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Littérature scientifique sur le sujet « J-C PARAMETERS »

Auteur : Grafiati

Publié le 16 janvier 2024

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Articles de revues sur le sujet "J-C PARAMETERS"

Sari, Injilia Pebrina. « Study Of Signal Quality Relationship On The Number Of Clusters And Propagation Parameters In Mobile Comumunication ». Jurnal Mekintek : Jurnal Mekanikal, Energi, Industri, Dan Teknologi 11, n^o 2 (30 octobre 2020) : 53–58. http://dx.doi.org/10.35335/mekintek.v11i2.14.

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A suitable telecommunications system to support a mobile communication system is a wireless communication system, which is a radio communication system complete with transmitting antennas and radio equipment. To be able to cover such a wide coverage, the coverage area is divided into sub-areas called cells. A collection of several cells is called a cluster, and several clusters will form a mobile cellular communication network area. The number of clusters in an area is affected by changes in parameters, especially the pathloss from the propagation environment. Planning in designing a communication network is needed to be able to see how much influence the parameter changes, especially the propagation attenuation factor and the number of clusters, is to make a computer program for cell planning. From the cell planning program, it can be obtained that the value of c/i is influenced by changes in the value of J when the value of n is 3.9. The value of c/i when the value of J is 3 is 6.5321. The value of c/i when the value of J is 4 is 8.4062. The value of c/i when the value of J is 5 is 9.8599. The value of c/i when the value of J is 6 is 11.0476. The value of c/i when the value of J is 7 is 12.0518. The value of c/i when the value of J is 8 is 12.9217. The value of c/i when the value of J is 9 is 13.6889. The value of c/i is influenced by changes in the value of n when the value of J is 15. The value of c/i when the value of n is 3 is 17.0167. The value of c/i when the value of n is 3.2 is 18.6698. The value of c/i when the value of n is 3.4 is 20.3231. The value of c/i when the value of n is 3.6 is 21.9761. The value of c/i when the value of n is 3.8 is 23.6293. The value of c/i when the value of n is 3.9 is 24.4561. The greater the number of cells, the greater the value of the signal ratio ratio (c/i) in the propagation. The propagation attenuation value is directly proportional to the signal ratio ratio (c/i). The greater the number of cells and the propagation attenuation, the greater the signal ratio ratio (c/i). The greater the value of the signal ratio ratio (c/i), the better the received signal quality.

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Zheng, Zhongpeng, Chenbing Ni, Yun Yang, Yuchao Bai et Xin Jin. « Numerical Analysis of Serrated Chip Formation Mechanism with Johnson-Cook Parameters in Micro-Cutting of Ti6Al4V ». Metals 11, n^o 1 (6 janvier 2021) : 102. http://dx.doi.org/10.3390/met11010102.

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Previous studies have reported significant differences in the Johnson-Cook (J-C) parameters of Ti6Al4V alloy. Thus, various serrated chip morphologies, cutting forces, and cutting temperatures are obtained when different constitutive parameters are used for numerical and simulation analyses, which decreases the reliability of the simulation model. Therefore, it is necessary to investigate and analyze simulation errors due to differences in the J-C parameters. In this study, the mechanism of the serrated chip formation of Ti6Al4V is thoroughly analyzed using the uniformly proportional J-C parameters. The serrated chip sensitivity, shear band spacing, serrated segmentation frequency, chip serration intensity, temperature field, strain energy, and cutting force is obtained. This study aims to improve the accuracy and reliability of the micro-cutting simulation models, as well as a reference for the selection of J-C constitutive parameters of simulation with Ti6Al4V manufactured with different heat treatments and additive manufacturing.

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Seshadri, R., et R. K. Kizhatil. « Robust Approximate Methods for Estimating Inelastic Fracture Parameters ». Journal of Pressure Vessel Technology 117, n^o 2 (1 mai 1995) : 115–23. http://dx.doi.org/10.1115/1.2842098.

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Robust approximate methods to estimate the inelastic energy release rate J, and the creep crack-growth parameter, C*, for cracked components are described in this paper. These methods use linear elastic finite element analysis in conjunction with the concepts of the generalized local stress strain (GLOSS) analysis and redistribution nodes (r-nodes), and are readily applicable to complex geometries and loadings. J-estimates obtained by the use of robust methods are found to be in good agreement with the results of elastic-plastic finite element analysis.

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Bartsch, Martin, Zhe-Feng Zhang, Christina Scheu, Manfred Rühle et Ulrich Messerschmidt. « Fracture parameters of chevron-notched Al₂O₃/Nb sandwich specimens ». International Journal of Materials Research 95, n^o 9 (1 septembre 2004) : 779–84. http://dx.doi.org/10.1515/ijmr-2004-0146.

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Abstract Fracture toughness tests were performed on Al2O3/Nb sandwich specimens using chevron-notched bending bars. These tests allow the independent determination of the fracture toughness K c at a defined crack velocity and the total work of fracture J c. The J c values are much greater than the data for the energy release rate G c following from K c. The fracture surfaces were studied by optical and scanning electron microscopy. The results are discussed in terms of the fracture toughness of cleavage in the Al2O3 and severe plastic deformation in the Nb sheet.

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Wang, Cunxian, Tao Suo, Yulong Li, Pu Xue et Zhongbin Tang. « A New Experimental and Numerical Framework for Determining of Revised J-C Failure Parameters ». Metals 8, n^o 6 (30 mai 2018) : 396. http://dx.doi.org/10.3390/met8060396.

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Böttcher, O., N. Heineking, M. Andolfatto et D. H. Sutter. « Molecular gᅩ-value, Magnetic Susceptibility Anisotropy, and Deuterium Quadrupole Coupling Constantin Deuterodiacetylene ». Zeitschrift für Naturforschung A 44, n^o 2 (1 février 1989) : 89–94. http://dx.doi.org/10.1515/zna-1989-0201.

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Abstract The rotational Zeeman effect in the J′ → J = 2 → 1 rotational transition and the deuterium quadrupole coupling effect in the J′→J = 1 → 0 transition have been observed for D - C = C - C = C - H using a microwave Fourier transform (MWFT)-spectrometer.The molecular parameters determined are: rotational constant B0= 4084.452 MHz, deuterium quadrupole coupling constant e q Q (D) = 217(6) kHz, molecular gᅩ-value = 0.0073(1) and molecular magnetic susceptibility anisotropy (Xᅩ - X||) = 11.5(7) 10-6 erg G-2mol-1.

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Itzler, M. A., et M. Tinkham. « Effective parameters j˜/sub c/ and λ˜J at commensurate fields in large Josephson junctions with periodic columnar defects ». IEEE Transactions on Appiled Superconductivity 5, n^o 2 (juin 1995) : 1091–94. http://dx.doi.org/10.1109/77.402741.

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Qiu, Xiaoli, Xianqiang Cheng, Penghao Dong, Huachen Peng, Yan Xing et Xin Zhou. « Sensitivity Analysis of Johnson-Cook Material Constants and Friction Coefficient Influence on Finite Element Simulation of Turning Inconel 718 ». Materials 12, n^o 19 (25 septembre 2019) : 3121. http://dx.doi.org/10.3390/ma12193121.

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The Johnson-Cook (J-C) constitutive model, including five material constants (A, B, n, C, m), and the Coulomb friction coefficient (μ) are critical preprocessed data in machining simulations. Before they become reliable preprocessed data, investigating these parameters’ effect on simulation results benefits parameter-selecting. This paper aims to investigate the different influence of five settings of the J-C constitutive equation and Coulomb friction coefficient on the turning simulation results of Inconel 718 under low-high cutting conditions, including residual stress, chip morphology, cutting force and temperature. A three-dimensional (3-D) finite element model was built, meanwhile, the reliability of the model was verified by comparing the experiment with the simulation. Sensitivity analysis of J-C parameters and friction coefficient on simulation results at low-high cutting conditions was carried out by the hybrid orthogonal test. The results demonstrate that the simulation accuracy of Inconel 718 is more susceptible to strain hardening and thermal softening in the J-C constitutive model. The friction coefficient only has significant effects on axial and radial forces in the high cutting condition. The influences of the coefficient A, n, and m on the residual stress, chip thickness, cutting force and temperature are especially significant. As the cutting parameters increase, the effect of the three coefficients will change visibly. This paper provides direction for controlling simulation results through the adjustment of the J-C constitutive model of Inconel 718 and the friction coefficient.

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Kunchur, Milind N. « Evaluating Superconductors through Current Induced Depairing ». Condensed Matter 4, n^o 2 (17 juin 2019) : 54. http://dx.doi.org/10.3390/condmat4020054.

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The phenomenon of superconductivity occurs in the phase space of three principal parameters: temperature T, magnetic field B, and current density j. The critical temperature T c is one of the first parameters that is measured and in a certain way defines the superconductor. From the practical applications point of view, of equal importance is the upper critical magnetic field B c 2 and conventional critical current density j c (above which the system begins to show resistance without entering the normal state). However, a seldom-measured parameter, the depairing current density j d , holds the same fundamental importance as T c and B c 2 , in that it defines a boundary between the superconducting and normal states. A study of j d sheds unique light on other important characteristics of the superconducting state such as the superfluid density and the nature of the normal state below T c , information that can play a key role in better understanding newly-discovered superconducting materials. From a measurement perspective, the extremely high values of j d make it difficult to measure, which is the reason why it is seldom measured. Here, we will review the fundamentals of current-induced depairing and the fast-pulsed current technique that facilitates its measurement and discuss the results of its application to the topological-insulator/chalcogenide interfacial superconducting system.

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Wang, J., N. Ito, S. Pyon, T. Nishizaki et T. Tamegai. « Vortex Dynamics and Critical Current Densities in 90 K-phase and 60 K-phase YBa₂Cu₃O_7−δ with Splayed Columnar Defects ». Journal of Physics : Conference Series 2323, n^o 1 (1 août 2022) : 012018. http://dx.doi.org/10.1088/1742-6596/2323/1/012018.

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Abstract Enhancement of critical current density (J c) was observed in YBa2Cu3O7−δ with splayed columnar defects (CDs). In the case of 90 K-phase YBa2Cu3O7−δ with splayed CDs, the enhanced J c drops suddenly at the depinning temperature of vortices from CDs (T dp), which is interpreted to be caused by the excitation of double kinks traversing neighboring CDs. In addition to the optimal 90 K-phase, where the superconductivity dominates, there is another stable 60 K-phase and other phases with different T c. This study reports temperature dependence of J c and the step-like decrease of J c in YBa2Cu3O7−δ with CDs and with different T c. Results show that the T dp is strongly related to the T c. However, additional entropic reduction of T dp may depend on parameters other than T c.

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Thèses sur le sujet "J-C PARAMETERS"

Maric, Danilo. « Firmware development of a User Interface on medical devices of DIMA ITALIA Srl ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.

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This dissertation was written based on an internship experience at Dima Italia Srl, a leader in designing, production and marketing of medical ventilators. Once these ventilators were simple machines for breathing support, manually pumping the air in and out. Today, medical ventilators are computerized machines, electronically controlled by a small embedded system. They feature a plethora of available modes and an easy-to-use graphical interface. Exactly this is the topic of the thesis: developing a firmware with graphical interface for the next ventilator, produced and sold by Dima Italia. The firmware is based on C++ language and was developed in a Qt Creator framework, ideal for developing applications with graphical interfaces on Linux-based devices. In the paper are found all the pages of the firmware, along with the logic of operation of the application. Moreover, all the details about the operation and modes of a medical ventilator are also found in the document. In the end, there's a section related to deployment of a Qt application on a device, along with the issues and bugs encountered during the development process.

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Chapitres de livres sur le sujet "J-C PARAMETERS"

Patton, Lydia. « Hybrid Enrichment of Theory and Observation in Next-Generation Stellar Population Synthesis ». Dans Synthese Library, 81–90. Cham : Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-26618-8_5.

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AbstractNext-generation observational surveys in astronomy provide empirical data with increasingly high resolution and precision. After presenting the basic methods of population synthesis (via Conroy C, Ann Rev Astronom Astrophys 51:393–455, 2013; Maraston C, Mon Not Royal Astronom Soc 362:799–825, 2005), this paper argues for several related conclusions. The increased precision of the new methods requires the development of improved theoretical resources and models to provide the richest interpretation of the new data (as argued by Maraston C, Strömbäck G, Monthly Not Royal Astronom Soc 418:2785–2811, 2011). The measurement of physical variables and parameters in population synthesis is best understood using a model-based account along the lines of (Tal E, The epistemology of measurement: a model-based approach. Dissertation, The University of Toronto, 2012) and (Parker WS, Br J Philos Sci 68:273–304, 2017). Finally, in the case of population synthesis, improved empirical data does not dispense with the need for theoretical reasoning in post-data analysis. In fact, the high-resolution data used in next-generation population synthesis demands ever richer theories and models, a process that results in hybrid enrichment of theoretical and observational methods and results.

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Nohel, John. « Commentary on : [L 45] Perturbations of Discontinuous Solutions of Non-Linear Systems of Differential Equations [L 48] An Ordinary Differential Equation with an Interval of Stability, a Separation Point, and an Interval of Instability [L 60] (with J. J. Levin), Singular Perturbations of Non-Linear Systems of Differential Equations and an Associated Boundary Layer Equation, [L 62] (with L. Flatto), Periodic Solutions of Singularly Perturbed Systems [L 56] (with E. A. Coddington), A Boundary Value Problem for a Nonlinear Differential Equation with a Small Parameter [L 63] (with S. Haber), A Boundary Value Problem for a Singularly Perturbed Differential Equation, [L 67] A Boundary Value Problem for a Singularly Perturbed Differential Equation, [L 46] The First Boundary Value Problem for $$ \in \Delta u + {\rm A}\left( {x,y} \right){u_x} + {\rm B}\left( {x,y} \right){u_y} + C\left( {x,y} \right)u = D\left( {x,y} \right)$$ for small ε ». Dans Selected Papers of Norman Levinson, 267–87. Boston, MA : Birkhäuser Boston, 1998. http://dx.doi.org/10.1007/978-1-4612-5332-7_29.

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Payne, Stanley E. « A Census of Finite Generalized Quadrangles ». Dans Finite Geometries, Buildings, and Related Topics, 29–36. Oxford University PressOxford, 1990. http://dx.doi.org/10.1093/oso/9780198532149.003.0003.

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Abstract A construction is given for each known isomorphism class of finite generalized quadrangles. Generalized quadrangles, as a special case of generalized polygons, were introduced by J. Tits in 1959 [26]. There he gave what are considered to be the classical exmples. As special cases of other types of geometries, these classical examples appeared elsewhere, most notably among the partial geometries of R. C. Bose [3]. The first nonclassical examples were also found by J. Tits in the mid-1960s and first appeared in P. Dembowski [5]. All these examples had parameters (s,t)of the form (q,q),, ,(q,q), or (q,q), where qis an arbitrary prime power. independently by M. Hall, Jr. [9]. Shortly afterwards, S. E. Payne [17] gave an abstractly more general construction which was shown in [18] to produce a new family for qany power of 2. More recently, starting with a construction of W. M. Kantor [10], several new families with parameters have been discovered, often with restrictions on the prime power q.Although the point-line dual of a GQ with parameters (s,t)is a GQ with parameters (t,s), implying that one could assume thats isnever larger than t,we often find it interesting to mention both a GQ and its point-line dual. In any case, each finite GQ known to us is isomorphic to at least one of the constructions given below or to its point-line dual.

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Singh, S. « Electrochemical Oxidation of Perfluorooctanoic Acid (PFOA) from Aqueous Solution using Non-Active Ti/SnO2-Sb2O5/PbO2 Anodes ». Dans Advances in Wastewater Treatment II, 48–67. Materials Research Forum LLC, 2021. http://dx.doi.org/10.21741/9781644901397-2.

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In this study, electrochemical oxidation of perfluorooctanoic acid (PFOA, C7H15CO2H) from aqueous solution was examined in terms of PFOA and total organic carbon (TOC) removal by using Ti/SnO2-Sb2O5/PbO2non-active electrodes. The effects of operating parameters: initial pH (pHo), current density (j), and electrolyte concentration (m) at different time intervals were examined. Specific energy consumption (SEC) was used to determine the process proficiency. The C-C bond between C7F15 was first cleaved and thendegraded into fluoride ions (F−) and short carbon-chain per-fluorinated carboxylic acids (PFCAs) ((∼C2−C7) such as perfluoroethanoic acid (PFEA: C2F5CO2H), perfluoropropanoic acid (PFPA: C3F7CO2H), perfluorobutanoic acid (PFBA: C4F9CO2H), perfluoropentanoic acid (PFPeA: C5F11CO2H), perfluorohexanoic acid (PFHxA: C6F13CO2H), perfluoheptanoic acid (PFHpA: C7F14CO2H). These intermediates by-products were determined using the gas chromatograph-mass spectrometry (GC/MS) analysis. The rate of PFOA decomposition was followed the pseudo-first-order kinetics. About 82%TOC and 94% PFOA removals were formed at the optimal condition of pHo = 3.58, j=168.34 Am-2, and m = 250 mgL-1 at 120 min of electrolysis with SEC = 593 kWh/kg TOC. A plausible degradation mechanism was also proposed at the optimal treatment condition.

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Nekovee,, M., W. M. C. Foulkes et R. J. Needs. « Quantum Monte Carlo studies of density functional theory ». Dans Quantum Monte Carlo, 141. Oxford University PressNew York, NY, 2007. http://dx.doi.org/10.1093/oso/9780195310108.003.00145.

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Abstract It is difficult to imagine that density functional theory (DFT) could be useful in improving quantum Monte Carlo methods, but it is easy to imagine that QMC could be useful in improving density functional methods. Since QMC can produce accurate wavefunctions and since wavefunctions lead to all other properties one should be able, in principle, to use QMC to predict the exchangecorrelation energy functional Exc[n(r)], the key (unknown) quantity required in DFT. In practice, that is not so easy, but this paper shows how QMC can take steps in that direction by providing insights gained from comparisons of results from QMC and DFT. The authors considered the case of the strongly inhomogeneous electron gas using variational Q:tvIC to obtain wavefunctions 1/J>. and energies E[7/J>.] for the ground state of the Hamiltonian iI>- = T +AVee+V >. associated with the coupling constant A in the range 0 to 1. Optimization of a Slater-Jastrow many-body wavefunction was made by minimizing a penalty function given by a weighted sum of the variance in local energies and a sum of squares of electron density differences. The variational parameters in 7/J>. and v>. were repeatedly varied to reach convergence followed by additional calculations to obtain the local values of the exchange-correlation energies e c and the exchange-correlation holes n c from which Exe and nxc could be determined.

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« Applicability of the Inverse Method to the Determination of C-J Parameters for Gaseous Mixtures at Elevated Pressures ». Dans Dynamics of Explosions, 64–76. Washington DC : American Institute of Aeronautics and Astronautics, 1988. http://dx.doi.org/10.2514/5.9781600865886.0064.0076.

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Devolder, Maud. « Architectural Energetics and Late Bronze Age Cretan Architecture : Measuring the Scale of Minoan Building Projects ». Dans Minoan Architecture and Urbanism. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198793625.003.0010.

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It may appear to be asking too much of archaeological evidence to attempt an assessment of the scale of Minoan building projects, their impact on communities, or the role of the labour-time needed for the construction of various kinds of masonry. By taking a firmly materialist perspective, however, the present paper offers an exploration of some of the parameters at play in the production of Minoan architecture. Architectural energetics is a method that translates a building into the labourtime necessary for its construction, a value expressed in person-days or person-hours (abbreviated p-d and p-h). Estimations are based on standard units of time necessary to accomplish each task making up the architectural project: the procurement of raw materials, their transport, manufacture, and assembling. These are most generally expressed in volumes per hour per person, and referred to as ‘standard costs’, which are applied to the volumes of edifices and thus determine the labour-time necessary for their construction. The first assessments of the duration and manpower of ancient building projects mainly appeared in the form of subjective labour-time estimates triggered by romantic views of the grandeur of early civilizations (Andrews 1877; Humboldt 1816; Squier and Davis 1848; Stephens 1841; Webster 1997: 219). Around the middle of the twentieth century, a growing body of publications started to make use of such estimates in order to correlate the magnitude of building or agricultural projects with particular stages of sociopolitical organization (Adams 1975; Cook 1947; Cottrell 1955; Erasmus 1965; Heizer 1960, 1966; Kaplan 1963; White 1949, 1959). Among the most prominent figures of this early trend was C. J. Erasmus, who led a series of experiments that aimed to provide objective quantification of building costs (Erasmus 1965). From the 1970s onwards, largely connected with a renewed research agenda promoting scientific methods of data recovery and interpretation of the archaeological record, quantitative assessments of architectural projects flourished (Aaberg and Bonsignore 1975; Arnold and Ford 1980; Carmean 1991; Cheek 1986; Craig, Holmlund, and Clark 1998; Hard et al. 1999; Price 1982; Trigger 1990; Webster 1985; Webster and Kirker 1995).

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Actes de conférences sur le sujet "J-C PARAMETERS"

Mehmanparast, A. N., C. M. Davies et K. M. Nikbin. « Validation of the K and J Parameters in a Compact Tension Specimen Containing Intergranular and Straight Crack Paths ». Dans ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/pvp2010-25281.

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Methods have been examined to evaluate the fracture mechanics parameters J and K in finite element (FE) analyses on a compact tension, C(T), geometry using a mesh appropriate for the evaluation of both intergranular and transgranular microstructural damage processes. Realistic grain and grain boundary microstructures were modelled using ABAQUS. Both straight and deviating crack profiles were considered, representing transgranular and intergranular crack growth processes, respectively. Elastic and elastic-plastic finite element analyses were performed on a C(T) specimen model with a standard straight and deviating crack profile to derive and compare the stress intensity factor, K, and J parameter values under plane stress and plane strain conditions. Considerations as to the validity of the J domain integral calculations that ABAQUS computes are discussed. It has been found that the values of K and J obtained from FE simulations are consistent with theoretical solutions and the stress distribution ahead of the crack tip is very close to that of expected from analytical studies for the case of a straight fronted transgranular crack. Reasonable values of K and J parameters could also be achieved from the FE contour integral values of a deviating crack when the contours selected were adequately far from the crack tip. However, significant differences were found between the analytical and FE contour integral values of a deviating crack when the crack growth direction was considered to continue at the angle defined by its grain boundary. The values of J obtained by from the load line displacement measurements were uninfluenced by the crack profile and in good agreement with other analytical solutions.

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Griffin, Robert J., Atsushi Ogawa, Abdus Shakil et Chang W. Song. « Local Hyperthermic Treatment of Solid Tumors : Interplay Between Thermal Dose and Physiological Parameters ». Dans ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0796.

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Abstract Reduction of tumor blood flow during hyperthermia may impair the ability of the tumor vasculature to dissipate heat and lead to greater tumor cell killing. We are currently testing a new compound (KB-R8498) which has been found to reduce tumor blood flow. One hour after an i.v. or an i.p. injection of KB-R8498 the blood flow in SCK tumors of A/J mice was reduced to 40%–70% of control. The blood flow in 6 A/J mouse normal tissues one hour after drug treatment was mostly unchanged. Control tumors grew to four times the starting volume in 6 days. An injection of 10 mg/kg KB-R8498 caused a growth delay of about 2 days. After tumors were heated at 42.5°C for 60 min, there was a delay of 4 days in tumor growth. When i.p. or i.v. injections of KB-R8498 were given and the tumors were heated at 42.5°C for 60 min, there was a growth delay of over 10 days. The implications for clinical hyperthermia treatments are discussed.

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Savioli, Rafael G., et Claudio Ruggieri. « Improved J and CTOD Estimation Formulas for C(T) Fracture Specimens Including Overmatched Weldments ». Dans ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57030.

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This work focuses on the evaluation procedure to determine the elastic-plastic J-integral and CTOD fracture toughness based upon the η-method for C(T) fracture specimens made of homogeneous and welded steels. The primary objective of this investigation is to enlarge on previous developments of J and CTOD estimation procedures for this crack configuration while, at the same time, addressing effects of strength mismatch on the plastic η-factors. The present analyses enable the introduction of a larger set of factor η for a wide range of crack sizes (as measured by the a/W-ratio) and material properties, including different levels of weld strength mismatch, applicable to structural, pipeline and pressure vessel steels. Very detailed non-linear finite element analyses for plane-strain models of square groove, center cracked C(T) fracture specimens provide the evolution of load with increased crack mouth opening displacement required for the estimation procedure. Overall, the present study, when taken together with previous investigations, provides a fairly extensive body of results to determine parameters J and CTOD for different materials using C(T) specimens with varying overmatch conditions.

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Pepin, J., C. Penniston, H. Henein, D. G. Ivey, J. B. Wiskel et J. D. Boyd. « The Effects of Squarewave Polarity Parameters on Microalloyed Steel Charpy V-Notch Results ». Dans 2008 7th International Pipeline Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ipc2008-64398.

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The welding processes used to produce microalloyed steel pipe can result in mechanical property changes in the heat affected zone (HAZ) regions of seam and double joint (circumferential) welds. HAZ properties are controlled primarily by the microstructures resulting from the thermal history during welding. While multi-pass welds have successfully achieved CVN values greater than 66.4 ft-lbs (90 J) at the fusion line, this work explores the use of single-OD welds to achieve similar toughness values. Thus, single OD-pass submerged arc welding (SAW) test specimens were produced to examine the effect of electrode polarity on the HAZ Charpy V-notch (CVN) toughness. CVN results indicate that a DC+ lead, AC 50% trail tandem arc setting produces moderately improved CVN test HAZ results at −20°C compared with an AC 75% lead, AC 25% trail tandem arc setting. The difference is believed to be related to differences in effective heat input, though further investigation is required. The CVN specimens notched furthest from the fusion line gave the largest toughness result scatter. The elevated values are believed to be the result of greater lengths of the notch passing through unaffected base metal. Lower values (average CVN from 37 to 59 ft lbs (51 to 80 J)) were produced by notches located at the fusion line, which would pass through significant amounts of coarse grain heat affected zone (CGHAZ). The weld and base metal CVN results for both sets of welding conditions were comparable. Further optimization of welding parameters is required for a single pass weld procedure to achieve HAZ CVN values exceeding 66.4 ft-lbs (90 J) at the fusion line.

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Kim, Nak Hyun, Yun Jae Kim, Catrin M. Davies, Ali Mehmanparast et Kamran M. Nikbin. « The Effect of Discontinuous Crack in Creep Crack Growth Tests ». Dans ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-98142.

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Discontinuous cracks ahead of the leading crack tip may be present in observedcertain creep crack growth tests as well as in components. In this work, a single crack of different dimensions and distance from the leading crack has been numerically modeled in a compact tension specimen using elastic, elastic-plastic and elastic-plastic-creep loading. In order to examine their effects on fracture mechanics parameters a sensitivity analysis was performed to determine the effects of size and distance of the secondary crack with respect to the main crack. t The elastic analysis shows that the compliance is insensitive small cracks ahead of the main crack. Limit load analyses, assuming an elastic-perfectly plastic material, show that the limit load decreases due to the presence of discontinuous cracks ahead of the main crack. Theload versus plastic load-line displacement response of the specimen was significantly influenced by discontinuous cracking. The J contour parameter and C*-integral have been evaluated at the three crack tips and the average of all of them derived for the appropriate contours were compared with the valuesobtained from on ASTM E1820(1) and E1457(2). Whilst the average values of the contour integral are similar to the ASTM J and C* values there is significant differences in J and C* for the individual crack tip values. This need to be further evaluated in future work.

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Cao, Yupeng, et Chen Bao. « Semi-Analytical Solutions of Fracture Parameters for Curved CT Specimen From CANDU Pressure Tube ». Dans ASME 2023 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/pvp2023-106414.

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Abstract The pressure tubes of Zr-2.5Nb are primary pressure boundaries in a CANDU reactor. The major threat to the inservice pressure tubes is posed by Delayed Hydrogen Crack (DHC) initiation and growth. The fracture initiation toughness values are the necessary input data required by CSA N285.8[1]. The curved compact tension (CCT) specimens are recommended. However, the CCT specimen is not a standard specimen specified by ASTM E1820[2]. This paper studies the K factor, the compliance C and the J-integral solutions for the CCT specimen using theoretical analysis and FEA modeling. The modified solutions are compared with the results from the solution for standard CT specimen in E1820 and from FEA. The applicability of the modified solutions is discussed in this paper.

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Hatamleh, Mohammad I., Sepehr Sadeh, Tayyub Farooq, Arif S. Malik et Dong Qian. « Finite Element Study of Laser Peening on Selective Laser Melted A357 Aluminum Alloy During Tension Test ». Dans ASME 2018 13th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/msec2018-6706.

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Laser shock peening (LSP) is an advanced surface treatment technique that can extend fatigue life in metallic components by inducing near-surface compressive residual stresses. In this study, LSP was implemented to induce compressive residual stresses and modify material properties of selective laser melted (SLM) aluminum A357 specimens. An initial hypothesis on the effect of LSP during tension testing was formulated and tested using finite element simulation. The hypothesis was that, due to the LSP-induced tensile residual stress field in the middle of the specimen cross sections, yielding was expected to initiate in this region. True stress-strain curves of two as-built (AB) and two laser shock peened samples were obtained through transverse tensile tests. The single explicit analysis using time dependent damping (SEATD) technique was used to simulate LSP process utilizing Johnson-Cook (J-C) constitutive parameters. J-C parameters for the cast A357 alloy were used for preliminary study. This was followed by the simulation of the transverse tensile test. J-C parameters for SLM A357 alloy were then empirically estimated, and simulations were repeated accordingly. It was found that the specific LSP pattern induced tensile residual stresses along the edges as well as the middle of the test specimen’s cross-section. Axial residual stress and yield strength profiles along three different paths on specimen’s cross-section were compared and yield regions were investigated. This supported the initial hypothesis, but also provided for a more detailed understanding of actual tensile test failure in the specific SLM A357 specimens for the given LSP treatment. In addition, the same LSP treatment on SLM A357 alloy resulted in lower magnitude of compressive residual stress than for cast A357 aluminum alloy.

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Mahmadi, K., M. Souli et N. Aquelet. « Numerical Study of Overdriven Detonation Phenomenon ». Dans ASME 2005 Pressure Vessels and Piping Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pvp2005-71667.

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The overdriven detonation refers to detonation process in which the main detonation parameters, such as detonation pressure and propagating velocity, exceed the corresponding Chapman-Jouguet (C-J) values. This kind of detonation can be occurred when the flyer plate of high velocity impacts the explosive. So, in this work numerical simulation of overdriven detonation (following O.D.D.) phenomenon, which brings out higher detonation pressures than C-J pressure of an explosive is considered. The shock-structure interaction in this fast event is modeled by a penalty coupling, which permits to couple a Lagrangian mesh of the plate to material points of a multi-material Eulerian flow. This technique has been used successfully in many areas of applications, including automotive and industrial fields. By using an explicit finite element method, a good agreement between numerical and experimental results will valid penalty coupling capabilities to solve accurately O.D.D. phenomenon.

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Faidy, Claude. « ASME XI–RSE-M : General Comparison of Flaw Evaluation Rules ». Dans ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93435.

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Abstract After a short review of the 2 Codes in term of flaw evaluation, this paper will compare Scope, Standards, Methods, Material Properties, Structural Factors of 2 major International In-service Codes: ASME Boiler and Pressure Vessel Codes – Section XI – “Rules for In-service Inspection of Nuclear Facility Components”, 2017 Edition and RSE-M “In-Service Inspection Rules for Mechanical Components of PWR Nuclear Island”, 2017 Edition. The cracked components are evaluated by dedicated engineering methods: comparison of fracture mechanic parameters (K/ Kcp, J, C*...) with material properties (toughness KIC, JIC, J resistance curve...) associated to structural factors for margins evaluation. The comparison will consider mainly Appendices A, C of ASME Section XI and Appendix 5 of RSE-M (Appendices 5.0 to 5.8). To conclude, the paper will discuss gaps, needs, ongoing and future developments of both Codes, like Warm-pre stressing, Master Curve, Leak Before Break....

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Seo, Jun-Min, Hune-Tae Kim, Yun-Jae Kim, Hiroyuki Yamada, Tomohisa Kumagai, Hayato Tokunaga et Naoki Miura. « Determination of Johnson-Cook Fracture Strain Model for Austenitic Stainless Steel 304 ». Dans ASME 2022 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/pvp2022-83772.

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Abstract In this study, Johnson-Cook fracture strain model considering the effect of stress triaxiality and strain rate is determined for austenitic stainless steel 304. Tensile test data of four different stress triaxiality and six different strain rate conditions are used to determine the parameters in the J-C fracture strain model. To see the effect of local variation of stress triaxiality and strain rate in the specimen, the J-C fracture models are determined in two different ways. The first case uses the initial stress triaxiality and nominal strain rate, and the second case uses the average value of local stress triaxiality and strain rate obtained from finite element analysis. The use of initial stress triaxiality gives conservative estimate of fracture strain at low stress triaxiality, and non-conservative estimate at high stress triaxiality. The use of nominal strain rate gives overall conservative estimate of fracture strain.

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Rapports d'organisations sur le sujet "J-C PARAMETERS"

Green, M. A. Generation of the J/sub c/, H/sub c/, T/sub c/ surface for commercial superconductor using reduced-state parameters. Office of Scientific and Technical Information (OSTI), avril 1988. http://dx.doi.org/10.2172/6979712.

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Malkinson, Mertyn, Irit Davidson, Moshe Kotler et Richard L. Witter. Epidemiology of Avian Leukosis Virus-subtype J Infection in Broiler Breeder Flocks of Poultry and its Eradication from Pedigree Breeding Stock. United States Department of Agriculture, mars 2003. http://dx.doi.org/10.32747/2003.7586459.bard.

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Objectives 1. Establish diagnostic procedures to identify tolerant carrier birds based on a) Isolation of ALV-J from blood, b) Detection of group-specific antigen in cloacal swabs and egg albumen. Application of these procedures to broiler breeder flocks with the purpose of removing virus positive birds from the breeding program. 2. Survey the AL V-J infection status of foundation lines to estimate the feasibility of the eradication program 3. Investigate virus transmission through the embryonated egg (vertical) and between chicks in the early post-hatch period (horizontal). Establish a model for limiting horizontal spread by analyzing parameters operative in the hatchery and brooder house. 4. Compare the pathogenicity of AL V-J isolates for broiler chickens. 5. Determine whether AL V-J poses a human health hazard by examining its replication in mammalian and human cells. Revisions. The: eradication objective had to be terminated in the second year following the closing down of the Poultry Breeders Union (PBU) in Israel. This meant that their foundation flocks ceased to be available for selection. Instead, the following topics were investigated: a) Comparison of commercial breeding flocks with and without myeloid leukosis (matched controls) for viremia and serum antibody levels. b) Pathogenicity of Israeli isolates for turkey poults. c) Improvement of a diagnostic ELISA kit for measuring ALV-J antibodies Background. ALV-J, a novel subgroup of the avian leukosis virus family, was first isolated in 1988 from broiler breeders presenting myeloid leukosis (ML). The extent of its spread among commercial breeding flocks was not appreciated until the disease appeared in the USA in 1994 when it affected several major breeding companies almost simultaneously. In Israel, ML was diagnosed in 1996 and was traced to grandparent flocks imported in 1994-5, and by 1997-8, ML was present in one third of the commercial breeding flocks It was then realized that ALV-J transmission was following a similar pattern to that of other exogenous ALVs but because of its unusual genetic composition, the virus was able to establish an extended tolerant state in infected birds. Although losses from ML in affected flocks were somewhat higher than normal, both immunosuppression and depressed growth rates were encountered in affected broiler flocks and affected their profitability. Conclusions. As a result of the contraction in the number of international primary broiler breeders and exchange of male and female lines among them, ALV-J contamination of broiler breeder flocks affected the broiler industry worldwide within a short time span. The Israeli national breeding company (PBU) played out this scenario and presented us with an opportunity to apply existing information to contain the virus. This BARD project, based on the Israeli experience and with the aid of the ADOL collaborative effort, has managed to offer solutions for identifying and eliminating infected birds based on exhaustive virological and serological tests. The analysis of factors that determine the efficiency of horizontal transmission of virus in the hatchery resulted in the workable solution of raising young chicks in small groups through the brooder period. These results were made available to primary breeders as a strategy for reducing viral transmission. Based on phylogenetic analysis of selected Israeli ALV-J isolates, these could be divided into two groups that reflected the countries of origin of the grandparent stock. Implications. The availability of a simple and reliable means of screening day old chicks for vertical transmission is highly desirable in countries that rely on imported breeding stock for their broiler industry. The possibility that AL V-J may be transmitted to human consumers of broiler meat was discounted experimentally.

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