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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.
31

On the Seismic Design of Structures with Tilting Located within a Seismic Region

Valenzuela-Beltrán, Federico, Ruiz, Sonia, Reyes-Salazar, Alfredo, Gaxiola-Camacho, J. 07 November 2017 (has links)
A reliability-based criterion to estimate strength amplification factors for buildings with asymmetric yielding located within a seismic region presenting different soil conditions is proposed and applied. The approach involves the calculation of the mean annual rate of exceedance of structural demands of systems with different levels of asymmetric yielding. Two simplified mathematical expressions are developed considering different soil conditions of the valley of Mexico. The mathematical expressions depend on the ductility of the structural systems, their level of asymmetric yielding, their fundamental vibration period and the dominant period of the soil. In addition, the proposed expressions are compared with that recommended by the current Mexico City Building Code (MCBC). Since the expressions are developed with the help of simplified structural systems, the validity of such expressions is corroborated by comparing the expected ductility demand of multi-degree of freedom (MDOF) structural systems with respect to that of their equivalent simplified systems. Both structural representations are associated with a given annual rate of exceedance value of an engineering demand parameter. The expressions proposed in this study will be incorporated in the new version of the MCBC.
32

Système de reconstruction d'environnement pour une aide au pilotage en environnement naturel / Unstructured environment reconstruction for driver assistance applications

Ricaud, Bruno 20 June 2016 (has links)
Le pilotage de véhicule blindé est rendu difficile par la faible visibilité offerte aux pilotes face aux environnements et aux situations complexes qu’ils doivent traverser.La protection des opérateurs de véhicules militaires et l’intégrité de ces véhicules sont des besoins primordiaux pour l’armée de terre.Afin de répondre à la problématique : sécuriser le pilotage des véhicules militaires avec comme périmètre la définition d’un système de perception d’environnement, nous avons procédé à l’étude au sens large de l’aide au pilotage dans le contexte militaire en environnement naturel et semi-structuré afin de mettre en exergue les moyens et les capteurs utilisables pour réaliser un système d’aide au pilotage.Ainsi, nous offrons une réponse technique pour la réalisation d’un tel système au travers premièrement d’une étude des méthodes et algorithmes existants applicables à notre cas d’application. Ensuite nous définissons les capteurs utilisables avec de telles méthodes. De cet état de l’art, nous définissonsune système répondant à notre problématique et nous expliquons sa mise en pratique au travers de la création d’une plateforme d’expérimentation.Cette plateforme se compose des solutions présentées et permet de valider le concept par l’évaluation des solutions d’acquisition de l’environnement afin d’offrir les données nécessaires à une aide au pilotage.Puis, l’étude des moyens d’analyse de cet environnement offre des pistes de réflexion sur le futur système d’aide au pilotage.Enfin, une l’étude d’un moyen alternatif de restitution de l’information à l’opérateur complète la solution présentée en offrant une piste de réflexion sur l’impact de la restitution dans les performances des opérateurs. / Armored vehicule driving is difficult because of low visibility given to pilots in tough environnements conditions and complex situations they have to manage.Soldiers safety and vehicle integrity are part of main topics for French “Armée de Terre”. To answer the problem Make the driving of military vehicles safer by improving environnement perception through driver asssistance systems, we study driving assistance in unstructured environnemnt by looking for sensors and methods which are suitable to realize such a system.First, we study existing methods and algorithms which fit our application case. Conclusion of this study is the definition of our system.Second, thanks to the previous study we explain the creation of an experimentation platform allowing evaluation of our concept. Data obtained from reconstruction are then exploited through environment analysis to bring obstacle extraction methods.Third, study of an alternative display solution is exposed and complete this work in explaining impact of restitution in operating cycle.
33

Generation of Topological Interlocking Configurations from a Geometric Approach

Andres M Bejarano Posada (8770007) 28 April 2020 (has links)
A Topological Interlocking Configuration (TIC) is an assembly where the shape and alignment of the blocks define the kinematic constraints. Conventional TICs are single-layered structures made of convex blocks. The interface between the blocks in an assembly is face-to-face contact. The traditional convention disregards the use of joinery, adhesive, or other mechanisms that keep two pieces next to each other. However, TICs require a support structure that prevents the lateral strain of the blocks.<br><br>The generation process of a TIC starts with a surface tessellation that describes a geometric domain. Each tile in the tessellation represents a traversal section of a block. For regular tessellations and uniform generation parameters, such sections lie in the middle of their respective blocks. Additionally, such conditions guarantee the blocks align adequately with each other. If one of such conditions does not hold, then the resultant blocks may not be aligned. Furthermore, there could be overlapping between the blocks, which makes a TIC invalid.<br><br>Traditionally, the generation parameters are angle values set at the edges of the tiles. The angles must match between tiles such that each block in the assembly has a geometry that imposes kinematic constraints to its neighboring blocks. Using the same angle values on regular and semi-regular tessellation produces feasible blocks. That is not the case for non-regular tessellations, curvilinear surfaces, and free-form 3D meshes. In such cases, the generation method must find specific angle values to design the blocks and reduce overlapping.<br><br>In this thesis, we propose a TIC generation framework focused on the generation of valid interlocking assemblies based on multiple types of surface tessellations. We start with the Height-Bisection method, a TIC generation approach that uses the distances from a tile to its respective evolution sections as the generation parameters. The method considers the bisector vectors between two tiles to define the parameters that generate aligned blocks to each other. We expand the generation model to a complete pipeline process that finds feasible generation parameters. The pipeline includes clipping parameters and methods in case that overlapping between blocks cannot be avoided.<br><br>Additionally, we describe a generalization of the mid-section evolution concept to include multiple evolution steps during the generation process. Our approach considers the angles and distances required to generate infinitely many TICs, including shapes that are not possible using the traditional generation method and the Height-Bisection method. Finally, we consider the interlocking assemblies that cannot maintain static equilibrium due to the shape of the surface tessellation. We consider the Structure Feasibility Analysis method to find the location and magnitude of the minimum tension forces that guarantee a TIC will reach a static equilibrium state. We describe how to update the generation parameters according to the results of the feasibility analysis. Our results show that the proposed pipeline generates valid TICs based on different surface tessellations, including closed and free-form shapes.
34

Multifunkční naklápěcí pánev / Mutifunction tilting pan

Kopecký, David January 2009 (has links)
The subject of this diploma thesis is costructional design gastronomical multifunction tilting pan with capacity 100 l. CAD model of equipment is designed in Autodesk Inventor 2008. Engineering design of equipment is supported by analytical calculation as well as strtuctural analyses in software Ansys Workbench 11.
35

Medial tilting of the joint line in posterior stabilized total knee arthroplasty increases contact force and stress / Posterior stabilized型人工膝関節置換術における関節面の内方傾斜により接触力および接触応力は上昇する

Tanaka, Yoshihisa 25 March 2019 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21674号 / 医博第4480号 / 新制||医||1036(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 安達 泰治, 教授 黒田 知宏, 教授 戸口田 淳也 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
36

A Tilting Trike with Rider Tuneable Stability and Handling for lmproved Safety

Dressel, Andrew E., Moore, Jason K. 02 January 2023 (has links)
The potential advantages of tilting trikes have been tantalizing for years: they can lean like a bike so that they do not have to be low, wide, or slow in turns; and they can keep the rider upright like a trike when stopped or going slow. Implementing this functionality, however, has been somewhat problematic. Many tilting trikes have been built in which the extra wheel only offers some redundant traction, in the case of inconsistent friction with the road surface. Some have been built with a so-called ''tilt-lock', in which the third wheel can also act as a kickstand to hold the trike rigid when stopped. A few tilting trikes have been built with sophisticated sensors, actuators, and control algorithms to assume the proper tilt angle in every situation, and the motorcycle press breathlessly announces the latest patent filings in this area from major motorcycle manufacturers. [from Introduction]
37

Tilting trains : Technology, benefits and motion sickness

Persson, Rickard January 2008 (has links)
Carbody tilting is today a mature and inexpensive technology allowing higher speeds in curves and thus reduced travel time. The technology is accepted by most train operators, but a limited set of issues still holding back the full potential of tilting trains. The present study identifies and report on these issues in the first of two parts in this thesis. The second part is dedicated to analysis of some of the identified issues. The first part contains Chapters 2 to 5 and the second Chapters 6 to 12 where also the conclusions of the present study are given. Chapters 2 and 3 are related to the tilting train and the interaction between track and vehicle. Cross-wind stability is identified as critical for high-speed tilting trains. Limitation of the permissible speed in curves at high speed may be needed, reducing the benefit of tilting trains at very high speed. Track shift forces can also be safety critical for tilting vehicles at high speed. An improved track standard must be considered for high speed curving. Chapters 4 and 5 cover motion sickness knowledge, which may be important for the competitiveness of tilting trains. However, reduced risk of motion sickness may be contradictory to comfort in a traditional sense, one aspect can not be considered without also considering the other. One pure motion is not the likely cause to the motion sickness experienced in motion trains. A combination of motions is much more provocative and much more likely the cause. It is also likely that head rotations contribute as these may be performed at much higher motion amplitudes than performed by the train. Chapter 6 deals with services suitable for tilting trains. An analysis shows relations between cant deficiency, top speed, tractive performance and running times for a tilting train. About 9% running time may be gained on the Swedish line Stockholm – Gothenburg (457 km) if cant deficiency, top speed and tractive performance are improved compared with existing tilting trains. One interesting conclusion is that a non-tilting very high-speed train (280 km/h) will have longer running times than a tilting train with today’s maximum speed and tractive power. This statement is independent of top speed and tractive power of the non-tilting vehicle. Chapters 7 to 9 describe motion sickness tests made on-track within the EU-funded research project Fast And Comfortable Trains (FACT). An analysis is made showing correlation between vertical acceleration and motion sickness. However, vertical acceleration could not be pointed out as the cause to motion sickness as the correlation between vertical acceleration and several other motions are strong. Chapter 10 reports on design of track geometry. Guidelines for design of track cant are given optimising the counteracting requirements on comfort in non-tilting trains and risk of motion sickness in tilting trains. The guidelines are finally compared with the applied track cant on the Swedish line Stockholm – Gothenburg. Also transition curves and vertical track geometry are shortly discussed. Chapters 11 and 12 discusses the analysis, draws conclusions on the findings and gives proposals of further research within the present area. / QC 20101119
38

Vortex tilting and the enhancement of spanwise flow in flapping wing flight

Frank, Spencer 01 December 2011 (has links)
In summary the tilting mechanism helps to explain the overall flow structure and the stability of the leading edge vortex.; The leading edge vortex has been identified as the most critical flow structure for producing lift in flapping wing flight. Its stability depends on the transport of the entrained vorticity into the wake via spanwise flow. This study proposes a hypothesis for the generation and enhancement of spanwise flow based on the chordwise vorticity that results from the tilting of the leading edge vortex and trailing edge vortex. We investigate this phenomenon using dynamically scaled robotic model wings. Two different wing shapes, one rectangular and one based on Drosophila melanogaster (fruit fly), are submerged in a tank of mineral oil and driven in a flapping motion. Two separate kinematics, one of constant angular velocity and one of sinusoidal angular velocity are implemented. In order to visualize the flow structure, a novel three dimensional particle image velocimetry system is utilized. From the three dimensional information obtained the chordwise vorticity resulting from the vortex tilting is shown using isosurfaces and planar slices in the wake of the wing. It is observed that the largest spanwise flow is located in the area between the chordwise vorticity of the leading edge vortex and the chordwise vorticity of the trailing edge vortex, supporting the hypothesis that the vortex tilting enhances the spanwise flow. Additionally the LEV on the rectangular wing is found to detach at about 80% span as opposed to 60% span for the elliptical wing. Also, two distinct regions of spanwise flow, one at the base and one at the tip, are observed at the beginning of the sinusoidal kinematic, and as the velocity of the wing increases these two regions unionize into one. Lastly, the general distribution of vorticity around each wing is found to be nearly the same, indicating that different wing shapes do not greatly affect the distribution of vorticity nor stability mechanisms in flapping flight.
39

Analysis the behaviour of spread footing for highway bridge foundation

Mahasantipiya, Sedtha January 1995 (has links)
No description available.
40

Nonlinear dynamic analysis of vertical rotors with tilting pad journal bearings

Benti, Gudeta January 2021 (has links)
Swedish Hydropower Centre - SVC

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