A method is developed for the optimal estimation of the parameters in a fully nonlinear model of flow in a channel. The data assimilated consist of values of the water surface elevation during a given interval. The me...
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A method is developed for the optimal estimation of the parameters in a fully nonlinear model of flow in a channel. The data assimilated consist of values of the water surface elevation during a given interval. The method is based on the adjoint method of optimal control. It is shown that accurate values of the parameters can be estimated, and the estimates are stable with respect to random perturbations of the data provided that data from a sufficient number of locations are available for assimilation.
Despite the numerous reports on the time-honored superconductor NiBi3, theoretical investigations remain limited, particularly regarding the impact of spin-orbit coupling (SOC). Based on first-principles calculations,...
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Despite the numerous reports on the time-honored superconductor NiBi3, theoretical investigations remain limited, particularly regarding the impact of spin-orbit coupling (SOC). Based on first-principles calculations, the electronic topology of NiBi3 is mainly studied herein. Nodal loops which intersect to form a nodal chain structure are enclosed by two valence bands, and they are fully gapped by SOC. The full gap contains topological surface states defined by a Z2 topological invariant, while for the top valence band and bottom conduction band, a three-dimensional massless Dirac point at Γ is produced by the two bands with SOC. In addition, nodal surfaces which prevalently appear in the band structure without SOC are present on the entire Brillouin zone surface, and SOC only partially gaps them, thus leading to nodal lines unaffected by SOC. Type-I and type-II fermions, which are distinguished by the tilt of cones, are shown to coexist in the bulk bands. Furthermore, two Rashba-split bands are found on the (100) surface, whose inner and outer Fermi circles share the same spin polarization direction. Finally, our analysis reveals that the superconductivity of NiBi3 primarily originates from the p orbitals of Bi and d orbitals of Ni coupling with the vibration modes of Bi. The rich topological features identified in this study suggest that NiBi3 holds significant potential for realizations of topological superconductivity and other exotic phenomena.
We present initial results on Hessian-free force-gradient integrators for lattice field theories. Integrators of this framework promise to provide substantial performance enhancements, particularly for larger lattice ...
We present an efficient algorithm for calculating the minimum energy path(MEP)and energy barriers between local minima on a multidimensional potential energy surface(PES).Such paths play a central role in the understa...
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We present an efficient algorithm for calculating the minimum energy path(MEP)and energy barriers between local minima on a multidimensional potential energy surface(PES).Such paths play a central role in the understanding of transition pathways between metastable *** method relies on the original formulation of the string method[***.B,66,052301(2002)],*** evolve a smooth curve along a direction normal to the *** algorithm works by performing minimization steps on hyperplanes normal to the *** the problem of finding MEP on the PES is remodeled as a set of constrained minimization *** provides the flexibility of using minimization algorithms faster than the steepest descent method used in the simplified string method[***.,126(16),164103(2007)].At the same time,it provides a more direct analog of the finite temperature string *** applicability of the algorithm is demonstrated using various examples.
Enhancing carrier mobility plays a crucial role in significantly improving thermoelectric performance. However, due to the lack of a systematic strategy, achieving high mobility remains an elusive goal for most compou...
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A class of time fractional partial differential equations is considered, which in- cludes a time fractional diffusion equation, a time fractional reaction-diffusion equation, a time fractional advection-diffusion equa...
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A class of time fractional partial differential equations is considered, which in- cludes a time fractional diffusion equation, a time fractional reaction-diffusion equation, a time fractional advection-diffusion equation, and their corresponding integer-order partial differential equations. The fundamental solutions to the Cauchy problem in a whole-space domain and the signaling problem in a half-space domain are obtained by using Fourier- Laplace transforms and their inverse transforms. The appropriate structures of the Green functions are provided. On the other hand, the solutions in the form of a series to the initial and boundary value problems in a bounded-space domain are derived by the sine- Laplace or cosine-Laplace transforms. Two examples are presented to show applications of the present technique.
The oscillatory Couette flow of a magnetohydrodynamic （MHD） Sisko fluid between two infinite non-conducting parallel plates is explored in a rotating frame. The lower plate is fixed, and the upper plate is oscillati...
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The oscillatory Couette flow of a magnetohydrodynamic （MHD） Sisko fluid between two infinite non-conducting parallel plates is explored in a rotating frame. The lower plate is fixed, and the upper plate is oscillating in its own plane. Using MATLAB, a numerical solution to the resulting nonlinear system is presented. The influence of the physical parameters on the velocity components is analyzed. It is found that the effect of rotation on the primary velocity is more significant than that on the secondary velocity. Further, the oscillatory character in the flow is also induced by rotation. The considered flow situation behaves inertialess when the Reynolds number is small.
The operational mechanics of a novel drug release implant capsule are formulated in terms of a one-dimensional Stefan moving boundary diffusion problem. computational solutions for this are obtained using Meyer's ...
The operational mechanics of a novel drug release implant capsule are formulated in terms of a one-dimensional Stefan moving boundary diffusion problem. computational solutions for this are obtained using Meyer's numerical technique, and a complementary open-form analytical solution applicable to constant drug impregnations is obtained by a perturbation method. A similarity solution pertaining to a particular boundary condition is also given. The question of attaining a predetermined drug release-rate/time characteristic by the introduction of a spatially variable drug impregnation is also considered.
Recent angle-resolved photoemission spectroscopy (ARPES) experiments on the kagome metal CsV3Sb5 revealed distinct multimodal dispersion kinks and nodeless superconducting gaps across multiple electron bands. The prom...
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Recent angle-resolved photoemission spectroscopy (ARPES) experiments on the kagome metal CsV3Sb5 revealed distinct multimodal dispersion kinks and nodeless superconducting gaps across multiple electron bands. The prominent photoemission kinks suggest a definitive coupling between electrons and certain collective modes, yet the precise nature of this interaction and its connection to superconductivity remain to be established. Here, employing the state-of-the-art ab initio many-body perturbation theory computation, we present direct evidence that electron-phonon (e-ph) coupling induces the multimodal photoemission kinks in CsV3Sb5, and profoundly, drives the nodeless s-wave superconductivity, showcasing the diverse manifestations of the e-ph coupling. Our calculations well capture the experimentally measured kinks and their fine structures, and reveal that vibrations from different atomic species dictate the multimodal behavior. Results from anisotropic GW-Eliashberg equations predict a phonon-mediated superconductivity with nodeless s-wave gaps, in excellent agreement with various ARPES and scanning tunneling spectroscopy measurements. Despite the universal origin of the e-ph coupling, the contributions of several characteristic phonon vibrations vary in different phenomena, highlighting a versatile role of e-ph coupling in shaping the low-energy excitations of kagome metals.
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