Дисертації з теми "Collision reaction"
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1
Keane, Norman Washington. "Reaction dynamics of short lived collision complexes." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329286.
Повний текст джерела
2
GYLLING, MARTIN. "Sensorless collision detection with safe reaction for a robot manipulator." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263829.
Повний текст джерелаАнотація:
This thesis is about collision detection and reaction for robot manipulators without joint torque sensors. The method for detecting collisions used by [1], [2] is based on an algorithm that estimates the residual torque i.e. the friction- and external torque in each joint by only using position data from encoders and the currents in each joint on the robot. The dynamic models for the robot in the residual torque estimation algorithm are calculated using the Lagrangian formulation. These models consist of different components that influence the joint torques such as inertia, centripetal acceleration, coriolis acceleration and gravity. By modelling the friction torque in the joints, it is possible to compare the modelled friction torque with the estimated residual torque from the algorithm. The difference between these torques results in an estimation of the external torque acting on each joint. Thresholds for the external torques are experimentally determined, when the external torques exceed these, a collision is detected by the robot. After a collision has been detected, the robot needs to react in a safe way to minimize the risk of damaging the robot and its environment. Collision reaction strategies have been proposed by [3], a few of these are implemented and compared between each other for different cases of collision in this thesis. The collision detection and different collision reactions were implemented on a UR5-e robot from Universal robots. The results showed that the simple reaction of braking the robot and then maintaining the position using position control is the quickest way of stopping the motion of the robot after a collision has been detected. Due to the hazard of someone getting stuck between the robot and the environment the former explained strategies were not chosen as an optimal collision strategy, instead a strategy where the robot brakes and then switches to a compliant control mode showed to be a better solution since the stopping time is only slightly longer but the impulse of the collision is the best of all the different strategies that were tested. Where the previous research in the field of sensorless collision detection that has been referenced in this report only has focused on the method of detecting the collision, this thesis continues the research by applying different reaction strategies on a robot without torque sensors and torque control capabilities. By combining the method for collision detection from [1], [2] together with reaction strategies from [3], this thesis has shown how robot manipulators that do not have expensive torque sensors in each joint can be made safer.Detta examensarbete handlar om kollisionsdetektering och kollisionsreaktion för robotarmar utan vridmomentssensorer. Detekteringsmetoden som tidigare använts av [1], [2] bygger på en algoritm som uppskattar residual vridmomentet d.v.s. friktions- samt det externa vridmomentet i varje axel genom att enbart nyttja positionsgivare och strömsensorer på roboten. De dynamiska modellerna för roboten som används i algoritmen för beräkning av residual vridmomentet framtags med hjälp av Lagranges ekvationer, dessa modeller består av olika komponenter som påverkar vridmomenten i robotens leder så som tröghetsmoment, centripetalacceleration, corioliseffekt samt gravitation. Genom att ta fram modeller för friktionsvridmomenten i robotens axlar går det att jämföra de beräknade friktionsvridmomenten från modellerna med de uppskattade residual vridmomenten från algoritmen, skillnaden mellan dessa två vridmoment blir då en uppskattning på det externa vridmomentet som roboten utsätts för. Tröskelvärden för de externa vridmomenten bestäms genom experiment, dessa tröskelvärden är till för att upptäcka kollisioner genom att övervaka när de externa vridmomenten överskrider dessa värden. Till följd av att en kollision har upptäckts måste roboten reagera på ett sätt som minimerar risken att roboten eller omgivningen tar skada. Strategier för hur en robot kan reagera då en kollision inträffar har tagits fram av [3], ett par av dessa implementeras och jämförs för olika kollisionsfall i denna rapport. Kollisionsdetekteringen samt olika reaktionsstrategier implementerades på en UR5-e robot från Universal robots. Resultaten visade att den enkla reaktionen där roboten bromsar och sedan bibehåller positionen med hjälp av positionsreglering var den reaktion som var snabbast att stoppa rörelsen av roboten. På grund av risken att någon kan fastna mellan roboten och omgivningen valdes inte strategin som tidigare beskrevs. En strategi där roboten bromsar och sedan går in i ett fridrifts läge visade sig vara en bättre lösning då tiden att få stopp på roboten var bara något längre än den 2 snabbaste strategin samt att impulsen vid en kollision i genomsnitt var lägst av alla strategier som prövades. Då tidigare forskning i området för sensorlös kollisonsdetektering som refereras i denna rapport enbart har fokuserat på kollision detekteringen, bygger denna rapport vidare på den forskning som utförts genom att lägga till och implementera olika strategier för kollisionsreaktion på en robot utan vridmomentsensorer eller vridmomentsreglering. Genom att kombinera metoden för kollisionsdetektering tagen från [1], [2] med reaktions strategier från [3] har detta examensarbete visat hur en robotarm som inte har dyra vridmomentssensorer kan göras säkrare.
3
Dexter, Matthew A. "Thermodynamic and parametric optimisation of collision/reaction cells in plasma-source mass spectrometry." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/34294.
Повний текст джерелаАнотація:
Inductively coupled plasma mass spectrometry (ICP-MS) is an established technique for elemental analysis. Collision/reaction cell ICP-MS is a recently established variation of the technique that facilitates the determination of elements suffering from spectral interference. Two distinct collision cell ion energy effects have been identified: the ion kinetic energy effect (IKEE) and kinetic energy discrimination (KED). IKEE influences the reactivity of the cell by altering the ion energy. Slowing ions by increasing the potential difference between the hexapole pole bias and plasma increases the rate of exothermic reactions in the cell. KED excludes slow, cell-formed ions from the mass analyser by the use of an appropriate potential difference between the quadrupole and hexapole pole biases.
4
Neves, Denise Regina das [UNESP]. "Avaliação de interface de reação e colisão para eliminar interferências poliatômicas na análise de etanol combustível por ICP-MS." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/97823.
Повний текст джерелаАнотація:
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neves_dr_me_araiq.pdf: 1981084 bytes, checksum: 865cb404889acf20e4c3ed4fe5b2320e (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A espectrometria de massa com plasma acoplado indutivamente empregando interface de reação/colisão (CRI-ICP-MS) foi avaliada para determinação simultânea de Al, Ba, Co, Cu, Cr, Fe, Mg, Mn, Mo, Na, Ni, Pb, Sb, Si, V e Zn em etanol combustível. Para as análises, amostras de etanol combustível foram diluídas vinte vezes de modo a conter 1% v/v de ácido nítrico e 10 μg L-1 Y utilizado como padrão interno. As calibrações foram feitas por ajuste de matriz utilizando etanol P.A.. Como gás de reação/colisão utilizou-se o hidrogênio e como gases auxiliares foram utilizados argônio e oxigênio. A CRI foi fundamental para a determinação da maioria dos analitos, principalmente Fe, Cr, Si e Mg. A escolha da melhor vazão do gás e a otimização dos parâmetros instrumentais foram estudadas utilizando soluções etanólicas contendo 10 μg L-1 dos analitos. Os limites de detecção para 27Al, 138Ba, 59Co,63Cu, 55Mn, 98Mo, 23Na, 58Ni, 208Pb, 121Sb, 51V e 64Zn em etanol por CRI-ICP-MS utilizando 20 mL min-1 de H2 no skimmer foram 0,2; 0,1; 0,005; 0,3; 0,02; 0,05; 0,8 0,2; 0,01; 0,1; 0,4 e 0,3 μg L-1, respectivamente. Os limites de detecção para 52Cr, 56Fe, 24Mg, 28Si em etanol utilizando 60 mL min-1 de H2 no skimmer foram 0,2; 0,1; 0,2 e 13,9 μg L-1. A validação do método foi feita por meio de testes de adição e recuperação dos analitos. Os intervalos de recuperação encontrados para 27Al, 138Ba, 59Co, 63Cu, 55Mn, 98Mo, 23Na, 58Ni, 208Pb, 121Sb, 51V, 64Zn, 52Cr, 56Fe, 24Mg, 28Si se apresentaram entre 78 e 114%
The use of inductively coupled plasma mass spectrometry with collision/reaction interface (CRI) was evaluated for simultaneous determination of Al, Ba, Co, Cu, Cr, Fe, Mg, Mn, Mo, Na, Ni, Pb, Sb, Si, V e Zn in ethanol fuel. Samples were diluted 1:20 v/v in a solution containing 1% v/v nitric acid and 10 μg L-1 Y used as internal standard. For all elements the instrument was operated in CRI-ICP-MS mode. The use of CRI was mandatory for Fe, Cr, Si e Mg. Hydrogen was evaluated as the reaction/collision gas and argon and oxygen were used as auxiliary gas. Selection of best reaction gas flow rate and optimization of the instrumental parameters were carried out using ethanolic solutions containing analytes at 10 μg L-1. Limits of detection for 27Al, 138Ba, 59Co, 63Cu, 55Mn, 98Mo, 23Na, 58Ni, 208Pb, 121Sb, 51V e 64Zn in ethanol fuel by CRI-ICP-MS using 20 mL min-1 H2 in the skimmer cone 0.2; 0.1; 0.005; 0.3; 0.02; 0.05; 0.8; 0.2; 0.01; 0.1; 0.4 and 0.3 μg L-1, respectively. The detection limits for 52Cr, 56Fe, 24Mg, 28Si using 60 mL min-1 H2 in the skimmer cone were respectively 0.2; 0.1; 0.2 and 13.9 μg L-1. Method validation was accomplished by the addition and recovery studies. Recoveries found for 27Al, 138Ba, 59Co, 63Cu, 55Mn, 98Mo, 23Na, 58Ni, 208Pb, 121Sb, 51V e 64Zn, 52Cr, 56Fe, 24Mg, 28Si were within the 78 - 114% interval
5
Schreiner, Lisa Marie. "An Investigation of the Effectiveness of A Strobe Light As An Imminent Rear Warning Signal." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/35887.
Повний текст джерелаАнотація:
Strobe lights have been used successfully in many transportation applications to increase conspicuity. It was hoped that a strobe signal could also be applied to more effectively warn distracted drivers of an unexpected rear end conflict.
This "proof of concept study" used a 2 x 2 between-subjects design using thirty-three subjects (16 subjects in the strobe condition, 17 subjects in the no strobe condition) who were divided into two age groups: younger (25-35) and older (60-70). The driver unexpectedly encountered a stopped "surrogate" vehicle in the roadway (with or without a rear-facing strobe light) in a controlled on-road study at the Smart Road located at the Virginia Tech Transportation Institute (VTTI).
Results suggested that younger subjects' perception times improved as a result of being exposed to the strobe signal. Faster perception of the situation allowed more time to initiate a brake response. Older subjects perception and response times remained unchanged by the strobe signal. More severe initial steering rate and subjective responses indicated that the strobe conveyed a sense of urgency irrespective of age.
Visual distraction of subjects proved difficult. Hence, the impact of the strobe on attracting the attention of a visually distracted driver to the stimulus could not be as fully investigated as originally hoped. The formulation of a more difficult distraction task was suggested for future research to truly assess the ability of the strobe light at alerting visually distracted drivers.Master of Science
6
Girard, Bertrand. "Etude de la collision reactive ii + f -> if + i par fluorescence induite par laser." Paris 6, 1987. http://www.theses.fr/1987PA066398.
Повний текст джерелаАнотація:
Etude de cette collision par la methode des faisceaux croises et grace a la transition (b <- x) intense, dans le visible, apres analyse de la saturation du processus d'excitation laser de cette transition de if forme. Deduction des populations des differents niveaux rovibrationnels de l'etat x. Etablissement d'une cartographie detaillee de la distribution rotationnelle des niveaux vibrationnels v = 8 a 20 de l'etat x de if: aspect bimodal qui implique la coexistence de deux chemins reactionnels differents. Attribution a un artefact de l'important signal observe anterieurement pour v = 0. Mesures preliminaires de la section efficace differentielle par effet doppler
7
Wright, Victoria E. "Ion mobility-mass spectrometry studies of organic and organometallic complexes and reaction monitoring." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/14275.
Повний текст джерелаАнотація:
Ion mobility (IM) spectrometry is a gas-phase electrophoretic technique in which ions are separated on the basis of their relative mobility in the presence of a weak electric field gradient and a buffer gas. Ion mobility-mass spectrometry (IM-MS) has the capability of separating ions based on m/z, size and shape, providing additional structural information compared to using mass spectrometry on its own. In this thesis, IM-MS has been used to investigate organic and organometallic complexes and identify reactants, intermediates and products in reaction mixtures. Collision cross sections (CCS) have been measured for three salen ligands, and their complexes with copper and zinc using travelling-wave ion mobility-mass spectrometry (TWIMS) and drift tube ion mobility-mass spectrometry (DTIMS), allowing a comparative size evaluation of the ligands and complexes. CCS measurements using TWIMS were determined using peptide and TAAH calibration standards with good intra-day and inter-day reproducibility. TWIMS measurements gave significantly larger CCS than DTIMS derived data in helium, indicating that the choice of calibration standards is important in ensuring the accuracy of TWIMS derived CCS measurements. The CCS data obtained from IM-MS measurements have been compared to CCS values obtained from X-ray coordinates and modelled structures. The analysis of small organic and organometallic molecules has been extended to investigations of the potential of IM-MS for reaction monitoring and structural studies of the components of catalytic cycles. Reaction mixtures of an organocatalysed Diels-Alder cycloaddition reaction have been monitored using IM-MS and high-field asymmetric waveform ion mobility-mass spectrometry (FAIMS-MS). Reactant, product, catalyst and reaction intermediates, including an intermediate not previously detected, were identified and the catalyst and intermediates monitored over time. An organometallic catalytic cycle using a palladium catalyst has been analysed using IM-MS and the CCS of reactants, intermediates and products have been measured and compared to theoretical CCS calculations. Good agreement was observed between measured and calculated data. Species not amenable to electrospray ionisation were covalently bound to an ionisable tag containing a quaternary ammonium ion allowing the tagged molecules to be detected by IM-MS.
8
Seamons, Scott Andrew. "The collision dynamics of OH(A)+H2." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:36319557-1efa-4840-8f46-c15479945a0c.
Повний текст джерелаАнотація:
This thesis presents a joint experimental and theoretical study of a bimolecular collision between OH(A) and H2 diatoms. The study focuses on the relationship between the initial, j, and final rotational angular momentum, j'. This relationship is explored from both a scalar point of view by measuring rotational energy transfer (RET), and a vectorial viewpoint by considering the collisional depolarisation. The experimental technique used in this investigation, Zeeman quantum beat spectroscopy, is first demonstrated by applying it to the determination of the lab-frame orientation of OH(X) photofragments following the photolysis of H2O2. The H2O2 is photolysed by circularly-polarised light at 248 nm, and Zeeman quantum beat spectroscopy probes the angular momentum orientation as a function of the photofragment spin-rotation level. The results of this experiment are compared with orientation parameters predicted by a simulation that couples the rotation of the parent molecule to the torsional motion during bond cleavage. The calculations from the model agree qualitatively with those from the experiment. The Zeeman quantum beat spectroscopy technique is then used to monitor the evolution of angular momentum polarisation of OH(A) radicals during collisions with H2. The technique allows for the determination of depolarisation cross sections for oriented and aligned distributions, as a result of collisions with H2. Alongside this, cross sections for collisional quenching to non-reactive OH(X)+H2 and reactive H2O+H products are determined. By resolving the fuorescence with a monochromator the contributions to depolarisation from elastic collisions (the elastic depolarisation cross sections) are measured alongside cross sections for RET. Cross sections for total depolarisation and rotational energy transfer demonstrate only weak dependence on the rotational quantum number of the OH(A) radical, NOH. Competing quenching processes that fall with NOH are likely a considerable cause of this weak dependence. Furthermore, the polarisation of the angular momentum of OH(A) is randomised following RET. The elastic depolarisation cross sections make only a small contribution to the depolarisation and fall with increasing NOH. Collectively these trends have not been seen previously in similar studies on OH(A) collisions with atomic colliders. For the theoretical calculations, a four-atom quasi-classical trajectory (QCT) method has been developed, utilising Lagrangian multipliers to fix the OH(A) and H2 bonds. The calculations demonstrate that collisions involving the formation of complexes that survive for several rotational periods are prevalent in this collision system, and that these lead to large amounts of depolarisation. The calculations also demonstrate that RET in the H2 diatom supports higher levels of RET in OH(A) than seen in previous triatomic systems. Additionally, when one diatom is depolarised the accompanying diatom is typically also depolarised. These trends, at least in part, are owed to the highly attractive and anisotropic potential energy surface (PES) describing the interaction. The QCT calculations overestimate the experimentally-measured cross sections by more than a factor of 2. The calculations are adiabatic and do not account for the non-adiabatic activity associated with this collision system, and this is likely one cause of the discrepancies. In an attempt to further account for this overestimation, alternative angular momentum binning approaches for the QCT calculations are developed, but with limited success. Further exploration of the topology of the PES used in the calculations suggests that inadequacies in this surface are a major contributor to the discrepancies.
9
Neves, Denise Regina das. "Avaliação de interface de reação e colisão para eliminar interferências poliatômicas na análise de etanol combustível por ICP-MS /." Araraquara : [s.n.], 2010. http://hdl.handle.net/11449/97823.
Повний текст джерелаАнотація:
Orientador: José Anchieta Gomes NetoBanca: Márcia Andréia Mesquita Silva da Veiga
Banca: Joaquim de Araujo Nóbrega
Resumo: A espectrometria de massa com plasma acoplado indutivamente empregando interface de reação/colisão (CRI-ICP-MS) foi avaliada para determinação simultânea de Al, Ba, Co, Cu, Cr, Fe, Mg, Mn, Mo, Na, Ni, Pb, Sb, Si, V e Zn em etanol combustível. Para as análises, amostras de etanol combustível foram diluídas vinte vezes de modo a conter 1% v/v de ácido nítrico e 10 μg L-1 Y utilizado como padrão interno. As calibrações foram feitas por ajuste de matriz utilizando etanol P.A.. Como gás de reação/colisão utilizou-se o hidrogênio e como gases auxiliares foram utilizados argônio e oxigênio. A CRI foi fundamental para a determinação da maioria dos analitos, principalmente Fe, Cr, Si e Mg. A escolha da melhor vazão do gás e a otimização dos parâmetros instrumentais foram estudadas utilizando soluções etanólicas contendo 10 μg L-1 dos analitos. Os limites de detecção para 27Al, 138Ba, 59Co,63Cu, 55Mn, 98Mo, 23Na, 58Ni, 208Pb, 121Sb, 51V e 64Zn em etanol por CRI-ICP-MS utilizando 20 mL min-1 de H2 no skimmer foram 0,2; 0,1; 0,005; 0,3; 0,02; 0,05; 0,8 0,2; 0,01; 0,1; 0,4 e 0,3 μg L-1, respectivamente. Os limites de detecção para 52Cr, 56Fe, 24Mg, 28Si em etanol utilizando 60 mL min-1 de H2 no skimmer foram 0,2; 0,1; 0,2 e 13,9 μg L-1. A validação do método foi feita por meio de testes de adição e recuperação dos analitos. Os intervalos de recuperação encontrados para 27Al, 138Ba, 59Co, 63Cu, 55Mn, 98Mo, 23Na, 58Ni, 208Pb, 121Sb, 51V, 64Zn, 52Cr, 56Fe, 24Mg, 28Si se apresentaram entre 78 e 114%
Abstract: The use of inductively coupled plasma mass spectrometry with collision/reaction interface (CRI) was evaluated for simultaneous determination of Al, Ba, Co, Cu, Cr, Fe, Mg, Mn, Mo, Na, Ni, Pb, Sb, Si, V e Zn in ethanol fuel. Samples were diluted 1:20 v/v in a solution containing 1% v/v nitric acid and 10 μg L-1 Y used as internal standard. For all elements the instrument was operated in CRI-ICP-MS mode. The use of CRI was mandatory for Fe, Cr, Si e Mg. Hydrogen was evaluated as the reaction/collision gas and argon and oxygen were used as auxiliary gas. Selection of best reaction gas flow rate and optimization of the instrumental parameters were carried out using ethanolic solutions containing analytes at 10 μg L-1. Limits of detection for 27Al, 138Ba, 59Co, 63Cu, 55Mn, 98Mo, 23Na, 58Ni, 208Pb, 121Sb, 51V e 64Zn in ethanol fuel by CRI-ICP-MS using 20 mL min-1 H2 in the skimmer cone 0.2; 0.1; 0.005; 0.3; 0.02; 0.05; 0.8; 0.2; 0.01; 0.1; 0.4 and 0.3 μg L-1, respectively. The detection limits for 52Cr, 56Fe, 24Mg, 28Si using 60 mL min-1 H2 in the skimmer cone were respectively 0.2; 0.1; 0.2 and 13.9 μg L-1. Method validation was accomplished by the addition and recovery studies. Recoveries found for 27Al, 138Ba, 59Co, 63Cu, 55Mn, 98Mo, 23Na, 58Ni, 208Pb, 121Sb, 51V e 64Zn, 52Cr, 56Fe, 24Mg, 28Si were within the 78 - 114% interval
Mestre
10
Salbaing, Thibaud. "Thermalisation dans une nanogoutte : évaporation versus réactivité." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1163/document.
Повний текст джерелаАнотація:
Les systèmes moléculaires sous irradiation sont présents dans le monde vivant et la matière inerte. D’un point de vue macroscopique, ils sont constitués d’un très grand nombre de molécules mais l’action d’un rayonnement agit à travers les électrons localisés sur une molécule, créant ainsi, localement et sur des échelles de temps courts, une situation manifestement très éloignée de l’équilibre thermodynamique. Etudier les nanosystèmes moléculaires sous irradiation permet d’accéder à la manière dont l’énergie déposée dans une molécule va être redistribuée dans le système, via les interactions entre molécules. Les distributions de vitesses d’une molécule évaporée mesurées pour les nanogouttes de méthanol protonées présentent un comportement bimodal avec, comme observé pour l’eau, l’évaporation de molécules avec des vitesses nettement supérieures à celles attendues après redistribution complète de l’énergie. De plus, une réaction dans l’agrégat, conduisant à la formation du diméthyléther protoné avec élimination d’une molécule d’eau, a été observée. La possibilité d’étudier la compétition suite à l’irradiation entre l’évaporation moléculaire et une réaction d’élimination pourra contribuer à contraindre les hypothèses quant à la formation de molécules prébiotiques en conditions interstellaires.Les résultats sur les nanogouttes mixtes eau-méthanol ont été comparés à ceux obtenus avec celles dopées en pyridine et celles d’eau pure. L’analyse de la partie basse vitesse des distributions de vitesses des molécules d’eau évaporées montrent que l’évaporation intervient avant la redistribution complète de l’énergie dans l’ensemble de l’agrégat. Il apparaît qu’il y a moins d’énergie disponible pour l’évaporation d’une molécule d’eau quand l’excitation initiale est déposée sur le méthanol protoné ou sur l’ion pyrimidium. Ainsi, à la différence de l’ion hydronium qui est parfaitement solvaté, les impuretés favorisent la croissance de ces petits agrégats d’eau dont la présence dans l’atmosphère facilite les premières étapes de la formation des aérosolsMolecular systems under irradiation are present in the living as well as in inert matter. From a macroscopic point of view, the matter is made up of a very large number of molecules but the action of radiation acts through the electrons located on a molecule and thus, creating locally and on short time scales a situation clearly far from the thermodynamic equilibrium. Studying molecular nanosystems under irradiation provides access to understanding of how the energy deposited in a molecule will be redistributed into the system through interactions between surrounding molecules.The velocity distributions of evaporated molecules measured for irradiated protonated methanol nanodroplets have a bimodal behaviour, as observed for water, including evaporation of molecules with much higher velocities than expected after complete redistribution of energy. In addition, a reaction in the cluster leading to the formation of protonated dimethyl-ether with elimination of a water molecule was observed. The possibility of studying the competition between molecular evaporation and an elimination reaction following irradiation of a nanodroplet will contribute to constrain the hypothesis on the formation of prebiotic molecules under interstellar conditions. The results for the water-methanol mixed nanodroplets were compared with those obtained with pyridine doped water nanodroplets and protonated water nanodroplets. Analysis of the low velocity part of the velocity distributions of the evaporated water molecules shows that evaporation occurs before the complete redistribution of energy in the cluster. It appears that there is less energy available for evaporation of a water molecule when the initial excitation is located on the protonated methanol ion or on the pyrimidium. Thus, unlike the hydronium ion which is fully solvated, impurities promote the growth of these small water clusters, whose presence in the atmosphere facilitates the early stages of aerosol formation
11
TRAPANI, STEFANO. "Task Oriented Programming and Service Algorithms for Smart Robotic Cells." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2743230.
Повний текст джерела
12
Gadea, Florent Xavier. "Theorie des hamiltoniens effectifs : applications aux problemes de diabatisation et de collision reactive." Toulouse 3, 1987. http://www.theses.fr/1987TOU30276.
Повний текст джерелаАнотація:
Etude approfondie sur la theorie des hamiltoniens effectifs et analyse de leurs applications aux methodes de diabatisation et au traitement des collisions reactives. Propositions pour le calcul des valeurs propres de l'hamiltonien par des methodes de perturbation ou iteratives, pour l'emploi d'hamiltoniens effectifs dans le calcul des surfaces quasi diabatiques et le traitement general des collisions reactives. Application a la reaction cs+h::(2) etudiee par les methodes ab initio pour la geometrie colineaire : surfaces de potentiel, sections efficaces et mecanismes predominants
13
Kelly, L. J. "The study of ion structures and their reaction chemistry by high-pressure source and collision induced decomposition mass spectrometry." Thesis, Swansea University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637774.
Повний текст джерелаАнотація:
This project has incorporated the use of mass spectrometric techniques to study the nature of protonated species, with respect to structure, thermodynamic properties, and their mechanism of formation. High-energy Collision Induced Decomposition (CID) has been used to probe the behaviour of these species as a function of reaction conditions, with the aim of determining the nature of the protonated species and the interconversion between closely related isomers. Pulsed high-pressure source mass spectrometry (PHPS-ms) has been used to investigate proton transfer equilibria in such systems. A detailed study of seven monoterpenes was undertaken using CID and PHPS-ms, along with semi-empirical theoretical calculations. This combination allowed determination of relative proton affinity data, showing good correlation between experiment and theory. In addition, study of the CI and CID spectra as a function of temperature, with the support of isotope labelling experiments and low-level theory, has given an insight into the most probable sites of protonation of each isomer. The varying CID spectra of these isomers highlight the importance of high-energy CID in studying effects of structural geometry on gas-phase reactivity, and provide evidence for a dependence on ion internal energy for some species. The protonation of ferrocene has been studied by high-energy CID-ms, providing the first experimental evidence for the existence of three protonated structures, ring-, metal-, and agostic “bridge”-protonated structures. Formation of the different protomers was found to be dependent on protonation exothermicity, with the different structures leading to different decompositions indicative of their structure. Finally, an extension to previous studies of protonated benzene was carried out, with the aim of corroborating previous data suggesting a face-centred protonated species. This investigation has shown the original interpretation to be wrong. The protonated benzene turns out to be yet another example of an ion whose CID spectrum is dependent on its internal rotational temperature.
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PALM, HARTMUT. "Etude des mecanismes de la reaction d'ions d'acetylene avec l'ethylene, en fonction de l'energie interne et de l'energie de collision." Paris 11, 1996. http://www.theses.fr/1996PA112107.
Повний текст джерелаАнотація:
Nous avons etudie les reactions d'ions d'acetylene avec le methane, l'ethylene et l'ethane en fonction de l'energie interne et de l'energie de collision. Ces reactions ion-molecule sont de bons exemples de systemes de petites molecules d'hydrocarbures qui permettent d'etudier la dynamique reactionnelle avec des molecules polyatomiques. Les ions reactants sont formes par photoionisation avec le rayonnement synchroton dans le domaine de l'ultraviolet lointain. On selectionne leur etat d'energie interne en utilisant la technique de coincidences entre photoelectrons de seuil et photoions. L'energie de collision peut varier depuis l'energie presque thermique jusqu'a 20 ev dans le systeme du laboratoire, en utilisant la technique des faisceaux d'ions guides. On a mesure les sections efficaces absolues de reaction en fonction de l'energie interne et de l'energie de collision. Les distributions en vitesse des ions produits ont ete obtenues a partir des spectres de temps de vol correspondants, provenant principalement de mesures effectuees avec l'appareil de faisceaux d'ions guides de chemmitz. Le marquage isotopique a ete utilise pour etudier le melange eventuel entre atomes d'hydrogene. La reaction d'ions d'acetylene avec l'ethylene donne trois ions produits aux faibles energies interne et collisionnelle (< 1 ev): c#2h#4#+ (transfert de charge), c#4h#5#+ et c#3hf393#+. C#4h#5#+ et c#3h#3#+ proviennent de la dissociation d'un complexe a longue duree de vie. La plupart des produits c#2h#4#+ proviennent d'un processus plus rapide qu'une periode de rotation (environ 1 ps). Un modele de ces reactions base sur des calculs statistiques rrkm/pst a donne des informations sur les etats de transition. La production de c#2h#3#+ est observee dans les trois systemes. Le transfert de h donnant ce produit passe par un complexe osculating sans melange total des atomes h et d. Il est neanmoins beaucoup moins efficace dans la reaction avec l'ethylene, a cause de la competition avec le transfert de charge. Cette etude confirme l'hypothese selon laquelle le transfert de proton passe par un complexe a relativement courte duree de vie et n'a lieu qu'apres isomerisation des ions d'acetylene en vinylidene
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Hikmet, Iskender. "Etude des collisions réactives entre atomes de cuivre et composés halogènes." Grenoble 1, 1991. http://www.theses.fr/1991GRE10126.
Повний текст джерелаАнотація:
Dans ce travail, nous avons etudie la reaction en phase gazeuse des atomes de cuivre dans l'etat fondamental cu(#2s#1#/#2, #2d#5#/#2) avec un compose halogene rx (x: f, cl, br, i) pour former la molecule cux a l'etat fondamental ou dans des etats electroniques excites. La spectroscopie d'emission (chimiluminescence) et la molecule cux excitee fournit beaucoup d'informations sur la repartition de l'energie disponible dans les differents etats de la molecule (electroniques, vibrationnels, rotationnels). Un pompage optique au moyen d'un laser a cuivre permet d'agir sur la concentration de chaque metastable #2d#3#/#2 et #2d#5#/#2 et de departager leur role dans la reaction (coefficient de reaction totale, repartition des populations). Les durees de vie des etats excites ont ete egalement mesurees. Une etude comparative entre les reactions des atomes de cuivres avec differents reactants rx montre que la repartition de l'energie des produits formes est differente dans chaque cas. Il semble qu'une distribution statistique soit favorisee en allant vers les halogenes plus lourds. Pour rendre compte des differents mecanismes de formation, nous proposons deux modeles de reaction: modele de harponnage et modele d'insertion. L'ensemble de cette etude a ete realise en utilisant la technique de post-decharge en ecoulement ou les produits de la reaction sont immediatement evacues. Cette technique permet de separer spatialement la zone de decharge de la zone d'injection du reactant de sorte que seuls les atomes de cuivre (#2d#1#/#2, #2d#3#/#2, #2d#3#/#2) interviennent dans la reaction etudiee
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McLaughlin, Shane Brendan. "Analytic Assessment of Collision Avoidance Systems and Driver Dynamic Performance in Rear-End Crashes and Near-Crashes." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/29561.
Повний текст джерелаАнотація:
Collision avoidance systems (CASs) are being developed and fielded to reduce the number and severity of rear-end crashes. Kinematic algorithms within CASs evaluate sensor input and apply assumptions describing human-response timing and deceleration to determine when an alert should be presented. This dissertation presents an analytic assessment of dynamic function and performance CASs and associated driver performance for preventing automotive rear-end crashes. A method for using naturalistic data in the evaluation of CAS algorithms is described and applied to three algorithms. Time-series parametric data collected during 13 rear-end crashes and 70 near-crashes are input into models of collision avoidance algorithms to determine when the alerts would have occurred. Algorithm performance is measured by estimating how much of the driving population would be able to respond in the time available between when an alert would occur and when braking was needed. A sensitivity analysis was performed to consider the effect of alternative inputs into the assessment method. The algorithms were found to warn in sufficient time to permit 50â 70% of the population to avoid collision in similar scenarios. However, the accuracy of this estimate was limited because the tested algorithms were found to alert too frequently to be feasible. The response of the assessment method was most sensitive to differences in assumed response-time distributions and assumed driver braking levels. Low-speed crashes were not addressed by two of the algorithms. Analysis of the events revealed that the necessary avoidance deceleration based on kinematics was generally less than 2 s in duration. At the time of driver response, the time remaining to avoid collision using a 0.5g average deceleration ranged from â 1.1 s to 2.1 s. In 10 of 13 crashes, no driver response deceleration was present. Mean deceleration for the 70 near-crashes was 0.37g and maximum was 0.72g. A set of the events was developed to measure driver response time. The mean driver response time was 0.7 s to begin braking and 1.1 s to reach maximum deceleration. Implications for collision countermeasures are considered, response-time results are compared to previous distributions and future work is discussed.Ph. D.
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Perkins, Thomas Edward James. "The effects of electronic quenching on the collision dynamics of OH(A) with Kr and Xe." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:5998e249-35ff-4d05-9c13-9b65d59b11d9.
Повний текст джерелаАнотація:
This thesis presents an experimental and theoretical study of the collision dynamics of OH(A2Σ+) with Kr and Xe. These two systems both exhibit a significant degree of electronically non-adiabatic behaviour, and a particular emphasis of the work presented here is to characterise the competition and interplay between electronic quenching on the one hand, and electronically adiabatic collisional processes on the other. Quenching takes place close to the bottom of the deepest potential well for both systems. In collisions that remain in the excited electronic state, this same region of the potential is also largely responsible for rotational energy transfer (RET) and the collisional depolarisation of angular momentum. Therefore, the direct competition between these processes suppresses the cross-sections for RET and collisional depolarisation from their expected value in the absence of quenching. To investigate this, experiments were carried out to measure cross-sections for the collisional transfer of electronic, vibrational and rotational energy in OH(A, v=0,1) + Kr and OH(A, v=0) + Xe. In addition, measurements were made of the j-j' correlation -- that is, the relationship between the angular momentum of the OH radical before and after a collision -- in collisions with Kr and Xe, using the experimental technique of Zeeman quantum beat spectroscopy. Collisions with both Kr and Xe tend to effectively depolarise the angular momentum of the OH radical, due to the very anisotropic character of the potential on which the process occurs. Electronic quenching, which plays an essential role in both systems, is more prevalent with xenon as the crossing to the ground state potential is located in a more accessible location. These experimental results were compared with single surface quasi-classical trajectory (QCT) calculations, where the overestimate of rotational energy transfer or collisional depolarisation helps to elucidate the degree to which the presence of quenching suppresses these processes. Surface hopping QCT was then used to account for non-adiabatic transitions in the theory, which led to an improvement in agreement with experiment. However, standard surface hopping QCT theory failed to account for the full extent of quenching in these two systems. A major focus of this work is therefore on the development of an extension to standard surface hopping QCT theory to incorporate rovibronic couplings. In non-linear configurations, the excited state of the OH + Kr, Xe systems has A' symmetry, while the ground state is split into symmetric (A') and antisymmetric (A'') components. For these symmetry reasons, coupling is restricted to the two states of the same symmetry, however a rotation of the correct (A'') symmetry can induce transitions to the A'' state too. Inclusion of all three electronic states, and the relevant couplings between them, is found to be crucial for a proper description of experimental reality.
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Lavaud, Franck. "Etude de la multifragmentation du systeme Au+Au entre 40 et 100 MeV/A: expansion et flot radial." Phd thesis, Université Paris Sud - Paris XI, 2001. http://tel.archives-ouvertes.fr/tel-00004100.
Повний текст джерелаАнотація:
Mon travail de thèse, concernant les collisions centrales Au+Au entre 40 et 100 MeV/A, se place dans le cadre d'une analyse comprenant le dépouillement et l'interprétation des résultats de la 4ème campagne de mesure du multidétecteur INDRA. La première phase de cette étude, dite de "dépouillement", a permis de reconstruire, à partir des données brutes des deux premiers étages de détection d'INDRA (chambre d'ionisation, Silicium), les énergies cinétiques et la charge des fragments détectés. Pour la première fois, il a été possible de mettre en évidence et de corriger les effets de non-linéarité dans la chaîne d'acquisition d'INDRA. A l'issue de ce travail, je me suis attaché à selectionner les collisions centrales.
Pour ce faire, et dans le souci de ne pas biaiser les interprétations physiques résultantes, j'ai mis en oeuvre deux méthodes distinctes: sélection en paramètre d'impact ainsi qu'une analyse en composante principale. Une étude comparative de ces deux outils mathématiques a été entreprise donnant lieu à des résultats très instructifs.
L'interprétation des résultats a fait appel à plusieurs types de modèles lesquels impliquant la validité de certaines hypothèses (équilibre thermodynamique, existence d'un volume de "freeze-out"). L'emploi de modèles statistiques (SMM, MMMC) a permis
d'extraire la taille du système émetteur, dit "source unique", ainsi que son énergie d'excitation. L'anisotropie des distributions en énergie cinétiques des fragments, a permis de
mettre en évidence, en fonction de l'énergie incidente de la collision, une déformation de la source, mais également de reconstruire les énergies thermique et collective entrant en jeu. Une nouvelle comparaison des données à l'aide de modèles dits "dynamique" (QMD,CMD) a été également entreprise. A l'issu de cette étude, des critiques portant sur la validité d'une approche telles SMM ou MMMC ont pu être émises remettant en jeu le fondement de l'interprétation physique du flot collectif couramment employé.
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Kerr, Samantha Louise. "Enhancing nucleic acid detection using inductively coupled plasma mass spectrometry, by means of metal and nano-particle labelling." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/4641.
Повний текст джерелаАнотація:
The application of ICP-MS to the fields of proteomics and genomics has arisen in part due to its ability to detect and quantify trace levels of S and P, which are major constituents in proteins and nucleic acids respectively. The development of collision/reaction cell technology and high resolution instruments has enabled these biologically important elements to be measured and quantified at the pg - ng ml-1 level. Despite these advances, the detection limits of P and S are still inferior compared to other elements. Oligonucleotides containing biotin functionality were labelled with Au nano-particles attached to a streptavidin protein to achieve site specific labelling, with 100% labelling efficiency. Each nano-particle contained ~86 Au atoms, resulting in an 882 fold signal enhancement for 24 base length oligonucleotides. However, this enhancement factor was only observed when one oligonucleotide bound to one nano-particle in a 1:1 ratio. Much lower Au labelling efficiencies and signal enhancements were observed when thiolated oligonucleotides were labelled with maleimide functionalised gold nano-particles. This was attributed to the extensive and difficult sample preparation steps that were required prior to labelling. The detection and quantification of adducts formed between DNA and the Pt anti-cancer drugs cisplatin and oxaliplatin were also investigated with ICP-MS. Acid digestion of the carbon based DNA matrix enabled Pt adducts to be quantified at low dose rates of 1 Pt atom per 1 500 000 nucleotides in ~12 μg DNA. Such sensitive mass spectrometric determinations could be employed in clinical tests to detect and quantify low level adducts formed in patients in-vivo. To complement ICP-MS analysis, electrospray ionisation linear ion trap mass spectrometry was employed to study the interaction of oxaliplatin with the four DNA nucleobases. Multiple stage mass spectrometry enabled detailed Pt-nucleobase adduct fragmentation pathways to be established. The method of DNA detection using P in conjunction with the collision cell, or cool plasma to form PO+ was also demonstrated and the limitations of the method, namely, polyatomic interferences and severe matrix effects were highlighted.
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Boutalib, Abderrahim. "Etude théorique de la surface de potentiel du système HO::(2) + H. : Influence de la corrélation électronique." Pau, 1986. http://www.theses.fr/1986PAUU3009.
Повний текст джерелаАнотація:
Calcul des géométries du points de sille et des barrières d'activation pour les réactions d'abstraction (HO::(2) + H->H::(2) + O::(2)) et d'approche concertée (HO::(2) + H->H::(2)O + O) pour la méthode SDCI à l'ordre d'une base DZ dans la région de valence, augmentée par des orbitales de polarisation de type D sur chaque atome O. Evaluation des paramètres cinétiques dans le cadre de la théorie de l'état de transition : énergies d'activation et constantes de vitesse. Faible probabilité du mécanisme de réaction concertée
21
Jones, Deanna M. Rago. "A study of ion-molecule reactions in a dynamic reaction cell to improve elemental analysis with inductively coupled plasma-mass spectrometry." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1180534215.
Повний текст джерела
22
Marsh, R. J. "Kinematic modelling of non reactive and reactive collisions." Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270740.
Повний текст джерела
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Barry, N. J. "Molecular beam studies of reactive collisions." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375059.
Повний текст джерела
24
Charvet, Michael. "Recherche de l'apparition du phénomène de multifragmentation dans le système 32S+27Al." Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10065.
Повний текст джерелаАнотація:
Le sujet de recherche presente dans ce memoire concerne la physique des ions lourds aux energies intermediaires, et plus precisement l'analyse du mode de desexcitation des systemes composites formes dans les collisions noyau-noyau. L'etude des noyaux chauds a mis en evidence la correlation qu'il existe entre l'energie deposee dans un systeme et son mode de desexcitation. Ainsi, a basse energie, les phenomene d'evaporation (emission de particules legeres de charge un ou deux) et d'emission binaire sequentielle (dont l'evaporation est un cas particulier) gouvernent le mode de desexcitation du systeme cree en voie de sortie. Lorsque l'energie croit, on observe l'apparition simultanee de fragments, dits de masse intermediaire (imf), dont la charge est superieure ou egale a trois. Ce phenomene, appele multifragmentation, fait aujourd'hui l'objet de nombreuses etudes car il pourrait refleter l'existence d'une transition de phase dans la matiere nucleaire. Ce travail s'inscrit dans le cadre d'une recherche du seuil d'apparition de ce phenomene. Pour ce faire, differentes experiences sur le systeme #3#2s+#2#7al ont ete realisees a l'aide du multidetecteur amphora, dans une gamme d'energie comprise entre 24,5 et 37,5 mev/nucleon. L'analyse des donnees, qui a largement fait appel aux techniques d'analyse multidimensionnelle developpees par le groupe (ces techniques permettant d'optimiser l'accord entre l'experience et la simulation), a permis de mettre en evidence un changement de mecanisme de desexcitation du systeme composite cree dans les collisions les plus centrales. A 24,5 mev/nucleon, les donnees sont compatibles avec un processus de desexcitation binaire sequentielle ; au dela, elles sont compatibles avec un processus de type multifragmentif, a ceci pres que l'on observe, experimentalement, un surplus d'energie cinetique pour les fragments. Ce surplus d'energie, incompatible avec un mecanisme purement thermique peut s'expliquer par la presence d'energie d'expansion dans nos echantillons. L'energie radiale extraite de nos donnees croit avec l'energie de bombardement : de 0 mev/nucleon a 24,5 mev/nucleon jusqu'a 0,8 mev/nucleon pour la plus grande energie faisceau.
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Maria, Aoun. "Development of Analytical methods for the evaluation of the impact of phosphate fertilizer industry on marine environment." Thesis, Pau, 2014. http://www.theses.fr/2014PAUU3033.
Повний текст джерелаАнотація:
Développement de méthodes analytiques pour l’évaluation de l'impact de l'industrie de fertilisants chimiques sur le milieu marinDevelopment of Analytical methods for the evaluation of the impact of phosphate fertilizer industry on marine environment
26
Paul, Dilip K. "Redox Reactions at Oil-Water Interface by Particle Collision Electroanalysis." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5406.
Повний текст джерелаАнотація:
Particle Collision Electrochemistry (PCE) has gained considerable attention in heterogeneous catalysis, petroleum chemistry and pharmaceutical fields. The PCE refers to a phenomenon in which a particle strikes on an inert electrode surface as a consequence of its Brownian motion and produces a spike of current for the direct oxidation/reduction of the individual particle. This method allows us characterization of individual particles and in-situ study of electrochemical reactions coupled to the particle.
Herein, emulsion droplets were studied by PCE where toluene droplets contained hydrophobic tetrachloro-1,4-benzoquinone (Q). This was investigated as a model system to study the molecular effects that arise due to hydrogen bonding reagents (oleic acid, acetic acid) inside and outside of the droplets. The emulsions were prepared by sonicating toluene-quinone solution with the water phase containing an ionic liquid to provide conductivity to the droplet. Each droplet produced a current spike while colliding with the electrode surface that was held at a potential to reduce tetrachoro-1,4-benzoquinone. In bulk acetonitrile and toluene, tetrachoro-1,4-benzoquinone undergoes a two electron reduction process to form the tetrachloro phenolate di-anion (Q2-). It was shown that the hydrogen bonding affinity of Q2- for acetic acid (pKa = 4.8) was higher than for oleic acid (pKa = 9.9) for both bulk systems (as acetic acid is stronger hydrogen bonding donor than oleic acid). However, the reversed trend was observed in emulsified toluene droplets when studied by PCE. This was attributed to the preferential partition of the carboxylic acids between the two phases in the emulsion. Oleic acid stays inside the droplets due its hydrophobic nature and hydrogen bonding with Q2- takes place inside the droplet. In contrast, solvation of acetic acid by the surrounding water, causes the hydrogen bonding with Q2- to occur significantly less inside the droplet.
Another redox system studied by PCE was hydrophobic ferrocene (Fc) trapped in the toluene droplet to determine the effect of surfactant on the particle size. The diameter determined electrochemically was compared with Dynamic Light Scattering (DSL) measurements. The presence of nonionic surfactant (triton X-100) was observed to affect the droplet’s size easily monitored by PCE. The mediated oxidation of cysteine by the oxidized Fc inside the droplet was investigated at different concentrations of cysteine.
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Rayner, Steven Phillip. "The stereodynamics of photo-initiated bimolecular collisions." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320636.
Повний текст джерела
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Ben, bouchrit Ridha. "Etude théorique des collisions moléculaires réactives de type atome + molécule polyatomique." Thesis, Besançon, 2015. http://www.theses.fr/2015BESA2037/document.
Повний текст джерелаАнотація:
Nous avons étudié les collisions réactives O(1D) + CH4 et O(1D) + H2O d’intérêt atmosphérique et astrophysique à l’aide de méthodes de chimie quantique et de dynamique réactionnelle. Pour la première réaction, des calculs de dynamique quantique à l’aide d’une méthode indépendante du temps ont été entrepris sur une surface d’énergie potentielle existante en considérant CH3 comme un pseudo-atome. Cette approche à dimensionnalité réduite, qualifiée ici de modèle pseudo-triatomique, a permis d’obtenir les probabilités de réaction à un moment angulaire total nul (J=0), puis de calculer les sections efficaces et les taux de réaction par une méthode approchée de type J-shifting. Nos résultats quantiques ont été comparés aux résultats obtenus par une méthode quasi-classique de trajectoires et aux prédictions expérimentales. Ces comparaisons ont, entre autre, validé le fait que la voie de sortie OH + CH3 était la voie principale pour cette réaction. La seconde réaction O(1D) + H2O a été abordée d’un point de vue structure électronique. Nous avons caractérisé les grandes lignes de la surface d’énergie potentielle de H2O2 en tenant compte de tous les degrés de liberté avec une méthode de calcul de haut niveau (MRCI : Multi Reference Configuration Interaction). Ainsi, nous avons pu déterminer avec une grande précision les géométries, les fréquences et les énergies des isomères du système H2O2 ainsi que son diagramme énergétique. A l’avenir, il faudra construire une surface d’énergie potentielle qui sera utilisée pour décrire la dynamique de cette réactionWe have studied the reactive collisions, O (1D) + CH4 and O (1D) + H2O, of atmospheric and astrophysical interest, using different quantum chemistry methods and reaction dynamics approaches. For the first reaction, quantum dynamical calculations using a time-independent method were carried out on an existing potential energy surface by considering CH3 as a pseudo-atom. This reduced dimensionality approach, i.e. a pseudo triatomic model, yielded the calculation of the reaction probabilities at zero total angular momentum (J = 0). The cross sections and reaction rates have been computed by the approximate J-shifting method. Our quantum results were compared with results obtained by a quasi-classical trajectory method and experimental predictions. These comparisons, among others, have enabled the fact that the channel CH3 + OH was the main exit channel for this reaction. The second reaction O(1D) + H2O has been studied at the level of electronic structure. We have characterized the outline of the potential energy surface of H2O2 , taking into account all the degrees of freedom at a high level calculation (MRCI: Multi Reference Configuration Interaction). Thus, we were able to determine with great accuracy the geometries, frequencies and energies of isomers of the H2O2 system and its energy diagram. In the future, a potential energy surface has to be built to be used in the dynamical calculations for this reaction
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Degen, Shane C. "Reactive image-based collision avoidance system for unmanned aircraft systems." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/46969/1/Shane_Degen_Thesis.pdf.
Повний текст джерелаАнотація:
Approximately 20 years have passed now since the NTSB issued its original recommendation to expedite development, certification and production of low-cost proximity warning and conflict detection systems for general aviation [1]. While some systems are in place (TCAS [2]), ¡¨see-and-avoid¡¨ remains the primary means of separation between light aircrafts sharing the national airspace. The requirement for a collision avoidance or sense-and-avoid capability onboard unmanned aircraft has been identified by leading government, industry and regulatory bodies as one of the most significant challenges facing the routine operation of unmanned aerial systems (UAS) in the national airspace system (NAS) [3, 4]. In this thesis, we propose and develop a novel image-based collision avoidance system to detect and avoid an upcoming conflict scenario (with an intruder) without first estimating or filtering range. The proposed collision avoidance system (CAS) uses relative bearing ƒÛ and angular-area subtended ƒê , estimated from an image, to form a test statistic AS C . This test statistic is used in a thresholding technique to decide if a conflict scenario is imminent. If deemed necessary, the system will command the aircraft to perform a manoeuvre based on ƒÛ and constrained by the CAS sensor field-of-view. Through the use of a simulation environment where the UAS is mathematically modelled and a flight controller developed, we show that using Monte Carlo simulations a probability of a Mid Air Collision (MAC) MAC RR or a Near Mid Air Collision (NMAC) RiskRatio can be estimated. We also show the performance gain this system has over a simplified version (bearings-only ƒÛ ). This performance gain is demonstrated in the form of a standard operating characteristic curve. Finally, it is shown that the proposed CAS performs at a level comparable to current manned aviations equivalent level of safety (ELOS) expectations for Class E airspace. In some cases, the CAS may be oversensitive in manoeuvring the owncraft when not necessary, but this constitutes a more conservative and therefore safer, flying procedures in most instances.
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Oueslati, Ichraf. "Etude théorique de la formation catalytique de petites molécules sur des modèles de grains interstellaires." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066074.
Повний текст джерелаАнотація:
L'hydrogène moléculaire est la molécule la plus abondante dans l'Univers. Il est reconnu que cette molécule ne peut se former que par un processus catalytique. Les études théoriques ont été menées très récemment sur la forstérite [010] cristalline et amorphe. C'est dans ce cadre que se situe notre étude qui porte sur les réactions de formation de l'hydrogène moléculaire sur des modèles de surfaces silicées et silicatées.Dans un premier temps, nous avons étudié la réaction d'abstraction par l'hydrogène atomique à partir du tétramethylsilane en phase gazeuse. La CVT incluant la correction SCT a été appliquée pour étudier la cinétique des réactions dans un intervalle de températures allant de 180 K à 2000 K. Etant donnée l'importance de l'effet tunnel à basse température, nous avons entrepris des calculs de dynamique quantique. Pour ce faire, une surface d'énergie potentielle en coordonnées hyper-sphériques a été construite. Le calcul quantique a été réalisé en utilisant une approche à dimensionnalité réduite à deux dimensions appliquée à ce problème de collision réactive colinéaire. Les résultats montrent que H2 est principalement formé dans son état vibrationnel fondamental. La comparaison avec les résultats expérimentaux réalisés dans le domaine de températures 425-570 K montre un accord satisfaisant. Une étude de formation de H2 sur des nanosilicates a été menée. Les méthodes de la DFT ont permis d'identifier les sites de physisorption et de chimisorption d'atomes d'hydrogène, d'étudier la diffusion de l'atome H physisorbé sur le cluster, de déterminer les caractéristiques énergétiques de ces sites et les énergies d'activation pour la désorption et la recombinaison de H2Molecular hydrogen is the most abundant molecule in the Universe. It was recognized long ago that the formation of molecular hydrogen most likely occurs on dust grains. Theoretical studies have focused on H2 formation mainly on model graphite surfaces and very recently on polycrystalline and amorphous foresterite [010]. It is within this framework that lies our study addressing the molecular hydrogen formation on new models of siliceous and silicateous surfaces. First, we studied the abstraction reaction by atomic hydrogen from tetramethylsilane in the gas phase. We used accurate methods of quantum chemistry based on the second-order perturbation theory and on the coupled clusters method. The KIEs and SKIEs were highlighted. CVT/SCT correction was applied to compute the reaction kinetics for a wide temperature range (180-2000 K). Given the importance of the quantum tunnelling effects at low temperatures, we investigated state-selected dynamics using quantum dynamics calculations. In order to achieve this purpose, a two-dimensional potential energy surface in the hyperspherical coordinates representation was built. Quantum calculations were performed using a reduced dimensionality approach applied to this collinear reactive collision problem. The comparison with the experimental results, performed within a temperature range between 425 and 570 K, shows a reasonable agreement.The H2 formation on nanosilicates, prototypes of silicate surfaces, was investigated. Using DFT, we identified physisorption and chemisorption sites for hydrogen atoms, then studied the diffusion of physisorbed hydrogen on the nanoclusters and calculated the energy properties and the activation energies for H2 recombination and desorption into the gas phase. Amorphous/porous grains with forsteritic composition tend to dissociate H2 and that the more crystalline/compact silicate grains would tend to catalyse H2 formation
31
Marinakis, Sarantos. "The dynamics of inelastic and reactive bimolecular collisions." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424735.
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Vandor, Balazs. "Effects of displays and alerts on subject reactions to potential collisions during closely spaced parallel approaches." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/23296.
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Bauge, Eric. "Collisions d'ions lourds aux énergies intermédiaires : étude de la dynamique d'émission des particules chargées et caractérisation des émetteurs." Université Joseph Fourier (Grenoble ; 1971-2015), 1994. http://www.theses.fr/1994GRE10086.
Повний текст джерелаАнотація:
Lors des collisions d'ions lourds aux energies intermediaires, une large gamme de processus de reaction est mise en jeu ; depuis des processus suffisamment lents pour qu'un equilibre soit atteint a chaque emission de particule, jusqu'a des processus directs, pour lesquels les diffusions nulceon-nucleon et le remplissage de l'espace de phase sont les effets dominants. Pour investiguer cette transition, nous avons etudie, a l'aide de mesures realisees dans le multidetecteur amphora et de simulations, a la fois la dynamique de desexcitation du systeme par emission de particules legeres, et les caracteristiques de l'emetteur de ces particules, ceci pour les systemes 7, 17, 27 et 34 amev, 40ar+al, 40ar+cu et 40ar+ag. Tout d'abord nous evaluons, pour ces systemes, le transfert d'impulsion lineaire des collisions les plus centrales en mesurant la vitesse des residus. Ensuite, en mesurant la fonction de correlation en angle azimutal de paires de particules legeres et en les comparant aux predictions d'un modele statistique nous evaluons le moment angulaire moyen de l'emetteur. Pour etudier la dynamique d'emission, nous comparons les resultats de simulations basees sur un modele de trajectoires classiques avec les fonctions de correlation experimentales en angle azimutal ou en impulsion relative. Enfin, nous examinons les predictions d'un modele buu avance pour le systeme 34amev 40ar+al
34
Quemet, Alexandre. "Contribution à la compréhension des réactions ion gaz dans les cellules de collision-réaction des ICP-MS : application à la résolution d'interférences isobariques et poly-atomiques." Thesis, Evry-Val d'Essonne, 2012. http://www.theses.fr/2012EVRY0021/document.
Повний текст джерелаАнотація:
La Spectrométrie de Masse par Plasma à Couplage Inductif (ICP-MS) s’est imposée comme technique d’analyse inorganique, de par sa souplesse d’utilisation, sa sensibilité et sa reproductibilité. L’analyse élémentaire et isotopique des combustibles nucléaires irradiés et de cibles de transmutation, doit faire face à un spectre de masse riche, dû à la présence de nombreux radionucléides. La technique ICP-MS ne peut toutefois pas différencier les ions de même masse ce qui induit des interférences isobariques et poly-atomiques quand les ions de même masse sont des espèces chimiques différentes. La majorité des ICP-MS de nouvelles générations sont équipés d’un dispositif de cellule de collision-réaction permettant la résolution in situ de telles interférences. Ce dispositif est un multipôle (quadripôle, hexapôle ou octopôle) rempli de gaz dont les molécules percutent les ions formés dans le plasma puis éventuellement réagissent. La résolution des interférences est alors basée sur la différence de réactivité chimique qui peut exister entre l’ion d’intérêt et son interférant, vis-à-vis d’un gaz de réaction donné : le choix du gaz est essentiel. Une meilleure compréhension des réactions « ions – gaz » pourrait ainsi aider à choisir le gaz réactif. Trois ICP-MS, avec différentes géométries de cellule de collision-réaction, ont été utilisés pour cette étude : Perkin Elmer Elan DRC e (quadripôle), Thermo Fischer X serie II (hexapôle) et Agilent Technologies 7700x (octopôle). L’influence de la géométrie de la cellule sur différents paramètres expérimentaux et sur la résolution de l’interférence poly-atomique 56Fe+/40Ar16O+ a été déterminée afin de mesurer le fer à l’état de trace ou d’ultra-trace. Cette étude préliminaire a ensuite été appliquée pour mesurer le fer en tant qu’impureté dans l’oxyde d’uranium, puis valider la méthode à l’aide d’un matériau de référence. La réactivité de métaux de transition (Zr, Ru, Pd, Ag, Cd, Sn), de lanthanides (La, Ce, Nd, Sm, Eu, Gd, Dy, Er et Yb) et d’actinides (U, Np, Pu, Am et Cm), éléments d’intérêts dans le domaine du nucléaire, a été testée vis-à-vis de nombreux gaz (O2, CO, CO2, N2O, NO, CH4, C2H4, C3H8, NH3, CH3Cl et COS). Parmi ces gaz, l’ammoniac est un gaz sélectif de lanthanides entre eux et aussi d'actinides. L’étude théorique, menée par des calculs DFT (Théorie de la Fonctionnelle de la Densité) et ab initio (MP2 et CCSD(T)) a permis de reproduire la différence de réactivité de quatre cations lanthanide (La+, Sm+, Eu+ et Gd+). Les chemins de réactions, les profils d’énergie potentielle, les orbitales moléculaires et l’influence de la configuration électronique le long du chemin de réaction ont permis de proposer une explication de la différence de réactivité observée. Quelques résultats expérimentaux et calculs de chimie quantique indiquent comment étendre ces explications aux actinidesInductively Coupled Plasma Mass Spectrometry (ICP-MS) emerged as the most essential technique in inorganic analytical chemistry thanks to its numerous assets, particularly its flexibility, its sensitivity and its reproducibility. As part of the elementary and isotopic analysis of irradiated fuel and transmutation target, the analyst is faced with a complex mass spectrum, due to the presence of many radionuclides. ICP-MS can not differentiate ions with the same mass, which induces isobaric and polyatomic interferences when the ions at the same mass are different chemical species. Last generations of ICP-MS have introduced collision reaction cells. It can in situ reduce these isobaric or polyatomic interferences. The cell is a multipol (quadrupole, hexapole or octopole) device filled with a collision and/or reaction gas. The gas molecules collide or possibly react with the ion beam, which eliminates or reduces interferences. Such resolution of interferences is based on the difference of chemical behaviours between the analyte and the interfering species: the choice of the gas is crucial. A better understanding of the “ion – gaz” reaction should help choosing the reacting gases. Three ICP-MS, with the different cell geometries, were used for this study: Perkin Elmer Elan DRC e (quadrupole), Thermo Fischer X serie II (hexapole) and Agilent Technologies 7700x (octopole). The effects of the cell geometry on different experimental parameters and on the resolution of the 56Fe+/40Ar16O+ polyatomic interferences were examined to measure iron at trace or ultra-trace level. This preliminary study was applied to measure iron as impurities in uranium oxide, the method was then validated with a Certified Reference Material. The reactivities of transition metals (Zr, Ru, Pd, Ag, Cd, Sn), lanthanides (La, Ce, Nd, Sm, Eu, Gd, Dy, Er and Yb) and actinides (U, Np, Pu, Am and Cm), elements of interest in the nuclear field, are studied with numerous gases (O2, CO, CO2, N2O, NO, CH4, C2H4, C3H8, NH3, CH3Cl and COS). Among these gases, ammonia appears to be a selective gas for lanthanides and actinides. DFT (Density Functional Theory) and ab initio calculations (MP2 and CCSD(T)) were able to reproduce the reactivity differences among lanthanide cations (La+, Sm+, Eu+ and Gd+). Reaction paths, potential energy surfaces, molecular orbitals and the influence of the electronic configuration along the reaction path are used to propose an explanation for the observed differences in the chemical behaviours. A few experimental results and quantum calculations indicate how to extend these explanations to actinides
35
Ferger, Neil Michael. "Some gas phase reactions of oxygen and halogen atoms under single collision conditions." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257953.
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Lange, Michael. "Competition between reaction channels in electron collisions of the hydrogen molecular ion HD+." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962794775.
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Francalanza, Laura. "Exploring Central Collisions in the Reaction 58Ni+48Ca at 25 AMeV with CHIMERA." Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/1715.
Повний текст джерелаАнотація:
In this PhD thesis it is presented the study concerning the competition of different reaction mechanisms in central collisions at Fermi energies, with particular interest on the onset of multifragmentation phenomena as a possible evolution of evaporative processes toward more explosive mechanisms.
This study has been carried out through the analysis of the 58Ni + 48Ca reaction at 25 AMeV, performed at the Laboratori Nazionali del Sud in Catania by the ISOSPIN and NUCL-EX collaborations in 2003 by using the CHIMERA multidetector.
As a main criterion for centrality selection we have chosen the event shape method, based on the construction of the kinetic energy tensor for the analysis of the configuration of the matter in the momentum space at the decay stage. It has been noticed how a cut on the shape variable "flow angle" (at 60 degrees) obtained by the diagonalization of the tensor resulted in a strong reduction of peripheral and semiperipheral less dissipative events, and in a very stringent selection of single compact sources, on an event by event basis.
This latter feature has been highlighted by the analysis of other event shape variables like the sphericity and the coplanarity and their correlations. Moreover, the main properties of the reaction products were explored by using different constraints on some of the relevant observables, like mass and velocity distributions and their correlations.
Much emphasis was devoted, for central collisions, to the competition between fusion-evaporation processes with subsequent identification of a heavy residue and a possible multifragmentation mechanism of a well defined (if any) transient nuclear system. A dominance of evaporative (sequential) mechanisms together with evidences of more fragmented processes has been highlighted and the two different contributions to emission have been firstly disentangled by a cut on the mass value of the heaviest fragment detected in each event (at A(1) = 40 amu) and then characterized.
Dynamical evolution of the system and pre-equilibrium emission were taken into account by simulating (with BNV calculations) the reactions in the framework of transport theories. Afterwards, the de-excitation of such sources was carried out by means of the SIMON code, that followed decay of the formed nuclei via binary sequential emissions of fragments and light particles.
Preliminary results show reasonable agreement with the assumption of sequential multifragmentation emission in the mass region of IMFs close to the heavy residues. Deviations from sequential processes were found for those IMFs in the region of masses intermediate between the mass of heavy residues and the mass of light IMFs. Such a region has been finally the object of a termodinamical analysis in terms of excitation energy estimation (both from calorimetric method and theoretical computations ) and apparent temperature evaluations through the isotopic ratio thermometer applied on light emitted nuclei (Li, Be and C): results are in quite in agreement with the existent systematic of excitation the energy and temperature correlation.
It could be very interesting to enlarge such analysis by studying the evolution of the reaction mechanisms with increasing of the incident energies and by investigating its isospin dependence. This will be possible by exploring those variables sensitive to the symmetry energy in the comparison with other systems as 58,62Ni+40,48Ca in the reactions at 25 AMeV and 35 AMeV carried out by the collaboration.
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Bhatti, Zaheer Ahmed. "Theoretical studies of collisional energy transfer in unimolecular reactions." Thesis, King's College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286244.
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Rashid, Shaan. "Dual-spray Synthesis and Reactions." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35726.
Повний текст джерелаАнотація:
By using two electrospray emitters containing different solutions (“dual-spray”) we have recently conducted in-source hydrogen/deuterium exchange (HDX) reactions and synthesized organometallic species. For dual-spray HDX reactions, peptide and protein solutions were electrosprayed through one emitter and the deuterating agent D2O through the secondary electrospray emitter. Clear shifts in isotope distributions indicated hydrogen-deuterium exchange occurring within the ion source. By ion mobility, simultaneous deuterium exchange for two isobaric species, the oxytocin monomer and dimer, was observed. Lysozyme has a linear relation between the charge state and the average number of exchanges, indicating that lysozyme becomes increasingly unfolded as the charge state increases. Based on deuterium uptake data and the lack of a temperature dependence, the dual-spray HDX reaction is thought to occur mostly in the gas phase. Tris(2,2’-bipyridine)ruthenium(II) and similar complexes containing the 1,10-phenanthroline ligand were formed by spraying a ligand solution and the ruthenium trichloride solution through two independent ESI emitters. This was confirmed by comparing ion mobility drift time, mass spectra, and CID fragmentation with the reference standard compounds. Tris(2,2’-bipyridine)iron(II), tris(1,10-phenantroline)iron(II) and mixed ligand complexes of iron(II) formed by dual-spray showed two additional hydrogens bonded to the complex. By CID, these unique gas phase complexes showed similar initial ligand loss to the reference standards however the secondary ligand loss showed dissimilar dissociation channels and energetics. Using DFT calculations, geometry optimizations for the [Fe(phen)3 + 2H]2+ complex and its fragment ions were done. After the initial ligand loss, the additional hydrogens are believed to transfer to the central iron atom. The relative energy of the dissociation channels showed good agreement with experimental breakdown curves.
40
Beck, Jonathan R. "Collision velocity dependence of products formed via surface induced dissociation /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3025601.
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41
Ta, C. T. "A theoretical study of charge-transfer reactions in collisions between identical ions." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378294.
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42
Xu, Yaodong. "Applications of mass spectrometric techniques to charge-transfer processes and cluster ion reactions." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/26208.
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43
Hughes, Dominic Wyndham. "The stereodynamics of photon-initiated bimolecular reactions." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299816.
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44
Gatchell, Michael. "Collision Induced Fragmentation of Molecules and Molecular Clusters : Knockout Driven Reactions in Fullerenes and PAHs." Licentiate thesis, Stockholms universitet, Fysikum, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-103501.
Повний текст джерелаАнотація:
This licentiate thesis covers experimental and theoretical studies of the fragmentation and sub- sequent reactions of fullerenes or Polycyclic Aromatic Hydrocarbons (PAHs). I present results from experiments where atoms or ions collide with fullerenes, PAHs, or clusters of these mole- cules at energies from 100 eV up to tens of keV. The results of these experiments are interpreted using quantum chemical calculations, mol- ecular dynamics simulations, and a stopping model that we have developed. With these models I show that different energy transfer processes dominate at different collision energies, from nuclear stopping in low energy (~ 100 eV) collisions to electronic stopping at higher energies (~ 10 keV). I particularly focus on non-statistical fragmentation induced by nuclear stopping which can lead to the formation of exotic new species such as the odd-numbered C119 fullerene- like molecule.
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Viquez, Rojas Oscar Alberto. "Evaluation of an acoustic detection algorithm for reactive collision avoidance in underwater applications." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83753.
Повний текст джерелаАнотація:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (page 33).
This thesis sought to evaluate a vehicle detection algorithm based on a passive acoustic sensor, intended for autonomous collision avoidance in Unmanned Underwater Vehicles. By placing a hydrophone at a safe distance from a dock, it was possible to record the acoustic signature generated by a small motor boat as it navigated towards, and then away from the sensor. The time-varying sound intensity was estimated by Root Mean Square of the sound amplitude in discrete samples. The time-derivative of the sound intensity was then used to estimate the time to arrival, or collision, of the acoustic source. The algorithm was found to provide a good estimate of the time to collision, with a small standard deviation for the projected collision time, when the acoustic source was moving at approximately constant speed, providing validation of the model at the proof-of-concept level.
by Oscar Alberto Viquez Rojas.
S.B.
46
Kassab, Emile. "Contribution à l'étude théorique de la réactivité des états excités de Rydberg de plus basse énergie de petits systèmes polyatomiques par des méthodes quantiques." Paris 6, 1987. http://www.theses.fr/1987PA066450.
Повний текст джерелаАнотація:
Etude théorique de la réactivité photochimique mono- et poly moléculaire des états de Rydberg infèrieurs de NH::(3), H::(2)O, CH::(4), alkylamines, alcools, radicaux méthyle, éthyle et ammonium de petits agrégats de NH::(3) ET NH::(3)-H::(2)O, de la photocyclodimèrisation de C::(2)H::(4), de l'extinction de l'état singulet excité de H::(2) par H::(2) à l'état fondamental, de la solvatation du radical NH::(4) dans un état de Rydberg par NH::(3), de l'interaction de H::(2) et HE avec NH::(3) excité, par la détermination des surfaces d'énergie potentielle par des méthodes ab initio quantitatives et des diagrammes de corrélation qualitatifs étendus aux états de Rydberg, en réunissant les différents concepts contenus dans les diagrammes de corrélation de l'atome unifié, dans le diagramme de Woodward Hoffmann, dans les règles de "topicité" et le concept de "rydbergnisation".
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Eyles, Chris J. "An experimental and theoretical study of the dynamics of atom-molecule scattering." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:d887db09-915e-4b3b-80e0-e9f1684518db.
Повний текст джерелаАнотація:
In this thesis, a joint experimental and theoretical study of the dynamics of atom- molecule collisions will be presented. The focus of this study will be conducted towards the precise, quantitative theoretical description of the collision dynamics in terms of the vectors k, k', j, and j' (the incoming and outgoing relative momenta associated with the collision, and the initial and final rotational angular momentum of the target diatom respectively) that define the collision, and on the experimental measurement of these vector correlations. Chapter 1 is introductory, providing an overview of the field of reaction dynamics, and the experimental and theoretical methods that exist to treat the collisions of atoms and molecules. This work focusses on the collisions of the spherically symmetric rare gas atoms Ar and He with the open-shell heteronuclear diatomic radicals NO and OH. In particular, the fully quantum state-to-state resolved differential cross-sections for the collisions of NO(X) with Ar (reflecting the k - k' vector correlation), and the collisional cross-sections for the depolarisation of the rotational angular momenta of the NO(A) and OH(A) radicals (reflecting the j - j' vector correlation) have been determined experimentally and theoretically, and the results have been discussed and interpreted in terms of the mechanistic aspects of the collision dynamics, and the features of the potential energy surface that give rise to these. In Chapter 2, the atom-molecule systems that constitute the subject of this work will be introduced in detail. The close-coupled quantum mechanical and quasi-classical trajectory scattering calculations performed as part of this work will be discussed in greater detail, providing a greater insight into molecular scattering theory. The explicit calculation of the quantities of interest (most significantly the differential cross-section, and the tensor/depolarisation cross-sections) will be presented for the quasi-classical and quantum cases, offering the most transparent definitions of these quantities. Finally the mathematical description of the spatial probability distribution of a single vector, a pair of correlated vectors, and three correlated vectors is described in detail, including a discussion of the quantum mechanical nature of the vectors in question. Chapter 3 describes the experimental measurement of the differential cross-sections for the collisions of NO(X) with Ar. A hexapole was used to select uniquely those NO molecules in the |Ω = 0.5; j = 0.5, f> quantum state, allowing full experimental quantum state-to-state selection for the first time. A crossed molecular beam apparatus with (1+1') resonantly enhanced multi-photon ionisation detection coupled with velocity mapped ion- imaging was employed to measure the differential cross-section, and the details of the experimental set-up are provided. The accurate extraction of the true, centre of mass frame differential cross-section from the laboratory frame information yielded by the experiment is something of an involved process, and much of this Chapter will be concerned with the development of a Monte Carlo method to achieve this end. In Chapter 4, the experimental and theoretical fully quantum state-to-state resolved differential cross-sections for the collisions of NO(X) with Ar are presented, having been measured for the first time. Full resolution of the initial parity of the rotational wave- function of the NO molecule has enabled the observation of parity dependent structures within the differential cross-section, and the origin of these structures has been investi- gated, employing quasi-classical, quantum mechanical and semi-classical methods in order to elucidate the mechanism by which they arise. Chapter 5 introduces the measurement of the collisional depolarisation of the rotational angular momentum of the diatom. Rate constants for the collisional depolarisation of j were measured by monitoring the time dependence of the amplitude of Zeeman and hyperfine quantum beats in the (1+1) laser induced fluorescence decays of an ensemble of NO(A) or OH(A) radicals in the presence of a series of background pressures of a collision partner. The creation and subsequent evolution of the polarisation of j induced by the absorption of polarised laser light is described, and the magnitude of this polarisation is linked to the amplitude of the quantum beat in the laser induced fluorescence decay. The extraction of the depolarisation cross-sections from the raw experimental data is discussed, and a Monte Carlo simulation of the experiment is described to account for any additional unwanted experimental factors that may contribute to the loss of polarisation of j. A formalism is also introduced that makes use of the tensor opacities to recover spin- rotation conserving and spin-rotation changing open-shell rotational energy transfer and depolarisation cross-sections from the intrinsically closed shell quasi-classical trajectory scattering calculations. In Chapter 6, the experimentally determined collisional depolarisation cross-sections for the collisions of NO(A) with He/Ar, and of OH(A) with Ar at collision energies of 39 meV/757meV are presented along with their theoretical counterparts. The relative magnitudes of the cross-sections are rationalised in terms of the potential energy surface over which the collision takes place, and the importance of spin-rotation conserving and spin-rotation changing transitions in the depolarisation process is assessed. A detailed study of the ensemble of quasi-classical trajectories is performed to determine the character of the various atom-molecule collisions, and to identify which conditions lead to the most efficient depolarisation of j. The relative importance of the potential energy surface and the collision kinematics is also assessed at this point. The results presented in this thesis thus investigate two complementary expressions of the collision dynamics, the k - k' and j - j' vector correlations, and encompass a variety of collision partners exhibiting vastly differing collision characteristics. As such, this work serves as an illustrative overview of atom-molecule scattering dynamics, containing both experimental and theoretical reflections of the collision dynamics, and relating this information back to the fundamentals of scattering theory.
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Barton, Robert Allan. "Multi-strange hyperon production in relativistic heavy -ion collisions." Thesis, University of Birmingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367744.
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RIAHI, KARIM. "Differentiation d'hydrocarbures aromatiques polycycliques isomeres par reactions ion-molecules, collisions dissociatives et reactives." Paris 6, 1999. http://www.theses.fr/1999PA066647.
Повний текст джерелаАнотація:
Les hydrocarbures aromatiques polycycliques (haps) sont ubiquistes dans l'environnement. Ils peuvent etre soit d'origine anthropogenique soit d'origine naturelle. Ils sont consideres comme des polluants prioritaires du fait de leur activite mutagene et/ou cancerigene, ce qui a conduit les scientifiques a les etudier afin de comprendre leur provenance, leur evolution ainsi que leur reactivite chimique en phase gazeuse. La spectrometrie de masse est un outil analytique puissant, sensible, specifique et bien adapte a l'etude de l'aspect fondamental des reactions ion-molecule en phase gazeuse. Differentes techniques en spectrometrie de masse ont ete utilisees comme l'impact electronique, l'ionisation chimique positive avec differents gaz reactants ainsi que les collisions dissociatives (cid) et reactives (car). Ces techniques ont permis d'etudier le comportement des haps en phase gazeuse et principalement de differencier les isomeres existants surtout ceux qui presentent des proprietes mutagenes differentes. La reactivite des haps en phase gazeuse evolue suivant deux principaux chemins traites ici : - les processus dissociatifs ou unimoleculaires (fragmentation, isomerisation) qui vont nous permettre d'etudier les differents chemins de fragmentations propres aux haps, la distribution de l'energie interne des differents ions formes ainsi que la nature des ions adduits (covalente ou non covalente). - les processus associatifs ou bimoleculaires (reactions ion-molecule) qui vont nous eclairer sur les reactions de transfert et d'echange de proton chez les haps par le biais de la reactivite des molecules protonees et des ions adduits avec des reactifs nucleophiles tels que l'ammoniac et l'ammoniac deuterie.
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Liu, Tingting. "Exclusive measurements with the spectrometer HADES in proton-proton reactions at 1. 25 GeV." Paris 11, 2010. http://www.theses.fr/2010PA112297.
Повний текст джерелаАнотація:
L'étude précise de la décroissance pionique et la première mesure de décroissance Dalitz de la résonance Δ(1232) sont obtenues par la collaboration HADES (High Acceptance Di-Electron Spectrometer) à GSI, Darmstadt. HADES a développé dans les dernières années un programme de réactions élémentaires visant à fournir une information sélective sur les différentes sources d'émission d'électrons en complément des expériences en ions lourds. Les mesures discutées dans cette thèse se réfèrent à l'étude des collisions proton-proton à une énergie de faisceau de 1. 25 GeV. Cette énergie, juste en dessous du seuil de production du η, est adaptée à l'étude de la décroissance DaIitz du Δ, qui est l'une des sources importantes d'émission d'électrons dans la région de masse intermédiaire (0. 15 GeV/c2The detailed study of the pionic decay and the first measurement of Dalitz decay of Δ(1232) resonance have been carried out with the High Acceptance Di-Electron Spectrometer (HADES) at GSI, Darmstadt. HADES developed in the last years an elementary reaction program aimed at providing selective information on different sources of di-electron emission as a complement to the heavy-ion experiments. The measurements discussed in this thesis refer to one experiment in this program, the study of proton-proton collisions at a kinetic beam energy of 1. 25 GeV. This energy is chosen just below the η production threshold and devoted to study the Δ Dalitz decay, which is one of the main sources of di-electron emission at intermediate e+e- invariant masses (0. 15 GeV/c2< Me+e-< 0. 5 GeV/c2). To provide a control of the cross sections and on the Δ resonance production mechanisms required by the study of the Δ Dalitz decay process, the full analysis of the pp→npπ+ at 1. 25 GeV has been performed, which is the main contribution of this PhD work. The results, such as the acceptance corrected mass and angular distributions of the pp→NΔ process and the Δ→Nπ decay angular distribution are shown and the comparisons to models are discussed. Another contribution of this PhD is a simulation study on helicity angle distributions, which was proposed on the one band as a support to the data analysis of the Δ Dalitz decay exclusive measurements and on the other hand as a reference to the preliminary results of helicity angle distribution obtained with inclusive e+e- in Ar+KCI collisions