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Impact of spring pressure on ignition and combustion of electrically controlled solid propellant 认领 引用
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作者 Zejun HU Jianjun WU +4 位作者 Zhicheng HE Yu ZHANG Peng ZHENG Yuanzheng ZHAO Zhengxue MA 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第2期202-214,共13页
The electrode structures in ignition devices for Electrically Controlled Solid Propellants(ECSP)can be classified into fixed and movable types.In movable electrode structures,springs are typically used to push the ele... The electrode structures in ignition devices for Electrically Controlled Solid Propellants(ECSP)can be classified into fixed and movable types.In movable electrode structures,springs are typically used to push the electrodes and the propellant.The effects of spring pressure on the ignition and combustion of propellants have not yet been studied.In this paper,a universal testing machine and an electrochemical workstation were firstly utilized to investigate the compressive mechanical property and conductivity of Hydroxylamine Nitrate(HAN)-ECSP.The maximum pressure at which the propellant undergoes elastic deformation is 65 kPa.When the spring pressure increased from 5.1 k Pa to 20.4 kPa,the propellant resistance decreased from 56.8Ωto 36.8Ω.Various observation methods were employed to study the process of electrical energy injection and the ignition and combustion characteristics under constant voltage.Appropriately increasing the spring pressure can accelerate the injection of electrical energy into the propellant,increase the electrification current,and thus reduce the initial ignition delay time of the propellant.When the spring pressure is 20.4 kPa,the squeezing speed of the propellant is too fast,making it difficult for the propellant to be adequately heated at the electrode interface,which is unfavorable for ignition.Excessive spring pressure also leads to the accumulation of a large amount of combustion residue on the electrode plate,hindering the mixing and diffusion of hot gases during the second ignition process,preventing the gaseous flame of the propellant.When the spring pressure is 5.1 kPa,improving the working voltage can enhance the repeated ignition characteristics of the propellant. 展开更多
关键词 Electrically controlled solid propellant Hydroxylamine nitrate Ignition and combustion Movable electrode structure Spring pressure
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A Discussion on the Complexity and Transit Mechanisms of Urban Traffic Systems 认领 引用 被引量：4
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作者 Ziyou Gao Bin Jia +2 位作者 Dongfan Xie Wenxu Wang Jianjun Wu 《Engineering》 SCIE EI CSCD 2025年第1期24-29,共6页
Urban traffic is a complex system composed of users,drivers,vehicles,roads,the environment,and information and management strategies,characterized by dynamics,randomness,openness,and complexity.Traditional traffic sci... Urban traffic is a complex system composed of users,drivers,vehicles,roads,the environment,and information and management strategies,characterized by dynamics,randomness,openness,and complexity.Traditional traffic science and engineering research usually focuses on specific traffic subsystems[1,2],such as drivers(i.e.,driving behavior),vehicles(i.e.,traffic flow),or traffic control(i.e.,signal systems),and significant progress has been achieved in these areas. 展开更多
关键词 Urban transportation system mechanism study
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AI-powered transportation can make traffic better? 认领 引用
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作者 Changxi Ma Jianjun Wu +1 位作者 Ciro Caliendo Xuecai Xu 《Digital Transportation and Safety》 2025年第3期175-176,共2页
Artificial intelligence(AI)technologies have brought tremendous progress in various fields,and AI-powered transportation has been given more attention in recent years.From this perspective,the advantages and challenge... Artificial intelligence(AI)technologies have brought tremendous progress in various fields,and AI-powered transportation has been given more attention in recent years.From this perspective,the advantages and challenges confronted by road transport systems,railway and subway systems,the aviation industry,and Europe,especially in Italy have been discussed,and the conclusion reached that AI-powered transportation can improve traffic and make life better in transportation. 展开更多
关键词 AI-powered transportation Intelligent transportation systems Connected and autonomous vehicles
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Multifunctional Asymmetric Bilayer Aerogels for Highly Efficient Electromagnetic Interference Shielding with Ultrahigh Electromagnetic Wave Absorption 认领 引用 被引量：6
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作者 Cheng‑Zhang Qi Peng Min +6 位作者 Xinfeng Zhou Meng Jin Xia Sun Jianjun Wu Yanjun Liu Hao‑Bin Zhang Zhong‑Zhen Yu 《Nano-Micro Letters》 SCIE EI CAS CSCD 2025年第11期680-697,共18页
Although multifunctional electromagnetic interference(EMI)shielding materials with ultrahigh electromagnetic wave absorption are highly required to solve increasingly serious electromagnetic radiation and pollution an... Although multifunctional electromagnetic interference(EMI)shielding materials with ultrahigh electromagnetic wave absorption are highly required to solve increasingly serious electromagnetic radiation and pollution and meet multi-scenario applications,EMI shielding materials usually cause a lot of reflection and have a single function.To realize the broadband absorption-dominated EMI shielding via absorption-reflection-reabsorption mechanisms and the interference cancelation effect,multifunctional asymmetric bilayer aerogels are designed by sequential printing of a MXene-graphene oxide(MG)layer with a MG emulsion ink and a conductive MXene layer with a MXene ink and subsequent freeze-drying for generating and solidifying numerous pores in the aerogels.The top MG layer of the asymmetric bilayer aerogel optimizes impedance matching and achieves re-absorption,while the bottom MXene layer enhances the reflection of the incident electromagnetic waves.As a result,the asymmetric bilayer aerogel achieves an average absorption coefficient of 0.95 in the X-band and shows the tunable absorption ability to electromagnetic wave in the ultrawide band from 8.2 to 40 GHz.Finite element simulations substantiate the effectiveness of the asymmetric bilayer aerogel for electromagnetic wave absorption.The multifunctional bilayer aerogels exhibit hydrophobicity,thermal insulation and Joule heating capacities and are efficient in solar-thermal/electric heating,infrared stealth,and clean-up of spilled oil. 展开更多
关键词 Multifunctional bilayer aerogels Electromagnetic interference shielding MXene sheets Graphene oxide Infrared stealth and camouflage
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Integrated optimization of train stopping plans and timetabling for urban rail transit based on dynamic demand 认领 引用
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作者 Jiayao Han Qiuchi Xue +2 位作者 Ye Yuan Xin Yang Jianjun Wu 《Digital Transportation and Safety》 2025年第1期42-49,共8页
This study addresses the higher demand of passengers during peak hours in urban rail transit by proposing an integrated optimization of train stopping plans and timetabling to reduce overcrowding and the total waiting... This study addresses the higher demand of passengers during peak hours in urban rail transit by proposing an integrated optimization of train stopping plans and timetabling to reduce overcrowding and the total waiting time.A nonlinear integer programming model is developed,incorporating passenger demand,operation costs,train capacity,and station congestion levels.The decision variables include the stopping plan and departure headways.The objective is to minimize total operation time,average operation time,and waiting time,while reducing congestion variance across stations.A case study using the NSGA-II algorithm shows that the optimized solution significantly alleviates station congestion compared to the all-stop plan.Additionally,it reduces average operation time,total operation time,and waiting time by 3.42%,9.40%,and 10.44%,respectively,demonstrating the model's feasibility and effectiveness. 展开更多
关键词 Timetable Train stopping plan Multi-objective optimization Nonlinear integer programming model Urban rail transit
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Ten years of gas shale fracturing in China:Review and prospect 认领 引用 被引量：19
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作者 Jinzhou Zhao Lan Ren +19 位作者 Tingxue Jiang Dongfeng Hu Leize Wu Jianfa Wu Congbin Yin Yongming Li Yongquan Hu Ran Lin Xiaogang Li Yu Peng Cheng Shen Xiyu Chen Qing Yin Changgui Jia Yi Song Haitao Wang Zhaoyuan Li Jianjun Wu Bin Zeng Linlin Du 《Natural Gas Industry B》 2022年第2期158-175,共18页
The first fractured shale gas well of China was constructed in 2010.After 10 years of development,China has become the second country that possesses the core technology of shale gas development around the world,realiz... The first fractured shale gas well of China was constructed in 2010.After 10 years of development,China has become the second country that possesses the core technology of shale gas development around the world,realized the shale gas fracturing techniques from zero to one and from lagging to partially leading,and constructed the fracturing theory and technology system suitable for middle-shallow marine shale gas exploitation.In order to provide beneficial guidance for the efficient exploitation of shale gas in China in the future,this paper comprehensively reviews development history and status of domestic fundamental theories,optimized design methods,fluid systems,tools and technologies of shale gas fracturing and summarizes the research results in fundamental theories and optimized design methods,such as fracturing sweet-spot cognition,fracture network propagation simulation and control,rock hydration and flowback control,and SRV(stimulated reservoir volume)evaluation and characterization.The development and application of slick-water fracturing fluid system and new fracturing fluid with little or no water is discussed.The development and independent research&development level of multi-stage fracturing tools are evaluated,including drillable composite plug,soluble plug,large-diameter plug and casing cementing sleeve.The implementation situations of field technologies and processes are illustrated,including the early conventional multi-stage multi-cluster fracturing and the current“dense cluster”fracturing and temporary plugging fracturing.Based on this,the current challenges to domestic shale gas fracturing technologies are analyzed systematically,and the development direction of related technologies is forecast.In conclusion,it is necessary for China to continuously research the fracturing theories,technologies and methods suitable for domestic deep and ultra-deep marine shale gas,terrestrial shale gas and transitional shale gas to facilitate the future efficient development of shale gas in China. 展开更多
关键词 China Shale gas Network fracturing Fundamental theory Fracturing technology Fluid and tools Deep/ultra-deep marine shale gas Terrestrial/marine-terrestrial transitional shale gas
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Bionic Coupling of Hardness Gradient to Surface Texture for Improved Anti-wear Properties 认领 引用 被引量：13
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作者 Long Zheng Jianjun Wu +5 位作者 Si Zhang Shishuai Sun Zhihui Zhang Song Liang Zhenning Liu Luquan Ren 《Journal of Bionic Engineering》 SCIE EI CSCD 2016年第3期406-415,共10页
This work investigates the potential of combining hardness gradient with surface texture （an example of bionic coupling） to improve anti-wear properties. The bionic coupling of hardness gradient and Hexagonal Textu... This work investigates the potential of combining hardness gradient with surface texture （an example of bionic coupling） to improve anti-wear properties. The bionic coupling of hardness gradient and Hexagonal Texture （HT） was achieved by laser heat treatment on steel specimens with pre-engraved hexagonal surface texture. The successful establishment of decreasing hardness from surface to internal bulk was verified by hardness measurements along the depth of cross-sectioned specimens and corre- lated with the observations from metallurgical microscopy. The tribological performance of bionic coupling specimens （HT-L） was examined under dry contact condition, together with respective control specimens of individual bionic features, e.g. HT-H （of similar surface hardness generated by conventional heat treatment but without hardness gradient） and SS-L （of smooth surface treated by the same laser processing as for HT-L）. It is found that HT-L not only exhibits lower friction coefficient and less friction fluctuation than HT-H and SS-L, but also demonstrates a 〉50% reduction of wear loss compared to HT-H and SS-L （0.0343 g for HT-L vs. 0.0723 g for HT-H, P〈0.001; 0.0343 g for HT-L vs. 0.0817 g for SS-L, P〈0.001）. Corroboratively, observations with scanning electron microscopy revealed a relatively smooth surface for worn HT-L specimen, contrasting with the rugged and grooved surfaces of worn HT-H and SS-L specimens. These results indicate that the bionic coupling of hardness gradient to hexagonal texture can indeed improve anti-wear properties, affording a new strategy to wear and friction manage- ment. 展开更多
关键词 anti-wear bionic coupling hardness gradient surface texture hexagonal texture
An atmosphere-breathing propulsion system using inductively coupled plasma source 认领 引用 被引量：11
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作者 Peng ZHENG Jianjun WU +2 位作者 Yu ZHANG Bixuan CHE Yuanzheng ZHAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2023年第5期223-238,共16页
CubeSats have attracted more research interest recently due to their lower cost and shorter production time.A promising technology for CubeSat application is atmosphere-breathing electric propulsion,which can capture ... CubeSats have attracted more research interest recently due to their lower cost and shorter production time.A promising technology for CubeSat application is atmosphere-breathing electric propulsion,which can capture the atmospheric particles as propulsion propellant to maintain longterm mission at very low Earth orbit.This paper designs an atmosphere-breathing electric propulsion system for a 3 U CubeSat,which consists of an intake device and an electric thruster based on the inductively coupled plasma.The capture performance of intake device is optimized considering both particles capture efficiency and compression ratio.The plasma source is also analyzed by experiment and simulation.Then,the thrust performance is also estimated when taking into account the intake performance.The results show that it is feasible to use atmosphere-breathing electric propulsion technology for CubeSats to compensate for aerodynamic drag at lower Earth orbit. 展开更多
关键词 Atmosphere-Breathing Electric Propulsion(ABEP) CubeSat Inductively coupled plasma Intake device Very Low Earth Orbit(VLEO)
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Understanding the Resilience of Urban Rail Transit:Concepts,Reviews,and Trends 认领 引用 被引量：7
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作者 Yun Wei Xin Yang +6 位作者 Xiao Xiao Zhiao Ma Tianlei Zhu Fei Dou Jianjun Wu Anthony Chen Ziyou Gao 《Engineering》 SCIE EI CAS CSCD 2024年第10期7-18,共12页
As the scale of urban rail transit(URT)networks expands,the study of URT resilience is essential for safe and efficient operations.This paper presents a comprehensive review of URT resilience and highlights potential ... As the scale of urban rail transit(URT)networks expands,the study of URT resilience is essential for safe and efficient operations.This paper presents a comprehensive review of URT resilience and highlights potential trends and directions for future research.First,URT resilience is defined by three primary abilities:absorption,resistance,and recovery,and four properties:robustness,vulnerability,rapidity,and redundancy.Then,the metrics and assessment approaches for URT resilience were summarized.The metrics are divided into three categories:topology-based,characteristic-based,and performance-based,and the assessment methods are divided into four categories:topological,simulation,optimization,and datadriven.Comparisons of various metrics and assessment approaches revealed that the current research trend in URT resilience is increasingly favoring the integration of traditional methods,such as conventional complex network analysis and operations optimization theory,with new techniques like big data and intelligent computing technology,to accurately assess URT resilience.Finally,five potential trends and directions for future research were identified:analyzing resilience based on multisource data,optimizing train diagram in multiple scenarios,accurate response to passenger demand through new technologies,coupling and optimizing passenger and traffic flows,and optimal line design. 展开更多
关键词 Urban rail transit Resilience assessment Resilience improvement Network disruption
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Experimental study on the effects of drying methods on the stabilities of lignite 认领 引用 被引量：4
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作者 Yixin Zhang Jixiang Dong +3 位作者 Fanhui Guo Xiaokai Chen Jianjun Wu Zhenyong Miao 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第7期1545-1554,共10页
The drying processes are always applied prior to the transportation or utilization of lignite, and result in notable changes in the stabilities of lignite. In this paper, the study on the effects of nitrogen and MTE d... The drying processes are always applied prior to the transportation or utilization of lignite, and result in notable changes in the stabilities of lignite. In this paper, the study on the effects of nitrogen and MTE drying process on the physico-chemical properties and stabilities of Zhaotung lignite was carried out. The briquettes produced by MTE drying in this study were 150 mm in dimension, and so had a much larger particle size than nitrogen- dried samples. Nitrogen adsorption, mercury intrusion porosimetry and scanning electron microscopy all suggested that drying was accompanied by the transformation of larger pores into smaller ones. Compared to nitrogen drying, the pore structures could be stabilized by the MTE process. The soluble salts were removed during MTE drying which resulted in the decrease in ash and the concentrations of some of the major metals. The removal of water enhanced the hydrophilicity of nitrogen dried samples, but did not affect the hydrophilicity of MTE dried samples. The moisture holding capacity of MTE dried samples reduced faster than nitrogen dried samples with the decrease of residual moisture content. The moisture readsorption processes of MTE dried sam- ples were strongly inhibited due to the much larger particle size of sample produced by MTE drying than nitrogen drying. The susceptibility to spontaneous combustion, indicated by cross point temperature and self-heating tests, of nitrogen and MTE dried samples increased with the decrease of residual moisture content. The MTE dried samples are more liable to spontaneous combustion than nitrogen dried samples with the same residual moisture and particle size. However, the larger particle size of the MTE product made it more stable with respect to spontaneous combustion and also moisture readsorption. 展开更多
关键词 Lignite Mechanical thermal expression Stability Hydrophilidty Readsorption Spontaneous combustion
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Measurement method and results of divergence angle of laser-controlled solid propellants used in space propulsion 认领 引用 被引量：4
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作者 Yang OU Jianjun WU +2 位作者 Yuqiang CHENG Yu ZHANG Yuqi LI 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2023年第9期195-206,共12页
The plume divergence angle is an important reference index for evaluating the thrust efficiency and propellant utilization of space propulsion systems.However,the characteristics of the dynamic variation of plume dive... The plume divergence angle is an important reference index for evaluating the thrust efficiency and propellant utilization of space propulsion systems.However,the characteristics of the dynamic variation of plume divergence angle over time cannot be measured using current methods.This paper utilizes high-speed photography and image processing methods to develop a strategy that can give a quick,non-destructive and real-time detection of the divergence angle.Effectiveness of the strategy is verified,and the characteristics of plume divergence angles of different lasercontrolled solid propellants were further analyzed and fitted.The experimental results indicate that graphene could effectively reduce the divergence angle,while oxide-doped samples had larger divergence angles than alloy-doped and carbon-doped samples. 展开更多
关键词 Ablation Image processing Laser Plume divergence angle Propellant Space application
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Nystose attenuates bone loss and promotes BMSCs differentiation to osteoblasts through BMP and Wnt/β-catenin pathway in ovariectomized mice 认领 引用 被引量：3
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作者 Qi Zhang Sijing Hu +7 位作者 Jianjun Wu Peng Sun Quanlong Zhang Yang Wang Qiming Zhao Ting Han Luping Qin Qiaoyan Zhang 《Food Science and Human Wellness》 SCIE CAS CSCD 2023年第2期634-646,共13页
Increasing the osteogenic differentiation ability and decreasing the adipogenic differentiation ability of bone marrow mesenchymal stem cells(BMSCs)is a potential strategy for the treatment of osteoporosis(OP).Natural... Increasing the osteogenic differentiation ability and decreasing the adipogenic differentiation ability of bone marrow mesenchymal stem cells(BMSCs)is a potential strategy for the treatment of osteoporosis(OP).Naturally derived oligosaccharides have shown significant anti-osteoporotic effects.Nystose(NST),an oligosaccharide,was isolated from the roots of Morinda officinalis How.(MO).The aim of the present study was to investigate the effects of NST on bone loss in ovariectomized mice,and explore the underlying mechanism of NST in promoting differentiation of BMSCs to osteoblasts.Administration of NST(40,80 and 160 mg/kg)and the positive control of estradiol valerate(0.2 mg/kg)for 8 weeks significantly prevented bone loss induced by ovariectomy(OVX),increased the bone mass density(BMD),improved the bone microarchitecture and reduced urine calcium and deoxypyridinoline(DPD)in ovariectomized mice,while inhibited the increase of body weight without significantly affecting the uterus weight.Furthermore,we found that NST increased osteogenic differentiation,inhibited adipogenic differentiation of BMSCs in vitro,and upregulated the expression of the key proteins of BMP and Wnt/β-catenin pathways.In addition,Noggin and Dickkopf-related protein-1(DKK-1)reversed the effect of NST on osteogenic differentiation and expression of the key proteins in BMP and Wnt/β-catenin pathway.The luciferase activities and the molecular docking analysis further supported the mechanism of NST.In conclusion,these results indicating that NST can be clinically used as a potential alternative medicine for the prevention and treatment of postmenopausal osteoporosis. 展开更多
关键词 Nystose Bone marrow mesenchymal stem cell Osteoblast Adipocyte BMP pathway Wnt/β-catenin pathway
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Simulation of an aircraft thermal management system based on vapor cycle response surface model 认领 引用 被引量：3
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作者 Haodong LIU Hongsheng JIANG +3 位作者 Sujun DONG Longxian XUE Yongji LIU Jianjun WU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第6期64-77,共14页
The modern aircraft Thermal Management System(TMS)faces significant challenges due to increasing thermal loads and limited heat dissipation pathways.To optimize TMS during the conceptual design stage,the development o... The modern aircraft Thermal Management System(TMS)faces significant challenges due to increasing thermal loads and limited heat dissipation pathways.To optimize TMS during the conceptual design stage,the development of a modeling and simulation tool is crucial.In this study,a TMS simulation model library was created using MATLAB/SIMULINK.To simplify the complexity of the Vapor Cycle System(VCS)model,a Response Surface Model(RSM)was constructed using the Monte Carlo method and validated through simulation experiments.Taking the F-22 fighter TMS as an example,a thermal dynamic simulation model was constructed to analyze the variation of thermal response parameters in key subsystems and elucidate their coupling relationships.Furthermore,the impact of total fuel flow and ram air flow on the TMS was investigated.The findings demonstrate the existence of an optimal total fuel flow that achieves a balance between maximizing fuel heat sink utilization and minimizing bleed air demand.The adaptive distribution of fuel and ram air flow was found to enhance aircraft thermal management performance.This study contributes to improving modeling efficiency and enhancing the understanding of the thermal dynamic characteristics of TMS,thereby facilitating further optimization in aircraft TMS design. 展开更多
关键词 Thermal management sys-tem Vaporcycle Response surface model Dynamic simulation MonteCarlo
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Experimental study on shock interaction control of double wedge in high-enthalpy hypersonic flow subject to plasma synthetic jet 认领 引用 被引量：3
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作者 Xuzhen XIE Qiang LIU +6 位作者 Yan ZHOU Zhenbing LUO Wei XIE Guanghui BAI Kai LUO Qiu WANG Jianjun WU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第4期151-165,共15页
The hypersonic shock-shock interaction flow field at double-wedge geometries controlled by plasma synthetic jet actuator is experimentally studied in a Ma = 8 high-enthalpy shock tunnel with the purpose of exploring a... The hypersonic shock-shock interaction flow field at double-wedge geometries controlled by plasma synthetic jet actuator is experimentally studied in a Ma = 8 high-enthalpy shock tunnel with the purpose of exploring a novel technique for reducing surface heat flux in a real flight environment. The results demonstrate that increasing the discharge energy is advantageous in eliminating the shock wave, shifting the shock wave interaction point, and shortening the control response time. The oblique shock wave can be completely removed when the actuator's discharge energy grows from 0.4 J to 11.5 J, and the displacement of the shock wave interaction point increases by 124.56%, while the controlled response time is shortened by 30 μs. Besides, the reduction in diameter of the jet exit is firstly proved to have a negative impact on energy deposition in a working environment with incoming flow, which reduces the discharge energy and hence decreases the control effect. The shock wave control response time lengthens when the jet exits away from the second wedge. Along with comparing the change in wall heat flux at the second wedge over time, the control effect of plasma synthetic jet actuator with and without inflation is also analyzed. When plasma synthetic jet works in inflatable mode, both the ability to eliminate shock waves and the shifting effect of the shock wave interaction point are increased significantly, and the wall heat flux is also reduced. 展开更多
关键词 Hypersonic flow High-enthalpy flow Plasma synthetic jet Shock wave Flow control
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An improved procedure for manufacture of 3D tubes with springback concerned in flexible bending process 认领 引用 被引量：10
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作者 Jianjun WU Zengkun ZHANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2021年第11期267-276,共10页
Three dimensional(3D)tubes,which possess the characteristics of space saving,lightweight and high strength,are widely used in many high-end industries such as aviation,aerospace,automobile and shipbuilding.However,whe... Three dimensional(3D)tubes,which possess the characteristics of space saving,lightweight and high strength,are widely used in many high-end industries such as aviation,aerospace,automobile and shipbuilding.However,when manufacturing a 3D tube in flexible bending process,springback is a big obstacle for improving the forming quality.In this paper,a new comprehensive strategy for springback control of 3D tubes is proposed.The strategy can be described as follows:(1)define the desired shape and manufacture shape;(2)optimize the manufacture shape using two tooling design methods(e.g.DA(displacement adjustment)method and B&T(bending and twisting)method presented in this paper);(3)make a discretization of the manufacture shape to acquire the optimized forming parameters.Additionally,experiment is implemented to validate the effectiveness of the new strategy.Results show that forming parameters acquired by the new strategy are partially effective.The new strategy also demonstrates that,during 3D tubes forming,the deviation caused by over-bent elements can be counteracted by the deficient-bent elements.This principle is helpful to reduce the difficulty of parameter determination in future. 展开更多
关键词 Bending and twisting 3D tube Finite element modelling Materials forming Springback compensation Tube bending
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Seasonal variations and size distributions of water-soluble ions in atmospheric aerosols in Beijing, 2012 认领 引用 被引量：23
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作者 Yongjie Yang Rui Zhou +4 位作者 Jianjun Wu Yue Yu Zhiqiang Ma Lejian Zhang Yi'an Di 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2015年第8期197-205,共9页
The characteristics of water-soluble ions in airborne particulate matter in Beijing were investigated using ion chromatography. The results showed that the total concentrations of ions were 83.7 ± 48.9 μg/m3 in ... The characteristics of water-soluble ions in airborne particulate matter in Beijing were investigated using ion chromatography. The results showed that the total concentrations of ions were 83.7 ± 48.9 μg/m3 in spring, 54.0 ± 17.0 μg/m3 in summer, 54.1 ± 42.9 μg/m3 in autumn, and 88.8 ± 47.7 μg/m3 in winter, respectively. Furthermore, out of all the ions, NO3-,SO42-and NH4＋accounted for 81.2% in spring, 78.5% in summer, 74.6% in autumn, and 76.3%in winter. Mg2＋and Ca2＋were mainly associated with coarse particles, with a peak that ranged from 5.8 to 9.0 μm. Na＋, NH4＋and Cl-had a multi-mode distribution with peaks that ranged from 0.43 to 1.1 μm and 4.7 to 9.0 μm. K＋, NO3-, and SO42-were mainly associated with fine particles, with a peak that ranged from 0.65 to 2.1 μm. The concentrations of Na＋, K＋,Mg2＋, Ca2＋, NH4＋, Cl-, NO3-and SO42-were 2.69, 2.32, 1.01, 4.84, 16.9, 11.8, 42.0, and 44.1 μg/m3 in particulate matter（PM） on foggy days, respectively, which were 1.4 to 7.3 times higher than those on clear days. The concentrations of these ions were 2.40, 1.66, 0.92, 4.95, 17.5,7.00, 32.6, and 34.7 μg/m3 in PM on hazy days, respectively, which were 1.2–5.7 times higher than those on clear days. 展开更多
关键词 Water-soluble ions Size distribution Hazy day Foggy day Beijing
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Investigation on plasma characteristics in a laser ablation pulsed plasma thruster by optical emission spectroscopy 认领 引用 被引量：2
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作者 Yu ZHANG Jianjun WU +2 位作者 Yang OU Daixian ZHANG Jian LI 《Plasma Science and Technology》 SCIE EI CAS CSCD 2020年第4期83-89,共7页
In order to further improve the propulsion performance of pulsed plasma thrusters for space micro propulsion,a novel laser ablation pulsed plasma thruster is proposed,which separated the laser ablation and electromagn... In order to further improve the propulsion performance of pulsed plasma thrusters for space micro propulsion,a novel laser ablation pulsed plasma thruster is proposed,which separated the laser ablation and electromagnetic acceleration.Optical emission spectroscopy is utilized to investigate the plasma characteristics in the thruster.The spectral lines at different times,positions and discharge intensities are experimentally recorded,and the plasma characteristics in the discharge channel are concluded through analyzing the variation of spectral lines.With the discharge energy of 24 J,laser energy of 0.6 J and the use of aluminum propellant,the specific impulse and thrust efficiency reach 6808 s and 70.6%,respectively. 展开更多
关键词 laser ablation pulsed plasma thruster optical emission spectroscopy plasma propulsion performance
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Investigation on and industrial application of degrading of methanol feed in methanol to propylene process 认领 引用 被引量：2
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作者 Lixiang Jiang Chufu Li +3 位作者 Ming Xu Aihua Xing Rui Feng Jianjun Wu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第10期2102-2111,共10页
At present, methanol to propylene(MTP) technology developed by Lurgi Company is adopted for commercial plants and refined methanol with the purity ≥99.85 wt% is required as the feed of MTP unit in Lurgi's technol... At present, methanol to propylene(MTP) technology developed by Lurgi Company is adopted for commercial plants and refined methanol with the purity ≥99.85 wt% is required as the feed of MTP unit in Lurgi's technology.Therefore, high energy cost for refined methanol production is one of the bottlenecks to improve the economy of MTP technology. Reducing the grade of feed refined methanol may be an effective method to save energy and reduce operation costs in MTP process. In this work, experiments and process simulation were carried out to investigate the influence and feasibility of degrading the methanol feed. Experiments were conducted to investigate the influence of crude methanol feed on conversion and selectivity of MTP reaction as well as the performance of ZSM-5 catalyst. The experimental results showed that degrading the methanol feed had no obvious influence on the conversion and selectivity of MTP reactions and the catalyst deactivation was caused by the carbon accumulation and metals deposition on the active sites. The process simulation results showed that the influence on the conversion and selectivity as well as the stream load of MTP process was negligible if 98 mol% methanol was used as feed. Finally, industrial experiments were conducted by adjusting the operation parameters to degrade of feed methanol of the commercial 500 kt·a-1 MTP unit of Ningmei Group in China. The results of industrial application illustrated that annually 180 kt fuel coal and 150 kt desalted water as well as 1770 MW·h-1 electricity would be saved when the water content increased from 0.01% to 0.4%. This work has identified the feasibility to improve MTP technology by degrading the methanol feed. 展开更多
关键词 MTP Methanol Distillation Simulation and optimization Energy saving
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The ablation characteristics of laser-assisted pulsed plasma thruster with metal propellant 认领 引用 被引量：2
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作者 Yuanzheng Zhao Sheng Tan +3 位作者 Jianjun Wu Yu Zhang Yang Ou Peng Zheng 《Plasma Science and Technology》 SCIE EI CAS CSCD 2021年第10期60-71,共12页
In this study,a laser-assisted pulsed plasma thruster(LA-PPT)with a novel configuration is proposed as an electric propulsion thruster which separates laser ablation and electromagnetic acceleration.Owing to the uniqu... In this study,a laser-assisted pulsed plasma thruster(LA-PPT)with a novel configuration is proposed as an electric propulsion thruster which separates laser ablation and electromagnetic acceleration.Owing to the unique structure of the thruster,metals can also be used as propellants,and a higher specific impulse is expected.The ablation quality,morphology,and plume distribution of various metals(aluminium alloy,red copper,and carbon steel)with different laser energies were studied experimentally.The ablation morphology and plume distribution of red copper were more uniform,as compared to those of other metals,and the ablation quality was higher,indicating its greater suitability for LA-PPT.The plume generated by nanosecond laser ablation of aluminium alloy expanded faster,which indicated that the response time of the thruster with aluminium alloy as the propellant was shorter.In addition,when the background pressure was 0.005 Pa,an obvious plume splitting phenomenon was observed in the ablation plume of the pulsed laser irradiating aluminium alloy,which may significantly reduce the utilisation rate of the propellant. 展开更多
关键词 plasma plume expansion dynamics plume splitting phenomenon nanosecond laser ablation laser-assisted pulsed plasma thruster
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Computational fluid dynamics simulation of friction stir welding:A comparative study on different frictional boundary conditions 认领 引用 被引量：9
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作者 Gaoqiang Chen Qingxian Ma +3 位作者 Shuai Zhang Jianjun Wu Gong Zhang Qingyu Shi 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2018年第1期128-134,共7页
Numerical simulation based on computational fluid dynamics （CFD） is a useful approach for quantitatively investigating the underlying thermal-mechanical conditions during FSW, such as temperature field and material ... Numerical simulation based on computational fluid dynamics （CFD） is a useful approach for quantitatively investigating the underlying thermal-mechanical conditions during FSW, such as temperature field and material deformation field. One of the critical issues in CFD simulation of FSW is the use of the frictional boundary condition, which represents the friction between the welding tool and the workpiece in the numerical models. In this study, three-dimensional numerical simulation is conducted to analyze the heat transfer and plastic deformation behaviors during the FSW of AA2024. For comparison purposes, both the boundary velocity （BV） models and the boundary shear stress （BSS） models are employed in order to assess their performances in predicting the temperature and material deformation in FSW. It is interesting to note that different boundary conditions yield similar predictions on temperature, but quite different predictions on material deformation. The numerical predictions are compared with the experimental results. The predicted deformation zone geometry by the BSS model is consistent with the experimental results while there is large difference between the predictions by the BV models and the experimental measurements. The fact that the BSS model yields more reasonable predictions on the deformation zone geometry is attributed to its capacity to automatically adjust the contact state at the tool/workpiece interface. Based on the favorable predictions on both the temperature field and the material deformation field, the BSS model is suggested to have a better performance in numerical simulation of FSW than the BV model. 展开更多
关键词 Friction stir welding Numerical simulation Frictional boundary condition Heat transfer Material deformation
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