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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Managing Congestion and Intermittent Renewable Generation in Liberalized Electricity Markets

Kunz, Friedrich 04 August 2015 (has links)
This dissertation focuses on selected aspects of network congestion arising in liberalized electricity markets and their management methods with a special weight placed on the integration of increased renewable generation in Europe and Germany. In a first step, the theoretical concepts of congestion management are introduced complemented by a review of current management regimes in selected countries. In the second step, the European approach of managing congestion on international as well as national transmission links is analyzed and the benefits of an integrated congestion management regime are quantified. It is concluded that benefits can be achieved by a closer cooperation of national transmission system operators (TSOs). Thirdly, the German congestion management regime is investigated and the impact of higher renewable generation up to 2020 on congestion management cost is determined. It is shown that a homogeneous and jointly development of generation and transmission infrastructure is a prerequisite for the application of congestion alleviation methods and once they diverge congestion management cost tend to increase substantially. Lastly, the impact of intermittent and uncertain wind generation on electricity markets is analyzed. A stochastic electricity market model is described, which replicates the daily subsequent clearing of reserve, dayahead, and intraday market typical for European countries, and numerical results are presented.
12

Managing Congestion and Intermittent Renewable Generation in Liberalized Electricity Markets

Kunz, Friedrich 27 February 2013 (has links)
This dissertation focuses on selected aspects of network congestion arising in liberalized electricity markets and their management methods with a special weight placed on the integration of increased renewable generation in Europe and Germany. In a first step, the theoretical concepts of congestion management are introduced complemented by a review of current management regimes in selected countries. In the second step, the European approach of managing congestion on international as well as national transmission links is analyzed and the benefits of an integrated congestion management regime are quantified. It is concluded that benefits can be achieved by a closer cooperation of national transmission system operators (TSOs). Thirdly, the German congestion management regime is investigated and the impact of higher renewable generation up to 2020 on congestion management cost is determined. It is shown that a homogeneous and jointly development of generation and transmission infrastructure is a prerequisite for the application of congestion alleviation methods and once they diverge congestion management cost tend to increase substantially. Lastly, the impact of intermittent and uncertain wind generation on electricity markets is analyzed. A stochastic electricity market model is described, which replicates the daily subsequent clearing of reserve, dayahead, and intraday market typical for European countries, and numerical results are presented.
13

E-model: event-based graph data model theory and implementation

Kim, Pilho 06 July 2009 (has links)
The necessity of managing disparate data models is increasing within all IT areas. Emerging hybrid relational-XML systems are under development in this context to support both relational and XML data models. However, there are ever-growing needs for adequate data models for texts and multimedia, which are applications that require proper storage, and their capability to coexist and collaborate with other data models is as important as that of a relational-XML hybrid model. This work proposes a new data model named E-model that supports rich relations and reflects the dynamic nature of information. This E-model introduces abstract data typing objects and rules of relation that support: (1) the notion of time in object definition and relation, (2) multiple-type relations, (3) complex schema modeling methods using a relational directed acyclic graph, and (4) interoperation with popular data models. To implement the E-model prototype, extensive data operation APIs have been developed on top of relational databases. In processing dynamic queries, our prototype achieves an order of magnitude improvement in speed compared with popular data models. Based on extensive E-model APIs, a new language named EML is proposed. EML extends the SQL-89 standard with various E-model features: (1) unstructured queries, (2) unified object namespaces, (3) temporal queries, (4) ranking orders, (5) path queries, and (6) semantic expansions. The E-model system can interoperate with popular data models with its rich relations and flexible structure to support complex data models. It can act as a stand-alone database server or it can also provide materialized views for interoperation with other data models. It can also co-exist with established database systems as a centralized online archive or as a proxy database server. The current E-model prototype system was implemented on top of a relational database. This allows significant benefits from established database engines in application development. In addition to extensive features added to SQL, our EML prototype achieves an order of magnitude speed improvement in dynamic queries compared to popular database models. Availability Release the entire work immediately for access worldwide after my graduation.
14

Model klienta veřejné správy z pohledu Unified Foundational Ontology / Model of public administration client from the perspective of Unified Foundational Ontology

Marek, Jan January 2017 (has links)
The thesis deals with possibilities of using Unified Foundational Ontology in modeling the onto-logical model of the public administration client, which was created as a result of the Optimiza-tion of life situations in relation to the Register of Rights and Obligations project. The main aim of this thesis is to extend and propose a modification of the current methodology of modeling the ontological model of the public administration client corresponding to the UFO-A ontology. By analyzing the current methodology and ontological model, it proposes the incorporation of OntoUML, which is based on UFO-A ontology. Its key benefit is the methodology of modeling the ontological model of the public administration client corresponding to the UFO-A ontology. The proposed methodology is presented in a case study.
15

Assessment of Managed Aquifer Recharge through Modeling—A Review

Ringleb, Jana, Stefan, Catalin, Sallwey, Jana 28 March 2017 (has links)
Managed aquifer recharge (MAR) is the purposeful recharge of an aquifer for later recovery or environmental benefits and represents a valuable method for sustainable water resources management. Models can be helpful tools for the assessment of MAR systems. This review encompasses a survey and an analysis of case studies which apply flow and transport models to evaluate MAR. The observed modeling objectives include the planning or optimization of MAR schemes as well as the identification and quantification of geochemical processes during injection, storage and recovery. The water recovery efficiency and the impact of the injected water on the ambient groundwater are further objectives investigated in the reviewed studies. These objectives are mainly solved by using groundwater flow models. Unsaturated flow models, solute transport models, reactive geochemical models as well as water balance models are also frequently applied and often coupled. As each planning step to setup a new MAR facility requires cost and time investment, modeling is used to minimize hazard risks and assess possible constraints of the system such as low recovery efficiency, clogging and geochemical processes.
16

Room for More of Us? : Important Design Features for Informed Decision-Making in BIM-enabled Facility Management

Koort, Hannes January 2021 (has links)
Building Information Modeling (BIM) is becoming imperative across building disciplines to improve communication and workflow from the first blueprint. Maintenance and facility management is however lagging behind in adoption and research of BIM. Utilizing research-through-design, this study explores BIM-enabled facility management and the critical practice of decision-making at the Celsius building in Uppsala. Contextual design and inquiry were applied to identify and suggest important design features that support decisions related to the task of establishing maximum room occupation. Results show that facility managers can make use of fuzzy multicriteria decision-making and expert heuristics to independently reach conclusions. Important design features were found to heavily rely on the existing building models, where context-view filtered to room capacity data in the existing BIM-system effectively supported the users’ assessment of data. The filtered, aggregated information presented in a simplified mobile format was insufficient for decision-making, suggesting that the building model was more important than initially perceived.

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