11 |
Enhancing the design-manufacturing interface in nanoscale technologiesBanerjee, Shayak 08 October 2010 (has links)
Semiconductor scaling has been largely driven by advancements in lithographic technologies. However, the lack of a viable next generation lithography solution since the 180nm node has driven the industry to printing sub-wavelength features. This has led to rising manufacturing costs and diminishing chip yield. In traditional methodologies, manufacturing and design are relatively insulated, with a layout being the only means of communicating design intent to the foundry. In this dissertation, we describe several techniques which utilize electrical information to improve properties of manufactured structures. We aim to show that a bi-directional flow of information between design and manufacturing is key to increasing chip yield. In particular, we target the mask data preparation flow of lithography. We develop an electrically-driven optical proximity correction (ED-OPC) tool that performs electrical matching as opposed to geometric matching in order to achieve lower post-lithography delay error. We then demonstrate how to harness ED-OPC to compensate electrical variability arising from non-lithographic sources as well. We then describe a technique to manufacture circuits with less timing violations across the process window by using design-aware shape tolerances generated from timing information. Finally, we observe that local wiring has low impact on design properties and use this information to modify target wire shapes themselves in order to improve their manufacturability in the presence of process variations. / text
|
12 |
Broadband Impedance Matching of Antenna Radiatorsiyer, vishwanath 29 September 2010 (has links)
"In the design of any antenna radiator, single or multi-element, a significant amount of time and resources is spent on impedance matching. There are broadly two approaches to impedance matching; the first is the distributed impedance matching approach which leads to modifying the antenna geometry itself by identifying appropriate degrees of freedom within the structure. The second option is the lumped element approach to impedance matching. In this approach instead of modifying the antenna geometry a passive network attempts to equalize the impedance mismatch between the source and the antenna load. This thesis introduces a new technique of impedance matching using lumped circuits (passive, lossless) for electrically small (short) non-resonant dipole/monopole antennas. A closed form upper-bound on the achievable transducer gain (and therefore the reflection coefficient) is derived starting with the Bode-Fano criterion. A 5 element equalizer is proposed which can equalize all dipole/monopole like antennas. Simulation and experimental results confirm our hypothesis. The second contribution of this thesis is in the design of broadband, small size, modular arrays (2, 4, 8 or 16 elements) using the distributed approach to impedance matching. The design of arrays comprising a small number of elements cannot follow the infinite array design paradigm. Instead, the central idea is to find a single optimized radiator (unit cell) which if used to build the 2x1, 4x1, 2x2 arrays, etc. (up to a 4x4 array) will provide at least the 2:1 bandwidth with a VSWR of 2:1 and stable directive gain (not greater than 3 dB variation) in each configuration. Simulation and experimental results for a solution to the 2x1, 4x1 and 2x2 array configurations is presented. "
|
13 |
Etude théorique et expérimentale de µ-OLEDs en régime impulsionnel à très haute densité de courant / Experimental and theoretical study of μ-OLEDs in pulsed regime under high current densitiesZeng, Lei 20 October 2016 (has links)
Ce travail de thèse porte sur l’estimation de la possibilité d’atteindre le seuil laser dans un matériau organique par pompage électrique. Dans le but ultime de réaliser le laser organique à pompage électrique, un prérequis est d’injecter une haute densité de courant dans un dispositif électroluminescent fonctionnel. Dans un premier temps, le comportement de l’OLED soumise à haute densité de courant est simulé et un modèle d’estimation de seuil laser basé sur la matrice de transfert est proposé. Ces études théoriques indiquent l’existence d’une densité de population maximale d’excitons radiatives au début d’injection de courant et estime la nécessité de 8.7×1016 cm-3 au seuil laser. Ensuite, la caractéristique résolue en temps des μ-OLED à base d’Alq3 : DCM excitées par des impulsions électriques de courtes durées (< 100 ns) et à faible taux de répétition (10 Hz) sont étudiées à l’aide d’un système de microscope confocal calibré. Les caractéristiques de l’OLED sont en bon accord avec les simulations théoriques. Une densité de courant de 3.6 kA/cm² et un pic de luminance de 8.4×106 cd/m² ont été obtenus en injectant des impulsions de 30 ns. Le pic de luminance correspond à une densité de population de 3.6×1017 cm-3, soit supérieure au plus petit seuil laser en littérature. Il est donc possible de réaliser le laser dans cette fenêtre de temps de quelques nanosecondes. / This thesis focus on the estimation of the possibility to achieve the laser threshold in an organic material with electrical pumping. As the ultimate goal is to demonstrate an electrically pumped organic laser, attaining high current density in a working electroluminescent device is pre-required. At first, the response of OLED at high current injection condition is simulated with a theoretical model. And the laser threshold estimation is performed by transfer matrix method. These theoretical studies show that a peak of emissive exciton (singlet) population density should exist at pulse onset, while a population density of 8.7×1016 cm-3 is necessary for lasing. Next, the time-resolved characteristics of μ-OLED based on Alq3 : DCM excited by short (< 100 ns) electrical pulses with low repetition rate (10 Hz) have been studied on the calibrated confocal microscope. The response of μ-OLED is in good agreement with the theoretical simulations. A current density of 3.6 kA/cm² and a luminance peak of 8.4×106 cd/m² have been achieved with 30-ns pulses. This luminance peak corresponds to singlet population density of 3.6×1017 cm-3, which is higher than the smallest laser threshold in literature. We suggest that it is possible to achieve laser effect in the time window of several nanoseconds at pulse onset.
|
14 |
Auger Electron Spectroscopy of Controlled Delaminating Materials on Aluminium SurfacesHögblad, Jon January 2008 (has links)
<p>This master thesis in physics mainly treats Auger spectroscopy of interfaces that has been adhesively bond together with so called controlled delaminating materials (CDM). CDM is a new technology which involves adhesives with the distinctive property that they by the appliance of electricity can be released from a substrate. The reason for using Auger spectroscopy was that it gives a surface sensitive view of the chemical composition of the samples examined and this was believed to give hints of the mechanisms behind loss of adhesion. The samples were so called laminates which is an aluminium foil, CDM adhesive, aluminium foil structure. As expected Auger spectroscopy produced some promising results, especially regarding the breakdown of a certain anion contained into the examined CDM adhesive. This awoke new questions regarding how this anion was decomposed and the idea that it could be due to hydrolysis took form. The by far most important result within this work is that the anion breaks down. This could lead to the formation of hydrofluoric acid if this breakdown in fact is due to hydrolysis and the hydrofluoric acid could then react with the aluminium causing loss of adhesion. This could be the good starting point of a continuing work on CDM.</p>
|
15 |
Auger Electron Spectroscopy of Controlled Delaminating Materials on Aluminium SurfacesHögblad, Jon January 2008 (has links)
This master thesis in physics mainly treats Auger spectroscopy of interfaces that has been adhesively bond together with so called controlled delaminating materials (CDM). CDM is a new technology which involves adhesives with the distinctive property that they by the appliance of electricity can be released from a substrate. The reason for using Auger spectroscopy was that it gives a surface sensitive view of the chemical composition of the samples examined and this was believed to give hints of the mechanisms behind loss of adhesion. The samples were so called laminates which is an aluminium foil, CDM adhesive, aluminium foil structure. As expected Auger spectroscopy produced some promising results, especially regarding the breakdown of a certain anion contained into the examined CDM adhesive. This awoke new questions regarding how this anion was decomposed and the idea that it could be due to hydrolysis took form. The by far most important result within this work is that the anion breaks down. This could lead to the formation of hydrofluoric acid if this breakdown in fact is due to hydrolysis and the hydrofluoric acid could then react with the aluminium causing loss of adhesion. This could be the good starting point of a continuing work on CDM.
|
16 |
Equilibrium and stability of magnetohydrodynamic flows in annular channelsKhalzov, Ivan 25 January 2008
Magnetohydrodynamic (MHD) flows in annular channels are of great current interest due to experimental search for the so-called magnetorotational instability (MRI) which is important for astrophysical applications (accretion disk physics, magnetic dynamo effect). <p>The main point of MRI experiments is to study the stability of liquid metal rotating in an external magnetic field. Two different types of fluid rotation are proposed: Taylor-Couette flow between rotating coaxial cylinders and electrically driven flow in transverse magnetic field. The implementation of MRI experiments and explanation of experimental results requires a theoretical study of the equilibrium and the stability of MHD flow in an annular channel. This is one of the main tasks of present thesis.<p>For study of equilibrium Taylor-Couette and electrically driven flows, a numerical code is developed which is based on the finite difference scheme with Jacobi iterations. The structure of flows is calculated for different parameters of the experiment. Effect of the inertia on the rotation profiles is investigated in detail. The approximate analytical expressions are obtained for radial profiles of rotation that can be used for optimization of the experimental device for MRI investigation. Equilibrium Taylor-Couette and electrically driven flows are compared from the perspective of experimental studies of MRI.<p>The spectral stability of electrically driven flow is studied by solving the eigen-value problem. This study is performed in the frames of both ideal and dissipative MHD models. It is shown that electrically driven flow can be destabilized through the mechanism of MRI if fluid velocity exceeds some instability threshold, which is determined by non-axisymmetric modes. The obtained results are compared with available experimental data.<p>A general variational method is developed for the stability study of MHD flows of ideal compressible fluids. It is shown that the linearized dynamics of such fluids has an infinite set of invariants. A necessary and sufficient stability criterion can be obtained after inclusion of one or several such invariants in analysis. An analytical example is presented to confirm the fruitfulness of the developed method.
|
17 |
Equilibrium and stability of magnetohydrodynamic flows in annular channelsKhalzov, Ivan 25 January 2008 (has links)
Magnetohydrodynamic (MHD) flows in annular channels are of great current interest due to experimental search for the so-called magnetorotational instability (MRI) which is important for astrophysical applications (accretion disk physics, magnetic dynamo effect). <p>The main point of MRI experiments is to study the stability of liquid metal rotating in an external magnetic field. Two different types of fluid rotation are proposed: Taylor-Couette flow between rotating coaxial cylinders and electrically driven flow in transverse magnetic field. The implementation of MRI experiments and explanation of experimental results requires a theoretical study of the equilibrium and the stability of MHD flow in an annular channel. This is one of the main tasks of present thesis.<p>For study of equilibrium Taylor-Couette and electrically driven flows, a numerical code is developed which is based on the finite difference scheme with Jacobi iterations. The structure of flows is calculated for different parameters of the experiment. Effect of the inertia on the rotation profiles is investigated in detail. The approximate analytical expressions are obtained for radial profiles of rotation that can be used for optimization of the experimental device for MRI investigation. Equilibrium Taylor-Couette and electrically driven flows are compared from the perspective of experimental studies of MRI.<p>The spectral stability of electrically driven flow is studied by solving the eigen-value problem. This study is performed in the frames of both ideal and dissipative MHD models. It is shown that electrically driven flow can be destabilized through the mechanism of MRI if fluid velocity exceeds some instability threshold, which is determined by non-axisymmetric modes. The obtained results are compared with available experimental data.<p>A general variational method is developed for the stability study of MHD flows of ideal compressible fluids. It is shown that the linearized dynamics of such fluids has an infinite set of invariants. A necessary and sufficient stability criterion can be obtained after inclusion of one or several such invariants in analysis. An analytical example is presented to confirm the fruitfulness of the developed method.
|
18 |
Studies of the electro-optical properties of liquid-crystal Fresnel lens based on cholesteric blue phaseWang, Yu-yin 02 August 2010 (has links)
In this study, a liquid crystal Fresnel lens based on the cholesteric blue phase liquid crystals is proposed. Blue phases are liquid-crystalline phases that appear in a very small temperature range between a cholesteric phase and an isotropic phase. There are three types of blue phases; BP¢¹,BP¢º and BP¢». The BP¢¹ and BP¢º are characterized by a spatially periodic director field with lattice constants comparable to the wavelength of visible light. Because of the structural symmetry, blue phases are optically isotropic.
In this study, the electro-optical properties of the BP¢º under different applied voltages are investigated. The results reveal that the Bragg reflection of the BPII has a red shift by increasing the applied voltage and a phase transition from BPII to cholesteric phase occurs at the high voltage regime (>100V). Based on the results, an electrically controlled blue phase Fresnel lens with polarization independence and high diffraction efficiency is demonstrated.
|
19 |
Living with colorectal cancer : naturalistic assessment of daily lifeRooney, Stephanie Buell 13 December 2010 (has links)
Ecological momentary assessment provides a unique way of studying quality of life factors of colorectal cancer patients. It has yet to be used to study the behavioral expression of distress or depression by colorectal cancer patients. The current study utilized the Electronically Activated Recorder (EAR) technology to capture the daily activities and conversations of forty-eight adults with colorectal cancer. The study had two purposes: 1) to test the feasibility of the EAR with colorectal cancer patients; 2) to examine separate (self-report and behavioral) indicators of physical functioning, coping, and social support for their relationship to depression.
Study participants wore the EAR, a portable digital recorder, for two consecutive days as the EAR recorded 30 seconds every 12.5 minutes. The EAR digital data were transcribed and analyzed for behavioral and linguistic indicators of physical functioning, coping, and social support. The acoustic data were analyzed using the standardized coding system Social Environment Coding of Sound Inventory (SECSI) and the Linguistic Inquiry and Word Count (LIWC2007) computer program.
The results provided preliminary evidence that the EAR operated as a feasible and non-disruptive tool for gathering naturalistic data about colorectal patients’ lives. The EAR data revealed information about both the colorectal patients’ internal emotional world as well as their external world which was characterized by solitary acts of daily living. Study subjects were more likely to accept and receive tangible support from others than directly discuss their cancer with others. Analysis of language found that personal disclosure to others was associated with coping through emotional support while causation words (e.g., because, effect, hence) were significantly related with self-report cognitive scales. Furthermore, the study found that first-person singular pronouns were associated not only with depression, but with appraisal of social support. Lastly, a predictive model was tested to see whether self-reported tangible and emotional support and behavioral coding of emotional support each contributed uniquely to the prediction of depression. Only self-reported tangible support was found to significantly predict depression. / text
|
20 |
Electrically Conductive Metal Nanowire Polymer NanocompositesLuo, Xiaoxiong Unknown Date
No description available.
|
Page generated in 0.0504 seconds