Analytical prediction of labyrinth-seal-flow-induced arotor excitation forces

An analytical method to calculate the rotor excitation forces arising from labyrinth seals is presented. The objective is to model the gas flow through the seal clearance passages and cavities when the rotor is positioned eccentricly relative to the stator center. The seal flow model used in the analysis yields solutions which validate the experimentally observed influence of seal parameters on seal forces reported in the literature. The analytically predicted seal pressure distributions and forces were compared with published experimental results

Thermal kinetics of ion irradiation hardening in selected alloys for the Canadian Gen. IV nuclear reactor concept

Canada is designing supercritical water fission reactors (SCWR) to increase the thermal efficiency of nuclear power generation from ~34% to ~48%. The temperature and pressure of a supercritical water reactor core is very high compared to a CANDU reactor. This thesis examines irradiation hardening and thermal recovery of two candidate alloys, AISI 310 and Inconel 800H, for the Canadian SCWR. Samples of both alloys are mechanically ground and polished, then irradiated using 8.0 MeV Fe ions. The use of ion irradiation safely and quickly simulates neutron damage. The change in the hardness of the samples is then studied during a series of thermal anneals at temperatures ranging from 400° to 600° C. This study found virtually all irradiation-induced hardening had recovered within 100 minutes of exposure to these temperatures

Neuroanatomical And Neurochemical Organization Of Compartments In The Basal Ganglia Of The Rat

The structural and neurochemical organization of the basal ganglia of the rat was investigated with highly sensitive modern anterograde and retrograde tracing methods in combination with immunocytochemical identification of intrinsic neuronal substances with the optical and laser-confocal microscope to address the fundamental organization of these centers as an integrated system.;Based on the present results and other evidence, a functional model of the basal ganglia is proposed: The corticostriatal inputs activate a large population of striatal neurons. Among these, appropriate neurons are \u27selected\u27 within each functional domain by the dopaminergic, cholinergic, and GABAergic recurrent collateral inputs. The same corticostriatal input simultaneously activates type II spiny projection neurons from each functional domain, which inhibit a population of parvalbumin-containing GABAergic pallidal neurons. These pallidal neurons disinhibit a number of pallidostriatal neurons via axon collaterals. The appropriate population of pallidostriatal neurons is \u27selected\u27, probably by subthalamic afferents. The selected GABAergic pallidostriatal neurons then inhibit striatal functional domains, thereby \u27selecting\u27 only the appropriate functional unit. The selected population of striatal projection neurons then inhibits a number of GABAergic neurons of the basal ganglia output centers. Again, appropriate neurons are \u27selected\u27 by subthalamic afferents and recurrent collaterals. The selected GABAergic neurons then disinhibit the thalamus, pedunculopontine nucleus and/or the superior colliculus via axon collaterals. The information sent to the thalamus is used to program memory, whereas that directed to the pedunculopontine nucleus or the superior colliculus participates in motor execution. The dorsolateral striatal circuit operates during sensory-guided and self-paced movements, while the medial and ventral striatal circuit operates during memory-guided movements. Striatal interneurons, globus pallidus neurons, subthalamic nuclear neurons and dopaminergic neurons play a role in \u27selecting\u27 the appropriate sets of neurons at different levels. (Abstract shortened by UMI.

Influence Of Developer Sentiment And Stack Overflow Developers On Open Source Project Success: An Empirical Examination

The collaborative effort of software developers around the world produces Open Source Software (OSS) products, and most importantly, the source code of the software product is shared publicly. A recent survey of 1300 IT professionals by Black Duck Software showed that the percentage of companies using open source software grew from 42% to 78% between 2010 and 2015. There has been a significant increase in the formation of self-organizing virtual teams to produce open source software products and services. The current literature does not address the factors affecting the success of open source projects through the lens of self-organizing virtual teams and the sentiment among the developers and the sentiment among software developers. This phenomenon suggests a need to understand how successful project teams are created in a virtual collaborative environment. This research investigates how successful virtual teams are formed through the influence of an online developer community. The focus of this research is to assess how the online developer community, Stack Overflow (SO), influences the success of open source projects. More precisely, the study empirically tests the influence of the SO community on successful Github (GH) projects. The investigation also empirically examines how the ties among the software developers in the SO community initiate the self-creation of OSS project teams. The research also explores the perception of the developers about open source projects. Furthermore, the study probes the impact of OSS artifacts, namely “feature” and “patch” requests, on open source projects. The findings indicate that the perception of the developers in the SO community, prior ties among the developers in the community, and the artifact type of the project are the factors that influence the success of OSS projects. The research discusses the implications of the outcomes concerning self-organizing open source project teams

Why Empirical Studies of the Groupthink Model have Failed

The theory of groupthink has been highly beneficial in the study of how groups make decisions. It has permeated almost every field containing decision making groups. Despite its popularity, there has been a surprising lack of empirical support for the model. It is the aim of this paper to suggest a possible explanation for the current state of groupthink research. First the groupthink model is described briefly, followed by a look at several selected empirical and case studies of groupthink. A potential reason for the dearth of empirical is then proposed along with a suggestion for future groupthink research

Modeling Lithium-Ion Rechargeable Battery System

Battery-powered electronics devices have become well-verse in the current society. The rapid growth of the use of portable devices such as portable computers, personal data assistants, cellular phones and Hybrid Electrical Vehicles (HEVs) creates a strong claim for fast deployment of the battery technologies at an extraordinary rate. The design of a battery-power-driven device requires many battery-management features, including charge control, battery-capacity monitoring, remaining run-time information and charge-cycle counting. Portable energy storage devices such as batteries are needed when the need in mobility increase. Compare to other batteries, lithium battery has the highest power density, energy density and the longest cycle life. Lithium batteries have been highly used as a choice of rechargeable battery for portable consumer electronic tools. The main objective is to develop a battery management system model to ensure that optimum use is made of the energy inside the battery powering the portable device and that the risk of damage to the battery is prevented. This is achieved by simulating the battery’s charging and discharging process. Modeling a battery management system by studying the charging and discharging characteristic curve of the lithium-ion battery is being proposed in this research project. This battery management model will construct a charging and discharging curves which will show different percentage of charges and discharge rate when it is connected to various loads. This model can further study on testing the other parameters effect towards the performance of the battery using the existed constructed model

Towards Strengthening Technology Culture amongst MSEs: Evidence from a Field Study in Bangalore, India

The Micro and Small Enterprises (MSEs) contribute a great deal in income and employment generation in India. The MSEs competitiveness is often marred by the level of technology they adopt. Realizing the vital role played by these units in the economy, previous Government of India provided tacit support to encourage them in adopting new technology. This shifted away from the hitherto approach of viewing the technology as the mere generators of employment. While state intervention could harness their growth, the forms of intervention require a careful examination of technology culture amongst MSEs. To explore firms’ tendencies in this regard, a field level investigation was conducted covering a few auto component manufacturing firms based in Bangalore. Availability of skilled labor and ease of finance were found to be the major constraints to technology acquisition and upgradation. While there are a plethora of government sponsored schemes implemented through other formal credit market channels, there are obstacles faced by the units in accessing those credit facilities. Based on the findings, the paper outlines some state interventions that may enhance technology acquisition and upgradation processes amongst the MSE

Master of Science

thesisCreating very small structures in the resist exceeding di raction limit is becoming a bottle-neck in lithography especially for nanoscale features. A novel optical lithography technique that has the ability to overcome the di raction barrier is Absorbance Modulation Interferometric-Lithography (AMIL). Feasibility of this technique is experimentally veri ed. In this approach of absorbance modulation, a standing wave at wavelength ?2 (633nm) is overlaid with a uniform beam from a light-emitting diode with a center wavelength at ?1 (310nm). Both beams illuminate a photoresist lm overcoated with a photochromic layer. This photochromic layer localizes the transmitted light at ?1 to subwavelength spatial dimensions. The subwavelength lines are spaced by a di raction-limited grating period. In order to generate dense lines, the sample is mounted on a single-axis high precision scanning stage that will enable multiple exposures