The CYCIAE-100 cyclotron developed by the BRIF project group had finished installation of its main equipments and parts in 2012.The field mapping of the main magnet has been done afterward.In Dec.13th,2012,the vacuum of the main chamber reached 4×10-7 mbar,conditioning for the RF resonant cavities were started shortly after.When the cyclotron is opened the interior surface is exposed to air and
Graphene nanosheets possess a promising potential as electrodes in Li-ion batteries （LIBs）; consequently, the development of low-cost and high-productivity synthetic approaches is crudal. Herein, porous grapheneqike nanosheets （PGSs） have been synthesized from expandable graphite （EG） by initially intercalating phosphoric acid, and then performing annealing to enlarge the interlayer distance of EG, thus fadlitating the successive intercalation of zinc chloride. Subsequently, the following pyrolysis of zinc chloride in the EG interlayer promoted the formation of the porous PGS structure; meanwhile, the gas produced during the formation of the porous structure could exfoliate the EG to graphene-like nanosheets. The synthetic PGS material used as LIB anode exhibited superior Li＋ storage performance, showing a remarkable discharge capacity of 830.4 mAh.g-1 at 100 mA.g-1, excellent rate capadty of 211.6 mAh＇g-1 at 20,000 mA-g-1, and excellent cycle performance （near 100% capacity retention after 10,000 cycles）. The excellent rate performance is attributed to the Li＋ ion rapid transport in porous structures and the high electrical conductivity of graphene-like nanosheets. It is expected that PGS may be widely used as anode material for high-rate LIBs via this facile and low-cost route by employing EG as the raw material.
Abstract Physical layer security (PLS) has been proposed to afford an extra layer of security on top of the conventional cryptographic techniques. Unlike the conventional complexity-based cryptographic techniques at the upper layers, physical layer security exploits the characteristics of wireless channels, e.g., fading, noise, interference, etc., to enhance wireless security. It is proved that secure transmission can benefit from fading channels. Accordingly, numerous researchers have explored what fading can offer for physical layer security, especially the investigation of physical layer security over wiretap fading channels. Therefore, this paper aims at reviewing the existing and ongoing research works on this topic. More specifically, we present a classification of research works in terms of the four categories of fading models: (i) small-scale, (ii) large-scale, (iii) composite, and (iv) cascaded. To elaborate these fading models with a generic and flexible tool, three promising candidates, including the mixture gamma (MG), mixture of Gaussian (MoG), and Fox’s H -function distributions, are comprehensively examined and compared. Their advantages and limitations are further demonstrated via security performance metrics, which are designed as vivid indicators to measure how perfect secrecy is ensured. Two clusters of secrecy metrics, namely (i) secrecy outage probability (SOP), and the lower bound of SOP; and (ii) the probability of nonzero secrecy capacity (PNZ), the intercept probability, average secrecy capacity (ASC), and ergodic secrecy capacity, are displayed and, respectively, deployed in passive and active eavesdropping scenarios. Apart from those, revisiting the secrecy enhancement techniques based on Wyner’s wiretap model, the on-off transmission scheme, jamming approach, antenna selection, and security region are discussed.
Honeypot is a recent developed computer security concept which uses active offense to against attacks from hackers. It lures hackers to attack a seemly vulnerable fake network where they could be well observed in order to learn about the tactics and tools used by the attackers, so that we may improve the system security accordingly later. In this paper, we propose a novel approach for redirecting technique in honeypot system. First, we introduce briefly concepts of the honeypot system. Then we describe a redirection technique and an implementation algorithm. Finally, using the IDS Snort and the firewall IPTable, we set up a testing environment and give some simulations results. We also discuss some future research topics.
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