Spelling suggestions: "subject:"abreakout""
51 |
In-Situ Ethylene Polymerization with Organoclay-Supported Metallocenes for the Preparation of Polyethylene-Clay NanocompositesManeshi, Abolfazl January 2010 (has links)
In-situ polymerization is one of the most efficient methods for production of polymer clay nanocomposites. In-situ polymerization of olefins using coordination catalysts is a type of heterogeneous polymerization. In order to achieve acceptable clay nanolayer dispersion in the polyolefin matrix, the clay layer exfoliation and particle break up during the polymerization are essential requirements. A literature review on polyolefin/clay nanocomposite is given in Chapter 2.
In Chapter 3, we present a new mathematical model, which is as an extension of the multigrain model (MGM), to describe the intercalative polymerization and expansion of clay interlayer spaces during polymerization using clay-supported metallocenes. The results from the model show that, under the studied conditions, mass transfer is not a strong factor controlling clay exfoliation and particle break up. If the polymerization active sites are supported uniformly on all clay surfaces, effective exfoliation will be achieved after a relative short polymerization time.
In practice, obtaining good dispersion of clay nanolayers with uniform properties requires that the active sites be exclusively located on the clay nanolayer surfaces, and not extracted by the solvent to form a homogeneous solution. Factors favouring active site extraction would result in nanocomposites with poor properties. In addition, high polymerization activities, stable polymerization runs, and ease of supporting are other criteria for a successful in-situ polymerization. For this purpose we established a catalyst supporting method by which most of these requirements were met. In this method, the water content on the clay surface, which is considered as poison for the metallocene catalyst, was used to produce MAO upon reaction with trimethylaluminum (TMA). Using this method, polymerization was highly active in absence of MAO cocatalyst, knowing that MAO cocatalyst promotes active site extraction from the clay surface and results in poor powder morphology. Chapter 4 describes the development of this supporting methodology.
Chapter 4 also investigates the effect of the organic modification type existing on the clay surface on the success of catalyst supporting and in-situ polymerization. We found that using the proposed supporting procedure, only tertiary ammonium type modification enhanced the in-situ polymerization, whereas the quaternary ammonium worsened the catalyst supporting efficiency and led to catalyst with poor or no polymerization activity. It is suggested that, in addition to enhancing clay surface-organic solvent compatibility (which facilitates catalyst supporting), the tertiary ammonium cation reacts with the in-situ produced MAO and increases the stability of the cocatalyst bonded to the clay surface.
The effect of different polymerization conditions on the polymerization behavior and nanocomposite structural properties, such as catalyst loading during supporting, polymerization temperature and triisobutylaluminum (TIBA) concentration, were studied in Chapter 5. It was found that TIBA acts merely as scavenger. High polymerization activities were obtained with low Al/Zr ratios (Al from TIBA) and increased Al concentration decreased the polymerization activity and also the quality of powder morphology. Catalyst loading in the supporting step showed to have an important role in determining the final properties. The clay particles with higher catalyst loading resulted in better exfoliation and powder morphologies
The effect of solvent type during catalyst supporting and polymerization was studied in Chapter 6. It was shown that catalyst supporting in n-hexane resulted in polymerizations with higher activities and polymers with higher molecular weight were produced. Polymerization with catalyst supported in hexane showed different ethylene uptake profiles, suggesting different mechanism of exfoliation. It is suggested that using this catalyst, the clay is mostly exfoliated before polymerization started.
Similar to the original clay, the catalyst supporting efficiency on the organically modified clay was close to 100 percent. However, comparing the polymerization activities of these catalysts to those that were supported directly in the reactor just before the polymerization (in-reactor, or in-situ, supported catalysts) shows that a considerable fraction of the active sites are deactivated during the prolonged contact between catalyst and clay support surface. In Chapter 5, it was shown that the in-reactor supported catalyst had considerably higher polymerization activities, up to 40 percent of that of the homogeneous catalyst. Nanocomposites made with in-reactor supported catalysts had powder morphology and nanaolayer dispersion comparable to those made with clay-supported catalysts.
|
52 |
Desenvolvimento de modelo computacional de previsão de quebra de gotas em simulador de separação de óleo e água em um hidrociclone / Development of computational model of forecast of drops break in simulator of separation of oil and water in a hydrocycloneCleber de Almeida Corrêa Junior 27 March 2008 (has links)
Petróleo Brasileiro S.A. / O presente trabalho aborda aspectos sobre o tratamento de águas oleosas, através de hidrociclones, em uma planta de processamento primário de petróleo. Apresenta o hidrociclone, sua utilização pela indústria do petróleo e os fenômenos de escoamento que ocorrem no seu interior. A partir das equações da conservação de massa e da quantidade de movimento linear, fazendo-se diversas considerações simplificadoras, chega-se a uma equação diferencial para a função corrente que, após ser trabalhada, possibilita a obtenção do conjunto de equações utilizadas como modelo para o cálculo da eficiência de separação do hidrociclone. Estudam-se algumas causas que fazem com que uma gota se deforme ou quebre, em seguida observam-se quais dessas causas são aplicadas no caso do escoamento no interior do hidrociclone, e desenvolve-se um modelo simplificado para a representação do
fenômeno da quebra de gotas. Calcula-se uma nova eficiência de separação, levando-se em conta o fenômeno da quebra de gotas. Toda a modelagem computacional foi feita com a utilização do software MATLAB. / The present work approaches aspects of oily water treatment, by using hydrocyclones, in a petroleum primary processing plant. It shows the hydrocyclone, its utilization in the petroleum industry and the flow phenomena occurring within it. Starting from the mass
conservation and linear momentum conservation equations, assuming some hypothesis, one writes a differential equation for the stream function that, after some work, provides a set of
equations suited to use as a model for calculating the hydrocyclone separation efficiency. Some causes of the deforming and break-up of droplets are studied. Afterwards, it is investigated which of these causes apply to the flow inside of the hydrocyclone and, finally, a simple model representative of the droplet break-up phenomenon is developed. A new separation efficiency is calculated, considering the droplet break-up phenomenon. All the
computational modeling was done using software MATLAB.
|
53 |
Desenvolvimento de modelo computacional de previsão de quebra de gotas em simulador de separação de óleo e água em um hidrociclone / Development of computational model of forecast of drops break in simulator of separation of oil and water in a hydrocycloneCleber de Almeida Corrêa Junior 27 March 2008 (has links)
Petróleo Brasileiro S.A. / O presente trabalho aborda aspectos sobre o tratamento de águas oleosas, através de hidrociclones, em uma planta de processamento primário de petróleo. Apresenta o hidrociclone, sua utilização pela indústria do petróleo e os fenômenos de escoamento que ocorrem no seu interior. A partir das equações da conservação de massa e da quantidade de movimento linear, fazendo-se diversas considerações simplificadoras, chega-se a uma equação diferencial para a função corrente que, após ser trabalhada, possibilita a obtenção do conjunto de equações utilizadas como modelo para o cálculo da eficiência de separação do hidrociclone. Estudam-se algumas causas que fazem com que uma gota se deforme ou quebre, em seguida observam-se quais dessas causas são aplicadas no caso do escoamento no interior do hidrociclone, e desenvolve-se um modelo simplificado para a representação do
fenômeno da quebra de gotas. Calcula-se uma nova eficiência de separação, levando-se em conta o fenômeno da quebra de gotas. Toda a modelagem computacional foi feita com a utilização do software MATLAB. / The present work approaches aspects of oily water treatment, by using hydrocyclones, in a petroleum primary processing plant. It shows the hydrocyclone, its utilization in the petroleum industry and the flow phenomena occurring within it. Starting from the mass
conservation and linear momentum conservation equations, assuming some hypothesis, one writes a differential equation for the stream function that, after some work, provides a set of
equations suited to use as a model for calculating the hydrocyclone separation efficiency. Some causes of the deforming and break-up of droplets are studied. Afterwards, it is investigated which of these causes apply to the flow inside of the hydrocyclone and, finally, a simple model representative of the droplet break-up phenomenon is developed. A new separation efficiency is calculated, considering the droplet break-up phenomenon. All the
computational modeling was done using software MATLAB.
|
54 |
Sovereign bonds: odious debts and state successionCollette, Stephanie 27 April 2012 (has links)
Though sovereign debts are often viewed as risk-free assets, some extreme events may lead to the repudiation of these debts. A large literature has been devoted to the motivations of repayment and to the causes of default. The impact of wars, which may lead to the repudiation of sovereign debt, on sovereign bond prices has also been analyzed. However, the impact of other types of seldom occurring but dramatic events, which may lead to the repudiation of debts, on bond prices has been overlooked. My current research aims to analyze three of them: the repudiation of debts because of their alleged "odiousness", the introduction of common debt after a state's unification and the debt partition following the break-up of a country. Since the events under consideration don't happen frequently, the dissertation will rely on four historical examples: Cuba, Russia, Italy and Belgium. The time period considered is the 19th century. Based on a historical analysis and the set-up of an original database, this project determines the effects of these events on sovereign debt valorization, using an econometric approach.<p><p>The first part of the research estimates the risk premium required by investors to hold debts which could be denounced as odious. Bondholders could require a premium to compensate for the higher default risk due to the odious character of the debts. The paper quantifies the risk premium required by investors to hold debts which could be denounced as odious and it analyses the relation between the value of the government bond and extreme "odious debt" events. In order to identify if such a premium exists, I focus on a Cuban case study. Based on an original database of Cuban bonds, the paper reveals the existence of a risk premium of at least 200 basis points which penalises bonds issued by dictatorial regimes. The bond market "odious" shocks are provided by a Structural VAR analysis. In a second case study, my research analyses the Tsarist bonds of 1906 and the premium to hold despotic regime debt. The paper shows that the market required a premium despite the attempts made by the Russian government to present the loan as clean.<p><p>The second and third parts of my research look at the effects of state succession on the sovereign bonds market. They analyze respectively the two subsets of state succession: state unification and "country break-up". The second part of the dissertation provides an empirical study of sovereign debt integration and analyses the evolution of sovereign bond prices when several countries merge to become a "unified country" or when the probability of such an event exists. Based on an original database made of pre-unification and post-unification Italian bonds, the paper shows the impact of Italy's unification on the bonds. The analysis puts forward that prior to the unification in 1862, the bonds issued by the future parts of the kingdom reacted in an idiosyncratic way. Around the sovereign debt integration, the paper highlights a large risk increase for low-yield bonds. Using a break point analysis and a Dynamic Factor Model, the paper proves that until the late 1860's the financial market did not believe in Italy's Unification. The third part of my research analyzes the financial impact on state bonds of a country which faces a risk to break up. This paper provides an empirical analysis of the evolution of sovereign debt prices when a state breaks up, or when it faces such an event. Based on an original database of Dutch and Belgian bonds, this research shows the impact of Belgian independence in 1830 on the Belgium bonds. This article analyses two risk premiums which may affect the sovereign debt of a state: the first one is linked to the country break-up (or the probability that one may occur) and the second one is due to the instability experienced by the new country. This analysis puts forward a "country break-up" risk premium of 142 basis points. The role of the debt underwriter has also been highlighted in the case of Belgian independence. Financial markets required no "new country" risk premium for Belgian bonds which were underwritten by Rothschild, but the risk premium remained for the Belgian authorities. This was likely due to the role of Rothschild as underwriter whose reputation persuaded the market that the risk is low, but who charged a premium to the Belgian government for their services.<p> / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished
|
55 |
Hodnota přání dítěte v současné praxi opatrovnických řízení / The value of the Child's Wish in the Contemporary Pracities of the Proceedings Regardiny the Adjustment of Legal Relations towards Minor ChildrenBöhmová, Tereza January 2019 (has links)
This Diploma Thesis is focused on the issue of the value of a child's wish in the framework of the divorce/break-up settlement. In the theoretical part of this thesis, the child's status, its right to participate and the means of ensuring that in the mentioned framework are presented. In this thesis, the term child's wish is also discussed in the context of defending child's own interest. In the last chapter of the theoretical part, there is illustrated the suitable way how to interview a child. The aim of the practical part is to, through half-structured interviews with the professionals taking part in this process and an analysis of those interviews, answer the main research question: How do the professionals taking part in the divorce/break-up settlement perceive and deal with the child's wish in this process? The research part of this thesis is also focused on the possible space for change in the contemporary attitude towards children as participants of trials.
|
56 |
På liv och död i hemmets (o)trygga vrå : En kvalitativ litteraturstudie om mäns våld mot kvinnor i nära relationer ur ett inifrånperspektiv / On life and death in the home of (un)safety : A qualitative literature study on men's violence against women in intimate relationships fom an inside perspectiveEnglund, Sandra, Johansson, Julia January 2021 (has links)
Syftet med studien var att identifiera de faktorer i kvinnors utsatthet för våld av män i nära relationer som påverkar deras val och möjlighet att stanna i alternativt lämna en våldsam parrelation samt vilken inverkan och påverkan det sociala nätverket har på kvinnors beslut att stanna i alternativt lämna relationen. Genom kvalitativ innehållsanalys av fyra självbiografier skrivna av tidigare våldsutsatta kvinnor sammanställdes resultat, som tematiserades och analyserades med hjälp av teorierna och begreppen normaliseringsprocess, traumatisk bindning och uppbrottsprocess tillsammans med tidigare forskning. Resultatet visade att anledningar till att en våldsutsatt kvinna stannar i en våldsam parrelation är starka känslomässiga band, normalisering av våldet, beroende, psykisk nedbrytning, internalisering, rädsla samt hopp om förändring. Vad som gör att en våldsutsatt kvinna lämnar en våldsam parrelation är insikten om att det skulle vara ohållbart att stanna av olika anledningar samt rädsla för sitt eget eller annans liv. Uppbrottsprocessen kan förklaras likt en process i flera steg. Omgivningens stöd visade sig också ha stor betydelse i kvinnans val och möjlighet att kunna lämna relationen, dock är beslutet att lämna relationen tvunget att komma från kvinnan själv. Slutsatsen var därmed att kvinnor som utsätts för våld av män i nära relationer är en mycket utsatt grupp i samhället, relationen till männen är ofta komplex. För att bryta kvinnors isolering, som följd av våldsutsattheten, krävs insatser från omgivningen samt förändring på samhällelig nivå. / The purpose of the study was to identify the factors in women's exposure to violence by men in intimate relationships that affect their choice and ability to stay in or leave a violent relationship and what impact the social network has on women's decision to stay in or leave the relationship. Through qualitative content analysis of four autobiographies written by previously abused women, results were compiled, thematized and analysed using theories and concepts such as normalization process, traumatic bonding, and break-up process together with previous research. The results showed that reasons why an abused woman stays in a violent relationship are strong emotional bonds, normalization of violence, addiction, being mentally break down, internalization, fear and hope for change. What causes an abused woman to leave a violent relationship has turned out to be the realization that it would be unsustainable to stay for various reasons as well as fear for her own or someone else's life. The breaking process can be explained as a process in several steps. The social network had a great importance in the woman's choice and opportunity to be able to leave the relationship, however, the decision to leave had to come from the woman herself. The conclusion was thus that women who are exposed by men in intimate partner violence are a very vulnerable group in society, the relationship is often complex. Breaking women's isolation, as a result of domestic violence, requires efforts from the social network and change at the societal level.
|
57 |
Kvinnors uppbrotts-, läknings- och återhämtningsprocess från en våldsam relation : Utifrån sociologisk-feministisk teori och anknytningsteori / Women's Breakup, Healing and Recovery Process from an abusive relationshipAlke, Marlene, Khabout, Ili, Molin, Veronica January 2024 (has links)
Föreliggande kvalitativa intervjustudie bygger på intervjuer med åtta kvinnor som i förfluten tid levt i en relation med förekomst av våld. Syftet med studien var att belysa heteronormativa kvinnors upplevelser av vad de anser har varit skadligt och/eller hjälpsamt i samband med och efter uppbrottet från en våldsam relation. Studien syftade även till att utröna förekomsten av kunskap, stödinsatser, behov och utmaningar som ställts under läknings- och återhämtningsprocessen. Det krävs större bildning om våld i nära relation på alla samhällsnivåer för att få en förståelse för hur hjälpinsatser och bemötande av kvinnor och barn bäst bör tillämpas. Det råder även brist på studier utifrån kvinnors egna upplevelser och insikter kring våldets mekanismer. Många kvinnor drabbas årligen av våldets konsekvenser, där förekomst och utevaro av kunskap och förmåga till stödjande hjälpinsatser i samhället kommit att påverka alla led av kvinnors uppbrotts-, läknings- och återhämtningsprocess. / The present qualitative interview studies are based on interviews with eight women who in the past have lived in a relationship with the occurrence of violence. The aim of this study was to illustrate heteronormative women's experiences of what they consider having been harmful and/or helpful in connection with and after the breakup from a violent relationship. The study also aimed to determine the prevalence of knowledge, support, needs and challenges that have been posed during the healing and recovery process. There is a need for greater education about domestic violence at all levels of society to gain an understanding of how relief efforts and the treatment of women and children should best be applied. There is also a lack of studies based on women's own experiences and insights into the mechanisms of violence. Many women are affected annually by the consequences of violence, where the presence and absence of knowledge and the ability to provide supportive assistance in society has come to affect all stages of the women's break-up, healing, and recovery process.
|
58 |
Responsabilité civile et rupture du couple / Civil liability and the couple’s break-upDucrocq, Karine 16 December 2013 (has links)
Le contexte de la rupture du couple, qu’il soit marié, uni par un pacte civil de solidarité, fiancé ou en concubinage, est un moment propice à la lésion des intérêts de ses membres. La question de la réparation des préjudices subis surgit alors, et la tentation est grande d’en imputer la responsabilité à l’autre membre du couple, surtout s’il est à l’origine de la rupture. Le droit commun de la responsabilité civile délictuelle, fondé sur l’article 1382 du Code civil, est une voie empruntable par chacun pour obtenir réparation ; demeurait la question de son adaptation à la matière. L’analyse des décisions qui le mettent en application à un cas de rupture de couple révèle une tendance nette, celle de l’utilisation à titre de sanction d’un mécanisme en principe réparateur. Cette résistance jurisprudentielle au mouvement d’objectivation et à la neutralité croissante du législateur dans l’organisation des rapports de couple se devait d’être précisée et expliquée. La présente étude vérifie, d’abord, la réalité du phénomène : l’article 1382 du Code civil est utilisé comme peine privée, ce qui met en avant la fonction répressive de la responsabilité civile. Elle s’attache ensuite à déterminer les valeurs que le juge cherche à protéger par la mise en œuvre de cette sanction. Au-delà de la diversité des comportements sanctionnés, c’est le travail d’équilibre réalisé par le juge entre droit à réparation et liberté de rupture que la thèse vise à souligner / The context of a couple’s break-up, whether they are married, in a civil partnership, engaged or cohabiting, is conducive to prejudice the respective interests of either person in the couple. As the issue of compensation for damages emerges, the temptation is to blame the other person, especially when this one can be regarded as the cause of the break-up. An action can be brought on the basis of tort liability in the section 1382 of the French civil Code. The question of its implementation was still open. A detailed analysis of the case-law shows that this legal basis, which is supposed to award compensation, is actually used as a punishment. This resistance to the development of objectification and to the increasing legal neutrality in the organization of the couple’s relationships had to be clarified and explained. The first objective of the study was to grasp the reality of the phenomenon : tort liability is used as a “private penalty”, which highlights its repressive function. The second purpose was to determine the values that judges are trying to protect through this particular way of application of the law. Beyond the diversity of sanctioned behaviours, the thesis aims at bringing out the role of judges in finding a right way between the right to compensation and the freedom to break-up.
|
59 |
Photoaktivierung des p-Kerns Mo-92 am Bremsstrahlungsmessplatz von ELBEErhard, Martin Andreas 22 December 2010 (has links) (PDF)
Das Thema der Arbeit ist experimentelle Bestimmung der Ausbeute durch Photoaktivierung von Mo-92 mittels Bremsstrahlung des supraleitenden Elektronenlinearbeschleuniger ELBE im Forschungszentrum Dresden-Rossendorf. Mo-92 ist der p-Kern mit der größten Isotopenhäufigkeit und wird in astrophysikalischen Netzwerkrechnungen deutlich unterproduziert. Untersucht wurde dabei insbesondere der (gamma,p)- und (gamma,n)-Kanal, wobei für letzteren wegen der Halbwertszeit des Endkerns (Isomer) von 65 s eine Rohrpost verwendet wurde. Die Aktivierung erfolgte an zwei verschiedenen Bestrahlungsplätzen. Am Kernphysikmessplatz konnte die Photonenfluenz absolut mittels Kernresonanzfluoreszenz an B-11 bestimmt werden. Im Elektronenstrahlfänger wurde die Photodesintegrationsreaktion Au-197(gamma,n) zur Normierung verwendet. Die Endpunktsenergie wurde über den Deuteronenaufbruch durch Messung der Protonenspektren mit Si-Detektoren bestimmt. Die Ergebnisse wurden mit der integralen Ausbeute mit Hauser-Feshbach-Modellrechnungen verglichen. Parasitär konnte auch die Ausbeute der Aktivierung des in natürlichem Mo enthaltenen Isotops Mo-100 untersucht und mit früheren Photoneutronenexperimenten verglichen werden.
|
60 |
Photoaktivierung des p-Kerns Mo-92 am Bremsstrahlungsmessplatz von ELBEErhard, Martin Andreas 01 October 2013 (has links) (PDF)
Die kosmische Nukleosynthese 35 protonenreicher stabiler Nuklide zwischen Selen und Blei kann nicht durch Neutroneneinfangprozesse erklärt werden. Es wird angenommen, dass diese Kerne in explosiven Szenarien, wie Supernova-Explosionen durch Protoneneinfang oder Photodesintegrationsprozesse, erzeugt werden, jedoch sind die solaren Häufigkeiten dieser sogenannten p-Kerne noch nicht verstanden. Der p-Kern mit der größten Isotopenhäufigkeit, 92Mo, wird in Nukleosynthese-Netzwerkrechnungen deutlich unterproduziert.
Eine mögliche Ursache könnten unpräzise Reaktionswirkungsquerschnitte sein, da die meisten Wirkungsquerschnitte nur aus Modellrechnungen bekannt sind. Daher war es naheliegend, die Photodesintegrationswirkungsquerschnitte von 92Mo mit der Methode der Photoaktivierung an der Strahlungsquelle ELBE im Forschungszentrum Dresden-Rossendorf zu überprüfen.
Durch die hohe Intensität der Bremsstrahlung von bis zu 10^9 MeV^-1cm^-2s^-1 im Energiebereich bis zu 20 MeV konnten im Rahmen dieser Arbeit erstmals nicht nur die (γ,n)-, sondern auch die (γ,p)-Reaktionen an 92Mo bei astrophysikalisch relevanten Energien untersucht werden. Durch die Messungen an zwei Bestrahlungsplätzen konnten systematische Unsicherheiten reduziert werden. Insbesondere wurde eine präzise Bestimmung der Photonenfluenz vorgenommen: Am Kernphysikmessplatz erfolgte die Bestimmung mittels Kernresonanzfluoreszenz an 11B. Im Elektronenstrahlfänger wurde die Photodesintegrationsreaktion 197Au(γ,n) zur Normierung der Photonenfluenz verwendet, nachdem sie zuvor am Kernphysikmessplatz überprüft wurde.
Die Reaktion 92Mo(γ,n)91mMo, mit einer Halbwertszeit des Endkerns von 65 s, war dank einer Rohrpost zugänglich, mit der die Proben in weniger als 10 s von der Bestrahlungsstation zum Zerfallsmessplatz transportiert werden können. Die Messungen dieser Arbeit bestätigen im wesentlichen die Hauser-Feshbach-Modellrechnungen bezüglich der Photodesintegrationsreaktionen (γ,n) und (γ,p). Die Unterproduktion der Mo- und Ru-Isotope ist daher nicht erklärbar durch ungenaue Wirkungsquerschnitte. Zur Nukleosynthese dieser Kerne müssen andere astrophysikalische Prozesse, z.B. neutrinoinduzierte Reaktionen beitragen.
Die gemessenen Photoaktivierungsausbeuten haben eine hohe Empfindlichkeit auf die Photonenstärkefunktion. ÄAnderungen der Dipolriesenresonanzparameter wirken sich stärker auf berechnete Ausbeuten aus, als ÄAnderungen der Kernniveaudichte oder der Parameter des optischen Modells. Durch gleichzeitige Messung der Photodesintegration am Kern 100Mo konnten Unsicherheiten in der Normierung von Photoneutronenexperimentdaten aus der Positronenannihilation im Flug geklärt werden.
|
Page generated in 0.0252 seconds