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- Title
- Smart Grid Demonstration: Distributed Active and Reactive Power Control.
- Creator
-
Vellakovil Rajamani, Siddarth, Qu, Zhihua, Simaan, Marwan, Sun, Wei, University of Central Florida
- Abstract / Description
-
The present infrastructure of energy delivery was designed over 60 years ago with the goal to be centralized. However, it is aging and is under-utilized, which will potentially limit the world's ability to achieve its energy objective. The lack of vibrant control on the grid makes it difficult to stop cascading power failure, and to achieve high penetration of renewable energy resources, such as wind and solar thus resulting in grid instability. A decentralized and distributed control...
Show moreThe present infrastructure of energy delivery was designed over 60 years ago with the goal to be centralized. However, it is aging and is under-utilized, which will potentially limit the world's ability to achieve its energy objective. The lack of vibrant control on the grid makes it difficult to stop cascading power failure, and to achieve high penetration of renewable energy resources, such as wind and solar thus resulting in grid instability. A decentralized and distributed control mechanism implemented with a definite communication protocol solves the issues mentioned above. The electric power grid going into the future is expected to consists of distributed generators and loads. The implementation of a distributed control will benefit utility services and will create financial advantages. One of the best solutions is to organize these distributed generators (DG) in a micro-grid structure which will then connect to the main grid through the point of common coupling (PCC). A proper organization and control of the Microgrid is always a big challenge. To overcome this, using cooperative control makes it possible to bring together different agents in the networked systems as a group and realize the desired objective. The micro grid power objective is set by a virtual leader and is transferred to the other agents in the system through a local communication channel. A distributed cooperative control is formulated to effectively organize all the DGs in the Microgrid to produce the necessary active and reactive power to satisfy multiple objectives. It not only satisfies the active power flow from the main grid to a constant but also reduces the reactive power flow to the main grid. Moreover, the algorithm can be used to implement the demand response continuously using a combination of DGs and their local controllable loads. The approach is to use distributed inverters with the aid of multiple local communication channels for active power compensation of the micro-grid in real-time in a distributed and cooperative manner.
Show less - Date Issued
- 2016
- Identifier
- CFE0006513, ucf:51362
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006513
- Title
- SOLAR-BASED SINGLE-STAGE HIGH-EFFICIENCY GRID-CONNECTED INVERTER.
- Creator
-
Tian, Feng, BATARSEH, ISSA, University of Central Florida
- Abstract / Description
-
Renewable energy source plays an important role in the energy cogeneration and distribution. Traditional solar-based inverter system is two stages in cascaded, which has a simpler controller but low efficiency. A new solar-based single-stage grid-connected inverter system can achieve higher efficiency by reducing the power semiconductor switching loss and output stable and synchronized sinusoid current into the utility grid. Controlled by the digital signal processor, the inverter can also...
Show moreRenewable energy source plays an important role in the energy cogeneration and distribution. Traditional solar-based inverter system is two stages in cascaded, which has a simpler controller but low efficiency. A new solar-based single-stage grid-connected inverter system can achieve higher efficiency by reducing the power semiconductor switching loss and output stable and synchronized sinusoid current into the utility grid. Controlled by the digital signal processor, the inverter can also draw maximum power from the solar array, thereby maximizing the utilization of the solar array. In Chapter 1, a comparison between the traditional two-stage inverter and the single-stage inverter is made. To increase the ability of power processing and enhance the efficiency further, a full-bridge topology is chosen, which applies the phase-shift technique to achieve zero-voltage transition. In Chapter 2, average-mode and switch-mode Pspice simulations are applied. All the features of the inverter system are verified, such as stability, zero voltage transition and feed-forward compensation, etc. All these simulation results provide useful design tips for prototyping. In Chapter 3, a phase-shift controller is designed based on UCC3895. Also, a detailed design procedure is given, including key components selection, transformer and inductor design and driver circuits design. In Chapter 4, experimental results of a prototype DC/DC converter are presented and analyzed. By optimization of the circuit, the problems of the prototype are solved and the prototype is working stably. The thesis' conclusion is given in Chapter 5.
Show less - Date Issued
- 2005
- Identifier
- CFE0000468, ucf:46414
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000468
- Title
- A Comprehensive Assessment of Vehicle-to-Grid Systems and Their Impact to the Sustainability of Current Energy and Water Nexus.
- Creator
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Zhao, Yang, Tatari, Omer, Oloufa, Amr, Mayo, Talea, Zheng, Qipeng, University of Central Florida
- Abstract / Description
-
This dissertation aims to explore the feasibility of incorporating electric vehicles into the electric power grid and develop a comprehensive assessment framework to predict and evaluate the life cycle environmental, economic and social impact of the integration of Vehicle-to-Grid systems and the transportation-water-energy nexus. Based on the fact that electric vehicles of different classes have been widely adopted by both fleet operators and individual car owners, the following questions...
Show moreThis dissertation aims to explore the feasibility of incorporating electric vehicles into the electric power grid and develop a comprehensive assessment framework to predict and evaluate the life cycle environmental, economic and social impact of the integration of Vehicle-to-Grid systems and the transportation-water-energy nexus. Based on the fact that electric vehicles of different classes have been widely adopted by both fleet operators and individual car owners, the following questions are investigated: 1. Will the life cycle environmental impacts due to vehicle operation be reduced? 2. Will the implementation of Vehicle-to-Grid systems bring environmental and economic benefits? 3. Will there be any form of air emission impact if large amounts of electric vehicles are adopted in a short time? 4. What is the role of the Vehicle-to-Grid system in the transportation-water-energy nexus? To answer these questions: First, the life cycle environmental impacts of medium-duty trucks in commercial delivery fleets are analyzed. Second, the operation mechanism of Vehicle-to-Grid technologies in association with charging and discharging of electric vehicles is researched. Third, the feasible Vehicle-to-Grid system is further studied taking into consideration the spatial and temporal variance as well as other uncertainties within the system. Then, a comparison of greenhouse gas emission mitigation of the Vehicle-to-Grid system and the additional emissions caused by electric vehicle charging through marginal electricity is analyzed. Finally, the impact of the Vehicle-to-Grid system in the transportation-water-energy nexus, and the underlying environmental, economic and social relationships are simulated through system dynamic modeling. The results provide holistic evaluations and spatial and temporal projections of electric vehicles, Vehicle-to-Grid systems, wind power integration, and the transportation-water-energy nexus.
Show less - Date Issued
- 2017
- Identifier
- CFE0007300, ucf:52153
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007300
- Title
- A Study of Perceptions on Incident Response Exercises, Information Sharing, Situational Awareness, and Incident Response Planning in Power Grid Utilities.
- Creator
-
Garmon, Joseph, Karwowski, Waldemar, Hancock, Peter, Elshennawy, Ahmad, Wan, Thomas, University of Central Florida
- Abstract / Description
-
The power grid is facing increasing risks from a cybersecurity attack. Attacks that shut off electricity in Ukraine have already occurred, and successful compromises of the power grid that did not shut off electricity to customers have been privately disclosed in North America. The objective of this study is to identify how perceptions of various factors emphasized in the electric sector affect incident response planning. Methods used include a survey of 229 power grid personnel and the use...
Show moreThe power grid is facing increasing risks from a cybersecurity attack. Attacks that shut off electricity in Ukraine have already occurred, and successful compromises of the power grid that did not shut off electricity to customers have been privately disclosed in North America. The objective of this study is to identify how perceptions of various factors emphasized in the electric sector affect incident response planning. Methods used include a survey of 229 power grid personnel and the use of partial least squares structural equation modeling to identify causal relationships. This study reveals the relationships between perceptions by personnel responsible for cybersecurity, regarding incident response exercises, information sharing, and situational awareness, and incident response planning. The results confirm that the efforts by the industry on these topics have advanced planning for a potential attack.
Show less - Date Issued
- 2019
- Identifier
- CFE0007805, ucf:52349
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007805
- Title
- cooperative control and advanced management of distributed generators in a smart grid.
- Creator
-
Maknouninejad, Ali, Qu, Zhihua, Lotfifard, Saeed, Haralambous, Michael, Wu, Xinzhang, Kutkut, Nasser, University of Central Florida
- Abstract / Description
-
Smart grid is more than just the smart meters. The future smart grids are expected to include ahigh penetration of distributed generations (DGs), most of which will consist of renewable energysources, such as solar or wind energy. It is believed that the high penetration of DGs will resultin the reduction of power losses, voltage profile improvement, meeting future load demand, andoptimizingthe use of non-conventionalenergy sources. However, more serious problems will ariseif a decent control...
Show moreSmart grid is more than just the smart meters. The future smart grids are expected to include ahigh penetration of distributed generations (DGs), most of which will consist of renewable energysources, such as solar or wind energy. It is believed that the high penetration of DGs will resultin the reduction of power losses, voltage profile improvement, meeting future load demand, andoptimizingthe use of non-conventionalenergy sources. However, more serious problems will ariseif a decent control mechanism is not exploited. An improperly managed high PV penetration maycause voltage profile disturbance, conflict with conventional network protection devices, interferewith transformer tap changers, and as a result, cause network instability.Indeed, it is feasible to organize DGs in a microgrid structure which will be connected to the maingrid through a point of common coupling (PCC). Microgrids are natural innovation zones for thesmart grid because of their scalability and flexibility. A proper organization and control of theinteraction between the microgrid and the smartgrid is a challenge.Cooperative control makes it possible to organize different agents in a networked system to actas a group and realize the designated objectives. Cooperative control has been already appliedto the autonomous vehicles and this work investigates its application in controlling the DGs in amicro grid. The microgrid power objectives are set by a higher level control and the application ofthe cooperative control makes it possible for the DGs to utilize a low bandwidth communicationnetwork and realize the objectives.Initially, the basics of the application of the DGs cooperative control are formulated. This includesorganizing all the DGs of a microgrid to satisfy an active and a reactive power objective. Then, thecooperative control is further developed by the introduction of clustering DGs into several groupsto satisfy multiple power objectives. Then, the cooperative distribution optimization is introducedto optimally dispatch the reactive power of the DGs to realize a unified microgrid voltage profileand minimizethelosses. Thisdistributedoptimizationis agradient based techniqueand itis shownthat when the communication is down, it reduces to a form of droop. However, this gradient baseddroop exhibits a superior performance in the transient response, by eliminating the overshootscaused by the conventional droop.Meanwhile, the interaction between each microgrid and the main grid can be formulated as aStackelberg game. The main grid as the leader, by offering proper energy price to the micro grid,minimizes its cost and secures the power. This not only optimizes the economical interests ofboth sides, the microgrids and the main grid, but also yields an improved power flow and shavesthe peak power. As such, a smartgrid may treat microgrids as individually dispatchable loads orgenerators.
Show less - Date Issued
- 2013
- Identifier
- CFE0004712, ucf:49817
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004712
- Title
- COMPARISON OF SINGLE STAGE AND TWO STAGE STAGE GRID-TIE INVERTERS.
- Creator
-
Mansfield, Keith, Batarseh, Issa, University of Central Florida
- Abstract / Description
-
This thesis compares two methods of designing grid-tie inverters. The first design topology is a traditional two stage approach consisting of an isolated DC-DC converter on the input followed by a high switching frequency SPWM (Sinusoidal Pulse Width Modulation) stage to produce the required low frequency sine wave output. The novel second design approach employs a similar DC-DC input stage capable of being modulated to provide a rectified sine wave output voltage/current waveform. This stage...
Show moreThis thesis compares two methods of designing grid-tie inverters. The first design topology is a traditional two stage approach consisting of an isolated DC-DC converter on the input followed by a high switching frequency SPWM (Sinusoidal Pulse Width Modulation) stage to produce the required low frequency sine wave output. The novel second design approach employs a similar DC-DC input stage capable of being modulated to provide a rectified sine wave output voltage/current waveform. This stage is followed by a simple low frequency switched Unfolding Stage to recreate the required sine wave output. Both of the above designs have advantages and disadvantages depending on operating parameters. The following work will compare the Unfolding Output Stage and the SPWM Output Stage at various power levels and power densities. Input stage topologies are similarly examined in order to determine the best design approach for each output stage under consideration.
Show less - Date Issued
- 2007
- Identifier
- CFE0001783, ucf:47258
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001783
- Title
- Data-driven Predictive Analytics For Distributed Smart Grid Control: Optimization of Energy Storage, Voltage and Demand Response.
- Creator
-
Valizadehhaghi, Hamed, Qu, Zhihua, Behal, Aman, Atia, George, Turgut, Damla, Pensky, Marianna, University of Central Florida
- Abstract / Description
-
The smart grid is expected to support an interconnected network of self-contained microgrids. Nonetheless, the distributed integration of renewable generation and demand response adds complexity to the control and optimization of smart grid. Forecasts are essential due to the existence of stochastic variations and uncertainty. Forecasting data are spatio-temporal which means that the data correspond to regular intervals, say every hour, and the analysis has to take account of spatial...
Show moreThe smart grid is expected to support an interconnected network of self-contained microgrids. Nonetheless, the distributed integration of renewable generation and demand response adds complexity to the control and optimization of smart grid. Forecasts are essential due to the existence of stochastic variations and uncertainty. Forecasting data are spatio-temporal which means that the data correspond to regular intervals, say every hour, and the analysis has to take account of spatial dependence among the distributed generators or locations. Hence, smart grid operations must take account of, and in fact benefit from the temporal dependence as well as the spatial dependence. This is particularly important considering the buffering effect of energy storage devices such as batteries, heating/cooling systems and electric vehicles. The data infrastructure of smart grid is the key to address these challenges, however, how to utilize stochastic modeling and forecasting tools for optimal and reliable planning, operation and control of smart grid remains an open issue.Utilities are seeking to become more proactive in decision-making, adjusting their strategies based on realistic predictive views into the future, thus allowing them to side-step problems and capitalize on the smart grid technologies, such as energy storage, that are now being deployed atscale. Predictive analytics, capable of managing intermittent loads, renewables, rapidly changing weather patterns and other grid conditions, represent the ultimate goal for smart grid capabilities.Within this framework, this dissertation develops high-performance analytics, such as predictive analytics, and ways of employing analytics to improve distributed and cooperative optimization software which proves to be the most significant value-add in the smart grid age, as new network management technologies prove reliable and fundamental. Proposed optimization and control approaches for active and reactive power control are robust to variations and offer a certain level of optimality by combining real-time control with hours-ahead network operation schemes. The main objective is managing spatial and temporal availability of the energy resources in different look-ahead time horizons. Stochastic distributed optimization is realized by integrating a distributed sub-gradient method with conditional ensemble predictions of the energy storage capacity and distributed generation. Hence, the obtained solutions can reflect on the system requirements for the upcoming times along with the instantaneous cooperation between distributed resources. As an important issue for smart grid, the conditional ensembles are studied for capturing wind, photovoltaic, and vehicle-to-grid availability variations. The following objectives are pursued:- Spatio-temporal adaptive modeling of data including electricity demand, electric vehicles and renewable energy (wind and solar power)- Predictive data analytics and forecasting- Distributed control- Integration of energy storage systemsFull distributional characterization and spatio-temporal modeling of data ensembles are utilized in order to retain the conditional and temporal interdependence between projection data and available capacity. Then, by imposing measures of the most likely ensembles, the distributed control method is carried out for cooperative optimization of the renewable generation and energy storage within the smart grid.
Show less - Date Issued
- 2016
- Identifier
- CFE0006408, ucf:51481
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006408
- Title
- TARGET ELEMENT SIZES FOR FINITE ELEMENT TIDAL MODELS FROM A DOMAIN-WIDE, LOCALIZED TRUNCATION ERROR ANALYSIS INCORPORATING BOTTOM STRESS AND CORIOLIS FORCE.
- Creator
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Parrish, Denwood, Hagen, Scott C., University of Central Florida
- Abstract / Description
-
A new methodology for the determination of target element sizes for the construction of finite element meshes applicable to the simulation of tidal flow in coastal and oceanic domains is developed and tested. The methodology is consistent with the discrete physics of tidal flow, and includes the effects of bottom stress. The method enables the estimation of the localized truncation error of the nonconservative momentum equations throughout a triangulated data set of water surface elevation...
Show moreA new methodology for the determination of target element sizes for the construction of finite element meshes applicable to the simulation of tidal flow in coastal and oceanic domains is developed and tested. The methodology is consistent with the discrete physics of tidal flow, and includes the effects of bottom stress. The method enables the estimation of the localized truncation error of the nonconservative momentum equations throughout a triangulated data set of water surface elevation and flow velocity. The method's domain-wide applicability is due in part to the formulation of a new localized truncation error estimator in terms of complex derivatives. More conventional criteria that are often used to determine target element sizes are limited to certain bathymetric conditions. The methodology developed herein is applicable over a broad range of bathymetric conditions, and can be implemented efficiently. Since the methodology permits the determination of target element size at points up to and including the coastal boundary, it is amenable to coastal domain applications including estuaries, embayments, and riverine systems. These applications require consideration of spatially varying bottom stress and advective terms, addressed herein. The new method, called LTEA-CD (localized truncation error analysis with complex derivatives), is applied to model solutions over the Western North Atlantic Tidal model domain (the bodies of water lying west of the 60° W meridian). The convergence properties of LTEACD are also analyzed. It is found that LTEA-CD may be used to build a series of meshes that produce converging solutions of the shallow water equations. An enhanced version of the new methodology, LTEA+CD (which accounts for locally variable bottom stress and Coriolis terms) is used to generate a mesh of the WNAT model domain having 25% fewer nodes and elements than an existing mesh upon which it is based; performance of the two meshes, in an average sense, is indistinguishable when considering elevation tidal signals. Finally, LTEA+CD is applied to the development of a mesh for the Loxahatchee River estuary; it is found that application of LTEA+CD provides a target element size distribution that, when implemented, outperforms a high-resolution semi-uniform mesh as well as a manually constructed, existing, documented mesh.
Show less - Date Issued
- 2007
- Identifier
- CFE0001738, ucf:52860
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001738
- Title
- GLOBAL SECURE SETS OF TREES AND GRID-LIKE GRAPHS.
- Creator
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Ho, Yiuyu, Dutton, Ronald, University of Central Florida
- Abstract / Description
-
Let G = (V, E) be a graph and let S be a subset of vertices. The set S is a defensive alliance if for all x in S, |N intersect S| >= |N - S|. The concept of defensive alliances was introduced in , primarily for the modeling of nations in times of war, where allied nations are in mutual agreement to join forces if anyone of them is attacked. For a vertex x in a defensive alliance, the number of neighbors of x inside the alliance, plus the vertex x, is at least the number of neighbors of x...
Show moreLet G = (V, E) be a graph and let S be a subset of vertices. The set S is a defensive alliance if for all x in S, |N intersect S| >= |N - S|. The concept of defensive alliances was introduced in , primarily for the modeling of nations in times of war, where allied nations are in mutual agreement to join forces if anyone of them is attacked. For a vertex x in a defensive alliance, the number of neighbors of x inside the alliance, plus the vertex x, is at least the number of neighbors of x outside the alliance. In a graph model, the vertices of a graph represent nations and the edges represent country boundaries. Thus, if the nation corresponding to a vertex x is attacked by its neighbors outside the alliance, the attack can be thwarted by x with the assistance of its neighbors in the alliance. In a different subject matter, applies graph theory to model the world wide web, where vertices represent websites and edges represent links between websites. A web community is a subset of vertices of the web graph, such that every vertex in the community has at least as many neighbors in the set as it has outside. So, a web community C satisfies for all x in C, |N intersect C| > |N - C|. These sets are very similar to defensive alliances. They are known as strong defensive alliances in the literature of alliances in graphs. Other areas of application for alliances and related topics include classification, data clustering, ecology, business and social networks. Consider the application of modeling nations in times of war introduced in the first paragraph. In a defensive alliance, any attack on a single member of the alliance can be successfully defended. However, as will be demonstrated in Chapter 1, a defensive alliance may not be able to properly defend itself when multiple members are under attack at the same time. The concept of secure sets is introduced in for exactly this purpose. The set S is a secure set if every subset X of S, with the assistance of vertices in S, can successfully defend against simultaneous attacks coming from vertices outside of S. The exact definition of simultaneous attacks and how such attacks may be defended will be provided in Chapter 1. In , the authors presented an interesting characterization for secure sets which resembles the definition of defensive alliances. A non-empty set S is a secure set if and only if for all subset X of S, |N intersect S| >= |N - S| (, Theorem 11). The cardinality of a minimum secure set is the security number of G, denoted s(G). A secure set S is a global secure set if it further satisfies N = V. The cardinality of a minimum global secure set of G is the global security number of G, denoted gs(G). In this work, we present results on secure sets and global secure sets. In particular, we present algorithms and bounds for the global security numbers of trees, and the exact values of the global security numbers of paths, cycles and their Cartesian products. Petter Kristiansen, Sandra M. Hedetniemi, and Stephen T. Hedetniemi. "Alliances in graphs." J. Combin. Math. Combin. Comput., 48:157-177, 2004. G. W. Flake, S. Lawrence, and C. L. Giles. "Efficient identification of web communities." ACM SIGKDD, pp. 150-160, 2000. Robert C. Brigham, Ronald D. Dutton, and Stephen T. Hedetniemi. "Security in graphs." Discrete Appl. Math., 155(13):1708-1714, 2007.
Show less - Date Issued
- 2011
- Identifier
- CFE0003888, ucf:48719
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003888
- Title
- MODELING, DESIGN AND EVALUATION OF NETWORKING SYSTEMS AND PROTOCOLS THROUGH SIMULATION.
- Creator
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Lacks, Daniel, Kocak, Taskin, University of Central Florida
- Abstract / Description
-
Computer modeling and simulation is a practical way to design and test a system without actually having to build it. Simulation has many benefits which apply to many different domains: it reduces costs creating different prototypes for mechanical engineers, increases the safety of chemical engineers exposed to dangerous chemicals, speeds up the time to model physical reactions, and trains soldiers to prepare for battle. The motivation behind this work is to build a common software framework...
Show moreComputer modeling and simulation is a practical way to design and test a system without actually having to build it. Simulation has many benefits which apply to many different domains: it reduces costs creating different prototypes for mechanical engineers, increases the safety of chemical engineers exposed to dangerous chemicals, speeds up the time to model physical reactions, and trains soldiers to prepare for battle. The motivation behind this work is to build a common software framework that can be used to create new networking simulators on top of an HLA-based federation for distributed simulation. The goals are to model and simulate networking architectures and protocols by developing a common underlying simulation infrastructure and to reduce the time a developer has to learn the semantics of message passing and time management to free more time for experimentation and data collection and reporting. This is accomplished by evolving the simulation engine through three different applications that model three different types of network protocols. Computer networking is a good candidate for simulation because of the Internet's rapid growth that has spawned off the need for new protocols and algorithms and the desire for a common infrastructure to model these protocols and algorithms. One simulation, the 3DInterconnect simulator, simulates data transmitting through a hardware k-array n-cube network interconnect. Performance results show that k-array n-cube topologies can sustain higher traffic load than the currently used interconnects. The second simulator, Cluster Leader Logic Algorithm Simulator, simulates an ad-hoc wireless routing protocol that uses a data distribution methodology based on the GPS-QHRA routing protocol. CLL algorithm can realize a maximum of 45% power savings and maximum 25% reduced queuing delay compared to GPS-QHRA. The third simulator simulates a grid resource discovery protocol for helping Virtual Organizations to find resource on a grid network to compute or store data on. Results show that worst-case 99.43% of the discovery messages are able to find a resource provider to use for computation. The simulation engine was then built to perform basic HLA operations. Results show successful HLA functions including creating, joining, and resigning from a federation, time management, and event publication and subscription.
Show less - Date Issued
- 2007
- Identifier
- CFE0001887, ucf:47399
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001887
- Title
- Automated Hybrid Singularity Superposition and Anchored Grid Pattern BEM Algorithm for the Solution of the Inverse Geometric Problem.
- Creator
-
Ni, Marcus, Kassab, Alain, Divo, Eduardo, Chopra, Manoj, University of Central Florida
- Abstract / Description
-
A method for solving the inverse geometrical problem is presented by reconstructing the unknown subsurface cavity geometry using boundary element methods, a genetic algorithm, and Nelder-Mead non-linear simplex optimization. The heat conduction problem is solved utilizing the boundary element method, which calculates the difference between the measured temperature at the exposed surface and the computed temperature under the current update of the unknown subsurface flaws and cavities. In a...
Show moreA method for solving the inverse geometrical problem is presented by reconstructing the unknown subsurface cavity geometry using boundary element methods, a genetic algorithm, and Nelder-Mead non-linear simplex optimization. The heat conduction problem is solved utilizing the boundary element method, which calculates the difference between the measured temperature at the exposed surface and the computed temperature under the current update of the unknown subsurface flaws and cavities. In a first step, clusters of singularities are utilized to solve the inverse problem and to identify the location of the centroid(s) of the subsurface cavity(ies)/flaw(s). In a second step, the reconstruction of the estimated cavity(ies)/flaw(s) geometry(ies) is accomplished by utilizing an anchored grid pattern upon which cubic spline knots are restricted to move in the search for unknown geometry. Solution of the inverse problem is achieved using a genetic algorithm accelerated with the Nelder-Mead non-linear simplex. To optimize the cubic spline interpolated geometry, the flux (Neumann) boundary conditions are minimized using a least squares functional. The automated algorithm successfully reconstructs single and multiple subsurface cavities within two dimensional mediums. The solver is also shown to accurately predict cavity geometries with random noise in the boundary condition measurements. Subsurface cavities can be difficult to detect based on their location. By applying different boundary conditions to the same geometry, more information is supplied at the boundary, and the subsurface cavity is easily detected despite its low heat signature effect at the boundaries. Extensions to three-dimensional applications are outlined.
Show less - Date Issued
- 2013
- Identifier
- CFE0004900, ucf:49644
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004900
- Title
- INTERACTION BETWEEN SECONDARY FLOW AND FILM COOLING JETS OF A REALISTIC ANNULAR AIRFOIL CASCADE (HIGH MACH NUMBER).
- Creator
-
Nguyen, Cuong, Kapat, Jayanta, University of Central Florida
- Abstract / Description
-
Film cooling is investigated on a flat plate both numerically and experimentally. Conical shaped film hole are investigated extensively and contribute to the current literature data, which is extremely rare in the open public domain. Both configuration of the cylindrical film holes, with and without a trench, are investigated in detail. Design of experiment technique was performed to find an optimum combination of both geometrical and fluid parameters to achieve the best film cooling...
Show moreFilm cooling is investigated on a flat plate both numerically and experimentally. Conical shaped film hole are investigated extensively and contribute to the current literature data, which is extremely rare in the open public domain. Both configuration of the cylindrical film holes, with and without a trench, are investigated in detail. Design of experiment technique was performed to find an optimum combination of both geometrical and fluid parameters to achieve the best film cooling performance. From this part of the study, it shows that film cooling performance can be enhanced up to 250% with the trenched film cooling versus non-trenched case provided the same amount of coolant. Since most of the relevant open literature is about film cooling on flat plate endwall cascade with linear extrusion airfoil, the purpose of the second part of this study is to examine the interaction of the secondary flow inside a 3D cascade and the injected film cooling jets. This is employed on the first stage of the aircraft gas turbine engine to protect the curvilinear (annular) endwall platform. The current study investigates the interaction between injected film jets and the secondary flow both experimentally and numerically at high Mach number (M=0.7). Validation shows good agreement between obtained data with the open literature. In general, it can be concluded that with an appropriate film coolant to mainstream blowing ratio, one can not only achieve the best film cooling effectiveness (FCE or η) on the downstream endwall but also maintain almost the same aerodynamic loss as in the un-cooled baseline case. Film performance acts nonlinearly with respect to blowing ratios as with film cooling on flat plate, in the other hand, with a right blowing ratio, film cooling performance is not affect much by secondary flow. In turn, film cooling jets do not increase pressure loss at the downstream wake area of the blades.
Show less - Date Issued
- 2010
- Identifier
- CFE0003546, ucf:48944
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003546
- Title
- A framework for interoperability on the United States electric grid infrastructure.
- Creator
-
Laval, Stuart, Rabelo, Luis, Zheng, Qipeng, Xanthopoulos, Petros, Ajayi, Richard, University of Central Florida
- Abstract / Description
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Historically, the United States (US) electric grid has been a stable one-way power delivery infrastructure that supplies centrally-generated electricity to its predictably consuming demand. However, the US electric grid is now undergoing a huge transformation from a simple and static system to a complex and dynamic network, which is starting to interconnect intermittent distributed energy resources (DERs), portable electric vehicles (EVs), and load-altering home automation devices, that...
Show moreHistorically, the United States (US) electric grid has been a stable one-way power delivery infrastructure that supplies centrally-generated electricity to its predictably consuming demand. However, the US electric grid is now undergoing a huge transformation from a simple and static system to a complex and dynamic network, which is starting to interconnect intermittent distributed energy resources (DERs), portable electric vehicles (EVs), and load-altering home automation devices, that create bidirectional power flow or stochastic load behavior. In order for this grid of the future to effectively embrace the high penetration of these disruptive and fast-responding digital technologies without compromising its safety, reliability, and affordability, plug-and-play interoperability within the field area network must be enabled between operational technology (OT), information technology (IT), and telecommunication assets in order to seamlessly and securely integrate into the electric utility's operations and planning systems in a modular, flexible, and scalable fashion. This research proposes a potential approach to simplifying the translation and contextualization of operational data on the electric grid without being routed to the utility datacenter for a control decision. This methodology integrates modern software technology from other industries, along with utility industry-standard semantic models, to overcome information siloes and enable interoperability. By leveraging industrial engineering tools, a framework is also developed to help devise a reference architecture and use-case application process that is applied and validated at a US electric utility.
Show less - Date Issued
- 2015
- Identifier
- CFE0005647, ucf:50193
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005647