Spiral waves and spatiotemporal chaos are sometimes harmful and should be controlled. In this paper spiral waves and spatiotemporal chaos are successfully eliminated by the pulse with a very specific spatiotemporal co...
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Spiral waves and spatiotemporal chaos are sometimes harmful and should be controlled. In this paper spiral waves and spatiotemporal chaos are successfully eliminated by the pulse with a very specific spatiotemporal configuration. The excited position D of spiral waves or spatiotemporal chaos is first recorded at an arbitrary time （to）. When the system at the domain D enters a recovering state, the external pulse is injected into the domain. If the intensity and the working time of the pulse are appropriate, spiral waves and spatiotemporal chaos can finally be eliminated because counter-directional waves can be generated by the pulse. There are two advantages in the method. One is that the tip can be quickly eliminated together with the body of spiral wave, and the other is that the injected pulse may be weak and the duration can be very short so that the original system is nearly not affected, which is important for practical applications.
Following recent successes with semivectorial polarisedẼ field solutions for rib, channel, embedded, and buried waveguides a method is presented for the determination of corresponding polarisedH̃ field modes for simi...
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Following recent successes with semivectorial polarisedẼ field solutions for rib, channel, embedded, and buried waveguides a method is presented for the determination of corresponding polarisedH̃ field modes for similar and other rectangular waveguide structures which may contain any arbitrary distribution of horizontal and vertical dielectric discontinuities. The new finite difference schemes take full account of the discontinuities in the normal gradients of magnetic field components across all internal dielectric interfaces. The polarisedH̃ field results, which are presented for various rib and embedded wave-guide structures, are found to be in excellent agreement with the corresponding polarisedẼ field modes. Application of the zero divergence constraint prevents the occurrence of spurious modes.
The current and the voltage of an X-pinch were measured. The inductance of the X-pinch was assumed to be a constant and estimated by the calculation of the magnetic field based on the well-known Biot–Savart’s Law. T...
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The current and the voltage of an X-pinch were measured. The inductance of the X-pinch was assumed to be a constant and estimated by the calculation of the magnetic field based on the well-known Biot–Savart’s Law. The voltage of the inductance was calculated with L · di/dt and subtracted from the measured voltage of the X-pinch. Then, the resistance of the X-pinch was determined and the following results were obtained. At the start of the current flow the resistance of the exploding wires is several tens of Ohms, one order of magnitude, higher than the metallic resistance of the wires at room temperature, and then it falls quickly to about 1 , which reflects the physical processes occurring in the electrically exploding wires, i.e., a current transition from the highly resistive wire core to the highly conductive plasma. It was shown that the inductive contribution to the voltage of the X-pinch is less than the resistive contribution. For the wires we used, the wires’ material and diameter have no strong influence on the resistance of the X-pinch, which may be explained by the fact that the current flows through the plasma rather than through the metallic wire itself. As a result, the current is almost equally divided between two parallel X-pinches even though the diameter and material of the wires used for these two X-pinches are significantly different.
A powerful tool to investigate hypotheses, verify experimental results and simulate the dynamics of complex systems is mathematical modeling. Different versions and generalizations of the logistic growth model have be...
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Risk-driven behaviour provides a feedback mechanism through which individuals both shape and are collectively affected by an epidemic. We introduce a general and flexible compartmental model to study the effect of het...
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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 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.
A simple fluctuation argument A la Landau suggests why probability density functions of velocity gradients of turbulent velocity fields are often found to have a close to exponential tail. The detailed functional form...
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A simple fluctuation argument A la Landau suggests why probability density functions of velocity gradients of turbulent velocity fields are often found to have a close to exponential tail. The detailed functional form depends on the assumptions made concerning the intermittency.
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 ...
Part-scale thermal process simulations play an important role in improving the part quality of the Laser Powder Bed Fusion (LPBF) process. The semi-analytical simulation method relies on the superposition of analytica...
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