Dissertations / Theses: 'Theory of engines'

1

Miller, Shannon L. "Theory and implementation of low-irreversibility chemical engines /." May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Kim, Kee Hyo. "Engines of growth industrial policy and the Korean motor industry /." Thesis, Online version, 1997. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.337677.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Green, Johney Boyd Jr. "Application of deterministic chaos theory to cyclic variability in spark-ignition engines." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/16809.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Hariri, Bassam. "Modelling and identification of S.I. engines for control system design." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266264.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Clifton, David A. "Novelty detection with extreme value theory in jet engine vibration data." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670016.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Humphrey, Tammy Ellen Physics Faculty of Science UNSW. "Mesoscopic quantum ratchets and the thermodynamics of energy selective electron heat engines." Awarded by:University of New South Wales. Physics, 2003. http://handle.unsw.edu.au/1959.4/19186.

Full text

Abstract:

A ratchet is an asymmetric, non-equilibrated system that can produce a directed current of particles without the need for macroscopic potential gradients. In rocked quantum electron ratchets, tunnelling and wave-reflection can induce reversals in the direction of the net current as a function of system parameters. An asymmetric quantum point contact in a GaAs/GaAlAs heterostructure has been studied experimentally as a realisation of a quantum electron ratchet. A Landauer model predicts reversals in the direction of the net current as a function of temperature, amplitude of the rocking voltage, and Fermi energy. Artifacts such as circuit-induced asymmetry, also known as self-gating, were carefully removed from the experimental data, which showed net current and net differential conductance reversals, as predicted by the model. The model also predicts the existence of a heat current where the net electron current changes sign, as equal numbers of high and low energy electrons are pumped in opposite directions. An idealised quantum electron ratchet is studied analytically as an energy selective electron heat engine and refrigerator. The hypothetical device considered consists of two electron reservoirs with different temperatures and Fermi energies. The reservoirs are linked via a resonant state in a quantum dot, which functions as an idealised energy filter for electrons. The efficiency of the device approaches the Carnot value when the energy transmitted by the filter is tuned to that where the Fermi distributions in the reservoirs are equal. The maximum power regime, where the filter transmits all electrons that contribute positively to the power, is also examined. Analytic expressions are obtained for the power and efficiency of the idealised device as both a heat engine and as a refrigerator in this regime of operation. The expressions depend on the ratio of the voltage to the difference in temperature of the reservoirs, and on the ratio of the reservoir temperatures. The energy selective electron heat engine is shown to be non-endoreversible, and to operate in an analogous manner to the three-level amplifier, a laser based quantum heat engine. Implications for improving the efficiency of thermionic refrigerators and power generators are discussed.

APA, Harvard, Vancouver, ISO, and other styles

7

Benyo, Theresa Louise. "Analytical and computational investigations of a magnetohydrodynamics (MHD) energy-bypass system for supersonic gas turbine engines to enable hypersonic flight." Thesis, Kent State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3618922.

Full text

Abstract:

Historically, the National Aeronautics and Space Administration (NASA) has used rocket-powered vehicles as launch vehicles for access to space. A familiar example is the Space Shuttle launch system. These vehicles carry both fuel and oxidizer onboard. If an external oxidizer (such as the Earth's atmosphere) is utilized, the need to carry an onboard oxidizer is eliminated, and future launch vehicles could carry a larger payload into orbit at a fraction of the total fuel expenditure. For this reason, NASA is currently researching the use of air-breathing engines to power the first stage of two-stage-to-orbit hypersonic launch systems. Removing the need to carry an onboard oxidizer leads also to reductions in total vehicle weight at liftoff. This in turn reduces the total mass of propellant required, and thus decreases the cost of carrying a specific payload into orbit or beyond. However, achieving hypersonic flight with air-breathing jet engines has several technical challenges. These challenges, such as the mode transition from supersonic to hypersonic engine operation, are under study in NASA's Fundamental Aeronautics Program.

One propulsion concept that is being explored is a magnetohydrodynamic (MHD) energy- bypass generator coupled with an off-the-shelf turbojet/turbofan. It is anticipated that this engine will be capable of operation from takeoff to Mach 7 in a single flowpath without mode transition. The MHD energy bypass consists of an MHD generator placed directly upstream of the engine, and converts a portion of the enthalpy of the inlet flow through the engine into electrical current. This reduction in flow enthalpy corresponds to a reduced Mach number at the turbojet inlet so that the engine stays within its design constraints. Furthermore, the generated electrical current may then be used to power aircraft systems or an MHD accelerator positioned downstream of the turbojet. The MHD accelerator operates in reverse of the MHD generator, re-accelerating the exhaust flow from the engine by converting electrical current back into flow enthalpy to increase thrust. Though there has been considerable research into the use of MHD generators to produce electricity for industrial power plants, interest in the technology for flight-weight aerospace applications has developed only recently.

In this research, electromagnetic fields coupled with weakly ionzed gases to slow hypersonic airflow were investigated within the confines of an MHD energy-bypass system with the goal of showing that it is possible for an air-breathing engine to transition from takeoff to Mach 7 without carrying a rocket propulsion system along with it. The MHD energy-bypass system was modeled for use on a supersonic turbojet engine. The model included all components envisioned for an MHD energy-bypass system; two preionizers, an MHD generator, and an MHD accelerator. A thermodynamic cycle analysis of the hypothesized MHD energy-bypass system on an existing supersonic turbojet engine was completed. In addition, a detailed thermodynamic, plasmadynamic, and electromagnetic analysis was combined to offer a single, comprehensive model to describe more fully the proper plasma flows and magnetic fields required for successful operation of the MHD energy bypass system.

The unique contribution of this research involved modeling the current density, temperature, velocity, pressure, electric field, Hall parameter, and electrical power throughout an annular MHD generator and an annular MHD accelerator taking into account an external magnetic field within a moving flow field, collisions of electrons with neutral particles in an ionized flow field, and collisions of ions with neutral particles in an ionized flow field (ion slip). In previous research, the ion slip term has not been considered.

The MHD energy-bypass system model showed that it is possible to expand the operating range of a supersonic jet engine from a maximum of Mach 3.5 to a maximum of Mach 7. The inclusion of ion slip within the analysis further showed that it is possible to 'drive' this system with maximum magnetic fields of 3 T and with maximum conductivity levels of 11 mhos/m. These operating parameters better the previous findings of 5 T and 10 mhos/m, and reveal that taking into account collisions between ions and neutral particles within a weakly ionized flow provides a more realistic model with added benefits of lower magnetic fields and conductivity levels especially at the higher Mach numbers. (Abstract shortened by UMI.)

APA, Harvard, Vancouver, ISO, and other styles

8

Chung, Gi Yun. "An analytical approach to real-time linearization of a gas turbine engine model." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50702.

Full text

Abstract:

A recent development in the design of control system for a jet engine is to use a suitable, fast and accurate model running on board. Development of linear models is particularly important as most engine control designs are based on linear control theory. Engine control performance can be significantly improved by increasing the accuracy of the developed model. Current state-of-the-art is to use piecewise linear models at selected equilibrium conditions for the development of set point controllers, followed by scheduling of resulting controller gains as a function of one or more of the system states. However, arriving at an effective gain scheduler that can accommodate fast transients covering a wide range of operating points can become quite complex and involved, thus resulting in a sacrifice on controller performance for its simplicity. This thesis presents a methodology for developing a control oriented analytical linear model of a jet engine at both equilibrium and off-equilibrium conditions. This scheme requires a nonlinear engine model to run onboard in real time. The off-equilibrium analytical linear model provides improved accuracy and flexibility over the commonly used piecewise linear models developed using numerical perturbations. Linear coefficients are obtained by evaluating, at current conditions, analytical expressions which result from differentiation of simplified nonlinear expressions. Residualization of the fast dynamics states are utilized since the fast dynamics are typically outside of the primary control bandwidth. Analytical expressions based on the physics of the aerothermodynamic processes of a gas turbine engine facilitate a systematic approach to the analysis and synthesis of model based controllers. In addition, the use of analytical expressions reduces the computational effort, enabling linearization in real time at both equilibrium and off-equilibrium conditions for a more accurate capture of system dynamics during aggressive transient maneuvers. The methodology is formulated and applied to a separate flow twin-spool turbofan engine model in the Numerical Propulsion System Simulation (NPSS) platform. The fidelity of linear model is examined by validating against a detailed nonlinear engine model using time domain response, the normalized additive uncertainty and the nu-gap metric. The effects of each simplifying assumptions, which are crucial to the linear model development, on the fidelity of the linear model are analyzed in detail. A case study is performed to investigate the case when the current state (including both slow and fast states) of the system is not readily available from the nonlinear simulation model. Also, a simple model based control is used to illustrate benefits of using the proposed modeling approach.

APA, Harvard, Vancouver, ISO, and other styles

9

Dufva, Johannes, and Andreas Lindgren. "Machine Learning Models for Fueling Inaccuracy Detection using Gas Exchange Signals in Heavy-duty Vehicle Engines." Thesis, Uppsala universitet, Avdelningen för systemteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-447180.

Full text

Abstract:

Heavy-duty trucks are important links in the logistic chains of transport. Critical components in trucks include fuel injectors in which inaccuracies can lead to severe financial damage and higher emissions. Intelligent and efficient ways to detect such scenarios are thus of high importance. This thesis applies machine learning algorithms to measured or estimated engine data, focused on gas exchange signals, to detect inaccuracies in fueling quantities. The fueling inaccuracies considered were of low deviations from the nominal curve, with magnitudes not covered by the currently used fueling diagnostics. The data used for the models was generated from Scania test cell engines where different setups of injectors were deliberately set to over- or underfuel. Seven different machine learning models were used on the data and evaluated on how well they could detect deviations from nominal fueling. The tests were mainly done with a pure data-driven approach but also improved through different data selection techniques and using domain knowledge. An investigation to connect the findings within the thesis to real customer data was initiated in order to make the results useful for e.g. predictive maintenance. The complications connected to why this was not ultimately achieved were discussed.

APA, Harvard, Vancouver, ISO, and other styles

10

Lindwall, Victor. "The application of Micro Perforation theory onto Volvo Cars's Air Induction Systems : Implementation and Manufacturing of Micro Perforated Silencers at Volvo Cars in Gothenburg." Thesis, Linköpings universitet, Maskinkonstruktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-145541.

Full text

Abstract:

Downsizing in cars lead to higher noise emissions through the addition of turbo-/superchargers. These noise emissions must be counteracted and cancelled in order to contribute to the overall quality feel of a car. This project follows a product development method in order to research if a new type of silencers are applicable in air induction systems in order to dampen noise emissions. The project also cover how to manufacture the new type of silencers, traditionally used as acoustic insulation in offices. The project covered everything from literature review on silencers, noise regulations, downsizing and traditional plastic manufacturing methods. After the analysis of the results, it stood clear that the new silencers are more effective than conventional solutions. A manufacturing process was also determined, which needs further research in order to derive what the manufacturing cost would be. The project resulted in strong indicators that the new silencers are promising but also opened up to new research questions.

APA, Harvard, Vancouver, ISO, and other styles

11

Sandlund, Erik. "Modelling the Magnetic Influence of a Jet Aircraft : A study on the magnetic interference of an aircraft configuration and its effect on a magnetometer." Thesis, Linköpings universitet, Teoretisk Fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157743.

Full text

Abstract:

Aircraft have been used for the detection of submarines since World War II. The basic concept is to attach a sensor to the back of an aircraft. Since the aircraft is a moving metallic object, it is bound to generate a great deal of interference. Because of this, mathematical models and software have been developed to help filter out this interference and thus make the detection of the submarine easier. Normally, the engines of the aircraft are placed on the wings, quite far away from the sensor. However, for a maritime patrol system in development, the jet engines are placed at the rear of the airframe, generating the necessity to study whether or not they affect the performance of the sensor, which is the purpose of this thesis. Several models were created, tested and simulated for the airframe and jet engines. One of each of these were then combined to create a simulation model for the complete aircraft. A jet engine model that included rotating machinery -- a possible source of magnetic interference -- was also created, but could not be added to the model for the complete aircraft. The magnetic interference was mathematically compensated for, removing the static interference, but not the interference during manoeuvres. The jet engine part of the complete aircraft model did not seem to generate a significant amount of magnetic interference compared to the airframe. An electric dipole, representing a submarine, was then added to the simulation. The data from that simulation was put through the mathematical model and distortions of a few~nT were noticeable during straight courses. The jet engine model that included rotating machinery yielded different results compared to the jet engine model in the complete aircraft model. They seemed to contain signals of higher frequency, which were however not detected by a frequency domain study or present during straight courses. It was thus concluded that using this particular engine model the submarine could probably still be detected if the course of the aircraft was kept straight, though further research is needed with more advanced models for the engine, in particular with regards to the rotating machinery.

APA, Harvard, Vancouver, ISO, and other styles

12

Ferhatosmanoglu, Nilgun. "Optimal design of experiments for emerging biological and computational applications." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1179177867.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Kashinath, Karthik. "Nonlinear thermoacoustic oscillations of a ducted laminar premixed flame." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/264291.

Full text

Abstract:

Finding limit cycles and their stability is one of the central problems of nonlinear thermoacoustics. However, a limit cycle is not the only type of self-excited oscillation in a nonlinear system. Nonlinear systems can have quasi-periodic and chaotic oscillations. This thesis examines the different types of oscillation in a numerical model of a ducted premixed flame, the bifurcations that lead to these oscillations and the influence of external forcing on these oscillations. Criteria for the existence and stability of limit cycles in single mode thermoacoustic systems are derived analytically. These criteria, along with the flame describing function, are used to find the types of bifurcation and minimum triggering amplitudes. The choice of model for the velocity perturbation field around the flame is shown to have a strong influence on the types of bifurcation in the system. Therefore, a reduced order model of the velocity perturbation field in a forced laminar premixed flame is obtained from Direct Numerical Simulation. It is shown that the model currently used in the literature precludes subcritical bifurcations and multi-stability. The self-excited thermoacoustic system is simulated in the time domain with many modes in the acoustics and analysed using methods from nonlinear dynamical systems theory. The transitions to the periodic, quasiperiodic and chaotic oscillations are via sub/supercritical Hopf, Neimark-Sacker and period-doubling bifurcations. Routes to chaos are established in this system. It is shown that the single mode system, which gives the same results as a describing function approach, fails to capture the period-$2$, period-$k$, quasi-periodic and chaotic oscillations or the bifurcations and multi-stability seen in the multi-modal case, and underpredicts the amplitude. Instantaneous flame images reveal that the wrinkles on the flame surface and pinch off of flame pockets are regular for periodic oscillations, while they are irregular and have multiple time and length scales for quasi-periodic and chaotic oscillations. Cusp formation, their destruction by flame propagation normal to itself, and pinch-off and rapid burning of pockets of reactants are shown to be responsible for generating a heat release rate that is a highly nonlinear function of the velocity perturbations. It is also shown that for a given acoustic model of the duct, many discretization modes are required to capture the rich dynamics and nonlinear feedback between heat release and acoustics seen in experiments. The influence of external harmonic forcing on self-excited periodic, quasi-periodic and chaotic oscillations are examined. The transition to lock-in, the forcing amplitude required for lock-in and the system response at lock-in are characterized. At certain frequencies, even low-amplitude forcing is sufficient to suppress period-$1$ oscillations to amplitudes that are 90$\%$ lower than that of the unforced state. Therefore, open-loop forcing can be an effective strategy for the suppression of thermoacoustic oscillations. This thesis shows that a ducted premixed flame behaves similarly to low-dimensional chaotic systems and that methods from nonlinear dynamical systems theory are superior to the describing function approach in the frequency domain and time domain analysis currently used in nonlinear thermoacoustics.

APA, Harvard, Vancouver, ISO, and other styles

14

Alcocer, Bonifaz Joaquin. "Design of High Performance Flanges and its Influence on Manufacturing Costs, Structural Performance and Weight." Thesis, KTH, Maskinkonstruktion (Inst.), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-248024.

Full text

Abstract:

This project attempts to research the manufacturing cost, with an emphasis on machining, of high performance flanges for Turbine Rear Structure (TRS) applications, as well as the tradeoffs with structural performance and weight. A combination of traditional cost modelling techniques from the literature, as well as, the non-conventional manufacturing complexity index, as cost indicator are implemented. A multidisciplinary study is carried out with the aid of ANSYS Workbench in the form of computer simulated experiments to investigate tradeoffs in flanges. It is concluded that multidisciplinary studies of cost, performance and weight lacked model robustness to draw sound conclusions about flange design. However, the manufacturing complexity index after partial validation with experienced engineers shows promising results, and could be a way forward to estimate final machining operation cost for flanges in the future.
Syftet för detta projekt är att undersöka tillverkningskostnaden, med tonvikt på bearbetning av högpresterande flänsar för turbinapplikationer (TRS), samt dess relation till strukturella prestanda och vikt. Traditionella kostnadsmodelleringstekniker kombineras med det ickekonventionella tillverkningskomplexitetsindexet och används som kostnadsindikator. En tvärvetenskaplig studie genomförs med hjälp av ANSYS Workbench i form av dator simulerade experiment för att undersöka flänsavvägningar. En slutsats av studien är att multidisciplinära modeller av kostnad, prestanda och vikt saknade robusthet för att kunna dra djupgående slutsatser om prestandan för en flänsdesign. Tillverkningskomplexitetsindexet visar dock, efter partiell validering med erfarna ingenjörer, lovande resultat och kan vara framgångsrikt ett sätt att uppskatta den slutliga bearbetningskostnaden för flänsar.

APA, Harvard, Vancouver, ISO, and other styles

15

Василенко, Олег Вадимович. "Совершенствование рабочего процесса двухтактного двигателя с искровым зажиганием и непосредственным впрыском топлива." Thesis, Украинский государственный университет железнодорожного транспорта, 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/21849.

Full text

Abstract:

Диссертация на соискание ученой степени кандидата технических наук по специальности 05.05.03 – двигатели и энергетические установки. Национальный технический университет "Харьковский политехнический институт", Харьков, 2016 г. Диссертация посвящена улучшению эколого-экономических показателей двухтактных ДВС с искровым зажиганием путем применение системы непосредственного впрыска топлива в камеру сгорания. На двигателе ДН-4М проведены экспериментальные исследования с расслоением и обеднением топливновоздушного заряда при непосредственном впрыске топлива. Для обеспечения организации расслоенного топливновоздушного заряда применяется клапанная форсунка с модернизированным распылителем (техническая новизна защищена патентом Украины на изобретение), обеспечивающим кумулятивную топливную струю, направленную на поверхность камеры сгорания возле электродов свечи зажигания. На такте сжатия воздушный поток движется над топливной пленкой, где организуется обогащенная топливновоздушная смесь, которая направляется к электродам свечи зажигания. При этом на режимах холостого хода и на частичных нагрузках на момент подачи искры зажигания на периферии топливновоздушной смеси, возле стенок надпоршневого объема, располагается воздушный заряд с продуктами сгорания. Выявлено, что резервами повышения показателей работы двигателя являются снижение тепловых потерь с отработавшими газами и в систему охлаждения. В двухтактных двигателях с искровым зажиганием при непосредственном впрыскивании топлива и с расслоением топливновоздушного заряда при использовании бензо-этанольных смесей обеспечивается устойчивая работа во всем диапазоне нагрузок без изменений регулировочных параметров с более высокими экономическими и экологическими показателями, чем в аналогичных двигателях с внешним смесеобразованием.
Thesis to obtain scientific degree of Candidate of Engineering sciences on the speciality 05.05.03 – engines and power plants. National Technical University "Kharkiv Polytechnic Institute", Kharkov, 2015. The dissertation is devoted to improving environmental and economic performance two-stroke internal combustion engines with spark ignition by the use of direct fuel injection. Determined that a promising way of internal mixing with direct fuel injection is the organization layered fuel-air charge, providing improved environmental and economic performance. The criterion L, which characterizes the stratification of the fuel-air charge, can qualitatively assess the effect of mixing process on the performance of the engine as a whole. A factor Z, which is deter-mined using indicator efficiency two-stroke engine with external mixture formation, which takes into account only that fuel which is involved in the combustion cylinder engine. The use of direct injection petrol bundle of fuel-air charge modes for loading characteristic at n = 3000 rev/min enabled the reduction in fuel con-sumption of 1.83 times at the effective efficiency rjfmax = 0,31, 7-10 times lower harmful substances (CO, CH) in exhaust gases, the use of gasoline-ethanol blends ensured stable operation of the engine in all load range and a high economic and environmental performance than when using carburetor system power.

APA, Harvard, Vancouver, ISO, and other styles

16

Василенко, Олег Вадимович. "Удосконалення робочого процесу двотактного двигуна з іскровим запалюванням і безпосереднім вприскуванням палива." Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/21826.

Full text

Abstract:

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.05.03 – двигуни та енергетичні установки. Національний технічний університет "Харківський політехнічний інститут". – Харків, 2016 р. Дисертація присвячена поліпшенню еколого-економічних показників двотактних ДВЗ з іскровим запалюванням шляхом застосування безпосереднього вприскування палива. Визначено, що перспективним способом внутрішнього сумішоутворення при безпосередньому вприскуванні палива є організація розшарованого паливоповітряного заряду, що забезпечує покращення еколого-економічних показників. Запропоновано критерій L, який характеризує рівень розшарування паливоповітряного заряду, дозволяє якісно оцінити вплив процесів сумішоутворення на показники двигуна в цілому. Запропоновано коефіцієнт Z, за допомогою якого визначається індикаторний ККД двотактного двигуна із зовнішнім сумішоутворенням, який враховує тільки те паливо, яке згоряє в циліндрі ДВЗ. Застосування безпосереднього вприскування бензину з розшаруванням паливоповітряного заряду на режимах навантажувальній характеристиці при n = 3000 хв-1 дозволило зменшити в 1,83 рази витрати палива при значенні ефективного ККД ηе max = 0,31, в 7–10 раз знизити вміст шкідливих речовин (СО, СН) у відпрацьованих газах, також використання бензо-етанольних сумішей забезпечило стійку роботу двигуна у всьому діапазоні навантажень та більш високі економічні і екологічні показники, чим при використанні карбюраторної системи живлення.
Thesis to obtain scientific degree of Candidate of Engineering sciences on the speciality 05.05.03 – engines and power plants. National Technical University "Kharkiv Polytechnic Institute", Kharkov, 2015. The dissertation is devoted to improving environmental and economic performance two-stroke internal combustion engines with spark ignition by the use of direct fuel injection. Determined that a promising way of internal mixing with direct fuel injection is the organization layered fuel-air charge, providing improved environmental and economic performance. The criterion L, which characterizes the stratification of the fuel-air charge, can qualitatively assess the effect of mixing process on the performance of the engine as a whole. A factor Z, which is deter-mined using indicator efficiency two-stroke engine with external mixture formation, which takes into account only that fuel which is involved in the combustion cylinder engine. The use of direct injection petrol bundle of fuel-air charge modes for loading characteristic at n = 3000 rev/min enabled the reduction in fuel con-sumption of 1.83 times at the effective efficiency rjfmax = 0,31, 7-10 times lower harmful substances (CO, CH) in exhaust gases, the use of gasoline-ethanol blends ensured stable operation of the engine in all load range and a high economic and environmental performance than when using carburetor system power.

APA, Harvard, Vancouver, ISO, and other styles

17

Chastain, John H. "Internal combustion engine cooling strategies theory and test /." Connect to this title online, 2006. http://etd.lib.clemson.edu/documents/1171042757/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Pacer, Michael D. "Mind as Theory Engine| Causation, Explanation and Time." Thesis, University of California, Berkeley, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10194103.

Full text

Abstract:

Humans build theories out of the data we observe, and out of those theories arise wonders. The most powerful theories are causal theories, which organise data into actionable structures. Causal theories make explicit claims about the structure of the world: what entities and processes exist in it, which of these relate to one another and in what form those relations consist. We can use causal theories to induce new generalisations about the world (in the form of particular models or other causal theories) and to explain particular occurrences. This allows rapidly disseminating causal information throughout our cognitive communities. Causal theories and the explanations derived from them guide decisions we make, including where and when to look for more data, completing the cycle.

Causal theories play a ubiquitous and potent role in everyday life, in formal pursuit of them in the sciences, and through their applications in medicine, technology and industry. Given this, the rarity of analyses that attempt to characterise causal theories and their uses in general, computational terms is surprising. Only in recent years has there been a substantial refinement of our models of causal induction due to work by computational cognitive scientists — the interdisciplinary tradition out of which which this dissertation originates. And even so, many issues related to causal theories have been left unattended; three features in particular merit much greater attention from a computational perspective: generating and evaluating explanation, the role of simplicity in explanation choice, and continuous-time causal induction. I aim to redress this situation with this dissertation.

In Chapter 0, I introduce the primary paradigms from computational cognitive science – computational level analysis and rational analysis – that govern my research. In Chapter 1, I study formal theories of causal explanation in Bayesian networks by comparing the explanations the generate and evaluate to human judgements about the same systems. No one model of causal explanation captures the pattern of human judgements, though the intuitive hypothesis, that the most probable a posteriori explanation is the best performs worst of the models evaluated. I conclude that the premise of finding model for all of human causal explanation (even in this limited domain) is flawed; the research programme should be refined to consider the features of formal models and how well they capture our explanatory practices as they vary between individuals and circumstances. One feature not expressed in these models explicitly but that has been shown to matter for human explanation is simplicity. Chapter 2 considers the problem of simplicity in human causal explanation choice in a series of four experiments. I study what makes an explanation simple (whether it is the number of causes invoked in or the number of assumptions made by an explanation), how simplicity concerns are traded off against data-fit, which cognitive consequences arise from choosing simpler explanations when the data does not fit, and why people prefer simpler explanations.

In Chapter 3, I change the focus from studying causal explanation to causal induction — in particular, I develop a framework for continuous time causal theories (

CTCTS

). A

CTCT

defines a generative probabilistic framework for other generative probabilistic models of causal systems, where the data in those systems expressed in terms of continuous time. Chapter 3 is the most interdisciplinary piece of my dissertation, accordingly it begins by reviewing a number of topics: the history of theories of causal induction within philosophy, statistics and medicine; empirical work on causal induction in cognitive science, focusing on issues related to causal induction with temporal data; conceptual issues surrounding the formal definition of time, data, and causal models; and probabilistic graphical models, causal theories, and stochastic processes. I then introduce the desiderata for the

CTCT

framework and how those criteria are met. I then demonstrate the power of

CTCTS

by using them to analyse five sets of experiments (some new and some derived from the literature) on human causal induction with temporal data. Bookending each experiment and the model applied to it is are case from medical history that illustrate a real-world instance of the variety of problem being solved in the section; the opening discussion describes the case and why it fits the problem structure of the model used to analyse the experimental results and the closing discussion illustrates aspects of the case omitted from the initial discussion that complicate the model and fit better with the model introduced in the next section. Then, I discuss ways to incorporate other advances in probabilistic programming, generative theories and stochastic processes into the

CTCT

framework, identify potential applications with specific focus on mechanisms and feedback loops, and conclude by analysing the centrality of temporal information in the study of the mind more generally.

Excepting the supporting appendices and bibliography that end the dissertation, I conclude in two parts. First, in Chapter 4, I analyse issues at the intersection of three of the main themes of my work: namely, (causal) explanation, (causal) induction and time. This proceeds by examining these topics first in pairs and then as a whole. Following that, is Chapter 5, an epilogue that clarifies the interpretations and intended meanings of the “Mind as Theory Engine” metaphor as it applies to human cognition.

APA, Harvard, Vancouver, ISO, and other styles

19

Fahlström, Kamilla, and Caroline Jensen. "Search Engine Marketing in SMEs : The motivations behind using search engine marketing." Thesis, Högskolan i Gävle, Avdelningen för ekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-21116.

Full text

Abstract:

Abstract Title: Search Engine Marketing in SMEs Level: Final assignment for Bachelor Degree in Business Administration Authors: Kamilla Fahlström & Caroline Jensen Supervisor: Jens Eklinder Frick Date: 2016 January Purpose: The purpose of this study is to use Expectancy theory to describe and analyze small company owners’ motivations for their usage of Search Engine Marketing, in terms of their perceived Valence, Expectancy and Instrumentality. Method: To research the aim of this study a qualitative research approach was used. The empirical data was compiled through ten semi-structured interviews from a varied selection of Swedish companies in the service sector. The data was analyzed with previous research to create an understanding of the motivations for using Search Engine Marketing. Conclusions: The result of this study, when analyzed alongside Expectancy theory, indicates that small business owners are motivated to use Search Engine Marketing. Furthermore, which method of Search Engine Marketing that the owners are motivated to use is dependent on their perceptions of the different methods. Future research: Due to the lack of research into the attitudinal and psychological aspects of Search Engine Marketing and the limitations of this study, it would be interesting if more research were done into this area. For example, it would be interesting to study if trust-based companies are motivated to use Search Engine Marketing, and if demographics affect the motivations. Contribution: This study contributes with results on a previously unexplored area within the research field of Search Engine Marketing. The study also contribute with some information to practice regarding small service company owners’ thoughts about their usage of Search Engine Marketing. Key words: Search Engine Marketing, SMEs, Expectancy theory, Motivation, Website visibility

APA, Harvard, Vancouver, ISO, and other styles

20

Lee, Szeyin. "Designing A Better Internet Search Engine Based On Information Foraging Theory." Scholarship @ Claremont, 2014. http://scholarship.claremont.edu/scripps_theses/456.

Full text

Abstract:

The first part of the thesis focuses on Information Foraging Theory which was developed by Peter Pirolli, a cognitive scientist from Intelligent Systems Lab at Palo Alto Research Center, to understand how human search in an information environment (Pirolli 1995). The theory builds upon the optimal foraging theory in behavioral ecology, which assumes that people adapt and optimize their information seeking behavior to maximize the success of accomplishing the task goals by selectively choosing paths based on the expected utility from the information cues. The expected utility in Information Foraging Theory is called Information Scent. The second part is to design and build a new way to visualize search engine results in a graphical way that incorporates the concept of information scent to make search experience more efficient for users. The end result of the project will be an improved visualization of search results, obtained by using Google’s Application programming interface (API), latent semantic analysis, and data visualization methods to present a semantics-based visualization of the search results. The proposed design is developed to increase information scent for relevant results and shorten the foraging path to reach the search goal by presenting users with fewer but more valuable proximal cues, thus making search a more human-centered experience.

APA, Harvard, Vancouver, ISO, and other styles

21

França, Alberto César Cavalcanti. "A theory of motivation and satisfaction of software engineers." Universidade Federal de Pernambuco, 2014. https://repositorio.ufpe.br/handle/123456789/12006.

Full text

Abstract:

Submitted by Nayara Passos (nayara.passos@ufpe.br) on 2015-03-11T18:03:12Z No. of bitstreams: 2 TESE Alberto César Cavalcanti França.pdf: 3788012 bytes, checksum: a84eaeee00c35211070eb3130be655f2 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5)
Made available in DSpace on 2015-03-11T18:03:12Z (GMT). No. of bitstreams: 2 TESE Alberto César Cavalcanti França.pdf: 3788012 bytes, checksum: a84eaeee00c35211070eb3130be655f2 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2014
CNPq
Pesquisas na área de engenharia de software indicam que o gerenciamento apropriado da motivação e satisfação no trabalho são importantes para o sucesso de projetos de software. No entanto, rara tem sido a preocupação com o uso apropriado de teorias bem estabelecidas para fundamentar tais pesquisas, o que deixa em aberto várias questões práticas sobre motivação e satisfação no contexto do desenvolvimento de softwares. Evidências apontam que o conhecimento sobre a satisfação no trabalho, neste contexto, está relativamente consolidado, mas ainda há muito a se aprender sobre as características específicas que antecedem a motivação dos engenheiros de software. Objetivo: O ponto de partida compreende teorias de Satisfação no Trabalho e das Características do Trabalho, que defendem que motivação e satisfação no trabalho referem-se a fenômenos distintos. Esta tese objetiva então clarificar quais são as características do trabalho que influenciam a motivação de engenheiros de software. Método: Este quadro teórico inicial foi evoluído baseado nos aprendizados resultantes de um estudo de múltiplos casos, executado em quatro organisações de software em Recife-PE. Durante 11 meses, dados foram coletados nestas organizações, através de entrevistas semi-estruturadas, estudos diários, e análise documental. Resultados: Os resultados apontam que (1) engenheiros de software não estão conscientes sobre a distinção entre os dois fenômenos (motivação e satisfação no trabalho), (2) motivação é caracterizada pelo engajamento e concentração, (3) motivação é afetada por diversas características da tarefa do engenheiro de software, mas também pela percepção sobre o engajamento dos colegas de trabalho e pela auto-confiança técnica do trabalhador, (4) motivação contribui para a satisfação no trabalho, moderada pela informação provida sobre a performance individual dos engenheiros, e (5) o papel mediador das características pessoais do indivíduo é universal. Conclusão: Com base nestes dados, é proposta uma nova teoria de motivação e satisfação de engenheiros de software (TMS-SE) que une elementos de teorias bem estabelecidas, expandindo-as e adaptando-as à realidade específica de engenheiros de software. A TMS-SE representa um avanço em nossa compreensão do comportamento de engenheiros de software, bem como levanta novas questões e propõe um terreno organizado para futuras investigações nesta área.
Context: Previous research work in the Software Engineering field indicates that a proper management of motivation and job satisfaction at work can help software organisations to achieve higher levels of project success. However, the little concern with the adequate use of well-established theories to underpin these researches left unclear several theoretical and practical aspects of work motivation and job satisfaction in the software context. In fact, there is enough knowledge about job satisfaction factors, but not on specific characteristics of the work that motivate software engineers. Objective: The starting point of this research comprises the Job Satisfaction and the Job Characteristics theories, which argue that job satisfaction and work motivation are distinguishable phenomena, with distinct antecedents and different outcomes. Then, this thesis aims to clarify specifically what factors drive motivation of software engineers at work. Method: The initial theoretical framework was evaluated and enhanced based on findings from a multiple case study that comprised four different software organisations from Recife, Brazil. For 11 months, rich data was collected independently in those organisations, by means of semi-structured interviews, diary studies, and document analyses, and the synthesis followed a standard procedure of cross-case analysis. Results: The results point out that (1) practitioners are not aware of the distinction between work motivation and job satisfaction, (2) work motivation is characterized by engagement and concentration, (3) work motivation is affected by software engineering tasks characteristics and by the co-workers’ engagement, workload and technical confidence, (4) work motivation improves satisfaction moderated by feedback information provided about the individual’s performance, and (5) the mediating role of individual characteristics is pervasive. Conclusion: Based on these data, it was possible to draw up a new theory of motivation and satisfaction of software engineers (TMS-SE), which unites elements from well established theories, expands and adapts them to the software engineering specific context. The TMS-SE represents an advance on our understanding of software engineers’ behaviour as well as it raises new questions and provides an organised ground for future investigations in this area.

APA, Harvard, Vancouver, ISO, and other styles

22

Gomma, Hesham Wagih. "Robust and predictive control of 1.5 MW gas turbine engine." Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302533.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Neuenstadt, Christian [Verfasser]. "An engine for ontology-based stream processing theory and implementation / Christian Neuenstadt." Lübeck : Zentrale Hochschulbibliothek Lübeck, 2018. http://d-nb.info/1161750231/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Hassan, Nofal Adrees. "Adaptive-stochastic identification of an idling automotive I.C. engine." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316554.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Walls, Anna H. "Getting through difficult projects : a grounded theory of engineers' competence frontiers." Thesis, University of Canterbury. Civil Engineering, 2004. http://hdl.handle.net/10092/7919.

Full text

Abstract:

Engineers often become emotionally involved in their projects, experiencing them as exciting and satisfying, with times of intense frustration and anxiety. Previous research has not focused on this emotional involvement despite its centrality to engineers' experiences. This study explored engineers' experiences of being involved in difficult projects, that is, projects they find stressful or have difficulty coping with, and developed substantive theory on how they cope with such projects. The study used the Grounded Theory method, which is concerned with understanding people's concerns and how they go about resolving those concerns. The primary source of data was in-depth interviews with thirty-nine people, mainly civil engineers, from throughout New Zealand. Additional data included project documentation collated following the collapse of the Opuha Dam, and books about the past Ministry of Works (New Zealand). The common concern of engineers is centered on the inter-relationships between their projects and their competence frontiers. Each engineer has a competence frontier, which is the self-image of the extent of his or her competence. Difficult projects provide engineers with the opportunity to advance their competence frontiers, however, there is greater risk of being, or being seen to be, incompetent. Engineers cope with this concern by assessing whether they have done a good job and adjusting the extent to which they take ownership of their projects, while concurrently tackling the project tasks. These processes affect the nature of engineers' emotional involvement with projects, which then feeds back to influence those processes in a complex web of interactions. The study provides an interpretive understanding of the relationships between engineers and their projects, and why they find some projects difficult. It highlights the importance of engineers having projects of appropriate difficulty with good social support and a culture that supports realistic attributions of the factors that affect performance.

APA, Harvard, Vancouver, ISO, and other styles

26

Hmad, Ouadie. "Evaluation et optimisation des performances de fonctions pour la surveillance de turboréacteurs." Thesis, Troyes, 2013. http://www.theses.fr/2013TROY0029.

Full text

Abstract:

Cette thèse concerne les systèmes de surveillance des turboréacteurs. Le développement de tels systèmes nécessite une phase d’évaluation et d’optimisation des performances, préalablement à la mise en exploitation. Le travail a porté sur cette phase, et plus précisément sur les performances des fonctions de détection et de pronostic de deux systèmes. Des indicateurs de performances associés à chacune de ces fonctions ainsi que leur estimation ont été définis. Les systèmes surveillés sont d’une part la séquence de démarrage pour la fonction de détection et d’autre part la consommation d’huile pour la fonction de pronostic. Les données utilisées venant de vols en exploitation sans dégradations, des simulations ont été nécessaires pour l’évaluation des performances. L’optimisation des performances de détection a été obtenue par réglage du seuil sur la statistique de décision en tenant compte des exigences des compagnies aériennes exprimées en termes de taux de bonne détection et de taux d’alarme fausse. Deux approches ont été considérées et leurs performances ont été comparées pour leurs meilleures configurations. Les performances de pronostic de surconsommations d’huile, simulées à l’aide de processus Gamma, ont été évaluées en fonction de la pertinence de la décision de maintenance induite par le pronostic. Cette thèse a permis de quantifier et d’améliorer les performances des fonctions considérées pour répondre aux exigences. D’autres améliorations possibles sont proposées comme perspectives pour conclure ce mémoire
This thesis deals with monitoring systems of turbojet engines. The development of such systems requires a performance evaluation and optimization phase prior to their introduction in operation. The work has been focused on this phase, and more specifically on the performance of the detection and the prognostic functions of two systems. Performances metrics related to each of these functions as well as their estimate have been defined. The monitored systems are, on the one hand, the start sequence for the detection function and on the other hand, the oil consumption for the prognostic function. The used data come from flights in operation without degradation, simulations of degradation were necessary for the performance assessment. Optimization of detection performance was obtained by tuning a threshold on the decision statistics taking into account the airlines requirements in terms of good detection rate and false alarm rate. Two approaches have been considered and their performances have been compared for their best configurations. Prognostic performances of over oil consumption, simulated using Gamma processes, have been assessed on the basis of the relevance of maintenance decision induced by the prognostic. This thesis has allowed quantifying and improving the performance of the two considered functions to meet the airlines requirements. Other possible improvements are proposed as prospects to conclude this thesis

APA, Harvard, Vancouver, ISO, and other styles

27

Ding, Zhengtao. "Dynamic model uncertainty and change detection with application to a diesel engine." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292779.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Delivani, Eleni. "Tourism as an alternative engine of economic growth : the case of Greece : a Kaldorian approach." Thesis, University of York, 1991. http://etheses.whiterose.ac.uk/4261/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Aquino, Phillip A. "PREDICTION OF PREMIXED INTERNAL COMBUSTION ENGINE MASS FRACTON BURNED PROFILES USING A PHYSICAL FORM OF THE WIEBE FUNCTION AND THE THEORY OF TURBULENT FLAME BRUSH THICKNESS DYNAMICS." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1606987013001077.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Collier, D. A. "A comparative history of the development of the leading stationary steam engine manufacturers of Lancashire, c. 1800-1939." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370407.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Frank, Mario. "Axiom relevance decision engine : technical report." Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2014/7212/.

Full text

Abstract:

This document presents an axiom selection technique for classic first order theorem proving based on the relevance of axioms for the proof of a conjecture. It is based on unifiability of predicates and does not need statistical information like symbol frequency. The scope of the technique is the reduction of the set of axioms and the increase of the amount of provable conjectures in a given time. Since the technique generates a subset of the axiom set, it can be used as a preprocessor for automated theorem proving. This technical report describes the conception, implementation and evaluation of ARDE. The selection method, which is based on a breadth-first graph search by unifiability of predicates, is a weakened form of the connection calculus and uses specialised variants or unifiability to speed up the selection. The implementation of the concept is evaluated with comparison to the results of the world championship of theorem provers of the year 2012 (CASC J6). It is shown that both the theorem prover leanCoP which uses the connection calculus and E which uses equality reasoning, can benefit from the selection approach. Also, the evaluation shows that the concept is applyable for theorem proving problems with thousands of formulae and that the selection is independent from the calculus used by the theorem prover.
Dieser technische Report beschreibt die Konzeption, Implementierung und Evaluation eines Verfahrens zur Auswahl von logischen Formeln bezüglich derer Relevanz für den Beweis einer logischen Formel. Das Verfahren wird ausschließlich für die Prädikatenlogik erster Ordnung angewandt, wenngleich es auch für höherstufige Prädikatenlogiken geeignet ist. Das Verfahren nutzt eine unifikationsbasierte Breitensuche im Graphen wobei jeder Knoten im Graphen ein Prädikat und jede existierende Kante eine Unifizierbarkeitsrelation ist. Ziel des Verfahrens ist die Reduktion einer gegebenen Menge von Formeln auf eine für aktuelle Theorembeweiser handhabbare Größe. Daher ist das Verfahren als Präprozess-Schritt für das automatische Theorembeweisen geeignet. Zur Beschleunigung der Suche wird neben der Standard-Unifikation eine abgeschwächte Unifikation verwendet. Das System wurde während der Weltmeisterschaft der Theorembeweiser im Jahre 2014 (CASC J6) in Manchester zusammen mit dem Theorembeweiser leanCoP eingereicht und konnte leanCoP dabei unterstützen, Probleme zu lösen, die leanCoP alleine nicht handhaben kann. Die Tests mit leanCoP und dem Theorembeweiser E im Nachgang zu der Weltmeisterschaft zeigen, dass das Verfahren unabhängig von dem verwendeten Kalkül ist und bei beiden Theorembeweisern positive Auswirkungen auf die Beweisbarkeit von Problemen mit großen Formelmengen hat.

APA, Harvard, Vancouver, ISO, and other styles

32

Briceño, Simón Ignacio. "A game-based decision support methodology for competitive systems design." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26671.

Full text

Abstract:

This dissertation describes the development of a game-based methodology that facilitates the exploration and selection of research and development (R&D) projects under uncertain competitive scenarios. The proposed method provides an approach that analyzes competitor positioning and formulates response strategies to forecast the impact of technical design choices on a project's market performance. A critical decision in the conceptual design phase of propulsion systems is the selection of the best architecture, centerline, core size, and technology portfolio. A key objective of this research is to examine how firm characteristics such as their relative differences in completing R&D projects, differences in the degree of substitutability between different project types, and first/second-mover advantages affect their product development strategies. Several quantitative methods are investigated that analyze business and engineering strategies concurrently. In particular, formulations based on the well-established mathematical field of game theory are introduced to obtain insights into the project selection problem. The use of game theory is explored in this research as a method to assist the selection process of R&D projects in the presence of imperfect market information. The proposed methodology focuses on two influential factors: the schedule uncertainty of project completion times and the uncertainty associated with competitive reactions. A normal-form matrix is created to enumerate players, their moves and payoffs, and to formulate a process by which an optimal decision can be achieved. The non-cooperative model is tested using the concept of a Nash equilibrium to identify potential strategies that are robust to uncertain market fluctuations (e.g: uncertainty in airline demand, airframe requirements and competitor positioning). A first/second-mover advantage parameter is used as a scenario dial to adjust market rewards and firms' payoffs. The methodology is applied to a commercial aircraft engine selection study where engine firms must select an optimal engine project for development. An engine modeling and simulation framework is developed to generate a broad engine project portfolio. The proposed study demonstrates that within a technical design environment, a rational and analytical means of modeling project development strategies is beneficial in high market risk situations.

APA, Harvard, Vancouver, ISO, and other styles

33

Scopa, Stefano. "Non-equilibrium dynamics of driven low-dimensional quantum systems." Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0084/document.

Full text

Abstract:

Cette thèse analyse certains aspects de la dynamique hors équilibre de systèmes quantiques unidimensionnels lorsqu’ils sont soumis à des champs externes dépendant du temps. Nous considérons plus particulièrement le cas des forçages périodiques, et le cas d’une variation temporelle lente d’un paramètre de l’Hamiltonien qui permet de traverser une transition de phase quantique. La première partie contient une présentation des notions, des modèles et des outils nécessaires pour comprendre la suite de la thèse, avec notamment des rappels sur les modèles quantiques critiques (en particulier sur les chaines de spin et sur le modèle de Bose-Hubbard), le mécanisme de Kibble-Zurek, et la théorie de Floquet. Ensuite, nous étudions la dynamique hors équilibre des gaz de Tonks-Girardeau dans un potentiel harmonique dépendant du temps par différentes techniques : développements perturbatifs, diagonalisation numérique exacte et solutions analytiques exactes basées sur la théorie des invariants dynamiques d’Ermakov-Lewis. Enfin, nous analysons la dynamique hors équilibre des systèmes quantiques ouverts markoviens soumis à des variations périodiques des paramètres du système et de l’environnement. Nous formulons une théorie de Floquet afin d’obtenir des solutions exactes des équations de Lindblad périodiques. Ce formalisme de Lindblad-Floquet est utilisé pour obtenir une caractérisation exacte du fonctionnement en temps fini des machines thermiques quantiques
This thesis analyzes some aspects regarding the dynamics of one-dimensional quantum systems which are driven out-of-equilibrium by the presence of time- dependent external fields. Among the possible kinds of driven systems, our focus is dedicated to the slow variation of a Hamiltonian’s parameter across a quantum phase transition and to the case of a time-periodic forcing. To begin with, we prepare the background and the tools needed in the following. This includes a brief introduction to quantum critical models (in particular to the xy spin chain and to the Bose-Hubbard model), the Kibble-Zurek mechanism and Floquet theory. Next, we consider the non-equilibrium dynamics of Tonks-Girardeau gases in time-dependent harmonic trap potentials. The analysis is made with different techniques: perturbative expansions, numerical exact diagonalization and exact methods based on the theory of Ermakov-Lewis dynamical invariants. The last part of the thesis deals instead with the non-equilibrium dynamics of markovian open quantum systems subject to time-periodic perturbations of the system parameters and of the environment. This has led to an exact formulation of Floquet theory for a Lindblad dynamics. Moreover, within the Lindblad-Floquet framework it is possible to have an exact characterization ofthe finite-time operation of quantum heat-engines

APA, Harvard, Vancouver, ISO, and other styles

34

Farrall, Simon. "A study in the use of fuzzy logic in the management of an automotive heat engine/electric hybrid vehicle powertrain." Thesis, University of Warwick, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387380.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Buisman, Jacco. "Game Theory and Bidding for Software Projects An Evaluation of the Bidding Behaviour of Software Engineers." Thesis, Blekinge Tekniska Högskola, Institutionen för programvaruteknik och datavetenskap, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5850.

Full text

Abstract:

The conception phase is one of the most important phases of software projects. In this phase it is determined which software development company will perform a software project. To obtain a software project, companies can have several bidding strategies. This thesis investigates if and how game theory can be a helpful tool to evaluate bidding for software projects. This thesis can be divided into two different parts: a theoretical and a practical. The theoretical part investigates the applicable parts of game theory in this thesis, explains what software projects are, explains the difference between costing and bidding and provides results of a literature survey about bidding behaviour. The practical part introduces a study to investigate strategies and bidding behaviour of software engineers, explains the experimental design that found the study, provides the results of the performed study and a discussion of the results. This thesis concludes that game theory contains some concepts that make it possible to evaluate bidding for software projects.
Jacco Buisman Bonairestraat 32 9715 SE Groningen The Netherlands

APA, Harvard, Vancouver, ISO, and other styles

36

Xue, Jian. "Improvement of decoding engine & phonetic decision tree in acoustic modeling for online large vocabulary conversational speech recognition." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4821.

Full text

Abstract:

Thesis (Ph. D.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 4, 2008) Vita. Includes bibliographical references.

APA, Harvard, Vancouver, ISO, and other styles

37

Malik, Pravir. "Development and evaluation of a framework for an engine of innovation in complex adaptive systems." Thesis, University of Pretoria, 2017. http://hdl.handle.net/2263/62779.

Full text

Abstract:

The emerging, multi-disciplinary field of Complex Adaptive Systems (CAS) is an alternative to linear, reductionist thinking. It is based on the observations that real-world systems, regardless of scale, are emergent, complex, adaptive, and evolutionary. In this research the scale of CAS examined range from distances of Planck’s constant to Gigaparsecs. CAS has also heavily leveraged the interpretations of several recent Nobel Laureates and assumes too that the world is random, indeterministic, and chaotic. But randomness, chaos, and indeterminism can hardly create the progressive, increasingly harmonious world that we are a part of. At the heart of this issue lies confusion around what innovation in CAS really is. The essential approach to arriving at a mathematical basis of innovation for CAS here has been to view systems from the outside-in as opposed to from the inside-out and the bottom-up. In this approach innovation is conceptualized as existing in every single space-time point-instant in a system. There is a process of precipitation by which this innovation may express itself through a series of quaternary-based architectural forces that are the prime sources of innovation. These series or arrays of forces may further precipitate by informing organizational signatures. Organizations can be thought of as formations with a unique signature at their center, and can vary in complexity and scale. The unique signature for each organization is usually hidden though by common surface dynamics, and “to innovate” is to work through and change the habitual and common patterns in order to allow the deeper founts of innovation to become active at the surface level. When this happens, it is then that innovation occurs. Once that is more clearly seen then the erected probabilistic and uncertainty functions assumed to be true of the fundamental layers of nature, will be relegated to their place as interim devices in model building. The nature of innovation can be progressively elaborated through inductive reasoning to arrive at a mathematical framework for innovation in CAS. Rather than assume a chaotic, random, indeterministic world as a starting point, this framework can be built assuming a purposeful, ordered world characterized by qualified determinism. Equations to provide insight into the inherent innovation bias of our system, the nature of each point in the system, the broad architectural forces behind the development of organizations, the inherent uniqueness of each organization, the way to think about varying cultures or organizations, and the inherent dynamism of our system, form the edifice of this framework. The resulting model can then be used deductively to reinforce observations, and predictively to suggest directions and / or steps to emerging trends. This research hence, through deriving mathematical equations, and by further applying these to various domains ranging from the quantum, to the atomic, to the cellular, to the astrophysical, has been able to provide mathematical contributions to the theory of CAS and to various CAS application areas. With respect to the theory of CAS, mathematical contributions have been made to understanding the underlying directional bias of CAS activity, understanding the nature of each point in any CAS, and creating mathematical sets for architectural forces that are posited to be behind the development of any CAS. Further, mathematical contributions have been made to understanding the inherent dynamics in any CAS, the dynamics of stagnation and growth in CAS, and the balance of randomness and determinism of any CAS. Mathematical contributions also extend to framing complexity in CAS, understanding what can drive sustainability of CAS, and arriving at a general set of mathematical operators true of any CAS. In terms of application areas in the organizational space, mathematical contributions have been made to understanding uniqueness of organizations, the emergence of uniqueness in organizations, and what constitutes varying culture of organizations. Further, existing work done by Nobel Laureate Ilya Prigogine and Alan Turing have been leveraged to further frame organizational transitions, and to frame and model shifts in innovations, respectively. Further mathematical contributions have been made in a range of CAS areas at different scale and level of complexity. Hence, a series of equations have been derived for the electromagnetic spectrum. Quantum, atomic, and cellular wave equations have been derived building off Schrodinger’s existing Wave Equation. Further qualifications have been derived for Heisenberg’s Uncertainty Principle and an equation has been derived for the integration of different layers of CAS also using Heisenberg’s Uncertainty Principle. Equations for space and time alteration as per Einstein’s Theory of Relativity have also been derived. Additionally, equations for the architectures of quantum particles, periodic table elements, and molecular plans at the cellular level have also been derived. Finally, equations for dark matter and dark energy, non-probabilistic quantum states in quantum computing, and the emergence of CAS in the universe have been derived. In all over 225 equations in 25 different areas have been derived in this dissertation. In fact, as suggested by the CAS equation derived for a unified field, everything, from unseen energy fields, to quantum particles, to atoms, to molecules, to cells, and therefore to all animate and even inanimate and even unseen objects, and therefore even any CAS system regardless of scale would have a high-degree of quaternary intelligence embedded in it and exist simultaneously. Quoting Schrodinger: “What we observe as material bodies and forces are nothing but shapes and variations in the structure of space. Particles are just schaumkommen (appearances). The world is given to me only once, not one existing and one perceived. Subject and object are only one. The barrier between them cannot be said to have broken down as a result of recent experience in the physical sciences, for this barrier does not exist.” This implicit quaternary-based intelligence likely sheds new light on properties such as distributed control, uncertainty, paradox, co-evolution, emergence, amongst others, seen as fundamental to CAS. Thinking about CAS as purposeful, and animated by a mathematically-framed engine of innovation, allows existence to potentially be considered as a unified field. Further, it allows insight and additional solutions to a host of complex problems regardless of scale – at the quantum, cellular, human, organizational, sociotechnical, market, economical, political, and social levels - to be conceptualized, designed, elaborated, and managed differently.
Thesis (PhD)--University of Pretoria, 2017.
Graduate School of Technology Management (GSTM)
PhD
Unrestricted

APA, Harvard, Vancouver, ISO, and other styles

38

Vance, Jonathan Blake. "Neural network control of nonstrict feedback and nonaffine nonlinear discrete-time systems with application to engine control." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.umr.edu/thesis/pdf/Vance_09007dcc8043fb11.pdf.

Full text

Abstract:

Thesis (Ph. D.)--University of Missouri--Rolla, 2007.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 26, 2008) Includes bibliographical references.

APA, Harvard, Vancouver, ISO, and other styles

39

Buse, Kathleen Relihan. "Women Persisting in the Engineering Profession: A Paradoxical Explanation Adapting Intentional Change Theory." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1333586402.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Busch, Stephen [Verfasser], and U. [Akademischer Betreuer] Spicher. "The Theory and Application of Optical Diagnostic Techniques in the Combustion Chamber of a Diesel Engine / Stephen Busch. Betreuer: U. Spicher." Karlsruhe : KIT-Bibliothek, 2013. http://d-nb.info/1035450984/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Bednar, Kathrin, Sarah Spiekermann, and Marc Langheinrich. "Engineering Privacy by Design: Are engineers ready to live up to the challenge?" Taylor & Francis Group, 2019. http://epub.wu.ac.at/6695/1/01972243.2019.pdf.

Full text

Abstract:

Organizations struggle to comply with legal requirements as well as customers' calls for better data protection. On the implementation level, incorporation of privacy protections in products and services depends on the commitment of the engineers who design them. We interviewed six senior engineers, who work for globally leading IT corporations and research institutions, to inves- tigate their motivation and ability to comply with privacy regulations. Our findings point to a lack of perceived responsibility, control, autonomy, and frustrations with interactions with the legal world. While we increasingly call on engineers to go beyond functional requirements and be responsive to human values in our increasingly technological society, we may be facing the dilemma of asking engineers to live up to a challenge they are currently not ready to embrace.

APA, Harvard, Vancouver, ISO, and other styles

42

Shankar, Praveen. "Self-organizing radial basis function networks for adaptive flight control and aircraft engine state estimation." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1186767939.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Bäcke, Louise, Ellinor Hansen, and Linnea Johansson. "Mobile Search : An empirical investigation of the next big thing." Thesis, Linnéuniversitetet, Ekonomihögskolan, ELNU, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-19290.

Full text

Abstract:

The remarkable spread of the Internet has generated new opportunities for companies to promote themselves and communicate with their customers. The most used Internet service of finding information today is search engines (e.g. Google, Bing, Yahoo) were almost three million searches are preformed every minute worldwide. This trend has led to an importance for companies having their websites visible on these search engines. In addition, people tend to be more and more on the go and are searching with their smartphones instead of traditional personal computer (PC). Meaning that companies’ websites can be available for customers 24 hour a day, 7 days a week, independent on customers location. Consequently, companies have the possibilities to reach the attention of customers when they actually search for a product/service and are therefore most likely to purchase. In this thesis a marketing strategy has been developed for managers regarding how to master this new communication tool, in order to reach success and competitive advantage. This strategy was developed by investigate in what characteristics and functions users desire when searching with their smartphone. Together with three hypotheses tested if the perceived user-friendliness, relative advantage and compatibility within mobile search have a positive affect on the intention of use this new technology. In this bachelor thesis a survey was conducted among people in generation C living in Sweden, which resulted in 397 completed responses. The hypotheses were tested with use of a regression analysis and the findings were that the relative advantage and compatibility in mobile search has a positive affect on the intention of use. Therefore, this thesis suggests companies to develop their mobile search engine marketing strategy with the aim of delivering value and satisfying the customer. Moreover, this thesis recommend managers to keep their mobile website quick, relevant and making sure having valuable and informative information about their business in the description text visible to users in the search engine hit list. Finally, the majority of the population does already act on this new market and it is therefore of great importance for companies satisfying these users in order to stay competitive.

APA, Harvard, Vancouver, ISO, and other styles

44

Kea, Howard Eric. "How Are NASA Engineers Motivated? An Analysis of Factors that Influence NASA Goddard Engineers’ Level of Motivation." [Yellow Springs, Ohio] : Antioch University, 2008. http://www.ohiolink.edu/etd/view.cgi?acc_num=antioch1232149548.

Full text

Abstract:

Thesis (Ph.D.)--Antioch University, 2008.
Title from PDF t.p. (viewed March 19, 2009). Advisor: Jon Wergin, Ph.D. "A dissertation submitted to the Ph.D. in Leadership and Change program of Antioch University in partial fulfillment of the requirements for the degree of Doctor of Philosophy July 2008."--from the title page. Includes bibliographical references (p. 146-151).

APA, Harvard, Vancouver, ISO, and other styles

45

Blaha, Josef. "Stirlingův motor." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228037.

Full text

Abstract:

This dissertation discusses Stirling’s cycle and its contribution using different approaches. There are calculation of Schmidt’s theory and distinctiveness between ideal and real cycle described. Based on my previous research, this work provides a detailed summary of different methods which are used to stimulate Stirling’s cycles as well as the motor as a whole. Attention is particularly dedicated to current utilization of this machine which is not broadly known within general public.

APA, Harvard, Vancouver, ISO, and other styles

46

Zhang, Daili. "Multi-agent based control of large-scale complex systems employing distributed dynamic inference engine." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33963.

Full text

Abstract:

Increasing societal demand for automation has led to considerable efforts to control large-scale complex systems, especially in the area of autonomous intelligent control methods. The control system of a large-scale complex system needs to satisfy four system level requirements: robustness, flexibility, reusability, and scalability. Corresponding to the four system level requirements, there arise four major challenges. First, it is difficult to get accurate and complete information. Second, the system may be physically highly distributed. Third, the system evolves very quickly. Fourth, emergent global behaviors of the system can be caused by small disturbances at the component level. The Multi-Agent Based Control (MABC) method as an implementation of distributed intelligent control has been the focus of research since the 1970s, in an effort to solve the above-mentioned problems in controlling large-scale complex systems. However, to the author's best knowledge, all MABC systems for large-scale complex systems with significant uncertainties are problem-specific and thus difficult to extend to other domains or larger systems. This situation is partly due to the control architecture of multiple agents being determined by agent to agent coupling and interaction mechanisms. Therefore, the research objective of this dissertation is to develop a comprehensive, generalized framework for the control system design of general large-scale complex systems with significant uncertainties, with the focus on distributed control architecture design and distributed inference engine design. A Hybrid Multi-Agent Based Control (HyMABC) architecture is proposed by combining hierarchical control architecture and module control architecture with logical replication rings. First, it decomposes a complex system hierarchically; second, it combines the components in the same level as a module, and then designs common interfaces for all of the components in the same module; third, replications are made for critical agents and are organized into logical rings. This architecture maintains clear guidelines for complexity decomposition and also increases the robustness of the whole system. Multiple Sectioned Dynamic Bayesian Networks (MSDBNs) as a distributed dynamic probabilistic inference engine, can be embedded into the control architecture to handle uncertainties of general large-scale complex systems. MSDBNs decomposes a large knowledge-based system into many agents. Each agent holds its partial perspective of a large problem domain by representing its knowledge as a Dynamic Bayesian Network (DBN). Each agent accesses local evidence from its corresponding local sensors and communicates with other agents through finite message passing. If the distributed agents can be organized into a tree structure, satisfying the running intersection property and d-sep set requirements, globally consistent inferences are achievable in a distributed way. By using different frequencies for local DBN agent belief updating and global system belief updating, it balances the communication cost with the global consistency of inferences. In this dissertation, a fully factorized Boyen-Koller (BK) approximation algorithm is used for local DBN agent belief updating, and the static Junction Forest Linkage Tree (JFLT) algorithm is used for global system belief updating. MSDBNs assume a static structure and a stable communication network for the whole system. However, for a real system, sub-Bayesian networks as nodes could be lost, and the communication network could be shut down due to partial damage in the system. Therefore, on-line and automatic MSDBNs structure formation is necessary for making robust state estimations and increasing survivability of the whole system. A Distributed Spanning Tree Optimization (DSTO) algorithm, a Distributed D-Sep Set Satisfaction (DDSSS) algorithm, and a Distributed Running Intersection Satisfaction (DRIS) algorithm are proposed in this dissertation. Combining these three distributed algorithms and a Distributed Belief Propagation (DBP) algorithm in MSDBNs makes state estimations robust to partial damage in the whole system. Combining the distributed control architecture design and the distributed inference engine design leads to a process of control system design for a general large-scale complex system. As applications of the proposed methodology, the control system design of a simplified ship chilled water system and a notional ship chilled water system have been demonstrated step by step. Simulation results not only show that the proposed methodology gives a clear guideline for control system design for general large-scale complex systems with dynamic and uncertain environment, but also indicate that the combination of MSDBNs and HyMABC can provide excellent performance for controlling general large-scale complex systems.

APA, Harvard, Vancouver, ISO, and other styles

47

Cruz, Vinicius Guimarães da. "Desenvolvimento experimental de um motor stirling tipo gama." Universidade Federal da Paraíba, 2012. http://tede.biblioteca.ufpb.br:8080/handle/tede/5341.

Full text

Abstract:

Made available in DSpace on 2015-05-08T14:59:44Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2663529 bytes, checksum: 5f0d6dec066e59a555afa41866bdae84 (MD5) Previous issue date: 2012-09-06
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The current paper develops an experimental Stirling engine Gama type. Different settings of this type of engine are presented (alpha, beta and gamma), along with the Stirling Cycle Definition and the mathematical modeling for each setting. It´s been Proceed a mathematical analysis based on the Stirling Theory, which is the method based upon the isothermical compression and expansion of an ideal gas, put to analysis by a computer software, determining the dependency between the engine s construction and functioning parameters. Bibliography used takes over the main Stirling engine settings and various working conditions, fed by a numerous types of fuels. The experimental part of the paper is assembling of a Stirling engine gamma type containing no regenerator, therefore, having the air as its working fluid, using electrical resistances as heat source, also a water jet at ambiance temperature to cool down the compression and heat exchanger. Engine tests were performed at atmospheric pressure, temperatures from 100 to 600 °C, 100 to 400 rpm rotations. The results are presented in graphics and are questioned.
O presente trabalho consiste no desenvolvimento experimental de um motor Stirling tipo gama. São apresentadas inicialmente as diferentes configurações deste tipo de motor (alfa, gama e beta), a definição do ciclo de Stirling e a modelagem matemática para cada configuração. Uma análise matemática é feita através da teoria de Schmidt, que é um método baseado na compressão e expansão isotérmica de um gás ideal, implementada em programa computacional permitindo determinar a dependência entre os parâmetros construtivos e de funcionamento do motor. A revisão bibliográfica contempla as principais configurações de motores Stirling e várias condições de funcionamento, alimentados por diversos tipos de combustíveis. A parte experimental do trabalho é a montagem de um protótipo de motor Stirling tipo gama sem regenerador tendo o ar como fluido de trabalho, utilizando resistências elétricas como fonte de calor e um fluxo de água a temperatura ambiente para o resfriamento do trocador de calor de compressão. Os testes do motor serão realizados a pressão atmosférica, para temperaturas de 100 a 600 °C e rotações de 100 a 400 rpm, os resultados são apresentados em gráficos e discutidos.

APA, Harvard, Vancouver, ISO, and other styles

48

Machado, Luis Paulo Silveira. "Propagação do momento linear e energia cinética em cadeias granulares afiladas." Universidade Federal da Paraíba, 2011. http://tede.biblioteca.ufpb.br:8080/handle/tede/5717.

Full text

Abstract:

Made available in DSpace on 2015-05-14T12:14:04Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 2897753 bytes, checksum: dcf36c9ad33420797b30ee420d027633 (MD5) Previous issue date: 2011-07-29
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Recently, tapered granular chains have been studied for the development of impact-absorbing devices (shock waves). The characteristic of this system to mitigate shock waves (pulses of linear momentum), makes this material an excellent candidate for such absorbers. Therefore, many studies have been conducted in this direction, but most are numeric character, and some analytical. However, the analytical approximations presented do not show good fits with numerical solutions. In this work we study analytically the propagation of linear momentum and kinetic energy in one-dimensional tapered chains of spherical grains that interact according to the Hertz potential. We apply the binary approximation, based on the supposition that the energy transferred along the chain occurs through successive collisions between two particles. Four settings taper were studied: forward linear, forward exponential, backward linear and backward exponential. With the Binary Theory, we correctly anticipate the trends of increase and decrease the propagation of linear momentum and kinetic energy. However, to capture the correct values of the amplitudes of the pulses of these quantities we developed a numericalanalytic correction to the velocities of particles. Compared the results with numerical solutions of the equations of motion, where we use the Runge-Kutta fourth order. The results show: good agreement between the analytical and numerical theories; forward exponentially tapered chains are the most suitable in the design of absorbers (present exponential decay of linear momentum); a weaker scenario for the propagation of kinetic energy (due to quadratic dependence with the velocity), but the linear momentum is the quantity relevant in the context of impacts.Furthermore, we found good agreement with experimental results presented by F. Melo et al (2006). Thus, we present analytical expressions that capture correctly the propagation of linear momentum and kinetic energy in tapered granular chains. These systems actually demonstrate be excellent for absorbing shock waves, attenuating pulses of linear momentum and saturating kinetic energy. An extension of this work is to study tapered decorated chains and with precompression, allowing the absorption in chains composed of a number smaller grains (short chains).
Recentemente, cadeias granulares afiladas tem sido objeto de estudo para o desenvolvimento de dispositivos absorvedores de impacto (ondas de choque). A caracterıstica deste sistema em atenuar ondas de choque (pulsos de momento linear), torna este material um excelente candidato para tais absorvedores. Assim, vários estudos neste sentido foram realizados, por´em a maioria são de caráter numérico e, alguns, anal´ıticos. Todavia, as aproximaçoes analıticas apresentadas não demonstram bons ajustes com soluções numericas. Neste trabalho estudamos analiticamente a propagação do momento linear e energia cinetica em cadeias afiladas unidimensionais de graos esfericos que interagem segundo o potencial de Hertz. Aplicamos a aproximaçao binaria, baseada na suposiçao que a energia transferida ao longo da cadeia ocorre atraves de colis oes sucessivas entre duas part´ıculas. Estudamos quatro configuraçoes de afilamento: linear para frente, exponencial para frente, linear para tras e exponencial para tras. Com a Teoria Binaria, prevemos corretamente as tendencias de aumento e diminuiçao das propagaçoes do momento linear e energia cinetica. Contudo, para capturarmos os valores corretos das amplitudes dos pulsos dessas grandezas desenvolvemos uma correçao numerico-analıtica para as velocidades das partıculas. Confrontamos os resultados com soluçoes numericas das equaçoes de movimento, onde utilizamos o metodo de Runge-Kutta de quarta ordem. Os resultados demonstram: bom acordo entre as teorias analıtica e numerica; as cadeias afiladas exponencialmente para frente são as mais indicadas nos projetos de absorvedores (apresentam decaimento exponencial do momento linear); um cen´ario mais fraco para a propagação da energia cinetica (devido a dependencia quadratica com a velocidade), porem o momento linear e a grandeza relevante no contexto de impactos. Alem disso, obtivemos bom acordo com resultados experimentais apresentados por F. Melo e colaboradores (2006). Dessa forma, apresentamos expressoes analıticas que capturam corretamente as propagaçoes de momento linear e energia cinetica em cadeias granulares afiladas. Estes sistemas, realmente demonstram serem excelentes para absorver ondas de choque, atenuando pulsos de momento linear e saturando pulsos de energia cin´etica.Uma extensao deste trabalho sera estudar cadeias decoradas afiladas com pre-compressao, que permitem a absorçao de ondas de choque com numero menor de graos nas cadeias (cadeias curtas).

APA, Harvard, Vancouver, ISO, and other styles

49

Kovář, Michal. "Indikace tlaku ve válcích modelu Stirlingova motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228846.

Full text

Abstract:

This thesis describes the design chain to indicate the measuring cylinder Stirling engine. It describes the practical problems of measurement methodology and highlights the possible pitfalls of the measuring chain. For measuring the use of pre-existing model of gamma Stirling engine modification. It was carried out systematic measurement and evaluation of measured data. As a mathematical model for comparison with the measured data was used ideal cycle and Schmidt theory.

APA, Harvard, Vancouver, ISO, and other styles

50

Jakel, Roland. "Analysis of Hyperelastic Materials with Mechanica - Theory and Application Examples." Universitätsbibliothek Chemnitz, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-201000705.

Full text

Abstract:

Part 1: Theoretic background information - Review of Hooke’s law for linear elastic materials - The strain energy density of linear elastic materials - Hyperelastic material - Material laws for hyperelastic materials - About selecting the material model and performing tests - Implementation of hyperelastic material laws in Mechanica - Defining hyperelastic material parameters in Mechanica - Test set-ups and specimen shapes of the supported material tests - The uniaxial compression test - Stress and strain definitions in the Mechanica LDA analysis Part 2: Application examples - A test specimen subjected to uniaxial loading - A volumetric compression test - A planar test - Influence of the material law Appendix - PTC Simulation Services Introduction - Dictionary Technical English-German
Teil 1: Theoretische Hintergrundinformation - Das Hookesche Gesetz für linear-elastische Werkstoffe - Die Dehnungsenergiedichte für linear-elastische Materialien - Hyperelastisches Material - Materialgesetze für Hyperelastizität - Auswählen des Materialgesetzes und Testdurchführung - Implementierung der hyperelastischen Materialgesetze in Mechanica - Definieren der hyperelastischen Materialparameter in Mechanica - Testaufbauten und Prüfkörper der unterstützten Materialtests - Der einachsige Druckversuch - Spannungs- und Dehnungsdefinition in der Mechanica-Analyse mit großen Verformungen Teil 2: Anwendungsbeispiele - Ein einachsig beanspruchter Prüfkörper - Ein volumetrischer Drucktest - Ein planarer Test - Einfluss des Materialgesetzes Anhang: - Kurzvorstellung der PTC Simulationsdienstleistungen - Wörterbuch technisches Englisch-Deutsch

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Theory of engines'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles