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Effective Algorithms to Detect Stepping-Stone Intrusion by Removing Outliers of Packet RTTs

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Tsinghua Science and Technology 2022年第2期27卷 432-442页

作者： Lixin Wang Jianhua Yang Michael Workman Pengjun Wan TSYS School of Computer Science Columbus State UniversityColumbusGA 31907USA the Department of Computer Science Illinois Institute of TechnologyChicagoIL 60616USA

An effective method to detect stepping-stone intrusion(SSI)is to estimate the length of a connection chain.This type of detection method is referred to as a network-based detection approach.Existing network-based SSI detection methods are either ineffective in the context of the Internet because of the presence of outliers in the packet round-trip times(RTTs)or inefficient,as many packets must be captured and processed.Because of the high fluctuation caused by the intermediate routers on the Internet,it is unavoidable that the RTTs of the captured packets contain outlier values.In this paper,we first propose an efficient algorithm to eliminate most of the possible RTT outliers of the packets captured in the Internet environment.We then develop an efficient SSI detection algorithm by mining network traffic using an improved version of k-Means clustering.Our proposed detection algorithm for SSI is accurate,effective,and efficient in the context of the Internet.Well-designed network experiments are conducted in the Internet environment to verify the effectiveness,correctness,and efficiency of our proposed algorithms.Our experiments show that the effective rate of our proposed SSI detection algorithm is higher than 85.7%in the context of the Internet.

关键词： network security intrusion detection stepping-stone intrusion round-trip time k-Means clustering connection chain

Stability characteristics and airworthiness requirements of blended wing body aircraft with podded engines

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Chinese Journal of Aeronautics 2022年第6期35卷 77-86页

作者： Lixin Wang Ning ZHANG Hailiang LIU Ting YUE School of Aeronautics Science and Engineering Beihang UniversityBeijing 100083China

Blended-Wing-Body(BWB)aircraft have a relatively short fuselage and no horizontal tail,and they usually adopt podded engines and a V tail instead of a vertical tail.Generally,BWB aircraft have decreased longitudinal and directional static stability and damping.In this paper,the three-axis static and dynamic stability characteristics of an example BWB aircraft with podded engines are studied.According to the differences in flight characteristics of BWB aircraft and conventional aircraft,the different airworthiness requirements for BWB aircraft are analyzed:first,based on current airworthiness regulations and transport aircraft flying quality specification,the relaxation requirement of longitudinal static stability for BWB aircraft is studied;second,the influences of podded engines on longitudinal trim,attitude and trajectory responses and maximum directional control power requirement of BWB aircraft are analyzed;third,the changes in the proportional relationships between the takeoff characteristic speeds of the example BWB aircraft are analyzed.In view of these variations in directional control power requirement and relationships between takeoff characteristic speeds,new recommendations for airworthiness evaluation are proposed for BWB aircraft.The conclusions of this paper are helpful references for configuration design,flight control law design and airworthiness evaluation of BWB aircraft.

关键词： Airworthiness Blended wing body Podded engine Relaxed static stability Stability characteristics

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让历史的烛光照亮未来——王立新教授访谈

历史教学（下半月） 2019年第8期 3-7页

作者：王立新王一哲北京大学历史学系

采访时间:2019年5月采访地点:北京大学历史学系问:王教授,您好!可以谈谈您的成长经历吗?您为什么选择学习美国史专业?又是什么原因促使您走上历史研究的道路呢?答:我出生在辽宁省兴城市(县)一个偏远的小山村,交通非常不便,在村里读完小... 详细信息

采访时间:2019年5月采访地点:北京大学历史学系问:王教授,您好!可以谈谈您的成长经历吗?您为什么选择学习美国史专业?又是什么原因促使您走上历史研究的道路呢?答:我出生在辽宁省兴城市(县)一个偏远的小山村,交通非常不便,在村里读完小学,到乡里中学上初中,1981年以全县第11名的成绩考入兴城市高级中学一县里唯一的一所省级重点高中。

关键词：历史学新教王立光照省级重点高中高级中学北京大学采访地点

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提高领导干部和公务员科学素质对策研究

未来与发展 2019年第11期40卷 32-41页

作者：王立新北京市科学技术进修学院

领导干部和公务员是党和国家政策的制定者、决策者和实施者,是实现"两个一百年"宏伟目标、建设创新型国家、实现中国梦的引领者。提高领导干部和公务员的科学素质,对于推进国家治理体系和治理能力现代化,推动经济和社会全面发展具有举... 详细信息

领导干部和公务员是党和国家政策的制定者、决策者和实施者,是实现"两个一百年"宏伟目标、建设创新型国家、实现中国梦的引领者。提高领导干部和公务员的科学素质,对于推进国家治理体系和治理能力现代化,推动经济和社会全面发展具有举足轻重的作用。文章从国家发展、民族复兴的角度分析了提高领导干部和公务员科学素质的重要意义,分析了制约提高领导干部和公务员科学素质的主要因素有:领导干部和公务员思想认识不足、工作机制体制不健全、施教机构培训能力不足、针对领导干部和公务员的科普资源缺乏等。文章分析借鉴欧美发达国家提升公民科学素质和公务员培训工作的经验如科普立法、科学活动策划、企业办科普、公务员培训制度建设等方面的好做法,从而提出提高领导干部和公务员科学素质的对策和建议有:提升思想认识、建立健全工作机制、加大培训力度、强化科普资源和设施建设、加强组织科普活动、突出宣传效果等。

关键词：领导干部公务员科学素质

Online Inertia Estimation Using Electromechanical Oscillation Modal Extracted from Synchronized Ambient Data

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Journal of Modern Power Systems and Clean Energy 2022年第1期10卷 241-244页

作者： Bo wang Deyou Yang Guowei Cai Jin Ma Zhe Chen Lixin Wang School of Electrical Engineering Northeast Electrical Power UniversityJilin 132012China School of Electrical and Information Engineering The University of SydneySydneyAustralia Department of Energy Technology Aalborg UniversityAalborgDenmark

An ambient modal framework for inertia estimation using synchrophasor data is proposed in this letter.Specifically,an analytical formulation is developed for the estimation of inertia based on the frequency and damping ratio modes extracted from ambient data.An advantage of the proposed framework is that it can rely on synchronized ambient data under non-disturbed conditions for online estimation and tracking of inertia.Ultimately,numerical simulation studies and physical experiments demonstrate the feasibility of the proposed approach.

关键词： Inertia electromechanical oscillation ambient modal

A local observability analysis method for a time-varying nonlinear system and its application in the continuous self-calibration system

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Science China(Information Sciences) 2021年第1期64卷 254-256页

作者： Qi wang Lixin Wang Weiwei QIN Qiang SHEN rd Department Xi’an High-tech Institution

Dear editor,Employing observability analysis of a dynamic system is necessary to determine the efficiency of a Kalman filter designed to estimate the state of dynamic system,and the system state is a set of variables which can describe the motion state of the dynamic system.The observability sets a lower limit for the estimation error,and the lower the limit,the better the likelihood of obtaining an accurate estimate of the system state.In other words,if the system is not observable,it is not possible to accurately estimate the system state,even if the noise level is negligible.While

关键词： Continuous self-calibration Local observability Piece-wise constant systems (PWCS) Observable degree Rotation scheme

Unilateral pleural effusion secondary to Takayasu arteritis: a case report and literature review

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The Journal of Biomedical Research 2022年第2期36卷 141-144页

作者： Ling Chen Ting Ma Liang wang Lixin Wang Minmin Li Rong Zhu The Huai'an Clinical College of Xuzhou Medical University Huai'anJiangsu 223300China Department of Respiratory Medicine Huai'an First People's HospitalHuai'anJiangsu 223300China

Takayasu arteritis (TA) is a chronic, nonspecific inflammatory disease of large and medium-sized vessels that primarily involves the aorta and its branches. TA involving the pulmonary arteries has a prevalence ranging from 14% to 86%, which can lead to pulmonary hypertension, a progressive increase in pulmonary artery pressure, and eventually death from right heart failure. The presentation of pulmonary arteritis (PA) is very nonspecific, with a reported misdiagnosis rate of up to 60% and a diagnosis time ranging from 1 month to more than 10 years. The clinical manifestation of pleural effusion is very rare in both TA and PA cases. Based on our literature review, this is the 6th reported case of TA with pleural effusion, and the specific mechanism of TA with pleural effusion is still unclear. The characteristics of this case and the previously reported cases are summarized in this article to improve the understanding of TA and PA and reduce the misdiagnosis rate.

关键词： Takayasu arteritis pulmonary arteritis pleural effusion case report literature review

Effects of Nd on microstructure and mechanical properties of as-cast Mg-12Gd-2Zn-xNd-0.4Zr alloys with stacking faults

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International Journal of Minerals,Metallurgy and Materials 2022年第8期29卷 1570-1577页

作者： lixin Hong Rongxiang wang Xiaobo Zhang School of Materials Science and Engineering Nanjing Institute of TechnologyNanjing 211167China Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology Nanjing 211167China

In order to study the effects of Nd addition on microstructure and mechanical properties of Mg-Gd-Zn-Zr alloys,the microstruc-ture and mechanical properties of the as-cast Mg-12Gd-2Zn-xNd-0.4Zr(x=0,0.5wt%,and 1wt%)alloys were investigated by using optical microscope,scanning electron microscope,X-ray diffractometer,nano indentation tester,microhardness tester,and tensile testing machine.The results show that the microstructures mainly consist ofα-Mg matrix,eutectic phase,and stacking faults.The addition of Nd plays a significant role in grain refinement and uniform microstructure.The tensile yield strength and microhardness increase but the compression yield strength decreases with increasing Nd addition,leading to weakening tension-compression yield asymmetry in reverse of the Mg-12Gd-2Zn-xNd-0.4Zr alloys.The highest ultimate tensile strength(194 MPa)and ultimate compression strength(397 MPa)are obtained with 1wt%Nd addition of the alloy.

关键词： magnesium alloy neodymium microstructure stacking fault mechanical properties

Sliding mode control design for oblique wing aircraft in wing skewing process

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Chinese Journal of Aeronautics 2019年第2期32卷 263-271页

作者： Ting YUE Zijian XU Lixin Wang Tong wang School of Aeronautic Science and Engineering Beihang University China Ship Development and Design Center

When the wing of Oblique Wing Aircraft(OWA) is skewed, the center of gravity, inertia and aerodynamic characteristics of the aircraft all significantly change, causing an undesirable flight dynamic response, affecting the flying qualities, and even endangering the flight safety. In this study,the dynamic response of an OWA in the wing skewing process is simulated, showing that the threeaxis movements of the OWA are highly coupled and present nonlinear characteristics during the wing skewing. As the roll control efficiency of the aileron decreases due to the shortened control arm in an oblique configuration, the all-moving horizontal tail is used for additional roll and the control allocation is performed based on minimum control energy. Given the properties of pitchroll-yaw coupling and control input and state coupling, and the difficulty of establishing an accurate aerodynamic model in the wing skewing process due to unsteady aerodynamic force, a multi-loop sliding mode controller is formulated by the time-scale separation method. The closed-loop simulation results show that the asymmetric aerodynamics can be balanced and that the velocity and altitude of the aircraft maintain stable, which means that a smooth transition is obtained during the OWA's wing skewing.

关键词： Decoupling Dynamic response Oblique wing aircraft Sliding mode control Wing skewing process