Dissertations / Theses on the topic 'Coupler strength'

Дисертація на здобуття наукового ступеня кандидата технічних наук (доктора філософії) за спеціальністю 05.17.11 "Технологія тугоплавких неметалічних матеріалів". – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017. Дисертацію присвячено розробці безпігментних одношарових хімічно та термічно стійких темнозабарвлених склоемалевих покриттів для захисту побутової техніки, зокрема кухонних газових та електричних плит, що отримуються за технологією POESTA. Синтезовано основи отримання покриттів вказаного типу, згідно із якими розробляється скломатриця із заданими фізико-хімічними властивостями, на основі якої отримується склоемалева фрита шляхом введення в оптимізований склад скла комплексного активатору зчеплення, одночасно виконуючий роль активного забарвлюючого комплексу, який поєднує задані міцнісні характеристики безпігментних одношарових темнозабарвлених склоемалевих покриттів. Встановлено межі значень структурних факторів, які забезпечують міцну структуру кремнекисневого каркасу скла в системі R₂O (Na₂O+K₂O+Li₂O) – RO (CaO+BaO+SrO+MgO) – TiO₂ – ZrO₂ – B₂O₃ – SiO₂ і заданий рівень її структурнозалежних експлуатаційних властивостей за рахунок встановлених співвідношень склоутворювачів і модифікаторів. Розроблено склад і співвідношення комплексного активатора зчеплення із урахуванням його впливу на характеристики міцності системи "склоемаль – сталь", корозійну здатність склорозплаву та експлуатаційні властивості покриттів, який одночасно виконує роль активного забарвлюючого комплексу. Обрано іонний механізм забарвлення та встановлено колірні координати в ККС XYZ, RGB, L*a*b. Проведено промислові та лабораторно-промислові випробування на підприємствах та розроблено практичні рекомендації щодо використання результатів.
The dissertation on competion of a scientific degree of the candidate of engineering science on a speciality 05.17.11 "Technology of refractory nonmetallic materials". – National Technical University "Kharkiv Polytechnical Institute", Kharkiv, 2017. The dissertation is devoted to the development of pigments free direct chemically and thermally resistant dark-colored glass-enamel coatings for the protection of household appliances, in particular kitchen gas and electric plates, obtained by the technology POESTA. The bases of obtaining the coatings of this type are synthesized, according to which the glass matrix is developed with the given physicochemical properties, on the basis of which glassmelee frit is obtained by introducing into the optimized composition of the MS complex agglomer activator, simultaneously performing the role of the active coloring complex which combines the specified strength characteristics of pigments free direct glass-enamel coatings with their dark coloring. The boundaries of the values of structural factors, which provide a solid structure of the silica-oxygen glass frame in the system R₂O (Na₂O+K₂O+Li₂O) – RO (CaO+BaO+SrO+MgO) – TiO₂ – ZrO₂ – B₂O₃ – SiO₂ and the specified level of its structurally dependent performance properties due to the established ratios of glass modifiers and modifiers. The composition and ratio of the complex coupler activator have been developed taking into account its influence on the strength characteristics of the glass-enamel-steel system, the corrosion capacity of the glass-fiber alloy and the operational properties of the coatings at the firing temperatures of 800 to 830 °C. Selected the ionic mechanism of color, which was realized by the components of the filling station, and the color coordinates are established in the XYZ, RGB, L*a*b, according to RAL. Industrial and laboratory-industrial tests were carried and practical recommendations for the use of development results are developed.

Дисертація на здобуття наукового ступеня кандидата технічних наук (доктора філософії) за спеціальністю 05.17.11 "Технологія тугоплавких неметалічних матеріалів". – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017. Дисертацію присвячено розробці безпігментних одношарових хімічно та термічно стійких темнозабарвлених склоемалевих покриттів для захисту побутової техніки, зокрема кухонних газових та електричних плит, що отримуються за технологією POESTA. Синтезовано основи отримання покриттів вказаного типу, згідно із якими розробляється скломатриця із заданими фізико-хімічними властивостями, на основі якої отримується склоемалева фрита шляхом введення в оптимізований склад скла комплексного активатору зчеплення, одночасно виконуючий роль активного забарвлюючого комплексу, який поєднує задані міцнісні характеристики безпігментних одношарових темнозабарвлених склоемалевих покриттів. Встановлено межі значень структурних факторів, які забезпечують міцну структуру кремнекисневого каркасу скла в системі R₂O (Na₂O+K₂O+Li₂O) – RO (CaO+BaO+SrO+MgO) – TiO₂ – ZrO₂ – B₂O₃ – SiO₂ і заданий рівень її структурнозалежних експлуатаційних властивостей за рахунок встановлених співвідношень склоутворювачів і модифікаторів. Розроблено склад і співвідношення комплексного активатора зчеплення із урахуванням його впливу на характеристики міцності системи "склоемаль – сталь", корозійну здатність склорозплаву та експлуатаційні властивості покриттів, який одночасно виконує роль активного забарвлюючого комплексу. Обрано іонний механізм забарвлення та встановлено колірні координати в ККС XYZ, RGB, L*a*b. Проведено промислові та лабораторно-промислові випробування на підприємствах та розроблено практичні рекомендації щодо використання результатів.
The dissertation on competion of a scientific degree of the candidate of engineering science on a speciality 05.17.11 "Technology of refractory nonmetallic materials". – National Technical University "Kharkiv Polytechnical Institute", Kharkiv, 2017. The dissertation is devoted to the development of pigments free direct chemically and thermally resistant dark-colored glass-enamel coatings for the protection of household appliances, in particular kitchen gas and electric plates, obtained by the technology POESTA. The bases of obtaining the coatings of this type are synthesized, according to which the glass matrix is developed with the given physicochemical properties, on the basis of which glassmelee frit is obtained by introducing into the optimized composition of the MS complex agglomer activator, simultaneously performing the role of the active coloring complex which combines the specified strength characteristics of pigments free direct glass-enamel coatings with their dark coloring. The boundaries of the values of structural factors, which provide a solid structure of the silica-oxygen glass frame in the system R₂O (Na₂O+K₂O+Li₂O) – RO (CaO+BaO+SrO+MgO) – TiO₂ – ZrO₂ – B₂O₃ – SiO₂ and the specified level of its structurally dependent performance properties due to the established ratios of glass modifiers and modifiers. The composition and ratio of the complex coupler activator have been developed taking into account its influence on the strength characteristics of the glass-enamel-steel system, the corrosion capacity of the glass-fiber alloy and the operational properties of the coatings at the firing temperatures of 800 to 830 °C. Selected the ionic mechanism of color, which was realized by the components of the filling station, and the color coordinates are established in the XYZ, RGB, L*a*b, according to RAL. Industrial and laboratory-industrial tests were carried and practical recommendations for the use of development results are developed.

This study is a two part study of the experiences of women participating in conjoint treatment for domestic violence. The participants in the first part of the study included 11 clients, from whom information was gathered in 25 interviews. The second part of the study focused on three women. Their opinions were garnered in five interviews. Five of the women were in multi-couple group therapy and nine participated in from four to twelve sessions of conjoint couple therapy with their partners. This study focused on how female partners of male batterers experienced strength-based focused couples therapy as part of a research and development project for couples treatment of domestic violence. The concepts of safety, responsibility for the violence, power and control, validation and empowerment guided the researcher. The women related that having two therapists and pre- and post-session check-ins contributed to their sense of safety. Although the women reported that their mate taking responsibility for the violence was important, they thought the therapy's focus on their strengths kept their mates committed to attending therapy sessions. Women, who reported that their mates were taking more responsibility for their actions, attributed the change to their therapists being persistent in discussing the various forms of abusive behavior and in stressing accountability for individual behavior. Most of the women indicated that talking about what they had experienced and that gaining support from therapists and group members increased their power and ability to focus on their own needs. Women in the study stressed the importance of having some form of follow-up support to be able to practicing new skills with their partners. Based on the recommendations of the women in this study, the treatment of domestic violence should provide women safe outlets for expressing their feelings, acknowledgment of their experience and tools for resolving the conflicts in their relationship.
Master of Science

This research is about modelling and simulation of how the hydrogen diffuses in high strength steels. The hydrogen diffusion in the material was examined by using finite element software with the help of material properties and some existing data. For modelling and simulating the diffusion analysis in finite element software, a cylindrical type dog-bone shaped specimen was chosen. To determine the diffusion at the centre of specimen, a cross-sectional area of the material was selected to proceed for the analysis. Abaqus software was considered as finite element software to progress the hydrogen diffusion and tensile testing of the specimen. Diffusion analysis was studied under the analogy of heat transfer and also, diffusion analysis with the addition of mechanical load was studied under the analogy of coupled temperature displacement in the Abaqus software. This process has executed for two types of high strength steels 316L and 304L stainless steels. The crack is also considered for analysis to check how it affects the specimen. Further, The 316L and 304L stainless steel results were compared to review that which steel is better to withstand the hydrogen diffusion rate and mechanical load on the material.

This thesis presents a systematic numerical modeling framework to simulate the stress-deformation and coupled stress-deformation-flow processes by performing uniaxial and biaxial compressive tests on fractured rock models with considering the effects of different loading conditions, different loading directions (anisotropy), and coupled hydro-mechanical processes for evaluating strength and deformability behavior of fractured rocks. By using code UDEC of discrete element method (DEM), a series of numerical experiments were conducted on discrete fracture network models (DFN) at an established representative elementary volume (REV), based on realistic geometrical and mechanical data of fracture systems from field mapping at Sellafield, UK. The results were used to estimate the equivalent Young’s modulus and Poisson’s ratio and to fit the Mohr-Coulomb and Hoek-Brown failure criteria, represented by equivalent material properties defining these two criteria. The results demonstrate that strength and deformation parameters of fractured rocks are dependent on confining pressures, loading directions, water pressure, and mechanical and hydraulic boundary conditions. Fractured rocks behave nonlinearly, represented by their elasto-plastic behavior with a strain hardening trend. Fluid flow analysis in fractured rocks under hydro-mechanical loading conditions show an important impact of water pressure on the strength and deformability parameters of fractured rocks, due to the effective stress phenomenon, but the values of stress and strength reduction may or may not equal to the magnitude of water pressure, due to the influence of fracture system complexity. Stochastic analysis indicates that the strength and deformation properties of fractured rocks have ranges of values instead of fixed values, hence such analyses should be considered especially in cases where there is significant scatter in the rock and fracture parameters. These scientific achievements can improve our understanding of fractured rocks’ hydro-mechanical behavior and are useful for the design of large-scale in-situ experiments with large volumes of fractured rocks, considering coupled stress-deformation-flow processes in engineering practice.

QC 20141111

Doctor of Philosophy
School of Family Studies and Human Services
Jared R. Anderson
Marriage and relationship education (MRE) is most commonly delivered in a skills-based format that traditionally centers on teaching couples communication skills. Critiques against the current skills-development approach lead to the development and pilot-testing of an alternative self-development curriculum entitled, “Strengthen Yourself, Strengthen Your Relationships.” Guided by Bowen’s (1978) theory of differentiation, the current study randomly assigned forty couples to the self-development (differentiation) curriculum condition or to a relationship assessment plus feedback condition. Repeated measures ANOVA’s, independent samples t-tests, and regressions were used to analyze the data from pre- to post-test (5 weeks), post-test to follow-up (4 weeks), and pre-test to follow-up (9 weeks). Statistical analyses indicate that women responded more favorably to the feedback condition in terms of differentiation, relationship self-regulation, and problem solving, whereas men responded more favorably to the curriculum condition in terms of relationship self-regulation. Feedback about the curriculum was gathered from participants and was received favorably. Implications from the study suggest that both approaches may have unique value for couples receiving relationship education. Future research should further develop and evaluate the self-development approach in MRE.

The topic of interpersonal relationships and the factors that enhance the longevity and strength of these have been well documented. Whilst there has been a steady increase in the occurrence of interracial relationships, it has not been matched by an increase in studies on the phenomenon and indeed very little empirical attention has been given to these relationships. Leslie and Letiecq (2004) highlight that the existing research on the phenomenon focuses primarily on the reasons individuals select partners outside of their own racial group. As interracial marriages are reportedly more vulnerable to divorce than marriages among same-race individuals, it seems important to examine the dynamics and quality of interracial relationships (Leslie & Letiecq, 2004). The goal of the study was therefore to explore the cross-cultural differences that inform the experiences, challenges, and strengths for partners in committed interracial relationships. In this qualitative, exploratory, descriptive and contextual study, the author has explored and described the specific cross-cultural differences that the couple has encountered in their relationship and the impact that these differences have had on the quality of their relationship. Furthermore the study aimed to explore and describe the strengths the couple has drawn from these cross-cultural differences to enhance the quality of their relationship. A combination of purposive and snowball sampling techniques has been utilised to identify interracial couples who have been in a committed monogamous relationship of at least one year. The sample consisted of eleven individuals. Semi-structured individual interviews were utilised as the data collection tool, and Tesch‟s model of data analysis (in Creswell, 1998) has been employed. This model of data analysis consists of eight steps that have been used to analyse the data. Five themes emerged from the study: (1) cultural difference factors, (2) negative factors that influence the couple‟s coping with cultural differences, (3) positive factors that influence the couple‟s coping with cultural differences, (4) factors relating to cultural differences that strengthen the relationship and (5) recommendations to other interracial couples. The findings of the study make a meaningful contribution to couple counselling interventions for interracial couples, and also add to the body of knowledge on this sparsely researched topic.

Despite increased numbers of intercultural couples in the United States, data shows that the pairing of non-Hispanic Black-White interracial couples falls short on all scales (Pew Research Center, 2012). The number of cohabitating interracial couples is almost double the number of married interracial couples; however, they have the lowest rates of marriage and are more likely to divorce when compared to all other intercultural couples. To determine what non-Hispanic Black-White interracial couples must do to strengthen and maintain their relationships, this study interviewed seven cohabitating couples. The qualitative analysis revealed five themes: Culture, Secure Attachment, Communication, Authenticity, and Humor. The themes and implications for couple therapy and future research are also discussed.

High field strength elements (HFSE) are geologically and economically important. These elements were once thought to be immobile during metasomatic processes, however, a growing body of empirical evidence indicates that HFSE can be mobilized under certain conditions. Despite this evidence, little is known about the factors controlling solubility, transport and deposition of HFSE by aqueous fluids, apart from some theoretical estimates and rare experimental studies. Therefore, the study of natural systems (e.g., HFSE ore deposits) provides an excellent opportunity to evaluate HFSE mobility by aqueous fluids. Five localities where evidence of hydrothermal transport of HFSE has been previously documented were included in this study: Gallinas Mountains, New Mexico; South Platte, Colorado; Rock Canyon Creek, British Columbia; St. Lawrence, Newfoundland; and Strange Lake, Quebec/Labrador. Minerals and, in the case of South Platte, fluid inclusions from these localities were analyzed using petrography and laser ablation inductively-coupled plasma mass spectrometry (LA-ICPMS) to evaluate the source of the HFSE and the hydrothermal fluids responsible for HFSE transport, and factors controlling HFSE and gangue mineral (e.g., fluorite, quartz) precipitation. Analysis of some of the important gangue minerals, which are also the primary host of fluid inclusions in many of these deposits (e.g., fluorite), is difficult using 266 nm Nd:YAG-based LA-ICPMS. Furthermore, complex mineral intergrowths and the desire to quantify the chemical composition of unknown minerals required the development of analytical and data reduction protocols for LA-ICPMS. Methods for conducting traversed opening of fluid inclusions, removing the host mineral contribution to fluid inclusion signals by calculating count rate ratios, and quantifying the composition of minerals without using an internal standard are presented. In general, hydrothermal enrichment of HFSE in these deposits appears to have resulted from interaction of an HFSE- and F-bearing magmatic fluid with another, Ca-bearing fluid or with Ca-bearing wall rocks or preexisting minerals. In most cases, HFSE appear to be derived locally, within the associated igneous intrusion.

The evolution of mountain landscapes is controlled by complex interactions between large-scale tectonic, surficial and climate conditions. Dominant processes are attributed to creating characteristic features of the landscape, but topographic features are the cumulative result of coupled surficial processes, each locally effective in a different climate or elevation regime. The focus of erosion by glacial, fluvial, or mass wasting processes is highly sensitive to small changes in boundary conditions, therefore spatial and temporal variability can be high when observed over short time scales. This work evaluated methods for dissecting the history of complex alpine landscapes to understand the role of individual processes influenced by changing climate and underlying bedrock. It also investigated how individual and combined mechanisms of surficial processes influenced the evolution of topography in the Teton Range in Wyoming. Detrital apatite (U-Th)/He thermochronology and cosmogenic radionuclide erosion rates were applied to determine spatial and temporal variability of erosion in the central catchments of the range. Spatial variability existed between the glacial and fluvial systems, indicating that sediment erosion and deposition by these processes was controlled by short-term variability in climate conditions. Effective glacial incision also controlled other processes, specifically enhancing rock fall activity and inhibiting fluvial incision. Short-term erosion rates were highly variable and were controlled by stochastic processes, particularly hillslope failures in response to slope oversteepening due to glacial incision and orientation and spacing of bedrock fractures. Erosion rates averaged over 10 ky time scales were comparable to long-term exhumation rates measured in the Teton Range. The similarity of spatial erosion patterns to predicted uniform erosion and the balance between intermediate and long-term erosion rates suggests the landscape of the Teton Range is approaching steady-state, but frequent stochastic processes, short-term erosional variability and coupled processes maintain rugged topographic relief.
Ph. D.

Transcription by RNA polymerase can induce the formation of hypernegatively supercoiled DNA both in vivo and in vitro. This phenomenon has been explained by a “twin-supercoiled-domain” model of transcription where a positively supercoiled domain is generated ahead of the RNA polymerase and a negatively supercoiled domain behind it. In E. coli cells, transcription-induced topological change of chromosomal DNA is expected to actively remodel chromosomal structure and greatly influence DNA transactions such as transcription, DNA replication, and recombination. In this study, an IPTG-inducible, two-plasmid system was established to study transcription-coupled DNA supercoiling (TCDS) in E. coli topA strains. By performing topology assays, biological studies, and RT-PCR experiments, TCDS in E. coli topA strains was found to be dependent on promoter strength. Expression of a membrane-insertion protein was not needed for strong promoters, although co-transcriptional synthesis of a polypeptide may be required. More importantly, it was demonstrated that the expression of a membrane-insertion tet gene was not sufficient for the production of hypernegatively supercoiled DNA. These phenomenon can be explained by the “twin-supercoiled-domain” model of transcription where the friction force applied to E. coli RNA polymerase plays a critical role in the generation of hypernegatively supercoiled DNA. Additionally, in order to explore whether TCDS is able to greatly influence a coupled DNA transaction, such as activating a divergently-coupled promoter, an in vivo system was set up to study TCDS and its effects on the supercoiling-sensitive leu-500 promoter. The leu-500 mutation is a single A-to-G point mutation in the -10 region of the promoter controlling the leu operon, and the AT to GC mutation is expected to increase the energy barrier for the formation of a functional transcription open complex. Using luciferase assays and RT-PCR experiments, it was demonstrated that transient TCDS, “confined” within promoter regions, is responsible for activation of the coupled transcription initiation of the leu-500 promoter. Taken together, these results demonstrate that transcription is a major chromosomal remodeling force in E. coli cells.

The geological disposal of nuclear waste, in underground openings and the long-term performance of these openings demand a detailed understanding of fundamental rock mechanics. A full scale field experiment: Äspö Pillar Stability Experiment was conducted at a depth of 450 m in sparsely fractured granitic rock to examine the rock mass response between two deposition holes. An oval shaped tunnel was excavated parallel to the σ3 direction to provide access to the experiment and also provide elevated stress magnitudes in the floor. In the tunnel floor two 1.75-m diameter 6-m deep boreholes were excavated so that a 1-m thick pillar was created between them. In one of the holes a confinement pressure of 700 kPa was applied and in the other displacement transducers were installed. The pillar volume was monitored by an Acoustic Emission System. Spatially distributed thermocouples were used to monitor the temperature development as the pillar was heated by electrical heaters. The excavation-induced stress together with the thermal-induced stress was sufficient to cause the wall of the open borehole to yield. The temperature-induced stress was increased slowly to enable detailed studies of the rock mass yielding process. Once the rock mass loading response was observed, the rock mass was unloaded using a de-stress slotting technique. This thesis focuses on the in-situ study of the rock mass response to coupled mechanical thermal loading and thermal-mechanical unloading. The experiment, its design, monitoring and observations are thoroughly described. An estimate of the yielding strength of the rock mass is presented and compared with laboratory test and results from other rock mass conditions reported elsewhere in the open literature. General conclusions about the effect of the confining pressure and the observations from the unloading of the pillar are also presented. Important findings are that the yielding strength of the rock mass has been successfully determined, low confinement pressures significantly affects the onset of yielding, the primary mode of fracture initiation and propagation is extensional, no significant time dependency of the yielding process was observed. The unloading studies also indicated that what appeared to be shear bands likely was a propagating zone of extensile failure that weakened the rock so that displacements in the shear direction could occur.

QC 20100622

Recent studies have reported that African American couples in the military are less likely to divorce than their civilian counterparts. This dissertation was designed to document the experiences of African American military couples in order to understand the challenges they face while serving in the armed forces and the strategies they have used to maintain their marriages. A grounded theory approach was utilized to produce 12 main themes that categorize experiences of both the individual and the couple within the context of their respective military branch. Photo-elicitation was incorporated into semi-structured interviews with 10 couples to identify what they consider to be the important aspects of their marriage, the ways in which their relationships were impacted by the demands of duty, and their perspectives on the role that race plays in an institution that has been characterized as relatively race-neutral.

This study evaluates the efficacy of a self-guided, low-intensity curriculum, Marriage Moments, based on Fowers' (2000) virtues model of marital quality that emphasizes friendship, generosity, justice and loyalty. The Marriage Moments program consists of a guidebook and a video that were designed to strengthen marriages during the transition to parenthood and is used in the context of a home visitation program for first-time parents. Participants in the study included 119 married couples who had recently given birth to their first child. They were assigned to either a treatment, comparison or control group. The treatment group received the Marriage Moments curriculum as well as the Welcome Baby home visitation curriculum, the comparison group only received the Welcome Baby curriculum and the control group received neither program. Data were gathered through a battery of self- and spouse-report measures given at 3-months, 4-months, and 9-months postpartum. Relationship outcome measures included in this study were the Marital Virtues Profile, Revised-Dyadic Adjustment Scale, RELATE Satisfaction subscale, Transition Adjustment Scale, Father Involvement Scale, Household Labor Scale, and Maternal Depression Scale. Despite positive evaluations of the program from participants, analyses revealed a lack of significant, positive effects for members of the treatment group. Further research is needed before reliable conclusions can be drawn about the value of a marital virtues model as a guide for low intensity intervention.

Puisque les incertitudes des paramètres de systèmes mécaniques entrainent la variabilité de la performance du produit, les systèmes optimisés sans prendre en compte les incertitudes peuvent présenter le risque de défaillance. L'optimisation fiabiliste (RBDO) focalise ainsi l'attention des ingénieurs et des chercheurs. Cependant, les méthodes habituelles de RBDO présentent un coût informatique excessif. Donc, afin d'améliorer l'efficacité informatique de la résolution de problèmes de RBDO, il est naturel de faire appel à des approches basées sur les surfaces de réponse (RSM). Dans ce travail, nous nous concentrons sur une Méthodologie de Surface de Réponse adaptée à la conception optimale dans le contexte fiabiliste. Nous proposons une variante de l'Approximation Diffuse, basée sur un modèle d'échantillonnage progressif et couplée à l'estimation de la fiabilité par FORM. La méthode proposée utilise simultanément des points dans l'espace normal standard U ainsi que dans l'espace physique X. Les deux réseaux forment un « plan d'expériences virtuel » défini par deux jeux de points dans les deux espaces de conception, qui sont évalués seulement quand nécessaire pour réduire au minimum le nombre d'évaluations « exactes » et ainsi diminuer le coût informatique. Dans chaque nouvelle itération, le pattern de points est mis à jour avec des points du design virtuel convenablement choisis afin d'effectuer l'approximation. Nous étendons ici l'idée d'Hypercube Latin (LHS) pour réutiliser au maximum des points précédemment calculés en ajoutant un nombre minimal de nouveaux points voisins à chaque étape, nécessaires pour l'approximation au voisinage du design actuel. Nous proposons des opérateurs de translation, de zoom avant et arrière, étendant ainsi le modèle LHS et le rendant récursif tout en contrôlant la qualité d'exploration de l'espace de conception et en maximisant le conditionnement de l'approximation. Dans la partie applicative de ce travail, nous examinons l'optimisation des paramètres du processus de fraisage à commande numérique (NC) de l'acier à haute limite élastique. Le succès de l'opération d'usinage dépend de la sélection des paramètres tels que le taux d'alimentation, la vitesse de coupe, les profondeurs axiales et radiales de coupe. Les contraintes d'optimisation sont exprimées comme des fonctions des indices de fiabilité calculés par FORM diffus
Since variances in the input parameters of engineering systems cause subsequent variations in the product performance, and deterministic optimum designs that are obtained without taking uncertainties into consideration could lead to unreliable designs. Reliability-Based Design Optimization (RBDO) is getting a lot of attention recently. However, RBDO is computationally expensive. Therefore, the Response Surface Methodology (RSM) is often used to improve the computational efficiency in the solution of problems in RBDO. In this work, we focus on a Response Surface Methodology (RSM) adapted to the Reliability-Based Design Optimization (RBDO). The Diffuse Approximation (DA), a variant of the well-known Moving Least Squares (MLS) approximation based on a progressive sampling pattern is used within a variant of the First Order Reliability Method (FORM). The proposed method simultaneously uses points in the standard normal space (U-space) as well as the physical space (X-space). The two grids form a “virtual design of experiments” defined by two sets of points in the two design spaces, that are evaluated only when needed in order to minimize the number of ‘exact’ thus computationally expensive function evaluations. In each new iteration, the pattern of points is updated with points appropriately selected from the “virtual design of experiments”, in order to perform the approximation. As an original contribution, we introduce the concept of « advancing Latin Hypercube Sampling (LHS) » which extends the idea of Latin Hypercube Sampling (LHS) to maximally reuse previously computed points while adding a minimal number of new neighboring points at each step, necessary for the approximation in the vicinity of the current design. We propose panning, expanding and shrinking Latin hypercube patterns of sampling points and we analyze the influence of this specific kind of patterns on the quality of the approximation. Next we calculate the minimal number of data points required in order to get a well-conditioned approximation system. In the application part of this work, we investigate the optimization of the process parameters for Numerical Control (NC) milling of ultrahigh strength steel. The success of the machining operation depends on the selection of machining parameters such as the feed rate, cutting speed, and the axial and radial depths of cut. A variant of the First Order Reliability Method (FORM) is chosen to calculate the reliability index. The optimization constraints are expressed as functions of the computed reliability indices

Durant la dernière décennie, le développement de nouvelles nuances d'acier à très haute résistance a connu un essor, en particulier dans l’automobile. Les acteurs de ce secteur ont pour objectif de produire des véhicules plus légers, plus performants, plus économes en carburant et garantissant un plus haut niveau de sécurité pour les passagers. De nouvelles nuances ou de nouvelles structures sont apparues sur le marché : plus résistants avec un meilleur compromis résistance/ductilité. Cependant cette élévation des propriétés mécaniques se fait le plus souvent au détriment de l’usinabilité des aciers.Les résultats de travaux antérieurs ont motivé une étude poussée qui porte sur l’influence de la structure métallique sur l’usinabilité des aciers. Le travail compare le comportement d’un aciers bas-carbone obtenue par refroidissement contrôlé à celui d’une nuance conventionnelle à l’état trempé revenue et à l’état bainitique. Les conditions thermomécaniques rencontrées à l’interface outil/copeau lors de l’usinage sont caractérisées par mesure des efforts de coupe et investigation de la morphologie et de la microstructure des copeaux. La durée de vie des outils coupants est quantifiée et les différents modes d’usure sont caractérisés
During the past decade, the automotive industry is increasingly relying on new grades of high strength steels. Companies involved in this sector aim to produce lighter, more effective vehicles that are both fuel-efficient and guarantee a high level of safety for its passengers. New structures have emerged on the market presenting an opportune correlation between high mechanical resistance and ductility. However, this increase in mechanical properties is most often achieved at the expense of the machinability of steels in question.The results of previous works have motivated a detailed study that focuses on the influence of the metallic structure on the machinability of steels. The work compares the behavior of low-carbon steels obtained by controlled cooling with that of a conventional steel in both the quenched and tempered state and the bainitic state. The thermomechanical conditions at the tool / chip interface during cutting are identified by measuring the cutting forces and investigating the chips morphology and microstructure. The cutting-tool life expectancy is quantified and the different modes of insert wear are studied

Cette thèse s'intéresse à la signature sismique du rôle des fluides dans les mécanismes de déformation des roches fracturées de la croûte supérieure, et plus précisément les failles et les glissements de terrain. S'il est admis que les fluides sont un facteur déclenchant de la rupture dans le cas d'épisodes de forçages climatiques importants ou de glissements très superficiels, leur rôle dans la déstabilisation des grands volumes associée à des forçages faibles est beaucoup moins bien compris. Ainsi, il apparaît nécessaire d'acquérir de nouvelles données synchrones des pressions/débits de fluides, de la déformation et de la sismicité sur le terrain dans des conditions de chargement hydraulique contrôlées pour progresser dans la compréhension des liens entre processus hydromécaniques et sismiques participant à la nucléation de la rupture des roches en partie associée à la réactivation de fractures existantes. Motivé par ce besoin de nouvelles observations, ce travail de thèse concerne l'interprétation de la sismicité produite lors d'expériences originales de stimulation hydraulique (0.3 à 3.5 MPa et 10 à 3000 secondes) de petites zones de faille ou de fractures de taille décamétrique, situées en zones non saturées profonde de versants rocheux. Ces expériences consistaient à produire des déformations menant à l'activation du glissement le long des fractures préexistantes. Le protocole expérimental combine des mesures de déformations/pressions distribuées dans les structures géologiques à des capteurs sismologiques proches (échelle métrique à décamétrique) des zones sources.

[EN] Phononic crystals are artificial materials formed by a periodic arrangement of inclusions embedded into a host medium, where each of them can be solid or fluid. By controlling the geometry and the impedance contrast of its constituent materials, one can control the dispersive properties of waves, giving rise to a huge variety of interesting and fundamental phenomena in the context of wave propagation. When a propagating wave encounters a medium with different physical properties it can be transmitted and reflected in lossless media, but also absorbed if dissipation is taken into account. These fundamental phenomena have been classically explained in the context of homogeneous media, but it has been a subject of increasing interest in the context of periodic structures in recent years as well. This thesis is devoted to the study of different effects found in sonic and phononic crystals associated with transmission, reflection and absorption of waves, as well as the development of a technique for the characterization of its dispersive properties, described by the band structure. We start discussing the control of wave propagation in transmission in conservative systems. Specifically, our interest is to show how sonic crystals can modify the spatial dispersion of propagating waves leading to control the diffractive broadening of sound beams. Making use of the spatial dispersion curves extracted from the analysis of the band structure, we first predict zero and negative diffraction of waves at frequencies close to the band-edge, resulting in collimation and focusing of sound beams in and behind a 3D sonic crystal, and later demonstrate it through experimental measurements. The focusing efficiency of a 3D sonic crystal is limited due to the strong scattering inside the crystal, characteristic of the diffraction regime. To overcome this limitation we consider axisymmetric structures working in the long wavelength regime, as a gradient index lens. In this regime, the scattering is strongly reduced and, in an axisymmetric configuration, the symmetry matching with acoustic sources radiating sound beams increase its efficiency dramatically. Moreover, the homogenization theory can be used to model the structure as an effective medium with effective physical properties, allowing the study of the wave front profile in terms of refraction. We will show the model, design and characterization of an efficient focusing device based on these concepts. Consider now a periodic structure in which one of the parameters of the lattice, such as the lattice constant or the filling fraction, gradually changes along the propagation direction. Chirped crystals represent this concept and are used here to demonstrate a novel mechanism of sound wave enhancement based on a phenomenon known as "soft" reflection. The enhancement is related to a progressive slowing down of the wave as it propagates along the material, which is associated with the group velocity of the local dispersion relation at the planes of the crystal. A model based on the coupled mode theory is proposed to predict and interpret this effect. Two different phenomena are observed here when dealing with dissipation in periodic structures. On one hand, when considering the propagation of in-plane sound waves in a periodic array of absorbing layers, an anomalous decrease in the absorption, combined with a simultaneous increase of reflection and transmission at Bragg frequencies is observed, in contrast to the usual decrease of transmission, characteristic in conservative periodic systems at these frequencies. For a similar layered media, backed now by a rigid reflector, out-of-plane waves impinging the structure from a homogeneous medium will increase dramatically the interaction strength. In other words, the time delay of sound waves inside the periodic system will be considerably increased resulting in an enhanced absorption, for a broadband spectral range.
[ES] Los cristales fonónicos son materiales artificiales formados por una disposición periódica de inclusiones en un medio, pudiendo ambos ser de carácter sólido o fluido. Controlando la geometría y el contraste de impedancias entre los materiales constituyentes se pueden controlar las propiedades dispersivas de las ondas. Cuando una onda propagante se encuentra un medio con diferentes propiedades físicas puede ser transmitida y reflejada, en medios sin pérdidas, pero también absorbida, si la disipación es tenida en cuenta. La presente tesis está dedicada al estudio de diferentes efectos presentes en cristales sónicos y fonónicos relacionados con la transmisión, reflexión y absorción de ondas, así como el desarrollo de una técnica para la caracterización de sus propiedades dispersivas, descritas por la estructura de bandas. En primer lugar, se estudia el control de la propagación de ondas en transmisión en sistemas conservativos. Específicamente, nuestro interés se centra en mostrar cómo los cristales sónicos son capaces de modificar la dispersión espacial de las ondas propagantes, dando lugar al control del ensanchamiento de haces de sonido. Haciendo uso de las curvas de dispersión espacial extraídas del análisis de la estructura de bandas, se predice primero la difracción nula y negativa de ondas a frecuencias cercanas al borde de la banda, resultando en la colimación y focalización de haces acústicos en el interior y detrás de un cristal sónico 3D, y posteriormente se demuestra mediante medidas experimentales. La eficiencia de focalización de un cristal sónico 3D está limitada debido a las múltiples reflexiones existentes en el interior del cristal. Para superar esta limitación se consideran estructuras axisimétricas trabajando en el régimen de longitud de onda larga, como lentes de gradiente de índice. En este régimen, las reflexiones internas se reducen fuertemente y, en configuración axisimétrica, la adaptación de simetría con fuentes acústicas radiando haces de sonido incrementa la eficiencia drásticamente. Además, la teoría de homogenización puede ser empleada para modelar la estructura como un medio efectivo con propiedades físicas efectivas, permitiendo el estudio del frente de ondas en términos refractivos. Se mostrará el modelado, diseño y caracterización de un dispositivo de focalización eficiente basado en los conceptos anteriores. Considérese ahora una estructura periódica en la que uno de los parámetros de la red, sea el paso de red o el factor de llenado, cambia gradualmente a lo largo de la dirección de propagación. Los cristales chirp representan este concepto y son empleados aquí para demostrar un mecanismo novedoso de incremento de la intensidad de la onda sonora basado en un fenómeno conocido como reflexión "suave". Este incremento está relacionado con una ralentización progresiva de la onda conforme se propaga a través del material, asociado con la velocidad de grupo de la relación de dispersión local en los planos del cristal. Un modelo basado en la teoría de modos acoplados es propuesto para predecir e interpretar este efecto. Se observan dos fenómenos diferentes al considerar pérdidas en estructuras periódicas. Por un lado, si se considera la propagación de ondas sonoras en un array periódico de capas absorbentes, cuyo frente de ondas es paralelo a los planos del cristal, se produce una reducción anómala en la absorción combinada con un incremento simultáneo de la reflexión y transmisión a las frecuencias de Bragg, de forma contraria a la habitual reducción de la transmisión, característica de sistemas periódicos conservativos a estas frecuencias. En el caso de la misma estructura laminada en la que se cubre uno de sus lados mediante un reflector rígido, la incidencia de ondas sonoras desde un medio homogéneo, cuyo frente de ondas es perpendicular a los planos del cristal, produce un gran incremento de la fuerza de
[CAT] Els cristalls fonònics són materials artificials formats per una disposició d'inclusions en un medi, ambdós poden ser sòlids o fluids. Controlant la geometría i el contrast d'impedàncies dels seus materials constituents, és poden controlar les propietats dispersives de les ondes, permetent una gran varietatde fenòmens fonamentals interessants en el context de la propagació d'ones. Quan una ona propagant troba un medi amb pèrdues amb propietats físiques diferents es pot transmetre i reflectir, però també absorbida si la dissipació es té en compte. Aquests fenòmens fonamentals s'han explicat clàssicament en el context de medis homogenis, però també ha sigut un tema de creixent interés en el context d'estructures periòdiques en els últims anys. Aquesta tesi doctoral tracta de l'estudi de diferents efectes en cristalls fonònics i sònics lligats a la transmissió, reflexió i absorció d'ones, així com del desenvolupament d'una tècnica de caracterització de les propietats dispersives, descrites mitjançant la estructura de bandes. En primer lloc, s'estudia el control de la propagació ondulatori en transmissió en sistemes conservatius. Més específicament, el nostre interés és mostrar com els cristalls sonors poden modificar la dispersió espacial d'ones propagants donant lloc al control de l'amplària per difracció dels feixos sonors. Mitjançant les corbes dispersió espacial obtingudes de l'anàlisi de l'estructura de bandes, es prediu, en primer lloc, la difracció d'ones zero i negativa a freqüències próximes al final de banda. El resultat és la collimació i focalització de feixos sonors dins i darrere de cristalls de so. Després es mostra amb mesures experimentals. L'eficiència de focalització d'un cristall de so 3D està limitada per la gran dispersió d'ones dins del cristall, que és característic del règim difractiu. Per a superar aquesta limitació, estructures axisimètriques que treballen en el règim de llargues longituds d'ona, i es comporten com a lents de gradient d'índex. En aquest règim, la dispersió es redueix enormement i, en una configuració axisimètrica, a causa de l'acoblament de la simetría amb les fonts acústiques que radien feixos sonors, l'eficiència de radiació s'incrementa significativament. D'altra banda, la teoria d'homogeneïtzació es pot utilitzar per a modelar, dissenyar i caracteritzar un dispositiu eficient de focalització basat en aquests conceptes. Considerem ara una estructura periòdica en la qual un dels seus paràmetres de xarxa, com ara la constant de xarxa o el factor d'ompliment canvia gradualment al llarg de la direcció de propagació. Els cristalls chirped representen aquest concepte i s'utilitzen ací per a demostrar un mecanisme nou d'intensificació d'ones sonores basat en el fenòmen conegut com a reflexió "suau". La intensificació està relacionada amb la alentiment progressiva de l'ona conforme propaga al llarg del material, que està associada amb la velocitat de grup de la relació de dispersió local en els diferents plànols del cristall. Es proposa un model basat en la teoria de modes acoblats per a predir i interpretar este efecte. Dos fenòmens diferents cal destacar quan es tracta d'estructures periòdiques amb dissipació. Per un costat, al considerar la propagació d'ones sonores en el plànol en un array periòdic de capes absorbents, s'observa una disminució anòmala de l'absorció i es combina amb un augment simultani de reflexió i transmissió en les freqüències de Bragg que contrasta amb la usual disminució de transmissió, característica dels sistemes conservatius a eixes freqüències. Per a un medi similar de capes, amb un reflector rígid darrere, les ones fora del pla incidint l'estructura des de un medi homogeni, augmentaran considerablement la interacció. En altres paraules, el retràs temporal de les ones sonores dins del sistema periòdic augmentarà significativament produint un augmen
Cebrecos Ruiz, A. (2015). Transmission, reflection and absorption in Sonic and Phononic Crystals [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/56463
TESIS
Premiado

碩士
國立台灣工業技術學院
營建工程技術研究所
85
In this study, the strength of welds connecting steel plate and steelcoupler is investigated. A total of 88 specimens, including partial penetration groove welds with single-J bevel and fillet welds, using #10 steel coupler are tested. Test results show that：(1) AWS prequalified partial penetration groove welds with single-J bevel is suitable for assemblage of couplers and steel. (2) The formula suggested in chapter 4 gives a good estimation of the weld strength of partial penetration groove welds with single-J bevel couplers, (3) In the practical range, the thickness combination of box column plate and diaphragm does not influence the strength of welds. (4) Eccentricity, between coupler and diaphragm, smaller than 7 mm, does not decrease the strength of welds.

碩士
國立成功大學
光電科學與工程學系
106
In this thesis, we present a numerical investigation of mutually injected semi-conductor lasers when the injection strength is asymmetric. For the purpose of ap-plications on communication system, the investigation focuses on period-one dy-namics and stable dynamics. First of all, the dynamics scenario of short delay sys-tem is studied to serve as a complete view of the dynamics changing. In order to study the effect on chip-scale mutually injected devices, we investigate the ul-tra-short delay system. Besides, the period-one dynamics is investigated in micro-wave fundamental frequency, sideband to carrier ratio and sideband rejection ratio and the potential of all-optical microwave generation is illustrated. Though symmet-ric mutual injection system is contract with unidirectional injection system, mutual injection systems share the same useful characteristic when proper asymmetry is presence. Finally, the stable dynamics is investigated in oscillation frequency and direct modulation response. The tunable high frequency oscillation and the condi-tions of flat frequency response is discovered.

博士
中正理工學院
國防科學研究所
86
Submersible pressure hull is an important element of submarine structures which, from a structural perspective, can withstand a uniform external pressure. The structure may undergo transient dynamic loading in a complex operating site. Therefore, owing to its practical applications, results obtained from transient interaction of shock wave with submerged structure have received considerable interest. Based on the procedure which couples the Finite Element method with the integral representation for the pressure on shell surface derived from Kirchhoff’s retarded potential integral method, this work addresses the problem of transient responses of a submarine’s pressure hull subjected to expotential incident shock wave in sea water, in air and in vacuum, in which geometrical nonlinear and elastoplastic material behavior is considered. Numerical results indicate that the adopted procedure shows good agreement with related literature, which considered the linear elastic behavior of a shell. In static study, performance results reveals that the maximum von mises stress and radial displacement occur at the middle of compartments. In transient dynamic study, analysis results indicate that the structure responses considered fluid-structure interaction has time delay, response level and frequency drop.

Detection and monitoring of the damage created by the corrosion of the steel reinforcement in concrete structures is a challenging and multidisciplinary problem. Economical monitoring strategy that is long-term and nondestructive requires low-cost, battery-free, wireless sensors. Our Electronic Structural Surveillance (ESS) platform uses battery-free passive resonant circuit (tag) as a sensor. The tag is magnetically coupled to an external reader coil. It is interrogated/read remotely in a non-contact (wireless) manner and the state of the sensor is determined from a swept frequency impedance measurement. When paired with the correct sensing element (transducer), the tag can be used for a variety of sensing applications for example, chemical & biochemical sensors. A circuit model of the reader and tag for such a universal battery-free wireless sensor platform is developed. The interaction between design and detection limit is examined. The dependence of the measured signal strength and read range on the various reader and tag circuit parameters is analyzed. Since the values of the circuit of the coils are dependent on their geometries, the effect of specific coil geometry is evaluated and design recommendations are made.
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