Skin Temperature Distribution Research Articles

Reducing the effect of face orientation using FaceMesh landmarks in drowsiness estimation based on facial thermal images

Abstract In this study, facial skin temperature distribution (FSTD) is focused on as a new driver monitoring index. FSTD is an autonomic index that can be measured remotely. Studies have been conducted to estimate drowsiness based on FSTD using modelng methods such as CNN, a type of deep learning, and sparse modeling, which can be trained with a small amount of data. These studies, however, only evaluated front-facing facial thermal images. FaceMesh is a model that extracts 478 3D facial feature landmarks from a 2D face image. In contrast to conventional models that extract only 68 facial feature landmarks, FaceMesh can extract facial feature landmarks for the entire face, including the cheeks, forehead, and other areas of the face that are in the blind spots. This study aims to improve the accuracy of drowsiness estimation by applying FaceMesh to automatically detect tilted faces and not including tilted images in the training data. As a result, the method proposed in this study improved drowsiness estimation accuracy by about 6% compared to the old method, which did not take face orientation into account.

Non-invasive vision-based personal comfort model using thermographic images and deep learning

An efficient method for predicting occupants' thermal comfort is crucial for developing optimal environmental control strategies while minimizing energy consumption in buildings. This paper presents a non-invasive vision-based personal comfort model that integrates thermographic images and deep learning. Unlike previous studies, the entire thermographic image of the upper body is directly used during model training, minimizing complex data processing and maximizing the use of rich skin temperature distribution. The proposed method is validated using thermographic images and corresponding thermal sensation votes (TSV) from 10 participants under different experimental conditions. Results show that the model based on a 3-point TSV scale achieves exceptional classification performance with an average accuracy of 99.51 %, outperforming existing models. The model performance using a 7-point TSV scale is slightly lower, with an average accuracy of 89.90 %. This method offers potential for integrating thermal comfort models into real-time building environmental control, optimizing occupant comfort and energy consumption.

Numerical simulation of the thermo-mechanical coupling behavior of skin tissue exposed to repetitive pulse laser irradiation

A thorough understanding of the thermo-mechanical coupling behavior during the interaction between pulsed laser and skin tissue is a prerequisite for successful application of pulsed laser technology in the treatment of various skin diseases and injuries. Taking into account the complex physiological structure of skin tissue, a theoretical model is established to characterize the thermo-mechanical response of multi-layer skin tissue with variable physical properties, in which the non-linear governing equations of bio-thermo-mechanics with dual-phase lag mechanism and Henrique burn equation are involved. The finite difference method was employed to obtain the time-space distribution of skin temperature, displacement and stress under repeated pulse laser action, and the incidental thermal damage was further evaluated on this basis. The numerical results stated that: i) repeated pulse laser can significant reduce the peak temperature of skin tissue and further reduce or even eliminate thermal damage under the premise of required energy threshold, ii) the thermo-mechanical coupling response and potential thermal damage will be inhibited when the temperature dependence of physical parameter is considered, in which the thermal stress is more sensitive to the temperature dependence than others, iii) the thermal damage is more sensitive to the input parameters than that of thermo-mechanical response, and the burn time can be effectively delayed or even avoided for appropriate input options.

Designing a personalized thermo-mechanically optimized liner for transfemoral prosthetics

Elastomeric interphases (liners) protect the residual limb and distribute mass bearing to the prosthetic socket. However, discomfort due to excessive sweat and heat in the residual limb is the most relevant factor that negatively affects the quality of life in transfemoral prosthetics users. Additionally, a warm and humid environment and the non-uniform mass distribution can compromise blood flow in the residual limb; these factors favor the development of skin lesions, the dropout rate of prosthetic use, and subsequent amputations. Previous mathematical models that predict skin temperature distribution based on Pennes' model and explain the Fourier and non-Fourier thermic response are available. However, these models require knowledge of difficult parameters to obtain in conditions that lead to amputation. Therefore, the current study aims to propose an experimentally based method to design a personalized liner with areas of different diffusivity rates by using perforations according to thermal needs, preserving the mechanical properties of the liner. After thermal and mechanical characterization, we elaborated a personalized plane liner according to the thermal expression of the anterior thigh using infrared analysis. We tested the liner to probe its ability to dissipate heat.

Effect of subjective health conditions on facial skin temperature distribution: a 1-year statistical analysis among four participants

Effect of subjective health conditions on facial skin temperature distribution: a 1-year statistical analysis among four participants

Hot, cold, or just right? An infrared biometric sensor to improve occupant comfort and reduce overcooling in buildings via closed-loop control

To improve occupant comfort and save energy in buildings, we have developed a closed-loop air conditioning (AC) sensor-controller that predicts occupant thermal sensation from the thermographic measurement of skin temperature distribution, then uses this information to reduce overcooling (cooling-energy overuse that discomforts occupants) by regulating AC output. Taking measures to protect privacy, it combines thermal-infrared (TIR) and color (visible spectrum) cameras with machine vision to measure the skin-surface temperature profile. Since the human thermoregulation system uses skin blood flow to maintain thermoneutrality, the distribution of skin temperature can be used to predict warm, neutral, and cool thermal states. We conducted a series of human-subject thermal-sensation trials in cold-to-hot environments, measuring skin temperatures and recording thermal sensation votes. We then trained random-forest classification machine-learning models (classifiers) to estimate thermal sensation from skin temperatures or skin-temperature differences. The estimated thermal sensation was input to a proportional integral (PI) control algorithm for the AC, targeting a sensation level between neutral and warm. Our sensor-controller includes a sensor assembly, server software, and client software. The server software orients the cameras and transmits images to the client software, which in turn assesses occupant skin temperature distribution, estimates occupant thermal sensation, and controls AC operation. A demonstration conducted in a conference room in an office building near Houston, TX showed that our system reduced overcooling, decreasing AC load by 42% when the room was occupied while improving occupant comfort (fraction of “comfortable” votes) by 15 percentage points.

Evaluation of mixed convection-radiation flow of a viscous fluid restricted to a vertical porous channel: A comparative study

This article examines the steady mixed convection flow in an upstanding porous channel of a hydrodynamic viscous fluid that is electrically conductive due to the thermal radiation effect. The homotopy perturbation method (HPM) is used to generate analytical solutions to the governing differential equations that characterize the velocity and temperature flow properties. For relevant temperature jump and velocity slip situations, the effects of mixed convection parameters, thermal radiation parameters, and magnetic field effects on the velocity field, skin friction coefficient, temperature distribution, and heat transfer rate have been described. This research also analyses and compares the results obtained by Abbas et al. (2020) with this present work when HPM was used for the limiting cases. It is interesting to report that an excellent agreement was established, thereby authenticating and validating the accuracy of HPM as a strong tool for obtaining approximate solutions. According to the results of this study, it is possible to effectively control the velocity and temperature gradients by varying the main relevant parameters such as: the mixed convection parameter for a constant pressure gradient, the thermal radiation parameter, the magnetic field effect, the rarefaction parameter, and the wall ambient temperature difference ratio parameter

Research on the Heating Effect of a Convection Radiator Based on a Human Thermophysiological Model

Forced convection is the most effective way to improve the thermal efficiency of a radiator under low-temperature conditions. This technical method differs significantly from the heating effects of general radiation and natural convection. Few studies have applied the objective evaluation method based on quantitative calculation to evaluate the effectiveness of indoor heating or optimize the technical parameters (air flow rate, air supply method, etc.) of heating systems. This article couples human metabolic factors with heating environmental factors and uses a 57-node human thermal physiological model to evaluate the effectiveness of forced convection radiator heating from the perspective of the local thermal comfort of the human body and demonstrates the feasibility of this scheme by comparing it with floor radiation heating. The research shows that the air supply speed of a radiator affects human thermal comfort. Continuing to increase the wind speed, at a speed of 3 m/s, the surface temperature of the human body reaches a high value and will then decrease, leading to a decrease in thermal comfort. Research on indoor air distribution shows that the use of bottom-side air supply provides better thermal comfort compared to top air supply. The local skin temperature distribution of the human body indicates that when the indoor average temperature is higher than 20 °C, the overall thermal comfort of convective radiator heating and floor radiant heating is comparable. The article provides a way of objectively calculating and directly quantifying the effect of heating equipment on human thermal physiological parameters.

A modified model to assess the thermal protective performance of fire-retardant clothing exposed to both flame and radiant source

The present work evaluates the thermal protective performance (TPP) of a multi-layered fire-resistant fabric system subjected to a high intensity risky thermal environment integrating both flame and radiant heat exposure by developing a modified model for the fabric as well as the skin. The present numerical analysis takes into consideration a multiple-layer flameproof gear (outer shell, moisture barrier, and thermal liner), an airgap separating fabric and skin, and a three-layer of skin (epidermis, dermis, and fat layer). The present model is formulated by considering a two-flux model for the radiative heat interaction in the porous fabric medium and a nonlinear bioheat transfer model for the multi-layered skin. The radiative part of the total incident energy from the flame and the radiant heater is considered to be absorbed, emitted, reflected, and transmitted through the porous fibrous layer. Here, a two-flux model is implemented to simulate the self-emission of hot gas trapped inside the porous fabrics. The thermal response in multi-layered skin is analysed using a non-linear bioheat transfer model considering a temperature dependent thermal conductivity of the living tissue. Purely radiant exposure markedly impairs turnout gear protection, while performance deteriorates more gradually with increased convective thermal energy. Greater fabric transmissivity negatively affects skin temperature distribution and TPP ratings more than equivalent reflection reduction. These study results aid in enhancing flame-resistant fabric thermal protection.

Analytical assessment of heat transfer due to Williamson hybrid nanofluid (MoS2 + ZnO) with engine oil base material due to stretched sheet

The efficiency of fuel consumptions and improved performances is real challenge in the vehicle engines. Recent advances in thermal engineering suggested various tools to improve the capacitance of engine oil for which the interaction of nanoparticles is more dynamical. The aim of current research is to enhance the thermal aspects of engine oil with suspension of Williamson hybrid nanofluid. The hybrid nanofluid is the suspension of molybdenum disulfide MoS2 and zinc oxide ZnO. In order to increase the heating capability of system, external heat source and viscous dissipation features are contributed. The flow analysis is based on moving surface contains porous medium. After modelling the problem, the analytical outcomes of attributed with variational iteration method (VIM). The computational simulations are performed with help of Lagrange Multiplier technique. The impact of numerous physical parameters on skin fraction, Nusselt numbers, temperature distribution and velocity profile is exhibited.

The optimization of sparse modeling for drowsiness estimation based on general facial skin temperature distribution

The optimization of sparse modeling for drowsiness estimation based on general facial skin temperature distribution

Determination of the Effects of a Series of Ten Whole-Body Cryostimulation Sessions on Physiological Responses to Exercise and Skin Temperature Behavior following Exercise in Elite Athletes.

The present study investigated the effects of a series of 10 whole-body cryostimulation (WBC) sessions (3 min; -110 °C) on physiological and thermal responses to a submaximal exercise test in 17 elite athletes. Participants performed an exercise test twice at similar levels of intensity before and after a series of ten WBC sessions. Before and during the test, each participant's oxygen uptake (VO2), heart rate (HR), internal temperature (Ti), and skin temperature in selected areas of the skin were measured, and the mean arterial pressure (MAP), physiological strain index (PSI), and mean skin temperature (Tsk) were calculated. The results show that during exercise, increases in Ti and the PSI were significantly lower after the WBC sessions, and although there were no significant changes in HR or the MAP, the Tsk was significantly higher. Following exercise, an increase in skin temperature asymmetry over the lower-body muscles was detected. A series of WBC sessions induced a tendency toward a decrease in temperature asymmetry over the thigh muscles. In conclusion, a series of ten WBC sessions does not induce significant modifications in physiological variables but does influence the PSI and Ti during exercise. Moreover, a series of ten WBC sessions influences the distribution of skin temperature and the magnitude of temperature asymmetries in the early phase of recovery.

Heat and mass transfer by stirring nanofluids with the presence of renewable solar rays, Joule heating, and entropy procreation

Renewable solar radiation is the foremost energy source because of its accessibility, natural replication, and sustainability in an environmentally safe manner. Here, researchers intended to inspect the heat and mass transfer via nanofluid transported on an inclined permeable expanded sheet in the presence of solar thermal radiation without any barrier. Mainly, the formation of non-recovery energy called entropy and Joule heating are also weighed. The guiding non-linear partial differential equations were transformed into systems of non-linear higher-order ordinary differential equations by felicitous similarity transformation. They are solved by the prevalent technique called the Homotopy Analysis Method, which is executed by the BVPh2.0 package in Mathematica 12.1 software. Comparisons with preceding published articles confirm the method's validity and accent its admirable uniformity. Afterward, the magnetic field interaction delays the mobility of nanofluid while increasing the magnitude of local skin friction and temperature distribution. By intensifying the thermal radiation parameter and Eckert number, the temperature and entropy production escalated. Furthermore, the heat transfer by convective surpasses that of conductive owing to the particles' Brownian motion. Thermophoresis established surplus tiny-particles concentration. Heat transfer from solar radiation in moving nanofluids has been applicable for cooking, heating water, and producing electricity.

High‐Resolution Thermal Imaging in the Antarctic Marginal Ice Zone: Skin Temperature Heterogeneity and Effects on Heat Fluxes

AbstractInsufficient in situ observations from the Antarctic marginal ice zone (MIZ) limit our understanding and description of relevant mechanical and thermodynamic processes that regulate the seasonal sea ice cycle. Here we present high‐resolution thermal images of the ocean surface and complementary measurements of atmospheric variables that were acquired underway during one austral winter and one austral spring expedition in the Atlantic and Indian sectors of the Southern Ocean. Skin temperature data and ice cover images were used to estimate the partitioning of the heterogeneous surface and calculate the heat fluxes to compare with ERA5 reanalyses. The winter MIZ was composed of different but relatively regularly distributed sea ice types with sharp thermal gradients. The surface‐weighted skin temperature compared well with the reanalyses due to a compensation of errors between the sea ice fraction and the ice floe temperature. These uncertainties determine the dominant source of inaccuracy for heat fluxes as computed from observed variables. In spring, the sea ice type distribution was more irregular, with alternation of sea ice cover and large open water fractions even 400 km from the ice edge. The skin temperature distribution was more homogeneous and did not produce substantial uncertainties in heat fluxes. The discrepancies relative to reanalysis data are however larger than in winter and are attributed to biases in the atmospheric variables, with the downward solar radiation being the most critical.

Experimental evaluation of partial body cryotherapy unit with gas supply regulation

The partial body cryotherapy is a medical treatment that uses a physical factor to stimulate the main part of body surface. Today physicians do not have the technical ability to improve this method towards predictive and personalized medicine. Different patients have different dimensions and other features (physique, sex, age, adaptation level, etc.). However, physicians are able to set only the exposure duration. In this case, the skin cooling uncertainty and non-uniformity reduces the safety and effectiveness of cryoexposure. The key to upgrade cryotherapy is increasing the number of parameters to achieve a less skin temperature difference at the end of exposure and to plan a given skin cooling for different patients by reducing the intensity of cooling. This article is aimed to experimentally evaluate the novel partial body cryotherapy unit that has the ability to regulate: the gas temperature in the cryocabin; the inlet jet direction and the exposure duration. Based on the proposed model of a human as an object of cooling, using the developed unit, the adopted cryoexposure protocol and the presented approach to the analysis of infrared images, experiments were conducted. Data were obtained on the participant's interview and skin temperature. It is shown that the approach used is safety treatment and make it possible to obtain an improved and controlled skin temperature distribution at the end of cryoexposure. It might be relevant for improving cryotherapy protocols and for equipment development.

GNN-Based Embedded Framework for Consumer Affect Recognition Using Thermal Facial ROIs

Recently consumer electronics products for the human device or machine interaction in smart healthcare systems have been widespread due to progress in health monitoring hardware and remote diagnostic services. Affect recognition through thermal facial signatures is significant in real-time Human-machine Interaction (HMI) studies. The distribution of facial skin temperature displays explicit characteristics related to affect arousal. During human interacts with a machine or computer, it is challenging to detect face and track the facial regions of interest (ROI) in a thermal video because of head motion artifacts. Our proposed embedded portable HMI product integrated with the required hardware and deep learning architecture is used to recognize the human affect in real-time. The transfer learning approach (Faster R-CNN) and the Multiple Instance Learning (MIL) algorithm are applied to thermal video for thermal face and ROIs detection and tracking. The multivariate time series (MTS) features generated from specific ROIs' calculated mean intensity variations. This study proposes a k-Nearest Neighbor (k-NN) algorithm-based graph neural network (GNN) architecture that utilizes MTS features to recognize affects in the facial thermal video. The effectiveness of the proposed algorithm for the In-house and NVIE thermal data-set gives better accuracy of 76.05% and 71.91% compared with state-of-the-art approaches.

Infrared Thermography Imaging for Assessment of Peripheral Perfusion in Patients with Septic Shock.

Skin temperature changes can be used to assess peripheral perfusion in circulatory shock patients. However, research has been limited to point measurements from acral parts of the body. Infrared thermography allows non-invasive evaluation of temperature distribution over a larger surface. Our study aimed to map thermographic patterns in the knee and upper thigh of 81 septic shock patients within 24 h of admission and determine the relationship between skin temperature patterns, mottling, and 28-day mortality. We extracted skin temperature measurements from zones corresponding to mottling scores and used a linear mixed model to analyze the distribution of skin temperature in patients with different mottling scores. Our results showed that the distribution of skin temperature in the anterior thigh and knee is physiologically heterogeneous and has no significant association with mottling or survival at 28 days. However, overall skin temperature of the anterior thigh and knee is significantly lower in non-survivors when modified by mottling score. No differences were found in skin temperature between the survivor and non-survivor groups. Our study shows the potential usefulness of infrared thermography in evaluating skin temperature patterns in resuscitated septic shock patients. Overall skin temperature of the anterior thigh and knee may be an important indicator of survival status when modified by mottling score.

MHD flow of nanofluid over moving slender needle with nanoparticles aggregation and viscous dissipation effects.

The study of boundary layer flows over an irregularly shaped needle with small horizontal and vertical dimensions is popular among academics because it seems to have a lot of uses in fields as different as bioinformatics, medicine, engineering, and aerodynamics. With nanoparticle aggregation, magnetohydrodynamics, and viscous dissipation all playing a role in the flow and heat transmission of an axisymmetric nanofluid via a moving thin needle, this article provides guidance on how to employ a boundary layer for this purpose. In this case, we utilized the similarity transformation to change the dimensional partial differential equation into the dimensionless ordinary differential equation. We utilize MATHEMATICA to include shooting using RK-IV methods after identifying the numerical issue. Several characteristics were measured, leading to the discovery of a broad variety of values for things like skin friction coefficients, Nusselt numbers, velocity profiles, and temperature distributions. Velocity profile decreases with increasing values of and increases against Temperature profiles enhances with increasing values of , and The reduction in skin friction between a needle and a fluid can be observed when the values of M and are boosted. Furthermore, it was also noticed an increase in heat transfer on needle surface dramatically when , and M were raised, whereas displayed the opposite effect. The findings of the current study are compared with prior findings for a particular instance in order to confirm the findings. Excellent agreement between the two sets of results is found.

Entropy Analysis on Magneto-Convective and Chemically Reactive Nanofluids Flow Over a Stretching Cylinder in the Presence of Variable Thermal Conductivity and Variable Diffusivity

The current paper is on the boundary layer flow of a magnetohydrodynamic nanofluids (Cu, Al2O3 nanoparticles with base fluid water) flow over a linearly stretching cylinder. We have analyzed the entropy generation with heat and mass transfer in mixed convection, thermal radiation, viscous dissipation, variable thermal conductivity, variable mass diffusivity, and binary chemical reaction with activation energy. Convective boundary conditions are also considered here. No such attempt is yet made by the researchers on hybridization and entropy optimization model by considering variable thermal conductivity and variable mass diffusivity with binary chemical reaction with convective boundary conditions induced by a stretching cylinder. The efficient implicit Runge-Kutta-Fehlberg method with shooting technique is used for numerical solutions to the transformed-converted non-linear system of equations. The study is motivated by analyzing the effects on the nanofluid velocity, skin friction coefficient, temperature distribution, Nusselt number, nanoparticles concentration, and Sherwood number inside the boundary layer. The impact of solid volume fraction, chemical reaction, and activation energy with entropy generation is the key findings of the current investigation. Variable thermal conductivity and variable diffusivity parameters hike temperature and concentration profile, respectively. Entropy and Bejan number are increasing functions for curvature parameters.

Skin temperature normalizes faster than pressure pain thresholds, pain intensity, and pain distribution during recovery from eccentric exercise

IntroductionAcute musculoskeletal injuries have diverse symptomatology and a multidimensional recovery process, including changes in swelling, redness, hyperalgesia, and expanded pain distribution. In a small proportion of cases, the tissue heals, although these symptoms persist, reflecting altered peripheral and central pain mechanisms. However, the otherwise healthy multidimensional recovery process following damage and pain is less than clear. The objective was to assess mechanical muscle hyperalgesia, skin temperature, and pain intensity and distribution during the recovery process in response to eccentric exercise in the hamstring muscles. MethodsTwenty-four healthy males participated in four sessions (Day-0, Day-2, Day-4, and Day-7). Exercise-induced muscle soreness was induced on Day-0 by five sets of 20 repetitions of an eccentric exercise involving the hamstrings on the dominant leg. Each session included assessments of thermography, pressure pain thresholds (PPTs), pain intensity, and area of exercise-induced pain. ResultsDecreased PPTs (P < 0.005), higher pain intensity (P < 0.001), and a larger area of pain (P < 0.001) were displayed on Day-2 and Day-4 than Day-0. Skin temperature decreased on Day-2 than Day-0 (P < 0.01) and returned to baseline assessments by Day-4, despite lower temperature than the contralateral tight (P < 0.01). Further, there was a positive correlation between pain intensity and area on Day-2 and Day-4 (P < 0.005), but no for changes in skin temperature. ConclusionThermographic changes and pain-related variables altered following eccentric exercise demonstrate different recovery times. These results provide insights into potential mechanisms and measures that can be used to assess recovery from exercise-induced damage.