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Defence Technology（防务技术） 2024年第2期32卷 412-429页

作者： wenxue chen Yudong Hu Changsheng Gao Ruoming An School of Astronautics Harbin Institute of TechnologyHarbin 150001China

This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost ***,the velocity control in such trajectory tracking guidance systems of missiles is *** our contribution,the velocity control channel is designed to deal with the intractable velocity problem and improve tracking *** global prescribed performance function,which guarantees the tracking error within the set range and the global convergence of the tracking guidance system,is first proposed based on the traditional ***,a tracking guidance strategy is derived using the integral sliding mode control techniques to make the sliding manifold and tracking errors converge to zero and avoid ***,an improved switching control law is introduced into the designed tracking guidance algorithm to deal with the chattering problem.A back propagation neural network(BPNN)extended state observer(BPNNESO)is employed in the inner loop to identify *** obtained results indicate that the proposed tracking guidance approach achieves the trajectory tracking guidance objective without and with disturbances and outperforms the existing tracking guidance schemes with the lowest tracking errors,convergence times,and overshoots.

关键词： BP network neural Integral sliding mode control(ISMC) Missile defense Prescribed performance function(PPF) State observer Tracking guidance system

Reconstruction of different scales of pore-fractures network of coal reservoir and its permeability prediction with Monte Carlo method

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International Journal of Mining Science and Technology 2017年第4期27卷 693-699页

作者： Ni Xiaoming chen wenxue Li Zheyuan Gao Xiang School of Energy Science and Engineering School of Civil Engineering Henan Polytechnic University Jiaozuo 454000 China Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region Jiaozuo 454000 China Opening Project of Key Laboratory of Deep Mine Construction Henan Polytechnic University Jiaozuo 454000 China Department of Building Civil & Environmental Engineering Concordia University Montreal H3G1M8 Canada china Coal Tunnel Engineering Go. LTD Xuzhou 221000 China

There are millimeter, micron and nanometer scales of pores and fractures in coal to describe different scales of coal pores and fissures communicating path and to quantitatively characterize their permeability. Such information provides an important basis for studying coalbed methane output mechanism. The pores and fissures in a large number of coal samples were observed and counted by scanning electron microscopy and optical microscopy. The probability distribution models of pore-fissure network were then established. Different scales of pore-fissures 2D network models were reconstructed by Monte Carlo method. The 2D seepage models were obtained through assignment zero method and using Matlab software. The effect of permeability on different scale pore-fractures network was obtained by two-dimensional seepage equation. Predicted permeability is compared with the measured ones. The results showed that the dominant order of different scale pore-fractures connected path from high to low is millimeter-sized fractures, seepage pores and micron-size fractures. The contribution of coal reservoir permeability from large to small is millimeter-size fractures, micron-size fractures and seepage pores. Different parameters in different scale pore-fractures are of different influence *** of different scale pore-fractures network can clearly display the connectivity of porefractures, which can provide a basis for selecting migration path and studying gas flow pattern.

关键词： Fractures network Different scales Reconstruction Permeability

A novel adaptive lateral reentry guidance algorithm with complex distributed no-fly zones constraints

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Chinese Journal of Aeronautics 2022年第7期35卷 128-143页

作者： Yudong HU Changsheng GAO Junlong LI Wuxing JING wenxue chen School of Astronautics Harbin Institute of TechnologyHarbin 150001China Beijing Institute of Electronic System Engineering China Aerospace Science and Industry CorporationBeijing 100854China

Aimed at complex distributed no-fly zones avoidance problems,a novel adaptive lateral reentry guidance algorithm is ***,by introducing the improved attractive and repulsive potential fields,an improved artificial potential field method is *** with the proposed judgment criterion for whether a no-fly zone has been avoided,the proposed improved artificial potential field method effectively solves the reference heading angle determination problem under the constraints of complex distributed no-fly ***,based on the proposed no-fly zone’s threat quantitative evaluation method and the reference heading angle determined by the proposed improved artificial potential field method,the heading corridor is improved to increase its sensitivity to the threat changes of the no-fly ***,for satisfying the requirements of complex distributed no-fly zones avoidance,a novel guidance logic via improved heading corridor is proposed to update the reference heading corridor adaptively in real time according to the threat and constraint changes of the no-fly zones,and the bank reversal logic is employed to control the lateral *** simulation results for nominal and dispersed cases indicate that the proposed guidance algorithm has high robustness,stability,and applicability,and is feasible and effective to deal with the complex distributed no-fly zones avoidance problems.

关键词： Guidance strategy Heading corridor Hypersonic vehicles Improved artificial potential field Lateral reentry guidance Threat quantitative evaluation

Methods for optical phase retardation measurement:A review

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Science China(Technological Sciences) 2013年第5期56卷 1155-1163页

作者： ZHANG Peng TAN YiDong LIU WeiXin chen wenxue State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentsTsinghua University

Optical-phase-retardation elements are widely used in many *** measurement of their phase retardation is crucial to the practical effect of the element's processing and *** development and present situation of the methods for optical phase retardation measurement are reviewed,with the wave plate,the most typical phase-retardation element,as an *** latest research progress in this field is introduced;the principles and characteristics of individual measurement method are summarized and *** new methods based on laser frequency splitting or laser feedback are presented in detail,in which the laser is not only regarded as a light source but also plays a role of ***,no standard wave plates are needed and arbitrary phase retardation can be ***,high precision and high repeatability are achieved as well.

关键词： optical measurement phase retardation wave plate frequency splitting laser feedback

Morphological structures of poly(vinylidene fluoride)/montmorillonite nanocomposites

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Science China Chemistry 2007年第6期50卷 790-796页

作者： SONG YuMing ZHAO ZhuDi YU wenxue LI Bo chen XinFang College of Materials Science and Engineering Jilin University Changchun 130012 China College of Materials Science and Engineering Jilin University Changchun 130012 China College of Materials Science and Engineering Jilin University Changchun 130012 China College of Materials Science and Engineering Jilin University Changchun 130012 China College of Materials Science and Engineering Jilin University Changchun 130012 China

Poly(vinylidene fluoride)(PVDF)/montmorillonite(MMT)nanocomposites were prepared by melt blending a kind of organically modified montmorillonite with *** morphological structures of the nanocomposites were studied using X-ray diffraction(XRD),transmission electron microscopy(TEM),Fourier transform infrared(FTIR)spectroscopy,and differential scanning calorimetry(DSC).The results indicate that organically modified montmorillonites are in the form of intercalation,exfoliation,and fragments in the PVDF *** the composites,the(001)peak position of MMT was found to shift to a lower angle in XRD patterns,and some MMT fragments could be observed under *** loading was favorable to producing the piezoelectric beta phase in the PVDF matrix and caused internal stress in a *** the same time,the crystallinity and spherulite size of PVDF decreased with the MMT *** induced beta phase is stable even at high temperatures(160℃).For these changes in morphological structures,some possible explanations were proposed based on the experimental results.

关键词： organically modified montmorillonite, nanocomposite, crystalline structure

Solderability and intermetallic compounds formation of Sn-9Zn-xAg lead-free solders wetted on Cu substrate

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Rare Metals 2009年第6期28卷 656-660页

作者： chen wenxue XUE Songbai WANG Hui WANG Jianxin HAN Zongjie College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

The eutectic Sn-9Zn alloy was doped with Ag （0 wt.%-1 wt.%） to form Sn-9Zn-xAg lead-free solder alloys. The effect of the addition of Ag on the microstructure and solderability of this alloy was investigated and intermetallic compounds （IMCs） formed at the solder/Cu interface were also examined in this study. The results show that, due to the addition of Ag, the microstructure of the solder changes. When the quantity of Ag is lower than 0.3 wt.%, the needle-like Zn-rich phase decreases gradually. However, when the quantity of Ag is 0.5 wt.%-1 wt.%, Ag-Zn intermetallic compounds appear in the solder. In particular, adding 0.3 wt.% Ag improves the wetting behavior due to the better oxidation resistance of the Sn-9Zn solder. The addition of an excessive amount of Ag will deteriorate the wetting property because the gluti- nosity and fluidity of Sn-9Zn-（0.5, 1）Ag solder decrease. The results also indicate that the addition of Ag to the Sn-Zn solder leads to the precipitation of ε-AgZn3 from the liquid solder on preformed interracial intermetallics （CusZn8）. The peripheral AgZn3, nodular on the Cu5Zn8 IMCs layer, is likely to be generated by a peritectic reaction L ＋ γ-Ag5Zns→AgZn3 and the following crystallization of AgZn3.

关键词： soldering materials lead-free solder wettability intermetallic compounds

Dissolution kinetics of Si and Al from montmorillonite in carbonic acid solution

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International Journal of Coal Science & Technology 2014年第1期1卷 31-38页

作者： Xiaoming Ni Quanzhong Li wenxue chen State Key Laboratory Cultivation Base for Gas Geology and Gas Control Henan Polytechnic UniversityJiaozuo 454000China School of Energy Science and Engineering Henan Polytechnic UniversityJiaozuo 454000China School of Civil Engineering Henan Polytechnic UniversityJiaozuo 454000China

The reaction between carbonic acid and montmorillonite minerals was studied in order to provide a theoretical basis for analyzing changes in the physical properties of coal seams after CO_(2)injection and for optimizing CO_(2) pumping parameters.A single montmorillonite mineral of purity[90%was selected and subjected to reactions at 25,35,and 45℃in carbonic acid solutions of varying *** Si and Al concentrations in the solutions and the structure and elemental compositions of the montmorillonite before and after the reactions were analyzed using a spectrophotometer,an X-ray diffractometer,and an energy-dispersive X-ray spectrometer;kinetic reaction models were established for the dissolution of Si and Al in carbonic acid solutions in order to estimate the apparent activation energy of Si dissolution under different acidity *** results indicate that Al dissolved rapidly and soon reached solubility *** the other hand,Si concentration in the solutions increased rapidly and then gradually declined with vibrations,with maximum values at 25,35,and 45℃,which were observed at approximately 96,72,and 48 h,*** addition,Si dissolution fitted the diffusion-controlled reaction model well;as the pH value decreased,the apparent activation energy of Si dissolution decreased,and Si became easier to ***,it was concluded that as a weak acid,carbonic acid causes little damage to the mineral structure of montmorillonite.

关键词： Montmorillonite Carbonic acid solution Dissolution of Si and Al Reaction kinetics

Linalool against Hafnia alvei,its antibacterial mechanism revealed by metabolomic analyses

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Food Bioscience 2023年第1期51卷 858-868页

作者： Luyao Gao Haiming chen wenxue chen Weijun chen Haoyu Jian Qiuping Zhong Ming Zhang HNU-HSF/LWL Collaborative Innovation Laboratory College of Food Science and EngineeringHainan University58 People RoadHaikou570228China Chunguang Agro-product Processing Institute Wenchang571333China College of Food Science and Engineering Northwest A&F UniversityYangling712100China

Linalool,a major component of aromatic plant essential oils,has an antibacterial effect against Hafnia alvei,which can induce food *** this study,we aimed to investigate the antibacterial effect and mechanism of linalool against *** treatment resulted in excessive reactive oxygen species(ROS)accumulation,which resulted in destruction of the cell *** to the field emission scanning electron microscopy(FESEM)and flow cytometry(FCM)results,it was confirmed that the membrane structure of *** was ***,metabolomics analysis showed that there were 64 and 73 differentially expressed metabolites screened by mass spectrometry in positive and negative ion modes,respectively,suggesting that nucleic acid metabolism,the respiratory chain and energy metabolism were negatively affected by *** validation confirmed that the activities of malate dehydrogenase(MDH),and succinate dehydrogenase(SDH)and respiratory metabolism were reduced after linalool *** was therefore concluded that the cell membrane was damaged,nucleic acid metabolism was disturbed,and energy metabolism was reduced by inhibition of the respiratory chain and tricarboxylic acid(TCA)*** results revealed the antibacterial mechanism of linalool against ***,and support the use of linalool as a potential natural preservative to control ***.

关键词： Linalool Hafnia alvei Antibacterial mechanism Metabolomics Respiratory metabolism Energy metabolism

A high-performance electrocatalyst for oxygen reduction derived from copolymer-anchored polyoxometalates

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Nano Research 2024年第6期17卷 5197-5205页

作者： Yue Du wenxue chen Zhiyi Zhong Zhixian Shi Yulin Zhang Xuanning chen Yisi Liu Dongbin Xiong Lina Zhou Zhenhui Liu Mingbo Zheng Hubei Key Laboratory of Photoelectric Materials and Devices&College of Material Science and Engineering Hubei Normal UniversityHuangshi 435002China College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The development and synthesis of cathode electrocatalysts with high activity and durable stability for metal-air batteries is an important challenge in the area of ***,we introduce a novel in-situ nitriding and phosphating strategy for producing W_(3)N_(4)and WP from phosphotungstic acid(HPW)-polyaniline-phytic acid-Fe3+organic-inorganic hybrid *** final material has a three-dimensional porous framework with W_(3)N_(4)-WP heterostructures embedded in the carbon matrix(W_(3)N_(4)-WP@NPC).As-made materials exhibit exceptional electrocatalytic performance for the oxygen reduction reaction(ORR),with a diffusion-limiting current density of 6.9 mA·cm^(−2)and a half-wave potential of 0.82 *** a Zn-air primary cathode,the W_(3)N_(4)-WP@NPC assembled battery can provide a relatively high peak power density(194.2 mW·cm^(−2)).As a Zn-air secondary air-cathode,it has great cycling stability over 500 *** work provides a simple and efficient method for rationally designing high-performance air cathodes from copolymer-anchored polyoxometalates.

关键词： W_(3)N_(4)-WP heterojunctions copolymer-anchored polyoxometalates oxygen reduction reaction Zn-air battery

One-step,in situ formation of WN-W_(2)C heterojunctions implanted on N doped carbon nanorods as efficient oxygen reduction catalyst for metal-air battery

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Nano Research 2023年第7期16卷 8773-8781页

作者： Yue Du wenxue chen Lina Zhou Rui Hu Shizhu Wang Xueqing Li Yunlong Xie Lun Yang Yisi Liu Zhenhui Liu Institute for Advanced Materials Hubei Normal UniversityHuangshi 435002China College of Material Science and Engineering Jiangsu Key Laboratory of Materials and Technology for Energy ConversionNanjing University of Aeronautics and AstronauticsNanjing 210016China

Transition metal nitrides and carbides have attracted intensive attentions in metal-air battery application due to their metallic electron transport behavior and high chemical stability toward the oxygen reduction reaction(ORR).Herein,the polyoxometalate@polyaniline composite derived WN-W_(2)C heterostructured composite(WN-W_(2)C@pDC)has been fabricated through an in situ nitriding-carbonization strategy,with WN-W_(2)C nanoparticles implanted on N doped carbon *** WN-W_(2)C@pDC demonstrates prominent electrocatalytic performance towards ORR and excellent cycling stability in metal-air battery,which possesses positive half-wave potential and large diffusion limiting current density(0.81 V and 5.8 mA·cm^(-2)).Moreover,it demonstrates high peak power density of 157.4 mW·cm^(-2)as Al-air primary cathode and excellent stability at the discharge-charge test(>500 h)of Zn-air secondary *** excellent activity and durability of WNW_(2)C@pDC catalyst should be attributed to the combined effect of intimate WN-W_(2)C heterointerfaces,unique embedded nanoparticles structure,and excellent electrical media of N doped carbon,confirmed by a series of contrast experiments.

关键词： WN-W_(2)C heterojunctions polyoxometalate@polyaniline composite oxygen reduction reaction metal-air battery