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Improved Statically Solvable Slice Method for Slope Stability Analysis

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Journal of Earth Science 2022年第5期33卷 1190-1203页

作者： Aijun Su mingquan feng Shan Dong Zongxing Zou Jinge Wang Badong National Observation and Research Station of Geohazards China University of GeosciencesWuhan430074China Three Gorges Research Center for Geohazards China University of GeosciencesWuhan430074China Changjiang Geotechnical Engineering Corporation Wuhan430074China

Although slice methods are simple and effective slope stability analysis approaches,they are statically *** modifications of the slice method,such as the Spencer,MorgensternPrice,and Chen-Morgenstern methods,are statically determinate and solvable as they assume the inter-slice force inclination angle;however,there is a small gap between the assumptions and actual landslide stability *** reasonable theoretical analysis,the Su slice method provides a reliable approach for determining the inter-slice force inclination angle that can be used in slice analysis to accurately analyse,calculate,and evaluate the stability of ***,the Su slice method requires further research and analysis,especially in terms of the parameter values sinλbiandρ.In this study,we investigated more accurate methods for calculating the parameters sinλbiandρ.In addition,an adjustment coefficient(μ)was introduced to improve the solution method for the inter-slice force inclination *** inter-slice force inclination and safety factors of three landslides with arc-shaped slip surfaces and one landslide with a polyline-shaped slip surface were analysed and compared using the different slice *** improved inter-slice force inclination not only satisfies the calculation of static force equilibrium condition but also satisfies the calculation of both the force and moment equilibrium *** improved method for calculating inter-slice force inclination presented the best *** safety factors calculated using the improved Su slice method were close to those obtained using numerical simulations and the Morgenstern-Price *** negligible differences among the safety factors calculated using the Su slice,improved Su slice,and M-P methods,the accuracy of the improved Su slice method was better than the M-P method in terms of inter-slice force inclination angles which can be useful to improve protection engineering design.

关键词： slope stability limit equilibrium analysis slice method inter-slice force inclination geological hazards

AN ADVANCED DUAL-FREQUENCY POSITIONING ALGORITHM FOR SATELLITE NAVIGATION RECEIVERS

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Journal of Electronics(China) 2009年第4期26卷 466-472页

作者： Liu Jiaxing Lu mingquan feng Zhenming Department of Electronic Engineering Tsinghua University Beijing 100084 China

With the development of the Ground Positioning System (GPS) modernization and the expectable implementation of Galileo, people pay more and more attention to civil applications on multi-frequency signals. This paper proposes a new and advanced positioning algorithm for the dual-frequency satellite navigation receivers, concerning the various influences of all the ranging error sources and taking advantage of the Klobuchar single-frequency ionospheric model. The paper also presents positioning precision provided by the new algorithm. Theoretical analysis and experimental results show that, the new dual-frequency positioning algorithm can achieve higher positioning accu- racy than the single-frequency positioning algorithm and the traditional dual-frequency positioning algorithm.

关键词： Satellite navigation Dual-frequency positioning Klobuchar model Positioning accuracy

Mapping and overlapping based carrier frequency searching technique for rapid GNSS long PN-code acquisition

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Science China(Information Sciences) 2010年第12期53卷 2642-2652页

作者： LI Hong ,LU mingquan & feng ZhenMing Department of Electronic Engineering,Tsinghua University,Beijing 100084,China Department of Electronic Engineering Tsinghua University

In global navigation satellite systems(GNSS),because of the long period and high chip rate of long pseudo-noise(PN) code,the rapid acquisition is hard to *** speed up search process,in the paper,a mapping and overlapping based carrier frequency searching technique is *** mapping incoming signals of the same interval to different carrier frequency cells and overlapping together the mapped incoming signals that correspond to the same code phase,the technique reduces the number of the cells to be *** effect of the technique on detection and mean acquisition time performance is *** is shown that the technique reduces the cells to be searched and shortens mean acquisition time at the expense of degrading detection *** technique is fit to the previously published acquisition methods and is capable of improving their mean acquisition time *** and simulation results validate the analysis.

关键词： carrier frequency cells mapping overlapping acquisition performance

Numerically stable method of signal subspace estimation based on multistage Wiener filter

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Science China(Information Sciences) 2010年第12期53卷 2620-2630页

作者： ZHUANG XueBin ,CUI XiaoWei,LU mingquan & feng ZhenMing Department of Electronic Engineering,Tsinghua University,Beijing 100084,China Department of Electronic Engineering Tsinghua University

In this paper,a numerically stable method of signal subspace estimation based on Householder multistage Wiener filter(HMSWF) is *** stability of the method lies on the fact that the Householder matrix in HMSWF ensures the unitary blocking operation and significantly strengthens the orthogonality of basis vectors,especially in the finite-precision *** the following,we analyze the numerical stability of HMSWF and MSWF based on the correlation subtractive structure(CSS-MSWF) by establishing the equivalence between the forward recursion of MSWF and the Arnoldi algorithm in numerical linear ***,the equivalence between HMSWF and the Householder QR decomposition(QRD) on the Krylov matrix underlying in MSWF is directly *** on the relationship,two theoretical upper bounds of the orthogonality error of basis vectors in signal subspace are obtained and it is demonstrated that the orthogonality of basis vectors based on HMSWF is perfectly preserved by the numerically well-behaved Householder matrix,and the corresponding signal subspace estimation is much more numerically stable than that based on *** show the numerical stability of the proposed method of signal subspace estimation by HMSWF.

关键词： multistage Wiener filter subspace estimation Householder transform numerical stability Arnoldi algorithm

Ferroptosis mechanism and Alzheimer's disease

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Neural Regeneration Research 2024年第8期19卷 1741-1750页

作者： Lina feng Jingyi Sun Ling Xia Qiang Shi Yajun Hou Lili Zhang mingquan Li Cundong Fan Baoliang Sun Shandong Key Laboratory of TCM Multi-Target Intervention and Disease Control the Second Affiliated Hospital of Shandong First Medical UniversityTaianShandong ProvinceChina Department of Internal Medicine Taian Traffic HospitalTaianShandong ProvinceChina Department of Neurology the Third Affiliated Clinical Hospital of Changchun University of Chinese MedicineChangchunJilin ProvinceChina

Regulated cell death is a genetically determined form of programmed cell death that commonly occurs during the development of living *** process plays a crucial role in modulating homeostasis and is evolutionarily conserved across a diverse range of living *** is a classic regulatory mode of cell *** studies of regulatory cell death in Alzheimer’s disease have yielded increasing evidence that fe rroptosis is closely related to the occurrence,development,and prognosis of Alzheimer’s *** review summarizes the molecular mechanisms of ferroptosis and recent research advances in the role of ferro ptosis in Alzheimer’s *** findings are expected to serve as a theoretical and experimental foundation for clinical research and targeted therapy for Alzheimer’s disease.

关键词： Alzheimer’s disease apolipoprotein E Fe^(2+) ferroptosis glial cell glutathione peroxidase 4 imbalance in iron homeostasis lipid peroxidation regulated cell death system Xc^(-)

Carbon nanotube films with ultrahigh thermal-shock and thermalshock-fatigue resistance characterized by ultra-fast ascending shock testing

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Nano Research 2024年第8期17卷 6777-6784页

作者： mingquan Zhu Shijun Wang Yunxiang Bai feng Gao Zhenxing Zhu Congying Wang Peng Zhang Hao Jin Hui Zhang Luqi Liu Zhiping Xu Xinghong Zhang Fei Wei Zhong Zhang CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical EngineeringTsinghua UniversityBeijing 100084China Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Center for Composite Materials and StructuresHarbin Institute of TechnologyHarbin 150001China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China

The exploration of material failure behavior not only involves defining its limits and underlying mechanisms but also entails devising strategies for improvement and protection in extreme ***'ve pioneered an advanced multi-scale,high-speed ascending thermal shock testing platform capable of inducing unprecedented heat shocks at rates surpassing 105℃/*** meticulous examination of the thermal shock responses of carbon nanotube(CNT)films,we've achieved remarkable *** employing an innovative macro-scale synchronous tightening and relaxing approach,we've attained a critical temperature differential in CNT films that exceeds an exceptional 2500℃—surpassing any previously reported metric for highperformance,thermal-shock-resistant ***,these samples have demonstrated exceptional resilience,retaining virtually unchanged strength even after enduring 10,000 thermal shock cycles at temperatures exceeding 1000℃.Furthermore,our research has revealed a novel thermal shock/fatigue failure mechanism that fundamentally diverges from conventional theories centered on thermal stress.

关键词： carbon nanotubes failure behavior thermal shock characterization

Fabricating bio-inspired high impact resistance carbon nanotube network films for multi-protection under an extreme environment

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Nano Research 2024年第9期17卷 7793-7802页

作者： mingquan Zhu Kailu Xiao Wei Zhang Xudong Lei Yunxiang Bai Shijun Wang Peng Zhang feng Gao Congying Wang Wenqiang Xu Huiyong Li Xianqian Wu Chao Wang Hui Zhang Luqi Liu Zhong Zhang CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Department of Materials Science and Engineering Texas A&M UniversityCollege StationTexas 77840USA Institute of Mechanics Chinese Academy of SciencesBeijing 100190China School of Astronautics Harbin Institute of TechnologyHarbin150001China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China

The fabrication of light-weight,highly impact-resistant,and energy-absorbent materials is urgently demanded in many facets of the society from body armor to aerospace engineering,especially under an extreme *** nanotubes(CNTs),one of the strongest and toughest materials ever found,also have good conductivity,chemical stability,and thermal stability,etc,making them a competitive candidate as building blocks to help achieve the above *** this work,a kind of CNT network was prepared by using chlorosulfonic acid(CSA)to release the internal stress of super-aligned carbon nanotube films(SA-CNTF)and dendritic polyamide amine(PAMAM)to further introduce multiple hydrogen bonds and interlocking *** fabricated bioinspired carbon nanotube network films(PAMAM@C-CNTF)have a high toughness of 45.97 MJ/m3,showing an increase of 420%compared to neat *** importantly,the anti-impact performance of the films(e.g.,with a maximum specific energy absorption of 1.40 MJ/kg under 80-100 m/s projectile impact)is superior to that of conventional protective materials from steel and Kevlar fiber,and also exceeds that of any other reported carbon-based *** hierarchical energy dissipation mechanism was further revealed through experiment and *** functions including intelligent heating/anti-icing,ultraviolet protection,as well as electromagnetic interference shielding properties make these network films have great potential in practical multi-protection applications,especially under an extreme environment.

关键词： carbon nanotubes composites mechanical properties multi-function

A Vector Tracking Loop Based on ML Estimation in Dynamic Weak Signal Environments

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A Vector Tracking Loop Based on ML Estimation in Dynamic Wea...

A novel method for AFRPs burrs removal:Principle of mechanochemo-induced fiber fracture

第三届中国卫星导航学术年会

作者： Jing Liu, Xiaowei Cui, mingquan Lu and Zhenming feng Department of Electronic Engineering, Tsinghua University, Beijing, China

Vehicle positioning with GNSS in urban environments faces two problems which are attenuation and dynamic. In the tracking loops of traditional GNSS receivers, using non-coherent discriminators, thermal noise error and dynamic stress threshold are contradictory. Thus, it is difficult for the traditional tracking loops using non-coherent discriminators to track weak signals in dynamic environments. In order to improve the tracking sensitivity of GNSS receiver in dynamic weak signal environments, a Joint Vector Position Tracking Loop （JVPTL） is proposed in the paper, in which the design of discriminator is based on Maximum Likelihood Estimation （MLE） according to the linear model of received baseband signal. Thus, the discriminator in the JVPTL is a coherent discriminator, which has relatively small discriminating errors and is able to ease the contradiction between thermal noise error and dynamic stress threshold. Moreover, the JVPTL tracks user position and velocity directly and takes full advantage of the coupling between codes and carriers of all visible satellite signals to reduce thermal noise error. Therefore, the proposed JVPTL is able to track dynamic weak signal. Simulation results show that in dynamic weak signal environments, the JVPTL performs better than the VDFLL with non-coherent discriminators.

关键词： Weak Signal·Dynamic·ML Estimation·Vector Tracking Loop·Coherent Discriminator

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Chinese Journal of Aeronautics 2024年第7期37卷 522-538页

作者： Jie XU Bo LI Pingfa feng Qiang WANG feng feng Division of Advanced Manufacturing Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Changhe Aircraft Industry(Group)Co.Ltd Jingdezhen 333000China

Burrs generated during the machining of Aramid-Fiber-Reinforced Composites(AFRPs)pose a challenge for the production efficiency of aircraft and helicopter housing *** studies have generally attempted to suppress burrs by referring to delamination suppression *** contrast to stratification,burrs are remediable machining *** such,a mechanochemical method with burrs trimming technological strategy are implemented to effectively combat ***,we clarify the mechanism by which aramid fibers cannot be cut off using analytical and numerical *** addition,the mechanism of fiber fracture with Modified Polyurethane Reactive Polymer(M-PUR),and development of anti-burr devices(thermostatic adhesive sealed generator)are ***,the experimental results show that the reduction rate in burr length is 87%-91%through the mechanochemical *** method not only opens a new avenue to solve the burr problem of aramid fibers but also builds an interdisciplinary bridge between polymer science and composite machining.

关键词： Mechanochemical method Burrs Orthogonal cutting Aramid fiber-reinforced composites Milling