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Bioinspired Scraper-File Type Frequency-Doubling Ultrasonic Exciter

Journal of Bionic Engineering 2024年第4期21卷 1801-1816页

作者： Wenshuai Wu Mingshuo Zhang Zeming Li Guang Yao Xinggang Jiang Deyuan Zhang School of Mechanical Engineering and Automation Beihang UniversityBeijing100191China Institute of Bionic and Micro-Nano Systems Beihang UniversityBeijing100191China Guangdong Provincial Key Laboratory of Minimally Invasive Surgical Instruments and Manufacturing Technology Guangdong University of TechnologyGuangzhou510006China

In the natural world,leaf-cutting ants cause vibrations through their mutual scraping of file-scraper *** this study,we designed a Biomimetic Ultrasonic Exciter(BUE)that imitates leaf-cutting *** operating characteristics of the BUE were studied through experimental testing and finite element *** results showed that the BUE could generate stable ultrasonic vibrations,and that the excitation frequency only needed to be half the Output Frequency(OF).This frequency-doubling phenomenon was conducive to achieving BUE *** further explore the phenomenon of frequency-doubling vibration output,this study designed scrapers of five different sizes,conducted excitation and first-order natural frequency measurement tests,and the corresponding finite element *** was found that each scraper could operate in frequency-doubling mode,but the operating frequency and natural mode frequencies did not correspond with one *** further explicate experimental and simulation results,a two-degrees-of-freedom vibration model was *** was evident that the contact relationship between the dentate disc and scraper introduced strong nonlinear factors into the system,accounting for the frequency-doubling phenomenon and the difference between the BUE’s operating and mode *** BUE could be expected to facilitate the production of high-power micro-ultrasonic generators and has potential application value in the fields of mechanical processing,industrial production,and medical health.

关键词： Leaf-cutting ants Power ultrasound Nonlinear vibration Ultrasonic scalpel Micro vibrator

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Effects and mechanisms of Helicobacter pylori infection on the occurrence of extra-gastric tumors

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World Journal of Gastroenterology 2024年第37期30卷 4090-4103页

作者： Shi-Qing Zhao Hui-Ling Zheng Xiao-Tian Zhong Zi-Ye Wang Yi Su Yan-Yan Shi Research Center of Clinical Epidemiology Peking University Third HospitalBeijing 100191China Health Science Center Peking UniversityBeijing 100191China Department of Gastroenterology Peking University Third HospitalBeijing 100191China

Helicobacter pylori(***)colonizes the human stomach and many studies have discussed the mechanisms of *** infection leading to gastric diseases,including gastric ***,increasing data have shown that the infection of *** may contribute to the development of extra-gastric diseases and ***,systemic immune responses,microbiome disorders,and hypergastrinemia caused by *** infection are associated with many extra-gastric *** review highlights recent discoveries;discusses the relationship between *** and various extra-gastric tumors,such as colorectal cancer,lung cancer,cholangiocarcinoma,and gallbladder carcinoma;and explores the mechanisms of extra-gastric carcinogenesis by ***,these findings refine our understanding of the pathogenic processes of ***,provide guidance for the clinical treatment and management of ***-related extra-gastric tumors,and help improve prognosis.

关键词： Helicobacter pylori Extra-gastric tumors Immune system response Mucosal barrier Gut microbiome

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Random Forest-Based Fatigue Reliability-Based Design Optimization for Aeroengine Structures

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 665-684页

作者： Xue-Qin Li Lu-Kai Song School of Energy and Power Engineering Beihang UniversityBeijing100191China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityKowloonHong Kong999077China Research Institute of Aero-Engine Beihang UniversityBeijing100191China

Fatigue reliability-based design optimization of aeroengine structures involves multiple repeated calculations of reliability degree and large-scale calls of implicit high-nonlinearity limit state function,leading to the traditional direct Monte Claro and surrogate methods prone to unacceptable computing efficiency and *** this case,by fusing the random subspace strategy and weight allocation technology into bagging ensemble theory,a random forest(RF)model is presented to enhance the computing efficiency of reliability degree;moreover,by embedding the RF model into multilevel optimization model,an efficient RF-assisted fatigue reliability-based design optimization framework is *** the low-cycle fatigue reliability-based design optimization of aeroengine turbine disc as a case,the effectiveness of the presented framework is *** reliabilitybased design optimization results exhibit that the proposed framework holds high computing accuracy and computing *** current efforts shed a light on the theory/method development of reliability-based design optimization of complex engineering structures.

关键词： Random forest reliability-based design optimization ensemble learning machine learning

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A novel neuroprotective method against ischemic stroke by accelerating the drainage of brain interstitial fluid

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Science China(Life Sciences) 2024年第10期67卷 2213-2223页

作者： Jingge Lian Liu Yang Hanbo Tan Shaoyi Su Leonor Serrano Lopes Fangxiao Cheng Junhao Yan Yu Fu Wanyi Fu Zhaoheng Xie Jianfei Sun Jicong Zhang Zhiqian Tong Yajuan Gao Hongbin Han Department of Radiology Peking University Third HospitalBeijing 100191China Beijing Key Laboratory of Magnetic Resonance Imaging Technology Beijing 100191China Institute of Medical Technology Peking University Health Science CenterBeijing 100191China Department of Informatics Technical University of MunichGarching 80539Germany Department of Anatomy and Histology School of Basic Medical SciencesPeking UniversityBeijing 100191China Department of Neurology Peking University Third HospitalBeijing 100191China Department of Electronic Engineering Tsinghua UniversityBeijing 100084China State Key Laboratory of Bioelectronics School of Biological Science and Medical EngineeringSoutheast UniversityNanjing 210096China School of Biological Science and Medical Engineering Beihang UniversityBeijing 100191China Key Laboratory of Alzheimer’s Disease of Zhejiang Province Institute of AgingSchool of Mental HealthWenzhou Medical UniversityWenzhou 325035China NMPA Key Laboratory for Evaluation of Medical Imaging Equipment and Technique Beijing 100191China

Ischemic stroke is a leading cause of death and disability *** response after stroke determines the outcome of ischemic injury.A recent study has reported an efficient method,epidural arterial implantation(EAI),for accelerating interstitial fluid(ISF)drainage,which provides a promising strategy to clear pro-inflammatory cytokines in the brain extracellular space(ECS).In this study,the method of EAI was modified(m-EAI)to control its function of accelerating the ISF drainage at different time points following ischemic *** neuroprotective effect of m-EAI on ischemic stroke was evaluated with the transient middle cerebral artery occlusion(tMCAO)rat *** results demonstrated the accumulation of IL-1β,IL-6,and TNF-αwas significantly decreased by activating m-EAI at 7 d before and immediately after ischemic attack in tMCAO rats,accompanied with decreased infarct volume and improved neurological *** study consolidates the hypothesis of exacerbated ischemic damage by inflammatory response and provides a new perspective to treat encephalopathy via brain *** research is essential to investigate whether m-EAI combined with neuroprotective drugs could enhance the therapeutic effect on ischemic stroke.

关键词： ischemic stroke brain extracellular space interstitial fluid modified epidural arterial implantation

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Identification of aircraft longitudinal aerodynamic parameters using an online corrective test for wind tunnel virtual flight

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Chinese Journal of Aeronautics 2024年第9期37卷 261-275页

作者： Shang TAI Chen BU Yanling WANG Ting YUE Hailiang LIU Lixin WANG School of Aeronautical Science and Engineering Beihang UniversityBeijing 100191China AVIC Aerodynamics Research Institute Harbin 150001China

The identification of aerodynamic parameters is accomplished through the test data of the dynamic movement of scaled aircraft models flying dynamically in wind tunnel,which can real-ize the accurate acquisition of the aerodynamic model of the aircraft in the preliminary stage for aircraft design,and it is of great significance for improving the efficiency of aircraft ***-ever,the translational motion of the test model in the wind tunnel virtual flight is subject to con-straints that result in distinct flight dynamics compared to free *** constraints have implications for the accuracy of aerodynamic derivatives obtained through the identification of wind tunnel test *** this issue in mind,the research studies the differences in longitudinal dynamic characteristics between unconstrained free flight and wind tunnel virtual flight,and inno-vatively proposes an online correction test based wind tunnel virtual flight test *** lon-gitudinal trajectory and velocity changes of the model are solved online by the aerodynamic forces measured during the test,and then the coupled relationship between aircraft translation and rota-tion is used to correct the model's pitch attitude motion *** the first time,the problem of solving the data approximation for free flight has been solved,eliminating the difference between the dynamics of wind tunnel virtual flight and free flight,and improving the accuracy of the aero-dynamic derivative identification *** experiment's findings show that accurate aerodynamic derivatives can be identified based on the online correction test data,and the observed behaviour of the identified motion model has similarities to that of the free flight motion model.

关键词： Wind tunnels Displacement constraints Online solution Flightcontrol law Aerodynamic parameter identification

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All-inorganic ultrathin high-sensitivity transparent temperature sensor based on a Mn-Co-Ni-O nanofilm

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Microsystems & Nanoengineering 2024年第3期10卷 195-205页

作者： Yuanyuan Cui Mengwei Sun Changbo Liu Yuan Deng Research Institute for Frontier Science Beihang UniversityBeijing 100191China School of Materials Science and Engineering Beihang UniversityBeijing 100191China Key Laboratory of Intelligent Sensing Materials and Chip Integration Technology of Zhejiang Province Hangzhou Innovation Institute of Beihang UniversityHangzhou 310051China

The demand for optically transparent temperature sensors in intelligent devices is ***,the performance of these sensors,particularly in terms of their sensitivity and resolution,must be further *** study introduces a novel transparent and highly sensitive temperature sensor characterized by its ultrathin,freestanding design based on a Mn-Co-Ni-O *** Mn-Co-Ni-O-based sensor exhibits remarkable sensitivity,with a temperature coefficient of resistance of−4%℃^(−1),and can detect minuscule temperature fluctuations as small as 0.03℃.Additionally,the freestanding sensor can be transferred onto any substrate for versatile application while maintaining robust structural stability and excellent resistance to interference,indicating its suitability for operation in challenging *** practical utility in monitoring the surface temperature of optical devices is demonstrated through vertical integration of the sensor and a micro light-emitting diode on a polyimide ***,an experiment in which the sensor is implanted in rats confirms its favorable biocompatibility,highlighting the promising applications of the sensor in the biomedical domain.

关键词： transparent sensor versatile

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Formation mechanism of Fe-based amorphous powders produced by spark erosion

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Journal of Materials Science & Technology 2024年第3期170卷 33-46页

作者： Chekai Liu Ran Li Jiazi Bi Ding Ma Xiaobin Liu Tao Zhang School of Materials Science and Engineering Key Laboratory of Aerospace Materials and Performance(Ministry of Education)Beihang UniversityBeijing 100191China

Spark erosion is a convenient,flexible,and low-cost method to quickly produce fine powders of metals,alloys,and semiconductors in size ranging from nearly a hundred micrometers to submicrometer by repetitive spark *** to the complexity of the powder-forming journey,normally accompanied by high temperature,high pressure,decomposition,diffusion and rapid quenching caused by discharge plasma,the mechanisms of powder formation and possible contaminant infiltration are still controversial,posing a significant challenge to control particle size and chemical composition of the powder produced by this *** this study,Fe-based amorphous powders in different particle-size distributions with high sphericity were fabricated by spark erosion under different discharge-energy *** max-imum particle size of the resultant powders can be correlated with discharge parameters,crater depth,and crater radius,respectively.A multi-ring-breakup model is proposed to reveal the particle-size distribution of the powder formed from the electrode melt under a single-pulse ***,a dielectric-element infiltration model is provided to quantitatively evaluate the infiltration mass ratio of the contaminant elements,stemming from the decomposed products of dielectric liquid,in the resultant powder with different particle *** models verified through the experimental data are significant for the development of high-performance fine Fe-based amorphous powder with controlled particle size and chemical composition.

关键词： Amorphous alloy Particle Spark erosion Infiltration Modeling

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Hydrogel dressings on neurotrophic keratitis in an experimental animal model

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International Journal of Ophthalmology(English edition) 2024年第8期17卷 1396-1402页

作者： Hua-Qin Xia Xiao-Dan Jiang Yi-Fan Song Xue-Min Li Yan-Jie Tian Department of Ophthalmology Peking University Third HospitalBeijing 100191China Beijing Key Laboratory of Restoration of Damaged Ocular Nerve Peking University Third HospitalBeijing 100191China

AIM:To investigate the therapeutic effects of hydrogel dressings on neurotrophic keratitis in ***:Male Wistar rats,aged 42–56d,were randomly divided into control,experimental,and treatment groups,each consisting of five *** experimental and treatment groups underwent neurotrophic keratitis modeling in both *** successful modeling,biomedical hydrogels formed with polyvinyl alcohol and polyvinyl pyrrolidone were used in treatment group for *** irritation response and keratitis index scores,Schirmer’s test,tear film break-up time(BUT),sodium fluorescein staining,and hematoxylin and eosin(HE)staining were used to evaluate the effectiveness of the ***:The neurotrophic keratitis model was successfully established in rats with severe ophthalmic nerve injury,characterized by keratitis,ocular irritation,reduced tear secretion measured by decreased BUT and Schirmer test values,corneal epithelial loss,and disorganized collagen fibers in the stromal *** treatment with hydrogel dressings,significant improvements were observed in keratitis scores and ocular irritation symptoms in model *** the recovery of tear secretion,as measured by the Schirmer’s test,did not show statistical differences,BUT was significantly *** staining confirmed a reduction in the extent of corneal epithelial loss after *** staining revealed the restoration of the structural disorder in both the epithelial and stromal layers to a certain ***:Hydrogel dressing reduces ocular surface irritation,improves tear film stability,and promotes the repair and restoration of damaged epithelial cells by maintaining a moist and clean environment on the ocular surface in the rat model.

关键词： neurotrophic keratitis hydrogel corneal epithelial cells rat

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Direct numerical simulation of shock wave/boundary layer interaction controlled by steady microjet in a compression ramp

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Chinese Journal of Aeronautics 2024年第10期37卷 83-102页

作者： Ruoye XIAO Dong SUN Jian YU School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China State Key Laboratory of Aerodynamics Mianyang 621000China

Shock wave/boundary layer interaction in a 24°turning angle of the compression ramp at Mach number 2.9 controlled by steady microjet is investigated using direct numerical *** different jet spacings which are termed as sparse,moderate and dense are considered,and the induced vortex system and shock structures are compared.A moderate jet spacing configuration is found to generate counter-rotating vortex pairs that transport high-momentum fluid towards the vicinity of wall and strengthen the boundary layer to resist separation,reducing the separation *** dense jet spacing configuration creates a larger momentum deficit region,reducing the friction downstream of the *** of pressure and pressure gradient reveals that dense jet spacing configuration reduces the intensity of separation *** impact of varying jet spacings on the turbulent kinetic energy transport mechanism is also investigated by decomposing the budget terms in the transport ***,the spectral characteristics of the separation region are studied using power spectral density and dynamic mode decomposition methods,revealing that moderate jet spacing configuration suppresses low-frequency fluctuations in the separation region.

关键词： Shock wave/boundary layer interaction Compression ramp Steady microjet Different jet spacings Direct numerical simulation

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Porous Ti_(3)C_(2)T_(x) MXene nanosheets sandwiched between polyimide fiber mats for electromagnetic interference shielding

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Nano Research 2024年第3期17卷 2070-2078页

作者： Wenhao Liang Juntao Wu Shan Zhang Pei-Yan Zhao Yi Cong Yongqiang Guo Guang-Sheng Wang Key Laboratory of Bioinspired Smart Interfacial Science and Technology of Ministry of Education School of ChemistryBeihang UniversityBeijing 100191China

With the rapid development of wireless communication technology and electronic devices,the issue of electromagnetic interference(EMI)is becoming increasingly *** a new and flexible electromagnetic interference shielding material has become a challenging ***,a sandwich-structured EMI shielding composite film was prepared using electrospinning and vacuum filtration *** this process,a porous MXene was synthesized through a reaction with cobalt acetate and served as the intermediate layer in the composite film to shield electromagnetic *** electrospun polyimide(PI)fibers were used as the top and bottom layers of the composite film,which can protect the porous MXene from *** lightweight and flexible composite film integrates electromagnetic interference shielding and thermal insulation capabilities,showing excellent comprehensive *** composite film achieves an EMI shielding effectiveness of 48.8 dB in X-band(8.2–12.4 GHz),and absolute shielding effectiveness of the composite film reached a satisfying 4142.43(dB·cm^(2))/*** to the design of a multi-layer porous structure,the density of the composite film is 0.65 g/***,the thermal conductivity of the film is 0.042 W/(m·K)due to the clamping of electrospun PI fibers,showing excellent thermal insulation ***,the composite film exhibits excellent high and low-temperature *** summary,this work provides a feasible strategy for preparing a lightweight polymer-based EMI shielding film.

关键词： porous MXene polyimide electromagnetic interference shielding thermal insulation

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