共查询到19条相似文献,搜索用时 78 毫秒
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激光诱导间质肿瘤热疗的数值模拟和实验研究 总被引:1,自引:0,他引:1
本文在考虑生物组织物性动态变化的情况下建立了激光诱导间质肿瘤热疗(LITT)的物理数学模型,采用MonteCarlo方法数值模拟了LITT中激光能量在生物组织内的传输过程,基于Pennes生物传热方程和Arrhenius方程数值求解了组织内的温度分布和热损伤体积的变化,分析了热物性及血液灌注率的动态变化对LITT过程的影响,并与相应的离体实验结果进行了对比。数值模拟结果表明,组织的热物性及血液灌注率的动态变化对于热损伤体积的变化具有重要的影响。因此在激光诱导间质肿瘤热疗的数值模拟中应该考虑热物性及血液灌注率的动态变化以期为临床治疗方案的制定提供更为准确的依据。 相似文献
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生物传热基本方程的研究 总被引:11,自引:0,他引:11
本文分析了已有的生物传热基本方程,采用多孔体模型导出了相应的基本方程,在此基础上,分析了生物组织的有效参数与骨架组织和血流参数之间的关系,这为测量在体组织热物性提供了有希望的前景。本文利用所提出的生物传热模型,按Pennes原文采用的数据资料对人臂径向温度分布进行了试算。结果表明,该模型相当适合Pennes原实验测试记录。 相似文献
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现场测量深层岩土热物性方法 总被引:31,自引:1,他引:30
地下岩土的热物性参数是地源热泵地热换热器的设计中所需要的很重要的参数。热物性参数的大小对钻孔的数量及钻孔的深度具有显著的影响,进而影响地源热泵系统的初投资。为了能够在现场测量地下岩土的热物性参数,本文利用一套现场测量设备测量了对地下埋管回路施加的热流与回路中循环水温度随时间的变化,并利用参数估计方法确定地下岩土的热物性参数。 相似文献
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用扫描热显微镜测量微小区域热导性质的探讨 总被引:3,自引:1,他引:2
随着高新技术的迅速发展,许多研究对象已进入亚微米和纳米范畴。在对这些对象的热性能和热可靠性的研究中,亚微米尺度的热物性测量已成为关键技术之一。例如:在微电子、微电子机械系统(MEMS)领域中,已使用纳米量级厚度的材质和做出纳米尺度线宽的器件。在材料科学、生物学、医学和化学等许多领域,高空间分辨率下的热物性测量也具有重要意义。本文经过实验;初步用扫描热显微镜判定了微小区域材料热导性质的差别,并从理论上探讨了用该仪器测量微小区域热导性质的方法原理。 相似文献
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光动力治疗中热效应的理论分析与计算 总被引:4,自引:3,他引:1
基于Pennes传热方程,从理论上分析了光动力治疗中激光作用所引起的组织温升的变化.结果表明,激光照射在生物组织内形成热源,该热源在一维生物组织空间引起组织的温升一般随时间呈指数形式增大,随激光照射处的距离呈指数减少.激光照射生物组织产生热效应,存在一个最小阈值光剂量,仅当照射的激光剂量大于阈值光剂量时,才能产生热效应.阈值光剂量大小由生物组织的光学参量和热物性参量决定,并随激光照射处的距离呈指数增加 相似文献
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The most challenging objective in the electronic industries is to develop materials that demonstrate a tunable thermal property with today's microelectronic devices. The development of composite material with balanced thermal properties is highly appreciated and currently competing the traditional monolithic conductive material. However, the tailored thermal properties of the composite are significantly influenced by the composites constituents and their fabrication routes. This article presents a review of thermal properties of particulate as well as fiber-reinforced composite proportional to matrix microstructure, reinforcement architecture. The processing techniques used to fabricate composites have been addressed with an objective to achieve suitable thermal properties. The developments in the analytical and numerical simulation approach to predict the thermal conductivity and CTE of the developed composites have been critically reviewed. Lastly, future work needs attention is summarized. 相似文献
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The thermal isolation properties of porous silicon photonic crystal structures have been designed and discussed theoretically.
Excellent thermal isolation properties can be obtained on such a porous silicon photonic crystal, even better than that of
porous silicon with high porosity. Due to the excellent thermal isolation properties of the porous silicon photonic crystal
structures, they can be used as the thermal isolation substrates in infrared detectors 相似文献
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Tian-Yu Wang 《中国物理 B》2021,30(12):128101-128101
In addition to electrical insulation properties, the thermal properties of nanodielectrics, such as glass transition temperature, thermal expansion coefficients, thermal conductivity, and mechanical properties, including Young's modulus, bulk modulus, and shear modulus, are also very important. This paper describes the molecular dynamics simulations of epoxy resin doped with SiO2 nanoparticles and with SiO2 nanoparticles that have been surface grafted with hexamethyldisilazane (HMDS) at 10% and 20% grafting rates. The results show that surface grafting can improve certain thermal and mechanical properties of the system. Our analysis indicates that the improved thermal performance occurs because the formation of thermal chains becomes easier after the surface grafting treatment. The improved mechanical properties originate from two causes. First, doping with SiO2 nanoparticles inhibits the degree of movement of molecular chains in the system. Second, the surface grafting treatment weakens the molecular repulsion between SiO2 and epoxy resin, and the van der Waals excluded region becomes thinner. Thus, the compatibility between SiO2 nanoparticles and polymers is improved by the grafting treatment. The analysis method and conclusions in this paper provide guidance and reference for the future studies of the thermal and mechanical properties of nanodielectrics. 相似文献
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《中国物理 B》2019,(8)
Surface charges can modify the elastic modulus of nanostructure, leading to the change of the phonon and thermal properties in semiconductor nanostructure. In this work, the influence of surface charges on the phonon properties and phonon thermal conductivity of GaN nanofilm are quantitatively investigated. In the framework of continuum mechanics,the modified elastic modulus can be derived for the nanofilm with surface charges. The elastic model is presented to analyze the phonon properties such as the phonon dispersion relation, phonon group velocity, density of states of phonons in nanofilm with the surface charges. The phonon thermal conductivity of nanofilm can be obtained by considering surface charges. The simulation results demonstrate that surface charges can significantly change the phonon properties and thermal conductivity in a GaN nanofilm. Positive surface charges reduce the phonon energy and phonon group velocity but increase the density of states of phonons. The surface charges can change the size and temperature dependence of phonon thermal conductivity of GaN nanofilm. Based on these theoretical results, one can adjust the phonon properties and temperature/size dependent thermal conductivity in GaN nanofilm by changing the surface charges. 相似文献
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雪作为衡量全球气候变化有效的信息源之一,其热辐射存在偏振特性,且这一偏振特性会受到多因素的影响。为了定量分析单一因素及其交互作用对雪的热辐射偏振特性的影响,在传统分析的基础上,设计了三因素三水平的正交实验。结果表明,探测角、方位角和波段均对雪的热辐射偏振特性产生影响;探测角对雪的热辐射偏振度产生显著的影响;探测角与其他两因素的交互作用以及波段均对雪的热辐射偏振度产生显著影响;方位角对雪的热辐射偏振度有一定的影响,而它与波段的交互作用不会对雪的热辐射偏振度产生影响。因此,在研究中,既要考虑单因素本身对雪的热辐射偏振特性的影响,还要考虑交互作用的影响。 相似文献
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Theoretical calculations have predicted that individual Single-Walled Carbon Nanotubes (SWNT) have extremely high thermal
conductivity (around 6.6 × 104 W/m-K). The feasibility of constructing practical devices using the above mentioned properties, is critically dependent on
the ability to synthesize high-thermal-conducting films. Highly conducting films would be of great use as heat sinks for the
next generation of integrated chips. Excessive heating is currently a very serious problem in the endeavor for achieving faster
and smaller chips. Since it is still not possible to perfectly align SWNT in the macroscopic scale, the thermal properties
of the nano-films are therefore expected to have a statistical effect and thus lower than the intrinsic thermal conductivity
of a single nanotube. Also the thermal conductivity perpendicular to the tube direction is more significant from a practical
point of view. Multi-Walled Carbon Nanotubes (MWNT) were synthesized by Chemical Vapor Deposition (CVD) technique and subsequently
characterized. The thin MWNT films were deposited by a solution casting technique over a metallic substrate. The off-axis
thermal properties of these nano-films were studied by AC-calorimetry studies. In this method, the sample is heated by an
AC source and the measurement of the relaxation rate is used to determine the thermal properties. This technique is well established
for studying the thermal properties of complex fluids. Our results are contrasted with other thermal conductivity measurements
intrinsic and bulk carbon nanotube samples. We have also measured off-axis thermal properties of nano-films synthesized from
more crystalline SWNT samples and have compared this result with that of the MWNT-film. A model to explain the thermal conduction
for our system is proposed.
George Muench: Presently at the Department of Physics, University of New Haven, West Haven, CT-06516, USA 相似文献
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Laser performance and thermal lensing in high-power diode-pumped Yb:KGW with athermal orientation 总被引:1,自引:0,他引:1
J.E. Hellström S. Bjurshagen V. Pasiskevicius 《Applied physics. B, Lasers and optics》2006,83(1):55-59
A comparative, experimental study of the high-power diode-pumped laser performance and thermal lensing properties between
standard b-cut Yb:KGW and Yb:KGW cut along an athermal direction is presented. The results show that thermal lens properties
in both the b-cut and the athermal direction-cut crystals are determined by anisotropic thermal expansion in Yb:KGW. Thermal
gradients due to the pump beam cause thermal lensing even in the athermal direction-cut geometry. The thermal lens is much
weaker and less astigmatic in the athermal direction-cut crystal, for the same absorbed power. These properties allow generation
of better-quality laser beams with the athermal direction-cut crystal as compared to the b-cut crystal.
PACS 42.55.Xi; 42.60.Jf; 42.70.Hj 相似文献