The application of the Lattice Boltzmann method to the one-dimensional modeling of pulse waves in elastic vessels

The one-dimensional nonlinear equations for the blood flow motion in distensible vessels are considered using the kinetic approach. It is shown that the Lattice Boltzmann (LB) model for non-ideal gas is asymptotically equivalent to the blood flow equations for compliant vessels at the limit of low Knudsen numbers. The equations of state for non-ideal gas are transformed to the pressure-luminal area response. This property allows to model arbitrary pressure-luminal area relations. Several test problems are considered: the propagation of a sole nonlinear wave in an elastic vessel, the propagation of a pulse wave in a vessel with varying mechanical properties (artery stiffening) and in an artery bifurcation, in the last problem Resistor–Capacitor–Resistor (RCR) boundary conditions are considered. The comparison with the previous results shows a good precision.     

Time-dependent Ginzburg–Landau equations for multi-gap superconductors

We numerically solve the time-dependent Ginzburg–Landau equations for two-gap superconductors using the finite-element technique. The real-time simulation shows that at low magnetic field, the vortices in small-size samples tend to form clusters or other disorder structures. When the sample size is large, stripes appear in the pattern. These results are in good agreement with the previous experimental observations of the intriguing anomalous vortex pattern, providing a reliable theoretical basis for the future applications of multi-gap superconductors.     

澄清对相对论性原理和协变性的误解

近来有些文章断言,在一个惯性参考系里能量守恒的物理系统,在别的参考系看来能量也一定守恒.实际上这些作者混淆了物理方程式的协变性和相对性原理.本文将澄清这一误解.     

对自由落体的诺维科夫时间与牛顿绝对时间关系讨论

文章首先将史瓦西黑洞场中自由下落质点的固有时(诺维科夫坐标时)公式,由自然单位制化成了国际单位制中的形式.然后,根据牛顿第二定律和万有引力定律,推导出了自由下落质点经历的绝对时间公式,进而证明了广义相对论中自由落体经历的固有时,恰好等于牛顿力学给出的绝对时间.最后,对自由下落质点在黑洞内外经历的时间进行了特例计算.     

Initial boundary value problem for a class of strongly damped semilinear wave equations with logarithmic nonlinearity

This paper deals with the initial boundary value problem for strongly damped semilinear wave equations with logarithmic nonlinearity $u_{tt}-\Delta u-\Delta u_t={\phi }_p\left(u\right)log\left|u\right|$ in a bounded domain $\Omega \subset {\mathbb{R}}^n$. We discuss the existence, uniqueness and polynomial or exponential energy decay estimates of global weak solutions under some appropriate conditions. Moreover, we derive the finite time blow up results of weak solutions, and give the lower and upper bounds for blow-up time by the combination of the concavity method, perturbation energy method and differential–integral inequality technique.     

The Bergman kernel for the Vekua equation

The paper extends some well-known results for analytic functions onto solutions of the Vekua equation $\partial \overline{{}_z}W=aW+b\overline{W}$ regarding the existence and construction of the Bergman kernel and of the corresponding Bergman projection operator.     

Ionic liquid gating control of magnetic anisotropy in Ni0.81Fe0.19 thin films

Voltage control magnetism is one of the most energy efficient pathway towards magnetoelectric (ME) device. Ionic liquid gating (ILG) method has already shown impressive manipulation power at the IL/electrode interface to influence the structure, orbital as well as spin of the electrode materials. As key material in anisotropy magnetoresistance sensor and spin valve heterostructure, the permalloy Ni_0.81Fe_0.19 was utilized as the electrode to investigate the ILG induced magnetic anisotropy change. In this work, we realized magnetic anisotropy control in Au/[DEME]⁺[TFSI]^-/Ni_0.81Fe_0.19 (2.5 nm)/Ta heterostructure via ILG caused electrostatic doping. This is evidenced in situ reversible ferromagnetic field (H_r) shift with electron spin resonance (ESR) spectrometer. Aiming at the question whether the charge accumulation at the ionic liquid interface is the main control mechanism at low voltage, we carefully tested the relationship between the change of resonance field and the amount of surface charge. It was found that these two had a good linear relationship between −1 V and +1 V. Defining the linear parameter as A whose value is 28.7 mT m²/Col. Unlike previously reported chemical regulation of Co, this article used ionic liquids to physically regulate NiFe, which has not been studied in the previous ionic liquid regulation. And NiFe has a narrower resonance line width for easy reference to microwave devices. In addition, It also has a stronger ferromagnetic signal than Co, which can be more easily detected as a sensor device. Therefore, this system is more promising. The ILG control NiFe may lead to a new kind of magnetoelectric sensor devices and path a new way to low energy consumption spintronics.