Dissertations / Theses: 'Particle charging'

1

Hangsubcharoen, Monpilai. "A Study of Triboelectrification for Coal , Quartz and Pyrite." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/27447.

Full text

Abstract:

The separation efficiency of a triboelectrostatic separation (TES) for fine coal cleaning depends profoundly on the surface charges of the particles involved. In general, the larger the difference between the charges of the particle to be separated, the higher the separation efficiency. The premise that coal and mineral matter can be triboelectrically charged differently serves as a basis for the TES process. In order to improve the separation performance, it is apparent that a highly efficient charger is needed for the TES unit, as well as the information on the triboelectrification mechanisms of the coal and mineral matter. Tribo- or contact electrification is a phenomenon in which electrical charge is usually transferred form one material to another, when two dissimilar materials are brought into rubbing or contact. In the present work, the triboelectrification mechanisms of coal, quartz, and pyrite were investigated in an in-line static mixer charger. A new in-situ charge-measuring device has been developed, in which an in-line mixer charger is located in side a Faraday cage. This makes it possible to observe the charging mechanisms of the particles when they pass through the mixer. This device was used to study the tribocharging mechanisms of coal, quartz, and pyrite as functions of the air velocity, particle feed rate, particle size, temperature, ash content, and the work functions of the materials that make up the in-line mixer. Evidence suggests that the charge transfer mechanisms of coal and mineral matter be due to electrons. A new turbocharger designed and developed in the present study has been tested and used to investigate the triboelectrification mechanisms of coal and quartz. The charge measurements were conducted using a developed on-line charge-measuring device, which is based on the principle of the Faraday cage. The tribocharging mechanisms of coal and quartz were investigated as functions of the particle feed rate, particle size, rotor-blade rotation speed, ash content, and the type of the materials used to construct the turbocharger. The information on the charging mechanisms of the coal and quartz will be useful for improving the triboelectrification process and subsequently the design of a TES unit.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

2

Brown, Douglas 1955. "Theoretical study of particle charging and entrapment in a cylindrical ion beam." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277287.

Full text

Abstract:

A particle within an ion beam is subjected to positive and negative currents. These currents deposit a net charge on the particle which interacts with the potential of the beam. A model is presented which describes this charging, the time required to attain an arbitrary charge, and the resulting coulomb force. Confinement by the beam is investigated through comparison of the electric force to the opposing force of gravity. To quantify this comparison, a normalized force is defined which, when negative, predicts those spatial regions where particle entrapment can occur. Utilizing a specially written VAX-Fortran program, the behavior of this force was characterized as a function of beam parameters. Regions were predicted in which particle confinement can arise and it was found that the magnitude of the trapping force varied significantly with those parameters that affect the beam-ion density. Moreover, calculations of the charging time revealed that the time to attain the minimum trapping charge was sufficiently short so as not to preclude entrapment.

APA, Harvard, Vancouver, ISO, and other styles

3

Daryanani, Roshan D. "Potential distribution around dust particles in plasmas." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337811.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Wang, Pu. "Immersed Finite Element Particle-In-Cell Modeling of Surface Charging in Rarefied Plasmas." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/37368.

Full text

Abstract:

Surface charging is a fundamental interaction process in space plasma engineering. A three-dimensional Immersed Finite Element Particle-In-Cell (IFE-PIC) method is developed to model surface charging involving complex boundary conditions. This method extends the previous IFE-PIC algorithm to explicitly include charge deposition on a dielectric surface for charging calculations. Three simulation studies are carried out using the new algorithm to model current collection and charging in both the orbital motion limited (OML) and space charge limited regime. The first one is a full particle simulation of the charging process of single small sphere and clusters of multiple small spheres in plasma. We find that while single sphere charging agrees well with the predictions of the OML theory, the charging of a sphere in a cluster is significantly, indicating that the often used OML charging model is not an accurate one to model charging in dusty plasma. The second one concerns a secondary electron emission experiment. The simulation includes detailed experimental setup in a vacuum chamber and the results are compared against experimental data. The simulation is used to determine the facility error in experiments. The third one is a full particle simulation of charging on lunar surface. The simulation concerns both flat and non-flat surface, and spacecraft on lunar surface, in the lunar polar region. The surface sees a mesothermal solar wind plasma flow and the emission of photoelectrons and secondary electrons. At a small sun elevation angle, the surface landscape generates a complex plasma flow field and local differential charging on surface. The results will be useful for further study of charging and levitation of lunar dust.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

5

Barrie, Alexander. "Modeling Differential Charging of Composite Spacecraft Bodies Using the Coliseum Framework." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34743.

Full text

Abstract:

The COLISEUM framework is a tool designed for electric propulsion plume interactions. Virginia Tech has been developing a module for COLISEUM called DRACO, a particle-in-cell based code capable of plume modeling for geometrically complex spacecraft. This work integrates a charging module into DRACO. Charge is collected via particle impingement on the spacecraft surface and converted to potential. Charge can be stored in the surface, or added to a local ground potential. Current can flow through the surface and is governed by the internal electric field in the spacecraft.

Several test cases were run to demonstrate the code's capabilities. The first was a plume impingement of a composite spherical probe by a xenon thruster. It was shown that the majority of current conducted will reach the interior of the spacecraft, not other surface elements. A conductive interior will therefore result in a uniform surface potential, even for low surface conductivities. A second test case showed a composite spacecraft exposed to a solar wind. This test showed that when a potential gradient is applied to a conductive body, the ground potential of the spacecraft will lower significantly to compensate and maintain a zero net current. The case that used the semiconductive material showed that the effect of the potential gradient can be lowered in cases such as this, where some charge will always be stuck in the surface. If a dielectric material is used, the gradient will disappear altogether. The final test case showed the effect of charge exchange ion backflow on the potential of a spacecraft similar to the DAWN spacecraft. This case showed that CEX ion distribution is not even along the spacecraft and will result in a transverse potential gradient along the panel.
Master of Science

APA, Harvard, Vancouver, ISO, and other styles

6

Forward, Keith Mitchell. "Triboelectrification of Granular Materials." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1238090974.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Jeong, Hyunju. "Kinetic Simulations of Spacecraft Charging and Plasma Interactions in the Solar Wind." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/30237.

Full text

Abstract:

Analytical and numerical studies are carried out to investigate spacecraft charging and plasma interactions in the solar wind. The physics of spacecraft charging in solar wind is determined by the mesothermal flow and the photoelectron sheath. In order to properly resolve both plasma flow and the photoelectron sheath, a 3-D full particle PIC model is applied. In this model, all plasma species (ambient ions and electrons, and photoelectrons) are modeled as macro-particles so the detailed dynamics of each species can be resolved around a charged spacecraft. In order to correctly resolve the mesothermal velocity ratio, PIC simulations are carried out using the real ion to electron mass ratio. A charging model based on the capacitance matrix method is integrated into the PIC model so the floating potential can be calculated self-consistently with the PIC code from charges deposited on the surface. We first investigate the photoelectron sheath in the solar wind. Previous analytical studies of monotonic and non-monotonic sheath profiles in stationary electrons have suggested that there can exist two solutions of the sheath profiles when photoelectron emissions are significant. We extend the previous analytical approach to include the effects of drifting electrons. Full particle PIC simulations suggest that the non-monotonic sheath profile is the stable solution under solar wind conditions. We found that the current balance calculation is not an accurate method to predict the floating potential when photoelectron emissions are significant. We next apply the simulation model to study spacecraft charging under various solar wind conditions. Due to photoelectron emissions, spacecraft charging is typically not a serious problem. The floating potential is ~2.5V under the mean solar wind condition. We also investigate the plasma interactions of a multi-body system consisting of a large platform and a small free flyer in the absence of photoelectron emissions where we set a free flyer at 2*Debye length behind the platform in the wake. For the particular system studied in this dissertation, the simulation shows that wake charging is not severe under both the mean solar wind condition and severe magnetosheath charging condition.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

8

Liu, Qiaoling. "Ultrafine particle generation and measurement." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/3971.

Full text

Abstract:

Ultrafine particles (UFPs) with diameters smaller than 100 nm are omnipresent in ambient air. They are important sources for fine particles produced through the agglomeration and/or vapor condensation. With their unique properties, UFPs have also been manufactured for industrial applications. But, from the toxicological and health perspective, ultrafine particles with high surface-to-volume ratios often have high bio-availability and toxicity. Many recent epidemiologic studies have evidence UFPs are highly relevant to human health and disease. In order to better investigate UFPs, better instrumentation and measurement techniques for UFPs are thus in need. The overall objective of this dissertation is to advance out current knowledge on UFPs generation and measurement. Accordingly, it has two major parts: (1) ultrafine particle generation for laboratory aerosol research via electrospray (ES), and (2) ultrafine particle measurement for ambient aerosol monitor and personal exposure study via the development of a cost-effective and compact electrical mobility particle sizer. In the first part, to provide monodisperse nanoparticles, a new single capillary electrospray with a soft X-ray photoionizer as a charge reduction scheme has been developed. The soft X-ray effects on electrospray operation, particle size distribution and particle charge reduction were evaluated. To generate ultrafine particles with sufficient mass concentration for exposure/toxicity study, a TSE twin-head electrospray (THES) was evaluated, as well. The configuration and operational variables of the studied THES has been optimized. Three different nanoparticle suspensions were sprayed to investigate material difference. In the second part, to develop a miniature electrical mobility based ultrafine particle sizer (mini e-UPS), a new mini-plate aerosol charger and a new mini-plate differential mobility analyzer (DMA) have been developed. The performances of mini-plate charger and mini-plate DMA were carefully evaluated for ultrafine particles, including intrinsic/extrinsic charging, extrinsic charge distribution, DMA sizing accuracy and DMA transfer function. A prototype mini e-UPS was then assembled and tested by laboratory generated aerosol. Also a constrained least square method was applied to recover the particle size distribution from the current measured by a mini Faraday Cage aerosol electrometer.

APA, Harvard, Vancouver, ISO, and other styles

9

Salyer, Zachary M. "Identification of Optimal Fast Charging Control based on Battery State of Health." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587037951166857.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Hoshi, Kento. "Study on Active Spacecraft Charging Model and its Application to Space Propulsion Systeｍ." Kyoto University, 2018. http://hdl.handle.net/2433/232002.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Sprenger, Susanne [Verfasser]. "Interplay between charging effects and multi-particle transport in superconducting single electron transistors with tunable junctions / Susanne Sprenger." Konstanz : KOPS Universität Konstanz, 2020. http://d-nb.info/1213246881/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Janeski, John. "Dynamics of an Electrodynamic Tether System in a Varying Space-Plasma Environment." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23922.

Full text

Abstract:

Electrodynamic tethers have a wide range of proposed applications in the fields of satellite propulsion and space plasma research. The fundamental purpose of this dissertation is to improve the understanding of the behavior of an electrodynamic tether (EDT) system in Earth's ionosphere. An electrodynamic tether system consists of two satellites connected by a long tether that generates current to produce either power or thrust via the system's electromagnetic interaction with the space environment. Previous electrodynamic tether investigations decouple the interaction between the tether and the constantly changing plasma environment. The limiting factor inhibiting the development of a full system model that has an accurate characterization of the tether/plasma interaction is that the understanding of that interaction is not well developed over a wide range of system parameters. The EDT system model developed in this study uses a high fidelity dynamics model that includes a tether current described by an analytical current collection model whose plasma parameters are determine by the International Reference Ionosphere. It is first shown that new instabilities are induced in the system dynamics under a basic analytical current model versus a constant current model. A 2-D3$v$ Particle-in-Cell (PIC) code has been developed to study the plasma dynamics near a positively charged EDT system end-body and their impact on the current collected. Simulations are run over a range of system parameters that occur throughout a LEO orbit. The azimuthal current structures observed during the TSS-1R mission are found to enhance the current collected by the satellite when the magnetic field is slightly off of perpendicular to the orbital velocity. When the in-plane component of the magnetic field becomes large, the electrons are not able to easily cross the field lines causing plasma lobes form above and below the satellite. The lobes limit the current arriving to the satellite and also cause an enhanced wake to develop. A high satellite bias causes a stable bow-shock structure to form in the ram region of the satellite, which limits the number of electrons entering the sheath region and thus limiting the current collected. Electron-neutral collisions are found to destabilize the bow-shock structure and remove its current limiting effects. Additionally, as the magnetization of the plasma is increased, the current becomes limited by the charged particle's inability to cross magnetic field lines. Analytical curve fits based on the simulation results are presented that characterize the dependence of the average current collected on the local magnetic field orientations, space plasma magnetization and satellite potential. The results from the PIC simulations characterizing the magnetic field's influence on the tether's current are incorporated into the system dynamics model to study the behavior of the EDT system over a range of inclinations. The magnetic field is found to limit the diurnal variations in the current collected by the system throughout its orbit. As the inclination of the system's orbit is increased, the impact of the magnetic field becomes more pronounced as its orientation sweeps through a larger range of angles. The impact of the magnetic field on the collected current is, therefore, found to limit the ability of an EDT system to boost the system's orbit as the orbit's inclination is increased. In summary, new system dynamics have been observed due to the previously unobserved behavior of the current over a range of end-body configurations.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

13

Eboreime, Ohioma. "Numerical Modeling of the Novel Cross-Flow Electrostatic Precipitator." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1575646113189561.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Aghanifor, Ishmael. "Charging the use of studded tires in Stockholm city-A cost Benefit analysis." Thesis, http://www.eurafrika.com, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-37753.

Full text

Abstract:

The stockholm county proposed legislation in 2010 on the use of studded tires in the city. The aim of the policy was to reduce the use of studded tires by 50 percent. The research question investigates the authenticity of the policy where it was hypothesized that the net social benefits for the imposition of this charge was less than or equal to zero. Emperical literatures were chosen systematically and with the help of theories on welfare economics, a meta analysis was employed quantifying cost and benefits of all outcomes. The findings shows that the NSB is less than zero meaning that it was a wise decision to reject the proposal.

APA, Harvard, Vancouver, ISO, and other styles

15

Song, Di. "Study of Electrostatic Charging and Particle Wall Fouling in a Pilot-scale Pressurized Gas-Solid Fluidized Bed up to Turbulent Flow Regime." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36007.

Full text

Abstract:

In gas-solid fluidized beds, the generation of electrostatic charges due to continuous contacts between fluidizing particles, and the particles and the fluidization vessel wall, is unavoidable. Industrial operations, such as the production of polyethylene, are susceptible to significant operational challenges caused by electrostatics including reactor wall fouling, a problem known as “sheeting”. The formation of particle sheets can require shutdown periods for clean-up which results in significant economic losses. To gain a better understanding of the underlying mechanisms of electrostatic charging in gas-solid fluidized beds, in an attempt to eliminate or minimize this problem, a pilot-scale pressurized gas-solid fluidization system was designed and built, housing an online electrostatic charge measurement technique consisting of two Faraday cups. The system permits the study of the degree of particle wall fouling at pressures and temperatures up to 2600 kPa and 100°C, respectively, and gas velocities up to 1 m/s (covering a range including turbulent flow regime). The system also allowed, for the first time, the measurement of the fluidizing particles’ mass, net charge and size distribution in various regions of the bed, especially those related to the wall coating under the industrially relevant operating conditions of high pressures and gas velocities. Experimental trials were carried out using polyethylene resin received from commercial reactors to investigate the influence of pressure and gas velocity on the bed hydrodynamics and in turn, the degree of bed electrification. Mechanisms for particle charging, migration and adherence to the column wall were proposed. The size distribution of the gas bubbles shifted towards smaller bubbles as the operating pressure was raised. Thus, higher pressures lead to greater mixing within the bulk of the bed and resulted in a higher degree of particle wall fouling. Moreover, the extent of wall fouling increased linearly with the increase in gas velocity and as the bed transitioned to turbulent regime, due to the increase in particle-wall contacts. Bipolar charging was observed especially within the wall coating with smaller particles being negatively charged. Overall, particle-wall contacts generated negatively charged particles resulting in a net negative charge in the bed, whereas particle-particle contacts generated positively and negatively charged particles resulting in no net charge when entrainment was negligible. The formation of the wall layer and its extent was influenced by the gravitational and drag forces balancing the image force and Coulomb forces (created by the net charge of the bed and the metallic column wall as the attraction between oppositely charged particles).

APA, Harvard, Vancouver, ISO, and other styles

16

Pustylnik, M. Y., N. Ohno, S. Takamura, and R. Smirnov. "Modification of the damping rate of the oscillations of a dust particle levitating in a plasma due to the delayed charging effect." American Physical Society, 2006. http://hdl.handle.net/2237/8846.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Forouzan, Mohammad Mehdi. "Simulation and Experiments to Understand the Manufacturing Process, Microstructure and Transport Properties of Porous Electrodes." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6791.

Full text

Abstract:

Battery technology is a great candidate for energy storage applications. The need for high-performance and cost-effective batteries has motivated researchers to put much effort into improving battery performance. In this work, we attempt to understand the elements that affect the microstructure and performance of two battery systems. The first part of this work focuses on the investigation of transport and structural properties of porous electrodes in an alkaline electrolyte. A DC polarization method was deployed for tortuosity measurements. An apparatus was designed to flow specified current through and measure the voltage drop over the porous electrodes. Using a modified Ohm's law, effective diffusion coefficient and associated tortuosity were determined. Multiple compositions (different types and amounts of conductive additives) were tested to understand the effects of composition on the transport properties. As a validation and to further understand the tests, a model was developed and used for data analysis. The second part of this dissertation describes simulations of the manufacturing process of a Li-ion electrode. LAMMPS, a particle simulator, was used for this meso-scale particle-based simulation. The interactions between particles were understood by model-experiment comparisons of the macroscopic properties such as viscosity of the slurry and elasticity of the dried film. The microstructure created by this simulation was consistent with the one we observed in SEM/ FIB images. Although the emphasis was the drying process in this part, some preliminary coating and calendering simulations are presented. Finally, the effects of electrode heterogeneity were investigated by a Newman-type model and tomographic images. An electronic conductivity map was initially generated over a Li-ion cathode. Then SEM/FIB images of specified high, middle, and low conductivity regions were taken to confirm heterogeneity. For modeling purposes, three regions of high, middle, and low ionic resistance were considered connected in parallel, representing the real electrode heterogeneity. Multiple cases of heterogeneities such as non-uniform ionic resistance and active material loading at low, middle, and high charge-discharge rates were studied. The results show that higher rates increase non-uniformities of dependent properties such as temperature, current density, positive and negative electrodes states of charge, and charge and discharge capacities especially in charging cases.

APA, Harvard, Vancouver, ISO, and other styles

18

Kotian, Reshma. "Electrical Behavior of Non-Aqueous Formulations: Role of Electrostatic Interactions in Pressurized Metered Dose Inhalers (pMDIs)." Unavailable until 8/19/2013, 2008. http://hdl.handle.net/10156/2280.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Das, Subhankar. "Electrostatic charging and separation of fine particles." Poitiers, 2007. http://www.theses.fr/2007POIT2299.

Full text

Abstract:

L’objectif de ce travail a été double : améliorer la connaissance des facteurs qui influencent les processus de charge des particules < 1 mm et proposer desProcédés innovants pour la séparation des mélanges de matériaux pulvérulents fins. La méthodologie des plans d’expérience a été utilisée pour la modélisation du processus de charge triboélectrique de poudres dans des dispositifs pneumatiques. En utilisant la charge en champ couronne, il a été possible de mettre au point, un procédé destiné au recyclage des cendres issues des centrales thermoélectriques à charbon. La compréhension des phénomènes en jeu a été améliorée par la simulation numérique des trajectoires des particules. L’induction Electrostatique est le troisième mécanisme de charge dont l’efficacité a été prouvée expérimentalement. En Conclusion : le développement de nouveaux procédés de séparation pour des particules fines implique le choix du mécanisme de charge et du système d’électrodes les plus appropriés.

APA, Harvard, Vancouver, ISO, and other styles

20

Bau, Sébastien. "Étude des moyens de la surface des aérosols ultrafins pour l'évaluation de l'exposition professionnelle." Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL095N/document.

Full text

Abstract:

Ce travail s'inscrit dans le cadre de l'amélioration de la connaissance sur la mesure de la surface des aérosols ultrafins. En effet, l'essor des nanotechnologies peut être à l'origine de situations d'exposition professionnelle aux particules nanostructurées dispersées dans l'air, ce qui soulève une problématique nouvelle de prévention. Si à ce jour aucun des trois indicateurs (masse, surface, nombre) ne fait l'objet d'un consensus, il semble que le paramètre de surface des particules permet une bonne corrélation avec les effets biologiques observés lorsqu'elles sont inhalées. Un travail théorique original a donc été mené afin de positionner le paramètre de surface vis-à-vis d'autres grandeurs caractéristiques des aérosols. En vue de caractériser des méthodes de mesure de la surface des aérosols nanostructurés, le banc d'essais CAIMAN (CAractérisation des Instruments de Mesure des Aérosols Nanostructurés) a été dimensionné et réalisé. Celui-ci permet la production d'aérosols nanostructurés de propriétés variables et maîtrisées (taille, concentration, nature chimique, morphologie, état de charge), offrant une très bonne stabilité dans le temps. Les aérosols générés en laboratoire ont été utilisés en vue d'évaluer expérimentalement la réponse des instruments de mesure étudiés (NSAM & AeroTrak 9000 TSI, LQ1-DC Matter Engineering). Les fonctions de réponse expérimentales établies sur des aérosols monodispersés présentent un bon accord avec les courbes théoriques, dans une large gamme d'étude de 15 à 520 nm. Par ailleurs, des hypothèses ont été avancées en vue d'expliquer les écarts raisonnables observés lors des mesures effectuées sur des aérosols polydispersés
This work aims at improving knowledge on ultrafine aerosols surface-area measurement. Indeed, the development of nanotechnologies may lead to occupational exposure to airborne nanostructured particles, which involves a new prevention issue. There is currently no consensus concerning what parameter (mass, surface-area, number) should be measured. However, surface-area could be a relevant metric, since it leads to a satisfying correlation with biological effects when nanostructured particles are inhaled. Hence, an original theoretical work was performed to position the parameter of surface-area in relation to other aerosol characteristics. To investigate measurement techniques of nanostructured aerosols surface-area, the experimental facility CAIMAN (ChAracterization of Instruments for the Measurement of Aerosols of Nanoparticles) was designed and built. Within CAIMAN, it is possible to produce nanostructured aerosols with varying and controlled properties (size, concentration, chemical nature, morphology, state-of-charge), stable and reproducible in time. The generated aerosols were used to experimentally characterize the response of the instruments in study (NSAM & AeroTrak 9000 TSI, LQ1-DC Matter Engineering). The response functions measured with monodisperse aerosols show a good agreement with the corresponding theoretical curves in a large size range, from 15 to 520 nm. Furthermore, hypotheses have been formulated to explain the reasonable biases observed when measuring polydisperse aerosols

APA, Harvard, Vancouver, ISO, and other styles

21

Bagga, Payel. "Measurement of Electrostatic Dipoles and Net Charge on Air Dispersed Particles." Thesis, University of Canterbury. Chemical and Process Engineering, 2009. http://hdl.handle.net/10092/2992.

Full text

Abstract:

Dipoles are expected to often dramatically enhance the mutual collision rate of diffusing particles (above the effects of Brownian or turbulent motion). However, this spreading awareness of the possible influence of discrete dipoles on particles is still based largely on theory, and some qualitative experience of particle behaviour from microgravity experiments. Individual particle dipoles have not yet been definitely isolated in experiments, nor measured in practical situations. In this project, it was intended to measure, for the first time, distributions of dipole strength (as well as net charge and particle size) on particulates dispersed into air by typical industrial and pharmaceutical processing methods. The instruments designed to do this were built around a sampling head which allowed examination of a flow of dust dispersed into an air stream. During dispersal, the particles suffered tribocharging by mutual separation and collision on walls. Examination of the particles involved recording the path of particles as they moved through a non-uniform electric field around a central electrode, which was supplied with high voltage. Particles were attracted towards the central electrode (of 0.5 mm diameter in this study) if they contained dipoles, independent of the polarity of the field or their net charge. Particles to be examined were illuminated by a laser sheet as they moved past, and a high speed video captured their trajectories (over a field of view of around 5 mm). The equation of motion of a particle which involved the forces of both particle net charge and dipole strength was applied to the particle path to evaluate both these parameters. The particle trajectories were modelled, and checked against the observed experimental trajectories. The voltage applied to the probe varied from 4 kV to 18 kV but for most of the runs 6 kV voltage was used. The electric field around the probe tip was assumed to be same as that for a spherical electrode of the same size as the probe. The flow field axially towards and around the probe tip was calculated using the Stokes creeping flow equations around a sphere. The calculated electric and flow fields were checked against COMSOL Multiphysics models applied to actual geometries and flow regimes. The rotation dynamics of the particles was also considered important in the technique, requiring possibly extra knowledge of the initial direction of the dipole. The flow was led through a lateral field between two plates in order to orient the direction of any dipoles in the direction of the lateral field. The expected orientation of dipoles coming out of the plates was used as an initial guess of their orientation for modelling the rotation of the dipoles when they entered the probe field. Misalignment after leaving the plate field and before entering the probe field was also considered, and was found to be important due to vortices characterised by smoke and particle studies. However, the trajectory modelling revealed that the particles studied quickly rotated into alignment with the probe field, providing maximum attractive force to the probe, and so the values of net charge and dipole strength obtained did not depend on the initial orientation. Estimated errors of particle position and diameter used in all the calculation steps were judged to be well within a basic image error limit of ±1 pixel. Some particle trajectories showed unexplainable shapes which was traced to the influence of large mixing eddies around the gas/particle jet. A check for corona discharge at the probe tip was made both at the beginning and at the end of the sampling experiments. No corona was detected initially (up to 18 kV), but a discharge could be observed at voltages close to 7 kV in the later checks. Particles of acrylic, glass bubbles, whole milk and fertiliser powder were sampled and net charges and dipole charges were estimated. The sampled particles overall had net charge and dipole charge in the range of 10-15 C to 10-12 C on individual particles with diameters 20 μm -130 μm. Dipoles were more evident (more easily measured) for glass bubbles but the presence of dipoles on other particle samples was found and could not be completely ruled out for many of them. The analysis procedure is presently time consuming but can be automated so it is recommended in the future that it should be automated. The work can be extended into industrial situations by sampling moving dust suspensions, e.g. fluid bed overflows and pneumatically conveyed outflows, useful in the dairy and fertilizer industries.

APA, Harvard, Vancouver, ISO, and other styles

22

Butterworth, Sean. "Shape and chemical anisotropic particles in low dielectric constant media." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/shape-and-chemical-anisotropic-particles-in-low-dielectric-constant-media(d8ace7a1-8993-4a6b-a50d-2a2ea71c10f8).html.

Full text

Abstract:

Electrophoretic displays (EDPs) are an attractive low power technology for small to large area displays. Such display technology has seen a surge of research interest with the launch of successful e-readers in the market place, owing to their lower power consumption and paper-like quality. This work aims to look at the influence of shape on the electrophoretic mobility of particles for such devices. Crosslinked poly(methyl methacrylate) (PMMA) precursor particles with a narrow size distribution were produced by non aqueous dispersion polymerisation utilising a pump-feed method. To produce shape anisotropic particles an adapted version of the dynamic swelling method for polar media was chosen. Suitable monomers were screened by the use of Hansen solubility theory to find monomers which interact with PMMA but not the solvent. It was found that 2- hydroxyethyl methacrylate (HEMA) and N-hydroxyethyl acrylamide (HEAm) were two such suitable monomers, methyl methacrylate (MMA) was also used as a control series.It was found that cluster-like particle morphologies could be produced by the MMA system by the inclusion of small quantities of crosslinking monomer. This was due to precipitation of higher molecular weight polymer segments to the seed particle surface. The cluster-like morphology could be enhanced by use of a polar crosslinking monomer and by sequential reactions. For the polar system, it was found that the reactions with pure monomer were unclean, due to the solubility mismatch of the monomer and the solvent system. This was overcome by a copolymerisation with MMA. The system showed different particle morphologies could be produced by varying the polar monomer content. In one case a sample of pure dumbbell-like particles could be produced. These dumbbell-like particles are thought to be chemical as well as shape anisotropic owing to monomer composition. EPD evaluation for the particles was undertaken and showed that all particles can become highly charged in low dielectric constant media, but that the shape anisotropic particles are prone to adsorption to the cell walls and electrodes.The work outlined in this thesis shows the first reporting of shape anisotropic polymeric particles produced in low dielectric constant solvents system.

APA, Harvard, Vancouver, ISO, and other styles

23

Li, Yiming. "Determination of chargino and neutralino masses at the International Linear Collider." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:b67602fb-93c2-4986-a2a5-414f8c0dc5cd.

Full text

Abstract:

A feasibility study is presented which measures the masses of the chargino X̃₁^± and neutralinos X̃₁⁰ and X̃₂⁰ using the processes of e⁺e⁻→ X̃₁⁺X̃₁^- → X̃₁⁰X̃₁⁰W⁺W⁻ and e⁺e⁻→ X̃₂⁰X̃₂⁰ → X̃₁⁰X₁⁰ZZ at the International Linear Collider. The detector simulation is based on the Silicon Detector (SiD) concept and an integrated luminosity of 500 fb⁻¹ is considered at the centre-of-mass energy of 500 GeV. A template-fitting method is employed to measure the chargino and neutralino masses, which results in uncertainties of 0.16 GeV, 0.5 GeV and 1.0 GeV for the mass of X̃₁⁰, X̃₁^± and X̃₂⁰ respectively. A study on the ISIS2 sensor, a technology for the ILC vertex detector, is also presented. The characteristic of the sensors are studied for both its test structure and main array pixels. The operation conditions are optimized and the sensor successfully demonstrated its capabilities of in-situ charge storage and charge transfer. The charge transfer efficiency is measured to be better than 98%.

APA, Harvard, Vancouver, ISO, and other styles

24

Akatsuka, Shunichi. "Search for chargino and neutralino production using final states with two soft leptons in pp collisions at √s = 13 TeV." Kyoto University, 2020. http://hdl.handle.net/2433/253471.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Guo, Qiong. "Surfactants in nonpolar oils: agents of electric charging and nanogel templates." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43622.

Full text

Abstract:

This thesis studies the formation of mobile and surface-bound electric charges in nonpolar liquids. Unlike aqueous media with their natural abundance of charged species, liquids of low dielectric constant do not readily accommodate charges, but can do so in the presence of certain surfactant additives. Surfactant-mediated charging in nonpolar oils has long been exploited industrially, but the underlying charging mechanisms are far from understood. The present work seeks clarification by comparing the effect of ionic and nonionic surfactants on the conductivity of nonpolar solutions and the electrophoretically observable surface charge of suspended polymer particles. Both types of surfactant are found to generate mobile ions in solution as well as particle charge; and in the more surprising case of nonionic surfactants, the occurrence of particle charge and screening ions is confirmed independently by measurements of the electrostatic particle interaction energy. A systematic variation of the particle material and functionalization, the residual water content, and the surfactant concentration above and below the critical micelle concentration provides insights about the possible charging pathways. Reverse surfactant micelles are explored not only as charging agents, but also as reactors and templates for the synthesis of novel nanogels with promise for drug delivery. Synthesis via copper-free Click chemistry is shown to allow for better control of the particle size than a more conventional polymerization scheme, while avoiding metal catalysts and free radicals that are considered hazardous for most biomedical applications.

APA, Harvard, Vancouver, ISO, and other styles

26

Hart, Andrew Evan. "Search for disappearing tracks in proton-proton collisions at √s = 13 TeV." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1517587469347379.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Tylmad, Maja. "Search for Weakly Produced Supersymmetric Particles in the ATLAS Experiment." Doctoral thesis, Stockholms universitet, Fysikum, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-108060.

Full text

Abstract:

The Large Hadron Collider located at CERN is currently the most powerful particle accelerator and ATLAS is an experiment designed to exploit the high energy proton-proton collisions provided by the LHC. It opens a unique window to search for new physics at very high energy, such as supersymmetry, a postulated symmetry between fermions and bosons. Supersymmetry can provide a solution to the hierarchy problem and a candidate for Dark Matter. It also predicts the existence of new particles with masses around 1 TeV, thus reachable with the LHC. This thesis presents a new search for supersymmetry in a previously unexplored search channel, namely the production of charginos and neutralinos directly decaying to electroweak on-shell gauge bosons, with two leptons, jets, and missing transverse momentum in the final state. The search is performed with proton-proton collision data at a center of mass energy of √s = 8 TeV recorded with the ATLAS experiment in 2012. The design of a signal region sensitive to the new signal is presented and a data driven technique to estimate the Z+jets background is developed. Precise measurements of hadronic jet energies are crucial to search for new physics with ATLAS. A precise energy measurement of hadronic jets requires detailed knowledge of the pulse-shapes from the hadron calorimeter signals. Performance of the ATLAS Tile Calorimeter in this respect is presented using both pion test-beams and proton–proton collision data.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2 and Paper 4: Technical report from the ATLAS experiment.

APA, Harvard, Vancouver, ISO, and other styles

28

Lesné, Vincent. "Recherche de charginos et neutralinos dans le canal dimuon de même signe auprès de l'expérience Dphi-FNAL." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2006. http://tel.archives-ouvertes.fr/tel-00693958.

Full text

Abstract:

Dans le cadre du modèle mSUGRA qui décrit un mécanisme de brisure simple de la supersymétrie, des sparticules avec des masses au-delà des limites fixées par les expériences de LEP II peuvent être produites au Tevatron, collisionneur pp délivrant une énergie de 1.96Tev dans le centre de masse. Un canal privilégié pour la découverte de la supersymétrie au Tevatron est la production associée du plus chargé chargino, chi-+, et du second plus léger neutralino, chi 20. Les modes de désintégrations leptoniques, chi20->chi10l+l- et chi1+-->chi10l+-nul, conduisent à une signature claire avec trois leptons et une quantité significative d'énergie transverse manquante. De manière à augmenter la sensibilité au signal dans des régions de l'espace des paramètres conduisant à un troisième lepton très mou présentant une faible éfficacité de reconstruction, une sélection avec deux leptons de même signe et de l'énergie transverse manquante a été développée. Le cas particulier du canal dimuon de même signe est étudié dans ce manuscrit

APA, Harvard, Vancouver, ISO, and other styles

29

Mathieu, Romain. "Modélisation de l'influence de la rapidité de recharge totale ou partielle sur les performances électro-thermiques et la durée de vie des batteries pour applications automobiles." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0026.

Full text

Abstract:

La charge rapide des batteries est un enjeu majeur pour le développement de l’automobile électrique. Côté infrastructure, un déploiement de chargeurs de haute voire très haute puissance est en cours. Ces hautes puissances motivent une recherche sur les batteries, dans l’objectif de réduire significativement leurs durées de charge.Pour une cellule de batterie de caractéristiques données, la puissance de charge est limitée par des considérations électriques, thermiques et de durée de vie. Cette thèse souhaite alors apporter une contribution à la réduction du temps de charge, par une approche numérique de modélisation, simulation et optimisation. Elle compare également 4 références de cellules de différents matériaux et différentes densités d’énergie.Tout d’abord, des modèles du comportement électrique, thermique et de vieillissement d’une cellule sont développés séparément, puis couplés. De manière systématique, les modèles sont présentés, leurs procédures de calibration sont décrites, et ils sont comparés à des résultats expérimentaux. Une attention particulière est portée à l’effet des forts régimes de courant dans différentes conditions thermiques. Ceci a permis d’étendre leurs domaines de validité respectifs.Ensuite, une campagne de vieillissement accéléré est réalisée sur 3 références de cellules. Elle compare l’effet du courant de charge, de la tension de fin de charge et de différentes conditions thermiques sur la dégradation, dans le cadre d’un protocole de charge référence. Les résultats ont permis d’identifier plusieurs stratégies pour la réduction du temps de charge, au niveau du choix d’une référence de cellule, de la gestion thermique, et de l’optimisation du protocole de charge.Enfin, cette dernière stratégie est étudiée. Une méthode de définition par optimisation numérique d’un protocole de charge à plusieurs niveaux de courant constant est développée. Elle se base sur le modèle électro-thermique mis en place. La méthode est utilisée pour définir 5 protocoles de charge optimisés qui sont soumis à des essais de vieillissement accéléré. La dégradation est ensuite comparée à celle observée pour le protocole de charge référence. Dans des conditions comparables au protocole référence, les protocoles optimisés permettent de réduire le temps de charge et/ou la dégradation
Fast charging of batteries is a major challenge for the development of electric vehicles. A deployment of high power chargers is underway. These high power levels motivate research on batteries, with the aim of significantly reducing their charging times.For a battery cell of given characteristics, the charging power is limited by electrical, thermal and lifetime considerations. This thesis then wishes to make a contribution to the reduction of the charging time, by taking a numerical approach including modeling, simulation and optimization. It also compares 4 cell references of different materials and different energy densities.First, models of the electrical, thermal and aging behavior of a cell are developed separately, then coupled. In a systematic way, the models are presented, their calibration procedures are described, and they are compared with experimental data. Particular attention is paid to the effect of high current regimes under different thermal conditions. This made it possible to extend their respective domains of validity.Then, an accelerated aging campaign is carried out on 3 cell references. It compares the effect of the charging current, the end-of-charge voltage and different thermal conditions on the degradation, within the framework of a reference charging protocol. The results made it possible to identify several strategies for reducing the charging time, regarding the choice of a cell reference, thermal management, and the optimization of the charging protocol.This last strategy is finally studied. A method of definition of a charge protocol, containing several stages of constant current, is developed based on numerical optimization. The method makes uses the electro-thermal model implemented. It is then used to define 5 optimized charging protocols which are subjected to accelerated aging tests. The degradation is compared to that observed for the reference charging protocol. Under comparable conditions with the reference protocol, the optimized protocols make it possible to reduce the charging time and/or the degradation

APA, Harvard, Vancouver, ISO, and other styles

30

Konečný, Zdeněk. "Vliv oxidu titaničitého na vlastnosti olověných akumulátorů pracujících v režimu hybridních vozidel." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219871.

Full text

Abstract:

This work deals with lead-acid batteries operating in hybrid electric vehicles mode, i.e. in a partial state of charge. The adverse effects such as premature capacity loss and large internal resistance can markedly affect the life of a lead battery. The experiment described in this work aims to clarify the influence of the titanium dioxide in the active mass of negative electrodes especially in the life of lead acid batteries.

APA, Harvard, Vancouver, ISO, and other styles

31

呂紹豪, Shao-Hao Lu, and 呂紹豪. "Effect of a Unipolar Ion Jet Generator on Characterization of Particle Charging." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/zmve97.

Full text

Abstract:

碩士
國立臺北科技大學
環境工程與管理研究所
101
Nanoparticle (dp≦100 nm) charging plays an important role in both scientific studies and practical applications related to aerosols, such as nano-structure patterning, contamination control, and aerosol instrumentation. However, the average charges of nanoparticle might be below one elementary charge. Therefore, it is necessary to improve the charge efficiency of nanoparticle. A charge system was set up in this study, including aerosol generator system and unipolar ion generator. The objectives of this research were to study the average charges of particle, particle charge distribution, particle loss and ozone concentration at different ion air flow rate. The experiment results indicated that the charge of nanoparticle increased with increasing air flow rate. When the air flow rate was 2lpm, the charge of 20, 50, and 80nm particle was above one elementary charge. Besides, the +3 charges distribution of 80nm could be produced because of more ion attached to the larger surface area of particles. All the charged particle loss was less than 25% due to the image force. In addition, the coulomb force effect could be neglect as using the unipolar ion generator in this research. However, the unipolar ion generator had higher electric field that caused higher ozone concentration exhaust.

APA, Harvard, Vancouver, ISO, and other styles

32

Chan, Sheng-Kai, and 詹聖凱. "Effect of operating parameters on submicron particle agglomeration by bipolar charging system." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/68ss44.

Full text

Abstract:

碩士
國立臺北科技大學
環境工程與管理研究所
102
Electrostatic agglomeration is a technique which can let the particle agglomeration. Particles move and collide with each other as electric field is provided. The small particles are growing into a large one and the particle number concentration is decreased when particles agglomerate. The mechanisms of the electrostatic agglomeration include: (1) Particles are charged by two different polar corona chargers. (2) These particles oscillate in an alternating electric field, and then particle collide with each other. However, the agglomeration efficiency of submicron particle is not good as well. Therefore, an electrostatic agglomeration system was set up in this study. The objective of this research was to find out effect of operating parameters on submicron particle agglomeration by electrostatic agglomeration system. The experimental results indicated that count median diameter, count mean diameter and geometric mean diameter were increased as increasing bipolar charging voltage, alternating voltage, and agglomeration residence time. The submicron particle agglomeration efficiency was 12.2% and 15.8% for 16 and 21kV of alternating voltage, respectively, when residence time was 4.5 seconds and bipolar charging voltage was 7.5kV and -6.6kV, respectively. The submicron particle agglomeration efficiency was 11.2% and 15.8% for 2.25 and 4.5 seconds of residence time, respectively, when alternating voltage was 21kV and bipolar charging voltage was 7.5kV and -6.6kV, respectively. The ozone concentration was 100 ppb and 200 ppb as direct current of charger was 0.01mA and 0.02mA, respectively. The results indicated the formation of ozone concentration was caused by the current of charger. The yield of ozone concentration under alternating current of agglomeration was far less than direct current of charger.

APA, Harvard, Vancouver, ISO, and other styles

33

López-Yglesias, Xerxes F. "Physical Investigations of Small Particles: (I) Aerosol Particle Charging and Flux Enhancement and (II) Whispering Gallery Mode Sensing." Thesis, 2013. https://thesis.library.caltech.edu/7699/7/Lopez-Yglesias-XF-2013a.pdf.

Full text

Abstract:

Part I

Particles are a key feature of planetary atmospheres. On Earth they represent the greatest source of uncertainty in the global energy budget. This uncertainty can be addressed by making more measurement, by improving the theoretical analysis of measurements, and by better modeling basic particle nucleation and initial particle growth within an atmosphere. This work will focus on the latter two methods of improvement.

Uncertainty in measurements is largely due to particle charging. Accurate descriptions of particle charging are challenging because one deals with particles in a gas as opposed to a vacuum, so different length scales come into play. Previous studies have considered the effects of transition between the continuum and kinetic regime and the effects of two and three body interactions within the kinetic regime. These studies, however, use questionable assumptions about the charging process which resulted in skewed observations, and bias in the proposed dynamics of aerosol particles. These assumptions affect both the ions and particles in the system. Ions are assumed to be point monopoles that have a single characteristic speed rather than follow a distribution. Particles are assumed to be perfect conductors that have up to five elementary charges on them. The effects of three body interaction, ion-molecule-particle, are also overestimated. By revising this theory so that the basic physical attributes of both ions and particles and their interactions are better represented, we are able to make more accurate predictions of particle charging in both the kinetic and continuum regimes.

The same revised theory that was used above to model ion charging can also be applied to the flux of neutral vapor phase molecules to a particle or initial cluster. Using these results we can model the vapor flux to a neutral or charged particle due to diffusion and electromagnetic interactions. In many classical theories currently applied to these models, the finite size of the molecule and the electromagnetic interaction between the molecule and particle, especially for the neutral particle case, are completely ignored, or, as is often the case for a permanent dipole vapor species, strongly underestimated. Comparing our model to these classical models we determine an “enhancement factor” to characterize how important the addition of these physical parameters and processes is to the understanding of particle nucleation and growth.

Part II

Whispering gallery mode (WGM) optical biosensors are capable of extraordinarily sensitive specific and non-specific detection of species suspended in a gas or fluid. Recent experimental results suggest that these devices may attain single-molecule sensitivity to protein solutions in the form of stepwise shifts in their resonance wavelength, \lambda_{R}, but present sensor models predict much smaller steps than were reported. This study examines the physical interaction between a WGM sensor and a molecule adsorbed to its surface, exploring assumptions made in previous efforts to model WGM sensor behavior, and describing computational schemes that model the experiments for which single protein sensitivity was reported. The resulting model is used to simulate sensor performance, within constraints imposed by the limited material property data. On this basis, we conclude that nonlinear optical effects would be needed to attain the reported sensitivity, and that, in the experiments for which extreme sensitivity was reported, a bound protein experiences optical energy fluxes too high for such effects to be ignored.

APA, Harvard, Vancouver, ISO, and other styles

34

Ting-WeiChang and 張庭維. "Search for an Optimal Four-Stage Constant Current Charging Pattern for Li-Ion Batteries with Hybrid Taguchi-Particle Swarm Optimization." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/r6ydzt.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Chéreau, Xavier. "Recherche de charginos et de neutralinos avec le détecteur L3 au LEP." Phd thesis, 1998. http://tel.archives-ouvertes.fr/tel-00003063.

Full text

Abstract:

Ce travail de thèse présente une recherche expérimentale de particules supersymétriques, les
charginos et neutralinos, avec le détecteur L3 auprès du collisionneur e+e- LEP à une énergie
dans le centre de masse de s = 161, 172 et 183 GeV. Dans le cadre de la conservation de la
R-parité, les événements recherchés ont une énergie manquante significative emportée par la
plus legère des particules supersymétriques (LSP), ce qui permet de les distinguer des
événements standards. Pour cela, un ensemble de sélections qui optimisent le rapport
signal sur bruit est mis au point pour chaque type de signal à chaque énergie. L'absence
d'excès d'événements par rapport aux prédictions du modèle standard permet de mettre des
limites sur les sections efficaces de production des charginos et neutralinos. Interprétés
dans le cadre du MSSM contraint, ces resultats, combinés avec les recherches de sleptons
effectuées parallèlement dans la collaboration L3, permettent de mettre des limites inférieures
sur la masse des charginos et neutralinos ; en particulier, on exclut à 95% de niveau de confiance
un neutralino plus léger que 25.9 GeV/c2. Ceci a des conséquences importantes sur
l'interprétation de la matière cachée de l'univers. La recherche d'événements à énergie
manquante implique une bonne hermiticité du détecteur. A ce titre, fin 1995, un calorimètre
électromagnétique supplémentaire a été installé dans l'expérience L3. On présente l'utilisation,
l'amélioration des performances et la calibration de ce détecteur constitué de modules fait
en Plomb avec des fibres scintillantes (SPACAL).

APA, Harvard, Vancouver, ISO, and other styles

36

David, Claire. "Search for supersymmetry using a Higgs boson in the decay cascade with the ATLAS detector at the Large Hadron Collider." Thesis, 2016. http://hdl.handle.net/1828/7254.

Full text

Abstract:

The Standard Model of particle physics is a successful theory, yet it is incomplete. Supersymmetry is one of the favoured extensions of the Standard Model, elegantly addressing several unresolved issues. This thesis presents a search for the pair production of supersymmetric particles chargino one and neutralino two, where the neutralino two decays to the lightest neutralino and the 125 GeV Higgs boson. The final states considered for the search have large missing transverse momentum, an isolated lepton and two jets identified as originating from bottom quarks. The analysis is based on 20.3 inverse femtobarns of 8 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. No excess over Standard Model predictions is observed. The analysis has been combined with three independent searches that probe other decay modes of the Standard Model Higgs boson. Limits are set at 95% confidence level in the context of a simplified supersymmetric model. Common masses of chargino one and neutralino two are excluded up to 250 GeV for a massless neutralino one. The analysis of this dissertation has been reinterpreted in the context of a large scan of the phenomenological Minimal Supersymmetric Standard Model, along with 22 other ATLAS Run 1 searches. The resulting summary paper represents the most comprehensive assessment of the ATLAS constraints on Supersymmetry models to date.
Graduate
0798
cdavid@uvic.ca

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Particle charging'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles