Condensate Formation in Collisionless Plasma

Particle condensates in general magnetic mirror geometries in high-temperature plasmas may be caused by a discrete resonance with thermal ion-acoustic background noise near mirror points. The resonance breaks the bounce symmetry, temporally locking the particles to the resonant wavelength. The relevant correlation lengths are the Debye length in the parallel direction and the ion gyroradius in the perpendicular direction.

Dielectric permittivity and relaxation process investigation of C-doped TlInS2 crystals

In this work, permittivity of TlInS2 and TlInS2 (5%[Formula: see text]C) crystals has been investigated at the AC field with 100–500 K temperatures ranges. [Formula: see text] temperature dependencies of TlInS2 and TlInS2 (5%[Formula: see text]C) crystals are studied at the frequency range of 25–106 Hz. Activation energy and ionic conductivity nature of sample were analyzed. Moreover, permittivity of these samples was studied at the perpendicular direction of axis “[Formula: see text]” of TlInS2 (5%[Formula: see text]C) crystals. The jumping process in the TlInS2 (5%[Formula: see text]C) crystals was studied using [Formula: see text] temperature dependencies.

Employment of Barkhausen Noise Technique for Assessment of Prestressing Bars Damage with Respect of Their Over-Stressing

This paper investigates the potential of a non-destructive magnetic technique based on Barkhausen noise emission for the monitoring of prestressing bars with respect to their undesired over-stressing. Barkhausen noise signals are correlated with tensile stress, residual stresses, and microhardness measurements. It was found that prestressing bars exhibit strong magnetic anisotropy which becomes more pronounced along with the increasing degree of the bar’s over-stressing. Barkhausen noise emission becomes strongly attenuated in the direction of the tensile stress at the expense of the perpendicular direction. However, the Barkhausen noise emission in the direction of the tensile stress exhibits a continuous and remarkable decrease, whereas the Barkhausen noise steep increase for lower degrees of over-stressing is followed by early saturation for higher over-stressing. This study demonstrates that the Barkhausen noise technique is capable of distinguishing between the prestressing bars loaded below yielding, and those which are over-stressed.

Направленное излучение из квантовых точек GaAs в теле нитевидных нанокристаллов AlGaAs

We present the results on experimental studies of the directional radiation from GaAs quantum dots in AlGaAs nanowires grown by molecular beam epitaxy technique on silicon surface. It was shown that the radiation intensity from GaAs quantum dots in the direction of nanowires growth is 2 orders of magnitude higher than the intensity of radiation in the perpendicular direction.

The Influence of Thermal Properties Anisotropy on Subtractive Laser Processing of B4C/h-BN Composites

This work concerns boron carbide matrix composites with the addition of hexagonal boron nitride particles (h-BN) as a solid lubricate. The composite materials were hot-pressed and analysed in terms of phase, structure, and microstructure changes in relation to the h-BN content. The uniaxial pressure applied during the manufacturing process allowed the orientation of single h-BN particles and its agglomerates in perpendicular direction to the pressing axis. The anisotropy of heat transfer and thermal expansion coefficient (CTE) and density changes in relation to temperature are discussed. Thermal diffusivity and conductivity were measured in relation to the material direction by the laser flash analysis method (LFA). In this paper, understanding the heat flow and CTE changes allowed explaining the results of investigated subtractive laser processes of the manufactured composites. The laser ablation process was conducted on B4C/h-BN composites in parallel and perpendicular direction to each other. It was done in a continuous work (CW) mode at 50 W with a 40 µm spot and 3 mm/s beam travel speed. The influence of h-BN particles and their orientation on thermal properties is discussed. The effect of laser processing on B4C/h-BN composites was also discussed in relation to the material surface roughness measured with a confocal microscope, microstructure observations, density, and thermal properties changes in relation to the material direction.

The Influence of Jam Density and Merging Cyclists on the Queue Discharge Rate

An increasing number of people use the bicycle for urban trips resulting in local congestion at intersections, especially during peak hours. Understanding the queue dynamics is key to find the correct measures that can reduce the delays for cyclists without affecting other traffic modes. To this end, the discharge process of bicycle queues is studied, focusing on the impact of jam density on the queue discharge rate and how this process is affected by cyclists that merge into the queue during the discharge phase. The impact of merging cyclists is captured by a newly introduced bicycle equivalent (BE) value. This direction-specific BE value is used to convert a merging cyclist into a cyclist that is waiting in the original queue. Results show that the queue discharge rate increases with increasing density of the queue. Furthermore, cyclists that merge by overtaking contribute to the queue discharge rate, while cyclists who merge from a perpendicular direction hinder the discharge process, thereby decreasing the bicycle flow at the intersection. The insights can be used to develop measures which minimise delay at intersections and to design efficient infrastructure for bicyclists.

Closed Knight’s Tours on (m,n,r)-Ringboards

A (legal) knight’s move is the result of moving the knight two squares horizontally or vertically on the board and then turning and moving one square in the perpendicular direction. A closed knight’s tour is a knight’s move that visits every square on a given chessboard exactly once and returns to its start square. A closed knight’s tour and its variations are studied widely over the rectangular chessboard or a three-dimensional rectangular box. For m,n>2r, an (m,n,r)-ringboard or (m,n,r)-annulus-board is defined to be an m×n chessboard with the middle part missing and the rim contains r rows and r columns. In this paper, we obtain that a (m,n,r)-ringboard with m,n≥3 and m,n>2r has a closed knight’s tour if and only if (a) m=n=3 and r=1 or (b) m,n≥7 and r≥3. If a closed knight’s tour on an (m,n,r)-ringboard exists, then it has symmetries along two diagonals.

"Anti-squeeze" for Mantle Convection Simulations in Two-Dimensional Spherical Geometry

<p>It is common to perform 2-dimensional simulations of mantle convection in spherical geometry, either with (r, theta) axisymmetry or the (r, phi) spherical annulus geometry (Hernlund and Tackley, PEPI 2008). </p><p>A problem with both of these is that the geometrical restriction forces deformation that is not present in 3 dimensions. Specifically, in a 2-D spherical approximation, a downwelling is forced to contract in the plane-perpendicular direction, requiring it to extend in the 2 in-plane directions. In other words, it is "squeezed" in the plane-perpendicular direction.  If the downwelling has a high viscosity, as a cold slab does, then it resists this forced deformation, sinking much more slowly than in three dimensions, in which it could sink with no deformation. This can cause unrealistic behaviour and scaling relationships for high viscosity contrasts. </p><p>This problem can be solved by subtracting the geometrically-forced deformation ("squeezing") from the strain-rate tensor when calculating the stress tensor. Specifically, components of in-plane and plane-normal strain rate that are required by and proportional to the vertical (radial) velocity are subtracted, a procedure that is here termed "anti-squeeze". It is demonstrated here that this "anti-squeeze" correction results in sinking rates and scaling relationships that are similar to those in 3-D geometry whereas without it, abnormal and physically unrealistic results can be obtained for high viscosity contrasts. This correction has been used for 2-D geometries in the code StagYY (Tackley, PEPI 2008; Hernlund and Tackley, PEPI 2008) since 2010.</p>