基于有限元的舌体三维温度场数值模拟

依据生物体自然形态所进行的三维温度场建构与计算是近年来国内外生物传热研究中的焦点之一.采用血管铸型的方法获取猪舌的血管树,通过数码成像及逆向建模将其转换为计算机可识别的数字模型.以Pennes方程为基准方程,对自然形态和实际传热状态下的舌体三维温度场进行了重构计算,并获得成功.通过此方法可获取其它生物体器官三维空间的温度分布,对本研究而言,舌体三维温度场计算的成功为探索生物传热与中医舌诊的机理研究搭建了技术平台.     

MATHEMATICAL ESTIMATION OF PHYSIOLOGICAL DISTURBANCES IN HUMAN DERMAL PARTS AT EXTREME CONDITIONS： ONE DIMENSIONAL STEADY STATE CASE

A mathematical model for the thermoregulation in the dermal layers of the human body is proposed. The skin is composed mainly of three layers — epidermis, dermis and subcutaneous tissues. The relative constancy of the body temperature is remarkable because there is a continuous exchange of heat with the external environment as well as within the different compartments of the body. A model describes the distribution of dermal temperature as a function of internal and external parameters, such as temperature of the incoming arterial blood, blood flow, ambient temperature, and heat exchange with the environment. It is shown that substantial changes in human dermal temperature can be accomplished only through changes in the temperature of the incoming arterial blood or substantial suppression of blood flow. Other parameters can lead only to temperature changes near the skin surface.     

微波诱导生物热传导方程的最优控制问题

用一组方程式描述均匀平板状生物组织的热传导,分析其分布式的最优控制问题,研究该生物组织在肿瘤局部特殊点上达到所必需的温度,通过控制微波,使微波辐射的诱导作用,在手术进程的总时间内,该肿瘤点达到过高热．研究在手术过程不同时间点上生物组织温度与其长度间的依赖关系,使肿瘤达到期望的温度值．     

生物导热基本方程的三维非定常代数显式解析解

对目前比较通用的生物导热基本方程Pennes方程,给出了其三维非定常情况下的代数显式解析解。据知,以前很少有发表过这类严格的几何多维解析解。它除了有不可代替的理论价值外,还可以作为标准解来校验日益发达的数值解以及作为基础来研究计算传热学的数值计算方法。另外,文章的特殊求解方法也有发展价值之处。     

舌模型建构与三维温度场数值模拟初探

舌体的三维温度场的建立可直观反映全舌空间温度的分布情况,能够深层次分析全舌的传热特性。本文选择猪舌为实验研究对象,建构舌体真实血管分布的物理模型为计算机可识别的数字模型,在此基础上用有限元方法对舌体三维温度场的数值模拟做了初步探索。讨论了血管形状分布,血液灌注率,代谢热与生物体三维温度场变化规律的相关性。     

The application of boundary element method in stress analysis of autofretted tube with notch

In this paper, the boundary element method is applied to investigate the internal stale of stress of autofretted tube with notch and the calculated results are important in the practical design.     

基于模拟方法生成血管树的人舌三维温度场数值模拟

采用分步模拟方法生成血管树并以此作为物理模型,进行舌体三维温度场的实验研究与数值计算。计算分为舌体组织和血液温度场数值模拟两部分,相应数学模型也包括舌体组织控制方程、血液控制方程及两者之间的耦合方程。在考虑了血液与组织间的耦合换热,舌津液蒸发的影响基础上,采用数值模拟得到的舌面对流换热系数,使计算结果与红外热像验证极为近似。以模拟方法生成的血管树替代生物体的血管铸型,在某种意义上说将生物体三维传热计算方法的研究推向了一个新的层面。     

Heat transport properties within living biological tissues with temperature-dependent thermal properties

Understanding of the heat transport within living biological tissues is crucial to effective heat treatments. The heat transport properties of living biological tissues with temperature-dependent properties are explored in this paper. Taking into account of variable physical properties, the governing equation of temperature is first derived in the context of the dual-phase-lags model (DPL). An effective method, according to the Laplace transform and a linearization technique, is then employed to solve this nonlinear governing equation. The temperature distribution of a biological tissue exposed to a pulsed heat flux on its exterior boundary, which frequently happens in various heat treatments, is predicted and analyzed. The results state that a lower temperature can be predicted when temperature dependence is considered in the heating process. The contributions of key thermal parameters are different and dependent on the ratio of phase lag and the amplitude of the exterior pulsed heat flux.     

激光诱导间质热疗中生物组织的温度场研究

激光诱导间质热疗疗效评估的前提是必须获得准确的激光在不同功率、不同照射时间的生物组织温度场分布.利用多物理场直接耦合分析软件COMSOL Multiphysics构建了在组织光学参量不变情况下的三维有限元传热模型.该模型基于Pennes生物传热方程和轴对称高斯形状的激光光束热源方程,参量针对离体猪肝组织,考虑到了生物组织热物性密度、比热和热导率随温度变化的情况.仿真获得激光功率为0.77 W、0.95 W、1.23 W,照射时间为10~90 s,径向距离0~2 mm范围和轴向距离0~4 mm范围的温度场数据集.利用拟合算法,获得了自变量为激光功率、照射时间、径向距离和轴向距离的生物组织温度场分布模型.将功率为0.88 W和1.05 W时的结果与Pennes方程结果相比较,两者误差在5%以内.     

Optimal control for bio-heat equation due to induced microwave

A distributed optimal control problem for a system described by a bio-heat equation for a homogeneous plane slab of tissue is analytically investigated. The required tissue temperature at a particular location of the tumour in hyperthermia can be attained within the total operation time of the process due to induced microwave radiation which is taken as control. The tissue temperature against the tissue length at different operation time of the process is considered to attain the desired temperature of the tumor.