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Number of results: 6
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Abstract

Sub-bottom profiler (SBP) is an acoustic instrument commonly used to survey underwater shallow geological structure and embedded objects whose most important performance parameter is the actual vertical resolution. This paper presented a methodology to measure and evaluate the actual vertical resolution of SBP based on an experiment in an anechoic tank, which was divided into three components: building of artificial geological model, measurement of acoustic parameters, and determination of actual vertical resolution of the acoustic profiles. First, the wedge-shaped geological model, whose thickness could be accurately controlled, was designed and built in an anechoic tank to try to directly measure the vertical resolution of SBP. Then, the acoustic pulse width of SBP was measured to calculate the theoretical general vertical resolution and extreme vertical resolution. Finally, based on the acoustic profiles obtained in the experiment, the method which was used to evaluate the actual vertical resolution by measuring the duration of reflection event was put forward. Due to comparing measurement data of different parameter settings of the SBP, the study has revealed that the SBP had the lowest resolution in the 4 kHz–500 µs setting, which was 226.5 µs, or 36.2 cm, and the highest resolution in the 15 kHz–67 µs setting, which was 72.7 µs, or 11.6 cm. The vertical resolution decreased with the increase of the pulse width. The results also showed that the actual resolution was close to the theoretical general resolution and far from the extreme resolution.

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Authors and Affiliations

Fangqi Wang
Lifeng Dong
Jisheng Ding
Xinghua Zhou
Changfei Tao
Xubo Lin
Guanhui Liang
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Abstract

The main purpose of the paper is to present a method which allows taking into account the anisotropic properties of dynamo steel sheets. An additional aim is to briefly present anisotropic properties of these sheets which are caused by occurrences of some textures. In order to take into account textures occurring in dynamo sheets, a certain sheet sample is divided into elementary segments. Two matrix equations, describing changes of the magnetic field, are transformed to one non-linear algebraic equation in which the field strength components are unknown. In this transformation the flux densities assigned to individual elementary segments are replaced by functions of flux densities of easy magnetization axes of all textures occurring in the given dynamo sheet. The procedure presented in the paper allows determining one non-linear matrix equation of the magnetic field distribution; in this equation all textures occurring in a dynamo sheet are included. Information about textures occurring in typical dynamo sheets may be used in various approaches regarding the inclusion of anisotropic properties of these sheets, but above all, the presented method can be helpful in calculations of the magnetic field distribution in anisotropic dynamo sheets.

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Authors and Affiliations

Witold Mazgaj
ORCID: ORCID
Zbigniew Szular
Michał Sierżęga
ORCID: ORCID
Paweł Szczurek
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Abstract

W artykule przedstawiono zalety i ograniczenia systemu Seismobile zebrane w wyniku wstępnych badań terenowych. Jest to system mobilny przystosowany do wykonywania równocześnie pomiarów sejsmicznych oraz georadarowych. Ta cecha wyróżnia ten system od dotychczas opracowanych strimerów. W pracy przedstawiono metodykę pomiarową systemu Seismobile, obejmującą przygotowanie sprzętu, akwizycję danych oraz wykonanie pomiaru danych sejsmicznych. Na podstawie dotychczasowych testów omówiono zalety systemu Seismobile, do których należy zaliczyć m.in. ograniczenie pracochłonności podczas pomiarów, bezprzewodową komunikację pomiędzy elementami systemu, niezależność modułów pomiarowych od siebie, możliwość zmiany rozstawu w zależności od zadania badawczego, mobilny wzbudnik, możliwość zastosowania dowolnego typu czujników sejsmicznych, zapis danych na powszechnie dostępnych kartach pamięci SDHC, stację dokującą służącą do archiwizowania i ładowania baterii modułów pomiarowych. System Seismobile, podobnie do innych tego typu urządzeń, posiada również różnego rodzaju ograniczenia, głównie o charakterze technicznym. Przygotowanie systemu do pierwszego pomiaru jest czasochłonne i wymaga dość dużego nakładu pracy. Zestawy czujników na metalowych podstawach mogą być niestabilne w trudnych warunkach terenowych, a ich kontakt z ośrodkiem jest słabszy niż w przypadku geofonów wbijanych w grunt. Czas pracy baterii modułów pomiarowych ulega skróceniu z upływem czasu. Mogą też występować problemy z rejestracją poprawnego sygnału GPS w trudnych warunkach terenowych, wykorzystywanego do lokalizacji systemu i synchronizacji czasu pracy jego elementów. Niezależnie od wskazanych ograniczeń wyniki uzyskiwane systemem Seismobile wskazują na jego dużą przydatność w badaniach defektów płytkiego podłoża.

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Authors and Affiliations

Maciej Barnaś
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Abstract

This paper concerns convective drying of carrot preliminary dehydrated in aqueous solutions of three types of osmotic agents (sucrose, fructose, glucose). Three solution concentrations (20, 40 and 60%) were examined to work out efficient conditions of osmotic dewatering. The parameters such as water loss (WL), solid gain (SG) and osmotic drying rate (ODR) indicating the real efficiency of osmotic dehydrations (OD) were determined. The samples dehydrated with osmotic solutions underwent further convective drying to analyze influence of dehydration process on drying kinetics and final products quality. The quality of products was assessed on the basis of visual appearance of the samples and colorimetric measurements. It was found that osmotic pretreatment improves significantly the final product quality as the samples were less deformed and their colour was better preserved compared to samples, which had not been preliminarily dehydrated. Preliminary dehydration, however, did not influence significantly the overall drying time of the samples.

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Authors and Affiliations

Stefan Kowalski
Dominik Mierzwa
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Abstract

A number of large permanent and temporary exhibitions of decorative arts, design and industrial design have opened in Poland over the last two years. They are varied but linked by the fact that they were all (with one exception) shown in major national museums. Permanent displays included The Gallery of Old Masters. European and Old Polish Decorative Arts, Painting and Sculpture, 15th–18th Century (in The National Museum in Warsaw) which opened in 2016, and The Museum of Applied Arts and The Gallery of Polish Design (both in The National Museum in Poznan), inaugurated in 2017. Temporary exhibitions included Organizers of Life. De Stijl, The Polish Avant-Garde and Design (at the Muzeum Sztuki in Łódź, 25 November 2017 – 28 February 2018) and The other Side of Things. Polish Design after 1989 (in the National Museum in Krakow, 6 April – 19 August 2018). On the one hand, these exhibitions make a case for a full and legitimate participation of Poland in this type of pan-European creativity, not as simple replication, but as participation with its own aesthetic and iconographic vision as well as functional adjustment. On the other hand, the exhibitions invite us to ask the question, if the collections of objects are representative enough to justify this claim? In the case of design exhibitions, there is no doubt that the decision to display it in national museums came about slowly, starting around the year 2000, as part of a wider process of establishing its position in the historical and academic sense within the modern artistic output. The layout and character of the two types of exhibitions are not only the result of the state of the existing collections, but of the tension between knowledge and display. In the case of design and craftsmanship, it is incomparably less important than when exhibiting art. This comes from the fact that in the former the experts’ perspective still dominates over more theoretical views.

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Authors and Affiliations

Piotr Korduba
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Abstract

The paper presents an adapted least squares identification method for reduced-order parametric models. On the example of the open velocity loop, different model approaches were implemented in a motion control system. Furthermore, it is demonstrated how the accuracy of the method can be improved. Finally, experimental results are shown.

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Authors and Affiliations

Reimund Neugebauer
Arvid Hellmich
Stefan Hofmann
Holger Schlegel

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