Articles de revista
http://hdl.handle.net/2117/1137
2017-02-20T06:34:56ZFrozen Jacobian iterative method for solving systems of nonlinear equations: application to nonlinear IVPs and BVPs
http://hdl.handle.net/2117/101173
Frozen Jacobian iterative method for solving systems of nonlinear equations: application to nonlinear IVPs and BVPs
Ullah, Malik Zaka; Ahmad, Fayyaz; Alshomrani, Ali Saleh; Alzahrani, A. K.; Alghamdi, Metib Said; Ahmad, Shamshad; Ahmad, Shahid
Frozen Jacobian iterative methods are of practical interest to solve the system of nonlinear equations. A
frozen Jacobian multi-step iterative method is presented. We divide the multi-step iterative method into two
parts namely base method and multi-step part. The convergence order of the constructed frozen Jacobian
iterative method is three, and we design the base method in a way that we can maximize the convergence
order in the multi-step part. In the multi-step part, we utilize a single evaluation of the function, solve four
systems of lower and upper triangular systems and a second frozen Jacobian. The attained convergence
order per multi-step is four. Hence, the general formula for the convergence order is 3 + 4(m - 2) for
m = 2 and m is the number of multi-steps. In a single instance of the iterative method, we employ only
single inversion of the Jacobian in the form of LU factors that makes the method computationally cheaper
because the LU factors are used to solve four system of lower and upper triangular systems repeatedly. The
claimed convergence order is verified by computing the computational order of convergence for a system of
nonlinear equations. The efficiency and validity of the proposed iterative method are narrated by solving
many nonlinear initial and boundary value problems.
2017-02-17T11:47:01ZUllah, Malik ZakaAhmad, FayyazAlshomrani, Ali SalehAlzahrani, A. K.Alghamdi, Metib SaidAhmad, ShamshadAhmad, ShahidFrozen Jacobian iterative methods are of practical interest to solve the system of nonlinear equations. A
frozen Jacobian multi-step iterative method is presented. We divide the multi-step iterative method into two
parts namely base method and multi-step part. The convergence order of the constructed frozen Jacobian
iterative method is three, and we design the base method in a way that we can maximize the convergence
order in the multi-step part. In the multi-step part, we utilize a single evaluation of the function, solve four
systems of lower and upper triangular systems and a second frozen Jacobian. The attained convergence
order per multi-step is four. Hence, the general formula for the convergence order is 3 + 4(m - 2) for
m = 2 and m is the number of multi-steps. In a single instance of the iterative method, we employ only
single inversion of the Jacobian in the form of LU factors that makes the method computationally cheaper
because the LU factors are used to solve four system of lower and upper triangular systems repeatedly. The
claimed convergence order is verified by computing the computational order of convergence for a system of
nonlinear equations. The efficiency and validity of the proposed iterative method are narrated by solving
many nonlinear initial and boundary value problems.Simultaneous detection of the nonlinear restoring and excitation of a forced nonlinear oscillation: an integral approach
http://hdl.handle.net/2117/101056
Simultaneous detection of the nonlinear restoring and excitation of a forced nonlinear oscillation: an integral approach
Ahmad, Fayyaz; Jang, Taek Soo; Park, Jinsoo; Sung, Hong Gun
We address in this article, how to calculate the restoring characteristic and the excitation of a nonlinear forced oscillating system. Under the assumption that the forced nonlinear oscillator has a periodic solution with period, we constructed a system of linear equations by introducing time-dependent multipliers. The periodicity assumption helps simplify the system of linear equations. The stability and uniqueness are also presented for the inverse problem. Numerical testing is conducted to show the effectiveness of our presented methodology.
2017-02-15T09:34:46ZAhmad, FayyazJang, Taek SooPark, JinsooSung, Hong GunWe address in this article, how to calculate the restoring characteristic and the excitation of a nonlinear forced oscillating system. Under the assumption that the forced nonlinear oscillator has a periodic solution with period, we constructed a system of linear equations by introducing time-dependent multipliers. The periodicity assumption helps simplify the system of linear equations. The stability and uniqueness are also presented for the inverse problem. Numerical testing is conducted to show the effectiveness of our presented methodology.M31N 2008-12a - The remarkable recurrent Nova in M31: Panchromatic observations of the 2015 eruption
http://hdl.handle.net/2117/100773
M31N 2008-12a - The remarkable recurrent Nova in M31: Panchromatic observations of the 2015 eruption
Darnley, M. J.; Henze, Martin; Bode, M. F.; Hachisu, I.; Hernanz Carbó, Margarita; Hornoch, Kamil; Hounsell, R.; Kato, M.; Ness, Jan-Uwe; Osborne, Julian; Page, Kim; Ribeiro, V. A.; Rodríguez-Gil, Pablo; Shafter, A. W.; Shara, M.; Steele, I. A.; Williams, S. C.; Figueira, Joana; José Pont, Jordi; Sala Cladellas, Glòria
2017-02-09T14:26:23ZDarnley, M. J.Henze, MartinBode, M. F.Hachisu, I.Hernanz Carbó, MargaritaHornoch, KamilHounsell, R.Kato, M.Ness, Jan-UweOsborne, JulianPage, KimRibeiro, V. A.Rodríguez-Gil, PabloShafter, A. W.Shara, M.Steele, I. A.Williams, S. C.Figueira, JoanaJosé Pont, JordiSala Cladellas, GlòriaThree–dimensional simulations of turbulent convective mixing in ONe and CO classical nova explosions
http://hdl.handle.net/2117/100535
Three–dimensional simulations of turbulent convective mixing in ONe and CO classical nova explosions
Casanova, J.; José Pont, Jordi; García-Berro Montilla, Enrique; Shore, Steven N.
2017-02-03T10:11:54ZCasanova, J.José Pont, JordiGarcía-Berro Montilla, EnriqueShore, Steven N.Coordinated analysis of two graphite grains from the CO3.0 LAP 031117 meteorite: First identification of a CO Nova graphite and a presolar iron sulfide subgrain
http://hdl.handle.net/2117/100533
Coordinated analysis of two graphite grains from the CO3.0 LAP 031117 meteorite: First identification of a CO Nova graphite and a presolar iron sulfide subgrain
Haenecour, P.; Floss, C.; José Pont, Jordi; Amari, S.; Lodders, K.; Jadhav, M.; Wang, A.; Gyngard, F.
Presolar grains constitute remnants of stars that existed before the formation of the solar system.
In addition to providing direct information on the materials from which the solar system formed, these grains provide ground-truth information for models of stellar evolution and nucleosynthesis.
Here we report the in-situ identification of two unique presolar graphite grains from the primitive meteorite LaPaz Icefield 031117. Based on these two graphite grains, we estimate a bulk presolar graphite abundance of 5-3+7 ppm in this meteorite. One of the grains (LAP-141) is characterized by an enrichment in 12C and depletions in 33,34S, and contains a small iron sulfide subgrain, representing the first unambiguous identification of presolar iron sulfide. The other grain (LAP-149) is extremely 13C-rich and 15N-poor, with one of the lowest 12C/13C ratios observed among presolar grains. Comparison of its isotopic compositions with new stellar
nucleosynthesis and dust condensation models indicates an origin in the ejecta of a low-mass CO nova. Grain LAP-149 is the first putative nova grain that quantitatively best matches nova model
predictions, providing the first strong evidence for graphite condensation in nova ejecta. Our discovery confirms that CO nova graphite and presolar iron sulfide contributed to the original building blocks of the solar system.
2017-02-03T09:58:18ZHaenecour, P.Floss, C.José Pont, JordiAmari, S.Lodders, K.Jadhav, M.Wang, A.Gyngard, F.Presolar grains constitute remnants of stars that existed before the formation of the solar system.
In addition to providing direct information on the materials from which the solar system formed, these grains provide ground-truth information for models of stellar evolution and nucleosynthesis.
Here we report the in-situ identification of two unique presolar graphite grains from the primitive meteorite LaPaz Icefield 031117. Based on these two graphite grains, we estimate a bulk presolar graphite abundance of 5-3+7 ppm in this meteorite. One of the grains (LAP-141) is characterized by an enrichment in 12C and depletions in 33,34S, and contains a small iron sulfide subgrain, representing the first unambiguous identification of presolar iron sulfide. The other grain (LAP-149) is extremely 13C-rich and 15N-poor, with one of the lowest 12C/13C ratios observed among presolar grains. Comparison of its isotopic compositions with new stellar
nucleosynthesis and dust condensation models indicates an origin in the ejecta of a low-mass CO nova. Grain LAP-149 is the first putative nova grain that quantitatively best matches nova model
predictions, providing the first strong evidence for graphite condensation in nova ejecta. Our discovery confirms that CO nova graphite and presolar iron sulfide contributed to the original building blocks of the solar system.Constructing frozen Jacobian iterative methods for solving systems of nonlinear equations, associated with ODEs and PDEs using the homotopy
http://hdl.handle.net/2117/100357
Constructing frozen Jacobian iterative methods for solving systems of nonlinear equations, associated with ODEs and PDEs using the homotopy
Qasim, Uswah; Ali, Zulifgar; Ahmad, Fayyaz; Serra Capizzano, Stefano; Ullah, Malik Zaka; Asma, Mir
A homotopy method is presented for the construction of frozen Jacobian iterative methods. The frozen Jacobian iterative methods are attractive because the inversion of the Jacobian is performed in terms of LUfactorization only once, for a single instance of the iterative method. We embedded parameters in the iterative methods with the help of the homotopy method: the values of the parameters are determined in such a way that a better convergence rate is achieved. The proposed homotopy technique is general and has the ability to construct different families of iterative methods, for solving weakly nonlinear systems of equations. Further iterative methods are also proposed for solving general systems of nonlinear equations.
2017-01-31T10:04:21ZQasim, UswahAli, ZulifgarAhmad, FayyazSerra Capizzano, StefanoUllah, Malik ZakaAsma, MirA homotopy method is presented for the construction of frozen Jacobian iterative methods. The frozen Jacobian iterative methods are attractive because the inversion of the Jacobian is performed in terms of LUfactorization only once, for a single instance of the iterative method. We embedded parameters in the iterative methods with the help of the homotopy method: the values of the parameters are determined in such a way that a better convergence rate is achieved. The proposed homotopy technique is general and has the ability to construct different families of iterative methods, for solving weakly nonlinear systems of equations. Further iterative methods are also proposed for solving general systems of nonlinear equations.Toward concordance of Ex and JPi values for proton unbound 31S states
http://hdl.handle.net/2117/100085
Toward concordance of Ex and JPi values for proton unbound 31S states
Parikh, Anuj Ramesh; Wrede, Christopher; Fry, C.
Nucleosynthesis in classical novae on oxygen-neon white dwarfs is sensitive to the poorly constrained thermonuclear rate of the 30P(p,¿)31S reaction. In order to improve this situation, a variety of experiments have been performed over the past decade to determine the properties of proton unbound 31S levels up to an excitation energy of ˜6.7 MeV. Inconsistencies in the energies and Jp values for these levels have made it difficult to produce a useful 30P(p,¿)31S reaction rate based on experimental information. In the present work, we revisit a subset of published data on the structure of 31S in order to shed light on these problems. First, we present an alternative calibration of 31P(3He, t)31S spectra using newly available high-precision data in order to address discrepant 31S excitation energies. Second, we apply a similar method to a recently acquired 32S(d, t)31S spectrum. Third, for a different 31P(3He, t)31S experiment in which angular distributions were acquired, we present alternative fits to the experimental data in order to address discrepant 31S Jp values. Finally, we compare the Jp values from 31P(3He, t)31S to those reported from in beam ¿-ray spectroscopy experiments in order to search for potential resolutions to the inconsistencies. Overall, viable new solutions to some of the problems emerge, but other problems persist.
2017-01-26T07:17:51ZParikh, Anuj RameshWrede, ChristopherFry, C.Nucleosynthesis in classical novae on oxygen-neon white dwarfs is sensitive to the poorly constrained thermonuclear rate of the 30P(p,¿)31S reaction. In order to improve this situation, a variety of experiments have been performed over the past decade to determine the properties of proton unbound 31S levels up to an excitation energy of ˜6.7 MeV. Inconsistencies in the energies and Jp values for these levels have made it difficult to produce a useful 30P(p,¿)31S reaction rate based on experimental information. In the present work, we revisit a subset of published data on the structure of 31S in order to shed light on these problems. First, we present an alternative calibration of 31P(3He, t)31S spectra using newly available high-precision data in order to address discrepant 31S excitation energies. Second, we apply a similar method to a recently acquired 32S(d, t)31S spectrum. Third, for a different 31P(3He, t)31S experiment in which angular distributions were acquired, we present alternative fits to the experimental data in order to address discrepant 31S Jp values. Finally, we compare the Jp values from 31P(3He, t)31S to those reported from in beam ¿-ray spectroscopy experiments in order to search for potential resolutions to the inconsistencies. Overall, viable new solutions to some of the problems emerge, but other problems persist.Gamma-ray emission from SN2014J near maximum optical light
http://hdl.handle.net/2117/99845
Gamma-ray emission from SN2014J near maximum optical light
Isern Vilaboy, Jordi; Jean, Pierre; Bravo Guil, Eduardo; Knodlseder, Jurgen; Lebrun, François; Churazov, Eugene; Sunyaev, Rashid; Domingo, Alberto; Badenes, Carles; Hartmann, Dieter, H; Hoeflich, Peter; Renaud, Matthieu; Soldi, Simona; Elias Rosa, Nancy; Hernanz Carbó, Margarita; Domínguez Aguilera, Inmaculada; García Senz, Domingo; Lichti, G.G.; Vedrenne, G.; Von Ballmoos, Peter
Context. The optical light curve of Type Ia supernovae (SNIa) is powered by thermalized gamma-rays produced by the decay of 56Ni and 56Co, the main radioactive isotopes synthesized by the thermonuclear explosion of a C/O white dwarf.
Aims. Gamma-rays escaping the ejecta can be used as a diagnostic tool for studying the characteristics of the explosion. In particular, it is expected that the analysis of the early gamma emission, near the maximum of the optical light curve, could provide information about the distribution of the radioactive elements in the debris.
Methods. The gamma data obtained from SN2014J in M¿82 by the instruments on board INTEGRAL were analysed paying special attention to the effect that the detailed spectral response has on the measurements of the intensity of the lines.
Results. The 158 keV emission of 56Ni has been detected in SN2014J at ~5s at low energy with both ISGRI and SPI around the maximum of the optical light curve. After correcting the spectral response of the detector, the fluxes in the lines suggest that, in addition to the bulk of radioactive elements buried in the central layers of the debris, there is a plume of 56Ni, with a significance of ~3s, moving at high velocity and receding from the observer. The mass of the plume is in the range of ~0.03-0.08 M¿.
Conclusions. No SNIa explosion model has ever predicted the mass and geometrical distribution of 56Ni suggested here. According to its optical properties, SN2014J looks like a normal SNIa, so it is extremely important to discern whether it is also representative in the gamma-ray band.
2017-01-23T11:57:13ZIsern Vilaboy, JordiJean, PierreBravo Guil, EduardoKnodlseder, JurgenLebrun, FrançoisChurazov, EugeneSunyaev, RashidDomingo, AlbertoBadenes, CarlesHartmann, Dieter, HHoeflich, PeterRenaud, MatthieuSoldi, SimonaElias Rosa, NancyHernanz Carbó, MargaritaDomínguez Aguilera, InmaculadaGarcía Senz, DomingoLichti, G.G.Vedrenne, G.Von Ballmoos, PeterContext. The optical light curve of Type Ia supernovae (SNIa) is powered by thermalized gamma-rays produced by the decay of 56Ni and 56Co, the main radioactive isotopes synthesized by the thermonuclear explosion of a C/O white dwarf.
Aims. Gamma-rays escaping the ejecta can be used as a diagnostic tool for studying the characteristics of the explosion. In particular, it is expected that the analysis of the early gamma emission, near the maximum of the optical light curve, could provide information about the distribution of the radioactive elements in the debris.
Methods. The gamma data obtained from SN2014J in M¿82 by the instruments on board INTEGRAL were analysed paying special attention to the effect that the detailed spectral response has on the measurements of the intensity of the lines.
Results. The 158 keV emission of 56Ni has been detected in SN2014J at ~5s at low energy with both ISGRI and SPI around the maximum of the optical light curve. After correcting the spectral response of the detector, the fluxes in the lines suggest that, in addition to the bulk of radioactive elements buried in the central layers of the debris, there is a plume of 56Ni, with a significance of ~3s, moving at high velocity and receding from the observer. The mass of the plume is in the range of ~0.03-0.08 M¿.
Conclusions. No SNIa explosion model has ever predicted the mass and geometrical distribution of 56Ni suggested here. According to its optical properties, SN2014J looks like a normal SNIa, so it is extremely important to discern whether it is also representative in the gamma-ray band.Synthesis of C-rich dust in CO nova outbursts
http://hdl.handle.net/2117/99271
Synthesis of C-rich dust in CO nova outbursts
José Pont, Jordi; Halabi, Ghina M.; El Eid, MounibF.
Context. Classical novae are thermonuclear explosions that take place in the envelopes of accreting white dwarfs in stellar binary systems. The material transferred onto the white dwarf piles up under degenerate conditions, driving a thermonuclear runaway. In these outbursts, about 10-7-10-3 M¿, enriched in CNO and sometimes other intermediate-mass elements (e.g., Ne, Na, Mg, or Al for ONe novae) are ejected into the interstellar medium. The large concentrations of metals spectroscopically inferred in the nova ejecta reveal that the solar-like material transferred from the secondary mixes with the outermost layers of the underlying white dwarf.
Aims. Most theoretical models of nova outbursts reported to date yield, on average, outflows characterized by O > C, from which, in principle, only oxidized condensates (e.g., O-rich grains) would be expected.
Methods. To specifically address whether CO novae can actually produce C-rich dust, six different hydrodynamic nova models have been evolved, from accretion to the expansion and ejection stages, with different choices for the composition of the substrate with which the solar-like accreted material mixes. Updated chemical profiles inside the H-exhausted core have been used, based on stellar evolution calculations for a progenitor of 8 M¿ through H- and He-burning phases.
Results. We show that these profiles lead to C-rich ejecta after the nova outburst. This extends the possible contribution of novae to the inventory of presolar grains identified in meteorites, particularly in a number of carbonaceous phases (i.e., nanodiamonds, silicon carbides, and graphites).
2017-01-16T09:55:17ZJosé Pont, JordiHalabi, Ghina M.El Eid, MounibF.Context. Classical novae are thermonuclear explosions that take place in the envelopes of accreting white dwarfs in stellar binary systems. The material transferred onto the white dwarf piles up under degenerate conditions, driving a thermonuclear runaway. In these outbursts, about 10-7-10-3 M¿, enriched in CNO and sometimes other intermediate-mass elements (e.g., Ne, Na, Mg, or Al for ONe novae) are ejected into the interstellar medium. The large concentrations of metals spectroscopically inferred in the nova ejecta reveal that the solar-like material transferred from the secondary mixes with the outermost layers of the underlying white dwarf.
Aims. Most theoretical models of nova outbursts reported to date yield, on average, outflows characterized by O > C, from which, in principle, only oxidized condensates (e.g., O-rich grains) would be expected.
Methods. To specifically address whether CO novae can actually produce C-rich dust, six different hydrodynamic nova models have been evolved, from accretion to the expansion and ejection stages, with different choices for the composition of the substrate with which the solar-like accreted material mixes. Updated chemical profiles inside the H-exhausted core have been used, based on stellar evolution calculations for a progenitor of 8 M¿ through H- and He-burning phases.
Results. We show that these profiles lead to C-rich ejecta after the nova outburst. This extends the possible contribution of novae to the inventory of presolar grains identified in meteorites, particularly in a number of carbonaceous phases (i.e., nanodiamonds, silicon carbides, and graphites).Reaction Rates of 64Ge(p,g)65As and 65As(p,g)66Se and the Extent of Nucleosynthesis in Type I X-Ray Bursts
http://hdl.handle.net/2117/99086
Reaction Rates of 64Ge(p,g)65As and 65As(p,g)66Se and the Extent of Nucleosynthesis in Type I X-Ray Bursts
Lam, Y.H.; He, J.J.; Parikh, Anuj Ramesh
The extent of nucleosynthesis in models of type I X-ray bursts (XRBs) and the associated impact on the energy released in these explosive events are sensitive to nuclear masses and reaction rates around the 64Ge waiting point. Using the well known mass of 64Ge, the recently measured 65As mass, and large-scale shell model calculations, we have determined new thermonuclear rates of the 64Ge(p,¿)65As and 65As(p,¿)66Se reactions with reliable uncertainties. The new reaction rates differ significantly from previously published rates. Using the new data, we analyze the impact of the new rates and the remaining nuclear physics uncertainties on the 64Ge waiting point in a number of representative one-zone XRB models. We find that in contrast to previous work, when all relevant uncertainties are considered, a strong 64Ge rp-process waiting point cannot be ruled out. The nuclear physics uncertainties strongly affect XRB model predictions of the synthesis of 64Zn, the synthesis of nuclei beyond A = 64, the energy generation, and the burst light curve. We also identify key nuclear uncertainties that need to be addressed to determine the role of the 64Ge waiting point in XRBs. These include the remaining uncertainty in the 65As mass, the uncertainty of the 66Se mass, and the remaining uncertainty in the 65As(p,¿)66Se reaction rate, which mainly originates from uncertain resonance energieS
2017-01-12T11:41:30ZLam, Y.H.He, J.J.Parikh, Anuj RameshThe extent of nucleosynthesis in models of type I X-ray bursts (XRBs) and the associated impact on the energy released in these explosive events are sensitive to nuclear masses and reaction rates around the 64Ge waiting point. Using the well known mass of 64Ge, the recently measured 65As mass, and large-scale shell model calculations, we have determined new thermonuclear rates of the 64Ge(p,¿)65As and 65As(p,¿)66Se reactions with reliable uncertainties. The new reaction rates differ significantly from previously published rates. Using the new data, we analyze the impact of the new rates and the remaining nuclear physics uncertainties on the 64Ge waiting point in a number of representative one-zone XRB models. We find that in contrast to previous work, when all relevant uncertainties are considered, a strong 64Ge rp-process waiting point cannot be ruled out. The nuclear physics uncertainties strongly affect XRB model predictions of the synthesis of 64Zn, the synthesis of nuclei beyond A = 64, the energy generation, and the burst light curve. We also identify key nuclear uncertainties that need to be addressed to determine the role of the 64Ge waiting point in XRBs. These include the remaining uncertainty in the 65As mass, the uncertainty of the 66Se mass, and the remaining uncertainty in the 65As(p,¿)66Se reaction rate, which mainly originates from uncertain resonance energieS