International Review of Applied Sciences and Engineering

Állandó link (URI) ehhez a gyűjteményhez

https://hdl.handle.net/2437/300770

International Review of Applied Sciences and Engineering is a peer reviewed journal. It offers a comprehensive range of articles on all aspects of engineering and applied sciences. It provides an international and interdisciplinary platform for the exchange of ideas between engineers, researchers and scholars within the academy and industry. It covers a wide range of application areas including architecture, building services and energetics, civil engineering, electrical engineering and mechatronics, environmental engineering, mechanical engineering, material sciences, applied informatics and management sciences. The aim of the Journal is to provide a location for reporting original research results having international focus with multidisciplinary content. The published papers provide solely new basic information for designers, scholars and developers working in the mentioned fields. The papers reflect the broad categories of interest in: optimisation, simulation, modelling, control techniques, monitoring, and development of new analysis methods, equipment and system conception.

Founder: Debreceni Egyetem

Publisher: Akadémiai Kiadó

URL: https://akjournals.com/view/journals/1848/1848-overview.xml

ISSN 2062-0810 (Print)
ISSN 2063-4269 (Online)

Böngészés

Megjelenítve 1 - 20 (Összesen 191)

Szabadon hozzáférhető
Influence of air distribution in modern large university lecture hall on thermal comfort
(Akadémiai Kiadó, 2019-06-01) Budiaková, Mária; nem
The paper is focused on the influence of air distribution in modern large university lecture hall on the thermal comfort. Providing the optimal parameters of the thermal comfort in the interiors of a university is immensely important for the students. Meeting these parameters is inevitable not only from physiological point of view but also to achieve the desirable students' performance. Parameters of the thermal comfort are also influenced by air distribution system in large university lecture hall. Correct position of supply air and extract air is very important. Experimental measurements of thermal comfort were carried out in the winter season in the large lecture hall of Vienna University of Economics and Business. The device Testo 480 was used for the measurements. Obtained values of air temperature, air relative humidity, air velocity, globe temperature, indexes PMV and PPD are presented in the charts. Modern air distribution system and air conditioning system of the large university lecture hall were evaluated on the basis of thermal comfort parameters. Conclusion of this paper states the principles of how to design modern air distribution systems and air conditioning systems in the new large university lecture halls.
Szabadon hozzáférhető
Cost efficiency of retrofit measures for typical masonry houses in Kosovo
(Akadémiai Kiadó, 2019-06-01) Bajraktari, Egzon; Nushi, Violeta; Almeida, Manuela; nem
A major challenge our society faces today is the energy consumption of buildings. Building stock is responsible for about 40% of energy consumption worldwide. The same applies to Kosovo, where a large number of houses are poorly weatherized and inefficient in terms of energy consumption. Most of the energy consumption in the household sector in Kosovo is dedicated to the needs for heating purposes. Furthermore, many of these houses use wood or coal for heating, releasing a lot of gases in the air and so contributing to an increased air pollution both indoors and outdoors. The Faculty of Civil Engineering and Architecture at the University of Prishtina “Hasan Prishtina” aims to address the issue of energy efficiency for these houses. Specifically, in this study we intend to evaluate various retrofit measures applicable in the country for typical masonry houses and identify the cost-efficient solution. This paper reports the initial results of the study and discusses related challenges.
Szabadon hozzáférhető
An innovative approach for harmonising availability and energy efficiency in data centres: A case study
(Akadémiai Kiadó, 2019-06-01) Kunbaz, Mahmoud; Bieser, Jürgen; nem
A Data Centre (DC) as critical, energy-hungry infrastructure is dominated by two main driving forces: i) Availability and ii) Energy requirements. As a result of increasing energy costs, algorithms for optimising energy efficiency have been devised. However, these algorithms do not take availability into consideration. This paper aims to present a combination of Failure Mode, Effects and Criticality Analysis (FMECA)/Reliability, Availability, Maintainability (RAM)/Energy Analysis as an innovative approach for harmonising availability and energy efficiency in DC. Based on various measures defined by FMECA/RAM, corresponding availability and reliability are modelled and calculated. In parallel, potential energy saving measures are included in RAM simulation to quantify their influence on the availability and reliability of DC infrastructure. As a result, a set of the most promising optimisation measures is selected. Results show that some energy saving measures are highly correlated with availability. However, required data centre availability can be achieved with improved energy efficiency if the right set of optimisation measures is implemented. This approach guides DC managers to identify improvement potentials in terms of availability and energy efficiency, providing a reliable decision basis for future investments.
Szabadon hozzáférhető
Reliability analysis of slope stability in earthen dams following rapid drawdown
(Akadémiai Kiadó, 2019-06-01) Kahot, Zakariae; Dkiouak, Rachid; Khamlichi, Abdellatif; nem
This work was dedicated to assessing reliability of slope stability in earthen dams following rapid drawdown. Modeling of the problem physics was based on saturated-unsaturated seepage flow through the nonlinear Richards equation, under the assumption of two-dimensional approximation in steady state and transient state. The modeling of seepage taking place inside the earth dam infill materials included soil parameters, the negative pore water pressure-hydraulic conductivity relationship as well as the negative pore water pressure-volumetric water content. Slope stability was analyzed by using safety factor as evaluated by the Bishop's simplified method. Solution of the governing equations in terms of pore water pressure and fluid flow velocity was performed by using the modules SEEP/W and SLOPE/W of the Finite Element based software package GeoStudio. The drawdown phenomenon was then analyzed and its influence on dam stability assessed by using surface response method and Monte Carlo simulation. A design formula was proposed in order to bound the probability of failure associated to slope stability.
Szabadon hozzáférhető
Performance study and evaluation of a solar PV testbed system using LabVIEW
(Akadémiai Kiadó, 2019-06-01) Farooq, A.; Aftab, R.; nem
The world is running out of the oil and natural resources with each passing day. Most of the electricity around the world is generated using natural resources. E-governments are trying to move the electricity production from natural resources to hydro and solar generation. For the places such as in the Middle East and deserted areas in Sindh district of Pakistan, where water resources are low and solar is superlative for generating electrical energy. The objective of this research is to implement, model, design and simulate the Photovoltaic Solar Monitoring (PVSM) systems. The simulation for the system is implemented on LabVIEW software and tests are carried out for certain values of input. All the details, expected outcomes, problems, and results are part of this research. The scope of this research is to obtain the results using real-time simulations performed in LabVIEW. The simulation performed in LabVIEW mimics the implementation of the advanced automation and control system technique Supervisory control and data acquisition (SCADA). The objective of this research work is to perform the essential simulation that is required to investigate current products for PV factors monitoring that influence solar panels efficiency. The goals are: to design and to develop a system for monitoring the PV solar systems using LabVIEW, to simulate the performance of PV solar system using the theoretical methods, to monitor system by means of LabVIEW and to show theoretical effects in the method of the curve of PV performance parameters. Implementing the interfacing technique at home level to monitor the local solar parameters helps in utilizing the solar generated energy in an efficient way. Analysis in LabVIEW helps in studying the parametric condition of the environment where solar is required to be installed.
Szabadon hozzáférhető
Behaviour of various experimental wall fragments exposed to real climate conditions – temperature measurement
(Akadémiai Kiadó, 2019-06-01) Jurasova, Daniela; Juras, Peter; nem
Main aim of this paper is to illustrate the experimental partial results of a study on various exterior wall fragments. The study was performed for selected wall fragments and time periods, with attention focused also on wall orientation (East and South) with identical layering and also on dynamic thermal parameters connected to the thermal comfort during summer and winter. Evaluation is done for real measured climate conditions in the area of experimental laboratory (exterior – University of Zilina) and interior conditions set according to the Slovak standard. For needs of the long-term experiment (since March 2017), temperature and relative humidity between layers are monitored. This paper deals specifically with the temperature measurement of selected days. For future publications also coupled heat-air-moisture transport analysis is intended. In this part of analysis, some extreme boundary conditions were selected and reviewed from the point of view of measured temperature inside the wall. Temperature peaks are characterized with respect to exposure to real atmospheric conditions.
Szabadon hozzáférhető
Mechanical properties of the gypsum composite reinforcement with wooden fibers
(Akadémiai Kiadó, 2019-06-01) Hošťálková, Markéta; Vavřínová, Nikola; Longauerová, Veronika; nem
The gypsum is one of the most often used materials in the civil engineering. Very often it is applied in the form of plasterboards without any reinforcement, for example, cladding boards are unusable as supporting construction. To improve the mechanical properties of plasterboards, fibrous materials such as cellulose or glass fiber are added. Reinforcement of gypsum with fibers improves in particular the flexural and shear strength. The main purpose of the research is to clarify whether natural wooden fibers could be used as the reinforced of composite gypsum building materials. Wooden fibers are used as a blown or board thermal insulation. This article presents the results of tests aimed at determining the mechanical and physical properties of gypsum composite reinforced with wooden fibers. The effect of the reinforcement on the strength properties as a compressive strength, flexural strength was verified on a series of test specimens. The results of the tests have shown that the reinforcing of gypsum composite has an impact on the mechanical-physical parameters.
Szabadon hozzáférhető
Hygrothermal assessment of roofs with above-rafter thermal insulation in the detail of the eave overhang
(Akadémiai Kiadó, 2019-06-01) Soudek, Pavel; Kalousek, Lubor; Žák, Antonín; nem
This paper is focused on hygrothermal assessment of the eave overhang detail in above-rafter placed thermal insulation roof system. Results of the long-term measurement of this detail performed on a real building as well as the testing of the measuring method are presented in this paper. Within this measurement the moisture of wooden elements performing an eave overhang of the roof was monitored primarily in order to verify their long-term functionality. In addition the temperature and relative humidity in the roof structure were measured as well. As part of this measurement, various design variants of above mentioned detail in combination with different compositions of the roof structure were compared. The long-term functionality of the assessed details is evaluated in the conclusion of this paper, taking into account especially hygrothermal status of wooden element, which is associated with threats of infestation of these elements by wood decaying fungi or insects.
Szabadon hozzáférhető
Energetic impact of preheating of fresh air in added convex window
(Akadémiai Kiadó, 2019-06-01) Kerekes, Attila; igen
During the renovation of an existing building keeping the original window and installing an added convex window is beneficial for the reduction of heating energy demand, furthermore this solution is free of the disposal and/or recycling of demolition waste. The energy need for heating can be further reduced, if the natural ventilation of the premise is through the buffer zone of the added convex window. In this case the fresh air is pre-heated in the buffer zone, increasing the utilised passive solar gain of the building. Measurements were carried out on experimental huts for analysis of this impact. Dynamic simulations of the huts have been carried out as well. In this paper the results will be presented, which proves the energetic effect.
Szabadon hozzáférhető
Application of nanofilters for ventilation
(Akadémiai Kiadó, 2019-06-01) Rubina, Aleš; Rubinová, Olga; Blasinski, Petr; nem
Nanotechnology is a perspective manufacturing technology, and in the technical fields, it deals with the production, development and utilization of technologies and materials with dimensions in nanometre sizes (1–100 nm). Nanofilters used in the article for filtration purposes consist from a nanolayer which is applied to a coarse textile backing layer, and they are inserted into the frames as conventional textile filters. The most commonly used materials are PP and PE polymers, as well as carbon, glass and metal filters. With the fabrication of nanotechnology-based filter, it is very important to choose materials, polymers with specific properties, which can be used for filtration function of the product itself. The results given in the main article compare the nanofilters with the main representatives of existing filter products currently available on the market. There is a problem with high pressure loss of the nanomaterial, and when we compare them with traditional filters, it is difficult to use them in technical practice, even if there exists the possibility for us to define the material and the thickness of the layer which are adapted to the application-specific application conditions.
Szabadon hozzáférhető
Behaviour of timber beam structures with suspended ceiling when exposed to fire
(Akadémiai Kiadó, 2019-06-01) Rusinová, Marie; Kalousek, Miloš; Lavický, Miloš; nem
Wooden structures are the oldest building elements accompanying man since time immemorial. The Czech Republic is strict in its legal and normative regulations relating to the use of wooden building components. In spite of that the Czech construction market is increasingly returning to wooden houses; not only for dwelling purposes, but also for public amenities. However, the structures made of wood as combustible material have to be carefully assessed especially from the viewpoint of fire safety of the building. This paper deals with the fire safety of wooden structures with special regard to the suspended type of ceiling, as it fulfils the role of insulation against the effects of fire. In particular, the thermal stress caused by fire and its impact upon the safety of the building elements has been investigated.
Szabadon hozzáférhető
Transient simulation study of floor heating systems
(Akadémiai Kiadó, 2019-06-01) Horka, Lucie; Hirs, Jiri; nem
This case study is aimed at transient simulation of floor heating systems. There is comparison of surface floor temperatures and heat fluxes changes of different systems over time. The first studied system is a dry floor heating system which consists of system boards made from insulation material, spreader plates, and it is covered by cement fiber boards. The second examined system is heavy wet concrete floor heating system whose heating power is set identically as heating power of dry floor heating system. Mean temperature of heating water is investigated. All simulations, both time steady-state and transient, are performed in software CalA. Reduction of duration and computational performance of simulation is achieved by creation of a surrogate model. The surrogate model evinces identical surface temperatures and heat fluxes. Total number of computational grid is reduced and therefore lower number of equations is solved. Results show that dry floor heating system has faster response than concreate floor heating system. It is caused by lower weight and lower thermal capacity of this system.
Szabadon hozzáférhető
Biological susceptibility of earth plasters: The influence of relative humidity on fungal growth
(Akadémiai Kiadó, 2019-06-01) Sokolová, Marie; Ryparová, Pavla; nem
All building materials can be affected by microbiological agents during their lifecycle. The presence of microorganisms changes the appearance of the surface, degrading it, and they can even cause health problems to the residents. The biological susceptibility is dependent on the content of nutrient based on organic compounds. Thus one of the most susceptible of those materials are earthen construction materials. The degree of fungal growth is influenced by the chemical composition and plant fibres additives as well as the external conditions such as temperature and relative humidity. The earth plastering mortar has started to gain more attention recently as it is considered to have a low environmental impact and to increase the indoor air quality. Mechanical and physical characteristics of earth materials were studied by a number of authors but the knowledge about the biological resistance of the material is scarce. This study intends to look into the issue of the biological colonisation of earth plasters depending on the relative humidity. The samples, made of four types of earth plasters with different plant fibres, were placed to an environment of the relative humidity ranging from 33% to 100%. During a period of 4 weeks the extent of fungal growth was observed.
Szabadon hozzáférhető
Ignitability small attack flame fire test of gypsum composite reinforced with natural fibres
(Akadémiai Kiadó, 2019-06-01) Teslík, Jiří; Hošťálková, Markéta; Vavřínová, Nikola; nem
Ignitability is one of the parameters that characterize the behaviour of building materials on flame action. The Ignitability Small Attack Flame fire test is used for the classification of building products by their reaction to fire. On the basis of the Ignitability fire test it can be determined that the tested material will be classified into the class E by reaction to fire. The Ignitability Small Attack Flame fire test precede the Single Burning Item fire test, that is used for classification of building products to class D, C, B, A2. The results of the Ignitability fire test were carried out as part of the research on the properties of gypsum composite with natural fiber reinforcement. As part of the research series of ignitability tests on two types of gypsum composite were carried out. The first type was a gypsum composite reinforced with straw fibres. The second type was composite reinforced with wooden fibres. Developed composite materials could be used in the future as board materials and therefore the determination of their fire parameters is a very important part of research. The results of the fire tests have shown that the developed material has a very good flame resistance.
Szabadon hozzáférhető
The assessment of the structural changes of fine-grained cement-based composites in the early-age using acoustic testing
(Akadémiai Kiadó, 2019-06-01) Hoduláková, Michaela; Topolář, Libor; nem
The paper deals with the monitoring of the structural changes of fine-grained cement-based composites in the early-age using acoustic emission method. After mixing, the cement-based materials exhibit continuous time-dependent structural changes which lead to the changes in the mechanical properties due to the chemical and physical processes. The events which are emitted due to the internal structure formation were detected using the acoustic emission techniques. A number of AE events are released due to the formation of new crystalline phases and due to microcracking in the material structure during the setting and hardening. The aim of the performed experiments was to extend the knowledge in the field of the early-age material characteristics and in the field of the internal structure formation of the cement-based materials. The results from temperature measurement show that mixture with microsilica has more slowly raised the internal temperature than mixture without microsilica. The results from acoustic emission measurement show that mixture with microsilica has lower activity of acoustic emission than mixture without microsilica during first six hours from measurement start.
Szabadon hozzáférhető
Gas filling in glass system
(Akadémiai Kiadó, 2019-06-01) Bizoňová, Silvia; Bagoňa, Miloslav; nem
The filler structure is one of the most critical parts of the building's envelope so great emphasis should be placed on its proper design. In addition to the number of panes in the glass system, material of the spacer, the type and the concentration of the filler gas in the cavity between glasses of the insulated system as well as the size of the cavity are also important. The paper focuses on the assessment of the influence of filler gas in the glass system cavity to the energy features of the glass structure. The reason for the assessment is the key influence of the inert gas and the glass cavity dimension on the energy properties of the glass system and the fact that its gradually decreasing concentration greatly affects the properties of the glass system.
Szabadon hozzáférhető
Effect on blending of supplementary cementitious materials on performance of normal strength concrete
(Akadémiai Kiadó, 2019-12-01) Jagan, S.; nem
Sustainability and scarcity in resources are the two major issues to be dealt within the present scenario by effective utilization of alternative materials. In this present study, an attempt has been taken to study the effect of supplementary materials such as fly ash and silica fume as a partial replacement to cement and steel slag and M-sand as a replacement to river sand on strength and durability of concrete. In this study, concrete specimens were prepared based on five different mixes by varying the percentages of these supplementary materials. Various mechanical properties like compressive strength, split tensile strength and flexural strength were performed to ascertain the mix with optimum levels of replacement of supplementary materials for cement and fine aggregate. Durability property like water absorption test was performed on the mix with optimum values of strength. Results revealed that mix with higher percentages of steel slag, optimum level of silica fume and fly ash have shown higher strength and lesser permeability in concrete.
Szabadon hozzáférhető
On the design of class-J microwave power amplifier
(Akadémiai Kiadó, 2019-12-01) Abdulhamid, Mohanad; Karugu, James; nem
Due to the ISM band being unlicensed for communication applications, a lot of applications have been developed in this band and a good example is WiFi IEEE 802.11a, b, g, n of Bluetooth. This numeracy of applications motivated this paper. The paper is concerned with the design of a low distortion 20 dBm 2.4 GHz class-J power amplifier (PA) since PAs are indispensable in radio communications. The design is based on the AVAGO ATF-52189 transistor with a transition frequency of 6 GHz. The design is done as a hybrid circuit network realized using microstrip elements and surface mount device (SMD) capacitors. The schematic design and simulation are carried out using Keysight's Advanced Design System version 2016.01. The simulated PA exhibited a drain efficiency of 69% and a power output of 21 dBm.
Szabadon hozzáférhető
Relationship analysis of wall transmittance and wind speed with numerical method
(Akadémiai Kiadó, 2019-12-01) Szodrai, F.; igen
In heat transfer calculations, transmittance values are often used as a constant in practice. With the spread of dynamic simulations, it opens an opportunity to study the sensitivity of the external effects (e.g., wind speed) on buildings. With the proper amount of result, adequate simplifications can be made to reduce the duration of the simulations. In this paper several steady sate simulations were carried out by Ansys 19.1. Academic version. In the examined cases three building structures were examined with different thermal resistances. Average initial air temperature difference was applied on the two sides of the structures, at the cold side the wind speed was varied, while at the warm side natural convection was present. The surface temperatures and the heat flux were monitored and the transmittances were calculated as a result.
Szabadon hozzáférhető
What type of professionals are worth being hired for fitness clubs? Study made among fitness trainers and fitness consumers
(Akadémiai Kiadó, 2019-12-01) Bartha, Éva Judit; Bácsné Bába, Éva; igen
Fitness industry is an important segment of sports economy worldwide. The number of registered members in fitness clubs has shown a slow, but steady increase. The key objective of our research is to look into the fitness sector in terms of both the demand and supply sides, from the aspect of the fitness providers, as well as of fitness consumers using these services. We are aspiring to explore the training session attendance-related habits of consumers in the Hungarian fitness sector and investigate the factors, features influencing the attendance of the specific trainers’ sessions. Our research focuses on fitness trainers and leisure-time sportspeople who attend gym sessions and therefore the sample may only include people who meet these parameters. As our primary research method, we used interviews and questionnaire survey among fitness trainers and consumers. We asked a total of 753 leisure-time sportspeople and 261 trainers. Our research covers the study of training habits of fitness consumers and a personality analysis of fitness trainers. We think our research results support our fundamental hypothesis that the competitiveness of gyms could be improved by gathering informations on the consumers training habits and selecting the proper experts (trainers).

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