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Experimental study on shock interaction control of double wedge in high-enthalpy hypersonic flow subject to plasma synthetic jet

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Chinese Journal of Aeronautics 2024年第4期37卷 151-165页

作者： Xuzhen XIE Qiang LIU Yan ZHOU Zhenbing LUO Wei XIE Guanghui BAI Kai LUO Qiu WANG jianjun wu College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China China Academy of Launch Vehicle Technology Beijing 100076China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China

The hypersonic shock-shock interaction flow field at double-wedge geometries controlled by plasma synthetic jet actuator is experimentally studied in a Ma = 8 high-enthalpy shock tunnel with the purpose of exploring a novel technique for reducing surface heat flux in a real flight environment. The results demonstrate that increasing the discharge energy is advantageous in eliminating the shock wave, shifting the shock wave interaction point, and shortening the control response time. The oblique shock wave can be completely removed when the actuator's discharge energy grows from 0.4 J to 11.5 J, and the displacement of the shock wave interaction point increases by 124.56%, while the controlled response time is shortened by 30 μs. Besides, the reduction in diameter of the jet exit is firstly proved to have a negative impact on energy deposition in a working environment with incoming flow, which reduces the discharge energy and hence decreases the control effect. The shock wave control response time lengthens when the jet exits away from the second wedge. Along with comparing the change in wall heat flux at the second wedge over time, the control effect of plasma synthetic jet actuator with and without inflation is also analyzed. When plasma synthetic jet works in inflatable mode, both the ability to eliminate shock waves and the shifting effect of the shock wave interaction point are increased significantly, and the wall heat flux is also reduced.

关键词： Hypersonic flow High-enthalpy flow Plasma synthetic jet Shock wave Flow control

Engineering hierarchical quaternary superstructure of an integrated MOF-derived electrode for boosting urea electrooxidation assisted water electrolysis

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Green Energy & Environment 2024年第4期9卷 695-701页

作者： jianjun Tian Changsheng Cao Yingchun He Muhammad Imran Khan Xin-Tao wu Qi-Long Zhu State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of Sciences(CAS)Fuzhou350002China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou350108China University of Chinese Academy of Sciences Beijing100049China Research Institute of Sciences and Engineering(RISE) University of SharjahSharjah27272United Arab Emirates

Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierarchical quaternary superstructure was fabricated through a self-sacrificing template strategy from the metal–organic framework(Co-ZIF-67)nanoplate arrays,which features an intriguing well-defined hierarchy when taking the unit cells of the NiCo-based layered double hydroxide(NiCo-LDH)as the primary structure,the ultrathin LDH nanoneedles as the secondary structure,the mesoscale hollow plates of the LDH nanoneedle arrays as the tertiary structure,and the macroscale three-dimensional frames of the plate arrays as the quaternary structure.Notably,the distinctive structure of NiCo-ZLDH/NF can not only accelerate both mass and charge transfer,but also expose plentiful accessible active sites with high intrinsic activity,endowing it with an excellent electrochemical performance for urea oxidation reaction(UOR).Specially,it only required the low potentials of 1.335,1.368 and 1.388 V to deliver the current densities of 10,100 and 200 mA cm^(-2),respectively,much superior to those for typical NiCo-LDH.Employing NiCo-ZLDH/NF as the bifunctional electrode for both anodic UOR and cathodic HER,an energy-saving electrolysis system was further explored which can greatly reduce the needed voltage of 213 mV to deliver the current density of 100 mA cm^(-2),as compared to the conventional water electrolysis system composed of OER.This work manifests that it is prospective to explore the hierarchically nanostructured electrodes and the innovative electrolytic technologies for high-efficiency electrocatalysis.

关键词： Hierarchical superstructures Metal–organic frameworks Layered double hydroxides Urea oxidation reaction Hydrogen evolution reaction

Detecting compromised email accounts via login behavior characterization

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Cybersecurity 2024年第1期7卷 16-36页

作者： jianjun Zhao Can Yang Di wu Yaqin Cao Yuling Liu Xiang Cui Qixu Liu Institute of Information Engineering Chinese Academy of SciencesBeijing100085China School of Cyber Security University of Chinese Academy of SciencesBeijing100049China China Cybersecurity Review Technology and Certification Center Beijing100013China Zhongguancun Laboratory Beijing100089China

The illegal use of compromised email accounts by adversaries can have severe consequences for enterprises and society.Detecting compromised email accounts is more challenging than in the social network field,where email accounts have only a few interaction events(sending and receiving).To address the issue of insufficient features,we propose a novel approach to detecting compromised accounts by combining time zone differences and alternate logins to identify abnormal behavior.Based on this approach,we propose a compromised email account detection framework that relies on widely available and less sensitive login logs and does not require labels.Our framework characterizes login behaviors to identify logins that do not belong to the account owner and outputs a list of account-subnet pairs ranked by their likelihood of having abnormal login relationships.This approach reduces the number of account-subnet pairs that need to be investigated and provides a reference for investigation priority.Our evaluation demonstrates that our method can detect most email accounts that have been accessed by disclosed malicious IP addresses and outperforms similar research.Additionally,our framework has the capability to uncover undisclosed malicious IP addresses.

关键词： Compromised account detection Mixture model Login log analysis Attribution and forensic

LDL-C rebound after long-term evolocumab treatment and intravascular imaging evidence in a familial hypercholesterolemia patient with early-onset myocardial infarction

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Chronic Diseases and Translational Medicine 2024年第1期10卷 69-74页

作者： Zhifan Li Shuang Zhang Zheng Yin Wenjia Zhang Yonggang Sui jianjun Li Kefei Dou Jie Qian Naqiong wu Cardiometabolic Center National Center for Cardiovascular DiseasesFuwai HospitalChinese Academy of Medical Science and Peking Union Medical CollegeBeijingChina

Patients with familial hypercholesterolemia(FH)have elevated low-density lipoprotein cholesterol(LDL-C)levels and are at high risk of premature cardiovascular disease.1 Heterozygous FH(HeFH)is one of the commonest genetic disorders,and is more frequent among those with ischemic heart disease(IHD),atherosclerotic cardiovascular disease(ASCVD)and premature IHD.

关键词： cardiovascular familial elevated

An atmosphere-breathing propulsion system using inductively coupled plasma source

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Chinese Journal of Aeronautics 2023年第5期36卷 223-238页

作者： Peng ZHENG jianjun wu Yu ZHANG Bixuan CHE Yuanzheng ZHAO College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

CubeSats have attracted more research interest recently due to their lower cost and shorter production time.A promising technology for CubeSat application is atmosphere-breathing electric propulsion,which can capture the atmospheric particles as propulsion propellant to maintain longterm mission at very low Earth orbit.This paper designs an atmosphere-breathing electric propulsion system for a 3 U CubeSat,which consists of an intake device and an electric thruster based on the inductively coupled plasma.The capture performance of intake device is optimized considering both particles capture efficiency and compression ratio.The plasma source is also analyzed by experiment and simulation.Then,the thrust performance is also estimated when taking into account the intake performance.The results show that it is feasible to use atmosphere-breathing electric propulsion technology for CubeSats to compensate for aerodynamic drag at lower Earth orbit.

关键词： Atmosphere-Breathing Electric Propulsion(ABEP) CubeSat Inductively coupled plasma Intake device Very Low Earth Orbit(VLEO)

Measurement method and results of divergence angle of laser-controlled solid propellants used in space propulsion

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中国航空学报:英文版 2023年第9期36卷 195-206页

作者： Yang OU jianjun wu Yuqiang CHENG Yu ZHANG Yuqi LI College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

The plume divergence angle is an important reference index for evaluating the thrust efficiency and propellant utilization of space propulsion systems.However,the characteristics of the dynamic variation of plume divergence angle over time cannot be measured using current methods.This paper utilizes high-speed photography and image processing methods to develop a strategy that can give a quick,non-destructive and real-time detection of the divergence angle.Effectiveness of the strategy is verified,and the characteristics of plume divergence angles of different lasercontrolled solid propellants were further analyzed and fitted.The experimental results indicate that graphene could effectively reduce the divergence angle,while oxide-doped samples had larger divergence angles than alloy-doped and carbon-doped samples.

关键词： Ablation Image processing Laser Plume divergence angle Propellant Space application

Application of Lattice Boltzmann Method to Simulate Forest Edge

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Advances in Applied Mathematics and Mechanics 2023年第2期15卷 376-401页

作者： Jie Wei jianjun wu An Jiang Kun Wan Key Laboratory of Mechanics on Disaster and Environment inWestern China Attached to the Ministry of Education of ChinaLanzhou UniversityLanzhouGansu 730000China College of Civil Engineering and Mechanics Lanzhou UniversityLanzhouGansu 730000China Shenzhen TenFong Technology Co. LtdGuangdongChina ZhongJiao TianHe Machinery Equipment Manufacturing Co.LTD SuzhouJiangsuChina

This study is focused on the forest edge flow by using numerical method.To model the effects of a forest canopy on airflow,source terms are introduced into the governing equations.The lattice Boltzmann method in conjunction with the standard k-εmodel is applied to solve the turbulent wind field.In order to perform the simulation on non-uniform grids,the Taylor series expansion and least square based lattice Boltzmann method(TLLBM)is adopted to improve the accuracy and computational efficiency.The present method and code are verified with an earlier forest edge simulation.A series of forest canopies are established to explore the impacts of canopy morphology on wind field.These canopies cover 3 canopy architectures and the Leaf Area Index(LAI)ranges from 2.0 to 4.0.The further study is carried out by adjusting the canopy foliage amount and the canopy architecture.The present study demonstrates the potential of lattice Boltzmann method to simulate the high Re number forest edge flow.The impacts of canopy morphology on zero plane displacement,aerodynamic roughness length,friction wind velocity,permeability coefficient,wall-shear stress are illustrated in detail.The results show that the canopy sub-layer wind field,especially the wind velocity profiles within and above the forest canopy,are mainly determined by canopy morphology.

关键词： Forest edge lattice Boltzmann method non-uniform grids canopy morphology

Deep Clinical Phenotyping of Parkinson’s Disease: Towards a New Era of Research and Clinical Care

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Phenomics 2022年第5期2卷 349-361页

作者： Zhiheng Xu Bo Shen Yilin Tang jianjun wu Jian Wang Department of Neurology and National Research Center for Aging and Medicine&National Center for Neurological Disorders State Key Laboratory of Medical NeurobiologyHuashan HospitalFudan UniversityShanghai 200040China

Despite recent advances in technology,clinical phenotyping of Parkinson’s disease(PD)has remained relatively limited as current assessments are mainly based on empirical observation and subjective categorical judgment at the clinic.A lack of comprehensive,objective,and quantifiable clinical phenotyping data has hindered our capacity to diagnose,assess patients’conditions,discover pathogenesis,identify preclinical stages and clinical subtypes,and evaluate new therapies.Therefore,deep clinical phenotyping of PD patients is a necessary step towards understanding PD pathology and improving clinical care.In this review,we present a growing community consensus and perspective on how to clinically phenotype this disease,that is,to phenotype the entire course of disease progression by integrating capacity,performance,and perception approaches with state-of-the-art technology.We also explore the most studied aspects of PD deep clinical phenotypes,namely,bradykinesia,tremor,dyskinesia and motor fluctuation,gait impairment,speech impairment,and non-motor phenotypes.

关键词： Parkinson’s disease Deep phenotyping Motor symptoms Non-motor symptoms

Advances in HIV Eradication Strategies

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Infectious Microbes & Diseases 2022年第2期4卷 64-70页

作者： Qingmin Mei Wei Wang jianjun wu Yong Gao The First Affiliated Hospital Division of Life Science and MedicineUniversity of Science and Technology of ChinaHefeiAnhuiChina Anhui Provincial Center for Disease Control and Prevention HefeiAnhuiChina

Although the advent of combination antiretroviral therapy can efficiently suppress human immunodeficiency virus(HIV)replication,a complete cure for HIV infection cannot be achieved due to the existence of latent viral reservoirs.In recent years,investigation of HIV cure strategies has become a hot topic in the field.In this article,we review the major barriers to HIV cure,compare the progress and challenges of non-specific and specific latent reversal agents in curing HIV,and discuss possible solutions to the current problems.

关键词： HIV latent reservoir latency reversing agents