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1
Olanrewaju, Oluwabamise. "Impact of the European gas network on the operation of Great Britain's gas and electricity networks." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/100254/.
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Recent events of natural gas supply disruption in Europe have led to severe consequences of supply shortages to some European Member States. As the United Kingdom increasingly depend on imported gas supply from different sources including Continental Europe, the effect of gas supply disruption in Europe on UK’s gas consumers is in question. This thesis investigated the effect of gas supply disruptions in Europe on the operation of the Great Britain’s gas and electricity network using a set of modelling tools. An optimisation model of the European gas network was developed to assess the resilience of the European gas network to the loss of gas supply through the Ukraine transit pipelines to Europe. The results showed that unserved gas demand occurred in South East Europe. It was shown that additional interconnector capacities of selected pipelines and higher storage withdrawal rate in South East Europe minimised unserved gas demand in South East Europe. A soft-link coupling of the European Gas Network model (EGN) and the Combined Gas and Electricity Network model (CGEN) was developed and used to examine the effect of a 90-day loss of Ukraine transit capacity in Europe on the operation of GB gas and electricity network at a period of limited LNG supply to Europe. The result showed that in a high gas demand situation, industrial customers would experience some amount of unserved gas demand. The effectiveness of the mitigation options to prevent or mitigate unserved gas in GB was analysed using the EGN-CGEN model. Then a cost-benefit assessment tool was used to rank the mitigation options according to the net benefit of reducing the cost of unserved gas demand in GB. It was shown that diversification of gas supply sources and routes in Europe would deliver significant security of supply benefit to GB gas and electricity network.
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Morgan, Christopher. "Gas sensing with carbon nanotube networks." Thesis, Queen Mary, University of London, 2009. http://qmro.qmul.ac.uk/xmlui/handle/123456789/480.
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Carbon nanotubes are an exciting new material with exemplary mechanical and electronic properties. Carbon nanotubes can be either metallic or semiconducting; either type has properties which rival conventional materials. The one-dimensional electronic nature of these materials leads to extreme sensitivity to the local energy landscape, a desirable property for a sensing element. Production of carbon nanotubes currently has no method of growing nanotubes with a speci c electronic property, any di erentiation occurs through processing a heterogenous ensemble. Recently, networks of carbon nanotubes have shown attractive properties for electronic applications. The self-selecting current path has properties averaged from the ensemble of nanotubes providing repeatability in addition to exibility and transparency. This thesis is a study of the transport properties of thin and thick networks of single-walled carbon nanotubes and their electrical response to oxygen adsorption in both a simple resistive geometry and as the gate layer in a nanotube-metal-oxide-silicon capacitor. The thickness of network was found to determine the electrical characteristics of the network ensemble, thin networks displaying semiconducting transport characteristics, thick networks becoming more metallic. The response of the nanotube networks to oxygen exposure was found to be dependent on UV treatment. UV-desorbed networks exhibited an increased conductance upon oxygen-exposure, adsorbed networks exhibited a decrease in conductance upon further oxygen-exposure. Thinner, more semiconducting nanotube networks exhibited a greater change in conductance upon oxygen exposure. The nanotube-metal-oxide-semiconductor capacitor also showed a greater change in at-band capacitance for thin nanotube networks. The capacitance of the nanotube device at the nanotube network at-band voltage is shown to be in uenced by both oxygen and nitrogen gases. The origin of the behaviour of the at-band voltage is attempted to be understood and future work is suggested. 4.
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André, Jean. "Optimization of investments in gas networks." Littoral, 2010. http://www.theses.fr/2010DUNK0286.
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Les réseaux de transport de gaz naturel nécessitent des investissements très importants pour faire face à une demande toujours croissante en énergie et pour satisfaire des contraintes réglementaires de plus en plus importantes. En effet, la libéralisation des marchés gaziers a imposé aux opérateurs de transport de gaz, d’une part, des règles de transparence d’un monopole naturel pour justifier leurs dépenses et, in fine, leurs tarifs, et , d’autre part, des objectifs de fluidification du marché afin de faciliter l’accès a la concurrence des clients finaux. Ces investissements majeurs justifient l’utilisation de techniques d’optimisation permettant de réduire leurs coûts. Vu la présence de choix discrets (choix de la localisation des investissements, choix limité de capacités supplémentaires, planification temporelle) en combinaison avec des contraintes physiques non linéaires (représentant la relation entre l’´ecoulement et les pressions dans les canalisations ou la plage de fonctionnement des compresseurs), les programmes à résoudre sont des programmes d’optimisation non linéaires en nombres entiers (PNLNE) de grandes tailles. Ce type de programmes étant connu pour être particulièrement difficile à résoudre en temps polynomial (NP-difficile), des méthodes avancées d’optimisation doivent être mises en oeuvre pour obtenir des réponses réalistes. Les objectifs de cette thèse sont au nombre de trois. Il s’agit d’abord de proposer une modélisation des problèmes d’investissement dans les réseaux de transport de gaz à partir des motivations du monde industriel. Il s’agit ensuite d’identifier les méthodes et algorithmes les plus adéquats pour résoudre les problèmes ainsi formulées. Il s’agit enfin d’évaluer les avantages et les inconvénients de ces méthodes à l’aide d’applications numériques sur des cas réelsThe natural gas networks require very important investments to cope with a still growing demand and to satisfy the new regulatory constraints. The gas market deregulation imposed to the gas network operators, first, transparency rules of a natural monopoly to justify their costs and ultimately their tariffs, and, second, market fluidity objectives in order to facilitate access for competition to the end-users. These major investments are the main reasons for the use of optimization techniques aiming at reducing the costs. Due to the discrete choice (investment location, limited choice of additional capacities, timing) crossed with physical non linear constraints (flow/pressure relations in the pipe or operating ranges of compressors), the programs to solve are Large Mixed Non Linear Programs (MINLP). As these types of programs are known to be hard to solve exactly in polynomial times (NP-hard), advanced optimization methods have to be implemented to obtain realistic results. The objectives of this thesis are threefold. First, one states several investment problems modeling of natural gas networks from industrial world motivations. Second, one identifies the most suitable methods and algorithms to the formulated problems. Third, one exposes the main advantages and drawbacks of these methods with the help of numerical applications on real causes
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Chaudry, Modassar. "Interactions beween gas and electricity networks." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529224.
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Choudhary, P. A. "State estimation applied to gas distribution networks." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378007.
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The need to make more efficient use of energy resources by improved methods of control, the deferment of expensive pipework reinforcement or replacement and the requirement to accommodate different loading patterns on sections of the gas network have made the requirement for effective feedback control essential. Gas distribution systems are large and complex and a major problem in applying conventional feedback techniques is the cost and reliability of transmitting the data necessary for automatic control. In order to overcome these difficulties, state estimation techniques have been investigated as a means of providing information about a distribution system from a minimum number of measurement points. The theoretical background to the study is reviewed including the modelling technique and the results of experimental work which has been performed on a distribution network in order to verify the techniques developed are presented. The results show that state estimation techniques have considerable potential for this type of application.
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Pearson, D. W. "Robust observer design and application to gas networks." Thesis, Coventry University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380696.
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Wong, Man Lam. "The application of constrained optimization gas transmission networks." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235972.
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Parkinson, J. S. "Control system design for low pressure gas distribution networks." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378367.
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SILVA, MARILIA PAULA E. "ARTIFICIAL NEURAL NETWORKS APPLIED TO GAS TURBINE FAULT DIAGNOSTICS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=16580@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROA deterioração do desempenho da turbina a gás é resultado de vários tipos de falhas, como acúmulo de sujeira, erosão e corrosão, que afetam os componentes no caminho do gás, sendo os principais o compressor, o combustor e a turbina. No presente trabalho é avaliado o desempenho de Redes Neurais Artificiais (RNA) no emprego de diagnóstico de falha de turbinas a gás. Todas as redes projetadas são do tipo MLP (multi-layer perceptron) com algoritmo de retropropagação (backpropagation). Para cada função de diagnóstico, várias arquiteturas foram testadas, modificando parâmetros de rede como o número de camadas escondidas e o número de neurônios em cada uma destas camadas. As RNAs para diagnóstico de falhas foram aplicadas ao modelo termodinâmico de uma turbina a gás industrial. Este modelo foi responsável pela criação de dados da usina saudável e também degradada, utilizados para o treinamento e validação das redes. Com os resultados obtidos do treinamento das redes é possível mostrar que as mesmas são capazes de detectar, isolar e quantificar falhas de componentes de turbinas a gás de forma satisfatória.
The gas turbine performance deterioration is a result of several types of faults such as fouling, erosion and corrosion, which affects the components throughout the gas path. As the most significant of these components we can enumerate the compressor, the combustion chamber and the turbine itself. In this work the performance of different types of Artificial Neural Networks (ANN) are evaluated in the diagnosis of this kind of fault. Every neural network designed in this work is MLP (multi-layer perceptron) with back propagation algorithm. For each diagnosis function several architectures were tested, varying network parameters as the numbers of hidden layers and the number of neurons in each layer. The ANNs for fault diagnosis were applied in an industrial gas turbine thermodynamic model. This model was also used for healthy and degraded turbine data generation, which were used for ANNs training and validation. With the ANNs training results we can conclude that these networks are capable of detecting, isolating and quantifying gas turbine components faults in a satisfactory way.
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Hosseini, Seyed. "State estimation of integrated power and gas distribution networks." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/109819/.
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Future energy networks are likely to be highly integrated with several energy conversion utilities operating between them, which make the control and management of the whole system more complicated. Therefore, analysis of operation and management of the whole system needs to be performed in an integrated approach. In order to perform an effective control and management of the whole system, an accurate and reliable estimation of the state parameters and the energy flows within the integrated network is essential. In this research simulation and state estimation of integrated power and gas distribution networks with decentralised injection and generation in both networks was investigated. For this purpose, state estimation of individual networks was first reviewed. Afterwards, state estimation of integrated power and gas distribution networks was studied. Firstly, an algorithm was developed for state estimation of power distribution networks, which was validated through a case study power distribution network. Afterwards, an algorithm for placement of additional measurements within power distribution networks for improvement of state estimation results was developed. The performance of the algorithm showed satisfactory results for placement of a given number of additional individual measurements and a given number of additional measurement units. Secondly, an algorithm was developed for simulation of operation of gas distribution networks with decentralised injection, which was validated with the results of the commercial software Synergi Gas. Then, an algorithm was developed for the WLS state estimation of gas distribution networks with decentralised injection, which was validated on a case study gas distribution network. Afterwards, an algorithm was developed for placement of additional measurements within gas distribution networks with decentralised injection for improvement of estimation of the gas mixtures within the network, which showed satisfactory results on a case study gas distribution network. Finally, an algorithm was developed for performing state estimation of power and gas distribution networks with decentralised injection and generation in both networks, which was validated on a case study power and gas distribution network. Afterwards, impact of deployment of smart meters on improvement of estimation of the state parameters of the other coupled network was investigated. It was observed that information from one of the energy networks has no significant impact on improvement of state estimation results of the other coupled network.
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Ramli, Muhammad M. "Carbon nanotubes and graphene oxide networks for gas sensing." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/807845/.
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Nowadays, Carbon Nanotubes (CNTs) and Graphene Oxide (GO) have attracted enormous interest in various applications such as thin film transistors, chemical sensors, field emission devices and transparent conductive coatings. In this report, thin films of CNT and GO networks were fabricated as a two-terminal device for gas sensing applications. These devices were fabricated using vacuum filtration and drop casting methods at room temperature in order to get a thin and uniform film. The electrical measurement was conducted in order to investigate the film resistance as the solution concentration increased. The multi – walled carbon nanotubes (MWCNTs) solutions were acid treated by attaching carboxylic acid (-COOH) groups, in order to form a stable aqueous suspension with a neutral pH. The conductivity of the networks film was increased as the solution concentration increased where the sheet resistance at the highest concentration (0.125 mg/ml) was around 7.09 kΩ/sq. The single – walled carbon nanotubes (SWCNTs) suspension was produced using an organic dye in order to improve its solubility in water. Raman spectroscopy showed that no damage to the structure of SWCNTs was occurred. The GO suspension was produced by the chemical exfoliation of graphite through oxidation. The basal plane and edges of GO were decorated by oxygen functional groups, hence improving its solubility in water. To decrease the concentration of solutions, the solutions were diluted with methanol or water and various concentrations were achieved. The extreme sensitivity to changes in CNTs and GO local chemical environment makes them an ideal candidate for gas sensing application. The devices were tested by exposure to gasses such as NO2 and NH3. Results show a tremendous sensitivity towards NO2 and NH3 gasses. The sensitivities of the MWCNTs sensor device were ranging from 2 to 20 %. Whereas for the SWCNTs sensor device, the sensitivities were ranging from 20 to 50 %. For the GO sensor devices, the optimum sensitivity was achieved when the device was exposed at room temperature. The changes in resistance of the devices reflected the interaction mechanism that happened between exposure gasses (NO2 and NH3) and the materials.
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Qureshi, Suhail Aftab. "Calculation of fast transients in gas insulated substations." Thesis, University of Manchester, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363514.
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Smith, Clinton James. "High-accuracy laser spectrometers for wireless trace-gas sensor networks." Thesis, Princeton University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3604506.
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The subject of this dissertation is the development of a wireless sensor network composed of instruments which employ both VCSELs and QCLs for accurate, highly sensitive, and reliable long-term monitoring of environmental trace-gases. The dissertation focuses on the development of low-power instruments and calibration methods that ensure the reliability of long-term measurements.
First the field deployment of a low-power, portable, wireless laser spectroscopic sensor node for atmospheric CO2 monitoring is demonstrated. The sensor node shows 0.14 ppmv Hz-1/2 1σ measurement sensitivity of CO2 concentration changes. It was first used to measure top-soil respiration rates in the laboratory and on forest floors in the field.
Then after a long-term field deployment to further assess instrument performance, new design solutions were implemented to improve fringe-limited precision of the nodes to 4-7 ppmv against a 400 ppmv CO2 background, making their performance comparable to higher power consuming commercial trace-gas analyzers. Three optimized nodes were then deployed into mixed landscapes as part of a solar powered CO2 monitoring wireless network. The three node network monitored CO2 in a grassy/woody courtyard, on top of the roof of an engineering building, and next to a road in the Princeton area. These works show that ultra-low powered VCSEL based sensor nodes can be placed in off-the-grid environments for autonomous distributed geographic monitoring of trace-gases in a manner which is impossible with current commercial techniques.
Next, this dissertation covers two techniques that were developed for the real-time calibration of laser-based trace-gas measurements. The first technique used an in-line reference gas cell and employed wavelength modulation spectroscopy (WMS) at higher harmonics to simultaneously probe the sample and reference spectra. The second technique used a revolving in-line reference cell to suppress background and other non-spectroscopic signals. These techniques were designed for eventual inclusion as a real-time calibration source for field deployable trace-gas sensors and wireless sensor networks.
Finally, this dissertation demonstrates the use of the CW injection current into a VCSEL in an external cavity configuration to tune the cavity emission's self-oscillation frequency and show through simulation and experiment that the tuning is dependent on VCSEL birefringence change.
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Afzal, Muhammad. "Mathematical modelling of gas flow networks in pellet induratlon systems." Thesis, University of Greenwich, 1994. http://gala.gre.ac.uk/5700/.
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The objective of this research is to develop a simulation software tool, GASFLO, which should evaluate pressure, flow and temperature distributions of process gas in pellet induration system networks. Pellet induration systems are complex industrial systems composed of heterogenous components. The magnitude of gas through leaks i.e. the air entering or leaving the system from the points other than the known exits, is substantial and it adversely effects the performance of induration process. These leaks are very difficult to measure because of the hostile environment in the plant. The modelling of such industrial systems requires a notable amount of experimentation so the tool has been designed to enable the user modeller to change the component models and solution algorithms easily. The conventional methods for flow network simulation are based on process centred approach, mostly composed of homogeneous components. For ease of computation, the non-pipe elements are modelled with an approximate linear or non-linear generic equation, whose coefficients can simulate different states of the element. The resulting set of non-linear equations is linearised and solved simultaneously using some iterative method. By contrast, GASFLO is based on device centred or unit based approach, and uses a two level hierarchical solution algorithm. The pellet induration system network is first idealised into a connected graph of streams (sets of serially connected components) and nodes. At the top or coordination level the flow and pressure distributions satisfying the Kirchhoff's laws are evaluated for the connected graph. At the lower or component level the exact mathematical models of components ale computed, in order of their occurrence in respective streams, using coordination variables as parameters. The converged flows are used for the temperature computation. The solution algorithm requires partitioning of the connected graph into forest and coforest structures, for which secondary algorithms have been developed using specific heuristics relevant to the pellet induration systems. The rigorous application of software engineering techniques for the design and implementation of software, enabled the resolution of the complexity of the modelled system, embedded the characteristics of 'quality software' into the resulting code and benefits from object orientation, even though it is implemented in standard FORTRAN 77. GASFLO predicted results are in a good agreement with the measured results, it has been validated for a real life pellet induration system. It has been applied to simulate several practical scenarios, like addition of extra wind boxes to the zones and to determine how the plant production can be increased by certain ratio, such simulations were not feasible otherwise. GASFLO takes less than a minute to simulate a real-life pellet induration system on a 486 PC. The combined simulation with an other software tool, INDSYS, which evaluates the heat distribution in the solids, is also feasible.
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Morsi, Antonio [Verfasser]. "Solving MINLPs on Loosely-Coupled Networks with Applications in Water and Gas Network Optimization / Antonio Morsi." München : Verlag Dr. Hut, 2013. http://d-nb.info/1042878153/34.
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Taylor, John David. "Numerical analysis of fast and slow transients in gas transmission networks." Thesis, Heriot-Watt University, 1997. http://hdl.handle.net/10399/1218.
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Kolb, Oliver [Verfasser]. "Simulation and Optimization of Gas and Water Supply Networks / Oliver Kolb." München : Verlag Dr. Hut, 2011. http://d-nb.info/1016531478/34.
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Asgari, Hamid. "Modelling, Simulation and Control of Gas Turbines Using Artificial Neural Networks." Thesis, University of Canterbury. Mechanical Engineering, 2014. http://hdl.handle.net/10092/9355.
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This thesis investigates novel methodologies for modelling, simulation and control of gas turbines using ANNs. In the field of modelling and simulation, two different types of gas turbines are modelled and simulated using both Simulink and neural network based models. Simulated and operational data sets are employed to demonstrate the capability of neural networks in capturing complex nonlinear dynamics of gas turbines. For ANN-based modelling, the application of both static (MLP) and dynamic (NARX) networks are explored. Simulink and NARX models are set up to explore both steady-state and transient behaviours.
To develop an offline ANN-based system identification methodology for a low-power gas turbine, comprehensive computer program code including 18720 different ANN structures is generated and run in MATLAB to create and train different ANN models with feedforward multi-layer perceptron (MLP) structure. The results demonstrate that the ANN-based method can be applied accurately and reliably for the system identification of gas turbines.
In this study, Simulink and NARX models are created and validated using experimental data sets to explore transient behaviour of a heavy-duty industrial power plant gas turbine (IPGT). The results show that both Simulink and NARX models successfully capture dynamics of the system. However, NARX approach can model gas turbine behaviour with a higher accuracy compared to Simulink approach. Besides, a separate complex model of the start-up operation of the same IPGT is built and verified by using NARX models. The models are set up and verified on the basis of measured time-series data sets. It is observed that NARX models have the potential to simulate start-up operation and to predict dynamic behaviour of gas turbines.
In the area of control system design, a conventional proportional-integral-derivative (PID) controller and neural network based controllers consisting of ANN-based model predictive (MPC) and feedback linearization (NARMA-L2) controllers are designed and employed to control rotational speed of a gas turbine. The related parameters for all controllers are tuned and set up according to the requirements of the controllers design. It is demonstrated that neural network based controllers (in this case NARMA-L2) can perform even better than conventional controllers. The settling time, rise time and maximum overshoot for the response of NARMA-L2 is less than the corresponding factors for the conventional PID controller. It also follows the input changes more accurately than the PID.
Overall, it is concluded from this thesis that in spite of all the controversial issues regarding using artificial neural networks for industrial applications, they have a high and strong potential to be considered as a reliable alternative to the conventional modelling, simulation and control methodologies. The models developed in this thesis can be used offline for design and manufacturing purposes or online on sites for condition monitoring, fault detection and trouble shooting of gas turbines.
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Mindt, Pascal [Verfasser], Jens [Akademischer Betreuer] Lang, and Michael [Akademischer Betreuer] Herty. "Hierarchical Gas Model Coupling on Networks / Pascal Mindt ; Jens Lang, Michael Herty." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1195141777/34.
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Stringer, Simon M. "The use of robust observers in the simulation of gas supply networks." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357129.
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Clegg, Stephen. "Integrated modelling of electrical and gas transmission networks in multi-energy systems." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/integrated-modelling-of-electrical-and-gas-transmission-networks-in-multienergy-systems(e1b07a2b-8bd2-472d-8274-8d54978e9770).html.
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The scope of this thesis is an investigation into the interactions between the gas and electrical transmission networks in the context of a low-carbon energy system with explicit considerations of the role played by multi-energy vectors, including heating, in future scenarios. Many energy systems are in a state of transition due to the growing need to reduce their carbon impact while maintaining reliability and reducing costs. The generation capacity of gas-fuelled power stations, as a cleaner alternative to coal, has been continuing to grow in many power systems. Furthermore, their operational characteristics are evolving as they are increasingly used to meet demand when there is a shortfall in renewable generation and are playing a role in contributing to the reliability of the power system. Additionally, changes to the heating sector (e.g., the electrification of heat or the increased use of combined heat-and-power) and the introduction of power-to-gas (to convert excess renewable electricity into hydrogen for successive energy generation) all lead to tighter interactions between the heat, gas and power sectors which require a multi-energy framework to assess. In this work this is achieved, firstly, through the development of integrated gas and power network modelling techniques. The power system modelling incorporates a multi-temporal DC optimal power flow, while gas network models use steady-state and transient flow analysis to allow for an assessment of the pressures and flows around the network. Additionally, a novel heat model is presented for a regional assessment of the heating demands of the British energy system, so that the impacts of changes to heating technologies on the gas and electrical transmission networks can be quantified in whole-energy system case studies. Power-to-gas technologies where (excess renewable) electrical energy is converted to hydrogen and then potentially synthetic natural gas which is then injected into the gas network where it can be stored and transported have the potential to increase the integration of renewable resources and reduce the carbon impact of both electricity and heating sectors. Models are presented which assess the operation of power-to-gas and its impact on the gas and electrical transmission networks as well as the benefits to the energy system. This uses power system modelling to assess the excess renewable energy (from wind and solar resources) that can be used in the power-to-gas process, with the amounts of produced hydrogen and synthetic natural gas also being evaluated considering constraints imposed by the gas network. The resulting case studies evaluate the impact on the gas and electrical networks and the benefit to the energy system by displacing natural gas and reducing carbon emissions. To assess the extent to which gas power stations can change their output to follow changes in renewable generation output, an integrated gas and electrical network flexibility model has been developed. This uses the notion of zonal linepack flexibility and allows for limits to be applied to the ability of gas turbines to change their output over the forthcoming hours with consideration of the intermittent nature of renewable generation. The developed models and methodologies are incorporated into a number of case studies using the British gas and electrical networks and heating sector showing their applicability to assessing future energy system needs.
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Bolen, Matthew Scott. "A new methodology for analyzing and predicting U.S. liquefied natural gas imports using neural networks." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2610.
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Liquefied Natural Gas (LNG) is becoming an increasing factor in the U.S. natural gas market. For 30 years LNG imports into the U.S. have remained fairly flat. There are currently 18 permit applications being filed in the U.S. and another 10 permit applications being filed in Canada and Mexico for LNG import terminals. The EIA (Energy Information Agency) estimates by 2025 that LNG will make up 21% of the total U.S. Natural Gas Supply.
This study developed a neural network approach to forecast LNG imports into the U.S. Various input variables were gathered, organized into groups based on similarity, and then a correlation matrix was generated to screen out redundant variables. Since a limited number of data points were available I used a restricted number of input variables. Based on this restriction, I grouped the input variables into four different scenarios and then generated a forecast for each scenario. These four different scenarios were the $/MMBTU model, natural gas energy consumption model, natural gas consumption model and the energy stack model.
The standard neural network approach was also used to screen the input variables. First, a correlation matrix determined which variables had a high correlation with the
output, U.S. LNG imports. The ten most correlated input variables were then put into correlation matrix to determine if there were any redundant variables. Due to the lack of data points only the five most highly correlated input variables were used in the neural network simulation.
A number of interesting results were obtained from this study. The energy stack model and the consumption of natural gas forecasted a non-linear trend in U.S. LNG imports, compared to the linear trend forecasted by the EIA. The energy stack model and consumption of natural gas model predicted that in 2025 U.S. LNG imports will be about 6.5 TCF, while the other three models prediction is about three times as less. The energy stack model is the most realistic model due its non-linear trend, when the rapid increase of LNG imports is going to occur, and the quantity of U.S. LNG imports predicted in 2025.
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Möller, Markus. "Mixed integer models for the optimisation of gas networks in the stationary case." [S.l. : s.n.], 2004. http://elib.tu-darmstadt.de/diss/000438.
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Thiedau, Jan [Verfasser]. "Dynamic Optimization of Gas Transmission Networks for Storage of Renewable Energy / Jan Thiedau." Hannover : Gottfried Wilhelm Leibniz Universität, 2018. http://d-nb.info/1158670478/34.
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Evans, G. P. "Single-walled carbon nanotube networks and related composite materials for gas sensing applications." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10046785/.
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In this thesis, the gas sensing properties of single-walled carbon nanotube (SWCNT) networks and SWCNT-Zeolite composite materials were investigated in a variety of environmental conditions. The aim of the project was to establish the effect that adsorbed water vapour had on the electrical properties of SWCNT networks, along with any subsequent impact on the NO2 sensing responses of SWCNT-based chemiresistors. Motivated by these investigations, the sensitivity of the SWCNT networks to water vapour was exploited to develop the water-assisted regeneration (WAR) method, enabling the improved recovery of the baseline sensing signal. Zeolites, known as molecular sieves due to their selective adsorption properties, were utilised in SWCNT-Zeolite composite sensing layers to reduce the cross-sensitivity of functionalised SWCNTs to water vapour. Functionalisation of the SWCNTs with a range of anionic, cationic and nonionic surfactants to aid solution processing was found to enhance the conductancehumidity effect, in some cases by a factor of 10. An interesting bi-directional switch in conductance change was observed when anionic (conductance decrease) vs cationic (conductance increase) were used. Under experimental conditions, fluctuations in atmospheric humidity levels were shown to alter the gas sensing characteristics of the SWCNT networks. Formed from interconnected metallic and semiconducting SWCNTs, the chemiresistive sensors demonstrated increased response magnitudes, adsorption rates and recovery rates at higher levels (A 50% RH) of relative humidity. Raman spectroscopy, UV-Vis-NIR spectroscopy, electron microscopy and electrical characterisation techniques were used in conjunction with gas sensing experiments to study changes in the properties of the sensing elements, helping to elucidate potential mechanisms. Extraction of key sensing parameters was facilitated by the application of a model for completely irreversible adsorption of NO2, whilst a model based on partially reversible desorption was found to best describe the sensing data.
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Cohen, Ruben Y. "Thermalization of a 1-dimensional Rydberg gas and entanglement distribution across quantum networks." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS281/document.
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Le comportement collectif des atomes de Rydberg est au cœur de nombreux protocoles d'information quantique, notamment de répéteurs quantiques. Cette thèse traite de deux sujets distincts: la dynamique collective de nuages d'atomes de Rydberg et l'utilisation de répéteurs quantiques dans des réseaux complexes. Dans la première partie, nous étudions un système simple composé d'une chaîne 1D d'atomes de Rydberg couplée à un laser résonnant sur la transition vers un niveau de Rydberg dans le régime contenant quelques excitations. Les atomes de Rydberg sont soumis à une forte interaction dipolaire qui tend à empêcher l'excitation simultanée de deux atomes proches l'un de l'autre. C'est ce phénomène de blocage de Rydberg qui fait des atomes de Rydberg d'éminents candidats pour des protocoles d'information quantique. Ce blocage induit une distribution spatiale particulière des excitations le long de la chaîne d'atomes. Le calcul exact de cette distribution est souvent impossible en pratique même numériquement, et des approximations sont a priori nécessaires:- l'approximation des sphères de Rydberg dures: l'interaction dipolaire est modélisée par une sphère centrée autour de chaque excitation, à l'intérieur de laquelle toute autre excitation est impossible;- l'hypothèse de thermalisation: le système est supposé thermaliser, c'est-à-dire qu'après suffisamment de temps, même sans effets dissipatifs, le système tendra vers un état quasi-thermique qui peut être décrit par la physique statistique et plus précisément l'ensemble microcanonique. Cette thèse présente une étude de la thermalisation d'un ensemble 1D d'atomes de Rydberg et, plus particulièrement, de l'acuité des prédictions de l'ensemble microcanonique en supposant l'hypothèse des sphères dures. Nous avons simulé numériquement la dynamique d'un tel système composé de 100 atomes, dans le régime contenant au plus deux excitations dans l'ensemble. De plus, un modèle analytique à 6 dimensions est présenté. Comparant les trois approches, nous montrons que le modèle analytique corrobore la simulation numérique, tandis que simulation et modèle mis ensemble contredisent les prédictions microcanoniques. Dans ce régime, l'utilisation de cet ensemble est donc inadaptée. La seconde partie de cette thèse porte sur la distribution d'intrication dans un réseau de répéteurs quantiques. Ces derniers devraient permettre la communication quantique de deux parties distantes. Ces répéteurs quantiques sont presque toujours connectés en un réseau linéaire. Dans cette thèse, nous explorons les possibilités offertes par des réseaux arbitraires constitués de ces répéteurs connectant une multitude de clients. Nous avons représenté ces réseaux à l'aide de graphes non orientés. Nous avons étudié deux scénarios de routage:- le routage classique d'intrication qui corresponds au cas où des clients, très limités par leurs dispositifs quantiques, souhaitent partager des paires intriqués. Sur ces réseaux, les problèmes de communication sont équivalents à des problèmes de chemins disjoints. Lorsque les clients souhaitant communiquer ensemble (les terminaux) sont choisis par un adversaire, nous avons obtenu deux bornes: l'une proportionnelle au genre topologique, et l'autre au degré minimal du graphe. Nous proposons deux architectures de réseau saturant la plus contraignante, celle due au degré minimal. D'autre part, lorsque les clients sont répartis dans un espace à 2-3 dimensions, nous avons montré une limitation géométrique sur la fraction de clients pouvant communiquer simultanément.- le routage quantique utilisant le codage de réseau, qui correspond au cas où le réseau quantique est composé de petits processeurs quantiques capable d'effectuer des opérations locales. Nous avons étudié un problème de communication, le réseau papillon, où le routage classique de l'intrication entre deux paires de clients est impossible. Grâce au codage de réseau, nous avons résolu ce problème de communicationThe collective behavior of Rydberg gases is at the heart of many proposals for quantum information. This thesis treats two distinct topics: the collective dynamic of a Rydberg ensemble and the use of quantum repeaters across quantum networks.In the first part of this thesis, we choose to focus on a simple system involving Rydberg atoms: a 1-dimensional Rydberg gas coupled to a laser resonant with the Rydberg transition. Rydberg atoms interact together through the dipole-dipole interaction. This particular feature is used for quantum information purposes, like applying multi-qubits gates for example. This interaction is strong enough so that the dynamic of such system in the regime of few excitations in the gas ensemble is already intractable without any assumptions. One of them is the hardcore Rydberg sphere assumption: we approximate this interaction by a sphere around each excitation inhibiting any second excitation within it. Another one is to suppose that the system thermalizes in such regime; a statistical treatment could then be applied. We have investigated the thermalization of a 1D-Rydberg gas and evaluated the accuracy of the microcanonical ensemble predictions under the first assumption. To do so, we have numerically simulated the dynamic of such system constituted by 100 atoms, in the regime of at most two excitations in the chain, in the initial excitation-less state. Furthermore, we constructed a 6-dimensional analytical model. Comparing the three approaches together, we have concluded that the numerical simulation and the analytical model both agree together but contradicts the microcanonical treatment. In this regime, the microcanonical ensemble is unadapted.In the second part of this thesis, we have studied the distribution of entanglement across a generic quantum network. We have mapped these quantum networks to undirected graphs and studied two different routing scenarios:- the classical routing of quantum entanglement corresponding to the scenario where clients of the network can perform only a single Bell measurement or keep a single qubit. This is the usual model of quantum repeaters. On these networks, peer-to-peer communication problems are equivalent to the vertex disjoint path problem. When the peers are chosen by an adversary, we have found two limitations due to the topological genus and the minimum degree of the graph. We have found two network architectures (almost) saturating the most constraining one, the minimum degree inequality. For the case where the peers are chosen at random, we have studied a specific graph lying in a 2- or 3-dimensional manifold and investigated the trade-off between the quantum links and the number of peers that can communicate simultaneously through the network.- true quantum routing problem (using network coding) corresponding to the situation where the quantum network is composed by small quantum processors that could apply local gates. We focus on a particular communication problem, namely the butterfly network, where classical routing is impossible. Using network coding, this communication is solved
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Kurdi, Jamal. "Molecular engineering and nanostructuring of polymer networks for high performance gas separation membranes." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/28990.
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The architecturing and characterization of polymer-based materials at a molecular scale are of great importance in the development of novel rigid polymeric molecular sieves for high performance gas separation membranes. The new rapidly growing field of nanoscience technologies and material nanostructuring offers novel ways for creating nanoengineered material combinations. Intermolecular and supramolecular interactions among different molecules and clusters play an important role in the microscopic behavior of molecular architectures and molecular self-assembly. In this work, the coordination shell number of polyetherimide (PEI) membranes was determined from experimental X-ray diffraction data and found to be a key link between microscopic pair intermolecular interactions and macroscopic scale interactions. This link enabled us to determine the intermolecular force parameters required to understand material structuring at a molecular scale. These physical parameters are required in all models used in the determination of the micropore size distributions from gas adsorption isotherms.
Computational chemistry and physicochemical principles were useful to illustrate molecular architecturing and coordinating to form intermediate stable molecular complexes during membrane fabrication. These coordination complexes acted as pore forming templates that could be disrupted and removed after polymer coagulation to open the closed PEI network structure and increase the interconnectivity and accessibility among polymer micropores. Based on nanotechnology concepts, a uniform dispersion of nanoscopically-sized filler particles into a polymer network created novel materials with superior properties and characteristics attributed to the presence of ultra-large interfacial area per unit volume. The adhesive (noncovalent interactions among different molecules) properties of nanoelement surfaces and polymer surfaces were the key for the creation of uniform polymeric molecular sieves. Narrowing the micropore size distribution is also possible when the adhesive energy between nanoparticles and polymer phase exceeds the cohesive energy of the pure polymer. Membranes were prepared using twelve metal-ligand complexes as filler additives that were uniformly dispersed into the PEI polymer solution before membrane casting. Membranes containing cobalt phthalocyanine (CoPc) showed the highest performance for oxygen separation from air. However, the performance was largely decreased upon annealing indicating a low nanostructure stability. (Abstract shortened by UMI.)
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Sulaiman, Nurul Sa'aadah. "Pipeline Integrity Management System (PIMS) using Bayesian networks for lifetime extension." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=232617.
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The majority of the world's offshore infrastructures are now showing the sign of aging and are approaching the end of their original design life. Their ability to withstand various operational and environmental changes have been the main concerns over the years. This is because the pipeline will still need to operate for a few more decades with increasing demand of oil and gas supply. To address the issues, an effective pipeline integrity management system is required to manage pipeline systems and to ensure the reliability and availability of the pipeline. The main goal is to identify, apply, and assess the applicability of the Bayesian network approach in evaluating the integrity of subsea pipelines that evolves with time. The study is aimed to specifically handle knowledge uncertainties and assist in the decision making of subsea pipeline integrity assessment. A static Bayesian network model was developed to compute the probability of pipeline condition and investigate the underlying factors that lead to pipeline damage. From the model, the most influential factors were identified and the sensitivity analysis demonstrated that the developed model was robust and accurate. The proposed model was then extended to develop a decision tool model using an Influence Diagram. The results from the proposed influence diagram were used to prioritize the maintenance scheme of the pipeline segments. Benefit to cost ratio was applied to determine the pipeline maintenance intervals. Dynamic Bayesian network was utilized to model timedependent deterioration of pipeline structural reliability. A good agreement with conventional structural reliability method is achieved. The present thesis has demonstrated the applicability and effectiveness of Bayesian network approach in the field of oil and gas. It is hoped that the proposed models can be applied by oil and gas pipeline practitioners to enhance the integrity and lifeltime of the oil and gas pipeline.
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Vieira, Cristiano Ribeiro. "Forecasting financial markets with artificial neural networks." Master's thesis, Instituto Superior de Economia e Gestão, 2013. http://hdl.handle.net/10400.5/6340.
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Mestrado em Matemática FinanceiraArtificial Neural Networks are exible nonlinear mathematical models widely used in forecasting. This work is intended to investigate the support these models can give to nancial economists predicting prices movements of oil and gas companies listed in stock exchanges. Multilayer Perceptron models with logistic activation functions achieved better results predicting the direction of stocks returns than traditional linear regressions and better performances in companies with lower market capitalization. Furthermore, multilayer perceptron with eight hidden units in the hidden layer had better predictive ability than a neural network with four hidden neurons.
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Willert, Bernhard Michael [Verfasser]. "Validation of nominations in gas networks and properties of technical capacities / Bernhard Michael Willert." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2014. http://d-nb.info/1063972825/34.
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Bourassa, M. A. J. "Autoassociative neural networks with an application to fault diagnosis of a gas turbine engine." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0004/MQ44834.pdf.
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Yiasoumis, Demetris. "Real Options in the Energy Sector: The Case of Oil/Natural Gas Pipeline Networks." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486549.
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This thesis is concerned with the application of the real options methodology to value oiVnatural gas pipeline networks. A simple real option model for the valuation of an oil storage facility is presented initially to demonstrate the concept of physical energy asset valuation with respect to market price movements. The investment strategy underpinning:1he model relies on forward dynamic optimisation. We consider a single-period optimisation problem of an oiVnatural gas pipeline network. In this problem, the network is represented by a graph with vertices and arcs denoting various markets and pipelines, respectively. Each market has delivery and supply constraints and there are also pipeline capacity constraints. The objective is to maximise profit subject to satisfying all constraints by flowing oiVgas through the network. Two formulations, one path-based and the other arc-based, transforming the problem into a linear programming problem are described. The performance of the algorithm d~veloped for each formulation is evaluated. A real option model for an oil/natural gas pipeline network is presented. The model uses the arc formulation and Monte Carlo simulation. Its algorithmic implementation is tested. We extend the single-period optimisation problem by introducing multiple time periods and an oil/gas storage facility. An arc-based formulation leading to a -new linear programming problem is presented. We test the implementation algorithm constructed. A description of how to use the arc-based formulation and Monte Carlo simulation to develop a real option model for an oiVnatural gas pipeline network with storage is also provided. A real option model for an oil/natural gas pipeline network with storage is developed. The model is a stochastic dynamic programming approach and takes into account optionality that may be exercised throughout the lifetime of the network. The constructed algorithm's performance is investigated.
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Tehranian, Azadeh. "Effects of artificial neural networks characterization on prediction of diesel engine emissions." Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=2956.
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Thesis (M.S.)--West Virginia University, 2003.Title from document title page. Document formatted into pages; contains xxii, 198 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 110-116).
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Plein, Fränk. "When Bilevel Optimization Meets Gas Networks: Feasibility of Bookings in the European Entry-Exit Gas Market: Computational Complexity Results and Bilevel Optimization Approaches." Doctoral thesis, Universite Libre de Bruxelles, 2021. https://dipot.ulb.ac.be/dspace/bitstream/2013/325604/3/TOC.pdf.
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Transport and trade of gas are decoupled after the liberalization of the European gas markets, which are now organized as so-called entry-exit systems. At the core of this market system are bookings and nominations, two special capacity-right contracts that grant traders access to the gas network. The latter is operated by a separate entity, known as the transmission system operator (TSO), who is in charge of the transport of gas from entry to exit nodes. In the mid to long term, traders sign a booking contract with the TSO to obtain injection and withdrawal capacities at entry and exit nodes, respectively. On a day-ahead basis, they then nominate within these booked capacities a balanced load flow of the planned amounts of gas to be injected into and withdrawn from the network the next day. The key property is that by signing a booking contract, the TSO is obliged to guarantee transportability for all balanced load flows in compliance with the booked capacities. To assess the feasibility of a booking, it is therefore necessary to check the feasibility of infinitely many nominations. As a result, deciding if a booking is feasible is a challenging mathematical problem, which we investigate in this dissertation.Our results range from passive networks, consisting of pipes only, to active networks, containing controllable elements to influence gas flows. Since the study of the latter naturally leads to a bilevel framework, we first consider some more general properties of bilevel optimization. For the case of linear bilevel optimization, we consider the hardness of validating the correctness of big-Ms often used in solving these problems via a single-level reformulation. We also derive a family of valid inequalities to be used in a bilevel-tailored branch-and-cut algorithm as a big-M-free alternative.We then turn to the study of feasible bookings. First, we present our results on passive networks, for which bilevel approaches are not required. A characterization of feasible bookings on passive networks is derived in terms of a finite set of nominations. While computing these nominations is a difficult task in general, we present polynomial complexity results for the special cases of tree-shaped or single-cycle passive networks. Finally, we consider networks with linearly modeled active elements. After obtaining a bilevel optimization model that allows us to determine the feasibility of a booking in this case, we derive various single-level reformulations to solve the problem. In addition, we obtain novel characterizations of feasible bookings on active networks, which generalize our characterization in the passive case. The performance of these various approaches is compared in a case study on two networks from the literature, one of which is a simplified version of the Greek gas network.Transport et commerce de gaz sont découplés depuis la libéralisation des marchés européens du gaz, qui sont désormais organisés en systèmes dit d'entrée-sortie. Au cœur de ce système de marché se trouvent les réservations et les nominations, deux contrats spéciaux de droit à la capacité qui permettent aux négociants d'accéder au réseau de gaz. Ce dernier est exploité par une entité distincte, appelée gestionnaire de réseau de transport~(GRT), qui est chargée du transport du gaz entre les nœuds d'entrée et de sortie. À moyen et long terme, les négociants signent un contrat de réservation avec le GRT pour obtenir des capacités d'injection et d'extraction aux nœuds d'entrée et de sortie, respectivement. Au jour le jour, ils désignent ensuite, dans les limites des capacités réservées, un flux de charge équilibrée des quantités de gaz prévues à injecter et à extraire le lendemain. La propriété essentielle est qu'en signant un contrat de réservation, le GRT est obligé de garantir la transportabilité de tous les flux de charge équilibrée respectant les capacités réservées. Pour évaluer la faisabilité d'une réservation, il est donc nécessaire de vérifier la faisabilité d'une infinité de nominations. Par conséquent, décider si une réservation est réalisable est un problème mathématique difficile, que nous étudions dans cette thèse.Nos résultats vont des réseaux passifs, constitués uniquement de pipelines, aux réseaux actifs, contenant des éléments contrôlables pour influencer les flux de gaz. Comme l'étude de ces derniers conduit naturellement à un cadre biniveau, nous considérons d'abord certaines propriétés plus générales de l'optimisation biniveau. Pour le cas de l'optimisation biniveau linéaire, nous étudions la difficulté de valider l'exactitude des constantes de type big-M souvent utilisées dans la résolution de ces problèmes via une reformulation à un seul niveau. Nous déduisons également une famille d'inégalités valides à utiliser dans un algorithme de branch-and-cut adapté au biniveau comme alternative à l'approche utilisant des big-Ms.Nous nous tournons ensuite vers l'étude des réservations réalisables. D'abord, nous présentons nos résultats sur les réseaux passifs, pour lesquels les approches biniveaux ne sont pas nécessaires. Une caractérisation des réservations réalisables sur les réseaux passifs est déduite en termes d'un ensemble fini de nominations. Bien que le calcul de ces nominations soit une tâche difficile en général, nous présentons des algorithmes polynomiaux pour les cas particuliers des réseaux passifs en forme d'arbre ou contenant un cycle unique. Enfin, nous considérons les réseaux avec des éléments actifs modélisés à l'aide de contraintes linéaires. Après avoir obtenu un modèle biniveau, permettant de déterminer la faisabilité d'une réservation dans ce cas, nous dérivons diverses reformulations à un seul niveau pour résoudre le problème. En outre, nous obtenons de nouvelles caractérisations des réservations réalisables sur les réseaux actifs, qui généralisent notre caractérisation dans le cas passif. La performance de ces différentes approches est comparée dans une étude de cas réalisée sur deux réseaux de la littérature, dont l'un est une version simplifiée du réseau de gaz grec.
Nach der Liberalisierung der europäischen Gasmärkte, welche nun als sogenannte Entry-Exit Systeme organisiert sind, sind Transport und Handel von Gas entkoppelt. Im Zentrum dieses neuen Marktsystems sind Buchungen und Nominierungen, zwei spezielle Kapazitätrechtsverträge, die Händlern Zugang zum Gasnetz gewähren. Letzteres wird von einem separaten Akteur betrieben, dem sogenannten Fernleitungsnetzbetreiber (FNB), der für den Transport des Gases von den Einspeise- zu den Ausspeiseknoten verantwortlich ist. Händler schließen mittel- bis langfristig einen Buchungsvertrag mit dem FNB ab, um Ein- und Ausspeisekapazitäten zu erhalten. Täglich nominieren sie dann innerhalb der gebuchten Kapazitäten einen bilanzierten Lastfluss der geplanten Gasmengen, die am nächsten Tag eingespeist und entnommen werden sollen. Die Haupteigenschaft ist, dass der FNB sich durch Unterzeichnung eines Buchungsvertrages für die Transportierbarkeit aller bilanzierten Lastflüsse innerhalb der gebuchten Kapazitäten verpflichtet. Um die Zulässigkeit einer Buchung zu bestimmen ist es daher notwendig, die Zulässigkeit von unendlich vielen Nominierungen zu prüfen. Die Entscheidung, ob eine Buchung zulässig ist, ist daher ein anspruchsvolles mathematisches Problem, das wir in dieser Dissertation untersuchen.Unsere Ergebnisse reichen von passiven Netzen, die nur aus Rohren bestehen, bis hin zu aktiven Netzen, die steuerbare Elemente zur Beeinflussung der Gasflüsse enthalten. Da die Untersuchung aktiver Netze uns auf natürlichem Wege zu Bilevel-Problemen führt, betrachten wir zunächst einige allgemeinere Eigenschaften der Bilevel-Optimierung. Für den Fall der linearen Bilevel-Optimierung betrachten wir die Schwierigkeit, Big-Ms zu validieren, die oft bei der Lösung dieser Probleme mittels einer einstufigen Reformulierung verwendet werden. Wir leiten außerdem eine Familie gültiger Ungleichungen ab, die in einem Bilevel-spezifischen Branch-and-Cut Algorithmus als big-M-freie Alternative verwendet werden können.Wir wenden uns dann der Untersuchung von zulässigen Buchungen zu. Zunächst stellen wir unsere Ergebnisse zu passiven Netzwerken vor, für die Bilevel-Ansätze nicht erforderlich sind. Eine Charakterisierung zulässiger Buchungen in passiven Netzwerken wird in Bezug auf eine endliche Menge an Nominierungen hergeleitet. Während die Berechnung dieser Nominierungen im Allgemeinen eine schwierige Aufgabe ist, präsentieren wir polynomielle Komplexitätsergebnisse für die Spezialfälle baumförmiger oder einzyklischer passiver Netze. Schließlich betrachten wir Netze mit linear modellierten aktiven Elementen. Nachdem wir ein Bilevel-Modell hergeleitet haben, mit dem wir die Zulässigkeit einer Buchung in diesem Fall bestimmen können, leiten wir verschiedene einstufige Reformulierungen zur Lösung des Problems ab. Darüber hinaus erhalten wir neuartige Charakterisierungen zulässiger Buchungen auf aktiven Netzen, die unsere Charakterisierung im passiven Fall verallgemeinern. Die Anwendbarkeit dieser verschiedenen Ansätze wird in einer Fallstudie an zwei Netzen aus der Literatur verglichen, wovon eines eine vereinfachte Version des griechischen Gasnetzes ist.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Holle, Yannick Verfasser], Michael [Akademischer Betreuer] [Herty, Michael [Akademischer Betreuer] Westdickenberg, and Benedetto [Akademischer Betreuer] Piccoli. "Entropy methods for gas dynamics on networks / Yannick Holle ; Michael Herty, Michael Westdickenberg, Benedetto Piccoli." Aachen : Universitätsbibliothek der RWTH Aachen, 2020. http://d-nb.info/1227447418/34.
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葉慶輝 and Hing-fai Devil Yip. "Applications of neural networks for industrial and office automation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31243873.
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Yip, Hing-fai Devil. "Applications of neural networks for industrial and office automation /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23555981.
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Bennett, Colin. "Reconstruction of gasoline engine in-cylinder pressures using recurrent neural networks." Thesis, University of Sussex, 2014. http://sro.sussex.ac.uk/id/eprint/48644/.
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Knowledge of the pressure inside the combustion chamber of a gasoline engine would provide very useful information regarding the quality and consistency of combustion and allow significant improvements in its control, leading to improved efficiency and refinement. While measurement using incylinder pressure transducers is common in laboratory tests, their use in production engines is very limited due to cost and durability constraints. This thesis seeks to exploit the time series prediction capabilities of recurrent neural networks in order to build an inverse model accepting crankshaft kinematics or cylinder block vibrations as inputs for the reconstruction of in-cylinder pressures. Success in this endeavour would provide information to drive a real time combustion control strategy using only sensors already commonly installed on production engines. A reference data set was acquired from a prototype Ford in-line 3 cylinder direct injected, spark ignited gasoline engine of 1.125 litre swept volume. Data acquired concentrated on low speed (1000-2000 rev/min), low load (10-30 Nm brake torque) test conditions. The experimental work undertaken is described in detail, along with the signal processing requirements to treat the data prior to presentation to a neural network. The primary problem then addressed is the reliable, efficient training of a recurrent neural network to result in an inverse model capable of predicting cylinder pressures from data not seen during the training phase, this unseen data includes examples from speed and load ranges other than those in the training case. The specific recurrent network architecture investigated is the non-linear autoregressive with exogenous inputs (NARX) structure. Teacher forced training is investigated using the reference engine data set before a state of the art recurrent training method (Robust Adaptive Gradient Descent – RAGD) is implemented and the influence of the various parameters surrounding input vectors, network structure and training algorithm are investigated. Optimum parameters for data, structure and training algorithm are identified.
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Yacoub, Yasser M. "Mean value modeling and control of a diesel engine using neural networks." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=473.
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Thesis (Ph. D.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains xv, 174 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 168-172).
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Wintergerst, David [Verfasser], Martin [Akademischer Betreuer] Gugat, and Martin [Gutachter] Gugat. "Optimization on Gas Networks under Stochastic Boundary Conditions / David Wintergerst ; Gutachter: Martin Gugat ; Betreuer: Martin Gugat." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1180724003/34.
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AL-Rashidi, Abdulrahman F. "Designing neural networks for the prediction of the drilling parameters for Kuwait oil and gas fields." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=1209.
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Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains x, 76 p. : ill. (some col.), map (some col.). Includes abstract. Includes bibliographical references (p. 54-55).
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Dawood, Bann. "Mixed matrix membranes consisting of porous polyimide networks and polymers of intrinsic microporosity for gas separation." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/mixed-matrix-membranes-consisting-of-porous-polyimide-networks-and-polymers-of-intrinsic-microporosity-for-gas-separation(bb07d633-69dc-471b-a5ae-f1f0888615b6).html.
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This research aimed to develop the fabrication of mixed matrix membranes (MMMs) utilizing a polymer of intrinsic microporosity (PIM-1) with porous polyimide networks, and to explore their effect on gas transport properties. PIM-1 has been chosen as polymer matrix for its high surface area and high sorption of gases. It is also considered as interesting candidate for membrane gas separation. PIM-1 has been synthesized successfully using high temperature methods (40 min, 160 oC) and low temperature methods (72 h, 65 oC). Porous polyimide networks have been chosen as organic fillers as they have good chemical affinity to polymer matrix and can adhere much better than inorganic fillers. MPN-1 and MPN-2 were synthesized by condensation polymerization of A2 (dianhydride) and B4 (tetraamino). The polymer matrix (PIM-1) and network polyimide fillers were characterized using various characterization techniques, including FTIR, NMR spectroscopy, TGA and N2 sorption analysis. MMMs were fabricated successfully utilizing PIM-1 with 10, 20, and 30wt. % loadings of fillers. The MMMs prepared were homogenous on a macroscale. They characterized using different techniques, such as FTIR spectroscopy, powder x-ray diffraction, and scanning electron microscopy. The gas transport properties of MMMs were obtained using a time lag method. The treatment of MMMs with alcohol showed an increase in the permeability and diffusivity of gases. We aimed in this research to increase solubility of microporous polyimide network (MPN-1) by decreasing the extent of network structure. Different strategies have been utilized. First, using different molar ratios and second, using end-capping modification. The polymers were characterized using various techniques, including FTIR, NMR spectroscopy and TGA. Following this, their CO2 uptake and solubility are also examined.
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Xie, Tao. "Hydrodynamic characteristics of gas/liquid/fiber three-phase flows based on objective and minimally-intrusive pressure fluctuation measurements." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-09192004-033703/unrestricted/xie%5Ftao%5F200412%5Fphd.pdf.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2005.D. William Tedder, Committee Member ; Minami Yoda, Committee Member ; Tom McDonough, Committee Member ; Andrei G. Fedorov, Committee Member ; S. Mostafa Ghiaasiaan, Committee Chair ; Seppo Karrila, Committee Member. Includes bibliographical references.
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Huls, Boyd T. "A feasibility study on modeling and prediction of production behavior in naturally fractured shale reservoirs." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3726.
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Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains viii, 105 p. : ill. (some col.), map. Includes abstract. Includes bibliographical references (p. 96-97).
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Perrotton, Florian. "The economics and regulation of natural gas pipeline networks : four essays on the impact of demand uncertainty." Thesis, Paris 10, 2017. http://www.theses.fr/2017PA100129.
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Cette thèse vise à développer les opportunités et conséquences d’une demande incertaine pour le réseau de transport de gaz. Ce sujet est décliné en quatre contributions. Les deux premières adoptent une perspective de long terme : on cherche à évaluer l’efficacité de la réglementation du taux rendement lorsqu’il s’agit d’inciter à la réalisation de projets d’infrastructures gazières dans des pays en développement. Une première contribution analytique présente le développement d’une représentation simplifiée du réseau de transport de gaz, de forme Cobb-Douglas. Inspiré par les projets d’acheminement de gaz naturel au Mozambique, celle-ci est ensuite utilisée pour évaluer dans quelles conditions il est possible pour une autorité de régulation de choisir un taux de rendement régulé qui améliore l’efficacité du système dans le cas où la demande réelle serait plus importante que la demande anticipée par la firme régulée. A moyen terme ensuite, l’efficacité face à une demande de plus en plus variable de la structure tarifaire actuelle dite « entrée-sortie » pour l’accès au réseau européen est évaluée. Après avoir démontré l’existence d’inefficacités dans un tel système, celles-ci sont évaluées numériquement. Enfin, la dernière contribution explore la possibilité d’offrir directement la flexibilité du réseau de transport de gaz à ses utilisateurs, dans le cadre d’enchères et du système de prix nodaux. Après avoir souligné la complexité d’un tel mécanisme, les limites à son efficacité sont présentées. A chaque fois, l’analyse repose sur la modélisation simultanée du réseau de transport de gaz (en régime statique ou transitoire) et des mécanismes économiques en jeuThis PhD thesis is centered on the opportunities and impact of demand uncertainty for the gas transport networks. We study the ability of various market designs to foster an efficient network allocation in liberalized gas markets when demand is variable or uncertain. We introduce and solve operation research models that bind an economic representation of the gas market and its associated regulation, to a technical representation of the gas network. The complex interactions at stake in liberalized gas markets, where shippers trade gas for its economic value and coordinate with system operators that allocate and operate the network, result in MCP or MPEC formulations. While a detailed network representation is necessary to assess the feasibility of gas flows under any market organization, the physics and engineering of gas transport networks adds non-linearities and non-convexities to those already challenging formulations. This thesis is divided in four contributions. We first introduce an approximated network representation of the Cobb-Douglas form and use it to study the impact of long-term demand uncertainty on investment problems in developing markets subject to rate-of-return regulation. We then study the effect of demand variability on daily gas dispatch in the European Entry-Exit system, using a linearized steady-state network representation. Finally, we assess the benefits of introducing flexibility products in gas locational marginal pricing auctions to handle intraday demand uncertainty. This requires the use of a linearized transient network formulation to account for linepack dynamics
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Aguilera, Miguel. "Semantic and Physical Modeling and Simulation of Multi-Domain Energy Systems: Gas Turbines and Electrical Power Networks." Thesis, KTH, Elkraftteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214532.
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The ITEA3 OpenCPS (Open Cyber-Physical System Model-Driven CertifiedDevelopment) project focuses on interoperability between the Modelica/UnifiedModeling Language (UML)/Functional Mock-up Interface (FMI) standards, improved(co-)simulation execution speed, and verified code generation. The project aims to developa modeling and simulation framework for cyber-physical and multi-domain systems. Oneof the main use cases for the framework, is the multi-domain equation-based modelingand simulation of detailed gas turbine power plants (including the explicit equation-basedmodeling of turbomachinery dynamics) and the electrical power grid.In this work, UML class diagrams based on the Common Information Model (CIM)standard are used to describe the semantics of the electrical power grid. An extension basedon the standard ISO 15926 has been proposed to derive the multi-domain semanticsrequired by the models that integrate the electrical power grid with the detailed gas turbinedynamics.Furthermore, the multi-domain physical modeling and simulation Modelica language hasbeen employed to create the equation-based models of the use case of this project. Acomparative analysis between the Single-Domain and Multi-Domain model responses hasbeen performed both in time and frequency. The results show some interesting differencesbetween the turbine dynamics representation of the commonly used GGOV1 standardmodel and the less simplified model of a gas turbine.Finally, the models from each domain can be exchanged between two differentstakeholders by means of Functional Mock-Up Units (FMUs), defined by the FMIstandard. Promising test results were obtained with different simulation tools that supportthe standard, which demonstrates the feasibility of exchanging unambiguous multi-domainmodels with a detailed gas turbine representation. This shows the potential of the FMIstandard for manufacturers to exchange equation-based multi-domain models, while at thesame time protecting their intellectual property.Projektet ITEA3 OpenCPS (Öppen, certifierad modelldriven utveckling för cyberfysiskasystem) fokuserar på interoperabilitet mellan standarderna för Modelica, Unified ModelingLanguage (UML) och Functional Mock-up Interface (FMI), förbättring av tidsåtgångenför (sam-)simulering, samt verifierad kodgenerering. Projektet syftar till att utveckla enplattform för modellering och simulering av cyberfysiska system och system somrepresenteras av olika sorters fysikaliska modeller (eng. multi-domain modeling). Ett av defrämsta användningsområdena för plattformen är ekvationsbaserad modellering ochsimulering av detaljerade gasturbinmodeller i elkraftverk (inklusive explicitekvationsbaserad modellering av dynamiken mellan termiska och roterande komponenter)som är sammankopplade med kraftsystemet.I detta examenarbete används klassdiagram i UML baserade på standarden för CommonInformation Model (CIM) och komponentdiagram från SysML för att beskrivakraftsystemet. En utvidgning baserat på ISO 15926-standarden föreslås för att härledasemantiken för modeller som integrerar både kraftsystemet och detaljerad dynamik förgasturbiner.Vidare så har Modelica, ett språk för modellering och simulering av olikartade fysikaliskasystem, utnyttjats för att skapa ekvationsbaserade modeller som utvecklats i detta projekt.En komparativ analys har genomförts för en detaljerad modell med termodynamik och enförenklad modell genom undersökning av både frekvenssvar och tidssimuleringar.Resultaten visar att skillnader uppstår mellan den detaljerade modellen och den ikraftsystemsammanhang allmänt använda modellen GGOV1, vilket kan förklaras medförenklingar i den snareSlutligen kan modeller från olika fysikaliska domäner utbytas mellan intressenter med s.k.Functional Mock-Up Units (FMU-enheter), som definieras av FMI-standarden. Lovanderesultat uppnåddes med simuleringsverktyg som stöder FMI-standarden vilket visarmöjligheten till ett otvetydigt utbyte av detaljerade gasturbinmodeller och elkraftsmodeller.Detta visar potentialen i FMI-standarden för modellutbyte mellan olikamodelleringsdomäner, vilket skulle kunna låta tillverkare att dela ekvationsbaserademodeller utan att ge upp immateriella tillgångar.
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Trimby, Stuart. "Engine cylinder pressure reconstruction using crank kinematics, block vibrations, and time-delay neural networks." Thesis, University of Sussex, 2016. http://sro.sussex.ac.uk/id/eprint/61201/.
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Time-delay feed-forward Artificial Neural Networks are examined for gasoline engine cylinder pressure reconstruction using both measured crank kinematics obtained from a shaft encoder, and measured engine cylinder block vibrations obtained from a production knock sensor. Initially, the study focuses on the information content associated with measured data, which is considered to be of equal importance to the particular network architecture and the training methodology. Several hypotheses are constructed, which when tested, reveal the influence of the data information content on the reconstruction potential and limitations. These hypotheses are tested on real data from a 3-cylinder (DISI) engine. Three distinct ideas emerge through this testing process, which are combined to produce a single pressure reconstruction methodology. Reconstruction results obtained via this methodology, applied to crank kinematics associated with steady-state engine operation, show a marked improvement over previously published reconstruction accuracy. Moreover, in steady-state engine operation, the application of this methodology to acceleration measurements of cylinder block vibration, obtained from a knock sensor, show very significant improvements over previous attempts. But the direct application of this same reconstruction methodology to transient engine operation, proves to be problematic. However, a novel generalisation of the approach in the form of a time-dependent feed-forward neural network is proposed and the required adaptation made to the use of the Levenberg-Marquardt training algorithm. This time-dependent approach has been tested under limited transient conditions and shown in the thesis to give good results, therefore offering considerable potential for use with real engine operation. Overall, the thesis shows that by careful processing of measured engine data, standard neural network architectures and standard training algorithms can be used to reconstruct engine cylinder pressure.
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Dick, Markus [Verfasser], and Martin [Akademischer Betreuer] Gugat. "Stabilization of the Gas Flow in Networks: Boundary Feedback Stabilization of Quasilinear Hyperbolic Systems on Networks = Stabilisierung des Gasflusses in Netzwerken / Markus Dick. Betreuer: Martin Gugat." Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2012. http://d-nb.info/1025182626/34.
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Jalali, Jalal. "Artificial neural networks for reservoir level detection of CO₂ seepage location using permanent down-hole pressure data." Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/11137.
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Thesis (Ph. D.)--West Virginia University, 2010.Title from document title page. Document formatted into pages; contains xii, 140 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 99-104).
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Lu, Yi [Verfasser], and Nicole [Gutachter] Marheineke. "Gramian Projection-based Interpolation Strategy for Parametric Model Order Reduction of Gas Pipeline-Networks / Yi Lu ; Gutachter: Nicole Marheineke." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2017. http://d-nb.info/1138115738/34.
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