支持这项工作由海军研究办公室（N000141210603）和陆军研究办公室（W911NF1010381）深表感谢。来自美国国家科学基金会（CBET-0931290，CMMI-0926704，和CBET-0932573）的部分支持这项工作也承认。

1。实验过程<ol><li>收集样品。在这项工作中，人的头发样本是从一个30岁的健康的亚洲女性的收集。 </li><li>暂停两个铜电极之间的样品， 如图1A所示 。应用银糊剂在样品电极接触，以减少热和电的接触电阻到可以忽略的水平。 </li><li>使用显微镜做样品的初步检查，并确保该银膏也不会污染悬浮样品。 </li><li>因为人体头部的头发样本不导电的，涂层具有非常薄的一层金膜（〜40nm）的样品的外面，使其具有导电性。 </li><li>将样品在真空室中，并将其泵至1-3毫乇。 </li><li>喂养的工序直流电流通过样品引入电加热和感应电压-时间（V - t）的更新将通过使用示波器进行记录。 </li&gt; <li>得到的样品出腔室和外套它与另一薄层金膜（〜40nm）的，并重复步骤1.5和1.6。 </li><li>准备新的样品具有不同的长度，并重复步骤1.2-1.7。 </li><li>使用扫描电子显微镜（SEM）表征样品（长和短的）的长度和直径。 </li></ol> 2。数据处理第一正常化实验温度升高，并通过使用样品的热扩散率不同试验值进行的，该理论拟合。此过程在郭的详细工作1讨论。然后减去的辐射损失和寄生传导的热扩散的影响，并计算热导率。细节在下面给出。 <ol><li>确定有效的热扩散系数 在TET实验设置的示意图如图1A所示。在测量中，进料的工序的电流通过样品诱导焦耳加热。使用示波器来记录的感应电压-时间（V - 吨 ），其是在图1B的配置文件。有多快/慢温度的升高是由两个竞争的过程决定:一个是焦耳加热，另一种是来自样品的热传导到电极上。样品的更高的热扩散将导致更快的温度变化，即在较短的时间内达到稳定状态。因此，瞬态电压/温度变化可以用来确定热扩散率。当测定样品的热扩散率，没有真正的升温是必要的。事实上，只有根据该电压增加的归一化温度上升被使用。该过程用于确定热扩散率和热导率概述如下。 <ol><li>简化的热量传递到一维:取试样中沿一维传热<html>轴向移动。注意:该线的长度必须比其直径要长很多。更多详细信息可参阅郭的工作1。 <ol><li>求解归一化的温升（T *，也被称为空间平均温度在整个样品）在样本为使用下列公式的一维传热问题: <img alt="1" fo:content-width="1.8in" height="46" src="/files/ftp_upload/51144/51144_clip_image002.gif" width="260" /> （1） α和L是样品的热扩散系数和长度。 </li><li>求解归一化温度升高的电压变化（V 线 ）录得的示波器，并进行数据拟合，以确定热扩散率。在导线上的电压有关，其温度为: 0"/&gt;（2） R 0是样品加热前的电阻， 余电流通过样品和k的导热率。Q 0是每单位体积的电加热功率。很显然，所测量的电压变化是固有地关联到该样品的温度变化。的归一化温度上升T *根据实验数据判断可以计算为T * EXP =（V 线 - V 0）/（V 1 - V 0），其中V 0和V1 顷穿过的初始和最终电压样品（ 如图1B）。获得T * EXP后，用α不同的试验值来计算的理论T *通过应用公式1和拟合实验重sults（T * EXP）。利用MATLAB编程来通过应用最小二乘拟合技术比较实验值和理论值，并取该值给出的T * EXP最适合作为样品的热扩散率。 </li></ol></li></ol></li><li>减去的辐射损失和气体传导的影响 在TET热特性，的辐射损失的影响可能是显著如果样品具有非常大的纵横比（L / D，D:试样的直径），特别是对低导热率的样品。此外，如果真空室中的压力不是很低，热量传递到空气会影响测量到一定的程度。从样品表面辐射的热传递率可以表示为: <img alt="" fo:content-width="3.1in" height="29" src="/files/ftp_upload/51144/51144_clip_image002_0001.gif" width="390" /> ，（3） 磨片重ε是样品的有效发射率，A S的表面积，T的表面的温度，T 0的环境（真空室）的温度，θ= T - T 0在大多数情况下，θ&lt;&lt;波 0 ，则: <img alt="" fo:content-width="1.05in" height="23" src="/files/ftp_upload/51144/51144_clip_image002_0002.gif" width="138" /> （4） 通过将面辐射和气体传导到身体冷源，对样品的传热控制方程变为: <img alt="" fo:content-width="2.25in" height="49" src="/files/ftp_upload/51144/51144_clip_image002_0003.gif" width="345" /> ，（5） 其中 h为气体传导系数。在我们的物理模型中，由于电极是比样品大得多，具有优异的热传导，将样品的温度是在室温下进行一t为接触。因为θ（X，T）= T（X，T） - T 0，边界条件是θ（0，T）=θ（L，T）=θ（X，0）= 0。 以公式（5）的解决方案是: <img alt="" fo:content-width="3.5in" src="/files/ftp_upload/51144/51144_clip_image002_0004.gif" width="489" /> （6） 在这里，f的定义为- （16εδT0 3 / D +4 H / D）L 2 /π2 K，这是无量纲的。它是一种类型的Biot数，其大小表示从样品的两侧的热损失量。结合这个方程沿x方向和平均温度可以得到: <img alt="" fo:content-width="3in" src="/files/ftp_upload/51144/51144_clip_image002_0005.gif" width="408" /> （7） 因此，归一化大道愤怒的温度是: <img alt="" fo:content-width="4.2in" src="/files/ftp_upload/51144/51144_clip_image004_0005.gif" width="510px" /> （8） 经过仔细的数值和数学的研究中，与αEFF =α（1 - F），T *可以近似为 <img alt="" fo:content-width="2.2in" height="48" src="/files/ftp_upload/51144/51144_clip_image008.gif" width="288" /> （9） 数值计算已进行了研究上述近似的精度。请注意，当f为小于0时，在整个过渡状态下的最大绝对差值小于0.014（ 图2中示出）。最后: <img alt="" fo:content-width="1.7in" height="50" src="/files/ftp_upload/51144/51144_clip_image010.gif" width="218" /> （10） 因为实验是在非常低的压力（1-3毫乇）在真空室中进行，该气体传导的影响（ 小时）是可以忽略不计<html> BLE。所以简化公式10为: <img alt="" fo:content-width="1.4in" height="49" src="/files/ftp_upload/51144/51144_clip_image012.gif" width="173" /> （11） 这个公式表明，使用TET技术测量热扩散具有与辐射损失（4εσT0 3）的效果线性关系。使用这样的理论背景，以减去的辐射损失和气体传导的影响。 </li><li>确定真正的热扩散率和电导率 在公式11所确定的热扩散率（α）仍具有寄生传导的效果，如果测试样品上涂有薄金膜。造成涂层的热传输效果可使用威德曼 - 弗兰兹定律可以忽略不计的不确定性中减去。样品的实际热扩散率（α）被确定为1: 在"高度="47"SRC ="/ files/ftp_upload/51144/51144_clip_image002_0006.gif .1"宽度="134"/&gt;，（12） ρCp是基于体积的比热，这可以从校准时，非接触式光热技术或分别测量密度和比热以下方式获得:L 洛伦茨 ，T和A的洛伦兹数，样品的温度和截面积，分别。 因为<img alt="" fo:content-width="2.4in" height="46" src="/files/ftp_upload/51144/51144_clip_image004_0006.gif" width="343" /> ，但很明显，αEFF的与1 / R成线性关系，因此，在该实验中，涂覆1样品与金膜的两倍（这将导致1 / R的变化）和测试两次可通过消除寄生传导的影响曲线拟合。对于实际的热导率K，它可以很容易地通过采用k =ρCp评价45; </li></ol>

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没有什么可以透露。

在实验过程中，三个步骤[步骤2），3）和5）]是用于精确地表征热性能的成功很关键。步骤2）和3），备受关注需要在施加银膏只在样品电极接触支付。这是很容易污染的悬浮​​样品用银膏，和热性质将增加，如果发生这种情况。因此，在步骤3）中，检查样品与显微镜仔细，如果任何污染，银膏施加或延伸至悬浮样品被注意到的，一个新的样本需要进行的实验制备。 当式（10）简化为式（11）中，假定该实验是在真空室中以非常低的压力（1-3毫乇）进行的，所以该气体传导效果是微不足道的。做了一系列的测试在不同的压力后，可以确认的是，在公式10中，气体的行为离子系数 h正比于压力p为h =γP。系数γ是关系到一个叫做热协调系数反映的能量耦合/交换系数，当气体分子撞击材料表面参数。γ可以计算为ξπ2DρcP /（4L 2）其中，ξ是斜率对压力的热扩散系数γ的变化从样品到样品。该气体传导系数可以强烈影响，在TET表征该材料的表面结构和空间配置在腔室中。步骤5），进行实验在非常低的压力（1-3毫托）将确保这个复杂的气体传导效应可以忽略不计。 通过这种技术测量的样品的表面发射率（ε），也可以计算无线TH基于体积的比热（ρCP），它可以从校准获得，非接触式光热技术或13-15分别测量密度和比热的给定值。减去寄生传导的影响后，在图6所示的热扩散率（α+实弧度 ）仅具有辐射损失的影响， <img alt="" fo:content-width="2in" height="60" src="/files/ftp_upload/51144/51144_clip_image002_0011.gif" width="342" /> 。这是很容易知道: <img alt="" fo:content-width="1.7in" height="59" src="/files/ftp_upload/51144/51144_clip_image004_0010.gif" width="244" /> （13） 这里波 0为室温，L被测样品的直径，并且D中的样品的直径。 有在TET技术的一些局限性。一，特性时间ΔtC为日ermal运输 样品，相当于0.2026 L 2 /α1，应该比上升时间电流源（约2微秒）大得多。否则，电压变化的精度将会显著影响。因此，它要求样品长度 L不宜太小或热扩散系数α应该不会太大。第二，将样品的温度将约20-30°的实验上升。在此范围内，样品的电阻应该具有对温度的线性关系。这是因为，在理论背景的一部分，它是已知的测得的电压的变化是固有地关联到该样品的温度变化。如果样品的电阻值不必温度成线性关系，电压变化不能忍受的温度变化。第三，将样品的电压应具有线性关系的直流电流在实验期间喂食。这意味着，在一定的温度时，电阻也不会改变的直流电流的变化，当。这是众所周知，半导体就没有这个属性。 最后，该TET技术是一种非常有效和有力的方法来测量各种材料的热性能。对于相同的材料，只是测试两个样品具有不同的长度各两次，材料，如热扩散系数，导热性，和表面发射率（如果ρCp被给出）的所有重要的热性能，可被表征。

在TET技术图1是开发来测量固体材料的热扩散率，包括导电，半导电或不导电的一维结构的有效方法。在过去，单丝3ω方法2-4和微制造装置的方法5-9已经开发了在微/纳米尺度来衡量的1维结构的热性能。为了拓宽材料（导电和不导电）的测量范围，提高了精度和稳定性，瞬态电热（TET）技术已发展为微/纳米线的热物性的表征。该技术已成功地用于自由站立微米厚的聚（3 -己基噻吩）薄膜10的热特性，薄膜的锐钛矿相TiO 2纳米纤维11，单壁碳纳米管1，微/ submicroscale由聚丙烯腈导线12，和蛋白质纤维。消除（如果样品是涂有一层金，使其电子导电）和辐射损失寄生传导的影响后，实际的热扩散率可以得到。那么真正的热导率可以计算基于体积的比热（ρCP），它可以从校准时，非接触式光热技术，或者分别测量密度和比热来获得一个给定的值。

<table><tbody><tr><td>Digital Phosphor Oscilloscope</td><td>Tektronix</td><td>DPO 3052</td><td>&amp;nbsp;</td></tr><tr><td>Sputter Coater</td><td>Denton Vacuum</td><td>DESK V</td><td>&amp;nbsp;</td></tr><tr><td>AC and DC Current Source</td><td>Keithley</td><td>Model 6221</td><td>&amp;nbsp;</td></tr><tr><td>Laboratory Microscope</td><td>Olympus</td><td>BX41</td><td>&amp;nbsp;</td></tr><tr><td>Dual Stage Rotary Vane Vacuum Pump</td><td>Varian</td><td>DS102</td><td>&amp;nbsp;</td></tr><tr><td>Vacuum Chamber</td><td>Huntington Mechanical Laboratories</td><td>Customized Product</td><td>The pressure in the chamber should be as low as 1-3 mTorr when working with the vacuum pump</td></tr><tr><td>Colloidal Silver Liquid</td><td>Ted Pella</td><td>16031</td><td>&amp;nbsp;</td></tr></tbody></table>

characterization of thermal transport in one-dimensional solid materials

在TET（瞬态电 - 热）的技术是开发来测量固体材料的热扩散率，包括导电，半导电或不导电的一维结构的有效方法。这种技术拓宽材料（导电和非导电）的测量范围，提高了精确度和稳定性。如果样品（特别是生物材料，诸如人的头发，蜘蛛丝，和蚕丝）是不导电的，但将涂覆有金层，使电子导电。可以在数据处理过程中被减去寄生传导和热扩散率的辐射损失的效果。那么真正的热导率可以计算基于体积的比热（ρCP），它可以从校准时，非接触式光热技术或分别测量密度和比热来获得给定的值。在这项工作中，人的头发样本是使用d，来说明如何设置该实验中，处理实验数据，并减去寄生传导和辐射损失的效果。

拟合实验数据对人头部的头发样品1（长度0.788毫米，涂有金膜仅一次）示于图3。其热扩散率是在1.67×10 -7米2 /秒，它包括辐射损失和寄生传导的影响来确定。 图4是人的头发的典型SEM图像。中，短和长的样品都涂有金膜两次，并测试了两次分别根据公式12，寄生传导的效果，可以很容易地通过曲线拟合中减去， 如图5。其中拟合曲线相交的αEFF-轴的交点为αEFF的价值 当电阻是无穷大，即寄生传导的公式12中的效果是0。两个人的头发样本，不同长度进行测量，以获得两个相交。关于EXP详情erimental条件和测量结果列于表1。通过结合这两点，αEFF的关系 和L 2 / D可以被揭示。从测得的双（α1，L 1 2 / D 1）和（α2，L 2 / D 2），线性外推法（如在图6中示出），完成对L = 0的点（意味着没有的辐射损失在该点有效），并且热扩散系数为1.42×10 -7米2 /秒[=α1 - （α1 - α2）* L-1 2 / D 1 /（L 1 2 / D 1 - L 2 / D 2）]。此值反映了热DIF样品fusivity无辐射损失和寄生传导的效果。 对人的头发，密度为特征的加权几缕头发和测量其体积，并测得在1100千克/米3。比热是通过使用DSC（差示扫描量热法）测定，并测量在1.602千焦/千克K.所以真正的热传导率为0.25W /实验参数和结果对人类头发样品1米K.细节和图2是如表1所示。 <img alt="图1" fo:content-width="6in" fo:src="/files/ftp_upload/51144/51144fig1highres.jpg" src="/files/ftp_upload/51144/51144fig1.jpg" width="500px" /> 图1。 A）原理的TET实验设置和B）一个典型的V-T曲线。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51144/51144fig1highres.jpg" target="_blank">ç</a><html>舔这里查看大图。 <img alt="图2" fo:content-width="6in" fo:src="/files/ftp_upload/51144/51144fig2highres.jpg" src="/files/ftp_upload/51144/51144fig2.jpg" width="500px" /> 图2。 T *和它的近似使用公式9之间的差异。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51144/51144fig2highres.jpg" target="_blank">点击这里查看大图</a> 。 <img alt="图3" fo:content-width="6in" fo:src="/files/ftp_upload/51144/51144fig3highres.jpg" src="/files/ftp_upload/51144/51144fig3.jpg" width="500px" /> 图3。为归一化的温度上升与时间的关系（人的头发样品1）的实验数据和理论拟合结果之间的比较 。&gt;点击这里查看大图。 <img alt="图4" fo:content-width="6in" fo:src="/files/ftp_upload/51144/51144fig4highres.jpg" src="/files/ftp_upload/51144/51144fig4.jpg" width="500px" /> 图4。人类头发的典型的SEM图像 。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51144/51144fig4highres.jpg" target="_blank">点击这里查看大图</a> 。 <img alt="图5" fo:content-width="6in" fo:src="/files/ftp_upload/51144/51144fig5highres.jpg" src="/files/ftp_upload/51144/51144fig5.jpg" width="500px" /> 图5。拟合结果对1 / R热扩散系数的变化对人的头发样品1和2， <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51144/51144fig5highres.jpg" target="_blank">点击此处查看大图</a> 。 图6。拟合结果对人的头发样品的实际热扩散率。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51144/51144fig6highres.jpg" target="_blank">点击这里查看大图</a> 。 <table border="0" cellpadding="0" cellspacing="0" width="473"><colgroup><col /><col /><col /></colgroup><tbody><tr height="52"><td height="52" style="height:52px;width:249px;">人的头发样本</td><td style="width:111px;">示例1 （短） </td><td style="width:115px;">样品2 （长） </td></tr><tr height="21"><td height="21" style="height:21px;">长度（mm） </td><td> 0.788 </td><td style="width:115px;"> 1.468 </td></tr><tr height="21"><td height="21" style="height:21px;">直径（mm） </td><td> 74.0 </td><td style="width:115px;"> 77.8 </td></tr><tr height="25"><td height="25" style="height:25px;"> 真正的α+辐射 （×10 -7米2 /秒） </td><td> 1.48 </td><td style="width:115px;"> 1.62 </td></tr><tr height="25"><td height="25" style="height:25px;"> 真正的 α（×10 -7米2 /秒） </td><td colspan="2"> 1.42 </td></tr><tr height="25"><td height="25" style="height:25px;"> ρC P（×10 6焦耳/米3 K） </td><td colspan="2"> 1.76 </td></tr><tr height="25"><td height="25" style="height:25px;">实际的热导率（W /米K） </td><td colspan="2"> 0.25 </td></tr></tbody></table> 表1:实验参数和结果对人类头发的详细信息。

Watch this Scientific Journal Video about Characterization of Thermal Transport in One-dimensional Solid Materials at JoVE.com

Characterization of Thermal Transport in One-dimensional Solid Materials

该TET（瞬态电热）技术是开发测量固体材料的热扩散率的有效途径。

在一维固体材料的热传输的特性

The TET (transient electro-thermal) technique is an effective approach developed to measure the thermal diffusivity of solid materials, including ...

characterization-thermal-transport-one-dimensional-solid

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17.1K 次观看.  Iowa State University. 该TET（瞬态电热）技术是开发测量固体材料的热扩散率的有效途径。 

视频: Characterization of Thermal Transport in One-dimensional Solid Materials

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma sintering techniques. Polycrystalline ceramics possessing a unique morphology can be achieved by optimizing the process parameters, particularly spark plasma sintering heating rate. The phase and morphology of the synthesized ceramics were investigated in detail using X-ray diffraction, scanning electron microcopy and energy-dispersive X-ray spectroscopy. It was observed that the grains of these bulk Pr-doped SrTiO3 ceramics were enhanced with Pr-rich grain boundaries. Electronic and thermal transport properties were also investigated as a function of temperature and doping concentration. Such a microstructure was found to give rise to improved thermoelectric properties. Specifically, it resulted in a significant improvement in carrier mobility and the thermoelectric power factor. Simultaneously, it also led to a marked reduction in the thermal conductivity. As a result, a significant improvement (> 30%) in the thermoelectric figure of merit was achieved for the whole temperature range over all previously reported maximum values for SrTiO3-based ceramics. This synthesis demonstrates the steps for the preparation of bulk polycrystalline ceramics of non-uniformly Pr-doped SrTiO3.

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

A protocol for the synthesis and processing of polycrystalline SrTiO3 ceramics doped non-uniformly with Pr is presented along with the investigation of their thermoelectric properties.

非均匀掺Pr的SrTiO的合成<sub&gt; 3</sub&gt;陶瓷及其热电性能

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma ...

科研

化学

Experimental Methodology for Estimation of Local Heat Fluxes and Burning Rates in Steady Laminar Boundary Layer Diffusion Flames

Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex interactions occurring at the interface between gas-phase flames and condensed-phase fuels. The current research provides a technique to explore the dynamic relationship between a combustible condensed fuel surface and gas-phase flames in laminar boundary layers. Experiments have previously been conducted in both forced and free convective environments over both solid and liquid fuels. A unique methodology, based on the Reynolds Analogy, was used to estimate local mass burning rates and flame heat fluxes for these laminar boundary layer diffusion flames utilizing local temperature gradients at the fuel surface. Local mass burning rates and convective and radiative heat feedback from the flames were measured in both the pyrolysis and plume regions by using temperature gradients mapped near the wall by a two-axis traverse system. These experiments are time-consuming and can be challenging to design as the condensed fuel surface burns steadily for only a limited period of time following ignition. The temperature profiles near the fuel surface need to be mapped during steady burning of a condensed fuel surface at a very high spatial resolution in order to capture reasonable estimates of local temperature gradients. Careful corrections for radiative heat losses from the thermocouples are also essential for accurate measurements. For these reasons, the whole experimental setup needs to be automated with a computer-controlled traverse mechanism, eliminating most errors due to positioning of a micro-thermocouple. An outline of steps to reproducibly capture near-wall temperature gradients and use them to assess local burning rates and heat fluxes is provided.

We describe the use of micro-thermocouples to estimate local temperature gradients in steady laminar boundary layer diffusion flames. By extension of the Reynolds Analogy, local temperature gradients can be further used to estimate the local mass burning rates and heat fluxes in such flames with high accuracy.

在稳定层流边界层扩散火焰本地热通量和燃烧率的估计实验方法

Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex ...

工程学

<meta charset="utf8"></head><body>一种研究 RMU 温升问题的综合方法

Comparative Study of Simulation of Temperature Rise in Ring Main Unit

The Ring Main Unit (RMU) is a critical device in power distribution systems used for connecting and distributing electricity. However, due to its compact internal structure and high current load, heat dissipation issues are particularly prominent. To address this problem, this study innovatively proposes a simplified RMU model, employing finite element simulation methods to accurately solve for the ohmic losses of conductors under actual operating conditions and obtain ohmic loss data for various components. This is the first in-depth investigation of the RMU's temperature rise problem using such a comprehensive approach. Subsequently, the temperature field was solved using two different temperature field analysis modules, with a detailed comparison and analysis of the simulation results to identify similarities, differences, and trends in temperature distribution. The results indicate that the temperature field solution model, which considers convective heat transfer, is more accurate and aligns with actual operating conditions. This research provides an innovative approach and practical solutions for the design and optimization of RMUs. Future research can further explore multiphysics coupling analysis methods to address structural design and mandatory validation issues for high and ultra-high voltage RMUs and other electrical equipment, thereby providing important insights for engineering design.

<meta charset="utf8"></head><body>作者聚焦：环网柜设备温升的仿真与分析

This paper addresses the temperature rise problem of the ring main unit by establishing a simplified model and conducting a comparative analysis in two temperature field-solving modules.

环网柜温升模拟的比较研究

The Ring Main Unit (RMU) is a critical device in power distribution systems used for connecting and distributing electricity. However, due to its compact ...

模拟双极射频热疗系统对肿瘤的影响

A Computational Modeling Approach to Investigate the Influence of Hyperthermia on the Tumor Microenvironment

The biophysical properties of the tumor microenvironment differ substantially from normal tissues. A constellation of features, including decreased vascularity, lack of lymphatic drainage, and elevated interstitial pressure, diminishes the penetration of therapeutics into tumors. Local&#160;hyperthermia within the tumor can alter microenvironmental properties, such as interstitial fluid pressure, potentially leading to improvements in drug penetration. In this context, multi-physics computational models can provide insight into the interplay between the biophysical parameters within the tumor microenvironment and can guide the design and interpretation of experiments that test the bioeffects of local hyperthermia.
This paper describes a step-by-step workflow for a computational model coupling partial differential equations describing electrical current distribution, bioheat transfer, and fluid dynamics. The main objective is to study the effects of hyperthermia delivered by a bipolar radiofrequency device on the interstitial fluid pressure within the tumor.&#160;The system of mathematical expressions linking electrical current distribution, bioheat transfer, and interstitial fluid pressure is presented, emphasizing the changes in the distribution of the interstitial fluid pressure that could be induced by the thermal intervention.

作者聚焦:计算局部射频热疗干预对肿瘤生物力学的影响

The article describes a protocol to simulate the transient temperature profiles and the coupled spatiotemporal variation of the interstitial fluid pressure following the heating delivered by a dipolar radiofrequency hyperthermia system. The protocol can be used to assess the response of biophysical parameters characterizing the tumor microenvironment to interventional hyperthermia techniques.

一种计算建模方法研究热疗对肿瘤微环境的影响

The biophysical properties of the tumor microenvironment differ substantially from normal tissues. A constellation of features, including decreased ...

生物工程

Quenching and Boiling

Source: Alexander S Rattner, Sanjay Adhikari, and Mahdi Nabil; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA
Controlled heating followed by rapid cooling is an important element of many materials processing applications. This heat-treating procedure can increase material hardness, which is important for cutting tools or surfaces in high wear environments. The rapid cooling stage is called quenching, and is often performed by immersing materials in a fluid bath (often water or oil). Quenching heat transfer can occur due to forced convection - when the action of rapidly moving material through coolant drives the heat transfer process, and due to free convection - when the reduced density of hot fluid near the material surface causes buoyancy-driven circulation and heat transfer. At high material temperatures, the coolant can boil, leading to increased heat transfer effectiveness. However, when extremely hot materials are quenched, they can be blanketed in relatively low thermal conductivity coolant vapor, leading to poor heat transfer.
In this experiment, quenching heat transfer will be measured for a heated copper cylinder, which is representative of small heat-treated parts. The transient sample temperature profile will be measured during quenching and compared with theoretical results for free convection heat transfer. Boiling phenomena will also be investigated qualitatively.

Quenching, Boiling, Convection and Nusselt Number

淬火和沸腾

Source: Alexander S Rattner, Sanjay Adhikari, and Mahdi Nabil; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, ...

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机械工程

Current Density

The total amount of current flowing through one unit value of a cross-sectional area is referred to as current density. If the current flow is uniform, the amount of current flowing through a conductor is the same at all points along the conductor, even if the conductor area varies. The current density consists of the local magnitude and direction of the charge flow, which varies from point to point. Current density is measured in amperes per meter square, and direction is defined as the net flow of positive charges through the area. Also, for any given current, as the diameter of the wire in a circuit increases, the charge density decreases. The magnitude of the current density is the current divided by the area.
<img alt="Equation1" src="/files/ftp_upload/13745/13745_Equation_1.svg" style="text-align: center; height: 28px;" />
<img alt="Equation2" src="/files/ftp_upload/13745/13745_Equation_2v2.svg" style="text-align: center; height: 14px;" />
Thus, the current density can be determined as:
<img alt="Equation3" src="/files/ftp_upload/13745/13745_Equation_3v2.svg" style="text-align: center; height: 22px;" />
If q is positive, drift velocity is in the same direction as the electrical field. If q is negative, drift velocity is in the opposite direction to the electric field. Either way, the direction of the current density is in the direction of the electrical field. For example, in a sodium chloride solution, current can be carried by both positive sodium ions and negative chlorine ions; the total current is found by adding up the currents due to each kind of charged particle.

电流密度

The total amount of current flowing through one unit value of a cross-sectional area is referred to as current density. If the current flow is uniform, ...

在一维固体材料的热传输的特性

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