基于神经元电响应的人体热舒适性评价理论

本文提出一种利用神经元电响应频率定量评价人体热舒适性的理论方法和准则。利用Hodgkin-Huxley方程和Pennes生物传热方程描述皮下神经元在瞬态温度场下的电响应特性,并研究了环境温度、对流换热系数,血液灌注率和组织导热率等参数对它的影响,结果表明神经元动作电位频率在等效温度发生0.1℃时就会发生明显变化,可以组合多个环境和热物性参数评价人体热舒适性。     

考虑冷热刀刀头温度响应对制定肿瘤治疗计划的影响

本文对冷热联合治疗肿瘤过程中在体生物组织的温度响应进行了深入的数值研究。组织被当作非理想材料,在一定的温度范围内冷冻和融化,并且考虑了未冻结组织和未损伤组织区域的血液灌注及代谢产热的影响。对比考虑和不考虑冷热刀刀头温度响应两种情形的计算结果表明,拟定治疗计划中若不考虑刀头温度响应,则有可能会造成冷热剂量的不足,从而无法彻底杀灭肿瘤。     

基于三点法的柱状生物组织热特性参数估计

针对柱状生物活体组织,提出了通过测量组织表面三个测量点的温度变化,同时确定多个热特性参数的新的非稳态无损测量方法。基于Pennes生物传热方程,建立了描述三点法测量系统传热过程的数学模型,进行了正问题的求解。根据数值计算以及参数灵敏度分析的结果,采用改进的高斯方法,对生物活体组织的热特性参数估计进行了模拟计算及分析。结果表明,采用三点测温同时确定活体生物组织的导热系数、血液灌注率、综合换热系数的测量方法是有效和可行的。     

激光诱导间质肿瘤热疗的数值模拟和实验研究

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。     

正常和嵌合肿瘤乳腺温度分布特征的有限元分析

基于乳腺解剖学结构和生理学特征,建立了适合应用于正常和嵌合肿瘤乳腺三维热传递的分析模型.该模型综合考虑了乳腺代谢产热、血液灌注和动静脉血管与乳腺组织之间的热交换等因素对温度场的影响.数值研究了正常和嵌合肿瘤乳腺的温度分布特征,着重分析代谢产热、血液灌注率、乳腺肿瘤的大小、位置与数目以及空气对流系数、环境温度等因素对乳腺温度分布的影响.结果表明:血液灌注率、代谢产热、乳腺肿瘤的大小、位置与数目对乳腺温度分布特征的影响明显;环境条件对嵌含肿瘤乳腺的体表温度分布影响较大.研究结果将有助于指导乳腺红外热图像的实验并为其定性分析提供重要的参考.     

基于热传导模型的血流灌注率无损量测研究

建立了多层皮肤组织的热传导模型,利用有限元方法对模型进行了求解分析,发现当在皮肤组织表面进行常热流量加热时皮肤组织表面最终恒定温度和血流灌注率的大小有关,利用ExpAssoc函数进行拟合得到了二者之间的关系曲线,并且根据此关系曲线设计了血流灌注率无损量测装置,对人体皮肤组织的血流灌注率进行了量测,发现测量结果与计算结果趋势一致,并且和其他文献报道的结果吻合度较高。此方法简单有效,也可应用于其它生物组织血流灌注率的无损量测.     

人体腿部四层结构的红外热成像有限元分析

为研究人体红外热成像和体内肿瘤热源的关联,本文构建了包括骨层、肌肉层、脂肪层、皮肤层的人体腿部有限元模型。根据体内温度沿径向分布的特点,给出了各区域内动脉血液灌注热生成率随径向坐标变化的情况,解决了有限元建模中动脉血灌注热生成率随温度变化的非线性问题。进而用有限元方法数值计算了不同尺寸和不同深度的体内肿瘤所带来的温度变化。结果表明：在所研究的肿瘤尺寸范围内,肿瘤尺寸越小,体内温度提升越高,体表的峰值温度越高,体表温度分布半峰宽越窄,温度变化越陡峭。对于特定尺寸的肿瘤,肿瘤越深,体内峰值温度越高,体表的峰值温度越低,体表温度分布半峰宽越宽,温度变化越平缓。     

人体腿部四层结构的红外热成像有限元分析（英文）

为研究人体红外热成像和体内肿瘤热源的关联,本文构建了包括骨层、肌肉层、脂肪层、皮肤层的人体腿部有限元模型。根据体内温度沿径向分布的特点,给出了各区域内动脉血液灌注热生成率随径向坐标变化的情况,解决了有限元建模中动脉血灌注热生成率随温度变化的非线性问题。进而用有限元方法数值计算了不同尺寸和不同深度的体内肿瘤所带来的温度变化。结果表明:在所研究的肿瘤尺寸范围内,肿瘤尺寸越小,体内温度提升越高,体表的峰值温度越高,体表温度分布半峰宽越窄,温度变化越陡峭。对于特定尺寸的肿瘤,肿瘤越深,体内峰值温度越高,体表的峰值温度越低,体表温度分布半峰宽越宽,温度变化越平缓。     

测量组织局部血液灌注率的表面热干扰法

1日u云去正常的血液灌注是机体组织重要的生理要素之一，组织所需的氧、营养和药物靠灌注的血液来运输供应。心肌缺血（即冠心病）是当前困扰人们的发病率高的严重疾病之一。脑对血液的供应则更是敏感，脑血管的局部栓塞将导致局部脑组织缺血甚至坏死。因此，组织灌注状况的检测不仅对于生理和病理研究是重要的，对临床医学也是十分重要的。事实上，某些非缺血性疾病的治疗（例如癌瘤的热疗）过程也直接或间接地涉及到组织的灌注率。寻求一种测量组织灌注率的方法一直是人们孜孜以求的。近年来，各种测量方法的研究已有相当的发展山，其中热…     

低温绝热压力容器蒸发率测试方法分析

蒸发率是评价低温绝热压力容器绝热性能的一项重要指标。文中在总结多年来开展低温绝热压力容器蒸发率测试经验和数据的基础上,从内容器温度平衡时间、环境温度变化、环境大气压力变化、流量计测量管径大小、测试场地振动等角度,分析了外界因素对蒸发率测试结果的影响规律,为正确开展蒸发率测量提供了操作方法,为后续标准的修订提供了数据支撑,可以方便测试者精确掌握被测产品绝热性能指标。     

光动力治疗中热效应的理论分析与计算

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     

A numerical simulation of photothermal response in laser medicine

In this paper, we reported a numerical solution of laser induced thermal effect in the bio-tissue. The model of photothermal effect and classical Pennes bio-heat transfer equation were introduced. Finite element method (FEM), which was realized by Matlab software, was used to calculate the temperature distribution. He-Ne laser (633 nm) was used to simulate the physical therapy in in vivo skin tissue. Under the cylinder coordinates, the three-dimension(3-D) geometry of tissue was reduced to two-dimension(2-D)computation. The results contained the radial, axial and temperature 3-D color plot. Combining the time animation display was possible. By changing the laser and tissue parameters we can get different results.This will be the initial and indispensable work of the non-destructive evaluation of the laser induced injury.     

Estimation of temperature elevation generated by ultrasonic irradiation in biological tissues using the thermal wave method

In most previous models,simulation of the temperature generation in tissue is based on the Pennes bio-heat transfer equation,which implies an instantaneous thermal energy deposition in the medium.Due to the long thermal relaxation time τ(20 s-30 s) in biological tissues,the actual temperature elevation during clinical treatments could be different from the value predicted by the Pennes bioheat equation.The thermal wave model of bio-heat transfer(TWMBT) defines a thermal relaxation time to describe the tissue heating from ultrasound exposure.In this paper,COMSOL Multiphysics 3.5a,a finite element method software package,is used to simulate the temperature response in tissues based on Pennes and TWMBT equations.We further discuss different factors in the bio-heat transfer model on the influence of the temperature rising and it is found that the temperature response in tissue under ultrasound exposure is a rising process with a declining rate.The thermal relaxation time inhibits the temperature elevation at the beginning of ultrasonic heating.Besides,thermal relaxation in TWMBT leads to lower temperature estimation than that based on Pennes equation during the same period of time.The blood flow carrying heat dominates most to the decline of temperature rising rate and the influence increases with temperature rising.On the contrary,heat diffusion,which can be described by thermal conductivity,has little effect on the temperature rising.     

脉冲激光烧蚀块状靶材的双动态界面研究

给出脉冲激光作用块状靶材的烧蚀模型.根据能量平衡原理,导出烧蚀面的位置随时间的变化关系.利用绝热近似、温度连续性条件和能量平衡原理来获得烧蚀面与固液相界面边界条件.结合热传导方程,利用精确解与积分近似法相结合的方案,给出固液两相的温度分布与时间和位置的变化关系,以及固液相界面的位置随时间的变化规律,并与已有的理论和实验结果进行比较.最后以铝靶为例计算模拟了激光烧蚀的全过程计算. 关键词： 脉冲激光 等离子体 固液相界面 烧蚀面     

Simulation of continuous terahertz wave transient state thermal effects on static water

We report a numerical simulation of continuous terahertz beam induced transient thermal effects on static water. The terahertz wave used in this paper has a Gaussian beam profile. Based on the transient heat conduction equation, the finite element method (FEM) is utilized to calculate the temperature distribution. The simulation results show the dynamic process of temperature change in water during terahertz irradiation. After about 300 s, the temperature reaches a steady state with a water layer thickness of 5 mm and a beam radius of 0.25 mm. The highest temperature increase is 7 K/mW approximately. This work motivates further study on the interaction between terahertz wave and bio-tissue, which has a high water content.     

Heating of a sample with a laser pulse

The transient temperature associated with the bulk absorption of a rectangular laser pulse in a solidstate sample of finite size is calculated analytically and analyzed. Radiation is incident on the frontal surface with an arbitrary surface thermal conductivity. The opposite surface is thermostatically controlled and maintained at a constant equilibrium temperature. The general solution is obtained for pulses of arbitrary duration. The pulse duration is determined with respect to the relaxation time of the nonstationary thermal diffusion (it is the characteristic time of the problem). The limiting cases of the adiabatic insulation and isothermal contact at the frontal surface are considered, and the criteria for surface and bulk light absorption are derived for both cases. The temperature distributions are numerically simulated and examined for long and short pulses, as well as for different values of the light absorption coefficient and the surface thermal conductivity of the frontal surface.     

Finite temperature contributions to the renormalized energy-momentum tensor for an arbitrary curved space-time

The finite temperature contributions to the effective Lagrangian and energy-momentum tensor in the cases of scalar and spinor fields are evaluated by means of the Green's function method. The results are obtained in an arbitrary curved space-time by adiabatic expansions of the Green's functions.We would like to thank professor D. Ivanenko for support of our work and many stimulating discussions.     

Properties of an adiabatically cooled SK spin glass

Some physical properties of an SK spin glass subject to slow cooling are investigated. Among those are Edwards-Anderson order parameter, energy, field cooled and zero field cooled susceptibilities. The results are compared with predictions from Parisi's solution. Different values are obtained for the field cooled susceptibility whereas other quantities are identical in both calculations. Ultrametricity results in a natural way if adiabatic temperature changes involving cooling and heating periods are considered. Some results are also given for adiabatic cooling in a finite external field and for adiabatic changes of the field at constant temperature. The present setup allows to investigate explicitly the dependence on history at least for adiabatic changes of temperature and external field.     

部分充液贮箱自由液面塌陷的数值研究

本文利用基于有限体积法的VOF方法模拟部分充液贮箱中液体的输送过程,根据数值计算结果可以获得出流过程中贮箱自由液面塌陷夹气时的液面高度和液面塌陷的过程,将数值计算结果和试验结果进行了比较,验证了该方法的有效性。通过对计算结果进行分析,本文获得了液面塌陷时流场特征和塌陷原理,为防塌陷装置的设计提供指导。