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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.
1

A Low Cost Implementation of Autonomous Takeoff and Landing for a Fixed Wing UAV

Carnes, Thomas 01 January 2014 (has links)
The take-off and landing of an Unmanned Aerial Vehicle (UAV) is often the most critical and accident prone portion of its mission. This potential hazard coupled with the time and resources necessary to train a remote UAV pilot makes it desirable to have autonomous take-off and landing capabilities for UAVs. However, a robust, reliable, and accurate autonomous takeoff and landing capability for fixed-wing aircraft is not an available feature in many low-cost UAV flight control systems. This thesis describes the design of an autonomous take-off and landing algorithm implemented on an existing low-cost flight control system for a small fixed wing UAV. This thesis also describes the autonomous takeoff and landing algorithm development and gives validation results from hardware in the loop simulation.
2

Comparing Time and Accuracy of Building Information Modeling to On-Screen Takeoff for a Quantity Takeoff of a Conceptual Estimate

Alder, Morgan A. 19 July 2006 (has links) (PDF)
Estimating is a critical aspect of every construction project. The most tedious component of an estimate is the quantity takeoff. Different tools are available to improve an estimator's productivity for a quantity takeoff. Faster quantity takeoffs enable estimator to bid more jobs. This study analyzed the time and accuracy of performing quantity takeoffs when using building information modeling (BIM) through a comparison study using Revit (BIM software) and On-Center's OST. In preparation for the study the researcher conducted a pilot study. Participants of the study were asked to perform a quantity takeoff using both Revit and OST. Their resulting data was then, analyzed comparing both the time and accuracy of each item taken off. The subjects' perspectives on the two different methods of performing takeoff are also included in the findings of this study. This study focused on a conceptual estimate takeoff for a small commercial building. The results of the study showed that, on average, those using BIM were able to perform the overall takeoff faster than those using OST while still maintaining equivalent accuracy. This study includes methods to improve productivity for quantity takeoff through an analysis of the takeoffs of counts, areas, and lengths. Findings of this study include methods, techniques, and cautions for performing a quantity takeoff using BIM.
3

The mechanics of the contact phase in trampolining

Burke, Dave January 2015 (has links)
During the takeoff for a trampoline skill the trampolinist should produce sufficient vertical velocity and angular momentum to permit the required skill to be completed in the aerial phase without excessive horizontal travel. The aim of this study was to investigate the optimum technique to produce forward somersault rotation. A seven-segment, subject-specific torque-driven computer simulation model of the takeoff in trampolining was developed in conjunction with a model of the reaction forces exerted on the trampolinist by the trampoline suspension system. The ankle, knee, hip, and shoulder joints were torque-driven, with the metatarsal-phalangeal and elbow joints angle-driven. Kinematic data of trampolining performances were obtained using a Vicon motion capture system. Segmental inertia parameters were calculated from anthropometric measurements. Viscoelastic parameters governing the trampoline were determined by matching an angle-driven model to the performance data. The torque-driven model was matched to the performance data by scaling joint torque parameters from the literature, and varying the activation parameters of the torque generators using a simulated annealing algorithm technique. The torque-driven model with the scaled isometric strength was evaluated by matching the performance data. The evaluation produced close agreement between the simulations and the performance, with an average difference of 4.4% across three forward rotating skills. The model was considered able to accurately represent the motion of a trampolinist in contact with a trampoline and was subsequently used to investigate optimal performance. Optimisations for maximum jump height for different somersaulting skills and maximum rotation potential produced increases in jump height of up to 14% and increases of rotation potential up to 15%. The optimised technique for rotation potential showed greater shoulder flexion during the recoil of the trampoline and for jump height showed greater plantar flexion and later and quicker knee extension before takeoff. Future applications of the model can include investigations into the sensitivity of the model to changes in initial conditions, and activation, strength, and trampoline parameters.
4

Computer simulation of the takeoff in springboard diving

Kong, Pui W. January 2005 (has links)
A computer simulation model of a springboard and a diver was developed to investigate diving takeoff techniques in the forward and the reverse groups. The springboard model incorporated vertical, horizontal and rotational movements based on experimental data. The diver was modelled as an eight-segment link system with torque generators acting at the metatarsal-phalangeal, ankle, knee, hip and shoulder joints. Wobbling masses were included within the trunk, thigh and shank segments to allow for soft tissue movement. The foot-springboard interface was represented by spring-dampers acting at the heel, ball and toes of the foot. The model was personalised to an elite diver so that simulation output could be compared with the diver's own performance. Kinematic data of diving performances from a one-metre springboard were obtained using high speed video and personalised inertia parameters were determined from anthropometric measurements. Joint torque was calculated using a torque / angle / angular velocity relationship based on the maximum voluntary torque measured using an isovelocity dynamometer. Visco-elastic parameters were determined using a subject-specific angledriven model which matched the simulation to the performance in an optimisation process. Four dives with minimum and maximum angular momentum in the two dive groups were chosen to obtain a common set of parameters for use in the torque-driven model. In the evaluation of the torque-driven model, there was good agreement between the simulation and performance for all four dives with a mean difference of 6.3%. The model was applied to optimise for maximum dive height for each of the four dives and to optimise for maximum rotational potential in each of the two dive groups. Optimisation results suggest that changing techniques can increase the dive height by up to 2.0 cm. It was also predicted that the diver could generate rotation almost sufficient to perform a forward three and one-half somersault tuck and a reverse two and one-half somersault tuck.
5

A decision problem involving the introduction of RTOL aircraft into commercial air transportation systems

Schmitt, Gary Allen 24 July 2012 (has links)
This study is concerned with determining the feasibility of introducing a reduced takeoff and landing (RTOL) aircraft into the national aviation system. In considering this problem, a multiple criteria decision model based on the responses of airline executives was developed to describe the RTOL utilization problem. The exact problem that is considered in this thesis is, for a given set of itineraries, determine the itineraries for which aircraft (RTOL or CTOL, conventional takeoff and landing) are to be assigned such that the amount of fuel used, delay and noise levels are to be minimized. These assignments are subject to aircraft, airport, system and budgetary constraints. A decision-making procedure was formulated to solve the decision problem utilizing an interactive, multicriteria programming procedure. This procedure was developed to consider the use of 0-l decision variables. Two example problems are presented. The air transportation systems considered in the examples include (a) six airports in New York State and (b) five major airport hub areas in the north-eastern section of the United States. / Master of Science
6

The economic justification and operational requirements of high-speed runway exits

Zhong, Caoyuan 04 December 2009 (has links)
The objective of this thesis is to analyze the operational requirements of aircraft during the runway exiting maneuvers and the economic feasibility of high-speed runway exits. The motion of the aircraft is simulated by a computer program based on the appropriate equations of motion and steering inputs. The economic analysis of high-speed runway exits is based on a life cycle cost approach. Historical data of airline operating costs are also used in the cost estimations. The results show that high-speed runway exits are operationally feasible and economically profitable. The results are also presented graphically to show the effect of various steering commands on the vehicle turning maneuvering requirements and the effect of different economic parameters to the evaluation of high-speed exit utilizations. / Master of Science
7

Development of a Miniature VTOL Tail-Sitter Unmanned Aerial Vehicle

Hogge, Jeffrey V. 22 April 2008 (has links) (PDF)
The design, analysis, construction and flight testing of a miniature Vertical Take-Off and Landing (VTOL) tail-sitter Unmanned Aerial Vehicle (UAV) prototype is presented in detail. Classic aircraft design methods were combined with numerical analysis to estimate the aircraft performance and flight characteristics. The numerical analysis employed a propeller blade-element theory coupled with momentum equations to predict the influence of a propeller slipstream on the freestream flow field, then the aircraft was analyzed using 3-D vortex lifting-line theory to model finite wings immersed in the flow field. Four prototypes were designed, built, and tested and the evolution of these prototypes is presented. The final prototype design is discussed in detail. A method for sizing control surfaces for a tail-sitter was defined. The final prototype successfully demonstrated controllability both in horizontal flight and vertical flight. Significant contributions included the development of a control system that was effective in hover as well as descending vertical flight, and the development of a strong but light weight airframe. The aircraft had a payload weight fraction of 14.5% and a maximum dimension of one meter, making it the smallest tail-sitter UAV to carry a useful payload. This project is expected to provide a knowledge base for the future design of small electric VTOL tail-sitter aircraft and to provide an airframe for future use in tail-sitter research.
8

Análise dos efeitos da manutenção periódica de tratores agrícolas através do método de planejamento de experimentos

Ferrari, Luís Eduardo Accordi January 2015 (has links)
Este trabalho tem o objetivo de quantificar os efeitos da manutenção periódica de motores de tratores agrícolas sobre a potência medida na sua tomada de potência - TDP, e sobre o consumo de combustível. Para isso, utiliza-se o método de planejamento de experimentos, com um fatorial completo 25 sem repetição, totalizando 32 ensaios independentes. Para o experimento, utiliza-se um trator agrícola de rodas, com motor 6 cilindros, de 6,8 litros, com sistema de combustível de injeção direta, com uma bomba injetora rotativa, turboalimentado e com intercooler. Os parâmetros de controle são escolhidos com base na experiência do autor e seus níveis são definidos experimentalmente. São eles: a) condição externa do radiador, b) condição do filtro de combustível, c) condição do filtro de ar, d) qualidade do combustível e e) condição do óleo de motor. É possível constatar que os parâmetros com maior influência na potência são a condição do filtro de ar, condição do óleo do motor e uma interação de segunda ordem entre a qualidade do combustível e o óleo do motor. Eles são responsáveis por variações na potência de, respectivamente, 2,7%, 2,4% e 1,7%, referenciados na condição ideal de teste. O consumo de combustível não apresenta variação significativa em relação a nenhum dos fatores estudados, o que leva a concluir que não existe relação entre ele e a manutenção periódica do trator nos termos propostos por este trabalho. Por fim, mostra-se que a correta manutenção, desde sua condição extrema até sua condição ideal, aumenta em até 7% a potência útil disponibilizada pelo equipamento para o trabalho do campo. / This study aims to quantify the effects of periodic maintenance of agricultural tractors’ engines on the power measured at its power takeoff - PTO, and its fuel consumption. To do this, we use the design of experiments method, 25 full factorial without replication, totaling 32 independent assays. For the experiment, we use an agricultural wheel tractor, with 6 cylinder engine, 6,8 liters, rotary fuel pump and direct injection fuel system, turbocharged with intercooler. The control parameters are chosen based on the author's experience and their levels are defined experimentally. They are: a) external condition of radiator, b) fuel filter condition, c) air filter condition, d) quality of the fuel and e) engine oil condition. It can be seen that the parameters with the greatest influence on power are the air filter condition, engine oil condition and a second-order interaction between fuel quality and engine oil. They are responsible for variations in power, respectively of, 2.7%, 2.4% and 1.7%, results based on ideal condition. Fuel consumption presents no significant variation in relation to any of the factors studied, which leads to the conclusion that there is no relation between it and the periodic maintenance of the tractor the way it is proposed by this work. Finally, it is shown that with the correct maintenance, since the extreme condition to the ideal condition, increases up to 7% the power provided by the equipment to work in the field.
9

Jämförelse av olika mängdavtagningsmetoder / Comparison of different quantity takeoff methods

Yusuf, Adan, Miakhil, Ahmad January 2017 (has links)
BIM står för Building Information Modeling. Det innebär att man har en gemensambyggmodell som innehåller information relevant för alla aktörer. Skillnaden mellan en 3Doch BIM modell är förutom visualiseringen att man har tillgång till fler dimensioner s om tidoch kostnad. Detta leder till en större tydlighet för alla aktörer under en byggnads livscykel.IFC format är ett neutralt filformat som underlättar informationsbyte mellan olika BIMverktyg. IFC format har utvecklats av byggbranschen och ägs inte a v någon leverantör. VDC, som står för Virtual Design Construction, är NCC:s sätt att arbeta med projekt knutnatill BIM. VDC ger möjligheten att ge användaren uppdaterad information för att förståkundens önskemål och hur man ska förverkliga det. Ett led i detta arbete är att undersöka nyamängdavtagningsmetoder och jämföra dem. Syftet med examenarbetet var att jämföra 4 olika mängdavtagningsmetoder utifrån tid ochkvalitet. De 4 olika metoderna var Vico Office, Solibri, Bluebeam och den traditionellamän gdavtagningen för hand. Mängdavtagningen avgränsades endast till att mängda ickebärande innerväggar i projektet. Vico Office, Solibri, Bluebeam och mängdning för hand är de 4 metoderna som granskats.Underlag för mängdavtagningen har varit en IFC fil er o ch 2D ritningar. Från IFC filernagjordes mängdavtagning i Vico Office och Solibri. 2D ritningarna användes till att ta frammängder från Bluebeam och för hand. Mängdavtagningen resulterar i en jämförelse avmängderna man har fått. Sammanställning har geno mförts i Excel. Mängdavtagningen har utförts på Kvarteret Pedagogen som är en nyproduktion avflerbostadshus i Karslundsskogen. Det består av 3 huskroppar med 55 lägenheter på 5våningar. Byggstart var 2015 och byggnaderna står färdiga i dagsläget Resultatet visade på markanta skillnader mellan de 4 metoderna. Resultaten visade att SolibriModel Checker är den programvara som var bäst lämpad för mängdavtagning om man toghänsyn till tid och mängd. Den var också den mest användarvänliga av de 4 metoderna. / BIM stands for Building Information Modeling. This means that you have a common buildingmodel that contains information relevant to all members of the building process . Thedifference between a 3D and BIM model is in addition to visualization that you have access tomore dimensions such as time and cost. This leads to greater clarity for all members during abuilding's life cycle. IFC for mat is a neutral file format that facilitates information exchangebetween different BIM tools. IFC format has been developed by the construction industry andis not owned by any supplier. VDC, which stands for Virtual Design Construction, is NCC's way ofworking on projectslinked to BIM. VDC provides the opportunity to provide the user with updated information tounderstand the customer's wishes and how to impleme nt it. A part of this work includesinvestigating new methods of quantity takeoff and comparing them. The purpose of the thesis work was to compare 4 different methods ofquantity takeoff basedon time and quality. The 4 different methods were Vico Office, Solibri, Bluebeam and thetraditional quantity takeoff by hand (manual) manual). The quantity take off was limited only to theamount of non bearing inner walls in the project. Vico Office, Solibri, Bluebeam andquantity takeoff by hand are the 4 methods reviewed. Thebasis for the quantity take off has been an IFC file and 2D drawings. From the IFC file, takeoffwas made in Vico Office and Solibri. The 2D drawings were used to obtain quantities fromBluebeam and by hand. The quantity take off results in a comparison of the quantities that wasreceived . Summary of quantities has been carried out in Excel. Thequantities has been collected from Kvarteret Pedagogen which is a new construction ofmulti family houses in Karslundsskogen . It consists of 3 houses with 55 apartments on 5floors. Building start was 2015 an d today the project is complete. The result showed significant differences between the four meth ods. The results showed thatSolibri Model Checker is the software that is best suited for quantity takeoff when consideringtime and quantity. It was also the most user friendly of the 4 methods.
10

Análise dos efeitos da manutenção periódica de tratores agrícolas através do método de planejamento de experimentos

Ferrari, Luís Eduardo Accordi January 2015 (has links)
Este trabalho tem o objetivo de quantificar os efeitos da manutenção periódica de motores de tratores agrícolas sobre a potência medida na sua tomada de potência - TDP, e sobre o consumo de combustível. Para isso, utiliza-se o método de planejamento de experimentos, com um fatorial completo 25 sem repetição, totalizando 32 ensaios independentes. Para o experimento, utiliza-se um trator agrícola de rodas, com motor 6 cilindros, de 6,8 litros, com sistema de combustível de injeção direta, com uma bomba injetora rotativa, turboalimentado e com intercooler. Os parâmetros de controle são escolhidos com base na experiência do autor e seus níveis são definidos experimentalmente. São eles: a) condição externa do radiador, b) condição do filtro de combustível, c) condição do filtro de ar, d) qualidade do combustível e e) condição do óleo de motor. É possível constatar que os parâmetros com maior influência na potência são a condição do filtro de ar, condição do óleo do motor e uma interação de segunda ordem entre a qualidade do combustível e o óleo do motor. Eles são responsáveis por variações na potência de, respectivamente, 2,7%, 2,4% e 1,7%, referenciados na condição ideal de teste. O consumo de combustível não apresenta variação significativa em relação a nenhum dos fatores estudados, o que leva a concluir que não existe relação entre ele e a manutenção periódica do trator nos termos propostos por este trabalho. Por fim, mostra-se que a correta manutenção, desde sua condição extrema até sua condição ideal, aumenta em até 7% a potência útil disponibilizada pelo equipamento para o trabalho do campo. / This study aims to quantify the effects of periodic maintenance of agricultural tractors’ engines on the power measured at its power takeoff - PTO, and its fuel consumption. To do this, we use the design of experiments method, 25 full factorial without replication, totaling 32 independent assays. For the experiment, we use an agricultural wheel tractor, with 6 cylinder engine, 6,8 liters, rotary fuel pump and direct injection fuel system, turbocharged with intercooler. The control parameters are chosen based on the author's experience and their levels are defined experimentally. They are: a) external condition of radiator, b) fuel filter condition, c) air filter condition, d) quality of the fuel and e) engine oil condition. It can be seen that the parameters with the greatest influence on power are the air filter condition, engine oil condition and a second-order interaction between fuel quality and engine oil. They are responsible for variations in power, respectively of, 2.7%, 2.4% and 1.7%, results based on ideal condition. Fuel consumption presents no significant variation in relation to any of the factors studied, which leads to the conclusion that there is no relation between it and the periodic maintenance of the tractor the way it is proposed by this work. Finally, it is shown that with the correct maintenance, since the extreme condition to the ideal condition, increases up to 7% the power provided by the equipment to work in the field.

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