http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Benjamin Maier,Mia Lenling,Hwasung Yeom,Greg Johnson,Stuart Maloy,Kumar Sridharan 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.4
A novel fabrication method of oxide dispersion strengthened (ODS) steel cladding tubes for advanced fastreactors has been investigated using the cold spray powder-based materials deposition process. Coldspraying has the potential advantage for rapidly fabricating ODS cladding tubes in comparison with theconventional multi-step extrusion process. A gas atomized spherical 14YWT (Fe-14%Cr, 3%W, 0.4%Ti, 0.2%Y, 0.01%O) powder was sprayed on a rotating cylindrical 6061-T6 aluminum mandrel using nitrogen asthe propellant gas. The powder lacked the oxygen content needed to precipitate the nanoclusters in ODSsteel, therefore this work was intended to serve as a proof-of-concept study to demonstrate that freestandingsteel cladding tubes with prototypical ODS composition could be manufactured using thecold spray process. The spray process produced an approximately 1-mm thick, dense 14YWT deposit onthe aluminum-alloy tube. After surface polishing of the 14YWT deposit to obtain desired claddingthickness and surface roughness, the aluminum-alloy mandrel was dissolved in an alkaline medium toleave behind a free-standing ODS tube. The as-fabricated cladding tube was annealed at 1000 C for 1 hin an argon atmosphere to improve the overall mechanical properties of the cladding
Assessment of a Low Power Offset BPSK Component for Spreading Code Authentication
Daniel S. Maier,Thomas Pany 사단법인 항법시스템학회 2020 Journal of Positioning, Navigation, and Timing Vol.9 No.2
In this paper a low power Spreading Code Authentication (SCA) sequence with a BPSK(1) modulation at a frequency offset of +7.161 MHz is tested for authentication purposes, the Galileo E1OS is used as base signal. The tested signals comprise a Galileo constellation with 5 satellites including the Galileo OS Navigation Message Authentication (OSNMA) and a low power offset BPSK (OBPSK(7,1)) as SCA component. The signals are generated with the software based MuSNAT-Signal-Generator. The generated signals were transmitted Over-The-Air (OTA) using a Software-Defined-Radio (SDR) as pseudolite. With a real-environment-testbed the performance of the SCA in real channel conditions (fading and multipath) was tested. A new SCA evaluation scheme is proposed and was implemented. Under real channel conditions we derive experimental threshold values for the new SCA evaluation scheme which allow a robust authentication. A Security Code Estimation and Replay (SCER) spoofing attack was mimicked on the real-environment-testbed and analyzed with the SCA evaluation scheme. It was shown that the usage of an OBPSK is feasible as an authentication method and can be used in combination with the OSNMA to improve the authentication robustness against Security SCER attacks.
Variable Aggregation in the ILP Design of WDM Networks with Dedicated Protection
Tornatore, Massimo,Maier, Guido,Pattavina, Achille The Korea Institute of Information and Commucation 2007 Journal of communications and networks Vol.9 No.4
In wavelength-division-multiplexing(WDM) networks a link failure may cause the failure of several high-bit-rate optical channels, thereby leading to large data loss. Recently, various protection and restoration mechanisms have been proposed to efficiently deal with this problem in mesh networks. Among them, dedicated path protection(DPP) is a promising candidate because of its ultra-fast restoration time and robustness. In this work we investigate the issue of planning and optimization of WDM networks with DPP. Integer linear programming(ILP), in particular, is one of the most common exact method to solve the design optimization problem for protected WDM networks. Traditional ILP formalizations to solve this problem rely on the classical flow or route formulation approaches, but both these approaches suffer from a excessively high computational burden. In this paper, we present a variable-aggregation method that has the ability of significantly reducing the complexity of the traditional flow formulation. We compare also the computational burden of flow formulation with variable aggregation both with the classical flow and route formulations. The comparison is carried out by applying the three alternative methods to the optimization of two case-study networks.