Because of an explosive growth of the intrusions, necessity of anomaly-based Intrusion Detection Systems (IDSs) which are capable of detecting novel attacks, is increasing. Among those systems, flow-based detection sy...Because of an explosive growth of the intrusions, necessity of anomaly-based Intrusion Detection Systems (IDSs) which are capable of detecting novel attacks, is increasing. Among those systems, flow-based detection systems which use a series of packets exchanged between two terminals as a unit of observation, have an advantage of being able to detect anomaly which is included in only some specific sessions. However, in large-scale networks where a large number of communications takes place, analyzing every flow is not practical. On the other hand, a timeslot-based detection systems need not to prepare a number of buffers although it is difficult to specify anomaly communications. In this paper, we propose a multi-stage anomaly detection system which is combination of timeslot-based and flow-based detectors. The proposed system can reduce the number of flows which need to be subjected to flow-based analysis but yet exhibits high detection accuracy. Through experiments using data set, we present the effectiveness of the proposed method.展开更多
The novel method for the preparation of titanium powder by multi-stage reduction was proposed. The primary reduction adopted self-propagating high-temperature synthesis(SHS) mode. This paper focuses on the primary red...The novel method for the preparation of titanium powder by multi-stage reduction was proposed. The primary reduction adopted self-propagating high-temperature synthesis(SHS) mode. This paper focuses on the primary reduction process of Mg–TiO_(2) system under the condition of off-balance reaction. The effects of different material ratios,material arrangement methods and reaction initiation modes on the SHS reaction process of Mg–TiO_(2) system and its reaction mechanism were systematically studied. SHS mode was used to Mg–TiO_(2) system, and non-stoichiometric lowvalent titanium oxide intermediate including a-Ti(Ti2 O type) and Ti O was directly obtained(with oxygen content of13.93 wt%). SHS reaction initiated by local ignition is more sufficient than by overall heating method. Compared with the loose setting materials, the compacts can increase the effective contact interface of the reactants, and SHS reaction proceeds more sufficiently, which is favorable for obtaining lower oxygen content product. The adiabatic temperatures of the Mg–TiO_(2) system at different initial conditions were calculated according to the improved calculation method.When the initial temperature is 298 K, the adiabatic temperature of Mg–TiO_(2) system is between 1363 and 2067 K at different material ratios. Therefore, unreacted or partially excess Mg at the reaction front will diffuse into the unreacted region in gas or liquid form, thereby preheating the material and initiating further SHS reaction.展开更多
The influence of reduction conditions on carbon deposition during fiuidized-bed pre-reduction of iron ore fines was investigated experimentally.The results showed that reduction temperature and the composition of redu...The influence of reduction conditions on carbon deposition during fiuidized-bed pre-reduction of iron ore fines was investigated experimentally.The results showed that reduction temperature and the composition of reducing gases had a significant effect on the rate of carbon deposition and the type of carbon deposits (graphite and Fe3C).Low reduction temperature,high CO content,and addition of H2favored the deposition of carbon,especially graphite.The reduction conditions also significantly affected the surface morphology of the as-reduced iron ore fines.As the amount of deposited graphite increased,the formation of fibrous iron disappeared and graphite filaments were observed.The pre-reduced iron ore fines were further fiuidized in pure CO at 850℃ for final reduction.The results showed that graphite could suppress the formation of fibrous iron and decrease the surface viscosity,thereby inhibiting agglomeration during the final high-temperature reduction stage.Reactions that consume the deposited carbon during the final high-temperature reduction were identified and graphite was shown to be more reactive than Fe3C.To enhance the application of fluidization technology in producing sponge iron,a novel solid-state high-temperature reduction method via deposited carbon was proposed and demonstrated to be feasible.展开更多
文摘Because of an explosive growth of the intrusions, necessity of anomaly-based Intrusion Detection Systems (IDSs) which are capable of detecting novel attacks, is increasing. Among those systems, flow-based detection systems which use a series of packets exchanged between two terminals as a unit of observation, have an advantage of being able to detect anomaly which is included in only some specific sessions. However, in large-scale networks where a large number of communications takes place, analyzing every flow is not practical. On the other hand, a timeslot-based detection systems need not to prepare a number of buffers although it is difficult to specify anomaly communications. In this paper, we propose a multi-stage anomaly detection system which is combination of timeslot-based and flow-based detectors. The proposed system can reduce the number of flows which need to be subjected to flow-based analysis but yet exhibits high detection accuracy. Through experiments using data set, we present the effectiveness of the proposed method.
基金financially supported by the National Natural Science Foundation of China(Nos.U1908225,U1702253 and 51774078)the Fundamental Research Funds for the Central Universities(Nos.N172506009,N170908001 and N182515007)。
文摘The novel method for the preparation of titanium powder by multi-stage reduction was proposed. The primary reduction adopted self-propagating high-temperature synthesis(SHS) mode. This paper focuses on the primary reduction process of Mg–TiO_(2) system under the condition of off-balance reaction. The effects of different material ratios,material arrangement methods and reaction initiation modes on the SHS reaction process of Mg–TiO_(2) system and its reaction mechanism were systematically studied. SHS mode was used to Mg–TiO_(2) system, and non-stoichiometric lowvalent titanium oxide intermediate including a-Ti(Ti2 O type) and Ti O was directly obtained(with oxygen content of13.93 wt%). SHS reaction initiated by local ignition is more sufficient than by overall heating method. Compared with the loose setting materials, the compacts can increase the effective contact interface of the reactants, and SHS reaction proceeds more sufficiently, which is favorable for obtaining lower oxygen content product. The adiabatic temperatures of the Mg–TiO_(2) system at different initial conditions were calculated according to the improved calculation method.When the initial temperature is 298 K, the adiabatic temperature of Mg–TiO_(2) system is between 1363 and 2067 K at different material ratios. Therefore, unreacted or partially excess Mg at the reaction front will diffuse into the unreacted region in gas or liquid form, thereby preheating the material and initiating further SHS reaction.
基金The authors gratefully acknowledge financial support from the National Natural Science Foundation of China (Grant No. 21736010).
文摘The influence of reduction conditions on carbon deposition during fiuidized-bed pre-reduction of iron ore fines was investigated experimentally.The results showed that reduction temperature and the composition of reducing gases had a significant effect on the rate of carbon deposition and the type of carbon deposits (graphite and Fe3C).Low reduction temperature,high CO content,and addition of H2favored the deposition of carbon,especially graphite.The reduction conditions also significantly affected the surface morphology of the as-reduced iron ore fines.As the amount of deposited graphite increased,the formation of fibrous iron disappeared and graphite filaments were observed.The pre-reduced iron ore fines were further fiuidized in pure CO at 850℃ for final reduction.The results showed that graphite could suppress the formation of fibrous iron and decrease the surface viscosity,thereby inhibiting agglomeration during the final high-temperature reduction stage.Reactions that consume the deposited carbon during the final high-temperature reduction were identified and graphite was shown to be more reactive than Fe3C.To enhance the application of fluidization technology in producing sponge iron,a novel solid-state high-temperature reduction method via deposited carbon was proposed and demonstrated to be feasible.
