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EMI滤波器技术在开关电源中的应用与研究 被引量:8
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作者 曹海洋 张玉成 +1 位作者 朱启伟 郭攀峰 《电源学报》 2012年第1期76-79,共4页
开关电源由于其可靠性高、输出稳定等优点而广泛应用于电力电子系统中,但其自身产生的电磁干扰对整个系统的影响不容忽视。为了抑制开关电源所产生的传导电磁干扰,提出了集成EMI滤波的级联技术,并针对功率变换器的输出波形进行仿真。仿... 开关电源由于其可靠性高、输出稳定等优点而广泛应用于电力电子系统中,但其自身产生的电磁干扰对整个系统的影响不容忽视。为了抑制开关电源所产生的传导电磁干扰,提出了集成EMI滤波的级联技术,并针对功率变换器的输出波形进行仿真。仿真实验结果表明:这种级联的集成EMI滤波器对谐波有良好的抑制作用。 展开更多
关键词 开关电源 电磁干扰 功率变换器 EMI滤波器
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多烯脂肪酸尿素包合富集的研究 被引量:15
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作者 文震 余德顺 吕晴 《化学研究与应用》 CAS CSCD 北大核心 2001年第4期414-416,共3页
With the method of Urea inclusion,the content of α Linolenic acid (ALA) from perilla oil,Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) from fish oil were enriched.The results showed that with once separa... With the method of Urea inclusion,the content of α Linolenic acid (ALA) from perilla oil,Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) from fish oil were enriched.The results showed that with once separation,the purity of ALA and EPA+DHA was concentrated to 87.1% and above 70% respectively,the optimum conditions being given. 展开更多
关键词 多烯脂肪酸 Α-亚麻酸 EPA DHA 尿素 包合 富集
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Status and Development of Rapid Detection Technology for Tunnel Structural Defects 被引量:2
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作者 LIU Xuezeng FANG Maoliu +3 位作者 WU Dexing LI Yinping LIU Xingen LI Gang 《隧道建设(中英文)》 北大核心 2025年第4期657-676,I0005-I0024,共40页
Based on inspection data,the authors analyze and summarize the main types and distribution characteristics of tunnel structural defects.These defects are classified into three types:surface defects,internal defects,an... Based on inspection data,the authors analyze and summarize the main types and distribution characteristics of tunnel structural defects.These defects are classified into three types:surface defects,internal defects,and defects behind the structure.To address the need for rapid detection of different defect types,the current state of rapid detection technologies and equipment,both domestically and internationally,is systematically reviewed.The research reveals that surface defect detection technologies and equipment have developed rapidly in recent years.Notably,the integration of machine vision and laser scanning technologies have significantly improved detection efficiency and accuracy,achieving crack detection precision of up to 0.1 mm.However,the non-contact rapid detection of internal and behind-the-structure defects remains constrained by hardware limitations,with traditional detection remaining dominant.Nevertheless,phased array radar,ultrasonic,and acoustic vibration detection technologies have become research hotspots in recent years,offering promising directions for detecting these challenging defect types.Additionally,the application of multisensor fusion technology in rapid detection equipment has further enhanced detection capabilities.Devices such as cameras,3D laser scanners,infrared thermal imagers,and radar demonstrate significant advantages in rapid detection.Future research in tunnel inspection should prioritize breakthroughs in rapid detection technologies for internal and behind-the-structure defects.Efforts should also focus on developing multifunctional integrated detection vehicles that can simultaneously inspect both surface and internal structures.Furthermore,progress in fully automated,intelligent systems with precise defect identification and real-time reporting will be essential to significantly improve the efficiency and accuracy of tunnel inspection. 展开更多
关键词 TUNNEL structural defect inspection techniques inspection equipment rapid inspection
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Factors Affecting the Thermal Conductivity of Vacuum-Insulated Panels:a Review 被引量:1
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作者 RONG Xian YANG Yuqi ZHANG Jianxin 《材料导报》 北大核心 2025年第13期278-290,共13页
In recent years,there has been a growing global demand for carbon neutrality and energy efficiency,which are expected to become long-term trends.In the field of architecture,an effective approach to achieve this is to... In recent years,there has been a growing global demand for carbon neutrality and energy efficiency,which are expected to become long-term trends.In the field of architecture,an effective approach to achieve this is to reduce heat loss in buildings.Vacuum insulation panels(VIPs),a type of high-performance insulation material,have been increasingly utilised in the construction industry and have played an increa-singly important role as their performance and manufacturing processes continue to improve.This paper provides a review of the factors affecting the thermal conductivity of VIPs and presents a detailed overview of the research progress on core materials,barrier films,and getters.The current research status of VIPs is summarised,including their thermal conductivity,service life,and thermal bridging effects,as well as their applications in the field of architecture.This review aims to provide a comprehensive understanding for relevant practitioners on the factors influencing the thermal conductivity of VIPs,and based on which,measures can be taken to produce VIPs with lower thermal conductivity and longer service life. 展开更多
关键词 vacuum insulation panel thermal conductivity thermal insulation energy conservation
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High-inclination WO_(3)Deposition Enabled Fast-response Aqueous Zinc-ion Electrochromism 被引量:1
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作者 CHEN Shuo XING Kaixiao +6 位作者 LYU Ying YAO Xinxin LI Pan GUO Xiaoyang WANG Tienan LI Xiaotian LIU Xingyuan 《发光学报》 北大核心 2025年第6期1082-1094,共13页
Aqueous zinc-ion electrochromic(EC)technology,boasting the capability to fulfill both safety and cost-ef⁃fectiveness requirements,is garnering extensive attention in various application areas including smart windows,t... Aqueous zinc-ion electrochromic(EC)technology,boasting the capability to fulfill both safety and cost-ef⁃fectiveness requirements,is garnering extensive attention in various application areas including smart windows,thermal management,displays,and camouflage.However,typical inorganic EC materials,such as tungsten oxides(WO_(3)),of⁃ten suffer from slow ion diffusion kinetics and limited optical contrast within the aqueous Zn^(2+)electrolyte because of the large size and strong Coulombic interactions of the Zn^(2+),which limits their wide applicability.Here,ordered WO_(3)nanowire films,constructed by a one-step grazing angle deposition method,is demonstrated to boost the response speed and optical contrast during EC phenomena.Compared with dense films,the ordered WO_(3)nanowire films with a porosity of 44.6%demonstrate anti-reflective property and excellent comprehensive EC performance,including fast response time(3.6 s and 1.2 s for coloring and bleaching,respectively),large optical contrast(66.6%at 700 nm)and high col⁃oration efficiency(64.3 cm^(2)·C^(-1)).A large-area prototype EC device(17 cm×12 cm)with fast color-switching is also successfully achieved.Mechanistic studies show that the improved performance is mainly due to the ordered porous nanowire structures,which provides direct electron transfer paths and sufficient interfacial contacts,thus simultaneously enhancing the electrochemical activity and fast redox kinetics.This study provides a simple and effective strategy to im⁃prove the performance of tungsten oxide-based aqueous zinc ion EC materials and devices. 展开更多
关键词 electrochromic WO_(3) aqueous Zn^(2+)electrolyte ordered nanowires glancing angle deposition
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Environmental DNA assessment of fish diversity, distribution and niche characteristics in Zhutuo spawning ground in the upper reaches of the Yangtze River
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作者 LU Jia WANG Li +3 位作者 LI Ruijiao YANG Jin ZHANG Peng YANG Shengfa 《水利水电技术(中英文)》 北大核心 2025年第S1期454-467,共14页
[Objective]Implementation of the Ten-Year Fishing Ban policy may alter fish diversity and niche characteristics of dominant species in spawning grounds within the National Nature Reserve for Rare and Endemic Fish in t... [Objective]Implementation of the Ten-Year Fishing Ban policy may alter fish diversity and niche characteristics of dominant species in spawning grounds within the National Nature Reserve for Rare and Endemic Fish in the Upper Yangtze River.This study initiated continuous monitoring of natural spawning habitats from February 2022 to assess these ecological changes.[Methods]Environmental DNA(eDNA)metabarcoding was employed to analyze fish species composition,biodiversity patterns,and niche parameters of dominant species.Water sampling followed the CEN/TS 19461 standard across five monitoring transects(ZT1-ZT5).[Results]The eDNA analysis detected 45 species of fish belonging to 38 genera,13 families,and 3 orders were detected through environmental DNA(eDNA)in this survey,including 10 species endemic to the upper reaches of the Yangtze River,such as Procypris rabaudi and Myxocyprinus asiaticus.The fish community was mainly composed of bottom-dwelling,settling ovum-producing,omnivorous fish.The variation ranges of the Chao1 index,ACE index,Shannon index,and Simpson index are 736~996,719~965,1.58~3.23,and 0.83~0.99,respectively,indicating that fish species in spawning sites are abundant and community distribution uniformity is high.All indexes are highest at ZT1 monitoring points.Cluster analysis showed that,at a certain similarity level,fish community types in spawning sites could be basically divided into two groups:ZT1,ZT3,and ZT5 clustered together,and ZT2 and ZT4 clustered together,indicating similar fish community habitats.There are 9 dominant fish species in typical deep pool habitats in the reserve,with niche widths(Bi)ranging from 1.13 to 3.87.The dominant fish species are broad and medium niche fish,such as Cyprinus carpio and Hemiculter tchangi,with the niche overlap index(Oik)of some dominant fish species reaching more than 0.95.This indicates fierce competition for resources among the fish in this spawning ground.[Conclusion]The Zhutuo spawning ground demonstrates high species richness with homogeneous community structure and intense resource competition.This study establishes an eDNA-based monitoring framework that enhances conventional survey method,providing critical baseline data for adaptive management under the fishing moratorium regime. 展开更多
关键词 eDNA metabarcoding fishes endemic to the upper reaches of the Yangtze River spawning ground fish diversity niche characteristics
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Na and O Co-doped Carbon Nitride for Efficient Photocatalytic Hydrogen Evolution
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作者 CHEN Libo SHENG Ying +3 位作者 WU Ming SONG Jiling JIAN Jian SONG Erhong 《无机材料学报》 北大核心 2025年第5期552-560,I0011,I0012,共11页
Elemental doping is an effective strategy for tuning the band structure of graphite carbon nitride(CN)to enhance its photocatalytic performance.In this study,sodium(Na)and oxygen(O)co-doped carbon nitride(Na/O-CN_(x),... Elemental doping is an effective strategy for tuning the band structure of graphite carbon nitride(CN)to enhance its photocatalytic performance.In this study,sodium(Na)and oxygen(O)co-doped carbon nitride(Na/O-CN_(x),x=1.0,2.0,3.0,4.0)was synthesized via solid-phase reaction of sodium citrate(NaCA)and pure CN powder in the Teflon-sealed autoclave under air conditions at 180℃.Surface area of Na/O-CN_(3.0) is measured to be 18.8 m^(2)/g,increasing by 60.7%compared to that of pure CN(11.7 m^(2)/g).Bandgap energy of Na/O-CN_(3.0) is determined to be 2.68 eV,marginally lower than that of pure CN(2.70 eV),thereby enhancing its capacity for sunlight absorption.Meanwhile,the incorporation of Na and O atoms into Na/O-CN_(x) is found to effectively reduce recombination rates of photogenerated electron-hole pairs.As a result,Na/O-CN_(x) samples exhibit markedly enhanced photocatalytic hydrogen evolution activity under visible light irradiation.Notably,the optimal Na/O-CN_(3.0) sample achieves a photocatalytic hydrogen production rate of 103.2μmol·g^(–1)·h^(–1),which is 8.2 times greater than that of pure CN(11.2μmol·g^(–1)·h^(–1)).Furthermore,a series of Na/O-CN_(x)-yO_(2)(y=0,20%,40%,60%,80%,100%)samples were prepared by modulating the oxygen content within reaction atmosphere.The catalytic performance evaluations reveal that the incorporation of both Na and O atoms in Na/O-CN_(3.0) enhances photocatalytic activity.This study also introduces novel methodologies for synthesis of metal atom-doped CN materials at lower temperature,highlighting the synergistic effect of Na and O atoms in photocatalytic hydrogen production of Na/O-CN_(x) samples. 展开更多
关键词 Na and O co-doped carbon nitride synergistic effect visible light photocatalytic hydrogen evolution
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Peroxymonosulfate Activation by CoFe_(2)O_(4)/MgAl-LDH Catalyst for the Boosted Degradation of Antibiotic
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作者 LI Jianjun CHEN Fangming +5 位作者 ZHANG Lili WANG Lei ZHANG Liting CHEN Huiwen XUE Changguo XU Liangji 《无机材料学报》 北大核心 2025年第4期440-448,I0022-I0024,共12页
Owing to outstanding hydrophilicity and ionic interaction,layered double hydroxides(LDHs)have emerged as a promising carrier for high performance catalysts.However,the synthesis of new specialized catalytic LDHs for d... Owing to outstanding hydrophilicity and ionic interaction,layered double hydroxides(LDHs)have emerged as a promising carrier for high performance catalysts.However,the synthesis of new specialized catalytic LDHs for degradation of antibiotics still faces some challenges.In this study,a CoFe_(2)O_(4)/MgAl-LDH composite catalyst was synthesized using a hydrothermal coprecipitation method.Comprehensive characterization reveals that the surface of MgAl-LDH is covered with nanometer CoFe_(2)O_(4) particles.The specific surface area of CoFe_(2)O_(4)/MgAl-LDH is 82.84 m^(2)·g^(-)1,which is 2.34 times that of CoFe_(2)O_(4).CoFe_(2)O_(4)/MgAl-LDH has a saturation magnetic strength of 22.24 A·m^(2)·kg^(-1) facilitating efficient solid-liquid separation.The composite catalyst was employed to activate peroxymonosulfate(PMS)for the efficient degradation of tetracycline hydrochloride(TCH).It is found that the catalytic performance of CoFe_(2)O_(4)/MgAl-LDH significantly exceeds that of CoFe_(2)O_(4).The maximum TCH removal reaches 98.2%under the optimal conditions([TCH]=25 mg/L,[PMS]=1.5 mmol/L,CoFe_(2)O_(4)/MgAl-LDH=0.20 g/L,pH 7,and T=25℃).Coexisting ions in the solution,such as SO_(4)^(2-),Cl-,H_(2)PO_(4)^(-),and CO_(3)^(2-),have a negligible effect on catalytic performance.Cyclic tests demonstrate that the catalytic performance of CoFe_(2)O_(4)/MgAl-LDH remains 67.2%after five cycles.Mechanism investigations suggest that O_(2)^(•-)and ^(1)O_(2) produced by CoFe_(2)O_(4)/MgAl-LDH play a critical role in the catalytic degradation. 展开更多
关键词 magnetic composite catalyst PEROXYMONOSULFATE CoFe_(2)O_(4)/MgAl-LDH advanced oxidation process antibiotic
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N/O co-doped microporous carbon as a high-performance electrode for supercapacitors
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作者 YAN Jing-jing FANG Xiao-hao +3 位作者 YAO De-zhou ZHU Cheng-wei SHI Jian-jun QIAN Shan-shan 《新型炭材料(中英文)》 北大核心 2025年第1期231-242,共12页
Carbon materials with adjustable porosity,controllable het-eroatom doping and low-cost have been received considerable attention as supercapacitor electrodes.However,using carbon materials with abundant micropores,a h... Carbon materials with adjustable porosity,controllable het-eroatom doping and low-cost have been received considerable attention as supercapacitor electrodes.However,using carbon materials with abundant micropores,a high surface area and a high-dopant content for an aqueous su-percapacitor with a high energy output still remains a challenge.We report the easy synthesis of interconnected carbon spheres by a polymerization re-action between p-benzaldehyde and 2,6-diaminopyridine.The synthesis in-volves adjusting the mass ratio of the copolymer and KOH activator to achieve increased charge storage ability and high energy output,which are attributed to the high ion-accessible area provided by the large number of micropores,high N/O contents and rapid ion diffusion channels in the porous structure.At a PMEC∶KOH mass ratio of 1∶1,the high electrolyte ion-adsorption area(2599.76 m^(2) g^(−1))and the N/O dopant atoms of the conductive framework of a typical carbon electrode produce a superior specific capacity(303.2 F g^(−1)@0.5 A g^(−1))giving an assembled symmetric capacitor a high energy delivery of 11.3 Wh kg^(−1)@250 W kg^(−1).This study presents a simple strategy for synthesizing microporous carbon and highlights its potential use in KOH-based supercapacitors. 展开更多
关键词 N/O codoping Carbon electrode Microporous structure High energy density SUPERCAPACITOR
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A N-doped carbon with encapsulated Fe and Co particles derived from a metal organic framework for use as the anode in lithium-ion batteries
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作者 CHEN Ren-tian ZHU Yu-xin +5 位作者 LUO Rui JIANG Xiao-nuo SI Hong-xiang QIU Xiang-yun WANG Qian WEI Tao 《新型炭材料(中英文)》 北大核心 2025年第2期363-376,共14页
Metal-organic frameworks(MOFs)are import-ant as possible energy storage materials.Nitrogen-doped iron-cobalt MOFs were synthesized by a one-pot solvo-thermal method using CoCl_(3)·6H_(2)O and FeCl_(3)·6H_(2)... Metal-organic frameworks(MOFs)are import-ant as possible energy storage materials.Nitrogen-doped iron-cobalt MOFs were synthesized by a one-pot solvo-thermal method using CoCl_(3)·6H_(2)O and FeCl_(3)·6H_(2)O dis-solved in N,N-dimethylformamide,and were converted into Fe-Co embedded in N-doped porous carbon polyhedra by pyrolysis in a nitrogen atmosphere.During pyrolysis,the or-ganic ligands transformed into N-doped porous carbon which improved their structural stability and also their electrical contact with other materials.The Fe and Co are tightly bound together because of their encapsulation by the carbon nitride and are well dispersed in the carbon matrix,and improve the material’s conductivity and stability and provide additional capacity.When used as the anode for lithium-ion batteries,the material gives an initial capacity of up to 2230.7 mAh g^(-1)and a reversible capa-city of 1146.3 mAh g^(-1)is retained after 500 cycles at a current density of 0.5 A g^(-1),making it an excellent candidate for this purpose. 展开更多
关键词 Metal-organic frameworks FeCo alloy Lithium-ion battery Anode materials
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Ionic Liquid Enhanced Proton Transfer for Neutral Oxygen Evolution Reaction
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作者 Ming-Xing Chen Nian Liu +2 位作者 Zi-He Du Jing Qi Rui Cao 《电化学(中英文)》 北大核心 2025年第7期27-36,共10页
The development of highly active catalyst in pH-neutral media for oxygen evolution reaction(OER)is critical in the field of renewable energy storage and conversion.Nevertheless,the slow kinetics of proton-coupled elec... The development of highly active catalyst in pH-neutral media for oxygen evolution reaction(OER)is critical in the field of renewable energy storage and conversion.Nevertheless,the slow kinetics of proton-coupled electron transfer(PCET)hinders the overall OER efficiency.Herein,we report an ionic liquid(IL)modified CoSn(OH)_(6)nanocubes(denoted as CoS-n(OH)_(6)-IL),which could be prepared through a facile strategy.The modified IL would not change the structural character-istics of CoSn(OH)_(6),but could effectively regulate the local proton activity near the active sites.The CoSn(OH)_(6)-IL exhibited higher intrinsic OER performances than the pristine CoSn(OH)_(6)in neutral media.For example,the current density of CoS-n(OH)_(6)-IL at 1.8 V versus reversible hydrogen electrode(RHE)was about 4 times higher than that of CoSn(OH)_(6).According to the pH-dependent kinetic investigations,operando electrochemical impedance spectroscopic,chemical probe tests,and deuterium kinetic isotope effects,the interfacial layer of IL could be utilized as a proton transfer mediator to promote the proton transfer,which enhances the surface coverage of OER intermediates and reduces the activation barrier.Consequent-ly,the sluggish OER kinetics would be efficiently accelerated.This study provides a facile and effective strategy to facilitate the PCET processes and is beneficial to guide the rational design of OER electrocatalysts. 展开更多
关键词 ELECTROCATALYSIS Oxygen evolution reaction Ionic liquid Proton transfer CoSn(OH)_(6)nanocube
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Design of Underground Load Haul Dump Hybrid Power System Based on QFD and TRIZ
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作者 XU Jun QIAO Sha +3 位作者 MA Xiaowen YUAN Kun QI Wenbo LIU Keyi 《有色金属(中英文)》 北大核心 2025年第3期462-473,共12页
As the mining industry continues to expand and international oil prices increase,more rigorous demands are being placed on the design of mining equipment.Given this,there is an urgent need to develop new power-driven ... As the mining industry continues to expand and international oil prices increase,more rigorous demands are being placed on the design of mining equipment.Given this,there is an urgent need to develop new power-driven mining equipment to solve the problems of high energy consumption and insufficient power coupling of current equipment.This study proposed a design of a hybrid power system for underground Load Haul Dump(LHD).The proposed design integrated Quality Function Deployment(QFD)and Theory of Inventive Problem Solving(TRIZ).It identified 7 user requirements and 10 related technical features,formulated 11 innovative design solutions,and ultimately adopting an electric drive hybrid power scheme.This scheme effectively addressesd power transmission coupling problems and improve the efficiency of loaders.A 6 m³hybrid power loader prototype has been developed,which reduces operational energy consumption and advances the electrification and green,low-carbon evolution of mining equipment. 展开更多
关键词 quality function deployment TRIZ LHD design solution
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Design and testing of a liftable chassis for rice harvester
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作者 YANG Ke LI Ju +3 位作者 CHEN Yu LI Hao AO Yu LEI Xiaolong 《智能化农业装备学报(中英文)》 2025年第1期59-70,共12页
During the operation of the rice combine harvester,the fuselage tilts due to the tilt and unevenness of the ground affect its maneuverability and operational reliability.Aiming at the problem of leveling due to the ti... During the operation of the rice combine harvester,the fuselage tilts due to the tilt and unevenness of the ground affect its maneuverability and operational reliability.Aiming at the problem of leveling due to the tilt of the field surface,this research developed an innovative dual-parallelogram chassis lifting mechanism for rice harvesters designed a hydraulic system to adjust the chassis height by extending the cylinder.Using Adams simulation software,a detailed model of the lifting chassis was constructed to analyze its performance,revealing a direct correlation between the hydraulic cylinder extension and chassis elevation.Notably,the mechanism could achieve leveling on slopes with inclination angles of up to 7.5°.Comprehensive evaluations of the liftable chassis system were conducted under both static and dynamic conditions.In the static tests,the system exhibited the capacity for comprehensive or unilateral auto-leveling contingent upon the tilt,with leveling times and angular variations confined to 3.6 s and±0.4°,respectively.In dynamic tests conducted on sloped fields and paddy soils,the system reduced post-leveling mean tilt angles and standard deviations remained below 1.2°and 0.6°,respectively.These results demonstrated a substantial improvement in the stability and reliability of the chassis during operations.This research provides valuable insights into the design and optimization of automatic leveling mechanisms and structural innovations for harvester chassis. 展开更多
关键词 rice combine harvester chassis lifting mechanism hydraulic leveling leveling time
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High-Precision Fish Pose Estimation Method Based on Improved HRNet
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作者 PENG Qiujun LI Weiran +1 位作者 LIU Yeqiang LI Zhenbo 《智慧农业(中英文)》 2025年第3期160-172,共13页
[Objective]Fish pose estimation(FPE)provides fish physiological information,facilitating health monitoring in aquaculture.It aids decision-making in areas such as fish behavior recognition.When fish are injured or def... [Objective]Fish pose estimation(FPE)provides fish physiological information,facilitating health monitoring in aquaculture.It aids decision-making in areas such as fish behavior recognition.When fish are injured or deficient,they often display abnormal behaviors and noticeable changes in the positioning of their body parts.Moreover,the unpredictable posture and orientation of fish during swimming,combined with the rapid swimming speed of fish,restrict the current scope of research in FPE.In this research,a FPE model named HPFPE is presented to capture the swimming posture of fish and accurately detect their key points.[Methods]On the one hand,this model incorporated the CBAM module into the HRNet framework.The attention module enhanced accuracy without adding computational complexity,while effectively capturing a broader range of contextual information.On the other hand,the model incorporated dilated convolution to increase the receptive field,allowing it to capture more spatial context.[Results and Discussions]Experiments showed that compared with the baseline method,the average precision(AP)of HPFPE based on different backbones and input sizes on the oplegnathus punctatus datasets had increased by 0.62,1.35,1.76,and 1.28 percent point,respectively,while the average recall(AR)had also increased by 0.85,1.50,1.40,and 1.00,respectively.Additionally,HPFPE outperformed other mainstream methods,including DeepPose,CPM,SCNet,and Lite-HRNet.Furthermore,when compared to other methods using the ornamental fish data,HPFPE achieved the highest AP and AR values of 52.96%,and 59.50%,respectively.[Conclusions]The proposed HPFPE can accurately estimate fish posture and assess their swimming patterns,serving as a valuable reference for applications such as fish behavior recognition. 展开更多
关键词 AQUACULTURE computer vision fish pose estimation key point attention mechanism
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寒区湿地重迎茬大豆亩产150165公斤技术模式
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作者 文安奎 《大豆通报》 1997年第5期14-14,共1页
寒区湿地重迎茬大豆亩产150165公斤技术模式同江市农业科技术开发研究中心·同江市15640文安奎为探索三江平原寒区湿地重迎茬大豆高产稳产优质高效途径,针对重迎茬大豆产量低而不稳,品质下降,病虫草害加剧、养分失... 寒区湿地重迎茬大豆亩产150165公斤技术模式同江市农业科技术开发研究中心·同江市15640文安奎为探索三江平原寒区湿地重迎茬大豆高产稳产优质高效途径,针对重迎茬大豆产量低而不稳,品质下降,病虫草害加剧、养分失衡、毒害趋重等问题,把“良种、两深、一... 展开更多
关键词 大豆 重迎茬 寒区湿地 栽培
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Syntheses,crystal structures,and catalytic properties of three zinc(Ⅱ),cobalt(Ⅱ)and nickel(Ⅱ)coordination polymers constructed from 5⁃(4⁃carboxyphenoxy)nicotinic acid 被引量:2
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作者 LING Weizhong CHEN Xiangyun +2 位作者 LIU Wenjing HUANG Yingkai LI Yu 《无机化学学报》 SCIE CAS CSCD 北大核心 2024年第9期1803-1810,共8页
Three zinc(Ⅱ),cobalt(Ⅱ),and nickel(Ⅱ)coordination polymers,namely[Zn(μ^(3-)cpna)(μ-dpea)_(0.5)]_(n)(1),[Co(μ^(3-)cpna)(μ-dpey)_(0.5)]_(n)(2),and[Ni(μ^(3-)cpna)(μ-dpey)_(0.5)(H_(2)O)]_(n)(3),have been construc... Three zinc(Ⅱ),cobalt(Ⅱ),and nickel(Ⅱ)coordination polymers,namely[Zn(μ^(3-)cpna)(μ-dpea)_(0.5)]_(n)(1),[Co(μ^(3-)cpna)(μ-dpey)_(0.5)]_(n)(2),and[Ni(μ^(3-)cpna)(μ-dpey)_(0.5)(H_(2)O)]_(n)(3),have been constructed hydrothermally using H_(2)cpna(5-(4-carboxyphenoxy)nicotinic acid),dpea(1,2-di(4-pyridyl)ethane),dpey(1,2-di(4-pyridyl)ethylene),and zinc,cobalt,and nickel chlorides at 160℃.The products were isolated as stable crystalline solids and were characterized by IR spectra,elemental analyses,thermogravimetric analyses,and single-crystal X-ray diffraction analyses.Single-crystal X-ray diffraction analyses revealed that three compounds crystallize in the triclinic system,space group P1.Compounds 1-3 show 2D layer structures.The catalytic activities in the Knoevenagel condensation reaction of these compounds were investigated.Compounds 1 and 2 exhibit effective catalytic activities in the Knoevenagel condensa-tion reaction at room temperature.For this reaction,various parameters were optimized,followed by the investiga-tion of the substrate scope.CCDC:2335676,1;2335677,2;2335678,3. 展开更多
关键词 coordination polymer dicarboxylic acid catalytic property Knoevenagel condensation reaction
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Anti-TMV activity and mnode of action of perillaldehyde in perilla essential oil 被引量:1
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作者 LUO Wei JIANG Yue +6 位作者 WANG Kaiyue LUO Jingyi LIU Yingchen ZHANG Yueyang MA Zhiqing YAN He WANG Kang 《农药学学报》 CAS CSCD 北大核心 2024年第4期744-756,共13页
Perilla essential oil(PEO)is reported as an aromatic yellowish oily substance with a volatile odor extracted from perilla leaves.It exhibits various biological activities except anti-tobacco mosaic virus(TMV)activity.... Perilla essential oil(PEO)is reported as an aromatic yellowish oily substance with a volatile odor extracted from perilla leaves.It exhibits various biological activities except anti-tobacco mosaic virus(TMV)activity.In this study,we investigated the main components and anti-TMV activity of PEO,identified its primary active components,and examined its mode of action.The results indicated that PEO exhibited anti-TMV activity(65.58%)at 800μg/mL,with perillaldehyde identified as the main active component.The protective,curative,and inactivation activities of perillaldehyde at 800μg/mL were 80.41%,73.42%,and 34.93%,respectively.These values were significantly higher than those of the control drug(commercial chitosan oligosaccharide)and the protective and curative activities were superior to those of ningnanmycin.The results of the mode of action showed that perillaldehyde induced a hypersensitive response(HR)in tobacco.Transmission electron microscope(TEM)observation revealed that perillaldehyde had no direct effect on TMV particles.The treatment of Nicotiana glutinosa with perillaldehyde at 800μg/mL indicated that perillaldehyde had significant induction activity(58.46%).The expression of three pathogenesis-related tobacco genes(PR genes),including nonexpressor of pathogenesis-related genes 1(NPR1),pathogenesis-related protein 1 gene(PR1),and pathogenesis-related protein 5 gene(PR5),were induced and upregulated by perillaldehyde treatment.Perillaldehyde also induced the overexpression of the phenylalanine ammonia-lyase gene(PAL),respiratory burst oxidase homolog B gene(RBOHB),and protochlorophyllide oxidoreductase gene 1(POR1).Furthermore,perillaldehyde increased the salicylic acid(SA)and H2O2 contents in tobacco leaves,and enhanced the activities of four defense enzymes:superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),and phenylalanine ammonia-lyase(PAL).N.glutinosa was treated with perillaldehyde at 800μg/mL for 24 h,and the results showed that the highest SA and H_(2)O_(2) contents(1032.08 pmol/L and 23.40μmol/g FW,respectively)were obtained in tobacco leaves.Defense enzyme activities also reached a maximum at 800μg/mL,and the activities of CAT,PAL,POD,and SOD increased by 1.76,1.95,2.17,and 3.78 times,respectively,compared to the control.The results of the study showed that perillaldehyde may enhance resistance to pathogen infection by inducing systemic acquired resistance(SAR),which may contribute to the activation of SA signal transduction pathway.Therefore,perillaldehyde has the potential for application in agriculture as a novel antiviral agent and immune inducer. 展开更多
关键词 perilla essential oil perillaldehyde tobacco mosaic virus(TMV) induced resistance systemic acquired resistance(SAR) plant immunity
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Enhancing Photocatalytic Hydrogen Evolution through Electronic Structure and Wettability Adjustment of ZnIn_(2)S_(4)/Bi_(2)O_(3) S-Scheme Heterojunction 被引量:1
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作者 Linfeng Xiao Wanlu Ren +4 位作者 Shishi Shen Mengshan Chen Runhua Liao Yingtang Zhou Xibao Li 《物理化学学报》 SCIE CAS CSCD 北大核心 2024年第8期50-63,共14页
The production of renewable fuels through water splitting via photocatalytic hydrogen production holds significant promise.Nonetheless,the sluggish kinetics of hydrogen evolution and the inadequate water adsorption on... The production of renewable fuels through water splitting via photocatalytic hydrogen production holds significant promise.Nonetheless,the sluggish kinetics of hydrogen evolution and the inadequate water adsorption on photocatalysts present notable challenges.In this study,we have devised a straightforward hydrothermal method to synthesize Bi_(2)O_(3)(BO)derived from metal‐organic frameworks(MOFs),loaded with flower-like ZnIn_(2)S_(4)(ZIS).This approach substantially enhances water adsorption and surface catalytic reactions,resulting in a remarkable enhancement of photocatalytic activity.By employing triethanolamine(TEOA)as a sacrificial agent,the hydrogen evolution rate achieved with 15%(mass fraction)ZIS loading on BO reached an impressive value of 1610μmol∙h^(−1)∙g^(−1),marking a 6.34-fold increase compared to that observed for bare BO.Furthermore,through density functional theory(DFT)and ab initio molecular dynamics(AIMD)calculations,we have identified the reactions occurring at the ZIS/BO S-scheme heterojunction interface,including the identification of active sites for water adsorption and catalytic reactions.This study provides valuable insights into the development of high-performance composite photocatalytic materials with tailored electronic properties and wettability. 展开更多
关键词 S-scheme Hydrogen evolution WETTABILITY PHOTOCATALYSIS Electronic structure
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Computational Simulation of Aptamer-target Binding Mechanisms
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作者 YANG Yuan-Yuan XU Fei WU Xiu-Xiu 《中国生物化学与分子生物学报》 CAS CSCD 北大核心 2024年第11期1550-1562,共13页
Aptamers are a type of single-chain oligonucleotide that can combine with a specific target.Due to their simple preparation,easy modification,stable structure and reusability,aptamers have been widely applied as bioch... Aptamers are a type of single-chain oligonucleotide that can combine with a specific target.Due to their simple preparation,easy modification,stable structure and reusability,aptamers have been widely applied as biochemical sensors for medicine,food safety and environmental monitoring.However,there is little research on aptamer-target binding mechanisms,which limits their application and development.Computational simulation has gained much attention for revealing aptamer-target binding mechanisms at the atomic level.This work summarizes the main simulation methods used in the mechanistic analysis of aptamer-target complexes,the characteristics of binding between aptamers and different targets(metal ions,small organic molecules,biomacromolecules,cells,bacteria and viruses),the types of aptamer-target interactions and the factors influencing their strength.It provides a reference for further use of simulations in understanding aptamer-target binding mechanisms. 展开更多
关键词 computational simulation APTAMER TARGET binding mechanism intermolecular forces
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Laser-assisted water jet machining of high quality micro-trap structures on stainless steel surfaces
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作者 LIU Li YAO Peng +3 位作者 CHU Dong-kai XU Xiang-yue QU Shuo-shuo HUANG Chuan-zhen 《中国光学(中英文)》 EI CAS CSCD 北大核心 2024年第6期1476-1488,共13页
Secondary electron emission(SEE)has emerged as a critical issue in next-generation accelerators.Mitigating SEE on metal surfaces is crucial for enhancing the stability and emittance of particle accelerators while exte... Secondary electron emission(SEE)has emerged as a critical issue in next-generation accelerators.Mitigating SEE on metal surfaces is crucial for enhancing the stability and emittance of particle accelerators while extending their lifespan.This paper explores the application of laser-assisted water jet technology in constructing high-quality micro-trap structures on 316L stainless steel,a key material in accelerator manufacturing.The study systematically analyzes the impact of various parameters such as laser repetition frequency,pulse duration,average power,water jet pressure,repeat times,nozzle offset,focal position,offset distance between grooves,and processing speed on the surface morphology of stainless steel.The findings reveal that micro-groove depth increases with higher laser power but decreases with increasing water jet pressure and processing speed.Interestingly,repeat times have minimal effect on depth.On the other hand,micro-groove width increases with higher laser power and repeat times but decreases with processing speed.By optimizing these parameters,the researchers achieved high-quality pound sign-shaped trap structure with consistent dimensions.We tested the secondary electron emission coefficient of the"well"structure.The coefficient is reduced by 0.5 at most compared to before processing,effectively suppressing secondary electron emission.These results offer indispensable insights for the fabrication of micro-trap structures on material surfaces.Laser-assisted water jet technology demonstrates considerable potential in mitigating SEE on metal surfaces. 展开更多
关键词 laser-assisted water jet 316L stainless steel micro-trap structures "well"structure surface morphology secondary electron emission(SEE) groove depth groove width
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