Novel software for medical and technical Thermal Object Identification (TOI) using dynamic temperature measurements by fast IR cameras

This paper presents a thermal analysis and methodology of thermal parameters identification of thermal multilayer structures using thermographic measurements after dynamic heating (or cooling) the investigated objects. During the thermal transient process, thermal images are recorded, with the highest possible frame rate of the camera. Then, temperature and power signals are transformed into the frequency domain, to get finally the thermal time constants distribution corresponding to the thermal parameters of the structure. A brief description of TOI program developed in MATLAB environment as well as the exemplary identifications of 2 different thermal objects are shown

Wpływ efektów geometrycznych na rozkład temperatury w narożnikach ścian budynków

Thermographic measurements on a wall of a building show clearly a decrease of temperature in the neighborhood of a corner. The same problem has been numerically modelled by taking thermal conduction inside the wall and convection on both sides into account. The modelling confirms the experimental measurements. A simple physical explanation is that a corner provides more "material" for thermal conduction than a flat wall so that the temperature at the inside is lower. The cooling surface outside is larger then inside the corner, which results in higher heat transfer. The opposite phenomenon is observed at the outside of a building. The paper is mainly devoted to camera operators making thermal insulation inspections frequently. In many practical cases the reports contain the wrong interpretation of the effect presented in this paper.Pomiary termowizyjne wewnątrz pomieszczeń budynków zazwyczaj pokazują spadek wartości temperatury w okolicy narożników. Ten problem termiczny został zbadany na drodze modelowania transferu energii przy uwzględnieniu konwekcyjnego przejmowania ciepła po obu stronach przegrody. Wyniki modelowania potwierdziły wyniki eksperymentów. Spadek wartości temperatury w narożach budynków jest zawsze obecny i wynika z większej masy przegrody i innej powierzchni przejmowania ciepła po obu jej stronach, a co za tym idzie zwiększonej wymiany ciepła na zewnątrz przegrody. Jak wykazały symulacje i pomiary wartość temperatury w narożniku może obniżyć się nawet o 20% w porównaniu w temperaturą na ścianie. Należy podkreślić, że przy przepływie ciepła do wewnątrz budynku efekt ten skutkuje wzrostem wartości temperatury w narożniku. Praca została przedstawiona głównie dla praktyków, którzy stosują termowizję do badań stanu izolacji w budownictwie. Często zdarza się, że niektórzy operatorzy kamer termowizyjnych niewłaściwie interpretują spadek wartości temperatury w narożnikach. Ich wnioski sugerują brak izolacji w narożniku, co nie zawsze jest prawdą

Convection and radiation cooling of overhead power lines - laboratory verification using thermography

The thermal behavior of overhead power lines depends upon physical parameters, such as surface emissivity and line dimensions, as well as weather conditions. In this paper, the results of the convection and radiation cooling of a conductor that simulate a power line are presented. Laboratory experiments were conducted and the results were compared with the data obtained using empirical formulae from the literature. Both the laminar and the turbulent airflow were investigated

Zastosowanie impedancji termicznej do modelowania cieplnych problemów odwrotnych kabli energetycznych

This paper presents the inverse heat transfer modeling in applications to the power cables. In order to simplify the calculations, the inverse modeling implements thermal simulations in frequency domain. Due to the cylindrical summery of the power cable, this model has an analytical solution, which simplifies using Bessel functions. The inverse model allows estimating the thermal parameters of the material the cable is made of. It can be used for defect detection and aging of the cable. The model was made in Matlab®, and compared with the results obtained from COMSOL® simulation software.W pracy przedstawiono zastosowanie modelowania cieplnych zjawisk odwrotnych do wyznaczania wartości parametrów termicznych kabli energetycznych. W procesie modelowania odwrotnego struktury wykorzystano model w dziedzinie częstotliwości, który dla struktury o symetrii cylindrycznej ma rozwiązanie analityczne przy użyciu funkcji Bessela. Model termiczny wraz z optymalizacją opracowano w programie Matlab®. Wyniki modelowania odwrotnego zweryfikowano rezultatami uzyskanymi z symulacji 3D wykonanych za pomocą oprogramowania COMSOL® oraz za pomocą danych pomiarowych, uzyskanych z kamery termowizyjnej. Opracowana metoda może być wykorzystana w praktyce do oceny stanu kabli energetycznych, ich zużycia, do wykrywania defektów związanych np. z korozją oraz do oszacowania warunków odprowadzania ciepła z kabli do otoczenia. W konsekwencji na podstawie wyników termowizyjnych można wyuczyć wartość impedancji termicznej kabla, co pozwoli oszacować maksymalną wartość temperatury w określonych warunkach pracy. Na obecnym etapie badań wykonano model kabla z litego materiału. Kolejnym krokiem będzie opracowanie modelu kabla wielowarstwowego, w tym z izolacją o małej przewodności cieplnej

A new software tool for transient thermal analysis based on fast IR camera temperature measurement

A new software tool for transient thermal analysis based on thermographic measurement of temperature is presented. In the proposed approach, temperature change after applying or removing power can be measured by a thermal camera or any contact temperature sensor. The software calculates thermal impedance in frequency domain and represents it in the form of the Nyquist plot. In addition, thermal time constant spectrum and cumulative structure function are evaluated. The software was developed in Matlab environment using in-built procedures for transfer function estimation. For the validation of the proposed tool, the results are compared with ones obtained using commercially available software

Thermal measurements of silicon integrated spiral inductors

Spiralne cewki scalone stanowią szczególny przypadek połączenia wewnątrzukładowego w układach scalonych. Pozwalają na bezpośrednią integrację indukcyjności w strukturach półprzewodnikowych, w standardowych technologiach CMOS/BiCMOS, bez konieczności wykonywania dodatkowych procesów technologicznych, dodatkowych fotomasek, a tym samym, bez zwiększania kosztów produkcji. W niniejszym artykule przedstawiono wyniki badań termowizyjnych spiralnych pojedynczej spiralnej cewki scalonej w technologii krzemowej i ich porównanie z wynikami symulacji.Spiral inductors are a special case of on-chip interconnects used in integrated circuits. They enable direct integration of inductances in semiconductor structures, in standard CMOS/BiCMOS technologies, without the need of additional technological processes, additional photomasks, thus without increase in ICs production costs. Because of their relatively large sizes compared to other elements integrated on a semiconductor wafer, spiral inductors can became a source of nonnegligible interferences for neighboring circuits located on the same semiconductor structure. According to the Joule-Lenz law, a current flowing through a metal produces heat. A spiral inductor is a metal interconnect conveying current, thus one can expect that the current flowing through the spiral will heat it, changing its series resistance and changing one of the inductor key design parameters - its quality factor Q. The neighboring circuits can also be affected. So far there have hardly been any publications dealing with that subject. The goal of the research was to investigate the thermal behavior of silicon integrated spiral inductors under current stress. In the introduction, an overview of spiral inductors is presented, including their typical geometries, dimensions and applications. The second section of the paper discusses the problems of silicon integrated spiral inductor model-ing. Next, in the third section there are given the results of temperature measurements of one of the spiral inductors integrated in test circuits. A MWIR camera with a cooled InSb 640x512 pixel detector matrix was used. The measurements are compared with simulation results. The fourth section presents the conclusions drawn from the measurement results. The measurement setup used allowed the imaging of a single spiral inductor, while only a general view of the test circuit was obtained form the previous results, without the possibility to discern a single, individual spiral inductor. It is shown that there is a good agreement between the simulations and measurements. Further investigations will be required to overcome the problems encountered during the measurements, such as influence of the on-wafer probes, the order of magnitude emissivity difference between the silicon substrate and aluminum interconnects. More complicated spiral geometries will have to be investigated, especially micromachined spiral inductors, in which the inductor is suspended, and typically connected to the rest of the integrated circuit only with 4 narrow SiO2 made bridges

Various applications of complex thermal impedance for transient and AC heat transfer analysis

This paper presents the concept and three practical examples of using complex thermal impedance for characterisation different thermal objects. The first problem describes estimation time shift between power and temperature in electric distribution systems with non-sinusoidal currents. The second example discussed here, shows the estimation of power losses distribution in the magnetic punched ferromagnetic strips. The third application presents the inverse thermal modelling of 3-layer biomedical objects (tissues) to estimate the thermal parameters. More details of the presented problems are in the appropriate papers of the authors referenced here

Conditioning attenuates kidney and heart injury in rats following transient suprarenal occlusion of the abdominal aorta

Suprarenal aortic clamping during abdominal aortic aneurysm (AAA) repair results in ischemia-reperfusion injury (IRI) in local (i.e. kidney) and distant (i.e. heart) tissue. To investigate perioperative approaches that mitigate IRI-induced tissue damage, Wistar rats underwent suprarenal aortic clamping either alone or in combination with short cycles of ischemic conditioning before and/or after clamping. Serum analysis revealed significant reduction in key biochemical parameters reflecting decreased tissue damage at systemic level and improved renal function in conditioned groups compared to controls (p < 0.05), which was corroborated by histolopathological evaluation. Importantly, the levels of DNA damage, as reflected by the biomarkers 8-oxo-G, γH2AX and pATM were reduced in conditioned versus non-conditioned cases. In this setting, NADPH oxidase, a source of free radicals, decreased in the myocardium of conditioned cases. Of note, administration of 5-HD and 8-SPT blocking key protective signaling routes abrogated the salutary effect of conditioning. To further understand the non-targeted effect of IRI on the heart, it was noted that serum TGF-β1 levels decreased in conditioned groups, whereas this difference was eliminated after 5-HD and 8-SPT administration. Collectively, conditioning strategies reduced both renal and myocardial injury. Additionally, the present study highlights TGF-β1 as an attractive target for manipulation in this context. © 2020, The Author(s)