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Dual-Unloading Mode Autonomous Operation Strategy and Cotransporter System for Rice Harvester and Transporter 被引量:1
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作者 fan ding Xiwen Luo +6 位作者 Zhigang Zhang Lian Hu Xinluo Wu Kaiyuan Bao Jiarui Zhang Bingxuan Yuan Wenyu Zhang 《Engineering》 2025年第5期220-233,共14页
To achieve an unmanned rice farm,in this study,a cotransporter system was developed using a tracked rice harvester and transporter for autonomous harvesting,unloading,and transportation.Additionally,two unloading and ... To achieve an unmanned rice farm,in this study,a cotransporter system was developed using a tracked rice harvester and transporter for autonomous harvesting,unloading,and transportation.Additionally,two unloading and transportation modes—harvester waiting for unloading(HWU)and transporter fol-lowing for unloading(TFU)—were proposed,and a harvesting-unloading-transportation(HUT)strategy was defined.By breaking down the main stages of the collaborative operation,designing module-state machines(MSMs),and constructing state-transition chains,a HUT collaborative operation logic frame-work suitable for the embedded navigation controller was designed using the concept and method of the finite-state machine(FSM).This method addresses the multiple-stage,nonsequential,and complex processes in HUT collaborative operations.Simulations and field-harvesting experiments were performed to evaluate the applicability of this proposed strategy and system.The experimental results showed that the HUT collaborative operation strategy effectively integrated path planning,path-tracking control,inter-vehicle communication,collaborative operation control,and implementation control.The cotrans-porter system completed the entire process of harvesting,unloading,and transportation.The field-harvesting experiment revealed that a harvest efficiency of 0.42 hm^(2)·h^(−1) was achieved.This study can provide insight into collaborative harvesting and solutions for the harvesting process of unmanned farms. 展开更多
关键词 Agricultural machinery Harvesting-unloading-transportation strategy Cotransporter system Unmanned farm Finite-state machine
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超声辅助SiO_(2)纳米颗粒强化铝/铜等离子弧熔钎焊工艺
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作者 樊丁 张欢 +2 位作者 黄健康 李岩 谢宇航 《材料工程》 北大核心 2025年第2期133-141,共9页
利用超声波辅助纳米强化等离子弧熔钎焊工艺成功实现了铝/铜异种金属的连接,并获得了形态良好的铝/铜搭接接头。使用SEM、EDS、XRD、拉伸实验和导电性能测试等方法,分析研究了超声波和SiO_(2)纳米颗粒对搭接接头的宏观和微观形貌、组织... 利用超声波辅助纳米强化等离子弧熔钎焊工艺成功实现了铝/铜异种金属的连接,并获得了形态良好的铝/铜搭接接头。使用SEM、EDS、XRD、拉伸实验和导电性能测试等方法,分析研究了超声波和SiO_(2)纳米颗粒对搭接接头的宏观和微观形貌、组织结构、力学性能以及导电性能的影响。结果表明:在超声波和SiO_(2)纳米颗粒耦合作用下得到的搭接接头,液态铝在铜表面的铺展和润湿效果更好,焊缝正面成形良好,接头主要由金属间化合物层区和Al-Cu共晶区组成,金属间化合物层的厚度明显减小,接头力学性能显著提高,采用了SiO_(2)纳米颗粒和超声波的铝/铜接头的相对电导率为153.527%IACS,导电性能有所改善。 展开更多
关键词 超声振动 SiO_(2)纳米颗粒 金属间化合物 力学性能 导电性能
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广西钦州荔枝产业发展现状及对策研究
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作者 刘宇昊 刘洋 +12 位作者 章睿 马致远 黎运梅 范鼎 郭泓廷 黄威呈 张艳青 徐炯志 郭标 丁峰 李彦彦 贾海锋 邱海吉 《中国果树》 2025年第10期148-153,共6页
荔枝是中国传统的热带优势农产品,在广西钦州市有着悠久的种植历史和广泛的种植基础。钦州市作为广西第一大荔枝主产区及全国第二大荔枝产地,其荔枝产业的发展不仅关乎当地农民的生活福祉,对全国荔枝市场的稳定与繁荣也具有重要意义。... 荔枝是中国传统的热带优势农产品,在广西钦州市有着悠久的种植历史和广泛的种植基础。钦州市作为广西第一大荔枝主产区及全国第二大荔枝产地,其荔枝产业的发展不仅关乎当地农民的生活福祉,对全国荔枝市场的稳定与繁荣也具有重要意义。在我国特色果业迈向高质量发展的关键时期,通过对钦州市荔枝产业的深入调查与分析,探讨钦州市荔枝产业的发展现状与面临的挑战,并提出相应的对策与建议,旨在为广西乃至全国荔枝产业的可持续发展提供理论支撑和实践指导,推动荔枝产业转型升级,实现农民收入持续增长。 展开更多
关键词 广西 钦州 荔枝 产业现状 对策
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柴胡及其方药制剂在畜禽生产中的应用进展
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作者 王婷 范丁 +4 位作者 谢文伟 叶锴 丁励 张贞贞 陈华丽 《饲料研究》 北大核心 2025年第17期169-174,共6页
柴胡作为我国传统中草药,其主要活性成分包括柴胡皂苷、多糖和黄酮类等,具有抗炎、抗菌、抗病毒和抗应激等多种功效。在畜禽生产中,柴胡及其方药制剂(如小柴胡汤、柴胡注射液等)作为绿色饲料添加剂和抗生素替代物,展现出显著的应用潜力... 柴胡作为我国传统中草药,其主要活性成分包括柴胡皂苷、多糖和黄酮类等,具有抗炎、抗菌、抗病毒和抗应激等多种功效。在畜禽生产中,柴胡及其方药制剂(如小柴胡汤、柴胡注射液等)作为绿色饲料添加剂和抗生素替代物,展现出显著的应用潜力。柴胡及其方药制剂能够改善家禽、猪、反刍动物及水产动物的生长性能,增强机体免疫功能,缓解热应激和氧化损伤,改善畜产品品质。柴胡复方制剂间的协同作用可克服病原菌耐药性,降低畜禽疾病发生率。文章综述了柴胡及其方药制剂的活性成分、生物学功能及其在畜禽生产中的应用进展,为柴胡在畜禽生产中的深入应用提供参考。 展开更多
关键词 柴胡 方药制剂 畜禽生产 免疫调节
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Mg-Li-Cu alloy anode for highly reversible lithium metal batteries
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作者 Xinbin Li Shuai Liu +7 位作者 fangya Li Kaiwen Ma Hao Xu Zhiang Li fan ding Zhenhua Yan Runhua fan Hongzhi Cui 《Journal of Magnesium and Alloys》 2025年第5期2144-2154,共11页
Lithium metal is considered as the most promising anode material for the next generation of secondary batteries due to its high theoretical specific capacity and low potential.However,undesirable parasitic reactions,p... Lithium metal is considered as the most promising anode material for the next generation of secondary batteries due to its high theoretical specific capacity and low potential.However,undesirable parasitic reactions,poor cycling stability and safety concerns could be caused by uncontrolled dendrite and high reactivity of Li metal,which hinder the practical application of Li-metal anode in high-energy rechargeable Li metal batteries(LMBs).Here,a facile way is reported to stabilize Li metal anode by building high lithiophilic Mg-Li-Cu alloy.Due to the delocalization of electrons on the deposited lithium enhanced by Cu self-diffusion into Mg-Li alloy,the growth of lithium dendrites could be inhibited by Mg-Li-Cu alloy.Moreover,the parasitic reactions with electrolyte could be avoided by the Mg-Li-Cu alloy anode.It is noteworthy that the symmetric battery life of Mg-Li-Cu alloy electrodes exceeds 9000 h at 1 m A cm^(-2)and 1 m Ah cm^(-2).The full cell(LiFePO_(4)|Mg-Li-Cu)exhibits a specific capacity of 148.2 m Ah g^(-1),with a capacity retention of 96.4%,at 1 C after 500 cycles.This work not only pave the way for application of flexible alloy anode in highly stable LMBs,but also provides novel strategies for preparation and optimization of Mg alloy. 展开更多
关键词 SELF-DIFFUSION Delocalization of electrons Mg-Li-Cu alloy Li dendrite Lithium metal battery
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Modeling, Simulation and Control of Pulsed DE-GMA Welding Process for Joining of Aluminum to Steel 被引量:3
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作者 ZHANG Gang SHI Yu +2 位作者 LI Jie HUANG Jiankang fan ding 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2014年第5期978-985,共8页
Joining of aluminum to steel has attracted significant attention from the welding research community,automotive and rail transportation industries.Many current welding methods have been developed and applied,however,t... Joining of aluminum to steel has attracted significant attention from the welding research community,automotive and rail transportation industries.Many current welding methods have been developed and applied,however,they can not precisely control the heat input to work-piece,they are high costs,low efficiency and consist lots of complex welding devices,and the generated intermetallic compound layer in weld bead interface is thicker.A novel pulsed double electrode gas metal arc welding(Pulsed DE-GMAW)method is developed.To achieve a stable welding process for joining of aluminum to steel,a mathematical model of coupled arc is established,and a new control scheme that uses the average feedback arc voltage of main loop to adjust the wire feed speed to control coupled arc length is proposed and developed.Then,the impulse control simulation of coupled arc length,wire feed speed and wire extension is conducted to demonstrate the mathematical model and predict the stability of welding process by changing the distance of contact tip to work-piece(CTWD).To prove the proposed PSO based PID control scheme’s feasibility,the rapid prototyping experimental system is setup and the bead-on-plate control experiments are conducted to join aluminum to steel.The impulse control simulation shows that the established model can accurately represent the variation of coupled arc length,wire feed speed and the average main arc voltage when the welding process is disturbed,and the developed controller has a faster response and adjustment,only runs about 0.1 s.The captured electric signals show the main arc voltage gradually closes to the supposed arc voltage by adjusting the wire feed speed in 0.8 s.The obtained typical current waveform demonstrates that the main current can be reduced by controlling the bypass current under maintaining a relative large total current.The control experiment proves the accuracy of proposed model and feasibility of new control scheme further.The beautiful and smooth weld beads are also obtained by this method.Pulsed DE-GMAW can thus be considered as an alternative method for low cost,high efficiency joining of aluminum to steel. 展开更多
关键词 pulsed double electrode gas metal arc welding dissimilar metals simulation and control particle swarm optimization
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Numerical analysis of arc-droplet behavior in thin wire high current MAG welding with magnetic control 被引量:4
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作者 樊丁 王亚洲 +1 位作者 李德全 黄健康 《China Welding》 CAS 2023年第4期29-37,共9页
High efficiency welding has always been one of the hot research subjects at home and overseas. Aiming at the problem of unstable droplet rotating spray transfer process in 450 A thin wire metal active gas arc(MAG) wel... High efficiency welding has always been one of the hot research subjects at home and overseas. Aiming at the problem of unstable droplet rotating spray transfer process in 450 A thin wire metal active gas arc(MAG) welding, a three-dimensional arc-droplet coupled model is established in this paper on the base of fluid dynamics to conduct numerical analysis for droplet transfer behavior with external magnetic controlled MAG welding, and used high-speed camera system to verify the simulation results. The results indicate that without external magnetic field, the droplet is transferred by the way of rotating spray, the arc is changeable and the spatter is serious. The electromagnetic force accelerates the radial liquid beam rotation under direct current(DC) magnetic field, and increases the angle between liquid beam and welding wire axis. Meanwhile, the rotation frequency of the liquid beam reaches 400 Hz, the area of arc column and heat loss increase under DC magnetic field. Based on the alternating magnetic field, the arc is the “bell shaped”, the arc stiffness raises, its temperature achieves 26 000 K, and the maximum speed of the liquid stream beam can reach 500 m/s. And the droplet transfer is more stable, the spatter significantly reduces, and welding quality is effectively improved. 展开更多
关键词 high efficiency welding numerical simulation droplet transfer external magnetic field
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The effect of activating fluxes on the cathode spots in the activating TIG welding 被引量:2
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作者 黄勇 王伯洋 +4 位作者 郭建航 刘永刚 黄健康 樊丁 余淑荣 《China Welding》 CAS 2023年第1期7-17,共11页
The cathode spots are a common phenomenon in the TIG(tungsten inert gas)welding process.However,it is rarely observed in the activating TIG welding process.This research is mainly focused on the effect of activating f... The cathode spots are a common phenomenon in the TIG(tungsten inert gas)welding process.However,it is rarely observed in the activating TIG welding process.This research is mainly focused on the effect of activating flux on cathode spots in the activating TIG welding.The characteristics and behaviors of cathode spots were investigated in activating TIG welding by the high-speed camera and the spectrograph.Three kinds of oxide(TiO_(2),SiO_(2),MnO_(2))and two halide(MnCl_(2),CaF_(2))activating fluxes are used in the activating TIG welding process.The results show that differ from the TIG welding,the oxide activating flux increases the number of cathode spots and decreases the velocity.The effect is the opposite for the halide activating flux.Moreover,the number of spots no longer varies with the current except TiO2 activating flux.As the temperature of the weld pool surface increases the spot moves away from the center.But this rule is not valid when silica and manganese compounds activating fluxes are used.The variation of cathode spots is caused by the oxide film reformed and the distribution of weld slag.The formation mechanism of cathode spots might be the impact of ions on the cathode surface and the strong electric field formed near the cathode surface. 展开更多
关键词 cathode spots behaviors activating tungsten inert gas welding high-speed photography spectrum
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Metal vapor behavior in double electrodes TIG welding 被引量:1
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作者 Wang Xinxin Luo Yi fan ding 《China Welding》 EI CAS 2018年第3期27-34,共8页
In present paper, the metal vapour behavior in double electrodes TIG welding was investigated by a numerical model, including the arc plasma and weld pool. The thermodynamic parameters and transport coefficients of th... In present paper, the metal vapour behavior in double electrodes TIG welding was investigated by a numerical model, including the arc plasma and weld pool. The thermodynamic parameters and transport coefficients of the arc plasma were dependent on both the local temperature and the mass ratio of the metal vapour. A second viscosity approximation was used to formulate the diffusion coefficient of the metal vapour in the arc plasma. The temperature and flow fields together with the metal vapour concentration were simulated, and the influences of metal vapour on the arc plasma and the weld pool were analyzed. It was found that the metal vapour transport in the arc plasma was significantly influenced by the flow of the arc plasma, and the distribution of the metal vapour was more extended in the direction perpendicular to the line through the double electrodes tips. Both the arc plasma and the heat flux at the weld pool were constricted by the presence of the metal vapour, while the metal vapour had a minor effect on the total heat input to the work piece and the weld pool profile as a whole. 展开更多
关键词 metal vapour double electrodes tungsten inert gas welding heat input
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Clinical application and research progress of extracellular slow wave recording in the gastrointestinal tract 被引量:1
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作者 fan ding Run Guo +2 位作者 Zheng-Yu Cui Hai Hu Gang Zhao 《World Journal of Gastrointestinal Surgery》 SCIE 2022年第6期544-555,共12页
The physiological function of the gastrointestinal(GI)tract is based on the slow wave generated and transmitted by the interstitial cells of Cajal.Extracellular myoelectric recording techniques are often used to recor... The physiological function of the gastrointestinal(GI)tract is based on the slow wave generated and transmitted by the interstitial cells of Cajal.Extracellular myoelectric recording techniques are often used to record the characteristics and propagation of slow wave and analyze the models of slow wave transmission under physiological and pathological conditions to further explore the mechanism of GI dysfunction.This article reviews the application and research progress of electromyography,bioelectromagnetic technology,and high-resolution mapping in animal and clinical experiments,summarizes the clinical application of GI electrical stimulation therapy,and reviews the electrophysiological research in the biliary system. 展开更多
关键词 Gastrointestinal tract Slow wave ELECTROMYOGRAPHY High-resolution mapping Bioelectromagnetic technology
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Real-Time Detection and Instance Segmentation of Strawberry in Unstructured Environment 被引量:1
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作者 Chengjun Wang fan ding +4 位作者 Yiwen Wang Renyuan Wu Xingyu Yao Chengjie Jiang Liuyi Ling 《Computers, Materials & Continua》 SCIE EI 2024年第1期1481-1501,共21页
The real-time detection and instance segmentation of strawberries constitute fundamental components in the development of strawberry harvesting robots.Real-time identification of strawberries in an unstructured envi-r... The real-time detection and instance segmentation of strawberries constitute fundamental components in the development of strawberry harvesting robots.Real-time identification of strawberries in an unstructured envi-ronment is a challenging task.Current instance segmentation algorithms for strawberries suffer from issues such as poor real-time performance and low accuracy.To this end,the present study proposes an Efficient YOLACT(E-YOLACT)algorithm for strawberry detection and segmentation based on the YOLACT framework.The key enhancements of the E-YOLACT encompass the development of a lightweight attention mechanism,pyramid squeeze shuffle attention(PSSA),for efficient feature extraction.Additionally,an attention-guided context-feature pyramid network(AC-FPN)is employed instead of FPN to optimize the architecture’s performance.Furthermore,a feature-enhanced model(FEM)is introduced to enhance the prediction head’s capabilities,while efficient fast non-maximum suppression(EF-NMS)is devised to improve non-maximum suppression.The experimental results demonstrate that the E-YOLACT achieves a Box-mAP and Mask-mAP of 77.9 and 76.6,respectively,on the custom dataset.Moreover,it exhibits an impressive category accuracy of 93.5%.Notably,the E-YOLACT also demonstrates a remarkable real-time detection capability with a speed of 34.8 FPS.The method proposed in this article presents an efficient approach for the vision system of a strawberry-picking robot. 展开更多
关键词 YOLACT real-time detection instance segmentation attention mechanism STRAWBERRY
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Agronomic performances of biodegradable and non-biodegradable plastic film mulching on a maize cropping system in the semi-arid Loess Plateau,China
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作者 Hao ZHANG Mengqiong CHEN +3 位作者 Ruiquan QIAO fan ding Hao FENG Rui JIANG 《Pedosphere》 SCIE CAS CSCD 2024年第1期88-96,共9页
Biodegradable plastic film mulch (PFM) is considered an alternative to non-biodegradable PFM to mitigate the negative impacts of residual film.However,the agronomic performance of biodegradable PFM in comparison to no... Biodegradable plastic film mulch (PFM) is considered an alternative to non-biodegradable PFM to mitigate the negative impacts of residual film.However,the agronomic performance of biodegradable PFM in comparison to non-biodegradable PFM still needs to be tested.In this study,we evaluated the effects of biodegradable and non-biodegradable PFM on soil physicochemical properties,microbial community,and enzyme activities,as well as maize growth performance.Biodegradable and non-biodegradable PFM both increased soil temperature,water content,N content,and microbial biomass and maize yield by up to 30%,but decreased soil enzyme activities as compared to no mulching (control,CK).Most soil physicochemical properties,microbial community,and enzyme activities were similar under non-biodegradable and biodegradable PFM at the early stages of maize growth.However,at the late stages,soil temperature,water content,mineral N,NO_(3)^(-)-N,ammonia monooxygenase (AMO) activity,and total phospholipid fatty acids (PLFAs) decreased under biodegradable PFM owing to film fragmentation.White PFM increased soil temperature,water content,and total PLFAs at the early stages of maize growth but decreased soil mineral N and total PLFAs at the late stages,as compared to black PFM.As soil temperature and N availability were the major factors affecting soil microbial community,microbial activity decreased after the fragmentation of biodegradable PFM,owing to the decreased soil temperature,water content,and mineral N.Notably,biodegradable PFM could decrease NO_(3)^(-)-N accumulation in topsoil by decreasing N transformation due to the lower microbial and N-related enzyme (e.g.,AMO) activities,compared with non-biodegradable PFM,which may avoid negative environmental impacts,such as NO_(3)^(-)-N leaching or gas emission after harvest.Maize yield,height,aboveground biomass,and N uptake under biodegradable PFM were similar to those under non-biodegradable PFM during maize growth,implying that biodegradable PFM has no negative impact on crop growth and yield.In general,biodegradable PFM was equivalent to non-biodegradable PFM in terms of maize yield increase and N uptake,but was environmentally friendly.Therefore,biodegradable PFM can be used as an alternative to non-biodegradable PFM in semi-arid areas for sustainable agricultural practices. 展开更多
关键词 black plastic film mulching enzyme activity film fragmentation microbial community phospholipid fatty acid white plastic film mulching
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PM_(2.5)-Metabolic Syndrome Causal Association:A Mendelian Randomization Study
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作者 fan ding Ning Ma +5 位作者 Shi Zhao Qingan Wang Zhanbing Ma Yuhong Zhang Yi Zhao Yu Zhao 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2024年第12期1421-1426,共6页
Metabolic syndrome(MS)is a common metabolic disorder status and defined as a pathology characterized by abdominal obesity,insulin resistance,hypertension,and hyperlipidemia(atherosclerosis)status[1].Evidence suggests ... Metabolic syndrome(MS)is a common metabolic disorder status and defined as a pathology characterized by abdominal obesity,insulin resistance,hypertension,and hyperlipidemia(atherosclerosis)status[1].Evidence suggests that the underlying etiology of MS is multifactorial and includes environmental factors,tobacco use,high alcohol consumption,dietary risks,and low physical activity.Thus,a deeper understanding of MS and its risk factors will be beneficial for mitigating health damage and improving the quality of life in high-risk subpopulations.PM_(2.5)is an important environmental pollutant,poses a serious threat to human health,and is associated with various health problems.Several epidemiological studies have shown that exposure to PM_(2.5)may influence the development of diabetes[2],cardiovascular disease,obesity,and MS.Existing evidence also suggests that the components of MS are sensitive to environmental pollutants,especially PM_(2.5).However,most of them were observational studies or literature analyses based on epidemiology。 展开更多
关键词 METABOLIC EPIDEMIOLOGY OBESITY
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水鬼蕉碱Pancratistatin的合成方法研究进展
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作者 梁蕾蕾 姚家灿 +2 位作者 丁凡 徐畅 刘丹丹 《有机化学》 SCIE CAS CSCD 北大核心 2024年第6期1793-1810,共18页
水鬼蕉碱(Pancratistatin)是具有显著抗肿瘤活性的天然生物碱, 包含高度羟基化六元环的异喹诺酮骨架, 有6个连续的手性中心. 芳环上取代基的区域选择性引入、内酰胺环的高效构建以及六取代环己烷的立体控制性合成是其全合成的主要挑战.... 水鬼蕉碱(Pancratistatin)是具有显著抗肿瘤活性的天然生物碱, 包含高度羟基化六元环的异喹诺酮骨架, 有6个连续的手性中心. 芳环上取代基的区域选择性引入、内酰胺环的高效构建以及六取代环己烷的立体控制性合成是其全合成的主要挑战. 综述了水鬼蕉碱的初次合成工作, 以及2000年以来的全合成研究进展, 对合成策略和反应关键步骤进行阐述. 展开更多
关键词 水鬼蕉碱 消旋合成 不对称合成
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基于边权的最小权重3路顶点覆盖算法
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作者 范鼎 刘春颜 +1 位作者 李洋 赵蕴龙 《应用科技》 CAS 2024年第4期69-74,共6页
城际仓储选址通常可以转化为顶点覆盖问题,顶点覆盖问题是一种经典的NP难问题。针对最小权重3路顶点覆盖问题,设计了基于边权和顶点度的贪心策略,构建了1个两阶段的最小权重3路顶点覆盖算法。通过与2种较优的最小权重3路顶点覆盖算法进... 城际仓储选址通常可以转化为顶点覆盖问题,顶点覆盖问题是一种经典的NP难问题。针对最小权重3路顶点覆盖问题,设计了基于边权和顶点度的贪心策略,构建了1个两阶段的最小权重3路顶点覆盖算法。通过与2种较优的最小权重3路顶点覆盖算法进行对比实验分析可知,本文提出的算法在城际物流仓储选址问题中具有较好的效果,最小权重和分别减少了3.34和1.13个百分点。 展开更多
关键词 顶点覆盖 3路顶点覆盖 最小权重3路顶点覆盖 组合优化 图论 边权策略 物流建仓 贪心策略
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基于改进卷积神经网络的管焊缝X射线图像缺陷识别方法 被引量:44
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作者 樊丁 胡桉得 +2 位作者 黄健康 徐振亚 徐旭 《焊接学报》 EI CAS CSCD 北大核心 2020年第1期7-11,I0001,共6页
针对卷积神经网络(CNN)应用于焊缝探伤图像识别时,目标区域占比小,局部信息冗余,激活函数小于零时出现硬饱和区导致模型对输入变化较敏感、网络参数难以训练的问题,采用超像素分割算法(SLIC)和改进的ELU激活函数构建CNN模型进行焊缝探... 针对卷积神经网络(CNN)应用于焊缝探伤图像识别时,目标区域占比小,局部信息冗余,激活函数小于零时出现硬饱和区导致模型对输入变化较敏感、网络参数难以训练的问题,采用超像素分割算法(SLIC)和改进的ELU激活函数构建CNN模型进行焊缝探伤图像缺陷识别.首先,在CNN模型中使用ELU激活函数,在缓解梯度消失时对输入噪声产生更好的鲁棒性,同时,利用SLIC算法对图像像素进行像素块处理的特点,增大焊缝探伤图像中感兴趣区域的占比,降低局部冗余信息,提高模型在训练过程中的特征提取能力.通过对焊缝探伤图像感兴趣区域提取并与所述CNN模型进行对比试验.结果表明,该方法在焊缝探伤图像特征提取、训练耗时及识别准确率方面较传统卷积神经网络有更好的表现. 展开更多
关键词 焊缝缺陷识别 卷积神经网络 SLIC算法 ELU函数
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异厚度铝钢电弧辅助激光对接熔钎焊温度场和应力应变场数值模拟 被引量:9
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作者 刘剑 樊丁 +2 位作者 陈秀娟 黄健康 余淑荣 《焊接学报》 EI CAS CSCD 北大核心 2018年第2期33-38,130,共7页
以厚度2 mm的5A06铝合金板和1 mm热镀锌ST04Z钢对接熔钎焊试验为研究对象.采用ANSYS有限元软件,选用高斯函数分布的热源模型模拟TIG电弧和三维锥体热源模型模拟激光的不重合组合热源.基于所建立的不重合组合热源模型对温度场和应力场进... 以厚度2 mm的5A06铝合金板和1 mm热镀锌ST04Z钢对接熔钎焊试验为研究对象.采用ANSYS有限元软件,选用高斯函数分布的热源模型模拟TIG电弧和三维锥体热源模型模拟激光的不重合组合热源.基于所建立的不重合组合热源模型对温度场和应力场进行耦合分析,得到焊接过程中的温度场和应力应变分布.结果表明,铝钢异厚度熔钎焊在焊缝及其附近区域中的纵向应力是拉应力,钢一侧远离焊缝产生较大的压应力,变形较大;铝合金一侧远离焊缝产生相应的变形,压应力相对较小,温度场、残余应力模拟结果与试验结果吻合较好,证明所建组合热源模型正确. 展开更多
关键词 铝钢 电弧辅助激光 熔钎焊 数值模拟
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高频交变磁场对大电流GMAW熔滴过渡和飞溅率的影响 被引量:12
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作者 樊丁 杨文艳 +1 位作者 肖磊 黄健康 《焊接学报》 EI CAS CSCD 北大核心 2019年第7期1-5,I0002,共6页
在熔化极气体保护焊过程中,采用大送丝速度,增大焊接电流和焊丝伸出长度是提高焊接熔敷率的直接途径.但当熔滴过渡转变为旋转射流过渡时,电弧不稳,飞溅增大,焊缝成形变差.施加不同频率的纵向交变磁场,对焊缝成形进行控制.采用高速摄像技... 在熔化极气体保护焊过程中,采用大送丝速度,增大焊接电流和焊丝伸出长度是提高焊接熔敷率的直接途径.但当熔滴过渡转变为旋转射流过渡时,电弧不稳,飞溅增大,焊缝成形变差.施加不同频率的纵向交变磁场,对焊缝成形进行控制.采用高速摄像技术,拍摄焊接过程中的电弧形态和熔滴过渡,研究不同频率的磁场对熔滴过渡和焊接飞溅率的影响规律.结果表明,熔滴过渡形式不同,产生飞溅的机理不同;外加频率为1000Hz纵向交变磁场时,电弧的旋转半径减小,电弧的挺度增大,旋转射流过渡时电弧更稳定,焊接飞溅率降低,焊缝成形改善. 展开更多
关键词 旋转射流过渡 高频磁场 高速摄像 飞溅率 蒸发速率
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一种自冷却结构燃油泵滑动轴承润滑特性分析 被引量:9
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作者 符江锋 李华聪 +3 位作者 樊丁 刘显为 朱嘉兴 李昆 《北京航空航天大学学报》 EI CAS CSCD 北大核心 2018年第10期2052-2062,共11页
为研究低介质黏度和自冷却结构限制下的航空燃油泵滑动轴承润滑特性分布规律,基于油膜动压润滑流动的Reynolds方程和等效黏度润滑流动模型,以绝热流动为假设简化滑动轴承内部流动的能量积分方程,构建一种联合Reynolds方程和绝热流动能... 为研究低介质黏度和自冷却结构限制下的航空燃油泵滑动轴承润滑特性分布规律,基于油膜动压润滑流动的Reynolds方程和等效黏度润滑流动模型,以绝热流动为假设简化滑动轴承内部流动的能量积分方程,构建一种联合Reynolds方程和绝热流动能量积分方程的燃油泵滑动轴承热流动润滑流动模型。采用CFD数值模拟和有限差分法相结合的混合仿真方法,分别对不同的间隙比、偏心率、宽径比条件下的滑动轴承的油膜压力、油膜厚度、油膜温度、端泄漏量、摩擦阻力等润滑特性进行了仿真分析。仿真结果表明:采用CFD计算滑动轴承径向载荷精度优于4.0%;保持偏心率不变,油膜承载力随着间隙比的增加而单调下降,油膜厚度随着间隙比的增高而增加;保持间隙比不变,油膜的承载力随着偏心率的增大也逐渐增大,油膜厚度随着偏心率的增高而下降,而油膜温度与油膜厚度成反比,且随着偏心率的升高,油膜温度的峰值越来越明显;当偏心率、间隙比一定时,可通过增加宽径比提高滑动轴承的油膜承载力。因此在滑动轴承的设计中,需综合考虑油膜承载力、端泄漏量、油膜厚度和温升间的相互制约因素,合理地优化间隙比、宽径比和偏心率以提高滑动轴承润滑性能。 展开更多
关键词 燃油齿轮泵 滑动轴承 润滑模型 润滑特性 自冷却结构
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高效MAG焊接熔滴过渡行为及交变磁场控制试验分析 被引量:9
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作者 樊丁 郑发磊 +1 位作者 肖磊 陈克选 《焊接学报》 EI CAS CSCD 北大核心 2019年第5期1-5,I0002,共6页
探索更加高效的焊接方法和工艺是当前国际焊接界一个热点课题,而增大焊接电流和焊丝伸出长度可直接提高MAG焊焊接效率.文中对商用MAG焊机进行改造,使送丝速度达到50 m/min,焊接电流提升至500 A以上,以进一步提高焊接效率.但是熔滴旋转... 探索更加高效的焊接方法和工艺是当前国际焊接界一个热点课题,而增大焊接电流和焊丝伸出长度可直接提高MAG焊焊接效率.文中对商用MAG焊机进行改造,使送丝速度达到50 m/min,焊接电流提升至500 A以上,以进一步提高焊接效率.但是熔滴旋转射流过渡的形成,导致电弧不稳,飞溅增大,因而采用外加交变磁场来改善电弧形态和熔滴过渡行为.通过焊接工艺试验,分析了焊接电流对焊接飞溅率和金属蒸发速率的影响规律,研究了交变磁场对熔滴过渡行为和焊缝成形的作用.结果表明,外加低频交变磁场可以有效提高大电流下电弧挺度和稳定性,缩短液流束长度,减小液尖偏斜程度,进而改善焊缝成形,大幅度提高焊接效率. 展开更多
关键词 熔滴过渡行为 旋转射流过渡 金属蒸发速率 交变磁场
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