Phase diagram of soft-core bosons in two dimensions

The low temperature phase diagram of Bose soft disks in two dimensions is studied by numerical simulations. It is shown that a supersolid cluster phase exists, within a range of the model parameters, analogous to that recently observed for a system of aligned dipoles interacting via a softened potential at short distance. These findings indicate that a long-range tail of the interaction is unneeded to obtain such a phase, and that the soft-core repulsive interaction is the minimal model for supersolidity

Quantum Monte Carlo studies of soft Bosonic systems and Minimum Energy Pathways.

In this thesis, we make use of Monte Carlo techniques to address two rather different subjects in condensed matter physics. The first study deals with the characterization of a relatively novel and elusive phase of matter, the so-called supersolid, in which crystalline order and dissipationless flow coexist. While supersolidity is a well studied phenomenology in lattice models, we will be working here in continuous space, where much fewer results are available. Specifically, we study a soft core Bosonic system, quantum analog of thoroughly studied classical models, which displays an unambiguous supersolid phenomenology. In this system such a behavior is not obtained through Bose Condensation of lattice defects, but rather it is mean field in character. By computer simulations we characterize many properties of the system: of these, the most prominent are the phase diagram of the system and its excitation spectrum. This study is loosely related to the ultracold atom experimental field, as it is speculated that interparticle potential pertaining to the same class of the one employed here may be realized in this context. After the recent (and apparently definitive) ruling out of supersolidity effects in ^4He, it seems fair to state that ultracold atoms are the most promising candidate for the observation of this phenomenology. In this section we employ our own implementation of the worm algorithm on the continuum. The second part of this thesis is instead related to electronic structure, more specifically to the study of minimum energy pathways of reactions calculated via quantum Monte Carlo methods. In particular, we aim at assessing the computational feasibility and the accuracy of determining the most significant geometries of a reaction (initial/final and transition state) and its energy barrier via these stochastic techniques. To this end, we perform calculations on a set of simple reactions and compare the results with density functional theory and high level quantum chemistry calculations. We show that the employed technique indeed performs better than density functional for both geometries and energy barrier. Therefore our methodology is a good candidate to study reactions in which an high accuracy is needed, but it is not possible to employ high level quantum chemistry methods due to computational limitations. We believe that this study is significant also because of its systematic use of forces from Monte Carlo simulations. Although several studies have addressed various aspects of the problem of computing forces within quantum Monte Carlo accurately and efficiently, there is little awareness that such estimators are in fact mature, and consequently there are very few studies which actually employ them. We hope to show here that these estimators are actually ready to be used and provide good results. In this section we have mainly developed interfaces for existing Quantum Monte Carlo codes

Pemanfaatan Kecerdasan Buatan Dalam Kesehatan dan Keselamatan Kerja Di Bidang Kelistrikan

Kecerdasan buatan telah menjadi salah satu penemuan teknologi terbesar manusia. Dengan adanya kecerdasan buatan, pekerjaan manusia menjadi lebih mudah. Kecerdasan buatan dapat menjadi faktor kemajuan dalam bidang kelistrikan, terutama dalam hal keamanan. Salah satu fungsi pengembangan kecerdasan buatan dalam Kesehatan dan Keselamatan Kerja (K3) adalah dalam mendeteksi bahaya, seperti mendeteksi tenaga kerja yang belum memakai Personal Protective Equipment (PPE) dengan menggunakan teknologi seperti Neural Network, Computer Vision, dan Object Recognition atau mendeteksi keadaan tanah yang akan digunakan untuk Grounding dengan Fuzzy Logic. Hal ini diharapkan dapat mengurangi risiko bahaya di lingkungan kerja

POSTURAL CONTROL IN CHILDREN BORN AT TERM ACCORDING TO THE ALBERTA INFANT MOTOR SCALE: COMPARISON BETWEEN SEXES

Introduction: acquisitions and changes in the motor and cognitive development of boys and girls are related not only to existing biological differences between both sexes, but also to socio-economic, cultural and family factors. Objective: to investigate the differences between sexes in the acquisition of anti-gravitational postures. Methods: the participants in this study were 638 children born at term (324 males and 314 females), from 0 to 18 months, coming from Infant Education Schools in the south of Brazil. The Alberta Infant Motor Scale (AIMS) was used to evaluate motor performance. Results: most of the evaluated children showed normal motor performance for their age (69.7%), with nonlinear development and plateaus in postural acquisition from 15 months. There were not significant differences (p>0.05) in motor performance between boys and girls from 0 to 18 months. Conclusion: motor development was similar between the sexes in the first months of life. However, throughout childhood, sociocultural differences and parents’ practices seem to influence differently the process of motor acquisition and development of skills, since children are exposed to experiences in conformity with sex expectations

Spinel and plagioclase peridotites of the Nain ophiolite (Central Iran): Evidence for the incipient stage of oceanic basin formation

The Nain ophiolites crop out along the western border of the central East Iran Microcontinent (CEIM) and consist of an ophiolitic mélange in which pargasite-bearing spinel and plagioclase mantle lherzolites are largely represented.Whole-rock and mineral chemistry data suggest that these rocks record the complex history of the asthenospheric and lithospheric mantle evolution. The spinel lherzolites have experienced low-degree (~5%) partial melting and contain clinopyroxenes with positive Eu anomalies (Eu/Eu⁎=1.10–1.48) suggesting that the partial melting occurred under oxidized conditions (fayalite–magnetite–quartz−0.8 to+1.3). The pargasite and coexisting clinopyroxene in these rocks are depleted in light rare earth elements (LREE) (mean chondrite-normalized CeN/SmN=0.045). The depleted chemistry of this amphibole reflects metasomatismduring interaction with H2O-rich subalkalinemaficmelts,most likely concurrentlywith or after the partial melting of the spinel lherzolites. The plagioclase lherzolites were subsequently formed by the subsolidus recrystallization of spinel lherzolites under plagioclase facies conditions as a result of mantle uprising, as evidenced by: (1) the development of plagioclase rims around the spinels; (2) plagioclase+orthopyroxene exsolution textures within some clinopyroxene grains; (3) an increase in plagioclase modal content coupled with an increase in modal olivine and a decrease in modal pyroxene and pargasite; (4) coincident decreases in Al, Mg, and Ni, and increases in Cr, Ti, and Fe in spinel, as well as decreases in Al and Ca, and increases in Cr and Ti in pyroxene and pargasite; and (5) the identical whole rock compositions of the spinel and plagioclase lherzolites, which rules out a magmatic origin for the plagioclase in these units. The Nain lherzolites have similar whole-rock and mineral geochemical compositions to subcontinental peridotites that are typically representative of Iberia-type rifted continental margins and ocean–continent transition zones (OCTZ), suggesting that they formed during the early stages of the evolution of the Nain oceanic basin. This means that the Nain lherzolites represent the Triassic–Jurassic western border of the CEIM or alternatively an associated OCTZ

Il “virus logico-linguistico” nella Scuola e nell’Università: come sconfiggerlo.

L’articolo parte da una premessa: la gravissima carenza logico-linguistica (LL), di cui soffrono percentuali altissime di studenti della Secondaria Superiore italiana, ha ormai prodotto (soprattutto nell’apprendimento delle materie scientifiche) livelli di degrado paragonabili agli effetti di un virus estremamente veloce nel diffondersi e virulento al punto tale da fare apparire irreversibili i danni di tutto ciò che raggiunge ed inquina; in particolare, fuor di metafora: Scuola ed anche Università, quest’ultima assai poco salvaguardata delle attuali protezioni. Ciò premesso l’articolo propone una metodologia fortemente innovativa [denominata “Studio Guidato” (SG)] che dimostra la reversibilità dei danni suddetti, a patto che si rinunci alla mentalità del difendersi per acquisire quella di un attacco frontale al virus, con forza superiore alla sua virulenza. Lo SG ha armi assai valide per farlo (strumenti metodologici da lungo tempo approntate) che intende utilizzare secondo tre direttrici di attacco: due orientate a colpire due difetti della didattica tradizionale (molto diffusi, ma anche abbastanza nascosti, sicchè di essi poco o nulla si parla) , la terza direttrice volta a convincere la classe docente (da tempo delusa per tanti motivi, tra cui quello di venire coinvolta da sempre in un volontariato che sembra non avere fine) che questa volta vale la pena partecipare. L’attacco è stato studiato, in una ricerca durata oltre sei anni, proprio a causa di quest’ultima direttrice, a lungo contrastata dai docenti per l’eccessivo stress a loro richiesto da una valutazione continua invero molto faticosa. Cinque lunghi anni per trovare il rimedio, poi di improvviso l’idea buona è venuta, nascosta in un ambito dall’apparenza utopistica: da lì l’abbiamo estratta dimostrandone, al contrario, la concreta sua realtà. Si chiama auto-correzione del proprio compito da parte di ciascuno studente: una sorta di uovo di Colombo che ha tenuto in scacco per un paio di anni la ricerca stessa, che poi l’ha reso distante anni-luce dall’utopia. Oggi lo consideriamo carta vincente di un progetto sperimentale mono-annuale che terrà fede al titolo di questo articolo

Analisi tecnico-economica di impianti per la cattura e lo stoccaggio di anidride carbonica con stoccaggio di energia termica

L’articolo riporta i risultati di uno studio per valutare tecnicamente ed economicamente l’integrazione tra un impianto supercritico a carbone, modellato sulla base del caso di studio prodotto dai report dell’IEA (Agenzia Internazionale Energia), con un impianto per lo stoccaggio di energia termica. Dopo un’analisi approfondita è stato scelto il sistema di stoccaggio ad oli diatermici. L’abbinamento di un sistema di stoccaggio di energia termica all’impianto CCS (Carbon Capture & Storage) permette di riportare la flessibilità, ossia la velocità di variazione nella produzione di energia elettrica, a livello degli impianti di generazione senza la sezione di cattura dell’anidride carbonica. Inoltre a seguito del calcolo del VAN (Valore Attuale Netto) seguendo i criteri di valutazione indicati dall’IEA, si evidenzia come per alcuni scenari del prezzo di vendita dell’energia elettrica e del carbone l’investimento risulti conveniente

DIGITALLY-ENABLED ADVANCED SERVICES: MANAGING THE JOURNEY FROM DATA TO VALUE

Purpose: this paper proposes a novel model to describe how data collected from smart connected products(SCP) should be managed to generate customer value through digitally-enabled advanced services (DEAS). Design/Methodology/Approach: literature integrative review and action research Findings: there are connections between the configuration of the service system designed to deliver DEAS, and the value (net benefits in terms of efficiency, efficacy and focus) that different customers expect. Originality/Value: the integration of literature on SCP, smart PSS, service science and sdl facilitates the understanding of mechanisms through which DEAS create customer value

Recycling of Wastes Deriving from the Production of Epoxy-Carbon Fiber Composites in the Production of Polymer Composites

The formulation of composites reinforced with shredded epoxy-carbon fibers wastes is investigated. Poly (buthylene terephthalate) PBT was selected as the matrix for the composites. In order to increase the interaction between the epoxy resin still coating the carbon fibers and the PBT matrix, polycarbonate (PC) was added either to the matrix formulation or as a waste coating. The flexural strength, impact strength, and dynamic-mechanical analysis of the new composites was investigated, as well as their microstructure by scanning electron microscopy. Experimental results show that the recycled fibers can be dispersed in both pure PBT and in its blend, enhancing the mechanical properties of the composites. An increase in the investigated properties is found specifically in the elastic modulus below 50 degrees C and in the impact strength. The extent of the increase depends on the obtained microstructure