The jump and bifurcation of Duffing oscillator with hardening spring subject to narrow-band random excitation are systematically and comprehensively examined. It is shown that, in a certain domain of the space of the ...The jump and bifurcation of Duffing oscillator with hardening spring subject to narrow-band random excitation are systematically and comprehensively examined. It is shown that, in a certain domain of the space of the oscillator and excitation parameters, there are two types of more probable motions in the stationary response of the Duffing oscillator and jumps may occur. The jump is a transition of the response from one more probable motion to another or vise versa. Outside the domain the stationary response is either nearly Gaussian or like a diffused limit cycle. As the parameters change across the boundary of the domain the qualitative behavior of the stationary response changes and it is a special kind of bifurcation. It is also shown that, for a set of specified parameters, the statistics are unique and they are independent of initial condition. It is pointed out that some previous results and interpretations on this problem are incorrect.展开更多
The solid propellant gas generators having high gas capacity are widely used for fast pressurization of elastic shells of saving devices of different applications. A typical example of such devices are safety system o...The solid propellant gas generators having high gas capacity are widely used for fast pressurization of elastic shells of saving devices of different applications. A typical example of such devices are safety system of automobile (airbags). After collision of an automobile with an obstacle the combustion products of gas generator fill the shell during 60 – 100 milliseconds. However the temperature of combustion products even of “low-temperature” fuel compositions of gas generators appears not below 1500К and to reduce of its it is necessary to apply a various types of porous and filling granular filters. There are passive and active granular filters. The passive filter can cool of combustion products as a result of absorption of heat only. The active cooling is evaporation of the granule material and in this case takes a place more intensive cooling of combustion products in the filter. The numerical modeling of cooling process of high- temperature combustion products at their movement in bulk of granular filter of active cooling is investigated. As the material of granules was used the carbonate of magnesium. At its heating takes a place process of gasification and formation of a porous slag shell which sublimates at higher temperature. The physical model of such spherical granule can be presented as the central part consisting of the carbonate magnesium surrounded with the porous slag spherical shell through which gaseous products of gasification of the central part are filtered. The problem of distribution of heat in each granule is Stefan problem when at the given temperature on the surface of sphere there is the front of gasification moving inside of the bulk of material. It is assumed that combustion products are the perfect gas moving in the filter. The upwind difference scheme of the second order of the accuracy with TVD properties was applied to calculation of the movement of gas. The results of calculations at various values of key parameters of the active and passive filters allow to draw a conclusion about enough high efficiency of active cooling filters.展开更多
Nanoparticles(NPs)can be transported via the nose-to-brain(N_(2)B)route.Nonetheless,quantitative data on their spatiotemporal dynamics and regulation of the N_(2)B transport are largely lacking.We surveyed metal oxide...Nanoparticles(NPs)can be transported via the nose-to-brain(N_(2)B)route.Nonetheless,quantitative data on their spatiotemporal dynamics and regulation of the N_(2)B transport are largely lacking.We surveyed metal oxide/hydroxide NPs as magnetic resonance imaging(MRI)contrasts for quantitative N_(2)B tracking.NPs containing divalent transition metals were the only ones capable of N_(2)B transmission.Using T1-weighted(T1W)MRI,we showed that Mn_(3)O_(4)-NPs were readily engulfed by olfactory receptor neurons(ORNs)without disrupting olfactory sensing,we mapped their N_(2)B trajectory.Within neurons,the Mn_(3)O_(4)-NPs were localized to the cytosol,mitochondria,vesicles,moved at mixed fast and slow axonal transport velocities intraand extra-vesicularly through ORNs.The NPs’axonal transport is dependent on neuronal activity and microtubule integrity.The Mn_(3)O_(4)-NPs were trans-synaptically transmitted through at least four synapses across the olfactory tract.Trans-synaptic transmission of the NPs was dependent on N-type Ca^(2+)channels and NMDA receptors but blocked by GABAB receptor activation.A five-parameter Weibull signal increase/decrease model fitted to the T1W MRI data allowed for estimating kinetic parameters of Mn_(3)O_(4)-NP accumulation/elimination.Absolute and relative accumulation rates,but not elimination,correlated negatively with the number of synapses from ORNs,indicating a coupling of the NPs’N_(2)B transport with spontaneous neuronal activity.Accordingly,olfactory stimuli(2,5-dimethylpyrazine and acetophenone)significantly modulated and rerouted the Mn_(3)O_(4)-NP N_(2)B transport odor specifically.Finally,the NPs’trans-synaptic transmission was impaired by aging and the onset of Parkinson’s disease.These data suggest new approaches to diagnostics,functional neuroimaging,controlling N_(2)B drug delivery.展开更多
A ground-based laser system for space-debris cleaning will use powerful laser pulses that can self-focus while propagating through the atmosphere.We demonstrate that for the relevant laser parameters,this self-focusin...A ground-based laser system for space-debris cleaning will use powerful laser pulses that can self-focus while propagating through the atmosphere.We demonstrate that for the relevant laser parameters,this self-focusing can noticeably decrease the laser intensity on the target.We show that the detrimental effect can be,to a great extent,compensated for by applying the optimal initial beam defocusing.The effect of laser elevation on the system performance is discussed.展开更多
From analyses of observation data it is found that stratification is usually unstable in the moist adiabatic process when cumulus develops vigorously. This shows that water vapour is an important factor for the develo...From analyses of observation data it is found that stratification is usually unstable in the moist adiabatic process when cumulus develops vigorously. This shows that water vapour is an important factor for the development of cumulus. Therefore, it can be seen that the condensation of water vapour in cumulus is not only the result of develop-展开更多
In this paper we describe a numerical method to solve numerically the weakly dispersive fully nonlinear SERRE-GREEN-NAGHDI(SGN)celebrated model.Namely,our scheme is based on reliable finite volume methods,proven to be...In this paper we describe a numerical method to solve numerically the weakly dispersive fully nonlinear SERRE-GREEN-NAGHDI(SGN)celebrated model.Namely,our scheme is based on reliable finite volume methods,proven to be very efficient for the hyperbolic part of equations.The particularity of our study is that we develop an adaptive numerical model using moving grids.Moreover,we use a special form of the SGN equations where non-hydrostatic part of pressure is found by solving a linear elliptic equation.Moreover,this form of governing equations allows to determine the natural form of boundary conditions to obtain a well-posed(numerical)problem.展开更多
In this paperwe reviewthe history and current state-of-the-art in modelling of long nonlinear dispersive waves.For the sake of conciseness of this review we omit the unidirectional models and focus especially on some ...In this paperwe reviewthe history and current state-of-the-art in modelling of long nonlinear dispersive waves.For the sake of conciseness of this review we omit the unidirectional models and focus especially on some classical and improved BOUSSINESQ-type and SERRE-GREEN-NAGHDI equations.Finally,we propose also a unified modelling framework which incorporates several well-known and some less known dispersive wave models.The present manuscript is the first part of a series of two papers.The second part will be devoted to the numerical discretization of a practically important model on moving adaptive grids.展开更多
基金The project supported by National Natural Science Foundation of China
文摘The jump and bifurcation of Duffing oscillator with hardening spring subject to narrow-band random excitation are systematically and comprehensively examined. It is shown that, in a certain domain of the space of the oscillator and excitation parameters, there are two types of more probable motions in the stationary response of the Duffing oscillator and jumps may occur. The jump is a transition of the response from one more probable motion to another or vise versa. Outside the domain the stationary response is either nearly Gaussian or like a diffused limit cycle. As the parameters change across the boundary of the domain the qualitative behavior of the stationary response changes and it is a special kind of bifurcation. It is also shown that, for a set of specified parameters, the statistics are unique and they are independent of initial condition. It is pointed out that some previous results and interpretations on this problem are incorrect.
文摘The solid propellant gas generators having high gas capacity are widely used for fast pressurization of elastic shells of saving devices of different applications. A typical example of such devices are safety system of automobile (airbags). After collision of an automobile with an obstacle the combustion products of gas generator fill the shell during 60 – 100 milliseconds. However the temperature of combustion products even of “low-temperature” fuel compositions of gas generators appears not below 1500К and to reduce of its it is necessary to apply a various types of porous and filling granular filters. There are passive and active granular filters. The passive filter can cool of combustion products as a result of absorption of heat only. The active cooling is evaporation of the granule material and in this case takes a place more intensive cooling of combustion products in the filter. The numerical modeling of cooling process of high- temperature combustion products at their movement in bulk of granular filter of active cooling is investigated. As the material of granules was used the carbonate of magnesium. At its heating takes a place process of gasification and formation of a porous slag shell which sublimates at higher temperature. The physical model of such spherical granule can be presented as the central part consisting of the carbonate magnesium surrounded with the porous slag spherical shell through which gaseous products of gasification of the central part are filtered. The problem of distribution of heat in each granule is Stefan problem when at the given temperature on the surface of sphere there is the front of gasification moving inside of the bulk of material. It is assumed that combustion products are the perfect gas moving in the filter. The upwind difference scheme of the second order of the accuracy with TVD properties was applied to calculation of the movement of gas. The results of calculations at various values of key parameters of the active and passive filters allow to draw a conclusion about enough high efficiency of active cooling filters.
基金the Russian Foundation for Basic Research RFBR(No.20-16-00078)the Centers of Collective Use“National Center of Catalyst Research”of Boreskov Institute of Catalysis SB RAS and by the budget project(No.FWNR-2022-0023 and project FWNR-2022-0004)+1 种基金the equipment of the Center for Genetic Resources of Laboratory Animals at ICG SB RAS,supported by the Ministry of Education and Science of Russia(Unique identifier of the project RFMEFI62119X0023)TEM imaging was performed at the Microscopy Center of Biological Subjects ICG SB RAS(project#0259-2021-0011)。
文摘Nanoparticles(NPs)can be transported via the nose-to-brain(N_(2)B)route.Nonetheless,quantitative data on their spatiotemporal dynamics and regulation of the N_(2)B transport are largely lacking.We surveyed metal oxide/hydroxide NPs as magnetic resonance imaging(MRI)contrasts for quantitative N_(2)B tracking.NPs containing divalent transition metals were the only ones capable of N_(2)B transmission.Using T1-weighted(T1W)MRI,we showed that Mn_(3)O_(4)-NPs were readily engulfed by olfactory receptor neurons(ORNs)without disrupting olfactory sensing,we mapped their N_(2)B trajectory.Within neurons,the Mn_(3)O_(4)-NPs were localized to the cytosol,mitochondria,vesicles,moved at mixed fast and slow axonal transport velocities intraand extra-vesicularly through ORNs.The NPs’axonal transport is dependent on neuronal activity and microtubule integrity.The Mn_(3)O_(4)-NPs were trans-synaptically transmitted through at least four synapses across the olfactory tract.Trans-synaptic transmission of the NPs was dependent on N-type Ca^(2+)channels and NMDA receptors but blocked by GABAB receptor activation.A five-parameter Weibull signal increase/decrease model fitted to the T1W MRI data allowed for estimating kinetic parameters of Mn_(3)O_(4)-NP accumulation/elimination.Absolute and relative accumulation rates,but not elimination,correlated negatively with the number of synapses from ORNs,indicating a coupling of the NPs’N_(2)B transport with spontaneous neuronal activity.Accordingly,olfactory stimuli(2,5-dimethylpyrazine and acetophenone)significantly modulated and rerouted the Mn_(3)O_(4)-NP N_(2)B transport odor specifically.Finally,the NPs’trans-synaptic transmission was impaired by aging and the onset of Parkinson’s disease.These data suggest new approaches to diagnostics,functional neuroimaging,controlling N_(2)B drug delivery.
基金This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344The support of the ERC and the grant from the Ministry of Education and Science of the Russian Federation(agreement no.14.B25.31.0003)are acknowledged.
文摘A ground-based laser system for space-debris cleaning will use powerful laser pulses that can self-focus while propagating through the atmosphere.We demonstrate that for the relevant laser parameters,this self-focusing can noticeably decrease the laser intensity on the target.We show that the detrimental effect can be,to a great extent,compensated for by applying the optimal initial beam defocusing.The effect of laser elevation on the system performance is discussed.
文摘From analyses of observation data it is found that stratification is usually unstable in the moist adiabatic process when cumulus develops vigorously. This shows that water vapour is an important factor for the development of cumulus. Therefore, it can be seen that the condensation of water vapour in cumulus is not only the result of develop-
基金This research was supported by RSCF project No 14-17-00219.The authors would like to thank Prof.Emmanuel AUDUSSE(UniversitéParis 13,France)who brought our attention to the problem of boundary conditions for the SGN equations.
文摘In this paper we describe a numerical method to solve numerically the weakly dispersive fully nonlinear SERRE-GREEN-NAGHDI(SGN)celebrated model.Namely,our scheme is based on reliable finite volume methods,proven to be very efficient for the hyperbolic part of equations.The particularity of our study is that we develop an adaptive numerical model using moving grids.Moreover,we use a special form of the SGN equations where non-hydrostatic part of pressure is found by solving a linear elliptic equation.Moreover,this form of governing equations allows to determine the natural form of boundary conditions to obtain a well-posed(numerical)problem.
基金This research was supported by RSCF project No 14-17-00219.D.Mitsotakis was supported by the Marsden Fund administered by the Royal Society of New Zealand.
文摘In this paperwe reviewthe history and current state-of-the-art in modelling of long nonlinear dispersive waves.For the sake of conciseness of this review we omit the unidirectional models and focus especially on some classical and improved BOUSSINESQ-type and SERRE-GREEN-NAGHDI equations.Finally,we propose also a unified modelling framework which incorporates several well-known and some less known dispersive wave models.The present manuscript is the first part of a series of two papers.The second part will be devoted to the numerical discretization of a practically important model on moving adaptive grids.
