Scaling slowly rotating asteroids with stellar occultations

Context. As evidenced by recent survey results, the majority of asteroids are slow rotators (spin periods longer than 12 h), but lack spin and shape models because of selection bias. This bias is skewing our overall understanding of the spins, shapes, and sizes of asteroids, as well as of their other properties. Also, diameter determinations for large (>60 km) and medium-sized asteroids (between 30 and 60 km) often vary by over 30% for multiple reasons. Aims. Our long-term project is focused on a few tens of slow rotators with periods of up to 60 h. We aim to obtain their full light curves and reconstruct their spins and shapes. We also precisely scale the models, typically with an accuracy of a few percent. Methods. We used wide sets of dense light curves for spin and shape reconstructions via light-curve inversion. Precisely scaling them with thermal data was not possible here because of poor infrared datasets: large bodies tend to saturate in WISE mission detectors. Therefore, we recently also launched a special campaign among stellar occultation observers, both in order to scale these models and to verify the shape solutions, often allowing us to break the mirror pole ambiguity. Results. The presented scheme resulted in shape models for 16 slow rotators, most of them for the first time. Fitting them to chords from stellar occultation timings resolved previous inconsistencies in size determinations. For around half of the targets, this fitting also allowed us to identify a clearly preferred pole solution from the pair of two mirror pole solutions, thus removing the ambiguity inherent to light-curve inversion. We also address the influence of the uncertainty of the shape models on the derived diameters. Conclusions. Overall, our project has already provided reliable models for around 50 slow rotators. Such well-determined and scaled asteroid shapes will, for example, constitute a solid basis for precise density determinations when coupled with mass information. Spin and shape models in general continue to fill the gaps caused by various biases

The conduction of selected fruit products

Celem badań było określenie właściwości przewodnościowych wybranych przetworów owocowych oraz ustalenie wpływu rodzaju surowca i technologii otrzymywania na zmiany właściwości elektrycznych. Materiał do badań stanowiły moszcze i przeciery owocowe otrzymane metodą laboratoryjną. Wykazano, że moszcze z owoców jagodowych, ziarnkowych i pestkowych charakteryzowała niższa wartość impedancji w porównaniu z przecierami uzyskanymi z tych samych owoców. Przeciery i moszcze otrzymane z poszczególnych owoców (poza nielicznymi przypadkami) różniły się statystycznie istotnie pod względem wartości impedancji.The aim of the research was to determine the conductivity of selected fruit products and establish the kind of raw material and production technology on changes of electric properties. Puree fruit and fresh juice fruit obtained by laboratory method were the experimental material. The authors revealed that fresh juice fruit from berry fruit, stone fruit, grain fruit were characterised by lower impedance comparing with puree obtained from the same fruit. Fresh juice fruit and puree derived from particular fruit (except from selected cases) were statistically significant in terms of impedance

Numerical modelling of the structural layer of foil bearing

Łożyska foliowe dzięki swoim wielu zaletom znajdują w ostatnim czasie coraz więcej zastosowań. Dzisiejszy poziom wiedzy pozwala na modelowanie własności łożysk foliowych przede wszystkim na podstawie badań eksperymentalnych, gdyż dotychczas opracowane modele obliczeniowe nie pozwalają na otrzymanie wiarygodnych wyników. W niniejszej pracy przedstawiono wstępny etap prac nad modelowaniem strukturalnej warstwy nośnej łożyska foliowego. Opracowano model dyskretny fragmentu folii gładkiej i falistej oraz przeprowadzono symulację komputerową pracy takiego układu. Otrzymany model numeryczny został następnie zweryfikowany eksperymentalnie. Uzyskano dużą zgodność wyników symulacji i eksperymentu, co świadczy o dużej przydatności opracowanego modelu w przewidywaniu własności łożysk foliowych.Foil bearings fulfil most of the requirements of novel oil-free turbomachinery. Only the experimental investigation of foil bearings giving us the fundamental knowledge of their behaviour, because of the luck of good numerical models. This work presented the preliminary stage of numerical modelling of the structural layer of foil bearing. The FEM model of bump and top foil was prepared and mutual motion was analyzed. The results of FEM model were verified experimentally. A good agreement between numerical simulation and experiment was obtained

Conductive properties of wheat grain

W pracy podjęto badania, których celem było określenie właściwości przewodnościowych ziarna pszenicy w zależności od odmiany, wilgotności, wielkości ziarniaków oraz stosowanej częstotliwości prądu. Materiałem badawczym było ziarno czterech odmian pszenicy ozimej: Korweta, Juma, Mikon i Kobra. Ziarno sortowano na trzy frakcje: > 2,8 mm, 2,5-2,8 mm i 2,2-2,5 mm. Właściwości przewodnościowe niesortowanego ziarna (próba kontrolna) oraz jego trzech frakcji, o wilgotności 11% i 15%, badano używając miernika HP 4263B. Stosowano napięcie sinusoidalne 250 mV i cztery częstotliwości prądu: 100 Hz, 1 kHz, 10 kHz i 100 kHz. Wykonano pomiary impedancji, rezystancji, admitancji i konduktancji ziarna. Otrzymane wyniki badań poddano analizie statystycznej korzystając z programu STATISTICATM . Zmiany właściwości przewodnościowych ziarna zależały istotnie (p ≤ 0,05) od wszystkich badanych czynników, tj.: odmiany, wilgotności, wielkości ziarniaków oraz stosowanej częstotliwości prądu.The work aimed at determination of conductive properties of wheat grain as affected by variety, moisture, size of kernels and applied frequency of electric current. Wheat grain of four winter varieties: Korweta, Juma, Mikon, Kobra was used as the material for study. Grain was sized into three fractions: > 2,8 mm, 2,5-2,8 mm and 2,2-2,5 mm. Conductive properties of not sorted grain (control sample) and its three fractions, at moisture 11% and 15%, have been performed with the HP 4263B meter. Sinusoidal voltage of 250 mV and four frequencies of electric current: 100 Hz, 1 kHz, 10 kHz and 100 kHz were used. Measurements of impedance, resistance, admittance and conductance were made. Obtained results were subjected to statistical analysis with the use of STATISTICATM programme. Changes in conductive properties of grain significantly (p ≤ 0,05) depended on all of studied factors, i.e. variety, moisture, size of kernels and applied frequency of electric current

The effects of beef carcasses high voltage electrical stimulation and roasting methods on tenderness and water retention of beef

The aim of the study was to determine the effect of high voltage electrical stimulation (330 V, 17 Hz, 120 s) of beef half-carcass and heat treatment on tenderness and water holding capacity of meat. The experimental material was a semimembranosus muscle derived from Polish Holstein-Friesian heifers (n=12). In the experiment, a forced and natural air circulation ovens were used; the raw material was heated at 170ºC to obtain a final temperature from 55 to 80ºC inside the beef. Results showed that electrical stimulation improved tenderness of roasted beef, which was demonstrated in the decrease in the maximum shear force from 39 to 26%. The electrical stimulation had a negative effect on cooking losses during roasting and water content in the final product. It has also been shown that studied quality attributes of beef depends on the type of heat treatment. Beef prepared in forced air circulation oven, were characterized by lower water content and higher values of maximum shear and compression forces than those heated in natural air circulation ove

Design and performance study of a small-scale waste heat recovery turbine

The paper presents the design process of a radial-axial turbine working with SES36 working fluid. First, the mean-line design process is performed and then the geometry is developed. In the next stage the numerical verification is performed taking into account the real properties of the working fluid. The properties are implemented via a look-up table and by a modified Benedict-Webb-Rubin equation of state. The presented turbine is characterized by a very small stator outflow angle which is about 4.5◦ but despite this small value, the efficiency of the machine is relatively high and equal to about 88%. The influence of internal leakages has also been investigated

The symbiotic binary St 2-22: Orbital and stellar parameters and jet evolution following its 2019 outburst

Context. St 2-22 is a relatively poorly studied S-type symbiotic system that belongs to a small group of jet-producing systems as a result of disc accretion onto a white dwarf fed by its red giant companion. Aims. The goal of this paper is to analyse the nature and derive the basic parameters of St 2-22, and to follow the jet evolution. Methods. Photometric monitoring for over 16 yr and high-quality spectroscopic data enabled us to shed new light on its nature. The high-resolution SALT spectra and V Ic photometry obtained during and between the last two outbursts have been used to search for periodic changes, to derive spectroscopic orbits of both system components, and to study the outburst and jet evolution. Results. We present the orbital and stellar parameters of the system components. The orbital period is Porb = 918 ± 6d. The double-line spectroscopic orbits indicate the mass ratio $q = M_{\mathrm{g}} M_{\mathrm{h}}^{-1} = 3.50 \pm 0.53$, and the components masses Mgsin3i ∼ 2.35 M⊙ and Mhsin3i ∼ 0.67 M⊙. The orbit shows significant eccentricity, e = 0.16 ± 0.07. The orbital inclination is close to 70°. During outbursts, accelerating and decelerating jets are observed with changes in their radial velocity component in a range from ∼1500 up to nearly 1800 km s−1. St 2-22 turned out to be a classical symbiotic system very similar to the precursor of the group – Z And