Thermal Imaging Method Research Articles

Thermal imaging for detecting temperature changes within the rheumatoid foot

The study reports the development of a thermal imaging method suitable for the screening and differentiation of joint inflammation in the rheumatoid foot of patients in comparison with the control group of healthy participants. The study included 81 patients, with rheumatoid arthritis (RA), and 39 healthy volunteers without any signs or symptoms of inflammation. The feet joints were examined by ultrasonography, and the surface temperature of the dorsal side of the foot was measured using a thermovision camera. Significant differences in mean temperatures between the study group and the control group were found. At the same time, there were no statistically significant differences between the mean temperatures in the left and right foot in any of the designated regions in the study and control group. The comparison of average temperatures of joints with or without inflammation, according to ultrasonography, did not show significance except for two joints. Despite the lack of statistical differences in the recorded temperatures, changes in the form of spikes, hot spots, and gradation of the temperatures during screening were observed. Screening analysis of the temperature distribution of the foot can aid in the diagnosis of RA and in the evaluation of the development of the disease. Additional studies must be conducted to confirm the results of this study.

Ensemble Joint Sparse Low-Rank Matrix Decomposition for Thermography Diagnosis System

Composite is widely used in the aircraft industry and it is essential for manufacturers to monitor its health and quality. The most commonly found defects of composite are debonds and delamination. Different inner defects with complex irregular shape are difficult to diagnosed by using conventional thermal imaging methods. In this article, an ensemble joint sparse low-rank matrix decomposition algorithm is proposed by applying the optical pulse thermography (OPT) diagnosis system. The proposed algorithm jointly models the low-rank and sparse pattern by using concatenated feature space. In particular, the weak defects information can be separated from strong noise and the resolution contrast of the defects has significantly been improved. Ensemble iterative sparse modeling are conducted to further enhance the weak information as well as reducing the computational cost. In order to show the robustness and efficacy of the model, experiments are conducted to detect the inner debond on multiple carbon fiber reinforced polymer composites. A comparative analysis is presented with general OPT algorithms. Notwithstanding above, the proposed model has been evaluated on synthetic data and compared with other low-rank and sparse matrix decomposition algorithms.

Experimental Investigation on Mechanism of Latent Heat Reduction of Sodium Acetate Trihydrate Phase Change Materials.

Sodium acetate trihydrate (SAT) phase change material (PCM) has been well known for thermal energy storage due to its high latent heat and resource abundance. However, SAT suffers from severe latent heat reduction after heating and cooling cycles. Although a few of previous researches showed the reduction could be effectively inhibited by using thickeners, the mechanisms of the reduction process and thickeners’ inhibition have not been deeply explored till now. In this work, SAT modified by 5 wt.% nucleating agent of disodium hydrogen phosphate dodecahydrate (SAT/5 wt.% DSP) was prepared and 200 thermal cycles were carried out. The differential scanning calorimeter, Rheometer, X-ray diffractometry, and scanning electron microscope were used to investigate the extent of latent heat reduction, viscosity, phase composition and microstructure, respectively, and the infrared thermal imaging method was used to evaluate heat storage capacity. It was found that the latent heat of SAT/5 wt.% DSP dropped dramatically and the relative decrease in latent heat was measured to be 22.44%. The lower layer of SAT/5 wt.% DSP contained 24.1 wt.% CH3COONa, which was quantitatively consistent with the reduction extent. Furthermore, the phase change endothermic time of the lower layer was only 44.1% of that of the upper. SAT/5 wt.% DSP was further modified by 3 wt.% thickener of carboxymethyl cellulose (SAT/5 wt.% DSP/3 wt.% CMC) and endured 200 thermal cycles. The extent of the latent heat reduction of SAT/5 wt.% DSP/3 wt.% CMC was only 9.29%, and phase compositions were more homogeneous. The 3 wt.% CMC increased viscosity by 14 times, which effectively prevented the Stokes sedimentation velocity of CH3COONa in melts and inhibited the final macroscopic phase separation.

Improvement of methods and means of thermal imagers verification and calibration

This paper suggests the verification and calibration method of thermal imagers that consists in comparison of temperature readings obtained by contact and thermal imaging method. The experimental setup has been developed to confirm the reliability of the proposed method. The main element of experimental setup is an emitting surface in the form of rectangular plate that measures 330×200×4 mm. The plate is covered with paint which emissivity factor is not less than 0,96. The paper presents the results of temperature field calculations on the plate emitting surface. The temperature field of the plate emitting surface has been determined by the contact method using chromel-alumel thermocouples and thermal imaging method. As a result of the obtained temperature values analysis, it has been concluded that if the plate emitting surface temperatures close to 50 °C, the heat exchange of the plate with the ambient air plays a significant role. The air heaters are applied in order to reduce the heat flows dissipation from the plate emitting surface into the environment. The heaters are two aluminum-magnesium alloy plates attached to the end face of the emitting surface. The metal heat exchangers – coils are installed on the surfaces of the plates and connected by hoses to the liquid thermostat. One of the plates heats the air flowing around the emitting surface, and another one prevents the emission thermal expansion into the environment. As a result of heaters application, the heat exchange intensity of a plate radiating surface with environment decreases. Moreover, recommendations about the choice of heaters sizes have been given. The main advantages of the method proposed are the following: ensuring high isothermic of the emitting surface throughout the height of the plate; accuracy of the temperature maintaining at a given level; reducing the device transition time to steady-state regime.

Influence of organism regulation process on the condition of biologically active points

Human body is an open energy system. Aggressive environment forces us to adapt to modern social and economic conditions, technogenic factors and increasing psychological, physical and informational overload. Physiological self-regulation is realized both at the level of individual functional system as well as through their interaction. These are the most important factor in achieving physiological, psychological and social adaptation. Biologically active points (BAP), are projected onto the skin areas of the highest activity of the system of interaction, which unites the integuments of the body, nervous system, internal organs. In them at different depths (from several millimeters to several centimeters) nerve receptors are located, which perceive the effect and transmit them to the internal organs. The functional properties of BAP allow them to participate in the processes of regulating the energy balance of the body. The purpose of this study is to measure changes in the physical parameters of BAPs involved in the energy exchange. In this study BAPs were impacted in two ways. In the first method, experiment participants concentrated mentally to affect the exchange of energy and information in the body. In the first method, organs or energy centers were impacted by the participant himself within his or her internal bodily environment. In the second method, external BAP activation was employed. Laser radiation with wavelength of 0.63 ÷ 0.65 μm and power output power no more than 5 mW. BAP status was assessed by methods of functional diagnostics, i.e measurement of electrical potentials (Foul method) and measurement of infrared radiation on the body surface (thermal imaging method). Despite the differences in impact mechanisms, both methods produce the same effect: an increase in the ability for adaptation and normalization of the functional body state. Thermal imaging is a method for objective monitoring the results of energy-information exchange in the body. Thermal field of the body surface reflects individual characteristics of an organism. Changes in thermal field parameters provoked by self-regulation correspond with individual differences related to person's physiological and psychological state.

ПРАКТИЧЕСКОЕ ПРИМЕНЕНИЕ МЕТОДОВ ТЕПЛОВИЗИОННОГО АНАЛИЗА И КОНТРОЛЯ

The process of operation of any technical objects is inevitably associated with a change in their technical condition and a decrease in operational characteristics. At the same time, the requirements for quality assur-ance of the specified reliability parameters and safety of various technical systems throughout the entire pe-riod of operation are constantly increasing. One of the ways to solve the given problem is integration to the technological process of various types of equipment of new means and methods of technical diagnostics [GOST (State standard) 20911-89, GOST (State standard) 13372-2013]. One of such perspective methods is the thermographic study of objects. In this paper, we experimentally evaluated the main means of thermal imaging control and methods of their application on certain types of equipment.

Features of the thermal imaging method for quality control of profile heat pipes

A new method for controlling the quality of a heat pipe is proposed and tested by separately using the conductive method of heat input and the optical method of measuring temperature at infrared wavelengths, as well as digital methods for processing the recorded brightness contrast of the heat field. The quality of the heat pipe is judged by the magnitude of the asymmetry coefficient of the isothermal surface relative to the heat supply zone, and the defect zone is visually determined by the distortion of the shape of the isothermal lines.

Ablation induced by intense pulsed ion beam and its effects on energy deposition on solid target

Ablation effects play an important role in material processing with intense pulsed ion beam (IPIB) and IPIB diagnostics such as calorimeters and infrared detection may also be influenced by ablation. In this study, with numerical analysis and thermal imaging method, the ablation plume and its effects on energy deposition of IPIB on solid target was studied. Radiation experiments of polyvinyl chloride (PVC) targets with a thickness of 200 μm were carried out on BIPPAB-450 pulsed ion beam accelerator and the energy deposition of the ion beam was investigated with infrared imaging diagnostics. It is revealed that due to the low thermal conductivity and decomposition temperature of PVC, ablation plume can be formed during the early stage of beam irradiation and the ablation product may shield the energy of the ion beam from depositing in the target when energy density reaches a certain threshold. This effect needs to be taken into consideration in order to avoid its influence on applications and beam diagnostics.

Fuzzy C-Means Clustering Based Anomalies Detection in Quadratic Frequency Modulated Thermal Wave Imaging

Defect characterization from its non-defective counterpart from the raw thermal response plays a vital role in Quadratic frequency modulated thermal wave imaging (QFMTWI). The strength of the bone reduces due to the skeletal disorder as the age of the person grows, Early diagnosis corresponding to disease is necessary to provide good bone strength. By detecting bone density variations the disease can be managed effectively. A non-stationary thermal wave imaging method, Quadratic frequency modulated thermal wave imaging (QFMTWI) is used to characterize strictness of the human bone, as well as experimentation also carried on Carbon fiber reinforced polymers (CFRP) sample and are extended to unsupervised machine learning algorithms like k-means clustering and fuzzy c-means clustering algorithms. In case of an observer with less expertise, a perfect unsupervised clustering approach is necessary to fulfill this requirement. In present article, we applied k-means and fuzzy c-means based unsupervised clustering techniques for subsurface defect detection in QFMTWI. The applicability of these algorithms is tested on a numerical simulated biomedical bone sample having various density variations and an experimental Carbon fiber reinforced polymers (CFRP) sample with flat bottom holes of different depths with same size. Signal to noise ratio (SNR) is taken as performance merit and on comparison, we conclude Fuzzy c-means provides better detection and characterization of defects compared to K-means clustering for QFMTWI.

Особенности диагностики технического состоянияпромышленных дымовых труб пассивнымтепловизионным методом

Особенности диагностики технического состоянияпромышленных дымовых труб пассивнымтепловизионным методом

English

English

Research status of on-line monitoring of laser metal deposition

The process of laser metal deposition was easy to be affected by fluctuations of environment and process parameters, leading to the deviation of melt pool temperature or deposition morphology and so on. Accumulation of small deviation would result in the instability of deposition process and lead to the failure of forming. Therefore, the on-line monitoring of laser metal deposition process was studied, involving thermal history of forming parts, temperature and size of melt pool, deposition morphology and forming defects, and so on. In this paper, the on-line monitoring technologies, such as thermocouple temperature measurement, infrared thermal imaging, high-speed camera and other monitoring methods, were introduced, and the open-loop monitoring, closed-loop feedback control and closed-loop feedforward control technologies were illustrated in detail. According to the research situation, the future development of on-line monitoring in laser metal deposition was prospected.

Thermography as a method for evaluating human vegetative reactions

The possibility of using the thermal imaging method to assess the level of blood flow in the course of building thermograms of the surface of the hands of healthy volunteers before and after the load on the muscles was studied in this paper. The results obtained using the thermal imaging method provide objective information about the degree of blood supply to the tissues, which opens up new perspectives for evaluating skin blood flow in the dynamics. The technique is absolutely safe, non-invasive, versatile and easy to perform.

Non-stationary combustion of natural and artificial methane hydrate at heterogeneous dissociation

Dissociation of natural and artificial methane hydrate at combustion was studied experimentally. Thermal imaging and Particle Tracking Velocimetry (PTV) methods were used to analyze the temperature field and gas velocity. The laminar air flow rate varied from 0 to 1.8 m/s. Previously, when modeling the combustion of gas hydrate, a simplified model for a standard laminar velocity profile had been considered. Expectedly, in the combustion region (in the vicinity of the wall) the gas flow velocity was much lower than that at the outer surface of the boundary layer, and calculations showed the presence of the stoichiometric ratio line. The presence of this line in the area of combustion was thought to result in high flame spread speed. The use of the Particle Tracking Velocimetry method and the experimental values of the methane injection rate have led to an unexpected result. High air velocities (maximum of 3–5 m/s) due to free convection have been found in the combustion region. At that in the combustion region, there is a significant excess of oxidant (oxygen) and the mole fraction of CH4 is 10–30 times lower than necessary for the maximum reaction rate. It is shown that high combustion rates (high flame spread speed) may be associated with extremely inhomogeneous dissociation inside the powder and inhomogeneous rate of methane injection over the layer surface. At combustion, “mushroom-like" pulsating flame and methane “bubbles” are formed. The frequency of pulsations increases with the growth of external flow rate. The influence of the initial concentration of methane in natural hydrate on its combustion has been considered. The studies prove that the description of the combustion process must take into account the free convection and heterogeneity of dissociation of methane hydrate in the powder volume.

Two-dimensional temperature distribution measurement of light-emitting diodes by micro-hyperspectral imaging-based reflected light method.

We propose a non-contact measurement method for determining two-dimensional (2D) temperature distribution of light-emitting diodes (LEDs). This method is based on both micro-hyperspectral imaging technology and reflected light method, owning merits of both high efficiency and high spatial resolution. Blue and green bare LEDs are used as LED under test, while red and near-infrared LEDs provide incident light to avoid spectral overlapping so as to reduce measurement error. During data processing, the convolution linear filtering algorithm is employed to improve the measurement accuracy. This proposed method is compared with the micro-thermocouple and infrared thermal imaging, with their respective comparison results in fairly good agreements. For spatial resolution of 2D temperature distribution, this method increases at least one order of magnitude compared with the thermal imaging method.

Photonic, Low-Friction and Antimicrobial Applications for an Ancient Icosahedral/Quasicrystalline Nano-composite Bronze Alloy

The recent discovery of an ancient mirror bronze alloy comprising of nano-quasicrystalline features is pursued further in this article. We have reported new evidence that indicates that two or more types of quasicrystalline phases may be present in the alloy along with hints of a glassy phase. The finding opens the possibilities of various new uses for this alloy. The distribution of the various phases and their morphological patterns that result from the solidification sequence of the alloy are suggestive of unique photonic applications such as optical gratings and optical cloaking. Low-friction applications at a high pair velocity are also possible with this alloy based on the modulus and the surface texture. The wear rate of many quasicrystalline phase containing alloys is low because of their minimal strain-rate softening tendencies. Based on the nano-crystal distribution and compared to known alloys, the use of the alloy is also contemplated for contact-surface antimicrobial uses. We have also reported findings of the possible evidence of an icosahedral structure even after some of the tin is “boiled” away leaving behind a copper-tin-zinc variation of the original alloy. New high-resolution electron microscope lattice imaging microstructures and diffraction patterns of the original mirror alloy have been discussed. A solidification sequence that can preserve the icosahedral features across the atomic stacking scale, the nanometer scale of the crystals and the micrometer scale of cells/dendrites has been proposed. Regardless, there is the difficulty of completely characterizing all phases in this complex mirror alloy by electron microscopy methods alone. X-ray diffraction, fracture surface analysis, thermal transformation analysis, ellipsometric and optical imaging methods are also employed for the characterization. The microstructures are compared with patterns of similar Fibonacci analogs in flowers and petals.

Exploratory Study to Evaluate Respiratory Rate Using a Thermal Imaging Camera

Background: Respiratory rate is a vital physiological measurement used in the immediate assessment of unwell children and adults. Convenient electronic devices exist for the measurement of pulse, blood pressure, oxygen saturation, and temperature. Although devices which measure respiratory rate exist, none have entered everyday clinical practice for acute assessment of children and adults. An accurate and practical device which has no physical contact with the patient is important to ensure readings are not affected by distress caused by the assessment method. Objective: The aim of this study was to evaluate the use of a thermal imaging method to monitor the respiratory rate in children and adults. Methods: Facial thermal images of adult volunteers and children undergoing elective polysomnography were included. Respiration was recorded for at least 2 min with the camera positioned 1 m from the subject’s face. Values obtained using the thermal imaging camera were compared with those obtained from contact methods such as the nasal thermistor, respiratory inductance plethysmography, nasal airflow, and end tidal CO₂. Results: A total of 61 subjects, including 41 adults (age range 27–46 years) and 20 children (age range 0.5–18 years) were enrolled. The correlation between the respiratory rate measured using thermal imaging and the contact method was r = 0.94. Sequential refinements to the thermal imaging algorithms resulted in the ability to perform real-time measurements and an improvement of the correlation to r = 0.995. Conclusion: This exploratory study shows that thermal imaging-derived respiratory rates in children and adults correlate closely with the best performing standard method. With further refinements, this method could be implemented in both acute and chronic care in children and adults.

Оценка точности тепловизионного метода измерения температуры в зоне резания при точении

Оценка точности тепловизионного метода измерения температуры в зоне резания при точении

An Experimental Study of Combustion of a Methane Hydrate Layer Using Thermal Imaging and Particle Tracking Velocimetry Methods

In this paper, the combustion of methane hydrate over a powder layer is experimentally studied using thermal imaging and Particle Tracking Velocimetry (PTV) methods. The experiments are carried out at different velocities of the external laminar air-flow from zero to 0.6 m/s. Usually, simulation of methane hydrate combustion is carried out without taking into account free convection. A standard laminar boundary layer is often considered for simplification, and the temperature measurements are carried out only on the axis of the powder tank. Measurements of the powder temperature field have shown that there is a highly uneven temperature field on the layer surface, and inside the layer the transverse temperature profiles are nonlinear. The maximum temperature always corresponds to the powder near the side-walls, which is more than 10 °C higher than the average volumetric temperature in the layer. Thermal imager measurements have shown the inhomogeneous nature of combustion over the powder surface and the highly variable velocity of methane above the surface layer. The novelty of the research follows from the measurement of the velocity field using the PTV method and the measurement of methane velocity, which show that the nature of velocity at combustion is determined by the gas buoyancy rather than by the forced convection. The maximum gas velocity in the combustion region exceeds 3 m/s, and the excess of the oxidizer over the fuel leads to more than tenfold violation of the stoichiometric ratio. Despite that, the velocity profile in the combustion region is formed mainly due to free convection, it is also necessary to take into account the external flow of the forced gas U0. Even at low velocities U0, the velocity direction lines significantly deviate under the forced air-flow.

Novel Thermal Imaging Method for Rapid Screening of Drug-Polymer Miscibility for Solid Dispersion Based Formulation Development.

This study aimed to develop a rapid, simple, and inexpensive screening method for selecting the best polymeric candidates possessing high active pharmaceutical ingredient (API) miscibility during the early stages of formulation development of solid dispersion based pharmaceutical products. A new thermal imaging based method, thermal analysis by structural characterization (TASC), was used as a thermoptometric tool in conjunction with data analysis software to detect the melting point depression and postmelting dissolution of felodipine particles screened over thin spin-coated films of ten polymers commonly used in the pharmaceutical field. On the polymeric substrates the drug showed different degrees of melting point reduction, reflecting their different levels of polymer-drug miscibility. Using TASC to detect melting point depression is significantly (20-40 times) faster than the conventional DSC method without loss of the sensitivity of detection. The quantity of the material required for the screening is less than 1/1000th of the material used in conventional DSC tests, which significantly reduce the material wastage. Isothermal TASC tests and IR imaging confirmed the occurrence of thermal dissolution of the drug in the polymer for more miscible pairs. The real-time stability tests validate the accuracy of the polymer-drug miscibility screening results. These results demonstrate TASC as a promising screening tool for rapidly selecting the polymeric excipients for pharmaceutical formulations development.