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Number of results: 7
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Abstract

Reverberation time (RT) is an important indicator of room acoustics, however, most studies focus on the mid-high frequency RT, and less on the low-frequency RT. In this paper, a hybrid approach based on geometric and wave methods was proposed to build a more accurate and wide frequency-band room acoustic impulse response. This hybrid method utilized the finite-difference time-domain (FDTD) method modeling at low frequencies and the Odeon simulation at mid-high frequencies, which was investigated in a university classroom. The influence of the low-frequency RT on speech intelligibility was explored. For the low-frequency part, different impedance boundary conditions were employed and the effectiveness of the hybrid method has also been verified. From the results of objective acoustical parameters and subjective listening experiments, the smaller the low-frequency RT was, the higher the Chinese speech intelligibility score was. The syllables, consonants, vowels, and the syllable order also had significant effects on the intelligibility score.
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Authors and Affiliations

Wuqiong Huang
1 2
Jianxin Peng
1
Tinghui Xie
3

  1. School of Physics and Optoelectronics, South China University of Technology, Guangzhou, China
  2. State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou, China
  3. School of Architecture and Art, Shijiazhuang Tiedao University, Shijiazhuang, China
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Abstract

The historic municipal park located in Zduńska Wola is covered in the central and northern part by conservator protection through an entry in the register of monuments and on the basis of an entry in the local spatial development plan. In terms of nature, the area has significant values due to old trees and the water system, which consists of two ponds fed by the Pichna River. As part of the preparatory work for the revalorization of the park, several studies and analyses were carried out, including assessment of the sanitary state of waters of Pichna River that supplies reservoirs. Degree of the river pollution made it impossible to restore the water system, the most important element of the park, while further supplying the ponds with river water. In order to ensure a satisfactory degree of purity and transparency of water in ponds, a decision was made to apply complex and modern technological solutions enabling the renovation of the water system. Project documentation was developed in 2015. After two years, they began to implement the project. Banks of both ponds were formed more gently, and the basins were deepened. Selection of vegetation around the reservoir and in the reservoir itself was based on the principle of biocenotic assumptions. The designed system is equipped with a circulation pump, skimmers, bottom drains, mechanical-mineral filter, swamp filter. This was to ensure adequate purification of water in ponds, based on natural processes, stimulated by the use of new, pro-ecological technologies.

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Authors and Affiliations

Ewelina Widelska
Wojciech Walczak
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Abstract

Reflection on the process of defining and redefining the notion of Polishness after 1918, and thus, an attempt to answer the questions: ‘What is Polishness?’; ‘Is it possible to talk about its single, monolithic, well-defined form in relation to a specific point in history as well as at present?’ – were the main topics of an international conference organised by the Centre for Historical Research on 21st–22nd June 2018 and held at the glamourous Louise-Schroeder-Saal of the Rotes Rathaus (Red Town Hall) in Berlin. Held on the occasion of the centenary of Poland’s regained independence, the event was simultaneously a festive farewell to Professor Robert Traba, the founder and Director of the Berlin-based Centre for Historical Research, Polish Academy of Sciences. The attendees included researchers from Poland as well as scholars from Germany and France, representing various fields of science: history, literature, sociology, political science, law, Slavic studies, Polish studies, and art history. A total of twenty-seven papers and comments, in Polish and/or German, were submitted. The conference ended with a panel discussion (lasting over two hours) on ‘Individual identities in the face of collective ideas of Polishness’ (now available on the CHR website: http://www.cbh.pan.pl/de/fotobericht-und-film-zur-konferenz-derunvollendete-krieg).

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Authors and Affiliations

Małgorzata Stolarska-Fronia
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Abstract

The last biomonitoring study in Poland on intoxication with fluoride compounds of deer was conducted almost two decades ago. Given the fact that fluoride level in air and water is not widely monitored in Poland, it is justified to undertake monitoring of F- levels in people and other long-lived mammals. This paper provides the assessment of the present level of fluoride accumulation in mineralized tissue of large herbivorous mammals. The aim of the present study was to determine fluoride concentration in teeth of deer inhabiting the areas of Poland which are industrially uncontaminated with fluoride compounds, to establish possible correlations between the analysed parameters, and to provide a comparison of the present results with those obtained in other studies. Mean concentration of fluoride in all analysed samples amounted to 231.0 F mg/kg, with the minimum value of 22.0 F mg/kg and the maximum of 935.0 F mg/kg. This results from the development of industry and a widespread use of fluoride-supplemented caries prevention products which contributes to an intense accumulation of these substances in vertebrates, predominantly in mineralized tissue.
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Authors and Affiliations

M. Palczewska-Komsa
1
K. Barczak
1
K. Grocholewicz
2
J. Buczkowska-Radlińska
1
P.R. Piotrowski
3
E. Sobolewska
4

  1. Pomeranian Medical University in Szczecin, Department of Conservative Dentistry and Endodontics, Powstańców Wlkp. 72, 71-111 Szczecin, Poland
  2. Pomeranian Medical University in Szczecin, Integrated Dentistry Department, Powstańców Wlkp. 72, 71-111 Szczecin, Poland
  3. University of Medical Sciences in Poznań, Professor Emeritus of the Medical Faculty, Bukowska 70, 60-812 Poznań, Poland
  4. Pomeranian Medical University in Szczecin, Department of Dental Prosthetics, Powstańców Wlkp. 72, 71-111 Szczecin, Poland
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Abstract

This work presents a simulation of the response of packets of microbubbles in an ultrasonic pulse-echo scan line. Rayleigh-Plesset equation has been used to predict the echo from numerically obtained radial dynamics of microbubbles. Varying the number of scattering microbubbles on the pulse wave form has been discussed. To improve microbubble-specific imaging at high frequencies, the subharmonic and second harmonic signals from individual microbubbles as well as microbubbles packets were simulated as a function of size and pressure. Two different modes of harmonic generation have been distinguished. The strength and bandwidth of the subharmonic component in the scattering spectrum of microbubbles is greater than that of the second harmonic. The pressure spectra provide quantitative and detailed information on the dynamic behaviour of ultrasound contrast agent microbubbles packet.
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Authors and Affiliations

Mohamed G.S. Ali
Nour Z. Elsayed
Ebtsam A. Eid
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Abstract

The difficulties of access and detailed measurements of land surface temperature (LST) and water surface temperature (WST) especially in wetlands made the use of remote sensing data as one of the sources and techniques to estimate many climate elements including surface temperature and surface emissivity (ɛ). This study aims to estimate the surface tempera-ture of the wetland of Lake Oubeira located in northeastern Algeria and their spatiotemporal evolution in both land and wa-ter. Landsat OLI-TIRS images in two dates (April and September 2016) obtained from the USGS have been used in this work, and forms the basis of a series of operations to obtain the final LST: development of the normalized difference vegeta-tion index (NDVI), conversion of the digital number (DN) of the thermal infrared band (TIR) into spectral radiance as well as the calculation of the effective luminosity temperature of the sensor from the spectral radiation and surface emissivity (ɛ). The results show that the LST varies in space and time (from 16 to 31°C in April and from 24 to 41°C in September). This implies that the absorption of the equilibrium temperature at land cover depends on the optical properties of the sur-face, which are essentially determined by its water content, colour and morphology. At the same time, the water surface is the lowest land cover temperature, which also has a spatial variation (from 19 to 25°C in April and from 26 to 34.5°C in September) induced by atmospheric temperature, wind direction and speed and the depth of the lake.

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Authors and Affiliations

Chouaib Rezzag Bara
Mohamed Djidel
Fethi Medjani
Sofiane Labar

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