Recently,vehicles have experienced a rise in networking and informatization,leading to increased security concerns.As the most widely used automotive bus network,the Controller Area Network(CAN)bus is vulnerable to at...Recently,vehicles have experienced a rise in networking and informatization,leading to increased security concerns.As the most widely used automotive bus network,the Controller Area Network(CAN)bus is vulnerable to attacks,as security was not considered in its original design.This paper proposes SIDuBzip2,a traffic anomaly detection method for the CAN bus based on the bzip2 compression algorithm.The proposed method utilizes the pseudo-periodic characteristics of CAN bus traffic,constructing time series of CAN IDs and calculating the similarity between adjacent time series to identify abnormal traffic.The method consists of three parts:the conversion of CAN ID values to characters,the calculation of similarity based on bzip2 compression,and the optimal solution of model parameters.The experimental results demonstrate that the proposed SIDuBzip2 method effectively detects various attacks,including Denial of Service,replay,basic injection,mixed injection,and suppression attacks.In addition,existing CAN bus traffic anomaly detection methods are compared with the proposed method in terms of performance and delay,demonstrating the feasibility of the proposed method.展开更多
Tritium self-sufficiency in future deuterium–tritium fusion reactors is a crucial challenge.As an engineering test reactor,the China Fusion Engineering Test Reactor requires a burning fraction of 3%for the goal to te...Tritium self-sufficiency in future deuterium–tritium fusion reactors is a crucial challenge.As an engineering test reactor,the China Fusion Engineering Test Reactor requires a burning fraction of 3%for the goal to test the accessibility to the future fusion plant.To self-consistently simulate burning plasmas with profile changes in pellet injection scenarios and to estimate the corresponding burning fraction,a one-dimensional multi-species radial transport model is developed in the BOUT++framework.Several pellet-fueling scenarios are then tested in the model.The results show that the increased fueling depth improves the burning fraction by particle confinement improvement and fusion power increase.Nevertheless,by increasing the depth,the pellet cooling-down may significantly lower the temperature in the core region.Taking the density perturbation into consideration,the reasonable parameters of the fueling scenario in these simulations are estimated as pellet radius r_(p)=3 mm,injection rate=4 Hz,and pellet injection velocity=1000–2000 m s^(-1) without drift or 450 m s^(-1) with high-field-side drift.展开更多
Microbial growth is an issue of concern that may cause hygienic and aesthetic problems during the transportation and usage of reclaimed water. Assimilable organic carbon （AOC） is an important parameter which determi...Microbial growth is an issue of concern that may cause hygienic and aesthetic problems during the transportation and usage of reclaimed water. Assimilable organic carbon （AOC） is an important parameter which determines the heterotrophic bacterial growth potential of water. Pseudomonas fluorescens P17 and Spirillum sp. NOX are widely used to measure AOC in drinking water. The AOC values of various reclaimed water samples determined by P 17 and NOX were compared with those determined by the new strains isolated from reclaimed water in this study. It showed that the conventional test strains were not suitable for AOC measurement of reclaimed water in certain cases. In addition to P17 and NOX, Stenotrophomonas sp. Z J2, Pseudomonas saponi- phila G3 and Enterobacter sp. G6, were selected as test strains for AOC measurement of reclaimed water. Key aspects of the bioassay including inoculum cell density, incubation temperature, incubation time and the pH of samples were evaluated for the newly selected test strains. Higher inoculum density （104 CFU.mL-1） and higher incubation temperature （25℃） could reduce the time required for the tests. The AOC results of various collected samples showed the advantages of the method proposed based on those five strains in evaluating the biologic stability of reclaimed water.展开更多
文摘Recently,vehicles have experienced a rise in networking and informatization,leading to increased security concerns.As the most widely used automotive bus network,the Controller Area Network(CAN)bus is vulnerable to attacks,as security was not considered in its original design.This paper proposes SIDuBzip2,a traffic anomaly detection method for the CAN bus based on the bzip2 compression algorithm.The proposed method utilizes the pseudo-periodic characteristics of CAN bus traffic,constructing time series of CAN IDs and calculating the similarity between adjacent time series to identify abnormal traffic.The method consists of three parts:the conversion of CAN ID values to characters,the calculation of similarity based on bzip2 compression,and the optimal solution of model parameters.The experimental results demonstrate that the proposed SIDuBzip2 method effectively detects various attacks,including Denial of Service,replay,basic injection,mixed injection,and suppression attacks.In addition,existing CAN bus traffic anomaly detection methods are compared with the proposed method in terms of performance and delay,demonstrating the feasibility of the proposed method.
基金supported by National Natural Science Foundation of China(Nos.11975087 and 41674165)the National Key Research and Development Program of China(Nos.2017YFE0300501 and 2018YFE030310)。
文摘Tritium self-sufficiency in future deuterium–tritium fusion reactors is a crucial challenge.As an engineering test reactor,the China Fusion Engineering Test Reactor requires a burning fraction of 3%for the goal to test the accessibility to the future fusion plant.To self-consistently simulate burning plasmas with profile changes in pellet injection scenarios and to estimate the corresponding burning fraction,a one-dimensional multi-species radial transport model is developed in the BOUT++framework.Several pellet-fueling scenarios are then tested in the model.The results show that the increased fueling depth improves the burning fraction by particle confinement improvement and fusion power increase.Nevertheless,by increasing the depth,the pellet cooling-down may significantly lower the temperature in the core region.Taking the density perturbation into consideration,the reasonable parameters of the fueling scenario in these simulations are estimated as pellet radius r_(p)=3 mm,injection rate=4 Hz,and pellet injection velocity=1000–2000 m s^(-1) without drift or 450 m s^(-1) with high-field-side drift.
文摘Microbial growth is an issue of concern that may cause hygienic and aesthetic problems during the transportation and usage of reclaimed water. Assimilable organic carbon （AOC） is an important parameter which determines the heterotrophic bacterial growth potential of water. Pseudomonas fluorescens P17 and Spirillum sp. NOX are widely used to measure AOC in drinking water. The AOC values of various reclaimed water samples determined by P 17 and NOX were compared with those determined by the new strains isolated from reclaimed water in this study. It showed that the conventional test strains were not suitable for AOC measurement of reclaimed water in certain cases. In addition to P17 and NOX, Stenotrophomonas sp. Z J2, Pseudomonas saponi- phila G3 and Enterobacter sp. G6, were selected as test strains for AOC measurement of reclaimed water. Key aspects of the bioassay including inoculum cell density, incubation temperature, incubation time and the pH of samples were evaluated for the newly selected test strains. Higher inoculum density （104 CFU.mL-1） and higher incubation temperature （25℃） could reduce the time required for the tests. The AOC results of various collected samples showed the advantages of the method proposed based on those five strains in evaluating the biologic stability of reclaimed water.
