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COMPUTER SIMULATION STUDY OF THE STABILITY OF UNDERACTUATED BIPEDAL ROBOT MODELS (motivated by Griffin and Grizzle, 2017)
Polach, P.; Anderle, Milan; Zezula, Pavel; Papáček, Štěpán
2023 - anglický
A key feature for bipedal walkers (robots and humans as well) is their stability or disturbance rejection defined as the ability to deal with unexpected disturbances. The paper by Griffin and Grizzle (2017) have significantly contributed to the shift from flat ground to slopes and steps when evaluating the walking efficiency of their robots. Similarly, in this contribution, based on the appropriate model of robot dynamics and control law, we examine the stability of walking-without-falling for different ground perturbations for a threelink compass gait walker. I.e., we perform the sensitivity analysis of the walking stability of underactuated bipedal walker with respect to certain disturbation using the alaska/MultibodyDynamics simulation tool.
Klíčová slova:
Mechatronics; Bipedal robot; Multibody dynamics; Acrobot; Control applications
Dokument je dostupný na externích webových stránkách.
COMPUTER SIMULATION STUDY OF THE STABILITY OF UNDERACTUATED BIPEDAL ROBOT MODELS (motivated by Griffin and Grizzle, 2017)
A key feature for bipedal walkers (robots and humans as well) is their stability or disturbance rejection defined as the ability to deal with unexpected disturbances. The paper by Griffin and Grizzle ...
Souvislost mezi principem nejmenší akce a termodynamickou podmínkou stability
Maršík, František; Trávníček, Zdeněk; Antošová, Zuzana
2023 - anglický
The extended principle is formulated for a material point (M.P.) X, which has nonzero mass, temperature, and trajectory x(X,t). The Lagrangian of this variation principle is equal to the kinetic energy from which, the internal energy of the material point (which depends on the entropy) and the additional energy caused by the frictional force are subtracted. The relation between the inertial force and the entropy gradient is found and the gravitational force is completely replaced by the entropy gradient. Thanks to the mentioned properties of the total enthalpy, the Thermodynamic criterion of stability of the state of M.P., is formulated.
Klíčová slova:
principle of the least action; thermodynamic stability condition; annular swirl flow
Dokument je dostupný na externích webových stránkách.
Souvislost mezi principem nejmenší akce a termodynamickou podmínkou stability
The extended principle is formulated for a material point (M.P.) X, which has nonzero mass, temperature, and trajectory x(X,t). The Lagrangian of this variation principle is equal to the kinetic ...
Texture Spectral Similarity Criteria Comparison
Havlíček, Michal; Haindl, Michal
2023 - anglický
Criteria capable of texture spectral similarity evaluation are presented and compared. From the fifteen evaluated criteria, only four criteria guarantee zero or minimal spectral ranking errors. Such criteria can support texture modeling algorithms by comparing the modeled texture with corresponding synthetic simulations. Another possible application is the development of texture retrieval, classification, or texture acquisition system. These criteria thoroughly test monotonicity and mutual correlation on specifically designed extensive monotonously degrading experiments.
Klíčová slova:
Texture Comparison; Texture Modeling; Texture Retrieval; Texture Classification; Texture Acquisition
Dokument je dostupný na externích webových stránkách.
Texture Spectral Similarity Criteria Comparison
Criteria capable of texture spectral similarity evaluation are presented and compared. From the fifteen evaluated criteria, only four criteria guarantee zero or minimal spectral ranking errors. Such ...
Statistical Method Selection Matters: Vanilla Methods in Regression May Yield Misleading Results
Kalina, Jan
2023 - anglický
The primary aim of this work is to illustrate the importance of the choice of the appropriate methods for the statistical analysis of economic data. Typically, there exist several alternative versions of common statistical methods for every statistical modeling task\nand the most habitually used (“vanilla”) versions may yield rather misleading results in nonstandard situations. Linear regression is considered here as the most fundamental econometric model. First, the analysis of a world tourism dataset is presented, where the number of international arrivals is modeled for 140 countries of the world as a response of 14 pillars (indicators) of the Travel and Tourism Competitiveness Index. Heteroscedasticity is clearly recognized in the dataset. However, the Aitken estimator, which would be the standard remedy in such a situation, is revealed here to be very inappropriate. Regression quantiles represent a much more suitable solution here. The second illustration with artificial data reveals standard regression quantiles to be unsuitable for data contaminated by outlying values. Their recently proposed robust version turns out to be much more appropriate. Both\nillustrations reveal that choosing suitable methods represent an important (and often difficult) part of the analysis of economic data.
Klíčová slova:
linear regression; assumptions; non-standard situations; robustness; diagnostics
Dokument je dostupný na externích webových stránkách.
Statistical Method Selection Matters: Vanilla Methods in Regression May Yield Misleading Results
The primary aim of this work is to illustrate the importance of the choice of the appropriate methods for the statistical analysis of economic data. Typically, there exist several alternative versions ...
Teplotní režim lesních horských půd
Dohnal, M.; Votrubová, J.; Mazúchová, R.; Blunár, P.; Tesař, Miroslav
2023 - český
S postupující automatizací, digitalizací a lepší dostupností pokročilých meteorologických a hydrologických přístrojů pro kontinuální sledování malých povodí jsou metody a postupy vycházející z bilance energie stále častěji vyhodnocovány v subdenním časovém kroku. V těchto případech již není možné dostupnou energii ztotožnit s čistou radiací a zanedbat tok tepla do půdy. Nevhodně zavedené předpoklady o velikosti toku tepla do půdy nebo použití příliš zjednodušených výpočetních postupů k jeho určení, vnášejí do zdánlivě přesnějších, ale ve skutečnosti pouze v čase podrobnějších, výpočtů značné nejistoty. Monitoring teplotního režimu půd a toků tepla do půdy, tak má velký význam pro ověření používaných výpočetních postupů a lepší pochopení omezení plynoucích z dlouhodobě využívaných předpokladů. Contribution deals with the monitoring of the temperature regime of forest soils and the soil heat flux at small mountainous basins Liz in the Šumava Mts. and Uhlířská in the Jizera Mts. Soil temperatures are measured with the help of soil moisture meters (Pt100 at Liz basin and CS107 at Uhlířská basin), the soil heat flux is measured with the use of the sensor Hukseflux HFP01. Measured results were statistically evaluated, the analysis of the consistence of the measurement was done and cumulative soil heat fluxes were calculated for the individual hydrological years.
Klíčová slova:
soil temperature; heat flux; HUKSEFLUX; Liz catchment
Dokument je dostupný na externích webových stránkách.
Teplotní režim lesních horských půd
S postupující automatizací, digitalizací a lepší dostupností pokročilých meteorologických a hydrologických přístrojů pro kontinuální sledování malých povodí jsou metody a postupy vycházející z bilance ...
Organoruthenium glycomimetics as selective galectin-1 inhibitors
Hamala, Vojtěch
2023 - anglický
The prepared organoruthenium glycomimetics demonstrated sin gle unit nanomolar affinity to Gal-1 and over four orders of magnitude\nhigher selectivity to Gal-1 in comparison to Gal-3. The organoruthe nium galectin inhibitors were found to be nontoxic to both cancer and\nnoncancerous cell lines. Selected complexes showed an in vitro an timigratory effect against invasive cancer cell lines MDA-MB-231 and\nSK-OV-3.
Klíčová slova:
galectin inhibitors; glycomimetcs; carbohydrates
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Organoruthenium glycomimetics as selective galectin-1 inhibitors
The prepared organoruthenium glycomimetics demonstrated sin gle unit nanomolar affinity to Gal-1 and over four orders of magnitude\nhigher selectivity to Gal-1 in comparison to Gal-3. The organoruthe ...
Use of photoautotrophic microorganisms in bioremediation of surface waters
Mušálková, Petra
2023 - anglický
Extensive experimental work has been executed to examine suitability of the proposed approach. Throughout the experiments, phosphorus concentration in the media was measured spectrophotometrically, to confirm the amount of phosphorus uptake,\nthe intracellular phosphorus concentration was analyzed by ICP-OES spectrophotometry.\n
Klíčová slova:
photoautotrophic microorganisms; surface water; phosphorus; bioremediation
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Use of photoautotrophic microorganisms in bioremediation of surface waters
Extensive experimental work has been executed to examine suitability of the proposed approach. Throughout the experiments, phosphorus concentration in the media was measured spectrophotometrically, to ...
Investigation of recycling possibilities of discarded photovoltaic solar panels
Šperlich, Antonín
2023 - anglický
This work aims to find an economically effective and industrially feasible method of how to recycle discarded photovoltaic solar panels. Performed experiments determined the exact composition of photovoltaic solar panels and the advantages and disadvantages of the treatment mentioned in the literature. Results will be used for a full-scale industrial unit design for solar photovoltaic panels recycling.\n
Klíčová slova:
photovoltaic solar panels; recycling; experiments
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Investigation of recycling possibilities of discarded photovoltaic solar panels
This work aims to find an economically effective and industrially feasible method of how to recycle discarded photovoltaic solar panels. Performed experiments determined the exact composition of ...
The effect of meteorology and aerosol size distribution on light scattering properties at a rural background site in Central Europe
Suchánková, Lenka
2023 - anglický
The aim of this study is to characterize the light scattering properties of aerosols at the rural background site National Atmospheric\nObservatory Košetice (NAOK; 49°34’20.787”N, 15°4’48.155”E) in Central Europe, namely the coefficients of total light scattering (σsp) and backscattering (σbsp), the Ångström exponent (SAE), the backscattering ratio (b), and the asymmetry factor (g), with special attention to the influence of meteorology and aerosol size distribution on these properties. We measured σ𝑠𝑝 and σ𝑏𝑠𝑝 at three wavelengths (450, 550, and 700 nm) using the Integrating Nephelometer TSI 3563 (PM10 inlet). The measurements were performed from August 16, 2012 to December 31, 2019.
Klíčová slova:
properties aerosols; backscattering; measurements
Plné texty jsou dostupné v digitálním repozitáři NUŠL
The effect of meteorology and aerosol size distribution on light scattering properties at a rural background site in Central Europe
The aim of this study is to characterize the light scattering properties of aerosols at the rural background site National Atmospheric\nObservatory Košetice (NAOK; 49°34’20.787”N, 15°4’48.155”E) in ...
N-alkylation of a lysergic acid derivative under PTC conditions in a continuous arrangement using sonication
Jaklová, Natalie
2023 - anglický
This contribution focuses on the application of sonication to the synthesis of a methyl ester of the 1-methyl-10α-methoxydihydrolysergic acid (MeLUME).
Klíčová slova:
sonication; synthesis; methyl ester
Plné texty jsou dostupné v digitálním repozitáři NUŠL
N-alkylation of a lysergic acid derivative under PTC conditions in a continuous arrangement using sonication
This contribution focuses on the application of sonication to the synthesis of a methyl ester of the 1-methyl-10α-methoxydihydrolysergic acid (MeLUME).
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