabilidade. Com o desenvolvimento dos produtos químicos utilizados na construção civil, em especial os superplastificantes e superfluidificantes, a utilização desse tipo de concreto tornou-se cada vez mais freqüente pela possibilidade de se obter uma mistura suficientemente trabalhável utilizando-se fatores água/cimento menores do que 0,35. Devido à sua microestrutura mais homogênea, esse tipo de concreto apresenta um comportamento mais frágil do que os concretos convencionais, exigindo uma melhor caracterização do material. A partir do final da década de 70 começou-se a aplicar os conceitos da Mecânica da Fratura para análise do comportamento de estruturas construídas com esse tipo de concreto. Como em algumas situações a resistência nominal de peças de concreto diminui com o aumento de suas dimensões, houve a necessidade de se considerar o efeito de escala das estruturas a fim de se obter níveis de segurança mais adequados no seu dimensionamento, o que justificou a utilização da Mecânica da Fratura. Neste trabalho a energia de fraturamento foi obtida experimentalmente pelo método do trabalho de fraturamento e pelo método do efeito de escala, por meio de ensaios estáveis de flexão de três pontos em amostras de concreto de alto desempenho com entalhe. Foi também desenvolvida a simulação numérica de uma viga com entalhe, analisada pelo método dos elementos finitos e empregando-se na modelagem constitutiva os conceitos da Mecânica da Fratura aplicada ao concreto. As vigas foram moldadas e ensaiadas no Instituto Politécnico do Rio de Janeiro (IPRJ) da Universidade do Estado do Rio de Janeiro (UERJ) na cidade de Nova Friburgo. Os ensaios foram realizados com controle de deslocamento da célula de carga. Foram ensaiadas três séries de 12 vigas, com quatro dimensões diferentes, geometricamente proporcionais, e três amostras para cada dimensão, totalizando 36 vigas. As alturas utilizadas para as vigas foram 38, 76, 152 e 304 mm, e sua espessura foi mantida constante igual a 38 mm. Os corpos de prova cilíndricos, para caracterização da resistência à compressão do concreto, foram moldados no IPRJ e rompidos no laboratório de engenharia civil da UERJ, na cidade do Rio de Janeiro. Os concretos utilizados apresentaram resistência à compressão média de 70 MPa.
The evolution of the concrete mixes used during the last decades gave birth to the High Performance Concrete (HPC), which, among its main characteristics, presents high strength and low permeability. With the development of chemical products used in civil engineering constructions, mainly the superplasticizers, the use of this kind of concrete has become more and more frequent due to the possibility of obtaining a workable mixture with a water/cement ratio lower than 0.35. Due to its more homogeneous microstructure, the HPC presents a more fragile behavior than the conventional concrete, demanding a better characterization of the material. At the end of the 1970s, concepts of the Fracture Mechanics started to be used for the analysis of the structural behavior of concrete structures. As the nominal stress of the material decreases as the size of the structure increases, it became necessary to consider this size effect in the analysis in order to obtain more suitable levels of security. This fact justifies the use of the Fracture Mechanics in the structural analysis of concrete structures. In this work, the fracture energy was experimentally obtained using the work-offracture method and the size effect method by performing three-point bend tests in HPC notched beams. It was also developed a numerical simulation of the tests, performing the analysis through the Finite Element Method and applying the concepts of the Fracture Mechanics of Concrete into the constitutive model. The notched beams were molded and tested at the Polytechnic Institute of the State University of Rio de Janeiro (IPRJ/UERJ), located in the city of Nova Friburgo. The tests were controlled by the vertical displacement of the load cell. Three series of twelve beams with four geometrically similar sizes were tested. Three samples for each size were cast, making an amount of 36 beams. The beams were 38, 76, 152 and 304 millimeters high and the width was kept constant equal to 38 millimeters. To characterize the concrete compression strength, 100x200 millimeters cylinders were molded at the IPRJ and tested at the UERJ civil engineering laboratory in the city of Rio de Janeiro. The tested concretes presented a medium compressive strength of 70 MPa.

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Ferdjani, Omar. "Behaviour of a one cell prestressed concrete box girder bridge : analytical study". Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66163.

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CHENG, YEOU-YEN. "MULTIPLE-WAVELENGTH PHASE SHIFTING INTERFEROMETRY (OPTICAL-TESTING, ASPHERIC SURFACE)". Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/187928.

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The problems of combining ideas of phase shifting interferometry (PSI) and synthetic-wavelength techniques to extend the phase measurement range of conventional single-wavelength PSI are investigated. This combination of PSI and synthetic-wavelengths gives multiple-wavelength phase-shifting interferometry the advantages of: (1) larger phase measurement range and (2) higher accuracy of phase measurement. Advantages, error sources, and limitations of single-wavelength PSI are discussed. Some practical methods to calibrate the piezoelectric transducer (PZT), used to phase shift the reference beam, are presented with experimental results. Two methods of two-wavelength PSI are used to solve the 2π ambiguity problem of single-wavelength PSI. For the first method, two sets of phase data (with 2π ambiguities) for shorter wavelengths are calculated and stored in the computer which calculates the new phase data for the equivalent-wavelength λ(eq). The "error magnification effect," which reduces the measurement precision of the first method, is then investigated. The second, more accurate method, uses the results of the first method as a reference to correct the 2π ambiguities in the single-wavelength phase data. Experimental results are included to confirm theoretical predictions. The enhancement of two-wavelength PSI is investigated, and requires the phase data of a third wavelength. Experiments are performed to verify the capability of multiple-wavelength PSI. For the wavefront being measured, the difference of the optical-path-difference (OPD) between adjacent pixels is as large as 3.3 waves. After temporal averaging of five sets of data, the repeatability of the measurement is better than 2.5 nm (0.0025%) rms (λ = 632.8 nm). This work concludes with recommendations for future work that should make the MWLPSI a more practical technique for the testing of steep aspheric surfaces.

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Più fonti

Libri sul tema "Concrete Testing Mathematical models"

Bažant, Z. P. Concrete at high temperatures: Material properties and mathematical models. Harlow: Longman, 1996.

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Kerr, Arnold D. The assessment of concrete pavement blowups: A user manual. McLean, Va: U.S. Dept. of Transportation, Federal Highway Administration, 1993.

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Tejchman, Jacek. Steel-fibrous concrete: Experiments and a numerical discrete model. Gdańsk: Wydwan. Politechniki Gdańskiej, 2000.

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(undifferentiated), Walter Kaufmann. Strength and deformations of structural concrete subjected to in-plane shear and normal forces. Basel: Birkhäuser Verlag, 1998.

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Gauvreau, Paul. Ultimate limit state of concrete girders prestressed with unbonded tendons. Basel: Birkhauser Verlag, 1993.

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Halicka, Anna. Studium stanu naprężeń i odkształceń w płaszczyźnie styku i strefie przypodporowej elementów zespolonych z udziałem betonów skurczowych i ekspansywnych: A study of the stress-strain state in the interface and support zones of composite structures with shrinking and expansive concretes. Lublin: Wydawnictwo Politechniki Lubelskiej, 2007.

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Stephens, Jerry E. Performance of steel pipe pile-to-concrete bent cap connections subject to seismic or high transverse loading, phase II: Final report. Helena]: Montana Dept. of Transportation, 2005.

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Stephens, Jerry E. Performance of steel pipe pile-to-concrete bent cap connections subject to seismic or high transverse loading, phase II: Project summary report. Helena, Mont: Montana Dept. of Transportation, 2005.

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A concrete approach to mathematical modelling. New York: Wiley, 1995.

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A concrete approach to mathematical modelling. Redwood City, Calif: Addison-Wesley, 1989.

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Capitoli di libri sul tema "Concrete Testing Mathematical models"

Broy, Manfred, Wolfgang Böhm e Bernhard Rumpe. "Advanced Systems Engineering". In Model-Based Engineering of Collaborative Embedded Systems, 353–64. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-62136-0_19.

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AbstractAdvanced systems engineering (ASE) is a new paradigm for agile, efficient, evolutionary, and quality-aware development of complex cyber-physical systems using modern digital technologies and tools. ASE is essentially enabled by smart digital modeling tools for specifying, modeling, testing, simulating, and analyzing the system under development embedded in a coherent and consistent methodology.The German Federal Ministry of Education and Research (BMBF) projects SPES2020, SPES_XT, and CrESt offer such a methodology and framework for model-based systems engineering (MBSE). The framework provides a comprehensive methodology for MBSE that is independent of tools and modeling languages. The framework also offers a comprehensive set of concrete modeling techniques and activities that build on a formal, mathematical foundation. The SPES framework is based on four principles that are of paramount importance: (1) Functional as well as non-functional requirements fully modeled and understood at system level. (2) Consistent consideration of interfaces at each system level. (3) Decomposition of systems into subsystems and their interfaces. (4) Models for a variety of cross-sectional topics (e.g., variability, safety, dynamics).

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Prodan, Emil. "Electron Dynamics: Concrete Physical Models". In SpringerBriefs in Mathematical Physics, 11–24. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-55023-7_2.

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Taler, Dawid. "Mathematical Models of Heat Exchangers". In Numerical Modelling and Experimental Testing of Heat Exchangers, 321–37. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-91128-1_9.

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Aceto, Luca, Rocco Nicola e Alessandro Fantechi. "Testing equivalences for event structures". In Mathematical Models for the Semantics of Parallelism, 1–20. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/3-540-18419-8_9.

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Wefelmeyer, Wolfgang. "Testing hypotheses on independent, not identically distributed models". In Mathematical Statistics and Probability Theory, 267–82. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3963-9_20.

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Sannella, Donald, e Andrzej Tarlecki. "Mind the gap! Abstract versus concrete models of specifications". In Mathematical Foundations of Computer Science 1996, 114–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/3-540-61550-4_143.

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Bayarri, M. J., James O. Berger e Gauri S. Datta. "Objective Bayes testing of Poisson versus inflated Poisson models". In Institute of Mathematical Statistics Collections, 105–21. Beachwood, Ohio, USA: Institute of Mathematical Statistics, 2008. http://dx.doi.org/10.1214/074921708000000093.

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Urbain, Jean-Pierre. "Testing for Weak Exogeneity in Error Correction Models". In Lecture Notes in Economics and Mathematical Systems, 83–111. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-95706-2_4.

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Bergan, Pål G., Arne Arnesen e Olav Fyrileiv. "Computational Applications of Alternative Mathematical Models for Reinforced Concrete". In Computational Mechanics ’95, 2334–39. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-79654-8_388.

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Baker, Rose. "Software Reliability Growth Models for Discrete and Incomplete Testing". In Lecture Notes in Economics and Mathematical Systems, 257–71. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-59105-1_19.

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Atti di convegni sul tema "Concrete Testing Mathematical models"

Massimo Borsa, M. "A mathematical model for predicting chloride penetration into concrete exposed to marine environment in temperate climate." In Third International RILEM Workshop on Testing and Modelling Chloride Ingress into Concrete. RILEM Publications SARL, 2005. http://dx.doi.org/10.1617/2912143578.011.

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Haynes, Mark D., Chih-Hang John Wu, Matthew Arnold, Naga Narendra B. Bodapati, B. Terry Beck e Robert J. Peterman. "Bond Index Numbers of Prestressed Concrete Reinforcement Wires and Their Relationships to Transfer Lengths and Pull-Out Forces". In 2016 Joint Rail Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/jrc2016-5787.

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The purpose of this research is to establish mathematical models that predicts the bond strength of a reinforcement wire in prestressed concrete members, given the known geometrical features of the wire. A total of nineteen geometrical features of the reinforcement wire were measured and extracted by a precision non-contact profilometer. With these mathematical models, prestressing reinforcement wires can now be analyzed for their bond strength without destructive testing. These mathematical models, based upon a large collection of empirical data via prestressing reinforcement wires from various wire manufacturers in US and Europe, have the potential to serve as quality assessment tools in reinforcement wire and prestressed concrete member production. Most of these models are very simple and easy to implement in practice, which could provide insight into which reinforcement wires provide the greatest bond strength and which combinations of geometrical features of the reinforcement wire are responsible for providing the bond strength. Our various empirical models have shown that the indent side-wall angle, which is suggested by the ASTM-A881/A881M, may not be the only significant geometrical feature correlated to the transfer length and bond strengths. On the contrary, features such as the indent surface area, indent width, indent edge surface area, indent volume, and release strengths do have significant correlations with the ultimate transfer lengths of the prestressed concrete members. Extensive experiments and testing performed at the Structures Laboratory in Kansas State University, as well as field tests at Transportation Technology Center, Inc. (TTCI) and one Prestressed Concrete Railroad Tie manufacturing facility, have been used to confirm the model predictions. In addition, our experimental results suggest that the maximum pull out force in the un-tensioned pullout testing has significant correlation with the ultimate transfer length. This finding could provide reinforcement wire manufactures with a quality assurance tool for testing their wires prior to the production. The resultant mathematical model relating the wire geometrical features to transfer length is referred to as the Bond Index Number (BIN). The BIN is shown to provide a numerical measure of the bond strength of prestressing steel reinforcement wire, without the need for performing destructive tests with the reinforcement wire. We believe that with the BIN and the maximal pull-out forces from the un-tensioned pull-out tests, one can have better insight into the optimal reinforcement wire design by testing the performance of wires before they are put into production lines.

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Al Nageim, Hassan. "Non Destructive Testing of Low Profile Light Weight Track System". In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24727.

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The paper presents the results of the responses of a concrete trough of a new lightweight rail track system (LR55) to full scale non destructive tasting. The system which is made from three main components; low profile steel rail, elastomeric pad and prestressed concrete trough is developed for light rail transits in cities streets, which can significantly help in improving the traffic flow, reducing the traffic congestion and thus providing opportunities for minimising serious environmental problems such as level of noise, vibration and air pollutions and in this regards it can be considered as environmentally friendly means of transport. A mathematical model was developed where the LR55 track system was treated as multilayer beams on elastic foundations, and the model was then validate experimentally through a series of non-destructive tests on full scale model subjected to a full scale service load specified by the current BS codes of practises.

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Haynes, Mark, Chih-Hang John Wu, B. Terry Beck, Naga Narendra B. Bodapati e Robert J. Peterman. "Prestressing Steel Reinforcement Wire Bond Index Number". In 2013 Joint Rail Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/jrc2013-2422.

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The purpose of this research project is to develop a mathematical model that predicts the bond strength of a prestressing steel reinforcement wire given the known geometrical features of the wire. The geometrical features of the reinforcement wire were measured by a precision non-contact profilometer. With this mathematical model, prestressing reinforcement wires can now be analyzed for their bond strength without destructive testing. This mathematical model has the potential to serve as a quality control assessment in reinforcement wire production. In addition this mathematical model will provide insight into which reinforcement wires provide the greatest bond strength and which combinations of geometrical features of the reinforcement wire are responsible for providing the bond strength. A precision non-contact profilometer has been developed to measure the important geometrical features of the reinforcement wire. The profilometer is capable of sub-micron resolution measurements to provide an extremely high quality three-dimensional rendering of the reinforcement wire surface profile. From this detailed profile data it is then possible to extract all of the relevant geometrical features of the reinforcement wire. A mathematical model has been created by testing a variety of different reinforcement wires available in the market. By correlating the transfer length of concrete prisms made with the reinforcement wires to various geometrical features, several different levels of mathematical correlation complexity have been investigated. The current empirical correlation models under development are first order and combine three to four unique geometrical features of the reinforcement wire which then act as predictors of the concrete prism transfer length. The resulting mathematical model relating the wire geometrical features to transfer length is referred to as the Bond Index Number (BIN). The BIN is shown to provide a numerical measure of the bond strength of prestressing steel reinforcement wire, without the need for performing destructive tests with the reinforcement wire.

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Bajaj, Mayank, e Biswajit Bhattacharjee. "Residual service life estimation of bridges". In IABSE Congress, Christchurch 2021: Resilient technologies for sustainable infrastructure. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2021. http://dx.doi.org/10.2749/christchurch.2021.0984.

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<p>While concrete structures perform well in many situations, lack of durability has emerged as a significant issue for asset owners. A review of past bridge failures was done to identify the most probable causes of bridge failures. This study has tended to focus on current models used for estimating the time to deterioration of concrete bridges instigated by Chloride ingress and Fatigue. Subsequently, mathematical modelling of the best-suited deterioration model is done to arrive at the residual life of two existing bridges. This work has highlighted high variability in the parameters used to describe the durability related properties of in-situ aged concrete. A realistic residual life assessment can be achieved by correct evaluation of these parameters by periodic testing of bridge samples</p>

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Yu, Hailing, e David Jeong. "Finite Element Bond Modeling for Indented Wires in Pretensioned Concrete Crossties". In 2016 Joint Rail Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/jrc2016-5782.

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Indented wires have been increasingly employed by concrete crosstie manufacturers to improve the bond between prestressing steel reinforcements and concrete, as bond can affect several critical performance measures, including transfer length, splitting propensity and flexural moment capacity of concrete ties. While extensive experimental testing has been conducted at Kansas State University (KSU) to obtain bond characteristics of about a dozen commonly used prestressing wires, this paper develops macro-scale or phenomenological finite element bond models for three typical wires with spiral or chevron indent patterns. The steel wire-concrete interface is homogenized and represented with a thin layer of cohesive elements sandwiched between steel and concrete elements. The cohesive elements are assigned traction-displacement constitutive or bond relations that are defined in terms of normal and shear stresses versus interfacial dilatation and slip within the elasto-plastic framework. A yield function expressed in quadratic form of shear stress and linear form of normal stress is adopted. The yield function takes into account the adhesive mechanism and hardens in the post-adhesive stage. The plastic flow rule is defined such that the plastic dilatation evolves with the plastic slip. The mathematical forms of the yield and plastic flow functions are the same for all three wire types, but the bond parameters are specific for each wire. The adhesive, hardening and dilatational bond parameters are determined for each wire type based on untensioned pullout tests and pretensioned prism tests conducted at KSU. Simulation results using these bond models are further verified with surface strain data measured on actual concrete crossties made with the three respective prestressing wires at a tie manufacturing plant.

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Tortoriello, Miguel A., Luis J. Lima, Ana C. Cobas e Renso A. Cichero. "Timber bodies strength of materials: Fundamental principles, test specimens proposal". In IABSE Congress, Christchurch 2021: Resilient technologies for sustainable infrastructure. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2021. http://dx.doi.org/10.2749/christchurch.2021.1112.

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<p>To reduce the economic cost of a Timber Structure, the first condition is to have a “rational” Structural Code, that is, a Code supported by research and a specific theory. To establish a rational Structural Timber Code, a specific theoretical support is needed. The objective of this paper is to cooperate in the construction of this theoretical support. To design timber structures, it is necessary to have mathematical models able to reproduce the resistance of timber bodies under different solicitations. In this paper, a “road map” to arrive to a specific Strength of Materials of Timber Bodies is proposed. This theory will be the tool needed to develop the mathematical models whose quantification will be obtained by testing “basic test specimens” obtained from timber of any particular timber building (like in concrete or soil mechanics). Finally, a “basic test specimen” for practical application of the theory is proposed. In this case, the experimental support is referred to “willow” wood.</p>

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Xue, Ruo-Jun, e Ji-Lin Sun. "Modeling and Simulation of Deaerator in Nuclear Power Plant". In 2014 22nd International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icone22-30452.

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Different deaerators have different structures, and the intensities of deaerating are different. But the deaerator models without considering the structure couldn’t show these aspects. In order to ensure the accuracy of simulation results, concrete structure of the deaerator should be taken into consideration. This paper carried out a mathematical model of horizontal type deaerator with constant nozzles and trays in nuclear power plants. It was built based on the structure of the segmentation deaerators and the process of heat transferring. This paper calculated the vapors condensation rate, it was based on heat transfer coefficient of direct contact condensation, and the heat transfer area of water film when working conditions were corresponding to the empirical formulas. While the working conditions were beyond the limits of empirical formulas, this paper would build models by conservation of energy, so the model could work under any working conditions. These models were installed in the simulation system of Qinshan Phase II., and were tested under variable power and accidental conditions. The testing results show that the models could fit for different steady working conditions. Compared with the outputs and the actual operating data, the error was small. Under the conditions of variable power and turbine tripping, changing of the parameters have the same trend curve with the actual operating data. Because of taking the concrete structure into consideration, these models can be performed better of the specific characteristics of the horizontal type deaerators with constant nozzles and trays in nuclear power plants, therefore the results are more accurate than the models without considering the structure.

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Pitts, Katie Lieg, e Timothy Shedd. "Viscosity Studies of Aqueous Solutions of Hafnium Oxide Particles and Polystyrene Nanospheres". In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30826.

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Nanoparticle colloidal system rheology has long been researched, without many concrete conclusions. Literature has been devoted to the viscosity and shear properties of these systems since Einstein’s PhD thesis. However, most models are based on molecular dynamics which are not necessarily applicable to real systems, and most real systems are modeled by empiricism. This report looks to unify these approaches through rheological testing and mathematical analysis in order to achieve several goals using a system composed of hafnium oxide particles suspended in water. The first goal is to have a viscosity model that fits not only empirical data, but also the relevant theory and first principles. By employing the modern techniques of a rhoemeter-on-a-chip to nano-scale particles, the limitations of traditional rheometry are bypassed. The molecular dynamics approaches are converted to zero-shear and infinite-shear viscosities which can be applied to traditional models. A modern model was then derived, applied to new data, and agreement was found to a satisfactory degree. No significant change in viscosity with shear rate was found experimentally or analytically. Traditional research is done with spherical particles, such as polystyrene nanopsheres, as which we are approximating hafnium oxide (HfOx) to be. Polystyrene nanospheres are nominally spherical and commercially available at relatively inexpensive costs. Actual spherical data was required for appropriate comparison, and the findings show that the spherical particles have distinct properties.

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Menzel, Thaddäus, e Thiago de Borba. "Methodology for Automated Definition of Critical Scenarios". In FISITA World Congress 2021. FISITA, 2021. http://dx.doi.org/10.46720/f2020-acm-073.

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The field of automated driving has been the focus of research in both, academia and industry in the recent decades. Thanks to the advancements in sensor technology currently used for Advanced Driver Assistance Systems (ADAS), automatization of several parts of the driving task was enabled. However, the introduction of new technologies into the market requires a testing phase. Different test methods can be applied to assess the automated driving functions and their features. Nevertheless, the systematic test of functions for driver assistance systems requires the identification and analysis of a huge number of traffic scenarios. Since most traffic scenarios are not challenging, an approach that automatically generates critical driving scenarios can reduce the testing efforts and costs. This paper presents a methodology for automated definition of critical scenarios, which is composed of seven steps: define a critical maneuver, define the logical scenario, model the critical maneuver using a mathematical description, define the assessment criteria, obtain the concrete scenarios, specify a performance improvement method, and obtain the boundary scenarios. Firstly, Independent if the validation/homologation is based on a virtual or a field test, the tests should be focused on the most critical situations, since the test phase is costly. The selection of critical scenarios, based on critical maneuvers, is an important phase to develop testing methods. Thus, the critical maneuver selected was the lane change maneuver. The logical scenario defined describes the event where Ego drives in highway, presenting certain speed and acceleration, and due to a traffic jam, the front vehicle and the rear vehicle, on the adjacent lane, are stationary and there is a considerable distance between Ego and the rear vehicle. After, the mathematical modelling of the lane change maneuver was performed. Composed of three parts, the trajectory planning, which is responsible to generate the desired trajectory that ensure a safe lane change maneuver based on different driver style, the second is the vehicle model, which describes the longitudinal and lateral motion of the Ego vehicle, and the last is the driver model, which is responsible to drive Ego vehicle along to the planned trajectory. The assessment criteria was based on the safety distances and on the maximum lateral acceleration performed during the maneuver. The concrete scenarios were generated by variating three parameters, in this case, relative velocity between Ego and the front vehicle, the distance between Ego and the front vehicle, and alpha, the coefficient that affects the lane change time. Then, the performance improvement approach was applied, using the k-Nearest Neighbor Classifier, to reduce the computational elapsed time. After completing the first six steps, the concrete scenarios have been classified as critical and non-critical. Lastly, through the analysis of each neighbor point, it was possible to reduce the result space, to a few number of scenarios that can be easily manipulated, the boundary scenarios. Thus, the proposed methodology shown to be an efficient method for the definition of critical scenarios, since thousands of scenarios could be generated and classified in a matter of seconds.

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Rapporti di organizzazioni sul tema "Concrete Testing Mathematical models"

Sparks, Paul, Jesse Sherburn, William Heard e Brett Williams. Penetration modeling of ultra‐high performance concrete using multiscale meshfree methods. Engineer Research and Development Center (U.S.), settembre 2021. http://dx.doi.org/10.21079/11681/41963.

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Terminal ballistics of concrete is of extreme importance to the military and civil communities. Over the past few decades, ultra‐high performance concrete (UHPC) has been developed for various applications in the design of protective structures because UHPC has an enhanced ballistic resistance over conventional strength concrete. Developing predictive numerical models of UHPC subjected to penetration is critical in understanding the material's enhanced performance. This study employs the advanced fundamental concrete (AFC) model, and it runs inside the reproducing kernel particle method (RKPM)‐based code known as the nonlinear meshfree analysis program (NMAP). NMAP is advantageous for modeling impact and penetration problems that exhibit extreme deformation and material fragmentation. A comprehensive experimental study was conducted to characterize the UHPC. The investigation consisted of fracture toughness testing, the utilization of nondestructive microcomputed tomography analysis, and projectile penetration shots on the UHPC targets. To improve the accuracy of the model, a new scaled damage evolution law (SDEL) is employed within the microcrack informed damage model. During the homogenized macroscopic calculation, the corresponding microscopic cell needs to be dimensionally equivalent to the mesh dimension when the partial differential equation becomes ill posed and strain softening ensues. Results of numerical investigations will be compared with results of penetration experiments.

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Hlushak, Oksana M., Svetlana O. Semenyaka, Volodymyr V. Proshkin, Stanislav V. Sapozhnykov e Oksana S. Lytvyn. The usage of digital technologies in the university training of future bachelors (having been based on the data of mathematical subjects). [б. в.], luglio 2020. http://dx.doi.org/10.31812/123456789/3860.

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This article demonstrates that mathematics in the system of higher education has outgrown the status of the general education subject and should become an integral part of the professional training of future bachelors, including economists, on the basis of intersubject connection with special subjects. Such aspects as the importance of improving the scientific and methodological support of mathematical training of students by means of digital technologies are revealed. It is specified that in order to implement the task of qualified training of students learning econometrics and economic and mathematical modeling, it is necessary to use digital technologies in two directions: for the organization of electronic educational space and in the process of solving applied problems at the junction of the branches of economics and mathematics. The advantages of using e-learning courses in the educational process are presented (such as providing individualization of the educational process in accordance with the needs, characteristics and capabilities of students; improving the quality and efficiency of the educational process; ensuring systematic monitoring of the educational quality). The unified structures of “Econometrics”, “Economic and mathematical modeling” based on the Moodle platform are the following ones. The article presents the results of the pedagogical experiment on the attitude of students to the use of e-learning course (ELC) in the educational process of Borys Grinchenko Kyiv University and Alfred Nobel University (Dnipro city). We found that the following metrics need improvement: availability of time-appropriate mathematical materials; individual approach in training; students’ self-expression and the development of their creativity in the e-learning process. The following opportunities are brought to light the possibilities of digital technologies for the construction and research of econometric models (based on the problem of dependence of the level of the Ukrainian population employment). Various stages of building and testing of the econometric model are characterized: identification of variables, specification of the model, parameterization and verification of the statistical significance of the obtained results.

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Wang, Yao, Mirela D. Tumbeva e Ashley P. Thrall. Evaluating Reserve Strength of Girder Bridges Due to Bridge Rail Load Shedding. Purdue University, 2021. http://dx.doi.org/10.5703/1288284317308.

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This research experimentally and numerically evaluated the reserve strength of girder bridges due to bridge rail load shedding. The investigation included: (1) performing non-destructive field testing on two steel girder bridges and one prestressed concrete girder bridge, (2) developing validated finite element numerical models, and (3) performing parametric numerical investigations using the validated numerical modeling approach. Measured data indicated that intact, integral, reinforced concrete rails participate in carrying live load. Research results culminated in recommendations to evaluate the reserve strength of girder bridges due to the participation of the rail, as well as recommendations for bridge inspectors for evaluating steel girder bridges subjected to vehicular collision.

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Соловйов, Володимир Миколайович, e D. N. Chabanenko. Financial crisis phenomena: analysis, simulation and prediction. Econophysic’s approach. Гумбольдт-Клуб Україна, novembre 2009. http://dx.doi.org/10.31812/0564/1138.

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With the beginning of the global financial crisis, which attracts the attention of the international community, the inability of existing methods to predict the events became obvious. Creation, testing, adaptation of the models to the concrete financial market segments for the purpose of monitoring, early prediction, prevention and notification of financial crises is gaining currency nowadays. Econophysics is an interdisciplinary research field, applying theories and methods originally developed by physicists in order to solve problems in economics, usually those including uncertainty or stochastic processes and nonlinear dynamics. Its application to the study of financial markets has also been termed statistical finance referring to its roots in statistical physics. The new paradigm of relativistic quantum econophysics is proposed.

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Ramakrishnan, Aravind, Ashraf Alrajhi, Egemen Okte, Hasan Ozer e Imad Al-Qadi. Truck-Platooning Impacts on Flexible Pavements: Experimental and Mechanistic Approaches. Illinois Center for Transportation, novembre 2021. http://dx.doi.org/10.36501/0197-9191/21-038.

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Truck platoons are expected to improve safety and reduce fuel consumption. However, their use is projected to accelerate pavement damage due to channelized-load application (lack of wander) and potentially reduced duration between truck-loading applications (reduced rest period). The effect of wander on pavement damage is well documented, while relatively few studies are available on the effect of rest period on pavement permanent deformation. Therefore, the main objective of this study was to quantify the impact of rest period theoretically, using a numerical method, and experimentally, using laboratory testing. A 3-D finite-element (FE) pavement model was developed and run to quantify the effect of rest period. Strain recovery and accumulation were predicted by fitting Gaussian mixture models to the strain values computed from the FE model. The effect of rest period was found to be insignificant for truck spacing greater than 10 ft. An experimental program was conducted, and several asphalt concrete (AC) mixes were considered at various stress levels, temperatures, and rest periods. Test results showed that AC deformation increased with rest period, irrespective of AC-mix type, stress level, and/or temperature. This observation was attributed to a well-documented hardening–relaxation mechanism, which occurs during AC plastic deformation. Hence, experimental and FE-model results are conflicting due to modeling AC as a viscoelastic and the difference in the loading mechanism. A shift model was developed by extending the time–temperature superposition concept to incorporate rest period, using the experimental data. The shift factors were used to compute the equivalent number of cycles for various platoon scenarios (truck spacings or rest period). The shift model was implemented in AASHTOware pavement mechanic–empirical design (PMED) guidelines for the calculation of rutting using equivalent number of cycles.

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