Modelling and Thermographic Measurements of LED Optical Power.

This paper presents a simple engineering method for evaluating the optical power emitted by light-emitting diodes (LEDs) using infrared thermography. The method is based on the simultaneous measurement of the electrical power and temperature of an LED and a heat source (resistor) that are enclosed in the same plastic packaging under the same cooling conditions. This ensures the calculation of the optical power emitted by the LED regardless of the value of the heat transfer coefficient. The obtained result was confirmed by comparing it with the standard direct measurement method using an integrated sphere. The values of the estimated optical power using the proposed method and the integrated sphere equipped with a spectrometer were consistent with each other. The tested LED exhibited a high optical energy efficiency, reaching approximately η ≈ 30%. In addition, an uncertainty analysis of the obtained results was performed. Compact modelling based on a thermal resistor network (Rth) and a 3D-FEM analysis were performed to confirm the experimental results.

Obstacle Detection in Infrared Navigation for Blind People and Mobile Robots.

The paper is a continuation of the authors' work intended for infrared navigation for blind people and mobile robots. This concerns the detection of obstacles in the person's or mobile robot's trajectory, in particular, the detection of corners. The temperature distribution of a building's internal wall near a corner has been investigated. Due to geometry, more heat will be transferred by conduction so that inside the building, the temperature on the wall will be decreasing towards a corner. The problem will be investigated theoretically and numerically, and the results are confirmed by experimental measurements. The purpose of this research is to help blind people by equipping them with a small infrared camera that warns them when they are approaching a corner inside a building. The same aim is addressed to mobile robots.

Thermal drift compensation method for microbolometer thermal cameras.

We propose a new method of compensation for drifts in thermal cameras using a filter in place of a shutter. The latter method requires periodically closing the camera, thus causing the images to appear frozen frequently. Our technique of replacing the shutter with a filter eliminates this frozen image problem. In this paper we discuss the principles of the new method and present the obtained results.

Cyclosporine A - treated nephrotic children show impaired vasodilatation but no autonomic neuropathy.

INTRODUCTION: The aim of the study was to determine the effect of long-term cyclosporine A (CsA) treatment in children with idiopathic nephrotic syndrome on autonomic nerve function and peripheral blood flow assessed with thermography. MATERIAL AND METHODS: The study group consisted of 19 nephrotic children treated with cyclosporine A compared to 16 healthy children. The assessment of blood flow was made based on the results of thermographic measurements during the cold stress test by an infrared radiation registering camera. Ewing's battery of non-invasive tests was used to assess autonomic function. RESULTS: The study showed diminished temperature increase after the cooling test in children with nephrotic syndrome treated with CsA. Sympathetic activity test results were comparable to healthy children. CONCLUSIONS: It may be hypothesized that cyclosporine A administered even in low doses induces small vessel dysfunction measured by the thermographic method. This effect seems to be independent of sympathetic nervous system involvement, which was absent in cyclosporine A treated nephrotic children.

Active thermography in qualitative evaluation of protective materials.

This is a study of the possibilities of a qualitative evaluation of protective materials with active thermography. It presents a simulation of a periodic excitation of a multilayer composite material. Tests were conducted with lock-in thermography on Kevlar composite consisting of 16 layers of Kevlar fabric reinforced with formaldehyde resin with implanted delamination defects. Lock-in thermography is a versatile tool for nondestructive evaluation. It is a fast, remote and nondestructive procedure. Hence, it was used to detect delaminations in the composite structure of materials used in the production of components designed for personal protection. This method directly contributes to an improvement in safety.

[Assessment of the peripheral circulation in children with nephrotic syndrome treated with cyclosporin A]. / Ocena zaburzen krazenia obwodowego u dzieci z idiopatycznym zespolem nerczycowym leczonych cyklosporyna A.

Cyclosporin A (CsA) is an immunosuppressive agent used in children for the treatment of steroid-dependent idiopathic nephrotic syndrome (INS). Despite its benefitial effect on a course of the disease CsA may exert nephrotoxic effects because of its vasoconstrictive properties. CsA-dependent disorders of the peripheral flow (Raynaud phenomenon--RP) have been recently described. The aim of the study was to assess the effect of CsA on the peripheral circulation. The study group comprised 16 children (12 male, 4 female; mean age 9.8 +/- 4.5 years) treated with CsA for at least 6 months due to INS (mean treatment time 39 +/- 27 months). Thirteen age- and sex-matched individuals served as controls. Peripheral circulation disorders were evaluated by means of a cold stress test (both hands were held in lukewarm water (20 degrees C) for 1 minute and thereafter the changes in the hand temperature were recorded with thermographic camera (Inframetrics SC1000). RP assessment was performed according to the method described by Ammer and Ring. The temperature gradient of 4 degrees C or greater maintained between metacarpal and peripheral areas of a hand after 10 minutes was considered diagnostic for RP. According to these criteria RP was confirmed in only 3 patients from the study group and in 2 controls. However, the time of the temperature increase in the first 5 minutes after cooling was considerably shorter in the children with INS (0.26 +/- 0.26 degrees C/min vs 0.51 +/- 0.29 degrees C/min, p=0.02). No correlation between CsA serum concentration, CsA dose and impairment of the hand temperature increase was found. The study confirmed that in children suffering from INS treated with CsA peripheral blood flow disorders can be seen. It seems that impaired vessel reactivity may result from the vasoconstrictive effect of CsA.

Investigations of single and multilayer structures using lock-in thermography--possible applications.

This paper presents a study of the possibilities of evaluating thermal parameters of single and multilayer structures using dynamic thermography. It also discusses potential uses of lock-in thermography. It presents a simulation of a periodic excitation of a multilayer composite material. In practice, the described methods can be employed in various applications, for example, in multilayer nonwoven microelectronic components manufactured from hemp fibers, chemical fibers, with an addition of electrically conducting fibers, and in medicine and biology. This paper describes tests conducted with lock-in thermography on carbon fibre reinforced composites with implanted delamination defects. Lock-in thermography is a versatile tool for non-destructive evaluation (NDE). Lock-in thermography is a fast, remote and non-destructive procedure. Hence, it has been used to detect delaminations in the composite structure of aircraft. This method directly contributes to an improvement in safety.

Raynaud's phenomenon and endothelial dysfunction in end-stage renal disease patients treated with hemodialysis.

BACKGROUND/AIMS: Steal syndrome is a well-known complication of arteriovenous shunt placement. Increased frequency of Raynaud's phenomenon (RP) especially concerning shunt limb is reported among hemodialysis (HD) patients. The aim of the study was to assess the relation of impairment of peripheral circulation diagnosed with cold stress test (CST) and thermography to the AV shunt location and markers of endothelial dysfunction in HD patients. METHODS: The study group comprised 21 patients (6 male, 15 female, mean age 32.6 +/- 15.0 years) treated with HD for a mean of 69 +/- 54 months. 10 healthy individuals (4 male, 6 female, mean age 38.6 +/- 14.7 years) served as controls. The diagnosis of RP was made upon the results of thermographic measurements during CST. Von Willebrand factor activity and antigen, endothelin-1 and plasma total homocysteine (tHcy) were measured in all subjects. RESULTS: RP was found significantly more often in HD patients than in controls: 11/21 vs. 1/10 (p = 0.04). RP occurred in both hands in 7/11 (64%) patients. tHcy was higher in HD patients than in the controls (31.7 +/- 13.9 vs. 10.9 +/- 3.2 microg/l, p < 0.0001). tHcy and von Willebrand factor antigen were significantly higher in the RP-positive than RP-negative patients or controls. CONCLUSION: Small vessel dysfunction diagnosed as positive RP is a frequent finding in HD patients. It seems that endothelial injury rather than AV shunt steal syndrome is responsible for development of RP in HD patients.