基于Bi-LSTM的金属疲劳裂纹涡流脉冲热像技术检测与识别

涡流脉冲热像(Eddy current pulsed thermography,ECPT)技术是一种新型的无损检测方法,广泛应用于金属材料结构的检测,但该技术常依赖人工经验提取特征进行裂纹检测与识别,自动化和智能性化程度不足。结合涡流脉冲热像技术以及循环神经网络(Recurrent Neural Network,RNN)的特性,提出一种基于双向长短期记忆网络(Bidirectional Long Short-Term Memory Network,Bi-LSTM)金属疲劳裂纹涡流脉冲热像分类识别方法。实验通过涡流加热装置对被测金属试件进行感应加热,使用红外热像采集装置对金属平板试件进行实时的数据采集,获得图像序列并制作数据集。运用设计的Bi-LSTM模型增强特征向量中的时序信息,对不同尺寸裂纹的热图像进行训练并测试。实验分析表明,Bi-LSTM网络可有效应用于金属疲劳裂纹检测与识别,针对现有裂纹检测准确率可达到100%,优于传统神经网络和其他深度学习的模型,具有更高的识别精度。

基于红外线热像技术的火灾现场勘察平台

火灾现场勘察的目的包括查明起火原因和火灾性质,查明火灾所造成的经济损失和人员伤亡情况,根据法律法规对火灾责任者进行处理,对研究火源产生的原因、火灾发生的规律、火灾预防和救援工作提供可靠的理论依据。利用现代化的技术手段最大限度地降低火灾发生的概率,对于社会的和谐稳定和人民生命财产安全都有非常重要的作用。随着城市化的持续发展,人口密度不断增加,用电设备越来越复杂,火灾隐患也随之上升,同时造成的危害也越来越大。因此,对于火灾的防范就成为了人们关注的焦点,文章中对基于红外线热像技术的火灾现场勘察平台设计进行了详细分析。

基于热像技术的电力变压器热故障的诊断方法

提出了一种基于变压器表面的红外热像对变压器热故障进行在线诊断的方法。根据变压器的表面温度、结构参数、物性参数和环境温度通过建立其传热模型,对变压器内部热故障温度进行反演计算,并与DGA诊断结果进行比较,证明了该方法的可行性,实现了变压器热故障的非接触、在线诊断。

红外热像技术在材料疲劳研究中的应用

利用红外热像仪可以精确、实时、非接触地测量材料疲劳过程中的温度变化,确定材料的疲劳极限和Whōler曲线。该方法相对于传统的疲劳实验方法,红外热像法具有方便、快捷、低成本等优点,同时红外热像法确定的材料疲劳极限都在工程误差范围内。

基于红外热像技术验证“头项寻列缺”理论

目的:验证列缺穴治疗头项部疾病是否通过表里同治这一作用途径实现。方法:选取甘肃中医药大学健康学生志愿者36例,采用随机数字表法随机分为列缺组和经渠组,每组18例。列缺组针刺受试者单侧列缺穴;经渠组采用与列缺同经且位置相近的经渠穴作为对照点针刺,使用红外热像技术测量两组针刺前后手太阴肺经上穴位(经渠、列缺、孔最、尺泽、天府)和手阳明大肠经上穴位(温溜、手三里、曲池、手五里、臂臑)的温度变化。结果:针刺列缺穴后,手太阴肺经上穴位(经渠、列缺、孔最、尺泽、天府)和手阳明大肠经上穴位(温溜、手三里、曲池、手五里、臂臑)的温度均明显高于针刺前(均P<0.05);针刺经渠穴后,手太阴肺经的穴位温度比针刺前明显上升(均P<0.05),手阳明大肠经的温度差异无统计学意义(均P>0.05)。结论:列缺穴治疗头项疾患可一穴通两经,起到表里同治的作用。

红外线热像技术在女工乳腺疾病筛查中的应用

红外线热像技术是通过在体外确定乳腺温度变化，以非接触无创伤技术来判断乳腺疾患的方法。近年来我院将红外线热像技术用于妇女乳腺疾病普查，收到良好效果，现介绍如下。

红外热像方法在针灸和经络研究中的应用

本文从红外线热成像原理、医学热像检测方法和检测机制,以及应用红外热像技术进行的针灸和经络研究三个方面作了介绍。其中第一部分简单介绍了红外线的性质、红外线辐射的探测和红外热成像的工作原理。第二部分对体表温度的形成、医学热像的检测方法、医学热像应用的范围等进行了扼要介绍。第三部分介绍了国内和作者单位应用红外热像方法进行的针灸原理和经络现象的部分研究工作及结果,包括:(1)针灸作用原理研究。(2)经络温度特性的观察。(3)针刺治疗面瘫效果的观察。(4)针刺手法的观察。(5)穴位温度特性的观察。

捻转补泻手法针刺合谷穴对其局部皮肤温度的影响

阐明针刺捻转补法与泻法的操作是否存在效应上的差异,并探讨其效应差异是否为补泻效应的差异。方法:应用红外线热像技术,采用不同的捻转补泻手法针刺健康人合谷穴后,观察其在即刻,10、20、30min,对局部皮肤温度的影响。结果:不同捻转补法与泻法的操作存在着不同程度的效应差异,其中补法可以使皮温升高,泻法可以使皮温降低,以石氏捻转补泻针法较为明显。结论:1)补泻手法,补法和泻法的操作可产生不同的效应。2)不同捻转补泻手法对皮肤温度产生的升降效应为补泻效应,其中以石氏捻转补泻手法最为明显。3)证明补泻手法实施的必要性。

捻转补泻手法针刺足三里穴对脘腹部皮肤温度的影响

目的 :阐明针刺捻转补法与泻法的操作是否存在效应上的差异 ,并探讨其效应差异是否为补泻效应的差异。方法 :应用红外线热像技术 ,采用不同的捻转补泻手法针刺健康人足三里后 ,观察其在即刻、10、20、30min ,对脘腹部皮肤温度的影响。结果 :不同捻转补法与泻法的操作存在着不同程度的效应差异 ,其中补法可以使皮温升高 ,泻法可以使皮温降低 ,以石氏捻转补泻针法较为明显。结论 :1)补泻手法 ,补法和泻法的操作可产生不同的效应。2)不同捻转补泻手法对皮肤温度产生的升降效应为补泻效应 ,其中以石氏捻转补泻手法最为明显。3)证明补泻手法实施的必要性。

Determination of Thermal Properties of Cuts and Residue Streams Obtained in the Molecular Distillation Process

A real-time sensing of the molecular distillation process temperature by a FLUKE brand thermograph Ti50 IR FlexCam and thermography technique was realized. After completion of the molecular distillation, three properties of heat transport chain cuts and residues obtained in the process were estimated by Differential Scanning Calorimetry （DSC） （specific heat, enthalpy, thermal conductivity）. These properties are of great importance for improving oil characterization and for future modeling and simulation of the molecular distillation process. The results show that through the method of Differential Scanning Calorimetry, profiles have been obtained from the variation of specific heat, enthalpy and thermal condutivity as a function of temperature for samples of cuts from the distillation （ASTM D-2892） and fractions of distillate and residue from the process of molecular distillation.

Infrared measurement of temperature field in coal gas desorption

In order to reveal the temperature change in coal gas desorption process,the temperature variation in coal gas desorption process under different particle sizes is analyzed with infrared thermal imager.The infrared video signals obtained by the experiment are processed with SAT.Then the infrared radiation signals are processed by EMD with Hilbert–Huang and the infrared radiation noise is effectively removed.The research results show that the desorption process,with the change of the temperature,is an endothermic process.The coal absorbs heat when the gas is desorbed and the temperature drops.The coal body temperature drop range is obviously related to coal particle size.The smaller the particle size is,the bigger the temperature drop becomes.The temperature variation curves in the process of coal gas desorption under different particle sizes are fitted,and they comply with the exponential function.The research results lay the theoretical and experimental foundation for non-contact prediction on working face of coal and gas outburst with infrared thermal image technology.

Ageing Assessment, Condition Inspection and Lifetime Evaluation for Safety Related Fuse in Nuclear Power Plant

This paper presents the ageing mechanism of fuse in nuclear power plant in detail. Metal Electromigration is identified as the dominant ageing mechanism. On this basis, the dominant status indicators, temperature and resistance of fuse were ensured, and current-temperature curve was proposed. The infrared thermal imaging technology was used to inspect the ageing condition and prove the current-temperature curve. Finally, the accelerated ageing testing was conducted abiding by the dominant ageing mechanism, and the lifetime was evaluated.

Neutron imaging at Peking University

Neutron imaging techniques were investigated at Peking University based on a 4.5 MV Van de Graaff accelerator.The thermal neutron radiography,fast neutron radiography and fast neutron resonance radiography were tested.The low neutron flux limits the image quality.A new radio frequency quadrupole (RFQ) accelerator based on neutron source with a yield of 1 012 n/s is being set up.

Applying Surface Fitting in the Medical Thermal Tomography Technology

Based on the thermal tomography technology, this thesis tries to calculate quantity and distribution of heat source in vivo from body surface temperature. A superposition temperature image of a number of point heat sources is surface fitted to get the Q of heat sources (information of cancer cells) quantitatively. The result can reflect the disease area information because cancer cell's Q value is much higher than that of normal cell. This application is a new try in the diagnosis of breast cancer, which has an important value on the early detection and diagnosis of disease source.

Direct prejudgement of hot images with detected diffraction rings in high power laser system

A direct prejudgement strategy that takes the diffraction ring as the analysis target is put forward to predict hot images induced by defects of tens of microns in the main amplifier section of high power laser systems. Analysis of hot-image formation process shows that the hot image can be precisely calculated with the extracted intensity oscillation of the diffraction ring on the front surface of the nonlinear plate. The gradient direction matching （GDM） method is adopted to detect diffraction tings. Recognition of simulated diffraction rings shows that it is feasible to directly prejudge hot images induced by those closely spaced defects and the defects that are far apart from each other. Image compression and cluster analysis are utilized to optimize the performance of the GDM method in recognizing actually collected diffraction images. Results show that hot images induced by defects of tens of microns can be directly prejudged without redundant information.

Viscous Heating for Laminar Liquid Flow in Microtubes

Using de-ionized ultra-filtered water (DIUFW) as the working fluid, the effects of viscous dissipation in micro-tubes with inner diameters of 19.9μm and 44.2μm, respectively, have been studied by experiments, the theoretical analysis and the numerical simulation at laminar state. Based on thermal imaging technology of micro-area, the temperature rise resulted from the viscous dissipation in microtube is measured by employing IR camera with a specially magnifying lens at different Reynolds numbers. A 2-D model adapted to microtube is presented to simulate the viscous dissipation characteristic considering electric double layer effect (EDL). The investigation shows the calculating results are in rough agreement with the experimental data if removing the experimental uncertainties. Based on the experimental and the numerical simulation results, a viscous dissipation number which can describe the law of the viscous heating in microtube is summed up and it explains the abnormity of the flow resistance in microtubes.