216 research outputs found
Physics and engineering studies on the MITICA accelerator: comparison among possible design solutions
No full textConsorzio RFX in Padova is currently using a comprehensive set of numerical and analytical codes, for the physics and engineering design of the SPIDER (Source for Production of Ion of Deuterium Extracted from RF plasma) and MITICA (Megavolt ITER Injector Concept Advancement) experiments, planned to be built at Consorzio RFX.
This paper presents a set of studies on different possible geometries for the MITICA accelerator, with the objective to compare different design concepts and choose the most suitable one (or ones) to be further developed and possibly adopted in the experiment. Different design solutions have been discussed and compared, taking into account their advantages and drawbacks by both the physics and engineering points of view
Sensitivity Analysis of the Off-Normal Conditions of the SPIDER Accelerator
No full textIn the context of the development of the 1 MV neutral beam injector for the ITER tokamak [1], the study on beam formation and acceleration has considerable importance. This effort includes the ion source and accelerator SPIDER (Source for Production of Ions of Deuterium Extracted from an Rf plasma) ion source, planned to be built in Padova, and designed to extract and accelerate a 355 A/m2 current of H- (or 285 A/m2 D-) up to 100 kV [2][3]. Exhaustive simulations were already carried out during the accelerator optimization leading to the present design [4]. However, as it is expected that the accelerator shall operate also in case of pre-programmed or undesired off-normal conditions, the investigation of a large set of off-normal scenarios is necessary. These analyses will also be useful for the evaluation of the real performances of the machine, and should help in interpreting experimental results, or in identifying dangerous operating conditions.
The present contribution offers an overview of the results obtained during the investigation of these off-normal conditions, by means of different modeling tools and codes. The results, showed a good flexibility of the device in different operating conditions. Where the consequences of the abnormalities appeared to be problematic further analysis were addressed
Modeling activities on the negative-ion-based Neutral Beam Injectors of the Large Helical Device
No full textAt the National Institute for Fusion Science (NIFS) large-scaled negative ion sources
have been widely used for the Neutral Beam Injectors (NBIs) mounted on the Large Helical Device
(LHD), which is the world-largest superconducting helical system. These injectors have achieved
outstanding performances in terms of beam energy, negative-ion current and optics, and represent a
reference for the development of heating and current drive NBIs for ITER.
In the framework of the support activities for the ITER NBIs, the PRIMA test facility, which
includes a RF-drive ion source with 100 keV accelerator (SPIDER) and a complete 1 MeV Neutral
Beam system (MITICA) is under construction at Consorzio RFX in Padova.
An experimental validation of the codes has been undertaken in order to prove the accuracy of the
simulations and the soundness of the SPIDER and MITICA design. To this purpose, the whole set
of codes have been applied to the LHD NBIs in a joint activity between Consorzio RFX and NIFS,
with the goal of comparing and benchmarking the codes with the experimental data. A description
of these modeling activities and a discussion of the main results obtained are reported in this pape
Development of a Yodogawa River Distributed Rainfall-Runoff/Flood Inundation Simulation Model and its Application to Flood Insurance
No full text本研究では広域で降雨流出過程と内水・外水氾濫過程を統一的に追跡可能な分布型降雨流出・洪水氾濫追跡モデルを構築する。本稿では特に淀川流域(流域面積8240km2)を対象とした。本稿のモデルは従来の広域モデルに比較すると, 高解像(250m)で流出・浸水過程を統一的かつシームレスに計算できる利点がある。モデルの基礎データは, 国土数値情報の各種データを用いており, 行政モデルともできる限り対応可能となるように配慮した。本モデルは, GISをデータ整備の基本ツールとし, 座標系を適切に設定することにより, 気象・気候モデル, 避難モデル, 脆弱性・経済損害評価モデルとのインターフェースが構築できるようにしており, 洪水による経済損害・保険損害, あるいはその気候変動影響を確率論的に評価することを目的とする。The development of a large-scale distributed rainfall-runoff/flood inundation simulation model is dealt with in this paper. The distributed model can simulate the rainfall-runoff, dike-break and inland flood inundation process simultaneously in a seamless and integrated manner. The model is applied to the Yodogawa river catchment (catchment area 8240 km2). Many of the necessary basic information for the model development are obtained from the Digital National Land Information of the Ministry of the Land, Infrastructure, Transport and Tourisms. This is the intention that the new model is compatible with the river administrator's model. The data process is carried out with GIS so that the coordinate system of the model is appropriately set up which can have the interface with other models such as weather, climate, evacuation, vulnerability and financial models. With such models, the model in this study is able to estimate economic and insurance losses caused by flood and the impact due to climate change.本研究では広域で降雨流出過程と内水・外水氾濫過程を統一的に追跡可能な分布型降雨流出・洪水氾濫追跡モデルを構築する。本稿では特に淀川流域(流域面積8240km2)を対象とした。本稿のモデルは従来の広域モデルに比較すると, 高解像(250m)で流出・浸水過程を統一的かつシームレスに計算できる利点がある。モデルの基礎データは, 国土数値情報の各種データを用いており, 行政モデルともできる限り対応可能となるように配慮した。本モデルは, GISをデータ整備の基本ツールとし, 座標系を適切に設定することにより, 気象・気候モデル, 避難モデル, 脆弱性・経済損害評価モデルとのインターフェースが構築できるようにしており, 洪水による経済損害・保険損害, あるいはその気候変動影響を確率論的に評価することを目的とする。The development of a large-scale distributed rainfall-runoff/flood inundation simulation model is dealt with in this paper. The distributed model can simulate the rainfall-runoff, dike-break and inland flood inundation process simultaneously in a seamless and integrated manner. The model is applied to the Yodogawa river catchment (catchment area 8240 km2). Many of the necessary basic information for the model development are obtained from the Digital National Land Information of the Ministry of the Land, Infrastructure, Transport and Tourisms. This is the intention that the new model is compatible with the river administrator's model. The data process is carried out with GIS so that the coordinate system of the model is appropriately set up which can have the interface with other models such as weather, climate, evacuation, vulnerability and financial models. With such models, the model in this study is able to estimate economic and insurance losses caused by flood and the impact due to climate change
Malicious DNS Tunnel Tool Recognition using Persistent DoH Traffic Analysis
No full textDNS over HTTPS (DoH) protocol can mitigate the risk of privacy breaches but makes it difficult to control network security services due to the DNS traffic encryption. However, since malicious DNS tunnel tools for the DoH protocol pose network security threats, network administrators need to recognize malicious communications even after the DNS traffic encryption has become widespread. In this paper, we propose a malicious DNS tunnel tool recognition system using persistent DoH traffic analysis based on machine learning. The proposed system can accomplish continuous knowledge updates for emerging malicious DNS tunnel tools on the machine learning model. The system is based on hierarchical machine learning classification and focuses on DoH traffic analysis. The evaluation results confirm that the proposed system is able to recognize the six malicious DNS tunnel tools in total, not only well-known ones, including dns2tcp, dnscat2, and iodine, but also the emerging ones such as dnstt, tcp-over-dns, and tuns with 98.02% classification accuracy.Published in: IEEE Transactions on Network and Service Management (Volume:20, Issue:2, June 2023
Powder Metallurgy
No full textFrom high-performance, economical and environmental points of view, Powder metallurgy process shows remarkable advantages in production of parts and components due to their special compositions by elemental mixing and 3-dimensional near net shape forming methods. Powder metallurgy process can be applied to not only metal materials but also ceramics and organic materials, which both are employed as structural and electrical products. Author contributions to Powder metallurgy present excellent and significantly important research topics to evaluate various properties and performance of P/M materials for applying these materials as actual components. In particular, the life estimation of P/M ferrous materials by sliding contact fatigue test and tribological performance evaluation of P/M semi-metallic materials are focused and introduced in this book
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