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Koleksiyondaki öğeler
- MakaleAçık Erişim2017Scopus SJRQ1Thermal performance assessment of a novel liquid desiccant-based evaporative cooling system: An experimental investigation
Cuce, Pinar Mert
Energy consumption in buildings due to heating, cooling and air conditioning (HVAC) systems has a steadily growing trend as a consequence of enhanced indoor thermal comfort conditions. The role of cooling in HVAC oriented energy consumption is remarkable especially in regions with extreme climatic conditions such as Africa and Middle East. In hot and arid climates, cooling demand is usually met by cost-effective evaporative cooling solutions. However, in hot and humid climates, evaporative cooling systems are not capable of providing cooling as the outdoor air is already almost saturated in most cases. Therefore in this research, a novel desiccant-based evaporative cooling system is presented. For different values of inlet supply air temperature and relative humidity provided by a standard environmental chamber, temperature and relative humidity values are measured experimentally at the inlet and outlet of dehumidification and humidification unit, respectively. Since the main purpose of the system developed is to provide cost-effective thermal comfort conditions especially in humid climates, dehumidification effectiveness is calculated for each case tested. The results indicate that the system provides attractive findings for temperate and humid climatic conditions, where stand-alone evaporative cooling systems are inconclusive. For a case of average inlet relative humidity of 94.7% and average inlet air temperature of 38.6 °C, the average outlet relative humidity and air temperature are determined to be 65.5% and 33.3 °C, respectively. An average of 5.3 °C reduction is achieved in supply air temperature as well as an average of 63.7% dehumidification effectiveness which is attractive and promising.
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İncele - MakaleYalnız künye2015Scopus SJRQ1Thermal loop test to determine structural changes and thermal stability of creamed honey: Rheological characterization
Karasu, Salih; Toker, Omer Said; Yilmaz, Mustafa Tahsin; Karaman, Safa; Dertli, Enes
This study was the first attempt to understand if thermal stability of any food product during storage could be determined. In this respect, a novel method, namely, the thermal loop test was used to determine structural changes and thermal stability of creamed honey in this study. The novelty of this method was that thermal stability of a product is tested within a number of thermal cycles over a determined range of temperature. Creamed honey was characterized in terms of physicochemical, thermomechanical and rheological properties. It showed non-Newtonian thixotropic behavior at all temperature levels (10, 25 and 40 °C). Time-dependent flow behavior was successfully defined by Weltman and second order structural models. Hysteresis loop area depended on temperature and decreased with increase in temperature. Creamed honey had liquid-like structure, showing that it had more pronounced viscous nature than elastic nature (G″ > G′). Temperature sweep tests were conducted to determine temperature dependency of η50, G′ and G″ values using Arrhenius equation. These test results confirmed the thermal stability test results, revealing that thermal loop test can be an accurate method to determine thermal stability of similar food products, as a new information. Relative structural index value (Δ) increased with number of thermal loop, suggesting that creamed honey had low thermal stability and showed a great structural change by the thermal stress applied between 5 °C and 50 °C. These results suggest that crystallized honey be abstained from large temperature fluctuations to avoid from irreversible changes in rheological characters; thus, to maintain spreadability.
AtıfScopus45WoS43OpenAlex47İncele - MakaleAçık Erişim2019Scopus SJRQ2Uniform boundedness of kantorovich operators in variable exponent Lebesgue spaces
Ayazoglu, Rabil; Akbulut, Sezgin; Akkoyunlu, Ebubekir
In this paper, the Kantorovich operators Kn, n ϵ N are shown to be uniformly bounded in variable exponent Lebesgue spaces on the closed interval [0, 1]. Also an upper estimate is obtained for the difference Kn (f) − f for functions f of regularity of order 1 and 2 measured in variable exponent Lebesgue spaces, which is of interest on its own and can be applied to other problems related to the Kantorovich operators.
AtıfScopus3WoS3OpenAlex3İncele - MakaleAçık Erişim2016Scopus SJRQ1A comparative study on optimum design of multi-element truss structures
Artar, Musa
A Harmony Search (HS) and Genetic Algorithms (GA), two powerful metaheuristic search techniques, are used for minimum weight designs of different truss structures by selecting suitable profile sections from a specified list taken from American Institute of Steel Construction (AISC). A computer program is coded in MATLAB interacting with SAP2000-OAPI to obtain solution of design problems. The stress constraints according to AISC-ASD (Allowable Stress Design) and displacement constraints are considered for optimum designs. Three different truss structures such as bridge, dome and tower structures taken from literature are designed and the results are compared with the ones available in literature. The results obtained from the solutions for truss structures show that optimum designs by these techniques are very similar to the literature results and HS method usually provides more economical solutions in multi-element truss problems.
AtıfScopus30WoS26İncele - MakaleAçık Erişim2018Scopus SJRQ1Gamma-ray attenuation coefficients and transmission thickness of high consistency heavyweight concrete containing mineral admixture
Gökçe, H.Süleyman; Öztürk, Buket Canbaz; Çam, N.Füsun; Andiç-Çakır, Özge
In the study, high consistency heavyweight concrete mixtures containing barite aggregate were produced by using some common mineral admixtures (viscosity modifier, silica fume and fly ash) at various water/binder ratios and binder contents. Gamma-ray linear attenuation coefficients of the concrete mixtures were determined by using gamma sources of 137Cs and 60Co in NaI(Tl) gamma spectrometry system. The relationship between specimen thickness and transmission of the rays was constituted by emphasizing their mean free path, half-value layer, and tenth-value layer. Moreover, experimental mass attenuation coefficients of the concrete specimens were determined and compared with theoretical mass attenuation coefficients calculated by XCOM software depending on elemental fractions of these concrete in equivalent energies (662 keV, 1173 keV and 1332 keV). As a result, the replacement of the aforementioned admixtures with ordinary cement negatively affected the linear attenuation coefficients of the heavyweight concrete. A relative change of up to 25% was observed between the least and the highest attenuation thickness values at a certain gamma-ray transmission. A good regression relationship has been established between density and linear attenuation coefficients, density and mean free path, and density and half- or tenth-value layers of the heavyweight concrete. Theoretical (XCOM) mass attenuation coefficients were found similar to the experimental mass attenuation coefficients of the heavyweight concretes. Although there is a good linear regression relation between the theoretical and experimental mass attenuation coefficients at 662 keV energy of gamma rays, the relations were disappeared at 1173 and 1332 keV energies of gamma rays.
AtıfScopus185WoS173OpenAlex193İncele - MakaleAçık Erişim2013Scopus SJRQ2Energetic and exergetic comparison of air to air and air to water heat pumps according to evaporator conditions
Çomakli, Kemal; Çakir, Uǧur; Şahin, Erol; Kuş, Ayşegül Çokgez
This paper presents an experimental energetic and exergetic comparison for a heat pump system that can be run in different modes as air to air and air to water. Components of the heat pump do not change when the running mode changes, except for the condenser. This means that some external and internal effects (like compressor type, pipe lines) that can affect the system performance will be the same for each running mode. The comparison which was made in this study demonstrates which system leads to an efficient conversion and supply of energy and exergy. In the analysis, four balance (mass, energy, entropy and exergy) equations are applied to the system for the two modes. Exergy and energy efficiency values for both systems are given, while exergy destructions in each of the systems are determined and presented. It is seen that the heat pump unit which has the highest COP value is the air to air type (3.45-3.8); second is the air to water type (3.35-3.41). The exergy efficiency of the air to air heat pump (29-32%) is higher than the exergy efficiency of the air to water type heat pump (24.1-25). Ranking of the exergy destruction rates of the two heat pump types from high to low is as follows: air to air and air to water.
AtıfScopus5OpenAlex5İncele - MakaleAçık Erişim2016Scopus SJRQ1A novel roof type heat recovery panel for low-carbon buildings: An experimental investigation
Cuce, Pinar Mert; Cuce, Erdem; Riffat, Saffa
Energy saving and its efficient utilization is of prime interest in today's world due to the limited energy resources and growing significance of environmental issues. Despite the intensive efforts to narrow the gap between conventional energy sources (wood, coal, gas, oil, etc.) and renewables, renewable energy resources currently supply only about 14% of total world energy demand. In this regard, energy management and optimization are considered compulsory as much as the clean energy generation. Recent works indicate that the buildings play a significant role on global energy consumption. They are responsible for about 40% of global energy demand. Among the different building types, domestic buildings have the largest share with 63% and most of energy is utilized for heating, ventilation and air conditioning (HVAC) systems in those buildings. Energy consumption levels of buildings can be notably reduced through waste heat recovery in HVAC systems. There are several attempts in literature addressing the possibility of decreasing energy consumption of buildings via waste heat recovery technologies. The heat recovery technologies are cost effective and user friendly applications. The use of heat recovery systems aims at mitigating the energy consumption for HVAC applications as well as the greenhouse gas emissions, and hence decreasing the adverse effects of global warming on the Earth. It is well-documented in literature that the heat recovery systems are very promising for domestic applications. In this paper, experimental results of a novel heat recovery system developed for low-carbon buildings are presented. The proposed heat recovery system consists of a plate-type heat exchanger, blower fans and ducts. The parallel-flow arrangement is used to run the system. The system is designed as under roof application. The aim of the system is to recover waste heat and to preheat fresh air using stale air. The experiments of the system are carried out in winter season in Kent, UK. The study aims to investigate the coefficient of performance (COP) of the system as well as the heat recovery efficiency. The results show that the heat recovery efficiency of the proposed system is around 89% while the COP is 4.5. The proposed system can be used in both winter and summer conditions without requiring additional work. Its labor cost is extremely low, so it is cost-effective and user friendly.
AtıfScopus28WoS23OpenAlex31İncele - MakaleAçık Erişim2018Scopus SJRQ2Free vibration analysis of fiber metal laminated straight beam
Maraş, Sinan; Yaman, Mustafa; Sansveren, Mehmet Fatih; Reyhan, Sina Karimpour
In recent years, studies on the development of new and advanced composite materials have been increasing. Among these new technological products, Fiber Metal Laminates (FML), and hybrid structures made of aluminium, carbon, glass or aramid fiber, are preferred especially in the aircraft industry due to their high performance. Therefore, free vibration analysis is necessary for the design process of such structures. In this study, the vibration characteristics of FML for clamped-free boundary conditions were investigated experimentally and numerically. Firstly, numerical results were obtained using Finite Element Method (FEM) and then these results were compared with the experimental results. It was seen that the numerical results were in good agreement with the experimental results. As the theoretical model was justified, the effects of various parameters such as number of layers, fiber orientations, and aluminium layer thickness on the in-plane vibration characteristics of the FML straight beam were analysed using FEM. Thus, most important parameters affecting the vibration characteristics of the hybrid structures were determined.
AtıfScopus21WoS18OpenAlex17İncele - Kitap BölümüYalnız künye2014A solar energy calculation study for the buildings in bayburt in order to get optimum benefit from the sun directly
Çakır, Uğur; Şahin, Erol
This study is a research made on evaluating solar energy utilization rates of the buildings and residences which are under the climatic and meteorological conditions of Bayburt. In the scope of this study, with the aim of enabling them to benefit from solar energy at the maximum level, a numerical modeling study in which we could determine the most suitable directions, shapes, and sizes of the buildings that would be built in Bayburt was carried out. Although the modeling was applied for sample buildings that have specific sizes and shapes and some results were obtained, this modeling can be used for other buildings which have different shapes and the most suitable direction and location designation that can be done. In the solar energy analysis made for the buildings, a year time was divided into four different periods. Related evaluations were made by taking into account that the building should be in shape and orientation which takes the maximum and minimum radiance in the summer and winter. Basic parameters were determined as azimuth angle, the ratio of the building length to its width, and the total periodical radiance that the building takes.
- MakaleAçık Erişim2019Scopus SJRQ3Plasma polymerized linalool (ppLin): An antimicrobial and biocompatible coating
Çakmak, Kenan; Bayram, Özkan; Solak, Kübra; Kaban, Güzin; Şimşek, Önder; Mavi, Ahmet
Bacterial infections in medical devices and drug resistance of bacteria can cause chaos in the world due to loss of lives in addition to the cost of device revisions, quarantine, disinfection of infected areas, and patient treatment. Antibacterial coatings of essential oils on medical devices can prevent bacterial attachment and reduce costs. Linalool is an antibacterial constituent of essential oils. Herein, we examine for the first time the fabrication and characterization of radio frequency (RF) plasma polymerized hydrophilic thin films from linalool (ppLin) by varying deposition parameters (RF power and deposition time) and the behavior of ppLin with two bacteria (Escherichia coli and Staphylococcus aureus) commonly related to microbial contamination of medical devices. While a dramatic reduction in E. coli and S. aureus attachment was observed on ppLin films, their hydrophilic surface was also bactericidal to S. aureus. Additionally, ppLin films were shown to be adherent and noncytotoxic to human fibroblast cells. ppLin can be potentially integrated into medical and other clinical devices as a promising low-cost biocompatible antimicrobial coating.
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İncele - MakaleYalnız künye2014Scopus SJRQ3Developing an Active Citizenship Scale for the Fourth Grade Primary School Students
Kansu, Ceren Çevik; Öksüz, Yücel
The purpose of the present paper is to develop a scale for assessing behaviours towards active citizenship for 4th grade primary school students. The proposal scale, composed of 42 items, was applied to 544 students who are studying at 4th grade of primary schools in the centre of Bayburt. The principal component analysis rotated by varimax rotation was used to obtain evidence for validity of the scale. As a result of this analysis, it has been determined that the scale consists of 25 items and it has a structure composed of four factors. Evidence for validity of the item, item test correlation of the scale and item analysis of the mean differences between upper and lower groups were calculated. It was observed that item test correlation of the scale changed between 0.42-0.74. Besides, Cr α reliabilities were calculated and it was found to be 0.85.
AtıfScopus1OpenAlex5İncele - MakaleAçık Erişim2015Scopus SJRQ2Decontamination of Escherichia coliO157: H7 and Staphylococcus aureus from Fresh-Cut Parsley with Natural Plant Hydrosols
Törnük, Fatih; Dertli, Enes
The inhibitory effects of sage, rosemary, oregano and thyme hydrosols were evaluated against Escherichia coliO157:H7 and Staphylococcus aureus inoculated on parsley at high and low concentrations. Following the pathogen inoculations, parsley samples were washed with the hydrosols and sterile tap water as a control for 0, 20, 40 and 60min, and reductions on pathogen counts were determined. Sterile tap water was ineffective on all conditions tested. After 20min of application, oregano and thyme hydrosols were able to significantly (P<0.05) reduce E.coliO157:H7 counts on low inoculum level, while all hydrosols showed significant reductions (P<0.05) on high inoculum levels at this period. Additional reductions on E.coliO157:H7 counts were observed with the increasing time. S.aureus was more sensitive to hydrosol treatments, and oregano hydrosol was able to completely eliminate S.aureus after 40min. In conclusion, decontamination of foodborne pathogens from fresh-cut vegetables can be achieved by hydrosol treatments.
AtıfScopus14WoS11OpenAlex16İncele - MakaleAçık Erişim2013Scopus SJRQ2Application of S-UTD-CH model into multiple diffraction scenarios
Tabakcioglu, Mehmet Baris; Cansiz, Ahmet
Propagation prediction models based on ray tracing in coverage estimation for digital broadcasting systems are compared. Geometrical Theory of Diffraction (GTD), Slope Uniform Theory of Diffraction (S-UTD), and Slope UTD with Convex Hull (S-UTD-CH) models are compared for computation time and propagation path loss. S-UTD-CH model is optimum model with respect to computation time and relative path loss.
AtıfScopus8WoS7OpenAlex11İncele - MakaleAçık Erişim2017Scopus SJRQ2Teaching word meanings to students at different reading ability: A controlled assessment of the contextual-based vocabulary instruction on reading comprehension
Ilter, Ilhan
The purpose of this study was to examine the effectiveness of contextual-based vocabulary instruction on reading comprehension of seventh-grade students at different reading ability levels in social studies. The Sentence Verification Technique test consisted of 16-items was used to determine participants' reading comprehension skills. In addition, a semi-structured interview form was used to describe participants' perceptions and experiences related to the vocabulary intervention program activities. The experimental condition received a contextual-based vocabulary instruction intervention program for eight weeks in 10 sessions; in contrast to the control condition participated in a wide reading program. As a result, this study yielded two findings: First, the results indicated that teaching students how to use contextual analysis to infer word meanings from context improved significantly their own reading comprehension scores. Second, the qualitative findings showed that poor readers could be able unlock the complexity of the meanings of unknown words and use the cognitive strategies that required to overcome their reading difficulties while reading through explicit instruction. The results suggested that it seemed as though the context-based vocabulary instruction used in this study to improve reading comprehension scores was a fairly powerful procedure for all students, both poor readers and average-high readers in the experimental condition.
AtıfScopus6WoS5OpenAlex10İncele - MakaleYalnız künye2014Scopus SJRQ2Comparison and analyzing of propagation models with respect to material, environmental and wave properties
Tabakcioglu, M.B.; Ayberkin, D.; Cansiz, A.
This paper presents a study on a class of algorithms based on Uniform Theory of Diffraction (UTD) for multiple diffractions. Within this context Slope UTD with Convex Hull (S-UTD-CH) model based on Slope UTD and Fresnel zone concept was reviewed. S-UTD-CH model can be used for fast and more accurate field prediction for multiple diffractions in transition zone. An extensive simulation results for comparison of UTD based algorithms with respect to the computation time and accuracy was provided. Furthermore, the study shows how relative permittivity constant, conductivity and inner angle of wedge and polarization type affect the relative path loss.
AtıfScopus6İncele - MakaleYalnız künye2018Scopus SJRQ2Influence of freeze-thaw on strength of clayey soil stabilized with lime and perlite
Yilmaz, Fatih; Fidan, Duygu
Stabilization of clayey soil has been studied from past to present by mixing different additives to the soil to increase its strength and durability. In recent years, there has been an increasing interest in stabilization of soils with natural pozzolans. Despite this, very few studies have investigated the impact of pozzolanic additives under freeze-thaw cycling. This paper presents the results of an experimental research study on the durability behavior of clayey soils treated with lime and perlite. For this purpose, soil was stabilized with 6% lime content by weight of dry soil (optimum lime ratio of the the soil), perlite was mixed with it in 0%, 5%, 10%, 20%, 25% and 30% proportions. Test specimens were compacted in the laboratory and cured for 7, 28 and 84 days, after which they were tested for unconfined compression tests. In addition to this, they were subjected to 12 closed system freeze-thaw cycles after curing for 28 days. The results show that the addition of perlite as a pozzolanic additive to lime stabilized soil improves the strength and durability. Unconfined compressive strength increases with increased perlite content. The findings indicate that using natural pozzolan which is cheaper than lime, has positive effect in strength and durability of soils and can result cost reduction of stabilization.
AtıfScopus27WoS25OpenAlex15İncele - MakaleYalnız künye2017Scopus SJRQ1Cross-entropy measure on interval neutrosophic sets and its applications in multicriteria decision making
Şahin, Rıdvan
The neutrosophic set model is an important tool for dealing with real scientific and engineering applications because it can handle not only incomplete information but also the inconsistent information and indeterminate information which exist commonly in real situations. In this paper, we firstly propose two practical techniques converting an interval neutrosophic set into a fuzzy set and a single-valued neutrosophic set, respectively. Then, we define the interval neutrosophic cross-entropy in two different ways, which are based on extension of fuzzy cross-entropy and single-valued neutrosophic cross-entropy. Additionally, two multicriteria decision-making methods using the interval neutrosophic cross-entropy between an alternative and the ideal alternative are developed in order to determine the order of the alternatives and choose most preferred one(s). Finally, an illustrative example is presented to verify the proposed methods and to demonstrate their effectiveness and practicality.
AtıfScopus65WoS62OpenAlex72İncele - Kitap BölümüYalnız künye2019Industry 4.0 and energy politics
Boz, Fusun Celebi
- MakaleAçık Erişim2016Scopus SJRQ2Bioactive content of rose hips of different wildly grown rosa dumalis genotypes
Alp, Sevket; Ercisli, Sezai; Jurikova, Tunde; Cakir, Ozlem; Gozlekci, Sadiye
A rose hip is the fruit of a rose plant and mostly belongs to Rosa canina and Rosa dumalis. These species are genuine found as wild in natural conditions, while in some countries are cultivated for their hips that are picked and used in a wide variety of preparations. Because they contain a variety of antioxidants, carotenoids, flavonoids, polyphenols, leucoanthocyanins and catechins, rose hips are considered to be a good cancer preventative. The Rosa genus has been the focus of many recent studies due to its potential benefic effects on treatment and prevention of several diseases. However, there are few in vitro studies concerning its composition and antioxidant capacity. The aim of the present study was to determine bioactive content, including ascorbic acid, total phenolics, total flavonoids, total carotenoids and antioxidant activity of Rosa dumalis genotypes growing wild in Erzurum province located eastern Anatolia. The results revealed that fruits of Rosa dumalis different genotypes were rich rich in terms of vitamin C, which ranged from 402 to 511 mg/100 g fresh weight base. The total phenolic content varied from 297 to 403 mg/100 g fresh weight. The genotype 'E-09' had the highest total flavonoids content (229 mg quercetin equivalent/100 g fresh weight) and the lowest value was attributed to genotype 'E-04' with 143 mg/ quercetin equivalent/100 g fresh weight. The antioxidant activity of the genotypes was between 12.9-28.6 μg Trolox/ml samples. The results revealed that there was enough diversity among Rosa dumalis genotypes for bioactive content and promising genotypes, with high bioactive content, were determined, which can become study material for future breeding activities.
AtıfScopus27WoS22OpenAlex27İncele - BildiriYalnız künye2017Influence of ball and powder filling ratios (Jb and fc) on the dry grinding process of calcite
Uçurum, M.
Turkey has important quantity of industrial minerals and calcite is one of them and is used as filler in the industries such as plastics, rubber, and paint, to gain a variety of features to products. In order to use calcite as filler, some specific properties such as fine product size are required. In the world, conventional ball mill technology is used to obtain calcite with micronized on the industrial scale. In the mill, ball filling ratio (Jb) and powder filling ratio (fc) directly affect product size, energy consumption, and grinding costs. In this study, influence of important operating parameters such as ball and calcite filling ratios (Jb and fc) on the grindability of calcite ore was examined to obtain a fine product (<100 μm) in the conventional ball mill. The batch test results show that the parameters play an important role in the fine grinding process of calcite.
