Oinezkoen simulazioak giza indarraren ereduaren bidez: larrialdi-egoerak

Pedestrian areas such as underground stations or shopping centres are more often than not overcrowded. In case of emergency, the safety of pedestrians is called into question. As a matter of fact, the analysis of pedestrian flows is highly meaningful. This study is developed following the Social Force Model, a perspective on modelling of crowd dynamics and pedestrian motion. The mathematical formulation, fields of applications, limits and the relation with experimental data have been considered. Moreover, a simulated evacuation of a single-exit room has been analysed, together with the influence of obstacles in the event of an emergency evacuation procedure. It has been proven that placing a wall or a column with special features can help reducing the evacuation time because the obstacles tend to organize the flow. In addition replacing a long wall by a row of columns or small walls can even improve the results.; Oinezkoentzako inguruneetan, metroetako pasabideetan edo merkataritza-guneetan esaterako, jende ugari pilatzen da. Ibiltarien segurtasuna arriskuan ipintzen du horrek, bereziki larrialdi-egoeretan. Ondorioz, oinezkoen dinamika aztertzeak berebiziko garrantzia dauka. Lan honetan jendetzaren dinamika modelizatzen duen ereduetako bat landu da, giza indarraren eredua alegia. Besteak beste, eredu horren formulazio matematikoa, aplikagarritasun-esparruak, mugak eta datu esperimentalekiko erlazioa aztertu dira. Gainera, eredu horren bitartez irteera bakarreko gela baten ebakuazioa aztertu da, ibiltarien hustutze prozesuan oztopoek nola eragiten duten ikusteko. Ate ondoan ezaugarri bereziak dituen horma edo zutabe bat kokatzeak irtete-denbora murrizten duela egiaztatu da, oztopoek oinezkoen fluxua ordenatzen dutelako. Bestalde, horma luze baten ordez zutabeen edo horma txikien ilara bat eratu daiteke emaitzak are gehiago hobetzeko

Nanotermodinamika

This work presents a theory that goes beyond the scope of Classical Thermodynamics. It is named Nanothermodynamics, and it was created and developed by physicist Terrell Hill in the 1960s. In essence, it includes the necessary tools for the study of small systems, by means of a thermodynamic potential known as the subdivision potential. In fact, it enables the construction of the "nanocanonical" statistical ensemble, by introducing a distinctive degree of freedom related to its distribution of small systems. Through examples, we shall emphasize the importance of taking account of finite size effects in the nanothermodynamic region. With that being said, undergraduates taking a course on Thermodynamics and Statistical Mechanics will find it rewarding to understand and internalize the fundamentals of Nanothermodynamics. Even if it has remained abandoned and left aside for many years, Hill’s theory has nowadays proved useful to scientists of wide-ranging areas for the advancement of their research, such as in Chemical Physics and Biology.; Lan honetan, Termodinamika Klasikotik haratago doan teoria aurkeztuko dugu: Terrell Hill fisikariak 1960ko hamarkadan sortutako eta garatutako Nanotermodinamika. Funtsean, sistema txikien azterketarako nahitaezkoa den tresneria biltzen du, banatze-potentzial deritzon potentzial termodinamikoa dela medio. Hain zuzen, horrek ahalbidetzen du, besteak beste, banatzearekin lotutako askatasun-gradu berezia abian jartzeaz bat, multzo estatistiko nanokanonikoaren eraikuntza. Adibideen bidez, eskualde nanotermodinamikoan kasuan kasuko tamaina finituko efektuek duten esanguran sakonduko dugu. Horiek horrela, Termodinamika eta Fisika Estatistikoa irakasgaiko ikasleei arras aberasgarria gertatuko zaie, alde batetik, ohiko Termodina- mikaren irismenaz ohartzea, eta, bestetik, Nanotermodinamikaren nondik norakoak ulertzea eta barneratzea. Aipatzekoa da ezen urte luzez baztertuta egon bada ere, egun Hill-en teoria baliagarria gertatu zaiela hainbat esparrutako zientzialariei; esate baterako, kimika fisikoan eta biologian

MinervaLab: Jupyter Notebook-etan oinarritutako irakaskuntza-proiektu alternatiboa

Technologies and platforms developed during the last years offer several ways to implement interactivity-based educational projects and to create and publish educational material. The MinervaLab project, which is based in software development tools and workflows, contains interactive material aimed to teach Thermodynamics. Applications, their documentation and theoretical explanations are available for both students and developers (the project can be consulted in https://minervalab.readthedocs.io). An experimental group consisted of students has shown interest on the project and highlighted its usefulness.In the future, MinervaLab will be used to teach phase transitions and van der Waals mechanical equation of state.; Azken urtetan agertutako teknologia eta plataforma berriek ikasleen elkarrekintzan oinarritutako proiektuak garatzeko eta irakaskuntzarako beharrezkoa den materiala sortzeko eta hedatzeko bide ugari eskaintzen dute. MinervaLab proiektuak Jupyter Notebook plataforman eta softwarearen garapenean erabili ohi diren tresna eta lan-fluxuetan oinarritutako Termodinamikaren inguruko material interaktiboa jasotzen du. Garatutako aplikazioak dokumentatuta eta azalpen teorikoz lagunduta aurkezten dira, material guztia ikasle zein garatzaileentzat eskuragarri ipiniz (proiektu guztia https://minervalab.readthedocs.io helbidean kontsulta daiteke). Egindako lanarekiko interes handia azaldu eta eskola emateko erabilgarria dela azpimarratu du ikaslez osatutako talde esperimentalak. Etorkizunean, MinervaLab proiektua fase-trantsizioen eta van der Waals-en egoera-ekuazio mekanikoaren inguruko eskolak emateko erabiliko da

Prozesu estokastikoak fisikan eta ekonomian: higidura browndarretik finantza-merkatuen ereduetara

rket behaviour. In fact, the universality of some simple statistical characteristics in the markets is noticeable: several financial variables (such as the probability distributions of stock returns) show scale invariance. These scale-free phenomena are relevant to different areas of physics.Thus, for physicists, economic research has become the study of a wealth of data on a well-defined complex system. One of the most important analysis methodologies is based on the use of stochastic processes. In fact, in the case of some complex physical systems with universal characteristics, deterministic models are not useful. From the parallelism between both areas, therefore, it would be fair to introduce the stochastic approach in the economic field and thus, model a stochastic market. In other words, it is possible to create independently a physical model and an economic model, using the same mathematical concept.; Azken hamarkadetan, ikerkuntza-talde anitzek, fisikan garatutako metodoak erabili dituzte merkatuen portaera aztertzeko. Izan ere, merkatuetako ezaugarri estatistiko sinple batzuen unibertsaltasuna nabarmena da: eskala-menpekotasunik gabeko fenomenoak antzeman daitezke (itzulkinen probabilitate-banaketetan, adibidez), fisikako hainbat esparrutan agertzen diren gisan. Hala, fisikarientzat, ekonomia ikertzea, ongi definitutako sistema konplexu bati buruzko datu ugari aztertzea bilakatu da. Aztertze-metodologia garrantzitsuenetariko bat, adibidez, prozesu estokastikoak erabiltzean datza. Izan ere, fisikan, ezaugarri unibertsalak dituzten sistema konplexu batzuen kasuan, eredu deterministak ez dira baliagarriak. Bi esparruen arteko paralelismotik, hortaz, ikuspegi estokastikoa ekonomiaren esparruan sartzea, eta merkatu estokastiko bat ereduztatzea zilegi litzateke. Hau da, kontzeptu matematiko beraz baliatuz, posible da eredu fisiko eta ekonomiko bat independenteki sortzea

NPG–TRIS Thermal Storage System. Quantification of the Limiting Processes: Sublimation and Water’s Adsorption

The NPG–TRIS binary system (NPG = (CH3)2C(CH2OH)2 = 2,2-dimetyl-1,3-propanodiol; TRIS = NH2C(CH2OH)3 = 2-Amino-2-(hydroxymethyl)-1,3-propanediol) was intensively investigated as a thermal energy storage system, due to the reversibility of its phase transitions and their associated energy. An adapted methodology was applied to precisely quantify its sublimation tendency. Relevant thermochemical data were revisited and evaluated using some specific experimental procedures. We also determined that the widely accepted requirement of working in an inert atmosphere to avoid deviations due to hygroscopicity is not necessary. Nevertheless, to take advantage of the energetic properties of the NPG–TRIS system, closed containers will be required to avoid NPG losses, due to its quantitatively determined high sublimation tendency.This study was financially supported by the Basque Government (IT1301-19, IT1364-19) and through the Elkartek18 R&D program, by the University of the Basque Country UPV/EHU (GIU19/019), and by the Ministry of Science and Innovation of Spain (PID2019-106644GB-I00

Larmor-en prezesioa kristaletan gertatzen diren aldaketen detektagailu

Material batean gertatzen diren trantsizio magnetikoen eta haren egitura kristalinoaren arteko erlazioa aztertzea oso garrantzitsua da, batik bat multiferroikoak diren materialetan. Gehienetan, trantsizio magnetikoetan gertatzen diren egiturazko al-daketak gako dira trantsizioan agertzen edo desagertzen den polarizazio elektrikoaren jatorria zein den ulertzeko. Hala ere, hainbat materialetan aldaketa horiek oso txikiak dira eta horiek detektatzea oso zaila izan daiteke. Hori da aztergai dugun materialean (MnWO4) gertatzen dena. Hori dela eta, ondorio zuzenetara heltzekotan, ezinbestekoa da kristalaren egitura ikertzeko teknika oso sentikorrak erabiltzea. Egiturazko aldaketa oso txikiak aztertzeko neutroien prezesioaz baliatzen den teknika aurkeztuko dugu lan honetan, neutroien bidezko Larmor-en difrakzioa, hain zuzen ere. Nahiz eta lortutako emaitzak behin-behinekoak izan, oso argi ikusten dira zein diren teknika honen indarra eta potentzia, eta trantsizio magnetikoetan gertatzen diren egiturazko aldaketak; The study of the interplay between magnetic transitions and the crystal structure is crucial for the investigation of multiferroic materials. In fact, the structural changes across the magnetic transitions are usually the clue to ascribe the origin of the concomitant appearance of electric polarization. Nevertheless, in some materials, those structural variations are so small that their detection is very difficult. That is the case of MnWO4. Hence, in order to reach appropiate conclusions we need to use experimental techniques which are very sensitive to crystal structure variations. In this piece of work we present an experimental technique that takes profit of the precession of the neutrons in magnetic fields in order to see those small changes in the crystallographic structures, that is, the Larmor diffraction by means of neutrons. Even if the obtained results are rather preliminary, the undoubtedly show the strength and power of this technique and the modifications of the structure across the magnetic transitions

Bateria-multzoen simulazio elektrotermikoak: 14S5P bateria-multzo komertziala

Electrothermal behaviour of 14S5P battery-pack, usually placed in small electric vehicles, is analysed for the first time using multiphysics simulations. An electrochemical model is developed to describe the electric behaviour of LMO 26650 battery (3.5 Ah). NMC active material is added in the LMO cathode (0, 29, and 59 % wt) to check the improvement of the electrical performance of the battery. The heating process of LMO 26650 battery is simulated in a high intensity discharge process (10 A). As a result, the temperature of the cell suffers an important increment of 64 %. Finally, with intensities of usual working conditions, the temperature of 14S5P battery-pack does not increase remarkably.; Normalean ibilgailu elektriko txikietan erabiltzen den 14S5P bateria-multzoaren jokaera elektrotermikoa lehenengo aldiz aztertu dugu simulazio multifisikoen bidez. LMO kimikako 26650 bateriaren (3,5 Ah) jokaera elektrikoa simulatzeko eredu elektrokimikoa garatu dugu. LMOko katodoan NMC material aktiboa gehitu dugu (pisuan, % 0, % 29 eta % 59), bateriaren ezaugarri elektrikoak hobetzen direla egiaztatzeko. LMO kimikadun 26650 bateriaren beroketa simulatu dugu intentsitate altuko deskarga batean (10 A), eta tenperatura % 64 igotzen dela behatu dugu. Azkenik, ohiko lan-baldintzetako korronteetan, 14S5P bateria-multzoaren tenperatura ez dela era nabarmenean handitzen frogatu dugu

Raman Scatering de CS₂SEO₄ A 20 K

CS₂SEO₄ es miembro de la familia de compuestos A₂BX₄ que tiene como prototipo a K₂Se0₄ perteneciente al grupo espacial Pnam a temperatura ambiente. En esta comunicación discutimos su espectro Raman polarizado a 20 K. Los fonones de los modos de estiramiento, entre 800 cm-1 y 430 cm-1, tienen similares características a las del prototipo a temperatura ambiente. En particular, se pondrá énfasis en las disímiles secciones eficaces de distintos modos que aún no perteneciendo a las especies permitidas aparecen en los espectros con intensidad dominante. La región espectral de los fonones de la red, entre 0 cm-1 y 150 cm-1, revela que si bien el número de bandas para las especies Ag, B2g, B3g están de acuerdo con lo estimado por la teoría de grupos para la especie B/g solo hay dos bandas fuertes, y una serie de modos extremadamente débiles y de origen cuestionable, de las siete predichas para el grupo espacial Pnam. Nuestros resultados también confirman la ausencia de transiciones de fase en este compuesto hasta 20 K.Facultad de Ciencias Exacta

Crystallographic at non-ambient conditions and physical properties of the synthesized double-perovskites Sr2(Co1-xFex)TeO6

Polycrystalline double perovskite-type Sr2(Co1-xFex)TeO6 with various stoichiometric compositions (x = 0, 0.25, 0.5, 0.75, and 1) were synthesized by solid-state reactions in air. The crystal structures and phase transitions of this series at different temperature intervals were determined by X-ray powder diffraction, and from the obtained data the crystal structures were refined. It has been proven that for the compositions x = 0.25, 0.50, and 0.75 the phases crystallize at room temperature in the monoclinic space group I2/m. Down to 100 K, depending on the composition, these structures experience a phase transition from I2/m to P21/n. At high temperatures up to 1100 K their crystal structures show two further phase transitions. The first one is a first-order phase transition, from monoclinic I2/m to tetragonal I4/m, followed by a second-order phase transition to cubic Fm3 @#x0305;m. Therefore, the phase transition sequence of this series detected in a temperature range from 100 K to 1100 K is: P21/n → I2/m → I4/m → Fm3 @#x0305;m. The temperature-dependent vibrational features of the octahedral sites were investigated by Raman spectroscopy, which furthermore complements the XRD results. A decrease of the phase-transition temperature with increasing iron content has been observed for these compounds. This fact is explained by the progressive diminishing of the distortion of the double-perovskite structure in this series. By means of room-temperature Mössbauer spectroscopy, the presence of two iron sites is confirmed. The two different transition metal cations Co and Fe on the B sites give the opportunity to explore their effect on the optical band-gap