A Diagnostic Method Based on Active Thermography for the Degradation Assessment of Power Plant Boiler Tubes

Proper maintenance management of power infrastructure requires inspections, in order to gather knowledge about the facility's current condition. For this purpose, periodic diagnostic tests are carried out, not only to determine the current state, but to also predict future conditions, and subsequently plan for the scope of necessary repair work. Currently, in the case of heat screens of power boilers, the diagnostic process takes many days, is very expensive, and usually does not cover the entire screen area. Therefore, it is necessary to develop new, noninvasive diagnostic methods. This study presents the concept and research for an alternative method of locating places with excessive energy boiler screen degradation that require replacement. It was assumed that the new method should be fast, require no scaffolding assembly, and permit checking of the entire screen surface; this is unlike the methods used currently, which require manual checking of selected screen tubes. The proposed method is based on active thermography, in which heat flux is forced by the liquid flowing inside the screen. Tests were carried out based on a model of an axial-symmetric system in the form of a tube, with controlled reductions in the wall thickness. An experiment was carried out many times by recording the pipe surface temperature in many characteristic places (different thicknesses of the tube walls) with a thermal imaging camera. A temperature change was forced by a controlled flow of hot or cold water. The methods of analysis were proposed and verified, allowing firstly, detection of places with a reduced wall thickness, and secondly, estimations of the wall thickness (i.e., excessive degradation). For the best-proposed model (one of the four analyzed), all of the thickness changes were detected, and the limit error of thickness obtained was 0.3 mm.

Frequency and chaotic analysis of pulsatile motion of blood vessel wall related to aneurysm

BACKGROUND/OBJECTIVE

In this research, using our proposed method, clinical measurements on the pulsatile velocity of blood vessel wall were conducted for cases with aneurysm. Furthermore, detailed analyses of frequency and attracter of trajectories of velocity of blood vessel wall were conducted. On the basis of these analyses, we tried to conduct unified clarification of the change and disturbance of frequency and wave form of pulsatile velocity of blood vessel wall caused by blood vessel diseases such as aneurysm.

RESULTS

In the pulsation motion of blood vessel wall, vasomotion, which is a regular long periodic fluctuation of amplitude of the pulsatile velocity of blood vessel wall, was found to exist. Furthermore, the shift of its frequency into low frequency region was found to correspond well with an increase in I∗, an indicator of progressive degree of visco elasticity of blood vessel wall and it reflects the mechanical deterioration of blood vessel wall. This long periodic fluctuation of amplitude of the pulsatile velocity of blood vessel wall exists in the low frequency region that composes the frequency of the pulsatile velocity of blood vessel wall. On the other hand, wave forms in high frequency region that compose the frequency of pulsatile velocity of blood vessel wall were found to correspond well with each pulsatile velocity wave form of blood vessel wall itself and their disturbances caused by the existence of aneurysm was typically reflected in these wave forms.

CONCLUSION

By dividing frequencies that compose the frequency of the pulsatile velocity of blood vessel wall into low and high frequency regions and conducting analyses at each region, the possibility of accurate selective detection of blood vessel diseases such as mechanical deterioration of blood vessel wall (low frequency region) and morphological change of blood vessel wall that is aneurysm (high frequency region) was indicated.

Occurrence of Bacterial and Viral Pathogens in Common and Noninvasive Diagnostic Sampling from Parrots and Racing Pigeons in Slovenia

Airborne pathogens can cause infections within parrot (Psittaciformes) and pigeon (Columbiformes) holdings and, in the case of zoonoses, can even spread to humans. Air sampling is a useful, noninvasive method which can enhance the common sampling methods for detection of microorganisms in bird flocks. In this study, fecal and air samples were taken from four parrot holdings. Additionally, cloacal and oropharyngeal swabs as well as air samples were taken from 15 racing pigeon holdings. Parrots were examined for psittacine beak and feather disease virus (PBFDV), proventricular dilatation disease virus (PDDV), adenoviruses (AdVs), avian paramyxovirus type-1 (APMV-1), avian influenza virus (AIV), Chlamydia psittaci (CP), and Mycobacterium avium complex (MAC). MAC and AdVs were detected in three parrot holdings, CP was detected in two parrot holdings, and PBFDV and PDDV were each detected in one parrot holding. Pigeons were examined for the pigeon circovirus (PiCV), AdVs, and CP; PiCV and AdVs were detected in all investigated pigeon holdings and CP was detected in five pigeon holdings.