| 1. |
- Bellomo, Nicola, 1943, et al.
(författare)
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The generalized-kinetics-based equilibrium distribution function for composite particles
- 2003
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Ingår i: Comptes Rendus - Mecanique. - : Elsevier Science B.V., Amsterdam.. - 1631-0721 .- 1873-7234. ; 331:7, s. 461-467
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Tidskriftsartikel (refereegranskat)abstract
- This work is devoted to the equilibrium distribution function for a fluid of mutually non-interacting identical composite point particles in three-dimensional physical space. The distribution function is derived within the generalized-kinetics (GK) vision from the proposed probabilistic model based on quantum-mechanical bosons and fermions. The first GK advantage is that the derivation does not involve any assumption on the interpolation between bosons and fermions whereas the resulting function provides this interpolation. The second GK advantage is that composons, the particles described with the GK-based distribution function, are considerably less schematic and more consistent physically than quons. Composons correspond to a specific case of Isakov's general q-commutation relation involving an infinite number of the q-coefficients. Connection of the composon concept to previous results in the literature is pointed out. A few directions for future research on the topic are formulated. The results of the work can be used in the composite-particle fluid problems where the Maxwell–Boltzmann description is not valid, for instance, in dense populations of not too massive point-like particles of a complex, composite nature at not too high temperatures. FRENCH: Ce travail s'intéresse à la fonction de distribution d'équilibre pour un fluide mutuellement non agissant, composé de particules points dans un espace de dimension trois. La fonction de distribution provient, d'un point de vue de CG, d'un modèle probabiliste issu de la mécanique quantique des fermions et des bosons. Le premier avantage de CG est que la dérivation ne nécessite aucune hypothèse sur l'interpolation entre les bosons et les fermions alors que la fonction résultante fournit cette interpolation. Le second est que les composons, les particules décrites par ce procédé sont considérablement moins schématiques et plus consistantes, physiquement, que les quons. Les composons correspondent à un cas particulier de la relation générale de q-commutation d'Isakov, pour un nombre infini de q-coefficients. Les résultats antérieurs liés au concept de composon sont signalés et quelques directions de recherches futures sont proposées. Les résultats de ce travail peuvent servir pour l'étude de fluides composés, où la description Maxwell–Boltzmann n'est pas valable, par exemple, pour une dense population de particules, pas trop lourdes et a des températures pas trop élevées, et d'une comoposition de nature complexe.
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| 2. |
- Berbyuk, Viktor, 1953, et al.
(författare)
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Ice detection for smart de-icing of wind turbines
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Icing on a wind turbine rotor blade is a problem in the operation of wind turbines in cold climates. Ice detection is a critical process to get a workable cost-effective wind turbine de-icing system. The paper presents the theoretical models, methods, algorithms, principles, and a demonstrator that are the basis for developing a new technique for detecting icing on rotor blades of a wind turbine based on acoustic wave propagation in composite structures. Two methods have been proposed: guided acoustic wave propagation and bulk acoustic wave propagation in composite structures. Analysis of computer simulations and the results of experimental study obtained by using the developed demonstrator in cold climate lab has shown that the integration of the guided acoustic wave propagation and the bulk acoustic wave propagation methods provides an efficient scientific approach to be used for the design of new ice detection system for wind turbines in cold climate regions. In particular, the guided acoustic wave propagation method makes it possible to detect ice and icing area location on the rotor blades. Several criteria (Icing Index, Frequency Factor Index, others) have been proposed for ice detection of composite structures. Bulk acoustic wave propagation method makes it possible to identify the time-varying spatially heterogeneous “landscapes” over the blade surface for each of the following eight ice parameters: thickness, the volumetric bulk density, bulk and shear moduli, stress relaxation time, porosity, and volume and shear viscosities. These data are necessary for smart, energy-efficient de-icing systems. The identification algorithm is computationally efficient and can be implemented in the real-time mode. A LIDAR (Light Detection And Ranging) for the detection of early ice growth on the wind turbine blades has also designed, tested and evaluated in this project. LIDAR uses laser pulses that emit at two different wavelengths and is capable of distinguishing between a thin layer of ice and water covering the turbine blades. The results of the tests that have been carried out in the project are undeniable. LIDAR detects early ice growth by measuring the difference in reflectivity of a surface by using two different laser wavelengths. The limitation of LIDAR is that it cannot be used to determine the amount of ice on the sheet, only if there is ice or not. The obtained results can be used to develop smart de-icing systems for wind turbines operating in cold climates, and can lead to new future products that are sought after by wind power industry. Since the efficient ice detection systems can increase wind turbine profitability, the results contribute to an increased ability to establish multiple wind turbines in cold regions.
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| 3. |
- Carlsson, Tobias, 1975, et al.
(författare)
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Irreducible memory function and slow dynamics in disordered systems.
- 2007
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Ingår i: Phys. Rev. E. - 1539-3755. ; 75:031109, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- We show how the irreducible memory function can be obtained in a rather straightforward way, and that it can be expressed in terms of two contributions representing two parallel decay channels. This representation should be useful for treating systems with a slow time dependence and where eventually some internal degrees of freedom enters in the relaxation process, and cuts off an underlying ideal ergodic to nonergodic transition. We also show how the irreducible memory function under certain mild conditions defines a regenerative stochastic process, or a two level stochastic system. This leads to a picture with dynamical heterogeneities, where the statistical properties asymptotically are ruled by limit processes. This can explain the universal behavior observed in many glass-forming systems.
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| 4. |
- Koptyug, Andrey, 1956-, et al.
(författare)
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Dynamic modeling of tumor development
- 2011
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Ingår i: Science First Hand. - Siberian Branch of RAS : Publishing House INFOLIO. - 1810-3960. ; 6:42, s. 44-51
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Koptyug, Andrey, 1956-, et al.
(författare)
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Towards personalised medicine : Problems of the drug therapy of cancer
- 2011
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Ingår i: Science First Hand. - Novosibirsk, Russia : Infolio Press. - 1810-8520. ; 38:2, s. 91-97
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- During the fall of 2010 headlines like "Aspirin a day helps to keep cancer at bay, say scientists" hit the world media. It appeared that all of these were inspired by a single publication in The Lancet. This research article shows that regular administration of small doses of aspirin reduces the mortality from certain types of cancer (like the bowel, lung and prostate cancers). In the present paper, we consider this phenomenon as well. The widespread reaction of the public and media to these headlines has persuaded us to write this paper without delay.
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| 6. |
- Mamontov, Eugen, 1955, et al.
(författare)
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A Scalar Acoustic Equation for Gases, Liquids, and Solids, Including Viscoelastic Media
- 2014
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Ingår i: Journal of Applied Mathematics and Physics. - : Scientific Research Publishing, Inc.. - 2327-4379 .- 2327-4352. ; 2, s. 960-970
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Tidskriftsartikel (refereegranskat)abstract
- The work deals with a mathematical model for real-time acoustic monitoring of material parameters of media in multi-state viscoelastic engineering systems continuously operating in irregular external environments (e.g., wind turbines in cold climate areas, aircrafts, etc.). This monitoring is a high-reliability time-critical task. The work consistently derives a scalar wave PDE of the Stokestype for the non-equilibrium part (NEP) of the average normal stress in a medium. The explicit expression for the NEP of the corresponding pressure and the solution-adequateness condition are also obtained. The derived Stokes-type wave equation includes the stress relaxation time and is applicable to gases, liquids, and solids.
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| 7. |
- Mamontov, Eugen, 1955
(författare)
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A specification of the Maxwell–Rayleigh–Heisenberg approach to modelling fluids for bioelectronic applications
- 2005
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Ingår i: Mathl Comput. Modelling. - : Elsevier BV. - 0895-7177. ; 42:3-4, s. 441-470
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Tidskriftsartikel (refereegranskat)abstract
- The key question which any version of random fluid mechanics has to resolve is how to provide continuous probability distributions for the fluid particles. Each specific way is determined by one or another set of assumptions. Statistical mechanics proceeds on the thermodynamic-limit assumption supposing that the domain occupied by the fluid is “macroscopically big” and the number of the particles in it is “statistically large”. This picture cannot be the case in mesoscopic systems. The latter are common in many modern applications including bioelectronics. The present work develops a nonstatistical way to provide the above continuous distributions. It follows the vision formed by certain results of Heisenberg, Rayleigh, and Maxwell and specifies it by means of extending nonlinear nonequilibrium stochastic hydrodynamics (NNSHD) introduced by the authors earlier. The work concentrates on the following two generalizations: first, allowing for nonzero volumes of the particles, the feature typical in the biological parts of bioelectronic problems, and, second, accounting the general kinetic-energy/momentum dependences, including the relativistic ones, which are usually necessary in the electronic parts of bioelectronic problems. The simplest case of the first generalization is exemplified with an evaluation of the electrochemical potentials and pressures of red blood cells in human blood in a recently published paper of the authors. The second generalization is illustrated in Section 10 of the present work with the relativistic distribution functions which take into account the general spin picture of composite particles by means of the model of composons, the flexible combination of bosons and fermions based on the generalized-kinetics (GK) methods. The above generalization is intended to be a framework rather than theory that inherently includes the capabilities in coupling to other fluid-modelling treatments like common hydrodynamics or stochastic kinetic equations. The issues on further extensions in line with GK and on the coupling to the latter are emphasized. A few directions for future research are discussed as well.
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| 8. |
- Mamontov, Eugen, 1955, et al.
(författare)
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An analytical-numerical method for fast evaluation of probability densities for transient solutions of nonlinear Itô’s stochastic differential equations
- 2009
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Ingår i: International Journal of Engineering Science. - : Elsevier BV. - 0020-7225. ; 47:1, s. 116-130
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Tidskriftsartikel (refereegranskat)abstract
- Probability densities for solutions of nonlinear Itô’s stochastic differential equations are described by the corresponding Kolmogorov-forward/Fokker-Planck equations. The densities provide the most complete information on the related probability distributions. This is an advantage crucial in many applications such as modelling floating structures under the stochastic load due to wind or sea waves. Practical methods for numerical solution of the probability-density equations are combined, analytical-numerical techniques. The present work develops a new analytical-numerical approach, the successive-transition (ST) method, which is a version of the path-integration (PI) method. The ST technique is based on an analytical approximation for the transition-probability density. It enables the PI approach to explicitly allow for the damping matrix in the approximation. This is achieved by extending another method, introduced earlier for bistable nonlinear reaction-diffusion equations, to the probability-density equations. The ST method also includes a control for the size of the time step. The overall accuracy of the ST method can be tested on various nonlinear examples. One such example is proposed. It is one-dimensional nonlinear Itô’s equation describing the velocity of a ship maneuvering along a straight line under the action of the stochastic drag due to wind or sea waves. Another problem in marine engineering, the rolling of a ship up to its possible capsizing is also discussed in connection with the complicated damping-matrix picture. The work suggests a few directions for future research.
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| 9. |
- Mamontov, Eugen, 1955, et al.
(författare)
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Associations and dissociations with time-dependent reaction coefficients in finite polymer mixtures: The model and analytical-numerical method for solution by successive approximations
- 2017
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Ingår i: Applied Mathematical Modelling. - : Elsevier BV. - 0307-904X. ; 51, s. 109-128
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Tidskriftsartikel (refereegranskat)abstract
- The work deals with the association and dissociation reactions with time-dependent coef- ficients in finite mixtures of polymers dispersed in fluid media with solid components. The polymers are regarded to be formed by identical units, polymer-forming units (PFUs) and, thus, present homopolymers. The model takes into account the porosity of the dispersion- medium/polymer-mixture system. The work derives the model for the reactions in the fi- nite mixtures. The model presents a non-autonomous quadratic finite ODE system in a time-independent hyperplane and is based on the conservation law for the total num- ber of PFUs. A variety of engineering applications of the derived finite-mixture model are discussed. The simplest case of the finite mixtures, i.e., the monomer-dimer mix- tures with time-independent reaction coefficients is completely analyzed. An analytical- numerical (AN) method of the successive-approximations (SA) type is proposed for solv- ing the derived model. The AN/SA method includes explicit analytical expressions for each of the approximations in terms of the preceding approximation. The method is exact in the dissociation-only case. The approximations are expected to converge if the association- reaction coefficients are not too large and the zeroth approximations are not very far from the solution. The AN/SA method comprises two sequences of the approximations. If the first one converges uniformly in the entire time axis, then the limit function is a steady- state (or “dynamic equilibrium”) solution of the non-autonomous quadratic ODE system. The second sequence presumes that the first sequence is convergent in the above men- tioned sense. The second sequence is intended for calculation of the solutions of initial- value problems for the above ODE system in a semi-infinite time interval. The main differ- ences from common computational methods are formulated. The AN/SA method is quan- titatively illustrated with a few examples of the settings in the aforementioned case of monomer-dimer mixtures, also in comparison with the explicit Euler method. The form of the AN/SA method allows especially efficient implementation on multi-processor/multicore personal computers with graphic processing units even if the dimension of the state space is large. The developed model and method form a constructive framework for analysis or design of polymer mixtures dispersed in fluid-solid media. An application to prospective manufacturing of spatially heterogeneous polymer products is noted. A few directions for future research are proposed as well.
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| 10. |
- Mamontov, Eugen, 1955, et al.
(författare)
-
Asymptotic trajectory matching in self-navigation of autonomous manless interceptors: Nonsearch method and a formulation of the functional optimization of the stability of random systems
- 2006
-
Ingår i: Proc. 5th MATHMOD Vienna Conf., 8-10 February, 2006 (Vienna Univ. of Technol., Vienna, Austria). - 3901608303 ; 2
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Konferensbidrag (refereegranskat)abstract
- In the field of self-navigation autonomous manless robots there is a noticeable interest to the robot-based target-interception problem. The interceptor trajectory is usually determined by search-based optimization algorithms. In contrast to this, the present work treats the interception as asymptotic trajectory matching and introduces a nonsearch method for the interceptor trajectory. This method is substantially simpler than the well-known proportional navigation and requires very limited computing resources. The latter feature makes the proposed method especially suitable to the interceptors based on embedded onboard computers and civil applications. An example of the latter discussed in the work is the protection of the infrastructure components against intended or unintended attacks. In a general case when parameters of the interceptor are random, the new method leads to a formulation of a new problem in stochastic optimization, namely the functional optimization of (the so-called targetal) stability of the interceptor trajectory. Certain aspects of a practical implementation of the new systems are analyzed. The work proposes the basic physical principle and schemes for innovative sensors which can make the interceptors truly autonomous, in particular, fully GPS-free. A list of the fundamental and applied topics for future research is also suggested.
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