On an Algorithm for Multiperiodic Words

We consider an algorithm by Tijdeman and Zamboni constructing a word of length k thathas periods p1, . . . , pr, and the richest possible alphabet. We show that this algorithm can be easilystated and its correctness briefly proved using the class equivalence approach

Benchmark VERCORS 2022: mechanical response of the prestressed concrete containment wall to ambient conditions

The VERCORS benchmark was developed to provide a solid experimental basis for numerical modeling of concrete containment buildings (CCBs) to extend their lifespan. The goal of the first phase of the third benchmark is to present a blind prediction of CCB’s behavior across the whole lifespan and under periodic pressure tests. This paper summarizes the calibration of the material model based on the Microprestress-solidification (MPS) theory according to the provided laboratory experimental data. A special emphasis is given to the influence of the ambient conditions on drying creep and transient thermal creep of concrete and the calibration of the corresponding material parameters. These phenomena are studied on a representative section of the containment wall using weakly coupled thermo-hygro-mechanical analyses

Influence of oxygen and argon plasma treatment on wettability and surface morphology of polypropylene microfibers

The surface treatment of polypropylene microfibers by plasma processing in oxygen and argon was studied with the motivation to increase their cohesion with the cement matrix. By plasma treatment, it is possible to modify the surface of the microfibers mechanically, chemically or with a combination of both. The microfibers were modified using the reactive ion etching plasma system. The surface of the microfibers was modified by oxygen and argon plasma. The wettability of the microfibers was measured using the Packed Cell method. Furthermore, the weight of the microfibers before and after plasma modification was measured. Finally, the surface of the modified microfibers was examined by scanning electron microscopy. Almost all modifications of the microfiber surfaces were able to increase their wettability with water. The wettability of the oxygen plasma treated microfibers increased on average by about 11%, the wettability of the argon plasma treated microfibers increased on average by about 6% compared to the fibers without modification. The mechanical effect of plasma treatment was proven only for microfibers modified by oxygen plasma

HYDRATION OF PLASMA-TREATED ALUMOSILICATE BINDERS

Plasma treatment offers several applications in material science. In this research, the potential of plasma treatment is explored on the hydration of hydrophilic CNT-enriched cement and hydrophilic fly ash. The evolution of the hydration heat and the compressive strength show that a hydrophilic surface slightly accelerates the early-age hydration kinetics, while the long-term properties remain unchanged

Effect of chromium on bainite transformation and microstructural evolution in austempered unconventional steels 42SiCr and 42SiMn

PING 2019 is organized with the support of funds for specific university research project SVK1-2019-002.Enrichment of austenite with carbon in the course of austempering is a fundamental mechanism which leads to incomplete bainite transformation. Higher carbon content in untransformed austenite, together with the presence of silicon, is understood to lead to stabilization of austenite. As a result, austenite does not decompose and carbide precipitates do not form which are otherwise present in conventional bainitic microstructures. Although evidence of the beneficial effects of silicon and carbon on austenite stabilization in unconventional CFB steels is irrefutable, the present experiments showed that an addition of chromium plays a very important role in achieving incomplete bainite transformation. This paper deals with the effect of the chromium level on bainite transformation and microstructural evolution in unconventional steels 42SiCr and 42SiMn during austempering

Direct Measurements of the Volume Flow Rate and Emissions in a Large Naturally Ventilated Building

The direct measurement of emissions from naturally ventilated dairy barns is challenging due to their large openings and the turbulent and unsteady airflow at the inlets and outlets. The aim of this study was to quantify the impacts of the number and positions of sensors on the estimation of volume flow rate and emissions. High resolution measurements of a naturally ventilated scaled building model in an atmospheric boundary layer wind tunnel were done. Tracer gas was released inside the model and measured at the outlet area, using a fast flame ionization detector (FFID). Additionally, the normal velocity on the area was measured using laser Doppler anemometry (LDA). In total, for a matrix of 65 × 4 sensor positions, the mean normal velocities and the mean concentrations were measured and used to calculate the volume flow rate and the emissions. This dataset was used as a reference to assess the accuracy while systematically reducing the number of sensors and varying the positions of them. The results showed systematic errors in the emission estimation up to +97%, when measurements of concentration and velocity were done at one constant height. This error could be lowered under 5%, when the concentrations were measured as a vertical composite sample

Resonant transport in a highly conducting single molecular junction via metal-metal covalent bond

Achieving highly transmitting molecular junctions through resonant transport at low bias is key to the next-generation low-power molecular devices. Although, resonant transport in molecular junctions was observed by connecting a molecule between the metal electrodes via chemical anchors by applying a high source-drain bias (> 1V), the conductance was limited to < 0.1 G$_0$, G$_0$ being the quantum of conductance. Here, we report electronic transport measurements by directly connecting a Ferrocene molecule between Au electrodes at the ambient condition in a mechanically controllable break junction setup (MCBJ), revealing a conductance peak at ~ 0.2 G$_0$ in the conductance histogram. A similar experiment was repeated for Ferrocene terminated with amine (-NH2) and cyano (-CN) anchors, where conductance histograms exhibit an extended low conductance feature including the sharp high conductance peak, similar to pristine ferrocene. Statistical analysis of the data along with density functional theory-based transport calculation suggests the possible molecular conformation with a strong hybridization between the Au electrodes and Fe atom of Ferrocene molecule is responsible for a near-perfect transmission in the vicinity of the Fermi energy, leading to the resonant transport at a small applied bias (< 0.5V). Moreover, calculations including Van der Waals/dispersion corrections reveal a covalent like organometallic bonding between Au and the central Fe atom of Ferrocene, having bond energies of ~ 660 meV. Overall, our study not only demonstrates the realization of an air-stable highly transmitting molecular junction, but also provides an important insight about the nature of chemical bonding at the metal/organo-metallic interface.Comment: 23 pages, 6 figures, supplementary include

Wavelength-Diverse Polarization Modulators for Stokes Polarimetry

Information about the three-dimensional structure of solar magnetic fields is encoded in the polarized spectra of solar radiation by a host of physical processes. To extract this information, solar spectra must be obtained in a variety of magnetically sensitive spectral lines at high spatial, spectral, and temporal resolution with high precision. The need to observe many different spectral lines drives the development of Stokes polarimeters with a high degree of wavelength diversity. We present a new paradigm for the design of polarization modulators that operate over a wide wavelength range with near optimal polarimetric efficiency and are directly applicable to the next generation of multi-line Stokes polarimeters. These modulators are not achromatic in the usual sense because their polarimetric properties vary with wavelength, but they do so in an optimal way. Thus we refer to these modulators as polychromatic. We present here the theory behind polychromatic modulators, illustrate the concept with design examples, and present the performance properties of a prototype polychromatic modulator.Comment: 13 pages, 1 table, 5 figures, accepted for publication in Applied Optic

Tourism in Šumava: analysis of the equipment

Bakalářská práce je zaměřena na analýzu stavu vybraných turistických tras v chráněnékrajinné oblasti a národním parku Šumava. Jedná se o dvě trasy, konkrétně trasa Prášily -Prášilské jezero - Poledník a zpět, trasa Hamry- Černé jezero - Čertovo jezero - Železná Ruda.Předmětem zkoumání je analýza vybavenosti turisticky oblíbených míst, tras a míravybavenosti a dostupnosti služeb (parkování, občerstvení, odpočívadla, možnost ubytováníatd.). Pomocí metod GIS jsou zjištěné nedostatky zaneseny do map. Práce se dále zabývámožnostmi využití tras pro rodiny s dětmi (především přístupnost pro kočárky). Závěr práce jevěnován návrhům na zlepšení technického stavu jednotlivých tras a také jejich vybavenosti.The bachelor thesis is focused on analysis of disposition chosen hiking trails in protectedlandscape area and national park Šumava. It is trails Prášily - Prášilské jezero - Poledník andHamry- Černé jezero - Čertovo jezero -Železná Ruda. The subject of the research is the analysisof the facilities of tourist places and service availability (parking, restaurants, rest areas, thepossibility of accommodation, etc.). The identified shortcomings are entered to the maps byGIS methods. The thesis also deals with the possibilities for families with small kids(particularly access for prams). The conclusion is devoted to individual proposals to improvethe technical condition of the trails and also their facilities.