Dissertations / Theses on the topic 'Process Physics'
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1
Gencoglu, Ahmet. "Physics based turning process simulation." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/36886.
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The manufacturing planning of parts is currently based on experience and physical test trials. The parts are modeled, and Numerically Controlled (NC) tool paths are generated in Computer Aided Manufacturing (CAM) environment. The NC programs are physically tested, and if the process faults are found, the NC program is re-generated in the CAM environment. The objective of this thesis is to develop Virtual Turning System that predicts the part machining process ahead of costly physical trials.
Tool–workpiece engagement geometry is calculated along the tool path by a proposed polycurve method. The part geometry is imported as a stereolithography (STL) model from the CAM system, and the cross section around the turning axis is reconstructed. The tool and part cross sections are modeled by polycurves, which are constructed by series of arcs and lines. The tool–part geometries are intersected using boolean operations to obtain the engagement conditions.
The turning process is modeled by predicting the chip area and equivalent chord angle. The process forces are modeled proportional to the material dependent cutting force coefficients, depth of cut and equivalent chord length that depends on the nose radius and approach angle of the tool. The chatter stability of the process is examined using Nyquist criterion at each tool–workpiece engagement station along the path.
The virtual turning simulation simulates the forces and detects the chatter stability, and adjusts the feeds at each tool-part engagement station. The physical turning of parts with arbitrary geometry can be simulated, and cutting conditions that leads to most optimal machining operation is automatically determined without violating the limits of the machine tool and part.
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Ma, Cynthia Kwai Wah. "Process causation and quantum physics." Thesis, London School of Economics and Political Science (University of London), 2001. http://etheses.lse.ac.uk/1609/.
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Philosophical analyses of causation take many forms but one major difficulty they all aim to address is that of the spatiotemporal continuity between causes and their effects. Bertrand Russell in 1913 brought the problem to its most transparent form and made it a case against the notion of causation in physics. The issue highlighted in Russell's argument is that of temporal contiguity between cause and effect. This tension arises from the imposition of a spectrum of discrete events occupying spacetime points upon a background of spacetime continuum. An immediate and natural solution is to superpose instead spatiotemporally continuous entities, or processes, on the spacetime continuum. This is indeed the process view of physical causation advocated by Wesley Salmon and Phil Dowe. This view takes the continuous trajectories of physical objects (worldlines) as the causal connection whereby causal influences in the form of conserved quantities are transported amongst events. Because of their reliance on spatiotemporal continuity, these theories have difficulty when confronted with the discontinuous processes in the quantum domain. This thesis is concerned with process theories. It has two parts. The first part introduces and criticizes these theories, which leads to my proposal of the History Conserved Quantity Theory with Transmission. The second part considers the extension of the idea of causal processes to quantum physics. I show how a probability distribution generated by the Schrodinger wavefunction can be regarded as a conserved quantity that makes the spacetime evolution of the wavefunction a quantum causal process. However, there are conceptual problems in the interpretation of the wavefunction, chiefly to do, as I shall argue, with the difference in the behaviours of probabilistic potentials between quantum and classical physics. I propose in the final chapter, the Feynman Path Integral formulation of quantum mechanics (with the Feynman histories) as an alternative approach to incorporating the probabilistic potentials in quantum physics. This account of how to introduce causal processes in quantum mechanics fares better, I claim, than the previous one in dealing with the situational aspect of quantum phenomena that requires the consideration of events at more than one time.
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Court, Steven James. "Physics of biological evolution." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9975.
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Part I: A remarkable feature of life on Earth is that despite the apparent observed diversity, the underlying chemistry that powers it is highly conserved. From the level of the nucleobases, through the amino acids and proteins they encode, to the metabolic pathways of chemical reactions catalyzed by these proteins, biology often utilizes identical solutions in vastly disparate organisms. This universality is intriguing as it raises the question of whether these recurring features exist because they represent some truly optimal solution to a given problem in biology, or whether they simply exist by chance, having arisen very early in life's history. In this project we consider the universality of metabolism { the set of chemical reactions providing the energy and building blocks for cells to grow and divide. We develop an algorithm to construct the complete network of all possible biochemically feasible compounds and reactions, including many that could have been utilized by life but never were. Using this network we investigate the most highly conserved piece of metabolism in all of biology, the trunk pathway of glycolysis. We design a method which allows a comparison between the large number of alternatives to this pathway and which takes into account both thermodynamic and biophysical constraints, finding evidence that the existing version of this pathway produces optimal metabolic fluxes under physiologically relevant intracellular conditions. We then extend our method to include an evolutionary simulation so as to more fully explore the biochemical space. Part II: Studies of population dynamics have a long history and have been used to understand the properties of complex networks of ecological interactions, extinction events, biological diversity and the transmission of infectious disease. One aspect of these models that is known to be of great importance, but one which nonetheless is often neglected, is spatial structure. Various classes of models have been proposed with each allowing different insights into the role space plays. Here we use a lattice-based approach. Motivated by gene transfer and parasite dynamics, we extend the well-studied contact process of statistical physics to include multiple levels. Doing so generates a simple model which captures in a general way the most important features of such biological systems: spatial structure and the inclusion of both vertical as well as horizontal transmission. We show that spatial structure can produce a qualitatively new effect: a coupling between the dynamics of the infection and of the underlying host population, even when the infection does not affect the fitness of the host. Extending the model to an arbitrary number of levels, we find a transition between regimes where both a finite and infinite number of parasite levels are sustainable, and conjecture that this transition is related to the roughening transition of related surface growth models.
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Turner, Mark J. "A study of the exotic-atom cascade process." Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/848141/.
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Klinger, Christopher Martin, and chris klinger@unisa edu au. "Process Physics: Bootstrapping Reality from the Limitations of Logic." Flinders University. SoCPES, 2005. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20080430.132508.
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For all the successes of the two edifices of modern physics, quantum theory and Einstein's relativity, a fundamental description of the Universe as a whole -- a theory that informs as to the true nature of reality -- has continued to elude science. This thesis describes the development and evolution of a new paradigm called Process Physics, a radical information-theoretic modelling of reality. It is argued that the failure of the extant approaches in physics is the direct consequence of limitations stemming from the mathematization, language and methodology of theoretical physics: the limitations of the postulated background spatial concepts and geometric modelling of time, the limitations of quantum theory in its failure to account for the measurement process and classicality; and the limitations of formal systems. In contrast, Process Physics utilizes the limitations of logic first identified by Godel and asserts the priority of process and relational endophysics, realized via a stochastic, autopoietic bootstrap system whose properties emerge a posteriori rather than being assumed a priori. The work is arranged in two parts. Part I discusses the historical, philosophical, and metaphysical foundations of physics to consider how the prevailing views in modern physics arose and what this revealed and contributed to the development of Process Physics. Part II describes the fundamentals of the new theory and its implementation, and demonstrates the viability of looking outside the current paradigms by showing that Process Physics yields unified emergent phenomena that permit an understanding of fundamental processes and penultimately motivate both quantum theory and relativity as relevant higher-level descriptors within their respective domains.
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Goriely, Stephane. "Some nuclear physics aspects of the r-process nucleosynthesis." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293481.
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Hess, Shelby Kimmel. "Cumulative effects in quantum algorithms and quantum process tomography." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/100678.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 129-134).
This thesis comprises three results on quantum algorithms and quantum process tomography. In the first section, I create a tool that uses properties of the quantum general adversary bound to upper bound the query complexity of Boolean functions. Using this tool I prove the existence of O(1)-query quantum algorithms for a set of functions called FAULT TREES. To obtain these results, I combine previously known properties of the adversary bound in a new way, as well as extend an existing proof of a composition property of the adversary bound. The second result is a method for characterizing errors in a quantum computer. Many current tomography procedures give inaccurate estimates because they do not have adequate methods for handling noise associated with auxiliary operations. The procedure described here provides two ways of dealing with this noise: estimating the noise independently so its effect can be completely understood, and analyzing the worst case effect of this noise, which gives better bounds on standard estimates. The final section describes a quantum analogue of a classical local search algorithm for Classical k-SAT. I show that for a restricted version of Quantum 2-SAT, this quantum algorithm succeeds in polynomial time. While the quantum algorithm ultimately performs similarly to the classical algorithm, quantum effects, like the observer effect, make the analysis more challenging.
by Shelby Kimmel.
Ph. D.
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Puthoor, Ittoop Vergheese. "Theory and applications of quantum process calculus." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/5986/.
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Formal methods is an area in theoretical computer science that provides the theories and tools for describing and verifying the correctness of computing systems. Usually, such systems comprise of concurrent and communicating components. The success of this field led to the development of quantum formal methods by transferring the ideas of formal methods to quantum systems. In particular, formal methods provides a systematic methodology for verification of systems. Quantum process calculus is a specialised field in quantum formal methods that helps to describe and analyse the behaviour of systems that combine quantum and classical elements. We focus on the theory and applications of quantum process calculus in particular to use Communicating Quantum Processes (CQP), a quantum process calculus, to model and analyse quantum information processing (QIP) systems. Previous work on CQP defined labelled transition relations for CQP in order to describe external interactions and also established the theory of behavioural equivalence in CQP based on probabilistic branching bisimilarity. This theory formalizes the idea of observational indistinguishability in order to prove or verify the correctness of a system, and an important property of the equivalence is the congruence property. We use the theory to analyse two versions of a quantum error correcting code system. We use the equational theory of CQP from the previous work and define an additional three new axioms in order to analyse quantum protocols comprising quantum secret-sharing, quantum error correction, remote-CNOT and superdense coding. We have expanded the framework of modelling in CQP from providing an abstract view of the quantum system to describe a realistic QIP system such as linear optical quantum computing (LOQC) and its associated experimental processes. By extending the theory of behavioural equivalence of CQP, we have formally verified two models of an LOQC CNOT gate using CQP. The two models use different measurement semantics in order to work at different levels of abstraction. This flexibility of the process calculus approach allows descriptions from detailed hardware implementations up to more abstract specifications. The orbital angular momentum (OAM) property of light allows us to perform experiments in studying higher dimensional quantum systems and their applications to quantum technologies. In relation to this work, we have extended CQP to model higher dimensional quantum protocols.
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King, J. R. "Mathematical aspects of semiconductor process modelling." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375274.
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Lloyd, Christopher James. "Diffusing wave spectroscopy applied to material analysis and process control." Thesis, Open University, 1997. http://oro.open.ac.uk/54375/.
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Diffusing Wave Spectroscopy (DWS) was studied as a method of laboratory analysis of submicron particles, and developed as a prospective in-line, industrial, process control sensor, capable of near real-time feedback. No sample pre-treatment was required and measurement was via a noninvasive, flexible, dip in probe. DWS relies on the concept of the diffusive migration of light, as opposed to the ballistic scatter model used in conventional dynamic light scattering. The specific requirements of the optoelectronic hardware, data analysis methods and light scattering model were studied experimentally and, where practical, theoretically resulting in a novel technique of analysis of particle suspensions and emulsions of volume fractions between 0.01 and 0.4. Operation at high concentrations made the technique oblivious to dust and contamination. A pure homodyne (autodyne) experimental arrangement described was resilient to environmental disturbances, unlike many other systems which utilise optical fibres or heterodyne operation. Pilot and subsequent prototype development led to a highly accurate method of size ranking, suitable for analysis of a wide range of suspensions and emulsions. The technique was shown to operate on real industrial samples with statistical variance as low as 0.3% with minimal software processing. Whilst the application studied was the analysis of Ti02 suspensions, a diverse range of materials including polystyrene beads, cell pastes and industrial cutting fluid emulsions were tested. Results suggest that, whilst all sizing should be comparative to suitable standards, concentration effects may be minimised and even completely modelled-out in many applications. Adhesion to the optical probe was initially a significant problem but was minimised after the evaluation and use of suitable non stick coating materials. Unexpected behaviour in the correlation in the region of short decay times led to consideration of the effects of rotational diffusion coefficient. The inherent instability of high density suspensions instigated high speed analysis techniques capable of monitoring suspensions that were undergoing rapid change as well as suggesting novel methods for the evaluation of the state of sample dispersion.
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Lin, Dacheng. "The accretion process in neutron-star low-mass X-ray binaries." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/62866.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 207-221).
There had been long-standing fundamental problems in the spectral studies of accreting neutron stars (NSs) in low-mass X-ray binaries involving the X-ray spectral decomposition, the relations between subtypes (mainly atoll and Z sources), and the origins of different X- ray states. Atoll sources are less luminous and have both hard and soft spectral states, while Z sources have three distinct branches (horizontal(HB)/normal(NB)/flaring(FB)) whose spectra are mostly soft. I analyzed more than twelve-year RXTE observations (~ 2500 in total) of four atoll sources Aql X-1, 4U 1608-522, 4U 1705-44, and 4U 1636-536. I developed a hybrid spec- tral model for accreting NSs. In this model, atoll hard-state spectra are described by a single-temperature blackbody (BB), presumed to model emission from the boundary layer where the accreted material impacts the NS surface, and a strong Comptonized compo- nent, modeled by a cutoffpl power law (CPL). Atoll soft-state spectra are described by two thermal components, i.e., a multicolor disk (MCD) and a BB, with additional weak Comp- tonized component, modeled by a single power law. I found that the accretion disk in most of the soft state is truncated at a constant value, most probably at the innermost stable circular orbit (ISCO), predicted by general relativity. This allows us to derive upper limits of magnetic fields on the NS surface of the above four atoll sources. The apparent emission area of the boundary layer is small, ~1/16 of the whole NS surface, but is fairly constant, spanning the hard and soft states. All this was not seen if the classical models for thermal emission plus high Comptonization were used instead. By tracking the accretion rate onto the NS surface, I inferred a strong mass jet in the hard state. My study of 4U 1705-44 using broadband spectra from Suzaku and BeppoSAX supported the above results. From my spectral study of the above four atoll sources, I also found that in a part of the soft state with frequent occurrences of kilohertz quasi-periodic oscillations (kHz QPOs), the accretion disk appears to be truncated at larger radii than in other parts of the soft state where the disk is presumably truncated at the ISCO. Thus the production of kHz QPOs in accreting NSs should be closely related to the behavior of the accretion disk. It is well known that the kHz QPO amplitude spectrum tracks the BB, even though we see no changes in the BB spectral evolution track when kHz QPOs are present. The simplest interpretation is that accretion oscillations are imparted in the inner disk and then seen as the waves impact the NS surface in the boundary layer. The transient XTE J1701-462 (2006-2007) is the only source known to exhibit properties of both the Z and atoll types. I carried out the state/branch classifications of all the ~900 RXTE observations. The Z-source branches evolved substantially in the X-ray color-color diagram during this outburst. In the decay, the HB, NB and FB disappeared successively, with the NB/FB transition evolving to the atoll-source soft state. Spectral analyses using my new spectral model show that the inner disk radius maintains at a nearly constant value, presumably at ISCO, when the source behaves as an atoll source in the soft state, but increases with accretion rates when the source behaves as a Z source at high luminosity. We interpreted this as local Eddington limit effects and advection domination in the accretion disk. The disks in the two Z vertices probably represent two stable accretion configurations, and we speculate that the lower (NB/FB) vertex represents a standard thin disk and the upper (HB/NB) vertex a slim disk. The changes in the accretion rate are responsible for movement of Z-source branches and the evolution from one source type to another. However, the three Z-source branches are caused by three mechanisms that operate at a roughly constant accretion rate. The FB is an instability tied to the Eddington limit. It is formed as the inner disk radius temporarily decreases toward the ISCO. The NB is traced out mostly due to changes in the boundary layer emission area, as a result of the system transiting from a standard thin disk to a slim disk. The HB is formed with the increase in Comptonization, consistent with strong radio emission detected from this branch.
by Dacheng Lin.
Ph.D.
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Dhina, Mourad. "A study of the process e⁺e⁻ [arrow] hadrons at high energies." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14861.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1987.The bracketed information is an arrow pointing to the right on the title page.
Bibliography: leaves 60-63.
by Mourad Dhina.
Ph.D.
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Maheswari, Dhiraj. "QCD Process in Few Nucleon Systems." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3795.
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One of the important issues of Quantum Chromodynamics (QCD) - the fundamental theory of strong interaction, is the understanding of the role of the quark-gluon interactions in the processes involving nuclear targets. One direction in such studies is to explore the onset of the quark gluon degrees of freedom in nuclear dynamics. The other direction is using the nuclear targets as a “micro-labs” in studies of the QCD processes involving protons and neutrons bound in the nucleus. In the proposed research, we work in both directions considering high energy photo- and electro-production reactions involving deuteron and 3 He nuclei.
In the first half of the research, we study the high energy break-up of the 3 He nucleus, caused by a incoming photon, into a proton-deuteron pair at the large center of mass scattering angle. The main motivation of the research is the theoretical interpretation of recent experimental data which revealed the unprecedentedly large exponent s −17 , for the energy dependence of the differential cross section. In the present research, we extend the theoretical formalism of the hard QCD rescattering model to calculate energy and angular dependences of the absolute cross section of the γ 3 He → pd reaction in high momentum transfer limit.
The second half of the research explores the deep-inelastic scattering of a polarized electron off the polarized deuteron and 3 He nuclei, to explore the quark-gluon structure of polarized neutron. The main reason of using deuteron is that it is the most simple and best understood nucleus. While the reason of using polarized 3 He as an effective polarized neutron target is that because of the Pauli-principle, the two protons in the target are in the opposite spin states and thus the neutron has all the polarization of the 3 He nucleus. However this approximation is exact only for the S-state and becomes less accurate with the increase of the internal momentum of the bound nucleons in the nucleus. There are several planned experiments which will be performed during next few years at the kinematics in which the internal momenta of the probed neutron cannot be neglected. Therefore, for the reliable interpretation of the data, all the nuclear effects, especially the effects related to the relativistic treatment of high momentum component of the nuclear wave function, should be taken into account. In this work, we developed a comprehensive theoretical framework for calculation of the all relevant nuclear effects that will allow the accurate extraction of the neutron data from deepinelastic scattering involving deuteron and 3 He targets.
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Davis, Sergio. "Atomistic Computer Simulations of the Melting Process and High Pressure Conditions." Licentiate thesis, KTH, Tillämpad materialfysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4826.
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The present work describes the use of atomistic computer simulations in the area of Condensed Matter Physics, and specifically its application to the study of two problems: the dynamics of the melting phase transition and the properties of materials at extreme high pressures and temperatures, problems which defy experimental measurements and purely analytical calculations. Both classical Molecular Dynamics (using semi–empirical interaction potentials) and first–principles (ab initio) Molecular Dynamics techniques has been applied in this study to the calculation of melting curves in a wide range of pressures for elements such as Xe and H2, the study of the elastic constants of Fe at the conditions of the Earth’s inner core, and the characterization of diffusion and defects formation in a generic Lennard–Jones crystal at the limit of superheating, including the role they play in the triggering of the melting process itself.QC 20101108
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Davis, Irarrazabal Sergio Michael. "Atomistic Computer Simulations of the Melting Process and High Pressure Conditions." Licentiate thesis, KTH, Materials Science and Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4826.
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The present work describes the use of atomistic computer simulations in the area of Condensed Matter Physics, and specifically its application to the study of two problems: the dynamics of the melting phase transition and the properties of materials at extreme high pressures and temperatures, problems which defy experimental measurements and purely analytical calculations.
Both classical Molecular Dynamics (using semi–empirical interaction potentials) and first–principles (ab initio) Molecular Dynamics techniques has been applied in this study to the calculation of melting curves in a wide range of pressures for elements such as Xe and H2, the study of the elastic constants of Fe at the conditions of the Earth’s inner core, and the characterization of diffusion and defects formation in a generic Lennard–Jones crystal at the limit of superheating, including the role they play in the triggering of the melting process itself.
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Bell, Candace. "Detection of the riming process with a vertically pointing radar." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33378.
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Supercooled cloud liquid water (SCW), which causes aircraft icing, can be detected indirectly by observing characteristics of the bright band with a vertically pointing radar. Accretion of supercooled water droplets on precipitating snow (riming) increases the density and fall speed of snow and decreases the intensity of the bright band. For stratiform precipitation with a melting layer, a small peak-to-rain reflectivity difference and a high snow-to-rain velocity ratio indicate high-density snow. A numerical model of the bright band gives a semi-quantitative relationship between snow density and bright band parameters. SCW content is computed theoretically and depends on the gradient of mass flux with height above the melting layer. A large mass flux gradient is an indication of growth by riming.
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Chen, Rung-Sheng. "The bend and polish method of aspheric surface manufacture : an investigation into optical design for this process and into the process itself." Thesis, Imperial College London, 2001. http://hdl.handle.net/10044/1/8158.
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Rosten, Jonatan Hans Niclas. "The ZZ → 4l process and anomalous triple gauge couplings with ATLAS at the LHC." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/271838.
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This thesis is a presentation of an analysis of the $ZZ\rightarrow 4\ell$ ($\ell = e,\mu$) process in proton-proton collisions with centre-of-mass energy $\sqrt{s}$ = 13 TeV at the LHC during 2015 and 2016 (a total integrated luminosity of 36.1 fb$^{-1}$), using the ATLAS detector. Candidate $ZZ \rightarrow 4\ell$ events are selected in the three decay channels, $4e$, $2e2\mu$ and $4\mu$. The cross section of the $ZZ\rightarrow 4\ell$ process is measured in four fiducial regions closely matching the detector acceptance: one for each decay channel ($4e$, $2e2\mu$ and $4\mu$) and one for the combination of all decay channels. The total cross section of $pp\rightarrow ZZ$ is measured in a phase-space in which both $Z$ bosons have a mass $m_{Z}$ in the range 66 GeV $ < m_{Z} < $ 116 GeV to be 16.5 $\pm 0.5$ (stat.) $\pm 0.4$ (syst.) $\pm 0.5$ (lumi.)$\,$ pb which is consistent with a next-to-next-to-leading-order prediction of $16.9^{+0.6}_{-0.5}$ pb. Observed event yields in four bins of transverse momentum are used to set 95{\%} CL$_{\text{s}}$ limits on four neutral triple gauge couplings ($f^{V}_{i}$, $V=Z,\gamma$, $i=4,5$) which parameterise an effective $ZZV$ vertex (assuming both $Z$ bosons are on shell). The obtained limits are of the order of $|f^{V}_{i}|<0.0017$.
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Thanathibodee, Thanawuth. "Chemical abundance analysis of HE 2324-0215, an r-process-enhanced metal-poor star." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105644.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 35-36).
We report the abundance analysis of the metal-poor halo star HE 2324-0215 for 22 neutron-capture elements and 14 light elements with Z < 30. The stellar parameters are [Fe/H] = -3.05 ± 0.17, Teff = 4477 K, Vt = 2.70 kms-1 , and log(g) = 0.70, indicating that HE 2324-0215 is a red giant star. The [Eu/Fe] = 0.73 and [Ba/Eu] = -0.68 suggests that this is an r-I star. Since thorium is detectable in this star, we derived the age of the star by the means of radioactive decay, resulting in the age of 13.0 ± 1.0 Gyr. The age and the metallicity of the star suggest that HE 2324-0215 formed in a dwarf galaxy which was later accreted and became part of the Milky Way.
by Thanawuth Thanathibodee.
S.B.
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Hencheck, Michael. "Nucleosynthesis during the rapid hydrogen burning process and the abundances of 92Mo and 94Mo /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487856906261345.
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Guest, Daniel. "Quantitative Analysis and Process of High Speed Live Cell Interferometry Measurements." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4843.
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The application of auto focus, using an optical beam deflection technique, to existing live cell interferometry measurements was developed and examined. The benefit to relevant experiments, currently being performed, is shown as well as its performance across various magnifications. Enough information is given so that the system can be reproduced to fit any end users needs.
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Carson, Jo. "Spider Speculations: A Physics and Biophysics of Storytelling." Digital Commons @ East Tennessee State University, 2008. http://amzn.com/1559362839.
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"Jo Carson lays bare her personal investigation into her own creative process after a spider bite on her back begins a series of life-altering events. Spider Speculations applies cutting edge mind-body science, quantum physics and ancient shamanistic techniques to describe how stories work in our bodies and our lives, and what happens when real stories are used in a public way. Carson, whose ability to capture the spoken word hallmarks her community-based work, sets down this story in her own distinctive voice, interspersing the journey with examples of her performance work. This truly original American book will speak to anyone thinking about art and community or engaging with people's stories"--Publisher description.https://dc.etsu.edu/alumni_books/1019/thumbnail.jpg
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Bateson, S. W. "Ion-selective electrode studies on sulphur compounds of process streams." Thesis, Cardiff University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354739.
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Kipling, Zak. "Cloud cycling, scavenging and aerosol vertical profiles : process sensitivity and observational constraints." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:16f442be-dac6-40d2-b1fa-4c5a2ff69e9c.
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The effects of aerosol in the atmosphere account for some of the largest uncertainties in estimates of the human impact on climate. These effects depend not only on the total mass of aerosol, but also its size distribution, mixing state and vertical profile. Previous studies have suggested that both the size distribution and mixing state of aerosol may be strongly influenced by repeated cycling through non-precipitating cloud. The extent of this process is assessed in the HadGEM3–UKCA model; although fewer cycles are seen for all aerosol than in previous studies, the figure varies considerably between aerosol types. The role of scavenging by precipitating cloud is also considered, and several approaches to increasing the physical realism of its representation are considered. In particular, coupling convective scavenging into the convective transport scheme is shown to provide significant benefits over an operator-split approach (which underestimates removal and allows excess aerosol to reach the upper troposphere and be transported to remote regions). To evaluate the alternative convective scavenging schemes, a method is developed for carrying out a pointwise evaluation against vertically-resolved in-situ observations from large-scale aircraft campaigns, based on nudging and flight-track sampling in the model. It is demonstrated that this approach can help to constrain the choice between different model configurations with a degree of statistical confidence. Finally, the processes controlling the vertical profile of aerosol are investigated using a series of model-based sensitivity tests, along with the extent to which these processes can account for the large diversity in vertical profiles seen amongst current models. For mass profiles and number profiles of large particles (greater than about 100nm dry diameter), removal and secondary production processes are shown to be most important; for number profiles of smaller particles, microphysical processes are shown to become increasingly dominant.
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Leadbeater, Thomas William. "The development of positron imaging systems for applications in industrial process tomography." Thesis, University of Birmingham, 2009. http://etheses.bham.ac.uk//id/eprint/521/.
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The diagnostic medical imaging technique of Positron Emission Tomography (PET) has been adapted at the University of Birmingham for use in imaging industrial processes. A particularly powerful technique, called Positron Emission Particle Tracking (PEPT) is used to study granular materials and fluid flows in a number of different applications. This thesis describes the most recent development of the detector systems which are used for PEPT studies at the Positron Imaging Centre. Primarily, the work has focussed upon developing a modular positron camera which can be arranged in custom geometries around the system under study. This camera is transportable and has been used to investigate a number of applications in situ. A new data acquisition system has been designed enabling the storage and analysis of the raw data produced by the detectors. The system has proven to operate reliably and with superior performance compared to that of the original device. These systems have been used for a number of successful PEPT studies on applications in various locations. Examples include improving process efficiency and gaining understanding of flow dynamics within industrial applications such as fluidised beds and polymer extrusion plant.
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Moisan, Jean-Francois. "Ultrasonic monitoring of die-casting process using clad buffer rod sensor." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32968.
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In-line monitoring of die-casting of aluminum (A356, A357, 86S), magnesium (AZ91) and a metal matrix composite (Gra-NiRTM 6S:3G) will be monitored using the reflection coefficient obtained by using an ultrasonic technique, the pulse/echo. For each of the materials enumerated above, the average temperature of the mold through its thickness, the end of filling of the part, the solidification of the part in the cavity of the mold, the gap and/or the detachment of the part, the sound velocity and the attenuation of the material will be measured by this ultrasonic technique during the process.For the materials the melt temperature will not exceed 600°C because the casting is made at the semi-solid state, between the solidus and liquidus, of the materials. A novel high performance buffer rod with a cooling system is integrated into the die. Therefore, ultrasonic measurements can be carried out with high signal-to-noise ratio at elevated temperatures.
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Kenney, Christopher John. "A measurement of the decay rate for the process kaon(L) going to positive muon negative muon." W&M ScholarWorks, 1989. https://scholarworks.wm.edu/etd/1539623786.
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A sample of 87 events of the GIM suppressed decay K$\sb{\rm L} \to \mu\sp+\mu\sp-$ were observed in an experiment performed in 1988 at the Brookhaven National Laboratory. Concurrently, 8,887 examples of the CP-violating decay K$\sb{\rm L} \to \pi\sp+\pi\sp-$ were also seen. The apparatus consisted of a double-magnet spectrometer as well as electromagnetic and muon detector systems. From the previously measured branching ratio for K$\sb{\rm L} \to \pi\sp+\pi\sp-$ and the different instrumental acceptances of the detector for the two decays, the data sample was normalized to the effective number of K$\sb{\rm L}$ decays observed. A value for the ratio (K$\sb{\rm L} \to \mu\sp+\mu\sp-)$/(K$\sb{\rm L} \to$ anything) of (5.7 $\pm$ 0.6(stat.) $\pm$ 0.3(syst.)) $\times$ 10$\sp{-9}$ was obtained.
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Van, Tonder Raynette. "Studies of the W±W± scattering process in pp collisions at the once and future ATLAS detector." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/28266.
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Tang, Xianmin. "Low damage processing and process characterization." W&M ScholarWorks, 2000. https://scholarworks.wm.edu/etd/1539623979.
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Two novel plasma sources (one neutral source and one pulsed inductively coupled plasma source) and ashing process characterization were investigated. The primary goal was to characterize these source properties and develop corresponding applications. The study includes process damage assessment with these two sources and another continuous wave (13.56MHz) plasma source. A global average simulation of the pulsed discharges was also included.;The transient plasma density and electron temperature from the double probe analysis were compared with single Langmuir probe results with sheath displacement corrections in pulsed discharges (200Hz--10kHz). The equivalent resistance method can be used effectively to analyze these double probe data. The transient behaviors of the plasma density and electron temperature are in accord with the model of the discharge. The hyper-thermal neutral source based on the surface reflection neutralization techniques was shown to provide enough fast neutrals for ashing applications. The surface roughness of the post-cleaned wafer was less than 10A. Ex-situ and in-situ measurements yield typical removal rates of about 10 A/s without stream collimation. The removal rates at increasing pressures show a trade-off between creating higher density plasma, leading to a large initial neutral flux and attenuation of neutrals due to collisions. Changing the reflector plate changes the neutral energy without changing the discharge composition. A novel technique, combining momentum and heat flux measurements shows that neutral stream energy is 3--6 eV and the neutral flux is on the order of 1015 cm-2 s-1. The derived etch rates from the measured neutral flux and energy values and the experimental rates are in good agreement. Quasi-static capacitance-voltage measurements demonstrate that the low energy neutral source induces much less damage than other plasma sources. Most of the neutral process damage is caused by uv photons escaping from the plasma source zone. The process-induced damage vary with the reflector bias and rf power.
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Jenner, Robert Peter. "Investigation of the suitability of amorphous semiconductors as sensors for optical process tomography." Thesis, University of Greenwich, 2000. http://gala.gre.ac.uk/6199/.
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In this work, the suitability of amorphous semiconductors as hard field optical sensors for application in optical process tomography (OPT) has been established. Two amorphous semiconductors were selected for the study, these being amorphous arsenic triselenide (a-As 2 Se3) and hydrogenated amorphous silicon (a-Si:H). The a-As2Se3 device was a single layered structure of 60|Um thickness fabricated upon a 2mm thick cylindrical aluminium substrate. The a-Si:H device was a multi-layered structure of 27.1fim overall thickness fabricated upon a 4mm thick cylindrical aluminium substrate. 20mm 2 samples were cut from the cylinders, their surface being left free for a xerographic investigation. For a tomographic investigation, semitransparent gold (Au) contacts were sputtered onto the surface of the devices to produce single contacts or contact arrays. The study comprised of the two fields of xerography and tomography. The xerographic study comprised of the measurement of such parameters as charge acceptance, dark decay, residual potential, and photoinduced discharge. The research project has concurred with other workers in that the dark discharge mechanism in a-As 2 Se 3 proceeds via a xerographic depletion discharge process, and a Poole-Frenkel type emission in a-Si:H. The tomographic investigation involved the study of such parameters as detectivity, responsivity, steady state photocurrent, and photoinduced fatigue. Detectivity has found to be dependant upon the magnitude of applied electric field and level of incident irradiance. Irradiance in the order of 3.45mW/cm 2 to 9.57mW/cm 2 for a- fj f\ As 2 Se3 and 5.31mW/cm to 28.32mW/cm for a-Si:H was required in order to produce a clean and repeatable photogenerated current pulse over the range of electric fields specified (0.66xl05 V/cm to 1.66xl05 V/cm). The production of steady state current has found to be dependant upon the magnitude of electric field, the level of irradiance, and the illumination period. Irradiance of 319mW/cm 2 to 1.46W/cm2 with an illumination period of 520ns was required to produce steady state photocurrent in a-As2Se3 , and 693mW/cm2 to 2.62W/cm 2 with an illumination period of 880ns for a-Si:H. A linear relationship between electric field and responsivity has been observed in both materials over a range of irradiance of 3.45mW/cm 2 to 9.57mW/cm2 . Responsivity in the order of 87.86|LiAAV to 145.19|iA/W for a-As2Se 3 and 14.19(iAAV to 103.81)J,AAV for a-Si:H has been demonstrated. An investigation as to the effects of photoinduced fatigue in both a-As 2 Se3 and a-Si:H has been carried out by the application of pulsed visible light of various flash repetition rate (FRR) under a constant high electric field over a 30 minute illumination period. It has been shown that the rate of fatigue is dependant upon the material, time, electric field, light intensity, and FRR. A maximum operating speed of 20Hz has been determined for a-As 2Se 3 and lOOHz for a-Si:H. The maximum operating speed of 20Hz for a-As 2 Se 3 was deemed unsuitable for OPT application and the a-As 2 Se 3 material was eliminated from further tomographic investigation. Tomographic prototypes were employed to establish the a-Si:H devices ability to produce qualitative and quantitative data. The results of this investigation demonstrated that 1mm changes in water level and 0.5% changes in fluid colour could be accurately determined by the a-Si:H device at speeds required for OPT. The use of an a-Si:H device containing a Au contact array facilitated the imaging of the curvature of a pipeline and a phantom object contained within the pipeline. The results of the overall investigation have confirmed that the a-Si:H device is suitable for application as a hard field optical sensor for OPT.
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Michaelides, Stylianos. "Physics-based process modeling, reliability prediction, and design guidelines for flip-chip devices." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16028.
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Tahkola, M. (Mikko). "Developing dynamic machine learning surrogate models of physics-based industrial process simulation models." Master's thesis, University of Oulu, 2019. http://jultika.oulu.fi/Record/nbnfioulu-201906042313.
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Abstract. Dynamic physics-based models of industrial processes can be computationally heavy which prevents using them in some applications, e.g. in process operator training. Suitability of machine learning in creating surrogate models of a physics-based unit operation models was studied in this research. The main motivation for this was to find out if machine learning model can be accurate enough to replace the corresponding physics-based components in dynamic modelling and simulation software Apros® which is developed by VTT Technical Research Centre of Finland Ltd and Fortum. This study is part of COCOP project, which receive funding from EU, and INTENS project that is Business Finland funded.
The research work was divided into a literature study and an experimental part. In the literature study, the steps of modelling with data-driven methods were studied and artificial neural network architectures suitable for dynamic modelling were investigated. Based on that, four neural network architectures were chosen for the case studies. In the first case study, linear and nonlinear autoregressive models with exogenous inputs (ARX and NARX respectively) were used in modelling dynamic behaviour of a water tank process build in Apros®. In the second case study, also Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU) were considered and compared with the previously mentioned ARX and NARX models. The workflow from selecting the input and output variables for the machine learning model and generating the datasets in Apros® to implement the machine learning models back to Apros® was defined. Keras is an open source neural network library running on Python that was utilised in the model generation framework which was developed as a part of this study. Keras library is a very popular library that allow fast experimenting. The framework make use of random hyperparameter search and each model is tested on a validation dataset in dynamic manner, i.e. in multi-step-ahead configuration, during the optimisation. The best models based in terms of average normalised root mean squared error (NRMSE) is selected for further testing.
The results of the case studies show that accurate multi-step-ahead models can be built using recurrent artificial neural networks. In the first case study, the linear ARX model achieved slightly better NRMSE value than the nonlinear one, but the accuracy of both models was on a very good level with the average NRMSE being lower than 0.1 %. The generalisation ability of the models was tested using multiple datasets and the models proved to generalise well. In the second case study, there were more difference between the models’ accuracies. This was an expected result as the studied process contains nonlinearities and thus the linear ARX model performed worse in predicting some output variables than the nonlinear ones. On the other hand, ARX model performed better with some other output variables. However, also in the second case study the model NRMSE values were on good level, being 1.94–3.60 % on testing dataset.
Although the workflow to implement machine learning models in Apros® using its Python binding was defined, the actual implementation need more work. Experimenting with Keras neural network models in Apros® was noticed to slow down the simulation even though the model was fast when testing it outside of Apros®. The Python binding in Apros® do not seem to cause overhead to the calculation process which is why further investigating is needed. It is obvious that the machine learning model must be very accurate if it is to be implemented in Apros® because it needs to be able interact with the physics-based model. The actual accuracy requirement that Apros® sets should be also studied to know if and in which direction the framework made for this study needs to be developed.Dynaamisten surrogaattimallien kehittäminen koneoppimismenetelmillä teollisuusprosessien fysiikkapohjaisista simulaatiomalleista. Tiivistelmä. Teollisuusprosessien toimintaa jäljittelevät dynaamiset fysiikkapohjaiset simulaatiomallit voivat laajuudesta tai yksityiskohtien määrästä johtuen olla laskennallisesti raskaita. Tämä voi rajoittaa simulaatiomallin käyttöä esimerkiksi prosessioperaattorien koulutuksessa ja hidastaa simulaattorin avulla tehtävää prosessien optimointia. Tässä tutkimuksessa selvitettiin koneoppimismenetelmillä luotujen mallien soveltuvuutta fysiikkapohjaisten yksikköoperaatiomallien surrogaattimallinnukseen. Fysiikkapohjaiset mallit on luotu teollisuusprosessien dynaamiseen mallinnukseen ja simulointiin kehitetyllä Apros®-ohjelmistolla, jota kehittää Teknologian tutkimuskeskus VTT Oy ja Fortum. Työ on osa COCOP-projektia, joka saa rahoitusta EU:lta, ja INTENS-projektia, jota rahoittaa Business Finland.
Työ on jaettu kirjallisuusselvitykseen ja kahteen kokeelliseen case-tutkimukseen. Kirjallisuusosiossa selvitettiin datapohjaisen mallinnuksen eri vaiheet ja tutkittiin dynaamiseen mallinnukseen soveltuvia neuroverkkorakenteita. Tämän perusteella valittiin neljä neuroverkkoarkkitehtuuria case-tutkimuksiin. Ensimmäisessä case-tutkimuksessa selvitettiin lineaarisen ja epälineaarisen autoregressive model with exogenous inputs (ARX ja NARX) -mallin soveltuvuutta pinnankorkeuden säädöllä varustetun vesisäiliömallin dynaamisen käyttäytymisen mallintamiseen. Toisessa case-tutkimuksessa tarkasteltiin edellä mainittujen mallityyppien lisäksi Long Short-Term Memory (LSTM) ja Gated Recurrent Unit (GRU) -verkkojen soveltuvuutta power-to-gas prosessin metanointireaktorin dynaamiseen mallinnukseen. Työssä selvitettiin surrogaattimallinnuksen vaiheet korvattavien yksikköoperaatiomallien ja siihen liittyvien muuttujien valinnasta datan generointiin ja koneoppimismallien implementointiin Aprosiin. Koneoppimismallien rakentamiseen tehtiin osana työtä Python-sovellus, joka hyödyntää Keras Python-kirjastoa neuroverkkomallien rakennuksessa. Keras on suosittu kirjasto, joka mahdollistaa nopean neuroverkkomallien kehitysprosessin. Työssä tehty sovellus hyödyntää neuroverkkomallien hyperparametrien optimoinnissa satunnaista hakua. Jokaisen optimoinnin aikana luodun mallin tarkkuutta dynaamisessa simuloinnissa mitataan erillistä aineistoa käyttäen. Jokaisen mallityypin paras malli valitaan NRMSE-arvon perusteella seuraaviin testeihin.
Case-tutkimuksen tuloksien perusteella neuroverkoilla voidaan saavuttaa korkea tarkkuus dynaamisessa simuloinnissa. Ensimmäisessä case-tutkimuksessa lineaarinen ARX-malli oli hieman epälineaarista tarkempi, mutta molempien mallityyppien tarkkuus oli hyvä (NRMSE alle 0.1 %). Mallien yleistyskykyä mitattiin simuloimalla usealla aineistolla, joiden perusteella yleistyskyky oli hyvällä tasolla. Toisessa case-tutkimuksessa vastemuuttujien tarkkuuden välillä oli eroja lineaarisen ja epälineaaristen mallityyppien välillä. Tämä oli odotettu tulos, sillä joidenkin mallinnettujen vastemuuttujien käyttäytyminen on epälineaarista ja näin ollen lineaarinen ARX-malli suoriutui niiden mallintamisesta epälineaarisia malleja huonommin. Toisaalta lineaarinen ARX-malli oli tarkempi joidenkin vastemuuttujien mallinnuksessa. Kaiken kaikkiaan mallinnus onnistui hyvin myös toisessa case-tutkimuksessa, koska käytetyillä mallityypeillä saavutettiin 1.94–3.60 % NRMSE-arvo testidatalla simuloitaessa.
Koneoppimismallit saatiin sisällytettyä Apros-malliin käyttäen Python-ominaisuutta, mutta prosessi vaatii lisäselvitystä, jotta mallit saadaan toimimaan yhdessä. Testien perusteella Keras-neuroverkkojen käyttäminen näytti hidastavan simulaatiota, vaikka neuroverkkomalli oli nopea Aprosin ulkopuolella. Aprosin Python-ominaisuus ei myöskään näytä itsessään aiheuttavan hitautta, jonka takia asiaa tulisi selvittää mallien implementoinnin mahdollistamiseksi. Koneoppimismallin tulee olla hyvin tarkka toimiakseen vuorovaikutuksessa fysiikkapohjaisen mallin kanssa. Jatkotutkimuksen ja Python-sovelluksen kehittämisen kannalta on tärkeää selvittää mikä on Aprosin koneoppimismalleille asettama tarkkuusvaatimus.
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Famiano, Michael A. "Beta-decay rates of nuclei in ground and excited states and effects on the r-Process of Nucleosynthesis /." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488204276531897.
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Dauncey, P. D. "A study of QCD process in e'+e'- annihilation." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375232.
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McConnell, Joseph Robert 1958. "Investigation of the atmosphere-snow transfer process for hydrogen peroxide." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282556.
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Of the three primary atmospheric oxidants, hydroxyl radical, ozone, and hydrogen peroxide (H₂O₂), only the latter is preserved in ice cores. To make quantitative use of the ice core archive, however, requires a detailed understanding of the physical processes that relate atmospheric concentrations to those in the snow, firn and thence ice. The transfer processes for H₂O₂ were investigated using field, laboratory, and computer modeling studies. Empirically and physically based numerical algorithms were developed to simulate the atmosphere-to-snow-to-firn transfer processes and these models coupled to a snow pack accumulation model. The models, tested using field data from Summit, Greenland and South Pole, indicate that H₂O₂ is reversibly deposited to the snow surface, with subsequent uptake and release controlled by advection of air containing H₂O₂ through the top meters of the snow pack and temperature-driven diffusion within individual snow grains. This physically based model was successfully used to invert year-round surface snow concentrations to an estimate of atmospheric H₂O₂ at South Pole. Field data and model results clarify the importance of accumulation timing and seasonality in determining the H₂O₂ record preserved in the snow pack. A statistical analysis of recent accumulation patterns at South Pole indicates that spatial variability in accumulation has a strong influence on chemical concentrations preserved in the snow pack.
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Campbell, Andrew Paul. "Modelling of freeze layer formation and refractory wear in direct smelting process." Thesis, University of Greenwich, 2002. http://gala.gre.ac.uk/6124/.
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The work discussed in this thesis is aimed at examining the formation of freeze layers and refractory wear on water-cooling elements within direct smelting processes through the use of computational modelling techniques. The motivation of performing this work is to examine the cooling of regions of the Smelt Reduction Vessel of the HIsmelt process closer to the molten bath material. HIsmelt is a novel process for the production of pig iron which has been under development by Rio Tinto and is now being ommercialised. The previous work performed in this are has been reviewed with particular focus on the refractory wear mechanisms as the solidification algorithms have been thoroughly implemented within the Computational Fluid Dynamics (CFD) framework PHYSCIA used within this work. The governing equations along with the Finite Volume discretisations of these equations are set out within this thesis. Some comment is made about the solution methods used, and how boundary conditions are implemented. The Free-surface flow and Solidification governing relationships are also described as these are important for investigating the formation of freeze layers. The implementation of the refractory wear mechanisms are discussed in some detail. The three mechanisms implemented are for the penetration of slag into the refractory, the corrosion of the refractory by this penetrated slag; and the erosion of the refractory by the bulk flow of slag within the furnace. To be able to reasonably predict refractory wear, it is necessary to make the properties of the materials within the system temperature dependent. During the pilot plant trials at the HIsmelt® Research and Development facility, located in Kwinana Western Australia, accretions formed on the end of the solids injection lances. These accretions have been termed Elephant's Trunks. With the imminent construction of the Development Plant which injects the iron bearing feeds at an elevated temperature rather than at ambient temperatures used on the pilot plant, the formation of these pipe-like accretions under both the cold and hot injection conditions have been examined. This work provides confidence that the freeze layers predicted from the model will reflect those formed within the furnace. To evaluate the effectiveness of the refractory wear mechanisms, data from experimental and the HIsmelt pilot plant have been modelled. Sections of refractory samples from an induction furnace test and a rotary slag test have been modelled. The results are in agreement with the profile and affected regions of the sectioned refractory test pieces. A part of the HIsmelt pilot plant Smelt Reduction Vessel (SRV) has been modelled for the period of campaign 8-1 & 8-2 (just over 20 days). The predicted wear is in agreement with the measurements taken after the vessel had been cooled. To bring together freeze layer formation with the refractory wear mechanisms, a water-cooled element was modelled for the sloping slag section. The results show the growth of a small freeze layer that is consistent with the small freeze layer seen on the upper cooling panels of the pilot plant SRV. This model is an ideal tool to evaluate different water-cooling strategies for HIsmelt and other similar direct smelting processes. This work has developed models that predict the formation of freeze layers and refractory wear within direct smelting processes. The models have focused on slag-refractory interactions and further work would be needed to extend the refractory wear models to account for metal-refractory interactions. To examine spalling, stress calculations could be performed to determine when this may occur.
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Kumar, Suman. "Computational fluid dynamics (CFD) and physical modelling of a metal refining process." Thesis, University of Greenwich, 2003. http://gala.gre.ac.uk/6213/.
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Impeller-stirred mixing is one of the most important processes employed throughout the chemical, metallurgical and allied industries. The research reported in this thesis is focused on impeller stirred mixing associated with the refining of lead bullion. The aim of this process is to sequentially remove contained impurities such as copper, antimony, silver and bismuth. This occurs in hemispherical vessels, called kettles, where reagents are initially added to the lead bath to form surface dross that contains both the required impurity and a large amount of lead oxide. This dross is then continuously mixed back into the bath to remove the lead oxide and capture more of the required impurity. A key requirement for this process is to obtain and remove dross that contains a high concentration of the impurity. Although this process has been in operation for many years, there is very little known on how the fluid dynamics associated with the mixing process affects final dross content. The aim of this research is to fully investigate the lead refining process using scientific analysis methods that help understand the mixing process and provide design tools which can be used to optimise process conditions. The three methods of analysis used are: (1) Direct readings from a real kettle, (2) Physical modelling (using water), and finally (3) Computational Fluid Dynamics (CFD). The use of physical modelling, exploiting the techniques of similitude, to predict vortex was also validated. An Acoustic Doppler Velocimeter (ADV) probe was used for the velocity measurement at various locations inside the water model and this gave valuable insight about the flow phenomena occurring inside the refining kettle. A particular important finding was that when fluid is stirred above certain rotational speed the vortex depth becomes independent of the Reynolds number of the operation. With regards CFD technology, the Volume of Fluid (VOF) method was used to capture the free surface and the Lagrangian Particle Tracking (LPT) and Algebraic Slip Model (ASM) to simulate the dross phase. Appropriate methods were also used to represent the moving impeller region. Validation of simulation results against experimental data was very encouraging. Computed vortex depth showed the similar trend as observed during the experiments on the physical model. A design strategy was developed that integrates results from both physical and computational modelling to allow optimal process conditions to be predicted at the kettle design stage. The use of this integrated physical and computational modelling methodology successfully helped eliminate surface swirl by introducing baffles to the kettle. The design and introduction of these flow controllers was also validated to ensure that it optimised the dross mixing process and final impurity content in the dross.
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Kong, Yung 1967. "Particle contamination in sulfur-hexafluoride/argon plasma etching process." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277919.
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Process generated particle contamination on unpatterned silicon wafers etched in an SF6/argon plasma using a Tegal MCR-1 etcher in the plasma triode-1 mode was characterized using response surface methodology. Particle deposition was observed to be a predictable function of plasma parameter space, which can be determined by relatively few statistically designed experiments. A model of particle deposition as a function of 13.56 MHz chamber electrode rf power, chamber pressure, gas flow rate, etch time and 100 kHz wafer electrode power was constructed. It is found that particle deposition depends linearly on etch time and both 13.56 MHz and 100 kHz power. In addition, particle deposition increased with gas flow rate at low flow rate, reaches a maximum, then decreased as flow rate increased further. Moreover, there was no observable effect on particle deposition due to pressure variation in the pressure range explored. Auger chemical analysis showed that the particles contained elemental sulfur, fluorine, silicon, aluminum, carbon and oxygen. Most particles were typically less than 2 μm in diameter.
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Brandenburg, Kristyn H. "Development of a Neutron Long Counter for (alpha,n) Cross Section Measurements at Ohio University." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1512730722722763.
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Sugden, Kate E. P. "Nonequilibrium statistical physics applied to biophysical cellular processes." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4339.
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The methods of statistical physics are increasingly being employed in a range of interdisciplinary areas. In particular, aspects of complex biological processes have been elucidated by bringing the problems down to the level of simple interactions studied in a statistical sense. In nonequilibrium statistical physics, a one dimensional lattice model known as the totally asymmetric simple exclusion processes (TASEP) has become prominent as a tool for modelling various cellular transport processes. Indeed the context in which the TASEP was first introduced (MacDonald et. al., 1968) was to model ribosome motion along mRNA during protein synthesis. In this work I study a variation of the TASEP in which particles hop along a one dimensional lattice which extends as they reach the end. We introduce this model to describe the unique growth dynamics of filamentous fungi, whereby a narrow fungal filament extends purely from its tip region while being supplied with growth materials from behind the tip. We find that the steady state behaviour of our model reflects that of the TASEP, however there is an additional phase where a dynamic shock is present in the system. I show through Monte Carlo simulation and theoretical analysis that the qualitative behaviour of this model can be predicted with a simple mean-field approximation, while the details of the phase behaviour are accurate only in a refined approximation which takes into account some correlations. I also discuss a further refined mean-field approximation and give a heuristic argument for our results. Next I present an extension of the model which allows the particles to interact with a second lattice, on which they diffuse in either direction. A first order meanfield continuum approximation suggests that the steady states of this system will exhibit some novel behaviour. Through Monte Carlo simulation I discuss the qualitative changes that arise due to the on-off dynamics. Finally I study a model for a second biological phenomenon: the length fluctuations of microtubules. The model describes stochastic polymerisation events at the tip of a microtubule. Using a mean-field theory, we find a transition between regimes where the microtubule grows on average, and where the length remains finite. For low rates of polymerisation and depolymerisation, the transition is in good agreement with Monte Carlo simulation.
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Kim, Taeman. "Buffer gas cooling of ions in a radio frequency quadrupole ion guide : a study of the cooling process and cooled beam properties." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35666.
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The buffer gas cooling process and the properties of the cooled beam in a novel rf quadrupole ion beam guide with axial field was studied. The operation principle of the axial field quadrupole ion beam guide is similar to the quadrupole mass filter operating in AC only mode but the rods were segmented and differential DC biases were applied to produce the axial field. It was operated in buffer gas.A Monte Carlo simulation was developed and the simulation results were compared with the experimental results. The beam distribution in a thermal equilibrium was assumed as the thermal equilibrium distribution in a simple harmonic motion with rf distortion and the assumption was confirmed by the Monte Carlo simulation.
The temperature of the cooled beam was measured with a beam profile, measurement system which consists of a miniature quadrupole ion beam guide aid a rotating semi-circular Faraday plate. The temperature of the cooled beam was measured to be 0.0424 +/- 0.0026 eV in the experiment while that of the simulated beam was 0.0372 +/- 0.0009 eV. The variation of beam temperature with beam current was 0.0153 +/- 0.0026 eV/nA. The maximum achieved ion transmission was 80%. The transmitted ion beam's energy spread was measured with a retarding potential energy analyzer to be less than 0.1 eV. The cooling time was 0.7 ms with 1V/ cm axial field and was observed to be very dependent on the ion current when there was no axial field.
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Manara, Carlo Felice Maria. "The physics of the accretion process in the formation and evolution of Young Stellar Objects." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-171652.
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Inal, Aydin. "Practical science process skills in physics, with special reference to test item assessment and classification." Master's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/11566.
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Bibliography: leaves 207-218.This study describes the development, validation, classification, administration and assessment of a compact programme of ten core practical task items chosen from a pool of 33 practical tasks developed for the purpose of this study in basic school physical science. The practical items encouraged and measured various science process skills laid out in the South African Revised National Curriculum Statement Draft. The derivation and classification of the specially designed diagnostic practical task items by experienced lecturers, teachers and academics constitutes an original and crucial part of the study. The objective is to assess the consensus of juries of four to eleven expert science educators on classification of the ten core practical activities, matching the categories. The investigation establishes whether there is a perceived relevant match or a perceived "irrelevant" mismatch between the science process skills tested by the current experimental programme of practical items and the descriptive theories of practical science and its classification schemes and criteria proposed by (a) Franus (1992), (b) Gardner (1983), (c) White (1988), (d) Solomon (1998), (e) Lock (1990), (t) Kapenda, Kandjeo-Marenga, Gaoseb, Kasanda and Lubben's (2001) the Cambridge-based International General Certificate of Education after Millar, Ie Marechal and Tiberghiea (1999), (g) Race (1997) and (h) OBE (Revised National Curriculum Statement Draft, 2001). Lock's assessment framework for practical tasks was found to be the most relevant scheme among the others. The study also identified eight process skills that are highly relevant to practical tasks of the compact programme. These skills included: (a) comprehension skills; (b) recognising given item of apparatus; (c) following instructions; (d) carrying out tasks and handling science apparatus; (e) observation skills; (t) interpretation of the observations; (g) making predictions; and (h) reporting and communicating scientific information.
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Strusevich, Nadezhda. "Numerical modelling of electrodeposition process for printed circuit boards manufacturing." Thesis, University of Greenwich, 2013. http://gala.gre.ac.uk/10214/.
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Printed circuit boards (PCBs) are used extensively in electronic products to connect assembled components within a system. The so-called vertical interconnect access (via) is a vertical hole or cavity in the PCB filled with metal to facilitate conductivity. The current trend, particularly for high technology products (e.g., 3D packaging), is to manufacture PCBs with high aspect ratio (AR) vias. Typically, the size of such a via is at the micrometer scale (this is why they are termed micro-vias). The most widely used technique for manufacturing micro-vias is electrodeposition of metal (e.g., copper), where the PCB is immersed into a plating cell filled with an electrolyte solution. Using standard conditions, electrodeposition usually does not produce micro-vias with the required quality. This is due to a lack of copper ion transport into the via. This has lead to studies of various ways of enhancing the ion transport. This thesis documents the results from a modelling study into the electrodeposition processes for fabricating high aspect ratio micro-vias. This includes basic electrodeposition and techniques that enhance ion transport such as forced convection (using a pump) and acoustic streaming (using transducers). In this work, a novel numerical method for explicitly tracking the interface between the deposited metal and the electrolyte is implemented and validated under the conditions of basic electrodeposition using experimental data. Results from a parametric study have established a set of design rules for micro-vias fabrication. When ion transport is enhanced by forced convection (e.g., pumping) in the plating cell, we apply a multi-scale modelling methodology that provides interaction between models at the macro level (the plating cell) and the micro level (the interior of a via). Numerical simulations can then be used to verify how ion transport into the micro-via is improved. These results can then be used to identify process conditions for the plating cell which will result in the required flow behaviour at the micro-via. Megasonic agitation can also be used to enhance electrolyte convection in the plating cell. This is achieved by placing megasonic transducers into the plating cell. This leads to several phenomena, one of which is known as the acoustic streaming. Models have been developed for predicting megasonic agitation both at the macro and micro-scales, and a number of designs have been investigated for both open and blind micro-vias.
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Hakim, Ali. "Characterization of Hard Metal Surfaces after Various Surface Process Treatments." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-12433.
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The aim of this thesis is to investigate how material surfaces are affected by various surface treatments and how this relates to the adhesion of the coating. The materials that were studied were WC-Co and Cermets and the surface treatments used were polishing, grinding with coarser and finer abrasive grains, and finally wet blasting and dry blasting. Focus was on deformations and residual stresses in the surface, surface roughness and cracks. The test methods used for examining the samples included surface roughness measurements, residual stress measurements, adhesion tests using Rockwell indentation and SEM images of the surface and the cross section.
The results concluded that polishing gives very good adhesion. Additionally, the adhesion for ground surfaces was good for WC-Co but very poor for Cermets. Furthermore, it was observed that finer abrasive grains did not result in better adhesion. In fact, the coarser grains gave slightly better results. Finally, it was concluded that wet blasting has a clear advantage over dry blasting and results in much better adhesion, especially for the Cermets. The results for the WC-Co were a bit inconsistent and so further research is required.
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Silva, Glauco dos Santos Ferreira da. "As intervenções do professor e processo grupal nas aulas de Física: uma análise à luz da teoria de Grupos Operativos." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/81/81131/tde-25042013-110927/.
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Quando alunos, convocados pelo professor, se reúnem em grupos numa sala de aula, inicia-se uma construção de relações interpessoais, envolvendo alunos e professor, que influenciam fortemente o processo grupal. O foco do nosso trabalho está neste processo, ou seja, em como um grupo de ensino-aprendizagem produz ou não seus resultados em sala de aula. Procuramos investigar questões do tipo: como e quando os grupos analisados funcionaram? Quais intervenções do professor favoreceram a aprendizagem? A pesquisa foi desenvolvida numa escola particular no interior de São Paulo, com alunos da 1ª série do Ensino Médio cujas aulas de Física foram marcadas pela constância de atividades em grupo em que o professor fazia uma série de intervenções (presencial, institucional e virtual) a fim de tornar o grupo mais operativo. Entre estas, consideramos significativa uma intervenção que consistiu em atribuições de funções (Líder, Anotador e Questionador) para cada um dos membros do grupo e que deveriam ser rotativas a cada atividade. O nosso trabalho consistiu na descrição dos episódios e na análise dos três grupos que compunham a classe investigada e encontramos resultados bem diferentes para cada um deles que foram caracterizados da seguinte maneira: o grupo 1, da dependência; o grupo 2 da resistência; grupo 3 da mudança. Utilizamos as concepções de grupos operativos de Pichon-Rivière, que focaliza a tarefa do grupo e o vinculo entre os membros como elementos essenciais do desenvolvimento grupal. Todo o processo tem na comunicação entre os membros do grupo o aspecto principal para atribuição de papéis (porta-voz, líder, bode expiatório e sabotador), os quais vão surgindo ao longo da tarefa e devem ser circular entre os atores. Quando estes estão estereotipados torna-se necessária a intervenção do professor que deve fazê-los circular, proporcionando mudanças que vão caracterizar a aprendizagem. O processo grupal é dividido em três etapas: a pré-tarefa, quando os alunos resistem à mudança; a tarefa, quando, por uma elaboração das ansiedades o grupo resolve atividade; e o projeto, que é o momento da criatividade e de uma projeção das suas atividades para além do \"aqui-agora\".When the teacher invites students to form groups inside the classroom, interpersonal relationship is built among students and teacher which influences the group process. Our work is focused in this process, in how a learning group is able, or not, to achieve good results. Some of our questions were: how and when the analyzed groups worked well? Which of the teacher\'s interventions were significant to learning? The research was developed with High School students from a private school in the state of São Paulo. The Physics teacher used to ask them to work in groups and he intervened in order to make the group operative. A significant intervention was the one in which the teacher asked each member of the group to act as an specific role (leader, writer and questioner). For each new activity they should chance roles. In this work, we described the events, analyzed the three groups formed in the chosen classroom and we found out different results for each of them. We could named the groups this way: group 1, of dependency; group 2, of resistance; group 3, of change. We used some concepts of operative groups from Pichon-Rivière, which focus the task and the bond among the members as essential to the group development. For him, the communication is the main aspect of the process. The roles appear during the development of the task and the members should change them. When they do not change, it is necessary that the teacher intervenes to promote learning. The group process is divided into three stages: the pre-task, when students resist changes; the task, when the group solves their anxieties and develops the activity; the project, which is the moment of creativity.
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Molaei, Chalchooghi Mazaher. "Modelling and CFD simulation of a fluidized bed process for the capture of C02 from fossil fuel combustion sources." Thesis, University of Greenwich, 2013. http://gala.gre.ac.uk/11960/.
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Fossil fuels provide the main source of energy for power generation in existing power plants. A mitigation option to reduce carbon dioxide (CO2) emission from existing power plants with fossil fuel combustion is the sequestration of carbon dioxide and storage in geological formations, in the ocean or for use in industrial processes. CO2 capture from combustion exhaust gases by mineral carbonation using a fluidised bed is studied in this project. CFD modelling has been used to study the efficiency of CO2 capture in a fluidized bed reactor containing a solid sorbent Calcium Oxide (CaO). This present work seeks to maximize CO2 conversion by a systematic modification of the flow domain. In particular, it is intended to use a convergent-divergent geometry to control the velocity of particles in the reaction domain thereby keeping the particles in the domain as long as possible. This is expected to improve the performance of the system as more time is allowed for any remaining CO2 to react with CaO and then be removed in the calcination stage. Further the effect of other key parameters such as particle size, CO2 concentration of flue gas and mass loading of solid sorbent have also been investigated. A Lagrangian/Eulerian scheme has been developed for this purpose, which uses a particle tracking model to describe CaO particle trajectories and mass, momentum and energy exchange with the carrier gas, entering the reactor in a typical flue gas composition. A steady-state condition is assumed, with each trajectory representing a parcel of particles of a given mass and diameter. The number of particles entering the fluidised bed is kept constant, and the fluidization velocity is chosen so that particles remain in the reactor. As the carbonation progresses, heavier well-reacted particles are collected at the bottom of the reactor. In the case of a non-uniform size distribution, fine particles would escape from the top of the reactor; in order to keep such particles within the domain the geometry was modified to increase the residence time of particles and to obtain maximum conversion. CO2 reduction of the order of 90% was achieved in a single pass, with a mass loading of 2.5 times of equivalent solid sorbent to CO2 in gas.
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Williams, John Alejandro. "Searching for deep understanding : implementing a mechanical engineering design process in K9-K12 physics classrooms to identify and improve levels of physics intuition and content." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/60208.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Vita. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 71).
This experiment tested the level of Physics content knowledge of various K9-K12 Physics students in a local Boston high school by having them implement a mechanical engineering design process to solve open-ended design problems. Using MIT's 2.009 and 2.72 Mechanical Engineering project-based classes as models for project planning, a fully hands-on collaborative project was developed whereby students designed, built, tested, and then raced model kit cars driven by compressed gas. Over the course of six weeks, students selected three design elements of their car to change and did detailed analysis to predict how these changes would affect the performance of their car. Major deliverables of the project included a group-kept design notebook that was turned in on a weekly basis as well as a final product brochure that highlighted the major areas of learning that the students experienced with the project. Results of the project were positive. The stock kit car ran anywhere from 20-25mph without modifications, but students achieved speeds of over 95mph by optimizing their design in ways dictated by the laws of physics. Yet, there can be disconnects between what a student produces in his or her work and their true understanding of what they have done. By examining the design notebooks as well as through weekly interactions with the students, it was clear that very few students exhibited true ownership of some very fundamental principles of Physics and mechanics. Yet, these same students tended to do very well in their MCAS (Massachusetts Comprehensive Assessment System) as well as in the framework of traditional classroom testing and assignments. Conclusions can be drawn from this thesis work that although students can demonstrate proficiency of bodies of scientific knowledge in the framework of written tests, their understanding of the material does not go deep enough to immediately apply this content knowledge to solve open-ended engineering problems. The good news is that these students aren't employees of an engineering firm who are expected to arrive with a well founded mastery of their field, instead they are students who are expected to grow and learn from failures. It is clear that hands-on projects like the one developed for this thesis work serve as irreplaceable learning opportunities where students can bridge the gap between textbook learning and the true physical implications of what they learn. Not only this, but they learn basic problem-solving, time, and team management skills that will serve them well regardless of the path they choose after graduation.
by John Alejandro Williams.
S.B.
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Dehbi-Alaoui, Azzeddine. "An investigation into the effect of process parameters on carbon film physical properties produced by different deposition techniques." Thesis, University of Hull, 1994. http://hydra.hull.ac.uk/resources/hull:8311.
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This thesis reports research to investigate the effect of process parameters on the physical properties of carbon films produced using different deposition techniques. The deposition techniques utilised are a FAB source, an r.f./d.c. EBPVD system and a hot filament CVD system. The findings of this study indicate that the films produced by the FAB source technique are relatively hard (-2000 HK at 25g). Occasionally some films showed a hardness up to 8000HK due, in part, to elastic recovery during testing. FAB source films are transparent in the infrared, however they suffer from a relatively poor transmission in the visible. The optical band gap is about 1eV. The refractive index is around 2.2 and their hydrogen content is low. When the carbon content in the source gas was reduced by mixing hydrogen with the hydrocarbon used, the transparency, the content of bonded hydrogen in the films and the optical band gap increased slightly but the hardness, adhesion, refractive index and deposition rate decreased. The impact energy has a dominant influence on the film properties. This has been demonstrated by changing the sample orientation.@ FAB source films have good wear and friction properties with only a small sign of localised failure after pin on disc sliding tests for 100 metres. A study on titanium nitride/DLC multilayer films showed that the adhesion at the TiN/DLC interface can be improved (and therefore the wear performance). The best adhesion and wear results were obtained by utilising an over-stoichiometric composition of titanium nitride. FAB source films have been deposited on PET and were shown to be as good as that of sputtered gold on PET, and much superior to evaporated titanium on PET. The transparency of the coated PET has been improved by optimising the deposition conditions. The properties of films grown by plasma-assisted evaporation of graphite depends on the carrier gas used, substrate type and bias voltage (under both d.c and r.f. conditions). Films grown on tool steel in a butane r.f. plasma have a hardness around 4000 HK (25g). The growth rate on glass under similar conditions is very low, but the film is completely transparent with an optical band gap of 2.6 eV. When argon is used as the carrier gas, no film is formed on tool steel, but on glass a completely transparent film is produced. Nanohardness measurement showed that r.f EBPVD films are extremely hard (33-44 GPa) and the lowest elastic recovery was obtained for the non-hydrogenated film (11% against 44% for the a-C:H film). Pin on disc tests of r.f. a-C:H films exhibited a typical film wear of 48x 10⁻⁶mm3/Nm against steel, which represents a modest reduction in wear compared to an uncoated steel substrate. All d.c. EBPVD films showed poor performance in the pin on disc machine due to their poor adhesion. The concentration of bonded hydrogen (αs) in d.c. films is up to five times more than that of FAB source films. Their relatively low refractive index reflects a polymeric type of film. They were more brittle and usually less well adhered than those produced by other methods. Their optical band gap varied between 1eV to 3.5eV. The concentration of total hydrogen (bonded or eventually non-bonded) has been found by coworkers to be 33% in dc EBPVD films and 25% in FAB source films. The decrease of the concentration of bonded hydrogen with cathode voltage and the absence of such correlation for the total hydrogen in dc/EBPVD an FAB source films, suggests the presence of nonbonded hydrogen in the films. One of the achievements of the work is that an empirical relationship is developed, linking the optical band gap with the amount of bonded hydrogen in the film, the relative carbon to hydrogen flow input ratio, and other plasma electrical parameters for carbon coatings produced using a thermionically enhanced plasma-assisted d.c. PVD process. It explains observed properties in terms of process parameters and highlights the difficulties in obtaining consistent coatings on sample surfaces at different locations and orientations in the deposition chamber. Finally a new system is described for the deposition of hard carbon films. This new system allows the generation of very high ionisation levels and produces films with hardnesses over 8000 HK (200g) (thickness - 2.5μm,substrate; tool steel). The deposition rate is higher than previously reported for such hard films (2-3μm/hr) in a 0.5-1% CH₄ in H₂ plasma. SEM microscopy showed particles having octahedral shapes. Raman spectroscopy indicates a OLC structure with some disordered graphite present. Infrared spectrophotometry showed very little evidence of bonded hydrogen in the films. The optical band gap is 2 eV for a film deposited on silica.
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Andre, Pascal. "Rapport d'habilitation à diriger des recherches." Habilitation à diriger des recherches, Université Blaise Pascal - Clermont-Ferrand II, 2001. http://tel.archives-ouvertes.fr/tel-00011679.
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