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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Varför lämnar kvinnor chefsrollen?

Hägglund, Christine January 2011 (has links)
Uppsatsen syftade till att 1) öka förståelsen varför kvinnor lämnat rollen som chef och 2) om det fanns skillnader mot män som lämnat rollen som chef. Resultaten visade att kvinnor i lämnade pga. "push"-orsaker, dvs. att man ej var nöjd, medan männen lämnade pga. "pull"-orsaker, positivt motiverande faktorer. Studien visade också att de kvinnor som stannade kvar i rollen som chef gjorde det pga. "pull"-orsaker. Arbetet baserades på en intervjustudie av 16 personer under våren 2010. Slutsatsen var att kvinnor oftare trycktes ut ur chefsrollen genom missnöje, medan männen drogs ut ur chefsrollen genom att lockas vidare. / The thesis was aimed to 1) increase the understanding of why women left the role as a manager and 2) if there was any differences between them and the men who left the role as a manager. The results showed that women left because of push-factors, that they weren’t satisfied, whereas men left because of pull-factors, positively motivating factors. The study also showed that women who stayed in the role as a manger did so because of pull-factors. The study was based on interviews of 16 persons during spring 2010. The conclusion was that women more often were pushed out of the manager role because of discontent, whereas men were pulled out because of attraction to something else.
12

Push-Pull Tests to Support In Situ Chemical Oxidation System Design

Mathai, Ashley January 2011 (has links)
The problems associated with the contamination of groundwater environments by non-aqueous phase liquids (NAPLs) such as chlorinated solvents, gasoline and manufacturing gas plant (MGP) residuals, including their distribution and persistence, are well accepted. The treatment of groundwater by in situ chemical oxidation (ISCO) relies on the oxidation potential of chemical reagents to destroy harmful organic compounds. The interaction of these oxidants with target and non-target compounds in the subsurface will help determine effectiveness and efficiency of an ISCO treatment system. Push-pull tests (PPTs) have the utility to estimate key properties in situ and allow for sampling a larger volume of aquifer to yield more representative estimates as compared to conventional bench-scale tests. The scale and cost-effectiveness of a PPT make it an ideal tool to collect valuable information on subsurface system behaviour so that uncertainties can be minimized. The use of PPTs to provide insight into treatment expectations or to support the design of an ISCO system requires a suitable interpretation tool. A multi-species numerical model (‘PPT-ISCO’) in a radial coordinate system was developed to simulate a PPT with the injection of a conservative tracer and oxidant (persulfate or permanganate) into the saturated zone of a porous medium environment. The pore space may contain variable amounts of immobile, multicomponent, residual NAPL. The aquifer material contains a natural organic matter (NOM) fraction and/or other oxidizable aquifer material (OAM) species. The model is capable of simulating mass transport for an arbitrary number of conservative and reactive tracers and NAPL constituents subjected to chemical reactions. The ability of PPTs to capture the in situ natural oxidant interaction (NOI) was tested with PPTISCO. Breakthrough curve (BTC) data collected from permanganate and persulfate PPTs conducted in the field were compared to simulated BTCs by assigning the same field operational parameters to the model and applying NOI kinetic information obtained from batch tests. These tests confirmed the usability of the model and PPTs to obtain the NOI kinetics from PPT BTCs. The sensitivity of PPT BTCs to variations in the field operating and NOI parameters were investigated. The results of varying the field operating parameters indicated that the oxidant BTCs could be scaled to match varying injection and extraction flow rates. Variations in NOI parameters revealed that the permanganate BTC is primarily controlled by the permanganate fast reaction rate coefficient and the quantity of OAM present in the aquifer. The spatial profiles of OAM across the test zone revealed that the majority of the OAM consumption is from the fast fraction and occurs in the vicinity of the well where the permanganate concentration is greatest. An estimate of the permanganate fast reaction rate coefficient can be obtained from a permanganate PPT BTC by employing the model to simulate the PPT with the operational parameters (used in the field) and literature estimates of the remaining NOI parameters. Calibration between the simulated and observed BTCs can be undertaken to adjust the permanganate fast reaction rate coefficient to fit the permanganate PPT BTC. Persulfate NOI sensitivity investigations revealed that persulfate PPT BTCs can be characterized by a concentration plateau at early times as a result of the increased ionic strength in the area around the injection well. The ionic strength is primarily controlled by the injected persulfate concentration, and as persulfate degrades into sulphate and acid, the ionic strength is enhanced. Graphical analysis of the BTC revealed that an underestimated value of the persulfate degradation rate coefficient can be obtained from the PPT BTC. A more representative estimate of the persulfate degradation rate coefficient can be achieved after fitting the field BTC to the simulated results, applying the underestimated value as a starting point. PPTs investigating ISCO treatability have the ability to provide insight into the effect of the NOI on the oxidation of target compounds, site-specific oxidant dosage requirements and NAPL treatment expectations. NAPL component BTCs from treatability PPTs are primarily controlled by the mass in the fast region, and the fast region mass transfer rate coefficient. Oxidation estimates extracted from NAPL component BTCs were shown to accurately approximate the mass of each NAPL component oxidized when compared to model calculations. The mass of NAPL oxidized for each of the components yields a site-specific oxidant dosage. This estimate exceeds what is prescribed by the stoichiometry between permanganate and the contaminant of concern due to the effect of the NOI. The utility of PPTs to study and quantify the interaction between injected oxidants and the aquifer material has been demonstrated with PPT-ISCO. In addition, PPT-ISCO has revealed that treatability PPTs can be tailored to investigate the dosage requirements and treatment expectations of residual NAPLs. Results from this effort will be used to support ongoing field research exploring the use of PPTs to assist in understanding the competing subsurface processes affecting ISCO applications.
13

Extended-CONWIP-Kanban System: Control and Performance Analysis

Boonlertvanich, Karin 14 April 2005 (has links)
A major challenge in designing and controlling flow lines is to achieve high customer service level while stay lean. Just-In-Time (JIT) manufacturing approach has triggered various 'pull production system', such as CONWIP or Kanban controls, which emphasizes on response to demand rather than forecasts. We identified and documented the anatomy of various pull type control policies. Based on the analysis, we designed a new class of control policy called Extended CONWIP Kanban control (ECK). We conducted comprehensive simulation comparison studies. Simulation results showed that the new control policy can achieve higher service levels with lower inventories than other policies including hybrid ones. We developed a state space comparison methodology to compare various policies with that of optimum solution. Our analysis reveals that our ECK policy provides the most adjustment flexibility toward the optimum. We also proposed a parameter design procedure and an adaptive parameter adjusting system. A case study verifies the advantages and utilities of the ECK policy. Beside the cost savings, another major advantage of the ECK policy is its robustness. That is, the total cost of the ECK policy is less sensitive to demand or system variations.
14

Nonlinear Static and Dynamic Characteristics of Electrostatic Micro-actuators

Chen, Chao-Jung 08 July 2004 (has links)
This dissertation performs a simulation investigation into the nonlinear static and dynamic characteristics of electrostatically driven shaped micro-actuators in micro-electro-mechanical systems (MEMS). The model proposed in the current nonlinear pull-in deflection study considers various boundary conditions for the electrostatically actuated structures, e.g. the cantilever beam and the fixed-fixed beam, and takes account of the electrical field fringing effect and the axial residual stress. Initially, the Adomian decomposition method is employed to evaluate the response of a micro-actuator incorporating a rectangular micro-beam and a flat electrode by obtaining the closed-form solution of the corresponding nonlinear equation. Since no iteration is required in solving the nonlinear deformation, this decomposition method is one of the most efficient methods available for evaluating the unstable pull-in behavior of an electrostatically driven micro-actuator. The present study implements both small and large deflection assumptions when simulating the response of the micro-actuator in order to explore the possible effects of the two models on the accuracy of the simulation results. The shaped micro-beam with a curved electrode micro-actuator is further assessed using the differential quadrature method (DQM) to examine the influence of the nonlinear pull-in effect. This dissertation also studies the contact force and the pull-in deflection of shaped micro-tweezers. The DQM is employed to solve the nonlinear interaction between the curved electrostatic field force and the corresponding deflection of the shaped cantilever actuators. The numerical results confirm the ability of the DQM to treat this form of nonlinear actuator problem accurately, efficiently and systematically. To evaluate the dynamic characteristics of the electrostatic micro-actuator, the DQM is applied to solve the natural frequencies of a fixed-fixed shaped beam vibrating around its statically deflected position under electrostatic loading. The proposed model not only takes account of the nonlinear interaction between the curved electrostatic field force and the restoring force of the shaped micro-beam, but also considers mid-plane stretching, axial residual stress, and electrical field fringing effects. It is shown that an excellent agreement exists between the simulation results obtained using the proposed model and those measured experimentally. This study also investigates the micro-beam and electrode shape effect on the natural frequencies of the actuator system. The analytical results indicate that variations in the shape of the micro-beam or of the electrode not only influence the electrostatic field distribution, but also significantly alter the dynamic characteristics of the micro-actuator. Furthermore, the results demonstrate that the shaped micro-beam with a curved electrode micro-actuator increases the working voltage range of the micro-actuator by a factor of approximately six times compared to that of a micro-actuator incorporating a rectangular micro-beam and a flat electrode. A continuing trend nowadays is the integration of micro-electro-mechanical devices with electronic circuitry to fabricate MEMS devices such as micro-switches, optical micro-mirrors, etc. It is known that when an electrical voltage is applied to these devices, the micro-actuators will undergo a residual vibration before reaching their permanent position. Hence, this dissertation investigates the residual vibration phenomenon of cantilever beam type micro-switches with air squeeze-film damping between the micro-beam and substrate. The present simulations of various shaped micro-actuators provide an understanding of the nonlinear static and dynamic behaviors of these devices and as such provide designers with the information required to properly and accurately control the device operating range during the design stage.
15

A Study of Migration Behavior of San-Ying Tribe in Taipei County

Chin, Han-yu 29 August 2005 (has links)
Since 1960, the aboriginal of Taiwan have gradually moved to urban areas, living with a kind of gathering or spreading style. So far, urban aboriginals become the majority among other kinds of aboriginals. Facing illegally gathered clusters of buildings over national lands, villages and riversides occupied by urban aboriginals, researcher have been trying to find out why those aboriginals moved into urban areas? How did those urban aboriginals select a suitable settlement for them? And what about current standard of living and conditions they could manage and reach? In order to find out the migration behaviour of urban aboriginals in this research, researcher use qualitative research such as interview, interpretive methods. From the various results of this research, it can be seen that some aboriginals of Amis are living in a closed environment located at San-Ying tribe in Taipei County. They are not only facing shortage goods, unstable working condition, but also having little educational training. They moved from original area to urban areas caused by economic reason. Different workplace caused urban aboriginal live, when they can¡¦t fine a job, they¡¦ll try to find somewhere to live. San-Ying tribe was chosen as the destination for new settlement because of friends¡¦ notice and a consideration of the position. For them, this new settlement has already been the second original area and almost of their colleagues and friends do make their living in the urban areas as it is easy to get a job there. What San-Ying tribe residents want now is to have a stable income and a home for them to survive in the society. Researcher suppose these problems lying on cooperation and collaborations between government and civil organizations to settlement solutions, employment solutions and educational solutions.
16

Nanoscale electrostatic actuators in liquid electrolytes: analysis and experiment

Kim, Doyoung 12 April 2006 (has links)
The objective of this dissertation is to analytically model a parallel plate electrostatic actuator operating in a liquid electrolyte and experimentally verify the analysis. The model assumes the system remains in thermodynamic equilibrium during actuation, which enables the ion mass balance equations and Guass’ Law to be combined into the Poisson-Boltzmann equation. The governing equations also include the linear momentum equation including the following forces: the electric force, the osmotic force, the spring force, the viscous damping force, and the van der Waals force. Equations are also derived for the energy stored in the actuator. The analytical results emphasize the stored energy at mechanical equilibrium and the voltage versus electrode separation behavior including the instability. The analytical results predict that the system may not be a good actuator because the displacement has a very limited stable range, although the actuator would be suitable for bistable applications. The experiment consisted of a fixed flat gold electrode and a movable gold electrode consisting of a gold sphere several micrometers in diameter mounted on the end of an Atomic Force Microscope (AFM) cantilever, which serves as the spring. The electrodes were separated by approximately 100nm of 1mM NaCl aqueous solution. The analytical results were not verified by the experiment. Relative to the analysis, the experiments did not show distinct critical points, and the experiments showed less electrode separation for a given applied electric potential. The experiments did show points at which the electrode separation versus electric potential rapidly changed slope, which may be instability points. It is suggested that this phenomenon may be due to coalesced gas bubbles on hydrophobic regions of the electrode surfaces, which are not included in the model. Although clean gold surfaces are hydrophilic, gold surfaces may become hydrophobic due to impurities.
17

Attentional pull: the off-task pull of emotions and on-task pull of goals

Merlo, Kelsey L. 08 June 2015 (has links)
The allocation of attentional resources to a focal task can influence performance on that task, but within-person changes in allocation policy is typically understudied. This study investigates the off-task pull of emotional experiences and the competing on-task pull of goals. Emotional experience was manipulated using an ostracizing event and goals were experimenter-assigned. The results did not support the off-task pull of emotional experiences or the on-task pull of goals. Implications and directions for future research are discussed.
18

Produktionsstyrning av cylinderbricka : För Atlas Copco, Tierp.

Pettersson, Erik January 2014 (has links)
The component workshop at Atlas Copco inTierp intends to reduce the costs inorder to increase their competitiveness.This thesis examines how the productionmanagement around cylinder washersshould be managed in a way that meetsthe customer needs. The customer to thecylinder washer is Atlas Copcos assemblydepartment in Tierp. The purpose of this thesis is to providean alternative way of managing theproduction. A chapter of theory is addedto give the reader an insight ofdifferent types of production managementsystems as well as the underlyingknowledge needed to get a better readingexperience. An introduction of kanbancan in theory help Atlas Copco in thedirection they strive. It should beclear how the purpose of this thesisaffects the cost for the componentworkshop and also how it relates to thecurrent production. The currentsituation is described by explaining howthey use SAP, EOQ and an analysis of how EOQ determine the batch size. Thencalculations on a kanban system is madeand also an idea of how the logistics ofthe kanban system should be managed. From this thesis, conclusions how animplementation of a kanbansystem wouldaffect the component workshop can beshown. By using the overcapacity withthe machine to increase the frequency ofchangeovers leads to reduced batch size.The reduced batch starts a chain of goodconsequences like reduction ofinventory. Changing from a productionmanaged by EOQ to a kanbanflow makes theproduction planning more transparent andrequire less resources. In a complexprocess there’s a lot of factors thatdetermine how the production is managed,a kanbansystem reduce the complexitywith an easy signal when the productionshould start. / Komponentverkstaden på Atlas Copco i Tierp har för avsikt att minska de kostnadsdrivandefaktorerna för att öka sin konkurrenskraft. Den här rapporten undersöker hur cylinderbrickorska produktionsstyras på ett sätt som tillgodoser cylinderbrickans kund (monteringen)samtidigt som lagernivåer inte ska vara för stora. Målet med rapporten är att ge komponentverkstaden i Tierp ett förslag om ett alternativttillvägagångssätt för att styra produktionen. Ett kapitel med teori finns för att ge läsaren eninblick i olika typer av produktionsledningssystem samt omkringliggande kunskaper sombehövs för att få en bättre läsupplevelse. Ett införande av kanbansystem anses i teorin kunnahjälpa Atlas Copco i den riktning de önskar. Det ska tydligt framgå hur alternativet påverkarde kostnadsdrivande faktorer samt hur det förhåller sig till nuvarande produktionsstyrning.Nuläget beskrivs genom att förklara hur de använder SAP och EOQ samt en analys av attutforma partistorlekar med hjälp av EOQ. Därefter räknas ett kanbansystem fram och en idéom hur logistiken kring kanbansystemet ska skötas. Från den här rapporten kan slutsatser dras om hur en implementering av ett kanbansystemskulle påverka komponentverkstaden. Genom att använda den överblivna tiden som finns vidmaskinen till att ställa om produktionen oftare, minskar partistorlekarna vilket startar enkedjereaktion av bra konsekvenser som till exempel mindre lager. Att gå ifrån en EOQ styrdproduktionsstyrning till ett kanbanflöde gör att produktionsplaneringen blir merlättöverskådlig och mindre resurskrävande. I en komplex process där en oöverskådlig mängdfaktorer styr hur produktionen ska planeras minskas komplexiteten med hjälp av ettkanbanstyrt flöde som ger signal om produktion efter förbrukning.
19

Push-Pull Tests to Support In Situ Chemical Oxidation System Design

Mathai, Ashley January 2011 (has links)
The problems associated with the contamination of groundwater environments by non-aqueous phase liquids (NAPLs) such as chlorinated solvents, gasoline and manufacturing gas plant (MGP) residuals, including their distribution and persistence, are well accepted. The treatment of groundwater by in situ chemical oxidation (ISCO) relies on the oxidation potential of chemical reagents to destroy harmful organic compounds. The interaction of these oxidants with target and non-target compounds in the subsurface will help determine effectiveness and efficiency of an ISCO treatment system. Push-pull tests (PPTs) have the utility to estimate key properties in situ and allow for sampling a larger volume of aquifer to yield more representative estimates as compared to conventional bench-scale tests. The scale and cost-effectiveness of a PPT make it an ideal tool to collect valuable information on subsurface system behaviour so that uncertainties can be minimized. The use of PPTs to provide insight into treatment expectations or to support the design of an ISCO system requires a suitable interpretation tool. A multi-species numerical model (‘PPT-ISCO’) in a radial coordinate system was developed to simulate a PPT with the injection of a conservative tracer and oxidant (persulfate or permanganate) into the saturated zone of a porous medium environment. The pore space may contain variable amounts of immobile, multicomponent, residual NAPL. The aquifer material contains a natural organic matter (NOM) fraction and/or other oxidizable aquifer material (OAM) species. The model is capable of simulating mass transport for an arbitrary number of conservative and reactive tracers and NAPL constituents subjected to chemical reactions. The ability of PPTs to capture the in situ natural oxidant interaction (NOI) was tested with PPTISCO. Breakthrough curve (BTC) data collected from permanganate and persulfate PPTs conducted in the field were compared to simulated BTCs by assigning the same field operational parameters to the model and applying NOI kinetic information obtained from batch tests. These tests confirmed the usability of the model and PPTs to obtain the NOI kinetics from PPT BTCs. The sensitivity of PPT BTCs to variations in the field operating and NOI parameters were investigated. The results of varying the field operating parameters indicated that the oxidant BTCs could be scaled to match varying injection and extraction flow rates. Variations in NOI parameters revealed that the permanganate BTC is primarily controlled by the permanganate fast reaction rate coefficient and the quantity of OAM present in the aquifer. The spatial profiles of OAM across the test zone revealed that the majority of the OAM consumption is from the fast fraction and occurs in the vicinity of the well where the permanganate concentration is greatest. An estimate of the permanganate fast reaction rate coefficient can be obtained from a permanganate PPT BTC by employing the model to simulate the PPT with the operational parameters (used in the field) and literature estimates of the remaining NOI parameters. Calibration between the simulated and observed BTCs can be undertaken to adjust the permanganate fast reaction rate coefficient to fit the permanganate PPT BTC. Persulfate NOI sensitivity investigations revealed that persulfate PPT BTCs can be characterized by a concentration plateau at early times as a result of the increased ionic strength in the area around the injection well. The ionic strength is primarily controlled by the injected persulfate concentration, and as persulfate degrades into sulphate and acid, the ionic strength is enhanced. Graphical analysis of the BTC revealed that an underestimated value of the persulfate degradation rate coefficient can be obtained from the PPT BTC. A more representative estimate of the persulfate degradation rate coefficient can be achieved after fitting the field BTC to the simulated results, applying the underestimated value as a starting point. PPTs investigating ISCO treatability have the ability to provide insight into the effect of the NOI on the oxidation of target compounds, site-specific oxidant dosage requirements and NAPL treatment expectations. NAPL component BTCs from treatability PPTs are primarily controlled by the mass in the fast region, and the fast region mass transfer rate coefficient. Oxidation estimates extracted from NAPL component BTCs were shown to accurately approximate the mass of each NAPL component oxidized when compared to model calculations. The mass of NAPL oxidized for each of the components yields a site-specific oxidant dosage. This estimate exceeds what is prescribed by the stoichiometry between permanganate and the contaminant of concern due to the effect of the NOI. The utility of PPTs to study and quantify the interaction between injected oxidants and the aquifer material has been demonstrated with PPT-ISCO. In addition, PPT-ISCO has revealed that treatability PPTs can be tailored to investigate the dosage requirements and treatment expectations of residual NAPLs. Results from this effort will be used to support ongoing field research exploring the use of PPTs to assist in understanding the competing subsurface processes affecting ISCO applications.
20

Conception de nouveaux matériaux moléculaires pour l'élaboration de cellules photovoltaïques hybrides de type p à colorant

Farre, Yoann 21 October 2016 (has links)
Les travaux présentés dans cette thèse ont pour objectif de contribuer au développement des cellules photovoltaïques hybrides employant un colorant organique pour sensibiliser un semi-conducteur de type p (NiO). Ces travaux de recherche ont porté sur la synthèse, l’étude théorique par des calculs DFT, les caractérisations physico-chimiques (absorption, émission, électrochimie et spectro-électrochimie) et les mesures photovoltaïques de sensibilisateurs innovants. Des modulations de structures sur la base du motif dicétopyrrolopyrrole (DPP) ont permis d’étudier l’influence d’une entité électrodonneuse ainsi que le rôle crucial de différents groupes électroaccepteurs sur la durée de vie de l’état à charges séparées (NiO+/colorant-) et sur les performances photovoltaïques. L’intensification et l’élargissement des bandes d’absorption de nouveaux colorants fondés sur cette même famille de sensibilisateur (DPP) ont accru considérablement la densité de courant. L’étude de nouveaux matériaux organiques de type donneur-accepteur et l’application d’une stratégie employant deux groupes accepteurs successifs de forces croissantes ont été réalisées. Cette partie a mis en lumière la nécessité de développer de nouveaux groupes électrodonneurs et fonctions d’ancrage mieux adaptées aux p-DSSC. Cette problématique a été abordée par la conception de colorants de type pérylène-monoimide dont la structure varie uniquement par la nature de la fonction d’ancrage. Ces colorants ont été testés dans des cellules sur des cathodes poreuses de NiO et de CuGaO2 et ont pu montrer que la fonction hydroxyquinoline conduit à des performances photovoltaïques supérieures à la fonction acide carboxylique. / This thesis aims at contributing to the development of dye sensitized solar cells (DSSC) that are based on an organic dye and a p-type semi-conductor as photocathode such as NiO. In this context, these studies focus on the synthesis, the theoretical study by DFT calculations, the physicochemical characterizations (absorption and emission spectra, electrochemistry and spectroelectrochemistry) and photovoltaic characterizations of these innovative sensitizers. Structure modulations on a diketopyrrolopyrrole dye (DPP) investigate the influence of an electron-donating group and the crucial role of different electron-withdrawing groups on the lifetime of the charge separation state (NiO+/dye-) and on the photovoltaic performances. Enhancement and broadening of the absorption bands with new sensitizers have enabled to considerably increase the photocurrent density and to reach among the highest values reported in the literature with the best dyes. Synthesis of new organic push-pull dyes and the application of a strategy using two successive electron-withdrawing groups of growing strengths have been realized. This part highlights the necessity to develop new electron-donating and anchoring groups for p-type dye sensitized solar cells. This point issue was investigated in the final chapter of this thesis by the design of new perylene monoimide sensitizers, whose structures only differ by the nature of the anchoring group (CO2H, acac, PO3H2, hydroxyquinoline…). These dyes were investigated in DSSCs with porous cathode made of NiO or CuGaO2. It was shown that the binding group hydroxyquinoline gives higher photovoltaic performances than the classical carboxylic acid group.

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