• Title/Summary/Keyword: Hefei

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Lightweight Intrusion Detection of Rootkit with VMI-Based Driver Separation Mechanism

  • Cui, Chaoyuan;Wu, Yun;Li, Yonggang;Sun, Bingyu
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.3
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    • pp.1722-1741
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    • 2017
  • Intrusion detection techniques based on virtual machine introspection (VMI) provide high temper-resistance in comparison with traditional in-host anti-virus tools. However, the presence of semantic gap also leads to the performance and compatibility problems. In order to map raw bits of hardware to meaningful information of virtual machine, detailed knowledge of different guest OS is required. In this work, we present VDSM, a lightweight and general approach based on driver separation mechanism: divide semantic view reconstruction into online driver of view generation and offline driver of semantics extraction. We have developed a prototype of VDSM and used it to do intrusion detection on 13 operation systems. The evaluation results show VDSM is effective and practical with a small performance overhead.

Comparative Genomics Uncovers the Genetic Diversity and Synthetic Biology of Secondary Metabolite Production of Trametes

  • Zhang, Yan;Wang, Jingjing;Yajun, Chen;Zhou, Minghui;Wang, Wei;Geng, Ming;Xu, Decong;Xu, Zhongdong
    • Mycobiology
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    • v.48 no.2
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    • pp.104-114
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    • 2020
  • The carbohydrate-active enzyme (CAZyme) genes of Trametes contribute to polysaccharide degradation. However, the comprehensive analysis of the composition of CAZymes and the biosynthetic gene clusters (BGCs) of Trametes remain unclear. Here, we conducted comparative analysis, detected the CAZyme genes, and predicted the BGCs for nine Trametes strains. Among the 82,053 homologous clusters obtained for Trametes, we identified 8518 core genes, 60,441 accessory genes, and 13,094 specific genes. A large proportion of CAZyme genes were cataloged into glycoside hydrolases, glycosyltransferases, and carbohydrate esterases. The predicted BGCs of Trametes were divided into six strategies, and the nine Trametes strains harbored 47.78 BGCs on average. Our study revealed that Trametes exhibits an open pan-genome structure. These findings provide insights into the genetic diversity and explored the synthetic biology of secondary metabolite production for Trametes.

Experimental and simulation study on the backstreaming positive ions on the quarter-size negative ion source for CRAFT NNBI test facility

  • Yongjian Xu;Yuwen Yang;Jianglong Wei;Ling Yu;Wen Deng;Rixin Wang;Yuming Gu;Chundong Hu;Yahong Xie
    • Nuclear Engineering and Technology
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    • v.56 no.2
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    • pp.546-551
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    • 2024
  • As an effective methods of plasma heating, neutral beam injection (NBI) systems based on negative hydrogen ion sources will be utilized in future magnetic-confinement nuclear fusion experiments. Because of the collisions between the fast negative ions and the neutral background gas, the positive ions are inevitable created in the acceleration region in the negative NBI system. These positive ions are accelerated back into the ion source and become high energy backstreaming ions. In order to explore the characters of backstreaming ions, the track and power deposition of backstreaming H+ beam is estimated using the experimental and simulation methods at NNBI test facility. Results show that the flux of backstreaming positive ions is 1.93 % of that of negative ion extraction from ion source, and the magnet filed in the beam source has an effect on the backstreaming positive ions propagation.

Purification and Characterization of an Antioxidant Protein from Fertilized Eggs

  • Yang, Shaohua;Tang, Zhengjiang;Tang, ShanShan;Zhang, Tingfang;Tang, Fei;Wu, Yu;Wang, Ying;Wang, Lu Lu;Liu, Guoqing
    • Food Science of Animal Resources
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    • v.36 no.6
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    • pp.791-798
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    • 2016
  • Free radicals may attack cells or tissue, leading to chronic diseases, and antioxidant consumption is potentially useful for removing free radicals. Egg proteins may be used as potential sources of antioxidant considering their ability of scavenging free radicals to apply for food or cosmetics industry. In this study, we obtained a natural antioxidant protein from fertilized eggs, which was a dietary supplement in some Asian countries. Meanwhile, antioxidant activities of these proteins were evaluated using different oxidation systems. With increasing incubation time, the antioxidant activity of these proteins increased during 15 d of incubation. The samples on day 15 were performed for isolation of antioxidant protein. The protein, named P4-1 (MW, 45 kDa), was isolated and purified by consecutive chromatographic methods. P4-1 contained 17 amino acids, which was determined by liquid chromatography-mass spectrometry and Amino Acid Analyzer. Moreover, the amino acid sequence was highly similar to that of ovalbumin. Differential scanning calorimetry showed that the denaturation temperature of P4-1 was $57.16^{\circ}C$. Furthermore, P4-1 suggested high oxygen radical-absorbance activity in ${\cdot}OH$ assays, and its antioxidant activity was stable at $30-50^{\circ}C$ in acidic and neutral pH. Thus, these results revealed that P4-1 may be a potential resource as a natural antioxidant.

Thermal analysis and optimization of the new ICRH antenna Faraday Screen in EAST

  • Q.C. Liang ;L.N. Liu ;W. Zhang ;X.J. Zhang ;S. Yuan ;Y.Z. Mao ;C.M. Qin;Y.S. Wang ;H. Yang
    • Nuclear Engineering and Technology
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    • v.55 no.7
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    • pp.2621-2627
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    • 2023
  • In Experimental Advanced Superconducting Tokamak (EAST) experiments, to achieve long pulse and high-power ICRH system operation, a new kind of ICRH antenna has been designed. One of the most critical factors in limiting the operation of long pulse and high power is the intense heat load in the front face of the ICRH antenna, especially the Faraday Screen (FS). Therefore, the cooling channels of FS need to be designed. According to thermal-hydraulic analysis, the FS tubes are divided into several groups to achieve more excellent water cooling capability. The number of series and parallel tubes in one group is chosen as six. This antenna went into service in the spring of 2021, and it is delightful that the temperature distribution of the FS tube is below 400 ℃ in 14.5 s and 1.8 MW ICRH system operation. However, the active water-cooling design was not carried out on the upper and lower plates of FS, which led to severe ablations on that region under long pulse and high power operation, and the temperature is up to 800. Therefore, the upper and lower side plates of the FS were designed with water cooling based on thermal-hydraulic analysis. During the 2022 winter experiments, the temperature of ICRH antenna FS was lower than 400 in the pulse of 200s and the power of 1 MW operation.

Fuzzy-PID controller for motion control of CFETR multi-functional maintenance platform

  • Li, Dongyi;Lu, Kun;Cheng, Yong;Zhao, Wenlong;Yang, Songzhu;Zhang, Yu;Li, Junwei;Wu, Huapeng
    • Nuclear Engineering and Technology
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    • v.53 no.7
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    • pp.2251-2260
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    • 2021
  • The motion control of the divertor maintenance system of the China Fusion Engineering Test Reactor (CFETR) was studied in this paper, in which CFETR Multi-Functional Maintenance Platform (MFMP) was simplified as a parallel robot for the convenience of theoretical analysis. In order to design the motion controller of parallel robot, the kinematics analysis of parallel robot was carried out. After that, the dynamic modeling of the hydraulic system was built. As the large variation of heavy payload on MFMP and highly nonlinearity of the system, A Fuzzy-PID controller was built for self-tuning PID controller parameters by using Fuzzy system to achieve better performance. In order to test the feasibility of the Fuzzy-PID controller, the simulation model of the system was built in Simulink. The results have showed that Fuzzy-PID controller can significantly reduce the angular error of the moving platform and provide the stable motion for transferring the divertor.

Fabrication of diamond/W-Cu functionally graded material by microwave sintering

  • Wei, Chenlong;Cheng, Jigui;Zhang, Mei;Zhou, Rui;Wei, Bangzheng;Yu, Xinxi;Luo, Laima;Chen, Pengqi
    • Nuclear Engineering and Technology
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    • v.54 no.3
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    • pp.975-983
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    • 2022
  • A four-layered W/Cu functionally graded material (FGM) (W90% + Cu10%/W80% + Cu20%/W70% + Cu30%/W60% + Cu40%, wt.% fraction) and a four-layered diamond/W-Cu FGM (W90% + Cu10%/W80% + Cu20%/W70% + Cu30%/W55% + Cu40% + diamond5%, wt.% fraction) were fabricated by microwave sintering. The thermal conductivity and thermal shock resistance of diamond/W-Cu FGM and W-Cu FGM were investigated. The morphologies of the diamond particles and different FGMs were analyzed using AFM, SEM, EDS, and TEM. The results show that a 200 nm rough tungsten coating was formed on the surface of the diamond. The density of the tungsten-coated diamond/W-Cu FGM, obtained by microwave sintering at 1200 ℃ for 30 min, was 94.66%. The thermal conductivity of the fourlayered diamond/W-Cu FGM was 220 W·m-1·K-1, which is higher than that of the four-layered W/Cu FGM (209 W m-1 K-1). This indicates that adding an appropriate amount of tungsten-coated diamond to the high Cu layer W/Cu FGM improves the thermal conductivity of the composite. The diamond/W-Cu FGM sintered at 1200 ℃ for 10 min exhibited better thermal shock resistance than diamond/W-Cu FGM sintered at 1100 ℃ for 10 min.

Research Method and Prediction Model of PM2.5 in Cities

  • Yang, ZhenYu;Xia, Sai;Jin, Jie
    • Journal of Urban Science
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    • v.8 no.2
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    • pp.25-28
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    • 2019
  • Hefei has suffered from heavy air pollution, especially car exhaust and industry emissions. The smoke contains PM2.5 and PM10. These smoke will enter people's bodies and have a bad impact on the human body. This review is about PM2.5. This review covers the sources and hazards of PM2.5. It introduces the use of modelling methods to analyze PM2.5 pollution in various places and proposes treatment measures. These cities were heavily polluted by PM2.5, and after the local government's management and renovation, there has been a significant improvement. However, there are still many shortcomings in the process of pollution improvement. This review combines the means used in the process of pollution prevention and control in Handan City, Beijing. Hefei now suffers from some of the same pollution as these cities did in the past.

Model-Free Adaptive Integral Backstepping Control for PMSM Drive Systems

  • Li, Hongmei;Li, Xinyu;Chen, Zhiwei;Mao, Jingkui;Huang, Jiandong
    • Journal of Power Electronics
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    • v.19 no.5
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    • pp.1193-1202
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    • 2019
  • A SMPMSM drive system is a typical nonlinear system with time-varying parameters and unmodeled dynamics. The speed outer loop and current inner loop control structures are coupled and coexist with various disturbances, which makes the speed control of SMPMSM drive systems challenging. First, an ultra-local model of a PMSM driving system is established online based on the algebraic estimation method of model-free control. Second, based on the backstepping control framework, model-free adaptive integral backstepping (MF-AIB) control is proposed. This scheme is applied to the permanent magnet synchronous motor (PMSM) drive system of an electric vehicle for the first time. The validity of the proposed control scheme is verified by system simulations and experimental results obtained from a SMPMSM drive system bench test.