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Characterization of Božanov sandstone: pilot fracture tests
Kumpová, I.; Rozsypalová, I.; Vavro, Leona; Vavro, Martin; Keršner, Z.
2020 - Czech
The aim of this paper is a characterization ofsandstone from Božanov quarry near Broumov, Czech Republic,by means of the pilot fracture tests. Five drill-core test specimens withnominal diameter of 50mm and lengths of 100 and 125mmwere provided by an initial chevron type notch. Specimens were loaded in the configuration of the three-point bending as a displacement driven experimentusing LabTest 6.250 equipment in the laboratory of the Institute of Building Testing, Faculty of Civil Engineering, Brno University of Technology. The load versus displacement diagrams were used to quantify the basic mechanical fracture parameters of the studied sandstone: modulus of elasticity, fracture toughness, toughness, and specific fracture energy. Cíl příspěvku představuje charakterizacipískovce zlomu Božanov u Broumova,Česká republika,pomocí pilotních lomových testů. Pět zkušebních těles z jádrových vývrtůnominálního průměru 50mm a délek 100 a125mm bylo před testy opatřeno koncentrátorem napětí ve tvaru šípového vrubu a zatěžováno spožadavkem konstantního přírůstku posunu vkonfiguraci tříbodového ohybu lisemLabTest 6.250 vlaboratoři Ústavu stavebního zkušebnictví FAST VUT vBrně. Snímaných diagramů síla–posun bylo po jejich korekci využito kvyčíslení základních lomově-mechanických parametrůstudovaného pískovce: statického modulu pružnosti, lomové houževnatosti, houževnatostia specifické lomové energie. Keywords: Božanov sandstone; drill-core specimen; chevron notch; fracture test; load–displacement diagram Fulltext is available at external website.
Characterization of Božanov sandstone: pilot fracture tests

The aim of this paper is a characterization ofsandstone from Božanov quarry near Broumov, Czech Republic,by means of the pilot fracture tests. Five drill-core test specimens withnominal diameter of ...

Kumpová, I.; Rozsypalová, I.; Vavro, Leona; Vavro, Martin; Keršner, Z.
Ústav geoniky, 2020

Random response of a dynamic system under polynomial of a white noise
Náprstek, Jiří; Fischer, Cyril
2020 - English
Many types of external additive random excitation of dynamic systems admit to be modelled as a combination of powers of a Gaussian noise. Such a type of excitation produces a non-Gaussian response even if the dynamic system is linear and the excitation is additive only. Although the excitation as a whole is non-Gaussian, the problem can be transformed into the form of a linear system with an additive and multiplicative white noise excitation which _nally produces a non-Gaussian response. The general method of transformation, the respective FPK equation, basic stochastic moments of the response, and a demonstrative example are discussed. Keywords: non-Gaussian excitation; nonlinear filtering; Kronecker algebra Available at various institutes of the ASCR
Random response of a dynamic system under polynomial of a white noise

Many types of external additive random excitation of dynamic systems admit to be modelled as a combination of powers of a Gaussian noise. Such a type of excitation produces a non-Gaussian response ...

Náprstek, Jiří; Fischer, Cyril
Ústav teoretické a aplikované mechaniky, 2020

Scientific report. Sps_025: Ceramics B4C + 1Ti, 1800°C, 2 min
Kumpová, Ivana; Vopálenský, Michal
2020 - Czech
The aim of the measurement was to verify the feasibility of 3D computed tomography for observing structural details in samples of B4C - Ti ceramics with 1 % of Ti. Sample designated Sps_025: Keramika B4C + 1Ti, 1800°C, 2 min, in the form a cylinder with the diameter of 12 mm and the height of 10 mm was investigated by this method. Cílem práce bylo ověřit možnost pozorování stukturních detailů ve vzorcích B4C - Ti keramiky s 1 % titanu na základě 3D modelů z výpočetní tomografie. V laboratoři byl touto metodou zkoumán vzorek Sps_025: Keramika B4C + 1Ti, 1800°C, 2 min, ve tvaru válce o průměru 12 mm a výšce 10 mm. Keywords: X-ray tomography; boron carbide ceramics; characterization of microstructures Available at various institutes of the ASCR
Scientific report. Sps_025: Ceramics B4C + 1Ti, 1800°C, 2 min

The aim of the measurement was to verify the feasibility of 3D computed tomography for observing structural details in samples of B4C - Ti ceramics with 1 % of Ti. Sample designated Sps_025: Keramika ...

Kumpová, Ivana; Vopálenský, Michal
Ústav teoretické a aplikované mechaniky, 2020

Survey of mortars of the Romanesque chapel in the tower of Landštejn Castle
Válek, Jan; Skružná, Olga; Kozlovcev, Petr; Frankeová, Dita; Svoboda, Milan; Ševčík, Radek; Kotková, Kristýna
2020 - Czech
Four samples of floor mortars and two samples of plasters were analysed as a part of the survey in the Romanesque chapel located in the tower at Landštejn Castle. The aim was to characterize used raw materials, determine their ratio, characterize the porosity of mortars and compare mortars sorted to different phases of construction. V rámci průzkumu byly odebrány čtyři vzorky malt z podlahy a dva vzorky z omítek v prostoru románské kaple nacházející se ve věži na hradě Landštejn. Cílem byla charakterizace použitých surovin, stanovení jejich poměru, charakterizace porozity malt a porovnání malt z jednotlivých stavebních fází. Keywords: cultural heritage; Romanesque mortars; natural hydraulic lime; renders; floor mortars Available at various institutes of the ASCR
Survey of mortars of the Romanesque chapel in the tower of Landštejn Castle

Four samples of floor mortars and two samples of plasters were analysed as a part of the survey in the Romanesque chapel located in the tower at Landštejn Castle. The aim was to characterize used raw ...

Válek, Jan; Skružná, Olga; Kozlovcev, Petr; Frankeová, Dita; Svoboda, Milan; Ševčík, Radek; Kotková, Kristýna
Ústav teoretické a aplikované mechaniky, 2020

The scalar-valued score functions of continuous probability distribution
Fabián, Zdeněk
2019 - English
In this report we give theoretical basis of probability theory of continuous random variables based on scalar valued score functions. We maintain consistently the following point of view: It is not the observed value, which is to be used in probabilistic and statistical considerations, but its 'treated form', the value of the scalar-valued score function of distribution of the assumed model. Actually, the opinion that an observed value of random variable should be 'treated' with respect to underlying model is one of main ideas of the inference based on likelihood in classical statistics. However, a vector nature of Fisher score functions of classical statistics does not enable a consistent use of this point of view. Instead, various inference functions are suggested and used in solutions of various statistical problems. Inference function of this report is the scalar-valued score function of distribution. Keywords: Shortcomings of probability theory; Scalar-valued score functions; Characteristics of continous random variables; Parametric estimation; Transformed distributions; Skew-symmetric distributions Available at various institutes of the ASCR
The scalar-valued score functions of continuous probability distribution

In this report we give theoretical basis of probability theory of continuous random variables based on scalar valued score functions. We maintain consistently the following point of view: It is not ...

Fabián, Zdeněk
Ústav informatiky, 2019

Probability density determination by means of Gibbs entropy probability density
Náprstek, Jiří; Fischer, Cyril
2019 - English
A method of random response investigation of a nonlinear dynam-ical system is discussed. In particular, the solution of the probability density of a single/multi-degree of freedom (SDOF/MDOF) system response is investigated. Multiple stable equilibrium states with possible jumps of the snap-through type among them are considered. The system is Hamiltonian with weak damping excited by a set of non-stationary Gaussian white noises. The solution, which is based on the Gibbs principle of the maximum entropy of probability, can be employed in various branches of engineering. The search for the extreme of the Gibbs entropy functional is formulated as a constrained optimization problem. The secondary constraints follow from the Fokker-Planck equation (FPE) for the system considered or from the system of ordinary di_erential equations for the stochastic moments of the response derived from the relevant FPE Keywords: Fokker-Planck equation; Gibbs entropy functional; maximum entropy; probability density principle Available at various institutes of the ASCR
Probability density determination by means of Gibbs entropy probability density

A method of random response investigation of a nonlinear dynam-ical system is discussed. In particular, the solution of the probability density of a single/multi-degree of freedom (SDOF/MDOF) system ...

Náprstek, Jiří; Fischer, Cyril
Ústav teoretické a aplikované mechaniky, 2019

Laser-generated nanoparticles to change physical properties of solids, liquids and gases
Torrisi, Alfio; Cutroneo, Mariapompea; Ceccio, Giovanni; Cannavó, Antonino; Horák, Pavel; Torrisi, L.; Vacík, Jiří
2019 - English
Synthesis of nanoparticles was possible employing a Nd: YAG pulsed laser at fundamental harmonic. The production of nanoparticles in water depends mainly on the laser parameters (pulse duration, energy, wavelength), the irradiation conditions (focal spot, repetition rate, irradiation time) and the medium where the ablation occurs (solid target, water, solution concentration). The nanoparticles can be introduced in solids, liquids or gases to change many physical characteristics. The optical properties of polymers and solutions, the wetting ability of liquids, the electron density of laser-generated plasma, represent some examples that can be controlled by the concentration of metallic nanoparticles (Au, Ag, Ti, Cu). Some bio-medical applications will be presented and discussed. Keywords: bio-medical applications; laser; nanoparticles Available at various institutes of the ASCR
Laser-generated nanoparticles to change physical properties of solids, liquids and gases

Synthesis of nanoparticles was possible employing a Nd: YAG pulsed laser at fundamental harmonic. The production of nanoparticles in water depends mainly on the laser parameters (pulse duration, ...

Torrisi, Alfio; Cutroneo, Mariapompea; Ceccio, Giovanni; Cannavó, Antonino; Horák, Pavel; Torrisi, L.; Vacík, Jiří
Ústav jaderné fyziky, 2019

Bolts loading in the stronly stressed rock mass
Waclawik, Petr; Sahendra, Ram; Šňupárek, Richard
2019 - Czech
The trial test of new mining method “Roadway-Pillar” was finished at the underground coal mine – ČSM Mine. The wide ranging monitoring was focused on the load bearing capacity of coal pillars and strata deformation changes induced by the roadway-pillar mining method. The results of monitoring allowed bolts loading and loading characteristics to be described. Further, an attempt is made to understand the rock bolt loading characteristics at different stages of rib dilation using numerical modelling with the available properties of rock mass and reinforcement for the studied site. Elastic and Mohr Coulomb strain-softening constitutive models are considered in FLAC3D to evaluate the performance of the rock bolts. Při zkušebním provozu modifikované metody komora-pilíř s ponechanými stabilními pilíři, nazvané chodba-pilíř byla na Dole ČSM použita svorníková výztuž stropu a boků chodeb (stěn ponechaných pilířů). Zatížení a deformace svorníků byly měřeny v rámci rozsáhlého geotechnického monitoringu [1,2]. Následně bylo použito matematického modelování v softwaru Itasca FLAC3D [3] pro lepší objasnění zatěžovacích charakteristik svorníkové výztuže. Keywords: Roadway-Pillar mining method; ČSM Mine; coal pillars Available in a digital repository NRGL
Bolts loading in the stronly stressed rock mass

The trial test of new mining method “Roadway-Pillar” was finished at the underground coal mine – ČSM Mine. The wide ranging monitoring was focused on the load bearing capacity of coal pillars and ...

Waclawik, Petr; Sahendra, Ram; Šňupárek, Richard
Ústav geoniky, 2019

Moving dynamic test loads for road bridges - a case study
Bayer, Jan; Urushadze, Shota
2019 - English
Two types of dynamic testing load for bridges - driving sprung mass and driving impulse load - areexamined from the drive-by identification point of view. Numerical studies in ANSYS using contact elements and in MATLAB using a modal solution together with coupling force were performed. Equations for the estimation of the impulse load caused by a rolling cogwheel were suggested. The experiments confirmed that a driving impulse load is more efficient in exciting bridge vibrations. This, together with the fact that impulse loading is not sensitive to surface roughness, leads to the conclusion that, as a method for bridge health monitoring, impulse loading is more promising than using a driving sprung mass Keywords: drive-by identification; bridge testing; moving sprung mass; impulse loading; vibration measurements; laboratory experiments Available at various institutes of the ASCR
Moving dynamic test loads for road bridges - a case study

Two types of dynamic testing load for bridges - driving sprung mass and driving impulse load - areexamined from the drive-by identification point of view. Numerical studies in ANSYS using contact ...

Bayer, Jan; Urushadze, Shota
Ústav teoretické a aplikované mechaniky, 2019

Shaanxi 2018 - First great discoveries
Motyčka, Z.; Filippi, Michal
2019 - Czech
Keywords: Shaanxi 2018 expedition; speleology; caves Available at various institutes of the ASCR
Shaanxi 2018 - First great discoveries

Motyčka, Z.; Filippi, Michal
Geologický ústav, 2019

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