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Number of results: 6
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Abstract

This paper discusses the concept of the reverberation radius, also known as critical distance, in rooms with non-uniformly distributed sound absorption. The reverberation radius is the distance from a sound source at which the direct sound level equals the reflected sound level. The currently used formulas to calculate the reverberation radius have been derived by the classic theories of Sabine or Eyring. However, these theories are only valid in perfectly diffused sound fields; thus, only when the energy density is constant throughout a room. Nevertheless, the generally used formulas for the reverberation radius have been used in any circumstance. Starting from theories for determining the reverberation time in non- diffuse sound fields, this paper firstly proposes a new formula to calculate the reverberation radius in rooms with non-uniformly distributed sound absorption. Then, a comparison between the classic formulas and the new one is performed in some rectangular rooms with non-uniformly distributed sound absorption. Finally, this paper introduces a new interpretation of the reverberation radius in non-diffuse sound fields. According to this interpretation, the time corresponding to the sound to travel a reverberation radius should be assumed as the lower limit of integration of the diffuse sound energy
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Authors and Affiliations

Higini Arau-Puchades
Umberto Berardi
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Abstract

The aim of the project was to collect experimental data regarding local distributions of fluid velocity and inert tracer concentration in a tank reactor with turbulent flow. The experiments were performed in a microscale in a region of tracer fluid injection. The results of experiments can be used for direct validation of currently developed CFD models, particularly for time-dependent mixing models used in LES.

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Authors and Affiliations

Łukasz Makowski
Wojciech Orciuch
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Abstract

Disinfection of drinking water is usually carried out by chlorination process. This is a well known, effective technology, which has many advantages. however during this process dangerous for health byproducts, such as trihalornethanes as well as chlorate, chlorite and bromale arc formed. Another disinfection process. which has emerged as the most promising alternative to chlorination technique, is ozonation. In spite of undeniable advantages. there are certain undefined hazards resulting from this method of water treatment. It is especially due to formation of carcinogen bromale anions in bromide containing waters. Determination of bromale as well as other inorganic oxyhalides is usually carried out by ion chromatography with conductivity detection. The detection sensitivity can be improved by using alternative hyphenated techniques such as IC-ICPMS or IS-MS-MS. These techniques are very sensitive, but are highly sophisticated and the instrumentation is very expensive. "Post-column reactions". i.e. derivative techniques coupled with ion chromatography are a relatively cheap and good alternative. This paper is a review or the newest achievements in analytical techniques used for determination of inorganic oxyhalides by-products formed during various drinking water disinfection processes.
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Authors and Affiliations

Rajmund Michalski
ORCID: ORCID
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Abstract

This study investigated the potential of three microalgae taxonomic groups of Chlorophyta, Cyanoprokaryota and Bacillariophyceae for biogas production. Biogas potential was assessed in mesophilic anaerobic digestion batch tests over a period of 20 days. The cumulative biogas yield (CBY) of Chlorophyta and Cyanoprocaryota was respectively 396.21 mL/g Volatile Solids (VS) and 382.45 mL/g VS. Bacillariophyceae digestion showed lower biogas production of 357.07 mL/g VS. The highest cumulative methane yield (CMY) of 241.25 mL CH 4/g VS was recorded for Cyanoprocaryota biomass, which was signifi cantly higher (p<0.05) than the other two types of microalgae. The highest methane content in biogas of 63.08% was observed with Cyanoprokaryota. Chemical composition of biomass as well as biogas productivity are infl uenced by algal taxonomy.
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Authors and Affiliations

Marta Kisielewska
1
Marcin Dębowski
1
Marcin Zieliński
1

  1. Uniwersytet Warmińsko-Mazurski w Olsztynie, Department of Environmental Engineering
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Abstract

In this contribution, a further parallel between the Akkadian and Egyptian literature is highlighted. The comparison between the lover and a wolf will be of crucial importance. The material consists of one Akkadian example and three Egyptian examples. The radius of the Egyptian formulation then expanded to include other examples.
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Authors and Affiliations

Stefan Bojowald
1
ORCID: ORCID

  1. University of Bonn, Germany

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