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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.
21

Tester kabeláže / Cable harness tester

Valenta, Jakub January 2021 (has links)
This semestral paper deals with the issues of testing and requirements examinations for cables and cable harnesses. These terms are defined in the work and the difference in their meaning is described. The work also describes the characteristic features of cables and cable harnesses, explains their importance and focuses in more detail on the variable properties that may change over time or that are dependent on manufacturing errors. The principles and procedures of tests of these properties are covered in the work and are the essence of the subsequent practical part. In this part, the work deals with the design of the measuring circuit prototype for testing of the insulation resistance of cables and their desired continuity in bundles. This design is then physically implemented, the processes of designing and implementing are described in detail and finally its functionality is tested and presented to the reader.
22

Biomechanics of Developmental Dysplasia of the Hip - An engineering study of closed reduction utilizing the Pavlik harness for a range of subtle to severe dislocations in infants.

Huayamave, Victor 01 January 2015 (has links)
Developmental Dysplasia of the Hip (DDH) is an abnormal condition where hip joint dislocation, misalignment, or instability is present in infants. Rates of incidence of DDH in newborn infants have been reported to vary between 1 and 20 per 1000 births, making it the most common congenital malformation of the musculoskeletal system. DDH early detection and treatment is critical to avoid the use of surgical treatment in infants and to prevent future complications such as osteoarthritis in adult life. To this day several non-surgical treatments involving the use of harnesses and braces have been proposed to treat DDH in infants, with the Pavlik harness being the current non-surgical standard used to treat DDH at early stages. Although the Pavlik harness has been proven to be successful treating subtle dislocations, severe dislocations do not always reduce. Until now the use of the harness remains an empirical method, and its effectiveness often depends on physician expertise or trial-error procedures; thus a clear guideline has not been established to determine the best optimal harness configuration to treat both subtle and severe dislocations. The goal of this dissertation is to understand the connection between reductions for subtle and severe dislocations and passive muscle forces and moments generated while the harness is used during treatment. While the understanding of DDH biomechanics will provide a valuable clinically applicable approach to optimize and increase harness success rate, it is not without its difficulties. This research has created and developed a three-dimensional based on patient-specific geometry of an infant lower limb. The kinematics and dynamics of the lower limb were defined by modeling the hip, femur, tibia, fibula, ankle, foot, and toe bones. The lines of action of five (5) adductor muscles, namely, the Adductor Brevis, Adductor Longus, Adductor Magnus, Pectineus, and Gracilis were identified as mediators of reduction and its mechanical behavior was characterized using a passive response. Four grades (1-4) of dislocation as specified by the International Hip Dysplasia Institute (IHDI) were considered, and the computer model was computationally manipulated to represent physiological dislocations. To account for proper harness modeling, the femur was restrained to move in an envelope consistent with its constraints. The model of the infant lower limb has been used to analyze subtle and severe dislocations. Results are consistent with previous studies based on a simplified anatomically-consistent synthetic model and clinical reports of very low success of the Pavlik harness for severe dislocations. Furthermore the findings on this work suggest that for severe dislocations, the use of the harness could be optimized to achieve hyperflexion of the lower limb leading to successful reduction for cases where the harness fails. This approach provides three main advantages and innovations: 1) the used of patient-specific geometry to elucidate the biomechanics of DDH; 2) the ability to computationally dislocate the model to represent dislocation severity; and 3) the quantification of external forces needed to accomplish reduction for severe dislocations. This study aims to offer a practical solution to effective treatment that draws from engineering expertise and modeling capabilities and also draws upon medical input. The findings of this work will lay the foundation for future optimization of non-surgical methods critical for the treatment of DDH.
23

Biomechanical Factors Influencing Treatment Of Developmental Dysplasia Of The Hip (ddh) With The Pavlik Harness

Ardila, Orlando 01 January 2013 (has links)
Biomechanical factors influencing the reduction of dislocated hips with the Pavlik harness in patients of Developmental Dysplasia of the Hip (DDH) were studied using a simplified three-dimensional computer model simulating hip reduction dynamics in (1) subluxated, and (2) fully dislocated hip joints. The CT-scans of a 6 month-old female infant were used to measure the geometrical features of the hip joint including acetabular and femoral head diameter, acetabular depth, and geometry of the acetabular labrum, using the medical segmentation software Mimics. The lower extremity was modeled by three segments: thigh, leg, and foot. The mass and the location of the center of gravity of each segment were calculated using anthropometry, based on the total body mass of a 6-month old female infant at the 50th length-for-age percentile. A calibrated nonlinear stress-strain model was used to simulate muscle responses. The simplified 3D model consists of the pubis, ischium, acetabulum with labrum, and femoral head, neck, and shaft. It is capable of simulating dislocated as well as reduced hips in abduction and flexion. Five hip adductor muscles were identified as key mediators of DDH prognosis, and the non-dimensional force contribution of each in the direction necessary to achieve concentric hip reductions was determined. Results point to the adductor muscles as mediators of subluxated hip reductions, as their mechanical action is a function of the degree of hip dislocation. For subluxated hips in abduction and flexion, the Pectineus, Adductor Brevis, Adductor Longus, and proximal Adductor Magnus muscles contribute positively to reduction, while the rest of the Adductor Magnus contributes negatively. In full dislocations all muscles contribute detrimentally to reduction, elucidating the need for traction to reduce Graf IV type dislocations. Reduction of iv dysplastic hips was found to occur in two distinct phases: (a) release phase and (b) reduction phase. To expand the range of DDH-related problems that can be studied, an improved threedimensional anatomical computer model was generated by combining CT-scan and muscle positional data belonging to four human subjects. This model consists of the hip bone and femora of a 10-week old female infant. It was segmented to encompass the distinct cartilaginous regions of infant anatomy, as well as the different regions of cortical and cancellous bone; these properties were retrieved from the literature. This engineering computer model of an infant anatomy is being employed for (1) the development of a complete finite element and dynamics computer model for simulations of hip dysplasia reductions using novel treatment approaches, (2) the determination of a path of least resistance in reductions of hip dysplasia based on a minimum potential energy approach, (3) the study of the mechanics of hyperflexion of the hip as alternative treatment for late-presenting cases of hip dysplasia, and (4) a comprehensive investigation of the effects of femoral anteversion angle (AV) variations in reductions of hip dysplasia. This thesis thus reports on an interdisciplinary effort between orthopedic surgeons and mechanical engineers to apply engineering fundamentals to solve medical problems. The results of this research are clinically relevant in pediatric orthopaedics.
24

Analyse électrothermique des faisceaux de câbles de puissance : une contribution à l’optimisation des systèmes de distribution d’énergie dans les véhicules routiers à propulsion électrique / Electro-thermal analysis of power cable harnesses : a contribution for the optimization of energy distribution systems in road vehicles with electric drives

Holyk, Christophe 04 December 2014 (has links)
Dans le contexte de la montée des préoccupations écologiques, le développement de véhicules de transports routiers s’oriente vers le développement de véhicules moins polluants à entraînement électrique comme les Véhicules Électriques Hybrides (VEHs) et les Véhicules tout Électriques (VEs). Avec l’augmentation des puissances requises et la réduction de l’espace disponible, la gestion thermique devient une préoccupation de plus en plus importante lors du développement des composants embarqués comme les moteurs/générateurs électriques, onduleurs, batteries et faisceaux électriques. Parmi eux, le faisceau électrique de puissance qui est typiquement composé de câbles électriques, de connecteurs et de boîtes de distribution de puissance ne peut être conçu de manière appropriée qu’à la suite d’une analyse thermique, électrique, chimique et mécanique approfondie.Cette thèse est écrite pour contribuer à l’optimisation de la conception électrothermique de faisceaux de câbles par des simulations afin de réduire la quantité de tests expérimentaux nécessaires pour leur développement. Des modèles théoriques pour la prédiction du comportement électrique et thermique de câbles électriques et des faisceaux de câbles sont passés en revue et adaptés aux exigences automobiles. La validation est accomplie en comparant les résultats de simulation avec ceux d’analyses élément finie (FEA) et de données de mesure. Une partie majeure de cette thèse aborde la simulation thermique de câbles électriques de longueur infinie suspendus dans l’air, prenant en compte les dépendances en température des résistances de conducteurs et la non-linéarité du coefficient de transfert thermique total à la surface du câble. L’influence des courants de blindage et de courants arbitraires dans les conducteurs sur la montée en température des câbles électriques est considérée dans des circuits thermiques équivalents et illustré par des exemples pratiques. / In the context of growing ecological concerns, the development of road transport vehicles moves itself toward the development of less polluting vehicles with electric drives such as Hybrid Electric Vehicles (HEVs) and full Electric Vehicles (EVs). With rising power requirements and reducing available space, thermal management is becoming an increasingly important concern during development of on-board vehicle components such as electric motor(s)/generator(s), power inverter(s), battery pack(s) and cable harnesses. Among them, the cable harness which is typically composed of electrical cables, connectors and power distribution boxes can only be designed properly after a detailed thermal, electrical, chemical and mechanical analysis.This thesis is written to contribute to the optimization of the electro-thermal design of cable harnesses through simulations and reduce the amount of experimental testing needed during their development. Theoretical models for the prediction of the electrical and thermal behavior of electric cables and cable harnesses are reviewed and adapted for automotive requirements. Validation is accomplished by comparing simulation results with Finite Element Analysis (FEA) and measurement data. A major part of this thesis addresses the thermal simulation of electrical cables of infinite length installed in air, taking into account the temperature dependencies of conductor resistances and non-linearity of the total heat transfer coefficient at the cable surface. The influence of shielding currents and arbitrary current loads in the conductors on the temperature rises within electric cables is also considered using thermal ladder networks and illustrated by practical examples. Because shielding currents in vehicles are not only caused by induced currents but also by functional electrical currents generated by low-voltage power sources, new theoretical studies and experimental observations for the estimation of these currents as a function of the vehicle electrical architecture and circuit characteristics are presented. A primary finding reveals that keeping the resistance of grounding connections low compared to that of the shielding connections is an appropriate but expensive means for limiting the transfer of functional currents in the shielding circuits. Finally, a complete and modular model for the prediction of transient temperatures along the length of cable harness sections is developed and validated based on the outcomes of all previous findings.
25

Modélisation électrothermique de système électrique électronique automobile et pilotage de mosfet intelligents pour protéger les faisceaux, éviter les courts circuits aggravés et diminuer la masse de câblage

Nguyen, Huy Cuong 11 April 2013 (has links)
Sur les différents calculateurs du véhicule, de plus en plus d'organes sont commandés par un interrupteur en silicium (circuit MOSFET) au lieu d'un relais. En plus de la fonction de commutation de puissance, le MOSFET peut comprendre un dispositif de mesure du courant afin de contrôler le pilotage de l'organe et/ou assurer une fonction de diagnostic. On appelle ce type de composant un commutateur intelligent de puissance ou Smart Switch. Il est aussi prévu dans le Smart Switch un dispositif de coupure du courant, en cas d'échauffement interne dû à une surintensité électrique. Avec les dernières avancées technologiques, ces composants peuvent aussi intégrer de la logique de pilotage et une interface de liaison numérique avec un microprocesseur. Cette dernière caractéristique motive lesujet de l'étude afin de définir des lois de protection améliorées contre les échauffements dus à une surintensité électrique.En effet, d’un point de vue de la protection électrique, le MOSFET a été conçu pour obtenir les mêmes caractéristiques qu’un fusible, avec la possibilité supplémentaire d’être réenclenché comme un disjoncteur. Le but est d’étudier les lois de pilotage qui pourraient permettre de mieux suivre les limites thermiques d’un conducteur électrique, en particulier dans les faibles surintensités, de façon à pouvoir diminuer le diamètre (donc le coût) des fils tout en assurant une meilleure protection face aux courts circuits impédants (courts-circuits sur une résistance un peu inférieure à la résistance nominale ducircuit, dans un rapport entre 1 et 3 par exemple). / On various vehicles Electronic Control Unit (ECU), more and more members are controlled bya MOSFET circuits instead of a relay. In addition to the power switching function, the MOSFET maymeasure the current to the steering control of the body and / or to ensure that a diagnostic function. Wecall this type of component a smart power switch or Smart Switch. It is also provided in the SmartSwitch device power failure, if the internal heating caused by electrical current. With the latesttechnology, these components can also integrate control logic and an interface for connection to adigital microprocessor. This last characteristic motivates the subject of study in order to defineimproved protection laws against overheating caused by an electrical current.Indeed, from the point of view of electrical protection, the MOSFET has been designed toachieve the same characteristics as a fuse, with the additional possibility to be reset as a circuit breaker.The aim is to study the control laws that could lead to better monitor the thermal limits of an electricalconductor, especially in low current, so as to reduce the diameter (hence the cost) of son while ensuringbetter protection against short-circuit-impedance (short circuit resistance of a little less than thenominal resistance of the circuit, in a ratio between 1 and 3 for example).
26

L'art rupestre de la phase des cavaliers au Maroc : les sites de Foum Chenna (Vallée du Draa) et du Jebel Rat (Haut Atlas) : Analyse iconographique, thématique et proposition de chronologie / The Rock Art of the Phase of the Horsemen in Morocco : Foum Chenna (Draa Valley) and Jebel Rat (High Atlas) sites : Iconography, Themes and Chronology

Bravin, Alessandra 19 December 2014 (has links)
La première partie présente les caractères généraux de la phase dite « libyco-berbère » dans la littérature. La lecture minutieuse de la bibliographie y est suivie de l'analyse de la notion de « libyco-berbère », d'où il ressort que celle-ci ne permet pas de définir adéquatement la phase en question et qu'il est donc nécessaire de la remplacer par une nouvelle dénomination : la « phase des cavaliers ». Ses traits distinctifs sont passés en revue : introduction du cheval au Maroc, iconographie, style et en replaçant la problématique dans le contexte du Maroc du Ier millénaire av. J.-C. La deuxième partie a pour objet le plateau du Tizi 'n Tirghiyst, examiné sur la base des publications ainsi que de prospections sur le terrain. Cette approche permet de souligner sa complexité et son hétérogénéité, qui inclut la phase des cavaliers et des phases plus anciennes. La méthodologie utilisée comprend l'analyse des éléments iconographiques : le cheval et le harnachement, le cavalier et ses armes, les thèmes. La troisième partie est consacrée à l'examen de Foum Chenna. L'homogénéité du site est flagrante, en dépit de l'existence d'une phase plus ancienne sous-jacente à celle des cavaliers. L'étude minutieuse de ses éléments constitutifs conduit à l'identification de nouveaux thèmes et à la découverte de nouvelles inscriptions libyques.La quatrième partie est une comparaison des deux sites en vue de mettre en évidence analogies et différences et d'identifier les éléments permettant d'avancer une proposition chronologique.Les trois annexes sont respectivement les corpus de gravures de cavaliers du Rat, de Foum Chenna et la totalité des inscriptions libyques de Foum Chenna. / The first part presents the general characters of the phase known as "Libyco-Berber". After a thorough examination of the literature, the very notion of "Libyco-Berber" is analysed and recognized as being inadequate to define the phase and it is proposed a new denomination i.e. the "phase of the horsemen."Its specific characters are analysed from the point of view of the introduction of the horse in North Africa, in terms of iconography and style, all set in the historical context of Morocco's I millennium BC.The second part relates to the plateau of Tizi 'n Tirghiyst, examined on the basis of publications and through an accurate prospecting work. From this approach emerges the complexity and heterogeneity of the rock art of this area that includes not only the phase of the horsemen but also earlier phases. The methodology includes the analysis of the iconographic typical elements: the horse and harness, his weapons and the themes.The third part is devoted to the study of Foum Chenna, in the Draa Valley. It is immediately detected the homogeneity of the site although an older phase is present. The methodology for the analysis is the detailed study of individual elements that led to the identification of new themes and the discovery of new inscriptions in Lybic letters.The fourth part is devoted to the comparison between the two sites, to highlight similarities and differences, to identify elements for a chronology.The three annexes are respectively the corpus of engravings of the horsemen phase of the Rat, of Foum Chenna and the totality of the Libyan inscriptions of this site.
27

Mode I Fracture Toughness of Eight-Harness-Satin Carbon Cloth Weaves for Co-cured and Post-bonded Laminates

Smith, Josh E 01 December 2013 (has links) (PDF)
Mode I interlaminar fracture of 3k 8-Harness-Satin Carbon cloth, with identical fill and weft yarns, pre-impregnated with Newport 307 resin was investigated through the DCB test (ASTM D5528). Crack propagations along both the fill and weft yarns were considered for both post-bonded (co-bonded) and co-cured laminates. A patent-pending delamination insertion method was compared to the standard Teflon film option to assess its applicability to mode I fracture testing. The Modified Beam Theory, Compliance Calibration method, and Modified Compliance Calibration method were used for comparative purposes for these investigations and to evaluate the validity of the proposed Equivalent Stiffness (EQS) method. Crack propagation, in all specimens, proceeded in a run-arrest manner for both delamination directions. Energy dissipation in the form of transverse yarn debonding, matrix deformation, and out of plane crack growth was witnessed for specimens with delaminations along weft yarns. A complete comparison between post-bonded and co-cured laminates was not achieved. The patent pending delamination insertion method was found to cause fewer instances of non-linear crack initiation behavior than the Teflon insert and, when non-linear behavior did occur, it was less prevalent. The EQS method was found to achieve fracture toughness values within 5% of the other three data reduction methods for 63% of the propagation values and achieved conservative values for over 33% of the propagations. Suggestions for future studies aimed at completing the comparisons above are provided in Chapter 5.
28

Toward Equine Gait Analysis : Semantic Segmentation and 3D Reconstruction

Hult, Evelina January 2023 (has links)
Harness racing horses are exposed to high workload and consequently, they are at risk of joint injuries and lameness. In recent years, the interest in applications to improve animal welfare has increased and there is a demand for objective assessment methods that can enable early and robust diagnosis of injuries. In this thesis, experiments were conducted on video recordings collected by a helmet camera mounted on the driver of a sulky. The aim was to take the first steps toward equine gait analysis by investigating how semantic segmentation and 3D reconstruction of such data could be performed. Since these were the first experiments made on this data, no expectations of the results existed in advance. Manual pixel-wise annotations were created on a small set of extracted frames and a deep learning model for semantic segmentation was trained to localize the horse, as well as the sulky and reins. The results are promising and could probably be further improved by expanding the annotated dataset and using a larger image resolution. Structure-from-motion using COLMAP was performed to estimate the camera motion in part of a video recording. A method to filter out dynamic objects based on masks created from predicted segmentation maps was investigated and the results showed that the reconstruction was part-wise successful, but struggled when dynamic objects were not filtered out and when the equipage was moving at high speed along a straight stretch. Overall the results are promising, but further development needs to be conducted to ensure robustness and conclude whether data collected by the investigated helmet camera configuration is suitable for equine gait analysis.
29

Design-Manufacturing Integration : Challenges in change management for new component in-house manufacturing / Integration av design och tillverkning: Utmaningar i uppstart för ny komponenttillverkning

Law Hing Ping, Siet-Ling, Suresh, Rahul January 2022 (has links)
In the highly competitive transportation industry, one way to gain a competitive advantage is to ensure the customer needs are satisfied and tailored according to each customer’s need. Scania’s one of the core values is customers first and believes that the organization is successful only when its customers are successful. In order to achieve their goals, modularization is the key to tailoring the needs of each customer. Considering this factor, an ‘n’ number of variants are required in each module of the trucks and buses offered to the customer. This thesis focuses onthe high voltage cables i.e. VCB cables in Scania’s terms, the cable harnesses are considered as the human nerves and blood vessels for automobiles. Scania is set to produce the VCB cables in-house instead of buying them from the suppliers which is the current method. The thesis focuses on the challenges in change management for new components in-house manufacturing by design-manufacturing integration as a solution. A case study is conducted for the products of electric trucks and buses to understand the design manufacturing integrations. The thesis aims to identify gaps and find where the highest risk exists for deviations in today’s process in terms of design demands, product specification, and product preparation in the production of VCB cables. The case study is conducted, including a literature review and semi-structured qualitative interviews to understand the workflow of how the information is transferred between many cross-functional groups with different business areas such as research & development (R&D) and production. The thesis aims to understand what challenges Scania’s METP (Engineering and process, Battery & VCB production) production group faces while going through a change of organizational structure and interpreting the information via engineering drawings between different stakeholders/groups. A conceptual framework is presented by emphasizing the communication between the R&D groups and the production group by benchmarking the DMI practices for collaborative product development. Furthermore, suggestions for effective drawing methods and increasing the group dynamics between R&D and production are discussed in the thesis. It is hoped that the thesis provides a guide to initiate the stated tasks in results to ensure a smooth production start-up. / I den mycket konkurrensutsatta transportbranschen är ett sätt att få en konkurrensfördel att säkerställa kundens behov genom att skräddarsy produkten efter varje kunds behov. En av Scanias kärnvärdena är “kunderna först” vilket Scania anser vara ett viktigt måtto, speciellt eftersom Scanias framgång bygger på kundens framgång. För att nå sina mål är modularisering nyckeln till framgång. För att lyckas med detta krävs ett "n" antal varianter i varje modul av de produkkter som erbjuds kunden. Detta examensarbete fokuserar på högspänningskablarna. Scania utforskar möjligheten att producera högspänningskablarna i egen regi istället för att köpa dem från leverantörerna, vilket är den nuvarande metoden. Avhandlingen fokuserar på utmaningarna inom förändringsarbetet som krävs för att impementera denna typ av förändring. En fallstudie genomfördes på elektriska lastbilar och bussar för att förstå integrationen av design och tillverkning på detaljerad nivå som tidgare inte hade behövts eftersom externa leverantör tog hand om detaljerna. Avhandlingen syftar till att identifiera luckor och hitta var den största risken finns för avvikelser i dagens process vad gäller designkrav, produktspecifikationer och produktförberedelser vid tillverkning av högspänningskablage. Fallstudien genomfördes, inklusive en litteraturgenomgång och semistrukturerade kvalitativa intervjuer för att förstå arbetsflödet för hur informationen överförs mellan tvärfunktionella grupper. Dessa grupper har olika affärsområden såsom forskning & utveckling (FoU) och produktion. Avhandlingen syftar till att förstå vilka utmaningar Scanias production team (Engineering and process, Battery & VCB production) produktionsgrupp står inför samtidigt som de går igenom en förändring av organisationsstrukturen och tolkar informationen via tekniska ritningar mellan olika intressenter/grupper. Ett konceptuellt ramverk presenteras genom att betona kommunikationen mellan FoU-grupperna och produktionsgruppen genom att jämföra DMI:s praxis för samverkande produktutveckling. Vidare diskuteras förslag på effektiva metoder för teknisk ritning samt att öka gruppdynamiken mellan FoU och produktion. Förhoppningen är att avhandlingen ger en vägledning för att initiera de angivna målen för att säkerställa en smidig produktionsstart.

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