Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Dertli, Enes(117)
- Kaya, Yunus(51)
- Şahin, Engin(48)
- İspirli, Hümeyra(47)
- Özen, Soner(46)
- Şenay, Volkan(45)
- Pat, Suat(44)
- Can, Zehra(39)
- Bayraktar, Bülent(37)
- Bayram, Sinan(37)
- Korkmaz, Şadan(36)
- Cuce, Erdem(35)
- Ecem Bayram, Nesrin(33)
- Kutlu, Naciye(33)
- Yilmaz, Mustafa Tahsin(32)
- Artar, Musa(31)
- Ertugrul, Mehmet(30)
- Öner, Erdal(30)
- Ayata, Ümit(29)
- Hasar, Ugur Cem(29)
- Esmer, Yusuf(28)
- Mercan, Emin(27)
- Cuce, Pinar Mert(26)
- Özdemir, Akın(25)
- Çolak, Murat(24)
- Bayram, Ozkan(23)
- Kamiloğlu, Aybike(23)
- Sert, Durmuş(22)
- Ayazoglu, Rabil(21)
- Abdioglu, Murat(20)
- Bayram, Nesrin Ecem(20)
- Kadakal, Mahir(20)
- Kara, Yakup(20)
- Kizil, Hamit Emre(20)
- Tozlu, Alperen(20)
- Birinci, Ahmet(19)
- Gerçek, Yusuf Can(19)
- Battal, Fetullah(18)
- Dirican, Ebubekir(18)
- Ergün, Mustafa(18)
Yayınlar
- MakaleYalnız künye2022THE NEXUS BETWEEN SOCIAL UNREST AND MIGRANT REMITTANCES: EMPIRICAL EVIDENCE FROM GEORGIA
Ari, Yilmaz Onur; Koç, Umit
The paper examines the social unrest and migrant remittances relationship for Georgia using monthly time series data covering January 2007- July 2019. The Granger Causality Test was employed in the application of the econometric technique. Frequency domain causality test was also used in order to empower the findings of the study. The empirical findings showed that there is a bidirectional causality between the reported social unrest index (RSUI) and the remittance inflow to Georgia. Besides, frequency domain causality test results indicated that RSUI was the Granger cause of remittance inflow in the medium term (7-10 months), while remittance inflow was the Granger cause of RSUI in the short term (2-6 months). Social unrest comprises protests based on basic economic needs such as food, gas, electricity etc. Therefore, social unrest can be a supportive factor of remittances inflow to Georgia. This is in line with the view that remittances sent by Georgian immigrants to their families in Georgia are used for consumption rather than investments. On the other hand, remittances can be a determinant of social unrest for Georgia because the existence of separatist movements in Abkhazia and former South Ossetia can be interpreted as remittances can be an important source to fund these movements.
- MakaleYalnız künye2022INEQUALITIES OF HERMITE-HADAMARD TYPE FOR n-TIMES DIFFERENTIABLE ARITHMETIC-HARMONICALLY FUNCTIONS
Kadakal, Huriye
In this work, by using an integral identity together with both the Holder and the power-mean integral inequalities we establish several new inequalities for n-times differentiable arithmetic-harmonically-convex function. Then, using this inequalities, we obtain some new inequalities connected with means. In special cases, the results obtained coincide with the well-known results in the literature.
AtıfWoS1
İncele - MakaleAçık Erişim2022Scopus SJRQ3Turkey's Long-Term Electricity Consumption Forecast
Emec, S.; Akkaya, G.
Demand forecasting is essential primarily for planning. Although it is crucial in many sectors and issues, it has particular importance for electricity. Therefore, the issue of electricity consumption forecasting has recently become a prevalent topic. In light of the above, this study aimed to develop an appropriate model to estimate the long-term electricity consumption of Turkey. The study consists of three steps. In the first step, eight models were developed to separately investigate the effects of eight input variables frequently used in electricity consumption forecasting studies in the literature. In the second step of the study, two models consisting of input variables with high impact in the first step were developed, and the trained performances of the developed models were calculated by using the regression analysis. In the final step, the combined effect of eight variables on electricity consumption forecasting was investigated using regression analysis. It can be conclude that the model in the third step showed significant results, and the model performance was good. Finally, Turkey's electricity consumption forecast for the years 2020-2030 was performed using the model in the third step.
AtıfWoS1OpenAlex3İncele - MakaleAçık Erişim2022The Dynamics Affecting the Export-Import Ratio in Turkey: A Hybrid Model Proposal with Econometrics and Machine Learning Approach
Özden, Erdemalp
The indicators related to foreign trade are conventionally measured in a currency or as the ratio of the country's gross domestic products. The ratio of exports to imports, alternatively, provides more useful results when comparing the foreign trade performance of economies both over time and with other countries as a unit-free indicator. In this study, the macroeconomics and financial determinants affecting this ratio are examined both econometrically and using the machine learning method. In this context, the autoregressive distributed lag model method was first used to investigate the relationship between normalized gross domestic products, exchange rate, consumer price index, producer price index, crude oil and Turkey's ratio of exports to imports rate between 2010-2021, monthly. Long-term analysis showed that the 1% depreciation of the Turkish Liras against the US dollar increased the ratio of exports to imports rate by 0.7 points. In addition, a 1% increase in consumer price index will increase ratio of exports to imports by 1.9 points, while a 1% increase in producer price index will cause a -0.8 point decrease on the ratio of exports to imports. Then, the pattern between the variables was analyzed with quadratic support vector machine, a machine learning method. Finally, the novel ARDL-SVM hybrid method was developed, and the pattern between the variables was examined. The findings revealed that although the econometric method provided a broader scope for interpreting the relationships between variables, the developed ARDL-SVM method successfully captured patterns between variables.
AtıfWoS1OpenAlex5TR Dizin1
İncele - MakaleAçık Erişim2022The Relationship Between Trait Anxiety Levels And Future Expectations Of Young Individuals
Gönen, Mevlut; Öktem, Tuncay
The future expectations of the youth of university-age can influence many of their decisions like the choice of university till their life plans. Many factors, including the psychological state, can affect the expectation for the future. In this study, the relationship between anxiety, which is one of the mentioned psychological factors, and future expectation was examined. A total of 1026 people from various cities of Turkey were enrolled in the special talent exam held by Bayburt University School of Physical Education and Sports. The state and trait anxiety scale developed by Spielberger and his friends was used.The Turkish reliability and validity study of the scale was conducted by Oner and Le Compte. The trait anxiety dimension of the related scale was used. The Future Visions Scale developed by Ginevra and his friends was used. The Turkish reliability and validity study of the scale was conducted by Akca and his friends. Research data were analyzed using SPSS 25 package program. As a result, there is a moderate negative relationship between the trait anxiety scores of all individuals participating in the research and the optimism and hope sub-dimensions of the future expectations scale, and a moderate positive relationship was found in the pessimism sub-dimension. In the correlation test according to gender, there is a negative moderate relationship in the optimism and hope sub-dimensions, and a positive moderate relationship in the pessimism sub-dimension in both female and male individuals. In the analysis made for another variable, the type of high school graduation, although there was a negative moderate relationship between trait anxiety and optimism and hope sub-dimensions, a positive moderate relationship was found with the pessimism sub-dimension.
AtıfOpenAlex3İncele - MakaleYalnız künye2022A New Approach to Human Capital: Crime Adjusted Human Capital Index on European Countries
Kabakçi Günay, Eylul; Yildiz, Umit; Günsoy, Guler; Günsoy, Bulent
Human capital is a one of the essential components in the economic growth and development. Also, the belief that education and health level, which are the main components of human capital, are main features of a happy and healthy society, is getting stronger. But there is a fact that crime is a destructive notion that affects a society???s human capital. In this context, this study aims to create an alternative social welfare measurement method that includes crime rates as a component to human capital on 35 European countries. In this regard, first, a general crime index was generated by using 13 different crime categories of the 35 European countries, and then this index was adapted to the Human Capital Index. As a result, the Crime-Adjusted Human Capital Index (CAHCI) was obtained. It was observed that the country rankings we obtained based on the CAHCI differ significantly from the rankings made based on the Human Capital Index. Significant number of countries, which ranks high in the Human Capital Index, ranks lower when crime rates are considered, indicates that the reliability of social welfare measures based on human capital should be questioned.
AtıfWoS1İncele - MakaleYalnız künye2022Scopus SJRQ1Nondestructive Experimental Measurement, Model Updating, and Fatigue Life Assessment of carsamba Suspension Bridge
Günaydin, Murat; Sunca, Fezayil; Altunisik, Ahmet Can; Ergün, Mustafa; Okur, Fatih Yesevi
This paper includes the structural condition assessment of a 164-m suspension bridge in accordance with numerical and experimental methods. A finite-element model was developed using SAP2000 software so that the assessment of the bridge could be calculated numerically. The operational modal analysis method was also used to obtain experimental dynamic characteristics. In this context: (i) numerical dynamic characteristics of the bridge were obtained and compared with the experimental dynamic characteristics, (ii) a model updating procedure was carried out to minimize the differences between the numerical and experimental natural frequencies, (iii) static and dynamic analyses of the bridge were carried out by using the initial and updated finite-element models, (iv) fatigue life assessment of the bridge was investigated, and (v) the utility of the bridge for pedestrians and vehicles was checked according to various regulations. The results showed that updating the finite-element model had a significant role to play in the static and dynamic behavior of the bridge. The results also demonstrated that the bridge was designed to be extremely safe against static, dynamic, and fatigue loads. Finally, it was concluded that the bridge investigated behaves as a girder bridge rather than a suspension bridge.
AtıfWoS17OpenAlex18İncele - MakaleAçık Erişim2022Scopus SJRQ1Structural Investigation of Masonry Arch Bridges Using Various Nonlinear Finite-Element Models
Tapkin, Serkan; Tercan, Emre; Motsa, Siphesihle Mpho; Drosopoulos, Georgios; Stavroulaki, Maria; Maravelakis, Emmanuel; Stavroulakis, Georgios
This article presents an investigation of the structural behavior of a masonry arch bridge in Turkey. An analytical study has been conducted to provide the geometry of the structure, using laser scanning. A point cloud describing the geometry was obtained and properly transformed into a format that is appropriate for structural analysis software (CAE). Then, nonlinear finite-element models were developed to simulate structural responses of the bridge. The goal of the article is to highlight the influence of both continuum and discrete approaches and related constitutive laws on the responses of the bridge. Thus, continuum damage laws and a discrete model consisting of unilateral contact-friction interfaces were developed. Different load cases were tested and a comparison between the results obtained from the different approaches was considered. The failure mechanisms and the ultimate strengths were derived, and core points of the models were highlighted. The output of this work shows how the different failure models predict the behavior of the masonry arches. It also shows that the three-hinge mechanism, which has been depicted in classical studies for single-span arch masonry bridges under a horizontal settlement of supports, may also be obtained for multiarch bridges. Similarly, downward, vertical settlement of supports may result in the development of two hinges, as in single-span arches. Finally, the beneficial influence of the backfill in limiting the failure in the arch is addressed.
AtıfWoS18OpenAlex21İncele - MakaleAçık Erişim2022Scopus SJRQ1Screening of plant pollen sources, polyphenolic compounds, fatty acids and antioxidant/antimicrobial activity from bee pollen
Gercek, Yusuf Can; Celik, Saffet; Bayram, And Sinan
In this study, the botanical origin, total flavonoid and phenolic content, antioxidant activity, phenolic profile and fatty acid composition of mixed bee pollen loads collected in Bayburt, Turkey, were determined. In addition to these assays, antibacterial activity of bee-collected pollen extract (BCPE) against a variety of food-borne pathogenic bacteria was determined in vitro. Pollen loads were classified into five botanical families based on their color: Asteraceae, Fabaceae, Campanulaceae, Cistaceae and Rosaceae. Total flavonoid, total phenolic, CUPRAC and CERAC concentrations were 173.52 mg GAE/g, 79.21 mg QE/g, 85.59 mg Trolox/g and 118.13 mg Trolox/g, respectively. Twenty-three phenolic compounds were scanned in bee pollen extract by LC-MS/MS, with rutin being the most abundant. Cis-4,7,10,13,16,19 docosahexaenoic acid was the predominant fatty acid, followed by cis-11-eicosenoic acid, palmitic acid, and alfa linolenic acid. In addition, the agar well diffusion (AWD) and micro-broth dilution methods were used to determine of the antibacterial activity of the BCPE sample. MIC values were observed to vary between 2.5–5 mg/mL for Gram-positive bacteria and 5–10 mg/mL for Gram-negative bacteria. These findings indicate that bee pollen could be a potential source of antioxidants and antimicrobials.
AtıfScopus62WoS56OpenAlex71
İncele - Derleme MakaleAçık Erişim2022Scopus SJRQ1Impact of ultrasonication applications on color profile of foods
Kutlu, Naciye; Pandiselvam, R.; Kamiloglu, Aybike; Saka, Irem; Sruthi, N.U.; Kothakota, Anjineyulu; Socol, Claudia Terezia; Maerescu, Cristina Maria
Food color is a feature that provides preliminary information about their preference or consumption. There are dominant pigments that determine the color of each food; the most important pigments are anthocyanins (red–purple color), chlorophylls (green color), carotenoids (yellow-orange color), and betalains (red color). These pigments can be easily affected by temperature, light, oxygen, or pH, thereby altering their properties. Therefore, while processing, it is necessary to prevent the deterioration of these pigments to the maximum possible extent. Ultrasonication, which is one of the emerging non-thermal methods, has multidimensional applications in the food industry. The present review collates information on various aspects of ultrasonication technology, its mechanism of action, influencing factors, and the competence of different ultrasonication applications (drying, irradiation, extraction, pasteurization, cooking, tempering, etc.) in preserving the color of food. It was concluded that ultrasonication treatments provide low-temperature processing at a short time, which positively influences the color properties. However, selecting optimum ultrasonic processing conditions (frequency, power, time, etc.) is crucial for each food to obtain the best color. The key challenges and limitations of the technique and possible future applications are also covered in the paper, serving as a touchstone for further research in this area.
AtıfScopus135WoS118OpenAlex129İncele - MakaleAçık Erişim2022Scopus SJRQ2Investigation of inlet air pressure and evaporative cooling of four different cogeneration cycles
Karaali, Rabi
The objective of this study was to search the effects of the inlet air compressor pressure and evaporative cooling of four different cogeneration plants that are absorption cooling (ab), basic (bsc), air heating (airh), and air fuel heating (airfh) cogeneration systems by using the first law and the second law of thermodynamics, and the exergy analysis methods. For analysis, a program is written by the author in the FORTRAN programming language. Decreasing the atmospheric pressure or increasing the installation altitude of the plants increases the Z factor (ratio of lost exergy to useful exergy) of the four cycles about 10-13%. Also, decreasing inlet air pressure decreases the specific work about 25-28%, and the fuel energy saving ratio of the four cycles decreases about 29-30%. The method of water spray cooling of the compressor inlet air especially in the summer months, the humidity increases and the evaporative cooling can be obtained. By using this method, the ratio of lost exergy to useful exergy can be decreased for the four cycles about 0.5-2%. Also, the specific work of the four cycles can be increased about 1.2-6%.
AtıfOpenAlex4İncele - MakaleAçık Erişim2022Scopus SJRQ2Investigations of low-velocity impact behaviour of single-lap joints having dissimilar hybrid composite adherends through cohesive zone model approach
Erbayrak, Engin
The low-velocity impact behavior of single-lap joints was investigated in this study. In single-lap joints, woven carbon fiber reinforced epoxy (CFRE) and plain woven glass fiber reinforced epoxy (GFRE) laminates as well as a hybrid composite laminate (HCGFRE), which is formed by stacking carbon and glass composite laminates, are used as adherends. Araldite 2011 and Araldite 138 M/HV998 epoxy adhesives were used with different mechanical properties for joining similar and dissimilar composite adherends. Low-velocity impact tests were carried out with 40 J impact energy. Reaction force-time and impact energy-time graphs were obtained from the experimental study as impact response. In numerical analyses, the damage approach of composite adherend was modeled using composite stress-based failure model (Mat 59) and adhesives were modeled utilizing a mixed-mode cohesive zone model (Mat 138) that existed in LS-DYNA explicit finite element software. It was seen that the numerical results indicated a similar tendency with the experimental results due to the modeling of the adhesives using the proper cohesive zone model, the application of correct boundary conditions, and the selection of the correct contact type.
AtıfScopus9WoS9OpenAlex10İncele - MakaleAçık Erişim2022Scopus SJRQ2EXTRACTIVES IN THERMALLY MODIFIED TROPICAL HARDWOODS
Esteves, Bruno; Ayata, Umit; Cruz-Lopes, Luísa; Brás, Isabel; Ferreira, José; Domingos, Idalina
Chemical composition of wood is known to change during thermal treatments. Two species grown in Turkey, afrormosia (Pericopsis elata) and duka (Tapirira guianensis) were heat treated according to Thermowood® method. Lignin, cellulose, hemicelluloses and extractives in dichloromethane, ethanol and water were determined. Wood extracts were analysed by gas chromatography with mass detection and existing compounds were identified by NIST17 database. Results show that hemicelluloses and cellulose content decreased for both heat-treated woods along the treatment while lignin percentage increased. The analysis of extractives has shown several compounds normally associated to lignin thermal degradation that increased along the treatment. At the same time several compounds associated to carbohydrate thermal degradation were found in all the extracts for both heat-treated woods. These founding have allowed the understanding of the degradation pattern of wood during thermal modification. There was not much difference between afrormosia and duka woods structural compounds behaviour along thermal modification. However, the variation of the amount of extractives along the treatment depended on the species.
AtıfScopus20WoS20OpenAlex16İncele - MakaleAçık Erişim2022Scopus SJRQ4Some Physical, Biological, Hardness, and Color Properties of Wood Impregnated with Propolis
Akçay, Çağlar; Ayata, Ümit; Birinci, Emre; Yalçın, Mesut; Kolaylı, Sevgi
Propolis is a bee product collected by honeybees from various tree species in nature. It has antifungal, antibacterial, antioxidant, and anticancerogenic properties. Recently, propolis has been used in wood protection area because it has antifungal properties and is a natural and environmentally friendly material. In this study, some deciduous wood species were treated with methanolic propolis extracts. Propolis solutions were prepared by dissolving propolis in methanol in concentrations of 0.5%, 2.5%, 5%, and 8%. These solutions were forced deep into the Scots pine (Pinus sylvestris L.), fir (Abies nordmanniana), and spruce (Picea orientalis L.) woodblocks under vacuum and pressure. Water uptake and water-repellent efficiencies of the woodblocks were tested at 2-, 4-, and 20-hour immersion periods. Sample blocks were tested against wood-destroying house borer (Hylotrupes bajulus) (Coleoptera, Cerambycidae) larvae for 21 weeks. In addition, color changes of woodblocks treated with propolis were determined. According to results obtained in the study, the highest water-repellent efficiency was 61.4% in propolis-impregnated spruce wood at concentration level of 8% during the 2-hour period. These results show that propolis extracts could be used as hydrophobic material for wood. Larvae mortality rates indicated that 8% concentration level was not adequate to overcome H. bajulus larvae or propolis is not effective against H. bajulus larvae. While L* value decreases with the increase of impregnation rate, a* and b* values increase in all wood types. As the impregnation rate increased, the total color difference also increased.
AtıfScopus2WoS2TR Dizin1İncele - Kitap BölümüYalnız künye2022Gut effect on phytochemicals
Cebeci, Fatma
The gut microbiota play an important role for host nutritional, physiological, immunological functions like food digestion, vitamin production, protection of gut integrity, regulation of host immunity, and disease pathogenesis. Dietary phytochemicals are important factors to shape and change the human gut microbiota composition in diversity and abundance context. On the other hand, the microbial community of the gut provides a broad range of enzymes to host which are different from its own resources. This enables human gut microbiota to affect and direct the biosynthesis and metabolism of many bioactive compounds. Bioavailability of phytochemicals is important to benefit from health conferring effects of these compounds. Most of the phytochemicals are not absorbed well by the small intestine and pass through to the gut then gut microbiota acts on the compounds to form different metabolites. Therefore, elucidating the role of human gut microbiota on phytochemical metabolism is essential. This chapter discusses the studies reporting the gut microbial effect on different phytochemicals.
- MakaleAçık Erişim2022Scopus SJRQ2Efficient bioreduction of cyclohexyl phenyl ketone by Leuconostoc pseudomesenteroides N13 biocatalyst using a distance-based design-focused optimization model
Özdemir, Akın; Şahin, Engin
Whole-cell biocatalysts have been a popular method for the preparation of chiral alcohols. Although asymmetric reduction of cyclohexyl(phenyl)methanone (1) by chemical catalysts is common, a biocatalytic asymmetric reduction is extremely rare. In this respect, we report herein that Leuconostoc pseudomesenteroides N13 was successfully employed as a biocatalyst to reduce 1 to (S)-cyclohexyl(phenyl)methanol ((S)-2). Furthermore, the use of a mathematical optimization strategy for asymmetric reduction of substrate 1 is not known in the current literature. The new distance-based design-focused optimization model was used to enhance the conversion of the substrate, enantiomeric excess (ee) of product, and yield. The distance-based design-focused optimization model identified the following optimal bioreduction conditions: pH=6.46, temperature=30°C, incubation period=72 hours, and agitation speed=199 rpm. Then it was stated that under these ideal conditions, (S)-2 may be produced with 99 % ee and 98.46 % conversion rate (cr). (S)-2 was achieved with 99% ee, and 99% cr as a consequence of the experimental reaction carried out under the indicated optimization conditions. It has been shown that Leuconostoc pseudomesenteroides N13 can be utilized as a biocatalyst in asymmetric reduction reactions. This study, in addition to being the first example of a bioreduction of substrate 1 by mathematical optimization, also demonstrates for the first time the distance-based design-focused model can be used in the bioreduction reaction.
AtıfScopus9WoS9OpenAlex8İncele - MakaleAçık Erişim2022Scopus SJRQ1Comparative seismic design optimization of spatial steel dome structures through three recent metaheuristic algorithms
Carbas, Serdar; Artar, Musa
Steel dome structures, with their striking structural forms, take a place among the impressive and aesthetic load bearing systems featuring large internal spaces without internal columns. In this paper, the seismic design optimization of spatial steel dome structures is achieved through three recent metaheuristic algorithms that are water strider (WS), grey wolf (GW), and brain storm optimization (BSO). The structural elements of the domes are treated as design variables collected in member groups. The structural stress and stability limitations are enforced by ASD-AISC provisions. Also, the displacement restrictions are considered in design procedure. The metaheuristic algorithms are encoded in MATLAB interacting with SAP2000 for gathering structural reactions through open application programming interface (OAPI). The optimum spatial steel dome designs achieved by proposed WS, GW, and BSO algorithms are compared with respect to solution accuracy, convergence rates, and reliability, utilizing three real-size design examples for considering both the previously reported optimum design results obtained by classical metaheuristic algorithms and a gradient descent-based hyperband optimization (HBO) algorithm.
AtıfScopus15WoS13OpenAlex15İncele - MakaleYayıncıda açık erişim2022Scopus SJRQ3Thiol disulfide homeostasis in primary dysmenorrhea
Savrun, Atakan; Savrun, Şeyda Tuba; Dirican, Ebubekir; Gökçen, Emre; Arıcı, Yeliz Kasko; Aygün, Ali; Korkmaz, Vakkas; Neşelioğlu, Salim; Erel, Özcan; Kıran, Tuğba Raika
Oxidative stress is defined as a result of the loss of balance between the production of free radical or reactive oxygen species and the antioxidant system. This study aimed to determine the level of thiol-disulfide homeostasis (TDH) in the serum of women with primary dysmenorrhea. The study group consisted of 42 subjects with primary dysmenorrhea, and the control group consisted of 30 volunteer women with demographic characteristics similar to the study group. Native thiol (SH), total thiol (TSH), disulphide (SS), and SH/SS parameters were measured for TDH of the subjects. The SH (p = 0.038) and SH/TSH (p = 0.046) levels were significantly higher while SS (p = 0.013), SS/SH (p = 0.042) and SS/TSH (p = 0.046) levels were lower in the study group than in the healthy control group. The SS cut-off value was determined as 17.85 in the study group (sensitivity = 61.9%, specificity = 43.3%). Therefore, the probability of dysmenorrhea may increase significantly when SS levels fall below this value. In subjects with dysmenorrhea, there was a decrease in SS levels and an increase in SH levels in order to protect the cells and tissues from the harmful effects of free radicals.
AtıfOpenAlex1İncele - MakaleAçık Erişim2022Scopus SJRQ1Conventional and Microcellular Injection Molding of a Highly Filled Polycarbonate Composite with Glass Fibers and Carbon Black
Yilmaz, Galip; Devahastin, Apichart; Turng, Lih-Sheng
Conventional solid injection molding (CIM) and microcellular injection molding (MIM) of a highly filled polycarbonate (PC) composite with glass fibers and carbon black were performed for molding ASTM tensile test bars and a box-shape part with variable wall thickness. A scanning electron microscope (SEM) was used to examine the microstructure at the fractured surface of the tensile test bar samples. The fine and uniform cellular structure suggests that the PC composite is a suitable material for foaming applications. Standard tensile tests showed that, while the ultimate strength and elongation at break were lower for the foamed test bars at 4.0–11.4% weight reduction, their specific Young’s modulus was comparable to that of their solid counterparts. A melt flow and transition model was proposed to explain the unique, irregular “tiger-stripes” exhibited on the surface of solid test bars. Increasing the supercritical fluid (SCF) dosage and weight reduction of foamed samples resulted in swirl marks on the part surface, making the tiger-stripes less noticeable. Finally, it was found that an injection pressure reduction of 25.8% could be achieved with MIM for molding a complex box-shaped part in a consistent and reliable fashion.
AtıfScopus2WoS2OpenAlex3İncele - MakaleAçık Erişim2022Scopus SJRQ4Angle Conceptions of Students with Learning Disabilities and Hearing Impairments; [Öğrenme Güçlüğüne Sahip ve İşitme Engelli Öğrencilerin Açı Kavrayışları]
Güven Akdeniz, Dilşad; Gürefe, Nejla; Arikan, Ahmet
The angle concept is central to the development of geometry knowledge, which is important and functional for everyday life. In this context, the aim of this study was to examine the understanding of the angle concept of middle school students with learning disabilities (LDs) and hearing impairment (HI). The participants of this study, which was a case study, were identified with the criterion and convenience sampling methods. The participants were two students, one of whom with LDs and the other had a HI, each of whom was in grade 6. Data collected through individual clinical interviews with the students were analyzed using the cross-case analysis method. According to the findings of the study, the angle conception of both students was limited to the shape of the angle, and both students were aware of the concept of direction in the angle, but the student with the LD perceived the angle more statically, and did not have enough knowledge about the angle measurement or its unit. It was seen that the student with the HI confused the angle and angle measure, but was aware of the various angles according to their measures.
AtıfScopus2WoS1OpenAlex2İncele