Samardzioska, Todorka

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Official Name

Samardzioska, Todorka

Main Affiliation

samardzioska@gf.ukim.edu.mk

Now showing 1 - 10 of 10

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Experimental and Numerical Investigation of Sound Absorption Characteristics of Rebonded Polyurethane Foam
(MDPI AG, 2022-12-16)
Mitrevska, Milica Jovanoska
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Mickovski, Viktor
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Iannace, Gino
<jats:p>Polyurethane foam (PUF) is an exceptionally adaptable product that has a variety of applications—it can be found almost everywhere. Due to such high utilization, the amount of polyurethane foam waste generated each year is growing over time. Rebonding polyurethane foam waste is a suitable way to progress towards a circular economy. In this paper, the prospect of using rebonded polyurethane foam (RPUF) in noise control applications is examined. An experimental study was carried out on RPUFs with various thicknesses and densities. The sound absorption coefficients at normal incidence and air resistivity were measured. The five-parameter Johnson-Champoux-Allard (JCA) model was adopted for the simulation of the porous layer. The remaining unknown parameters of the JCA model were estimated by inverse acoustic characterization based on fitting the transfer matrix method (TMM) model of an unbounded porous layer with rigid backing to the experimentally obtained sound absorption coefficients. Furthermore, sound absorption coefficients were calculated for a wide range of sample thicknesses, as well as for different air gap thicknesses between the wall and the porous layer. For some of the considered RPUFs, a sound absorption coefficient above 0.8 was achieved over a wide frequency range.</jats:p>
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An artificial neural network prediction model for fire resistance of composite columns
(Centre for Evaluation in Education and Science (CEON/CEES), 2014)
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Milanovic, Milivoje
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Knezevic, Milos
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Red Clay as a Raw Material for Sustainable Masonry Composite Ceramic Blocks
(MDPI AG, 2025-07-28)
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Zileska Pancovska, Valentina
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Golaboski, Bojan
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The pursuit of sustainable construction practices has become imperative in the modern era. This paper delves into the research of the properties and application of a specific material called “red clay” from the locality “Crvena Mogila” in Macedonia. A series of laboratory tests were conducted to evaluate the physical, mechanical, and chemical properties of the material. The tested samples show that it is a porous material with low density, high water absorption, and compressive strength in range of 29.85–38.32 MPa. Samples of composite wall blocks were made with partial replacement of natural aggregate with red clay aggregate. Two types of blocks were produced with dimensions of 390 × 190 × 190 mm, with five and six holes. The average compressive strength of the blocks ranges from 3.1 to 4.1 MPa, which depends on net density and the number of holes. Testing showed that these blocks have nearly seven-times-lower thermal conductivity than conventional concrete blocks and nearly twice-lower conductivity than full-fired clay bricks. The general conclusion is that the tested red clay is an economically viable and sustainable material with favourable physical, mechanical, and thermal parameters and can be used as a granular aggregate in the production of composite ceramic blocks.
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Numerical investigation of sound transmission through single and double walls with periodic arrays of resonators
(Institute of Noise Control Engineering (INCE), 2023-02-01)
Jovanoska, Milica
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<jats:p>Lightweight partition walls are widely used in buildings, especially nowadays when sustainability is of a major interest. At the same time noise pollution is becoming a growing problem across the globe. All this implies the need to find possible solutions for sound insulation improvement of the lightweight partitions. This paper is focused on exploring the possibilities of exploiting the dynamic effects of periodic subwavelength arrays of resonators for sound insulation enhancement. In order to improve the sound transmission loss in a specific frequency region, periodic resonant units are tuned and introduced to single and double panels. It can be shown that the resonance mode of the resonators couples with the host plate vibration in the way of breaking the mass law and overcoming some phenomena like coincidence effect and mass-air-mass resonance. The investigation of the considered panels under acoustic field excitation is conducted using different methods. Sound transmission loss curves and dispersion diagrams are calculated. Finite element method is employed for this purpose, but also the theory of three-dimensional elasticity and well-known transfer matrix method (TMM). Several designs of resonators are proposed.</jats:p>
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Enhancing the sound transmission loss of a single panel in the coincidence-controlled region through theoretical optimization of metamateral design
(Optikai, Akusztikai, Film- és Színháztechnikai Tudományos Egyesület (OPAKFI) Scientific Society for Optics, Acoustics, Motion Pictures and Theatre, 2021-09)
Jovanoska, Milica
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The lightweight design of partition walls is in line with the new green building trend, due to which the gypsum panel is a highly demanded building material. As a result of present-day life dynamics which increases noise pollution, new challenges are posed for further improvement of sound insulation. All this implies the need for evolution of the classical partition systems, and metamaterials are considered as a promising solution. This paper is concerned with an analytical optimization of the sound insulation performance in the coincidence region of a gypsum board as a host structure with periodically attached locally resonant units, with subwavelength size of the unit cell. The spring-mass resonators have been designed to interact with the flexural waves in the host structure in the specific tuned range in order to overcome the coincidence effect. Using the effective medium (EM) method and plane wave expansion (PWE) method, the sound transmission loss (STL) curves and the dispersion curves have been calculated. Based on the dispersion plots, detection of the band gaps is made possible, which can also be confirmed in the STL curves. This theoretical design can bring potential ideas for improving the sound insulation of partition systems that include plasterboard.
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Design of Earthship for Climate Conditions in Macedonia
(IOP Publishing, 2019-09-01)
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Salih, Nena
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Grujoska, Vesna
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Jovanoska, Milica
<jats:title>Abstract</jats:title><jats:p>The Earthship, as a sustainable nearly zero house, built of natural and recycled materials, represents one of the solutions for the numerous environmental issues. A specific location is chosen by the Lake Ohrid in Macedonia. The house is designed for a single family, with dimensions and materials selected according to recommendations in the literature. It is not connected to the public infrastructural network, reducing its dependence on public services and the use of fossil fuels. It is built of natural and recycled materials, having thermal solar heating and cooling, collection and storage of rain water, controlled wastewater treatment, power from sun or wind and food self-production. Static and dynamic analysis has been performed and stability in this highly seismic region is confirmed, followed by the analysis of the energy efficiency and bill of quantities. This design meets the passive house criteria and the planned investment is considerably lower in comparison to a passive house built of “standard” building materials. The potential benefits of this designed Earthship might have an impact in the future building construction and architecture in Macedonia, especially for suburbs. They might help raise people’s awareness of the benefits of sustainable architecture: reduction of the greenhouse gas emission, saving fresh water reserves by harvesting rainwater and reusing it as grey water, controlling the micro climate of the suburban areas by using energy efficient materials and choosing the right location for building.</jats:p>
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Numerical investigation on sound transmission behaviour of multilayered panels with periodic arrays of spring-mass resonators
(European Acoustics Association, 2022-05)
Jovanoska, Milica
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Recent developments in engineering and sustainability initiatives have resulted in building trend of lightweight partitions, utilizing new materials and technologies. At the same time, noise pollution is becoming a growing problem across the globe, as a result of present-day life dynamics. The impact of the increased noise levels on human health and wellbeing is perceived. All this implies the need for sound insulation enhancement of the lightweight partitions. Theoretical and numerical investigation of multi-layered panels under acoustic excitation are conducted using different methods. The sound transmission loss (STL) of unbounded multi-layered panels is calculated using the theory of three- dimensional elasticity and well-known transfer matrix method (TMM). Additionally, the finite element method (FEM) is also used for sound transmission loss calculation and for obtaining the dispersion diagrams. Based on the dispersion curves, detection of the band gaps is made possible. In order to improve the sound transmission loss in a specific frequency region, periodic resonant units (spring-mass resonators) are tuned and introduced to the considered panels. It can be shown that the resonance mode of the spring-mass resonators couples with the plate vibration in the way of breaking the mass law and overcoming some phenomena like coincidence effect and mass-air-mass resonance. These units can be attached or embedded in the host panel. Such periodic structures recently have been recognized as acoustic metamaterials. Acoustic resonant metamaterials are artificial periodic structures with unique acoustic wave manipulation properties, owing to the dynamic influence of their local resonant units. The drawback of this concept is that this ”unordinary” power for wave manipulation works only in specific narrow frequency band associated with the resonant frequency of the resonant units. Nevertheless, this phenomenon has potential to be useful ”tool” for correcting/complementing lightweight partition systems.
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Experimental analysis of mechanical characteristics of FRP materials
(MASE - Macedonian Association of Structural Engineers, 2015-10)
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New urban bridge as a socially responsible public space
(International Association for Bridge and Structural Engineering (IABSE), 2010)
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Trombeva, Ana G.
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<jats:p><p>New governmentally financed project “Skopje 2014” with intention to “re-establish” the identity of the nation through development of infrastructure and architecture in Baroque style has substantially changed the urban, social, political and ethical context of the central area of the city.</p><p>The aim of our work is to present an open approach of form finding process as a result of interaction of functional, engineering and social issues that is in contrast with fixed and predetermined typology proposed by government. Our new pedestrian bridge on river Vardar in the centre of the city creates new urban landscapes acting as a social attractor and urban infrastructure. Its geometry and structure is a result of formal and functional concept generated as a complex emergent property of the topologically based system expressing high level of social responsibility of design and ethical and esthetical approach to complex engineering challenges in urban areas.</p></jats:p>
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Current Deveopments towards seismic metamaterials
(2019)
Jovanoska, Milica
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Samardzioska, Todorka

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