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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

A 3d geoscience information system framework

Apel, Marcus 17 December 2004 (has links)
Two-dimensional geographical information systems are extensively used in the geosciences to create and analyse maps. However, these systems are unable to represent the Earth's subsurface in three spatial dimensions. The objective of this thesis is to overcome this deficiency, to provide a general framework for a 3d geoscience information system (GIS), and to contribute to the public discussion about the development of an infrastructure for geological observation data, geomodels, and geoservices. Following the objective, the requirements for a 3d GIS are analysed. According to the requirements, new geologically sensible query functionality for geometrical, topological and geological properties has been developed and the integration of 3d geological modeling and data management system components in a generic framework has been accomplished. The 3d geoscience information system framework presented here is characterized by the following features: - Storage of geological observation data and geomodels in a XML-database server. According to a new data model, geological observation data can be referenced by a set of geomodels. - Functionality for querying observation data and 3d geomodels based on their 3d geometrical, topological, material, and geological properties were developed and implemented as plug-in for a 3d geomodeling user application. - For database queries, the standard XML query language has been extended with 3d spatial operators. The spatial database query operations are computed using a XML application server which has been developed for this specific purpose. This technology allows sophisticated 3d spatial and geological database queries. Using the developed methods, queries can be answered like: "Select all sandstone horizons which are intersected by the set of faults F". This request contains a topological and a geological material parameter. The combination of queries with other GIS methods, like visual and statistical analysis, allows geoscience investigations in a novel 3d GIS environment. More generally, a 3d GIS enables geologists to read and understand a 3d digital geomodel analogously as they read a conventional 2d geological map.
12

Optimized Renewable Energy Forecasting in Local Distribution Networks

Ulbricht, Robert, Fischer, Ulrike, Lehner, Wolfgang, Donker, Hilko 16 September 2022 (has links)
The integration of renewable energy sources (RES) into local energy distribution networks becomes increasingly important. Renewable energy highly depends on weather conditions, making it difficult to maintain stability in such networks. To still enable efficient planning and balancing, forecasts of energy supply are essential. However, typical distribution networks contain a variety of heterogeneous RES installations (e.g. wind, solar, water), each providing different characteristics and weather dependencies. Additionally, advanced meters, which allow the communication of final-granular production curves to the network operator, are not available at all RES sites. Despite these heterogeneities and missing measurements, reliable forecasts over the whole local distribution network have to be provided. This poses high challenges on choosing the right input parameters, statistical models and forecasting granularity (e.g. single RES installations vs. aggregated data). In this paper, we will discuss such problems in energy supply forecasting using a real-world scenario. Subsequently, we introduce our idea of a generalized optimization approach that determines the best forecasting strategy for a given scenario and sketch research challenges we are planning to investigate in future work.
13

Probabilistic information retrieval in a distributed heterogeneous environment

Baumgarten, Christoph 01 October 1999 (has links) (PDF)
This thesis describes a probabilistic model for optimum information retrieval in a distributed heterogeneous environment. The model assumes the collection of documents offered by the environment to be hierarchically partitioned into subcollections. Documents as well as subcollections have to be indexed. At this indexing methods using different indexing vocabularies can be employed. A query provided by a user is answered in terms of a ranked list of documents. The model determines a procedure for ranking the documents that stems from the Probability Ranking Principle: For each subcollection the subcollection´s elements are ranked; the resulting ranked lists are combined into a final ranked list of documents where the ordering is determined by the documents´ probabilities of being relevant with respect to the user´s query. Various probabilistic ranking methods may be involved in the distributed ranking process. The underlying data volume is arbitrarily scalable. A criterion for effectively limiting the ranking process to a subset of subcollections extends the model. The model´s applicability is experimentally confirmed. When exploiting the degrees of freedom provided by the model experiments showed evidence that the model even outperforms comparable models for the non-distributed case with respect to retrieval effectiveness. An architecture for a distributed information retrieval system is presented that realizes the probabilistic model. The system provides access to an arbitrary number of dynamic multimedia databases.
14

Kontextbasiertes Information-Retrieval : Modell, Konzeption und Realisierung kontextbasierter Information-Retrieval-Systeme /

Morgenroth, Karlheinz. January 2006 (has links)
Universiẗat, Diss., 2006--Bamberg.
15

Structural Dynamics of DNA Hydration Shell Studied by 2D IR and Pump-Probe Technique

Liu, Yingliang 17 November 2017 (has links)
Biochemische Prozesse treten in wässriger Umgebung auf und Wechselwirkungen der Wasserhülle mit Biomolekülen spielt eine Schlüsselrolle für deren Struktur und Funktion. In dieser Arbeit wird die Strukturdynamik der Wassermoleküle und Gegenionen in der umgebenden Wasserhülle der DNA mit der Methode der zweidimensionalen Infrarotspektroskopie (2D IR) sowie Anrege-Abfrage-Spektroskopie untersucht. Die Ergebnisse der vorliegenden Arbeit zeigt das starke Potenzial von Schwingungsmoden an Grenzflächen für die Abbildung und das Verständnis von Wechselwirkungen zwischen Biomolekülen und ihrer Wasserhülle. In Zukunft soll dieses Konzept auch auf andere Biomoleküle angewendet werden. / Biochemical processes occur in an aqueous environment and interactions of the water shell with biomolecules play a key role for their structure and function. In this thesis, the structural dynamics of water molecules and counterions in the hydration shell of DNA is investigated by two-dimensional infrared (2D IR) spectroscopy and pump-probe transient spectroscopy. 2D IR spectroscopy is a powerful technique that can track molecular couplings between different vibrational modes and structural fluctuations of the chemical environment on a femto- to picosecond time scale. In the present study, vibrational modes of the DNA backbone serve as probes located at the DNA-water interface. The results of this thesis demonstrate the strong potential of interfacial vibrational modes for mapping and understanding interactions between biomolecules and their water shell. In future, this concept will be applied to other biomolecular systems.
16

Probabilistic information retrieval in a distributed heterogeneous environment

Baumgarten, Christoph 15 February 1999 (has links)
This thesis describes a probabilistic model for optimum information retrieval in a distributed heterogeneous environment. The model assumes the collection of documents offered by the environment to be hierarchically partitioned into subcollections. Documents as well as subcollections have to be indexed. At this indexing methods using different indexing vocabularies can be employed. A query provided by a user is answered in terms of a ranked list of documents. The model determines a procedure for ranking the documents that stems from the Probability Ranking Principle: For each subcollection the subcollection´s elements are ranked; the resulting ranked lists are combined into a final ranked list of documents where the ordering is determined by the documents´ probabilities of being relevant with respect to the user´s query. Various probabilistic ranking methods may be involved in the distributed ranking process. The underlying data volume is arbitrarily scalable. A criterion for effectively limiting the ranking process to a subset of subcollections extends the model. The model´s applicability is experimentally confirmed. When exploiting the degrees of freedom provided by the model experiments showed evidence that the model even outperforms comparable models for the non-distributed case with respect to retrieval effectiveness. An architecture for a distributed information retrieval system is presented that realizes the probabilistic model. The system provides access to an arbitrary number of dynamic multimedia databases.
17

A Generic Language for Query and Viewtype Generation By-Example

Werner, Christopher, Wimmer, Manuel, Aßmann, Uwe 02 July 2021 (has links)
In model-driven engineering, powerful query/view languages exist to compute result sets/views from underlying models. However, to use these languages effectively, one must understand the query/view language concepts as well as the underlying models and metamodels structures. Consequently, it is a challenge for domain experts to create queries/views due to the lack of knowledge about the computer-internal abstract representation of models and metamodels. To better support domain experts in the query/view creation, the goal of this paper is the presentation of a generic concept to specify queries/views on models without requiring deep knowledge on the realization of modeling languages. The proposed concept is agnostic to specific modeling languages and allows the query/view generation by-example with a simple mechanism for filtering model elements. Based on this generic concept, a generic query/view language is proposed that uses role-oriented modeling for its non-intrusive application for specific modeling languages. The proposed language is demonstrated based on the role-based single underlying model (RSUM) approach for AutomationML to create queries/views by-example, and subsequently, associated viewtypes to modify the result set or view.
18

Bringing Linear Algebra Objects to Life in a Column-Oriented In-Memory Database

Kernert, David, Köhler, Frank, Lehner, Wolfgang 27 January 2023 (has links)
Large numeric matrices and multidimensional data arrays appear in many science domains, as well as in applications of financial and business warehousing. Common applications include eigenvalue determination of large matrices, which decompose into a set of linear algebra operations. With the rise of in-memory databases it is now feasible to execute these complex analytical queries directly in a relational database system without the need of transfering data out of the system and being restricted by hard disc latencies for random accesses. In this paper, we present a way to integrate linear algebra operations and large matrices as first class citizens into an in-memory database following a two-layered architectural model. The architecture consists of a logical component receiving manipulation statements and linear algebra expressions, and of a physical layer, which autonomously administrates multiple matrix storage representations. A cost-based hybrid storage representation is presented and an experimental implementation is evaluated for matrix-vector multiplications.
19

Highspeed Graph Processing Exploiting Main-Memory Column Stores

Hauck, Matthias, Paradies, Marcus, Fröning, Holger, Lehner, Wolfgang, Rauhe, Hannes 03 February 2023 (has links)
A popular belief in the graph database community is that relational database management systems are generally ill-suited for efficient graph processing. This might apply for analytic graph queries performing iterative computations on the graph, but does not necessarily hold true for short-running, OLTP-style graph queries. In this paper we argue that, instead of extending a graph database management system with traditional relational operators—predicate evaluation, sorting, grouping, and aggregations among others—one should consider adding a graph abstraction and graph-specific operations, such as graph traversals and pattern matching, to relational database management systems. We use an exemplary query from the interactive query workload of the LDBC social network benchmark and run it against our enhanced in-memory, columnar relational database system to support our claims. Our performance measurements indicate that a columnar RDBMS—extended by graph-specific operators and data structures—can serve as a foundation for high-speed graph processing on big memory machines with non-uniform memory access and a large number of available cores.
20

XML Stream Processing Quality

Schmidt, Sven, Gemulla, Rainer, Lehner, Wolfgang 12 January 2023 (has links)
Systems for selective dissemination of information (SDI) are used to efficiently filter, transform, and route incoming XML documents according to pre-registered XPath profiles to subscribers. Recent work focuses on the efficient implementation of the SDI core/filtering engine. Surprisingly, all systems are based on the best effort principle: The resulting XML document is delivered to the consumer as soon as the filtering engine has successfully finished. In this paper, we argue that a more specific Quality-of-Service consideration has to be applied to this scenario. We give a comprehensive motivation of quality of service in SDI-systems, discuss the two most critical factors of XML document size and shape and XPath structure and length, and finally outline our current prototype of a Quality-of-Service-based SDI-system implementation based on a real-time operating system and an extention of the XML toolkit.

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