Thermal Conductivity and Heat Transfer Coefficient of Concrete

A very simple model for predicting thermal conductivity based on its definiensis was presented. The thermal conductivity obtained using the model provided a good coincidence to the investigations performed by other authors. The heat transfer coefficient was determined by inverse analysis using the temperature measurements. From experimental results, it is noted that heat transfer coefficient increases with the increase of wind velocity and relative humidity, a prediction equation on heat transfer coefficient about wind velocity and relative humidity is given.

Electrical Conductivity of Spark Plasma Sintered W-Cu and Mo-Cu Composites for Electrical Contact Applications

Tungsten copper and molybdenum copper composites, with weight percent copper in the range of 20% - 40%, have been produced using the spark plasma sintering (SPS) technique. Other specimens having similar compositions were also developed using the conventional techniques of Liquid Phase Sintering (LPS) and Infiltration. Electrical conductivity measurements showed that the specimens produced by the SPS process had substantially higher levels of electrical conductivity than those produced by the other methods. Relative density measurements showed that the SPS specimens achieved very high densification, with relative densities in the range of 99.1% - 100%. On the other hand, the specimens produced by LPS and infiltration had relative densities in the range of 88% - 92% and 96% - 98% respectively. The superior conductivity of the SPS specimens has been attributed to the virtually full densification achieved by the process. The effect of porosity on electrical conductivity has been discussed and three standard models were assessed using results from porous sintered skeletons of pure tungsten and pure molybdenum.

Measurement and temperature effect on soil thermal conductivity in Changchun area

The study on soil thermal conductivity (STC) was an important side of research on ground source heat pump technique,geological disposal of high-level radioactive wastes,heat distribution of buried cable. Especially owing to technical requirement for shallow terrestrial heat recently, it directly influenced the design and solution in engineering problems. The authors measured the STC in the studied area with QTM-D2 and discussed the effect of samples in size, the measurement error between the samples in lab and in site. The results indicate measuring STC by heat pole method with less influence upon the samples in size, and measuring results on the different geometry size approach very much. The STC is fit for the empirical relation between the temperature and TC under the condition of normal temperature. It is significance for understanding STC in northern China and simulation of temperature field.

气象观测场在汽车试验场中的应用研究

汽车试验场作为汽车开展道路测试的重要场所,用于验证汽车产品的品质以及可靠性。除了场地道路外,气象条件作为汽车道路测试的重要一环,在《GB/T12534-1990汽车道路试验方法通则》中也有明确要求,如:试验时应是无雨无雾天气,相对湿度小于95%,气温0-40℃,风速不大于3m/s。同时气象条件也作为试验场道路管控的重要依据,实时风速、雨量、能见度等信息为场地管理者发布限速、限行、封场等通知提供必要参考依据,直接影响道路测试安全管控的及时性。因此,文章从气象观测场的建设、气象服务、异常天气道路管控等方面开展气象观测场在汽车试验场中的应用研究。

Thermoelastic waves in helical strands with Maxwell–Cattaneo heat conduction

Harmonic thermoelastic waves in helical strands with Maxwell–Cattaneo heat conduction areinvestigated analytically and numerically. The corresponding dispersion relation is a sixth-orderalgebraic equation, governed by six non-dimensional parameters: two thermoelastic couplingconstants, one chirality parameter, the ratio between extensional and torsional moduli, the Fouriernumber, and the dimensionless thermal relaxation. The behavior of the solutions is discussedfrom two perspectives with an asymptotic-numerical approach: (1) the effect of thermal relaxationon the elastic wave celerities, and (2) the effect of thermoelastic coupling on the thermal wavecelerities. With small wavenumbers, the adiabatic solution for Fourier helical strands is recovered.However, with large wavenumbers, the solutions behave differently depending on the thermalrelaxation and chirality. Due to thermoelastic coupling, the thermal wave celerity deviates from theclassical result of the speed of second sound.

Response of stomatal conductance of two tree species to vapor pressure deficit in three climate zones

Stomatal behavior is a central topic of plant ecophysiological research under global environmental change. However, the physiological mechanism controlling the response of stomata to vapor pressure deficit （VPD） or relative humidity （RH） has been inadequately understood till now. In this study, responses of stomatal conduc- tance （gs） to VPD in two species of trees （Fraxinus chinensis Roxb., Populus alba L. var. pyramidalis Bge.）in three different climate zones （Jinan with typical warm humid/semi-humid climate, Urumqi with temperate continental arid climate and Turpan with extreme arid desert climate） were measured. Levels of two phytohormones （abscisic acid, ABA; indole-3-acetic acid, IAA） in the leaves of the two tree species at these three sites were also measured by high performance liquid chromatography. The results showed that the responses of gs to an increasing VPD in these two tree species at the three sites had peak curves which could be fitted with a Log Normal Model （gs=a.exp（-O.5（In（DIc）lb）2）. The VPD/RH values corresponding to the maximum g, can be calculated using the fitting models for the two tree species in the three sites. We found that the calculated g, -VPD correlated nega- tively with relative air humidity in the three sites during the plant growth period （April to October 2010）, which showed the values of g,-max-VPD were related to the climate conditions. The prevailing empirical stomatal model （Leuning model） and optimal stomatal behavior model could not properly simulate our measured data. The water use efficiency in the two tree species did not show obvious differences under three very different climatic conditions, but the highest gs, photosynthetic and transpiration rates occurred in P. alba var. of Turpan. The sensitivity in re- sponse of g~ to VPD in leaves of the two trees showed positive correlations with the concentration of ABA, which implied that ABA level could be used as an indicator of the sensitivity of stomatal response to VPD. Our results confirmed that the prediction of the response of gs to VPD might be incomplete in the two current popular models. Therefore, an improved g, model which is able to integrate the results is needed. Also, the stomatal response mechanism of single peak curves of g~ to VPD should be considered.

经导管主动脉瓣植入术后发生传导阻滞的预测研究

目的探讨经导管主动脉瓣植入(TAVI)治疗重度主动脉瓣狭窄术后出现心脏传导阻滞的预测因素。方法回顾性病例对照研究。纳入2018年7月至2022年3月在福建省立医院心内科行TAVI术且术后1周内新发的传导阻滞23例作为研究组,将同期相匹配的行TAVI术且未发生心脏传导阻滞的37例作为对照组。比较两组一般临床资料、超声心动图、影像学参数、TAVI术中相关资料。多元logistic回归分析发生心脏传导阻滞的相关因素。结果研究组无冠瓣钙化体积显著高于对照组[(366.2±25.8)mm^(3)比(206.2±23.9)mm^(3),t=4.502,P=0.005],瓣膜植入的深度大于对照组[(5.9±0.7)mm比(3.3±0.6)mm,t=4.520,P=0.001],球囊后扩张比例高于对照组(95.7%比21.6%,χ^(2)=3.217,P=0.047)。采用多元logistic回归分析显示,无冠瓣钙化体积(OR=3.235,95%CI:2.121~12.161,P=0.005)、瓣膜植入深度(OR=2.212,95%CI:1.256~7.361,P=0.023)和球囊后扩张(OR=1.243,95%CI:1.056~2.526,P=0.031)均是发生心脏传导阻滞的相关因素。结论无冠瓣钙化体积、瓣膜植入的深度及球囊后扩张与TAVI术后发生心脏传导阻滞明显相关。

易筋经导引联合益气健脾补肾方治疗肺癌术后癌因性疲乏临床研究

目的:观察易筋经导引联合益气健脾补肾方治疗肺癌术后癌因性疲乏(CRF)肺脾气虚证的临床疗效。方法:选取76例肺癌术后CRF肺脾气虚证患者,按密闭信封法随机分为治疗组和对照组各38例。研究期间,治疗组剔除3例、脱落1例,最终纳入34例,对照组剔除5例、脱落1例,最终纳入32例。治疗组给予易筋经导引联合益气健脾补肾方治疗,对照组仅给予益气健脾补肾方治疗,2组均治疗2个月。比较2组治疗前后多维度疲乏症状量表-简表(MFSI-SF)、肺癌患者生存质量测定量表(FACT-L)评分及细胞免疫功能。结果:治疗后,2组一般疲乏、情绪疲乏、身体疲乏、心理疲乏评分及疲乏总分均较治疗前降低,活力评分均较治疗前升高,差异均有统计学意义(P<0.05);治疗组一般疲乏、身体疲乏、心理疲乏评分及疲乏总分均低于对照组(P<0.05),活力评分高于对照组(P<0.05);2组情绪疲乏评分比较,差异无统计学意义(P>0.05)。2组生理状况(PWB)、情感状况(EWB)、功能状况(FWB)、肺癌相关症状(LCS)评分,总分,以及治疗组社会/家庭状况(SWB)均较治疗前升高,治疗组PWB、EWB、FWB、LCS评分及总分均高于对照组,差异均有统计学意义(P<0.05);2组SWB评分比较,差异无统计学意义(P>0.05)。治疗组血清CD3^(+)水平改善情况优于对照组,差异有统计学意义(P<0.05)。2组CD4^(+)/CD8^(+)值及血清自然杀伤细胞(NK)水平改善情况比较,差异均无统计学意义(P>0.05)。结论:易筋经导引联合益气健脾补肾方治疗能有效缓解肺癌术后CRF肺脾气虚证患者的临床症状,提高其生活质量和细胞免疫功能。

Three Dimensional Coupling between Elastic and Thermal Fields in the Static Analysis of Multilayered Composite Shells

This new work aims to develop a full coupled thermomechanical method including both the temperature profile and displacements as primary unknowns of the model.This generic full coupled 3D exact shell model permits the thermal stress investigation of laminated isotropic,composite and sandwich structures.Cylindrical and spherical panels,cylinders and plates are analyzed in orthogonal mixed curved reference coordinates.The 3D equilibrium relations and the 3D Fourier heat conduction equation for spherical shells are coupled and they trivially can be simplified in those for plates and cylindrical panels.The exponential matrix methodology is used to find the solutions of a full coupled model based on coupled differential relations with respect to the thickness coordinate.The analytical solution is based on theories of simply supported edges and harmonic relations for displacement components and sovra-temperature.The sovra-temperature magnitudes are directly applied at the outer faces through static state hypotheses.As a consequence,the sovra-temperature description is assumed to be an unknown variable of themodel and it is calculated in the sameway as the three displacements.The final systemis based on a set of coupled homogeneous differential relations of second order in the thickness coordinate.This system is reduced in a first order differential relation system by redoubling the number of unknowns.Therefore,the exponential matrix methodology is applied to calculate the solution.The temperature field effects are evaluated in the static investigation of shells and plates in terms of displacement and stress components.After an appropriate preliminary validation,new benchmarks are discussed for several thickness ratios,geometrical data,lamination sequences,materials and sovra-temperature values imposed at the outer faces.Results make evident the accordance between the uncoupled thermo-mechanical model and this new full coupled thermo-mechanical model without the need to separately solve the Fourier heat conduction relation.Both effects connected with the thickness layer and the related embedded materials are included in the conducted thermal stress analysis.

Experimental study on the influence of temperature and humidity on the thermal conductivity of building insulation materials

At present,thermal conductivity is usually taken as a constant value in the calculation of building energy con-sumption and load.However,in the actual use of building materials,they are exposed to the environment with continuously changing temperature and relative humidity.The thermal conductivity of materials will inevitably change with temperature and humidity,leading to deviations in the estimation of energy consumption in the building.Therefore,in this study,variations in the thermal conductivity of eight common building insulation materials(glass wool,rock wool,silica aerogel blanket,expanded polystyrene,extruded polystyrene,phenolic foam,foam ceramic and foam glass)with temperature(in the range of 20-60°C)and relative humidity(in the range of 0-100%)were studied by experimental methods.The results show that the thermal conductivity of these common building insulation materials increased approximately linearly with increasing temperature with maxi-mum growth rates from 3.9 to 22.7%in the examined temperature range.Due to the structural characteristics of materials,the increasing thermal conductivity of different materials varies depending on the relative humidity.The maximum growth rates of thermal conductivity with humidity ranged from 8.2 to 186.7%.In addition,the principles of selection of building insulation materials in different humidity regions were given.The research re-sults of this paper aim to provide basic data for the accurate value of thermal conductivity of building insulation materials and for the calculation of energy consumption.

规范论视域下身份犯的行为不法内涵与类型

身份犯并不保护所谓真正“特别法益”,也并未创设特别法益的保护规范,只创设了保护一般法益的特别举止规范。身份犯的不法内涵,在于违反了特别主体资格附加的作为义务。基于违反的义务类型,可将身份犯分为违反制度性作为义务的身份犯、违反法益保护特别义务的身份犯以及附属于一般不法的身份犯。不同类型的身份犯,遵循各自由一般举止规范到具体作为义务的衍化机制。在身份犯中确定正犯,遵循与所有不法判断一样的教义学基础。在有身份者参与共同犯罪的场合,应以具体犯罪中行为人是否违反、违反何种法益保护(作为)义务导致法益侵害结果的实现,以及违反的义务强度,共同作为犯罪参与者行为不法的判断标准。

“支付结算型”帮助信息网络犯罪活动罪的行为认定问题

支付结算型帮助信息网络犯罪活动行为的认定存在诸多争议,其根源于对支付结算行为的误读和对行为特征的理解偏差。支付结算行为的实质特征是货币资金的转移,转账、套现、取现等行为才应被视为帮助信息网络犯罪活动罪中的支付结算帮助。该罪兼具共犯性与独立性的特征,应对行为作类型化处理,将其分为合作型支付结算帮助行为与协作型支付结算帮助行为。合作型支付结算帮助行为不具中立性,但因其成立依附于正犯的犯罪链条而具有共犯性特征。协作型支付结算帮助行为具有独立性和“积量构罪”的特征。以此为基础,通过细化不同类型的客观行为与主观“明知”认定标准,有助于构建完善的网络犯罪规制体系。

电导率结合质量法测定沿海地区盐渍化土壤水溶性盐含量的可行性研究——以东营市为例

为实现对盐渍化土壤含盐量的快速准确测定,以东营市为例,对盐渍化土壤水溶性盐含量(y,g/kg)与浸提液电导率(EC,μs/cm,x)的相关性进行了分析,得到回归关系式为y=0.0035x-0.1076(r=0.9952),二者相关性达到了极显著水平;在此基础上,对电导率结合质量法批量测定盐渍化土壤水溶性盐含量的可行性进行了分析验证,结果表明,东营市区域内含盐量为1.0~24.1 g/kg或EC为260~6590μs/cm的盐渍化土壤,采用电导率结合质量法测定结果与质量法测定结果的相对偏差符合《森林土壤水溶性盐分分析》(LY/T 1251—1999)“全盐量(质量法)与离子总量之间的允许偏差”规定。提出的电导率结合质量法对我国沿海地区盐渍化土壤水溶性盐含量的批量快速检测具有一定的参考价值。

公司关联关系主体信义义务的衡平规则解析

公司关联关系主体的信义义务源自于信义法。公司所有权与控制权分离所产生的利益冲突驱动着公司法的发展,特别是对公司关联关系主体的信义义务提出了更高的要求。信义义务的功能之一是遏制公司关联关系主体榨取公司潜在价值的交易行为,为公司治理确立了道德规范,也为阻却公司关联关系主体获取非法利益的机会主义行为提供了路径选择。不当得利这一教义规则在商法领域,是针对公司机会主义及其类似问题构建的强制性信义义务和法律推定的命令与禁止的规则体系。这是公司关联关系主体信义义务属于衡平规则的理性法律论证。

Properties and microstructure of Cu/diamond composites prepared by spark plasma sintering method

Cu/diamond composites have been considered as the next generation of thermal management material for electronic packages and heat sinks applications. Cu/diamond composites with different volume fractions of diamond were successfully prepared by spark plasma sintering（SPS） method. The sintering temperatures and volume fractions（50%, 60% and 70%） of diamond were changed to investigate their effects on the relative density, homogeneity of the microstructure and thermal conductivity of the composites. The results show that the relative density, homogeneity of the microstructure and thermal conductivity of the composites increase with decreasing the diamond volume fraction; the relative density and thermal conductivity of the composites increase with increasing the sintering temperature. The thermal conductivity of the composites is a result of the combined effect of the volume fraction of diamond, the homogeneity and relative density of the composites.

Study on Physiological Characteristics of Three Different Cold-resistant Tomato Strains

[Objective]The aim was to study cold-resistant indexes and physiological characters of three different cold-resisitant tomato strains selected under natural conditions. [Method]With 3-4 weeks tomato seedlings as tested materials,through simulating external environment conditions by the cold treatment in lab,the survival ratio and growth status of seedlings were identified; by studying the morphological change of in vitro leaves after cold treatment and determining the relative conductivity,the cold-resistant degree of different tomato strains was identified and the correlation between conductivity and survival rate was analyzed; the variation of soluble sugar and praline content in plant of tomato was determined under the condition of cold stress. [Result]The results showed that leaf morphological changes,size of conductivity and growth status of different tomato strains after cold treatment have significant differences; the variation of soluble sugar contents in plant has significant differences,while the variation of proline content has no significant differences. [Conclusion]There is a certain correlation between conductivity and survival rate under cold treatment conditions,and plant cold tolerance is related to accumulation of soluble sugar content.

Effects of water stress on Haloxylon ammodendron seedlings in the desert region of Heihe inland river watershed, Gansu Province, China

The water relation and leaf gas exchange of saxoul (Haloxylon Ammodendron Bge, a C4 shrub) seedlings were studied under water stress in 2001. Saxoul seedlings maintained high transpiration when the soil moisture was above 11%. The seedlings were able to take up water from soil with above 6 % soil water content, which was the threshold level of soil moisture for seedlings. The relationship between transpiration and potential evaporation was linear for well-watered seedlings. The de-crease of soil water availability led to different degrees of down-regulation of stomatal conductance, leaf transpiration and net CO2 assimilation rate. The stomata played a relatively small part in determining the net CO2 assimilation rate for the same seedling. The relationship between net CO2 assimilation rate and transpiration was linear diurnally, and reduction scale of leaf transpiration was much bigger than that of net CO2 assimilation rate by waters tress treatments, therefore intrinsic wa-ter-use-efficiency increased. High evaporative demand increased the leaf transpiration but inhibited net CO2 assimilation rate. Because of the effect of VPD on transpiration in this region, the transpiration of well-watered and mild water stress seedlings becomes responsive to change in stomatal conductance over a wider range.

岩土热导率测量和温度影响研究

利用QTM-D2常温导热系数测定仪测定了典型砂、黏土、岩石的导热特性,探讨了室内外试验、试样饱和程度对测量结果影响,通过试验结果和数值模拟研究了不同试样导热系数的尺寸差异,为现场岩土材料导热系数的测定提出了可行的解决方案。热线法测量时,试件尺寸影响范围不大,不同几何尺寸边界的测量结果很接近。根据国内外对导热系数的温度影响问题的研究实际,通过大量的实测数据和数值理论计算,总结了常温条件范围内各类岩土材料导热系数与温度之间的经验关系以及它们的温度变异影响系数β。各类岩土材料的β值普遍较小,大多在10-3的数量级上,导热系数与温度关系曲线近线性。该系数和这些经验公式的导出对中国北方地区岩土材料导热性能的理解及温度场模拟工作均具重要意义。

单轴压力对高密度聚乙烯/碳黑导电复合材料电阻特性的影响

研究了高密度聚乙烯 /炭黑导电复合材料在单轴压力作用下电阻的变化规律 .结果表明 ,在低压力下 ,复合材料电阻随压力增加而降低 ;而在较高压力下则随压力增大而升高 ,分别呈现出所谓的“电阻负压力系数”和“电阻正压力系数”效应 .电阻的压力依赖性以及由压缩引起的电阻不可回复性 ,被认为与外力作用下导电网络的重组与破坏有关 .由此提出了导电复合材料单轴压力作用

干热河谷9种造林树种在旱季的水分关系和气孔导度

对元谋干热河谷人工混交林中 9个树种叶片的水势、饱和渗透势、气孔导度、渗透调节和季节变化进行了测定 ,同时对树高和胸径也进行了比较。水分生理特征表明 :1 )随着旱季的深入 ,除刺槐 (Robiniapseudoacacia)、黄荆 (Vitexnegundo)、滇榄仁 (Terminaliafranchetii)落叶外 ,其余常绿树种叶片的气孔导度、水势和饱和渗透势都呈下降的趋势 ,在最旱的三、四月份 ,它们适应干旱的方式有 4种 :①低水势、气孔导度近似关闭的厚荚相思 (Acacialepto carpa)、大叶相思 (A .auriculiformis)和肯氏相思 (A .cunninghamii) ;②低水势、低气孔导度的赤桉 (Eucalyptusdulebsis)、娟毛相思 (A .holosericea)和车桑子 (Dodonaeawiscosa) ;③较高水势、低气孔导度的柠檬桉 (Eucalyptuscitriodora)和新银合欢 (Leucaenaleucocephala) ;④较高水势、气孔导度近似关闭的马占相思 (Acaciamangium)。 2 )在干旱胁迫过程中 ,主要渗透调节物质出现的先后顺序是K+ 、游离脯氨酸、游离氨基酸和可溶性糖 ,K+ 和可溶性糖贡献最大 ,分别在干旱的前后期起渗透调节作用 ,游离脯氨酸和游离氨基酸在干旱的中期起渗透调节作用。