The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
M.l. Sichitiu - One of the best experts on this subject based on the ideXlab platform.
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The Nominal Capacity of wireless mesh networks
IEEE Wireless Communications, 2003Co-Authors: M.l. SichitiuAbstract:Wireless mesh networks are an alternative technology for last-mile broadband Internet access. In WMNs, similar to ad hoc networks, each user node operates not only as a host but also as a router; user packets are forwarded to and from an Internet-connected gateway in multihop fashion. The meshed topology provides good reliability, market coverage, and scalability, as well as low upfront investments. Despite the recent startup surge in WMNs, much research remains to be done before WMNs realize their full potential. This article tackles the problem of determining the exact Capacity of a WMN. The key concept we introduce to enable this calculation is the bottleneck collision domain, defined as the geographical area of the network that bounds from above the amount of data that can be transmitted in the network. We show that for WMNs the throughput of each node decreases as O(1/n), where n is the total number of nodes in the network. In contrast with most existing work on ad hoc network Capacity, we do not limit our study to the asymptotic case. In particular, for a given topology and the set of active nodes, we provide exact upper bounds on the throughput of any node. The calculation can be used to provision the network, to ensure quality of service and fairness. The theoretical results are validated by detailed simulations.
Martin Horn - One of the best experts on this subject based on the ideXlab platform.
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Optimal operation of residential heating systems with logwood boiler, buffer storage and solar thermal collector
Biomass & Bioenergy, 2020Co-Authors: Christopher Zemann, Markus Deutsch, Sandra Zlabinger, Georg Hofmeister, Markus Gölles, Martin HornAbstract:Abstract Modern central heating systems with logwood boilers are comprised of the boiler, a buffer storage and solar thermal collectors. Conventional control strategies for these heating systems do not coordinate the utilization of all components. This can lead to a sub-optimal operation of the entire heating system resulting in a loss of efficiency and increased pollutant emissions. This contribution presents a control strategy which considers all components of the heating system including the user and forecasts for the solar yield and heat demand. It determines and carries out an optimal operating strategy that improves the user utility and maximizes the heating system efficiency while also ensuring a clean and efficient combustion. The control strategy continuously learns the user behavior and instructs the user when to refill the logwood boiler and how much fuel to use. The new control strategy was verified through test runs performed at an experimental setup consisting of a commercially available logwood boiler with a Nominal Capacity of 28 kW , two buffer storages with a Capacity of 1.5 m 3 each and a heating device with a thermal output of up to 12 kW simulating a solar thermal collector. During these test runs, the CO emissions were reduced by 93.6 % in the main combustion phase, 7.1 % more solar yield was utilized, the buffer losses were reduced by − 16.9 % and the overall efficiency was increased by 3.1 % . Thus, the application of this control strategy resulted in a significantly improved user utility and heating system efficiency.
Masabumi Nishikawa - One of the best experts on this subject based on the ideXlab platform.
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Core configuration of a gas-cooled reactor as a tritium production device for fusion reactor
Nuclear Engineering and Design, 2014Co-Authors: Hiroyuki Nakaya, Hideaki Matsuura, Minoru Goto, Shigeaki Nakagawa, Y Nakao, Satoshi Shimakawa, Masabumi NishikawaAbstract:Abstract The performance of a high-temperature gas-cooled reactor as a tritium production device is examined, assuming the compound LiAlO2 as the tritium-producing material. A gas turbine high-temperature reactor of 300 MWe Nominal Capacity (GTHTR300) is assumed as the calculation target, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations are carried out. To load sufficient Li into the core, LiAlO2 is loaded into the removable reflectors that surround the ring-shaped fuel blocks in addition to the burnable poison insertion holes. It is shown that module high-temperature gas-cooled reactors with a total thermal output power of 3 GW can produce almost 8 kg of tritium in a year.
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evaluation of tritium production rate in a gas cooled reactor with continuous tritium recovery system for fusion reactors
Fusion Engineering and Design, 2013Co-Authors: Hideaki Matsuura, Minoru Goto, Shigeaki Nakagawa, Hiroyuki Nakaya, Y Nakao, Satoshi Shimakawa, Masabumi NishikawaAbstract:Abstract The performance of a high-temperature gas-cooled reactor as a tritium production with continuous tritium recovery system is examined. A gas turbine high-temperature reactor of 300-MWe (600 MW) Nominal Capacity (GTHTR300) is assumed as the calculation target, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations for the three-dimensional entire-core region of the GTHTR300 were performed. A Li loading pattern for the continuous tritium recovery system in the gas-cooled reactor is presented. It is shown that module gas-cooled reactors with a total thermal output power of 3 GW in all can produce ∼6 kg of tritium maximum in a year.
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performance of high temperature gas cooled reactor as a tritium production device for fusion reactors
Nuclear Engineering and Design, 2012Co-Authors: Hideaki Matsuura, Minoru Goto, Shigeaki Nakagawa, S Kouchi, Hiroyuki Nakaya, T Yasumoto, Y Nakao, Satoshi Shimakawa, Masabumi NishikawaAbstract:Abstract The performance of a high-temperature gas-cooled reactor as a tritium production device is examined. A gas turbine high-temperature reactor of 300 MWe Nominal Capacity (GTHTR300) is assumed as the calculation target of a typical gas-cooled reactor, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations for the 3-dimensional entire-core region of GTHTR300 were carried out considering its unique double heterogeneity structure. It is shown that gas-cooled reactors with thermal output power of 3 GW in all can produce 5–8 kg of tritium in a year.
Hideaki Matsuura - One of the best experts on this subject based on the ideXlab platform.
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the t containment properties of a zr containing li rod in a high temperature gas cooled reactor as a t production device for fusion reactors
Fusion Engineering and Design, 2021Co-Authors: Hideaki Matsuura, Takuro Suganuma, Yuki Koga, Motomasa Naoi, Kazunari Katayama, T Otsuka, Minoru Goto, Shigeaki Nakagawa, Shinpei Hamamoto, Etsuo IshitsukaAbstract:Abstract The production of tritium (T) using high-temperature gas-cooled reactors (HTGRs) has been studied for a prior engineering research with T handling and initial T possession in demonstration fusion reactors. Stable containment of T in Li-loading rods during HTGR operation is a critical issue. This study investigates this for an irradiation test to examine T-containment performance in Li-loading rods and develops an analytical model of evaluating the amount of T outflow to a He coolant. The hydrogen absorption characteristics, including the deterioration of the hydrogen absorption speed after Zr has sufficiently absorbed the hydrogen, is experimentally measured assuming an HTGR setting. We present an analytical model of evaluating the T outflow from a Li rod and, on the basis of this model, estimate the total T outflow, assuming the presence of a gas-turbine high-temperature reactor of 300 MWe with a Nominal Capacity and a high-temperature engineering test reactor. It is demonstrated that, by loading a sufficient amount of Zr into the Li rod, the T outflow can be suppressed to less than a small percent of the total T produced during 360 days of reactor operation.
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study on a method for loading a li compound to produce tritium using high temperature gas cooled reactor
Nuclear Engineering and Design, 2015Co-Authors: Hiroyuki Nakaya, Hideaki Matsuura, Kazunari Katayama, Minoru Goto, Shigeaki NakagawaAbstract:Abstract Tritium production using high-temperature gas-cooled reactors and its outflow from the region loading Li compound into the helium coolant are estimated when considering the suppression of tritium outflow. A Li rod containing a cylindrical Li compound placed in an Al 2 O 3 cladding tube is assumed as a method for loading Li compound. A gas turbine high-temperature reactor of 300 MW electrical Nominal Capacity (GTHTR300) with 600 MW thermal output power is considered and modeled using the continuous-energy Monte Carlo transport code MVP-BURN, where burn-up simulations are carried out. Tritium outflow is estimated from equilibrium solution for the tritium diffusion equation in the cladding tube. A GTHTR300 can produce 400–600 g of tritium over a 180-day operation using the chosen method of loading the Li compound while minimizing tritium outflow from the cladding tube. Optimizing tritium production while suppressing tritium outflow is discussed.
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Core configuration of a gas-cooled reactor as a tritium production device for fusion reactor
Nuclear Engineering and Design, 2014Co-Authors: Hiroyuki Nakaya, Hideaki Matsuura, Minoru Goto, Shigeaki Nakagawa, Y Nakao, Satoshi Shimakawa, Masabumi NishikawaAbstract:Abstract The performance of a high-temperature gas-cooled reactor as a tritium production device is examined, assuming the compound LiAlO2 as the tritium-producing material. A gas turbine high-temperature reactor of 300 MWe Nominal Capacity (GTHTR300) is assumed as the calculation target, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations are carried out. To load sufficient Li into the core, LiAlO2 is loaded into the removable reflectors that surround the ring-shaped fuel blocks in addition to the burnable poison insertion holes. It is shown that module high-temperature gas-cooled reactors with a total thermal output power of 3 GW can produce almost 8 kg of tritium in a year.
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evaluation of tritium production rate in a gas cooled reactor with continuous tritium recovery system for fusion reactors
Fusion Engineering and Design, 2013Co-Authors: Hideaki Matsuura, Minoru Goto, Shigeaki Nakagawa, Hiroyuki Nakaya, Y Nakao, Satoshi Shimakawa, Masabumi NishikawaAbstract:Abstract The performance of a high-temperature gas-cooled reactor as a tritium production with continuous tritium recovery system is examined. A gas turbine high-temperature reactor of 300-MWe (600 MW) Nominal Capacity (GTHTR300) is assumed as the calculation target, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations for the three-dimensional entire-core region of the GTHTR300 were performed. A Li loading pattern for the continuous tritium recovery system in the gas-cooled reactor is presented. It is shown that module gas-cooled reactors with a total thermal output power of 3 GW in all can produce ∼6 kg of tritium maximum in a year.
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performance of high temperature gas cooled reactor as a tritium production device for fusion reactors
Nuclear Engineering and Design, 2012Co-Authors: Hideaki Matsuura, Minoru Goto, Shigeaki Nakagawa, S Kouchi, Hiroyuki Nakaya, T Yasumoto, Y Nakao, Satoshi Shimakawa, Masabumi NishikawaAbstract:Abstract The performance of a high-temperature gas-cooled reactor as a tritium production device is examined. A gas turbine high-temperature reactor of 300 MWe Nominal Capacity (GTHTR300) is assumed as the calculation target of a typical gas-cooled reactor, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations for the 3-dimensional entire-core region of GTHTR300 were carried out considering its unique double heterogeneity structure. It is shown that gas-cooled reactors with thermal output power of 3 GW in all can produce 5–8 kg of tritium in a year.
Shigeaki Nakagawa - One of the best experts on this subject based on the ideXlab platform.
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the t containment properties of a zr containing li rod in a high temperature gas cooled reactor as a t production device for fusion reactors
Fusion Engineering and Design, 2021Co-Authors: Hideaki Matsuura, Takuro Suganuma, Yuki Koga, Motomasa Naoi, Kazunari Katayama, T Otsuka, Minoru Goto, Shigeaki Nakagawa, Shinpei Hamamoto, Etsuo IshitsukaAbstract:Abstract The production of tritium (T) using high-temperature gas-cooled reactors (HTGRs) has been studied for a prior engineering research with T handling and initial T possession in demonstration fusion reactors. Stable containment of T in Li-loading rods during HTGR operation is a critical issue. This study investigates this for an irradiation test to examine T-containment performance in Li-loading rods and develops an analytical model of evaluating the amount of T outflow to a He coolant. The hydrogen absorption characteristics, including the deterioration of the hydrogen absorption speed after Zr has sufficiently absorbed the hydrogen, is experimentally measured assuming an HTGR setting. We present an analytical model of evaluating the T outflow from a Li rod and, on the basis of this model, estimate the total T outflow, assuming the presence of a gas-turbine high-temperature reactor of 300 MWe with a Nominal Capacity and a high-temperature engineering test reactor. It is demonstrated that, by loading a sufficient amount of Zr into the Li rod, the T outflow can be suppressed to less than a small percent of the total T produced during 360 days of reactor operation.
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study on a method for loading a li compound to produce tritium using high temperature gas cooled reactor
Nuclear Engineering and Design, 2015Co-Authors: Hiroyuki Nakaya, Hideaki Matsuura, Kazunari Katayama, Minoru Goto, Shigeaki NakagawaAbstract:Abstract Tritium production using high-temperature gas-cooled reactors and its outflow from the region loading Li compound into the helium coolant are estimated when considering the suppression of tritium outflow. A Li rod containing a cylindrical Li compound placed in an Al 2 O 3 cladding tube is assumed as a method for loading Li compound. A gas turbine high-temperature reactor of 300 MW electrical Nominal Capacity (GTHTR300) with 600 MW thermal output power is considered and modeled using the continuous-energy Monte Carlo transport code MVP-BURN, where burn-up simulations are carried out. Tritium outflow is estimated from equilibrium solution for the tritium diffusion equation in the cladding tube. A GTHTR300 can produce 400–600 g of tritium over a 180-day operation using the chosen method of loading the Li compound while minimizing tritium outflow from the cladding tube. Optimizing tritium production while suppressing tritium outflow is discussed.
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Core configuration of a gas-cooled reactor as a tritium production device for fusion reactor
Nuclear Engineering and Design, 2014Co-Authors: Hiroyuki Nakaya, Hideaki Matsuura, Minoru Goto, Shigeaki Nakagawa, Y Nakao, Satoshi Shimakawa, Masabumi NishikawaAbstract:Abstract The performance of a high-temperature gas-cooled reactor as a tritium production device is examined, assuming the compound LiAlO2 as the tritium-producing material. A gas turbine high-temperature reactor of 300 MWe Nominal Capacity (GTHTR300) is assumed as the calculation target, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations are carried out. To load sufficient Li into the core, LiAlO2 is loaded into the removable reflectors that surround the ring-shaped fuel blocks in addition to the burnable poison insertion holes. It is shown that module high-temperature gas-cooled reactors with a total thermal output power of 3 GW can produce almost 8 kg of tritium in a year.
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evaluation of tritium production rate in a gas cooled reactor with continuous tritium recovery system for fusion reactors
Fusion Engineering and Design, 2013Co-Authors: Hideaki Matsuura, Minoru Goto, Shigeaki Nakagawa, Hiroyuki Nakaya, Y Nakao, Satoshi Shimakawa, Masabumi NishikawaAbstract:Abstract The performance of a high-temperature gas-cooled reactor as a tritium production with continuous tritium recovery system is examined. A gas turbine high-temperature reactor of 300-MWe (600 MW) Nominal Capacity (GTHTR300) is assumed as the calculation target, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations for the three-dimensional entire-core region of the GTHTR300 were performed. A Li loading pattern for the continuous tritium recovery system in the gas-cooled reactor is presented. It is shown that module gas-cooled reactors with a total thermal output power of 3 GW in all can produce ∼6 kg of tritium maximum in a year.
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performance of high temperature gas cooled reactor as a tritium production device for fusion reactors
Nuclear Engineering and Design, 2012Co-Authors: Hideaki Matsuura, Minoru Goto, Shigeaki Nakagawa, S Kouchi, Hiroyuki Nakaya, T Yasumoto, Y Nakao, Satoshi Shimakawa, Masabumi NishikawaAbstract:Abstract The performance of a high-temperature gas-cooled reactor as a tritium production device is examined. A gas turbine high-temperature reactor of 300 MWe Nominal Capacity (GTHTR300) is assumed as the calculation target of a typical gas-cooled reactor, and using the continuous-energy Monte Carlo transport code MVP-BURN, burn-up simulations for the 3-dimensional entire-core region of GTHTR300 were carried out considering its unique double heterogeneity structure. It is shown that gas-cooled reactors with thermal output power of 3 GW in all can produce 5–8 kg of tritium in a year.