Thermal and luminescent properties of M2Zn(VO3) 4 (M = Rb, Cs)

We have developed processes for the synthesis of the Rb 2Zn(VO3)4 and Cs2Zn(VO 3)4 tetrametavanadates. Rb2Zn(VO 3)4 has been prepared by solid-state reaction (350 C) between presynthesized RbVO3 and ZnV2O6 powders, and Cs2Zn(VO3)4 has been prepared by the Pechini method (sol-gel process). Both metavanadates crystallize in monoclinic symmetry (sp. gr. P21/m). Thermochemical characterization results demonstrate that the vanadates undergo complex transformations during heating to 450 C and subsequent cooling. As a result, the materials are in a nonequilibrium state at room temperature and consist of both the parent double metavanadates and their peritectic decomposition products. We believe that the formation of the structure of the M2Zn(VO3)4 compounds from their melts is a kinetically hindered process. These compounds are structurally stable only at temperatures below 369 (Rb2Zn(VO 3)4) or 420 C (Cs2Zn(VO3) 4). We have measured for the first time the diffuse reflectance and photoluminescence excitation spectra of the two tetrametavanadates in their emission range and their photoluminescence spectra at various excitation wavelengths and determined their chromaticity coordinates. Their X-ray luminescence and scintillation decay characteristics have been determined for the first time under pulsed electron beam excitation. The electron excitation dissipation processes in the cesium and rubidium compounds are shown to be similar. We discuss the origin of the emission bands in the mixed vanadates and their potential application areas. © 2013 Pleiades Publishing, Ltd

Softening and hardening of ECAP nickel under ultrasonic treatment

Commercially pure nickel was processed by equal channel angular pressing (ECAP) through route Bc for 12 passes to obtain an ultrafine grained (UFG) microstructure and further subjected to an ultrasonic treatment (UST) which introduced a maximum amplitude equivalent to anormal stresses of 100 MPa in a steady state regime. It was observed that the microstructure of UFG Ni can be differently altered depending on the position in the sample, i.e. on the amplitude of the ultrasonic wave. The microstructural analysis demonstrated a lower dislocation density (due to the activation of recovery) at the cross section of the specimen subjected to UST at an amplitude equal to 0.8 of the maximum one, plus enhanced hardening in the cross section at the maximum amplitude.Preprin

Algorithms for collaborative filtering in Point-of-Interest Recommendation Systems

S dostupností obrovského množství uživatelů a geolokačních sociálních sítí získal v posledních letech problém doporučení míst zájmu značnou pozornost výzkumu. Zatímco předchozí práce zabývající se doporučením míst zájmu se většinou zaměřovaly na zkoumání prostorového, časového a sociálního vlivu, použití dodatečných obsahových informací nebylo cíleně studováno. Tyto dodatečné informace mohou nejen zlepšit kvalitu doporučení, ale také překonat i problém tzv. studeného startu. V této práci navrhuji algoritmus pro doporučení míst zájmu založený na faktorizaci matice s přidanou obsahovou informací -- atributy a kategorie míst zájmu. Navrhuji dvě varianty algoritmu, které mohou pracovat s explicitní a implicitní zpětnou vazbou. Informace o atributech a kategoriích jsou získány z existujících datových sad a použity k měření podobnosti mezi dvěma místy. Experimentální výsledky ukazují, že navrhovaná metoda zlepšuje kvalitu doporučení, překonává většinu populárních algoritmů kolaborativního filtrováni a dokáže efektivně zvládnout problém studeného startu.With the availability of the vast amount of users and Location-based social networks, the problem of POI recommendations has been widely studied and received significant research attention in the last seven years, and many approaches have been suggested. While previous works of POI recommendation mostly focused on investigating the spatial, temporal, and social influence, the use of additional content information has not been directionally studied. Such additional information can not only improve the performance of the recommendation system but also help to overcome the so-called cold start problem. In this paper, we propose the content-aware matrix factorization method based on incorporating POI attribute and categories information. We propose two variants of the algorithm that can work with explicit and implicit feedback. The attribute and categories information of a POI is collected from existing datasets and used to measure the similarity between two POIs. These similarity values are subsequently used as a regularization term added to the objective function of matrix factorization. Experimental results show that the proposed method improves the quality of recommendation, outperforms most state-of-the-art collaborative filtering algorithms and can effectively cope with the so-called cold start problem

System-didactic complex of training for teachers of natural and geographical disciplines

© Medwell Journals, 2016.Purpose of the study the development and using in the process of training teachers of natural geographical disciplines of system-didactic complex that includes diagnostics readiness of the teacher to the creative teaching activities, the implementation of inter-subject relationship, the competence approach. System-didactic complex built on metamethodic and holistic ideas. System-didactic complex allows: to claim the creativity of the teacher, the scientific potential of the fundamental disciplines of the creative potential of the teacher, going beyond disciplinary disunity, transfer logical form of scientific knowledge in activity-shape, forming a complete picture of the world, the relationship of various phenomena

Classroom-based and remote methods of creative potential development of a teacher in the process of advanced training

The goal of the article is the use and comparison of classroom-based and remote methods of creative potential development of a teacher in the process of advanced training. The use of classroom-based and remote methods, which promote the development of creative potential of a teacher, is considered on the example of complex integrated tasks