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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.
121

Influence of flame retardant additives on the processing characteristics and physical properties of ABS

Seddon, Richard January 2000 (has links)
Antimony trioxide (Sb203) and halogenated additives are used together in flameretarded formulations due to their synergistic retardant properties. A study has been made to determine the effects of adding different grades of Sb203 (dSD particle sizes 0.11 um, 0.52um and 1.31 um) into ABS polymer either alone or with commercial brominated materials (BTBPE, TBBA, DBDPO) and an experimental bromine grade (sDBDPO). The Sb20 3 was added at 4wt% loadings and the bromines at 20wt% loadings. The results consider the influence of the additives on processing, mechanical, morphological and flame retardant properties. All compounds were produced using a twin-screw co-rotating extruder and then an injection moulder was used to mould notched impact (falling weight testing), flexural, LOI and UL-94 flame test bars. Samples of all the compounded formulations were titrated to determine Sb20 3 and Br contents. Fracture surface, morphology, size and dispersion analysis was carried out using both SEM and TEM equipment. Osmium tetroxide (OS04) staining was used to determine relative locations of filler particles and polybutadiene phase. Additions of the different antimony trioxide grades showed that the 0.52um and 1.31 um grades lowered impact energy absorption (-25 to -30%) when added at 4wt% loading. The use of a sub-micron size grade (0.1 um) did not significantly lower impact properties (-3%) and had similarly small effects on the flexural modulus and flexural strength. Additions of the brominated materials had much greater effects causing large reductions in impact properties (-20 to :70%). The presence of the bromines generally increased flexural modulus and lowered flexural strength with the exception of TB BA, which increased both modulus and strength. Compounds containing both 1.31 um Sb203 and bromines suffered a further reduction in impact energies, with the bromine properties dominating. Using the 0.1 um Sb20 3 grade again improved impact and flexural properties compared to the 1.31 um grade. The 0.1 um grade resulted in improvements in fire resistance as measured by the UL-94 properties when used with all bromine grades.
122

隨機違約強度模型下CDO之評價與分析-Copula方法

蔡麗君 Unknown Date (has links)
資產證券化一詞源自1970年代,而第一筆資產基礎證券的發行則始於1986 年。由於其具有自資本市場直接融資、降低籌資成本、分散籌資來源、提高資本適足率等誘因之下,逐漸受到銀行以及其他企業的重視,並發展成為固定收益證券市場中比重相當大的一環。擔保債權證券交易自1988年出現在美國,然後在歐美迅速發展,目前已成為重要債券市場之一。台灣金融產業發展正值轉型期,銀行除面對低利率帶來經營壓力之外,同時亦需規避評等較差之企業貸款的信用風險,而保險業者在低利率時代來臨卻無良好報酬之投資標的可供投資。因此,此環境乃為推動證券化之良好契機。自1997年發生東南亞金融危機,乃至1998年韓國的亞洲金融危機,造成許多跨國企業紛紛裁員、關廠、甚至倒閉,造成一連串的金融危機連鎖效應。因此,公司間或產業間之榮枯是相互關聯的,且均會受總體經濟因素所影響。是以,近年來信用風險亦成為近年來財務領域上重要議題。理論或實證上,當多個標的資產之信用衍生性商品被加以開發,並用來管理信用風險的時候,需考慮多個標的資產間的違約相關性,方能準確地衡量信用風險。故在信用風險管理與信用衍生性商品的評價中,違約相關性的估計與考量顯得格外重要。結構式或縮減式模型在發展違約相關性的多變數模型中是困難的,因為其衍生性商品價值的理論推導繁複或其數值計算是相當費時。本研究是假設隨機違約強度模式下,並在多標的資產之信用風險評價模型中,透過適當個別資產之邊際違約機率與Copula函數之選擇,及其相關參數之估算,即可快速求算具違約相關性之多變數聯合機率函數,以利擔保債權證券(CDO)之評價,並模擬出未來可能損失分配,進行主次順位架構下不同分券比例的敏感度分析,以瞭解不同的次順位劃分比例對於各順位分券風險值的影響程度為何。另外,隨著國內目前證券化腳步的發展,在未來證券化商品勢必成為市場上的主流商品之一,將來可供證券化的資產種類勢必也會增加。因此,為了提高投資人對於不同資產種類的投資信心,以方便發行人對於證券化商品的銷售,信用增強機制在證券化中所佔的地位也將更形重要。在這樣的情況下,評估標的資產可能的違約損失,以決定信用增強的比例該為多少,對於發行人而言也將會是一項重要的課題。因此本文針對Copula方法與分析架構做一剖析,再以國內第一檔公募之擔保債權證券-法國里昂信貸銀行企業貸款為例,進行模擬實證並分析結果。 本研究結論如下:在信用風險管理與信用衍生性商品評價中,違約相關性是ㄧ個重要的因子。此外,本研究發現違約回收率、標的資產間的相關係數以及違約機率等三者均會影響分券信用價差的評價:就權益分券而言,信用價差與相關係數是呈反比的,而次償分券表現出來也與權益分券大致相同,相對於權益分券與次償分券,先償分券之信用價差則與債權群組內標的資產間的相關係數則是呈正比的。實證結果亦顯示,承購風險性較高的分券其估算出的合理的風險溢酬也較高,此外,當違約回收率愈高時,債務人違約後的損失愈低,因此發行者需給予證券投資人的合理風險溢酬也愈低。另外,債務人的信用評等高低影響違約機率的大小,其亦是影響CDO商品合理溢酬高低的主要關鍵。再者,假使忽略債務人之間的違約相關性時,則各分券所估算出來的合理溢酬均會有所偏誤。因此,此結果隱含,評價CDO商品之合理溢酬時,需考慮債權群組內資產間的違約相關性,亦即投資人所面對風險除分券本身的信用風險外,還需考慮到債權人違約相關之風險,違約相關性愈高則投資者所面對的風險也較高。另外,介於先償分券與權益分券之間的次償債之信用價差,其信用價差大小大致上約介於先償分券與權益分券之間,而預期損失金額則是受到各順位分券比例大小不同,而有所差異。因此,將再進行主次順位架構下不同分券比例的敏感度分析,結果顯示若次順位債權分券(即權益分券)比例愈高,愈有信用增強之作用。 最後,若將本研究所估算出來分券的合理溢酬與實際CDO契約所載明計算出的結果相比較,其間差異並不大。因此本研究所建構的評價模型應能提供發行者與市場投資人一個評價基礎,不失為一種可行方法。
123

Simulador extensível para navegação de agentes baseado em inteligência de enxames / Extensible simulator for agent navigation based on swarm intelligence

Danilo Nogueira Costa 25 April 2007 (has links)
A visão de muitas pessoas sobre uma colônia de formigas, em geral, é de que estes pequenos e inofensivos insetos somente se movem aleatoriamente para coletar alimento e conservá-los em seus ninhos. Um olhar destreinado não conseguiria notar o nível de complexidade e organização que é requerido por uma colônia de formigas para sua sobrevivência. Uma formiga simples é parte de um grande grupo que coopera entre si para criar um superorganismo. Sem uma autoridade central ou indivíduos com habilidade de um pensamento cognitivo complexo, a colônia se auto-organiza, e, de fato, ajusta seus recursos de uma maneira muito eficiente. Essa dissertação investiga o papel da comunicação indireta nas tarefas de exploração e forrageamento, e como isso afeta as decisões de um agente simples e traz um comportamento emergente útil à toda colônia. Por fim, este trabalho implementa uma plataforma de simulação multi-agente inspirado em formigas / Most people\'s view of an ant colony and ants in general is that they simply pose harmless little insects that move randomly and gather food in their underground nests. The untrained eye would have never guessed the level of complexity and organisation that is required in order for an ant colony to survive. The simple ant is a part of a huge group, which cooperate one superorganism. Without any central authority or the ability of complex cognitive thought from the individuals, the colony seems to self organise and in fact adjust its resources in a quite efficient way. This dissertation investigates the role of indirect communication in the exploration and forage task and how it affects the decisions of the single agent and brings an emergent behaviour that is useful to all the colony. Finally this work implements an ant inspired multi-agent simulation plataform
124

Spojování 3D FDM tištěných dílů z ABS / Bonding of 3D FDM printed parts from ABS

Halabrín, Marek January 2021 (has links)
The thesis focuses on comparisons of usability of distinct types of glues to attach specimens. The specimens were glued using 4 types of glue: BISON Power Adhesive, BISON Epoxy Universal, PATTEX Repair Epoxy 5 min and a mixture of acetone with diluted ABS plastic as the last. The specimens underwent tensile and impact tests. For the tensile test, the specimens were made in 3 variants: blunt frontal joint, bevelled joint and gradually folded joint. For the impact test, the specimens were made in the form of a rod with a V-shaped notch. All variants of the joints consisted of 5 specimens with 3 unglued specimens for reference. The testing was conducted on the ZD 10/90 tensile strength machine and a Charpy impact test machine from the WPM company. The thesis contains technical-economic evaluation of the results of the tests with comparisons of the individual glues and forms.
125

Povrchové změny v závislosti na parametrech FDM tisku / Surface changes based on FDM printing parameters

Čada, Jiří January 2016 (has links)
This thesis deals with a construction of modified RepRap 3D printer Rebel II which operates with Fused Deposition Modeling technology and selection of suitable criterion for printing. It mainly focuses on the temperature of the material being printed and speed of printing for three selected materials. Materials were selected based on availability in the market and their application. An experiment, focusing on surface changes of products as well as on the look of a fibre after passing through a nozzle, was performed.
126

L’EMDR dans l’évolution de la prise en charge du TSPT : psychothérapie de la dissociation par les Stimulations Bilatérales Alternées Auditives / EMDR in the evolution of the treatment of PTSD : Psychotherapy of a dissociation by auditory alternated bilateral

Viard, Florent 08 December 2018 (has links)
Contexte scientifique : Les Stimulations Bilatérales Alternées (SBA) sont des techniques portant sur les modalités visuelles, tactiles ou auditives utilisées dans la psychothérapie EMDR « Eyes Movement Desensitization And Reprocessing ». Les recherches isolant les SBA portent souvent sur la modalité visuelle et relatent son effet sur la perturbation subjective à partir de la diminution de l'activité végétative observée. Or certains TSPT ne présentent pas d'activité végétative marquée, ceci corrélativement à la présence de dissociation (Choi et al., 2017; Sack, Cillien, & Hopper, 2012; Briere, Weathers, & Runtz, 2005) Aussi, peu d'études sont consacrées aux SBA auditives sauf pour signaler leur effet moindre comparativement aux autres modalités (Van Den Hout et al, 2012). Par ailleurs, le lien entre les SBA auditives et la dissociation n'a jamais fait l'objet de publication.Problématique : Quel est l'effet des SBA auditives sur l'intensité des signes de dissociation et de perturbation liées à un événement ?Méthode : Après avoir défini la dissociation comme un processus de perception du vécu subjectif qui échappe à la conscience, nous utilisons une méthode expérimentale incluant 40 participants volontaires pour offrir un argument en faveur de l’intérêt des SBA auditives dans le traitement de la dissociation. L'étude comprend 40 participants sains ayant une activité végétative stable pendant le rappel d'un souvenir inquiétant. Les sujets sont distribués au hasard pour la phase de traitement au cours de laquelle ils se rappellent l'événement simultanément à des SBA auditives (n = 20) ou sans SBA auditive (n = 20). L'intensité des signes de dissociation et de perturbation est mesurée en pré-traitement et post-traitement à partir des scores moyens dans le questionnaire RSDI «Response to script Driven imagerie» (Hopper et al, 2007). Résultats : Pour la dissociation, il y a une interaction significative entre les variables Groupe et Moment, F(1, 38) = 5.25, p= .03. Avec SBA auditives, on observe une différence des scores en pré et post traitement significative V = 134, n = 20, p = .03 ; dans le sens d'une diminution. Pour la perturbation subjective, il n'y a pas d'interaction significative entre les variables et la différence des scores n'est pas significative.Discussion : la technique SBA auditive diminue l'intensité des signes de dissociation. Cela ne génère pas forcément un vécu subjectif perturbant. Ces résultats préliminaires ouvrent un champ de recherche sur la psychopathologie dissociative et des SBA auditives. À partir des travaux de Stanislas Dehaene sur « l’espace de travail neuronal global » et la conscience, nous proposons un nouveau modèle théorique de l’action des SBA en intégrant ses effets sur la dissociation. À terme, des recommandations méthodologiques sont envisagées. / Scientific background: The alternate bilateral stimulations (ABS) are techniques relating to the visual, tactile or aural modalities used in the psychotherapy EMDR "Eyes Movement Desensitization And reprocessing". Insulating research the SBA often focus on visual modality and relate its effect on subjective disturbance from the decline in observed vegetative activity. However, some PTSD do not exhibit marked vegetative activity, this correlatively with the presence of dissociation (Choi et al., 2017; Sack, Cillien, & Hopper, 2012; Briere, Weathers, & Runtz, 2005) Also, few studies are devoted to auditory ABS except to indicate their lesser effect compared to other modalities (Van Den Hout et al, 2012). On the other hand, the link between the auditory ABS and the dissociation has never been the subject of publication.Problem: What is the effect of auditory ABS on the intensity of event-related dissociation and disturbance signs?Method : After defining dissociation as a process of perception of subjective experience that escapes consciousness, we use an experimental method including 40 voluntary participants to offer an argument in favor of the interest of the auditory ABS in the treatment of dissociation. The study includes 40 healthy participants with stable vegetative activity during the recall of a disturbing memory. The subjects are randomly distributed for the treatment phase during which they recall the event simultaneously to auditory SBA (n = 20) or without hearing SBA (n = 20). The intensity of the signs of dissociation and disturbance is measured in pre-treatment and post-treatment from the average scores in the questionnaire RSDI "Response to script Driven imaging" (Hopper and LA, 2007). Results : For dissociation, there is a significant interaction between the variables group and Moment, F (1, 38) = 5.25, p =. 03. With SBA auditory, there is a difference in pre-and post-treatment scores of significant V = 134, n = 20, p =. 03; In the sense of a decrease. For subjective disturbance, there is no significant interaction between the variables and the difference in scores is not significant.DISCUSSION : The auditory technique reduces the intensity of the dissociation signs. This does not necessarily generate a disturbing subjective experience. These preliminary results open a field of research on dissociative psychopathology and of auditory ABS. Based on the work of Stanislas Dehaene on the "Global Neural work space" and consciousness, we propose a new theoretical model of ABS action by integrating its effects on dissociation. Methodological recommendations are envisaged.
127

[pt] ANÁLISE DE EFICIÊNCIA E CONTROLE DE UM SISTEMA INTEGRADO RODA-MOTOR ELÉTRICO / [en] EFFICIENCY ANALYSIS AND CONTROL OF AN INTEGRATED IN-WHEEL ELECTRIC MOTOR

DANIEL ZACARIAS FREITAS 12 May 2016 (has links)
[pt] Esta dissertação apresenta o estudo para o desenvolvimento de um powertrain elétrico com motorização independente na massa não suspensa do veículo, acoplado diretamente nas rodas In Wheel ou Hub-Motor . O desenvolvimento do sistema proposto visa à maximização da eficiência dos veículos elétricos pela minimização das perdas relacionadas a sistemas mecânicos, como na transmissão convencional utilizada em veículos com motorização única. Outro fator motivador para o desenvolvimento do powertrain com motorização independente é a aplicação de controles independentes para cada roda, possibilitando desenvolver e aplicar uma gama de controles no veículo, os quais com a motorização única não são possíveis ou possuem desempenho não satisfatório. O trabalho apresenta uma visão geral sobre os veículos elétricos, o estudo do comportamento dinâmico vertical com o aumento da massa não suspensa do veículo, desenvolvimento de um controle de velocidade para o powertrain proposto, desenvolvimento de um controle de frenagem ABS elétrico, simulação do sistema em ciclos de direção com o cálculo da eficiência energética do powertrain, e um experimento em um dinamômetro de bancada para validação da eficiência energética dos ciclos simulados. / [en] This paper presents a study for the development of an electric powertrain with independent engines in the vehicle mass not suspended, directly coupled to the wheels In Wheel or Hub-Motor . The development of the proposed system aims at maximizing the efficiency of electric vehicles by minimizing losses related to mechanical systems, as in conventional transmission used in vehicles with single engine. Another motivating factor for the development of powertrain with independent engines is the application of independent controls for each wheel, allowing for the development and application of a range of controls in the vehicle, which would not be possible or would have unsatisfactory performance if a single engine was used. This work presents an overview of electric vehicles, the study of the dynamic vertical behavior with increasing mass of the suspended vehicle, development of a speed control for the proposed powertrain, development of an electric ABS braking control, system simulation toward cycles to calculate the energy efficiency of the powertrain, and an experiment on a bench dynamometer to validate the energy efficiency of simulated cycles.
128

Prototype for automotive roll over safety system

Tevetzidis, Ilias January 2020 (has links)
This thesis presents the theory, methodology and results of building, tuning and testing a prototype for controlling body roll movement. Body roll is a result of lateral acceleration that acts on a vehicle when turning and result in torque on the roll center of the vehicle. The objective of this thesis is, in collaboration with Freno Air AB [7], to build a prototype and, with the help of sensors and micro controllers, restrict the body roll to avoid roll over on a semi-trailer that the company builds. The control unit in this thesis includes two PID controllers that is vastly used today in many different applications. The control unit is fed with signals from two pressure sensors on each side of the prototype frame. The pressures are given by four syringes, two on each side that are connected to the pressure sensors. One PID has small gains of KP = 0.2, KD = 0.005 and KI = 0 to take care of smaller and slower variations of pressure difference and one PID with higher gains of KP = 1, KD = 1 and KI = 0 to take care of faster and bigger variations in pressure difference which in both of the cases the pressure difference translates to body roll. The pressures give is enough of information of the prototypes state to be able to control it with the help of a motion platform that is able to roll in opposite direction to equalize the pressures. The results for the two cases of slow roll and fast roll are promising with a fast response, few oscillations and overshoots, which makes the system fast and stable, two things that are opposites in the world of closed loop control. The experiment was performed in a stationary form with applied disturbances and actuated with a motion platform capable of roll rotation.
129

Biometrics in the World of Electronic Borders

Kumi Kyeremeh, George, Abdul-Al, Mohamed, Abduljabbar, Nabeel, Qahwaji, Rami S.R., Abd-Alhameed, Raed 06 December 2021 (has links)
Yes / Recently, the demand for border crossing has increased massively, with the aim to increase the processing and clearance speed at border crossing points (BCP). The attempt to improve travel convenience, Border Cross Point (BCP) output, and national security result in automated border control (ABC) with biometric technology having a major effect on the efficiency, and safety of the control processes. The border processing of BCP can be increased by automating biometric recognition and facilitated by clearance procedures. This paper discussed the two structures of an e-gate (ABC) and a prospective benefit of biometrics to the EU border in terms of accuracy, integrity, robustness, and efficiency. Challenges posed by biometrics in border control systems were identified and recommendations such as multimodal systems and smart systems with AI and machine learning were suggested to assist travelers to cross border points faster. / e European Union’s Horizon-MSCA-RISE-2019-2023, Marie Skłodowska-Curie, Research, and Innovation Staff Exchange (RISE), titled: Secure and Wireless Multimodal Biometric Scanning Device for Passenger Verification Targeting Land and Sea Border Control
130

Une méthodologie de modélisation par processus multiples et incrémentiels : application pour l'évaluation des performances de la Supply Chain

Féniès, Pierre 05 December 2006 (has links) (PDF)
L'étude de la littérature montre que l'aide à la décision pour la Supply Chain (SC) ignore l'évaluation des flux financiers. Cette thèse propose une approche transdisciplinaire permettant l'évaluation des flux physiques et financiers de la SC. Nous proposons une méthodologie de modélisation par processus multiples et incrémentiels ainsi qu'un environnement de modélisation qui ont pour but d'évaluer flux physiques et financiers d'une SC. L'évaluation de la performance est réalisée par un modèle générique décisionnel combinant modèles du contrôle de gestion et couplages de modèles de simulation et d'optimisation. La mise en oeuvre de ces modèles se matérialise par une suite logicielle appelé Advanced Budgeting and Schedeling (ABS) qui constitue, par l'intégration des flux financiers dans l'aide à la décision, une évolution dans les logiciels pour la SC. Nous concevons deux ABS, l'un pour une SC industrielle d'une multinationale, l'autre pour la SC du Nouvel Hôpital d'Estain.

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