• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 50
  • 13
  • 10
  • 9
  • 6
  • 6
  • 4
  • 3
  • 1
  • 1
  • 1
  • Tagged with
  • 123
  • 18
  • 13
  • 12
  • 12
  • 11
  • 11
  • 10
  • 9
  • 9
  • 9
  • 8
  • 8
  • 8
  • 7
  • 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.
1

Příprava a využití α-alkyliden-β-laktamů ve zkrížených metatezích / Praparation and use of α-alkylidene-β-lactams in cross-metathesis

Kretschmer, Jan January 2016 (has links)
The main topic of this thesis was preparation of α-alkyliden-β-lactams and their use in cross metathesis in a presence of transition metal catalyst. Kinugasa reaction as well as Morita- Baylis-Hillman derivatives were used for preparation of lactams. α-alkyliden-β-lactams were used in reactions with aliphatic alkens and for study of subsituent electronic effect on lactames in cross metathesis step. The formal total synthesis of Ezetimibe was also developed in this work.
2

Konfigurationshanteringsverktyg (CM-verktyg) och CM-kriterier, dess tillämpning för presentation av migreringsdata

Skogsberg, Joakim January 2010 (has links)
The purpose of this thesis is to present and describe which criteria, according to the systemfamily Configuration Management, should be met when developing a CM-tool to handlemigration data.ACT is a tool developed by Microsoft to gather information about, analyze, test and mitigateapplications in a network when migrating the IT-infrastructure of an organization to a newoperating system. The organization that is being studied wants to present the data about theanalyzed applications in such a way, that a customer can choose what to mitigate and migrate.The goal is therefore to develop a prototype (CM-tool) that will present this data.The study has shown that ACT lacks certain requirements stated by the organization when itcomes to presentation. But when it comes to the rest of the functions, ACT performs as expected.The investigation resulted in specifications and technical solution for the new CM-tool. CMcriteriafor migration data was put forth and parts of the prototype were also developed.
3

Surface structure study of imidazolium based ionic liquid

Kadel, Rajesh January 1900 (has links)
Master of Science / Department of Physics / Bruce M. Law / Interest in the properties of room-temperature ionic liquids is rapidly expanding. Although there have been numerous studies concerning their preparation, their use as a reaction medium and their physical properties, Ionic Liquids (ILs) are so new that many of their bulk physicochemical properties, optical properties, surface properties, toxicities etc. are unknown or only just beginning to be characterized. The highly polar nature of the ILs causes the surfaces of the liquids to become highly ordered in comparison with the surfaces of many other types of organic liquids. Surface structuring at the liquid-vapor interface of the imidazolium based ILs can be examined by using Brewster Angle Ellipsometry and Contact Angle Measurement. The preliminary observation of Ellipsometric measurement shows that there is an interfacial order-disorder transition at temperature Tc=385 K. This result is not analyzed yet but the initial thought behind this is an indication of a ferroelectric transition at the liquid-vapor interface of dipole moment of ILs. From the contact angle measurement it is shown that there is a remarkable change in the contact angle of the imidazolium based ILs over short interval of time ([similar to] ten minutes). Also study of the spreading of the ILs on hard surface shows that there is some definite structural dependence
4

Effekt på värdeutfallet av sågad vara vid övergång från 30 till 60 cm moduler : - en fallstudie av Moelven

Lundgren, Joakim, Larsson, Joakim January 2007 (has links)
The purpose of this study is to explain how the value of sawn wood changes when sawn wood are cut in 30 respective 60 cm lengths. The raw material into the saw mill will mainly be bucked in 30 cm and 60 cm modules. There will also be two alternatives where the timber will be bucked special lengths, 370, 490 and 550 cm but also in 490 and 550 cm. The method used for the study is to simulate both cutting and sawing the woods. For cutting the simulator Timan is used and for sawing the simulator Timberopt is used. When data is generated from the simulators, calculations of some key figures is done and also how much the revenue need to be increased for the sawn wood in order to cover for the increased costs of changing sawn wood from 30 cm to 60 cm modules The conclusion is that the single biggest reason, impacting the value of the sawn wood is the cutting at the saw mill. When going from 30 to 60 cm modules, the impact will be that the customers to the saw mill must pay more to increase the revenue by at least 10% for the sawn wood in order to justifice the change in production. It is also possible to increase the value of the products further by bucking the timber in three lengths, 370, 490 and 550 cm, in order to get 12 % increase of the share of longer sawn wood (>= 480 cm). / Syftet med studien är att förklara hur värdet på sågad vara förändras när den avkapas i 30 respektive 60 cm moduler. Råvaran in till sågverket kommer huvudsakligen att apteras i 30 cm respektive 60 cm moduler. Det kommer också att finnas två alternativ där timret apteras i speciallängderna 370, 490 och 550 cm, samt 490 och 550 cm. Metoden som användes i studien är att simulera såväl aptering som avkapning. För aptering i skogen användes simulatorn Timan. För sönderdelning och avkap på sågverket användes simulatorn Timberopt. När data genererats från simulatorerna har också beräkning av vissa nyckeltal gjorts, samt beräkningar på hur mycket intäkterna för den sågade varan behöver öka för att täcka värdeminskningen av en omläggning av sågad vara från 30 cm till 60 cm moduler. Slutsatsen är att den största, enskilda posten till minskat värde uppstår vid avkapet i justerverket. Vid en övergång från 30 cm till 60 cm moduler, blir konsekvensen att kunderna till sågverket måste vara beredda att betala minst 10% mer för att täcka värdeminskningen vid omläggning till 60 cm moduler. Det är också möjligt att öka värdet på produkten ytterligare genom att aptera timret i två långa och en kort längd, dvs 370, 490 och 550 cm. Då fås en ökning med ca 12% av sågad vara som överstiger 480 cm i längd.
5

Effekt på värdeutfallet av sågad vara vid övergång från 30 till 60 cm moduler : - en fallstudie av Moelven

Lundgren, Joakim, Larsson, Joakim January 2007 (has links)
<p>The purpose of this study is to explain how the value of sawn wood changes when sawn wood are cut in 30 respective 60 cm lengths. The raw material into the saw mill will mainly be bucked in 30</p><p>cm and 60 cm modules. There will also be two alternatives where the timber will be bucked special lengths, 370, 490 and 550 cm but also in 490 and 550 cm.</p><p>The method used for the study is to simulate both cutting and sawing the woods. For cutting the simulator Timan is used and for sawing the simulator Timberopt is used. When data is generated</p><p>from the simulators, calculations of some key figures is done and also how much the revenue need to be increased for the sawn wood in order to cover for the increased costs of changing sawn wood</p><p>from 30 cm to 60 cm modules</p><p>The conclusion is that the single biggest reason, impacting the value of the sawn wood is the cutting at the saw mill.</p><p>When going from 30 to 60 cm modules, the impact will be that the customers to the saw mill must pay more to increase the revenue by at least 10% for the sawn wood in order to justifice the change</p><p>in production.</p><p>It is also possible to increase the value of the products further by bucking the timber in three lengths, 370, 490 and 550 cm, in order to get 12 % increase of the share of longer sawn wood (>= 480 cm).</p> / <p>Syftet med studien är att förklara hur värdet på sågad vara förändras när den avkapas i 30 respektive 60 cm moduler. Råvaran in till sågverket kommer huvudsakligen att apteras i 30 cm respektive 60 cm moduler. Det kommer också att finnas två alternativ där timret apteras i speciallängderna 370, 490 och 550 cm, samt 490 och</p><p>550 cm.</p><p>Metoden som användes i studien är att simulera såväl aptering som avkapning. För aptering i skogen användes simulatorn Timan. För sönderdelning och avkap på sågverket användes simulatorn Timberopt. När data genererats från simulatorerna har också beräkning av vissa nyckeltal gjorts, samt beräkningar på hur mycket intäkterna för den sågade varan behöver öka för att täcka värdeminskningen av en omläggning av sågad vara från 30 cm till 60 cm moduler.</p><p>Slutsatsen är att den största, enskilda posten till minskat värde uppstår vid avkapet i justerverket.</p><p>Vid en övergång från 30 cm till 60 cm moduler, blir konsekvensen att kunderna till sågverket måste vara beredda att betala minst 10% mer för att täcka värdeminskningen vid omläggning till 60 cm moduler.</p><p>Det är också möjligt att öka värdet på produkten ytterligare genom att aptera timret i två långa och en kort längd, dvs 370, 490 och 550 cm. Då fås en ökning med ca 12% av sågad vara som överstiger 480 cm i längd.</p>
6

Category management

Beran, Jan January 2007 (has links)
Práce popisuje category management, jeho definice a vývoj. Stěžejní část práce se věnuje osmi krokům category management procesu a subjektům, které do tohoto procesu vstupují. Mezi osm kroku patří definování kategorie, analýza kategorie, hodnocení subjektů, stanovení cíle kategorie, taktická rozhodnutí, strategická rozhodnutí, implementace a zpětná vazba. Praktická část je zaměřena na deskripci konkrétního category management projektu a tento projekt je porovnán s teoretickými předpoklady.
7

The CM class number one problem for curves / Le problème du nombre de classes 1 pour les courbes à multiplication complexe

Kilicer, Pinar 05 July 2016 (has links)
Soit E une courbe elliptique sur C ayant multiplication complexe (CM) par l’ordre maximal OK d’un corps quadratique imaginaire K. Le premier théorème principal de la multiplication complexe affirme que le corps K(j(E)), obtenu en adjoignant à K le j-invariant de E, est égal au corps de classes de Hilbert de K, confer Cox [11, Theorem 11.1]. Notons que lorsque E est définie sur Q, le corps de classes de Hilbert K(j(E)) est égal à K et le groupe des classes ClK est trivial. Se pose alors le problème de déterminer les corps quadratiques totalement imaginaires K pour lesquels la courbe elliptique à multiplication complexe par OK correspondante est définie sur Q. De façon équivalente, il s’agit de trouver tous les corps quadratiques imaginaires dont le groupe des classes est trivial. Ce problème est connu sous le nom de problème du nombre de classes 1 de Gauss et a été résolu par Heegner en 1952 [16], Baker en 1967 [2] et Stark en 1967 [41]; les corps quadratiques imaginaires dont le groupe des classes est trivial sont les corps Q(racine carrée−d), où d e {3, 4, 7, 8, 11, 19, 43, 67, 163}. Dans les années ’50, Shimura et Taniyama [39] ont généralisé le premier théorème principal de la multiplication complexe aux variétés abéliennes. On dit qu’une variété abélienne A de dimension g a multiplication complexe si son anneau d’endomorphismes contient un ordre d’un corps CM de degré 2g. Soit K un corps CM de degré 2g et d’ordre maximal OK et soit un type CM de K. Soit A une variété abélienne complexe simplement polarisée de dimension g ayant multiplication complexe par OK. Le premier théorème principal de la multiplication complexe dans ce cadre affirme que le corps de classes H du corps du modules M de la variété abélienne simplement polarisée A est une extension non ramifiée du corps reflex Kr de K. De plus, le corps des classes H correspond au groupe d’idéaux I0(.r) (voir page 17) qui ne dépend que de (K,.), confer Théorème 1.5.6. Notons que le premier théorème de la multiplication complexe implique que si la variété abélienne polarisée A est définie sur Kr, le groupe des classes CM IKr/I0(.r) est trivial. Comme dans le cas des courbes elliptiques, on peut alors chercher à déterminer les couples CM (K,.) pour lesquels les variétés abéliennes correspondantes sont définies sur Kr. De fa¸con équivalente, il s’agit de déterminer les couples CM (K,.) dont le groupe des classes CM, IKr/I0(.r), est trivial. Dans cette thèse, on résout ce problème dans le cas des corps CM quartiques imaginaires (voir Chapitre 2) ainsi que dans celui des corps CM sextiques contenant un corps quadratique imaginaire (voir Chapitre 3). Enfin, on peut se demander quels sont les corps CM pour lesquels la variété abélienne simple à multiplication complexe admet Q comme corps de module. Murabayashi et Umegaki [31] ont déterminé les corps quartiques CM correspondant aux surfaces abéliennes simples à multiplication complexe de corps du module Q. Dans le chapitre 4, on détermine les corps CM sextiques correspondant aux variétés abéliennes simples à multiplication complexe de dimension 3 de corps du module Q. / Let E be an elliptic curve over C with complex multiplication (CM) by the maximal order OK of an imaginary quadratic field K. The first main theorem of complex multiplication for elliptic curves then states that the field extension K(j(E)), obtained by adjoining the j-invariant of E to K, is equal to the Hilbert class field of K, see Theorem 11.1 in Cox [11]. Note that if E is defined over Q, then the Hilbert class field K(j(E)) is equal to K, which implies that the class group ClK is trivial. We can ask for which imaginary quadratic fields K the corresponding elliptic curve with CM by OK is defined over Q. This is equivalent to asking to find all imaginary quadratic fields with trivial class group ClK. This problem is known as Gauss’ class number one problem, which was solved by Heegner in 1952 [16], Baker in 1967 [2], and Stark in 1967 [41]. The imaginary quadratic fields with trivial class group are the fields Q(V−d) with d E {3, 4, 7, 8, 11, 19, 43, 67, 163}. In the 1950’s, Shimura and Taniyama [39] generalized the first main theorem of CM for elliptic curves to abelian varieties. We say that an abelian variety A of dimension g has CM if the endomorphism ring of A contains an order of a CM field of degree 2g. Let K be a CM field of degree 2g with maximal order OK, and let K be a CM type of K. Let A be a polarized simple abelian variety over C of dimension g that has CM by OK. Then the first main theorem of CM says that the field of moduli M of the polarized simple abelian variety A gives an unramified class field H over the reflex field Kr of K. Moreover, the class field H corresponds to the ideal group I0(?r) (see page 17), which only depends on (K,?), see Theorem 1.5.6. Note that the first main theorem of CM implies that if the polarized abelian variety A is defined over Kr, then the CM class group IKr/I0(?r) is trivial. As in the elliptic curve case, we can ask for which CM pairs (K,?) the corresponding CM abelian varieties are defined over Kr. Equivalently, we can ask for which CM pairs (K,?) the CM class group IKr/I0(?r) is trivial. In this thesis we give an answer to this problem for quartic CM fields (see Chapter 2), and for sextic CM fields containing an imaginary quadratic field (see Chapter 3). Furthermore, we can ask for which CM fields the corresponding simple CM abelian varieties have field of moduli Q. Murabayashi and Umegak [31] determined the quartic CM fields that correspond to a simple CM abelian surface with field of moduli Q. In Chapter 4, we determine the sextic CM fields that correspond to a simple CM abelian threefold with field of moduli Q.
8

Common mode electromagnetic interference attenuation for DC/AC inverters using enhanced sinusoidal frequency modulation technique

Le, Dinh 10 May 2024 (has links) (PDF)
Common mode (CM) electromagnetic interference (EMI) can compromise electronics systems, interfere with communication systems, and degrade mechanical systems. Multiple inverters can also generate excessive CM EMI that often exceeds individual inverter EMI standards. Due to their weight, volume, cost, and suboptimal performance, active and passive filters and chokes are inefficient as EMI mitigation options. By utilizing frequency modulation (FM) or spread spectrum frequency modulation (SSFM), EMI energy is dispersed. In spite of not requiring expensive, bulky, and heavy filters, these techniques produce significant ripples in output voltages and currents. This dissertation uses enhanced sinusoidal frequency modulation to reduce CM EMI output, bridging the gap between existing EMI solutions: 1) To reduce performance degradation, a state-of-the-art FM topology with duty cycle correction is proposed. Due to large output voltage and current ripples, FM techniques have limited bandwidth and utilization. Duty cycle correction allows for a wider FM bandwidth with better EMI attenuation while minimizing output ripple performance tradeoffs. 2) CM EMI accumulation is a growing concern in power converter networks. Even if each converter complies with EMI regulations, multiple converters may produce CM EMI that exceeds EMI standards in parallel operation. A novel algorithm is proposed to suppress CM EMI in a large-scale network using SFMCW frequency indexing. The algorithm minimizes aggregate EMI by minimizing switching frequency overlap among converters. 3) CM EMI noise in complex systems presents a critical challenge. Since standalone converters are rarely affected by CM EMI phases, they were usually overlooked in most studies until recently. CM currents generated by multiple converters can be added or subtracted based on phase differences. The CM currents in large systems with multiple inverters are distributed randomly, resulting in multiple peaks and nulls. In order to reduce network EMI, a sinusoidal FM technique with phase shift is proposed to attenuate CM EMI on multiple parallel inverters. This method overcomes conventional methods' critical disadvantages, including the need for accurate component characterization and modeling, and reducing CM EMI without additional passive components.
9

Hydratation et évolution isotopique précoce des astéroïdes carbonés : approches expérimentale et isotopique / Early Hydration and Isotopic Evolution of Carbonaceous Asteroids : Experimental and Isotopic Approaches

Vacher, Lionel 09 November 2018 (has links)
Les astéroïdes carbonés ont été affectés par des processus d’altération aqueuse qui ont largement modifié leur minéralogie primaire au profit d’une grande diversité de phases néoformées. Malgré les nombreuses études conduites sur les chondrites hydratées (chondrites CM), la compréhension des processus physico-chimiques de l’altération aqueuse et les conditions d'hydratation des astéroïdes reste aujourd’hui encore très parcellaire. À partir de l’étude minéralogique et isotopique des phases secondaires, cette thèse a pour objectifs (i) de déchiffrer l’origine et l’évolution de l’eau accrétée par les astéroïdes primitifs et (ii) de retracer les conditions physico-chimiques de l’altération aqueuse grâce à des expériences hydrothermales en laboratoire. Tout d’abord, les résultats montrent que la chondrite CM Paris contient des carbonates de calcium dont la composition isotopique en oxygène ([delta]17,18O) implique l’incorporation de 8-35 % de glace d’eau originaire du Système Solaire externe. De plus, les analyses isotopiques en carbone, menées sur ces mêmes carbonates, indiquent que les valeurs en [delta]13C sont similaires à celles de la matière organique soluble (SOM) présente dans les chondrites carbonées. Ainsi, j’ai pu proposer que la SOM représente la source la plus probable de carbone pour former les carbonates. L’étude des différents clastes de la CM Boriskino a permis de mettre en évidence que cette météorite a subi des épisodes d’impacts de forte intensité, engendrant la formation de fractures et la circulation de fluides tardifs enrichis en 16O. Enfin, des expériences de laboratoire de basse température ont permis de synthétiser les phases d’altération les plus caractéristiques des chondrites CM : la tochilinite et la cronstedtite. Par ailleurs, en comparant ces résultats avec ceux obtenus par d’autres études expérimentales, une corrélation positive a été observée entre la quantité de Mg contenue dans la couche hydroxylée de la tochilinite synthétique et la température. Cette corrélation suggère que la composition chimique de la tochilinite peut servir de traceur pour remonter aux températures des processus d'altération aqueuse des chondrites CM / Carbonaceous asteroids were affected by aqueous alteration processes that have strongly modified their primary mineralogy in favour of a wide diversity of newly formed phases. Despite the numerous studies carried out on hydrated chondrites (CM chondrites), the physicochemical conditions of aqueous alteration and the identification of the water sources accreted by asteroids are still poorly constrain. From the mineralogical and isotopic survey of secondary phases, this thesis aims (i) to decipher the origin and evolution of water accreted by primitive asteroids and (ii) to retrace the physicochemical conditions of aqueous alteration using hydrothermal laboratory experiments. First of all, our results show that the pristine CM chondrite Paris contains Ca-carbonates whose O-isotopic compositions ([delta]17,18O) requires an 8-35% contribution of water ice from the outer part of the Solar System. In addition, our C-isotopic analyses conducted on these same Ca-carbonates indicate similar [delta]13C values to those of the soluble organic matter (SOM) that constitute carbonaceous chondrites. Thus, we suggest that SOM is the most probable source of carbon to form Ca-carbonates. Then, the study of different clasts in the CM chondrite Boriskino revealed that this meteorite has experienced high intensity impact events, causing the formation of fractures and the circulation of later 16O-rich fluid flow. Finally, our low temperature laboratory experiments successfully synthetized the most characteristic phases of CM chondrites: tochilinite and cronstedtite. Moreover, by comparing our results to other experimental studies, we observed a positive correlation between the nMg content in the hydroxide layer of synthetic tochilinite and temperature. This correlation suggests that the chemical composition of tochilinite represents as powerful proxy to retrace the alteration temperature experienced by CM chondrites
10

Vaikystės kaleidoskopas / Childhood kaleidoscope

Šlepetytė, Jonė 11 February 2012 (has links)
Šio baigiamojo darbo objektas yra „Vaikystės kaleidoskopas“. Paveikslai tapyti 2011m. Šiaulių Universitete menų fakultete. Tai šešių abstrakčių paveikslų ciklas - „Vaikystės kaleidoskopas“, 140x160 cm, drobė/aliejus. Tapybos darbų kolekcija atlikta tradicine tapybos technika, tačiau turi abstraktų charakterį. Tapybos kolekcija išsiskiria drąsiais tapybiniais spręndimais. Tapydama šiuos darbus, tarsi įprasminau savo vaikystės prisiminimų būseną: vaizdai kinta, mirga arba visai išnyksta kaip ir kaleidoskope. / The object of this graduation work is “Childhood kaleidoscope” – the pictures painted in 2011 at Šiauliai University’s Department of Arts. It is a cycle of six abstract paintings entitled “Childhood kaleidoscope”, 140x160 cm, canvas/oil. The collection of pictorial works has been rendered in traditional painting technique; however, it has abstract character. The painting collection is distinguished by brave pictorial solutions. While painting these works I tried to give a sense to the state of my childhood memories: the images vary, flicker or completely disappear like in a kaleidoscope.

Page generated in 0.0245 seconds