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Disappearing stepping stones: technological change and career paths
Kashkarov, Daniil; Artemev, V.
2024 - English
Which career paths lead workers towards high-skilled non-routine cognitive occupations? Using PSID data, we show that, for a significant share of workers, a career path towards non-routine cognitive occupations goes through middle-skilled routine occupations, with the majority going through a subset of routine cognitive occupations. We then argue that the decline in employment in routine cognitive occupations due to routine-biased technological change can negatively affect the chances of younger cohorts joining high-skilled occupations. To test this hypothesis, we develop a structural occupational choice model that endogenously generates realistic career paths and estimate it using PSID data and job ad data from three major US outlets covering the period from 1940 to 2000. Our estimations suggest that, on average, 6% of workers ending up in non-routine cognitive occupations use routine cognitive occupations as stepping stones that allow them to maintain and accumulate human capital and experience relevant for later employment in high-skilled occupations. A fall in employment opportunities in routine cognitive occupations over the period of the most intensive routine-biased technological change led to at least 1.37 million lost high-skilled workers who got stuck in less skilled occupations.
Keywords:
routine-biased technological change; occupational choice; human capital
Fulltext is available at external website.
Disappearing stepping stones: technological change and career paths
Which career paths lead workers towards high-skilled non-routine cognitive occupations? Using PSID data, we show that, for a significant share of workers, a career path towards non-routine cognitive ...
Numerical evaluation of mass-diffusive compressible fluids flows models
Bodnár, Tomáš; Fraunié, P.
2024 - English
This contribution presents first numerical tests of some recently published alternative models for solution of viscous compressible and nearly incompressible models. All models are solved by high resolution compact finite difference scheme with strong stability preserving RungeKutta time stepping. The two simple but challenging computational test cases are presented, based on the double-periodic shear layer and the Kelvin-Helmholtz instability. The obtained time-dependent flow fields are showing pronounced shear and vorticity layers being resolved by the standard as well as by the new mass-diffusive modified models. The preliminary results show that the new models are viable alternative to the well established classical models.
Keywords:
compressible Navier-Stokes; nearly incompressible flow; mass diffusion; compact finite-difference
Available in digital repository of the ASCR
Numerical evaluation of mass-diffusive compressible fluids flows models
This contribution presents first numerical tests of some recently published alternative models for solution of viscous compressible and nearly incompressible models. All models are solved by high ...
Motion of fluids in the moving domain
Nečasová, Šárka
2024 - English
It is a survay paper where the problem of the existence of weak solutions of compressible barotropic solutions in a moving bounded domain is studied.
Keywords:
compressible fluid; moving domain; weak solutions
Available in digital repository of the ASCR
Motion of fluids in the moving domain
It is a survay paper where the problem of the existence of weak solutions of compressible barotropic solutions in a moving bounded domain is studied.
Modification of cooling system for laboratory measurement of rotor blade vibration
Maturkanič, Dušan; Procházka, Pavel; Hodboď, Robert; Voronova, Evgeniya; Mekhalfia, Mohammed Lamine
2024 - English
Last year, the replacement of the turbine wheel model was completed in the Laboratory of Rotational Laser Vibrometry of the Institute of Thermomechanics AS CR, v.v.i. Based on previous experience and the expected higher operating load planned for the new wheel, the cooling system was modified at the same time. The paper describes the main effort in this direction and the results that clarify the previous damage of the measuring device.
Keywords:
blade; vibration; cooling system; measurement; laboratory
Available at various institutes of the ASCR
Modification of cooling system for laboratory measurement of rotor blade vibration
Last year, the replacement of the turbine wheel model was completed in the Laboratory of Rotational Laser Vibrometry of the Institute of Thermomechanics AS CR, v.v.i. Based on previous experience and ...
PROPERTIES OF NANOCRYSTALLINE FE-NI PARTICLES PREPARED BY THERMAL REDUCTION OF OXALATE PRECURSORS
Švábenská, Eva; Roupcová, Pavla; Havlíček, Lubomír; Schneeweiss, Oldřich
2024 - English
Recent technological advancements require development of cost-effective and high-performance magnets \nwhich ideally do not contain rare earth metals or noble metals. The promising candidates are Fe-Ni-based \nalloys, in particular, the Fe50Ni50 L10 phase (tetrataenite), which has a great perspective for producing hard \nmagnetic materials. Our study explores a promising method for preparing nanoparticles of Fe-Ni alloy from an \niron-nickel oxalate precursor. The coprecipitation method was employed to prepare oxalate precursors, \nfollowed by controlled thermal decomposition in a reducing hydrogen atmosphere. The morphology and \nproperties of the resulting particles were analysed using scanning electron microscopy (SEM) coupled with \nenergy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Mössbauer spectroscopy (MS), and \nmagnetic measurements.\nThe SEM analysis revealed that the particles have approximately cube-shaped unit cell morphology with a\nsize in a range of 1 - 2 μm. Upon annealing, the samples contain multiple phases with varying Fe-Ni content.\nMagnetic measurements confirmed the formation of magnetically suitable Fe-Ni phases in the samples after \nannealing. Mössbauer spectroscopy emerged as a highly effective method for characterizing individual phases \nof the Fe-Ni system.
Keywords:
Magnetic materials; thermal decomposition; Mössbauer spectroscopy
Available at various institutes of the ASCR
PROPERTIES OF NANOCRYSTALLINE FE-NI PARTICLES PREPARED BY THERMAL REDUCTION OF OXALATE PRECURSORS
Recent technological advancements require development of cost-effective and high-performance magnets \nwhich ideally do not contain rare earth metals or noble metals. The promising candidates are ...
DYNAMICS OF MACHINES AND MECHANICAL SYSTEMS WITH INTERACTIONS : PROCEEDINGS DYMAMESI 2024
Zolotarev, Igor; Pešek, Luděk; Kozień, M. S.
2024 - English
The aim of the DYMAMESI is to facilitate the exchange of up to date information and knowledge among specialists in structural and multibody dynamics, in coupled interacting systems as aero-elasticity, hydro-elasticity, biomechanics, systems with feedbacks and mechatronics. In 2023 will be hosted by Cracow University of Technology, Institute of Applied Mechanics, Section of Dynamics of Systems.
Keywords:
dynamics; vibrations of mechanical systems; vibrodiagnostics; energy transformations
Available at various institutes of the ASCR
DYNAMICS OF MACHINES AND MECHANICAL SYSTEMS WITH INTERACTIONS : PROCEEDINGS DYMAMESI 2024
The aim of the DYMAMESI is to facilitate the exchange of up to date information and knowledge among specialists in structural and multibody dynamics, in coupled interacting systems as aero-elasticity, ...
Some modifications of the limited-memory variable metric optimization methods
Vlček, Jan; Lukšan, Ladislav
2023 - English
Several modifications of the limited-memory variable metric (or quasi-Newton) line search methods for large scale unconstrained optimization are investigated. First the block version of the symmetric rank-one (SR1) update formula is derived in a similar way as for the block BFGS update in Vlˇcek and Lukˇsan (Numerical Algorithms 2019). The block SR1 formula is then modified to obtain an update which can reduce the required number of arithmetic operations per iteration. Since it usually violates the corresponding secant conditions, this update is combined with the shifting investigated in Vlˇcek and Lukˇsan (J. Comput. Appl. Math. 2006). Moreover, a new efficient way how to realize the limited-memory shifted BFGS method is proposed. For a class of methods based on the generalized shifted economy BFGS update, global convergence is established. A numerical comparison with the standard L-BFGS and BNS methods is given.
Keywords:
unconstrained minimization; variable metric methods; limited-memory methods; variationally derived methods; arithmetic operations reduction; global convergence
Available in a digital repository NRGL
Some modifications of the limited-memory variable metric optimization methods
Several modifications of the limited-memory variable metric (or quasi-Newton) line search methods for large scale unconstrained optimization are investigated. First the block version of the symmetric ...
Utilization of electrochemically induced cleavage of various sulfonimides
Salvadori, Karolína
2023 - English
In this work, we describe the unexpected electrochemical cleavage of sulfonimides, providing a direct pathway to corresponding sulfonamides. For this purpose, 16 substances were synthesized and tested, reflecting the influence of different electron effects of -SO2Ph-R substituents, and the impact of the number of nosyl units present in molecules. In the case of octakis-nosylated calixarenes, the electrochemical cleavage via direct potential-controlled electrolysis was compared with conventional organic synthetic procedures. After electrolysis, all prepared sulfonamides were isolated in excellent yields.
Keywords:
sulfonimides; green chemistry procedures; electrochemisty
Available in a digital repository NRGL
Utilization of electrochemically induced cleavage of various sulfonimides
In this work, we describe the unexpected electrochemical cleavage of sulfonimides, providing a direct pathway to corresponding sulfonamides. For this purpose, 16 substances were synthesized and ...
Green approach for the preparation of biosourced ionic liquids and the study of their thermodynamic properties\n
Souvenir Zafindrajaona, Mahasoa-Salina
2023 - English
This presentation will address a green approach to the synthesis of ionic liquids qualified as biosourced (monocatenar or bolaform systems) from specific agro-resources, according to several principles of green chemistry. As these solvents could be used to solubilize lignocellulosic biomass and/or extract bioactive compounds (from plant sourcing), the physicochemical characteristics (density, viscosity and heat capacity) of pure ILs or mixtures of IL/water must be determined. Preliminary results concerning this last point will be presented.
Keywords:
biosourced ionic liquids; lignocellulosic biomass; thermodynamic properties
Available in a digital repository NRGL
Green approach for the preparation of biosourced ionic liquids and the study of their thermodynamic properties\n
This presentation will address a green approach to the synthesis of ionic liquids qualified as biosourced (monocatenar or bolaform systems) from specific agro-resources, according to several ...
Cultivation of Limnospira maxima and utilization of its fresh biomass in human nutrition
Vásquez, Claudia
2023 - English
This work aims to enhance productivity, efficiency and sustainability of L. maxima cultivation as well as to determine the safe microbiological conditions for the nutritional use of fresh spirulina biomass. Various parameters such as light intensity, light spectral composition, temperature, pH, CO2, and culture media composition can be optimized. A series of experiments were performed to find the most suitable configuration to cultivate L. maxima, defined by cyanobacterium productivity and yield as well as other metabolites production such as phycocyanin (C-PC) and carotenoids.
Keywords:
Limnospira maxima; fresh biomass; human nutrition
Available in a digital repository NRGL
Cultivation of Limnospira maxima and utilization of its fresh biomass in human nutrition
This work aims to enhance productivity, efficiency and sustainability of L. maxima cultivation as well as to determine the safe microbiological conditions for the nutritional use of fresh spirulina ...
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