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An Improved Thermal Conductivity Measurement Scheme for Macroscopic Graphitic Films Using the Laser Flash Method

Journal of Thermal Science 2024年第4期33卷 1480-1490页

作者： ZHANG Peijuan MING Xin LIU Yingjun WANG Xuelong SHI Hang HAO Yuanyuan LU Jiahao LIU Zheng LAI Haiwen ZHANG Ying gao Weiwei XU Zhen gao Chao MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringKey Laboratory of Adsorption and Separation Materials&Technologies of Zhejiang ProvinceZhejiang UniversityHangzhou310027China Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering Taiyuan030032China Special Equipment Safety Supervision and Inspection Institute of Jiangsu Province National Graphene Products Quality Inspection and Testing Center(Jiangsu)Wuxi214174China Hangzhou gaoxi Technol Co. LtdHangzhou311113China China Academy of Aerospace Aerodynamics Beijing100074China

Achieving efficient thermal management urges to exploit high-thermal-conductivity materials to satisfy the boosted demand of heat *** is critical to adopt standardized characterization protocols to evaluate the intrinsic thermal conductivity of thermal management ***,for the most representative laser flash method,the lack of standard measurement methodology and systematic description on the thermal diffusivity and influencing factors has led to significant deviations and confusion of the thermal conduction performance in the emerging thermal management ***,the measurement error factors of thermal diffusivity by the common laser flash analyzer(LFA)are *** high-thermal-conductivity graphitic film(gf)as a typical case,the key factors are analyzed to guide the measurement protocol of related carbon-based thermal management *** basic principle of the LFA measurement,actual pre-processing conditions,instrument parameters setting,and data analysis are elaborated for accurate ***,the graphene thick films and common isotropic materials are also extended to meet various thermal measurement *** on the existing practical problems,we propose a feasible test flow to achieve a unified and standardized thermal conductivity measurement,which is beneficial to the rapid development of carbon-based thermal management materials.

关键词： thermal management graphitic film laser flash method thermal conductivity thermal diffusivity

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Highly Thermally Conductive and Structurally Ultra‑Stable Graphitic Films with Seamless Heterointerfaces for Extreme Thermal Management

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Nano-Micro Letters 2024年第3期16卷 383-397页

作者： Peijuan Zhang Yuanyuan Hao Hang Shi Jiahao Lu Yingjun Liu Xin Ming Ya Wang Wenzhang Fang Yuxing Xia Yance Chen Peng Li Ziqiu Wang Qingyun Su Weidong Lv Ji Zhou Ying Zhang Haiwen Lai Weiwei gao Zhen Xu Chao gao MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringKey Laboratory of Adsorption and Separation Materials and Technologies of Zhejiang ProvinceZhejiang University38 Zheda RoadHangzhou 310027People’s Republic of China Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering Taiyuan 030032People’s Republic of China Beijing Spacecrafts Manufacturing Co. LtdBeijing Friendship Road 104Haidian DistrictBeijing 100094People’s Republic of China Beijing Institute of Space Mechanics and Electricity Beijing Friendship Road 104Haidian DistrictBeijing 100094People’s Republic of China China Academy of Aerospace Aerodynamics Beijing 100074People’s Republic of China Hangzhou gaoxi Technol Co. LtdHangzhou 311113People’s Republic of China International Research Center for X Polymers International CampusZhejiang UniversityHaining 314400People’s Republic of China

Highly thermally conductive graphitic film(gf)materials have become a competitive solution for the thermal management of high-power electronic ***,their catastrophic structural failure under extreme alternating thermal/cold shock poses a significant challenge to reliability and ***,we present the first investigation into the structural failure mechanism of gf during cyclic liquid nitrogen shocks(LNS),which reveals a bubbling process characterized by“permeation-diffusion-deformation”*** overcome this long-standing structural weakness,a novel metal-nanoarmor strategy is proposed to construct a Cu-modified graphitic film(gf@Cu)with seamless *** well-designed interface ensures superior structural stability for gf@Cu after hundreds of LNS cycles from 77 to 300 ***,gf@Cu maintains high thermal conductivity up to 1088 W m^(−1)K^(−1)with degradation of less than 5%even after 150 LNS cycles,superior to that of pure gf(50%degradation).Our work not only offers an opportunity to improve the robustness of graphitic films by the rational structural design but also facilitates the applications of thermally conductive carbon-based materials for future extreme thermal management in complex aerospace electronics.

关键词： Highly thermally conductive Structurally ultra-stable Graphitic film Extreme thermal management Liquid nitrogen bubbling

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High-fat diet impairs gut barrier through intestinal microbiota-derived reactive oxygen species

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Science China(Life Sciences) 2024年第5期67卷 879-891页

作者： Nianyi Zeng Fan Wu Junqi Lu Xiang Li Shaomei Lin Lang Zhou Zhongwei Wang Guangyan Wu Qingfa Huang Daowen Zheng Jie gao Shan Wu Xiaojiao Chen Muxuan Chen Fanguo Meng Haitao Shang Yan He Peng Chen Hong Wei Zhuang Li Hongwei Zhou Microbiome Medicine Center Department of Laboratory MedicineZhujiang HospitalSouthern Medical UniversityGuangzhou 510282China Department of Environmental Health Guangdong Provincial Key Laboratory of Tropical Disease ResearchSchool of Public Health and Tropical MedicineSouthern Medical UniversityGuangzhou 510515China Redox Medical Center for Public Health Soochow UniversitySuzhou 215301China Precision Medicine Institute The First Affiliated HospitalSun Yat-sen UniversityGuangzhou 510080China Department of Pathophysiology Guangdong Provincial Key Laboratory of ProteomicsSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou 510515China

Gut barrier disruption is a key event in bridging gut microbiota dysbiosis and high-fat diet(HFD)-associated metabolic ***,the underlying mechanism remains *** the present study,by comparing HFD-and normal diet(ND)-treated mice,we found that the HFD instantly altered the composition of the gut microbiota and subsequently damaged the integrity of the gut *** sequencing revealed that the HFD upregulates gut microbial functions related to redox reactions,as confirmed by the increased reactive oxygen species(ROS)levels in fecal microbiota incubation in vitro and in the lumen,which were detected using in vivo fluorescence *** microbial ROS-producing capability induced by HFD can be transferred through fecal microbiota transplantation(FMT)into germ-free(gf)mice,downregulating the gut barrier tight ***,mono-colonizing gf mice with an Enterococcus strain excelled in ROS production,damaged the gut barrier,induced mitochondrial malfunction and apoptosis of the intestinal epithelial cells,and exacerbated fatty liver,compared with other low-ROS-producing Enterococcus *** administration of recombinant high-stability-superoxide dismutase(SOD)significantly reduced intestinal ROS,protected the gut barrier,and improved fatty liver against the *** conclusion,our study suggests that extracellular ROS derived from gut microbiota play a pivotal role in HFD-induced gut barrier disruption and is a potential therapeutic target for HFD-associated metabolic diseases.

关键词： fatty liver disease gut microbiota gut barrier high-fat diet oxidative stress reactive oxygen species

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n-余纯Gorenstein AC模

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山东大学学报（理学版） 2024年第6期59卷 71-75,90页

作者：高娜娜杨刚兰州交通大学数理学院甘肃兰州730070

设R是环,n是固定非负整数,GJ_(n)(gf_(n))是Gorenstein AC内射(Gorenstein AC平坦)维数至多为n的左(右)R-模构成的类。称左(右)R-模M是n-余纯Gorenstein AC-内射模(n-余纯Gorenstein AC平坦模),若对任意的N∈GJ_(n),都有Ext_(R)^(1)(N,M)=0(Tor_(1)^(R)(M,N)=0)。证明了有限表现右R-模M是n-余纯Gorenstein AC平坦的当且仅当M是右R-模K的gf_(n)-预包络K→F的上核,其中F是平坦的。

关键词： n-余纯Gorenstein AC内射模 n-余纯Gorenstein AC-平坦模 gf_(n)-预包络

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考虑关节间隙的多维隔振系统振动特性分析

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振动工程学报 2024年第3期37卷 448-456页

作者：高翔石峰牛军川董瑞春山东理工大学机械工程学院山东淄博255000 中铝万成山东建设有限公司山东淄博255000 山东大学机械工程学院山东济南250061

为隔离车载精密仪器承受的多维振动,引入基于并联机构且考虑机构关节间隙的多维被动隔振系统。通过gf集(Generalized Function Set)型综合理论,得到一种具有三平移一转动运动特性的4-PUU(移动副-虎克副-虎克副)并联机构,在主动关节处添... 详细信息

为隔离车载精密仪器承受的多维振动,引入基于并联机构且考虑机构关节间隙的多维被动隔振系统。通过gf集(Generalized Function Set)型综合理论,得到一种具有三平移一转动运动特性的4-PUU(移动副-虎克副-虎克副)并联机构,在主动关节处添加弹簧和黏滞阻尼器,建立考虑关节间隙的多维隔振系统运动学和动力学方程,研究存在关节间隙的多维隔振系统在谐波、随机路面激励下的时域、频域隔振能力。研究结果表明:存在关节间隙的多维隔振系统能够实现多维振动在时域和频域中的有效衰减;随着关节间隙数值逐渐增大,隔振能力沿x轴方向变化最敏感,沿y轴方向变化最不敏感;系统第一阶共振峰对关节间隙变化敏感,向低频区域移动,隔振能力恶化。

关键词：多维隔振系统并联机构关节间隙隔振性能

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基于改进Deeplab-v3+的土地覆盖分类

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测绘与空间地理信息 2024年第3期47卷 150-152页

作者：高鹏远河北省煤田地质局物测地质队河北邢台054000

土地覆盖分类是全球变化研究的核心,精准分类是开展土地覆盖分类变化研究的基础。基于此,本文以Deeplab-v3+模型为基础,在编码阶段改进ASPP模型,并采用Xception-ResNet结合的网络结构,解码阶段引入跃层特征融合优化模块,得到改进后的Dee... 详细信息

土地覆盖分类是全球变化研究的核心,精准分类是开展土地覆盖分类变化研究的基础。基于此,本文以Deeplab-v3+模型为基础,在编码阶段改进ASPP模型,并采用Xception-ResNet结合的网络结构,解码阶段引入跃层特征融合优化模块,得到改进后的Deeplab-v3+模型,对研究区进行土地覆盖分类提取。结果表明:改进后的模型分类精度为82.93%,训练速度为7 h 22 min,相比原始模型分别提高了4%,模型训练速度提升了25%。综上可知,改进后的Deeplab-v3+模型可以实现快速且高精度的土地覆盖分类,可为土地覆盖分类研究提供技术支持。

关键词：深度学习语义分割高分二号土地分类

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模拟CO_(2)浓度和温度升高对宁夏枸杞果实品质形成的影响

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林业科学 2024年第3期60卷 1-9页

作者：马亚平冯学瑞高捍东宋丽华曹兵宁夏大学林业与草业学院林木资源高效生产全国重点实验室银川750021 南京林业大学林学院南京210037

【目的】探究CO_(2)浓度和温度升高对3个宁夏枸杞品种形态特征和营养组分积累的影响,为未来气候变化背景下培育高抗性优良枸杞品种以及经济林应对气候变化的适应性管理提供依据。【方法】采用开顶气室(OTC)模拟控制系统,对3个宁夏枸杞品... 详细信息

【目的】探究CO_(2)浓度和温度升高对3个宁夏枸杞品种形态特征和营养组分积累的影响,为未来气候变化背景下培育高抗性优良枸杞品种以及经济林应对气候变化的适应性管理提供依据。【方法】采用开顶气室(OTC)模拟控制系统,对3个宁夏枸杞品种(‘宁杞1号’、‘宁杞7号’、‘宁杞10号’)分别进行CO_(2)浓度(e CO_(2))和温度(e T)升高处理。在果实发育的幼果期(YF,处理60天)、青果期(gf,处理70天)、转色期(CF,处理80天)和红果期(RF,处理90天)采集果实,测定其形态特征和营养组分含量。【结果】1)形态特征分析表明,在CO_(2)浓度升高处理下,‘宁杞1号’果实转色期纵、横径及红果期横径和单果质量显著增加,‘宁杞7号’青果期纵径和转色期横径显著增加,‘宁杞10号’幼果期横径和转色期单果质量显著增加。在温度升高处理下,‘宁杞1号’果实转色期和红果期纵径以及红果期单果质量显著增加,‘宁杞7号’青果期和转色期纵径、转色期和红果期横径和单果质量也显著增加,‘宁杞10号’单果质量显著增加(P<0.05)。2)营养组分分析表明,CO_(2)浓度升高处理显著增加‘宁杞1号’果实4个发育阶段的半乳糖、蔗糖、甜菜碱和黄酮含量,‘宁杞7号’果实红果期果糖、总糖、蔗糖、多糖、类胡萝卜素及甜菜碱含量显著增加,‘宁杞10号’果实红果期半乳糖、果糖、葡萄糖、多糖含量显著增加(P<0.05)。温度升高处理显著增加‘宁杞1号’红果期半乳糖、果糖、总糖、多糖、甜菜碱及黄酮含量,‘宁杞7号’4个发育阶段半乳糖、葡萄糖、蔗糖及红果期果糖、总糖、多糖、类胡萝卜素及甜菜碱含量显著增加,‘宁杞10号’4个发育阶段蔗糖、类胡萝卜素和黄酮含量及红果期半乳糖、总糖、甜菜碱含量显著增加(P<0.05)。【结论】CO_(2)浓度和温度升高对宁夏枸杞果实形态发育和营养组分积累均产生影响。‘宁杞10号’表现出更强的适应性,该品种在发育期,果实大小、单果质量和百粒质量增长最大,果实半乳糖、果糖、总糖、多糖、类胡萝卜素、甜菜碱含量增加显著。

关键词：宁夏枸杞形态特征 CO_(2)浓度升高气温升高枸杞多糖

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Type Synthesis of Walking Robot Legs

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Chinese Journal of Mechanical Engineering 2018年第1期31卷 53-65页

作者： Da Xi Feng gao State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University

Walking robots use leg structures to overcome obstacles or move on complicated terrains. Most robots of current researches are equipped with legs of simple structure. The specific design method of walking robot legs is seldom studied. Based on the generalized-function(gf) set theory, a systematic type synthesis process of designing robot legs is introduced. The specific mobility of robot legs is analyzed to obtain two main leg types as the goal of *** synthesis problem is decomposed into two stages, actuation and constraint synthesis by name,corresponding to the combinatorics results of linear Diophantine equations. Additional restrictions are discussed to narrow the search range to propose practical limb expressions and kinematic-pair designs. Finally, all the fifty-one leg structures of four subtypes are carried out, some of which are chosen to make up robot prototypes, demonstrating the validity of the method. This paper proposed a novel type synthesis methodology, which could be used to systematically design various practical robot legs and the derived robots.

关键词： Type synthesis Robot leg gf set Number synthesis Linear Diophantine equation

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Type Synthesis for Bionic Quadruped Walking Robots

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Journal of Bionic Engineering 2015年第4期12卷 527-538页

作者： Jun He Feng gao State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai 200240 China

Regarding walking robots, biomimetic design has attracted a great deal of attention. Currently, studies have focused mainly on performance analysis and the design of some specific biomimetic walking robots. However, the systematic type synthesis of bionic quadruped robots has seldom been studied. In this paper, a new approach to type synthesis for quadruped walking robots is proposed based on the generalized fimction （Ge） set theory. The current types of typical walking robots are analyzed using the Ge set theory. The research status and existing problems are investigated. The skeletal systems of quadruped mammals are analyzed. The motion characteristics of all joints of quadruped mammals are denoted by 6;F sets. A process of conversion from biological types to serial, parallel and hybrid types is proposed. Limb types in serial, parallel and hybrid topology are synthe- sized. Finally the quadruped robots with serial, parallel and hybrid topology are produced. Two of these types have been suc- cessfully used for the design of walking rescue robots that is suitable for responding to nuclear accidents.

关键词： type synthesis bionic design quadruped robot parallel mechanism gf set

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HDPE/改性蛭石复合材料的制备与气体阻隔性能研究

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塑料工业 2024年第1期52卷 46-51页

作者：刘会鹏潘凯高源卢晓英陈轲北京化工大学材料科学与工程学院北京100029 中国石油天然气股份有限公司石油化工研究院北京102206 北京化工大学塑料机械及塑料工程研究所北京100029

利用改性后的蛭石作为填充材料,通过熔融共混法制备了高密度聚乙烯(HDPE)/改性蛭石复合材料。研究了改性蛭石的添加量对复合材料热稳定性能、结晶性能、力学性能和氧气阻隔性能的影响。结果表明,相比纯HDPE,HDPE/改性蛭石复合材料仍能... 详细信息

利用改性后的蛭石作为填充材料,通过熔融共混法制备了高密度聚乙烯(HDPE)/改性蛭石复合材料。研究了改性蛭石的添加量对复合材料热稳定性能、结晶性能、力学性能和氧气阻隔性能的影响。结果表明,相比纯HDPE,HDPE/改性蛭石复合材料仍能保持较好的拉伸强度,当含量为1%时拉伸强度为24.1 MPa,断裂伸长率先提高后下降,当含量为0.5%时断裂伸长率达到最高为535%;改性蛭石的加入提升了材料的韧性,当改性蛭石含量为1%时材料缺口冲击强度达到最高为45.8 kJ/m^(2);HDPE/改性蛭石复合材料的氧气阻隔性能明显提升,当改性蛭石含量为1%时材料的氧气阻隔性能达到最优,氧气渗透系数为6.9×10^(-15)cm^(3)·cm/(cm^(2)·s·Pa)。

关键词：高密度聚乙烯膨胀蛭石改性气体阻隔

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