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Mechanism analysis of hysteretic aerodynamic characteristics on variable-sweep wings

Chinese Journal of Aeronautics 2023年第5期36卷 212-222页

作者： lifang ZENG liu liu Xueming SHAO Jun LI Zhejiang University Hangzhou 310027China Rotor Aerodynamics Key Laboratory China Aerodynamics Research and Development CenterMianyang 621000China

Variable-sweep wings have large shape-changing capabilities and wide flight envelops,which are considered as one of the most promising directions for intelligent morphing UAVs.Aerodynamic investigations always focus on several static states in the varying sweep process,which ignore the unsteady aerodynamic characteristics.However,deviations to static aerodynamic forces are inevitably caused by dynamic sweep motion.In this work,first,unsteady aerodynamic characteristics on a typical variable-sweep UAV with large aspect ratio were analyzed.Then,deep mechanism of unsteady aerodynamic characteristics in the varying sweep process was studied.Finally,numerical simulation method integrated with structured moving overset grids was applied to solve the unsteady fluid of varying sweep process.The simulation results of a sweep forward-backward circle show a distinct dynamic hysteresis loop surrounding the static data for the aerodynamic forces.Compared with the static lift coefficients,at the same sweep angles,dynamic lift coefficient in sweep forward process are all smaller,while dynamic sweep backward lift coefficient are all larger.In addition,dynamic deviations to static lift coefficient are positively related with the varying sweep speeds.Mechanism study on the unsteady aerodynamic characteristics indicates that three key factors lead to the dynamic hysteresis loop in varying sweep process.They are the effects of additional velocity caused by varying sweep motion,the effects of flow hysteresis and viscosity.The additional velocity induced by sweep motion affects the transversal flow direction along the wing and the effective angle of attack at the airfoil profile.The physical properties of flow,the hysteresis and viscosity affect the unsteady aerodynamic characteristics by flow separation and induced vortexes.

关键词： Hysteresis Mechanism Numerical simulation Unsteady aerodynamic characteristics Variable-sweep wings

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One dimensional nickel phosphide polymorphic heterostructure as carbon-free functional support loading single-atom iridium for promoted electrocatalytic water oxidation

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Journal of Energy Chemistry 2023年第4期79卷 410-417页

作者： Rashid Mehmood Guifa Long Wenjun Fan Mingrun Li Lifang Liu Fuxiang Zhang StateKey Laboratory of Catalysis iChEMDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian National Laboratory for Clean EnergyDalian 116023LiaoningChina Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China GuangxiKey Laboratory of Chemistry and Engineering of Forest Products School of Chemistry and Chemical EngineeringGuangxi Minzu UniversityNanning 530008GuangxiChina

Although conducting materials such as carbon nanotube and carbon fiber paper(CFP)have been extensively employed as support of electrocatalytic active sites,most of them are of poor catalytic functionality by themselves and undesirable stability during strong acid/alkaline environments or oxidation process.Here we report a novel one-dimensional(1D)nickel phosphide polymorphic heterostructure(denoted as NPPH)to work as one effective carbon-free functional support for loading of single-atom Ir water oxidation electrocatalyst.Specifically,the NPPH composed of both Ni12P5and Ni2P phases is not only active for robust alkaline water oxidation but also is of good stability and hydrophilicity for favorable loading of single-atom dispersed iridium.The NPPH supported single-atom Ir electrocatalyst(Ir/NPPH)is found to exhibit remarkably superior water oxidation activity with respect to the NPPH itself or CFP supported single-atom Ir catalyst(Ir/CFP),demonstrating the synergetic promotion effect between NPPH and single-atom Ir catalyst.Furthermore,the NPPH supported single-atom Ir catalyst can bear alkaline water oxidation for over 120 h at current density of 50 mA cm^(-2).The NPPH developed here is expected as functional support to composite with other water oxidation catalysts,as may be an alternative strategy of developing highly efficient carbon-free electrocatalysts.

关键词： Oxygen evolution reaction Single atom catalyst Nickel phosphide Heterostructure One-dimensional

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Time-history performance optimization of flapping wing motion using a deep learning based prediction model

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Chinese Journal of Aeronautics 2024年第5期37卷 317-331页

作者： Tianqi WANG liu liu Jun LI lifang ZENG School of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310027China Huanjiang Laboratory Zhuji 311800China

Flapping Wing Micro Aerial Vehicles(FWMAVs)have caused great concern in various fields because of their high efficiency and maneuverability.Flapping wing motion is a very important factor that affects the performance of the aircraft,and previous works have always focused on the time-averaged performance optimization.However,the time-history performance is equally important in the design of motion mechanism and flight control system.In this paper,a time-history performance optimization framework based on deep learning and multi-island genetic algorithm is presented,which is designed in order to obtain the optimal two-dimensional flapping wing motion.Firstly,the training dataset for deep learning neural network is constructed based on a validated computational fluid dynamics method.The aerodynamic surrogate model for flapping wing is obtained after the convergence of training.The surrogate model is tested and proved to be able to accurately and quickly predict the time-history curves of lift,thrust and moment.Secondly,the optimization framework is used to optimize the flapping wing motion in two specific cases,in which the optimized propulsive efficiencies have been improved by over 40%compared with the baselines.Thirdly,a dimensionless parameter C_(variation)is proposed to describe the variation of the time-history characteristics,and it is found that C_(variation)of lift varies significantly even under close time-averaged performances.Considering the importance of time-history performance in practical applications,the optimization that integrates the propulsion efficiency as well as C_(variation)is carried out.The final optimal flapping wing motion balances good time-averaged and time-history performance.

关键词： FWMAV Flapping wing motion Deep learning Unsteady aerodynamic performance Optimization Time-history curve

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LSB page refresh based retention error recovery scheme for MLC NAND Flash

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Science China(Information Sciences) 2016年第4期59卷 121-131页

作者： Haozhi MA Lifang Liu Liyang PAN Jun XU Institute of Microelectronics Tsinghua University Tsinghua National Laboratory for Information Science and Technology

NAND Flash memories present inevitable decline in reliability due to scaling down and multilevel cell(MLC) technology. High retention error rate in highly program/erase(P/E) cycled blocks induces stronger ECC requirement in system, causing higher spare bits cost and hardware overhead. In this paper, a least significant bit(LSB) page refresh based retention recovery scheme is proposed to improve the retention reliability of highly scaled MLC NAND Flash. As in the scheme, LSB page refresh operation induces floating gate electron re-injection to compensate charge leakage during long retention time, and realizes retention error rate reduction. Experiment result on 2x-nm MLC NAND Flash exhibits more than 78% retention error rate reduction. Compared with reported retention error recovery scheme, the proposed scheme presents 2.5 times recovery efficiency promotion and 60% latency reduction.

关键词： NAND flash reliability retention refresh data error recovery

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Fault diagnosis based on dial-test data in datacenter networks

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Journal of Systems Engineering and Electronics 2019年第5期30卷 1035-1043页

作者： QI Xiaogang WANG Bingchun liu lifang School of Mathematics and Statistics Xidian UniversityXi’an 710071China School of Computer Science and Technology Xidian UniversityXi’an 710071China Xidian-Ningbo Information Technology Institute Ningbo 315200China

The fast growth of datacenter networks,in terms of both scale and structural complexity,has led to an increase of network failure and hence brings new challenges to network management systems.As network failure such as node failure is inevitable,how to find fault detection and diagnosis approaches that can effectively restore the network communication function and reduce the loss due to failure has been recognized as an important research problem in both academia and industry.This research focuses on exploring issues of node failure,and presents a proactive fault diagnosis algorithm called heuristic breadth-first detection(HBFD),through dynamically searching the spanning tree,analyzing the dial-test data and choosing a reasonable threshold to locate fault nodes.Both theoretical analysis and simulation results demonstrate that HBFD can diagnose node failures effectively,and take a smaller number of detection and a lower false rate without sacrificing accuracy.

关键词： datacenter network node failure proactive fault diagnosis

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SEM-Based Method for Performance Evaluation of Wired LANs

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Transactions of Nanjing University of Aeronautics and Astronautics 2018年第3期35卷 403-412页

作者： Qi Xiaogang Xu Chunxia liu lifang School of Mathematics and Statistics Xidian University School of Computer Science and Technology Xidian University

For wired local area networks(LANs),their effectiveness and invulnerability are very critical.It is extraordinarily significant to evaluate the network performance effectively in the design of a reasonable network topology and the performance improvement of the networks.However,there are many factors affecting the performance of the networks,and the relation among them is also complicated.How to evaluate the performance of the wired LANs more accurately has been a heavy challenge in the network research.In order to solve the problem,this paper presents a performance evaluation method that evaluates the effectiveness and invulnerability of the wired LANs.Compared to traditional statistical methods,it has the distinct advantage of being able to handle several dependent variables simultaneously and tolerates the measurement errors among these independent variables and dependent variables.Finally,the rationality and validity of this method are verified by the extensive experimental simulation.

关键词： wired local area networks(LANs) structural equation model(SEM) node contribution performance prediction network topology

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Research on performance of complex networks based on principal component analysis

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The Journal of China Universities of Posts and Telecommunications 2019年第1期26卷 40-48页

作者： Xu Chunxia Qi Xiaogang liu lifang School of Mathematics and Statistics Xidian University School of Computer Science and Technology Xidian University

For complex networks, their effectiveness and invulnerability are extremely important. With the development of complex networks, how to evaluate the effectiveness and invulnerability of these networks becomes an important research topic. The relationship among many influencing factors is very complicated, so it is essential to confirm the weighting coefficient of these influencing factors. Principal component analysis(PCA) is proposed to evaluate the performance of complex networks. It can improve one-sidedness of the single evaluation index and select different evaluation models according to different complex networks, which make the evaluation result more accurate. Performance of complex networks can be predicted according to comprehensive evaluation model. To verify the rationality and validity of this method, several small-world networks with different probability values and scale-free network are chosen to evaluate the network performance. Finally, simulation results show that PCA can be applied to performance evaluation of complex networks.

关键词： complex networks network topology principal component analysis performance prediction

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Association of TRIM22 with the type 1 interferon response during primary human cytomegalovirus infection in THP-1 macrophages

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BIOCELL 2019年第4期43卷 285-291页

作者： WEI LI HUIHUI GAO RAN TAO Lifang Liu SHIQIANG SHANG Department of Clinical Laboratory the Children’s HospitalZhejiang University School of MedicineNational Clinical Research Center For Child HealthHangzhou310052China

As a response factor of interferon,tripartite motif(TRIM)22 was reported to exert antiviral activity against viruses.In this study,THP-1 macrophages were infected with human cytomegalovirus(HCMV)to establish the HCMV lytic infection model.The mRNA levels of interleukin-6(IL-6),tumor necrosis factor-alpha(TNF-α)and interferonbeta(IFN-β)were significantly up-regulated in THP-1 macrophages at different infection time and titers.Moreover,for the first time,upregulation of TRIM22 expression was found during HCMV infection at both mRNA and protein levels in THP-1 macrophages.Furthermore,IFN-β could induce TRIM22 expression in THP-1 macrophages or HCMV infected THP-1 macrophages.Depletion of TRIM22 increased replication activity of HCMV with increasing of HCMV titers and HCMV proteins.In conclusion,it is the first report that HCMV can induce TRIM22 activation through IFN-β signaling and TRIM22 can suppress replication of HCMV in THP-1 macrophages.

关键词： Human cytomegalovirus TRIM22 IFN-βReplication

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Individualized Treatment and Palliative Care for A90-Year-Old Patient with Primary Gastric Diffuse Large-B Cell Lymphoma:4 Year Follow-up and Inspiration

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Chinese Medical Sciences Journal 2021年第1期36卷 72-77页

作者： Yanjie Cao Jingqi Duan Lifang Liu Xuan Wei Li Ren Lanning Zhang Wei Zhang Department of Geriatrics Air Force Medical CenterBeijing 100142China Department of Pathology Air Force Medical CenterBeijing 100142China

A 90-year-old man was diagnosed with primary gastric diffuse large B-cell lymphoma(PGDLBL)by PET/CT examination,gastroscopy,biopsy and histopathological analysis at a regular physical check in April,2016.The patient received R-CO chemotherapy(rituximab,cyclophosphamide,and vincristine)and radiotherapy subsequently,with enteral nutritional treatment through 3-cavity nasogastric tube due to development of pyloric obstruction.To satisfy patient's strong desire of eating by himself,we performed surgery of exploratory laparotomy and Roux-en-Y gastric bypass(RGB)to relieve pylorus obstruction.Postoperatively,the patient resumed oral feeding,supplemented by nasogastric tube feeding at 1350-1550 Kcal daily.He is now 94 years old with fairly well nutrition and normal communication.The outcome of 4 year follow-up suggests that nutritional treatment and palliative medicine are important for improving prognosis and life-quality of very elderly patients with end-stage tumors apart from the effective chemotherapy,radiotherapy,and surgery.

关键词： primary gastric lymphoma diffuse large B-cell lymphoma very elderly patient nutritional treatment palliative care

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TGR5 deficiency activates antitumor immunity in non-small cell lung cancer via restraining M2 macrophage polarization

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Acta Pharmaceutica Sinica B 2022年第2期12卷 787-800页

作者： lifang Zhao Hongyan Zhang Xueqing liu Shan Xue Dongfang Chen Jing Zou Handong Jiang Department of Respiratory and Critical Care Medicine Ren Ji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai 200127China

The bile acid-responsive G-protein-coupled receptor TGR5 is expressed in monocytes and macrophages,and plays a critical role in regulating inflammatory response.Our previous work has shown its role in promoting the progression of non-small cell lung cancer(NSCLC),yet the mechanism remains unclear.Here,using Tgr5-knockout mice,we show that TGR5 is required for M2 polarization of tumorassociated macrophages(TAMs)and suppresses antitumor immunity in NSCLC via involving TAMsmediated CD8+T cell suppression.Mechanistically,we demonstrate that TGR5 promotes TAMs into protumorigenic M2-like phenotypes via activating c AMP-STAT3/STAT6 signaling.Induction of c AMP production restores M2-like phenotypes in TGR5-deficient macrophages.In NSCLC tissues from human patients,the expression of TGR5 is associated with the infiltration of TAMs.The co-expression of TGR5 and high TAMs infiltration are associated with the prognosis and overall survival of NSCLC patients.Together,this study provides molecular mechanisms for the protumor function of TGR5 in NSCLC,highlighting its potential as a target for TAMs-centric immunotherapy in NSCLC.

关键词： TGR5 Bile acids Tumor-associated macrophages(TAMs) Tumor microenvironment(TME) Non-small cell lung cancer(NSCLC) Antitumor immunity Immunotherapy c AMP-STAT3/STAT6

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