Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Uzun, Sevda(64)
- Merdan, Mehmet(47)
- Baltaci, Cemalettin(35)
- Kulakaç, Nurşen(28)
- Duran, Celal(27)
- Ozdes, Duygu(24)
- Turan, Ibrahim(24)
- Demir, Selim(23)
- Türkkan, Tuğba(22)
- Bayrakdaroglu, Serdar(21)
- Topal, Fevzi(21)
- Öztürk, Serkan(21)
- Ürkek, Bayram(21)
- Gücer, Mehmet Ali(20)
- Akar, Zeynep(19)
- Kaygusuz, Abdullah(19)
- Topal, Meryem(19)
- Anaç, Halil(18)
- Aydin, Aydanur(18)
- Batan, Nevzat(18)
- Erata, Hüseyin(18)
- Tuncer, Metin(18)
- Akyürek, Suat(17)
- Baltacı, Cemalettin(17)
- Karimullah, Suud Sarim(17)
- Acet, Tuba(16)
- Akar, Bülent(16)
- Ashyralyyev, Charyyar(16)
- Düzgün, Azer Özad(16)
- Hintistan, Sevilay(16)
- Yılmaz, Coşkun(16)
- Aliyazicioglu, Yuksel(15)
- Kaya, Hacer(15)
- Kurnaz, Muammer(15)
- Kurt, Kemal(15)
- Ozden, Talat(15)
- Yilmaz, Coskun(15)
- Yuksel, Ferhat(15)
- Yücel, Cem(15)
- Öz, Mehmet(15)
Yayınlar
- Derleme MakaleAçık Erişim2018Problems Face to Organic Forage Plant Improvement and Their Recommended Solutions
Okcu, Melih
As the world's population increases tremendously, mankind harmed the environment by applying different techniques to be able to close the deficit for food and consequently this resulted in the questioning of the effects of production techniques on food security, quality, animal welfare and their impacts on environment. Organic agriculture is developed with the help of policies that are driven by environmental and food safety. Organic livestock farming increased correlated to the increase of organic agriculture. However, getting healthy, safe and sound products from animals is only possible with the consumption of well qualified feed. Nowadays, unsatisfactory field productions, improper soil cultivation methods and more other obstacles which restrict the improvement of forage plants. In this review article, the current situation of cultivation in Turkey as well as in the world, imperfections and solution offers to those problems are stated.
- MakaleAçık Erişim2018Do We Need Friendship in the Workplace? The Theory of Workplace Friendship and Employee Outcomes: The Role of Work Ethics
Ozbek, Mehmet Ferhat
This study builds and tests the models that two types of workplace friendships (friendship with coworkers and friendship with the supervisor) may have a negative influence on employees'job insecurity and turnover intention. Further, this study assumes that the positive association between workplace friendship with a supervisor and job performance is stronger for employees having a low work ethic than for those with a high work ethic. This study also assumes that the negative relationship between friendship with a supervisor and organizational deviance is stronger for employees who have a low work ethic but not for those with a high work ethic. To test these hypotheses, 313 data samples have been collected from service sector employees. According to the results, two types of workplace friendships (friendship with coworkers and friendship with a supervisor) are negatively related to job insecurity and turnover intention. The results also show that friendship with a supervisor was positively associated with job performance for employees having a low work ethic but not for those with a high work ethic. Furthermore, the results show that friendship with a supervisor was negatively associated with organizational deviance for employees having a low work ethic but not for those with a high work ethic. Surprisingly, the friendship with a supervisor is positively associated with organizational deviance for employees having a high work ethic.
AtıfWoS16OpenAlex16TR Dizin5
İncele - MakaleAçık Erişim2018Scopus SJRQ4Investigation of lsepamicin, Chloramphenicol and Minocycline Sensitivity in Carbapenem-Resistant Enterobacteriaceae
Karakullukçu, Asiye; Borsa, Baris Ata; Kuskucu, Mert Ahmet; Bakir, Esra; Taner, Zeynep; Özalp, Veli Cengiz; Aygün, Gokhan
Objective: In this study, we aimed to determine the resistance mechanisms of carbapenem-resistant Enterobacteriaceae (CRE), and evaluate the prospective alternative treatment options. Methods: Between October 2014 and July 2015, rectal swabs routinely obtained from hospitalized patients were included in the study. The isolated Gram-negative enteric bacteria were identified to the species level by using standard conventional microbiological methods. Determined carbapenem resistance in enteric bacteria was confirmed by using meropenem Etest (R) (bioMerieux, Marcy l'Etoile, France), and the resistance mechanisms were investigated with MAST-ID (TM) Discs (Mast Diagnostics Ltd, Bootle, Merseyside, UK). Antibiotic susceptibilities of the CRE were determined by disk diffusion method using isepamicin, chloramphenicol, and minocycline disks (Oxoid, Basingstoke, Hampshire, UK). Results: Of the 3,323 rectal swabs sent to the laboratory during the study period, totally 84 (2.5%) CRE were isolated with one strain from each patient. Of the 84 CRE, 74 (88%) were Klebsiella pneumoniae and 10 (12%) were Escherichia coli. Among the 84 CRE, 66 (78.5%) with OXA-48, 11 (13.1%) with OXA48 + metallo-beta-lactamase (MBL), 1 (1.2%) with only MBL and 1 (1.2%) with AmpC + porin loss were detected, none of the strains were positive for KPC. In 5 (6%) strains, none of the resistance mechanisms were found. Of the 84 CRE, 80 (95.2%), 77 (91.6%) and 14 (16.6%) were found to be susceptible to isepamicin, chloramphenicol and minocycline, respectively. Conclusions: The OXA-48 type, endemic in Turkey, was also the most commonly detected carbapenemase in the study. It has been observed that isepamicin and chloramphenicol can be the potential antibiotics in the treatment of KDE-related infections.
AtıfWoS4OpenAlex2İncele - MakaleAçık Erişim2018Scopus SJRQ2Are extramedian symptoms associated with peripheral causes in patient with carpal tunnel syndrome? Electrodiagnostic and ultrasonographic study
Mansiz-Kaplan, Basak; Akdeniz-Leblecicier, Merve; Yagci, Ilker
Objective: To evaluate the relationship between extramedian spreading of sensorial symptoms and median and ulnar nerve cross-sectional area (CSA) and to compare the ultrasonographic and electrophysiological findings in patients with carpal tunnel syndrome (CTS) with or without extramedian sensory symptoms. Design: Cross-sectional study. Materials and methods: Patients with CTS were divided into two groups as with or without extramedian symptoms and were assessed clinically, electrophysiologically and ultrasonographically by three blind investigators. In electrophysiological tests, median and ulnar nerve conduction studies were performed. Nerve cross-sectional areas were measured at hook of hamate, psiform bone, radio-ulnar joint, one-third distal part of forearm, and medial epicondyle by ultrasonography. Findings: The study was completed with 61 patients (108 hands). Extramedian symptoms were present in 31 patients (54 hands). Finger grip strength was lower, pain values evaluated with visual analogue scale were higher in patients with extramedian symptoms (p < 0.05). There was no statistically significant difference in electrophysiological and ultrasonographic parameters. Conclusion: According to our results, extramedian symptoms are not related to nerve conduction studies or nerve ultrasonography, these symptoms may be explained with central sensitization in patient with CTS. (C) 2017 Elsevier Ltd. All rights reserved.
AtıfWoS7OpenAlex10
İncele - EditoryalAçık Erişim2018Scopus SJRQ3A rare coincidence of hypoplasia of the posterior mitral leaflet and the bicuspid aortic valve
Demirel, Muhittin; Acar, Emrah; Sivri, Serkan; Sökmen, Erdogan; Özbek, Sinan Cemgil
AtıfWoS1OpenAlex1İncele - MakaleAçık Erişim2018Cytotoxic Effect of Rhododendron luteum Leaf Extract on Human Cancer Cell Lines
Demir, Selim; Turan, Ibrahim; Aliyazicioglu, Yuksel
Rhododendron luteum belongs to the genus Rhododendron, members of which are frequently used in folk medicine. Various studies have investigated the cytotoxic effect of different Rhododendron species, but there have been limited studies of the cytotoxic effect of R. luteum. The aim of this study was to investigate the antioxidant properties and cytotoxic effect of R. luteum leaf extract on the human cancer cells. The total phenolic content (TPC), total flavonoid content (TFC), and reducing power of the extract were evaluated using spectrophotometric procedures. The cytotoxic effect of the extract on five cancers (human breast, colon, lung, prostate, and liver carcinoma) and human fibroblast cells was determined using the MTT assay. TPC and reducing power values of extract were found 173.2 +/- 3.97 mg gallic acid equivalents, and 629.5 +/- 3.49 mg trolox equivalents per g sample, respectively. R. luteum leaf extract exhibited selective cytotoxicity especially against colon (1.9 fold) and liver (2.2 fold) cancer cells compared to normal fibroblast cells. This is the first study to reveal the cytotoxic effect of R. luteum leaf extract. Further studies are now needed to identify the cytotoxic molecules in the extract and their mechanisms.
AtıfWoS15İncele - MakaleAçık Erişim2018Scopus SJRQ4Comparison of Different Dynamic Contrast Enhanced-Magnetic Resonance Imaging Descriptors and Clinical Findings Among Breast Cancer Subtypes Determined Based on Molecular Assessment
Dogan, Serap; Ozmen, Soner; Oz, Bahadir; Imamoglu, Hakan; Kahriman, Guven; Zararsiz, Gokmen; Ozturk, Mustafa
Background: Breast cancer is a heterogeneous disease with different molecular and histologic subtypes, clinical behaviors and prognosis. The same stage of disease and similar histopathological characteristics may show different treatment responses. Identification of breast cancer subtypes has become important for planning the targeted therapy and personalized management of patients. Objectives: To compare the clinicopathologic findings, dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) characteristics and associated MRI findings among breast cancer molecular subtypes. Patients and Methods: 267 pathologically proven invasive breast cancers in 263 patients were included. Clinicopathological findings, DCE-MRI findings and associated MRI findings were retrospectively evaluated and compared among breast cancer subtypes. Results: Invasive ductal carcinoma was the most common histological tumor type (87.6%). There were 222 (83.1%) masses and 45 (16.9%) non-mass enhancements. The molecular subtypes were luminal A in 174 (65.1%), luminal B in 45 (16.9%), human epidermal growth factor receptor 2 (HER2) positive in 24 (9%) and triple negative (TN) in 24 (9%) of the lesions. Spiculated mass margin was significantly associated with luminal A breast cancer (45.2%) and irregular shape was significantly more common in luminal A (86.3%) and luminal B lesions (95.1%) (P < 0.001). Larger mass size (P= 0.027), non-mass enhancement (P= 0.005), perilesional+ prepectoral edema and skin + perilesional+ prepectoral edema were significantly associated with HER2 positive breast cancer (P= 0.001). Higher histological grade, oval mass shape, circumscribed mass margin, intratumoral high/very high signal intensity on T2 weighted image (T2WI) were significantly associated with TN breast cancer (P < 0.001). Conclusion: Histological grade, size and morphological features of masses on DCE-MRI, intratumoral signal intensity on T2WI and edema pattern would be helpful to distinguish breast cancer subtypes.
AtıfWoS2OpenAlex2İncele - MakaleAçık Erişim2018Scopus SJRQ4The investigation of the lattice strains and crystallite sizes of Y358 and Y123 high-temperature superconductors
Duzgun, Ibrahim
In this study, the Y358 phase, the newest high-temperature superconductor member of the yttrium barium copper oxide family, was produced using the solid-state reaction technique. The Y358 superconductor exhibited the Meissner effect at low temperature (77 K). The X-ray diffraction spectra indicated that the crystal structure was almost identical to that of Y123, but with some impurity peaks. An X-ray peak broadening analysis was applied to determine the lattice strain, and the medial crystallite size was calculated perpendicular to the surface of the superconductor specimens. As a result of the analyses, it was determined that the crystallite size of the Y358 superconductor was about 1.125 times larger than that of the Y123 superconductor.
AtıfScopus12WoS9OpenAlex12
İncele - MakaleAçık Erişim2018Scopus SJRQ2The effect of apple cider vinegar and mushroom stalk supplementation on laying hens
Karaalp, Musa; Aksakal, Vecihi; Sarikaya, Sevim Beyza Ozturk; Urusan, Hilal; Bayram, Bahri; Zulkadir, Ayhan
The aim of this trial was to study the effects of consuming water with apple cider vinegar (ACV) and feed including mushroom (Agaricus bisporus) stalk (MS) on performance and certain egg characteristics. The hens were separated into four treatment groups (with 4 replicates and 6 hens per replicate). The experimental groups were control (not consumed ACV and MS), ACV (3 ml/l drinking water), MS (20 g/kg feed) and ACV+MS (combination). At the end of the experiment, among the performance criteria tested, body weight, feed intake, egg production and weight of eggs, and feed efficiency were not affected by the treatments (P>0.05). Treatments had no effect on physical external and internal egg characteristics. The amount of yolk malondialdehyde of the ACV and MS groups was lower than the control group (P<0.05) in stored eggs (28 d) (P<0.05).
AtıfScopus6WoS4OpenAlex7İncele - MakaleAçık Erişim2018Scopus SJRQ4Petrography, mineral chemistry and crystallization conditions of cenozoic plutonic rocks located to the north of Bayburt (Eastern Pontides, Turkey)
Kaygusuz, Abdullah; Yücel, Cem; Arslan, Mehmet; Sipahi, Ferkan; Temizel, Irfan; Çakmak, Gökhan; Güloglu, Z. Samet
The Eastern Pontides comprise many intrusive bodies varying in composition, size and age from Palaeozoic to Cenozoic. Especially Cenozoic aged bodies are commonly observed in the southern part, while they are rarely exposed in the northern part of the Eastern Pontides. In this study, the petrography and mineral chemistry of the Cenozoic aged Çiçekli, Somarova, Sorkunlu, Şaşurluk, Aydintepe, Kemerlikdagi and Pelitli plutons located to the north of Bayburt are determined, and the crystallisation conditions of the studied bodies were estimated by means of thermobarometer calculations. The studied plutons extend mostly in NE-SW directions and are approximately ellipsoid in shape. The contacts between the plutons and surrounding rocks are sharp, and plutons commonly contain mafic microgranular enclaves (MMEs) of different sizes. Petrographic and mineral chemistry studies reveal some disequilibrium textures reflecting the magma mixing process. Based on modal mineralogy, the plutonic rocks are gabbroic diorite, diorite, tonalite, granodiorite and monzogranite in composition. The rocks have fine to medium granular, porphyric, monzonitic, poikilitic, occasionally myrmekitic and micrographic textures. The main minerals are labradorite and albite (An68-02), magnesiohornblende and actinolite (Mg# = 0.6-0.9), diopside and augite (Wo44-46), clinoenstatite (En53-57) and Fe-Ti oxide minerals. Crystallization temperatures calculated from amphibole, biotite, clinopyroxene, magnetite and ilmenite minerals are 405°C to 1161°C, pressure values are 0.1 to 2.7 kbar, and oxygen fugacity (log10 fO2) is -20 to -12. Estimation of water content calculated by using amphiboles is between 2.9 and 6.8%. Based on obtained data, it is suggested that the studied plutons were emplaced at shallow depths (∼ 1-8 km).
AtıfScopus16WoS12OpenAlex9TR Dizin5İncele - MakaleAçık Erişim2018Scopus SJRQ1Cytotoxic effect of Rosa canina extract on human colon cancer cells through repression of telomerase expression
Turan, Ibrahim; Demir, Selim; Kilinc, Kagan; Yaman, Serap Ozer; Misir, Sema; Kara, Hanife; Genc, Berna; Mentese, Ahmet; Aliyazicioglu, Yuksel; Deger, Orhan
Rosa canina is a member of the genus Rosa that has long been used for medical objectives. Several studies have reported cytotoxic effects of different Rosa species, but there has been only limited investigation of the cytotoxic effect of R. canina. The purpose of the current study was to examine the potential effect of R. canina extract on cell viability, the cell cycle, apoptosis, and the expression of telomerase in human colon cancer (WiDr) cells. The cytotoxic effect of the extract was determined using MTT assay. The mechanism involved in the cytotoxic effect of the extract was then evaluated in terms of apoptosis and the cell cycle using flow cytometry. Mitochondrial membrane potential (MMP) was investigated using the fluorometric method, and expression levels of telomerase were studied using RT-PCR. R. canina extract exhibited a selective cytotoxic effect on WiDr cells compared with normal colon cells. The extract induced cell cycle arrest at the S phase and apoptosis via reduced MMP in WiDr cells. R. canina extract significantly repressed telomerase expressions at treatment times of 48 and 72 h in WiDr cells. Our results suggest that R. canina may have considerable potential for development as a novel natural product-based anticancer agent.
AtıfScopus56WoS45OpenAlex59İncele - MakaleAçık Erişim2018Scopus SJRQ3Investigation of the Effect of Recycled Asphalt Pavement Material on Permeability and Bearing Capacity in the Base Layer
Seferoǧlu, Ayşegül Güneş; Seferoǧlu, Mehmet Tevfik; Akpinar, Muhammet Vefa
The purpose of this research was to investigate the effects of recycled asphalt pavement (RAP) and cement content on the permeability and bearing capacity characteristics of aggregate base courses. Mixtures containing untreated RAP ranging between 0 and 100 percent and 1, 2, and 3% cement-treated RAP were subjected to laboratory tests (bitumen content, sieve analysis, modified proctor, soaked California bearing ratio (CBR), and constant-level permeability tests). The results showed that, as the RAP percentage in the mixture increased, CBR values decreased considerably. Moreover, there is a linear increase in the CBR values with cement treatment. Optimum moisture contents (OMC) and maximum dry densities (MDD) showed a decreasing trend. Increasing the cement percentages in 100% RAP blend increases the OMC and MDD values. The permeability of RAP showed a decrease as the percentage of RAP and cement increased in blends. The study showed that the CBR value of the 20% RAP blend is also obtained in the 100% RAP/3% cement-treated blend. Thus, it has been understood that cement is a suitable material in order to increase the use of RAP. In addition, the increase in the percentage of RAP and cement made the base course more impermeable.
AtıfScopus24WoS20OpenAlex32İncele - MakaleAçık Erişim2018Scopus SJRQ4Synthesis of fluorine-containing phthalocyanines and investigation of the photophysical and photochemical properties of the metal-free and zinc phthalocyanines
Çelenk Kaya, Elif; Ersoy, Sibel; Durmuş, Mahmut; Kantekin, Halit
4-(3-(Trifluoromethyl)benzylthio)phthalonitrile (1) was synthesized. Metal-free phthalocyanine 2, zinc(II) phthalocyanine 3 and cobalt(II) phthalocyanine 4 were synthesized starting with dinitrile compound 1. Photodynamic therapy properties of 2 and 3 were studied.
AtıfScopus8WoS7OpenAlex5İncele - Derleme MakaleAçık Erişim2018Scopus SJRQ1Late Cretaceous arc igneous activity: the Eğrikar Monzogranite example
Sipahi, F.; Kaygusuz, A.; Saydam Eker, Ç.; Vural, A.; Akpınar, İ.
The geochemical and Sr–Nd–Pb isotope properties, as well as the Laser Ablation Inductively Coupled Plasma and Mass Spectrometry (LA-ICP-MS) U–Pb zircon age, of Eğrikar Monzogranite in the eastern Pontides, are primarily investigated in this study with the aim of determining its magma source and geodynamic evolution. The U–Pb zircon age obtained from Eğrikar Monzogranite is 78 ± 1.5 Ma, thereby reflecting the age of monzogranite. The I-type Eğrikar Monzogranite comprises quartz, plagioclase (An35–45), orthoclase, muscovite, and biotite. The geochemical analyses of the Eğrikar Monzogranite indicate being medium K calc-alkaline, peraluminous, and resembling magmatic arc granite. The Eğrikar Monzogranite is enriched in large ion lithophile elements and light rare earth elements relative to high field strength elements. Chondrite-normalized rare earth element patterns have concave upward shapes (LaN/YbN 2.47–8.58) with pronounced negative Eu anomalies (EuN/Eu* = 0.29–0.65). Initial εNd(i) values vary between 1.85 and 2.18 and initial 87Sr/86Sr values between 0.7048 and 0.7067. Fractionation of plagioclase, hornblende, and apatite played an important role in the evolution of Eğrikar Monzogranite. The crystallization temperatures of the melts ranged from 770°C to 919°C based on zircon and apatite saturation temperatures. The geochemical and isotopic data suggest being generated by the partial melting of mafic lower crustal sources.
AtıfScopus38WoS32OpenAlex45İncele - MakaleAçık Erişim2018Scopus SJRQ3A rapid and sensitive spectrofluorometric method for the determination of au(III) based on fluorescence quenching of a 1,3,5-triphenyl-2-pyrazoline
Başoğlu, Aysel; Ocak, Ümmühan; Fandakli, Seda; Yayli, Nurettin
A simple, rapid, sensitive, and low-cost spectrofluorometric method was developed for the determination of Au(III) using 5-(2,3-dimethoxyphenyl)-3-(4-methoxyphenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (L) in ethanol/water. The method is based on the change in the fluorescence intensity at 464 nm after excitation at 355 nm as a result of the reaction between the ligand and Au(III). The fluorescent emission of ligand at 464 nm decreased with the increasing of Au(III) concentration. The ligand concentration, pH effect, response time, and effect of foreign ions were determined. From the results of fluorescence titration experiments, it was found that the ligand (1 × 10−7 M) was selective and sensitive to Au(III) in EtOH-H2 O (1:1, v/v, phthalate buffer, pH 4.0). The calibration curve showed good linearity in the concentration range of 17.4–237.6 µg L−1 Au(III). The limits of detection and quantification were 5.2 and 17.4 µg L−1 Au(III) with a response time of 1 min, respectively. Satisfactory accuracy was obtained for standard reference material (CRM-SA-C Sandy Soil C). The proposed method was successfully applied to the determination of Au(III) in tap water, sea water, and stream water samples, and high levels of recovery were obtained.
AtıfScopus4WoS4OpenAlex5TR Dizin1İncele - MakaleAçık Erişim2018Scopus SJRQ3Antioxidant properties and protective effect of Turkish propolis on t-BHP-induced oxidative stress in foreskin fibroblast cells
Misir, Sema; Aliyazicioglu, Yuksel; Demir, Selim; Turan, Ibrahim; Yaman, Serap Ozer; Deger, Orhan
Objective: Propolis is an important bee product, rich in polyphenolic compounds. It has antitumoral, antioxidant, antimutagenic, and other useful activities. Biological activities of propolis are generally attributed to its substance of polyphenolic compounds. The aim of this study was to investigate the in vitro antioxidant properties and reduction amount of intracellular reactive oxygen species (ROS) in human normal foreskin fibroblast cells by Turkish propolis ethanolic extract (EEP). Method: Total phenolic and flavonoid contents, reducing power, radical scavenging capacity, and iron chelating activity of EEP were determined using spectrophotometric methods. Intracellular ROS levels were determined by spectrofluorometric analysis with CM-H2 DCFDA. Results: Our results indicated that antioxidant activity was correlated with the higher total phenolic and flavonoid contents of EEP. The generated ROS levels were significantly decreased by EEP compared to only t-BHP group. Conclusion: Ethanolic propolis extract may be evaluated as a potency antioxidant resource and/or a novel natural agent in food and drug industries.
AtıfScopus11WoS15OpenAlex16İncele - BildiriAçık Erişim2018Thermal modeling and verification of pv module temperature and energy yield using outdoor measurements for Ankara, Turkey
Tuncel, Bilge; Akinoglu, Bulent G.; Ozden, Talat; Balog, Robert S.
Ankara is in the Central Anatolia region of Turkey where the climate is dry-continental with an annual solar insolation of around 1750 kWh/m 2 . In the transition to renewable energy, detailed analyses are required to ensure effective and economic utilization of the available solar resource. An essential part of these analyses is to calculate expected energy yield. For photovoltaic (PV) systems, this includes the effect of temperature on the PV efficiency, which determines the power yield of the PV modules. In this study, a first-principles thermal modeling approach is improved by adding the speed and direction of wind across the PV module into a forced convection term as well as including the temperature dependency of the module conversion efficiency. The analytical model is based on the principle of conservation of energy and uses meteorological data that are readily available from most state meteorological services. The mathematical analysis is suitable to predict the performance of a proposed PV installation without the time and expense of installing and monitoring a pilot system. The mathematical model is compared against measured data from the METU-GUNAM Outdoor Test Facility in Ankara to validate the methodology. Preliminary analyses showed that the model performs well especially during sunrise and sunsets shoulders of the diurnal cycle with a deviation of only a few W/m 2 for the electrical power yield and about 2°C for the module temperature. However, these deviations could become as large as 12 W/m 2 and 8°C at solar noon which suggests that the model still requires further improvement. In general, this error was found to be less that obtained by using basic explicit correlation methods and offers the advantage that it can be used for other geographical environments for which insolation and meteorological data is available without needing to construct a test-site.
AtıfScopus6WoS4OpenAlex6İncele - BildiriAçık Erişim2018Well-posedness of Neumann-type elliptic overdetermined problem with integral condition
Ashyralyyev, Charyyar; Çay, Aysel; Ashyralyev, A.; Sadybekov, M.; Lukashov, A.
The current paper is devoted to overdetermined elliptic problem with integral condition for derivatives. This overde-termined problem is converted to auxiliary nonlocal boundary value problem (ANBVP) with integral boundary condition. Well-posedness of abstract problem is established. Then, obtained results are used to obtain stability inequalities for solution of three Neumann-type inverse elliptic problems with integral condition to multidimensional differential equation.
AtıfScopus14WoS9OpenAlex16İncele - BildiriAçık Erişim2018Performance and degradation analyses of two different pv modules in central anatolia
Ozden, Talat; Akinoglu, Bulent G.; Kurtz, Sarah
Ankara (latitude: around 40°N) is in Central Anatolia and the climate is dry continental. Due to the rapid transition to renewable energy policies of Turkey it is now a must to complete truthful feasibility analyses for solar power systems countrywide. Long term performance and degradation analyses have been carried out by the authors for three different arrays and many research results appearing in the literature are summarized. Present research analyzes the outdoor testing results of two PV modules monthly data. One of the modules has multi crystalline silicon (Poly-Si) cells and the other is thin film silicon (amorphous Si / microcrystalline Si tandem structure - a-Si/μc-Si) cells. The results showed that in five years the average yearly efficiency decreases from 14% to 11% for Poly-Si (14.72% is the nameplate Standard Test Condition (STC) efficiency) and from 8% to 6% for thin film modules (9.15% is STC efficiency). Our calculations are based on measured solar global-horizontal irradiance from which we calculated plane-of-array irradiation using an anisotropic sky model. We present the details of these analyses and degradation rates for the two types of modules to be used in long term feasibility analyses.
AtıfScopus11OpenAlex10İncele - BildiriAçık Erişim2018Stress Analysis and Fatigue Behaviour of PTFE-Bronze Layered Journal Bearing under Real-Time Dynamic Loading
Duman, M.S.; Kaplan, E.; Cuvalci, O.; Hamamci, M.; Gocer, A.; Karamis, M.B.; Nair, F.; Savas, S.
The present paper is based on experimental studies and numerical simulations on the surface fatigue failure of the PTFE-bronze layered journal bearings under real-time loading. 'Permaglide Plain Bearings P10' type journal bearings were experimentally tested under different real time dynamic loadings by using real time journal bearing test system in our laboratory. The journal bearing consists of a PTFE-bronze layer approximately 0.32 mm thick on the steel support layer with 2.18 mm thick. Two different approaches have been considered with in experiments: (i) under real- time constant loading with varying bearing widths, (ii) under different real-time loadings at constant bearing widths. Fatigue regions, micro-crack dispersion and stress distributions occurred at the journal bearing were experimentally and theoretically investigated. The relation between fatigue region and pressure distributions were investigated by determining the circumferential pressure distribution under real-time dynamic loadings for the position of every 10° crank angles. In the theoretical part; stress and deformation distributions at the surface of the journal bearing analysed by using finite element methods to determine the relationship between stress and fatigue behaviour. As a result of this study, the maximum oil pressure and fatigue cracks were observed in the most heavily loaded regions of the bearing surface. Experimental results show that PTFE-Bronze layered journal bearings fatigue behaviour is better than the bearings include white metal alloy.
AtıfScopus4WoS5OpenAlex5İncele