Can infrared camera images be used for screening in Adolescent Idiopathic Scoliosis?

Adolescent idiopathic scoliosis (AIS) is the most common type of scoliosis, and affects up to 4% of adolescents in early stages. The deformity can develop during any of the rapid periods of growth in children, and the time of pubertal growth spurt also plays a role in spinal curve progression. Hence it is crucial to detect the disease early, to provide timely intervention. Detection of scoliosis when it is mild or before the growth spurt can be conducted via various screening methods. Adam's forward bend test (FBT) and scoliometer measurement of the angle of trunk rotation (ATR) are commonly used, to observe lateral bending and rotation of the spine, causing a visible rib hump. Moire topography can also be used, but is reserved for second tier due to some degree of ambiguity. X-rays (XR) remain the best way to diagnose scoliosis, as it provides a clear image of the spine and allows measurement of Cobb angle; however it has risks associated including requirement of the use of ionising radiation. Infrared (IR) thermography can be used to measure surface temperature and is performed with an IR camera. The temperature distribution and data matrix can be visualised into a thermal map, which has previously been studied and associated with the thermal asymmetry in paraspinal muscles, as well as significant temperature differences between the convex and concave side of the spinal curvature for idiopathic scoliotic patients. We hypothesize that such asymmetry and temperature differences may produce a detectable pattern on IR thermography, which would prompt further confirmatory investigations to reach a fast and non-radiation screening of AIS.

Challenges and Best Practices for Deriving Temperature Data from an Uncalibrated UAV Thermal Infrared Camera

Miniaturized thermal infrared (TIR) cameras that measure surface temperature are increasingly available for use with unmanned aerial vehicles (UAVs). However, deriving accurate temperature data from these cameras is non-trivialsince they are highly sensitive to changes in their internal temperature and low-cost models are often not radiometrically calibrated. We present the results of laboratory and field experiments that tested the extent of the temperature-dependency of a non-radiometric FLIR Vue Pro 640. We found that a simple empirical line calibration using at least three ground calibration points was sufficient to convert camera digital numbers to temperature values for images captured during UAV flight. Although the camera performed well under stable laboratory conditions (accuracy ±0.5 °C), the accuracy declined to ±5 °C under the changing ambient conditions experienced during UAV flight. The poor performance resulted from the non-linear relationship between camera output and sensor temperature, which was affected by wind and temperature-drift during flight. The camera’s automated non-uniformity correction (NUC) could not sufficiently correct for these effects. Prominent vignetting was also visible in images captured under both stable and changing ambient conditions. The inconsistencies in camera output over time and across the sensor will affect camera applications based on relative temperature differences as well as user-generated radiometric calibration. Based on our findings, we present a set of best practices for UAV TIR camera sampling to minimize the impacts of the temperature dependency of these systems.

Infrared Thermography: Not a Valid Method to Track Changes in Core Temperature in Exercising Athletes

ABSTRACT Purpose: Field measurement of core temperature typically requires rectal or other invasive, expensive core temperature methods. Infrared (IR) thermography uses a handheld camera to measure surface temperature at discrete locations. We attempted to validate IR thermography against core-temperature capsules for the tracking of core-temperature changes at rest, during exercise, and recovery. Hypothesis: Infrared thermography is a noninvasive method to follow changes in core temperature during exercise. Materials and methods: Twelve athletes swallowed an ingestible core-temperature (CorTemp) capsule 1-hour prior to exercise. Athletes refrained from drinking for 2 hours prior to or during the study. Temperatures were obtained using both the CorTemp capsule and IR thermography at 10-minute intervals for 30 minutes before exercise, during 30 minutes of moderate intensity aerobic exercise, and for 30 minutes of recovery. The temperatures were then averaged for each segment of data collection. Study design: Prospective descriptive study. Results: Infrared thermography results (rest = 34.7°C C 0.49, exercise = 34.1°C ± 0.77, recovery = 34.6°C ± 0.46) were significantly lower than with the CorTemp capsules (rest = 37°C ± 0.55, exercise = 38.6°C ± 0.47, recovery = 37.7°C ± 0.47) throughout the data collection period. There were no significant correlations between the two measurement methods (rest = 0.22, exercise = 0.07, recovery = 0.59; all p > 0.05). Conclusion: Infrared thermography is not a valid method to track core-temperature changes during exercise. In addition to IR thermography readings being consistently lower, temperature changes before, during, and after exercise showed wide and inconsistent variability. Boggess BR, Stafford H, Moorman CT III, Berkoff DJ. Infrared Thermography: Not a Valid Method to Track Changes in Core Temperature in Exercising Athletes. The Duke Orthop J 2017;7(1):46-50.

Accuracy of Superposition Predictions of Film Cooling Effectiveness on a Flat Plate With Double Rows of Holes

Multi-row film cooling is widely used on both suction side and pressure side of turbine vane, and the coolant behavior is considerable for engine design. Main work of this paper is to find out the accuracy of superposition predictions. Experiments were conducted on flat plates with double rows of cooling holes. The method of stable infrared measurement technique was used to measure surface temperature. Four factors, including hole shape, hole arrangement, row-to-row spacing and blowing ratio were simulated. Numerical simulation using commercial software ANSYS Fluent was also performed to observe the flow structure and film cooling mechanisms between each row. Result showed that the blowing ratio within the range of 0.5 to 2 has an obvious influence on the accuracy of superposition prediction. At low blowing ratio, results obtained by superposition method agreed well with the experimental data while the increase of blowing ratio caused a decrease in accuracy. Another significant factor is hole arrangement, results obtained by superposition prediction was nearly the same as experimental values on staggered arrangement plates while it was much higher on in-line arrangement plates. For different hole shapes, the accuracy of superposition prediction on converging-expanding holes was better than cylinder holes and compound angle holes. For both two hole spacing in this paper, prediction results show good agreement with the experiment results.

Characterization of Fouled Flat Sheet Membranes by Infrared Thermography

An Infrared thermography (IRT) technique for characterization of fouling on membrane surface has been developed. The emitted spectral power from the fouled membrane is a function of emissivity and surface morphology. In this work, a FLIR A320 IR camera was used to measure surface temperature and emissivity. The surface temperature and the corresponding emissivity value of various areas on the fouled membrane surface is measured by the infrared camera and recorded alongside its thermogram. Different fouling experiments were performed using different concentrations of aluminum oxide nanoparticle mixed with deionized water as feed solution (333 ppm, 1833 ppm and 3333 ppm) so as to investigate the effect of feed concentration on the degree of fouling and thus its effect on the emissivity values measured on the membrane surfaces. Surface plots in 3D and Line plots are obtained for the measured emissivity values and thickness of the fouling deposit on the membrane surface respectively. The results indicate that the IRT technique is sensitive to changes that occur on the membrane surface due to deposition of contaminants on the membrane surface and that emissivity is a function of temperature, surface roughness and thickness of the specimen under investigation.

Automated field detection of rock fracturing, microclimate, and diurnal rock temperature and strain fields

The rates and processes that lead to non-tectonic rock fracture on Earth's surface are widely debated but poorly understood. Few, if any, studies have made the direct observations of rock fracturing under natural conditions that are necessary to directly address this problem. An instrumentation design that enables concurrent high spatial and temporal monitoring resolution of (1) diurnal environmental conditions of a natural boulder and its surroundings in addition to (2) the fracturing of that boulder under natural full-sun exposure is described herein. The surface of a fluvially transported granite boulder was instrumented with (1) six acoustic emission (AE) sensors that record micro-crack associated, elastic wave-generated activity within the three-dimensional space of the boulder, (2) eight rectangular rosette foil strain gages to measure surface strain, (3) eight thermocouples to measure surface temperature, and (4) one surface moisture sensor. Additionally, a soil moisture probe and a full weather station that measures ambient temperature, relative humidity, wind speed, wind direction, barometric pressure, insolation, and precipitation were installed adjacent to the test boulder. AE activity was continuously monitored by one logger while all other variables were acquired by a separate logger every 60 s. The protocols associated with the instrumentation, data acquisition, and analysis are discussed in detail. During the first four months, the deployed boulder experienced almost 12 000 AE events, the majority of which occur in the afternoon when temperatures are decreasing. This paper presents preliminary data that illustrates data validity and typical patterns and behaviors observed. This system offers the potential to (1) obtain an unprecedented record of the natural conditions under which rocks fracture and (2) decipher the mechanical processes that lead to rock fracture at a variety of temporal scales under a range of natural conditions.

Automated field detection of rock fracturing, microclimate, and diurnal rock temperature and strain fields

The rates and processes that lead to non-tectonic rock fracture on the Earth's surface are widely debated but poorly understood. Few, if any, studies have made the direct observations of rock fracturing under natural conditions that are necessary to directly address this problem. An instrumentation design that enables concurrent high spatial and temporal monitoring resolution of (1) diurnal environmental conditions of a natural boulder and its surroundings in addition to (2) the fracturing of that boulder under natural full-sun exposure is described herein. The surface of a fluvially transported granite boulder was instrumented with (1) six acoustic emission (AE) sensors that record micro-crack associated, elastic wave-generated activity within the three-dimensional space of the boulder, (2) eight rectangular rosette foil strain gages to measure surface strain, (3) eight thermocouples to measure surface temperature, and (4) one surface moisture sensor. Additionally, a soil moisture probe and a full weather station that measures ambient temperature, relative humidity, wind speed, wind direction, barometric pressure, insolation, and precipitation were installed adjacent to the test boulder. AE activity was continuously monitored by one logger while all other variables were acquired by a separate logger every 60 s. The protocols associated with the instrumentation, data acquisition, and analyses are discussed in detail. During the first four months, the deployed boulder experienced almost 12 000 AE events, the majority of which occur in the afternoon when temperatures are decreasing. This paper presents preliminary data that illustrates data validity and typical patterns and behaviors observed. This system offers the potential to (1) obtain an unprecedented record of the natural conditions under which rocks fracture and (2) decipher the mechanical processes that lead to rock fracture at a variety of temporal scales under a range of natural conditions.

Simultanous Transient Surface Temperature and Heat Flux Measurements in a Large Bore Two-Stroke Diesel Engine

Surface temperature measurements were performed in a large bore two-stroke diesel engine used for ship propulsion. A specially designed fast-response surface thermocouple was used together with an embedded standard K-type thermocouple to measure surface temperature and heat flux with high temporal resolution. Heat flux calculations were carried out both analytically and numerically showing good agreement between the results. Measurements were carried out at three different engine load conditions (25%, 30% and 50% load) in one of the fuel atomizers in the cylinder head. Cyclic surface temperature variations of up to approximately 80 K with a peak temperature of 860 K were observed. The magnitude of the perturbation of the temperature field due to the presence of the thermocouples was investigated by three dimensional CFD simulations.

Effect of Radial Location of Nozzles on Heat Transfer in Preswirl Cooling Systems

This paper investigates heat transfer in a rotating disk system using preswirled cooling air from nozzles at high and low radius. The experiments were conducted over a range of rotational speeds, flow rates, and preswirl ratios. Narrow-band thermochromic liquid crystal (TLC) was specifically calibrated for application to experiments on a disk, rotating at ∼5000 rpm and subsequently used to measure surface temperature in a transient experiment. The TLC was viewed through the transparent polycarbonate disk using a digital video camera and strobe light synchronized to the disk frequency. The convective heat transfer coefficient h was subsequently calculated from the one-dimensional solution of Fourier's conduction equation for a semi-infinite wall. The analysis was accounted for the exponential rise in the air temperature driving the heat transfer, and for the experimental uncertainties in the measured values of h. The experimental data was supported by “flow visualization,” determined from CFD. Two heat transfer regimes were revealed for the low-radius preswirl system: a viscous regime at relatively low coolant flow rates, and an inertial regime at higher flow rates. Both regimes featured regions of high heat transfer where thin, boundary layers replaced air exiting through receiver holes at high radius on the rotating disk. The heat transfer in the high-radius preswirl system was shown to be dominated by impingement under the flow conditions tested.