Dissertations / Theses on the topic 'Double Layer'
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1
Mitsos, Ioannis. "Double-layer tensegrity grids." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648489.
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Lécz, Zsolt. "Laser ion acceleration from a double-layer metal foil." Phd thesis, TU Darmstadt, 2013. https://tuprints.ulb.tu-darmstadt.de/3335/1/PHD_final.pdf.
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The laser-ion acceleration with ultra-intense and ultra-short laser pulses has opened a
new field of accelerator physics over the last decade. Fast development in laser systems are
capable of delivering short pulses of a duration of a few hundred femtoseconds at intensities
between 10^18-10^20 W/cm2. At these high intensities the laser-matter interaction induces
strong charge separation, which leads to electric fields exceeding the acceleration gradients
of conventional devices by 6 orders of magnitude. The particle dynamics and energy
absorption of the laser pulse can be understood by means of high-performance simulation
tools.
In the framework of the LIGHT (Laser Ion Generation, Handling and Transport) project
our goal is to provide an analytical description of the 3D distribution of the protons accelerated
via TNSA (Target Normal Sheath Acceleration). In this acceleration mechanism
the short pulse impinging on a metal foil heats the electrons to relativistic energies, which
triggers the strong charge separation field on the opposite target surface (Debye-sheath).
The accelerated light ions (proton, carbon, oxygen) observed in the experiments originate
from the contamination layer deposited on the surface. The thickness of this layer in the
experiments is not known exactly. According to our study these ions can be accelerated in
three different regimes depending on layer thickness: quasi-static acceleration (QSA, for
thin layers), plasma expansion (for thick layers) and a not well understood intermediate
(or combined) regime.
In a laser-plasma simulations time-dependent hot electron density and temperature are
observed, therefore we performed plasma simulations with a well defined and constant
initial hot electron distribution. Thus the simulation results are easier to compare with
analytical models. In our case the theoretical investigation of the TNSA involves the
understanding of the charge separation effects at the surface of a two-temperature plasma
and the consequent proton acceleration in one dimension. We omit the detailed dynamics
of the laser-plasma interaction by assuming a preheated electron distribution. With our 1D
electrostatic simulations we investigate the influence of the proton layer thickness on the
TNSA energy spectrum. Additionally we investigate the divergence of the protons using
2D simulations: In these we simulate the heating of the electrons by the laser pulse.
Numerical studies in this work were carried out using a Particle-in-Cell (PIC) plasma
simulation code (VORPAL). The target is defined as a single-ionized plasma with a doublelayer
structure: a bulk layer of heavy ions, which represents the metal foil itself and a much
thinner proton layer, which serves as the contamination layer. The layer is considered thin
if it is thinner compared to the skin depth of the accelerating electric field. For a thin
proton layer the quasi-static acceleration is the governing mechanism. When the proton
layer is larger than skin depth the process can be described as plasma expansion.
I found that the energy and phase-space distribution of the protons strongly depends
on the layer thickness. In the QSA regime the proton spectrum shows a nearly monoenergetic
feature, but the maximum energy is typically low compared to the plasma expansion regime, where the protons have a broad exponential energy spectrum. For the
plasma expansion we observe a cut-off energy that logarithmically depends on the acceleration
time.
The simulation results in these two extreme cases for one- and two-temperature plasmas
have been extensively compared to analytical predictions showing an overall good
agreement. In the intermediate regime an analytical expression could be obtained for the
energy conversion from electrons to protons as a function of electron parameters and layer
thickness. By changing the layer thickness a smooth transition between the two extreme
cases could be identified.
The proton layer thickness also has an impact on the transversal acceleration, which
defines the divergence of a proton beam. In the two-dimensional TNSA simulations a laser
pulse is needed to generate the hot electron population in the plasma. The simulations show
that theoretically with the right laser pulse duration and layer thickness the divergence
of the most energetic protons can be reduced almost to zero. In the QSA regime the
transversal distribution and temperature of the hot electrons changes too quickly compared
to the time-scale of the acceleration. The analytical treatment of the divergence is only
possible for the thick layers, where the plasma expansion model is suitable to describe the
physics. The model derived in this work can be used to reconstruct the whole velocity
phase-space of the protons in 3D. Therefore it enables us to perform particle tracking and
beam optics simulations with realistic TSNA proton bunch. The envelope angle of the
protons measured in experiments can be also reproduced using our 2D model.
The beam quality during motion through magnetic focusing and energy selection systems
downstream of the laser acceleration is sensitive to the initial distribution. After
benchmarking our analytic models, simulation results and measurements with each another,
we are confident we can now provide sufficiently realistic particle distributions to be
expected a few mm from the target in TNSA. Using our particle distributions as input, the
effect of co-moving electrons, the degradation of the transverse emittance and chromatic
aberration effects can be investigated. Thereby this study hopefully contributes to the goal
of the Light project: Coupling the new laser ion acceleration techniques to conventional
accelerator facilities.
3
Shlapunov, Alexander. "On Iterations of double layer potentials." Universität Potsdam, 2000. http://opus.kobv.de/ubp/volltexte/2008/2568/.
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We prove the existence of Hp(D)-limit of iterations of double layer potentials constructed with the use of Hodge parametrix on a smooth compact manifold X, D being an open connected subset of X. This limit gives us an orthogonal projection from Sobolev space Hp(D) to a closed subspace of Hp(D)-solutions of an elliptic operator P of order p ≥ 1. Using this result we obtain formulae for Sobolev solutions to the equation Pu = f in D whenever these solutions exist. This representation involves the sum of a series whose terms are iterations of double layer potentials. Similar regularization is constructed also for a P-Neumann problem in D.
4
Kaufmann, Stefan. "Charge transfer through layers of self-assembling molecules : double-layer studies." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359049.
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Affan, Amer. "Collapse of double-layer space grid structures." Thesis, University of Cambridge, 1987. https://www.repository.cam.ac.uk/handle/1810/250905.
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This dissertation is concerned with the behaviour of square-on-square double-layer space grids (DLSG's) and in particular their collapse mechanisms after initial buckling. A detailed review of the methods used for collapse analysis of these structures is conducted, which shows that their collapse can be of progressive nature. An outline of the remedies that have been suggested to make safe their collapse behaviour is given, and it traces the line for further study. The present investigation starts by describing the redundancy in these regular pin-jointed assemblies in terms of unit states of self-stress. This enables us to understand, by means of the extended Maxwell rule, how it is that mechanisms of collapse can occur when relatively few bars in the assembly have failed. The influence of boundary conditions on the mechanisms of collapse and its progressive nature is also investigated. This method of analysis is verified by detailed examination of several previously reported experimental results, and some conclusions can be drawn. The prestressing of statically indeterminate assemblies by means of lack-of-fit is investigated in the hope of changing their collapse characteristics. The unit state of self-stress has been used to explain a method for selecting the bars that can be shortened/lengthened in order to impose a prescribed state of self-stress, and the scope for achievable patterns of bar tensions has been described. A by-product of the investigation is an algorithm which calculates the required lack-of-fit to impose an initial state of self-stress which maximizes the load-carrying capacity of indeterminate trusses. Using the formulae derived for prestress, a statistical analysis is developed to estimate initial bar tensions due to random lack-of-fit in order to obtain a realistic estimate of the load-factor of an assembly before initial bar failure. Furthermore, we have argued and demonstrated how backlash at the bar-joint connection may have a beneficial effect in reducing substantially initial bar tensions due to the inevitable lack-of-fit on account of manufacturing errors of bars. An extensive experimental program has been conducted to verify the assumptions adopted and formulae derived in this dissertation.
6
Tang, Wang-Rei 1975. "Design and analysis of double-layer grids." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80176.
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New, David Allen 1976. "Double layer capacitors : automotive applications and modeling." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28337.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 223-227).
This thesis documents the work on the modeling of double layer capacitors (DLCs) and the validation of the modeling procedure. Several experiments were conducted to subject the device under test to a variety of charging/discharging profile and temperatures in an effort to simulate the various conditions such a device might encounter in an automotive type application. High and low current charging profiles were performed for both charge/discharge and charge/hold/discharge type experiments. Low temperature ([approx.] -25 ⁰C), room temperature ([approx.] 21 ⁰C), and high temperature experiments ([approx.] 50 ⁰C) were performed for the investigation of temperature effects on these devices. The derived DLC model was used in PSpice® and Matlab® simulations to determine how accurately the model could predict the performance of the device. The nonlinear characteristics of the device were also investigated and the nonlinear modeling information presented as an addition to the basic DLC model. Device variation was explored for a small sample of these devices in an effort to gain insight on the range of tolerances for modern devices. This work also presents an extensive look into the variety of electrochemical capacitor devices under investigation and in use today. An explanation of these devices and their distributed resistances and capacitance is included. This thesis gives a detailed look into the experimental setups and testing procedures used to test the devices, the simulations for the comparison, and presents the results of the comparison. Finally, this thesis documents the conclusion that this simple model procedure adequately predicts the performance of the device under these various performance profiles.
by David Allen New.
S.M.
8
Sahol, Hamid Yazmin. "Progressive collapse of double layer space trusses." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/808321/.
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This study deals with the progressive collapse of full scale square-on-square double-layer space truss (DLST) systems. The failure of certain space structures in recent years, ranging from a lattice dome in Romania, Burcharest 1963 to the DLST in Hartford USA, 1978 and the recent collapse of the Sultan Zainal Abidin Stadium, a double-layer space frame constructed in Malaysia, 2009, gives an insight into how sensitive some space structures are to progressive collapse. These tragic incidents have provided very valuable lessons for designers of the importance of understanding progressive collapse in these structural configurations. By understanding what caused such failures engineers may avoid any reoccurrence and in addition help to develop safer structures. Hence, a study of this particular problem has been conducted and the results obtained are presented in the thesis. Evaluation on the consequences of progressive collapse leads to the determination of structural Vulnerability Index due to sudden loss of an individual member (Case 1) or losses of members progressively (Case 2). In order to trace the collapse behavior a nonlinear analysis subject to increasing applied load was used. However, it is difficult for engineers to perform this nonlinear analysis due to its complexity. Hence, a simple linear analysis as an alternative method was used whereby assessment of Vulnerability Index using linear analysis is carried out using two different approaches, i.e. Rate Factor and Probabilistic Approach. Since a DLST has large number of members which correspond to a large data set, hence, these two proposed approaches are suitable. A close statistical correlation between both approaches indicates that there is a high correlation between both approaches. To ensure reliability of the proposed approaches, their results are compared using nonlinear collapse analysis and the results are found to be in good agreement. The solution strategy used to analyse the full scale models was first tested using small scale models. The numerical results of the small scale models have been verified with pre-existing experimental results and good agreements between the results are obtained. Behavior of each DLST member and also the overall structural behavior can be obtained from the nonlinear analysis. There are three different boundary conditions of the DLSTs considered. Vulnerability of the DLSTs susceptible to progressive collapse are identified and then are compared for the identification of efficient structures. The Vulnerability Index of the DLST helps engineers to discover failures that may occur due to damage or loss of its members.
9
Cagle, Clint William. "Charging kinetics of electric double layer capacitors." Connect to this title online, 2009. http://etd.lib.clemson.edu/documents/1263402254/.
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Premathilake, Dilshan V. "Vertically Oriented Graphene Electric Double Layer Capacitors." W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639673.
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Vertically oriented graphene nanosheets (VOGN) synthesized by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) have been fabricated as electrical double layer capacitors (EDLCs). The relatively open morphology of the films provided good frequency response, but had limited capacitance compared to present day activated carbon EDLCs. The objective of this research was to improve the capacitance of these films to a commercially viable level while maintaining sufficient frequency response for AC filtering. The growth of VOGN on Ni and Al substrates has been studied in this work. The native oxide on Ni was thinned at temperatures above ~600ºC with the oxygen from the surface oxide dissolving into the bulk, thus creating a low resistance ohmic contact that reduced the overall equivalent series resistance (ESR). Aluminum was studied because it is the primary substrate material used in electrolytic capacitors. However, it was much more difficult to work with because of its tenacious surface oxide. The maximum capacitance for a 10-minute VOGN/Ni growth observed was ~260µF/cm2, at temperature 850ºC, at 120 Hz, but the morphology was not very ordered. The best combination of capacitance (~160 µF/cm2) and frequency response (phase angle near -85º up to ~3000 Hz) was grown at 750ºC. The capacitance of VOGN/NI was further improved by using coatings of carbon black by an aerosol spray method. A capacitance of 2.3 mF/cm2 and frequency response phase angle near -90º at 120 Hz was achieved. It is the highest specific capacitance for an EDLC, reported in the literature, to date, suitable for AC filtering. Employing Al as a substrate required a novel method of plasma sputter cleaning of the oxide near the Al melting point (660ºC) and superimposing VOGN growth to prevent further oxidation. Initial results were ~80 µF/cm2 at a temperature of 620ºC with frequency response phase angle near -90º. Modeling of a uniform coating of carbon black (100 nm thick) on this underlying VOGN/Al architecture suggests that a capacitance of near 50 mF/cm2 can be achieved thus making this a potentially viable replacement for electrolytic capacitors. Another approach to commercialization of VOGN/Ni EDLCs has been studied by using a single substrate sheet interdigitated pattern design to create a low volume capacitor. A YAG laser was used to ablate resistance lines in the film resulting in a sinuous, square pattern on a VOGN/Ni coated alumina substrate and utilizing a gel electrolyte to create the EDLC.
11
Lucio, Anthony Joseph. "The electrochemical double layer in ionic liquids." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6183.
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The electrochemical double layer (EDL) at the solid–liquid interface is the near surface region where important electrochemical processes (e.g., electrodeposition, corrosion, and heterogeneous catalysis) take place. Subtle changes in the electrode surface material/topography and the nature of the fluid medium can drastically alter interactions between liquid molecules and the solid surface. A better understanding of this interfacial region can help advance numerous applied fields, such as battery technologies, solar cells, double layer capacitors, and carbon dioxide capture/conversion.
Ionic liquids (IL) are an emerging class of solvents that could replace traditional aqueous/non-aqueous solvents due to their advantageous physiochemical properties (e.g., wide solvent window, high thermal stability, and excellent solvating power). However, our understanding of the near-surface structure of ILs in the EDL is still being developed. This thesis focuses on the fundamental electrochemical behavior of ILs to help understand its interfacial behavior in three main areas: 1) the nature of capacitance-potential relationships in neat ILs, 2) the role of ‘user-defined’ experimental variables on capacitive electrochemical measurements, and 3) the impact of IL + water mixtures on experimental data.
The general shape of capacitance-potential curves can suggest at the broad architecture of the EDL region. Fundamental capacitive studies of the IL EDL show a wide range of results, even for similar electrochemical systems. Theoretical predictions suggest the capacitance-potential curve should exhibit bell- or camel-shaped curvature depending on the nature of the IL. Experimental observations have demonstrated several functional shapes such as U-shaped, bell-shaped, camel-shaped, and relatively featureless responses. Much of the work in this thesis starkly contrasts theoretical expectations by demonstrating capacitive behavior that is analogous to high temperature molten salts and dilute aqueous electrolytes with metallic and non-metallic electrode materials. However, our systematic studies of a model IL electrochemical system reveal that there are several ‘user-defined’ experimental variables (i.e. potential scan direction, data acquisition protocol, experimental technique, and potential range probed) which in some instances can significantly impact the resulting capacitance curvature. Some of these variables are often overlooked in the literature and our efforts are aimed at uniting the scientific community in this area to help better compare and understand results. An additional experimental variable of importance is the sorption of water into ILs, which is nearly impossible to prevent due to their hygroscopic nature. The presence of water is known to have a significant effect on the resulting mixtures’ bulk and interfacial properties. While the interaction between ILs and water can significantly vary depending on the nature of the IL, this thesis demonstrates that within small quantities (e.g., < 5000 ppm) of sorbed water there are only minor changes in spectroscopic and electrochemical responses. Collectively, the work outlined in this thesis helps the scientific community better understand electrochemical measurements in IL solvents by examining key analytical variables associated with capacitive measurements.
The fundamental electrochemical studies described in this thesis demonstrate that the solid-liquid interface for IL solvents is response to even subtle changes in surface chemistries. These governing interfacial properties have ramifications in myriad applications from energy storage to lubrication.
12
Ljungberg, Stefan. "High Frequency Oscillations at an Electric Double Layer." Thesis, KTH, Rymd- och plasmafysik, 1995. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91579.
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Farhat, Ali Y. "Vibrational analysis of composite double layer skeletal structures." Thesis, University of Surrey, 1992. http://epubs.surrey.ac.uk/624/.
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Pashaei, Mohammad Hadi. "Damping characteristics of mero-type double layer grids." Thesis, University of Surrey, 2004. http://epubs.surrey.ac.uk/731/.
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Jhon, Mark. "Diffuse double-layer interaction for nonspherical colloidal particles." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/114088.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2001.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 35-36).
The DLVO theory of colloids is used to consider the stability of clay colloid particles. An approach to colloid physics using classical electrostatic methods is presented. Specifically, the electrical double layer is examined using computational methods. To this end, the Poisson-Boltzman equation is solved numerically for geometries corresponding to interacting clay particles. The interaction energies of double layers is calculated for several particle configurations.
by Mark Jhon.
S.B.
16
Hou, Chia-Hung. "Electrical double layer formation in nanoporous carbon materials." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22698.
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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.Committee Chair: Sotira Yiacoumi; Committee Co-Chair: Costas Tsouris; Committee Member: Ching-Hua Huang; Committee Member: Sankar Nair; Committee Member: Spyros G. Pavlostathis.
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Krimpogiannis, Michail. "The Double Layer Potential Operator Through Functional Calculus." Licentiate thesis, Linköpings universitet, Matematik och tillämpad matematik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-81924.
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Layer potential operators associated to elliptic partial differential equations have been an object of investigation for more than a century, due to their contribution in the solution of boundary value problems through integral equations. In this Licentiate thesis we prove the boundedness of the double layer potential operator on the Hilbert space of square integrable functions on the boundary, associated to second order uniformly elliptic equations in divergence form in the upper half-space, with real, possibly non-symmetric, bounded measurable coefficients, that do not depend on the variable transversal to the boundary. This uses functional calculus of bisectorial operators and is done through a series of four steps. The first step consists of reformulating the second order partial differential equation as an equivalent first order vector-valued ordinary differential equation in the upper halfspace. This ordinary differential equation has a particularly simple form and it is here that the bisectorial operator corresponding to the original divergence form equation appears as an infinitesimal generator. Solving this ordinary differential through functional calculus comprises the second step. This is done with the help of the holomorphic semigroup associated to the restriction of the bisectorial operator to an appropriate spectral subspace; the restriction of the operator is a sectorial operator and the holomorphic semigroup is well-defined on the spectral subspace. The third step is the construction of the fundamental solution to the original divergence form equation. The behaviour of this fundamental solution is analogous to the behaviour of the fundamental solution to the classical Laplace equation and its conormal gradient of the adjoint fundamental solution is used as the kernel of the double layer potential operator. This third step is of a different nature than the others, insofar as it does not involve tools from functional calculus. In the last step Green’s formula for solutions of the divergence form partial differential equation is used to give a concrete integral representation of the solutions to the divergence form equation. Identifying this Green’s formula with the abstract formula derived by functional calculus yields the sought-after boundedness of the double layer potential operator, for coefficients of the particular form mentioned above.
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Zubieta, Bernal Luis Eduardo. "Characterization of double-layer capacitors for power electronics applications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28861.pdf.
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Sasvari, Gyorgy. "Charge generation and injection in double layer organic photoreceptors." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267529.
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Farsangi, Hossein E. "Topological optimisation of double layer grids using genetic algorithm." Thesis, University of Surrey, 2002. http://epubs.surrey.ac.uk/750/.
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Fellman, Batya A. (Batya Ayala). "Carbon-based electric double layer capacitors for water desalination." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61603.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 68-72).
In capacitive deionization (CDI), salt water is passed through two polarized electrodes, whereby salt is adsorbed onto the electrode surface and removed from the water stream. This approach has received renewed interest for water desalination due to the development of new high-surface area, carbon-based nanomaterials. However, there is limited understanding as to how electrode geometry, surface properties, and capacitance affect ion capture. In this work, we experimentally investigated various standard carbon-based electrode materials, including activated carbon and carbon cloths, as well as microfabricated silicon structures for CDI. Electrochemical characterization through cyclic voltammetry was used to determine the electrochemical properties of each material. The capacitance values of the carbon materials tested were 40 F/g for 2000 m2 /g carbon cloth, 32 F/g for 1000 m2 /g carbon cloth, and 25 F/g for activated carbon. In addition, we constructed two iterations of flow test channels to perform parametric studies on ion capture. The first flow cell utilized a commercial conductivity probe to measure salt concentration after charging the electrodes without flow. We showed that the ion capture on both the carbon cloth and activated carbon electrodes were proportional to the applied voltage, however two orders of magnitude smaller than what is expected from the electrode charge. We addressed a significant experimental limitation in the second flow cell by integrating conductivity sensors into the flow channel to measure effluent salt concentration during electrode charging. We found that the salt adsorption increased from 33.1 pmol/g in the first flow cell to 63.5 pmol/g in the redesigned flow for an applied potential of 1.2 V. Future directions will focus on controlling electrode geometry and chemistry to help elucidate transport mechanisms and provide insight into the design of optimal materials for capacitive deionization.
by Batya A. Fellman.
S.M.
22
Adams, Jonathan. "Collapse behaviour of double layer grid structures in steel." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/12341.
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Includes bibliographical references.Flat double layer grid (DLG) structures are efficient modular, structural systems which span in two or more directions and consequently develop their resistance in three dimensions. Although such structures offer many structural, constructional and aesthetic advantages over alternative planar structures, for use in unobstructed roofing applications, they have been observed to have a propensity for sudden collapse behaviour, as witnessed in the collapse of the Hartford Coliseum roof structure in 1978. Previous study of DLG behaviour has been undertaken through experimental and numerical analysis; these studies have confirmed the sudden collapse behaviour and sensitivity of such structures to geometric imperfections for selected cases but have not developed the full spectrum of DLG behaviour. A parameter study was therefore undertaken to identify desirable DLG pre-critical yielding behaviour and post-critical increases in grid structural resistance. The parameter study also served to identify and characterize grid plastic, failure and collapse behaviour for structures representative of those employed in practice; the Structural Eurocodes were used for this purpose.
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Чорноус, Анатолій Миколайович, Анатолий Николаевич Чорноус, Anatolii Mykolaiovych Chornous, Лариса Валентинівна Однодворець, Лариса Валентиновна Однодворец, Larysa Valentynivna Odnodvorets, Іван Юхимович Проценко, et al. "Magneto-deformation effect in double-layer nanodimentional film systems." Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20537.
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Sokmen, Gokce. "Molecular Dynamics Investigation Of Moire Patterns In Double-layer Graphene." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614751/index.pdf.
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Before Moire patterns are discovered in graphene, graphene was assumed to be found in only the rhombohedral form in nature. After transfer of graphene layer over another substrate
was achieved by Andre Geim and Konstantin Novoselov, studies on graphene gained momentum. Following this, moire paterns were observed by scanning tunelling microscopy (STM) and high resolution transmision electron microscopy (HR-TEM). However, stability of these structures are still unknown. In this thesis, for the first time in literature, molecular dynamics of double layer graphene based Moire patterns are investigated as a result of the
rotation of two graphene layers with LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) which has a GNU general public license. To model the two graphene layers,
hexagonal graphene layers are generated by home writen Octave code. Then, periodicity condition for the Moire patterns are derived in chapter 2 according to rotation of graphene layers around their central axis, perpendicular to the layers. Then these layers with different angles or temperature or size are simulated by LAMMPS. There are 4 kind of molecular dynamics simulations studied according to modeled flakes.
These are grouped under the name of &rsquoExperiment #&rsquo
according to the modeling structure. Experiment-1 simulates double layer hexagonal flakes of graphene at a temperature of 0.1K. Experiment-2 simulates periodic moire patterns under periodic boundary conditions and represents the infinitely large graphene layers at 10K. Experiment 3 is dierent version of the experiment 1 but at higher temperature (10K). Finally, experiment 4 is modeled to show the behaviour of the graphene flake on a growth or attached region. The atoms around the flakes are modeled as a rigid body and constructs some stress on the graphene flakes.
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Allison, Giles Daniel. "Compressibility study of single- and double-layer two-dimensional systems." Thesis, University of Exeter, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400928.
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Silva, Ricardo Manuel Fonseca Lopes. "Metal oxide/carbon nanotubes heterostructures for electric double layer capacitors." Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22962.
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Doutoramento em Ciência e Engenharia de MateriaisO presente estudo teve como objetivo principal a elaboração e caracterização de hétero-estruturas hibridas tridimensionais (3D) de nanotubos de carbono alinhados verticalmente e revestidos com óxido de manganês para aplicações em condensadores eletroquímicos como elétrodos livres de aditivos. Numa primeira fase, foram desenvolvidas metodologias para o crescimento de nanotubos de carbono puro e para nanotubos de carbono dopados com azoto, em substratos isoladores e metálicos, por deposição química em fase de vapor. Foi dada especial atenção ao crescimento direto de nanotubos de carbono alinhados verticalmente no substrato metálico (Inconel®600) e sua aplicação em elétrodos livres de aditivos à base de carbono. Posteriormente, foi desenvolvido um processo inovador para a deposição de óxido de manganês (Mn3O4) por deposição por camada atómica para o revestimento de nanoestruturas, como os nanotubos de carbono, para a elaboração de heteroestruturas. Estas foram devidamente caracterizadas como materiais para aplicações em eléctrodos. A eficiência electroquímica dos eléctrodos atinge um máximo para o nanocompósito de nanotubos de carbono puro/óxido de manganês revestidos com 600 ciclos por deposição por camada atómica e apresenta uma capacitância de 78.68 mF cm-2 a 5 mV s-1. Este resultado pode ser atribuído ao efeito cooperativo entre os componentes do nanocompósito e uma utilização eficaz dos materiais ativos. Provou-se que um material nanocompósito que englobe a capacitância da dupla camada elétrica, bem como a estrutura condutora dos nanotubos de carbono e a pseudocapacitância dos óxidos metálicos é de grande interesse devido ao seu mecanismo duplo de armazenamento de carga e as vantagens de cada mecanismo são exploradas nestes novos dipositivos híbridos. Este trabalho foi realizado na Universidade de Aveiro e na Universidade de Humboldt (Berlim), beneficiando das infraestruturas adequadas à execução do trabalho experimental de ambas as instituições e das competências complementares das equipas de investigação associadas. Devido à natureza multidisciplinar da área de investigação onde este doutoramento se insere, a colaboração com outras instituições internacionais valorizaram a discussão dos resultados obtidos e fundamentaram os novos materiais desenvolvidos
The purpose of this work was the elaboration and characterization of hybrid three-dimensional (3D) arrays of vertically aligned carbon nanotubes coated with manganese oxide heterostructures for application as binder-free electrodes in electrochemical capacitors. In the first stage, methodologies to grow pure and nitrogen doped vertically aligned carbon nanotubes arrays on nonmetallic and metallic substrates by thermal chemical vapor deposition have been developed. Particular attention was devoted to obtain vertically aligned carbon nanotubes arrays grown directly on metallic conductive substrates (Inconel®600) and their application in binderfree carbon-based electrodes. Subsequently, as one of the main points of this work, a novel manganese oxide (Mn3O4) atomic layer deposition process has been developed for coating nanostructures, such as carbon nanotubes, for the elaboration of heterostructures which were further used and characterized as electrodes materials. The electrochemical performance of the electrodes reaches a maximum for the pure carbon nanotubes/manganese oxide nanocomposite coated with 600 ALD cycles exhibiting a specific capacitance of 78.68 mF cm-2 at 5 mV s-1. This result could be attributed to the synergetic effect between the components in the nanocomposite and an effective utilization of the active materials. Therefore it was demonstrated that a nanocomposite material comprising electric double layer capacitance together with the conductive framework of the carbon nanotubes and pseudocapacitive metal oxides is of great interest due to its dual charge storage mechanism and the advantages of each mechanism are exploited in these new hybrid devices. This work was carried out at University of Aveiro and at Humboldt-Universität zu Berlin due to complementary avaivable expertises and equipments, and also benefits of several international collaborations due to the multidisciplinar nature of the research field.
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Yang, Kun-Lin. "Electrical double-layer formation at the nanoscale : molecular modeling and applications." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/20123.
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Marnham, Lachlan Leslie. "Bi-electron bound states in single- and double-layer graphene nanostructures." Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/23165.
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The prototypical exciton model of two interacting Dirac particles in graphene was analysed by Sabio et al, Phys. Rev. B 81, 045428 (2010), and it was found that in one of the electron-hole scattering channels the total kinetic energy vanishes, resulting in a singular behaviour. We show that this singularity can be removed by extending the quasiparticle dispersion, thus breaking the symmetry between upper and lower Dirac cones. The dynamics of an electron-electron pair are then mapped onto that of a single particle with negative mass and anisotropic dispersion. We show that the interplay between dispersion and repulsive interaction can result in the formation of bound, Cooper-pair-like, metastable states in double-layered hybrid structures. We analyse these states by calculating their binding energies, decay rates into the free- electron continuum and semiclassical trajectories. We also analyse the problem of bi-electron pairing with the inclusion of the two dominant many-body effects at zero temperature: screening of the Coulomb interaction by the Dirac sea, and reduction of the available phase space due to Pauli blocking of transitions into the states below the Fermi level. We show that these effects result in strong renormalization of the binding energy, but do not destroy the metastable states. Thus the binding energies are strongly dependent on the chemical potential owing to the combined effects of screening and Pauli blocking. Hence, the quasibound resonances can be tuned by electrostatic doping.
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Shiu, Huan-Ruei. "Effects of Electric Double Layer on Bypass Transition in Microchannel Flow." Université Joseph Fourier (Grenoble), 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-0401200516434500.
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Ogbomo, Sunny Minister. "Processing, structure property relationships in polymer layer double hydroxide multifunctional nanocomposites." Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc12174/.
Full textAbstract:
Dan Beaty (1937-2002) was a prolific composer, pianist, researcher, educator, and writer. His large compositional output included chamber works, choral works, songs, orchestral pieces, electronic music, and keyboard works. Beaty was well versed in traditional Western music as well as the more avant-garde and perplexing idioms of the twentieth century. Beaty's compositions reflect the many fascinating, if not always popular, musical trends of his time. His music encompasses styles from serial to jazz, shows compositional influences from Arnold Schoenberg to Indonesian music, and demonstrates thought-provoking and highly intellectual craftsmanship. This document explores several of Beaty's songs through a discussion of the composer's life and compositional process. Songs included in this document are Three Weeks Songs, October, November, A Sappho Lyric, Love Song, That Night When Joy Began, and War Lyrics. This document was written to accompany the author's DMA Lecture-Recital at the University of North Texas. Unfortunately, Beaty's vocal music was never published and is mostly unknown. One goal of the project was to initiate interest in Beaty's songs. Through this document, Lecture-Recital, and additional performances, considerable strides have been made to bring Beaty's songs to new audiences throughout the United States. In addition, the author has received permission from the Beaty family to publish Dan Beaty's songs.
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Singh, Gaurav. "Interface Driven Dynamics at Nanoscales:Polymer thin films and Electrical Double Layer." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/30261.
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The electrical double layer (EDL) is formed due to the accumulation of charge at the interface of a metal surface in contact with an electrolyte. The total charge in the EDL compensates the charge on the metal surface. As EDL is the layer that "connects" the electrode to the "bulk", all electrode mediated transport and redox reaction depends on the structure and dynamics of the ions in the EDL. Thus the ion dynamics in the EDL are critical to a wide range of physical and biological phenomena such as electrochemical reaction, flow in channels of nanofluidic devices, wetting of fluids; to biology, for example, folding and function of proteins, conformation change of DNA and ionic flow through cell membranes.
EDL polarization is the ion accumulation or depletion in the EDL due to the potential of the metal surface. The conventional method of measuring the EDL polarization is by monitoring the current flowing through the electrochemical system. Thus, the electrical characteristics of the EDL are inferred indirectly from the total current that is implicitly related to effects such as the impedance of the bulk solution. We have developed a sensitive optical interferometric technique to directly measure the polarization of the metal-electrolyte interface. The key advantage of our method is high sensitivity, and the measurement is specific only to the changes at the metal-electrolyte interface. The ion accumulation in the EDL of a simple salt like NaCl is studied as a function of the frequency and the amplitude of the applied potential on the metal electrode. The amplitude of modulation of the ions is linearly proportional to the amplitude of the applied AC potential. The linearity is observed up to high amplitude (up to 2V) and salt concentration as high as 0.5M. Furthermore, the local segmental dynamics of polyelectrolytes such as polystyrene sulfonate have been measured.
Next we extend this novel technique to study electrochemical redox reactions. The oxidation of the widely used redox ion [Fe(CN)6]4- is followed by measuring the response to an AC potential (amplitude ~100mV) as a function of a superimposed saw-tooth potential ramp, at a time period 106 fold slower and amplitude 5-10 fold larger than the AC potential. The sensitivity of the optical method is significantly better than the measurement of the AC current. For a redox process on the electrode, the change in the optical signal is over two orders of magnitude larger than the electrical signal. Using the optical technique, we can separate the kinetic events in redox processes: transport of charged species to the electrode surface and charge transfer across the electrode-electrolyte interface. Because we measure the local electrochemical process, the method can be used to probe redox reaction at multiple spots on the same electrode (i.e., combinatorial electrochemistry).Ph. D.
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Ogbomo, Sunny Minister D'Souza Nandika Anne. "Processing, structure property relationships in polymer layer double hydroxide multifunctional nanocomposites." [Denton, Tex.] : University of North Texas, 2009. http://digital.library.unt.edu/ark:/67531/metadc12174.
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Song, Zhuorui. "Electrokinetic Flow in a Nanochannel with an Overlapped Electrical Double Layer." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4271.
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Electrokinetic flows within an overlapped Electrical Double Layer (EDL), which are not well-understood, were theoretically investigated in this study with the particular attention on the consideration of hydronium ions in the EDL. Theoretical models for fully-developed steady pressure-driven flow for salt-free water or a binary salt solution in a slit-like nanochannel connecting to two reservoirs were developed. The transient flow in such a domain was also simulated from static state to the final steady state. In these models, the Poisson equation and the Nernst-Planck equation were solved either by analytic methods or by the finite element method. Surface adsorption-desorption equilibrium and water equilibrium were considered to account for the proton exchange at the surface and in the fluid. These models were the first to include those comprehensive processes that are uniquely important for overlapped EDL scenarios.
This study improves the understanding of electrokinetic flows within an overlapped EDL by demonstrating the profound impact of hydronium ions on the EDL structure. In the steady flow of potassium chloride solutions, hydronium ions are more enriched than potassium ions by up to 2~3 orders of magnitude, making the electrokinetic effects greatly depressed. The unequal enrichment effects of counterions were omitted in the traditional theory partially because the transient is extremely slow. The simulation results show that a concentration hump of hydronium ions initially forming at the channel entrance gradually expands over the whole channel in a way similar to the concentration plug flow moving downstream. The time required for the flow to reach the steady state could be as long as thousands of times the hydraulic retention time, dependent on the degree of the EDL overlap. This study improves the fundamental understanding for nanofluidic flows.
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Lim, Jong Il. "Transient finite element analysis of electric double layer using Nernst-Planck-Poisson equations with a modified stern layer." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4703.
Full textAbstract:
Finite element analysis of electric double layer capacitors using a transient
nonlinear Nernst-Planck-Poisson (NPP) model and Nernst-Planck-Poisson-modified
Stern layer (NPPMS) model are presented in 1D and 2D. The NPP model provided
unrealistic ion concentrations for high electrode surface potential. The NPPMS model
uses a modified Stern layer to account for finite ion size, resulting in realistic ion
concentrations even at high surface potential.
The finite element solution algorithm uses the Newton-Raphson method to solve
the nonlinear problem and the alpha family approximation for time integration to solve
the NPP and NPPMS models for transient cases. Cubic Hermite elements are used for
interfacing the modified Stern and diffuse layers in 1D while serendipity elements are
used for the same in 2D. Effects of the surface potential and bulk molarity on the electric potential and ion
concentrations are studied. The ability of the models to predict energy storage capacity is
investigated and the predicted solutions from the 1D NPP and NPPMS models are
compared for various cases. It is observed that NPPMS model provided realistic and
correct results for low and high values of surface potential.
Furthermore, the 1D NPPMS model is extended into 2D. The pore structure on
the electrode surface, the electrode surface area and its geometry are important factors in
determining the performance of the electric double layer capacitor. Thus 2D models
containing a porous electrode are modeled and analyzed for understanding of the
behavior of the electric double layer capacitor. The effect of pore radius and pore depth
on the predicted electric potential, ion concentrations, surface charge density, surface
energy density, and charging time are discussed using the 2D Nernst-Planck-Poissonmodified
Stern layer (NPPMS) model.
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Meige, Albert, and albert@meige net. "Numerical modeling of low-pressure plasmas: applications to electric double layers." The Australian National University. Research School of Physical Sciences and Engineering, 2006. http://thesis.anu.edu.au./public/adt-ANU20070111.002333.
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Inductive plasmas are simulated by using a one-dimensional particle-in-cell simulation including Monte Carlo collision techniques (pic/mcc). To model inductive heating, a non-uniform radio-frequency (rf) electric field, perpendicular to the electron motion is included into the classical particle-in-cell scheme. The inductive plasma pic simulation is used to confirm recent experimental results that electric double layers can form in current-free plasmas. These results differ from previous experimental or simulation systems where the double layers are driven by a current or by imposed potential differences. The formation of a super-sonic ion beam, resulting from the ions accelerated through the potential drop of the double layer and predicted by the pic simulation is confirmed with nonperturbative laser-induced fluorescence measurements of ion flow. It is shown that at low pressure, where the electron mean free path is of the order of, or greater than the system length, the electron energy distribution function (eedf) is close to Maxwellian, except for its tail which is depleted at energies higher than the plasma potential. Evidence supporting that this depletion is mostly due to the high-energy electrons escaping to the walls is given.
¶
A new hybrid simulation scheme (particle ions and Boltzmann/particle electrons), accounting for non-Maxwellian eedf and self-consistently simulating low-pressure high-density plasmas at low computational cost is proposed. Results obtained with the improved hybrid model are in much better agreement with the full pic simulation than the classical non self-consistent hybrid model. This model is used to simulate electronegative plasmas and to provide evidence supporting the fact that propagating double layers may spontaneously form in electronegative plasmas. It is shown that critical parameters of the simulation were very much aligned with critical parameters of the experiment.
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Adams, Barry D. O. "Models of fluid microstructure." Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308827.
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Bergantz, George W. "Double-diffusive boundary layer convection in a porous medium : implications for fractionation in magma chambers." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/26030.
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Thompson, David. "The local Coulombic Monte Carlo algorithm : applications to the electric double layer." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/32355.
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A reformulation of the Coulomb problem, using a local Coulomb algorithm
based on auxiliary fields, has been extended to slab and quasi-2D geometries.
It has been implemented using Metropolis Monte Carlo and Gaussian
charge interpolation functions. We have established the accuracy of the algorithm
by generating effective pair potentials. Using this implementation,
the Gouy-Chapman problem was numerically resolved for constant potential
slab boundaries. In the low coupling limit, we find excellent aggreement with
analytic solutions. In the high coupling regime, we find agreement with the
analytic theory in the limit of large wall separation. Using the contact value
theorem, we calculate the pressure experienced by like-charged equipotential
walls. The parameter space we consider pertains to many interesting biomaterials
ranging from monovalent biomembranes to spermidine DNA. The
numerical results show attractions mediated by counter-ions between the
like-charged equipotential slab boundaries. We also extend the implementation
to allow for inhomogeneous dielectric backgrounds. The effect of a thin
adsorbed layer of solvent is considered for an electrolyte system bounded
by isolated electrodes. We show that a reduction in the dielectric value of
this adsorbed layer results in a depletion of ions near the electrodes, even
though the electrodes carry zero total charge. The applications considered
show the versatility and accuracy of our implementation.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Wang, Hao. "Mechanistic studies of electrochemical double layer capacitors using solid-state NMR spectroscopy." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708302.
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Casses, Cécile J. (Cécile Jeanne Florence). "Aerodynamic benefits of boundary layer ingestion for the D8 double-bubble aircraft." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101494.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 133-135).
This thesis describes experimental assessments of the aerodynamic boundary layer ingestion (BLI) benefit of the D8 advanced civil aircraft design. Two independent methods were applied for 1:11 scale (4.1 m wingspan) powered aircraft model experiments in the NASA Langley 14x22-foot Subsonic Wind Tunnel. The metric used as a surrogate for fuel consumption was the input mechanical flow power, and the benefit was quantified by back-to-back comparison of non-BLI (podded) and BLI (integrated) configurations. The first method (indirect) was the estimate of mechanical flow power based on the measured electrical power to the propulsors, plus supporting experiments to characterize the efficiencies of the fans and the electric motors that drive them, at the MIT Gas Turbine Laboratory. The second method (direct) was the direct integration of flowfield measurements, from five-hole probe surveys at the inlet and exit of the propulsors, which provided flow angles, velocity components, and pressure coefficients. Data were taken at different wind tunnel speeds, and conditions to determine overall performance dependence on non-dimensional power and angle of attack. At the simulated cruise point, the first method gave a measured aerodynamic BLI benefit of 7.9% +/- 1.5% at 70 mph tunnel velocity, and 8.5% +/- 1.5% at 84 mph, and the second method gave a measured benefit of 8.1% +/- 3.3% at 70 mph, and 12.2% +/- 3.4% at 84 mph. For the aircraft models examined, the aerodynamic benefit was found to come primarily from a decrease in the propulsor jet velocity (increase in propulsive efficiency) and thus a decreased jet dissipation, with the contribution from decreased wake and airframe dissipation being roughly an order of magnitude smaller.
by Cécile J. Casses.
S.M.
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Lee, Won Hee. "Biomedical research application of a novel double-layer parallel-plate flow chamber." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/32817.
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Since integrity and functions of vascular endothelial cells are greatly affected by shear stress, a variety of in vitro systems to subject endothelial cells under precisely controlled fluid conditions has been developed. Complicated designs of the conventional flow devices, however, have impeded such implementation. In the present study, we designed and developed a novel parallel-plate flow chamber (PPFC). It consists of multiple layers of different materials to adjust the required geometries of the chamber and provide a wide span of biomedical research applications. Because the chamber stacks separate layers to constitute the flow channel, different pieces can be easily removed or replaced. Moreover, the multilayer design only requires 2D cutting, which is easier and faster to manufacture. It is also capable of accepting up to four glass slides facing each other so that the flow within the channel is exclusively formed by endothelial cells. Furthermore, it minimizes the pressure loss across the chamber while maximizing the effective area of endothelial cells up to 96 cm2. Results from mathematical analysis and dye injection experiments showed that a uniform magnitude of shear stress is applied throughout the entire surface of endothelial cells. In addition, the morphological changes and attenuated gene expression of pro-inflammatory mediators were observed in endothelial cells exposed to the physiologically relevant shear stress. These findings indicate that our newly designed PPFC can provide a better in vitro system for versatile applications of biomedical research.
The reperfusion of blood flow occurred in a number of conditions such as stroke and organ transplantation immensely augments tissue injury and can cause more severe damage than prolonged ischemia. The injuries caused by cessation and reperfusion of blood flow are closely related to the inflammatory reactions involving in endothelium-leukocyte cascade responding to a shear stress exerted by the flow. Shear stress is also known to play an important role in human chronic diseases including atherosclerosis, neurological disorders, and cancer metastasis. Therefore, it is important to investigate the transmission of mechanical stimuli such as shear stress to various complex endothelial cell signaling pathways which process as a whole is often referred as mechanotransduction. Shear stress-mediated signaling pathways have been known to trigger endothelial cell responses and contribute to the pathophysiology of human vascular diseases. The present study was designed to apply the novel PPFC to biomedical research, especially ischemia/reperfusion injury. The changes in mRNA and protein expression of inflammatory mediators in endothelial cells were analyzed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. RBE4 and HMEC-1 cells were either maintained in continuous laminar flow condition (Normal Flow) or subjected to 1 h of flow cessation followed by reperfusion of flow (Ischemia/Reperfusion) for 24 h. Ischemia/Reperfusion significantly up-regulated expression of inflammatory mediators, such as IL-6, MCP-1, ICAM-1, VCAM-1, and E-selectin, in microvascular endothelial cells. Furthermore, antioxidant pyrrolidine dithiocarbamate (PDTC) significantly attenuated ischemia/reperfusion-induced overexpression of pro-inflammatory mediators. These data indicates that our newly designed PPFC provide a better in vitro system for versatile applications of biomedical research.Master of Science
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Huang, Yun, and 黃雲. "4ACE:A Double-layer Double-channel Array Capacitance Equilibrium Router." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/07726353507992412941.
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碩士國立中央大學
電機工程學系
101
As the shrink of semiconductor process, the process variation effects performance of circuit much more seriously. It also causes high complexity and time-consuming on designing circuits. Therefore, layout automation is likely to play a key role in analog circuit design. The performance of many types of analog circuits, like ADC, DAC, etc., relies on the implementation of accurate capacitor ratio. Generally, capacitor mismatch can result from two sources of error: random mismatch and system mismatch. Random mismatch is due to process variation, while system mismatch is mainly caused by asymmetrical layout and processing gradient. These will decrease the accuracy and yield of circuits. To reduce these negative effects, several smaller unit capacitors will be parallel connected to replace the whole bigger capacitor. The parasitic effect between each unit capacitor will also be considered. In this thesis, a double-layer double-channel array capacitance equilibrium router is proposed for capacitor array block creation. By four steps: initial setting, capacitor placement, generation of interconnects, parasitic capacitor and compensation, the whole routing of circuit will be established. The router can be not only applied to the case of a pair of two target but also to the multiple target capacitors. By the conjunction of an array assignment using of spatial correlation feature, three cases are used as examples to demonstrate the assignment-routing flow. The first one is a case of two targets with a ratio of 1:1. The second one is a case of multiple targets with continuous ratio of 8:4:2:1:1. The last one is a case with non-integer ratio and compensation from parasitic effect, it also can provide an accurate ratio up to second digit after decimal point. After finishing layout creation, the wire parasitic capacitor will be extracted from Calibre. Finally, the accuracy of capacitor ratio and layout area will contrasted with a yield-aware ratio-keeping channel router which uses only vertical channel.
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Malaza, Nkosinathi. "Double-layer capacitance from the charged surface." Thesis, 2016. http://hdl.handle.net/10539/21665.
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A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science.
28 October 2016.Energy storage has become an important issue for society, there is a need for affordable and efficient devices that can store energy optimally. Supercapacitors are energy storage devices that can solve society’s energy storage problem. They can store the energy generated by renewable energy systems. In this work approaches will be studied that may be used to estimate capacitance of materials that can be used as the electrode of these devices. These materials must have high energy density, which will address one of the limitations of supercapacitors. To estimate the capacitance of the double layer, the double layer theory and ab initio numerical tools based on density functional theory (DFT) are used. The ab initio tools work with periodic systems, when charging the system one violates the periodicity of the system. This is overcome by using the effective screening medium method, which prevents energy divergent of the system. In this work different configurations of the water molecules are used to average the different orientations of water molecules in the electrolyte. The Pt(111) electrode is used, and electrolyte of sodium ion and water. In different configurations the sodium ion in the electrolyte is located at different positions. The capacitances calculated using two different approaches that we developed in this work are comparable to previously estimated capacitance. This is achieved by using minimal computational efforts. We obtained capacitance within that range. Double layer capacitance can be estimated to a good accuracy with the methods developed in this work. Though there are improvements that can be made on the methods that have been developed in this work to better estimate the double layer capacitance. And also more research has to be done in this field to come up with a theory that will accurately estimate capacitance. At the moment calculating the double layer capacitance is not trivial due to the lack of theory that describe the processes taking place at the surface of the electrode where the capacitance is calculated.
LG2017
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Bielo, Joseph Anthony. "Layer formation in semiconvection /." 2001. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:9999626.
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王炫富. "Fabrication and Properties of Electrric Double-Layer Capacitor." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/66387645822851549070.
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碩士國立臺灣科技大學
纖維及高分子工程系
89
Electric double-layer capacitors (EDLCs) are based on the charge stored at the interface between a highly surface-area activated carbon electrode and an organic electrolyte solution. High energy density has been received a considerable attention as compared to the conventional rechargeable chemical batteries. EDLCs with the highly rated charging and discharging have demonstrated an excellent rechargeability. There is a strong relationship between the breakdown voltage of the capacitor and the decomposition voltage of the electrolyte. It is useful to employ an organic electrolyte under high decomposition voltage to establish a capacitor with stable performance and high energy density. The experimental results indicate that the following orders of the potential window based on the Cyclic Voltammertry are BF4－＞ClO4－＞Br－. Low internal resistance has been verified to be an important factor of EDLCs in demonstrating the greater power capability in highly rated charging and discharging from the laboratory measurement. A 2.2V & 50F EDLC is developed and consisted of activated carbon electrodes, electrolytic solutions, separator, and collector electrodes.
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Lin, Pei-hua, and 林佩樺. "Study of corrosion resistance on double-layer coatings." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/w58vah.
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Chen, Yin-Chang, and 陳垠璋. "High-Power Matrerials for Electric Double layer Capacitors." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/63q3h2.
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碩士國立臺北科技大學
有機高分子研究所
102
In this study, the high surface area of activated meso-carbonemicro-beads and the carbon nanotube for use as modern composite supercapacitor electrodes. The activated mesocarbonemicrobeads will be porous in internal and external part for high performance electrode materials. The aMCMB electrode has a high energy storage capacity. This capacitance of electrode is 350 F g-1 under current is 0.02A g-1. The capacitance of electrode will decrease to 155 F g-1 under current is 0.6A g-1. The study was decreased transfer path of internal ion and raise particle touch for power output of supercapacitor and high rate charge-discharge ability. This capacitance of electrode is 372 F g-1 under current is 0.02A g-1. The capacitance of electrode will decrease to 153 F g-1 under current is 0.6A g-1. The CNTs was added to milling process for raising electron transport and inter-granular pore. This capacitance of electrode is 292 F g-1 under current is 0.02A g-1. The capacitance of electrode will decrease to 177 F g-1 under current is 0.6A g-1.
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Yu-JengSu and 蘇育正. "The Current-Free Double Layer in Helicon sources." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/41483655085392899218.
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碩士國立成功大學
太空天文與電漿科學研究所
99
Helicon sources can have mirror-like magnetic fields. These fields act like a magnetic nozzle that divides plasmas into the convergent side, the throat and the divergent side when plasmas flow along the field line. In addition, helicon sources, that have strong magnetic field, low gas pressure and high plasma density, provide the experimental setup for the current-free double layer. In Charles and Boswell’s experiments [Appl. Phy. Lett. 82, 9 (2003)], a current-free double layer in high-density helicon discharges is observed. They have observed abrupt decreases in density and temperature across the double layer. To explain the experimental results, the physics of a current-free double layer in plasmas that have two components of isothermal electrons with different temperatures has been studied [Ahedo and Sa ?nchez, Phy. Rev. Lett. 130, 135002 (2009)]. However, this isothermal model cannot account for the change of the electron temperature across the double layer as seen in the experiments. To explain the abrupt change of the electron temperature, electrons cannot be isothermal along the magnetic field lines. In this thesis, a model for the formation of a stationary current-free double layer in collisionless plasmas expanding in a magnetic nozzle is presented. The model consists of cold ions, isothermal hot electrons and fere-isothermal, i.e., almost isothermal, cold electrons and their dynamics. It can determine the position and the amplitude of double layer including the jump in cold electron temperature across the layer. The magnitude of the jump is consistent with the experimental observations. Plasmas are accelerated to the supersonic speed mainly by magnetic nozzle and the contribution from the double layer is small. The effects of ion charge Z on the flow speed at the nozzle throat and at the exit are also discussed.
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蔡涵琦. "Analysis on Double layer tensioned web slot coating." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/85387848908675563701.
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楊博鈞. "Double Layer Ultra-Broadband Finite State Markov Channel." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/35803137432768487308.
Full textAbstract:
碩士國立臺灣海洋大學
通訊與導航工程系
96
The objective of this study is to find an effective algorithm to build and model the broadband fading channel. For broadband or even ultra-broadband fading channels in the wireless communication system, we will not be able to describe them by a conventional channel model algorithm. There are block fading effects both in time and in frequency when the channel is considered to be a broadband fading channel. The uniform signal over time and frequency in the ultra-broadband channel does not achieve good channel utilization; we shall adopt bandwidth scaling to offer a suitable bandwidth range by combining the upper and lower channel capacity bounds to decide how large should be the bandwidth. Applying bandwidth scaling scheme twice for a very large bandwidth on ultra-broadband fading channels, we then be able to describe each bandwidth scaled broadband fading channel by a finite-state Markov channel (FSMC) model. We have discussed the transition probability and steady state probability of each state. By partition the range of the received signal-to-noise ratio (SNR) into a finite number of intervals, the finite-state Markov channel model can be applied to construct broadband Rayleigh fading channels as well as others broadband fading channels