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Analysis of reflected signal of quad rotor UAV based on model fitting in mobile communication system

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Journal of Systems Engineering and Electronics 2022年第1期33卷 97-104页

作者： LI Xiaohui fang Cong FAN tao School of Telecommunication Engineering Xidian UniversityXi’an 710071China Guangzhou Institute of Technology Xidian UniversityGuangzhou 510555China

In view of the many scenes of unmanned aerial vehicle(UAV)detection,a third-party signal source is used to design a receiver to monitor the UAV.It is of great significance to understand the reflection of the signal illuminating the UAV.Taking the communication base station(BS)signal as the third-party signal source,and considering the complete transmission link,reflection changes and loss fading of the communication signal,this study conducts model fitting for irregular UAV targets,simplifying complex targets into a combination of simple targets.Furthermore,the influence of the dielectric constant of the target surface and the signal irradiation angle on the signal reflection is analyzed.The analysis shows that the simulation results of this model fitting method are consistent with the results of other literature,which provides theoretical support for the detection of low and slow small targets such as UAVs.

关键词： mobile communication signal quad rotor unmanned aerial vehicle(UAV) signal reflection model fitting

Bimetal-containing covalent organic framework boosted photocatalytic amination

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Science China Chemistry 2023年第2期66卷 299-300页

作者： Weiwei fang tao Tu Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources International Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjing210037China Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Department of ChemistryFudan UniversityShanghai200433China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai200032China Green Catalysis Center and College of Chemistry Zhengzhou UniversityZhengzhou450001China

The design of new catalytic systems allowing for rapid,selective,and sustainable chemical transformations is of immense scientific importance.As ubiquitous skeleton motifs,during the past decades,a range of well-designed ligands and catalysts have been developed,which benefited the construction of C-N bond under mild reaction conditions[1].

关键词： skeleton photocatalytic mild

Dynamic Investigations on the Wear Behavior of a 3D Revolute Joint Considering Time-Varying Contact Stiffness: Simulation and Experiment

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Chinese Journal of Mechanical Engineering 2023年第6期36卷 230-246页

作者： Li Zhang Yining fang Guanghan Bai Junyong tao College of Information and Communication National University of Defense TechnologyWuhan 430010China Laboratory of Science and Technology on Integrated Logistics Support College of Intelligence Science and TechnologyNational University of Defense TechnologyChangsha 410073China

The existence of the relative radial and axial movements of a revolute joint’s journal and bearing is widely known.The three-dimensional(3D)revolute joint model considers relative radial and axial clearances;therefore,the freedoms of motion and contact scenarios are more realistic than those of the two-dimensional model.This paper proposes a wear model that integrates the modeling of a 3D revolute clearance joint and the contact force and wear depth calculations.Time-varying contact stiffness is first considered in the contact force model.Also,a cycle-update wear depth calculation strategy is presented.A digital image correlation(DIC)non-contact measurement and a cylindricity test are conducted.The measurement results are compared with the numerical simulation,and the proposed model’s correctness and the wear depth calculation strategy are verified.The results show that the wear amount distribution on the bearing’s inner surface is uneven in the axial and radial directions due to the journal’s stochastic oscillations.The maximum wear depth locates where at the bearing’s edges the motion direction of the follower shifts.These find-ings help to seek the revolute joints’wear-prone parts and enhance their durability and reliability through improved design.

关键词： Multibody dynamics 3D revolute joint Wear prediction Digital image correlation

Photoelectrocatalytic degradation of high COD dipterex pesticide by using TiO_2 /Ni photo electrode

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Journal of Environmental Sciences 2012年第6期24卷 1149-1156页

作者： Tao Fang Chao Yang Lixia Liao The State Key Lab of Urban Water Resource and Environment National Engineering Research Center of Urban Water Resource&The Academy of Fundamental and Interdisciplinary ScienceHarbin Institute of TechnologyHarbin 150080China College of Science Northeast Forestry UniversityHarbin 150040China

A TiO2 thin film electrode deposited on porous nickel net （TiO2/Ni） was prepared by the sol-gel method, and the surface morphology, crystal structure features and the grain size were characterized by Field emission scan electron microscopy （FESEM） and X-ray diffraction （XRD）. The photoelectrocatalytic system was set up using a UV high-pressure mercury lamp as the light source, TiO2 coated on foamed nickel as photo anode, Pt sheet as counter electrode and the pesticide dipterex in synthetic wastewater. Various factors that influence the photoelectrocatalytic decomposition of dipterex pesticide have been studied, such as degradation time, the type of electrolyte, current density, original pH value and different degradation methods. The prepared catalysts were employed to photoelectrocatalytically degrade the pesticide dipterex under UV irradiation, comparing the results with photocatalytic degradation and electrochemical oxidation. The results indicated that under the optimal conditions of 0.02 mol/L NaC1 as the supporting electrolyte, current density = 2.5 mA/cm^2, pH 6.0 and dipterex pesticide 40 mg/L, and reaction time 2 hr, dipterex chemical oxygen demand （COD） removal rate and organophosphorous conversion of up to 82.6% and 83.5% were achieved, respectively. The method of photoelectrocatalytic degradation is more efficient than photocatalysis and electrochemical oxidation. The possible roles of the electrolytes on the reactions and probable mechanisms were also discussed.

关键词： photoelectrocatalysis COD removal TiO2 dipterex pesticide

Electrochemical drilling of small holes by regulating in real-time the electrolyte flowrate in multiple channels

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Chinese Journal of Aeronautics 2022年第5期35卷 470-483页

作者： Jinxing LUO Xiaolong fang tao YANG Di ZHU National Key Laboratory of Science and Technology on Helicopter Transmission Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Electrochemical drilling(ECD)provides an alternative technique for drilling multiple small holes in difficult-to-machine materials in numerous industrial applications such as for aeroengines.The value and fluctuation of electrolyte flowrate can seriously affect the machining stability and hole quality in ECD.In particular,when drilling multiple holes,the distribution and fluctuations of the electrolyte flowrate in each channel could influence the uniformity of the electrolyte flowrate among multiple tube electrodes,thereby affecting the machining stability and the maximum feed rate.Thus,an eight-channel flow control system was developed to measure and regulate in real time the electrolyte flowrate supplied into each individual tube electrode.This paper proposes ECD of small holes with real-time flowrate control to improve the uniformity of electrolyte flowrate in each tube electrode and reduce the fluctuations in the electrolyte flowrate.In single-hole drilling,when the electrolyte flowrate was regulated in real time,the hole quality and machining stability were considerably better than without regulation.This is because the electrolyte flowrate remains basically constant,which stabilizes the flow field.Moreover,by considering the hole profile,it was found that an electrolyte flowrate of 200.0 m L/min can be acceptable for ECD of small holes.When the eight-channel flow control system was used in multiple-hole drilling,the uniformity of the electrolyte flowrate in each tube electrode was obviously improved,which led to a more stable process.Additionally,the maximum feed rate can attain 2.40 mm/min in multiple-hole drilling.Based on these findings,a matrix(5×32)of multiple small holes was successfully fabricated with a satisfactory diameter consistency,as the machining stability and machining efficiency had been enhanced.

关键词： Electrochemical drilling Small holes Electrolyte flowrate Real-time regulation Machining stability

Effect of GGBS on performance deterioration of non-dispersible underwater concrete in saline soil

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Research in Cold and Arid Regions 2022年第2期14卷 120-137页

作者： fang Liu BaoMin Wang GuoRong tao tao Luo XiaoSa Yuan Shaanxi Key Laboratory of Safety and Durability of Concrete Structures Xijing UniversityXi'anShaanxi 710123China State Key Laboratory of Simulation and Regulation of Water Cycle in River Basins China Institute of Water Resources and Hydropower ResearchBeijing 100038China School of Civil Engineering Dalian University of TechnologyDalianLiaoning 116023China

In saline soil areas,there are a large number of ions in soil or water environments,such as Cl^(-)and SO_(4)^(2-),which have strong corrosive interactions with buildings.To study the deterioration of non-dispersible underwater concrete in sulfate,chloride,and mixed salt environments,the compressive strength and deterioration resistance coefficient of the studied concrete mixed with different amounts of ground granulated blast-furnace slag(GGBS)were analyzed in this paper.At the same time,the micro morphology and corrosion products distribution of the studied concrete were observed by means of SEM,plus XRD diffraction,TG-DTG and FT-IR analyses to explore the influence of corrosive solutions on the hydration products of concrete.We also analyzed the mechanism of improving the deterioration resistance of the studied concrete by adding GGBS in a saline soil environment.The results show that the compressive strength of the studied concrete in a chloride environment was close to that in a fresh water environment,which means that chloride has no adverse effect on compressive strength.The deterioration of the studied concrete was most serious in a sulfate environment,followed by mixed salt environment,and the lowest in a chloride environment.In addition,by adding GGBS,the compressive strength and deterioration resistance of the studied concrete could be effectively improved.

关键词： saline soil non-dispersible underwater concrete granulated blast furnace slag deterioration resistance mechanism analysis

Study of the wall adhesive tensile contact of moist iron ore bulk solids

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Particuology 2020年第3期18卷 67-75页

作者： Tao Fang Wei Chen Jens Plinke Craig Wheeler Alan Roberts School of Civil Engineering East China Jiaotong UniversityNanchang 330013China School of Engineering The University of NewcastleCallaghan 2308Australia

The adhesive tensile stress between moist bulk iron ore solids and wall surfaces are critical to control and avoid blockage in large throughput material handling plants.In this study,an experimental system was designed to investigate the adhesive tensile contact between a range of iron ore materials and wall lining specimens.The contact mechanism between the material specimen and the wall surface was initially characterised.The experimental results indicated that the adhesive tensile stress is dependent on both the moisture content and the applied major consolidation stress,with the former exhibiting more significant contribution to increasing the magnitude of stress.The surface roughness of the wall showed a negligible effect in determining the adhesive tensile stress.Additionally,the iron ore sample with a higher fines content was observed to be able to achieve a higher adhesive tensile stress compared to the coarse samples.Consequently,the insights resulting from the study demonstrated practical applicability through measures such as blending and/or beneficiation,which reduce the adhesive tensile stress and minimise blockages.

关键词： Wet sticky material Adhesive tensile stress Wall linings Liquid bridge force Capillary stress Soil texture

Effect of back pressure on the grinding performance of abrasive suspension flow machining

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Advances in Manufacturing 2022年第1期10卷 143-157页

作者： Ming-Hui fang tao Yu Feng-Feng Xi Department of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200444People’s Republic of China Shanghai University of Engineering Science Shanghai 201620People’s Republic of China Department of Aerospace Engineering Ryerson UniversityTorontoCanada

Abrasive suspension flow machining(ASFM)is an advanced finishing method that uses an abrasive suspension slurry for grinding and chamfering as well as the finishing of inaccessible components.This study examines the effect of back pressure on the grinding characteristics of an abrasive suspension flow during the grinding of slender holes.A numerical model was developed to simulate the abrasive suspension flow in a slender hole and was verified experimentally using injector nozzle grinding equipment under different grinding pressures and back pressures.It is shown that the ASFM with back pressure not only eliminates the cavitation flow in the spray hole,but also increases the number of effective abrasive particles and the flow coefficient.Increasing the back pressure during the grinding process can increase the Reynolds number of the abrasive suspension flow and reduce the thickness of the boundary layer in the slender hole.Moreover,increasing the back pressure can improve the flow rate of the injector nozzle and its grinding performance.

关键词： Abrasive suspension flow machining(ASFM)Back pressure Injector nozzle Grinding performance

Effect of electromagnetic stirring on metallurgical quality of GCr15 electroslag ingot

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China Foundry 2022年第1期19卷 46-54页

作者： Xiao-fang Shi tao Xu Li-zhong Chang School of Metallurgy Engineering Anhui University of TechnologyMa'anshan 243002AnhuiChina Anhui Fukai Special Material Co. Ltd.Jixi 245300AnhuiChina

To further improve the metallurgical quality of electroslag remelting,remove the large inclusions in electroslag ingot and refine the solidification structure of electroslag ingot,an electroslag remelting furnace with electromagnetic stirring was designed,and the influence of different magnetic induction intensities on metallurgical quality of GCr15 electroslag ingot was studied.Inclusions with different sizes and types were analyzed by an ASPEX scanning electron microscope,and the morphology and composition of inclusions were further observed by a JSM-6510LV scanning electron microscope.The distribution of alloying elements on the cross section of electroslag ingot was analyzed by original position analysis(OPA).The results show that whether or not electromagnetic stirring is used,the inclusions in electroslag ingot are mainly composed of Al_(2)O_(3),MnS,MnS-oxide and other oxides,among which Al_(2)O_(3) is the most.Compared with an electroslag ingot without electromagnetic stirring,the number of inclusions decreases considerably,and the proportion of small inclusions increases while the proportion of large inclusions decreases when the electromagnetic stirring with remelting current of 1.1 kA and magnetic induction intensity of 62 Gs is applied.However,excessive electromagnetic force will cause the number and diameter of inclusions to increase again.Electromagnetic stirring has different effects on the segregation of different elements.Under the experimental conditions,the weak electromagnetic force with 1.1 kA and magnetic induction intensity of 108 Gs has little effect on the segregation of C,but decreases the segregation of P,and the excessive electromagnetic force aggravates the segregation of alloy elements.

关键词： electroslag remelting electromagnetic stirring inclusion solidification segregation GCr15 bearing steel