Wolfram Krause | Goethe-Universität Frankfurt am Main (original) (raw)
Papers by Wolfram Krause
BWK ENERGIE., 2021
Die Installation von Photovoltaik (PV)-Anlagen wird für Hausbesitzerinnen und -besitzer wie auch ... more Die Installation von Photovoltaik (PV)-Anlagen wird für Hausbesitzerinnen und -besitzer wie auch für Unternehmen aufgrund ihrer verbesserten Wirtschaftlichkeit immer attraktiver. Bei der wachsenden Verbreitung von Solarenergie ist es wichtig zu bedenken, dass es sich um komplexe Mini-Kraftwerke handelt. Wolfram Krause, Director of Product Europe bei SolarEdge Technologies, erläutert was dabei zu bedenken ist und welche Möglichkeiten die „SafeDC“-Technologie hier bietet.
Das Förderprogramm E-Energy und seine Partner aus den Modellprojekte sind vom 20.-24.April 2009 v... more Das Förderprogramm E-Energy und seine Partner aus den Modellprojekte sind vom 20.-24.April 2009 vielfach auf der Han no ver Messe vertreten. Auf ver schiedenen Veranstaltungen und Messeständen werden die einzelnen Projektvorhaben vorgestellt und die aktuellen Entwicklungen präsentiert. "E-Energy-IKT-basiertes Energiesystem der Zukunft" ist ein vom Bundesministerium für Wirtschaft und Technologie (BMWi) initiierter neuer Förderschwerpunkt im Rahmen der Technologiepolitik der Bundesregierung. Das BMWi unterstützt in Zusammenarbeit mit dem in ressortübergreifender Zusammenarbeit mit dem Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit (BMU) Forschungs-und Entwicklungsaktivitäten in sechs Technologiepartnerschaften mit insgesamt rund 60 Millionen Euro. Die Partner investieren dafür nochmals weitere rund 80 Millionen Euro, so dass für die E-Energy-Modell projekte insgesamt rund 140 Millionen Euro zur Verfügung stehen. Aufgrund seiner herausragenden innovations-und wirtschaftspolitischen Bedeutung erklärte Bundeskanzlerin Dr. Angela Merkel das Projekt auf dem IT-Gipfel 2008 zum nationalen Leuchtturmprojekt. Weitere Informationen finden Sie unter www.e-energie.info. E-Energy Das IKT-basierte Energiesystem der Zukunft auf der Hannover Messe Montag, 20.April 10.00-11.00 Uhr Energieforum "Life Needs Power" Halle 12/ Stand C06 11.00 Uhr Messestand EWE AG Halle 13 / Stand C30 Dienstag, 21. April 15.00 Uhr Messestand EWE AG Halle 13 / Stand C30 "Erneuerbare Energien: Systemdienstleister oder Gefahr für die Netzstabilität" Podiumsdiskussion mit Prof. Zbigniew A. Styczynski (Uni Magdeburg) und Dr. Kurt Rohrig (ISET) u. a.
Total spectrum of photon emission by an ultra-relativistic positron channelling in a periodically... more Total spectrum of photon emission by an ultra-relativistic positron channelling in a periodically bent crystal. ‡
As a representative of a complex technological system, so-called wireless multihop ad hoc communi... more As a representative of a complex technological system, so-called wireless multihop ad hoc communication networks are discussed. They represent an infrastructure-less generalization of todays wireless cellular phone networks. Lacking a central control authority, the ad hoc nodes have to coordinate themselves such that the overall network performs in an optimal way. A performance indicator is the end-to-end throughput capacity. Various models, generating differing ad hoc network structure via differing transmission power assignments, are constructed and characterized. They serve as input for a generic data traffic simulation as well as some semi-analytic estimations. The latter reveal that due to the most-critical-node effect the end-to-end throughput capacity sensitively depends on the underlying network structure, resulting in differing scaling laws with respect to network size.
Abstract. This paper discusses the undulator radiation emitted by high-energy positrons during pl... more Abstract. This paper discusses the undulator radiation emitted by high-energy positrons during planar channeling in periodically bent crystals. We demonstrate that the construction of the undulator for positrons with energies of 10 GeV and above is only possible if one takes into account the radiative energy losses. The frequency of the undulator radiation depends on the energy of the particle. Thus the decrease of the particle’s energy during the passage of the crystal should result in the destruction of the undulator radiation regime. However, we demonstrate that it is possible to avoid the destructive influence of the radiative losses on the frequency of the undulator radiation by the appropriate variation of the shape of the crystal channels. We also discuss a method by which, to our mind, it would be possible to prepare the crystal with the desired properties of its channels.
Load balancing in electricity grids becomes a more sophisticated problem by the increased availab... more Load balancing in electricity grids becomes a more sophisticated problem by the increased availability of time-varying stochastic availability of electricity from renewable resources. Demand side management by load shifting is one attempt to cope with this problem. In this paper we discus and compare two control strategies to use the thermal storage of electrical household appliances as balancing power. For this objective we analyze a simulation model of 5000 controllable refrigerators with respect to the ability to shift their energy demand depending on parameterized external signals. Both control strategies can be used for short term reserves with delivery within 15 minutes of time, but they differ in possible shapes of the resulting load curves and in the reaction time of the controlled system.
Load balancing in electricity grids becomes a more sophisticated problem by the increased availab... more Load balancing in electricity grids becomes a more sophisticated problem by the increased availability of timevarying stochastic availability of electricity from renewable resources. Demand side management by load shifting is one attempt to cope with this problem. In this paper we discus and compare two control strategies to use the thermal storage of electrical household appliances as balancing power. For this objective we analyze a simulation model of 5000 controllable refrigerators with respect to the ability to shift their energy demand depending on parameterized external signals. Both control strategies can be used for short term reserves with delivery within 15 minutes of time, but they differ in possible shapes of the resulting load curves and in the reaction time of the controlled system.
E-Energy, 2009
In meinem Vortrag möchte ich Ihnen heute das E-Energy Projekt eTelligence vorstellen. Meine Vorre... more In meinem Vortrag möchte ich Ihnen heute das E-Energy Projekt eTelligence vorstellen. Meine Vorredner haben sehr schön die Notwendigkeit dargelegt, warum wir Innovationen für unser Stromnetz, für ein modernes Stromnetz brauchen, ob das die Versorgungssicherheit, ob das die erneuerbaren Energien sind. Es gibt vielfältige Gründe, dass wir unser monochromatisches Energieversorgungssystem überdenken müssen, und mit eTelligence wollen wir einige der Ideen, die bei der EWE seit vielen Jahren entwickelt werden, weiterbringen. Wir haben uns mit sehr leistungsfähigen Partner, die zum Teil hier vertreten sind, zusammengetan und wollen diese Ideen im Rahmen des Projektes „eTelligence“ in einem Feldtest umsetzen, den Nutzen demonstrieren und damit genau wie von Herrn Scott angesprochen einige dieser Schritte tun, nämlich das akademische Wissen demonstrieren, als Feldtest umsetzen und Erfahrungen sammeln.
Lecture Notes in Computer Science, 2005
Wireless multihop ad hoc communication networks represent an infrastructure-less generalization o... more Wireless multihop ad hoc communication networks represent an infrastructure-less generalization of todays cellular networks. Since a central control authority is missing, the complex network has to self-⋆ itself for various operating tasks. Key to a self-⋆ realization is the design of simple, yet robust distributive control rules, which allow the overall network to perform well. Two examples from topology control are given. The first one addresses the connectivity issue, where a self-⋆ rule is presented and shown to lead to strong network connectivity almost surely. A generic system analysis is used in the second example to first develop a phenomenological description of the network’s end-to-end throughput capacity and then to sketch further steps towards a self-⋆ rule for obtaining a large throughput performance.
We discuss radiation generated by positrons channeling in a crystalline undulator. The undulator ... more We discuss radiation generated by positrons channeling in a crystalline undulator. The undulator is produced by periodically bending a single crystal with an amplitude much larger than the interplanar spacing. Different approaches for bending the crystal are described and the restrictions on the parameters of the bending are established. We present the results of numeric calculations of the spectral distributions of the spontaneous emitted radiation and estimate the conditions for stimulated emission. Our investigations show that the proposed mechanism provides an efficient source for high energy photons, which is worth to be studied experimentally.
It is not only biology, chemistry and physics, which are addressing selfor- ganization as the key... more It is not only biology, chemistry and physics, which are addressing selfor- ganization as the key design principle of nature, but also the engineering, computer and social sciences. As an example for the selforganizing control of complex tech- nical systems we pick so-called wireless multi-hop ad hoc communication networks, which represent an infrastructureless generalization of today's wireless cellular phone networks. Lacking a central control authority, the ad hoc nodes have to process data trafc and information o ws by themselves and to decide on distributive, local control actions in such a way that the overall, global network performs in an optimal way. One important global issue is strong network connectivity, which allows each node to be able to communicate to each other node via a multi-hop route. A simple distributed protocol, guaranteeing this almost surely, is constructed by referring to continuum percolation and mutations thereof. Another important issue for the ove...
Physica A: Statistical Mechanics and its Applications, 2008
Clever assignments of link weights are able to change communication routes in such a way that loa... more Clever assignments of link weights are able to change communication routes in such a way that loads are distributed almost evenly across a network. This is achieved by weight assignments based on the link load. As demonstrated for scale-free as well as synthetic Internet networks, they decorrelate the loads of the nodes and links from the network structure and increase the transport capacity of the network. For various Internet scans the increase of transport capacity amounts to a factor of around five when compared to shortest-path routing.
This paper discusses the undulator radiation emitted by high-energy positrons during planar chann... more This paper discusses the undulator radiation emitted by high-energy positrons during planar channeling in periodically bent crystals. We demonstrate that the construction of the undulator for positrons with energies of 10 GeV and above is only possible if one takes into account the radiative energy losses. The frequency of the undulator radiation depends on the energy of the particle. Thus the decrease of the particle's energy during the passage of the crystal should result in the destruction of the undulator radiation regime. However, we demonstrate that it is possible to avoid the destructive influence of the radiative losses on the frequency of the undulator radiation by the appropriate variation of the shape of the crystal channels. We also discuss a method by which, to our mind, it would be possible to prepare the crystal with the desired properties of its channels.
Physica A: Statistical Mechanics and its Applications, 2004
Due to their inherent complexity, engineered wireless multihop ad hoc communication networks repr... more Due to their inherent complexity, engineered wireless multihop ad hoc communication networks represent a technological challenge. Having no mastering infrastructure the nodes have to selforganize themselves in such a way that for example network connectivity, good data traffic performance and robustness are guaranteed. In this contribution the focus is on routing & congestion control. First, random data traffic along shortest path routes is studied by simulations as well as theoretical modeling. Measures of congestion like end-to-end time delay and relaxation times are given. A scaling law of the average time delay with respect to network size is revealed and found to depend on the underlying network topology. In the second step, a distributive routing & congestion control is proposed. Each node locally propagates its routing cost estimates and information about its congestion state to its neighbors, which then update their respective cost estimates. This allows for a flexible adaptation of end-to-end routes to the overall congestion state of the network. Compared to shortest-path routing, the critical network load is significantly increased.
Physica A: Statistical Mechanics and its Applications, 2004
As a representative of a complex technological system, so-called wireless multihop ad hoc communi... more As a representative of a complex technological system, so-called wireless multihop ad hoc communication networks are discussed. They represent an infrastructure-less generalization of todays wireless cellular phone networks. Lacking a central control authority, the ad hoc nodes have to coordinate themselves such that the overall network performs in an optimal way. A performance indicator is the end-to-end throughput capacity. Various models, generating differing ad hoc network structure via differing transmission power assignments, are constructed and characterized. They serve as input for a generic data traffic simulation as well as some semi-analytic estimations. The latter reveal that due to the most-critical-node effect the end-toend throughput capacity sensitively depends on the underlying network structure, resulting in differing scaling laws with respect to network size.
BWK ENERGIE., 2021
Die Installation von Photovoltaik (PV)-Anlagen wird für Hausbesitzerinnen und -besitzer wie auch ... more Die Installation von Photovoltaik (PV)-Anlagen wird für Hausbesitzerinnen und -besitzer wie auch für Unternehmen aufgrund ihrer verbesserten Wirtschaftlichkeit immer attraktiver. Bei der wachsenden Verbreitung von Solarenergie ist es wichtig zu bedenken, dass es sich um komplexe Mini-Kraftwerke handelt. Wolfram Krause, Director of Product Europe bei SolarEdge Technologies, erläutert was dabei zu bedenken ist und welche Möglichkeiten die „SafeDC“-Technologie hier bietet.
Das Förderprogramm E-Energy und seine Partner aus den Modellprojekte sind vom 20.-24.April 2009 v... more Das Förderprogramm E-Energy und seine Partner aus den Modellprojekte sind vom 20.-24.April 2009 vielfach auf der Han no ver Messe vertreten. Auf ver schiedenen Veranstaltungen und Messeständen werden die einzelnen Projektvorhaben vorgestellt und die aktuellen Entwicklungen präsentiert. "E-Energy-IKT-basiertes Energiesystem der Zukunft" ist ein vom Bundesministerium für Wirtschaft und Technologie (BMWi) initiierter neuer Förderschwerpunkt im Rahmen der Technologiepolitik der Bundesregierung. Das BMWi unterstützt in Zusammenarbeit mit dem in ressortübergreifender Zusammenarbeit mit dem Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit (BMU) Forschungs-und Entwicklungsaktivitäten in sechs Technologiepartnerschaften mit insgesamt rund 60 Millionen Euro. Die Partner investieren dafür nochmals weitere rund 80 Millionen Euro, so dass für die E-Energy-Modell projekte insgesamt rund 140 Millionen Euro zur Verfügung stehen. Aufgrund seiner herausragenden innovations-und wirtschaftspolitischen Bedeutung erklärte Bundeskanzlerin Dr. Angela Merkel das Projekt auf dem IT-Gipfel 2008 zum nationalen Leuchtturmprojekt. Weitere Informationen finden Sie unter www.e-energie.info. E-Energy Das IKT-basierte Energiesystem der Zukunft auf der Hannover Messe Montag, 20.April 10.00-11.00 Uhr Energieforum "Life Needs Power" Halle 12/ Stand C06 11.00 Uhr Messestand EWE AG Halle 13 / Stand C30 Dienstag, 21. April 15.00 Uhr Messestand EWE AG Halle 13 / Stand C30 "Erneuerbare Energien: Systemdienstleister oder Gefahr für die Netzstabilität" Podiumsdiskussion mit Prof. Zbigniew A. Styczynski (Uni Magdeburg) und Dr. Kurt Rohrig (ISET) u. a.
Total spectrum of photon emission by an ultra-relativistic positron channelling in a periodically... more Total spectrum of photon emission by an ultra-relativistic positron channelling in a periodically bent crystal. ‡
As a representative of a complex technological system, so-called wireless multihop ad hoc communi... more As a representative of a complex technological system, so-called wireless multihop ad hoc communication networks are discussed. They represent an infrastructure-less generalization of todays wireless cellular phone networks. Lacking a central control authority, the ad hoc nodes have to coordinate themselves such that the overall network performs in an optimal way. A performance indicator is the end-to-end throughput capacity. Various models, generating differing ad hoc network structure via differing transmission power assignments, are constructed and characterized. They serve as input for a generic data traffic simulation as well as some semi-analytic estimations. The latter reveal that due to the most-critical-node effect the end-to-end throughput capacity sensitively depends on the underlying network structure, resulting in differing scaling laws with respect to network size.
Abstract. This paper discusses the undulator radiation emitted by high-energy positrons during pl... more Abstract. This paper discusses the undulator radiation emitted by high-energy positrons during planar channeling in periodically bent crystals. We demonstrate that the construction of the undulator for positrons with energies of 10 GeV and above is only possible if one takes into account the radiative energy losses. The frequency of the undulator radiation depends on the energy of the particle. Thus the decrease of the particle’s energy during the passage of the crystal should result in the destruction of the undulator radiation regime. However, we demonstrate that it is possible to avoid the destructive influence of the radiative losses on the frequency of the undulator radiation by the appropriate variation of the shape of the crystal channels. We also discuss a method by which, to our mind, it would be possible to prepare the crystal with the desired properties of its channels.
Load balancing in electricity grids becomes a more sophisticated problem by the increased availab... more Load balancing in electricity grids becomes a more sophisticated problem by the increased availability of time-varying stochastic availability of electricity from renewable resources. Demand side management by load shifting is one attempt to cope with this problem. In this paper we discus and compare two control strategies to use the thermal storage of electrical household appliances as balancing power. For this objective we analyze a simulation model of 5000 controllable refrigerators with respect to the ability to shift their energy demand depending on parameterized external signals. Both control strategies can be used for short term reserves with delivery within 15 minutes of time, but they differ in possible shapes of the resulting load curves and in the reaction time of the controlled system.
Load balancing in electricity grids becomes a more sophisticated problem by the increased availab... more Load balancing in electricity grids becomes a more sophisticated problem by the increased availability of timevarying stochastic availability of electricity from renewable resources. Demand side management by load shifting is one attempt to cope with this problem. In this paper we discus and compare two control strategies to use the thermal storage of electrical household appliances as balancing power. For this objective we analyze a simulation model of 5000 controllable refrigerators with respect to the ability to shift their energy demand depending on parameterized external signals. Both control strategies can be used for short term reserves with delivery within 15 minutes of time, but they differ in possible shapes of the resulting load curves and in the reaction time of the controlled system.
E-Energy, 2009
In meinem Vortrag möchte ich Ihnen heute das E-Energy Projekt eTelligence vorstellen. Meine Vorre... more In meinem Vortrag möchte ich Ihnen heute das E-Energy Projekt eTelligence vorstellen. Meine Vorredner haben sehr schön die Notwendigkeit dargelegt, warum wir Innovationen für unser Stromnetz, für ein modernes Stromnetz brauchen, ob das die Versorgungssicherheit, ob das die erneuerbaren Energien sind. Es gibt vielfältige Gründe, dass wir unser monochromatisches Energieversorgungssystem überdenken müssen, und mit eTelligence wollen wir einige der Ideen, die bei der EWE seit vielen Jahren entwickelt werden, weiterbringen. Wir haben uns mit sehr leistungsfähigen Partner, die zum Teil hier vertreten sind, zusammengetan und wollen diese Ideen im Rahmen des Projektes „eTelligence“ in einem Feldtest umsetzen, den Nutzen demonstrieren und damit genau wie von Herrn Scott angesprochen einige dieser Schritte tun, nämlich das akademische Wissen demonstrieren, als Feldtest umsetzen und Erfahrungen sammeln.
Lecture Notes in Computer Science, 2005
Wireless multihop ad hoc communication networks represent an infrastructure-less generalization o... more Wireless multihop ad hoc communication networks represent an infrastructure-less generalization of todays cellular networks. Since a central control authority is missing, the complex network has to self-⋆ itself for various operating tasks. Key to a self-⋆ realization is the design of simple, yet robust distributive control rules, which allow the overall network to perform well. Two examples from topology control are given. The first one addresses the connectivity issue, where a self-⋆ rule is presented and shown to lead to strong network connectivity almost surely. A generic system analysis is used in the second example to first develop a phenomenological description of the network’s end-to-end throughput capacity and then to sketch further steps towards a self-⋆ rule for obtaining a large throughput performance.
We discuss radiation generated by positrons channeling in a crystalline undulator. The undulator ... more We discuss radiation generated by positrons channeling in a crystalline undulator. The undulator is produced by periodically bending a single crystal with an amplitude much larger than the interplanar spacing. Different approaches for bending the crystal are described and the restrictions on the parameters of the bending are established. We present the results of numeric calculations of the spectral distributions of the spontaneous emitted radiation and estimate the conditions for stimulated emission. Our investigations show that the proposed mechanism provides an efficient source for high energy photons, which is worth to be studied experimentally.
It is not only biology, chemistry and physics, which are addressing selfor- ganization as the key... more It is not only biology, chemistry and physics, which are addressing selfor- ganization as the key design principle of nature, but also the engineering, computer and social sciences. As an example for the selforganizing control of complex tech- nical systems we pick so-called wireless multi-hop ad hoc communication networks, which represent an infrastructureless generalization of today's wireless cellular phone networks. Lacking a central control authority, the ad hoc nodes have to process data trafc and information o ws by themselves and to decide on distributive, local control actions in such a way that the overall, global network performs in an optimal way. One important global issue is strong network connectivity, which allows each node to be able to communicate to each other node via a multi-hop route. A simple distributed protocol, guaranteeing this almost surely, is constructed by referring to continuum percolation and mutations thereof. Another important issue for the ove...
Physica A: Statistical Mechanics and its Applications, 2008
Clever assignments of link weights are able to change communication routes in such a way that loa... more Clever assignments of link weights are able to change communication routes in such a way that loads are distributed almost evenly across a network. This is achieved by weight assignments based on the link load. As demonstrated for scale-free as well as synthetic Internet networks, they decorrelate the loads of the nodes and links from the network structure and increase the transport capacity of the network. For various Internet scans the increase of transport capacity amounts to a factor of around five when compared to shortest-path routing.
This paper discusses the undulator radiation emitted by high-energy positrons during planar chann... more This paper discusses the undulator radiation emitted by high-energy positrons during planar channeling in periodically bent crystals. We demonstrate that the construction of the undulator for positrons with energies of 10 GeV and above is only possible if one takes into account the radiative energy losses. The frequency of the undulator radiation depends on the energy of the particle. Thus the decrease of the particle's energy during the passage of the crystal should result in the destruction of the undulator radiation regime. However, we demonstrate that it is possible to avoid the destructive influence of the radiative losses on the frequency of the undulator radiation by the appropriate variation of the shape of the crystal channels. We also discuss a method by which, to our mind, it would be possible to prepare the crystal with the desired properties of its channels.
Physica A: Statistical Mechanics and its Applications, 2004
Due to their inherent complexity, engineered wireless multihop ad hoc communication networks repr... more Due to their inherent complexity, engineered wireless multihop ad hoc communication networks represent a technological challenge. Having no mastering infrastructure the nodes have to selforganize themselves in such a way that for example network connectivity, good data traffic performance and robustness are guaranteed. In this contribution the focus is on routing & congestion control. First, random data traffic along shortest path routes is studied by simulations as well as theoretical modeling. Measures of congestion like end-to-end time delay and relaxation times are given. A scaling law of the average time delay with respect to network size is revealed and found to depend on the underlying network topology. In the second step, a distributive routing & congestion control is proposed. Each node locally propagates its routing cost estimates and information about its congestion state to its neighbors, which then update their respective cost estimates. This allows for a flexible adaptation of end-to-end routes to the overall congestion state of the network. Compared to shortest-path routing, the critical network load is significantly increased.
Physica A: Statistical Mechanics and its Applications, 2004
As a representative of a complex technological system, so-called wireless multihop ad hoc communi... more As a representative of a complex technological system, so-called wireless multihop ad hoc communication networks are discussed. They represent an infrastructure-less generalization of todays wireless cellular phone networks. Lacking a central control authority, the ad hoc nodes have to coordinate themselves such that the overall network performs in an optimal way. A performance indicator is the end-to-end throughput capacity. Various models, generating differing ad hoc network structure via differing transmission power assignments, are constructed and characterized. They serve as input for a generic data traffic simulation as well as some semi-analytic estimations. The latter reveal that due to the most-critical-node effect the end-toend throughput capacity sensitively depends on the underlying network structure, resulting in differing scaling laws with respect to network size.