112 research outputs found
Optimisation of a heat source for infrared thermography measurements : comparison to mehler engineering + service-heater
Using an optimised heating source in active thermography can facilitate the processing of
measurement results. By designing a custom heat source for dynamic line scan thermography, we reduced
the excitation power needed to heat the sample and decreased the unwanted side effects originating
of a wide-range heating source. The design started from a regular halogen tube lamp and a reflector
is composed to provide the desired heating power in a narrow band. The reflector shape is optimised
using ray-tracing software to concentrate the electromagnetic radiation along with the heat in a slim
line. A comparison between the optimised heat source and a commercially available line-heater is
performed. The width of the heated region from the Mehler Engineering + Service-heater is larger than
prescribed in the datasheet. The optimised line heater has several advantages over the comercially
available heat source
Spot weld inspections using active thermography
Spot welds have a significant part in the creation of automotive vehicles. Since the integrity
of, for example, a car, is dependent on the performance of multiple welds, it is important to ensure
the quality of each spot weld. Several attempts have been made in order to determine the quality of
spot welds, but most of them do not focus on the applicability in the manufacturing process. Spot
weld inspections are often performed using back heating. However, during manufacturing, robotic
inspections are desired, and since the bodywork of a car is a complex shape, the accessibility from the
inside of the vehicle is minor. Therefore, inspections using front heating are more suitable. In this
manuscript, multiple excitation methods are compared as well as different post-processing techniques.
The used excitation techniques can be divided into light heating and inductive heating. Light heating
is further divided in lock-in thermography and pulse thermography. The used post-processing
techniques are principle component analysis and fast Fourier transform. Inductive heating turns out
to be the most suitable measurement technique since it is fast and can be performed as front and back
heating. Both investigated post-processing techniques deliver suitable information, such as relief
images and information of the internal structure of the spot wel
Mechanics of Psoas Tendon Snapping. A Virtual Population Study.
Internal snapping of the psoas tendon is a frequently reported condition, especially in young adolescents involved in sports. It is defined as an increased tendon excursion over bony or soft tissue prominence causing local irritation and inflammation of the tendon leading to groin pain and often is accompanied by an audible snap. Due to the lack of detailed dynamic visualization means, the exact mechanism of the condition remains poorly understood and different theories have been postulated related to the etiology and its location about the hip. In the present study we simulated psoas tendon behavior in a virtual population of 40,000 anatomies and compared tendon movement during combined abduction, flexion and external rotation and back to neutral extension and adduction. At risk phenotyopes for tendon snapping were defined as the morphologies presenting with excess tendon movement. There were little differences in tendon movement between the male and female models. In both populations, abnormal tendon excursion correlated with changes in mainly the femoral anatomy (male r = 0.72, p < 0.001, female r = 0.66, p < 0.001): increased anteversion and valgus as well as a decreasing femoral offset and ischiofemoral distance. The observed combination of shape components correlating with excess tendon movement in essence presented with a medial positioning of the minor trochanter. This finding suggest that psoas snapping and ischiofemoral impingement are possibly two presentations of a similar underlying rotational dysplasia of the femur
Personalized hip joint kinetics during deep squatting in young, athletic adults
The goal of this study was to report deep squat hip kinetics in young, athletic adults using a personalized numerical model solution based on inverse dynamics. Thirty-five healthy subjects underwent deep squat motion capture acquisitions and MRI scans of the lower extremities. Musculoskeletal models were personalized using each subject's lower limb anatomy. The average peak hip joint reaction force was 274 percent bodyweight. Average peak hip and knee flexion angles were 107 degrees and 112 degrees respectively. These new findings show that deep squatting kinetics in the younger population differ substantially from the previously reported in vivo data in older subjects
Recommended from our members
Mechanics of Psoas Tendon Snapping. A Virtual Population Study.
Internal snapping of the psoas tendon is a frequently reported condition, especially in young adolescents involved in sports. It is defined as an increased tendon excursion over bony or soft tissue prominence causing local irritation and inflammation of the tendon leading to groin pain and often is accompanied by an audible snap. Due to the lack of detailed dynamic visualization means, the exact mechanism of the condition remains poorly understood and different theories have been postulated related to the etiology and its location about the hip. In the present study we simulated psoas tendon behavior in a virtual population of 40,000 anatomies and compared tendon movement during combined abduction, flexion and external rotation and back to neutral extension and adduction. At risk phenotyopes for tendon snapping were defined as the morphologies presenting with excess tendon movement. There were little differences in tendon movement between the male and female models. In both populations, abnormal tendon excursion correlated with changes in mainly the femoral anatomy (male r = 0.72, p < 0.001, female r = 0.66, p < 0.001): increased anteversion and valgus as well as a decreasing femoral offset and ischiofemoral distance. The observed combination of shape components correlating with excess tendon movement in essence presented with a medial positioning of the minor trochanter. This finding suggest that psoas snapping and ischiofemoral impingement are possibly two presentations of a similar underlying rotational dysplasia of the femur
Recommended from our members
Mechanics of Psoas Tendon Snapping. A Virtual Population Study.
Internal snapping of the psoas tendon is a frequently reported condition, especially in young adolescents involved in sports. It is defined as an increased tendon excursion over bony or soft tissue prominence causing local irritation and inflammation of the tendon leading to groin pain and often is accompanied by an audible snap. Due to the lack of detailed dynamic visualization means, the exact mechanism of the condition remains poorly understood and different theories have been postulated related to the etiology and its location about the hip. In the present study we simulated psoas tendon behavior in a virtual population of 40,000 anatomies and compared tendon movement during combined abduction, flexion and external rotation and back to neutral extension and adduction. At risk phenotyopes for tendon snapping were defined as the morphologies presenting with excess tendon movement. There were little differences in tendon movement between the male and female models. In both populations, abnormal tendon excursion correlated with changes in mainly the femoral anatomy (male r = 0.72, p < 0.001, female r = 0.66, p < 0.001): increased anteversion and valgus as well as a decreasing femoral offset and ischiofemoral distance. The observed combination of shape components correlating with excess tendon movement in essence presented with a medial positioning of the minor trochanter. This finding suggest that psoas snapping and ischiofemoral impingement are possibly two presentations of a similar underlying rotational dysplasia of the femur
A simplified model of a mechanical cooling tower with both a fill pack and a coil
Cooling accounts for a large amount of the global primary energy consumption in buildings and industrial processes. A substantial part of this cooling demand is produced by mechanical cooling towers. Simulations benefit the sizing and integration of cooling towers in overall cooling networks. However, for these simulations fast-to-calculate and easy-to-parametrize models are required. In this paper, a new model is developed for a mechanical draught cooling tower with both a cooling coil and a fill pack. The model needs manufacturers' performance data at only three operational states (at varying air and water flow rates) to be parametrized. The model predicts the cooled, outgoing water temperature. These predictions were compared with experimental data for a wide range of operational states. The model was able to predict the temperature with a maximum absolute error of 0.59°C. The relative error of cooling capacity was mostly between ±5%
- …