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Number of results: 6
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Abstract

Effective use of energy in various branches of economy is one of world trends in development of power engineering. Relevant energy consumption occurs during exploitation of buildings, so there is still potential to diminish it as far as heating, ventilation, and air conditioning are concerned. Particularly in summer season, the choice of respective roofing colour can play a decisive role for the heat flux transferred to the inside of the object. Decrease of heat flux causes a lower heat burden to the building and lower power consumption by the air conditioning systems. In winter, on the contrary, heat flux transferred to building’s interior should be higher, as a result, demand of energy for heating will be lower. However, calculations of the heat flux require that energy balance must be made for the object. Unfortunately, not all producers of roofing covers inform about the values of reflectivity and thermal emissivity of their products, which is, in turn, necessary for calculations. In the present paper, research methodology elaborated by authors is proposed for determination of thermal emissivity of roofing covers. The paper presents test stand, methodology, and research results for roofing paper in blue colour (as an example) for which the thermal emissivity is an unknown parameter.

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Authors and Affiliations

Zbigniew Zapałowicz
Anna Walterowicz
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Abstract

Sound intensity measurements using special sensors in a form of pressure-velocity and pressure-pressure probes are becoming more and more often the method of choice for characterization of sound sources. Its wider usability is blocked by the probes’ costs. This paper is on a possible modification of the well-known pressure-pressure sound intensity measurement method. In the proposed new approach a synchronized measurement procedure using only single microphone is used. The paper presents the basics of the sound intensity theory, a review of currently usedmethods of intensity measurement and requirements and limitations of the new method. In the proposed approach one microphone and a properly designed positioning system is used. The application of the method to study the directional characteristics of an active loudspeaker system have been described in detail. The obtained results were compared with those of measurements performed with a commercial p–u probe. The paper contains conclusions indicating advantages of the applied method in comparison with standard pressure measurement methods.

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Authors and Affiliations

Witold Mickiewicz
Michał Raczyński
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Abstract

The paper presents the case study of geotechnical investigations reporting connected with expert’s opinion on undrained shear strength of organic sediments in the river valley at the north of Poland according to reinforcement methodology of c.a. 0,7 km highway embankment. Diversification of primary results caused additional research which revealed and confirmed liquid consistency of organic soils – several meters of organic and calcareous sediments – gyttja under the thin cover of peat. The main goal of the paper is a discussion on standardization of consistency of organic soils itself and additionally to point out very rare possibility of liquid consistency, finally not pointed in International Standards ISO 14688. The application of Atterberg limits in organic sediments is moot but even organic soil with water content higher than liquid limit can’t be classified and interpreted as very soft with description as soil which exudes between the fingers when squeezed in the hand. Such identification is practically impossible when it’s hard to squeeze because of gravitationally leaking through the fingers.
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Authors and Affiliations

Grzegorz Kacprzak
1
ORCID: ORCID
Paweł Pietrzykowski
2
ORCID: ORCID
Želmir Veinović
3
ORCID: ORCID

  1. DSc., Eng., Warsaw University of Technology, Faculty of Civil Engineering, Al. Armii Ludowej 16, 00-637 Warsaw, Poland
  2. PhD., University of Ecology and Management, Faculty of Architecture, ul. Olszewska 12, 00-792 Warsaw, Poland
  3. PhD., Sc., Eng. Ass. Prof., University of Zagreb, Faculty of Mining Geology and Petroleum Engineering, Pierottijeva 6, p.p. 390, 10000 Zagreb, Croatia
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Abstract

In the examined area three types of waters have been recorded: Surface Waters of winter modification, Warm Deep Waters and East Bransfield Strait Waters. Geographical location of Scotia Front is similar to that observed in previous years. The dynamics of waters within the examined area is high. It is reflected not only in physical and chemical parameters but also in the distribution of chlorophyll α. In the Front its total amount in a water column is greater than outside.

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Authors and Affiliations

Stanisław Rakusa-Suszczewski
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Abstract

The effects of the miniature channel-shaped scratches not detectable by the present inline electromagnetic defect detection system employed for wires’ surface defect detection on the fracture behaviour of the wires for civil engineering applications were investigated numerically. Finite element analysis revealed that both miniature channel-shaped across-the-thickness and across-the-width scratches change the fracture behaviour of the wires in terms of the fracture initiation locations and fracture process sequence. However, miniature across-the-thickness scratches does not affect the fracture shape of the wire while miniature across-the-width scratches changed the wires’ cup and cone fracture to a fracture shape with a predominantly flat fracture. These results provide an understanding of the fracture behaviour of wires with miniature scratches and serve as an alternative or a complimentary tools to experimental or fractographic failure analysis of wires with miniatures scratches which are difficult to carry out in the laboratory due to the sizes of the scratches.

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Authors and Affiliations

K.K. Adewole
S.J. Bull

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