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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.
81

The use of a geographic information system to investigate the effect of land-use change on wattled crane Bugeranus carunculatus breeding productivity in KwaZulu-Natal, South Africa.

Coverdale, Brent Miles. January 2006 (has links)
The Wattled Crane, Bugeranus carunculatus Gmelin, is presently classified as being 'Critically Endangered' within South Africa according to the Eskom Red Data book of Birds of South Africa, Lesotho and Swaziland, with a population of a meagre 235 individuals. Of this, 85% occur within KwaZulu-Natal and live predominantly on privately owned agricultural land. As a result thereof, Wattled Cranes and agriculture compete for the same resources. Up until now, the loss of viable habitat, as a result of agricultural development and afforestation, has been mooted as being the primary reason for the decline in numbers of the species. The advancements in the Geographical Information Systems field have enabled conservationists to acquire data, especially pertaining to habitat requirements, which were previously unattainable. This improved data acquisition is enabling for more informed decision making and better allocation of resources. The study therefore attempts to make use of a Geographical Information System to determine whether or not differences exist within the home ranges of active and historical Wattled Crane nesting sites, utilising the National Land cover database. The updated Land cover data for South Africa, although not completed at the time the present study took place, allowed for the interrogation of the various Land cover classes within an estimated home range. Natural Grassland was the predominant Land cover type within both active and historical home ranges, whilst both active and historical home ranges were subject to some degree of transformation. The potential impact of management practices in and around nesting sites warrants further investigation because this could not be determined through the analysis of land cover. / Thesis (M.Env.Dev.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.
82

Virtual Holonomic Constraints: from academic to industrial applications

Ortiz Morales, Daniel January 2015 (has links)
Whether it is a car, a mobile phone, or a computer, we are noticing how automation and production with robots plays an important role in the industry of our modern world. We find it in factories, manufacturing products, automotive cruise control, construction equipment, autopilot on airplanes, and countless other industrial applications.         Automation technology can vary greatly depending on the field of application. On one end, we have systems that are operated by the user and rely fully on human ability. Examples of these are heavy-mobile equipment, remote controlled systems, helicopters, and many more. On the other end, we have autonomous systems that are able to make algorithmic decisions independently of the user.         Society has always envisioned robots with the full capabilities of humans. However, we should envision applications that will help us increase productivity and improve our quality of life through human-robot collaboration. The questions we should be asking are: “What tasks should be automated?'', and “How can we combine the best of both humans and automation?”. This thinking leads to the idea of developing systems with some level of autonomy, where the intelligence is shared between the user and the system. Reasonably, the computerized intelligence and decision making would be designed according to mathematical algorithms and control rules.         This thesis considers these topics and shows the importance of fundamental mathematics and control design to develop automated systems that can execute desired tasks. All of this work is based on some of the most modern concepts in the subjects of robotics and control, which are synthesized by a method known as the Virtual Holonomic Constraints Approach. This method has been useful to tackle some of the most complex problems of nonlinear control, and has enabled the possibility to approach challenging academic and industrial problems. This thesis shows concepts of system modeling, control design, motion analysis, motion planning, and many other interesting subjects, which can be treated effectively through analytical methods. The use of mathematical approaches allows performing computer simulations that also lead to direct practical implementations.
83

[en] STUDY OF PENDULAR ACTIVE SYSTEMS FOR THE TRANSPORT IN VEHICLES OF LOADS SENSIBLE OF DISTURBANCES / [pt] ESTUDO DE SISTEMAS ATIVOS PENDULARES PARA O TRANSPORTE EM VEÍCULOS COM CARGAS SENSÍVEIS A DISTÚRBIOS

PAULO ROBERTO ROCHA AGUIAR 08 May 2002 (has links)
[pt] Talhas são dispositivos mecânicos muito usados para carregar e descarregar objetos e/ou transportá-los em indústrias e em armazéns. O movimento da talha é controlado por um operador ou é programado e controlado automaticamente. Nos dois casos, o movimento da talha causa balanços indesejáveis da carga e da garra, levando a um tempo ocioso antes do agarramento e do posicionamento da carga, bem como podendo ocasionar o escape dos cabos das ranhuras das polias, sendo pois um problema de segurança. Este trabalho apresenta o desenvolvimento de modelos matemáticos que representam um sistema tipo pêndulo embarcado em um veículo que suporta uma carga suspensa por um ou mais cabos. A estrutura na qual se prende o ponto de fixação do cabo de sustentação, chamada de trolley, movimenta-se nas direções horizontal e vertical em função de excitações que são oriundas do movimento sofrido pelo veículo. Este veículo é representado por um outro modelo que está acoplado ao sistema do pêndulo. São projetadas leis de controle para cada um dos modelos criados para que sejam minimizadas as acelerações da carga suspensa. Um dos modelos criados representa uma maca com paciente, suspensos por cabo numa ambulância. A lei de controle deve dar conforto a este paciente ao ser transportado. Para avaliar e validar os modelos dinâmicos e os projetos de controle são realizadas várias simulações e análises experimentais. / [en] Cranes are very used mechanical devices to load and to unload objects and/or to carry them in industries and warehouses. The movement of the crane is controlled by an operator or is programmed and controlled automatically. In the two cases, the movement of the crane cause undesirable swings of the load and claw, leading to an idle time before the grasping and the positioning of the load, as well as being able to cause to the escape of the ropes of the grooves of the pulleys. This can cause a security problem. This work presents the development of mathematical models that represent a system like a pendulum, where the load is suspended by one or more ropes. The structure in which the point of attachment of the rope of sustentation, called trolley, have motion in the horizontal and vertical directions. These excitements are deriving of the movement suffered from another model that represents a vehicle that is coupled to the system of the pendulum. Laws of control are projected for each model created so that the accelerations of the suspended load are minimized. One of the models created represents a stretcher with patient suspended by rope in an ambulance. The control law must give comfort to this patient in the transport. To evaluate and to validate the dynamic models and the designs of control created some simulations and experimental analyses are carried through.
84

Transformation of the artifact : adaptive reuse of the LaSalle Coke Tower in Montreal, Quebec

Weryk, Michael E. 05 1900 (has links)
The LaSalle Coke Tower is an existing structure located on a fifty-five foot strip of land bordering the south edge of the Lachine Canal and the north side of St. Patrick's St. (Montreal, Quebec). The railway passes through the structure at its base. Built at the turn of the century, the crane was used to hoist coal from barges to an elevated conveyor that carried it across the street to Cote-St.-Paul Gas Works. It is approximately 15 storeys high (167'). The Lachine Canal serviced the cause of industry from its completion in 1824 to the opening of the St. Lawrence Seaway in 1959 at which time industry slowly began to abandon the Lachine Canal area. The basic premise of the design project revolved around both preservation and development of Tour LaSalle Coke (LaSalle Coke Tower). Regarding preservation, it was the state of abandonment that was to be preserved, allowing for a sense of mobility, vagrant roving, free time, and liberty. Architectural production within the abandoned site must respond to the rhythms and flows of the passing of time and the loss of limits. The two principal components include a provision for discovery (architecture as a heuristic device) and an archive component housing historical documents relevant to the tower and it's surrounding context (the Lachine Canal). The essence of the project was to develop this type of site without destroying its character and without detracting from its historical significance. Careful consideration was essential to negotiate between development and preservation. A broader interpretation of heritage preservation was necessary: moving beyond the isolated monument to include territory which characterizes a particular place. In this instance tire place consisted of the extreme linear space of the canal and its adjacent properties in addition to the remnant architectural artifact of the tower. The state of abandonment is a part of the history of the site. The provision for discovery is made through the use of stairs and an elevator, allowing visitors uninhibited access to the tower. This provision allows for multiple levels of interaction with the artifact, from the short visit to a more comprehensive survey of the object. The archive component is a smallscale intervention thereby minimizing the impact of specialized components (or private spaces) which limit the sense of mobility, vagrant roving, free time and liberty. For the same reason, the food service and primary toilet facility is located 'off site' approximately 320 feet to the east. The goal was to retain the basic features of the artifact while providing for a means of discovery and documentation of a National Historic Landmark. / Applied Science, Faculty of / Architecture and Landscape Architecture (SALA), School of / Graduate
85

Crane control of an automatic storage & retrieval system

Chieng, Joseph C. January 1983 (has links)
The nature of how an Automatic Storage & Retrieval System stacker crane moves through the aisle, between picking and storing operations, is analyzed through a simulation model. A continuous SLAM model simulates the performance of a single aisle Automatic Storage & Retrieval System stacker crane under various control conditions. Crane speed, acceleration rate, job arrival rate, and discrete or continuous interrupt sensing are the variables examined within the model. The performance level of the system is observed while altering the control. / M.S.
86

Pulse rate, pulse pattern, and onset distance effects on subject braking responses while using an auditory collision warning signal

Pizarro, David Victor 17 January 2009 (has links)
This study examined the effect that pulse rate, pulse pattern, and onset distance had on the performance of an auditory warning signal. The warning signal's purpose was to alert mobile crane operators of their proximity to overhead power lines. The study consisted of two experimental phases. The first phase consisted of three sections; A) development and construction of the PWD's auditory warning signal. B) development of the experimental tasks and a pilot study, and C) an examination of the workload level of the secondary tracking task. Phase two consisted of a full factorial experiment which examined the performance effects caused by pulse rate range, pulse pattern, and onset distance manipulations. The experimental task required subjects to monitor an auditory warning system while simultaneously operating a single-axis driving simulation task. Subjects were required to initiate braking responses based on the information conveyed through the auditory collision warming system. In addition, subjective ratings were obtained to compare subjects’ actual performance using the warning system to their subjective preferences. Results indicate that subjects performed optimally under warning signals with moderate onset distances and low pulse rates. The pulse pattern did not have a large impact on subjects' performance across the various warning signals. Overall, it was concluded that a pulsing auditory warning signal comprised of a moderate onset distance and low pulse rate was subjectively preferred and would work effectively as a proximity warning device for mobile cranes. / Master of Science
87

Optimisation des systèmes de stockage de conteneurs dans les terminaux maritimes automatisés / Optimization of container handling system at automated maritime terminals

Dkhil, Hamdi 05 October 2015 (has links)
Notre travail s’intéresse à un cas très particulier des terminaux à conteneurs, il s’agit des terminaux à conteneurs automatisés, qui en plus des véhicules autoguidés, sont équipés de grues de quai et de grues de stockage automatiques (grues de cour), ce qui pousse souvent les scientifiques à considérer les problèmes d’ordonnancement intégré dans les terminaux automatisés ou semi-automatisés. Nous traitons dans ce travail l’optimisation de plusieurs objectifs pour stocker les conteneurs d'une manière efficace et réaliste. Nous traitons le problème d’ordonnancement intégré considérant les trois équipements d’un terminal à conteneurs automatisé soient: les véhicules autoguidés, les grues de quai et les grues de baie (éventuellement). L’objectif principal de cette étude est la minimisation du coût opérationnel de stockage de conteneurs dans un terminal maritime automatisé / AIn our study, we consider two optimization problems in automated container terminals at import; the first is the vehicle scheduling problem; and the second is the integrated problem of location assignment and vehicle scheduling. In the first part of our study, we propose different traffic layout adapted to the two studied problems and to every kind of automated container terminal. We also introduce relevant reviews of literature treating the optimization of container handling systems at maritime terminal, the optimization of general automated guided vehicle system and the multi-objective optimization in general, and in particular context of maritime container terminals. In the second part, we resolve the planning of QC-AV-ASC (Quay Cranes-Automated Vehicles - Automated Stacking Cranes). We present an effective model for every kind of traffic layout. Moreover, we propose an efficient bi-objective model which is important to determine the optimal storage time and the minimal number of required AVs. CPLEX resolutions are used to prove the efficiency of our modelling approach. In the third part of this thesis, we explore a problem which has not been sufficiently studied: the integrated problem of location assignment and vehicle scheduling (IPLAVS), in Maritime Automated Container Terminal (MACT) at import. This part represents a new and realistic approach of MACT optimization considering mono-objective and multi-objective aspect.
88

Modelagem paramétrica de pórticos rolantes: estabilidade estrutural e otimização. / Gantry cranes parametric modeling: structural stability and optimization.

Sobue, Gustavo 29 July 2005 (has links)
O objetivo deste trabalho é desenvolver uma ferramenta de automatização de cálculo para projeto estrutural de pórticos rolantes. Com o apoio da geração automática de um modelo de elementos finitos e um memorial de cálculo, o projeto estrutural desses equipamentos pode ser rapidamente verificado quanto ao limite de escoamento do material e resistência à flambagem. Optou-se pela utilização do método dos elementos finitos para o cálculo estrutural, pois se trata de uma ferramenta de cálculo moderna, que permite avaliar soluções para as quais não há ferramentas analíticas disponíveis. Porém, o tempo para geração de modelos de cálculo pode ser longo em relação ao cronograma do projeto, principalmente se houver a necessidade de se alterar a geometria inicial ou se existirem várias condições de carregamento a serem analisadas. A utilização de um pré-processador permite que várias alternativas sejam analisadas para escolha da que melhor atenda aos requisitos de projeto e de custo. Assim como ocorre com outras estruturas de engenharia, não existe uma equação de dimensionamento, mas sim de verificação; as estruturas ótimas são procuradas por tentativa e erro com base na experiência do projetista. Para facilitar a busca de uma estrutura ótima, implementou-se também uma rotina para otimizar as estruturas metálicas do pórtico. Adotou-se como função objetivo nesta implementação a minimização da massa, o que no caso dos pórticos implica em redução da área da seção transversal das vigas. Como restrições a esta redução adotaram-se o limite de escoamento do material e limite de estabilidade da estrutura (flambagem). Foram utilizados os aplicativos Excel (Microsoft), Ansys (Ansys Inc.) e Mathcad (Mathsoft) de maneira integrada a fim de se obter uma interface amigável, uma análise estrutural confiável e a elaboração automática de um memorial de cálculo. / The objective of this work is to develop a tool to generate an automatic structural design of gantry cranes. With an automatic generation of finite element models and also a design report, this routine allows a fast verification against yield of material and structural instability. The use of the finite element method was chosen for the structural design because it is a modern analysis tool that permits the evaluation of geometric configurations for which there are no analytical formulations available. However, the time necessary to build these models may be high, especially if there are changes in the initial geometry and many load cases. The use of a pre-processor allows the evaluation of a series of geometric alternatives, within which would be chosen the one with the lowest cost that attends the client’s specifications. Like many other engineering problems, there are no direct equations to find an adequate structure; there are only verification procedures available; the optimum structures are searched by trial and error, based on the designers’ experience. To accelerate this search process, an optimization routine was developed. Mass reduction was adopted as the objective function, which leads to reduction of the cross section area of the beams. Yield strength and buckling were adopted as restrictions to this optimization. Excel (Microsoft), Ansys (Ansys Inc) and Mathcad (Mathsoft) software were integrated to provide an user-friendly interface, reliable structural analysis and an automatic report generation.
89

Robust Control For Gantry Cranes

Costa, Giuseppe, Electrical Engineering & Telecommunications, Faculty of Engineering, UNSW January 1999 (has links)
In this thesis a class of robust non-linear controllers for a gantry crane system are discussed. The gantry crane has three degrees of freedom, all of which are interrelated. These are the horizontal traverse of the cart, the vertical motion of the goods (i.e. rope length) and the swing angle made by the goods during the movement of the cart. The objective is to control all three degrees of freedom. This means achieving setpoint control for the cart and the rope length and cancellation of the swing oscillations. A mathematical model of the gantry crane system is developed using Lagrangian dynamics. In this thesis it is shown that a model of the gantry crane system can be represented as two sub models which are coupled by a term which includes the rope length as a parameter. The first system will consist of the cart and swing dynamics and the other system is the hoist dynamics. The mathematical model of these two systems will be derived independent of the other system. The model that is comprised of the two sub models is verified as an accurate model of a gantry crane system and it will be used to simulate the performance of the controllers using Matlab. For completeness a fully coupled mathematical model of the gantry crane system is also developed. A detailed design of a gain scheduled sliding mode controller is presented. This will guarantee the controller's robustness in the presence of uncertainties and bounded matched disturbances. This controller is developed to achieve cart setpoint and swing control while achieving rope length setpoint control. A non gain scheduled sliding mode controller is also developed to determine if the more complex gain scheduled sliding mode controller gives any significant improvement in performance. In the implementation of both sliding mode controllers, all system states must be available. In the real-time gantry crane system used in this thesis, the cart velocity and the swing angle velocity are not directly available from the system. They will be estimated using an alpha-beta state estimator. To overcome this limitation and provide a more practical solution an optimal output feedback model following controller is designed. It is demonstrated that by expressing the system and the model for which the system is to follow in a non-minimal state space representation, LQR techniques can be used to design the controller. This produces a dynamic controller that has a proper transfer function, and negates the need for the availability of all system states. This thesis presents an alternative method of solving the LQR problem by using a generic eigenvalue solution to solve the Riccati equation and thus determine the optimal feedback gains. In this thesis it is shown that by using a combination of sliding mode and H??? control techniques, a non-linear controller is achieved which is robust in the presence of a wide variety of uncertainties and disturbances. A supervisory controller is also described in this thesis. The supervisory control is made up of a feedforward and a feedback component. It is shown that the feedforward component is the crane operator's action, and the feedback component is a sliding mode controller which compensates as the system's output deviates from the desired trajectory because of the operator's inappropriate actions or external disturbances such as wind gusts and noise. All controllers are simulated using Matlab and implemented in real-time on a scale model of the gantry crane system using the program RTShell. The real-time results are compared against simulated results to determine the controller's performance in a real-time environment.
90

Shake table experiments for the determination of the seismic response of jumbo container cranes

Jacobs, Laura Diane 15 November 2010 (has links)
Container cranes represent one of the most critical components of ports worldwide. Despite their importance to port operations, the seismic behavior of cranes has been largely ignored. Since the 1960s, industry experts have recommended allowing cranes to uplift, believing that it would limit the amount of seismic loading. However, modern cranes have become larger and more stable, and the industry experts are now questioning the seismic performance of modern jumbo cranes. The main goal of this research was to experimentally investigate the seismic behavior of container cranes from the general elastic behavior through collapse, including non-linear behavior such as buckling and cross section yielding, utilizing the 6 degree-of-freedom shake tables at the University at Buffalo. The testing was divided into two phases. The first phase of testing was conducted on a 1/20th scale model. The second phase of testing was conducted on a 1/10th scale model, which was designed such that no inelastic action would develop prior to uplift (as is the common design practice). In support of the experiments, finite element models were created to determine what simplifications could be made to the structure to aid in testing. The data collected from the testing has been used to validate finite element models, to give a better understanding of the behavior of container cranes under seismic excitations, validate fragility models, and to develop recommendations and guidelines for the design and testing of container cranes.

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