Superconductivity at 5.2 K in ZrTe3 polycrystals and the effect of Cu, Ag intercalation

We report the occurrence of superconductivity in polycrystalline samples of ZrTe3 at 5.2 K temperature at ambient pressure. The superconducting state coexists with the charge density wave (CDW) phase, which sets in at 63K. The intercalation of Cu or Ag, does not have any bearing on the superconducting transition temperature but suppresses the CDW state. The feature of CDW anomaly in these compounds is clearly seen in the DC magnetization data. Resistivity data is analysed to estimate the relative loss of carriers and reduction in the nested Fermi surface area upon CDW formation in the ZrTe3 and the intercalated compounds.Comment: 5 pages, 8 figure

Collisionless Magnetic Reconnection via Alfven Eigenmodes

We propose an analytic approach to the problem of collisionless magnetic reconnection formulated as a process of Alfven eigenmodes' generation and dissipation. Alfven eigenmodes are confined by the current sheet in the same way that quantum mechanical waves are confined by the tanh^2 potential. The dynamical time scale of reconnection is the system scale divided by the eigenvalue propagation velocity of the n=1 mode. The prediction of the n=1 mode shows good agreement with the in situ measurement of the reconnection-associated Hall fields

Particle Image Thermometry for Natural Convection Flows

Particle Image Thermometry (PIT) is a technique by which temperature fields can be obtained non-invasively using thermochromic liquid crystals (TLCs) through image processing of experimental true-colour photographs. This is done using a calibration curve (hue versus temperature). With the calibration data, every pixel of the colour photograph is transformed to a temperature value, and thus accurate experimental temperature maps are obtained. Using this technique, examples of steady and unsteady natural convection are presented, which include steady magnetic convection of paramagnetic fluids in a cubic enclosure heated and cooled from opposite walls, and unsteady convective flows in a reservoir model cooled from above (night-time cooling). The instantaneous measurement of temperature fields is very useful for understanding flow characteristics in situations where conventional flow visualisation is not sufficient. This method also provides additional quantitative information for comparisons with numerical modelling

Challenges and Solutions for Autonomous Robotic Mobile Manipulation for Outdoor Sample Collection

In refinery, petrochemical, and chemical plants, process technicians collect uncontaminated samples to be analyzed in the quality control laboratory all time and all weather. This traditionally manual operation not only exposes the process technicians to hazardous chemicals, but also imposes an economical burden on the management. The recent development in mobile manipulation provides an opportunity to fully automate the operation of sample collection. This paper reviewed the various challenges in sample collection in terms of navigation of the mobile platform and manipulation of the robotic arm from four aspects, namely mobile robot positioning/attitude using global navigation satellite system (GNSS), vision-based navigation and visual servoing, robotic manipulation, mobile robot path planning and control. This paper further proposed solutions to these challenges and pointed the main direction of development in mobile manipulation

Soliton with a Pion Field in the Global Color Symmetry Model

We calculate the property of the global color symmetry model soliton with the pion field being included explicitly. The calculated results indicate that the pion field provides a strong attraction so that the eigen-energy of a quark and the mass of a soliton reduce drastically, in contrast to those with only the sigma field.Comment: 15 pages, 2 figure

Void-mediated formation of Sn quantum dots in a Si matrix

Atomic scale analysis of Sn quantum dots (QDs) formed during the molecular beam-epitaxy (MBE) growth of Sn_xSi_(1−x) (0.05 ⩽ x ⩽ 0.1) multilayers in a Si matrix revealed a void-mediated formation mechanism. Voids below the Si surface are induced by the lattice mismatch strain between Sn_xSi_(1−x) layers and Si, taking on their equilibrium tetrakaidecahedron shape. The diffusion of Sn atoms into these voids leads to an initial rapid coarsening of quantum dots during annealing. Since this formation process is not restricted to Sn, a method to grow QDs may be developed by controlling the formation of voids and the diffusion of materials into these voids during MBE growth

Magnetization reversal in Kagome artificial spin ice studied by first-order reversal curves

Magnetization reversal of interconnected Kagome artificial spin ice was studied by the first-order reversal curve (FORC) technique based on the magneto-optical Kerr effect and magnetoresistance measurements. The magnetization reversal exhibits a distinct six-fold symmetry with the external field orientation. When the field is parallel to one of the nano-bar branches, the domain nucleation/propagation and annihilation processes sensitively depend on the field cycling history and the maximum field applied. When the field is nearly perpendicular to one of the branches, the FORC measurement reveals the magnetic interaction between the Dirac strings and orthogonal branches during the magnetization reversal process. Our results demonstrate that the FORC approach provides a comprehensive framework for understanding the magnetic interaction in the magnetization reversal processes of spin-frustrated systems

How expensive space-zero-gravity convection experiments can be carried out in terrestrial conditions – magnetic convection of a paramagnetic fluid

Over the last decade or so it has became possible to build high-temperature super-conducting magnets that operate in a laboratory environment. Many new phenomena connected with strong magnetic fields have been reported (e.g. promotion of combustion, magnetic levitation, separation methods for weakly magnetic materials etc.). There are many applications of the use of magnetic force on the Earth. For instance, knowing how to control such a force makes it possible to negate the influence of the gravitational force and study a particular phenomenon as it would occur in the Cosmos, but under terrestrial conditions, avoiding the need for expensive space travel. The use of a magnetic field may also help in many processes such as crystal growth, mixing and material processing. The present work is concerned with magnetic convection of a paramagnetic fluid in a cubical enclosure heated and cooled from the sidewalls. The influence of a 10-T magnetic field on the convection mode of the paramagnetic fluid and the heat transfer rate were investigated numerically and experimentally, and compared with gravitational natural convection. The present study clearly shows that natural convection can be enhanced, and the direction of the convection flow can be changed using a strong magnetic field in terrestrial conditions