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Influence of Participating Radiation on Measuring Thermal Conductivity of Translucent Thermal Insulation Materials with Hot Strip Method

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Journal of Thermal Science 2022年第4期31卷 1023-1036页

作者： zhang hu WU Kefan TANG Guihua State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace Engineering Xi'an Jiaotong Universityxi'an 710049china MOE Key Laboratory of Thermo-Fluid Science and Engineering School of Energy and Power Engineering Xi'an Jiaotong Universityxi'an 710049china

The hot strip method,as one typical transient method,is widely used to measure the effective thermal conductivity of thermal insulation materials at various *** the test theory is based on solving the energy equation via heat conduction,the test result will be questionable when measuring thermal insulation materials,such as silica aerogel and photovoltaic glazing,in which the participating thermal radiation is a dominant heat transfer mode at high *** this study,numerical investigation is employed to reveal the measurement reliability of hot strip method when applied to translucent thermal insulation *** reproducing the dynamic conduction-radiation coupled heat transfer process within the translucent materials numerically,the effective thermal conductivity of translucent materials with varying extinction coefficients are obtained at various *** are made for the effective thermal conductivity of translucent materials determined by the hot strip method,one-dimensional steady state method,transient plane source method and Rosseland *** discrepancies are found among the effective thermal conductivity determined by different methods for translucent materials with low extinction *** thermal conductivity obtained from the hot strip method is overestimated at elevated temperature when compared with that from one-dimensional steady state *** order to measure the effective thermal conductivity of translucent materials accurately,the effect of thermal radiation should be considered for different transient methods.

关键词： hot strip method thermal conductivity translucent materials thermal radiation

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关于现场计量标准化的探讨

中国标准化 2024年第6期 152-155页

作者：张虎崔浩南济南市计量检定测试院

针对我国现场计量情况越来越普遍的现状,本文从现场计量的环境条件、工作条件、人员设备等方面出发,分析了如今现场计量存在的特点与难点,阐述了现场计量存在的困难和问题,并通过讨论对现场计量的组织实施、条件控制、结束总结等流程进... 详细信息

针对我国现场计量情况越来越普遍的现状,本文从现场计量的环境条件、工作条件、人员设备等方面出发,分析了如今现场计量存在的特点与难点,阐述了现场计量存在的困难和问题,并通过讨论对现场计量的组织实施、条件控制、结束总结等流程进行标准化管理,尝试将现场计量的全过程形成完整的标准化流程,达到对现场计量中的影响因子进行控制的目的,从而影响整个测量过程与测量结果,减小影响因子带来的不确定度,以保证得到良好可靠的测量结果。

关键词：标准化现场计量流程控制校准结果

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一种新型三电平变换器中点电压平衡调制策略

机车电传动 2024年第2期 43-50页

作者：张虎柴英浩张贵苑国锋变频技术北京市工程研究中心(北方工业大学) 北京100144

在大功率轨道交通装备领域中,三电平变换器因具有众多优点,在实际中得到广泛应用,但是也存在中点电压不平衡这一固有问题。为解决三电平中点箝位(NPC)型变换器存在的中点电压不平衡问题,减少输出相电流畸变情况,提高系统运行稳定性,文... 详细信息

在大功率轨道交通装备领域中,三电平变换器因具有众多优点,在实际中得到广泛应用,但是也存在中点电压不平衡这一固有问题。为解决三电平中点箝位(NPC)型变换器存在的中点电压不平衡问题,减少输出相电流畸变情况,提高系统运行稳定性,文章提出了一种基于分析中点电荷量的双自由度新型中点电压平衡调制策略。该调制策略首先从数学分析的角度介绍了三电平变换器直流侧中点电压不平衡问题的原因;之后分析了在空间矢量脉宽调制(SVPWM)技术中,电压矢量输出序列对中点电压的影响;最后基于上述分析结果,改进传统的电压矢量输出序列,并基于改进序列的特点提出了一种新的双自由度中点电压平衡调制策略,通过双自由度的平衡因子调节作用时间。理论上,所提出的新型调制策略具有更多可控电荷量,相较于传统方法具有更良好的控制效果;仿真和试验结果验证了所提的新型调制策略对中点电压的控制效果具有更好的快速性和稳定性。综上所述,文章所提的新型双自由度调制策略可更有效解决三电平变换器存在的中点电压不平衡问题。

关键词：三电平 NPC变换器空间矢量脉宽调制中点电压平衡平衡因子

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降雨和地震共同作用下高填方边坡稳定性研究

交通科技 2024年第4期 50-55,140页

作者：张虎彭小勇马康贵州省交通规划勘察设计研究院股份有限公司贵阳550081

为研究降雨和地震共同作用对高填方边坡稳定性影响,利用降雨时长、降雨强度,以及地震加速度3个主要因子进行叠合分析,基于GeoStudio数值软件进行稳定性分析计算,并采用正交试验法对因素敏感性进行评价。结果表明,降雨主要影响边坡浅层... 详细信息

为研究降雨和地震共同作用对高填方边坡稳定性影响,利用降雨时长、降雨强度,以及地震加速度3个主要因子进行叠合分析,基于GeoStudio数值软件进行稳定性分析计算,并采用正交试验法对因素敏感性进行评价。结果表明,降雨主要影响边坡浅层土体孔隙水压力,降雨强度和时间对高填方边坡稳定性影响程度有限;地震作用对边坡稳定影响很大,边坡稳定系数随地震峰值加速度增大而降低;降雨和地震共同作用下,填方边坡稳定性明显小于降雨或地震单一作用,叠合作用效果明显;在考虑的边坡稳定性影响因素中,地震作用影响最大,降雨时间次之,降雨强度最小。

关键词：高填方边坡降雨地震稳定性数值分析正交试验

Adropin as an indicator of T2DM and its complications

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Food Science and human Wellness 2022年第6期11卷 1455-1463页

作者： hu zhang Ning Chen Graduate School Wuhan Sports UniversityWuhan 430079China Tianjiu Research and Development Center for Exercise Nutrition and Foods Hubei Key Laboratory of Exercise Training and MonitoringCollege of Health ScienceWuhan Sports UniversityWuhan 430079China

Type 2 diabetes mellitus(T2 DM)is one of metabolic diseases with the major inducer of *** to the change in lifestyle and dietary structure,more and more people are being suffered from T2 ***,the prevention and treatment of T2 DM and its complications has become an urgent problem to be *** a secreted peptide,adropin is identifi ed as a useful regulator associated with insulin sensitivity and energy *** has the potential for regulating metabolic diseases including obesity and T2 *** should be noted that the secretion of adropin can be induced by diets,aerobic exercise and other *** this article,the underlying mechanisms of adropin for regulating obesity,T2 DM and its complications including diabetic nephropathy,diabetic retinopathy,diabetic encephalopathy,diabetic vascular disease and diabetic cardiovascular disease were ***,the strategies for promoting the secretion of adropin were also discussed,which will provide a target for the prevention and targeted treatment,or a candidate of novel and effective functional food or drug for metabolic diseases in the future.

关键词： Adropin Metabolic disease Obesity T2DM Diabetic complications

Antibacterial,antioxidant and antiproliferation activities of essential oils and ethanolic extracts from Chinese mugwort(Artemisia vulgaris L.)leaf in Shanxi

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Traditional Medicine Research 2024年第1期9卷 47-56页

作者： hu-Tan-Xian zhang Feng-Ru Lyu Jia-Tong He Chen-Yu Liu Zheng-Yang Zhou Rui-Jie Wu Zi-Qing Zhao He Li School of Chemistry and Chemical Engineering North University of ChinaTaiyuan 030051China Shanxi Jinshuo Biomedical Technology Co. Ltd.Jinzhong 030600China

Background:Artemisia vulgaris,a medicinal aromatic plant,is widely used as a food item,tonic pharmaceutical,and cosmetic industry additive owing to its antibacterial,antihypertensive,hepatoprotective,antioxidant,and antispasmodic *** the effect of different geographic locations on the chemical composition and bioactivities of its extracts is ***:Biological activities of essential oils and ethanol extracts of three varieties of Artemisia vulgaris leaves,which are grown in Shanxi province China,were ***:Gas chromatography-mass spectrometry analysis revealed that the main components of essential oils were terpenes and *** oils and ethanol extract of Artemisia vulgaris leaves possessed good antioxidant activities,and their half maximal inhibitory concentrations determined using 1,1-diphenyl-2-picrylhydrazyl and 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate)assays were 57.0 and 22.9μg/mL,*** essential oils also exhibited remarkable antibacterial activity against three foodborne pathogenic bacterial *** ethanol extract presented a high anticancer activity against the MGC-803 human gastric cancer cell ***:These biological activities were well correlated with the composition of the extract and EOs,which in turn is affected by the genetic composition of Artemisia vulgaris and geographic location and diverse climatic condition under which it is *** findings demonstrate the remarkable potential of Artemisia vulgaris as a valuable source of antioxidant,antibacterial,and anticancer agents.

关键词： Artemisia vulgaris essential oils ethanol extracts antioxidant antiproliferation

手足十二针联合强制性运动疗法治疗脑梗死偏瘫的临床疗效及其对患者日常生活活动能力的影响

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实用心脑肺血管病杂志 2024年第4期32卷 112-115页

作者：韩伟张虎张春荣于磊北京市中医院顺义医院康复科 101300

目的探究手足十二针联合强制性运动疗法治疗脑梗死偏瘫的临床疗效及其对患者日常生活活动能力的影响。方法选取2022年2月—2023年2月北京市中医院顺义医院收治的脑梗死偏瘫患者120例,采用随机数字表法将其分为对照组和观察组,每组60例... 详细信息

目的探究手足十二针联合强制性运动疗法治疗脑梗死偏瘫的临床疗效及其对患者日常生活活动能力的影响。方法选取2022年2月—2023年2月北京市中医院顺义医院收治的脑梗死偏瘫患者120例,采用随机数字表法将其分为对照组和观察组,每组60例。对照组患者接受强制性运动疗法,观察组患者在对照组基础上接受手足十二针治疗,两组患者疗程均为4周。比较两组患者临床疗效及治疗前后Berg平衡量表(BBS)评分、Fugl-Meyer运动功能评估量表(FMA)评分、神经营养因子〔神经生长因子(NGF)和脑源性神经营养因子(BDNF)〕、Barthel指数(BI)。结果治疗4周后,观察组患者临床疗效优于对照组(Z=2.237,P=0.025)。治疗后,两组患者BBS、FMA评分分别高于本组治疗前,且观察组患者BBS、FMA评分高于对照组(P<0.05)。治疗后,两组患者NGF、BDNF分别高于本组治疗前,且观察组患者NGF、BDNF高于对照组(P<0.05)。治疗后,两组患者BI分别高于本组治疗前,且观察组患者BI高于对照组(P<0.05)。结论手足十二针联合强制性运动疗法能有效提高脑梗死偏瘫患者的临床疗效、平衡能力及运动能力,促进脑神经功能恢复,进而提高患者的日常生活活动能力。

关键词：脑梗死偏瘫手足十二针强制性运动疗法治疗结果日常生活活动

Morphological Heredity of Intermetallic Nb_(5)Si_(3)Dendrites in Hypereutectic Nb-Si Based Alloys via Non-Equilibrium Solidification

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Chinese Journal of Mechanical Engineering 2022年第5期35卷 393-400页

作者： Yueling Guo Lina Jia Wenjun Lu hu zhang School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Research Center of Light‑alloy Materials Frontier Institute of Science and Technology InnovationBeihang UniversityBeijing 100191China Max-Planck-Institut für Eisenforschung Max‑Planck‑Straße 140237 DüsseldorfGermany

For hypereutectic Nb-Si based alloys,primary Nb_(5)Si_(3)phases typically grow in a faceted mode during equilibrium or near-equilibrium solidification,which damages the ductility and *** address this issue,here we artificially manipulate the growth morphology of Nb_(5)Si_(3)using electron beam surface melting(EBSM)and subsequent annealing *** show that such a non-equilibrium solidification pathway enables the transition from faceted growth to non-faceted dendritic growth of Nb_(5)Si_(3),along with evident microstructure refinement,generation of metastableβ-Nb_(5)Si_(3)phases and elimination of chemical *** transformation fromβ-Nb_(5)Si_(3)toα-Nb_(5)Si_(3)and Nb solid solution(Nbss)particles is triggered by the annealing treatment at 1450°C for 5 ***,we find the annealing-mediated formation of inherited Nb_(5)Si_(3)dendrites that maintain the dendritic morphology of the original as-solidifiedβ-Nb_(5)Si_(3)*** work thus provides a feasible routine to obtain thermally stable and refinedα-Nb_(5)Si_(3)dendrites in hypereutectic Nb-Si based alloys.

关键词： Nb-Si alloy Intermetallics Nb_(5)Si_(3) Rapid solidification Dendritic growth

Radiative properties of alumina/aluminum particles and influence on radiative heat transfer in solid rocket motor

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Chinese Journal of Aeronautics 2022年第2期35卷 98-116页

作者： Xuefan HAO hu zhang Xiao HOU Guihua TANG State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’an 710049China Shaanxi Key Laboratory of Environment and Control for Flight Vehicle Xi'an Jiaotong UniversityXi’an 710049China College of Astronautics Northwestern Polytechnical UniversityXi’an 710072China Key Laboratory of Thermo-Fluid Science and Engineering Ministry of EducationXi’an Jiaotong UniversityXi’an 710049China

The thermal radiation of micron-sized condensed phase particles plays a dominant role during the heat transfer process in aluminized Solid Rocket Motors(SRMs).Open research mainly focuses on the radiative properties of alumina particles while the study considering the presence of aluminum is *** addition,the thermal radiation inside the SRM with consideration of the participating particles is seldom *** this work,the multiscale method of predicting the thermal environment inside SRMs is established from the particle radiation at microscale to the twophase flow and heat transfer at *** effective gray radiative properties of individual particles(alumina,aluminum,and hybrid alumina/aluminum)and particles cloud are investigated with the Mie theory and approximate *** a numerical method for predicting the thermal environment inside SRMs with considering particle radiation is established and applied in a subscale *** convective and radiative heat flux distributions along inner wall of motor are obtained,and it is found that the heat transfer in the combustion chamber is dominated by thermal radiation and the radiative heat flux is essentially a constant of 5.6–6.8 MW/m^(2).The convective heat transfer plays a dominant role in the nozzle and the heat flux reaches the maximum value of 11.2 MW/m^(2) near the *** the combustion efficiency of aluminum drops,the radiative heat flux remains unchanged in most regions and increases slightly along the diverging section wall of the nozzle.

关键词： Alumina Aluminum Condensed phase particle Radiative heat transfer Radiative properties Solid rocket motor