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Zakharov, V. E., i A. N. Pushkarev. "Diffusion model of interacting gravity waves on the surface of deep fluid". Nonlinear Processes in Geophysics 6, nr 1 (31.03.1999): 1–10. http://dx.doi.org/10.5194/npg-6-1-1999.
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Abstract. A simple phenomenological model for nonlinear interactions of gravity waves on the surface of deep water is developed. The Snl nonlinear interaction term in the kinetic equation for wave action is replaced by the nonlinear second-order diffusion-type operator. Analytical and numerical studies show that the new model gives a reasonably good description of a real situation, consuming three order of magnitude less computer time.
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Frommater, Stefan, Jens Neumann i Christian Hasse. "A phenomenological mixture homogenization model for spark-ignition direct-injection engines". International Journal of Engine Research 19, nr 2 (6.06.2017): 168–78. http://dx.doi.org/10.1177/1468087417711858.
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In modern turbocharged direct-injection, spark-ignition engines, proper calibration of the engine control unit is essential to handle the increasing variability of actuators. The physically based simulation of engine processes such as mixture homogenization enables a model-based calibration of the engine control unit to identify an ideal set of actuator settings, for example, for efficient combustion with reduced exhaust emissions. In this work, a zero-dimensional phenomenological model for direct-injection, spark-ignition engines is presented that allows the equivalence ratio distribution function in the combustion chamber to be calculated and its development is tracked over time. The model considers the engine geometry, mixing time, charge motion and spray–charge interaction. Accompanying three-dimensional computational fluid dynamics, simulations are performed to obtain information on homogeneity at different operating conditions and to calibrate the model. The calibrated model matches the three-dimensional computational fluid dynamics reference both for the temporal homogeneity development and for the equivalence ratio distribution at the ignition time, respectively. When the model is validated outside the calibrated operating conditions, this shows satisfying results in terms of mixture homogeneity at the time of ignition. Additionally, only a slight modification of the calibration is shown to be required when transferring the model to a comparable engine. While the model is primarily aimed at target applications such as a direct-injection, spark-ignition soot emission model, its application to other issues, such as gaseous exhaust emissions, engine knock or cyclic fluctuations, is conceivable due to its general structure. The fast calculation enables mixture inhomogeneities to be estimated during driving cycle simulations.
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Bušík, Martin, Martin Slavík i Ivan Cimrák. "Dissipative Coupling of Fluid and Immersed Objects for Modelling of Cells in Flow". Computational and Mathematical Methods in Medicine 2018 (27.09.2018): 1–11. http://dx.doi.org/10.1155/2018/7842857.
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Modelling of cell flow for biomedical applications relies in many cases on the correct description of fluid-structure interaction between the cell membrane and the surrounding fluid. We analyse the coupling of the lattice-Boltzmann method for the fluid and the spring network model for the cells. We investigate the bare friction parameter of fluid-structure interaction that is mediated via dissipative coupling. Such coupling mimics the no-slip boundary condition at the interface between the fluid and object. It is an alternative method to the immersed boundary method. Here, the fluid-structure coupling is provided by forces penalising local differences between velocities of the object’s boundaries and the surrounding fluid. The method includes a phenomenological friction coefficient that determines the strength of the coupling. This work aims at determination of proper values of such friction coefficient. We derive an explicit formula for computation of this coefficient depending on the mesh density assuming a reference friction is known. We validate this formula on spherical and ellipsoidal objects. We also provide sensitivity analysis of the formula on all parameters entering the model. We conclude that such formula may be used also for objects with irregular shapes provided that the triangular mesh covering the object’s surface is in some sense uniform. Our findings are justified by two computational experiments where we simulate motion of a red blood cell in a capillary and in a shear flow. Both experiments confirm our results presented in this work.
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Perez, Marta, Emmanuelle Abisset-Chavanne, Elias Cueto, Roland Keunings i Francisco Chinesta. "Fluid-Long Fiber Interaction Based on a Second Gradient Theory". Key Engineering Materials 651-653 (lipiec 2015): 331–37. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.331.
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Most suspension descriptions nowadays employed are based on the Jeffery's model andsome phenomenological adaptations of it that do not take into account size effects, that is, the kinematicsand stresses do not introduce a micro-mechanical characteristic length and thus, the rheologicalproperties become independent of the rod length. New models able to enrich first gradient kinematicsas well as to activate rod-bending mechanisms (needed for explaining the mild elasticity experimentallynoticed) are needed. In this paper we propose a second gradient description able to activate rods bending.
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MANGANO, G., G. MIELE i V. PETTORINO. "COUPLED QUINTESSENCE AND THE COINCIDENCE PROBLEM". Modern Physics Letters A 18, nr 12 (20.04.2003): 831–42. http://dx.doi.org/10.1142/s0217732303009940.
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We consider a model of interacting cosmological constant/quintessence, where dark matter and dark energy behave as, respectively, two coexisting phases of a fluid, a thermally excited Bose component and a condensate, respectively. In a simple phenomenological model for the dark components interaction we find that their energy density evolution is strongly coupled during the universe evolution. This feature provides a possible way out for the coincidence problem affecting many quintessence models.
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Khurshudyan, M., J. Sadeghi, E. Chubaryan i H. Farahani. "Phenomenologically varying Λ and a toy model for the universe". Canadian Journal of Physics 92, nr 11 (listopad 2014): 1494–500. http://dx.doi.org/10.1139/cjp-2014-0103.
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We consider a model of the Universe with variable G and Λ. The subject of interest is a phenomenological model for Λ proposed and considered in this article for the first time (to our knowledge), with the assumption that ghost dark energy exists and interacts with the Universe through Λ. We consider the possibility that there exist unusual connections between different components of the fluids in Universe. We would like to stress that this is simply an assumption and could be very far from reality. This model is interesting phenomenologically and mathematically but we will not discuss physical conditions or possibilities of implementing the modifications. To test our assumption and to observe the behavior of the Universe, we will consider toy models filled by a barotropic fluid and modified Chaplyagin gas. Finally, we will consider interaction between barotropic fluid or Chaplygin gas and ghost dark energy as a separate scenario. The statefinder diagnostic provided stability analysis of the models. All free parameters of the model are fixed to satisfy the generalized second law of thermodynamics.
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Gonchar, Liudmila, i Anatoliy Nikiforov. "Vibronic interaction as main reason of magnetic ordering in insulating manganites R1–xAxMnO3". EPJ Web of Conferences 185 (2018): 06005. http://dx.doi.org/10.1051/epjconf/201818506005.
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The model of orbitally dependent magnetic structure of charge ordered insulated manganites is proposed. The model is semi-phenomenological. It allows using a few parameters to describe possible magnetic structures of compounds. The experimental crystal structure of compounds also could be taken into account. The compounds LaMnO3, La1/2Ca1/2MnO3, La1/3Ca2/3MnO3, BiMnO3 are considered.
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Pushkarev, A., D. Resio i V. Zakharov. "Second generation diffusion model of interacting gravity waves on the surface of deep fluid". Nonlinear Processes in Geophysics 11, nr 3 (27.07.2004): 329–42. http://dx.doi.org/10.5194/npg-11-329-2004.
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Abstract. We propose a second generation phenomenological model for nonlinear interaction of gravity waves on the surface of deep water. This model takes into account the effects of non-locality of the original Hasselmann diffusion equation still preserving important properties of the first generation model: physically consistent scaling, adherence to conservation laws and the existence of Kolmogorov-Zakharov solutions. Numerical comparison of both models with the original Hasselmann equation shows that the second generation models improves the angular distribution in the evolving wave energy spectrum.
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Zhang, Ying. "A unified Yukawa interaction for the Standard Model of quarks and leptons". Modern Physics Letters A 36, nr 27 (7.09.2021): 2150196. http://dx.doi.org/10.1142/s0217732321501960.
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To address fermion mass hierarchy and flavor mixings in the quark and lepton sectors, a minimal flavor structure without any redundant parameters beyond phenomenological observables is proposed via decomposition of the Standard Model Yukawa mass matrix into a bi-unitary form. After reviewing the roles and parameterization of the factorized matrix [Formula: see text] and [Formula: see text] in fermion masses and mixings, we generalize the mechanism to up- and down-type fermions to unify them into a universal quark/lepton Yukawa interaction. In the same way, a unified form of the description of the quark and lepton Yukawa interactions is also proposed, which shows a similar picture as the unification of gauge interactions.
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da Rocha, Roldão. "MGD Dirac Stars". Symmetry 12, nr 4 (1.04.2020): 508. http://dx.doi.org/10.3390/sym12040508.
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The method of geometric deformation (MGD) is here employed to study compact stellar configurations, which are solutions of the effective Einstein–Dirac coupled field equations on fluid branes. Non-linear, self-interacting, fermionic fields are then employed to derive MGD Dirac stars, whose properties are analyzed and discussed. The MGD Dirac star maximal mass is shown to increase as a specific function of the spinor self-interaction coupling constant, in a realistic model involving the most strict phenomenological current bounds for the brane tension.
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DERRETH, CH, H. TH ELZE i W. GREINER. "NUCLEAR MATTER STABILITY IN A SOLITON MODEL FOR FINITE NUCLEI". International Journal of Modern Physics E 01, nr 02 (czerwiec 1992): 249–68. http://dx.doi.org/10.1142/s0218301392000126.
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A relativistic band structure method for the computation of the electronic structure of atomic clusters is adapter to the Friedberg–Lee nontopological soliton model. Thus, finite nuclei can be studied in the soliton model. As a verification of our method, we calculated the equation of state of nuclear matter. In order to achieve nuclear matter stability, we added the colour magnetic interaction for an inhomogeneous dielectric medium as well as a phenomenological residual interaction to the soliton model. Both modifications are examined in detail. Nuclear matter stability near the empirical ground state density and binding energy has been achieved.
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Nennemann, B., C. Monette, O. Braun, Daniel Biner i Cécile Münch-Alligné. "Eigenfrequencies of rotating discs in dense fluid: imposed modal motion approach". IOP Conference Series: Earth and Environmental Science 1079, nr 1 (1.09.2022): 012072. http://dx.doi.org/10.1088/1755-1315/1079/1/012072.
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Abstract The mode split on disc like structures rotating in a dense fluid leads to a deviation of eigenfrequencies at high rotational speeds compared to their values in still water. Predicting eigenfrequencies correctly is essential to avoid fatigue cracks on prototype turbine runners. Analytical models for simple geometric configurations and complex numerical models using fully coupled fluid structure interaction to predict the mode split on arbitrary geometries exist. We are presenting a complementary approach of intermediate complexity applicable to arbitrary geometries. Mode shapes and modal parameters are computed by finite element analysis in still water. These mode shapes are imposed with a harmonic variation in time during an unsteady computational fluid dynamics computation. From the interaction between the flow and the modal motion, the modal force and the modal work can be computed. These can be converted into added modal mass and hydrodynamic damping and further into the shift of the eigenfrequency under rotation due to the fluid for a given mode. The tendencies of the frequencies with rotation compare reasonably well with experimental data. The numerical method can be applied to disc rotation speeds far beyond the range of experimental data revealing interesting tendencies and a phenomenological interpretation of the cause of the mode split.
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Mahata, Nilanjana, i Subenoy Chakraborty. "Dynamical system analysis for DBI dark energy interacting with dark matter". Modern Physics Letters A 30, nr 02 (15.01.2015): 1550009. http://dx.doi.org/10.1142/s0217732315500091.
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A dynamical system analysis related to Dirac–Born–Infeld (DBI) cosmological model has been investigated in this present work. For spatially flat FRW spacetime, the Einstein field equation for DBI scenario has been used to study the dynamics of DBI dark energy interacting with dark matter. The DBI dark energy model is considered as a scalar field with a nonstandard kinetic energy term. An interaction between the DBI dark energy and dark matter is considered through a phenomenological interaction between DBI scalar field and the dark matter fluid. The field equations are reduced to an autonomous dynamical system by a suitable redefinition of the basic variables. The potential of the DBI scalar field is assumed to be exponential. Finally, critical points are determined, their nature have been analyzed and corresponding cosmological scenario has been discussed.
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Córdoba, G., M. F. Sheridan i E. B. Pitman. "TITAN2F: a pseudo-3-D model of 2-phase debris flows". Natural Hazards and Earth System Sciences Discussions 3, nr 6 (12.06.2015): 3789–822. http://dx.doi.org/10.5194/nhessd-3-3789-2015.
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Abstract. Debris flows, avalanches, landslides, and other geophysical mass flows can contain O(106–1010) m3 or more of material. These flows commonly consist of mixture of soil and rocks with a significant quantity of interstitial fluid. They can be tens of meters deep, and their runouts can extend many kilometers. The complicated rheology of such a mixture challenges every constitutive model that can reasonably be applied; the range of length and timescales involved in such mass flows challenges the computational capabilities of existing systems.This paper extends recent efforts to develop a depth averaged "thin layer" model for geophysical mass flows that contain a mixture of solid material and fluid. Concepts from the engineering community are integrated with phenomenological findings in geo-science, resulting in a theory that accounts for the principal solid and fluid forces as well as interactions between the phases, across a wide range of solid volume fraction. A principal contribution here is to present drag and phase interaction terms that comport with the literature in geo-sciences. The program predicts the evolution of the concentration and dynamic pressure. The theory is validated with with data from one dimensional dam break solutions and it is verified with data from artificial channel experiments.
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Battistel, Orimar Antônio. "Partículas e interações fundamentais". Ciência e Natura 14, nr 14 (14.12.1992): 71. http://dx.doi.org/10.5902/2179460x26317.
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We present a discussion of some of the ideas and facts that led to the modern conception of the structure of matter in terms of basic constituents and fundamental interactions. We discuss the construction of the quark model in a historical context, stressing that the phenomenological knowledge of particle properties induced the mathematical formalism. The interaction between quarks is discussed in the framework of the color force based on the exchange of gluons. For the sake of completeness we mention briefly the microworld structure that emerged from these new ideas.
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Stroberg, S. Ragnar, Heiko Hergert, Scott K. Bogner i Jason D. Holt. "Nonempirical Interactions for the Nuclear Shell Model: An Update". Annual Review of Nuclear and Particle Science 69, nr 1 (19.10.2019): 307–62. http://dx.doi.org/10.1146/annurev-nucl-101917-021120.
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The nuclear shell model has perhaps been the most important conceptual and computational paradigm for the understanding of the structure of atomic nuclei. While the shell model has been used predominantly in a phenomenological context, there have been efforts stretching back more than half a century to derive shell model parameters based on a realistic interaction between nucleons. More recently, several ab initio many-body methods—in particular, many-body perturbation theory, the no-core shell model, the in-medium similarity renormalization group, and coupled-cluster theory—have developed the capability to provide effective shell model Hamiltonians. We provide an update on the status of these methods and investigate the connections between them and their potential strengths and weaknesses, with a particular focus on the in-medium similarity renormalization group approach. Three-body forces are demonstrated to be important for understanding the modifications needed in phenomenological treatments. We then review some applications of these methods to comparisons with recent experimental measurements, and conclude with some remaining challenges in ab initio shell model theory.
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de Bruin, Leon Rene. "Shaping interpersonal learning in the jazz improvisation lesson: Observing a dynamic systems approach". International Journal of Music Education 36, nr 2 (13.07.2017): 160–81. http://dx.doi.org/10.1177/0255761417712318.
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Music institutions predominantly utilize the one-to-one lesson in developing and supporting music students’ learning of skill and knowledge. This article explores the effect that interpersonal interaction plays in shaping pedagogical applications between teacher and student. Observing the learning of improvisation within this individualized social context, dynamic systems theory (DST) is used to explore how learning and development of musical improvisation skills are shaped by interpersonal behaviors and learning relationships. Through the dimensions of teacher “action” and “affiliation”, this phenomenological study investigates the interactive behaviors of five expert Australian educator/improvisers and their students. Interpretative phenomenological analysis is utilized to identify modes of behavioral interactions that evolve through dynamic and fluid interplay. Interactive behavior positions and facilitates the delivery of skill, knowledge, teacher attitudes and understandings of the improvisation process. An interpersonal model of behaviors within the instrumental music lesson is posited, and implications for ongoing critical reflection of interpersonal and pedagogical approaches in the one-to-one context are suggested.
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JACOBSEN, RAFAEL B., CÉSAR A. Z. VASCONCELLOS, BARDO E. J. BODMANN i DIMITER HADJIMICHEF. "ON THE ROLE OF THE ADIABATIC INDEX IN THE STABILITY OF NEUTRON STARS". International Journal of Modern Physics D 16, nr 02n03 (luty 2007): 261–67. http://dx.doi.org/10.1142/s0218271807009991.
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We study the influence of interaction strengths on nuclear properties and global static properties of neutron stars with emphasis on the adiabatic index, considering also the constraint of chemical equilibrium and charge neutrality. We develop an equation of state (EoS) in the framework of an extended effective QHD model using a parameterized phenomenological Lagrangian density containing the fundamental baryon octet, the σ, ω and ϱ meson fields and the lightest charged leptons. The results of our approach show that, for a small range of values of the baryon–meson coupling parameters, we can consistently describe nuclear matter and the structure of neutron stars. Our results indicate that in the energy density range above hyperon thresholds, the behavior of the adiabatic index is roughly comparable to the corresponding one in the case of an extreme relativistic hydrodynamical perfect fluid.
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Jain, Arvind, Shubhangi Soni, Sanjay Shah i Netram Kaurav. "Theoretical Analysis of the Structural Phase Transformation and Elastic Properties in the ZrN under High Pressure". Journal of Metastable and Nanocrystalline Materials 28 (grudzień 2016): 101–7. http://dx.doi.org/10.4028/www.scientific.net/jmnm.28.101.
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We report a phenomenological model based calculation of pressure-induced structural phase transition and elastic properties of ZrN compound. Gibb’s free energy is obtained as a function of pressure by applying an effective interionic interaction potential, which includes the long range Coulomb, van der Waals (vdW) interaction and the short-range repulsive interaction upto second-neighbor ions within the Hafemeister and Flygare approach. From the present study, we predict a structural phase transition from NaCl structure (B1) to the CsCl structure (B2). The variations of elastic constants with pressure follow a systematic trend identical to that observed in others compounds of NaCl type structure family.
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Benchikh, I. L., i L. Aissaoui. "Shell-model calculations of the spectroscopic properties of neutron-rich calcium isotopes around 40,48Ca cores". Journal of Ovonic Research 18, nr 1 (luty 2022): 21–28. http://dx.doi.org/10.15251/jor.2022.181.21.
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With the aim of predicting the possible existence of new magic numbers, we theoretically studied the recently available experimental data for spectroscopic properties of the neutron rich even-even calcium isotopes around Ca 40,48 doubly magic cores. The calculations were performed with the phenomenological interactions for fppn and HO model spaces using the nuclear structure code Nushell. The two-body matrix elements (TBMEs) of the new effective interaction KB3G48 were derived from the microscopic Kuo-Brown’s G-matrix interaction KB3GPN for Ca 40 core. The calculated energies 𝐸(21 +) of the first excited state, the ratio 𝑅4/2 of the excitation energies, the reduced electric transition probabilities 𝐵(𝐸2; 21 + → 01 +) and the ratio 𝐵4/2 of reduced transition probabilities are compared with the available experimental data. The results of this study are an attempt to demonstrate that 𝑁 = 32 or 𝑁 = 34 are new magic numbers for Ca isotopes.
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Chen, Zhanghui, i Lin-Wang Wang. "Role of initial magnetic disorder: A time-dependent ab initio study of ultrafast demagnetization mechanisms". Science Advances 5, nr 6 (czerwiec 2019): eaau8000. http://dx.doi.org/10.1126/sciadv.aau8000.
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Despite more than 20 years of development, the underlying physics of the laser-induced demagnetization process is still debated. We present a fast, real-time time-dependent density functional theory (rt-TDDFT) algorithm together with the phenomenological atomic Landau-Lifshitz-Gilbert model to investigate this problem. Our Hamiltonian considers noncollinear magnetic moment, spin-orbit coupling (SOC), electron-electron, electron-phonon, and electron-light interactions. The algorithm for time evolution achieves hundreds of times of speedup enabling calculation of large systems. Our simulations yield a demagnetization rate similar to experiments. We found that (i) the angular momentum flow from light to the system is not essential and the spin Zeeman effect is negligible. (ii) The phonon can play a role but is not essential. (iii) The initial spin disorder and the self-consistent update of the electron-electron interaction play dominant roles and enhance the demagnetization to the experimentally observed rate. The spin disorder connects the electronic structure theory with the phenomenological three-temperature model.
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KOVALENKO, ANDRIY, i FUMIO HIRATA. "TOWARDS A MOLECULAR THEORY FOR THE VAN DER WAALS–MAXWELL DESCRIPTION OF FLUID PHASE TRANSITIONS". Journal of Theoretical and Computational Chemistry 01, nr 02 (październik 2002): 381–406. http://dx.doi.org/10.1142/s0219633602000282.
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We briefly review developments of theories for phase transitions of molecular fluids and mixtures, from semi-phenomenological approaches providing equations of state with adjustable parameters to first-principles microscopic methods qualitatively correct for a variety of molecular models with realistic interaction potentials. We further present the generalization of the van der Waals–Maxwell description of fluid phase diagrams to account for chemical specificities of polar molecular fluids, such as hydrogen bonding. Our theory uses the reference interaction site model (RISM) integral equation approach complemented with the new closure we have proposed (KH approximation), successful over a wide range of density from gas to liquid. The RISM/KH theory is applied to the known three-site models of water, methanol, and hydrogen fluoride. It qualitatively reproduces their vapor-liquid phase diagrams and the structure in the gas as well as liquid phases, including hydrogen bonding. Furthermore, phase transitions of water and methanol sorbed in nanoporous carbon aerogel are described by means of the replica generalization of the RISM approach we have developed. The changes as compared to the bulk fluids are in agreement with simulations and experiment. The RISM/KH theory is promising for description of phase transitions in various associating fluids, in particular, electrolyte as well as non-electrolyte solutions and ionic liquids.
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Dey, Jayanta, Sarthak Satapathy, Ankita Mishra, Souvik Paul i Sabyasachi Ghosh. "From noninteracting to interacting picture of quark–gluon plasma in the presence of a magnetic field and its fluid property". International Journal of Modern Physics E 30, nr 06 (czerwiec 2021): 2150044. http://dx.doi.org/10.1142/s0218301321500440.
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We have attempted to build a parametric-based simplified and analytical model to map the interaction of quarks and gluons in the presence of magnetic field, which has been constrained by quark condensate and thermodynamical quantities like pressure, energy density, etc., obtained from the calculation of lattice quantum chromodynamics (QCDs). To fulfill that mapping, we have assumed a parametric temperature and magnetic field-dependent degeneracy factor, average energy, momentum and velocity of quarks and gluons. Implementing this QCD interaction in calculation of transport coefficient at finite magnetic field, we have noticed that magnetic field and interaction both are two dominating sources, for which the values of transport coefficients can be reduced. Though the methodology is not so robust, but with the help of its simple parametric expressions, one can get a quick rough estimation of any phenomenological quantity, influenced by temperature and magnetic field-dependent QCD interaction.
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RASHDAN, M. "TEST OF NL-RA1 RELATIVISTIC EFFECTIVE INTERACTION FOR THE STRUCTURE OF DEFORMED AND SUPERHEAVY NUCLEI". International Journal of Modern Physics E 21, nr 06 (czerwiec 2012): 1250055. http://dx.doi.org/10.1142/s0218301312500553.
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The NL-RA1 effective interaction of the relativistic mean field theory is employed to study the structure of deformed and superheavy nuclei, using an axially deformed harmonic oscillator basis. It is found that a fair agreement with the experimental data is obtained for the binding energies (BE), deformation parameters and charge radii. Comparison with NL-Z2, NLSH and NL3 interactions show that NL-Z2 gives good binding but larger radii, while NL-SH gives good radii but larger binding. The NL-RA1 interaction is also tested for the new deformed superheavy element with Z≥98. Excellent agreement with the experimental binding is obtained, where the relative error in BEs of Cf, Fm, No, Rf, Sg and Ea (Z = 110) isotopes are found to be of the order ~0.1%. The NL3 predicted larger binding and larger relative errors ~0.2–0.5%. Furthermore, the experimental Q-values of the alpha-decay of the superheavy elements 270110, 288114 and 292116 are satisfactory reproduced by NL-RA1 interaction, where the agreement is much better than that predicted by the phenomenological mass FRDM model. Furthermore, the alpha-decay chain of element 294118 are also better reproduced by NL-RA1 interaction.
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Karampagia, S., i V. Zelevinsky. "Nuclear shell model and level density". International Journal of Modern Physics E 29, nr 06 (czerwiec 2020): 2030005. http://dx.doi.org/10.1142/s0218301320300052.
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The accurate knowledge of the nuclear level density is crucial for understanding the nuclear structure and for numerous applications including astrophysical reactions. In this review paper, we discuss the shell-model description of the nuclear level density, the use of the statistical moments method and underlying physics. The level density found with the moments method is shown to agree with the results of the exact diagonalization of the Hamiltonian matrix. The statistical approach is also compared to other standard methods for deriving level densities. The role of specific interaction matrix elements is reviewed in connection to the behavior of the level densities as these evolve. Chaotization and thermalization processes, collective enhancement and phase transitions are discussed with changing strengths of specific groups of two-body interaction matrix elements. The popular phenomenological constant temperature model is compared to the moments method and the effective temperature parameter of the model for different isotopes is discussed.
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Li, Haijing, Herman J. H. Clercx i Federico Toschi. "Lattice Boltzmann method investigation of a reactive electro-kinetic flow in porous media: towards a phenomenological model". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 379, nr 2208 (30.08.2021): 20200398. http://dx.doi.org/10.1098/rsta.2020.0398.
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A model based on the Lattice Boltzmann method is developed to study the flow of reactive electro-kinetic fluids in porous media. The momentum, concentration and electric/potential fields are simulated via the Navier–Stokes, advection–diffusion/Nernst–Planck and Poisson equations, respectively. With this model, the total density and velocity fields, the concentration of reactants and reaction products, including neutral and ionized species, the electric potential and the interaction forces between the fields can be studied, and thus we provide an insight into the interplay between chemistry, flow and the geometry of the porous medium. The results show that the conversion efficiency of the reaction can be strongly influenced by the fluid velocity, reactant concentration and by porosity of the porous medium. The fluid velocity determines how long the reactants stay in the reaction areas, the reactant concentration controls the amount of the reaction material and with different dielectric constant, the porous medium can distort the electric field differently. All these factors make the reaction conversion efficiency display a non-trivial and non-monotonic behaviour as a function of the flow and reaction parameters. To better illustrate the dependence of the reaction conversion efficiency on the control parameters, based on the input from a number of numerical investigations, we developed a phenomenological model of the reactor. This model is capable of capturing the main features of the causal relationship between the performance of the reactor and the main test parameters. Using this model, one could optimize the choice of reaction and flow parameters in order to improve the performance of the reactor and achieve higher production rates. This article is part of the theme issue ‘Progress in mesoscale methods for fluid dynamics simulation’.
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VARSHNEY, DINESH. "PRESSURE INDUCED PHASE TRANSITION (B3–B1) AND ELASTIC PROPERTIES OF II–VI ZnSe SEMICONDUCTORS". International Journal of Modern Physics B 26, nr 14 (16.05.2012): 1250077. http://dx.doi.org/10.1142/s0217979212500774.
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We evolve an effective interionic interaction potential (EIoIP) to investigate the pressure induced phase transitions from Zinc blende (B3) to Rocksalt (B1) structure in ZnSe semiconductor. The developed potential consists of the long-range Coulomb and three-body interactions (TBI) and the Hafemeister and Flygare type short-range (SR) overlap repulsion extended upto the second neighbor ions and the van der Waals (vdW) interaction. The three-body interactions arise from the electron-shell deformation when the nearest-neighbor ions overlap and has been employed for detailed studies of pressure-induced phase-transition behavior of ZnSe semiconductors. Our calculated value of the phase transition pressure (Pt) is higher and the magnitude of the discontinuity in volume at the transition pressure is consistent with reported data. The variation of second-order elastic constants with pressure resembles that observed in some binary semiconductors. It is inferred that the vdW interaction is effective in obtaining the Debye temperature, Gruneisen parameter, thermal expansion coefficient and compressibility. It is argued that the model with TBI (model II) has yielded somewhat more realistic predictions of the phase-transition and high-pressure behavior as compared to usual two-body potentials (model I) based on phenomenological approach.
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Kuksa, Vladimir, i Vitaly Beylin. "Hyperfine Splitting of Excited States of New Heavy Hadrons and Low-Energy Interaction of Hadronic Dark Matter with Photons, Nucleons, and Leptons". Universe 6, nr 6 (19.06.2020): 84. http://dx.doi.org/10.3390/universe6060084.
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We consider the structure of excited states and low-energy interaction of hadronic dark matter with photons, leptons, and nucleons. Description of the lowest excited levels is fulfilled in an analogy with the standard heavy-light mesons. Using the effective vertex of new heavy hadrons interaction with W-boson, we calculate cross-section of the lepton scattering on the dark matter particle. Analysis of strong low-energy interaction of new hadrons was carried out within the effective meson-exchange model based on dynamical realization of SU(3)-symmetry. A cross-section of nucleon scattering on the hadronic dark matter was also calculated using this model. The most essential phenomenological consequences of the low-energy dark matter interaction with leptons and nucleons are discussed.
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Guan, Peng, Yanting Ai, Chengwei Fei i Yudong Yao. "Thermal Fatigue Life Prediction of Thermal Barrier Coat on Nozzle Guide Vane via Master–Slave Model". Applied Sciences 9, nr 20 (16.10.2019): 4357. http://dx.doi.org/10.3390/app9204357.
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The aim of this paper was to develop a master–slave model with fluid-thermo-structure (FTS) interaction for the thermal fatigue life prediction of a thermal barrier coat (TBC) in a nozzle guide vane (NGV). The master–slave model integrates the phenomenological life model, multilinear kinematic hardening model, fully coupling thermal-elastic element model, and volume element intersection mapping algorithm to improve the prediction precision and efficiency of thermal fatigue life. The simulation results based on the developed model were validated by temperature-sensitive paint (TSP) technology. It was demonstrated that the predicted temperature well catered for the TSP tests with a maximum error of less than 6%, and the maximum thermal life of TBC was 1558 cycles around the trailing edge, which is consistent with the spallation life cycle of the ceramic top coat at 1323 K. With the increase of pre-oxidation time, the life of TBC declined from 1892 cycles to 895 cycles for the leading edge, and 1558 cycles to 536 cycles for the trailing edge. The predicted life of the key points at the leading edge was longer by 17.7–40.1% than the trailing edge. The developed master–slave model was validated to be feasible and accurate in the thermal fatigue life prediction of TBC on NGV. The efforts of this study provide a framework for the thermal fatigue life prediction of NGV with TBC.
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Arora, N., C. K. Kang, W. Shyy i A. Gupta. "Analysis of passive flexion in propelling a plunging plate using a torsion spring model". Journal of Fluid Mechanics 857 (25.10.2018): 562–604. http://dx.doi.org/10.1017/jfm.2018.736.
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We mimic a flapping wing through a fluid–structure interaction (FSI) framework based upon a generalized lumped-torsional flexibility model. The developed fluid and structural solvers together determine the aerodynamic forces, wing deformation and self-propelled motion. A phenomenological solution to the linear single-spring structural dynamics equation is established to help offer insight and validate the computations under the limit of small deformation. The cruising velocity and power requirements are evaluated by varying the flapping Reynolds number ($20\leqslant Re_{f}\leqslant 100$), stiffness (represented by frequency ratio,$1\lesssim \unicode[STIX]{x1D714}^{\ast }\leqslant 10$) and the ratio of aerodynamic to structural inertia forces (represented by a dimensionless parameter$\unicode[STIX]{x1D713}$($0.1\leqslant \unicode[STIX]{x1D713}\leqslant 3$)). For structural inertia dominated flows ($\unicode[STIX]{x1D713}\ll 1$), pitching and plunging are shown to always remain in phase ($\unicode[STIX]{x1D719}\approx 0$) with the maximum wing deformation occurring at the end of the stroke. When aerodynamics dominates ($\unicode[STIX]{x1D713}>1$), a large phase difference is induced ($\unicode[STIX]{x1D719}\approx \unicode[STIX]{x03C0}/2$) and the maximum deformation occurs at mid-stroke. Lattice Boltzmann simulations show that there is an optimal$\unicode[STIX]{x1D714}^{\ast }$at which cruising velocity is maximized and the location of optimum shifts away from unit frequency ratio ($\unicode[STIX]{x1D714}^{\ast }=1$) as$\unicode[STIX]{x1D713}$increases. Furthermore, aerodynamics administered deformations exhibit better performance than those governed by structural inertia, quantified in terms of distance travelled per unit work input. Closer examination reveals that although maximum thrust transpires at unit frequency ratio, it is not transformed into the highest cruising velocity. Rather, the maximum velocity occurs at the condition when the relative tip displacement${\approx}\,0.3$.
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Sun, Y., M. Beshara, R. J. Lucariello i S. A. Chiaramida. "A comprehensive model for right-left heart interaction under the influence of pericardium and baroreflex". American Journal of Physiology-Heart and Circulatory Physiology 272, nr 3 (1.03.1997): H1499—H1515. http://dx.doi.org/10.1152/ajpheart.1997.272.3.h1499.
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A phenomenological model of the cardiopulmonary circulation is developed with a focus on the interaction between the right heart and the left heart. The model predicts the hemodynamic consequences of changing circulatory parameters in terms of a broad spectrum of pressure and flow waveforms. Hemodynamics are characterized by use of an electrical analog incorporating mechanisms for transseptal pressure coupling, pericardial volume coupling, intrathoracic pressure, and baroreflex control of heart rate. Computer simulations are accomplished by numerically integrating 28 differential equations that contain nonlinear and time-varying coefficients. Validity of the model is supported by its accurate fit to clinical pressure and Doppler echocardiographic recordings. The model characterizes the hemodynamic waveforms for mitral stenosis, mitral regurgitation, left heart failure, right heart failure, cardiac tamponade, pulsus paradoxus, and the Valsalva maneuver. The wave shapes of pulmonary capillary wedge pressure under the above conditions are also accurately represented. Sensitivity analysis reveals that simulated hemodynamics are insensitive to most individual model parameters with the exception of afterload resistance, preload capacitances, intrathoracic pressure, contractility, and pericardial fluid volume. Baseline hemodynamics are minimally affected by transseptal coupling (up to 2%) and significantly affected by pericardial coupling (up to 20%). The model should be useful for quantitative studies of cardiopulmonary dynamics related to the right-left heart interaction under normal and disease conditions.
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FUKS, BENJAMIN. "BEYOND THE MINIMAL SUPERSYMMETRIC STANDARD MODEL: FROM THEORY TO PHENOMENOLOGY". International Journal of Modern Physics A 27, nr 07 (20.03.2012): 1230007. http://dx.doi.org/10.1142/s0217751x12300074.
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Thanks to the latest development in the field of Monte Carlo event generators and satellite programs allowing for a straightforward implementation of any beyond the Standard Model theory in those tools, studying the property of any softly-broken supersymmetric theory is become an easy task. We illustrate this statement in the context of two nonminimal supersymmetric theories, namely the Minimal Supersymmetric Standard Model with R-parity violation and the Minimal R-symmetric Supersymmetric Standard Model and choose to probe interaction vertices involving a nonstandard color structure and the sector of the top quark. We show how to efficiently implement these theories in the MATHEMATICA package FEYNRULES and use its interfaces to Monte Carlo tools for phenomenological studies. For the latter, we employ the latest version of the MADGRAPH program.
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Ignace, Richard, Nicole St-Louis i Raman K. Prinja. "Radio variability from corotating interaction regions threading Wolf–Rayet winds". Monthly Notices of the Royal Astronomical Society 497, nr 1 (10.07.2020): 1127–34. http://dx.doi.org/10.1093/mnras/staa2014.
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ABSTRACT The structured winds of single massive stars can be classified into two broad groups: stochastic structure and organized structure. While the former is typically identified with clumping, the latter is typically associated with rotational modulations, particularly the paradigm of corotating interaction regions (CIRs). While CIRs have been explored extensively in the ultraviolet band, and moderately in the X-ray and optical, here we evaluate radio variability from CIR structures assuming free–free opacity in a dense wind. Our goal is to conduct a broad parameter study to assess the observational feasibility, and to this end, we adopt a phenomenological model for a CIR that threads an otherwise spherical wind. We find that under reasonable assumptions, it is possible to obtain radio variability at the 10 per cent level. The detailed structure of the folded light curve depends not only on the curvature of the CIR, the density contrast of the CIR relative to the wind, and viewing inclination, but also on wavelength. Comparing light curves at different wavelengths, we find that the amplitude can change, that there can be phase shifts in the waveform, and the entire waveform itself can change. These characterstics could be exploited to detect the presence of CIRs in dense, hot winds.
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Dimitriu, Valeriu Gabriel. "The Triadic Structure of the Human Psychism – between Psychopathology and Theology". Revista Psicopatologia Fenomenológica Contemporânea 4, nr 1 (17.10.2015): 104–23. http://dx.doi.org/10.37067/rpfc.v4i1.1003.
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The aim of this work is to present the triontic theory of the normal and pathological human psychism, elaborated by the Romanian psychiatrist Eduard Pamfil, and to highlight its deep connection with the Holy Trinity model of God. The main idea of the work is that mental illness, considered from a wider anthropo-phenomenological perspective, appears as the result of a deficit within interpersonal communication and, in a deeper way, of the lack of communion between human persons. According to Pamfil, the conscious human being is the result of the interaction of its three poles: I (ipseity), You (tui-ty) and He (ille-ity). Pamfil emphasises the inter-ontic nature of the person, its unity and uniqueness. I (ipseity), stands for the “archaic-primitive condition of the person”. You (tui-ty) stands for the “alter ego function”, the structural pole of personality. He (ille-ity) is the “systemic, axiological pole”. Thus, personality is a “mobile crossroad” between I, You and He, which are “moments of phenomenological subjectivity”. The psychopathological commentary of mental illness is made for three major clinical entities: neurosis, psychosis, psychopathy. The above presented theory is closely related to the Orthodox view of human person, who has its spiritual and moral model in the Holy Trinty of God. The modification of the triontic structure of the human person will lead to important changes in the existence of each person (I, You, He) within the trinitary relational system, among which mental illness is certainly the most significant.
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Nguyen, T., i A. Oloyede. "Predictive rheological models for the consolidation behaviour of articular cartilage under static loading". Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 215, nr 6 (1.06.2001): 565–77. http://dx.doi.org/10.1243/0954411011536172.
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This paper evaluates an existing rheological model of articular cartilage and explores the representative capacity of other phenomenological models of the tissue's matrix within the framework of mechanical consolidation. A unique feature is the introduction of a swelling element in tandem with ‘fluid-filled’ hyperelastic rheological elements to predict the transient load-induced behaviour of the tissue and evaluate the role of swelling in determining its load-carriage mechanism. The rheological models proposed have been used to predict the dependence of the one-dimensional consolidation response of the articular cartilage matrix, and the results obtained have been compared with published experimental results. This comparison demonstrates that the hydrostatic excess pore pressure, especially in the initial stages of deformation cannot be predicted without an adequate representation of swelling and its non-linear interaction with mechanical governing parameters such as permeability and stiffness.
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Yanovsky, Yu G., V. E. Zgaevskii, A. V. Teplukhin i Yu N. Karnet. "RHEOLOGICAL PROPERTIES OF ER-FLUIDS IN TERM OF MULTIPARTICLE PHYSICAL MODEL AND MONTE-CARLO COMPUTER SIMULATION". International Journal of Modern Physics B 19, nr 07n09 (10.04.2005): 1184–90. http://dx.doi.org/10.1142/s0217979205030049.
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An electrorheological fluids (ERF) are the suspensions consisting of dielectric rigid particles in the viscous (or viscoelastic) media. Based on the three-dimensional well-ordered multi-particle model (the crystal model) we describe rheological properties of ERF. We use the model of cubic body-centered lattice. We also assume that the electric field is orthogonal to the velocity of shear of fluid's layers. The displacement gradients are assumed to be different (from small to finite values). For small deformations in the framework of the approach proposed and under assumptions made it was stated that the ERF can be treated as a viscoelastic body and it is consequently described on the basis of the linear theory of viscoelasticity. We obtain a complex dynamic shear modulus as a function of the electric field strength, volume fraction of filler, electric properties of components of ERF and viscosity of the fluid phase. For finite deformation the relation between stresses and shear rate gradients has also been made. The relation does not keeps whatever phenomenological or arbitrary parameters and takes into account contribution an electrostatic interaction painted by external field dipoles. From other side a bunch of computational experiments by Monte-Carlo approximation to model both the structure and the peculiarities of ERF were made. We use a procedure by Metropolis for canonic NVT ensemble and parallel computational technologies. The structural characteristics, density, energetic parameter and others for system under consideration have been estimated. In order to verify a theoretical predictions we compare both approaches and some experimental data.
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Kotsyubynsky, V., V. Moklyak i A. Hrubiak. "Synthesis and Mossbauer studies of mesoporous γ-Fe2O3". Materials Science-Poland 32, nr 3 (1.09.2014): 481–86. http://dx.doi.org/10.2478/s13536-014-0202-4.
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AbstractA method of synthesis of mesoporous γ-Fe2O3 by thermal decomposition of iron citrate has been proposed. Investigations of the crystalline and magnetic structure of obtained materials were done. Nanodispersed maghemite (γ-Fe2O3) with the sizes of coherent scattering regions of about 4–7 nm consisted of one phase only after gel sintering at 200, 250 and 300 °C. The particles of synthesized materials were both in magnetically ordered, and superparamagnetic states, and they formed a grid-like mesoporous structure. The influence of magnetic dipole interparticle interaction on the parameters of Mossbauer spectra was observed. A phenomenological model of the differences between nanodispersed γ-Fe2O3 magnetic microstructures obtained after annealing at different temperatures was presented.
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Biasiori-Poulanges, L., i K. Schmidmayer. "A phenomenological analysis of droplet shock-induced cavitation using a multiphase modeling approach". Physics of Fluids 35, nr 1 (styczeń 2023): 013312. http://dx.doi.org/10.1063/5.0127105.
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Investigations of shock-induced cavitation within a droplet are highly challenged by the multiphase nature of the mechanisms involved. Within the context of heterogeneous nucleation, we introduce a thermodynamically well-posed multiphase numerical model accounting for phase compression and expansion, which relies on a finite pressure-relaxation rate formulation. We simulate (i) the spherical collapse of a bubble in a free field, (ii) the interaction of a cylindrical water droplet with a planar shock wave, and (iii) the high-speed impact of a gelatin droplet onto a solid surface. The determination of the finite pressure-relaxation rate is done by comparing the numerical results with the Keller–Miksis model, and the corresponding experiments of Sembian et al. and Field et al., respectively. For the latter two, the pressure-relaxation rate is found to be [Formula: see text] and [Formula: see text], respectively. Upon the validation of the determined pressure-relaxation rate, we run parametric simulations to elucidate the critical Mach number from which cavitation is likely to occur. Complementing simulations with a geometrical acoustic model, we provide a phenomenological description of the shock-induced cavitation within a droplet, as well as a discussion on the bubble-cloud growth effect on the droplet flow field. The usual prediction of the bubble cloud center, given in the literature, is eventually modified to account for the expansion wave magnitude.
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Liao, Xin, Jianrun Zhang i Xiyan Xu. "Analytical Model of Bolted Joint Structure and Its Nonlinear Dynamic Characteristics in Transient Excitation". Shock and Vibration 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/8387497.
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The dynamic response of crucial components often depends upon the dynamic behavior of bolted connections. As is usually the case, the accurate modeling of structures with many mechanical joints remains a challenge work. The nonlinear behavior included in assembled structures strongly depends on the interface properties. In this paper, an analytical model of the simple bolted joint beam in tangential direction is first proposed for transient excitation, based on phenomenological model. The fourth-order Runge-Kutta method is employed to calculate the transient response, where the dynamic response of the nonlinear stiffness on system is also investigated. The simulation results show that natural frequency has a certain dependence on cubic stiffness term and cubic stiffness is more suitable for modeling of nonlinear system of a wider frequency range. Thereby, a series Iwan model containing cubic stiffness term is established to describe nonlinear behaviors of bolted joint beams in shear vibration. The amplitude-frequency curves show that the influence of interaction between nonlinear stiffness and damping mechanism on dynamic response characteristics is more obvious. Finally, a new type of nonlinear model is applied into finite element analysis. The results of proposed transient excitation experiment are discussed qualitatively, indicating that nonlinear effects observed agree with the numerical simulation results.
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Al-Ghamdi, A. H., Awad A. Ibraheem i M. El-Azab Farid. "Comparative study of alpha + nucleus elastic scattering using different models". International Journal of Modern Physics E 24, nr 01 (styczeń 2015): 1550003. http://dx.doi.org/10.1142/s0218301315500032.
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The alpha (α) elastic scattering from different targets potential over the energy range 10–240 MeV has been analyzed in the framework of the single-folding (SF) optical model. Four targets are considered, namely, 24 Mg , 28 Si , 32 S and 40 Ca . The SF calculations for the real central part of the nuclear optical potential are performed by folding an effective α–α interaction with the α-cluster distribution density in the target nucleus. The imaginary part of the optical potential is expressed in the phenomenological Woods–Saxon (WS) form. The calculated angular distributions of the elastic scattering differential cross-section using the derived semimicroscopic potentials successfully reproduce 36 sets of data all over the measured angular ranges. The obtained results confirm the validity of the α-cluster structure of the considered nuclei. For the sake of comparison, the same sets of data are reanalyzed using microscopic double-folded optical potentials based upon the density-dependent Jeukenne–Lejeune–Mahaux (JLM) effective nucleon–nucleon interaction.
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BRAUN, OLEG M., IRINA I. ZELENSKAYA i YURI S. KIVSHAR. "DIFFUSION IN THE FRENKEL–KONTOROVA MODEL WITH ANHARMONIC INTERATOMIC INTERACTIONS". International Journal of Modern Physics B 08, nr 17 (30.07.1994): 2353–89. http://dx.doi.org/10.1142/s0217979294000968.
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Low-temperature diffusion and transport properties of the generalized Frenkel–Kontorova model are investigated analytically in the framework of a phenomenological approach which treats a system of strongly interacting atoms as a system of weaklyinteracting quasiparticles (kinks). The model takes into account realistic (anharmonic) interaction of particles subjected into a periodic substrate potential, and such a generalization leads to a series of novel effects which we expect are related to the experimentally-observed phenomena in several quasi-one-dimensional systems. Analysing the concentration dependences in the framework of the kink phenomenology, we use the renormalization procedure when the atomic structure with a complex unit cell is treated as (more simple) periodic structure of kinks. Using phenomenology of the ideal kink gas, the low-temperature states of the chain are described as those consisting of "residual" kinks supplemented by thermally-excited kinks. This approach allows us to describe the ground states of the chain as a hierarchy of "melted" kink lattices. Dynamical and diffusion properties of the system are then described in terms of the kink dynamics and kink diffusion. The motion equation for a single kink is reduced to a Langevin-type equation which is investigated with the help of the Kramers theory. Susceptibility, conductivity, self-diffusion and chemical diffusion coefficients of the chain are calculated as functions of the kink diffusion coefficient. In this way, we qualitatively analyze, for the first time to our knowledge, dependence of the different diffusion coefficients on the concentration of atoms in the chain. The results are applied to describe peculiarities in conductivity and diffusion coefficients of quasi-one-dimensional systems, in particular, superionic conductors and anisotropic layers of atoms adsorbed on crystal surfaces which were earlier investigated experimentally.
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Shen, Chuanliang, Wei Su, Guochao Sun, Binyu Zhou, Tairong Sun i Yi Liu. "Preliminary study of vibration characteristics of intelligent beam with the influence of SMA's restoring force". MATEC Web of Conferences 238 (2018): 05007. http://dx.doi.org/10.1051/matecconf/201823805007.
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In order to solve the problem of noise and comfort caused by vibration during automobile driving, this paper proposes to use shape memory alloy wire as driving element and simplified beam structure to form intelligent beam composite structure, and use the restoring force generated by shape memory alloy wire to realize vibration control of the structure. several macroscopic phenomenological constitutive models of NiTi alloy were summarized and analyzed. On the basis of the Liang-Rogers one-dimensional constitutive model, Simulating the response force changing process of the SMA wire by useing MATLAB. According to the oretical analysis, we can obtain the system stiffness matrix and mass matrix, establish the dynamic model of smart beam composite structure, and analyze the interaction between shape memory composite wire prestress and natural frequency. The numerical simulation method is used to establish the simulation model and study the influence of the size and position parameters of the intelligent beam structure and the restoring force on its vibration characteristics. The results show that the natural frequency of the beam decreases and the natural frequency of the SMA wire increases with the increasing restoring force of SMA wire. As the distance from the SMA wire to the neutral axis increases, the natural frequency of the system increases, revealing the mechanism of vibration control of the shape memory alloy smart beam composite structure.
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Coon, Sidney A., i Michael K. G. Kruse. "Properties of infrared extrapolations in a harmonic oscillator basis". International Journal of Modern Physics E 25, nr 05 (maj 2016): 1641011. http://dx.doi.org/10.1142/s0218301316410111.
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The success and utility of effective field theory (EFT) in explaining the structure and reactions of few-nucleon systems has prompted the initiation of EFT-inspired extrapolations to larger model spaces in ab initio methods such as the no-core shell model (NCSM). In this contribution, we review and continue our studies of infrared (ir) and ultraviolet (uv) regulators of NCSM calculations in which the input is phenomenological [Formula: see text] and [Formula: see text] interactions fitted to data. We extend our previous findings that an extrapolation in the ir cutoff with the uv cutoff above the intrinsic uv scale of the interaction is quite successful, not only for the eigenstates of the Hamiltonian but also for expectation values of operators, such as [Formula: see text], considered long range. The latter results are obtained with Hamiltonians transformed by the similarity renormalization group (SRG) evolution. On the other hand, a possible extrapolation of ground state energies in the uv cutoff when the ir cutoff is below the intrinsic ir scale is not robust and does not agree with the ir extrapolation of the same data or with independent calculations using other methods.
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Boychuk, V., V. Kotsyubynsky, K. Bandura, M. Hodlevska, B. Dzundza i O. Khatsevych. "The Mechanisms of Nickel-Iron Spinel Phase Nucleation in Aquous Solutions: Crystal Quasichemical Approach". Фізика і хімія твердого тіла 20, nr 2 (10.07.2019): 156–64. http://dx.doi.org/10.15330/pcss.20.2.156-164.
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The phenomenological model of nikel-iron spinel nucleation with spinel structure based on the partial charge theory and analysis of hydrolysis and polycondensation processes at the interaction of Fe3+-, Fe2+- and Ni2+- hydroxocomplexes at different pH values of reaction medium was proposed. UV-vis optical spectroscopy was used for verification of the obtained results about the regularities of hydroxocomplexes formation. Crystal quasichemistry approach was applied for nucleation of nikel-iron spinel under the conditions of predomination of different defect types in NixFe3-xO4-δ (δ is oxygen non-stoichiometry) spinel lattice. The analysis of changes in electrical conductivity and lattice parameter of defect nickel-iron spinel as a function of Ni2+ atomic concentration was done for different values of d parameter.
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RODRIGUES, H., S. B. DUARTE i J. C. T. OLIVEIRA. "EXO 0748-676 AS A QUARK STAR". International Journal of Modern Physics D 19, nr 08n10 (sierpień 2010): 1447–54. http://dx.doi.org/10.1142/s0218271810017500.
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This work shows results for the EXO 0748-676 neutron star structure obtained with the use of a phenomenological quark matter description by taking into account a quark interaction, and observing the asymptotic freedom and the confinement characteristics of the fundamental theory. An appropriated choice of model parameters permit to reach the stability of compact dense stellar objects compatible with the observational data to the neutron star EXO 0748-676. It is assumed a color-flavor locked (CFL) superconducting phase to the ground state of the quark–gluon plasma formed in the object interior. We also discuss the surface properties of these objects, introducing a crust composed by a lattice of neutron-rich nucleus close to the neutron drip line, imbedded in an electron gas.
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Fang, Fei, i Spencer P. Lake. "Modelling approaches for evaluating multiscale tendon mechanics". Interface Focus 6, nr 1 (6.02.2016): 20150044. http://dx.doi.org/10.1098/rsfs.2015.0044.
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Tendon exhibits anisotropic, inhomogeneous and viscoelastic mechanical properties that are determined by its complicated hierarchical structure and varying amounts/organization of different tissue constituents. Although extensive research has been conducted to use modelling approaches to interpret tendon structure–function relationships in combination with experimental data, many issues remain unclear (i.e. the role of minor components such as decorin, aggrecan and elastin), and the integration of mechanical analysis across different length scales has not been well applied to explore stress or strain transfer from macro- to microscale. This review outlines mathematical and computational models that have been used to understand tendon mechanics at different scales of the hierarchical organization. Model representations at the molecular, fibril and tissue levels are discussed, including formulations that follow phenomenological and microstructural approaches (which include evaluations of crimp, helical structure and the interaction between collagen fibrils and proteoglycans). Multiscale modelling approaches incorporating tendon features are suggested to be an advantageous methodology to understand further the physiological mechanical response of tendon and corresponding adaptation of properties owing to unique in vivo loading environments.
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Fenske, Jochen, Dieter Lott, Elena V. Tartakovskaya, Hwachol Lee, Patrick R. LeClair, Gary J. Mankey, Wolfgang Schmidt, Karin Schmalzl, Frank Klose i Andreas Schreyer. "Magnetic order and phase transitions in Fe50Pt50–xRhx". Journal of Applied Crystallography 48, nr 4 (18.07.2015): 1142–58. http://dx.doi.org/10.1107/s1600576715011462.
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Polarized and unpolarized neutron diffraction techniques have been applied to study the temperature-dependent magnetic and structural properties of four 200 nm-thick Fe50Pt50−xRhxfilms withx= 5,x= 10,x= 17.5 andx= 25. Similar to the bulk system, an antiferromagnetic to ferromagnetic transition can be found in the films with decreasing Rh concentration. The application of structure factor calculations enables one to determine the microscopic magnetic configuration of the different films as a function of temperature and Rh concentration. The developed models indicate a magnetic transition from a dominant antiferromagnetic order in the out-of-plane direction to a dominant ferromagnetic order in the in-plane direction with decreasing Rh concentration. The different magnetic configurations can theoretically be described by a phenomenological model which includes a two-ion and a one-ion interaction Hamiltonian term with different temperature dependencies of the anisotropy constants.
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Shirokov, Vladimir B., i Mikhail V. Talanov. "Phase transitions in Bi4Ti3O12". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, nr 6 (7.11.2019): 978–86. http://dx.doi.org/10.1107/s2052520619011843.
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Bi4Ti3O12 is a representative of the Aurivillius family of layered perovskites. These are high-temperature ferroelectric materials with prospects for applications in random-access memory and are characterized by an extremely confused interaction of their structural degrees of freedom. Using group-theoretical methods, structural distortions in the Bi4Ti3O12 high-symmetry phase, caused by rotations of rigid octahedra and their displacements as a single unit, have been investigated, taking into account the connections between them. Within the Landau theory, a stable thermodynamic model of phase transitions with three order parameters has been constructed. It is shown that, according to the phenomenological phase diagram, the transition between the high-temperature tetragonal phase and the low-temperature ferroelectric can occur both directly and through intermediate states, including those observed experimentally. The role of improper ordered parameters and possible domain configurations in the structure formation of the low-temperature ferroelectric phase are discussed.
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OKOROKOV, V. A. "EVENT SHAPES FOR HADRONIC FINAL STATE: EXPERIMENTAL REVIEW". International Journal of Modern Physics A 27, nr 08 (30.03.2012): 1250037. http://dx.doi.org/10.1142/s0217751x12500376.
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The analysis is presented for the first moments of collective observable distributions in two-jet events for various interaction types and for wide initial energy range. These observables include sphericity, thrust, components of transverse particle momentum, alignment and planarity. Database of experimental results created in the framework of the paper includes data for all interactions. Energy dependencies of average values for collective observables except components of transverse momentum show universal behavior for various interactions. Particle transverse momentum as well as its components increase faster for e+e- interaction with growth of [Formula: see text], than that for other interactions. Empirical analytical functions are suggested for description of energy dependence for all collective observables under study with exception of infrared-stable thrust variable. Energy dependence for average thrust is compared with QCD predictions including perturbative part and analytical phenomenological corrections which account for nonperturbative effects. Dispersive model and single dressed gluon approximation are considered for description of energy dependence of first moment of thrust distribution and estimation of strong coupling constant for various interactions as well as for joint sample. The dispersive model allow to describe average thrust versus initial energy in wide range of [Formula: see text] down to strongly nonperturbative domain [Formula: see text] at qualitative level at least. Study of event shape observables allows to obtain estimations of αS(MZ) which are in reasonable agreement both with world average value and with results extracted in the framework of other methods. Using suggested analytical fitted functions some estimations of values of collective parameters under study have been obtained for present and future facilities. In TeV energy domain average values of collective observables either depend on [Formula: see text] weakly or do not depend on initial energy at all within errors. Thus, the TeV scale can be considered as an estimation of the low boundary of asymptotic region for traditional collective parameters. Usually, multiplicity dependence of collective observables under consideration agree with power function in energy domain [Formula: see text] at qualitative level at least. Behavior of sphericity versus multiplicity and comparison of experimental results with model calculations allow to suggest that the universal estimation of the low energy boundary for experimental appearance of event jet structure in multiparticle production processes is [Formula: see text].
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Shrinivas, Ajay B., i Gary R. Hunt. "Confined turbulent entrainment across density interfaces". Journal of Fluid Mechanics 779 (14.08.2015): 116–43. http://dx.doi.org/10.1017/jfm.2015.366.
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In pursuit of a universal law for the rate of entrainment across a density interface driven by the impingement of a localised turbulent flow, the role of the confinement, wherein the environment is within the confines of a box, has to date been overlooked. Seeking to unravel the effects of confinement, we develop a phenomenological model describing the quasi-steady rate at which buoyant fluid is turbulently entrained across a density interface separating two uniform layers within the confines of a box. The upper layer is maintained by a turbulent plume, and the localised impingement of a turbulent fountain with the interface drives entrainment of fluid from the upper layer into the lower layer. The plume and fountain rise from sources at the base of the box and are non-interacting. Guided by previous observations, our model characterises the dynamics of fountain–interface interaction and the steady secondary flow in the environment that is induced by the perpetual cycle of vertical excursions of the interface. We reveal that the dimensionless entrainment flux across the interface $E_{i}$ is governed not only by an interfacial Froude number $\mathit{Fr}_{i}$ but also by a ‘confinement’ parameter ${\it\lambda}_{i}$, which characterises the length scale of interfacial turbulence relative to the depth of the upper layer. By deducing the range of ${\it\lambda}_{i}$ that may be regarded as ‘small’ and ‘large’, we shed new light on the effects of confinement on interfacial entrainment. We establish that for small ${\it\lambda}_{i}$, a weak secondary flow has little influence on $E_{i}$, which follows a quadratic power law $E_{i}\propto \mathit{Fr}_{i}^{2}$. For large ${\it\lambda}_{i}$, a strong secondary flow significantly influences $E_{i}$, which then follows a cubic power law $E_{i}\propto \mathit{Fr}_{i}^{3}$. Drawing on these results, and showing that for previous experimental studies ${\it\lambda}_{i}$ exhibits wide variation, we highlight underlying physical reasons for the significant scatter in the existing measurements of the rate of interfacial entrainment. Finally, we explore the implications of our results for guiding appropriate choices of box geometry for experimentally and numerically examining interfacial entrainment.