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Nano-silica modified lightweight and high-toughness carbon fiber/phenolic ablator with excellent thermal insulation and ablation performance

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Defence Technology（防务技术） 2024年第1期31卷 192-199页

作者： Wenjie Xu Wenda song Xianfeng Jia Cheng ma Jitong Wang Wenming Qiao Licheng Ling state Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai 200237China school of Chemical Engineering and materials Changzhou Institute of TechnologyChangzhou 213032China Key Laboratory of specially Functional Polymeric materials and Related Technology(Ministry of Education) School of Materials Science and EngineeringEast China University of Science and TechnologyShanghai 200237China

Lightweight and high-toughness carbon fiber/phenolic ablator(CFPA)is required as the Thermal Protection system(TPs)material of aerospace vehicles for next-generation space *** improve the ablative properties,silica sol with good particle size distribution prepared using tetramethoxysilane(TMOs)was blended with natural rubber latex and deposited onto carbon fiber felt,which was then integrated with phenolic aerogel matrix,introducing nano-silica into the framework of *** modified CFPA with a low density of 0.28—0.31 g/cm3exhibits strain-in-fracture as high as 31.2%and thermal conductivity as low as 0.054 W/(m·K).Furthermore,a trace amount of nano-silica could effectively protect CFPA from erosion of oxidizing atmosphere in different high-temperature *** oxyacetylene ablation test of 3000°C for 20 s shows a mass ablation rate of 0.0225 g/s,a linear ablation rate of 0.209 mm/s for the modified CFPA,which are 9.64%and 24.82%lower than the unmodified ***,the long-time butane ablation test of 1200°C for 200 s shows an insignificant recession with mass and linear ablation rate of 0.079 g/s and 0.039 mm/s,16.84%and 13.33%lower than the unmodified ***,the fixed thermocouple in the test also demonstrates a good thermal insulation performance with a low peak back-face temperature of 207.7°C,12.25%lower than the unmodified ***,the nano-silica modified CFPA with excellent overall performance presents promising prospects in high-temperature aerospace applications.

关键词： Nano-silica Carbonfiber Phenolic aerogel Insulation Ablation

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A Comprehensive study of a Low-Grade Heat-Driven Cooling and Power system Based on Heat Current Method

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Journal of Thermal science 2024年第4期33卷 1523-1541页

作者： ZHAO Tian XU Ronghong XIN Yonglin HE Kelun ma Huan YUAN Mengdi CHEN Qun school of Energy storage science and Engineering North China University of TechnologyBeijing100144China Key Laboratory for Thermal science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing100084China

Combined cooling and power(CCP)system driven by low-grade heat is promising for improving energy *** work proposes a CCP system that integrates a regenerative organic Rankine cycle(RORC)and an absorption chiller on both driving and cooling fluid *** system is modeled by using the heat current method to fully consider nonlinear heat transfer and heat-work conversion constraints and resolve its behavior *** off-design system simulation is performed next,showing that the fluid inlet temperatures and flow rates of cooling water as well as RORC working fluid strongly affect system *** off-design operation even becomes infeasible when parameters deviate from nominal values largely due to limited heat transfer capability of components,highlighting the importance of considering heat transfer constraints via heat current *** optimization aiming to minimize the total thermal conductance is also *** efficiency increases by 7.9%and decreases by 12.4%after optimization,with the hot fluid inlet temperature increase from 373.15 to 403.15 K and mass flow rate ranges from 10 to 30 kg/s,emphasizing the necessity of balancing system cost and performance.

关键词： combined cooling and power system organic Rankine cycle absorption chiller cascade heat utilization heat current method off-design analysis

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Measurement and Correlation of Liquid-liquid Equilibria for 1-Hexene-n-Hexane-3-Methysulfolane

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China Petroleum Processing & Petrochemical Technology 2024年第2期26卷 81-87页

作者： ma Rui Tian Longsheng Zhao Ming Yang Mingke Qie siyuan sINOPEC Research Institute of Petroleum Processing Co. Ltd.Beijing 100083China

Utilizing solvent extraction to separate alkanes and olefins from catalytic light gasoline is an effective method for maximizing the utility of gasoline *** study presents the determination of liquid-liquid equilibrium data for the ternary system of 1-hexene-n-hexane-3-methylsulfolane at 30℃,40℃,and 50℃under atmospheric *** obtained data facilitated the construction of a ternary phase diagram for the *** results showed that the extraction selectivity of 1-hexene/n-hexane exceeded 1.5 when using 3-methylsulfolane as the extraction ***,the thermodynamic consistency of the experimental data was examined using Hand’s equation and the Othmer-Tobias *** correlation coefficient,R^(2)≥0.9578,indicated the acceptable reliability of the phase equilibrium ***,the NRTL(non-random two liquid)model was used to correlate the liquid-liquid phase equilibrium data and derive the binary interaction ***,the results demonstrated that the root mean square deviation of the NRTL model correlation values from the experimental values did not exceed 2.5%.

关键词： liquid-liquid phase equilibrium 1-hexene n-hexane 3-methylsulfolane NRTL

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A statistical analysis of the Kappa-type energy spectrum distribution of radiation belt electrons observed by Van Allen Probes

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Earth and Planetary Physics 2024年第2期8卷 368-374页

作者： LuHuai Jiao Xin ma YuanNong Zhang TaiFeng Jin song Fu BinBin Ni Department of space Physics School of Electronic InformationWuhan UniversityWuhan 430072China

The energy spectrum of energetic electrons is a key factor representing the dynamic variations of Earth’s Van Allen radiation *** measurements have indicated that the commonly used maxwellian and Kappa distributions are inadequate for capturing the realistic spectral distributions of radiation belt *** we adopt the Kappa-type(KT)distribution as the fitting function and perform a statistical analysis to investigate the radiation belt electron flux spectra observed by the Van Allen *** calculating the optimal values of the key KT distribution parameters(i.e.,κandθ2)from the observed spectral shapes,we fit the radiation belt electron fluxes at different L-shells under different geomagnetic *** this manner,we obtain typical values of the KT distribution parameters,which are statistically feasible for modeling the radiation belt electron flux profiles during either geomagnetically quiet or active periods.A comparison of the KT distribution model results with those using the maxwellian or Kappa distribution reveals the advantage of the KT distribution for studying the overall properties of the radiation belt electron spectral distribution,which has important implications for deepening the current understanding of the radiation belt electron dynamics under evolving geomagnetic conditions.

关键词： radiation belt electron Kappa-type distribution fitting geomagnetic storm

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Effect of dynamic loading orientation on fracture properties of surrounding rocks in twin tunnels

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 393-409页

作者： Ze Deng Zheming Zhu Lei Zhou Leijun ma Jianwei Huang Yao Zhang Key Laboratory of Deep Earth and Engineering(Ministry of Education) College of Architecture and EnvironmentSichuan UniversityChengdu610065China Failure Mechanics and Engineering Disaster Prevention Key Laboratory of sichuan Province College of Architecture and EnvironmentSichuan UniversityChengdu610065China Institute for Disaster management and Reconstruction Sichuan UniversityChengdu610065China

For expedited transportation,vehicular tunnels are often designed as two adjacent tunnels,which frequently experience dynamic stress waves from various orientations during blasting *** analyze the impact of dynamic loading orientation on the stability of the twin-tunnel,a split Hopkinson pressure bar(sHPB)apparatus was used to conduct a dynamic test on the twin-tunnel *** two tunnels were rotated around the specimen’s center to consider the effect of dynamic loading ***-DYNA software was used for numerical simulation to reveal the failure properties and stress wave propagation law of the twin-tunnel *** findings indicate that,for a twin-tunnel exposed to a dynamic load from different orientations,the crack initiation position appears most often at the tunnel corner,tunnel spandrel,and tunnel *** the impact direction is created by a certain angle(30°,45°,60°,120°,135°,and 150°),the fractures are produced in the middle of the line between the left tunnel corner and the right tunnel *** the impact loading angle(a)is 90°,the tunnel sustains minimal damage,and only tensile fractures form in the surrounding *** orientation of the impact load could change the stress distribution in the twin-tunnel,and major fractures are more likely to form in areas where the tensile stress is concentrated.

关键词： Twin-tunnel Dynamic load split Hopkinson pressure bar(sHPB) Fracture mode stress distribution Displacement field distribution

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state of the art in movement around a remote point:a review of remote center of motion in robotics

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Frontiers of Mechanical Engineering 2024年第2期19卷 1-28页

作者： Wuxiang ZHANG Zhi WANG Ke ma Fei LIU Pengzhi CHENG Xilun DING school of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Ningbo Institute of Technology Beihang UniversityNingbo 315832China Intelligent Aerospace manufacturing Engineering Technology Co. Ltd.Beijing 100191China

The concept of remote center of motion(RCM)is pivotal in a myriad of robotic applications,encompa-ssing areas such as medical robotics,orientation devices,and exoskeletal *** efficacy of RCM technology is a determining factor in the success of these robotic *** paper offers an exhaustive review of RCM technologies,elaborating on their various methodologies and practical *** delves into the unique characteristics of RCM across different degrees of freedom(DOFs),aiming to distill their fundamental *** addition,this paper categorizes RCM approaches into two primary classifications:design based and control *** are further organized according to their respective DOFs,providing a concise summary of their core *** upon the understanding of RCM’s versatile capabilities,this paper then transitions to an in-depth exploration of its applications across diverse robotic *** this review,we critically analyze the existing research challenges and issues that are inherently present in both RCM methodologies and their *** discussion is intended to serve as a guiding framework for future research endeavors and practical deployments in related areas.

关键词： remote center of motion mechanism robotics medical robot orientation device exoskeleton

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Insights into Nano-and Micro-structured scaffolds for Advanced Electrochemical Energy storage

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Nano-Micro Letters 2024年第7期16卷 187-230页

作者： Jiajia Qiu Yu Duan shaoyuan Li Huaping Zhao Wenhui ma Weidong shi Yong Lei Fachgebiet Angewandte Nanophysik Institut Für Physik and IMN MacroNanoTechnische Universit.t Ilmenau98693 IlmenauGermany Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization Faculty of Metallurgical and Energy EngineeringKunming University of Science and TechnologyKunming 650093People’s Republic of China school of Chemistry and Chemical Engineering Jiangsu UniversityZhenjiang 212013People’s Republic of China school of science and Technology Pu’er UniversityPu’er 665000People’s Republic of China

Adopting a nano-and micro-structuring approach to fully unleashing the genuine potential of electrode active material benefits in-depth understandings and research progress toward higher energy density electrochemical energy stor-age devices at all technology readiness *** to various challenging issues,especially limited stability,nano-and micro-structured(NMs)electrodes undergo fast electrochemical performance *** emerging NMs scaffold design is a pivotal aspect of many electrodes as it endows them with both robustness and electrochemical performance enhancement,even though it only occupies comple-mentary and facilitating components for the main ***,extensive efforts are urgently needed toward optimizing the stereoscopic geometrical design of NMs scaffolds to minimize the volume ratio and maximize their functionality to fulfill the ever-increasing dependency and desire for energy power source *** review will aim at highlighting these NMs scaffold design strategies,summariz-ing their corresponding strengths and challenges,and thereby outlining the potential solutions to resolve these challenges,design principles,and key perspectives for future research in this ***,this review will be one of the earliest reviews from this viewpoint.

关键词： Nano-and micro-structured Interconnected porous scaffolds Electrode design Electrochemical energy storage

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In situ Reconfiguration of Assembling Pattern for Modular Continuum Robots

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Journal of Bionic Engineering 2024年第4期21卷 1695-1706页

作者： Jie Zhang Jiannan Cai Ke ma Jinzhao Yang Zhigang Wu Haijun Peng Jianing Wu school of Mechanical Engineering Dalian University of TechnologyDalian116024People’s Republic of China school of Advanced manufacturing Sun Yat-Sen UniversityShenzhen518107People’s Republic of China school of Aeronautics and Astronautics Sun Yat-Sen UniversityShenzhen518107People’s Republic of China

Modular continuum robots possess significant versatility across various scenarios;however,conventional assembling methods typically rely on linear connection between *** limitation can impede the robotic interaction capabilities,especially in specific engineering ***,inspired by the assembling pattern between the femur and tibia in a human knee,we proposed a multidirectional assembling *** strategy encompasses linear,oblique,and orthogonal connections,allowing a two-module continuum robot to undergo in-situ reconfiguration into three distinct initial *** anticipate the final configuration resulting from diverse assembling patterns,we employed the positional formulation finite element framework to establish a mechanical model,and the theoretical results reveal that our customizable strategy can offer an effective route for robotic *** showcased diverse assembling patterns for coping with interaction *** experimental results indicate that our modular continuum robot not only reconfigures its initial profile in situ but also enables on-demand regulation of the final *** capabilities provide a foundation for the future development of modular continuum robots,enabling them to be adaptable to diverse environments,particularly in unstructured surroundings.

关键词： Assembling patterns Continuum robot In-situ reconfiguration Tensegrity structure Varying stiffness

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sTGNN-LMR:A spatial–temporal Graph Neural Network Approach Based on sEMG Lower Limb Motion Recognition

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Journal of Bionic Engineering 2024年第1期21卷 256-269页

作者： Weifan mao Bin ma Zhao Li Jianxing Zhang Yizhou Lu Zhuting Yu Feng Zhang shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201210China University of Chinese Academy of sciences Beijing 101408China University of science and Technology of China Hefei 230026China shanghai Zhongyan Jiuyi Technology Co. Ltd.Shanghai 201821China Academy of Military science Bejing 100091China

Lower limb motion recognition techniques commonly employ surface Electromyographic signal(sEMG)as input and apply a machine learning classifier or Back Propagation Neural Network(BPNN)for ***,this artificial feature engineering technique is not generalizable to similar tasks and is heavily reliant on the researcher’s subject *** contrast,neural networks such as Convolutional Neural Network(CNN)and Long short-term Memory Neural Network(LsTM)can automatically extract features,providing a more generalized and adaptable approach to lower limb motion *** this approach overcomes the limitations of human feature engineering,it may ignore the potential correlation among the sEMG *** paper proposes a spatial–temporal graph neural network model,sTGNN-LMR,designed to address the problem of recognizing lower limb motion from multi-channel ***-LMR transforms multi-channel sEMG into a graph structure and uses graph learning to model spatial–temporal *** 8-channel sEMG dataset is constructed for the experimental stage,and the results show that the sTGNN-LMR model achieves a recognition accuracy of 99.71%.Moreover,this paper simulates two unexpected scenarios,including sEMG sensors affected by sweat noise and sudden failure,and evaluates the testing results using hypothesis *** to the experimental results,the sTGNN-LMR model exhibits a significant advantage over the control models in noise scenarios and failure *** experimental results confirm the effectiveness of the sTGNN-LMR model for addressing the challenges associated with sEMG-based lower limb motion recognition in practical scenarios.

关键词： Lower limb motion recognition Exoskeleton sEMG.Graph neural network Noise sensor failure

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Milk fat globule epidermal growth factor 8 alleviates liver injury in severe acute pancreatitis by restoring autophagy flux and inhibiting ferroptosis in hepatocytes

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World Journal of Gastroenterology 2024年第7期30卷 728-741页

作者： Qing Cui Hang-Cheng Liu Wu-Ming Liu Feng ma Yi Lv Jian-Cang ma Rong-Qian Wu Yi-Fan Ren Department of Cardiology Xi’an Central Hospital Affiliated to Xi’an Jiaotong UniversityXi’an 710003Shaanxi ProvinceChina Department of General surgery The Second Affiliated Hospital of Xi’an Jiaotong UniversityXi’an 710004Shaanxi ProvinceChina National Local Joint Engineering Research Center for Precision surgery&Regenerative Medicine Shaanxi Provincial Center for Regenerative Medicine and Surgical EngineeringFirst Affiliated Hospital of Xi’an Jiaotong UniversityXi’an 710061Shaanxi ProvinceChina Department of Vascular surgery The Second Affiliated Hospital of Xi’an Jiaotong UniversityXi’an 710004Shaanxi ProvinceChina

BACKGROUND Liver injury is common in severe acute pancreatitis(sAP).Excessive autophagy often leads to an imbalance of homeostasis in hepatocytes,which induces lipid peroxidation and mitochondrial iron deposition and ultimately leads to *** previous study found that milk fat globule epidermal growth factor 8(MFG-E8)alleviates acinar cell damage during sAP via binding toαvβ3/5 ***-E8 also seems to mitigate pancreatic fibrosis via inhibiting chaperone-mediated *** To speculate whether MFG-E8 could also alleviate sAP induced liver injury by restoring the abnormal autophagy *** sAP was induced in mice by 2 hly intraperitoneal injections of 4.0 g/kg L-arginine or 7 hly injections of 50μg/kg cerulein plus ***8-knockout mice were used to study the effect of MFG-E8 deficiency on sAPinduced liver ***,a specificαvβ3/5 integrin inhibitor,was used to investigate the possible mechanism of *** The results showed that MFG-E8 deficiency aggravated sAP-induced liver injury in mice,enhanced autophagy flux in hepatocyte,and worsened the degree of *** MFG-E8 reduced sAP-induced liver injury in a dose-dependent ***,MFG-E8 mitigated excessive autophagy and inhibited ferroptosis in liver *** abolished MFG-E8’s beneficial effects in sAP-induced liver *** MFG-E8 acts as an endogenous protective mediator in sAP-induced liver ***-E8 alleviates the excessive autophagy and inhibits ferroptosis in hepatocytes by binding to integrinαVβ3/5.

关键词： Autophagy flux Ferroptosis Liver injury Milk fat globule epidermal growth factor 8 αvβ3/5 integrins Acute pancreatitis

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