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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.
41

Compression vidéo très bas débit par analyse du contenu / Low bitrate video compression by content characterization

Decombas, Marc 22 November 2013 (has links)
L’objectif de cette thèse est de trouver de nouvelles méthodes de compression sémantique compatible avec un encodeur classique tel que H.264/AVC. . L’objectif principal est de maintenir la sémantique et non pas la qualité globale. Un débit cible de 300 kb/s a été fixé pour des applications de sécurité et de défense Pour cela une chaine complète de compression a dû être réalisée. Une étude et des contributions sur les modèles de saillance spatio-temporel ont été réalisées avec pour objectif d’extraire l’information pertinente. Pour réduire le débit, une méthode de redimensionnement dénommée «seam carving » a été combinée à un encodeur H.264/AVC. En outre, une métrique combinant les points SIFT et le SSIM a été réalisée afin de mesurer la qualité des objets sans être perturbée par les zones de moindre contenant la majorité des artefacts. Une base de données pouvant être utilisée pour des modèles de saillance mais aussi pour de la compression est proposée avec des masques binaires. Les différentes approches ont été validées par divers tests. Une extension de ces travaux pour des applications de résumé vidéo est proposée. / The objective of this thesis is to find new methods for semantic video compatible with a traditional encoder like H.264/AVC. The main objective is to maintain the semantic and not the global quality. A target bitrate of 300 Kb/s has been fixed for defense and security applications. To do that, a complete chain of compression has been proposed. A study and new contributions on a spatio-temporal saliency model have been done to extract the important information in the scene. To reduce the bitrate, a resizing method named seam carving has been combined with the H.264/AVC encoder. Also, a metric combining SIFT points and SSIM has been created to measure the quality of objects without being disturbed by less important areas containing mostly artifacts. A database that can be used for testing the saliency model but also for video compression has been proposed, containing sequences with their manually extracted binary masks. All the different approaches have been thoroughly validated by different tests. An extension of this work on video summary application has also been proposed.
42

The Susceptibility of Electric Resistance Welded Line Pipe to Selective Seam Weld Corrosion

Ritchie, Porter 07 October 2020 (has links)
No description available.
43

Clip Reactions in Standing Seam Roofs of Metal Buildings

Fowler, Shaunda Lynn 04 August 2001 (has links)
Prediction of the clip reactions of a standing seam roof in a metal building under dynamic loading is of great interest because currently static uplift tests are the standard for determining the design load capacity. The use of a static test to replicate a dynamic loading leads to a great amount of debate because clearly a standing seam roof visually behaves very different under the two different types of loads. This leads to the question of whether a static test accurately replicates the magnitude of loads that the roof clips would feel under a dynamic wind load. This study uses a magnetic suspension uplift loading for the simulation of wind tunnel data in comparison with the ASTM E-1592 ?Standard Test Method for Structural Performance of Sheet Metal Roof and Siding Systems by Uniform Static Air Pressure Difference? test to determine clip reactions. An approximate finite element model is also utilized to verify the validity of the experimentally acquired clip reactions to form another comparison.
44

"Jaha, det gick ju bra den här gången också" : En kvalitativ undersökning av seniorers förhållande till e-handel / "Oh well, it worked out this time as well" : A qualitative study of the relationship between seniors and e-business

Ekman, Agnes, Hägglund, Emma January 2012 (has links)
In this paper we have examined why seniors do not use e-business to the same extent as other age groups. Seniors belong to the age group that, according to statistics from Statistics Sweden (SCB) in 2011, utilizes e-business the least in relation to the number who use the internet. To understand how seniors reason and perceive the possibility to shop on the internet, we have conducted four interviews with people from 65 years and older. We have let the respondents answer questions regarding utility aspects, e-business interfaces, general shopping habits, risks, and whether or not they usually shop online. We also found out how seniors reason when they sell products and services. The results of our study show that seniors must see a benefit in using an e-business, that lack of knowledge can make them opposed to it and that they are characterized by a certain reluctance and aversion towards learning how e-business works. In this study we have used Technology Acceptance and Adoption Model (STAM) by Renaud and van Biljon (2008), to see what constitutes the seniors accepting or rejecting a technology. The model is focused on seniors and technology but not on e-business so we developed our own model, Senior E-Business Adoption & Acceptance Model (SEAM), focusing on seniors and e-business. / I den här uppsatsen har vi valt att ta reda på varör seniorer inte nyttjar möjligheten att handla via e-handel i samma utsträckning som övriga åldersgrupper. Seniorer tillhör den ålderskategori som, enligt statistik från Statistiska Centralbyrån (SCB) år 2011, handlar via e-handel minst i förhållande till antalet som använder internet. För att förstå hur seniorerna resonerar och upplever möjligheten att handla via internet har vi genomfört fyra kvalitativa intervjuer med personer från 65 år och uppåt. Vi har låtit intervjupersonerna besvara ett antal frågor gällande nyttoaspekt, e-handelsgränssnitt, generella shoppingvanor, risker och huruvida de själva brukar handla via internet. Vi har också tagit reda på hur seniorerna resonerar gällande att sälja produkter och tjänster. Resultatet av vår undersökning visar att seniorer måste se en nytta i att använda en e-handel, att okunskap kan göra dem negativt inställda och att de präglas av en viss ovilja och olust att lära sig hur e-handel fungerar. I studien har vi utgått från Technology Acceptance and Adoption Model (STAM) av Renaud och van Biljon (2008), för att se vad som leder fram till att seniorerna accepterar eller förkastar teknik. Modellen fokuserar på seniorer och teknik men inte på e-handel så vi valde att vidareutveckla den och skapade Senior E-business Adoption & Acceptance Model (SEAM) med inriktning på både seniorer och e-handel.
45

Analysis and Characterization of Residual Stresses in Pipe and Vessel Welds

Song, Shaopin 15 December 2012 (has links)
This research sought to establish residual stress distribution characteristics in typical pipe and vessel welds by carrying out a comprehensive parametric study using an advanced sequentially coupled thermo-mechanical finite element procedure. The parametric study covered vessel and pipe components with a ranging radius to thickness ratio from r/t=2 to 100, for thickness ranging from t=1/4” to 10”. Component materials varied from low carbon steel to high alloy steels, such as stainless steel and titanium alloy. Furthermore, a structural mechanics based framework is proposed to generalize through-thickness residual stress distributions for a broad spectrum of joint geometry and welding conditions. The results of this study have been shown to provide both a significantly improved understanding of important parameters governing residual stresses in pipe and vessel welds, as well as a unified scheme for achieving consistent residual stress prescriptions for supporting fitness-for-service assessments of engineering structures. Specific contributions of this investigation may be summarized as follows: (a) A welding heating input characterization procedure has been developed and validated to relate prescribed temperature thermal modeling procedure to conventional linear input definition. With this development, a large number of parametric analyses can be carried in a cost-effective manner without relying on the heat flux based weld pool model that can be exhaustive and time-consuming. (b) A set of governing parameters controlling important residual stress distribution characteristics regardless of joint types, materials, and welding procedures have been identified. These are characteristic heat input intensity and radius over thickness ratio. (c) A shell theory based residual stress estimation scheme has been developed to interrelate all parametric analysis results for circumferential girth welds, which can also be used to estimate residual stress distributions in both through-thickness and at any distance away from the weld, for cases that are not covered in the parametric study. (d) In a similar manner, a curve bar theory based residual stress estimation scheme has also been developed for longitudinal seam welds. These developments can significantly advance the residual stress profile prescription methods stipulated in the current national and international FFS Codes and Standards such as 2007 API 579 RP/ASME FFS-1 and BS 7910: 2011.
46

Durabilité des méthodes de management dans les organisations : cas des projets de management socio-économique / Sustainability of management methods in organizations : case of Socio-Economic Approach of Management projects

Desmaison, Gérard 24 March 2014 (has links)
Comment pérenniser les méthodes de management dans les entreprises pour améliorer la performance globale des acteurs et concilier changement et plaisir de travailler?Nous avons choisi d’effectuer une recherche longitudinale historique sur une méthode de management : le Management Socio-Économique à travers plusieurs organisations de 1984 à nos jours en nous appuyant sur des concepts théoriques (outils de gestion, résilience organisationnelle, théorie socio-économique), des interviews croisées (dirigeants, intervenants-chercheurs et d’acteurs d’entreprise) et sur l’expérience professionnelle du chercheur.Nous en tirons les conditions de durabilité de la méthode étudiée mais aussi une généralisation à d’autres méthodes de management. La durée de vie des méthodes de management dépend de l’atteinte de résultats économiques attendus, du comportement du dirigeant, de l’incrustation de la méthode dans l’entreprise et de l’anticipation de l’attente des acteurs. / How to sustain the management methods in companies to improve the overall performance of the actors and reconcile change and pleasure to work?We chose to perform a historical longitudinal research on a management method: Socio- Economic Approach of Management (SEAM) from 1984 in organizations based on theoretical concepts (management tools, organizational resilience, socio-economic theory), cross interviews (leaders, practitioners, actors) and the professional experience of the author.We define the conditions for the studied sustainable method (SEAM) but also a generalization to other management methods. The duration of life of a management method depends on the achievement of expected economic performance, of the behavior of the leader, of the incrustation of the method in the company and of the anticipation of expectations of the actors.
47

Prestandajämförelse av ABBs EGM och Permanova Lasersystems externaxel för fogföljning / Comparison of ABB EGM and Permanova external axis in performance and seam tracking

Hansson, Niklas, Nyberg, Eleonore January 2019 (has links)
Syftet med denna studie är att jämföra två olika lösningar för fogföljning med svetsrobot. I nuläget används en extern sjunde axel utgiven av Permanova, denna jämförs med programvara från ABB vid namn EGM. Främst skall dödtid och tidskonstant fastställas och jämföras för systemen. Problematiken med detta var främst osäkerheten i den okulära inspektion av graferna som gav värdena. Ytterligare ett problem, som dessutom försvårade avläsningarna, var att det förekom störningar i processen som orsakade förvrängda kurvor. Experimenten utfördes på en modell av den riktiga processen. I den modellerade processen anslöts ingen svetsanordning till roboten, istället monterades en laseravståndsgivare som mätte mot ett parallellt metallblock. Den sjunde axeln var ansluten vid alla test för att säkerställa att resultaten var jämförbara med hänseende till vikten som belastar robotarmen. Varje testfall hade olika parametrar, så som hastighet och avstånd från robotbas. Flera experiment gjordes med samma parametrar för att säkerställa bra resultat. Analys av insamlade data gjordes bland annat genom att liknande stegsvar av första ordningen jämfördes med experimentets stegsvar. Det estimerade stegsvarets värden finjusterades tills dess att de båda stegsvaren var någorlunda lika, dock är mänsklig faktor mycket relevant i denna analys. Resultatet visade en klar fördel med Permanovas sjunde axel i både minskad dödtid och tidskonstant. Exempelvis var det filtrerade medelvärdet för dödtiden med EGM 266 ms och en standardavvikelse på 20,8 ms, medan det för Permanova är nere på 11,5 ms och standardavvikelse på 2,0 ms. De filtrerade tidskonstanterna följde samma trend och uppgick till 68 ms, standardavvikelse 13,5 ms, för EGM respektive 33 ms och standardavvikelse 4,8 ms för Permanova. Det var överraskande att skillnaden mellan EGM och Permanovas sjunde axel var så pass stor, men sjunde axeln verkar helt klart vara bäst lämpad för en sådan här process på grund av dess mycket snabbare dödtid och tidskonstant. Då EGM presterade så mycket sämre anses den inte lämplig för applikationer i lasersvetsning på PTC. / The purpose of this study is to compare solutions for seam tracking with a welding robot. At the moment the used solution is an external seventh axis made by Permanova which is going to be compared to software made by ABB called EGM. The primary comparisons shall be done regarding the dead time and the time constant of the two processes. A primary problem with this was the uncertainty that comes with ocular inspection of the graphs in order to extract relevant values. Another problem, that also made construing the curves harder, was that there were some disturbances that caused distorted curves. Experiments were done on a model of the actual process, meaning that no welding equipment was connected to the robot in this model process. Instead a laser sensor was mounted onto the robot that measured against a parallel metal block. The seventh axis was connected for all tests to make sure that the results were comparable when it comes to the weight that the robot arm is burdened with. Each experiment had different parameters, such as speed and distance from the robot's base. Several tests were made with the same parameters to make sure that good results were had. One method used for analysis of gathered data was comparing a similar first order system to the step response of different experiments. The values of this approximate step response were tweaked until both step responses were fairly similar, however, the human factor is very relevant in this analysis. The results showed a clear advantage towards Permanova's seventh axis in both decreased dead time and time constant. For example, the filtered mean value for the dead time with EGM was 266 ms and a standard deviation of 20,8 ms, while Permanova clocked in at 11,5 ms with a standard deviation of 2,0 ms. The filtered time constants followed the same trend and were at 68 ms, standard deviation of 13,5 ms, for EGM and 33 ms, standard deviation of 4,8 ms, for Permanova. It was quite surprising how big the difference was between EGM and Permanova's seventh axis, but the seventh axis was without a doubt the solution best suited to this kind of process. Due to the lacking performance from EGM it is determined to be unfit for laser welding applications at PTW.
48

Prozessdatenanalyse zur Inline-Verminderung von Störeinflüssen beim Ultraschallsiegeln

Thürling, Karsten 03 November 2016 (has links)
Beim Siegeln von Verpackungen können nicht-qualitätsgerechte Siegelnähte dadurch entstehen, dass sich Teile des Packguts zwischen den zu fügenden Packmittelbahnen befinden. Im Gegensatz zum konventionellen Wärmekontaktsiegeln besteht beim Ultraschallsiegeln die Möglichkeit, für jeden einzelnen Siegelvorgang Prozessdaten zu erfassen. Aus dem Bereich des Ultraschallschweißens ist bekannt, dass sich anhand dieser Daten der Prozess überwachen und dessen Güte bewerten lässt. Die vorliegende Arbeit untersucht den Informationsgehalt dieser Prozessdaten hinsichtlich störungsbehafteter Siegelnähte und leistet damit einen Beitrag zur Verbesserung der Verpackungsqualität und damit im besten Fall auch zu weniger Lebensmittelverlusten. Es wird dazu zunächst eine Systematisierung von möglichen Störprinzipen beim Siegeln hinsichtlich ihrer physikalischen Wirkprinzipe vorgenommen. Darauf aufbauend konnte ein Versuchsstand und eine Methodik zur Untersuchung der Thematik entwickelt werden. Abschließend wurden ausgewählte Störprinzipe untersucht, wobei sich ein sehr starker Packstoff- und Einfluss der Prozessführung herausstellte. Es konnte ein prinzipieller Zusammenhang zwischen Auswirkung einer Störung auf die Nahtqualität und die Prozessdaten gezeigt werden, welcher sich jedoch auf Basis der erarbeiteten Ergebnisse nicht verallgemeinern lässt.
49

Bereitstellung von Materialkennwerten für die Simulation von Bekleidungsprodukten

Seif, Manal Abdel-Aziz Mohamed 30 July 2007 (has links)
Die exakte Kenntnis vom Materialverhalten und speziell von lokalen Flächenmasseschwankungen der textilen Flächen ist Voraussetzung für eine Verbesserung der Produktentwicklung und für eine hohe Qualitätsverarbeitung in der Konfektionsindustrie. Dieser Fakt ist ebenfalls für die zunehmende Anwendung im Bereich der Simulationsberechnungen von erheblicher Bedeutung. Der Wandel von 2D-CAD- zu 3D-CAD-Systemen führt in der Bekleidungsindustrie zur zwingenden Berücksichtigung der Materialeigenschaften. Aufgrund des Montageprozesses zeigen die konfektionierten textilen Flächen im Vergleich zu unkonfektionierten textilen Flächen ein anderes Erscheinungsbild. Mehrlagige Gewebe (infolge einer Naht, einer Einlage oder eines Futterstoffes) beeinflussen das Biegeverhalten und das Fallverhalten der textilen Flächen erheblich. Zur Bestimmung der Biegesteifigkeit ist seit Jahrzehnten das manuell zu bedienende Prüfgerät nach dem Cantilever-Verfahren das Bekannteste. Die eigenen Untersuchungen bestätigen, dass das Prüfgerät viele Mängel hat, welche die Genauigkeit und die Reproduzierbarkeit der Messergebnisse wesentlich beeinflussen. Im Rahmen dieser Arbeit wird ein neues Biegesteifigkeitsprüfgerät (ACPM 200) entwickelt, um eine optimale Genauigkeit und hohe Reproduzierbarkeit der Messergebnisse zu erfassen. Eine neue Methode zur Ermittlung des Einflusses der Naht auf die Biegesteifigkeit einer größeren textilen Fläche ist in der Arbeit vorhanden, um die exakte Beschreibung des realen Verhaltens von textilen Bekleidungsprodukten zu ermitteln. Die Simulation des Biegeverhaltens textiler Flächen ohne und mit vertikaler Naht wird mit Hilfe der FEM durchgeführt. Abschließend wird eine neue Prüfnorm vorgestellt, welche die Biegesteifigkeit von textilen Flächen mit lokalen Flächenmasseschwankungen mittels des neuen Biegesteifigkeitsprüfgerätes ACPM 200 beinhaltet. / Bending stiffness and Drapeability are essential material parameters for simulating textile and clothing products. Due to assembling processes garments are showing different appearances through modelling than textile fabrics. This is based on stiffening, which is caused by assembling process and local variations within material’s mass throughout the fabric. Since decades the manual bending stiffness testing device, which is based on Cantilever method, has been known. This device is insufficient because of irregular feed speed of bending sample, the visual determination of reaching and reading the bending length, the little reading precision of the measurable slide (half Millimetre) and the form of the front edge of the sample does not stay linear. Obtaining an exact evaluation of this sample edge is not possible with this device. Extensive experiments have confirmed that these deficits influence the accuracy and the reproduction of the results in a high degree. To remedy these deficits and to obtain an exact description of the material’s behaviour in order to achieve an optimal modelling of the clothing products is the new bending stiffness testing device (ACPM 200) at the ITB of TU Dresden developed. Within the investigations a new method for determining the influence of the seam on the bending stiffness of the adjacent textile fabric will be introduced. The Influence of seams on the drapability of textile fabric is investigated. A static model of Fabric with and without vertical seams is analysed with using the finite element method (FEM).
50

Passform på babyleggings : En studie kring faktorer i grenen som påverkar passformen

Hoveida, Arvin January 2020 (has links)
Denna studie undersöker vilka faktorer i grenen på babyleggings som kan komma att påverkapassformen. En marknadsundersökning visar att ett flertal leggings erhåller passformsproblem i grenen bak. Få studier har gjorts kring barnplagg och passform, därmed jämförs leggings från marknaden mot leggings konstruerade utifrån litteratur för att finna konstruktionsmässiga likheter och skillnader. Genom digitalisering av marknadens fysiska plagg kunde grenkurvorna tydligt jämföras mot litteraturens konstruktioner och tillsammans medavprovningar samt prototypframtagning kunde slutsatser dras. Resultatet visade på stora skillnader där marknadens plagg hade en bättre passform och anknytning till målgruppenskroppsutformning. Dock fanns passformsproblem i form av en nedåtdragande midjelinje bak och dragningar i sidan. Detta kunde knytas till en konstruktion med en djup grenkurva och stor lutning. Även en mindre lutad gren tillsammans med en grund kurva gav oönskadpassform. Resultatet visade även att grensträckan inte är en påverkande faktor, utan formplaceringen i grenkurvan. Studiens resultat applicerades och vidareutvecklade litteraturens konstruktion som mynnade ut i ett grundmönster. Konstruktionen kommer att vara till hjälp för företag som kan använda den i kommunikationen med leverantörer för att minska på prototypframtagningen. / This thesis investigates factors which may influence the fit of the back rise in baby leggings. Market research showed that a majority had issues regarding fit of the back rise. There’s no studies made regarding children´s clothes and fit, therefore leggings from the market has been compared to patterns in literature to find deviations and similarities. With digitalization of the market’s leggings the curvature of the back rise could be compared to those made from literature. Together with fittings and production of prototypes conclusions could be made. The result showed significant deviations where the market’s leggings overall obtained the most pleasing fit and body-to- pattern relationship. Fitting problems was found at the waistline back which created a concave line and pulling was found at the side seams. This was connected to a pattern with a deep curve and significantly tilted back rise. It was found that the curve depth and tilt of the back rise had a vast influence on the garment fit, rather than the length. The conclusions were used to create a basic pattern for baby leggings that companies can utilize in the communication with suppliers to minimize the number of prototypes.

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