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Coaxial Wet Spinning of Boron Nitride Nanosheet‑Based Composite Fibers with Enhanced Thermal Conductivity and Mechanical Strength
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作者 Wenjiang Lu Qixuan Deng +3 位作者 Minsu Liu Baofu Ding Zhiyuan Xiong Ling Qiu 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第2期126-138,共13页
Hexagonal boron nitride nanosheets(BNNSs)exhibit remarkable thermal and dielectric properties.However,their self-assembly and alignment in macroscopic forms remain challenging due to the chemical inertness of boron ni... Hexagonal boron nitride nanosheets(BNNSs)exhibit remarkable thermal and dielectric properties.However,their self-assembly and alignment in macroscopic forms remain challenging due to the chemical inertness of boron nitride,thereby limiting their performance in applications such as thermal management.In this study,we present a coaxial wet spinning approach for the fabrication of BNNSs/polymer composite fibers with high nanosheet orientation.The composite fibers were prepared using a superacid-based solvent system and showed a layered structure comprising an aramid core and an aramid/BNNSs sheath.Notably,the coaxial fibers exhibited significantly higher BNNSs alignment compared to uniaxial aramid/BNNSs fibers,primarily due to the additional compressive forces exerted at the core-sheath interface during the hot drawing process.With a BNNSs loading of 60 wt%,the resulting coaxial fibers showed exceptional properties,including an ultrahigh Herman orientation parameter of 0.81,thermal conductivity of 17.2 W m^(-1)K^(-1),and tensile strength of 192.5 MPa.These results surpassed those of uniaxial fibers and previously reported BNNSs composite fibers,making them highly suitable for applications such as wearable thermal management textiles.Our findings present a promising strategy for fabricating high-performance composite fibers based on BNNSs. 展开更多
关键词 Boron nitride nanosheets coaxial fiber Interfacial compression Nanosheet aligning Wearable thermal management
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Experimental study on temperature fluctuations on plate surface induced by coaxial-jet flow
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作者 Xue-Yao Xiong Zun-Quan Liu +2 位作者 Guo-Yan Zhou Xing Luo Shan-Tung Tu 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第5期139-153,共15页
In nuclear reactors,temperature fluctuations of fluids may cause fatigue damage to adjacent structures;this is referred to as thermal striping.Research on thermal striping in the upper plenum has mainly focused on flu... In nuclear reactors,temperature fluctuations of fluids may cause fatigue damage to adjacent structures;this is referred to as thermal striping.Research on thermal striping in the upper plenum has mainly focused on fluid fields.Few experimental studies have been reported on solid structures in a fluid field with a coaxial jet.This study entailed an experimental study of the temperature fluctuations in the fluid and on a plate surface caused by a coaxial jet.The temperature fluctuations of the fluid and plate surfaces located at different heights were analyzed.The cause of the temperature fluctuation was analyzed using a transient temperature distribution.The results show that the mixing of the hot and cold fluids gradually becomes uniform in the positive axial direction.The average surface temperatures tended to be consistent.When the jet reaches the plate surface,the swing of the jet center,contraction and expansion of the cold jet,and changes in the jet shape result in temperature fluctuations.The intensity of the temperature fluctuation was affected by the position.More attention should be paid when the plate is located at a lower height,and between the hot and cold-fluid nozzles. 展开更多
关键词 Temperature fluctuation Thermal striping coaxial jet Thermal mixing The upper plenum of nuclear reactor
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Study of plasma parameters of coaxial plasma source using triple Langmuir probe and Faraday cup diagnostics
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作者 Sunil KANCHI Rohit SHUKLA Archana SHARMA 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第4期94-100,共7页
Coaxial plasma guns are a type of plasma source that produces plasma which propagates radially and axially controlled by the shape of the ground electrode, which has attracted much interest in several applications. In... Coaxial plasma guns are a type of plasma source that produces plasma which propagates radially and axially controlled by the shape of the ground electrode, which has attracted much interest in several applications. In this work, a 120° opening angle of CPG nozzle is used as a plasma gun configuration that operates at the energy of 150 J. The ionization of polyethylene insulator between the electrodes of the gun produces a cloud of hydrogen and carbon plasma.The triple Langmuir probe and Faraday cup are used to measure plasma density and plasma temperature. These methods are used to measure the on-axis and off-axis plasma divergence of the coaxial plasma gun. The peak values of ion densities measured at a distance of 25 mm on-axis from the plasma gun are(1.6±0.5)×10^(19)m^(-3)and(2.8±0.6)×10^(19)m^(-3)for hydrogen and carbon plasma respectively and the peak temperature is 3.02±0.5 eV. The mean propagation velocity of plasma is calculated using the transit times of plasma at different distances from the plasma gun and is found to be 4.54±0.25 cm/μs and 1.81±0.18 cm/μs for hydrogen and carbon plasma respectively. The Debye radius is obtained from the measured experimental data that satisfies the thin sheath approximation. The shot-to-shot stability of plasma parameters facilitates the use of plasma guns in laboratory experiments. These types of plasma sources can be used in many applications like plasma opening switches, plasma devices, and as plasma sources. 展开更多
关键词 coaxial plasma source triple Langmuir probe Faraday cup plasma density plasma temperature
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Numerical Simulation of Droplet Generation in Coaxial Microchannels
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作者 Zongjun Yin Rong Su Hui Xu 《Fluid Dynamics & Materials Processing》 EI 2024年第3期487-504,共18页
In this study,numerical simulations of the pinching-off phenomena displayed by the dispersed phase in a continuous phase have been conducted using COMSOL Multiphysics(level-set method).Four flow patterns,namely“drop ... In this study,numerical simulations of the pinching-off phenomena displayed by the dispersed phase in a continuous phase have been conducted using COMSOL Multiphysics(level-set method).Four flow patterns,namely“drop flow”,“jet flow”,“squeeze flow”,and“co-flow”,have been obtained for different flow velocity ratios,channel diameter ratios,density ratios,viscosity ratios,and surface tension.The flow pattern map of two-phase flow in coaxial microchannels has been obtained accordingly,and the associated droplet generation process has been critically discussed considering the related frequency,diameter,and pinch-off length.In particular,it is shown that the larger the flow velocity ratio,the smaller the diameter of generated droplets and the shorter the pinch-off length.The pinch-off length of a droplet is influenced by the channel diameter ratio and density ratio.The changes in viscosity ratio have a negligible influence on the droplet generation pinching frequency.With an increase in surface tension,the frequency of generation and pinch-off length of droplets decrease,but for small surface tension the generation diameter of droplet increases. 展开更多
关键词 Droplet generation characteristics coaxial microchannels flow patterns pinch-off length
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Percutaneous ultrasound-guided coaxial core needle biopsy for the diagnosis of multiple splenic lesions: A case report
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作者 Sha-Hong Pu Wu-Yong-Ga Bao +2 位作者 Zhen-Peng Jiang Rui Yang Qiang Lu 《World Journal of Gastrointestinal Surgery》 SCIE 2024年第2期616-621,共6页
BACKGROUND The overlap of imaging manifestations among distinct splenic lesions gives rise to a diagnostic dilemma.Consequently,a definitive diagnosis primarily relies on his-tological results.The ultrasound(US)-guide... BACKGROUND The overlap of imaging manifestations among distinct splenic lesions gives rise to a diagnostic dilemma.Consequently,a definitive diagnosis primarily relies on his-tological results.The ultrasound(US)-guided coaxial core needle biopsy(CNB)not only procures sufficient tissue to help clarify the diagnosis,but reduces the incidence of puncture-related complications.CASE SUMMARY A 41-year-old female,with a history of pulmonary tuberculosis,was admitted to our hospital with multiple indeterminate splenic lesions.Gray-scale ultrasono-graphy demonstrated splenomegaly with numerous well-defined hypoechoic ma-sses.Abdominal contrast-enhanced computed tomography(CT)showed an en-larged spleen with multiple irregular-shaped,peripherally enhancing,hypodense lesions.Positron emission CT revealed numerous abnormal hyperglycemia foci.These imaging findings strongly indicated the possibility of infectious disease as the primary concern,with neoplastic lesions requiring exclusion.To obtain the precise pathological diagnosis,the US-guided coaxial CNB of the spleen was ca-rried out.The patient did not express any discomfort during the procedure.CONCLUSION Percutaneous US-guided coaxial CNB is an excellent and safe option for obtaining precise splenic tissue samples,as it significantly enhances sample yield for exact pathological analysis with minimum trauma to the spleen parenchyma and sur-rounding tissue. 展开更多
关键词 SPLEEN Splenic disease Ultrasound BIOPSY Ultrasound-guided coaxial core needle biopsy Case report
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Temperature‑Arousing Self‑Powered Fire Warning E‑Textile Based on p-n Segment Coaxial Aerogel Fibers for Active Fire Protection in Firefighting Clothing 被引量:2
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作者 Hualing He Yi Qin +6 位作者 Zhenyu Zhu Qing Jiang Shengnan Ouyang Yuhang Wan Xueru Qu Jie Xu Zhicai Yu 《Nano-Micro Letters》 SCIE EI CAS CSCD 2023年第12期141-160,共20页
Firefighting protective clothing is a crucial protective equipment for firefighters to minimize skin burn and ensure safety firefighting operation and rescue mission.A recent increasing concern is to develop self-powe... Firefighting protective clothing is a crucial protective equipment for firefighters to minimize skin burn and ensure safety firefighting operation and rescue mission.A recent increasing concern is to develop self-powered fire warning materials that can be incorporated into the firefighting clothing to achieve active fire protection for firefighters before the protective clothing catches fire on fireground.However,it is still a challenge to facilely design and manufacture thermoelectric(TE)textile(TET)-based fire warning electronics with dynamic surface conformability and breathability.Here,we develop an alternate coaxial wet-spinning strategy to continuously produce alternating p/n-type TE aerogel fibers involving n-type Ti_(3)C_(2)T_(x)MXene and p-type MXene/SWCNT-COOH as core materials,and tough aramid nanofiber as protective shell,which simultaneously ensure the flexibility and high-efficiency TE power generation.With such alternating p/n-type TE fibers,TET-based self-powered fire warning sensors with high mechanical stability and wearability are successfully fabricated through stitching the alternating p-n segment TE fibers into aramid fabric.The results indicate that TET-based fire warning electronics containing 50 p-n pairs produce the open-circuit voltage of 7.5 mV with a power density of 119.79 nW cm-2 at a temperature difference of 300℃.The output voltage signal is then calculated as corresponding surface temperature of firefighting clothing based on a linear relationship between TE voltage and temperature.The fire alarm response time and flame-retardant properties are further displayed.Such self-powered fire warning electronics are true textiles that offer breathability and compatibility with body movement,demonstrating their potential application in firefighting clothing. 展开更多
关键词 Self-powered fire warning coaxial wet spinning P-n segment thermoelectric fiber Thermoelectric textiles Active fire protection
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Numerical Simulation of Aerodynamic Interaction Effects in Coaxial Compound Helicopters 被引量:1
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作者 Maosheng Wang Yanyang Wang +1 位作者 Yihua Cao Qiang Zhang 《Fluid Dynamics & Materials Processing》 EI 2023年第5期1301-1315,共15页
The so-called coaxial compound helicopter features two rigid coaxial rotors,and possesses high-speed capabilities.Nevertheless,the small separation of the coaxial rotors causes severe aerodynamic interactions,which re... The so-called coaxial compound helicopter features two rigid coaxial rotors,and possesses high-speed capabilities.Nevertheless,the small separation of the coaxial rotors causes severe aerodynamic interactions,which require careful analysis.In the present work,the aerodynamic interaction between the various helicopter components is investigated by means of a numerical method considering both hover and forward flight conditions.While a sliding mesh method is used to deal with the rotating coaxial rotors,the Reynolds-Averaged Navier-Stokes(RANS)equations are solved for the flow field.The Caradonna&Tung(CT)rotor and Harrington-2 coaxial rotor are considered to validate the numerical method.The results show that the aerodynamic interaction of the two rigid coaxial rotors significantly influences hover’s induced velocity and pressure distribution.In addition,the average thrust of an isolated coaxial rotor is smaller than that of the corresponding isolated single rotor.Compared with the isolated coaxial rotor,the existence of the fuselage results in an increment in the thrust of the rotors.Furthermore,these interactions between the components of the considered coaxial compound helicopter decay with an increase in the advance ratio. 展开更多
关键词 coaxial compound helicopter aerodynamic interaction numerical simulation sliding mesh method
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Dual-channel fiber-optic surface plasmon resonance sensor with cascaded coaxial dual-waveguide D-type structure and microsphere structure 被引量:1
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作者 李玲玲 魏勇 +4 位作者 刘春兰 任卓 周爱 刘志海 张羽 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第2期201-208,共8页
To address the restriction of fiber-optic surface plasmon resonance(SPR) sensors in the field of multi-sample detection, a novel dual-channel fiber-optic SPR sensor based on the cascade of coaxial dual-waveguide D-typ... To address the restriction of fiber-optic surface plasmon resonance(SPR) sensors in the field of multi-sample detection, a novel dual-channel fiber-optic SPR sensor based on the cascade of coaxial dual-waveguide D-type structure and microsphere structure is proposed in this paper. The fiber sidepolishing technique converts the coaxial dual-waveguide fiber into a D-type one, and the evanescent wave in the ring core leaks, generating a D-type sensing region;the fiber optic fused ball push technology converts the coaxial dual waveguides into microspheres, and the stimulated cladding mode evanescent wave leaks, producing the microsphere sensing region. By injecting light into the coaxial dual-waveguide middle core alone, the sensor can realize single-stage sensing in the microsphere sensing area;it can also realize dual-channel sensing in the D-type sensing area and microsphere sensing area by injecting light into the ring core. The refractive index measurement ranges for the two channels are 1.333–1.365 and 1.375–1.405, respectively, with detection sensitivities of 981.56 nm/RIU and 4138 nm/RIU. The sensor combines wavelength division multiplexing and space division multiplexing technologies, presenting a novel research concept for multi-channel fiber SPR sensors. 展开更多
关键词 coaxial dual-waveguide optical fiber D structure optical fiber microsphere structure dual-channel fiber-optic surface plasmon resonance(SPR)sensor
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Improvement in discharge characteristics and energy yield of ozone generation via configuration optimization of a coaxial dielectric barrier discharge reactor
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作者 Chuang Liang Zhihao Liu +2 位作者 Baochang Sun Haikui Zou Guangwen Chu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2023年第8期61-68,共8页
Dielectric barrier discharge (DBD) has been widely employed in ozone generation.However,the technology still exhibits relatively low energy yield (E_(Y)) referring to its theoretical value.In this work,E_(Y)of ozone g... Dielectric barrier discharge (DBD) has been widely employed in ozone generation.However,the technology still exhibits relatively low energy yield (E_(Y)) referring to its theoretical value.In this work,E_(Y)of ozone generation was improved by optimizing the mesh number,electrode length,and dielectric material in a coaxial DBD reactor with two wire mesh electrodes.Meanwhile,the discharge characteristics were investigated to elucidate the effect of reactor configuration on E_(Y).Results showed that the discharge characteristics were improved by increasing the mesh number,electrode length,and relative permittivity.When the mesh number was increased from 40 to 100,an improvement of approximately 48%in E_(Y) was obtained.Additionally,higher E_(Y) values were obtained using corundum as the dielectric material relative to polytetrafluoroethylene and quartz.Ultimately,E_(Y) in the optimal DBD reactor could reach 326.77 g·(k W·h)^(-1).Compared with the reported DBD reactor,the coaxial DBD reactor with the mesh electrode and the dielectric material of corundum could effectively improve E_(Y),which lays a foundation for the design of high-efficiency coaxial DBD reactor. 展开更多
关键词 coaxial DBD reactor Configuration optimization Ozone generation Discharge characteristics Energy yield
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Hydrodynamic Performance and Power Absorption of A Coaxial DoubleBuoy Wave Energy Converter
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作者 LI De-min DONG Xiao-chen +2 位作者 LI Yan-ni HUANG He-ao SHI Hong-da 《China Ocean Engineering》 SCIE EI CSCD 2023年第3期378-392,共15页
As an important wave energy converter(WEC),the double-buoy device has advantages of wider energy absorption band and deeper water adaptability,which attract an increasing number of attentions from researchers.This pap... As an important wave energy converter(WEC),the double-buoy device has advantages of wider energy absorption band and deeper water adaptability,which attract an increasing number of attentions from researchers.This paper makes an in-depth study on double-buoy WEC,by means of the combination of model experiment and numerical simulation.The Response Amplitude Operator(RAO)and energy capture of the double-buoy under constant power take-off(PTO)damping are investigated in the model test,while the average power output and capture width ratio(CWR)are calculated by the numerical simulation to analyze the influence of the wave condition,PTO,and the geometry parameters of the device.The AQWA-Fortran united simulation sy stem,including the secondary developme nt of AQWA software coupled with the flowchart of the Fortran code,models a new dynamic system.Various viscous damping and hydraulic friction from WEC system are measured from the experimental results,and these values are added to the equation of motion.As a result,the energy loss is contained in the final numerical model the by united simulation system.Using the developed numerical model,the optimal period of energy capture is identified.The power capture reaches the maximum value under the outer buoy's natural period.The paper gives the peak value of the energy capture under the linear PTO damping force,and calculates the optimal mass ratio of the device. 展开更多
关键词 coaxial double-buoy wave energy converter physical model experiment numerical simulation hydrodynamic performance
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Coaxial radiography guided puncture technique for percutaneous transforaminal endoscopic lumbar discectomy:A randomized control trial
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作者 Li-Ping Chen Bin-Song Wen +6 位作者 Heng Xu Zheng Lu Lai-Jun Yan Han Deng Hong-Bo Fu Hong-Jie Yuan Pei-Pei Hu 《World Journal of Clinical Cases》 SCIE 2023年第16期3802-3812,共11页
BACKGROUND The coaxial radiography-guided puncture technique(CR-PT)is a novel technique for endoscopic lumbar discectomy.As the X-ray beam and the puncturing needle are maintained in a parallel and coaxial direction,t... BACKGROUND The coaxial radiography-guided puncture technique(CR-PT)is a novel technique for endoscopic lumbar discectomy.As the X-ray beam and the puncturing needle are maintained in a parallel and coaxial direction,the X-ray beam can be used to guide the trajectory angle,facilitating the choice of the puncture site and providing real-time guidance.This puncture technique offers numerous advantages over the conventional anterior-posterior and lateral radiography-guided puncture technique(AP-PT),especially in cases of herniated lumbar discs with a hypertrophied transverse process or articular process,high iliac crest,and narrowed intervertebral foramen.AIM To confirm whether CR-PT is a superior approach to percutaneous transforaminal endoscopic lumbar discectomy compared to AP-PT.METHODS In this parallel,controlled,randomized clinical trial,herniated lumbar disc patients appointed to receive percutaneous endoscopic lumbar discectomy treatment were recruited from the Pain Management Department of the Affiliated Hospital of Xuzhou Medical University and Nantong Hospital of Traditional Chinese Medicine.Sixty-five participants were enrolled and divided into either a CR-PT group or an AP-PT group.The CR-PT group underwent CR-PT,and the AP-PT group underwent AP-PT.The number of fluoroscopies during puncturing,puncture duration(min),surgery duration(min),VAS score during puncturing,and puncture success rate were recorded.RESULTS Sixty-five participants were included,with 31 participants in the CR-PT group and 34 in the AP-PT group.One participant in the AP-PT group dropped out due to unsuccessful puncturing.The number of fluoroscopies[median(P25,P75)]was 12(11,14)in the CR-PT group vs 16(12,23)in the AP-PT group,while the puncture duration(mean±SD)was 20.42±5.78 vs 25.06±5.46,respectively.The VAS score was 3(2,4)in the CR-PT group vs 3(3,4)in the AP-PT group.Further subgroup analysis was performed,considering only the participants with L5/S1 segment herniation:9 patients underwent CR-PT,and 9 underwent AP-PT.The number of fluoroscopies was 11.56±0.88 vs 25.22±5.33;the puncture duration was 13.89±1.45 vs 28.89±3.76;the surgery duration was 105(99.5,120)vs 149(125,157.5);and the VAS score was 2.11±0.93 vs 3.89±0.6,respectively.All the above outcomes demonstrated statistical significance(P<0.05),favoring the CR-PT treatment.CONCLUSION CR-PT is a novel and effective technique.As opposed to conventional AP-PT,this technique significantly improves puncture accuracy,shortens puncture time and operation time,and reduces pain intensity during puncturing. 展开更多
关键词 Herniated lumbar disc coaxial PUNCTURE ANTERIOR-POSTERIOR L5/S1
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Preparing 3D Perovskite Li_(0.33)La_(0.557)TiO_(3)Nanotubes Framework Via Facile Coaxial Electro-Spinning Towards Reinforced Solid Polymer Electrolyte
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作者 Yichun Zhao Lin Fan +5 位作者 Biao Xiao Shaojun Cai Jingchao Chai Xueqing Liu Jiyan Liu Zhihong Liu 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2023年第4期273-279,共7页
It is of significance to construct continuous multiphase percolation channels with fast lithium-ion pathway in hybrid solid electrolytes.3D ceramic nanostructure frameworks have attracted great attention in this field... It is of significance to construct continuous multiphase percolation channels with fast lithium-ion pathway in hybrid solid electrolytes.3D ceramic nanostructure frameworks have attracted great attention in this field.Herein,the three-dimensional perovskite Li_(0.33)La_(0.557)TiO_(3)nanotubes framework(3D-LLTO-NT)is fabricated via a facile coaxial electro-spinning process followed by a calcination process at 800°C.The hybrid polymer electrolyte of 3DLLTO-NT framework and poly(ethylene carbonate)(3D-LLTO-NT@PEC)shows improved ionic conductivity of 1.73×10^(-4)S cm^(-1)at ambient temperature,higher lithium-ion transference number(t_(Li)^(+))of 0.78 and electrochemical stability window up to 5.0 V vs Li/Li^(+).The all-solid-state cell of LiFePO_(4)/3D-LLTO-NT@PEC/Li delivers a high specific capacity of 140.2 mAh g^(-1)at 0.1 C at ambient temperature.This outstanding performance is attributed to the 3D ceramic nanotubes frameworks which provide fast lithium ion transfer pathway and stable interfaces. 展开更多
关键词 coaxial electro-spinning ion conductivity Li_(0.33)La_(0.557)TiO_(3) NANOTUBES solid composite electrolyte
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Modeling and Robust Backstepping Sliding Mode Control with Adaptive RBFNN for a Novel Coaxial Eight-rotor UAV 被引量:11
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作者 Cheng Peng Yue Bai +3 位作者 Xun Gong Qingjia Gao Changjun Zhao Yantao Tian 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI 2015年第1期56-64,共9页
This paper focuses on the robust attitude control of a novel coaxial eight-rotor unmanned aerial vehicles(UAV) which has higher drive capability as well as greater robustness against disturbances than quad-rotor UAV. ... This paper focuses on the robust attitude control of a novel coaxial eight-rotor unmanned aerial vehicles(UAV) which has higher drive capability as well as greater robustness against disturbances than quad-rotor UAV. The dynamical and kinematical model for the coaxial eight-rotor UAV is developed, which has never been proposed before. A robust backstepping sliding mode controller(BSMC) with adaptive radial basis function neural network(RBFNN) is proposed to control the attitude of the eightrotor UAV in the presence of model uncertainties and external disturbances. The combinative method of backstepping control and sliding mode control has improved robustness and simplified design procedure benefiting from the advantages of both controllers. The adaptive RBFNN as the uncertainty observer can effectively estimate the lumped uncertainties without the knowledge of their bounds for the eight-rotor UAV. Additionally, the adaptive learning algorithm, which can learn the parameters of RBFNN online and compensate the approximation error, is derived using Lyapunov stability theorem. And then the uniformly ultimate stability of the eight-rotor system is proved. Finally, simulation results demonstrate the validity of the proposed robust control method adopted in the novel coaxial eight-rotor UAV in the case of model uncertainties and external disturbances. 展开更多
关键词 coaxial eight-rotor UAV model uncertainties external disturbances robust backstepping sliding mode controller adaptive radial basis function neural network
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Detection of Coaxial Backscattered Electrons in SEM 被引量:5
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作者 JIANG Chang-zhong REN Da-zhi (Department of Physics, Wuhan University, Wuhan 430072, China) 《Wuhan University Journal of Natural Sciences》 CAS 2000年第1期41-44,共4页
We present a coaxial detection of the backscattered electrons in SEM. The lens-aperture has been used to filter in energy and focus the backscattered electrons. This particular geometry allows us to eliminate the low ... We present a coaxial detection of the backscattered electrons in SEM. The lens-aperture has been used to filter in energy and focus the backscattered electrons. This particular geometry allows us to eliminate the low energy backscattered electrons and collect the backscattered electrons, which are backscattered close to the incident beam orientation. The main advantage of this geometry is adapted to topographic contrast attenuation and atomic number contrast enhancement. Thus this new SEM is very suitable to analyze the material composition. 展开更多
关键词 scanning electron microscopy backscattered electrons coaxial detection
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Investigation on discharge characteristics of a coaxial dielectric barrier discharge reactor driven by AC and ns power sources 被引量:6
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作者 王乾 刘峰 +2 位作者 苗传润 严冰 方志 《Plasma Science and Technology》 SCIE EI CAS CSCD 2018年第3期78-86,共9页
A coaxial dielectric barrier discharge(DBD) reactor with double layer dielectric barriers has been developed for exhaust gas treatment and excited either by AC power or nanosecond(ns)pulse to generate atmospheric ... A coaxial dielectric barrier discharge(DBD) reactor with double layer dielectric barriers has been developed for exhaust gas treatment and excited either by AC power or nanosecond(ns)pulse to generate atmospheric pressure plasma. The comparative study on the discharge characteristics of the discharge uniformity, power deposition, energy efficiency, and operation temperature between AC and ns pulsed coaxial DBD is carried out in terms of optical and electrical characteristics and operation temperature for optimizing the coaxial DBD reactor performance. The voltages across the air gap and dielectric layer and the conduction and displacement currents are extracted from the applied voltages and measured currents of AC and ns pulsed coaxial DBDs for the calculation of the power depositions and energy efficiencies through an equivalent electrical model. The discharge uniformity and operating temperature of the coaxial DBD reactor are monitored and analyzed by optical images and infrared camera. A heat conduction model is used to calculate the temperature of the internal quartz tube. It is found that the ns pulsed coaxial DBD has a much higher instantaneous power deposition in plasma, a lower total power consumption, and a higher energy efficiency compared with that excited by AC power and is more homogeneous and stable. The temperature of the outside wall of the AC and ns pulse excited coaxial DBD reaches 158 ℃ and 64.3 ℃ after 900 s operation, respectively.The experimental results on the comparison of the discharge characteristics of coaxial DBDs excited by different powers are significant for understanding of the mechanism of DBDs,reducing energy loss, and optimizing the performance of coaxial DBD in industrial applications. 展开更多
关键词 coaxial dielectric barrier discharge discharge characteristics nanosecond pulse operation temperature
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Corneal biomechanical properties changes after coaxial 2,2-mm microincision and standard 3,0-mm phacoemulsification 被引量:4
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作者 Zhe Zhang Hua Yu +3 位作者 Hui Dong Li Wang Ya-Ding Jia Su-Hua Zhang 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2016年第2期230-234,共5页
AIM: To compare the changes in corneal biomechanics measured by ocular response analyzer (ORA) after 2.2-ram microincision cataract surgery and 3.0-mm standard coaxial phacoemulsification. METHODS: The prospectiv... AIM: To compare the changes in corneal biomechanics measured by ocular response analyzer (ORA) after 2.2-ram microincision cataract surgery and 3.0-mm standard coaxial phacoemulsification. METHODS: The prospective nonrandomized study comprised eyes with cataract that had 2.2-mm coaxial microincision or 3.0 -mm standard incision phacoemulsification. The corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated intraocular pressure (IOPg) were measured by ORA preoperatively and at ld, 1-, 2-, 3- and 4-week postoperatively. Results were analyzed and compared between groups. RESULTS: In both groups, CH decreased in the immediate postoperative period (P〈0.05), returned to the preoperative level at one week (P =0.249) in the 2.2-mm group, and at two weeks in the 3.0-mm group (P --0.264); there was no significant change in CRF values. In 2.2-mm group, mean IOPcc and IOPg increased at ld postoperatively (both ,P〈0.05), and returned to preoperative level at one week (,0 =0.491 and P =0.923, respectively). In 3.0-mm group, mean IOPcc and IOPg increased at ld and lwk postoperatively (P =0.005 and ,P =0.029, respectively), and returned to preoperative level at 2wk (P =0.347 and P =0.887, respectively). CONCLUSION: Significant differences between preoperative and postoperative corneal biomechanical values were found for CH, IOPcc and IOPg. But the recovery time courses were different between the two groups. The 2.2-mm coaxial microincision cataract surgery group seemed recovery faster compared to the 3.0-mm standard coaxial phacoemulsification group. 展开更多
关键词 coaxial microincision cataract surgery 2.2-mm microincision corneal biomechanical parameters time course
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Research on a combinatorial control method for coaxial rotor aircraft based on sliding mode 被引量:5
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作者 Yi-ran Wei Hong-bin Deng +2 位作者 Zhen-hua Pan Ke-wei Li Han Chen 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2022年第2期280-292,共13页
Aiming at the position and attitude tracking of coaxial rotor aircraft(CRA),this paper proposes a combinatorial control method of sliding mode control(SMC)coupled with proportional-integralderivative control(PIDC).Con... Aiming at the position and attitude tracking of coaxial rotor aircraft(CRA),this paper proposes a combinatorial control method of sliding mode control(SMC)coupled with proportional-integralderivative control(PIDC).Considering the complete description of flight dynamics,aerodynamics and airflow interference,the dynamical model of CRA is established.The dynamical model is simplified according to the actual flight,then the simplified dynamical model is divided into two subsystems:a fully-actuated subsystem and an under-actuated subsystem.The controller of the fully-actuated subsystem consists of a SMC controller coupled with a rate bounded PIDC controller,while the controller of the under-actuated subsystem is composed of a SMC controller.The sliding manifold is defined by combining the position and velocity tracking errors of the state variables for each subsystem.Lyapunov stability theory is used to verify the stability of the sliding mode controller,which ensures that all state trajectories of the system can reach and stay on the sliding mode surface,the uncertainty and external interference of the model are compensated.Simulation and experiment compared with the conventional PIDC are carried out,the results demonstrate the effectiveness and the robustness of the proposed control method of this paper. 展开更多
关键词 coaxial rotor aircraft Sliding mode control Position and attitude tracking Simulation Experiment
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Coaxial Twin-shaft Magnetic Fluid Seals Applied in Vacuum Wafer-Handling Robot 被引量:2
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作者 CONG Mingt WEN Haiying +1 位作者 DU yu DAI Penglei 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2012年第4期706-714,共9页
Compared with traditional mechanical seals,magnetic fluid seals have unique characters of high airtightness,minimal friction torque requirements,pollution-free and long life-span,widely used in vacuum robots.With the ... Compared with traditional mechanical seals,magnetic fluid seals have unique characters of high airtightness,minimal friction torque requirements,pollution-free and long life-span,widely used in vacuum robots.With the rapid development of Integrate Circuit(IC),there is a stringent requirement for sealing wafer-handling robots when working in a vacuum environment.The parameters of magnetic fluid seals structure is very important in the vacuum robot design.This paper gives a magnetic fluid seal device for the robot.Firstly,the seal differential pressure formulas of magnetic fluid seal are deduced according to the theory of ferrohydrodynamics,which indicate that the magnetic field gradient in the sealing gap determines the seal capacity of magnetic fluid seal.Secondly,the magnetic analysis model of twin-shaft magnetic fluid seals structure is established.By analyzing the magnetic field distribution of dual magnetic fluid seal,the optimal value ranges of important parameters,including parameters of the permanent magnetic ring,the magnetic pole tooth,the outer shaft,the outer shaft sleeve and the axial relative position of two permanent magnetic rings,which affect the seal differential pressure,are obtained.A wafer-handling robot equipped with coaxial twin-shaft magnetic fluid rotary seals and bellows seal is devised and an optimized twin-shaft magnetic fluid seals experimental platform is built.Test result shows that when the speed of the two rotational shafts ranges from 0-500 r/min,the maximum burst pressure is about 0.24 MPa.Magnetic fluid rotary seals can provide satisfactory performance in the application of wafer-handling robot.The proposed coaxial twin-shaft magnetic fluid rotary seal provides the instruction to design high-speed vacuum robot. 展开更多
关键词 magnetic fluid SEALS coaxial twin-shaft magnetic field wafer handling robot
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Continuous Fabrication of Ti_(3)C_(2)T_x MXene-Based Braided Coaxial Zinc-Ion Hybrid Supercapacitors with Improved Performance 被引量:4
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作者 Bao Shi La Li +3 位作者 Aibing Chen Tien-Chien Jen Xinying Liu Guozhen Shen 《Nano-Micro Letters》 SCIE EI CAS CSCD 2022年第2期206-215,共10页
Zinc-ion hybrid fiber supercapacitors(FSCs)are promising energy storages for wearable electronics owing to their high energy density,good flexibility,and weavability.However,it is still a critical challenge to optimiz... Zinc-ion hybrid fiber supercapacitors(FSCs)are promising energy storages for wearable electronics owing to their high energy density,good flexibility,and weavability.However,it is still a critical challenge to optimize the structure of the designed FSC to improve energy density and realize the continuous fabrication of super-long FSCs.Herein,we propose a braided coaxial zinc-ion hybrid FSC with several meters of Ti_(3)C_(2)T_x MXene cathode as core electrodes,and shell zinc fiber anode was braided on the surface of the Ti_(3)C_(2)T_x MXene fibers across the solid electrolytes.According to the simulated results using ANSYS Maxwell software,the braided structures revealed a higher capacitance compared to the spring-like structures.The resulting FSCs exhibited a high areal capacitance of 214 mF cm^(-2),the energy density of 42.8μWh cm^(-2)at 5 mV s^(-1),and excellent cycling stability with 83.58%capacity retention after 5000 cycles.The coaxial FSC was tied several kinds of knots,proving a shape-controllable fiber energy storage.Furthermore,the knitted FSC showed superior stability and weavability,which can be woven into watch belts or embedded into textiles to power smart watches and LED arrays for a few days. 展开更多
关键词 Ti_(3)C_(2)T_x MXene Fiber supercapacitor coaxial structure Zinc-ion
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Wave Run-up on A Coaxial Perforated Circular Cylinder 被引量:2
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作者 朱大同 《China Ocean Engineering》 SCIE EI 2011年第2期201-214,共14页
This paper describes a plane regular wave interaction with a combined cylinder which consists of a solid inner column and a coaxial perforated outer cylinder. The outer perforated surface is a thin porous cylinder wit... This paper describes a plane regular wave interaction with a combined cylinder which consists of a solid inner column and a coaxial perforated outer cylinder. The outer perforated surface is a thin porous cylinder with an annular gap between it and the inner cylinder. The non-linear boundary condition at the perforated wall is a prime focus in the study; energy dissipation at the perforated wall occurs through the resistance to the fluid across the perforated wall. Explicit analytical formulae are presented to calculate the wave run-up on the outer and inner surfaces of the perforated cylinder and the surface of the inner column. The theoretical results of the wave run-up are compared with previous experimental data. Numerical results have also been obtained: when the ratio of the annular gap between the two cylinders to incident wavelength (b-a)/L≤0. 1, the wave run-up on the inner surface of the perforated cylinder and the surface of inner column can partially or completely exceed the incident wave height. 展开更多
关键词 plane water wave coaxial perforated cylinder wave run-up flow resistance
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