检索结果-南通市图书馆

Progress in Natural Science:Materials International 2007年第3期17卷 289-297页

作者： liu zhiyu and wei hao (Key Laboratory of Physical Oceanography, State Education Ministry, Ocean University of China, Qingdao 266003, China) Key Laboratory of Physical Oceanography Ocean University of China Qingdao 266003 China

High frequency velocity fluctuations were measured by using an acoustic Doppler velocimeter (ADV) in the tidal bottom boundary layer (BBL) of the Yellow Sea (YS) for 25 h. The turbulent kinetic energy dissipation rate and the bottom shear stress were estimated and analyzed. Results show that: (1) in the tidal BBL of the YS, the variations of the dissipation rate and the bottom shear stress during 25 hare (1.8×10-8-3.4×10 -5) W·kg-1 and (6.6×10-4-7.5×10-1) N·m - 2 respectively, indicating that there are strong dissipations in the tidal BBL of the YS; (2) in the well-mixed tidal BBL, the turbulence is mainly shear-induced locally and the production and dissipation are generally in equilibrium; (3) for the seas where the semidiurnal tidal current is dominant, both the dissipation rate and the bottom shear stress exhibit a strong quarter-diurnal variation; (4) the mean bottom drag coefficient Cd (0.45) is 0.0017 (corresponding Cd( 1.00) = 0.0015), but it has significant variations (0.0005-0.0082). The mean bottom roughness length is 2.8×10-5 m.

关键词： tidal bottom boundary layer turbulent kinetic energy dissipation rate bottom shear stress ADV the Yellow Sea.

Autonomous trajectory tracking control method for an agricultural robotic vehicle

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Agricultural and Biological Engineering 2024年第1期17卷 215-224页

作者： Jin Yan Wenguang Zhang Yong liu wei Pan Xiaoyu Hou zhiyu liu School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China School of Information Engineering Xuzhou University of TechnologyXuzhou 221018JiangsuChina National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing 210094China School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China

To address the nonlinearities and external disturbances in unstructured and complex agricultural environments,this paper investigates an autonomous trajectory tracking control method for agricultural ground ***,this paper presents the design and implementation of a lightweight,modular two-wheeled differential drive vehicle equipped with two drive wheels and two caster *** vehicle comprises drive wheel modules,passive wheel modules,battery modules,a vehicle frame,a sensor system,and a control ***,a novel robust trajectory tracking method was proposed,utilizing an improved pure pursuit ***,an Online Particle Swarm Optimization Continuously Tuned PID(OPSO-CTPID)controller was introduced to dynamically search for optimal control gains for the PID *** results demonstrate the superiority of the improved pure pursuit algorithm and the OPSO-CTPID control *** validate the performance,the vehicle was integrated with a seeding and fertilizing machine to realize autonomous wheat seeding in an agricultural *** outcomes reveal that the vehicle of this study completed a seeding operation exceeding 1 km in *** proposed method can robustly and smoothly track the desired trajectory with an accuracy of less than 10 cm for the root mean square error(RMSE)of the curve and straight lines,given a suitable set of parameters,meeting the requirements of agricultural *** findings of this study hold significant reference value for subsequent research on trajectory tracking algorithms for ground-based agricultural robots.

关键词： trajectory tracking autonomy control agricultural robotic vehicle online PSO continuously tuned PID dynamic pure pursuit algorithm

High-performance Si/VO_(2)-nanorod heterojunction photodetector based on photothermoelectric effect for detecting human radiation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第3期43卷 1177-1185页

作者： Fu-Hai Guo Lan-Zhong hao wei-Zhuo Yu Si-Qi Li Guan-Chu liu Jing-Yi hao Yun-Jie liu College of Science China University of PetroleumQingdao266580China School of Materials Science and Engineering China University of PetroleumQingdao266580China

As a typical candidate of optoelectronic materials,vanadium dioxide(VO_(2))has wide applications in photodetectors(PDs),but is still challenging in largely enhancing the photodetecting performance for low-power human ***,high-performance Si/VO_(2)nanorods(NRs)heterojunction PDs based on the photothermoelectric(PTE)effect are *** uniform VO_(2)-NRs array films were deposited on Si by using magnetron sputtering technique,and a Si/VO_(2)heterojunctions were *** device exhibits a four-stage photoresponse and broadband photoresponse from ultraviolet to long-wavelength *** from the unique nanorods structure and the strong PTE effect,the fabricated device exhibits a large enhancement of the photodetecting performance,showing an ultrahigh photodetectivity of 1.6×10^(13)Jones and ultrafast response rates with a risingedge time of~65.0μs,three orders of magnitude higher than other VO_(2)-based ***,the device exhibits unique abilities to detect human radiation even when the human fingers are far away from the device surface up to 10.0 ***,the fabricated Si/VO_(2)devices can also be applied as breath sensors to distinguish different breathing *** results supply an effective route to design high-performance photodetectors toward detecting human thermal radiation and respiration.

关键词： Vanadium dioxide Heterojunction Photodetector Photothermoelectric Human radiation and respiration sensing

Dynamical switchable quantum nonreciprocity induced by off-resonant chiral two-photon driving

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 31-37页

作者： Da-wei liu Zi-hao Li Shi-Lei Chao Ying Wu liu-Gang Si School of Physics and Institute for Quantum Science and Engineering Huazhong University of Science and TechnologyWuhan 430074China

Optical nonreciprocity,which refers to the direction-dependent emission,scattering and absorption of photons,plays a very important role in quantum engineering and quantum information ***,we propose an all-optical approach to achieve the optical dynamical switchable quantum nonreciprocity by an off-resonant chiral two-photon driving in a single microring cavity,which differs from the conventional nonreciprocal *** is shown that the optical field with time-dependent statistical properties can be generated and the nonreciprocity flips periodically,with switchable photon blockade and photon-induced tunneling *** find that the dynamical system is robust and immune to the parameter variations,which loosens the parameter range of ***,the time window for one-way quantum information is sufficiently wide and *** work opens a new idea for the current quantum nonreciprocal research,which can facilitate a memory functionality and be used for future inmemory superconducting quantum *** other nonreciprocal quantum devices,i.e.,dynamical switchable nonreciprocal squeezing and entanglement,may be inspired by our method,which is expected to have important applications in future quantum technology.

关键词： dynamical switchable nonreciprocity single-photon source chiral two-photon driving

Effect of tubastatin A on NLRP3 inflammasome activation in macrophages under hypoxia/ reoxygenation conditions

在线全文

学校读者我要写书评

暂无评论

World Journal of Emergency Medicine 2024年第4期15卷 289-296页

作者： hao Li Chang liu Ying Cui Panpan Chang wei Chong Department of Emergency Medicine the First Hospital of China Medical UniversityShenyang 110001China Trauma Medicine Center Peking University People's HospitalBeijing 100871China Key Laboratory of Trauma and Neural Regeneration Peking UniversityBeijing 100871China National Center for Trauma Medicine of China Beijing 100871China

BACKGROUND:There are currently no effective drugs to mitigate the ischemia/reperfusion injury caused by fluid resuscitation after hemorrhagic shock(HS).The aim of this study was to explore the potential of the histone deacetylase 6(HDAC6)-specific inhibitor tubastatin A(TubA)to suppress nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome activation in macrophages under hypoxia/reoxygenation(H/R)***:The viability of RAW264.7 cells subjected to H/R after treatment with different concentrations of TubA was assessed using a cell-counting kit-8(CCK8)***,2.5μmol/L TubA was used with RAW264.7 cells under H/R ***264.7 cells were divided into three groups,namely the control,H/R,and TubA *** levels of reactive oxygen species(ROS)in the cells were detected using fluorescence *** protein expression of HDAC6,heat shock protein 90(Hsp90),inducible nitric oxide synthase(iNOS),NLRP3,gasdermin-D(GSDMD),Caspase-1,GSDMD-N,and Caspase-1 p20 was detected by western *** levels of interleukin-1β(IL-1β)and IL-18 in the supernatants were detected using enzyme-linked immunosorbent assay(ELISA).RESULTS:HDAC6,Hsp90,and iNOS expression levels were significantly higher(P<0.01)in the H/R group than in the control group,but lower in the TubA group than in the H/R group(P<0.05).When comparing the H/R group to the control group,ROS levels were significantly higher(P<0.01),but significantly reduced in the TubA group(P<0.05).The H/R group had higher NLRP3,GSDMD,Caspase-1,GSDMD-N,and Caspase-1 p20 expression levels than the control group(P<0.05),however,the TubA group had significantly lower expression levels than the H/R group(P<0.05).IL-1βand IL-18 levels in the supernatants were significantly higher in the H/R group compared to the control group(P<0.01),but significantly lower in the TubA group compared to the H/R group(P<0.01).CONCLUSION:TubA inhibited the expression of HDAC6,Hsp90,and iNOS in macrophages

关键词： Hemorrhagic shock Hypoxia/reoxygenation Macrophage NLRP3 Tubastatin A

Effect of coral sand on the mechanical properties and hydration mechanism of magnesium potassium phosphate cement mortar

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第2期25卷 116-129页

作者： hao liu Huamei YANG Houzhen wei Jining YU Qingshan MENG Rongtao YAN College of Civil Engineering and Architecture Guilin University of TechnologyGuilin541004China Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering Guilin University of TechnologyGuilin541004China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China School of Intelligent Construction Wuchang University of TechnologyWuhan430002China Hydraulic Concrete Institute China Three Gorges CorporationBeijing100038China The First Railway Survey and Design Institute Group Corporation Xi’an710043China

Damaged structures on coral islands have been spalling and cracking due to the dual corrosion of tides and *** ensure easy access to aggregate materials,magnesium potassium phosphate cement(MKPC)and coral sand(CS)are mixed to repair damaged structures on coral ***,CS is significantly different from land-sourced sand in mineral composition,particle morphology,and *** has a substantial impact on the hydration characteristics and macroscopic properties of MKPC ***,in this study we investigated the compressive strength,interfacial mechanical properties,and corrosion resistance of MKPC CS *** in the morphology,microstructure,and relative contents of hydration products were revealed by scanning electron microscope-energy dispersive spectrometer(SEM-EDS)and X-ray diffraction(XRD).The results indicated that the compressive strength increased linearly with the interfacial micro-hardness,and then stabilized after long-term immersion in pure water and Na2SO4 solution,showing excellent corrosion *** with MKPC river sand(RS)mortar,the hydration products of CS mortar were an intermediate product 6KPO2·8H2O with a relative content of 3.9%at 1 h and 4.1%at 12 *** hydration product MgKPO_(4)·6H_(2)O increased rapidly after 7-d curing,with an increased growth rate of 1100%.Our results showed that CS promoted the nucleation and formation of hydration products of MKPC,resulting in better crystallinity,tighter overlapping,and a denser interfacial transition *** results of this study provide technical support for applying MKPC mortar as a rapid repair material for damaged structures on coral islands.

关键词： Magnesium potassium phosphate cement(MKPC) Coral sand(CS) Mechanical properties Corrosion resistance Hydration mechanism

Cobalt-nitrogen co-doped porous carbon sphere as highly efficient catalyst for liquid-phase cyclohexane oxidation with molecular oxygen and the active sites investigation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2024年第3期18卷 101-112页

作者： Lei Chen Yuan Sun Jinshan Chi wei Xiong Pingle liu Fang hao College of Chemical Engineering National&Local United Engineering Research Centre for Chemical Process Simulation and IntensificationXiangtan UniversityXiangtan411105China

The selective oxidation of cyclohexane to cyclohexanone and cyclohexanol(KA oil)is a challenging issue in the chemical *** present the industrial conversion of cyclohexane to cyclohexanone and cyclohexanol is normally controlled at less than 5%***,the development of highly active and stable catalysts for the aerobic oxidation of cyclohexane is necessary to overcome this low-efficiency ***,we have developed a cobalt-nitrogen co-doped porous sphere catalyst,Co-NC-x(x is the Zn/Co molar ratio,where x=0,0.5,1,2,and 4)by pyrolyzing resorcinol-formaldehyde resin *** achieved 88.28%cyclohexanone and cyclohexanol selectivity and a cyclohexane conversion of 8.88%under *** results showed that the introduction of zinc effectively alleviated the aggregation of Co nanoparticles and optimized the structural properties of the *** addition,Co0 and pyridinic-N are proposed to be the possible active species,and their proportion efficiently increased in the presence of Zn^(2+)*** this study,we developed a novel strategy to design highly active catalysts for cyclohexane oxidation.

关键词： KA oil production cyclohexane selective oxidation cobalt-nitrogen co-doped porous carbon spheres metal-organic framework

The Influence of Acid on the RockMechanical Characteristics of Deep Shale in theWujiaping Formation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Energy Engineering 2024年第1期121卷 27-42页

作者： hao Zhang Yan Zhang wei liu Ximin Zhang Xiang liu School of Petroleum Engineering Yangtze UniversityWuhan430100China Petroleum Engineering Technology Research Institute Jianghan Oilfield Branch of SinopecWuhan430035China Drilling Technology Research Institute Sinopec Shengli Oilfield Service CorporationDeyang618000China

The microscopic characteristics and mechanical properties of rocks change after the action of acid on deep shale,which affects the fracturing ***,we designed and conducted indoor experiments related to the changes in macro and microscopic characteristics after the interaction of acid with the shale of Wujiaping Formation,based on which the characteristic law of fracture volume modification after acid fracturing was studied using numerical *** results demonstrate that the pores and fractures are enlarged and the structure is significantly loosened after the acid *** a 15%concentration of hydrochloric acid can effectively dissolve ***,the degree of acid-etching reaction is highly variable because of the different carbonate content,which reveals the strong inhomogeneity of the shale system in the Wujiaping Group reservoir *** the acid interacted with the shale rock samples,the triaxial compressive strength,elastic modulus,and Poisson’s ratio of shale ***,the evaluation of the effect after acid fracturing simulated by fracturing software revealed that the smaller the value of elastic modulus in shale-based reservoirs,the more favorable the fracture volume *** discovery not only provides a theoretical basis for the expansion and extension patterns of acid-fracturing in carbonaceous shale formations but also offers research methods and theoretical insights for the fundamental exploration of other deep-seated oil and gas resources.

关键词： Shale acid fracturing macro characteristics microscopic characteristics mechanical properties

Temperature prediction model in multiphase flow considering phase transition in the drilling operations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2024年第3期21卷 1969-1979页

作者： Yang Zhang Yong-An Li Xiang-wei Kong hao liu Teng-Fei Sun College of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100027China School of Petroleum Engineering Yangtze UniversityWuhan430000HubeiChina

The study considers gas compression properties,gas slippage,back pressure(BP),phase transition(PT),well depth,and differences in gas-liquid physical properties.A new temperature model for multiphase flow is proposed by considering phase transition in the drilling *** mathematical model of multiphase flow is solved using the finite difference method with annulus mesh division for grid nodes,and a module for multiphase flow calculation and analysis is *** results indicate that the temperature varies along the annulus with the variation of gas influx at the bottom of the *** the process of controlled pressure drilling,as gas slips along the annulus to the wellhead,its volume continuously expands,leading to an increase in the gas content within the annulus,and consequently,an increase in the pressure drop caused by gas *** temperature increases with the increase in BP and decreases in gas influx rate and wellbore *** gas influx,the thermal conductivity coefficient for the gas-drilling mud two phases is significantly weakened,resulting in a considerable change in temperature along the *** the context of MPD,the method of slightly changing the temperature along the annulus by controlling the back pressure is feasible.

关键词： Managed pressure drilling Phase transition Temperature Gas-drilling mud two phase

Investigation of wake-induced vibration interference between two staggered wave-cone cylinders at subcritical Reynolds number

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2024年第2期36卷 378-393页

作者： Lin Zou Di-wei liu Jian liu Hong-cheng Zuo Yin-huan Zheng hao Xia School of Mechanical and Electronic Engineering Wuhan University of TechnologyWuhan430070China Department of Aeronautical and Automotive Engineering Loughborough UniversityLoughboroughUK

The wake induced vibration(WIV)of a one-and two-degree-of-freedom(1DOF,2DOF)downstream wave-cone cylinder(WCC)behind a stationary equal-size upstream wave-cone cylinder in the staggered arrangement is numerically investigated at subcritical Reynolds number of 3900 by using shear stressed transfer(SST)k-ωturbulence *** streamwise pitch ratios(P/Dm)vary from 4 to 6 with a fixed incident angleα=8°.Experimental measurements were also performed for the validation of the present numerical *** is found that the largest vibration amplitude in crossflow direction occurred at P/Dm=4,Ur=8 with small difference of streamwise vibration at P/Dm=4,*** from single wavy-cone cylinder(SWCC),the downstream flexible one of a pair staggered WCCs got larger vibration amplitude during phase switching stage instead of in-phase *** upstream wake will suppress the triple frequency of main frequency in the power spectra density(PSD)functions of Cl but stimulate the double one of *** intriguing vibration mechanism happened in all 2DOF cases where the trajectory of downstream WCC is a significant ellipse rather than a figure of *** transformation of phase switching and the variation of the main frequency of drag coefficient(Cd)can be explained by the vortex-shedding modes of downstream WCC.

关键词： Two wave-cone cylinders staggered arrangement wake induced vibration phase switching vortex shedding