National Repository of Grey Literature 64 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Methodology for long-term evaluation of transgenic plum cv. ´HoneySweet´ resistance against Plum pox virus: Certified methodology applied
Polák, Jaroslav ; Komínek, Petr ; Krška, Boris ; Jarošová, Jana
Methodology describes procedure of establishing the field trial with Biotech plum cv. ´HoneySweet´, growing the plants in the experimental orchard and evaluation of plum resistance against Plum pox virus infection, as well as against co-infection with other two viruses, Apple chlorotic leafspot virus and Prune dwarf virus.
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Methodology evaluation of GM plum (Prunus domestica L.) clone C5, its resistance to Plum pox virus, fruit quality and possible gene-flow of transgene to plants of genus Prunus: applied methodology with certification
Polák, Jaroslav ; Kumar, Jiban ; Krška, Boris ; Komínek, Petr ; Jarošová, Jana
The methodology presents resistance evaluation of Biotech plum clone C-5 (´HoneySweet´), as well as evaluation of its fruit quality (Prof. Krška and Ass. Prof. Polák), evaluation of symptoms on its fruits (Ass. Prof. Polák) and possible gene-flow of transgene to plants of genus Prunus (Dr. Komínek).
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LCF behaviour of 301LN steel: coarse-grained vs. UFG-bimodal structure
Man, Jiří ; Chlupová, Alice ; Kuběna, Ivo ; Kruml, Tomáš ; Man, O. ; Järvenpää, A. ; Karjalainen, L. P. ; Polák, Jaroslav
Low-cycle fatigue (LCF) behaviour of metastable austenitic 301LN steel with different grain sizes – coarse-grained (14 µm) and UFG (1.4 µm) with a grain bimodality – produced by reversion annealing (RA) was investigated. Symmetrical push-pull LCF tests were conducted on flat sheet specimens at room temperature with constant strain rate of 2×10–3 s–1 and constant total strain amplitude ranging from 0.4% to 0.8%. After completion of fatigue tests a ferritescope was adopted for quantitative assessment of volume fraction of deformation induced martensite (DIM). Microstructural changes, distribution and morphology of DIM in the volume of material were characterized at different scales by colour etching, TEM and EBSD techniques. Experimental data on microstructural changes are confronted with the stress-strain response and with the chemical heterogeneity present in the material.
Crack initiation in austenitic stainless steel sanicro 25 subjected to thermomechanical fatigue
Petráš, Roman ; Škorík, Viktor ; Polák, Jaroslav
Thermomechanical fatigue experiments were performed with austenitic stainless Sanicro 25 steel. Several amplitudes of mechanical strain in a wide temperature interval (250-700 °C) were applied to the specimens. Mechanical response was recorded and fatigue lives were obtained. Scanning electron microscopy combined with FIB technique was used to study the mechanism of crack initiation in in-phase and in out-of-phase thermomechanical cycling. Different mechanisms of the crack initiation were found in these two types of loading. During in-phase loading fatigue cracks start in grain boundaries by cracking of the oxide. Cracks grew preferentially along grain boundaries which resulted in rapid crack initiation and low fatigue life. In out-of-phase loading multiple cracks perpendicular to the stress axis developed only after sufficiently thick oxide layer was formed and cracked in low temperature loading half-cycle. The cracks in oxide allowed localized repeated oxidation and finally also cracking. The cracks grow transgranularly and result in longer fatigue life.
IN-SITU HIGH TEMPERATURE LOW CYCLE FATIGUE STUDY OF SURFACE TOPOGRAPHY EVOLUTION IN NICKEL SUPERALLOY
Petrenec, M. ; Polák, Jaroslav ; Šamořil, T. ; Dluhoš, J. ; Obrtlík, Karel
In-situ Low Cycle Fatigue test (LCF) at temperature 635 degrees C have been performed in Scanning Electron Microscope (SEM) equipped with Electron Backscatter Diffraction analysis (EBSD) on a small dog-bone-shaped specimen of cast Inconel 713LC superalloy. The aim of the work was to study early stage fatigue damage at high temperature by the observations of the characteristic surface relief evolution and crystallographic characterization changes by EBSD. The detail of slip bands shape was checked by FIB and AFM microscopes. The LCF test was conducted on GATAN stage with pre tilted position and constant stress amplitude of total cycle number of 20. The relief produced in the first cycle determines the other locations of the localized cyclic slip to the primary slip planes (111). The relief was modified in the next cycles but without forming additionally new slip traces in the primary system. Based on EBSD analysis before and after LCF, the orientation of two grains was changed which caused activation of second slip system. The damage mechanism evolution is closely connected with the cyclic strain localization to the persistent slip bands where the fatigue cracks were initiated.
A metodical approach for sanitation of grapevine cultivars using chemotherapy
Komínek, Petr ; Jandová, Barbora ; Komínková, Marcela ; Polák, Jaroslav
The guideline describe a method of grapevine cultivation in vitro and its sanitation from virus pathogens usinf Ribavirin. Large part of this guideline describe diagnostic protocols for estimation of healthy status of sanitated grapevines. The guideline is intended for laboratories dealing with sanitation and diagnostics of viral pathogens of grapevine cultivars and rootstocks. Further utilization can be done by the Ministry of Agriculture, Central Institute for Supervising and Testing in Agriculture and also by growers of grapevine.
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Usage of psychometrics in the organizational setting
Polák, Jaroslav ; Štikar, Jiří (referee) ; Bahbouh, Radvan (advisor)
Theoretical part of this work is supposed to serve as a basic handbook for those who are willing to use psychometric, respective psychological tests in the organizational setting. In the preliminary part there is briefly explained what psychometrics is, there is shown its historical development, arguments for its use, methods of calculating its economical effectiveness and areas of most common application of results based on psychometric testing in context with human resources management. Next part is concerned with basic abstract of category structure of psychometric methods and characterization of basic features that all tests should fulfill. Following part of this text is focused on practical issues regarding to use of psychometric test in the organizational setting - from creating clear conception, through job analysis, selection of suitable testing methods, test administration and scoring until their interpretation and giving feedback. Practical part is devoted to the validization research in conditions of an unnamed company. Basic aim of this research was to verify validity and justifiability of use of tests NMG1 (numerical critical reasoning test), VMG1 (verbal critical reasoning test) and OPQ32 (personality questionnaire) by SHL Company and of test RSPM (Raven standard progressive matrices) and to...
GRAIN REFINEMENT EFFECT ON FATIGUE PROPERTIES OF AUSTENITIC STAINLESS STEEL WITH DEFORMATION INDUCED MARTENSITE FORMATION
Chlupová, Alice ; Man, Jiří ; Polák, Jaroslav ; Škorík, Viktor ; Karjalainen, J.
Fatigue properties of metastable austenitic 301LN steel with coarse and ultrafine-grained microstructures were investigated at ambient temperature and the effect of grain refinement was evaluated. Two different microstructural states of material were introduced by different annealing conditions during special thermo-mechanical treatment. Fatigue life curves were obtained and compared for both coarse-grained and ultra-fine-grained states of austenitic stainless steel. Magnetic measurements before, during and after cyclic loading were performed to reveal structural changes, i.e. formation of deformation-induced martensite. Relationship between microstructure refinement, phase composition and fatigue properties was discussed.
Propagation of Fatigue Cracks under Shear Loading Modes II, III and II+III in the Near-Threshold Region
Vojtek, Tomáš ; Man, Jiří (referee) ; Polák, Jaroslav (referee) ; Pokluda, Jaroslav (advisor)
Práce je zaměřena na šíření únavových trhlin v módech II, III a II + III v prahové oblasti v kovových materiálech. Byly provedeny experimenty pro ARMCO železo, titan, nikl a austenitickou ocel na třech druzích vzorků pro zatěžování trhliny ve smykových módech. Byl použit zvláštní způsob vytváření iniciační trhliny, který eliminoval efekt zavírání trhliny na začátku smykového zatěžování. Ve všech zkoumaných materiálech byly efektivní prahové hodnoty v módu II přibližně 1,7 krát nižší než v módu III. Měřením úhlů lokálních odklonů a natočení lomových faset s použitím stereofotogrammetrie v SEM bylo usuzováno na tendenci trhliny k vyhýbání do lokálního módu I. Nejmenší úhly byly zjištěny u ARMCO železa pro trhliny v módech II i III, středně velké úhly u titanu a niklu a největší úhly (vyhnutí do čistého módu I) byly pozorovány u austenitické oceli. Tyto rozdíly lze vysvětlit různým počtem dostupných skluzových systémů v krystalových mřížkách daných materiálů. Poměry mezi naměřenými prahovými hodnotami v módu I, II a III byly srovnány s předpověďmi teoretických modelů. Byl navržen analytický vztah pro efektivní prahové hodnoty v módu II, který byl v dobré shodě s experimentálními výsledky. Pomocí efektivních prahových hodnot bylo vyčísleno kritérium pro vyhýbání do módu I, které vedlo ke kritickému úhlu odklonu 40° souvisejícímu s přechodem z lokálního smykového módu do otevíracího módu.
PROPAGATION OF LONG FATIGUE CRACKS IN AUSTENITIC STEEL UNDER SHEAR MODES II AND III
Holáň, Libor ; Man, Jiří (referee) ; Polák, Jaroslav (referee) ; Pokluda, Jaroslav (advisor)
This work is focused on the realization of experiment allowing simultaneous loading under mode II and III in a single circular specimen. Proposed experiment allowed to minimize crack closure during the cyclic loading and obtained values of thresholds of stress intensity range can be considered to be very close to effective values. This was attained by means of an unique experimental devices and procedure of preparation of pre-crack of specimen with circumferential notch, which was made of stainless austenitic steel. The obtained values were compared with theoretical models with the support of molecular dynamics and ab-anitio calculation. Based on observation was found out, that fatigue crack propagation is controlled by decohesion model in austenitic steel. The morphology of fracture surfaces was studied by means of optical chromatographie and 3D stereophotogrammetry, which allowed a comparison of created morphology under shear modes II and III. Morphology of fracture surface formed (static and cyclic loading) by pre-crack was also studied by means of selected roughness parameters. The mechanism of deflection (kink) of crack growth under mode II was defined.

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See also: similar author names
12 POLÁK, Jan
17 POLÁK, Jaroslav
2 Polák, Jakub
12 Polák, Jan
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3 Polák, Jiří
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1 Polák, Jozef
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