Size effect and the quadratic temperature dependence of the transverse magnetoresistivity in "size-effect" tungsten single crystals

The transverse magnetoresistivity of pure tungsten single crystals with a residual resistivity ratio ρ293K/ρ4.2K of about 75000 was measured from 4.2 to 20 K and in magnetic fields of up to 15 T. The size effect, i.e. the linear dependence of the magnetoconductivity on the inverse cross sample dimensions, was studied in detail at high fields. We show that the size effect can be used for the separation of the contributions from the electron-surface and the electron-phonon scattering mechanisms to the full conductivity. We demonstrate that the electron-phonon scattering leads to the exponential temperature dependence of the conductivity, and the interference between the electron-phonon and the electron-surface processes leads to a new scattering mechanism "electron-phonon-surface" with a quadratic temperature dependence of the magnetoconductivity. © Published under licence by IOP Publishing Ltd

Magnetic States and Electronic Properties of Manganese-Based Intermetallic Compounds Mn2_2YAl and Mn3_3Z (Y = V, Cr, Fe, Co, Ni; Z = Al, Ge, Sn, Si, Pt)

We present a brief review of experimental and theoretical papers on studies of electron transport and magnetic properties in manganese-based compounds Mn$_2$YZ and Mn$_3$Z (Y = V, Cr, Fe, Co, Ni, etc.; Z = Al, Ge, Sn, Si, Pt, etc.). It has been shown that in the electronic subsystem of Mn$_2$YZ compounds, the states of a half-metallic ferromagnet and a spin gapless semiconductor can arise with the realization of various magnetic states, such as a ferromagnet, a compensated ferrimagnet, and a frustrated antiferromagnet. Binary compounds Mn$_3$Z have the properties of a half-metallic ferromagnet and a topological semimetal with a large anomalous Hall effect, spin Hall effect, spin Nernst effect, and thermal Hall effect. Their magnetic states are also very diverse: from a ferrimagnet and an antiferromagnet to a compensated ferrimagnet and a frustrated antiferromagnet, as well as an antiferromagnet with a kagome-type lattice. It has been demonstrated that the electronic and magnetic properties of such materials are very sensitive to external influences (temperature, magnetic field, external pressure), as well as the processing method (cast, rapidly quenched, nanostructured, etc.). Knowledge of the regularities in the behavior of the electronic and magnetic characteristics of Mn$_2$YAl and Mn$_3$Z compounds can be used for applications in micro- and nanoelectronics and spintronics.Comment: Review paper, 27 page

Equivalence of operations with respect to discriminator clones

For each clone C on a set A there is an associated equivalence relation, called C-equivalence, on the set of all operations on A, which relates two operations iff each one is a substitution instance of the other using operations from C. In this paper we prove that if C is a discriminator clone on a finite set, then there are only finitely many C-equivalence classes. Moreover, we show that the smallest discriminator clone is minimal with respect to this finiteness property. For discriminator clones of Boolean functions we explicitly describe the associated equivalence relations.Comment: 17 page

Electrical and galvanomagnetic properties of AuAl2+6%Cu intermetallic compounds at low temperatures

The AuAl2 intermetallic compounds are of substantial interest in view of their application potential. The investigated intermetallics AuAl 2+6%Cu were prepared from fine powders of AuAl2 and Cu by vacuum sputtering on a glass substrate and consisted of films with a thickness of about one micrometer. The films were annealed. The temperature and field dependence of the electroresistivity, the magnetoresistivity and the Hall effect of AuAl2+6%Cu films were measured in the temperature interval from 4.2 to 100 K and at magnetic fields of up to 15 T. We demonstrate that the temperature dependence of the electroresistivity has a minimum at T = 20 K and a metallic behavior above this temperature. The magnetoresistivity is very small (less then 1%), positive at low temperatures and negative above 12 K. The Hall coefficient is positive, which corresponds to the holes in a one zone model with a charge carrier concentration of about 1.6 1020 cm-3. © Published under licence by IOP Publishing Ltd

Specific features of the electrical resistance of half-metallic ferromagnetic alloys Co2CrAl and Co2CrGa

It has been shown by comparing the results of studying the electrical and magnetic properties of the half-metallic ferromagnetic Heusler alloys Co2CrAl and Co2CrGa with the calculations of their electronic structure that high values of the electrical resistivity ρ are caused by a disordered distribution of atoms over the sites of the L21 cubic structure, and the anomalous behavior of ρ(T) is associated with the transformation of the electronic spectrum due to the ferromagnetic-to-paramagnetic transition. © 2013 Pleiades Publishing, Ltd

Automatic satellite building construction monitoring

One of the promising applications of satellite images is building construction monitoring. It allows to control the construction progress around the world even in the locations that are hard to reach. One of the main hurdles of this approach is the interpretation of the image data. In this paper, we have employed several novel deep learning techniques to tackle the problem. Various image segmentation and object detection networks were combined into a unified pipeline, which was then used to determine the building construction progress.Comment: 10 pages, 5 figures, 3 table

The Republic of Korea and the Arctic region: from policy formulating to policy making

The following article is a policy review paper devoted to the general analysis of the Arctic policy of the Republic of Korea. The analysis includes the explanation of the country’s demand for conducting its own policy in the Arctic that mostly resides in the peculiarities of South Korea’s geographical position and economic conditions and demands. The policy of South Korea in the Arctic region is highlighted in the three stages: before joining the Arctic Council, during the first master plan for the Arctic, and after the updated Arctic policy was issued. The brief history of the Korea’s participation in the Arctic activities is highlighted. Also, the provisions of Korea’s first master plan for the Arctic are highlighted, and some conclusions are made regarding its implementation. Then the updated Arctic policy of South Korea is examined. The core conclusion is that during 20 year of participation in the Arctic-related activities, the Republic of Korea has transformed its Arctic policy from being research-oriented only to providing national economic benefits from the multilateral inclusion in the Arctic cooperation institutions and events. Some further reflections on Korea’s further Arctic policy are provided at the conclusion

User presence detection based on tracking network activity in smartroom

The SmartRoom system provides a set of services for assisting collaborative activity when many participants are physically present in the same room. The SmartRoom service intelligence is due to the use of diverse sources of information on ongoing activity. One promising source is information on user presence and network activity of the participants. In this paper, we consider the problem of utilizing such an information source for smart spaces based on the Smart-M3 platform. We employ the Innorange technology, which is one of the many examples for passive radio detection in WLAN. We define scenarios with this information source for use in SmartRoom services. We propose an integration solution oriented to Smart- M3 applications. Our software prototype is integrated into the SmartRoom system. Experimental study confirms the feasibility and reasonable performance of the proposed solution

Geophysical models of Western Aphrodite-Niobe region: Venus

The new topography and gravitational field data for Venus expressed in spherical harmonics of degree and order up to 50 allow us to analyze the crust-mantle boundary relief and stress state of the Venusian lithosphere. In these models, we consider models in which convection is confined beneath a thick, buoyant lithosphere. We divide the convection regime into an upper mantle and lower mantle component. The lateral scales are smaller than on Earth. In these models, relative to Earth, convection is reflected in higher order terms of the gravitational field. On Venus geoid height and topography are highly correlated, although the topography appears to be largely compensated. We hypothesize that Venus topography for those wavelengths that correlate well with the geoid is partly compensated at the crust-mantle boundary, while for the others compensation may be distributed over the whole mantle. In turn the strong sensitivity of the stresses to parameters of the models of the external layers of Venus together with geological mapping allows us to begin investigations of the tectonics and geodynamics of the planet. For stress calculations we use a new technique of space- and time-dependent Green's response functions using Venus models with rheologically stratified lithosphere and mantle and a ductile lower crust. In the basic model of Venus the mean crust is 50-70 km thick, the density contrast across the crust-mantle boundary is in the range from 0.3 to 0.4 g/cm(exp -3). The thickness of a weak mantle zone may be from 350 to 1000 km. Strong sensitivity of calculated stress to various parameters of the layered model of Venus together with geological mapping and analysis of surface tectonic patterns allow us to investigate the tectonics and geodynamics of the planet. The results are presented in the form of maps of compression-extension and maximum shear stresses in the lithosphere and maps of crust-mantle boundary relief, which can be presented as a function of time. We have modeled the region of Western Aphrodite and the Niobe plains to get reasonable depths of compensation. Crust mantle boundary relief is calculated for Western Aphrodite-Niobe relative to a mean crustal thickness of 50 km. The calculations include the consequences of simple crust models and more complicated models with a weak, ductile lower crust, a strong upper mantle and a weak lower mantle layer