• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 65
  • 53
  • 14
  • 12
  • 9
  • 8
  • 4
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 184
  • 39
  • 32
  • 30
  • 25
  • 25
  • 24
  • 24
  • 22
  • 19
  • 16
  • 16
  • 15
  • 15
  • 15
  • 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.
71

Upplevelser av rektorsrollen : en studie av tre rektorer

Karlsson, Marcus January 2009 (has links)
<p> </p><p>This report is about the principle and his / her role at the school it’s also about how the principle understands the role, its expectations and the demands connected. The facts are based on deep detailed interviews with three different principles. The theoretical approach is coming from “hermeneutiken” and “Gadamers” ideas regarding how an individual is creating the world and the surroundings to act within. The ambition was to evaluate the three different principles opinions and feelings in the light of the above approach plus describe possible areas of difficulties because of too different demands and expectations. The interviews indicate both similarities and totally different opinions. It will be very interesting to connect basic business management and impacts from both the formal and also the informal organisation to the interview results and findings.</p><p> </p>
72

Upplevelser av rektorsrollen : en studie av tre rektorer

Karlsson, Marcus January 2009 (has links)
This report is about the principle and his / her role at the school it’s also about how the principle understands the role, its expectations and the demands connected. The facts are based on deep detailed interviews with three different principles. The theoretical approach is coming from “hermeneutiken” and “Gadamers” ideas regarding how an individual is creating the world and the surroundings to act within. The ambition was to evaluate the three different principles opinions and feelings in the light of the above approach plus describe possible areas of difficulties because of too different demands and expectations. The interviews indicate both similarities and totally different opinions. It will be very interesting to connect basic business management and impacts from both the formal and also the informal organisation to the interview results and findings.
73

SETUP TIME OPTIMIZATION

Andersson, Joakim, Bertilsson, Jimmy January 2012 (has links)
Sammanfattning   Emhart Glass AB är världsledande företag inom glasflasktillverkning. De konstruerar automatiserade maskiner som formar glasflaskor. I Sverige finns det två fabriker, en i Örebro och en i Sundsvall. I Örebro tillverkar man främst reservdelar och nya delar till maskinerna medan man i Sundsvall monterar ihop maskinerna. Det finns totalt 15 olika fabriker och kontor över världen med huvudkontor i schweiziska Cham.      Eftersom Emhart Glass Örebro har för långa ställtider på några av deras maskiner ska det undersökas hur omställningsarbetet går till i dagsläget och hur omställningsarbetet skiljer sig åt mellan operatörerna. Det ska även undersökas om det finns några möjligheter till förbättringar samt om det i dagsläget finns något standardiserat sätt som operatören borde följa. Ett dokument som beskriver hur ställarbetet ska gå till kommer även att tas fram.   Ett utmärkt verktyg för att förkorta ställtiderna i en produktion är SMED-Metoden. Filosofin bakom SMED är att man ska analysera och skilja på inre och yttre ställ. Med inre och yttre ställ menas de som endast kan utföras då maskinen är avstängd resp. de som kan utföras när maskinen är i drift.   För att standardisera omställningsarbetet så att samtliga operatörer jobbar på liknande sätt så krävs det att man tar fram en dokumentation över hur arbetet ska gå till. Därför har checklistor tagits fram till operatören. "Checklista - Omställning.xls" är en checklista med syftet att man ska kunna bocka för vilka delar i förberedelserna man gjort inför kommande ställ. Den har tagits fram för att man enkelt ska kunna hålla reda på vilka delar man gjort om man blivit tvungen att jobba med maskinen emellan förberedelserna eller om man slutar sitt skift och lämnar delar av arbetet till nästa operatör.   Om samtliga av dessa förbättringar införs kan man förvänta sig en ställtidsreducering på 20,5% vilket motsvarar ca 35min per ställ. Ignorerar man inkörningstiderna och endast kollar på riggningstider kan man se en förbättring på 36,4 %. / Abstract   Emhart Glass Ltd is a world leader in glass bottle manufacturing. They design automated machines that shape glass bottles. In Sweden there are two factories, one in Örebro and one in Sundsvall. In Örebro they manufacture primarily spare parts and new parts for the machines while they in Sundsvall assemble the machines. There are a total of 15 factories and offices around the world with the headquarter located in Swiss Cham.Since Emhart Glass Örebro has long setup times on some of their machines. This is why we want to identify the current setup process and how the setup process differs between operators. We will also look at whether there are any opportunities for improvement to be made and if they have a standardized way to work. A document that describes how to setup work should be done will also be developed.An excellent tool to shorten the setup time in a production is the SMED method. The philosophy behind SMED is that you should analyze and separate the inner and outer activities. Inner and outer activities mean those activities which can only be performed when the machine is turned off, respectively those activities that can be performed when the machine is in operation. In order to standardize the adjustment process so that all operators are working in a similar way it's required that you make a documentation about how the work should be done. Therefore, checklists been developed to the operator. "Checklista - Omställning.xls" is a checklist with the purpose to be able to check which parts of the preparations they have made before the next setup work. It has been designed to be easy to keep track of what parts you have done if you had to work with the machine between the trial or if you quit your shift and leaving parts of the work to the next operator. If all of these improvements are implemented, we expect a set-up time reduction of 20.5% which corresponds to about 35min per set-up. By ignoring the running time and only check on the setup times, one can see an improvement of 36.4%.
74

AVIX VIDEOANALYS FÖR REDUCERING AV STÄLLTIDER / AVIX VIDEOANALYSIS FOR SETUP TIME REDUCTION

Franzén, Mikael, Jonsson, Pierre January 2011 (has links)
Emhart Glass AB är en världsledande internationell tillverkare av automatiska glasformningsmaskiner för framställning av olika glasprodukter bl.a glasflaskor och glasburkar. Emhart Glass AB har i dagsläget 14 kontor i 10 olika länder och är sedan 1998 ägt av Bucher Industries. Den svenska divisionen är uppdelade i två enheter. I Örebro tillverkas maskindelar, reservdelar och strategiska komponenter. Komponenterna skickas sedan vidare till Sundsvall för del- och slutmontage. På Emhart Glass Sweden i Örebro har det uppmärksammats att långa ställtider förekommer vid vissa maskingrupper. Uppdraget består av att med hjälp av videoinspelningar och mjukvaran AviX analysera omställningsarbetet och komma med förbättringsförslag. Målet är att med hjälp av AviX reducera ställtiden och utvärdera huruvida AviX är ett lämpligt verktyg för det här sortens undersökning. Utvalda förbättringar ska sedan genomföras och utvärderas. Arbetet har utförts enligt SMED-metoden som är en välbeprövad metod för ställtidsreducering. Med hjälp av videoinspelningar kunde en grundlig nulägesanalys genomföras där alla ingående aktiviteter kunde identifieras. AviX användes sedan för att separera aktiviteterna och arrangera dem i den följd som gav den effektivaste omställningen. Den framtagna metoden standardiserades sedan genom rutinframtagning. Att standardisera utförandet ansågs vara ett krav för det kommande förbättringsarbetet då det är viktigt att samtliga operatörer utför omställningsarbetet på samma sätt. Förbättringsarbetet resulterade i ett antal förslag att förenkla och effektivisera omställningsarbetet för operatörerna. Utvalda förbättringar har genomförts och implementerats i omställningsarbetet. Förbättringarna tillsammans med de framtagna rutinerna uppskattas ge en ställtidsreducering mellan 20-30 %. Förbättringarna har gett operatörerna bättre förutsättningar att genomföra omställningarna snabbt och effektivt. Genom att genomföra fler förbättringsförslag kan ställtiden reduceras ytterligare. Emhart Glass rekommenderas att följa upp och föra statistik över omställningsarbetet och ställtiderna för att se hur dessa påverkats och arbeta med ständiga förbättringar för att effektivisera arbetet ytterligare. Vi anser att AviX är ett effektivt verktyg för att arbeta med ställtidsreducering och kan även användas i effektiviseringsarbetet för att leta fram och eliminera slöserier. Nyckelord: SMED, AviX, omställningsarbete, videoanalys, ställtidsreducering. / Emhart Glass AB is a leading international manufacturer of automatic glass forming machines for the manufacture of various glass products, among other things, glass bottles and jars. Emhart Glass AB has currently 14 offices in 10 countries and is since 1998 owned by Bucher Industries. The Swedish division is divided into two units. In Örebro manufactured machine parts, spare parts and strategic components. The components are then sent to Sundsvall for interim and final assembly. At Emhart Glass Sweden in Örebro has been discovered that long setup times occur at certain machine groups. The mission consists of using video recordings and the software AviX to analyze the changeover process and suggest improvements. The goal is that by using AviX reduce set-up time and evaluate whether AviX is a suitable tool for this sort of investigation. Featured improvements are then implemented and evaluated. The work has been performed according to the SMED-method which is a proven method for set-up time reduction. With the help of video recordings was a thorough situation analysis conducted in which all activities could be identified. AviX was then used to separate activities and arrange them in the order that gave the most efficient changeover. The developed method was standardized with new routines. To standardize the performance was considered to be a requirement for future improvement efforts because it is important that all operators perform changeovers in the same way. Improvement work resulted in a number of proposals to simplify and streamline the changeover process for operators. Featured improvements are in place and implemented in the changeover. These improvements along with the resulting procedures are estimated to provide a set-up time reduction between 20-30%. The improvements have given operators a better basis to carry out reorganization quickly and efficiently. By conducting more improvement suggestions set-up time is reduced even further. Emhart Glass is recommended to conduct a follow up and keep statistics on changeovers and set-up times to see how these are affected and making continuous improvements to improve efficiency further. We believe that AviX is an effective tool for working with set-up time reduction and can also be used to improve efficiency to seek out and eliminate waste.
75

Some Problems in One-Operator Scheduling

Baki, Mohammed Fazle January 1999 (has links)
A flexible workforce or a versatile machine is employed to perform various types of operations. Often these resources are associated with setups. Whenever a worker or machine switches from processing one type of operation to another a setup time may be required although several operations of a same type can be processed in succession after a single setup. The presence of setups gives rise to the problem of choosing batch sizes that are neither too large nor too small. In the last one and a half decade, many researchers have addressed the problem of scheduling with batching. A majority of articles assumes that there is only one type of scarce resource, which is typically machine. Often there can be two scarce resources such as a worker and a machine or a machine and a tool. We propose a resource constrained scheduling model with a single operator and two or more machines. Whenever the operator changes machine, a setup time is required that may be sequence dependent or sequence independent. We consider the two cases of an open shop and a flow shop. In the open shop case, the order in which a job visits the machines is unrestricted. In the flow shop case, every job must visit the machines in the same order. We consider various scheduling objectives. For variable number of machines, many cases are intractable. We discuss some dominance properties that narrow down the search for an optimal schedule. We present a dynamic programming approach which solves a large number of cases. The running time of the dynamic program is polynomial for a fixed number of machines. For the case of two machines, we show that the dominance properties have a nice interpretation. We develop some algorithms and justify their use by establishing running times, comparing the running times with those of the existing algorithms, and testing the performance of the algorithms.
76

Does democracy have an effect on a nation's ability to achieve economic growth? : An empirical analysis of the relationship between deomcracy and growth

Kalingas Ruin, Maria January 2012 (has links)
The rate of economic growth varies extensively between different countries. The underlying reasons to the differences are dissimilarities in productivity and efficiency, which in turn seem to be affected by factors such as the institutional setup, the rate of economic freedom, the level of human and social capital, corruption and interpersonal trust.This thesis investigates the relationship between economic growth and the level of democracy in developing countries, as a well-functioning democracy to a large extent corresponds to an inclusive institutional setup. The empirical investigation is conducted with a regression analysis. Using secondary data from acknowledged organizations and institutes, possible factors that may affect average GDP per capita growth are examined. The estimations included in the regression are democracy, foreign direct investment, education expectancy, initial GDP per capita, population growth rate, life expectancy, corruption, Rule of Law and Internet users. The empirical result shows that democracy has no significant effect on growth, but suggests that the effect might be indirect since factors such as good maintenance of Rule of Law, low level of corruption, high interpersonal trust, a high level of economic freedom and enhanced property rights are empirically proven to correspond to well functioning institutions. This result is in accordance with previous research and seems to support the idea that a good institutional setup is important for economic growth.
77

Modeling and Analysis of the Batch Production Scheduling Problem for Perishable Products with Setup Times

Charnprasitphon, Aphiwat 16 January 2007 (has links)
The focuses of this dissertation are problems of batch production scheduling problems for perishable products with setup times, with the main applications in answering production planning problems faced by manufacturers of perishable products, such as beers, vaccines and yoghurts. The benefits of effective production plans can help companies reduce their total costs substantially to gain the competitive advantages without reduction of the service level in a globalize economy. We develop concepts and methodologies that are applied in two fundamental problems: (i) the batch production scheduling problem for perishable products with sequence-independent setup times (BPP-SI) and (ii) the batch production scheduling problem for perishable products with sequence-dependent setup times (BPP-SD). The problem is that given a set of forecast demand for perishables products to be produced by a set of parallel machines in the single stage of batch production, with each product having fixed shelf-life times and each machine requiring setup times before producing a batch of product, find the master production schedule which minimizes total cost over a specified time horizon. We present the new models for both problems by formulating them as a Mixed Integer Program (MIP) on the discrete time. Computational studies in BPP-SI and BPP-SD for industrial problems are presented. In order to efficiently solve the large BPP-SI problems in practice, we develop the five efficient heuristics. The extensive computational results show that the developed heuristics can obtain the good solution for the very large problem size and require very short amount of computational time.
78

Mechanical Properties Identification Of Viscoelastic / Hyperelastic Materials Based On Experimental Data

Tabakci, Alican 01 September 2010 (has links) (PDF)
Mechanical simulation of viscoelastic materials and assigning a viscoelastic material to the modeled parts in the simulations are difficult task. For the simulations, material model should be well chosen and material coefficients of the chosen models should be known. In order to obtain accurate simulations, hyperelastic characteristics of the viscoelastic materials should be investigated and hyperelastic model should be incorporated in the solutions. Material models and material model&rsquo / s coefficients are chosen with the help of mechanical tests/experiments for these situations. The main goal of this thesis is to optimize material model&rsquo / s coefficients by using an indenter test setup results and inverse finite element modeling. To achieve this, firstly by using a haptic device and other required equipments an indenter setup was prepared to test the materials mechanically. Inverse finite element modeling method is used in order to model the materials according to their viscoelastic and hyperelastic characteristics. The model obtained from analysis was optimized by using the results obtained from indenter setup according to experimental test data. By doing this, the correctness of the model chosen by inverse finite element modeling was proved for the tested material and material model coefficients were calculated correctly.
79

A 3D Computer Vision System in Radiotherapy Patient Setup

Chyou, Te-yu January 2012 (has links)
An approach to quantitatively determine patient surface contours as part of an augmented reality (AR) system for patient position and posture correction was developed. Quantitative evaluation of the accuracy of patient positioning and posture correction requires the knowledge of coordinates of the patient contour. The system developed uses the surface contours from the planning CT data as the reference surface coordinates. The corresponding reference point cloud is displayed on screen to enable AR assisted patient positioning. A 3D computer vision system using structured light then captures the current 3D surface of the patient. The offset between the acquired surface and the reference surface, representing the desired patient position, is the alignment error. Two codification strategies, spatial encoding, and temporal encoding, were examined. Spatial encoding methods require a single static pattern to work, thus enabling dynamic scenes to be captured. Temporal encoding methods require a set of patterns to be successively projected onto the object, the encoding for each pixel is only complete when the entire series of patterns has been projected. The system was tested on a camera tracking object. The structured light reconstruction was accurate to within ±1 mm, ±1.5 mm, and ±4 mm in x, y, and z-directions (camera optical axis) respectively. The method was integrated into a simplified AR system and a visualization scheme based on z-direction offset was developed. A demonstration of how the final AR-3D vision hybrid system can be used in a clinical situation was given using an anatomical teaching phantom. The system and visualisation worked well and demonstrated the proof of principal of the approach. It was found that the achieved accuracy was not yet sufficient for clinical use. Further work on improving the projector calibration accuracy is required. Both the camera registration process and 3D computer vision using structured light have been shown to be capable of sub-millimeter accuracy on their own. If that level of accuracy can be reproduced in this system, the concept presented can potentially be used in Oncology departments as a cost-effective patient setup guidance system for external beam radiotherapy, used in addition to current laser/portal imaging/cone beam CT based setup procedures.
80

Instalação e capacidade de carga axial de estacas modelo fluidizadas em solos arenosos / Installation and axial load capacity of fluidized model piles in sandy soils

Passini, Larissa de Brum January 2015 (has links)
O objetivo desta tese foi verificar a viabilidade de utilização de jatos de água verticais circulares, únicos e contínuos, provenientes da ponteira de uma estaca torpedo, para auxiliar sua instalação por peso próprio no leito marinho, através da fluidização do solo. Foram realizados ensaios de laboratório, em modelo reduzido, utilizando hastes para simular estacas torpedo (sem aletas) seguindo a lei de semelhança pelo número de Froude. Os ensaios de instalação por peso próprio, com e sem fluidização, ocorreram sem altura de queda, com a estaca modelo em contato com a superfície do leito. Trabalhou-se com três diâmetros de estacas, seis massas, quatros vazões e areia fina saturada compactada em duas densidades relativas iniciais (média e densa). Os ensaios de arrancamento, em leito arenoso fluidizado e não fluidizado, foram realizados imediatamente, 4, 24 e 48 horas após a instalação dos modelos. A metodologia de instalação proposta mostrou-se viável, quando o jateamento é aplicado desde a superfície em solo arenoso. As profundidades instaladas atingidas por fluidização (L/de > 50) foram consideravelmente superiores às profundidades cravadas por apenas peso próprio (L/de < 5). A geometria da zona perturbada durante a instalação por fluidização dos modelos, permaneceu constante e paralela ao fuste, com geometria de aproximadamente 2de em relação ao modelo, independentemente da vazão aplicada e da densidade relativa inicial do solo. A partir das leis de análise dimensional, uma expressão para a profundidade instalada das estacas modelo foi proposta, mostrando que a mesma é função do peso e da geometria do modelo, das propriedades físicas do solo e do fluido, e de sua vazão. Quanto maior a massa do modelo e a vazão aplicada e menor a densidade relativa, maior a profundidade atingida e maior a velocidade inicial de instalação. Constatou-se que a capacidade de carga axial dos modelos depende da densidade relativa, do diâmetro do modelo e do método de instalação (com e sem fluidização). Independentemente da densidade relativa inicial, o solo fluidizado convergiu para a mesma densidade relativa final, próxima as suas condições no estado crítico. As estacas em solo fluidizado apresentaram ganho resistência com o tempo (efeito de setup), com capacidade de carga inferior às estacas cravadas em solo não fluidizado. / The aim of this thesis was to investigate the feasibility of using circular vertical water jets, single and continuous, from the tip of a torpedo pile, to assist its installation by own weight on the seabed, through soil fluidization. Laboratory model tests were carried out, using tubes to simulate torpedo piles (without wings) following the law of similarity defined by the Froude number. The installation tests by the pile own weight, with and without fluidization, occurred without drop height, with the piles in contact with the surface of the bed. Three diameters of model piles and six masses, four flow rates and saturated sand at two initial relative densities (medium and dense) have been used in this set of experiments. Pullout tests in fluidized and nonfluidized soils were performed immediately, 4, 24 and 48 hours after the installation of the models. The proposed installation methodology proved to be feasible when the fluidization is applied from the surface in sandy soils. The installation depths achieved by fluidization (L/de > 50) were significantly higher than the depths reached by pile own weight (L/de < 5). The geometry of the perturbed zone during model installation by fluidization remained constant and parallel to the shaft in a geometry of about 2de of the pile model, regardless of the applied flow rate and the initial relative density of the soil. Following the laws of dimensional analysis, an expression for the embedment of fluidized piles is derived, showing that the penetration depth is a function of pile weight and geometry, fluidized water jet flow rate and velocity, as well as the soil and fluid properties. Increasing the model mass and fluidized flow rate and decreasing the relative density leads to an increase in the depth reached and the initial speed of installation. The axial load capacity of the models depends on the soil relative density, piles diameter and installation method (with and without fluidization). Regardless the initial relative density, the fluidized soil converged to the same final relative density, near its conditions of critical state. Piles installed in fluidized soil presented gain of axial capacity over time (setup effect) with lower resistance than piles driven in nonfluidized soil.

Page generated in 0.038 seconds