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https://kobra.uni-kassel.de:443/handle/123456789/16028
Parametric timed automata (PTA) have been introduced by Alur, Henzinger, and Vardi as an extension of timed automata in which clocks can be compared against parameters. The reachability problem asks for the existence of an assignment of the parameters to the non-negative integers such that reachability holds in the underlying timed automaton. The reachability problem for PTA is long known to be undecidable, already over three parametric clocks. A few years ago, Bundala and Ouaknine proved that for PTA over two parametric clocks and one parameter the reachability problem is decidable and also showed a lower bound for the complexity class PSPACENEXP. Our main result is that the reachability problem for two-parametric timed automata with one parameter is EXPSPACE-complete. Our contribution is two-fold. For the EXPSPACE lower bound, inspired by [13, 14], we make use of deep results from complexity theory, namely a serializability characterization of EXPSPACE (in turn based on Barrington’s Theorem) and a logspace translation of numbers in Chinese remainder representation to binary representation due to Chiu, Davida, and Litow. It is shown that with small PTA over two parametric clocks and one parameter one can simulate serializability computations. For the EXPSPACE upper bound, we first give a careful exponential time reduction from PTA over two parametric clocks and one parameter to a (slight subclass of) parametric one-counter automata over one parameter based on a minor adjustment of a construction due to Bundala and Ouaknine. For solving the reachability problem for parametric one-counter automata with one parameter, we provide a series of techniques to partition a fictitious run into several carefully chosen subruns that allow us to prove that it is sufficient to consider a parameter value of exponential magnitude only. This allows us to show a doubly-exponential upper bound on the value of the only parameter of a PTA over two parametric clocks and one parameter. We hope that extensions of our techniques lead to finally establishing decidability of the long-standing open problem of reachability in parametric timed automata with two parametric clocks (and arbitrarily many parameters) and, if decidability holds, determinining its precise computational complexity.
Mon, 24 Apr 2023 00:00:00 GMThttps://kobra.uni-kassel.de:443/handle/123456789/160282023-04-24T00:00:00ZGöller, StefanHilaire, MathieuParametric timed automata (PTA) have been introduced by Alur, Henzinger, and Vardi as an extension of timed automata in which clocks can be compared against parameters. The reachability problem asks for the existence of an assignment of the parameters to the non-negative integers such that reachability holds in the underlying timed automaton. The reachability problem for PTA is long known to be undecidable, already over three parametric clocks. A few years ago, Bundala and Ouaknine proved that for PTA over two parametric clocks and one parameter the reachability problem is decidable and also showed a lower bound for the complexity class PSPACENEXP. Our main result is that the reachability problem for two-parametric timed automata with one parameter is EXPSPACE-complete. Our contribution is two-fold. For the EXPSPACE lower bound, inspired by [13, 14], we make use of deep results from complexity theory, namely a serializability characterization of EXPSPACE (in turn based on Barrington’s Theorem) and a logspace translation of numbers in Chinese remainder representation to binary representation due to Chiu, Davida, and Litow. It is shown that with small PTA over two parametric clocks and one parameter one can simulate serializability computations. For the EXPSPACE upper bound, we first give a careful exponential time reduction from PTA over two parametric clocks and one parameter to a (slight subclass of) parametric one-counter automata over one parameter based on a minor adjustment of a construction due to Bundala and Ouaknine. For solving the reachability problem for parametric one-counter automata with one parameter, we provide a series of techniques to partition a fictitious run into several carefully chosen subruns that allow us to prove that it is sufficient to consider a parameter value of exponential magnitude only. This allows us to show a doubly-exponential upper bound on the value of the only parameter of a PTA over two parametric clocks and one parameter. We hope that extensions of our techniques lead to finally establishing decidability of the long-standing open problem of reachability in parametric timed automata with two parametric clocks (and arbitrarily many parameters) and, if decidability holds, determinining its precise computational complexity.Individualrechte in der KI-Verordnung
https://kobra.uni-kassel.de:443/handle/123456789/16027
Während der Kommissionsentwurf zur KI-VO die Rechtspositionen der betroffenen Personen praktisch komplett ausblendete, enthält der verabschiedete Normtext einen deutlich stärkeren Fokus in dieser Richtung und führt insbesondere zwei neue Betroffenenrechte ein. Angesichts der Grundrechtsrelevanz vieler KI-Systeme ist dies zu begrüßen; die konkrete Umsetzung führt allerdings zu neuen Fragen sowohl in der Binnensystematik der KI-VO als auch im Verhältnis zur DS-GVO.
Tue, 20 Aug 2024 00:00:00 GMThttps://kobra.uni-kassel.de:443/handle/123456789/160272024-08-20T00:00:00ZHornung, GerritWährend der Kommissionsentwurf zur KI-VO die Rechtspositionen der betroffenen Personen praktisch komplett ausblendete, enthält der verabschiedete Normtext einen deutlich stärkeren Fokus in dieser Richtung und führt insbesondere zwei neue Betroffenenrechte ein. Angesichts der Grundrechtsrelevanz vieler KI-Systeme ist dies zu begrüßen; die konkrete Umsetzung führt allerdings zu neuen Fragen sowohl in der Binnensystematik der KI-VO als auch im Verhältnis zur DS-GVO.Comparison of solar district heating and renovation of buildings as measures for decarbonization of heat supply in rural areas
https://kobra.uni-kassel.de:443/handle/123456789/16026
In this study two different decarbonization strategies for rural heat supply are compared on the example of 180 buildings located in a small village in Germany with about 860 inhabitants and typically mainly old buildings, partly in half-timbered construction. The comparison shows that erection of a solar district heating system with solar fraction of about 67 % leads to similar heating costs as an energy efficient renovation followed by installation of decentralized air source heat pumps for most of the buildings. Both concepts aim to achieve a heat supply that is free from the local use of fossil fuels. While the solar district heating system can probably be realized within a few years and therefore achieves the full CO2 savings promptly, this would take decades for the implementation of energy efficient renovation and heat pumps due to low renovation rate. Reaching climate-neutrality for the heat supply could thus be accelerated significantly by the construction of a solar district heating system. Moreover, the two decarbonization approaches do not appear to be fundamentally mutually exclusive: subsequent steady renovation of connected buildings will either increase solar share in heat supply or enable connection of new consumers at similar solar coverage rate. However, it should be also noted that with solar district heating alone, not always the same thermal comfort as with reinforced building renovation is achieved.
Fri, 07 Jun 2024 00:00:00 GMThttps://kobra.uni-kassel.de:443/handle/123456789/160262024-06-07T00:00:00ZKelch, JanKusyy, OlegZipplies, JohannesOrozaliev, JanybekVajen, KlausIn this study two different decarbonization strategies for rural heat supply are compared on the example of 180 buildings located in a small village in Germany with about 860 inhabitants and typically mainly old buildings, partly in half-timbered construction. The comparison shows that erection of a solar district heating system with solar fraction of about 67 % leads to similar heating costs as an energy efficient renovation followed by installation of decentralized air source heat pumps for most of the buildings. Both concepts aim to achieve a heat supply that is free from the local use of fossil fuels. While the solar district heating system can probably be realized within a few years and therefore achieves the full CO2 savings promptly, this would take decades for the implementation of energy efficient renovation and heat pumps due to low renovation rate. Reaching climate-neutrality for the heat supply could thus be accelerated significantly by the construction of a solar district heating system. Moreover, the two decarbonization approaches do not appear to be fundamentally mutually exclusive: subsequent steady renovation of connected buildings will either increase solar share in heat supply or enable connection of new consumers at similar solar coverage rate. However, it should be also noted that with solar district heating alone, not always the same thermal comfort as with reinforced building renovation is achieved.Acoustic condition monitoring of coffee beans, during the roasting process
https://kobra.uni-kassel.de:443/handle/123456789/16025
The research results presented here deal with the acoustic condition monitoring of coffee beans during the roasting process. In particular, the question was investigated whether the current state (roasting level) of the coffee beans during the roasting process can be detected by acoustic monitoring. To answer this question, an experiment was carried out with a sample drum roaster (Hottop KN–8828B– 2K+) in which the airborne sound pressure was recorded for five different roasting methods and then examined. The methods used differed in the inner temperature of the roaster when the coffee beans were inserted (75◦C, 100◦C, 150◦C, 175◦C, 200◦C). The recording of the roasting processes has been made by two microphones placed in front of the drum, with each process being repeated five times. To enable a comparison between the different processes, five points at which the coffee beans had reached a certain temperature were determined for each grating. Five sequences of equal length were then cut from each recording, with the determined time points serving as the starting value of the sequence.
First, the differences in the spectral composition of the signals in the first and second crack were investigated and compared with those in other past publications. Furthermore, the comparison of the behavior as a function of the throw-in temperature has been investigated. For most of the processes analysed, the sound pressure levels can be clearly separated as a function of the bean temperature. In conclusion, it was shown that sound analysis can be used to determine the proportion of cracked beans.
Sat, 27 Apr 2024 00:00:00 GMThttps://kobra.uni-kassel.de:443/handle/123456789/160252024-04-27T00:00:00ZSiebald, HubertusMöller, MortenLenz, FinnKirchner, SaschaHensel, OliverThe research results presented here deal with the acoustic condition monitoring of coffee beans during the roasting process. In particular, the question was investigated whether the current state (roasting level) of the coffee beans during the roasting process can be detected by acoustic monitoring. To answer this question, an experiment was carried out with a sample drum roaster (Hottop KN–8828B– 2K+) in which the airborne sound pressure was recorded for five different roasting methods and then examined. The methods used differed in the inner temperature of the roaster when the coffee beans were inserted (75◦C, 100◦C, 150◦C, 175◦C, 200◦C). The recording of the roasting processes has been made by two microphones placed in front of the drum, with each process being repeated five times. To enable a comparison between the different processes, five points at which the coffee beans had reached a certain temperature were determined for each grating. Five sequences of equal length were then cut from each recording, with the determined time points serving as the starting value of the sequence.
First, the differences in the spectral composition of the signals in the first and second crack were investigated and compared with those in other past publications. Furthermore, the comparison of the behavior as a function of the throw-in temperature has been investigated. For most of the processes analysed, the sound pressure levels can be clearly separated as a function of the bean temperature. In conclusion, it was shown that sound analysis can be used to determine the proportion of cracked beans.