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摩擦力对空间非导电绳系释放动力学的影响

兵工学报 2024年第4期45卷 1158-1167页

作者：梁福文苗龙田丰宋家辉白松何梓豪王宁飞北京理工大学宇航学院北京100081

当前空间非导电绳系释放过程因摩擦力数据缺乏,导致释放动力学仿真结果不能有效反映真实情况。为此,基于绳系地面释放平台,开展非导电绳系释放摩擦力测量实验,研究了系绳材料、直径、缠绕方向和释放速度对系绳释放所受摩擦力的影响,阐... 详细信息

当前空间非导电绳系释放过程因摩擦力数据缺乏,导致释放动力学仿真结果不能有效反映真实情况。为此,基于绳系地面释放平台,开展非导电绳系释放摩擦力测量实验,研究了系绳材料、直径、缠绕方向和释放速度对系绳释放所受摩擦力的影响,阐明非导电绳系释放过程影响球形效应不稳定现象的主要因素,确定非导电绳系释放摩擦力与释放条件之间的定量关系。进一步建立考虑摩擦力的绳系释放动力学模型。仿真结果表明,非导电绳系释放摩擦力对释放过程影响较大,对于500 m长的系绳,初始释放速度为2 m/s,在未考虑释放摩擦力时,绳系释放完成时间与考虑摩擦力的实际情况相差约20%。

关键词：空间绳系释放摩擦力地面实验释放速度动力学仿真

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Influence of extracellular polymeric substances from activated sludge on the aggregation kinetics of silver and silver sulfide nanoparticles

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Frontiers of Environmental Science & Engineering 2022年第2期16卷 13-24页

作者： Wanpeng Chen jiahui song Shaojie Jiang Qiang He Jun Ma Xiaoliu Huangfu Key Laboratory of Eco-environments in Three Gorges Reservoir Region(Ministry of Education) College of Environment and EcologyChongqing UniversityChongqing 400044China Sichuan Education Press Chengdu 610200China State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of TechnologyHarbin 150090China

Extracellular polymeric substances(EPS)in activated sludge from wastewater treatment plants(WWTPs)could affect interactions between nanoparticles and alter their migration behavior.The influence mechanisms of silver nanoparticles(Ag NPs)and silver sulfide nanoparticles(Ag_(2)S NPs)aggregated by active EPS sludge were studied in monovalent or divalent cation solutions.The aggregation behaviors of the NPs without EPS followed the Derjaguin-Landau-Verwey-Overbeek(DLVO)theory.The counterions aggravated the aggregation of both NPs,and the divalent cation had a strong neutralizing effect due to the decrease in electrostatic repulsive force.Through extended DLVO(EDLVO)model analysis,in NaNO3 and low-concentration Ca(NO_(3))_(2)(<10 mmol/L)solutions,EPS could alleviate the aggregation behaviors of Cit-Ag NPs and Ag_(2)S NPs due to the enhancement of steric repulsive forces.At high concentrations of Ca(NO_(3))_(2)(10‒100 mmol/L),exopolysaccharide macromolecules could promote the aggregation of Cit-Ag NPs and Ag_(2)S NPs by interparticle bridging.As the final transformation form of Ag NPs in water environments,Ag_(2)S NPs had better stability,possibly due to their small van der Waals forces and their strong steric repulsive forces.It is essential to elucidate the surface mechanisms between EPS and NPs to understand the different fates of metal-based and metal-sulfide NPs in WWTP systems.

关键词： Silver nanoparticles Silver sulfide nanoparticles Extracellular polymeric substances Aggregation kinetics Influence mechanisms

组合倾角对软硬介质组合岩体动态力学特性的影响

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岩石力学与工程学报 2024年第S1期43卷 3342-3353页

作者：王雁冰宋佳辉杨柳邹宝平任斌李林青中国矿业大学(北京)力学与土木工程学院北京100083 浙江科技大学土木与建筑工程学院浙江杭州310023

为探究冲击荷载下不同组合倾角软硬介质组合岩体的动力学响应特性,利用分离式霍普金森压杆(SHPB)、高速相机和离散格子弹簧法(DLSM)数值模拟,对花岗岩-砂岩6种不同组合倾角软硬介质组合岩体进行动态冲击试验,研究6种不同组合倾角软硬介... 详细信息

为探究冲击荷载下不同组合倾角软硬介质组合岩体的动力学响应特性,利用分离式霍普金森压杆(SHPB)、高速相机和离散格子弹簧法(DLSM)数值模拟,对花岗岩-砂岩6种不同组合倾角软硬介质组合岩体进行动态冲击试验,研究6种不同组合倾角软硬介质组合岩体的应力波传播特征、应力-应变曲线差异、能量耗散规律、损伤演化特性以及总动能同岩体裂纹扩展之间的关系。结果表明:软硬介质组合岩体的动态力学特性及能量耗散规律均与组合倾角相关。组合倾角由0°增加至75°时,试件透射波幅值、峰值应力、动态弹性模量呈先增大后减小的变化趋势,反射波幅值呈先减小后增大的变化趋势。组合倾角为45°~60°,软硬介质组合岩体容易被破坏。组合倾角不仅会阻碍应力波传播也会影响胶结面两侧岩石的应力变化,使胶结面两侧岩体产生二次加载现象。岩体的损伤值随组合倾角增加呈倒“V”型变化,45°~60°范围内试件的损伤值最高。组合倾角越大,岩体破坏过程中总动能越低,裂纹则越少,试件的变形位移量越小。

关键词：岩石力学组合倾角组合岩体分离式霍普金森压杆能量耗散离散格子弹簧法

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人工智能时代我国高等教育变革路径探索

大学（研究与管理） 2024年第3期 6-9页

作者：宋佳慧渤海大学辽宁锦州121000

在当今信息化的时代背景下,教育已经成为社会发展的重要组成部分。随着信息技术的发展,传统的教学模式已经不能满足人们的需求,如何适应新的技术环境成为当前亟须解决的问题之一。人工智能作为一种新兴的技术手段被广泛应用于各个领域... 详细信息

在当今信息化的时代背景下,教育已经成为社会发展的重要组成部分。随着信息技术的发展,传统的教学模式已经不能满足人们的需求,如何适应新的技术环境成为当前亟须解决的问题之一。人工智能作为一种新兴的技术手段被广泛应用于各个领域中。在高等教育领域,其应用也逐渐成为研究热点。目前,我国高等教育面临着诸多挑战,如课程设置不合理、师资力量不足、学生素质参差不齐等问题。这些问题不仅影响了高等教育的质量,而且对国家发展和人才培养产生了负面影响。在这样的局面下,如何利用人工智能来促进高等教育改革显得尤为重要。本研究旨在探讨人工智能时代高等教育的基础理论及现实背景,分析其基础理论及影响因素,并提出可行的实施方案,为我国高等教的转型提供有效的参考。

关键词：人工智能高等教育人才培养

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空心阴极羽流等离子体放电不稳定性二维仿真模型

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兵工学报 2024年第4期45卷 1208-1218页

作者：田丰苗龙梁福文宋家辉何梓豪武志文王宁飞北京理工大学宇航学院北京100081

空心阴极放电过程中空间电势振荡会影响其工作性能,振荡过程产生的高能离子会对阴极孔产生溅射腐蚀,进而严重影响空心阴极的使用寿命。建立由质点网格(Particle-in-Cell,PIC)模型、振荡幅值模型与等效电路模型组成的一体化耦合模型来计... 详细信息

空心阴极放电过程中空间电势振荡会影响其工作性能,振荡过程产生的高能离子会对阴极孔产生溅射腐蚀,进而严重影响空心阴极的使用寿命。建立由质点网格(Particle-in-Cell,PIC)模型、振荡幅值模型与等效电路模型组成的一体化耦合模型来计算空心阴极放电过程电势振荡特性。采用PIC模型计算不同放电电流、放电电压及气体流量下羽流等离子体放电特性,获得羽流的电势、等离子数密度、电场强度和电子温度等时均参数的空间分布。基于等离子体聚集与耗散理论,建立电势振荡幅值模型,根据计算得到的时均参数来预估空间电势振荡幅值。将等离子体时均参数以及电势幅值振荡参数作为输入参数,代入到空心阴极放电等效电路模型中,从而得到相应工况下的电势振荡波形图。通过和实验结果对比发现,所建立的一体化耦合模型能较好地预估空心阴极羽流等离子体电势振荡特性,研究成果可用于指导空心阴极稳定放电,提升空心阴极在轨工作时限。

关键词：空心阴极质点网格模型电势振荡等效电路模型等离子体聚集与耗散

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钢丝绳芯输送带接头强度与预成型芯胶技术研究

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煤炭科学技术 2024年第4期52卷 336-345页

作者：张弘玉李军霞宋佳辉樊文瑞太原理工大学机械与运载工程学院山西太原030024 矿山流体控制国家地方联合工程实验室山西太原030024 山西省矿山流体控制工程技术研究中心山西太原030024

钢丝绳芯输送带是带式输送机的牵引和运载构件,接头破坏是引起钢丝绳芯输送带故障的主要原因。为了提高输送带的接头强度和接头硫化效率,基于现有接头硫化工艺,提出了一种预成型芯胶敷设技术,以ST1600型钢丝绳芯输送带接头为研究对象,... 详细信息

钢丝绳芯输送带是带式输送机的牵引和运载构件,接头破坏是引起钢丝绳芯输送带故障的主要原因。为了提高输送带的接头强度和接头硫化效率,基于现有接头硫化工艺,提出了一种预成型芯胶敷设技术,以ST1600型钢丝绳芯输送带接头为研究对象,对该技术的应用进行了理论分析和试验研究。首先,建立输送带接头力学模型并进行受力分析,通过ANSYS Workbench软件研究钢丝绳水平、垂直间距不均匀性对接头强度的影响,然后,提出预成型芯胶敷设方法,通过芯胶流固耦合分析对比了填充式芯胶与三角形、梯形和半圆形芯胶凹槽对限制钢丝绳偏移的作用效果。最后,通过接头预成型芯胶硫化试验研究了该技术对输送带胶体粘合强度、接头硫化效率以及接头强度的影响。研究表明:输送带接头处钢丝绳的受力与其纵向位移有关,由于传统接头硫化作业中无法实现钢丝绳的均匀分布从而引起钢丝绳受力不均,影响接头强度,而钢丝绳水平间距相较垂直间距的变化对钢丝绳等效应力的影响尤为显著,更易引起接头钢丝绳的破坏。预成型芯胶敷设技术能够有效减少钢丝绳的偏移量,其中半圆形芯胶凹槽效果最优,水平方向减少70%,垂直方向减少86.9%。在相同硫化条件下,与填充式芯胶相比,三角形、梯形和半圆形芯胶凹槽硫化后的粘合强度分别提升了1.91%、−3.51%、2.48%,半圆形芯胶与钢丝绳结合度最好;采用半圆形芯胶凹槽的预成型芯胶技术敷设钢丝绳可减少70%作业时间,硫化后的输送带接头强度提高5.74%。研究结果可为钢丝绳芯接头硫化工艺的改进提供理论和实践指导。

关键词：钢丝绳芯输送带预成型芯胶硫化工艺接头强度

Carbon dots-enhanced pH-responsive lubricating hydrogel based on reversible dynamic covalent bondings

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Chinese Chemical Letters 2024年第5期35卷 232-237页

作者： Jianye Kang Xinyu Yang Xuhao Yang jiahui Sun Yuhang Liu Shutao Wang Wenlong song State Key Laboratory of Supramolecular Structure and Materials College of ChemistryJilin UniversityChangchun 130012China CAS Key Laboratory of Bio-inspired Materials and Interfacial Science CAS Center for Excellence in NanoscienceTechnical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Due to the various pH liquid environment in nature,the pH-responsive lubricating hydrogel is widely investigated and developed for tissue interface substitute.However,the applied liquid environment will lead to poor mechanical property and weaken the pH-responsive capability.In this work,a carbon dotsenhanced pH-responsive lubricating hydrogel is developed by combining a pH-responsive section of dynamic PVA-borax network into a PAAm covalent polymer network.The formed hydrogel presents a partial gel-sol transition under controlled pH environments.At low pH environments(<6.0),the formed lubricating layer originated from dynamic disassembly of PVA-borax hydrogel,and brings the lubricating properties on the hydrogel surface.Moreover,the mechanical strength and lubrication properties are well promoted by introducing the carbon dots into the hydrogel,the blue sol layer can be observed more visually under the fluorescence microscope.The pH-response also exhibits well reversibility.The prepared hydrogel broadens the idea for designing pH-responsive soft materials for soft lubricating actuator or robot.

关键词： pH-responsive Carbon dots Dynamic covalent bonding Lubrication

An equivalent model of discharge instability in the discharge chamber of Kaufman ion thruster

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Plasma Science and Technology 2022年第11期24卷 126-134页

作者：田丰谢侃苗龙梁福文宋家辉白松王宁飞 School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081People’s Republic of China

The industrial application of the Kaufman ion thruster in its arc stage is limited owing to the instability of the discharge pulse.Presently,a complete prediction model that can predict the discharge pulse in the high-current stage does not exist.In this study,a complete prediction model for the pulse in the ion thruster is established using the zero-dimensional plasma discharge model and equivalent circuit model.The zero-dimensional plasma discharge model is used to obtain the corresponding plasma parameters by calculating the beam current,discharge current,voltage,and gas flow under actual working conditions.The input parameters of the equivalent circuit model are calculated using empirical formulae to acquire the estimated discharge waveforms.The pulse waveforms obtained using the model are found to be consistent with the experimental results.The model is used to evaluate the process of rapid changes in plasma density.Additionally,this model is employed to predict changes in the pulse waveforms when the volume of the discharge chamber and grid plate transmittance are changed.

关键词： Kaufman ion thruster arc discharge pulse phenomenon zero-dimensional plasma discharge model equivalent circuit model

Multifunctional high-performance pressure/proximity/temperature sensors enabled by hybrid resistive-supercapacitive response

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Nano Research 2024年第6期17卷 5604-5613页

作者： Huijun Kong Zhongqian song Meichun Ding Changxiang Shao jiahui Yu Baolei Wang Weiyan Li Chenwei Li Li Niu School of Chemistry and Pharmaceutical Engineering Shandong First Medical University and Shandong Academy of Medical SciencesJinan 250117China College of Artificial Intelligence and Big Data for Medical Sciences Shandong First Medical University and Shandong Academy of Medical SciencesJinan 250117China School of Chemical Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

The issue of sensitivity attenuation in high-pressure region has been a persistent concern for pressure-sensitive electronic skins.In order to tackle such trade-off between sensitivity and linear range,herein,a hybrid piezoresistive-supercapacitive(HRSC)strategy is proposed via introducing a piezoresistive porous aerogel layer between the charge collecting electrodes and iontronic films of the pressure sensors.Surprisingly,the HRSC-induced impedance regulation and supercapacitive behavior contribute to significant mitigation in sensitivity attenuation,achieving high sensitivity across wide linear range(44.58 kPa^(−1)from 0 to 3 kPa and 23.6 kPa^(−1)from 3 to 12 kPa).The HRSC pressure sensor exhibits a low detection limit of 1 Pa,fast responsiveness(~130 ms),and excellent cycling stability,allowing to detect tiny pressure of air flow,finger bending,and human respiration.Meanwhile,the HRSC sensor exhibits exceptional perception capabilities for proximity and temperature,broadening its application scenarios in prosthetic perception and electronic skin.The proposed HRSC strategy may boost the ongoing research on structural design of high-performance and multimodal electronic sensors.

关键词： multimodal sensor pressure sensor high sensitivity MXene/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)aerogel structural design