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Experimental Investigation of the Role of Turbulence Fluctuations on Incipient Motion of SedimentCelik, Ahmet Ozan 08 September 2011 (has links)
The movement of granular material along a streambed has been a challenging subject for researchers for more than a century. Predicting the limiting case of nearly zero bedload transport, usually referred to as threshold of motion or critical condition, is even more challenging due to the highly fluctuating nature of turbulent flow. Numerous works have advocated that the peak turbulent forces, randomly occurring in time and space with magnitudes higher than the average, initiate the bed material motion. More recent findings have shown that not only the magnitude of the peak turbulent forces acting on individual grains but their duration as well have to be considered for determining the incipient conditions. Their product, or impulse, is better suited for specifying such conditions.
The goal of this study was to investigate the mechanism responsible for initiation of sediment motion under turbulent flow conditions. The impulse concept was investigated by utilizing appropriate measurement methods in the laboratory for determining the condition of incipient motion. The experimental program included measurements of particle entrainment rates of a mobile grain and turbulence induced forces acting upon a fixed grain for a range of flow conditions. In addition, near bed flow velocities were measured synchronously with both the entrainment and pressure measurements at turbulent resolving frequencies.
Results of this work covered the limitations and uncertainties associated with the experimental methods employed, and the description of the inadequacies of existing incipient motion models via the impulse framework. The extreme sensitivity of bed material activity to minute adjustments in flow conditions was explained by the associated change in the frequency of impulse events. The probability density function proposed for impulse was used together with the critical impulse to estimate the particle entrainment rate for a range of flow conditions. It was shown that the impulse events with potential to dislodge the grain were occurring mostly during sweep type of flow structures. The impulse events were also typically accompanied by positive lift forces. The force patterns showed that the positive peaks in the lift consistently occurred before and after the impulse events in the drag force. The magnitude of these lift forces were significantly higher in the wake of a cylinder compared to that of uniform flow conditions. The time average lift force in the wake of a cylinder was also observed to be positive with magnitudes reaching more than 30% of the submerged weight of the particle. The cylinder caused the downstream turbulence intensity to increase slightly but the particle entrainment rate to increase significantly. This finding provided a physically based explanation for the modification of turbulent force fluctuations and resulting changes in the particle movement rates by such unsteady flow conditions. / Ph. D.
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ARCC - Ett förslag för kilskriftens digitala framtidLesniak, Tim, Strandberg, Alexander January 2018 (has links)
För att vi ska ha en förståelse av det förflutna måste arkeologer ha möjlighet att tolka arkeologiska fynd (Why Is Archaeology Important?, 2018). En typ av fynd är kilskrift. För att säkerställa bevaringen av denna typ av fynd har etiska principer etablerats som exempelvis inte låter någon utsätta fynden för fara ("Principles of Archaeological Ethics", 2018), till exempel i form av förvittring genom beröring. På grund av detta har digitala arbetssätt börjat etableras vid exempelvis rekonstruktionsarbete av kilskrift så att arbetet kan utföras utan direkt beröring (Fisseler, Müller & Weichert, 2017). Problemet är att denna typ av arbete upplevs som frustrerande av arkeologerna då det nya digitala arbetssättet skiljer sig från deras tidigare analoga arbetssätt (Woolley et al., 2017). För att lösa denna problematik har en konceptdriven metod använts i uppsatsen. Det har skapats ett digitalt koncept kallat ARCC som kan låta arkeologer arbeta på liknande vis som det analoga naturliga arbetssättet utan att beröra kilskriften. Konceptet ARCC är en kombination av teknologierna: augmented reality, magnetic tracking systems och 3D-printing. Detta koncept är ett exempel på möjligheterna som existerar angående ett praktiskt och etiskt arbetssätt i förhållande till rekonstruktionsarbete av kilskrift. ARCC kan vidareutvecklas för att stärka konceptet, samt också agera indikator på att fler möjligheter inom detta område existerar. / In order to have an understanding of the past archaeologists need to be able to interpret archaeological finds (Why Is Archaeology Important?, 2018). One type of find is cuneiform. Ethical principles has been established to secure the conservation of this kind of find by prohibiting handling that could cause weathering ("Principles of Archaeological Ethics", 2018). Because of this, digital work methods has been established in conjunction with reconstruction of cuneiform in order to eliminate the risk of weathering through touch (Fisseler, Müller & Weichert, 2017). The problem is that this kind of work is found to be frustrating by the archaeologists since this way of work differs from their usual analog work method (Woolley et al., 2017). To solve this problem we have used a concept driven method. The digital concept ARCC has been developed which allows archaeologists to use their usual work method without touching the cuneiform. The concept ARCC is a combination of the technologies: augmented reality, magnetic tracking systems and 3D-printing. This concept is an example of the possibilities that exist regarding a practical and ethical work method regarding reconstruction of cunaiform. ARCC can be further developed to improve the concept, it could also act as an indicator of further possibilities within this area
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Řízení projektu ve filmové a reklamní postprodukci / Managing projects of a feature film and commercial postproductionDvořák, Petr January 2009 (has links)
This thesis is focused on digital image postproduction -- specific field, which is responsible for digital creation and manipulation with image data of a feature film or a commercial. To achieve that, it uses large amount of human resources and the newest computer technology. The aim of this thesis was to review actual situation in film production from the informatics point of view. That comprises of explanation of field specifics, identification of information system in a typical postproduction house and finding ways how to effeciently manage postproduction projects through that. Thesis is designed as a complex practical guide, which is well understandable both to inexperienced people and proffesionals and delivers them useful information. It can be used by existing employees of a postproduction house (primarily managers and heads), freelancers or prospective future employees. This thesis highlights importanant aspects of postproduction, connected risks and helps people's to better orientate in this field. Outputs are numerous table summaries, recommendations, tips and hints and examples of possible solutions of actual postproduction problems. They are based on many internet sources and my own previous experience as a 3d graphic.
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Controle de arfagem e guinada de um sistema de hélices paralelas / Pitch and yaw control of a parallel propeller systemBreganon, Ricardo 24 September 2009 (has links)
A aplicação de técnicas de controle multivariáveis com o auxílio de ferramentas computacionais vem sendo bastante empregada em projetos de sistemas de controle complexos, que tem como base o conceito de variáveis de estado. Neste trabalho, visamos desenvolver um sistema de controle seguidor com realimentação de estados para um protótipo de um sistema de hélices paralelas onde a dinâmica é não linear e possui três graus de liberdade sendo dois graus de liberdade controlados. Serão utilizados dois modelos matemáticos: um modelo linear e um modelo não linear. A representação linear será utilizada para gerar as matrizes de ganho do sistema de controle. O modelo não linear é obtido através de prototipagem virtual no ambiente de desenvolvimento ADAMS®, que utiliza técnicas de modelagem de sistemas multicorpos para a obtenção das equações dinâmicas do movimento. Em seguida o modelo não linear é exportado para o ambiente de simulações em MATLAB®. A simulação é utilizada para verificar se a técnica de controle linear utilizada tem a capacidade de controlar o sistema não linear e analisar o comportamento do conjunto controlador mais a planta não linear já que está sendo feita atribuição de auto-estrutura completa. Os resultados obtidos ilustram o desempenho e a eficiência da metodologia proposta. / The application of multivariable control techniques with the aid of computing tools has been largely used in projects of complex control systems that are based on the concept of state-variables. The objective of this paper is to show the development of a tracking-system with state-feedback for a prototype of a parallel propeller system presenting nonlinear dynamics with three degrees-of-freedom but having only two controlled. Two mathematical models are used: a linear model and a nonlinear model. The linear representation is used to design the gain matrices of the linear control system. The nonlinear model is obtained through the virtual prototyping environment system ADAMS®, using modeling techniques of multi-body systems to obtain the dynamic motion equations. Then, the nonlinear model is exported to SIMULINK® (MATLAB®). The simulation is used to verify if the applied linear control techniques are able to control the nonlinear model and to analyze the system behavior (control system plus nonlinear plant). The design of the control system is done using the entire eigenstructure assignment technique. The results show the performance and the efficiency of the proposed methodology.
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Physical Modeling of the Motions of a Container Ship Moored to a Dock with Comparison to Numerical SimulationZhi, Yuanzhe 16 December 2013 (has links)
Container vessel motions need to be small when loading and offloading cargo while moored to wharfs. Waves and their reflections from structures can induce ship motions. These motions are characterized by six degrees of freedom, including translations of surge, sway, and heave and rotations of pitch, roll, and yaw. Monitoring and quantifying these motions offer a reference for design and selection of the mooring system and wharf types. To measure the six degrees of freedom motions of a container ship moored to a dock, a 1:50 scale model is moored to two types of dock, solid wall dock and pile supported dock. Irregular waves of TMA spectrum with various periods, heights, and directions are generated in the wave basin to induce the motions of the model container ship. Optical motion capturing cameras are used to measure and quantify the six degree of freedom motions. Results of the effects of wave period, significant wave height, and wave direction on the motion characteristics of the model container ship moored at the solid dock and a pile supported dock are described in detail. A numerical simulation called aNySIM is applied to numerically predict the motion characteristics of the container ship moored to a solid wall dock only. The physical model experimental results of solid dock are also compared with the numerical simulation. These comparisons indicate that the motion characteristics of the model container ship represent similar trends for both rotations and translations. The experimental and numerical prediction values of motions of the ship moored to a solid wall dock display the same tendencies while differing in magnitude.
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Wireless realtime motion tracking system using localised orientation estimationYoung, Alexander D. January 2010 (has links)
A realtime wireless motion tracking system is developed. The system is capable of tracking the orientations of multiple wireless sensors, using a semi-distributed implementation to reduce network bandwidth and latency, to produce real-time animation of rigid body models, such as the human skeleton. The system has been demonstrated to be capable of full-body posture tracking of a human subject using fifteen devices communicating with a basestation over a single, low bandwidth, radio channel. The thesis covers the theory, design, and implementation of the tracking platform, the evaluation of the platform’s performance, and presents a summary of possible future applications.
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Designing and implementing the Student Online Project Planning and Tracking System : students and faculty evaluation of the SOPPTS softwareZhang, Yong January 2002 (has links)
The purposes of this study were to design and to evaluate an online system designed to enhance communication skills and project tracking of computer software courses at Ball State University (BSU). Student Online Project Planning and Tracking System (SOPPTS) was designed and field tested to provide real-time feedback from faculty on student progress, offer online guidance for software project planning, produce tracking automation, and facilitate communication between faculty and students.SOPPTS technology was designed under the supervision of W. Zage and D. Zage, professors in the Computer Science Department at BSU.Participants in this study included six BSU undergraduate students, six BSU graduate students and seven BSU faculty members. Each participant was interviewed for one hour in an instructor's office in the BSU Computer Science Department. With the participants' permission, each interview was audio-taped and coded with a letter and number.Data evaluation consisted of narrative summaries of the interviews, an analysis of the evidence in terms of the research questions and the compilation of data to show both emerging themes and major trends.Analysis of the data showed that learning was definitely enhanced, and that faculty evaluations were also strongly enhanced. Participants recommended more SOPPTS applications, both industrial and academic. The emerging themes showed that faculty and students:1) Had more and easier access to information; students' work was better organized; student team spirit grew; students were more accurately evaluated by instructors;2) Had more efficient methods for report submission and record keeping; students interaction with teachers increased; students found SOPPTS better than email;3) Students and teachers could work from various locations, with greater access to record retrieval and submission of reports, so that documents submitted were available to all instead of getting lost;4) Students were motivated by the nature of online task assignment and tracking because of greater accountability; faculty members were happy to see students' project progress online; 5) Improved time and project management through greater awareness of milestones, deadlines and date/ time "stamping" of report submissions.Major trends show that improved access to information and communication facilitated learning, and that planning and tracking skills improved. / Department of Educational Leadership
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Detect and Analyze the 3-D Head Movement Patterns in Marmoset Monkeys using Wireless Tracking SystemJanuary 2015 (has links)
abstract: Head movement is a natural orienting behavior for sensing environmental events around us. Head movement is particularly important for identifying through the sense of hearing the location of an out-of-sight, rear-approaching target to avoid danger or threat. This research aims to design a portable device for detecting the head movement patterns of common marmoset monkeys in laboratory environments. Marmoset is a new-world primate species and has become increasingly popular for neuroscience research. Understanding the unique patterns of their head movements will improve its values as a new primate model for uncovering the neurobiology of natural orienting behavior. Due to their relatively small head size (5 cm in diameter) and body weight (300-500 g), the device has to meet several unique design requirements with respect to accuracy and workability. A head-mount wireless tracking system was implemented based on inertial sensors that are capable of detecting motion in the Yaw, Pitch and Roll axes. The sensors were connected to the encoding station, which transmits wirelessly the 3-axis movement data to the decoding station at the sampling rate of ~175 Hz. The decoding station relays this information to the computer for real-time display and analysis. Different tracking systems, based on the accelerometer and Inertial Measurement Unit is implemented to track the head movement pattern of the marmoset head. Using these systems, translational and rotational information of head movement are collected, and the data analysis focuses on the rotational head movement in body-constrained marmosets. Three stimulus conditions were tested: 1) Alert, 2) Idle 3) Sound only. The head movement patterns were examined when the house light was turned on and off for each stimulus. Angular velocity, angular displacement and angular acceleration were analyzed in all three axes.
Fast and large head turns were observed in the Yaw axis in response to the alert stimuli and not much in the idle and sound-only stimulus conditions. Contrasting changes in speed and range of head movement were found between light-on and light-off situations. The mean peak angular displacement was 95 degrees (light on) and 55 (light off) and the mean peak angular velocity was 650 degrees/ second (light on) and 400 degrees/second (light off), respectively, in response to the alert stimuli. These results suggest that the marmoset monkeys may engage in different modes of orienting behaviors with respect to the availability of visual cues and thus the necessity of head movement. This study provides a useful tool for future studies in understanding the interplay among visual, auditory and vestibular systems during nature behavior. / Dissertation/Thesis / Masters Thesis Bioengineering 2015
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Controle de arfagem e guinada de um sistema de hélices paralelas / Pitch and yaw control of a parallel propeller systemRicardo Breganon 24 September 2009 (has links)
A aplicação de técnicas de controle multivariáveis com o auxílio de ferramentas computacionais vem sendo bastante empregada em projetos de sistemas de controle complexos, que tem como base o conceito de variáveis de estado. Neste trabalho, visamos desenvolver um sistema de controle seguidor com realimentação de estados para um protótipo de um sistema de hélices paralelas onde a dinâmica é não linear e possui três graus de liberdade sendo dois graus de liberdade controlados. Serão utilizados dois modelos matemáticos: um modelo linear e um modelo não linear. A representação linear será utilizada para gerar as matrizes de ganho do sistema de controle. O modelo não linear é obtido através de prototipagem virtual no ambiente de desenvolvimento ADAMS®, que utiliza técnicas de modelagem de sistemas multicorpos para a obtenção das equações dinâmicas do movimento. Em seguida o modelo não linear é exportado para o ambiente de simulações em MATLAB®. A simulação é utilizada para verificar se a técnica de controle linear utilizada tem a capacidade de controlar o sistema não linear e analisar o comportamento do conjunto controlador mais a planta não linear já que está sendo feita atribuição de auto-estrutura completa. Os resultados obtidos ilustram o desempenho e a eficiência da metodologia proposta. / The application of multivariable control techniques with the aid of computing tools has been largely used in projects of complex control systems that are based on the concept of state-variables. The objective of this paper is to show the development of a tracking-system with state-feedback for a prototype of a parallel propeller system presenting nonlinear dynamics with three degrees-of-freedom but having only two controlled. Two mathematical models are used: a linear model and a nonlinear model. The linear representation is used to design the gain matrices of the linear control system. The nonlinear model is obtained through the virtual prototyping environment system ADAMS®, using modeling techniques of multi-body systems to obtain the dynamic motion equations. Then, the nonlinear model is exported to SIMULINK® (MATLAB®). The simulation is used to verify if the applied linear control techniques are able to control the nonlinear model and to analyze the system behavior (control system plus nonlinear plant). The design of the control system is done using the entire eigenstructure assignment technique. The results show the performance and the efficiency of the proposed methodology.
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Návrh metodiky řízení a správy incidentů a problémů a jejího využití ve vybrané organizaci / Design of methodology of administration and management of issues and its application in chosen organisationHolub, Adam January 2016 (has links)
This thesis is focused on design methodology of administration and management of issues, using issue-tracking system. The objective is to create such methodology and deploy it to specific organization. During methodology creation, there were used best practices, acquired from source thesis and authors experiences. In theoretical part of thesis are described approaches, witch is this thesis based on. Then thesis describes what issue-tracking system is and lists mostly used issue-tracking systems. In practical part, the methodology itself is created. At first, target group is described. Then, types of issuse and roles used in issue-tracking system are described. Then is described, how to create lifecycle of issue and how to handle with its attributes. Last part is focused on data reporting from issue-tracking system. Last chapter of practical part describes how to implement methodology to issue-tracking system JIRA.
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