In this thesis, two problems are studied. The first problem is to find a technique to generate a particular type of failure information in real time for large flexible space structures (LFSSs). This problem is solved by using structured residuals. The failure information is then incorporated into an existing fault tolerant control scheme. The second problem is a ``spin-off'' from the first. Although the H-infinity sliding mode observer (SMO) cannot be applied to the colocated LFSS , its ability to do robust state and fault estimation of the SMO makes it suitable to be used in an integrated fault tolerant control (IFTC) scheme. We propose to combine the H-infinity SMO with a linear fault accommodation controller. Our IFTC scheme is closed loop stable, suppresses the effects of faults and enjoys enhanced robustness to disturbances. The effectiveness of the IFTC is illustrated through the control of a permanent magnet synchronous motor under actuator fault.

Este trabalho apresenta um estudo sobre o comportamento de treliças espaciais formadas por elementos tubulares de seção circular, com ênfase no desempenho das tipologias de ligação utilizadas no Brasil. Foram ensaiadas experimentalmente 9 treliças espaciais com vãos de 7,5 x 15,0m e uma de 7,5m x 7,5m com altura de 1,5m, variando-se o tipo de ligação entre barras, com o objetivo de caracterizar e comparar o comportamento dos sistemas de ligações mais comuns (nó típico – extremidade estampada, nó de aço e nó com chapa de ponteira).A análise teórica, via elementos finitos, tem como objetivo aferir a validade dos modelos numéricos normalmente utilizados e refiná-los incluindo as características do comportamento estrutural observadas em ensaio. A análise numérica segue duas abordagens: análise global da estrutura incluindo os efeitos não-lineares, excentricidade na ligação e variação de seção nas extremidades das barras; com isso o comportamento das treliças ensaiadas foi representado de forma satisfatória. A análise do comportamento do nó típico, modelado tridimensionalmente com elementos de casca, possibilitou analisar a interação entre as barras na região nodal por meio de elementos de contato. Com esta modelagem, apesar das simplificações, foi possível reproduzir o modo de colapso observado experimentalmente. / This paper presents a study of the behavior of tubular circular section space trusses with the main emphasis placed on the performance of the various truss typologies used in Brazil. Nine space trusses with plan dimensions of 7.5m x 15.0m and one with plan dimensions of 7.5mx7.5m and height of 1.5m were tested. The joint type was varied with the objective to characterize and compare the behavior of the more common types of connection systems (typical node – stamped end, steel node, and end plate node). The theoretical analysis employing finite elements was adopted mainly to ascertain the validity of various numerical models commonly employed and hence refining them by including the some basic characteristics of the observed structural behavior.The numerical analysis employed was based on two methodologies: a global structural analysis that takes into account the effects of non-linearity, eccentricities at connection, and the variation of the end bars cross section. In this manner the actual behavior of the tested trusses was well represented. The analysis of the behavior of a typical node, modeled using tri-dimensional finite shell elements made it possible to analyze the interaction between bars that converge at the nodal region by applying contact elements. Despite it simplicity, predicted results of the collapse mode obtained by using the proposed model, very well reproduce the experimental observation.

Inflatable structures have been a subject of renewed interest in recent years for space applications such as communication antennas, solar thermal propulsion, and entry/landing systems. This is because inflatable structures are very lightweight and on-orbit deployable. In addition, they have high strength-to-mass ratio and require minimal stowage volume, which makes them especially suitable for cost-effective large space structures. An inflated toroidal structure (torus) is often used there in order to provide structural support. For these structures to be effective, their vibration must be controlled while keeping the weight low. Piezoelectric materials have become strong candidates for actuator and sensor applications in the active vibration control of such structures due to their lightweight, conformability to the host structure, and distributed nature. In this study, our main focus is to understand the dynamic characteristics of an inflatable torus and to control its vibration using piezoelectric actuators and sensors. The first part of this study is concerned with theoretical formulations. We use Sanders' shell theory to derive the governing equations of motion for a shell subjected to pressure. To take into account the prestress effects of internal pressure, we use geometric nonlinearity, and to model the follower action of pressure force, we consider the work done by internal pressure during the vibration of the shell. These equations are then specialized to obtain approximate equations presented by previous researchers. We extend this analytical formulation to derive the equivalent forces due to piezoelectric actuators in unimorph and bimorph configurations and include their mass and stiffness effects in the governing equations. A sensor equation is also developed for the shell. The actuator and sensor equations are then written in terms of modal displacements and velocities so as to evaluate their interactions with different vibratory modes. In the second part, we focus on numerical studies related to an inflated torus. At first, we perform a free vibration analysis of the inflated torus using Galerkin's method. We study how different parameters (aspect ratio, internal pressure, and wall-thickness) of the inflated torus affect the natural frequencies and mode shapes of the inflated torus. We compare the results obtained from the theory used in this research with the results from different approximate theories and commercial finite element codes. The results suggest that the use of an accurate shell theory and pressure effect is very important for the vibration analysis of an inflated torus. Next, the modal behaviors of piezoelectric actuator and sensor are analyzed. A detailed study is done in order to understand how the size and location of actuator and sensor affect the modal forces, the modal sensing constants, and the overall performance for all the considered modes. In order to determine the optimal locations and sizes of actuators and sensors, we use a genetic algorithm. Natural frequencies and mode shapes are calculated considering the passive effects of actuators and sensors. Finally, we attempt the vibration control of the inflated torus using the optimally designed actuators and sensors and sliding mode controller/observer. The numerical simulations show that piezoelectric actuators and sensors can be used in the vibration control of an inflatable torus. The robustness properties of the controller and observer against the parameter uncertainty and disturbances are verified. / Ph. D.

Despite the abundance of descriptive studies on the urban development plans of Ankara, analytical studies on specific features of these plans, especially on implementation and modification processes are scarce. This study examines the green space structure brought in Jansen&rsquo / s 1932 development plan of Ankara, the way it was implemented and the modifications that a component of this structure was subject to. The 1932 Jansen plan is a holistic and comprehensive plan that contained a conceptual green space structure, integrated with other public uses and social facilities. An in depth evaluation of Jansen&rsquo / s 1928 and 1932 plans is made and a typology of the components of the green space structure is formed. It is found that the plan principles and the components of the green space structure of Jansen&rsquo / s plan for Ankara are perfectly congruent with German planning approach and principles of the time. From the analysis of the plan modifications of the G&uuml / ven Park- Tandogan Greenway a typology of modifications is developed. It is argued that the 1933 and 1957 development laws and regulations lacked definitions for realizing and sustaining the green space types proposed by Jansen, which consequently lead to their modifications. In reality the land ownership status, &ldquo / h&acirc / l&icirc / arazi&rdquo / , under which the greenways of Jansen plan were placed, illustrates the difficulty of translating these spatial categories into the Turkish legislative framework. In this respect, this study is an attempt to provide a contribution to the study of green spaces in relation with the implementation of development plans.

The main goal of this study was to investigate space structure of pure pine stands, to assess optimal parameters of trees crown depending on stand age. The study was carried out in seven trials of 2 – 8 age classes pine stand. Trees crown horizontal projection area, the overlapping of crown, tree DBH, 5 years increment of diameter, tree developing class was measured of 200 trees in every trial. It was investigated that maximally possible crown projection area makes up from 12,0 thousand m2/ha to 6,5 thousand m2/ha while the age of stands changes from 2 to 8 age class. Depending upon the age of pine stand, maximally possible crown cover area makes up from 8,5 thousand m2/ha to 6,2 thousand m2/ha and decreases with increasing of stand age. The area of inevitable openings comprises 15-38 % of a forest area and increases with increasing of stand age. The overlapping comprises 43-6 % and decreases with increasing of stand age. The area of pine crown increases from 1,2 to 8,8 m2 while the age of stands changes from 2 to 8 age class. In the same age class the area of tree crown depends on tree developing class. The crown area of well-developed trees (class A) is 1.7-1.9 times bigger then crown area of poor-developed trees (class B) and 2.7-4.6 times bigger then crown area of trees being developed in a depressed state (class C). The crown area of vigorously-developed trees (class A’) is 1.8-3.5 times bigger than crown area of well-developed trees (class A). 1 m2 of the crown area... [to full text]

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The locality is situated in the city quarter Brno-Židenice in close proximity of the railway line connecting Brno and Česká Třebová. The area is delimited by the Bubeníčkova Street from the South, the Koperníkova Street from the East, by Lazaretní Street from the North and by a road copying the railway line from the West. The elemental form of the projected compound is divided into three blocks by pass-through axes. The blocks are interconnected with a common basement where underground car park is located. The blocks have up to six floors above ground. On the first floor, there is a variety of commercial spaces for shops and restaurants and in the middle there is a supermarket. In the northern object, there are situated different types of amenities (kinder-garden, leisure activities for children, spa) on the second and higher floors. On the top floor of this object we can find the flats as well as in the middle building from the second floor. The commercial areas, offices and library are situated in the southern block.

The subject of the diploma thesis is the architectural study of the mix-used urban housing situated closed to the Brno city centre. The design will allow mixing of greater amount of different functions on a relatively small built-up area, which will reduce the requirements on transport and provide the inhabitant with various forms of housing, services and employment. The mass and spatial solution respects the surrounding city blocks on south and the mass increase to the north industrial zone. The mass defines the area and respect noise protection zone on housing development. The shape of object's ground plan is based on the area, which is divided by four axes of pedestrian paths. The basic matter of object is divided into four blocks linked by common internal square. The mass solution provides private, semi-private and public courtyards.

The territory is located in the city of Brno, district Trnitá on the embankment of the river Svitava. The subject of the diploma thesis is the architectural study of the design of the urban spatial structure with intensive use of city urban area, designed in pre-diploma project, which preceded diploma thesis. The design will allow mixing of greater amount of different functions on a relatively small built-up area, which will reduce the requirements on transport and provide the inhabitant with various forms of housing, services and employment. The shape of object's ground plan is based on area, which is connected from three sides to access roads. The mass and spatial solution respects the surrounding buildings and uses existing bike trails and sidewalks in the southeastern part of the area. The basic matter of object is divided by three axes passing through the building, into three blocks linked by common internal block. This creates a square with a tree-lined atrium with seating under the trees. The shape of these three blocks is further formed by removing of the mass, which results into forming of atriums, terraces and balconies, which brings natural light into the interior while allowing illumination of the patio and surrounding buildings within the territory. This spatial structure is horizontally divided by functions. Designed here are underground public garages, passages with shops, services, administration / commerce and housing. Despite the diversity of functions, for the facade was chosen a unified character of white horizontal lines contrasting with the dark gray lines of windows and facade cladding.