Tesi: "Mechanical equilibrium"

1

Jung, Sunghoon. "Nanomechanics model for static equilibrium". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FJung.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Ekoto, Isaac Wesley. "Supersonic turbulent boundary layers with periodic mechanical non-equilibrium". Texas A&M University, 2006. http://hdl.handle.net/1969.1/4709.

Testo completo

Abstract (sommario):

Previous studies have shown that favorable pressure gradients reduce the turbulence levels and length scales in supersonic flow. Wall roughness has been shown to reduce the large-scales in wall bounded flow. Based on these previous observations new questions have been raised. The fundamental questions this dissertation addressed are: (1) What are the effects of wall topology with sharp versus blunt leading edges? and (2) Is it possible that a further reduction of turbulent scales can occur if surface roughness and favorable pressure gradients are combined? To answer these questions and to enhance the current experimental database, an experimental analysis was performed to provide high fidelity documentation of the mean and turbulent flow properties along with surface and flow visualizations of a high-speed ( 2.86 M = ), high Reynolds number (Re 60,000 q ÃÂ» ) supersonic turbulent boundary layer distorted by curvature-induced favorable pressure gradients and large-scale ( 300 s k + ÃÂ» ) uniform surface roughness. Nine models were tested at three separate locations. Three pressure gradient models strengths (a nominally zero, a weak, and a strong favorable pressure gradient) and three roughness topologies (aerodynamically smooth, square, and diamond shaped roughness elements) were used. Highly resolved planar measurements of mean and fluctuating velocity components were accomplished using particle image velocimetry. Stagnation pressure profiles were acquired with a traversing Pitot probe. Surface pressure distributions were characterized using pressure sensitive paint. Finally flow visualization was accomplished using schlieren photographs. Roughness topology had a significant effect on the boundary layer mean and turbulent properties due to shock boundary layer interactions. Favorable pressure gradients had the expected stabilizing effect on turbulent properties, but the improvements were less significant for models with surface roughness near the wall due to increased tendency towards flow separation. It was documented that proper roughness selection coupled with a sufficiently strong favorable pressure gradient produced regions of Ã¢ÂÂnegativeÃ¢ÂÂ production in the transport of turbulent stress. This led to localized areas of significant turbulence stress reduction. With proper roughness selection and sufficient favorable pressure gradient strength, it is believed that localized relaminarization of the boundary layer is possible.

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Wang, Yi Jenny. "Equilibrium molecular dynamics study of heat conduction in octane". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97858.

Testo completo

Abstract (sommario):

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 73-79).
Fluids are important components in heat transfer systems. Understanding heat conduction in liquids at the atomic level would allow better design of liquids with specific heat transfer properties. However, heat transfer in molecular chain liquids is a complex interplay between heat transfer within a molecule and between molecules. This thesis studies the contribution of each type of atomic interaction to the bulk heat transfer in liquid octane to further the understanding of thermal transport between and within chain molecules in a liquid. The Green-Kubo formula is used to calculate thermal conductivity of liquid octane from equilibrium molecular dynamics, and the total thermal conductivity is split into effective thermal conductivities for the different types of atomic interactions in the system. It is shown that the short carbon backbone of octane does not dominate thermal transport within the system. Instead, the thermal resistance within a molecule is about the same as the resistance between molecules.
by Yi Jenny Wang.
S.M.

Gli stili APA, Harvard, Vancouver, ISO e altri

4

Ebadi, Alireza. "Transport of heat and momentum in non-equilibrium wall-bounded flows". Thesis, University of New Hampshire, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10241615.

Testo completo

Abstract (sommario):

Transport of momentum and heat in non-equilibrium wall-bounded flows is studied analytically and experimentally to better understand the underlying physics, transition dynamics, and appropriate flow scaling in non-equilibrium flows. Non-equilibrium flows, in which the mean flow time scales are comparable to turbulent flow time scales, do not exhibit universal behaviors and cannot be characterized only in terms of local parameters. Pressure gradients, fast transients and complex geometries are among the sources that can perturb a flow from an equilibrium state to a non-equilibrium state. Since all or some of these perturbation sources are present in many engineering application relevant flow systems and geophysical flows, understanding and predicting the non-equilibrium flow dynamics is essential to reliably analyze and control such flows.

Reynolds-averaged Navier-Stokes (RANS) simulations are extensively used to model and predict fluid transport across a wide range of disciplines. The shortcoming is that most turbulence models used in RANS simulations use almost exclusively wall-models based on equilibrium boundary layer behaviors, despite the fact that many basic assumptions required of equilibrium boundary layers are not satisfied in the majority of the flow systems in which RANS simulations are used. In particular, pressure gradients, dynamic walls, roughness, and large-scale flow obstacles produce boundary layers that are strongly non-equilibrium in nature. Often the prediction of RANS simulations in complex engineering systems (with perturbations that induce non-equilibrium flow behaviors) fail spectacularly primarily owing to the fact that the turbulence models do not incorporate the correct physics to accurately capture the transport behaviors in non-equilibrium boundary layers. These failures result in over-engineered and hence, less efficient designs. This lack of efficiency manifests in higher economic and environmental costs. The broad objective of this dissertation work is to develop analytical and experimental tools needed to better understand the underlying transport physics in non-equilibrium boundary layers.

The key scaling parameter in wall-bounded flows is the wall flux of momentum and heat. It follows that an accurate determination of the wall fluxes is essential to study the dynamics of non-equilibrium wall-bounded flows. As part of this dissertation research, an integral method to evaluate wall heat flux suitable for experimental data is developed. The method is exact and does not require any streamwise gradient measurements. The integral method is validated using simulation and experimental data. Complications owing to experimental limitations and measurement error in determining wall heat flux from the method are presented, and mitigating strategies are described. In addition to the ability to evaluate the wall heat flux, the method provides a means to connect transport properties at the wall to the mean flow dynamics.

The integral method is further developed to formulate a novel and robust validation technique of Reynolds-averaged Navier-Stokes (RANS) turbulence models. Validation of the turbulence models employed in RANS simulations is a critical part of model development and application. The integral based validation technique is used to evaluate the performance of two low-Reynolds-number and two high-Reynolds number RANS turbulence models of reciprocating channel flow, and results are compared to the so-called standard validation technique. While the standard validation technique indicates that the low-Reynolds-number models predict the wall heat flux well, the integral validation technique shows that the models do not accurately capture the correct physics of thermal transport in reciprocating channel flow. Moreover, it shows that the correct prediction of the wall heat flux by the models is owed to the serendipitous cancellation of model errors.

One of the identified failures of the RANS simulations of reciprocating channel flow is the inability to accurately predict the flow dynamics during the laminar-turbulence transition. The development of improved RANS turbulence models, therefore requires an improved understanding of the underlying laminar-turbulent transition mechanisms. As part of this dissertation work, the balance of the leading order terms in the phase-averaged mean momentum equation are used to study the transition mechanism in a reciprocating channel flow. It is concluded that the emergence of an internal layer in the late acceleration phase of the cycle triggers the flow to transition from a self-sustaining transitional regime to an intermittently turbulent regime. In the absence of this internal layer, the flow remains transitional throughout the cycle.

Lastly, since experimental studies of heat transfer in non-equilibrium wall-bounded flows are very limited, a unique experimental facility was developed to study non-equilibrium boundary layers with heat transfer. The facility consists of boundary layer wind tunnel that nominally measures 303×135 mm cross-section and 2.7m in length. A freestream heater and a thermal wall-plate are used to maintain the desired outer and inner thermal boundary conditions, respectively. A rotor-stator assembly is fabricated to generate a periodic pressure gradient used to produce pulsatile boundary layer flow. (Abstract shortened by ProQuest.)

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Kuo, Long-Sheng 1969. "Non-equilibrium energy transfer and phase change during intense picosecond laser-metal interactions". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/34346.

Testo completo

Abstract (sommario):

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.
Includes bibliographical references (leaves 55-57).
Laser interactions with metals involve absorption of photon energy by electrons, energy coupling between electrons and the lattice, and energy transport by diffusion of electrons and lattice vibrations. During picosecond laser irradiation of metal films, electrons and the lattice are not in thermal equilibrium. On the other hand, rapid laser heating produces a large degree of superheating and undercooling during melting and solidification. First, this work investigates experimentally non-equilibrium heating processes during intense picosecond laser heating of metal films. Results show excellent agreement with predictions of the two-step radiation heating model. Second, this work develops a general model to characterize both non-equilibrium energy deposition and phase change processes. The predictions show that the non-equilibrium heating processes significantly increase the laser melting threshold, enlarge the thermal-affected region, reduce the lattice temperature rise, prolong the phase change duration, and reduce the solidification speed. These results are important for materials processing using ultrashort pulsed lasers.
by Long-Sheng Kuo.
S.M.

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Laradji, Mohamed. "Ternary mixtures of water, oil and surfactants : equilibrium and dynamics". Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39483.

Testo completo

Abstract (sommario):

The equilibrium phase behaviour of ternary mixtures of water, oil and surfactants is examined using both a lattice-gas model and a Ginzburg-Landau model. The lattice model is based on the Blume-Capel model with additional orientational degrees of freedom for surfactants, and the Ginzburg-Landau model is based on two local scalar fields. When the concentrations of water and oil are equal the following phases are observed: a water and oil rich phase, a lamellar phase, and a disordered phase which is divided into an ordinary disordered fluid and a microemulsion region. In the lattice model, a square phase is also observed. The effects of fluctuations on the lattice model is studied via Monte-Carlo simulations and by the Langevin approach in the Ginzburg-Landau model. In both cases, we found that in the vicinity of the water/oil coexistence region, the lamellar phase becomes unstable against the microemulsion.
Furthermore, we have studied the effects of surfactants on the dynamics of phase separation of two immiscible fluids, and found a drastic alteration in the kinetics. In particular, we found that surfactants slow down the growth to a non-algebraic one leading eventually to a microphase separation.

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Karlsson, Jens Olof Mattias. "Non-equilibrium phase transformations of intracellular water : applications to the cryopreservation of living cells". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11623.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Courtland, Hayden-William C. "Equilibrium mechanical properties of two noncollagenous cartilages in the sea lamprey, Petromyzon marinus". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ63256.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

9

O'Neill, Maura Rose. "Digital Rotating Unbalance Identification and Parametric Determination of Counterbalance Placement for Predictable Dynamic Behavior". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500563587083873.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Apte, Pankaj A. "Phase equilibria and nucleation in condensed phases a statistical mechanical study /". Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1135876018.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

11

Cooper, Moogega Fridman Alexander A. "Elucidation of levels of bacterial viability post-non-equilibrium dielectric barrier discharge plasma treatment /". Philadelphia, Pa. : Drexel University, 2009. http://hdl.handle.net/1860/3181.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Cheluget, Eric Lanǵat. "Vapor-liquid equilibrium studies. Prediction for ill-defined mixtures and modification of a data collecting apparatus". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61908.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Jones, Gareth Paul. "Acoustic sensitivity of the vestibular system and mechanical analysis of the tectorial membrane in mammals". Thesis, University of Sussex, 2012. http://sro.sussex.ac.uk/id/eprint/38740/.

Testo completo

Abstract (sommario):

This thesis cover two separate topics related to the function of the mammalian inner ear. Acoustic sensitivity of the vestibular system. Data are presented showing facilitation of the auditory startle response by tones outside the range of the mouse cochlea. The sensation of these low frequency tones is demonstrated to be mediated via the acoustically sensitive sacculus of the vestibular system by data collected from Nox3-/- mice. These mice lack the otoconia of the vestibular system and, unlike the wild-type mice, only show facilitation to tones within the range of the mouse cochlea, and not in response to tones <4 kHz. The mechanical properties of the tectorial membrane (TM). The mechanical properties of the TM are investigated using a laser interferometer-based method for tracking the longitudinal propagation of a radially shearing travelling wave in segments of TM isolated from the basal and apical regions of the wild-type cochlea. The properties of these travelling waves (wave propagation velocity and wave amplitude decay) are tracked over a range of stimulus frequencies (1-20 kHz). The viscoelastic properties, shear storage modulus (G') and shear viscosity (η), are estimated over this frequency range and are found to be lower in the apical TM segments compared to the basal TM segments, indicating the apical region of the TM is less stiff than the basal region. These data are compared to data collected from TM segments isolated from the basal cochlear region of three mutant groups, each lacking expression of TM-specific proteins; α-tectorin (TectaY1870C/+), β-tectorin (Tectb-/-) and otoancorin (OtoaEGFP/EGFP), using the same laser interferometer-based method. The viscoelastic properties are estimated for each of the mutants and indicate varying degrees of loss of structural integrity in their respective TM segments. Reflective difference between the wild-types and mutants are also observed and compared.

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Apte, Pankaj A. "Phase equilibria and nucleation in condensed phases: a statistical mechanical study". The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1135876018.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Uenishi, Keisuke. "Formation of Non-equilibrium Phases in the Alloy Systems with Positive Heat of Mixing by Mechanical Alloying". Kyoto University, 1992. http://hdl.handle.net/2433/74609.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Raghavan, Ashwin Ph D. Massachusetts Institute of Technology. "Multi-scale modeling tools for coupled reaction, phase equilibrium and two-phase mixing phenomena with application to supercritical water heavy oil upgrading process". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121848.

Testo completo

Abstract (sommario):

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 253-261).
Supercritical water heavy oil upgrading, which has the potential for high distillate liquid yields with lower coke formation, is a complex process involving coupled reactions, phase equilibrium and two-phase mixing phenomena. This thesis presents the development of a range of models and tools to simulate such processes at different scales with varying levels of fidelity in describing the underlying physical phenomena. Over the past decade, a number of experiments have been performed in batch reactors to study the upgrading of various heavy oils and crude oil vacuum residua through both oil-phase pyrolysis and reaction in the presence of supercritical water (SCW). While these studies indicate that the presence of SCW can significantly affect the outcomes of the upgrading process, there remains a lack of clarity on whether thermolytic processing in the presence of SCW is indeed significantly beneficial as opposed to pure oil phase pyrolysis and if so, at what operating conditions.
In addition, modeling tools coupling the reaction kinetics and phase equilibrium, which can provide deeper insight into the process and the underlying phenomena have been lacking. The first part of this thesis describes the development and application of a two-phase stirred reactor (TPSR) model which couples sub-models for the phase-specific reaction kinetics and multi-component hydrocarbon-water phase equilibrium. Using this model, separate lumped kinetics rate parameters for the oil and SCW phases were inferred that best fit batch reactor experimental data. Analysis of the obtained kinetics parameters reveal the following crucial insights on the chemical pathways involved in the SCW upgrading process (i) the primary coke precursor formation pathway is not suppressed in the SCW phase and (ii) only the secondary pathway towards coke precursors from product distillate species is suppressed in the SCW phase, especially at higher operating temperatures.
The TPSR model was then applied to evaluate the performance of heavy oil upgrading using SCW in an oil-water co-flow (visbreaking) Next, an extractive upgrading reactor design was hypothesized to improve high-value distillate liquid product yields and reduce undesirable extrinsic coke formation by removing the distillate products safely out of the reactor in a SCW up-flow thereby preventing their further participation in secondary retrograde combination reactions towards more aromatic coke precursors and low-value gas. The TPSR model was used to evaluate the performance of the SCW extractive upgrading process in terms of distillate liquid yields and coke formation rates for heavy oil vacuum residue over a range of operating temperatures and water flow rates. The predictions demonstrate the significant potential of the extractive upgrading process to achieve the aforementioned objectives.
The effect of the extraction rate governed by the interphase mixing time-scale on the product yields and oil-inflow rate for steady-state operation was then quantified. The second part of the thesis describes the development of a computational fluid dynamics (CFD) framework and modeling tool for simulating the coupled two-phase flow and multi-component interphase mass transfer at near-critical/supercritical conditions in applications like SCW heavy oil upgrading. The CFD tool accounts for interface tracking in 2-D/3-D, intra-phase species diffusion, phase-equilibrium limited interphase species transfer and non-ideal thermodynamics. In this tool, the interface is tracked with a conservative sharp interface capturing Volume of Fluid (VoF) scheme using (i) a Piece-wise Linear Interface Reconstruction (PLIC) algorithm (ii) an unsplit geometrical advective flux calculation and (iii) a flux-polyhedron correction.
The intra-phase species diffusion is handled using a corrected face-normal gradient calculation accounting for the arbitrary shape and size of phase-specific sub-cells. The interphase mass transfer is computed as a source term consistent with the local phase equilibrium and transport flux constraints at the interface. Finally, the phase-volume change is rigorously accounted for in the discrete pressure equation. The tool was implemented on an open-source CFD platform ensuring compatibility with unstructured mesh information and parallel processing constraints. Finally, the developed CFD tool was applied to determine the two-phase mixing rates in an extractive upgrading configuration for water flow rates of interest. The predictions suggest that the earlier assumption of instantaneous phase-equilibration with respect to the time-scale of reactions relevant in the SCW heavy-oil upgrading process is a reasonable approximation for centimeter-scale reactors.
Furthermore, the scaling of the total oil-water interfacial area in the reactor and the average Sherwood number with the water inlet velocity and oil-water interfacial tension were established, providing insight into ways to manipulate the two-phase mixing rate to enable control of the extractive upgrading process at higher operating temperatures.
by Ashwin Raghavan.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Mechanical Engineering

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Andrienko, Daniil. "Non-equilibrium Models for High Temperature Gas Flows". Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1405505300.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Essenhigh, Katherine Anne. "Energy transfer and chemistry of carbon monoxide in vibrational mode non-equilibrium". Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1124292824.

Testo completo

Abstract (sommario):

Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xiv, 172 p.; also includes graphics (some col.). Includes bibliographical references (p. 167-172). Available online via OhioLINK's ETD Center

Gli stili APA, Harvard, Vancouver, ISO e altri

19

Mehta, Rajeev. "A study of the mechanical properties and the equilibrium nature of the blend of thermotropic liquid crystalline copolyesters". Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/53728.

Testo completo

Abstract (sommario):

This work deals with the melt blend of 60/40 PHB/PET (p-hydroxybenzoic acid and polyethylene terephthalate) and 80/20 PHB/PET copolyesters in a 50:50 weight% ratio. Specifically, the interest was to determine as to how do the mechanical properties of the injection-molded parts from the blend compare with that of 70/30 PHB/PET composition and to find out if the melt blend obtained after a single extrusion pass represents an equilibrium composition blend. To determine the anisotropic mechanical properties, injection-molded plaques were obtained by injection-molding the blend at different temperatures. It was found that the tensile properties (tensile strength, modulus and elongation at break in the machine direction) of the blend increase with the increase in the injection-molding temperature (from 300 to 320°c) and then decrease. The flexural modulus of the injection-molded plaques (at an injection-molding temperature of 330°c) of a 50:50 blend of 60/40 PHB/PET and 80/20 PHB/PET mixed only in the injection-molded unit was 2.2 x 10⁶ psi which is 40% higher than that reported for the 60/40 PHB/PET, 100% higher than reported for either 80/20 PHB/PET or 70/30 PHB/PET. To determine the equilibrium nature of the blend, samples with different residence time in the extruder and the 70/30 PHB/PET samples were analyzed by means of Differential Scanning Calorimeter (DSC), Dynamic Mechanical Analysis (DMA), Thermal Mechanical Analysis (TMA), Scanning Electron Microscope (SEM) and Rheometrics Mechanical Spectrometer (RMS), and the mechanical properties of the injection-molded plaques were also determined. The DSC thermogram of the four extrusion pass blend showed multiple melting endotherms. Similar behavior was observed for a number of samples which had been annealed above the melt temperatures for different lengths of time. The formation of multiple peaks was attributed to the incomplete transesterification reaction in the extruder. The OMA results also indicated a substantial decrease in the melting temperatures with the increase in the number of extruder passes. A similar decrease in the melting temperatures has been reported in the literature for various polyesters undergoing transesterification reaction. The TMA results showed that the modulus versus temperature profiles (softening profiles) of one, two and three extrusion pass samples were the same but that of the four extrusion pass film was different and was closer to the softening profile of the 70/30 PHB/PET film. The softening profile of the four extrusion pass sample indicated the presence of crystallites of varying degrees of development, which corresponds well with the splitting peak phenomenon observed in the corresponding DSC thermograms. Thus, it is clear that a chemical reaction is occurring in the extruder. It is suspected that the observed decrease in the flexural properties with the increase in the number of extruder passes is due the transesterification reaction occurring in the extruder. Transesterification studies were also carried out in a cone & plate geometry in the RMS in a no-shear (simple melt annealing) and shearing environment on a larger time scale. From a comparison of the thermal behavior of the blend (as a function of the reaction time) in different environments, it was concluded that the transesterification reaction proceeds faster in the presence of deformation such as occurs in the extruder or in a simple shear flow and with an increase in temperature. Finally, to compare the rheological properties of the multiple extrusion pass and the 70/30 PHB/ PET samples, dynamic frequency sweeps were performed in the RMS at different temperatures. At a given frequency, the complex viscosity, storage modulus and loss modulus increased with an increase in the number of extrusion passes. This increase is unexpected. A number of explanations have been proposed to account for this increase in the rheological properties.
Master of Science

Gli stili APA, Harvard, Vancouver, ISO e altri

20

Shanmugam, Rajesh Kumar. "Experimental Study of Non Equilibrium Electrodeposition of Nanostructures on Copper and Nickel Used for Fuel Cell Application". University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302294800.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

21

Eckert, Zakari Sebastian. "Master Equation Modeling of a Nanosecond Pulsed Discharge in Nitrogen in Pin-to-Pin Geometry". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429191278.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

22

Gallagher, Michael J. Fridman Alexander A. "Partial oxidation and autothermal reforming of heavy hydrocarbon fuels with non-equilibrium gliding arc plasma for fuel cell applications /". Philadelphia, Pa. : Drexel University, 2010. http://hdl.handle.net/1860/3199.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Eckert, Zakari Sebastian. "Energy Transfer in Non-Equilibrium Reacting Gas Flows: Applications in Plasma Assisted Combustion and Chemical Gas Lasers". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515099058664013.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

24

Goldberg, Benjamin M. "Electric Field Measurements in Non-Equilibrium ElectricDischarge Plasmas Using Picosecond Four-Wave Mixing". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449236861.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Hilts, Wade William. "Emulating Balance Control Observed in Human Test Subjects with a Neural Network". PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4499.

Testo completo

Abstract (sommario):

Human balance control is a complex feedback system that must be adaptable and robust in an infinitely varying external environment. It is probable that there are many concurrent control loops occurring in the central nervous system that achieve stability for a variety of postural perturbations. Though many engineering models of human balance control have been tested, no models of how these controllers might operate within the nervous system have yet been developed. We have focused on building a model of a proprioceptive feedback loop with simulated neurons. The proprioceptive referenced portion of human balance control has been successfully modeled by a PD controller with a time delay and output torque positive feedback. For this model, angular position is measured at the ankle and corrective torque is applied about the joint to maintain a vertical orientation. In this paper, we construct a neural network that performs addition, subtraction, multiplication, differentiation and signal filtering to demonstrate that a simulated biological neural system based off of the engineering control model is capable of matching human test subject dynamics.

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Pond, Ian. "Toward an Understanding of the Breakdown of Heat Transfer Modeling in Reciprocating Flows". ScholarWorks @ UVM, 2015. http://scholarworks.uvm.edu/graddis/477.

Testo completo

Abstract (sommario):

Reynolds average Navier-Stokes (RANS) modeling has established itself as a critical design tool in many engineering applications, thanks to its superior computational efficiency. The drawbacks of RANS models are well known, but not necessarily well understood: poor prediction of transition, non-equilibrium flows, mixing and heat transfer, to name the ones relevant to our study. In the present study, we use a direct numerical simulation (DNS) of a reciprocating channel flow driven by an oscillating pressure gradient to test several low- and high-Reynolds' RANS models. Temperature is introduced as a passive scalar to study heat transfer modeling. Low-Reynolds' models manage to capture the overall physics of wall shear and heat flux well, yet with some phase discrepancies, whereas high-Reynolds' models fail. We have derived an integral method for wall shear and wall heat flux analysis, which reveals the contributing terms for both metrics. This method shows that the qualitative agreement appears more serendipitous than driven by the ability of the models to capture the correct physics. The integral method is shown to be more insightful in the benchmarking of RANS models than the typical comparisons of statistical quantities. This method enables the identification of the sources of discrepancies in energy budget equations. For instance, in the wall heat flux, one model is shown to have an out of phase dynamic behavior when compared to the benchmark results, demonstrating a significant issue in the physics predicted by this model. Our study demonstrates that the integral method applied to RANS modeling yields information not previously available that should guide the derivation of physically more accurate models.

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Reeder, Todd A. "Corrosion-related Gas Measurements and Analysis for a Suite of Coals in Staged Pulverized Coal Combustion". BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2230.

Testo completo

Abstract (sommario):

Eleven gas species, including CO, CO2, H2, H2O, H2S, HCl, NOX, O2, SO2, COS and SO3, were measured in a 150 kWth, staged, pulverized coal, down-fired combustor using a Fourier transform infrared (FTIR) spectrometer, gas chromatograph (GC), and a Horiba PG-250 5-gas analyzer. Additional gases such as HCN, NH3, CH4, and other hydrocarbons were also measured. Seven coals of varying rank and composition were investigated. Measurements were obtained in reducing (S.R. = 0.85) and oxidizing (S.R. = 1.15) conditions. In particular, sulfur- and chlorine-containing species including H2S, SO2, COS, SO3, and HCl are discussed. In the reducing zone, all four measured sulfur species were present although SO3 was only 1-3% of the total coal sulfur. A trade-off between SO2, H2S, and COS was clearly identifiable according to S.R. H2S and COS increased and SO2 decreased in highly reducing or high-CO regions. The total amount of sulfur in the measured species in the reducing zone was estimated to be about 65-80% of the total coal sulfur. The total amount of sulfur measured in the four gases increased linearly with coal sulfur in both the oxidizing and reducing zones for the seven coals considered. In the oxidizing zone, SO3 remained low (1-3% of total sulfur) with the only other measurable sulfur bearing species being SO2. Chlorine was found to be released in the reducing zone and form primarily HCl. As the HCl was transported into the oxidizing region, the chlorine remained as HCl. Measurement of HCl was difficult, making some of the data incomplete. The HCl concentration was found to be affected by the flow rate of gases into the sampling line and gas analyzers suggesting HCl is highly reactive and needs to be quenched rapidly or it will react during sampling. Several trends in the data were matched by equilibrium calculations including trends for H2S, COS and SO2 in both reducing and oxidizing conditions. SO3 did not match equilibrium although the amount of SO3 was proportional to the amount of sulfur in the coal. HCl, though consistent with cited literature for several coals, did not agree with equilibrium trends or values.

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Mittal, Arpit. "Prediction of Non-Equilibrium Heat Conduction in Crystalline Materials Using the Boltzmann Transport Equation for Phonons". The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316471562.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

29

Botha, Jan. "The development of a device for the investigation of dorsiflexion range of the ankle with a capacity to measure pathology, recovery and pharmacological benefit". Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/2086.

Testo completo

Abstract (sommario):

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005.
Various ways exist whereby balance abilities of the individual can be assessed. However, most of these are subjective methods. This thesis strives to demonstrate the effectiveness of a new device, the Dorsiflexometer that can be used to objectively assess one’s balance abilities. The Dorsiflexometer was constructed and mathematically modelled using appropriate simplifying assumptions. After its construction, the Dorsiflexometer was tested using two experimental set-ups to obtain raw data. Both these set-ups consisted of the two tiltable platforms equipped with three load cells each, the bridge amplifiers and the personal computer (PC). The only difference in the two experimental set-ups is in the type of test that was performed as well as the bridge amplifiers used. Numerous parameters, such as the radius of movement and the Lyapunov number can be extracted from the raw data. A computer program was written to analyse the raw data and present the results in a user-friendly manner. A new parameter, the Sway Index, was used to obtain a single balance value for the tested individual. This parameter proved useful in quantifying balance. An advanced patent search was carried out before the device was constructed. This was necessary to provisionally patent the device – official application number: 2003/6702.

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Baniahmad, Ata. "QUANTUM MECHANICAL Study and Modelling of MOLECULAR ELECTRONIC DEVICES". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13193/.

Testo completo

Abstract (sommario):

Molecular electronics pursues the use of molecules as fundamental electronic components. The inherent properties of molecules such as nano-size, low cost, scalability, and self-assembly are seen by many as a perfect complement to conventional silicon electronics. Molecule based electronics has captured the attention of a broad cross section of the scientiﬁc community. In molecular electronic devices, the possibility of having channels that are just one atomic layer thick, is perhaps the most attractive feature that takes the attention to graphene.The conductivity, stability, uniformity, composition, and 2D nature of graphene make it an excellent material for electronic devices. In this thesis we focused on Zigzag Graphene NanoRibbon(ZGNR) as a transmission channel. Due to the importance of an accurate description of the quantum eﬀects in the operation of graphene devices, a full-quantum transport model has been adopted: the electron dynamics has been described by Density Functional Theory(DFT) and transport has been solved within the formalism of Non-Equilibrium Green’s Functions (NEGF). Using DFT and NEGF methods, the transport properties of ZGNR and ZGNR doped with Si are studied by systematically computing the transmission spectrum. It is observed that Si barrier destroyed the electronic transport properties of ZGNR, an energy gap appeared for ZGNR, and variations from conductor to semiconductor are displayed. Its followed by a ZGNR grown on a SiO2 crystal substrate, while substituting the Graphene electrodes with the Gold ones, and its eﬀect on transmission properties have been studied. Improvement in transmission properties observed due to the formation of C-O bonds between ZGNR and substrate that make the ZGNR corrugated. Finally, we modeled a nano-scale Field Effect Transistor by implementing a gate under SiO2 substrate. A very good I-ON/I-OFF ratio has been observed although the device thickness.

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Mehta, Urmish R. "Optimal control of a high speed overhead crane including hoisting". Ohio : Ohio University, 1992. http://www.ohiolink.edu/etd/view.cgi?ohiou1172863064.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

32

Sung, Dejun. "Design and simulation of the Broom-balance vehicle system". Ohio : Ohio University, 1993. http://www.ohiolink.edu/etd/view.cgi?ohiou1176236797.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Allu, Pareekshith. "A Hybrid Ballistic-Diffusive Method to Solve the Frequency Dependent Boltzmann Transport Equation". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1451998769.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

34

Hassan, Mohamed K. I. "Novel Elastomers, Characterization Techniques, and Improvements in the Mechanical Properties of Some Thermoplastic Biodegradable Polymers and Their Nanocomposites". University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1086633832.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Nadimi, Ebrahim. "Quantum Mechanical and Atomic Level ab initio Calculation of Electron Transport through Ultrathin Gate Dielectrics of Metal-Oxide-Semiconductor Field Effect Transistors". Doctoral thesis, Universitätsbibliothek Chemnitz, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200800477.

Testo completo

Abstract (sommario):

The low dimensions of the state-of-the-art nanoscale transistors exhibit increasing quantum mechanical effects, which are no longer negligible. Gate tunneling current is one of such effects, that is responsible for high power consumption and high working temperature in microprocessors. This in turn put limits on further down scaling of devices. Therefore modeling and calculation of tunneling current is of a great interest. This work provides a review of existing models for the calculation of the gate tunneling current in MOSFETs. The quantum mechanical effects are studied with a model, based on a self-consistent solution of the Schrödinger and Poisson equations within the effective mass approximation. The calculation of the tunneling current is focused on models based on the calculation of carrier’s lifetime on quasi-bound states (QBSs). A new method for the determination of carrier’s lifetime is suggested and then the tunneling current is calculated for different samples and compared to measurements. The model is also applied to the extraction of the “tunneling effective mass” of electrons in ultrathin oxynitride gate dielectrics. Ultrathin gate dielectrics (tox<2 nm) consist of only few atomic layers. Therefore, atomic scale deformations at interfaces and within the dielectric could have great influences on the performance of the dielectric layer and consequently on the tunneling current. On the other hand the specific material parameters would be changed due to atomic level deformations at interfaces. A combination of DFT and NEGF formalisms has been applied to the tunneling problem in the second part of this work. Such atomic level ab initio models take atomic level distortions automatically into account. An atomic scale model interface for the Si/SiO2 interface has been constructed and the tunneling currents through Si/SiO2/Si stack structures are calculated. The influence of single and double oxygen vacancies on the tunneling current is investigated. Atomic level distortions caused by a tensile or compression strains on SiO2 layer as well as their influence on the tunneling current are also investigated
Die vorliegende Arbeit beschäftigt sich mit der Berechnung von Tunnelströmen in MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors). Zu diesem Zweck wurde ein quantenmechanisches Modell, das auf der selbstkonsistenten Lösung der Schrödinger- und Poisson-Gleichungen basiert, entwickelt. Die Gleichungen sind im Rahmen der EMA gelöst worden. Die Lösung der Schrödinger-Gleichung unter offenen Randbedingungen führt zur Berechnung von Ladungsverteilung und Lebensdauer der Ladungsträger in den QBSs. Der Tunnelstrom wurde dann aus diesen Informationen ermittelt. Der Tunnelstrom wurde in verschiedenen Proben mit unterschiedlichen Oxynitrid Gatedielektrika berechnet und mit gemessenen Daten verglichen. Der Vergleich zeigte, dass die effektive Masse sich sowohl mit der Schichtdicke als auch mit dem Stickstoffgehalt ändert. Im zweiten Teil der vorliegenden Arbeit wurde ein atomistisches Modell zur Berechnung des Tunnelstroms verwendet, welche auf der DFT und NEGF basiert. Zuerst wurde ein atomistisches Modell für ein Si/SiO2-Schichtsystem konstruiert. Dann wurde der Tunnelstrom für verschiedene Si/SiO2/Si-Schichtsysteme berechnet. Das Modell ermöglicht die Untersuchung atom-skaliger Verzerrungen und ihren Einfluss auf den Tunnelstrom. Außerdem wurde der Einfluss einer einzelnen und zwei unterschiedlich positionierter neutraler Sauerstoffleerstellen auf den Tunnelstrom berechnet. Zug- und Druckspannungen auf SiO2 führen zur Deformationen in den chemischen Bindungen und ändern den Tunnelstrom. Auch solche Einflüsse sind anhand des atomistischen Modells berechnet worden

Gli stili APA, Harvard, Vancouver, ISO e altri

36

Kakitani, Celina. "Estudo do equilíbrio de fases de hidratos de metano e da mistura metano e dióxido de carbono". Universidade Tecnológica Federal do Paraná, 2014. http://repositorio.utfpr.edu.br/jspui/handle/1/1035.

Testo completo

Abstract (sommario):

Petrobrás
Hidratos são estruturas cristalinas constituídas por moléculas de água e gás ou líquido, sendo que a estabilização dessa estrutura cristalina requer condições de altas pressões e/ou baixas temperaturas. A formação e a aglomeração de hidratos podem causar o bloqueio de linhas de transporte de óleo e/ou gás, reduzindo a eficiência do processo, danificando os equipamentos e comprometendo a segurança da parte operacional. Neste cenário, no presente trabalho é apresentado o estudo numérico-experimental de equilíbrio de fases dos hidratos para identificar as regiões de formação e adequar as condições de operação na indústria petrolífera. Para a predição das condições de formação dos hidratos é desenvolvido um modelo termodinâmico baseado na teoria de sólido ideal de van der Waals e Platteeuw. O modelo é fundamentado na igualdade dos potenciais químicos de todas as espécies em todas as fases (água líquida, hidrato e vapor). Para os cálculos de equilíbrio da fase hidrocarboneto foi utilizada a equação de estado de Soave Redlich-Kwong e o método da secante foi utilizado para solucionar o modelo iterativamente. As medidas experimentais foram realizadas utilizando metano puro e a mistura metano (90 % em mol) e dióxido de carbono e os testes foram realizados em duas bancadas distintas, sendo os procedimentos realizados semelhantes, baseados no método isocórico pela monitoração da resposta da pressão do sistema com a variação da temperatura. Os resultados experimentais e numéricos obtidos foram comparados com dados da literatura com a finalidade de validar o modelo termodinâmico proposto, o aparato experimental e o procedimento adotado. O erro absoluto máximo entre os resultados obtidos experimentalmente e do modelo termodinâmico desenvolvido foi de 0,57%. Desta forma, nota-se os resultados apresentaram boa concordância entre os dados experimentais e os da modelagem numérica.
Hydrates are crystalline structures composed by molecules of water or liquid and gas, and the crystal structure that requires stabilization conditions of high pressure and/or low temperatures. The formation and agglomeration of hydrates can cause blockage of transmission lines oil and / or gas, reducing process efficiency, damaging the equipment and compromise the safety of the operating part. In this scenario, in this paper the numerical-experimental study of phase equilibria of hydrates is presented to identify the regions of formation and adjust the operating conditions in the oil industry. To predict hydrate formation conditions of a thermodynamic model based on the ideal solid solution theory by van der Waals and Platteeuw is developed. The model is based on the equality of the chemical potentials of all species in all phases (liquid water, vapor and hydrate). The SoaveRedlich-Kwong equation of state was employed for the phase equilibrium properties of the hydrocarbon fluid phase and the secant method was used to solve the model iteratively. Experimental measurements were performed using pure methane and methane mixture (90 mol%) and carbon dioxide, and the tests were performed on two separate stands, and similar procedures performed based on the isochoric method by monitoring the pressure response of the system with changes in the temperature. The experimental and numerical results were compared with literature data in order to validate the proposed thermodynamic model, the experimental apparatus and procedure adopted. The maximum absolute error between the experimental results and thermodynamic model was 0.57%. Thus, the results showed good agreement between experimental data and numerical modeling.

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Evans, Allan Kenneth. "Foundations of non-equilibrium statistical mechanics". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389831.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

38

AL-AZMI, BADER SHABEEB. "ANALYSIS OF TRANSPORT MODELS AND COMPUTATION ALGORITHMS FOR FLOW THROUGH POROUS MEDIA". The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1051059625.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

39

Merkli, Marco. "Positive commutator method in non-equilibrium statistical mechanics". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58618.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

40

Stapleton, Matthew Alexander. "Self-organised criticality and non-equilibrium statistical mechanics". Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443792.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

41

Tavassoli, Zohreh. "Topics in statistical mechanics of non-equilibrium systems". Thesis, Brunel University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326896.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

42

Hancock, Benjamin R. "Non-equilibrium Statistical Mechanics of Self-Propelled Particles". Thesis, Brandeis University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10929778.

Testo completo

Abstract (sommario):

Self-propelled particles (SPPs) are particles who, by themselves, are able to generate persistent motion by converting energy from an ambient reservoir into work. Collections of such particles form a class of intrinsically out-of-equilibrium fluids called active fluids which have energy input and dissipation at the scale of the particle constituents. Despite their non-equilibrium nature, large scale, cohesive structures will often spontaneously emerge. These structures can manifest in microscopic realizations such as collective cell motility but also in much larger objects like flocks of birds. In this work we apply the powerful tools of non-equilibrium statistical mechanics to study SPPs both at the single particle level and for collections of interacting particles.

The primary non-equilibrium characteristic of a SPP is the persistent correlation in its direction of motion. In the first theme, we address the following question: What is the effect of the details of the decorrelation process on long time properties of SPPs? This question is addressed in 2 parts. First, we compare the response of active Brownian particles and run-and-tumble particles when subject to external torques. Second, we investigate the nature of the non-equilibrium steady state by constructing the Smoluchowski equation. The second topic comes with the added feature that it allows us to address the validity of different approximation techniques available to deal with correlated stochastic processes.

In the second theme we construct a theoretical framework to characterize the non-equilibrium steady states of interacting SPPs. Starting from a microscopic model of self-propelled hard spheres we use tools of non-equilibrium statistical mechanics and the kinetic theory of hard spheres to derive a Smoluchowski equation for interacting active Brownian particles. We illustrate the utility of the statistical mechanics framework developed with two applications. First, we derive the steady state pressure of the hard sphere active fluid in terms of the microscopic parameters and second, we identify the critical density for the onset of motility-induced phase separation in this system. We show that both these quantities agree well with overdamped simulations of active Brownian particles with excluded volume interactions given by steeply repulsive potentials. The results presented in this section can be used to incorporate excluded volume effects in diverse models of self-propelled particles.

The final theme is an application of the self-propelled particle model to systems of motile cells. Some cells are able to deform the substrate they are adhered to and at the same time are able to sense and respond to their mechanical environment. For a collection of cells this can lead to a elastic interaction between them. In this study the cells are modeled as self-propelled “force dipoles” that deform the surface. We find that a combination of only activity and the medium mediated elastic interaction is enough to form the collective swarming, clustering, and streaming seen in some experiments. The numerical phenomenology is then rationalized using a mean-field hydrodynamic theory.

Gli stili APA, Harvard, Vancouver, ISO e altri

43

Nikoletopoulos, Theodore. "Equilibrium and non-equilibrium statistical mechanics of disordered Ising spin models with mixed range interactions". Thesis, King's College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412486.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

44

Zhu, Wenbo. "Soldering interconnects through self-propagating reaction process". Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/23259.

Testo completo

Abstract (sommario):

This thesis presents a research into the solder interconnects made through the reactive bonding process based on the self-propagating reaction. A numerical study of soldering conditions in the heat affected zone (HAZ) during bonding was initially carried out in order to understand the self-propagating reactive bonding and the related influencing factors. This was subsequently followed by an extensive experimental work to evaluate the feasibility and reliability of the reactive bonding process to enable the optimisation of processing parameters, which had provided a detailed understanding in terms of interfacial characteristics and bonding strengths. In addition, by focusing on the microstructure of the bonds resulted from the self-propagating reactions, the interfacial reactions and microstructural evolution of the bonded structures and effects of high-temperature aging were studied in details and discussed accordingly. To study the soldering conditions, a 3D time-dependent model is established to describe the temperature and stress field induced during self-propagating reactions. The transient temperature and stress distribution at the critical locations are identified. This thus allows the prediction of the melting status of solder alloys and the stress concentration points (weak points) in the bond under certain soldering conditions, e.g. ambient temperature, pressure, dimension and type of solder materials. Experimentally, the characterisation of interconnects bonded using various materials under different technical conditions is carried out. This ultimately assists the understanding of the feasibility, reliability and failure modes of reactive bonding technique, as well as the criteria and optimisation to form robust joints. The formation of phases such as intermetallic compounds (IMCs) and mechanism of interfacial reactions during reactive bonding and subsequent aging are elaborated. The composition, dimension, distribution of phases have been examined through cross-sectional observations. The underlying temperature and stress profile determining the diffusion, crystallization and growth of phases are defined by numerical predictions. XXI Through the comparative analysis of the experimental and numerical results, the unique phases developed in the self-propagating joints are attributed to the solid-liquid-convective diffusion, directional solidification and non-equilibrium crystallization. The recrystallization and growth of phases during aging are revealed to be resulted from the solid-state diffusion and equilibration induced by the high-temperature heating. In conclusion, the interfacial reactions and microstructural evolution of interconnect developed through self-propagating reactive bonding are studied and correlated with the related influencing factors that has been obtained from these predictions and experiments. The results and findings enable the extensive uses of self-propagating reactive bonding technology for new design and assembly capable of various applications in electronic packaging. It also greatly contributes to the fundamentals of the crystallization and soldering mechanism of materials under the non-equilibrium conditions.

Gli stili APA, Harvard, Vancouver, ISO e altri

45

Nowak, Sarah Alice. "Membrane mechanics and non-equilibrium transport in cell biology". Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1970611221&sid=7&Fmt=2&clientId=1564&RQT=309&VName=PQD.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

46

Prévost, Mireille. "Dynamical systems based non equilibrium statistical mechanics for Markov chains". Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104732.

Testo completo

Abstract (sommario):

We introduce an abstract framework concerning non-equilibrium statistical mechanics in the specific context of Markov chains. This framework encompasses both the Evans-Searles and the Gallavotti-Cohen fluctuation theorems. To support and expand on these concepts, several results are proven, among which a central limit theorem and a large deviation principle. The interest for Markov chains is twofold. First, they model a great variety of physical systems. Secondly, their simplicity allows for an easy introduction to an otherwise complicated field encompassing the statistical mechanics of Anosov and Axiom A diffeomorphisms. We give two examples relating the present framework to physical cases modelled by Markov chains. One of these concerns chemical reactions and links key concepts from the framework to their well known physical counterpart.
Nous présentons une structure mathématique de la physique statistique hors d'équilibre appliquée aux chaînes de Markov. Cette structure comprend les théoremes de fluctuations de Evans-Searles et de Gallavotti-Cohen. Afin de supporter et enrichir ces concepts, plusieurs résultats sont presentés, notamment un théoreme central limite ainsi qu'un principe de grandes deviations. Il y a deux principales raisons d'étudier les chaînes de Markov. Premièrement, elles modélisent une grand variété de systèmes physiques. Ensuite, leur simplicité permet une introduction facile a un vaste champ comprenant la mécanique statistique des difféomorphismes d'Anosovet Axiome A. Nous présentons deux examples permettant de lier la structure présente a des cas physiques modelés par des chaînes de Markov. Un de ces examples concerne les réactions chimiques et établit un lien entre les concepts clés de la structure et leurs homologues physiques bien connus.

Gli stili APA, Harvard, Vancouver, ISO e altri

47

Ottobre, Michela. "Asymptotic analysis for Markovian models in non-equilibrium statistical mechanics". Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9797.

Testo completo

Abstract (sommario):

This thesis is mainly concerned with the problem of exponential convergence to equilibrium for open classical systems. We consider a model of a small Hamiltonian system coupled to a heat reservoir, which is described by the Generalized Langevin Equation (GLE) and we focus on a class of Markovian approximations to the GLE. The generator of these Markovian dynamics is an hypoelliptic non-selfadjoint operator. We look at the problem of exponential convergence to equilibrium by using and comparing three different approaches: classic ergodic theory, hypocoercivity theory and semiclassical analysis (singular space theory). In particular, we describe a technique to easily determine the spectrum of quadratic hypoelliptic operators (which are in general non-selfadjoint) and hence obtain the exact rate of convergence to equilibrium.

Gli stili APA, Harvard, Vancouver, ISO e altri

48

Chin, Chen-Shan. "Stochastic fluctuations far from equilibrium : statistical mechanics of surface growth /". Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/9759.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

49

Štěpánek, Roman. "Studium substrukturních změn ultrajemnozrnných Mg-slitin při cyklickém zatěžování a teplotní expozici". Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-263403.

Testo completo

Abstract (sommario):

This thesis deals with complex analysis of fine-grained magnesium alloy AZ91 prepared by ECAP process. Mechanical properties of investigated alloy in different states at various external conditions are compared. The structure of this material is inherently unstable therefore changes on microstructural and sub-microstructural level occur during thermal exposure and/or mechanical loading. These changes are analysed and quantified for investigated alloy in selected states in this thesis.

Gli stili APA, Harvard, Vancouver, ISO e altri

50

Turnbull, R. W. "Approximation schemes for statistical mechanics in the complex temperature plane". Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376171.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Tesi sul tema "Mechanical equilibrium"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili