Academic literature on the topic 'Points de contacts quantiques'
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Journal articles on the topic "Points de contacts quantiques"
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Osama Shaalan, Omar. "Evaluation of Matrix Band Systems for Posterior Proximal Restorations among Egyptian Dentists: A Cross-Sectional Survey." Acta Stomatologica Croatica 54, no. 4 (December 15, 2020): 392–400. http://dx.doi.org/10.15644/asc54/4/6.
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Objectives: This study aimed to investigate the techniques of matricing used by Egyptian dentists, and evaluate the influence of these techniques on the reproduction of optimum proximal contacts for posterior proximal resin composite restorations. Material and methods: An online questionnaire was developed and sent to 785 dentists via e-mail and social media platforms. The survey asked the participants about the following: the highest academic degree achieved and their experience, techniques of matricing used, brands of matricing systems used, assessment of proximal contact points, their evaluation of the contact points they reproduced, and their assessment of the restorations’ emergence profiles. Results: A total of 415 dentists participated in the study (response rate 52.8%). 308 dentists (74%) preferred using the sectional matrix system, while 107 dentists (26%) preferred using the circumferential matrix system. One hundred twenty-six dentists (31%) reported that the circumferential matrix systems reproduced optimum contacts, 105 dentists (25%) reported tight contacts and 184 dentists (44%) reported open contacts. However, for the sectional matrix systems, the optimum contacts were reported by 279 dentists (67%) tight contacts by 109 dentists (26%) and open contacts by 27 dentists (7%). There was a statistically significant difference between the sectional matrix systems and the circumferential matrix systems regarding the tightness of the proximal contact points (P<0.0001). Conclusions: Egyptian dentists preferred using the sectional matrix systems. The survey indicated that optimum contact points were highly associated with the sectional matrix systems, while poor (open and tight) contacts were highly associated with the circumferential matrix systems.
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Semprini, Massimiliano. "The points of contacts between academics and professionals." FINANCIAL REPORTING, no. 2 (September 2017): 61–65. http://dx.doi.org/10.3280/fr2017-002006.
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Some argue that the ultimate purpose of accounting research should be to improve accounting practice, rather than simply to describe or understand or critique it. Hence a gap appears to have emerged between practitioners and academics with regards to accounting research. In order to exploit as better as possible the output of the accounting research performed by academic researchers, the accounting profession should create a point of contact; auditing networks might facilitate this link. On the other hand, research performed by academics should become "understandable" by practitioners using a different jargon and simple mathematical formulas.
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Guevara Reyes, Janet. "Clinical application of digitalization of occlusal contacts with dental scanner." Jaw Functional Orthopedics and Craniofacial Growth 2, no. 2 (November 1, 2022): 56–63. http://dx.doi.org/10.21595/jfocg.2022.22789.
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This study aimed to evaluate the number, intensity and position of occlusal contact points in a case of mesiocclusion, hyperdivergence, with open bite. An occlusal record was taken from a patient with anterior and lateral open bite mesiocclusion, using the Planmeca Esmerald S intraoral scanner in maximum intercuspation. The intensity of the occlusal contact was analyzed with the software 3shape Ortho Analyzer Orthodontics, using the Occlusion Map module, through the 3D Color Map tool, with a 0.5 mm virtual articular paper. These results were compared to the occlusal support points defined by Planas [10]. The interpretation of the data obtained was made by assessing the interocclusal intensity of the contact points, number of contacts and position during three different moments (1S, 2S, 3S) in the record taking process. The chromatic scale of the Color Map is: red, orange, yellow, green and blue. To identify the occlusal contact points in digital, they are shown in red points when full contact occurs, while minimum contact is shown in blue. We evaluated the number of teeth with interocclusal contacts. It was determined that having the appropriate number of contacts does not imply that they are in the correct position. In addition, the method suggests reliability in the filing and record keeping of occlusal contacts. By identifying intensity, number and position of the occlusal support point we can objectively record interocclusal alterations.
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Lin, Kaifeng Lisa, LeShara M. Fulton, Matthew Berginski, Michelle L. West, Nicholas A. Taylor, Timothy P. Moran, James M. Coghill, Bruce R. Blazar, James E. Bear, and Jonathan S. Serody. "Intravital imaging of donor allogeneic effector and regulatory T cells with host dendritic cells during GVHD." Blood 123, no. 10 (March 6, 2014): 1604–14. http://dx.doi.org/10.1182/blood-2013-09-526020.
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Key Points Allogeneic donor T cells establish stable contacts with dendritic cells in lymph nodes immediately (2 hours) after they are transplanted. Endogenous Tregs disrupt stable contacts between T cells and DCs, which are interleukin-10 dependent.
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Wilkens, Jens, Hans Thulesius, Eva Arvidsson, and Björn Ekman. "Evaluating the effect of digital primary care on antibiotic prescription: Evidence using Swedish register data." DIGITAL HEALTH 9 (January 2023): 205520762311562. http://dx.doi.org/10.1177/20552076231156213.
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Background The growing use of digital primary care consultations has led to concerns about resource use, equity and quality. One of these is how it affects antibiotic prescription. Differences in ease of access for patients and available diagnostic information for the prescribing physicians are reasons to believe prescription rates may be affected. Objectives We estimated differences in antibiotic prescription between traditional office-based and digital contacts, if these differences varied between groups of diagnoses depending on the availability of information for the prescribing physician, and if differences were associated with socio-demographic patient characteristics. Methods Using individual level register data for a sample of patients diagnosed with an infection over a two-year period, we estimated differences in prescription between the two types of contacts and applied propensity score techniques to mitigate possible problems with treatment selection bias. Results The share of antibiotic prescription was 28 (95% CI 27–30, p < 0.001) to 33 (95% CI 29–36, p < 0.001) percentage points lower among digital contacts as compared to office-based contacts. For urinary tract infections, the differences in prescription rates between the two contact types were smaller (34 to 41 percentage points difference) than for throat and skin infections (50 to 60 percentage points difference). For women, rural, older, and people born outside Sweden, digital contacts were associated with higher prescription rates. Conclusions Antibiotic prescription rates were significantly lower for digital contacts compared with office-based contacts. The findings suggest that digital primary care may be an effective alternative to in-person visits without undue consequences for antibiotic prescription levels, although to varying degree depending on diagnosis.
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Adams, Josephine Clare. "Regulation of protrusive and contractile cell-matrix contacts." Journal of Cell Science 115, no. 2 (January 15, 2002): 257–65. http://dx.doi.org/10.1242/jcs.115.2.257.
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The extracellular matrix is vital for tissue organisation in multicellular organisms. Cells attach to the extracellular matrix at discrete points on the cell surface, termed cell-matrix contacts. In general molecular terms, these contacts are assembled from large multiprotein complexes. However, many forms of matrix contacts can be distinguished by microscopy or by biochemical criteria, and these fulfil a diverse range of roles associated with cell adhesion, guidance, migration, matrix assembly, differentiation and survival. Two major functional categories are the protrusive and contractile matrix contacts. I describe contexts for the formation of protrusive or contractile contacts and discuss recent information on the molecular processes by which these contacts are specified, coordinated and regulated at a cellular level.
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Al-Rayes, Naim Z., and Mohammad Y. Hajeer. "Evaluation of Occlusal Contacts among Different Groups of Malocclusion using 3D Digital Models." Journal of Contemporary Dental Practice 15, no. 1 (2014): 46–55. http://dx.doi.org/10.5005/jp-journals-10024-1486.
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ABSTRACT Objectives (1) To evaluate the applicability of using 3D digital models in the assessment of the magnitude of occlusal contacts by measuring occlusal contact surface areas (OCSAs) and 3D mesh points in ‘contact’ (OCMPs) in a sample of orthodontic patients; (2) To detect any sex differences in the magnitude of occlusal contacts in all malocclusion groups; (3) To detect intergroup differences; (4) To assess possible correlations between occlusal contacts and other dental characteristics. Materials and methods Study casts of 120 malocclusion patients were selected and divided into 4 groups (class I division 1, class II division 1, class II division 2, class III) with equal numbers for both sexes. 3D digital models were produced using O3DM™ technology. Occlusal contacts were quantified using two methods of measuring. Results (1) No significant sexual differences were detected for OCMPs (mesh points) and OCSAs (mm2) in all groups. (2) There were statistically significant differences among malocclusion groups for OCMPs and OCSAs (p < 0.001). Tukey's HSD posthoc tests showed that class III patients had significantly less occlusal contacts than other malocclusion groups. (3) Stepwise multiple regression equations showed that overjet, lower arch width and overbite could explain approximately 19.5% of the total variance of OCSAs and OCMPs. Conclusion Sexual differences in occlusal contacts were not detected. Class I division 1 patients had the highest amount of occlusal contacts among all groups of malocclusion. Overjet, overbite and lower dental arch width were best predictors of occlusal contacts in the current sample. How to cite this article Al-Rayes NZ, Hajeer MY. Evaluation of Occlusal Contacts among Different Groups of Malocclusion using 3D Digital Models. J Contemp Dent Pract 2014;15(1):46-55.
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Alimi, Dervish. "MISSION CONTACT POINTS BETWEEN ANTIQUE AND SLAVICISM." International Journal of Applied Language Studies and Culture 2, no. 1 (March 31, 2019): 1–4. http://dx.doi.org/10.34301/alsc.v2i1.12.
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The questions are: Where are the ‘footprints’ of the ancient Macedonian Macedonians’ toponyms and vocabulary, remaining in the linguistic-semantic fund that would witness the continuity of historical development and transformation, respectively, the “antico-Slavic mixing” that has been widely claimed by some Macedonian historian? “What are the remaining words of the ancient Macedonian heritage, even of the language of the old Greeks old neighbors who would testify to their every day contacts?”, when we see that today’s vocabulary fund of the Macedonian language is strictly Slavic, except for Turkish and Bulgarian-Serbian borrowings and the modern inflows of internationalisms and technicalities? Where are the old ancient Macedonian words which the Macedonian Slavic language today inherited, however few were they ?! The ancient language dictionary of the ancient Macedonian tribe should have definitely left a mark on today’s Macedonian language vocabulary, as they have left the mark of the old Anglo-Saxon in today’s English language or the language of Old Gallons in the French language today. This is the fact of the missing points of contacts between these two cultures, among others....
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Kawase, Taro. "Three weak points in electrical installations. Contacts, connections and capacitors." IEEJ Transactions on Industry Applications 107, no. 9 (1987): 1088–91. http://dx.doi.org/10.1541/ieejias.107.1088.
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Matveevsky, Sergey, Irina Bakloushinskaya, Valentina Tambovtseva, Maret Atsaeva, Tatiana Grishaeva, Aleksey Bogdanov, and Oxana Kolomiets. "Nonhomologous Chromosome Interactions in Prophase I: Dynamics of Bizarre Meiotic Contacts in the Alay Mole Vole Ellobius alaicus (Mammalia, Rodentia)." Genes 13, no. 12 (November 23, 2022): 2196. http://dx.doi.org/10.3390/genes13122196.
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Nonhomologous chromosome interactions take place in both somatic and meiotic cells. Prior to this study, we had discovered special contacts through the SYCP3 (synaptonemal complex protein 3) filament between the short arms of nonhomologous acrocentrics at the pachytene stage in the Alay mole vole, and these contacts demonstrate several patterns from proximity to the complete fusion stage. Here, we investigated the nonhomologous chromosome contacts in meiotic prophase I. It turned out that such contacts do not introduce changes into the classic distribution of DNA double-strand breaks. It is noteworthy that not all meiotic contacts were localized in the H3k9me3-positive heterochromatic environment. Both in the mid zygotene and in the early–mid diplotene, three types of contacts (proximity, touching, and anchoring/tethering) were observed, whereas fusion seems to be characteristic only for pachytene. The number of contacts in the mid pachytene is significantly higher than that in the zygotene, and the distance between centromeres in nonhomologous contacts is also the smallest in mid pachytene for all types of contacts. Thus, this work provides a new insight into the behavior of meiotic contacts during prophase I and points to avenues of further research.
Dissertations / Theses on the topic "Points de contacts quantiques"
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Zimmermann, Katrin. "Contacts ponctuels quantiques dans le graphène de haute mobilité." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY008/document.
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Dans le régime de l'effet Hall quantique, les porteurs de charge se propagent le long de canaux unidimensionnels situés au bords d'un gaz d'électron bidimensionel (2D electron gas, 2DEG). Un contact ponctuel quantique (quantum point contact, QPC) - une constriction étroite confinant spatialement le gaz électronique - permet de contrôler la transmission de ces canaux de bords. Dans un 2DEG conventionnel, une tension négative appliquée sur les grilles électrostatiques du QPC engendre la déplétion locale du gaz électronique sous la grille, forçant les électrons à se propager au travers de la constriction. Cependant, dans le graphène, du fait de l'absence de bande interdite, une tension négative provoque la transition continue du dopage d'électrons à trous. Dans le régime de l'effet Hall quantique, électrons et trous se propagent le long de l'interface p-n dans la même direction, et la diffusion inélastique induit un transfert de charge et du mélange entre eux.Au cours de cette thèse, nous avons fabriqué des dispositifs à base de graphène encapsulé dans deux feuillets de hBN, et munis de grilles électrostatiques définissant un QPC. Nous avons étudié l'effet du QPC sur la propagation des canaux de bords entiers et fractionnaires de l'effet Hall quantique, et sur le mélange entre eux. Dans l'effet Hall quantique, nous avons démontré que les canaux entiers et fractionnaires peuvent être contrôlés et sélectivement transmis au travers de la constriction. Du fait de la haute mobilité de nos structures, et de la levée de dégénérescence complète des niveaux de Landau qui en résulte à fort champ magnétique, l'équilibrage à l'interface p-n est réduit aux sous-niveaux de même spin et au niveau de Landau N=0.Un QPC dans le régime de l'effet Hall quantique constitue également un système idéal pour l'étude de l'effet tunnel des porteurs de charge entre canaux de bords fractionnaires, unidimensionnels et fortement corrélés, se propageant dans des directions opposées, décrits par la théorie de Tomonaga-Luttinger. Nous avons étudié l'effet tunnel entre canaux de bords fractionnaires dans notre structure muni un QPC, en nous concentrant sur l'état fractionnaire 7/3 et la dépendance en température de ses propriétés tunnelsIn the quantum Hall regime, the charge carriers are conducted within one-dimensional channels propagating at the edge of a two-dimensional electron gas (2DEG). A quantum point contact (QPC) – a narrow constriction confining spatially electron transport – can control the transmission of these quantum Hall edge channels. In conventional 2DEG systems, a negative voltage applied on the electrostatic split gates depletes locally the electrons underneath them forcing the electrons to pass through the constriction. In contrast, due to the absence of a band gap in graphene, a negative gate voltage induces a continuous shift of the doping from electrons to holes. In the quantum Hall regime, electron and hole edge channels propagate along the pn-interface in the same direction while inelastic scattering induces charge transfer and mixing between them.In this PhD thesis, we have fabricated ballistic graphene devices made by van der Waals stacking of hBN/Gr/hBN heterostructures, and equipped with split gates forming a quantum point contact (QPC) constriction. We have studied the effect of the QPC on the propagation of integer and fractional quantum Hall edge channels and the mixing among them. In the quantum Hall regime, we demonstrate that the integer and fractional quantum Hall edge channels can be controlled and selectively transmitted by the QPC. Due to the high mobility of our devices and the resultant full lifting of the degeneracies of the Landau levels in strong magnetic field, equilibration at the pn-interface is restricted to sublevels of identical spins of the N=0 Landau level.A QPC in the quantum Hall regime offers also an ideal system to study the tunnelling of charge carriers between counter-propagating fractional edge channels of highly correlated, one-dimensional fermions described by the theory of Tomonaga-Luttinger. We study the tunnelling between fractional quantum Hall edge channels in our QPC device in graphene and focus on the 7/3-fractional state to explore the temperature dependence of tunnelling characteristics
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Seoudi, Tarek. "Non-intrusive CdSe-based quantum dots for sensing pressure and temperature in lubricated contacts." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI009.
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Cette thèse est dédiée à la mesure des pressions et des températures locales et à la comparaison de la génération de chaleur dans les contacts élastohydrodynamiques (EHD) de type tout acier et hybride (nitrure de silicium-acier). Le but ultime de ce travail est de développer une nouvelle technique in situ non-intrusive, exploitant la sensibilité de la photoluminescence (PL) des boîtes quantiques (QDs) de CdSe/CdS/ZnS aux variations de pression et température, afin de cartographier ces deux paramètres dans les contacts EHD. Dispersible à faible concentration dans les lubrifiants, il est montré que les QDs ne modifient pas le comportement rhéologique du fluide porteur et que le cisaillement n’est pas perturbateur à la réponse en PL. La calibration des QDs en suspension confirme la dépendance de la réponse en PL des QDs à la pression et à la température. Les mesures in situ sont effectuées en utilisant un banc d’essai bille-disque. La comparaison entre les mesures in situ de pression et de température et celles prédites à l'aide d'un modèle éléments finis TEHD interne montre une bonne concordance, ce qui démontre la faisabilité de la méthodologie proposée. Les effets du glissement et du chargement normal sur la pression, la température et la chaleur générée sont reportés. L’effet des propriétés thermiques des solides est souligné et la répartition de la chaleur générée entre les solides en contact est étudiée. L'équilibre énergétique entre l'énergie mécanique et l'énergie thermique interne générée par compression et cisaillement est démontré en comparant les pertes de puissance expérimentales et la chaleur générée issue du modèle numérique, pour des contacts acier-acier et hybridesThis thesis is dedicated to the measurement of local pressure and temperature and to compare the heat generation in all-steel and silicon nitride-steel (hybrid) elastohydrodynamic (EHD) contacts. The ultimate goal of this work is to develop a new non-intrusive in situ technique, exploiting the sensitivity of the photoluminescence (PL) of CdSe/CdS/ZnS quantum dots (QDs) to pressure and temperature. Dispersible in small concentration in lubricants, it is shown that the QDs doesn’t modify the rheological behavior of the carrier fluid and that shearing is not perturbative to the QDs PL response. The calibration of QDs in the suspension confirms the QDs PL dependence on temperature and pressure. The in situ measurements were conducted in EHD contacts using a ball-on-disc test rig. Comparisons between pressure and temperature measurements and predictions, using an in–house finite element thermal EHD model, showed a good agreement which demonstrates the feasibility of the proposed methodology. The effects of sliding and normal loading on pressure, temperature and heat generation are indicated. The effect of the thermal properties of the solid materials is underlined and the partition of the generated heat between the contacting solids is investigated. The energy equilibrium between the mechanical energy and the internal thermal energy generated by compression and shearing is demonstrated by comparing experimental power losses and numerical heat generation, in steel-steel and hybrid contacts
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Szewc, Wojciech. "Theory and simulation of scanning gate microscopy : applied to the investigation of transport in quantum point contacts." Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-00876522.
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This work is concerned with the theoretical description of the Scanning Gate Microscopy (SGM) in general and with solving particular models of the quantum point contact (QPC) nanostructure, analytically and numerically. SGM is an experimental technique, which measures the conductance of a nanostructure, while a charged AFM tip is scanned above its surface. It gives many interesting results, such as lobed and branched images, interference fringes and a chequerboard pattern. A generally applicable theory, allowing for unambiguous interpretation of the results, is still missing. Using the Lippman-Schwinger scattering theory, we have developed a perturbative description of non-invasive SGM signal. First and second order expressions are given, pertaining to the ramp- and plateau-regions of the conductance curve. The maps of time-reversal invariant (TRI) systems, tuned to the lowest conductance plateau, are related to the Fermi-energy charge density. In a TRI system with a four-fold spatial symmetry and very wide leads, the map is also related to the current density, on any plateau. We present and discuss the maps calculated for two analytically solvable models of the QPC and maps obtained numerically, with Recursive Green Function method, pointing to the experimental features they reproduce and to the fundamental difficulties in obtaining good plateau tuning which they reveal.
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Lamouche, Guy. "Propriétés optiques des semiconducteurs, impuretés et points quantiques." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21480.pdf.
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Lachance-Quirion, Dany. "Étude par transport électrique de points quantiques colloïdaux." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29510/29510.pdf.
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Dionne, Patrice. "Biofonctionnalisation de points quantiques pour le suivi de récepteurs synaptiques." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/28940/28940.pdf.
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La membrane cellulaire est un environnement très dynamique où diffusent plusieurs familles de protéines. Pour assurer la communication entre neurones, certains récepteurs membranaires diffusant librement doivent être stabilisés aux jonctions de communication neuronales: les synapses. Des changements dans le comportement diffusif de ces récepteurs induisent des variations de leurs populations à la synapse. La capacité d’observer ces protéines diffuser individuellement est donc importante pour mieux comprendre certains mécanismes cellulaires associés au fonctionnement du système nerveux.
Alors que les fluorophores organiques (Alexa, Atto,…) et génétiquement encodées (GFP, RFP,…) photoblanchissent rapidement, les nanocristaux semi-conducteurs fluorescents (points quantiques: QDs) sont photo-stables, ce qui permet de suivre les protéines marquées sur de plus longues périodes. Même si la structure cristalline du QD dépasse rarement les 10nm de diamètre, la taille de la sonde fonctionnalisée, une fois équipée d’un enrobage hydrophile et de protéines d’hameçonnage, est d’environ 30 nm, limitant leur accessibilité dans la fente synaptique (environ 20 nm). De plus, la multivalence des versions commerciales des QDs fonctionnalisés pose problème, en leur permettant de lier plusieurs récepteurs à la fois.
Dans ce mémoire, nous présentons donc différentes approches pour la biofonctionnalisation de petit QDs monovalents, ainsi que les principales stratégies pour marquer des récepteurs synaptiques uniques à partir de QDs. De plus, nous présentons une étude de la diffusion de récepteurs synaptiques diffusant à l’intérieur et à l’extérieur de synapses et comparons les résultats en fonction des 2 types de sondes utilisés : QDs enrobés d’anticorps et QDs enrobés de streptavidine. Ces travaux devraient contribuer à l’optimisation d’une approche pour suivre les dynamiques des récepteurs synaptiques dans des modèles de plasticité synaptique.
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Sauret, Olivier. "Transport de spin dans des points quantiques et information quantique." Université Joseph Fourier (Grenoble), 2004. http://www.theses.fr/2004GRE10191.
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Cette thèse se situe dans le domaine de la nanoélectronique appliquée à l'information quantique. Le vecteur de l'information est ici le spin de l'électron manipulé et contrôlé dans les circuits comportant un ou plusieurs points quantiques. Grâce au blocage de Coulomb, les points quantiques permettent le passage des électrons, et donc des spins, un par un. La première partie de cette thèse développe les méthodes d'étude théorique de circuits à base de points quantiques. Les équations maîtresses quantiques permettent de déterminer l'évolution d'un système via celle de sa matrice densité. Elles permettent notamment d'obtenir les propriétés de courant moyen et de corrélations de courant entre deux points du circuit. On insiste également sur le bruit de courant résolu en spin, qui permet notamment de distinguer les corrélations coulombiennes introduites par la répulsion entre les électrons dans un point quantique, et les corrélations dues au principe d'exclusion de Pauli. Ces méthodes sont appliquées dans la seconde partie à des dispositifs proposant de réaliser des opérations élémentaires de l'information quantique. Un dispositif formé d'un supraconducteur couplé à deux points quantiques permet de créer une paire d'électrons intriqués par le spin. Les corrélations de courant et de spin s'y avèrent particulièrement instructives et complémentaires. Un protocole de téléportation du spin est ensuite proposé. Le fonctionnement du système en régime de téléportation est en principe autocontrôlé par interaction coulombienneThis thesis applies nanoelectronics to quantum information. Electron spin is used to carry information. It is controlled and manipulated in nanocircuits with one more quantum dots. Because of Coulomb blocade quantum dots allow the transport one by one of electrons (or spins). The first part of this thesis develops theoretical methods to study nanocircuits with quantum dots. Quantum master equations describes the evolution of a system by the evolution of its density matrix. From them, one can get average current and current correlation between two points of the circuits. We particularly insist on spin-resolved current noise, which allows to distinguish coulombian correlation introduced by repulsion between electrons and correlations due to pauli principle. These methods are applied in the second part to devices aimed at performing elementary operations for quantum information. A device, composed of one superconductor coupled to two information. A spin-teleportation protocol is then proposed. The correspondong device is in principle autocontrolled by coulombien interaction
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Choi, Deung Jang. "Effet Kondo et détection d'un courant polarisé en spin dans un point de contact quantique." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00862415.
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L'effet Kondo observé dans des objets individuels constitue un système modèle pour l'étude de corrélations électroniques. Ces dernières jouent un rôle moteur dans le domaine émergent de l'électronique de spin (ou spintronique) où l'utilisation d'atomes issus des terres rares et des métaux de transition est incontournable. Dans ce contexte, l'étude de l'interaction d'une impureté Kondo avec des électrodes ferromagnétiques ou avec d'autres impuretés magnétiques peut donc s'avérer fondamental pour la spintronique. L'effet Kondo est sensible à son environnement magnétique car en présence d'interactions magnétiques la résonance ASK se dédouble. Dans une certaine mesure, la résonance ASK agit comme un niveau atomique discret doublement dégénérée qui subit un dédoublement Zeeman en présence d'un champ magnétique ou plus généralement d'un champ magnétique effectif. Inversement, la détection d'un dédoublement Zeeman indique l'existence d'un champ magnétique. Dans une boîte quantique, le couplage de la boîte avec les deux électrodes est faible en général et la largeur de la résonance ASK est donc de l'ordre de quelques meV. Beaucoup d'études de l'effet Kondo en présence d'interactions magnétiques ont été menées sur les boîtes quantiques, grâce notamment au contrôle qui peut être exercé sur la résonance ASK, mais aussi grâce au faible élargissement de la résonance qui peut alors être dédoublée avec un champ magnétique de l'ordre de 10 Tesla ou moins. A ces études, s'ajoutent de nombreux travaux similaires menés avec des dispositifs tels des jonctions cassées comprenant une molécule individuelle jouant le rôle de l'impureté magnétique. En revanche, peu d'études de ce type ont été consacrées aux atomes individuels. Cela est dû à l'hybridation plus marquée entre l'impureté atomique et la surface comparée aux boîtes quantiques, qui entraine une largeur typique de 10 meV ou plus pour la résonance ASK. Un champ magnétique d'environ 100 T ou plus est alors nécessaire afin de dédoubler la résonance et donc en pratique difficile à mettre en oeuvre. Cette thèse est consacrée précisément à l'étude de l'interaction entre une impureté Kondo individuel et son environnement magnétique à l'aide d'un STM. Une nouvelle stratégie est adoptée ici par rapport aux études antérieures de ce genre. Tout d'abord, nous éliminons la barrière tunnel en établissons un contact pointe-atome. Nous formons ainsi un point de contact quantique comprenant une seule impureté Kondo. Deuxièmement, nous utilisons des pointes ferromagnétiques. Le contact pointe-atome permet de sonder l'influence du ferromagnétisme sur l'impureté Kondo vial'observation de la résonance ASK. La géométrie de contact permet tout particulièrement de produire une densité de courant polarisé en spin suffisamment élevée pour qu'elle entraîne un dédoublement de la résonance ASK. Ce dédoublement constitue la première observation à l'échelle atomique d'un phénomène connu sous le nom d'accumulation de spin, laquelle se trouve être une propriété fondamentale de la spintronique.
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Delage, Marie-Ève. "Caractérisation de points quantiques comme matériau luminescent pour applications en dosimétrie." Doctoral thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/35023.
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La thèse présentée porte sur l’investigation d’un nouveau matériau luminescent pour une application en dosimétrie à scintillation, un matériau développé pour la première fois il y a environ une vingtaine d’années : les points quantiques colloïdaux (cQDs). Ces derniers sont des nanocristaux de semi-conducteurs possédant des propriétés uniques, découlant entre autres du confinement tridimensionnel de leurs porteurs de charge. Les cQDs constituent un matériau d’intérêt pour la dosimétrie à scintillation d’abord grâce à leur luminescence dont l’intensité est bonifiée par rapport à celle de leur équivalent macroscopique. Plusieurs autres propriétés des cQDs les rendent intéressants pour le développement d’un dosimètre à scintillation. Ils possèdent un large spectre d’absorption et un étroit spectre d’émission, dont la position du maximum d’absorption (émission) est dépendante de la taille et de la composition des cQDs. De plus, il existe de multiples supports physiques dans lesquels peuvent être insérés les cQDs, des supports comme divers solvants ou plastiques. Peu de travaux ont été menés sur la caractérisation de cQDs comme scintillateurs, spécialement dans le contexte d’une application en dosimétrie à scintillation pour la radio-oncologie. Une panoplie d’avenues nécessitaient donc d’être explorées pour établir un portrait des cQDs comme matériau luminescent pour des applications en dosimétrie. Plusieurs formes physiques dans lesquelles étaient inclus les cQDs ont été testées : de la poudre, des liquides et des plastiques. La majeure partie de la thèse traite de la caractérisation de cQDs comme scintillateur, mais une portion de la thèse porte aussi sur le développement d’instrumentation spécifique à la mesure aux accélérateurs linéaires. Celui-ci a été motivé par le fait que l’accélérateur linéaire a un rapport cyclique de 0,144%, faisant en sorte que la majorité de l’intégration continue de signal lumineux collecte du bruit. Un prototype de circuit intégrateur synchronisé a donc été développé, ce qui a permis de faire un gain sur le rapport signal sur bruit du signal mesuré. Concernant la caractérisation des cQDs, la première étude présentée rapporte les résultats d’une comparaison de la résistance à la radiation ionisante de cQDs à coquille simple et de cQDs à coquilles multiples, ce dernier étant le type utilisé pour le projet de thèse. Il a été montré que les cQDs à coquilles multiples ont une meilleure résistance à la radiation que les cQDs à coquille simple grâce à leur meilleure passivation de surface. De plus, la répétition de multiples irradiations entrecoupées de pauses a fait ressortir deux effets antagonistes pour chaque type de cQDs concernant la récupération, ou non, de leur efficacité de scintillation. Les cQDs à coquille simple ont présenté une accélération de la dégradation de leur scintillation entre les pauses alors que les cQDs à coquilles multiples ont présenté un recouvrement systématique de leur intensité de scintillation. Ensuite, une étude portant sur les dispersions liquides de cQDs est présentée. On en retire que l’efficacité de scintillation dépend de la nature du solvant dans lequel sont dispersés les cQDs. L’alkylbenzène, le meilleur solvant, permet notamment d’obtenir une intensité de scintillation constituant le dixième de celle du scintillateur commercial Ultima Gold, et ce, malgré que la concentration de cQDs soit cinq ordres de grandeur plus faible que celle du fluorophore dans Ultima Gold. La dernière étude présentée porte sur la poursuite de la caractérisation des formes poudreuse et liquide de cQDs comme dosimètres. Des mesures rapportant la linéarité du signal en fonction de la dose déposée ont été menées pour des faisceaux de photons et d’électrons. D’autres mesures ont permis de caractériser la dépendance du signal en fonction de l’énergie du faisceau. Il a été montré que les dispersions liquides ont la dépendance la moins marquée, ayant une variation maximale de 15% à 220 kVp par rapport au signal à 6 MV pour la dispersion dans l’alkylbenzène. Cette variation se trouve même à être plus petite que celle observée pour la fibre scintillante BCF-60 et pour Ultima Gold. Quelques résultats préliminaires sont finalement rapportés concernant les scintillateurs plastiques de cQDs. Entre autres, il a été observé, aux énergies kV, que la dépendance en énergie du signal suit une tendance similaire à celle du BCF-60, mais dont l’amplitude de variation est moindre. En conclusion, chacune des formes de cQDs testées possède des particularités qui pourraient mettre de l’avant son utilisation en dosimétrie à scintillation. Ces dernières sont relatées en détail dans la conclusion de la thèse.This thesis presents the investigation of a new luminescent material as the sensible volume of scintillating dosimeters, a material which has been developed in the past twenty years: colloidal quantum dots (cQDs). These nanocrystals are composed of semiconductors and have unique properties, which are in part due to the three-dimensional quantum confinement of their charge carriers. cQDs constitute a material of interest for scintillation dosimetry since they have a more important light emission than their bulk counterpart. Moreover, they have a wide absorption and a narrow emission spectrum, for which their maximum absorption (emission) is tuneable with the cQD size and composition. The cQDs can be incorporated to many physical supports like liquids or plastics. Few studies have characterized cQDs as scintillators for an application in radiation oncology dosimetry. Thus, many research paths had to be explored to establish the portrait of cQDs as a luminescent material for applications in dosimetry. cQDs under multiple physical forms were tested: powder, liquids and plastics. Even though the major part of the thesis deals with the characterization of cQDs, work has been done on improving the light signal collection. This part of the project was motivated by the low duty cycle of the linear accelerator (0.144%), which results in a continuous light acquisition including a lot of noise. Thus, a prototype of an integrated synchronized circuit was developed and lead to a better signal to noise ratio of the light signal collected, evaluated to be up to 8 times better. The first study on the cQD characterization reports the comparison results of the resistance to ionizing radiation of core/shell (CS) and multishell (MS) cQDs, the type that is used throughout the thesis. MS cQDs have proven to have a better radiation resistance than CS cQDs due to their better surface passivation. Moreover, repeated irradiations separated with pauses put forward an opposite trend concerning the effect of the pauses on the recovery of the scintillation efficiency. CS cQDs presented an accelerated degradation of their light production efficiency while MS cQDs showed a systematic scintillation efficiency recovery. In the second study, measurements were conducted in order to characterize the cQD liquid dispersions. It was observed that the cQD dispersion scintillation efficiency was dependent on the nature of the solvent. The alkylbenzene dispersion, offering the best light production, wasshown to reach a tenth of the light emission intensity of the commercial scintillator Ultima Gold. This observation is remarkable since the cQD concentration is five orders of magnitude lower than the fluorophore concentration in Ultima Gold. The last study presents the continuing characterization of the cQD powder and the cQD liquid dispersions as dosimeters. It is reported that their scintillation output is linear with dose when the cQDs are irradiated with various photon and electron beam energies. The light output dependence on beam energy was also quantified and it was shown that the cQD liquid dispersions have the least important dependence. Indeed, the alkylbenzene dispersion has a maximal signal variation from 6 MV of 15% observed at 220 kVp, a variation lower than what was reported for the scintillating fiber BCF-60 and Ultima Gold. Preliminary results are also presented for the cQD plastic scintillators. At kV energies, it was observed that the energy dependence of the scintillation output followed a similar trend than that of the BCF-60’s but had a lower variation amplitude. To conclude, each of the cQD forms has a potential in being used for scintillation dosimetry considering their proper particularities. These particularities are discussed in detail in the conclusion of the thesis.
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Nguyen, Hai Son. "Contrôle optique de l'émission résonnante de boites quantiques semiconductrices." Paris 6, 2011. http://www.theses.fr/2011PA066542.
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Cette thèse est consacrée à l'étude de l'émission résonnante de boîtes quantiques uniques InAs/GaAs en microcavité planaire. Un montage original d'excitation par fibre optique est mis en œuvre afin de découpler spatialement l'excitation résonnante de l'émission des boîtes quantiques et de s'affranchir de la diffusion parasite du laser superposée au signal d'émission résonnante. Des études en puissance d'excitation et les mesures des fonctions de corrélation du premier et deuxième ordre confirment qu'une boîte quantique semiconductrice sous excitation résonnante peut être assimilée à un véritable système à deux niveaux. Cependant, l'environnement électrostatique lié aux impuretés non-intentionnelles de l'échantillon influence fortement l'émission résonnante des boîtes quantiques. Il apparaît pour la quasi-totalité des boîtes quantiques une complète inhibition de l'émission résonnante par blocage de Coulomb. L'utilisation d'un laser non-résonant supplémentaire de très faible puissance permet de résoudre ce problème grâce à un contrôle optique très efficace de l'émission résonnante. En effet, en présence de ce « gate » optique, l'émission résonnante est débloquée et les propriétés d'un système à deux niveaux sont spectaculairement restituées. Les effets du « gate » optique sur l'émission résonnante, le décalage spectral de l'émission résonnante et la statistique des photons émis sont parfaitement expliqués de manière quantitative par un modèle de population aléatoire que nous avons développé au cours de cette thèse.
Books on the topic "Points de contacts quantiques"
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NATO Advanced Research Workshop on Quantum Dots: Fundamentals, Applications and Frontiers (2003 Crete, Greece). Quantum dots: fundamentals, applications, and frontiers: [proceedings of the NATO Advanced Research Workshop on Quantum Dots: Fundamentals, Applications and Frontiers, Crete, Greece, 20 to 24 July 2003]. Dordrecht: Springer, 2005.
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Vertrauensanknüpfung im internationalen Privat- und Zivilverfahrensrecht. Zürich: Dike-Verlag, 2008.
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Takafumi, Yao, Woo Jong-Chun, Kikai Shinkō Kyōkai, and Hanʼguk Kwahak Chaedan, eds. Physics and applications of semiconductor quantum structures: Proceedings of the International Workshop on Physics and Applications of Semiconductor Quantum Structures (Asian Science Seminar), Cheju Island, Korea, October 18-23, 1998. Bristol, U.K: Institute of Physics Pub., 2001.
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F, Habenicht Bradley, ed. Excitonic and vibrational dynamics in nanotechnology: Quantum dots vs. nanotubes. Singapore: Pan Stanford Pub., 2009.
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Design and Test of Digital Circuits by Quantum-Dot Cellular Automata. Artech House Publishers, 2007.
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Chakraborty, Tapash. Nanoscale Quantum Materials: Musings on the Ultra-Small World. Taylor & Francis Group, 2021.
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Nanoscale Quantum Materials. Taylor & Francis Group, 2021.
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Leburton, Jean-Pierre. Physical Models for Semiconductor Quantum Dots. Jenny Stanford Publishing, 2021.
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Leburton, Jean-Pierre. Physical Models for Semiconductor Quantum Dots. Jenny Stanford Publishing, 2021.
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Chakraborty, Tapash. Nanoscale Quantum Materials: Musings on the Ultra-Small World. Taylor & Francis Group, 2021.
Find full textBook chapters on the topic "Points de contacts quantiques"
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Plašienková, Zlatica, and Barbara Szotek. "Slovensko-poľské kontakty profesora Jana Zouhara." In Filosofie jako životní cesta, 52–60. Brno: Masaryk University Press, 2019. http://dx.doi.org/10.5817/cz.muni.p210-9458-2019-2.
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The article briefly reflects on Professor Jan Zouhar’s personal and professional contacts within his activities in the Slovak and Polish philosophical environment with an emphasis on the personal experience of the authors. It points out Professor Zouhar’s contribution and influence on the development of mutual relations and fruitful cooperation in the field of philosophy, as well as on the unforgettable human dimension that he brought to these relations.
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Kallestrup, Morten. "Restrained Wisdom or Not? The Advisory Roles of Political Scientists in Denmark." In The Advisory Roles of Political Scientists in Europe, 111–30. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-86005-9_6.
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AbstractThe few existing studies on Denmark showed that political scientists are not well represented in public committees, while subsequent studies argued that the means by which political scientists offer their advice are writing articles in the media and participation in other such means of communications. The survey used in this study provides empirical data offering interesting new evidence regarding the role of political scientists in the policy advisory system in Denmark. It points to the fact that political scientists deliver substantial policy advice via informal contacts and forms of communication, e.g. to civil servants, civil society organizations, politicians and advisory bodies, mainly at the national level. According to the survey’s respondents, this advice is based on sound scientific evidence, which fits well with survey evidence emphasizing the belief that experts are more prominent than opinionating scholars in Denmark compared to other countries. Thus it would seem that political scientists’ role as providers of informal and direct policy advice has been underestimated. In the light of the amount, and the soundness, of the advice provided informally, Denmark may not be a case of restrained wisdom after all.
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van Bree, Cor. "The dialect of Vriezenveen." In Investigating West Germanic Languages, 260–75. Amsterdam: John Benjamins Publishing Company, 2024. http://dx.doi.org/10.1075/sigl.8.12van.
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The village of Vriezenveen (not far from Almelo in Twente, an eastern region of the Netherlands) has a dialect that differs from its neighboring dialects in a number a features. For instance, instead of lengthened vowels in open syllables it can have rising diphthongs whereas the other Twente dialects have centered diphthongs or short vowels more open than the original short ones: ljèvn ‘to live’ [jæ.] opposite to lèëvn [εǝ] of lèvvn [ε] (Standard Dutch leven [e.] < [ε]). The Vriezenveen dialect also has (or had) diphthongs in stein ‘stone’ [εi], geitn ‘to pour’, bouk ‘book’ [ɔu] instead of Twente dialect stèèn [ε.], geetn [e.], book [o.], Standard Dutch steen [e.], gieten [i], boek [u]. These conservative features can be explained by the fact that the inhabitants of Vriezenveen had extensive contacts with the Westphalian region through which they travelled on their commercial tours to Russia (Saint Petersburg). In this German region these features can still be found. On the other hand, a form like huus ‘house’, with [y.] instead of [u.], points in a western direction. Nowadays the young inhabitants of Vriezenveen are adapting their dialect to the more general Twente dialect. This regiolectization clearly manifested itself during interviews organized from 2012 through 2015.
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Black, Jasmine E., Chris Short, and Jenny Phelps. "Water with Integrated Local Delivery (WILD) for Transformative Change in Socio-Ecological Management." In Fostering Transformative Change for Sustainability in the Context of Socio-Ecological Production Landscapes and Seascapes (SEPLS), 155–73. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-6761-6_9.
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AbstractAn innovative approach towards transformative change through multi-stakeholder participation for socio-ecological practices—Integrated Local Delivery (ILD)—has been used to restore the water quality and biodiversity across a catchment in the Cotswolds, South West England. This was triggered by the need to improve the Ecological Status of water as a part of the European Union’s Water Framework Directive. On a landscape scale of roughly 25,000 hectares, multi-stakeholders collaborated through a bottom-up approach to carry out environmental restoration of the catchment.Over 3 years, an iterative learning loop of reflection and evolution created increased engagement. Twenty farmers have been empowered as ‘guardians’ to be key contacts between institutions and ensure the sustained environmental quality of the area. Both farmers and communities acted to reduce chemical use, protect river banks from livestock damage and clear waterways to enhance water quality and biodiversity. Local communities fed into the development of a ‘Community Water Guide’ which can be applied internationally for similar projects. Within the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) transformative change framework, the ILD model can also be applied by facilitators to access levers and leverage points in order to enable change.Important take home messages from the project include having well-trained facilitators who ensure active engagement, connections and continuity over the long term. Likewise, ensuring all stakeholders feel listened to and clearly communicated with is essential to build trust and motivation.
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Bruaset, Are Magnus, Glenn Terje Lines, and Joakim Sundnes. "Chapter 7 Data aggregation and anonymization for mathematical modeling and epidemiological studies." In Simula SpringerBriefs on Computing, 121–41. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-05466-2_7.
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AbstractAn important secondary purpose of the Smittestopp development was to provide aggregated data sets describing mobility and social interactions in Norway’s population. The data were to be used to monitor the effect of government regulations and recommendations, provide input to advanced computational models to predict the pandemic’s spread, and provide input to fundamental epidemiology research. In this chapter we describe the challenges and technical solutions of Smittestopp’s data aggregation, as well as preliminary results from the time period when the app was active.We first give a detailed overview of the requirements, specifying the types of data to be collected and the level of spatial and temporal aggregation. We then proceed to describe the concepts for anonymization via :-anonymity and Y-differential privacy (Y-DP ), and the technical solutions for collecting and aggregating data from the database. In particular, we present details of how GPS- and Bluetooth events were mapped to geographical regions and points of interest, and the solutions employed for efficient data retrieval and processing. The preliminary results demonstrate how the recorded GPS- and Bluetooth events match with expected temporal and spatial variations in mobility and social interactions, and indicate the usefulness of the aggregated data as a tool for pandemic monitoring and research. One of the main criticisms of Smittestopp concerns the centralized storage of individuals’ movements, even if such data were used and presented only at an aggregated and anonymized level. In this chapter, we also outline a completely different approach, where the GPS data do not leave the user’s phone but are, instead, pre-processed to a much higher level of privacy before being dispatched to a server-side data aggregation algorithm. This approach, which would make the app significantly less intrusive, is made possible by recent advances in determining close contacts from Bluetooth data, either by a revised Smittestopp algorithm or by means of the Google/Apple Exposure Notification framework.
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Roselaar, Saskia T. "Points of Contact." In Italy's Economic Revolution, 29–60. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198829447.003.0002.
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This chapter discusses where and how interaction between Romans and Italians occurred. An important location for interaction may have been the colonies settled by the Romans throughout Italy. Many Italians also lived in these towns, which thus served as meeting places between Romans and Italians. Seasonal migration for work and transhumant pasturing created further contacts between different peoples. Finally, economic interaction also occurred at sanctuaries, seasonal fairs, and permanent marketplaces, which often served as regional economic centres. Furthermore, chapter 2 will discuss non-economic types of interaction between Romans and Italians, especially social relations and military service. This will give a general impression of the type and frequency of interactions between Romans and Italians.
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"Appendix H. Possible Discussion Points with Contacts—Informal Assistance Stage." In Asset Recovery Handbook, 224–25. The World Bank, 2011. http://dx.doi.org/10.1596/9780821386347_app-h.
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Mate, C. Mathew, and Robert W. Carpick. "Surface Forces Derived from Surface Energies." In Tribology on the Small Scale, 140–80. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780199609802.003.0006.
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As it more practical to measure the forces acting between two contacting surfaces then the energies of surfaces, this chapter covers those surface forces that are derived from surface energies. The starting point is Derjaguin’s approximation, which relates the energy between two flat surfaces to the force in other geometries: sphere/flat, sphere/sphere, and crossed cylinders. Next is a discussion of the surface forces in dry contacts with no liquid menisci around the contact points. This discussion covers the cases where adhesion causes significant deformation (JKR theory), where deformation is insignificant (DMT theory), and the cases in between. How surface roughness impacts adhesion is also discussed. The second half of this chapter deals with how liquid menisci around contacts contribute to adhesion forces, both for the sphere-on-flat geometry and for contacting rough surfaces.
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Eisenbrandt, Matt. "“ARENA’s Achilles’ Heel”." In Assassination of a Saint. University of California Press, 2017. http://dx.doi.org/10.1525/california/9780520286795.003.0006.
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This chapter describes the launch of the legal team’s investigation with a trip to El Salvador to look into those who financed the death squads. The most promising lead comes from allegations by Hector Regalado, a known associate of Roberto D’Aubuisson, who spoke with contacts of the legal team. Through a description of the trip and trial testimony about the Saravia diary, the chapter provides further evidence about the financiers, and points to evidence about an ARENA party founder, Billy Sol.
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Muzychka, Yuri S., and M. Michael Yovanovich. "How to Use this Book." In Thermal Spreading and Contact Resistance: Fundamentals and Applications, 1–13. ASME, 2023. http://dx.doi.org/10.1115/1.862tsc_ch1.
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Thermal spreading (or constriction) resistance results when heat is conducted away from a finite region into a larger region (spreading resistance) or from a larger region through a smaller region (constriction resistance). Spreading or constriction resistance can be determined by solving transient or steady-state heat conduction in a solid region with appropriately applied boundary and initial conditions. When the contact areas result in imperfect contact at the microscopic level, we find an array of discrete points of contacts results. Heat transfer across the apparent contact region occurs through conduction at these discrete points of contact and across the gap if there is a gas or liquid present; otherwise, heat transfer through radiation may occur in a vacuum. In these instances, we have contact resistance. In this text, we strive to present the general theory and applications of thermal spreading and contact resistance.
Conference papers on the topic "Points de contacts quantiques"
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Liang, Huimin, Jun Xu, Rongling Zhang, Guofu Zhai, and Yanling Hao. "Research on the Starting Points of the Combined Subsection Permanent Magnet." In 2008 IEEE Holm Conference on Electrical Contacts (Holm 2008). IEEE, 2008. http://dx.doi.org/10.1109/holm.2008.ecp.33.
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Israel, Toni, Stephan Schlegel, Steffen Grosmann, Tom Kufner, and George Freudiger. "Modelling of Transient Heating and Softening Behaviour of Contact Points During Current Pulses and Short Circuits." In 2019 IEEE Holm Conference on Electrical Contacts. IEEE, 2019. http://dx.doi.org/10.1109/holm.2019.8923941.
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Fallahi, Behrooz, and Andrew Behnke. "A Graphical User Interface for Contacts Between Wheel and Rail." In 2014 Joint Rail Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/jrc2014-3829.
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Analysis of contact points between wheel and rail during the wheel climb is of interest to railroad application engineers. In this study the climb maneuver of a wheelset is modeled in a general purpose multi-body system computer program. This model then is used to generate the contact data for a climbing wheelset. A graphical user interface is developed which uses this contact data and generates several contact points charts. In developing the graphical user interface, mouse and keyboard events as well as other controls are used to make the interface interactive and intuitive.
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Sugiyama, Hiroyuki, and Yoshihiro Suda. "Hybrid Contact Search Algorithm for Wheel/Rail Contact Problems." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68588.
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In this investigation, the on-line and off-line hybrid contact algorithm for modeling wheel/rail contact problems is developed based on the elastic contact formulation. In the tabular contact search used in existing specialized railroad vehicle dynamics codes, contact points are predicted using an assumption of rigid contacts. For this reason, the contact points can be different from those predicted by the on-line based contact search used in general elastic contact formulations. The difference in the contact point becomes significant when flange contacts that have large contact angles are considered. In the hybrid algorithm developed in this investigation, the off-line tabular search is used for treating tread contacts, while the on-line iterative search is used for treating flange contacts. By so doing, a computationally efficient procedure is achieved while keeping accurate predictions of contact points on the wheel flange. Furthermore, the use of the proposed hybrid algorithm can eliminate the use of time-consuming on-line search procedures for the second points of contact as well. Since the location of second points of contact is pre-computed in the contact geometry analysis, the occurrence of two-point contact can be predicted using the look-up table in a straightforward manner. For the two-point contact scenarios encountered in curve negotiations, the online search is used for flange contacts, while the off-line search is used for tread contacts simultaneously. The on-line one-point contact search is also important for flange climb scenarios. It is demonstrated by several numerical examples that the proposed hybrid contact search algorithm can be effectively used for modeling wheel/rail contacts in the analysis of general multibody railroad vehicle systems.
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Spiˆnu, Sergiu, and Emanuel Diaconescu. "Numerical Simulation of Elastic Conforming Contacts Under Eccentric Loading." In STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71275.
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The subject of eccentrically loaded conforming contacts is approached analytically under the restriction that the eccentricity is small enough to keep the contact closed. This paper advances a numerical method for contact analysis valid at any eccentricity value. An additional loop is added to the classic elastic contact solver to account for load eccentricity. The method predicts contact area and pressure distribution even when the contacting bodies lose contact in some peripheral points. Numerical results of pressure distribution for a circular flat end punch agree well with existing analytical predictions.
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Slade, Paul G. "The threshold welding current for large area closed contacts with ‘n’ points of contact for short duration, high fault currents." In 2014 IEEE 60th Holm Conference on Electrical Contacts (Holm). IEEE, 2014. http://dx.doi.org/10.1109/holm.2014.7031015.
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Shabana, Ahmed A., Khaled E. Zaazaa, Jose´ L. Escalona, and Jalil R. Sany. "Modeling Two-Point Wheel/Rail Contacts Using Constraint and Elastic-Force Approaches." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-39601.
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Two approaches are commonly used for solving the problem of wheel/rail contact in railroad dynamics. The first is the elastic approach in which the wheel is assumed to have six degrees of freedom with respect to the rail. The normal contact forces are defined using Hertz’s contact theory or in terms of assumed stiffness and damping coefficients. The second approach is the constraint approach in which nonlinear kinematic contact constraint equations are introduced, leading to a model in which the wheel has five degrees of freedom with respect to the rail. It is the objective of this investigation to present a new formulation for the wheel/rail contact problem based on the elastic force approach. Crucial to the success of any elastic force formulation for wheel/rail contact problem is the accurate prediction of the location of the contact points. To this end, features of multibody formulations that allow introducing arbitrary differential equations are exploited in this investigation in order to obtain a good estimate of the rail arc length traveled by the wheel set. In the formulation presented in this paper, four surface parameters are used to describe the wheel and the rail surfaces each with arbitrary geometry. In order to determine the location of the points of contact between the wheel and the rail, a first order differential equation for the rail arc length is introduced and is integrated simultaneously with the multibody equations of motion of the wheel/rail system. The method presented in this paper allows for multiple points of contact between the wheel and the rail by using an optimized search for all possible contact points. The normal contact forces are calculated and used with non-linear expressions for the creepages to determine the creep forces. The paper also discusses two different procedures for the analysis of the two-point contact in the wheel/rail interaction. Numerical results obtained using the elastic force model are presented and compared with the results obtained using the constraint approach.
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Milovanović, Milan R., Jelena M. Živković, Ivana M. Stanković, Dragan B. Ninković, and Snežana D. Zarić. "Repulsive water-water contacts from Cambridge Structural Database." In 2nd International Conference on Chemo and Bioinformatics. Institute for Information Technologies, University of Kragujevac, 2023. http://dx.doi.org/10.46793/iccbi23.637m.
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Water is one of the most important molecules on the Earth. Since water plays a crucial role in many life processes, it is of great importance to understand every aspect of its behavior and interactions with itself and its surroundings. It is known that water molecules can interact via classical hydrogen bonds and antiparallel interactions, with interaction energies of – 5.02 kcal/mol and -4.22 kcal/mol, respectively. Besides these attractive interactions, repulsive interactions were also noticed. In this work, we analyzed repulsive water-water contacts from the Cambridge Structural Database. All interaction energies were calculated at the so- called gold standard, i.e., CCSD(T)/CBS level of theory. It was found that among all water-water contacts, ca. 20% (2035 contacts) are repulsive with interaction energies mainly up to 2 kcal/mol. Most of these repulsive contacts do not belong to two main groups of water-water contacts. Namely, 12.8% of all repulsive contacts can be classified as classical hydrogen bonds, 2.1% to the antiparallel interactions, and the rest (85.3%) as remaining contacts. This study points out that additional attention should be paid when one deals with contacts including water or, eventually, hydrogen atoms in general.
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Shuttleworth, David M., and Mary Drummond Roby. "Scanning Electron Microscope Induced Electrical Breakdown of Tungsten Windows in Integrated Circuit Processing." In ISTFA 2004. ASM International, 2004. http://dx.doi.org/10.31399/asm.cp.istfa2004p0236.
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Abstract Interaction of inline SEM inspections with tungsten window-1 integrity were investigated. Multiple SEMs were utilized and various points in the processing were inspected. It was found that in certain circumstances inline SEM inspection induced increased window-1 contact resistance in both source/drain and gate contacts, up to and including electrical opens for the source/drain contacts.
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Camuz, Soner, Magnus Bengtsson, Rikard Söderberg, and Kristina Wärmefjord. "Contact Variation Optimization for Surface-to-Surface Contacts." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70877.
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Locating schemes, used to position parts during manufacturing, are usually designed in such a way that the response from the system is minimized. This implies that the position of the fasteners and/or welds are known in an assembly. Today there exist numerous of methods aiming to find an optimal set of locating points to increase the stability of an assembly, for both rigid and compliant parts. However, various industrial applications use surface-to-surface contacts to constrain certain degrees of freedom. This can lead to designs sensitive to geometric and load variations. As the complexity of the surfaces increases, difficulties of allocating geometric tolerances arise. An approach to control this is to keep the contact locations statistically stable. In this paper a methodology is presented where the First-Order Reliability Method (FORM) is applied for numerical data, retrieved through Finite Element Analysis (FEA), to ensure that statistically stable contact location are achieved for two bodies with surface-to-suface contact. The FEA data represents how much of the total stress that lies within a given area, σΩ. The data is continuous and therefore it is assumed that the gradient can be calculated numerically with small steps. The objective function is to maximize σΩ for n variables. The data set is simulated through Finite Element Analysis using the commercial software Ansys and the results is illustrated on a case study from the machining industry.
Reports on the topic "Points de contacts quantiques"
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Nakasone, Eduardo. Soap Operas for Female Micro Entrepreneur Training. Inter-American Development Bank, December 2014. http://dx.doi.org/10.18235/0011672.
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This paper analyzes the impact of the Strengthening Women Entrepreneurship in Peru (SWEP) program. SWEP trained female micro entrepreneurs in business management practices (such as accounting and marketing). The training, which was provided in 4- to 5-hour sessions, used soap operas and practical exercises specifically designed for the program. A field experiment was conducted among a group of micro entrepreneurs based in two Peruvian cities (Lima and Piura) to investigate whether SWEP had a positive impact on its beneficiaries. The results show that the program positively affected the adoption of business practices taught by the program. In particular, those who received the training were 4 to 6 percentage points more likely to assign themselves a fixed salary (rather than taking cash from their businesses based on personal needs) and 6 to 11 percentage points more likely to keep better records of potential business contacts. Some positive impacts were found on the adoption of bookkeeping practices (4 to 6 percentage points), although this result is not significant across all of the specifications. Although these changes in adoption rates were large compared with their baseline levels, they were rather small in absolute terms. Therefore, the study did not find any impact on average business performance, household expenditures, or women's empowerment in the household. Qualitative information suggests that micro entrepreneurs were satisfied with the training, but considered that many of the practices taught by the program were difficult to follow because of time constraints.
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Гарлицька, Тетяна Сергіївна. Формування міжкультурної компетентності як одна з умов запровадження європейських стандартів мовної освіти. Wschodnioeuropejski Institut Psychologii, 2022. http://dx.doi.org/10.31812/123456789/7064.
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Статтю присвячено обґрунтуванню важливості формування міжкультурної компетентності, зокрема у студентів філологів. Реалізація міжкультурної компетентності розглядається як одна з умов запровадження європейських стандартів мовної освіти. Сучасні глобалізаційні процеси, розширення міжкультурних контактів вимагають від освітнього простору України орієнтації на виховання фахівця нового рівня – суб’єкта полікультурного простору. Професійна компетентність фахівців різних галузей стає неможливою без володіння ними міжкультурною компетентністю. Поняття «міжкультурна компетентність» розглядається в роботі як міждисциплінарний феномен та досліджується з позицій філософії, культурології, соціології, психології, педагогіки та лінгводидактики. Особливу увагу зосереджено на зв’язку культури та мови, оскільки мовні знання є інструментом пізнання іншої культури та важливою умовою міжкультурної комунікації. The article raises the problem of importance of intercultural competence forming, in particular among students of philology. The realization of intercultural competence is considered as one of the conditions for establishment of the European standards of language education. Modern globalization processes, expansion of intercultural contacts demand the Ukrainian education to be focused on the new level specialist – the subject of multicultural surrounding. Professional competence of specialists of different fields is impossible without possessing intercultural competence. The concept «intercultural competence» is considered as multidisciplinary phenomenon which is studied from different points of view: philosophical, cultural, sociological, psychological, pedagogical and linguodidactic. The main attention is focused of the connection of culture and language because language competence is the tool for another culture cognition and an important condition of intercultural communication.