Jiri Tesar

Jiri Tesar
University of West Bohemia · New Technologies - Research Centre

Ing. Ph.D.

About

28
Publications
2,540
Reads
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137
Citations
Additional affiliations
September 2006 - June 2014
University of West Bohemia
Position
  • PhD Student
Education
September 2001 - June 2006
University of West Bohemia
Field of study
  • Faculty of Applied Sciences, Department of Physics

Publications

Publications (28)
Conference Paper
Tesař, J., Švantner, M., Skála, J., Honnerová, P., Novák, M., Thermographic method for fatigue limit determination at cyclic loading - Measurement procedure overview and validation (2019) METAL 2019 - 28th International Conference on Metallurgy and Materials, Conference Proceedings, pp. 526-531. https://www.scopus.com/inward/record.uri?eid=2-s2.0-...
Article
Full-text available
An increase in surface absorptivity can be helpful with a number of laser heat treatment processes. This study examines the relationship between the surface condition and its influence on interaction with a laser beam. The aim of this paper is to examine the effect of the oxide layer pattern size on the absorption of IR radiation and the influence...
Article
In this paper, a new measurement system and a new approach in calculation for infrared (IR) radiation investigation in quasi-simultaneous transmission laser welding of plastics are presented. The measurement system is based on a MW/SWIR (medium-wave/short-wave IR) camera and optical filters narrowing the spectral region to SWIR. The measured signal...
Conference Paper
Infrared nondestructive testing (IRNDT) is an active thermography method for inspection of material-surface inhomogeneities or discontinuities. It is based on an excitation of an inspected sample and a detection of its thermal response by thermographic methods. The IRNDT is commonly used for an inspection of delaminations. However, it is also appli...
Conference Paper
Testing of material fatigue properties belongs to important material examinations. A standard fatigue testing is mostly a time-consuming and expensive experiment, among others due to a number of samples needed. Infrared thermography is a method for a noncontact temperature measurement. Thermographic methods can detect small temperature changes caus...
Conference Paper
Infrared nondestructive testing is an inspection method based on an external excitation of a measured sample and a thermographic analysis of its thermal response. It often uses advanced evaluation techniques based on temperature spatial and temporal changes. IRNDT is a suitable method for an inspection of thin samples, near-surface layers and crack...
Conference Paper
Active thermography and its approaches are introduced in this contribution. Possibilities of active thermography are demonstrated on two examples – inspection of steel walls and inspection of components at cyclic loading. Example of an inspection of a corrosion loss at rear side of steel walls by halogen lock-in and step/transient thermography is p...
Article
Full-text available
Silica–titania mixed oxides and composites have been broadly examined for their physical and catalytic properties, but titanium monoxide–silicon monoxide counterparts have yet drawn very little attention. Here we report that laser-induced processing of mixed silicon and titanium monoxides results in reactions yielding a nanostructured Ti/Si/O compo...
Conference Paper
Full-text available
Příspěvek se zabývá možnostmi využití infračervené termografie pro kontrolu, dia-gnostiku a řízení procesu v technologiích laserového svařování. V příspěvku je představen proces laserového svařování a metody inspekce pomocí infračervené termografie. Mož-nosti využití infračervené termografie jsou demonstrovány na příkladech termovizní kontro-ly při...
Article
Full-text available
This study examines the influence of surface condition on its interaction with a laser beam. The relation was tested on milled C45 steel samples with a different width of created oxide layer. The milled surface with roughness 1.6 was modified by the creation of oxide layer. The oxide layers were created by solid state pulsed laser with scanning opt...
Article
Thermally sprayed coatings can be remelted to improve their microstructure and functional properties. Among other remelting technologies, laser remelting has the advantage of precise control of the remelting process by suitably chosen parameters. It enables the remelting of the whole thickness of the coating and creation of a metallurgical bonding...
Article
Abstract A new single-side flash method for thermal diffusivity determination is presented. The method is based on a laser-flash pulse excitation and infrared thermography non-contact temperature measurement of a thermal response of a studied object. Using this method, the both excitation and measurement at one side (front side) of the studied obje...
Article
Industrial lasers are an expanding technology of welding and other materials processing. Lasers with optical scanning heads are often used, as these provide more versatility, accuracy, and speed. The output part of the scanning head is covered by a protective glass, which might get contaminated by various particles from the laser processing. This d...
Article
Full-text available
The improvement of surface properties such as laser hardening becomes very important in present manufacturing. Resulting laser hardening depth and surface hardness can be affected by changes in optical properties of material surface, that is, by absorptivity that gives the ratio between absorbed energy and incident laser energy. The surface changes...
Article
A study of temperature of a magnetron target was performed for the case of high power pulsed magnetron sputtering (HPPMS) of titanium thin films, using a water-cooled target and a hot target. Temporal evolution and spatial distribution of surface temperature were investigated. Temperature measurements were made by an infrared camera for target diam...
Article
Full-text available
New experimental results are obtained by coupling both time-resolved reflectivity and rapid infrared pyrometry under a hemispherical reactor. The heating source KrF laser beam (28 ns, 248 nm) is homogenized and as for probing, a CW He–Ne laser beam (10 mW, 633 nm) is used.Using both methods infrared pyrometry with an IR detector cooled with liquid...
Article
Full-text available
2D transient heat conduction model was created in COMSOL Multiphysics for the study of temperature change in material irradiated by KrF laser pulse (nanosecond flash front method). Simulations were made for thin films and for bulk materials. An analytical 1D model was created in MATLAB to determine thermal resistance between thin film and substrate...

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Projects

Projects (4)
Project
The project is focused on the research of thermodiagnostic methods using IR cameras as tools for non-contact and fast identification of people with increased temperature and at the same time tools aiming to ensure the national security and management of epidemic threats. Details at https://medical.labir.cz/en/ Main goal: - To learn from the COVID ‐ 19 epidemic and to prepare a solution for a functional system of reliable thermodiagnostics of people in the Czech Republic for future epidemic threats manifesting the increased temperature of those infected. Additional goals: - Practically verify the hypothesis of a more accurate determination of the internal temperature of the measured person coming from an external warmer/colder environment, using an IR camera with a more sophisticated evaluation of the temperature field distribution. - Practically verify the hypothesis of earlier diagnosis of the onset of the epidemic and monitoring of its course using IR cameras with advanced processing of time series thermograms of a large number of people. - Develop a methodology for the use of thermographic diagnostic tools in times of “peace”, at the beginning of the epidemic, in the ongoing epidemic, and in local outbreaks. - To pass on information about new possibilities of using thermal imaging systems to the components of the integrated rescue system and to train them for more efficient and effective provision of their tasks not only during the epidemic. - To acquaint the professional and general public with the results of research and development and thus ensure wider application of project results, strengthen cooperation with the components of the integrated rescue system and achieve an increase in the level of security of the state and citizens in case of epidemic threats in the future.
Project
An overview project of our laboratory made for sharing ideas, events, publications and our other activities. The project topics are mostly related to themography, thermographic testing, temperature measurement and some additional thinks connected with our "thermal" activities.
Project
• development and use of original methods for the fabrication of innovative devices based on laser material processing. Concretely, the methods developed must allow: Laser Surface Processing of functional nanostructures, Laser cutting, Laser drilling, Laser welding, Laser heat treatment, Laser cleaning… Different laser techniques such as Laser (ns, ps, and fs) Direct Write, Pulsed Laser Deposition (PLD) are used. • The main characterization techniques that I use consists of optical, morphological and spectroscopic analysis. • these studies falls within the contexts of industrial applications (main part of my work), but are also conducted for fundamental research.