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Correlation of proton conductivity and free volume in sulfonated polyether ether ketone electrolytes: a positron annihilation lifetime spectroscopy study
(Elsevier Ltd, 2025) Lahmuni, Muhammet; Yılmazoğlu, Mesut; Abacı, Ufuk; Çoban, Ozan; Yumak Yahşi, Ayse; Tav, Cumali; Yahşi, Uğur
Proton-conducting polymers play a pivotal role in clean energy technologies and various industrial applications, with a significant emphasis on enhancing energy efficiency and minimizing environmental impact. Sulfonated polyether ether ketone (SPEEK), which is renowned for its proton conductivity, has emerged as a key material in electrochemical processes, notably in proton exchange membrane (PEM) fuel cells. This study investigated the proton conductivity and dielectric behavior of SPEEK electrolytes at varying degree of sulfonation (DS) of 65% and 80%, correlating these properties with free volume profiles determined by positron annihilation lifetime spectroscopy (PALS). The SPEEK-65 and SPEEK-80 electrolytes were prepared via a controlled sulfonation process and characterized by FTIR, TGA, and SEM analyses. Proton conductivity and dielectric measurements were conducted at temperatures ranging from 300 to 370 K and frequencies ranging from 20 Hz to 1 MHz. The results revealed that SPEEK-80 exhibited a maximum proton conductivity of 3.4 × 10?2 S/m at 300 K and 1 MHz, which was significantly greater than the 4.38 × 10?3 S/m observed for SPEEK-65 under the same conditions. PALS analysis demonstrated a notable increase in free volume with increasing DS, with SPEEK-80 showing a higher o-Ps lifetime and intensity, indicating larger free volume sizes and fractions. These findings underscore the critical interplay between DS, free volume, and proton conductivity, offering insights into optimizing SPEEK-based electrolytes for advanced electrochemical applications.
Synthesis and characterization of metakaolin-based geopolymers doped with CRT waste glass for radiation shielding applications
(Elsevier, 2024) Al-Buriahi, M. S.; Kırkbınar, Mine; Alrowaili, Ziyad Awadh; Katubi, Khadijah Mohammedsaleh; Alsaiari, Norah Salem; Alalawi, Amani; Alomayrah, Nora; Olarinoye, I. O.
This study presents the influence of CRT glass on the gamma-ray interaction processes in metakaolin-based geopolymers. Four batches of G-CRT composites (namely, G, G-10CRT, G-20CRT, and G-30CRT, which represent geopolymer (G) samples doped with 0, 10, 20, and 30 wt% of CRT glass) were prepared using the cold hydrostatic press method. The mass attenuation coefficients of the prepared C-xCRT samples were computed using XCOM and FLUKA simulations for photons within the energy range of 15 keV-15 MeV. The density of the pristine geopolymer increased from about 1.86 g/cm3 3 to 2.09, 2.26, and 2.34 g/cm3 3 for G-10CRT, G-20CRT, and G-30CRT, respectively. The photon mass and linear attenuation coefficients of the geopolymers increased with CRT glass concentration. The half-value layer and mean free path were within the ranges 0.070-18.079 cm and 0.101-26.083 cm for G; 0.036-15.110 cm and 0.052-21.799 cm for G-10CRT; 0.024-13.197 cm and 0.014-19.039 cm for G-20CRT; and 0.018-12.074 and 0.026-17.419 cm for G-30CRT. The G-30CRT had the best gamma attenuating prowess in contrast to other G-xCRT. CRT-rich G-xCRT had a higher effective atomic number. For 10 mm thick geopolymer, the absorbed dose rates were 0.211 mu R/h, 0.66 mu R/h, 1.11 mu R/h, and 1.55 mu R/h for G, G-10CRT, G-20CRT, and G-30CRT, respectively, for 100 keV photons. The introduction of CRT glass into the geopolymer matrix improved their photon interaction cross-section. The geopolymers showed outstanding photon interaction ability compared to ordinary concrete and some shielding glasses at low photon energies. The CRT glass-doped geopolymer samples are useful for preparing radiation shielding concrete.
Development of hybrid actuator system for recovery of the model rockets
(Institute of Electrical and Electronics Engineers Inc., 2024) İpek, Gülhas; Dalkıran, Atılay; Dilibal, Savaş
Model rockets are the advanced mechatronic systems established through the design, manufacturing, and integration of the model-scale mechatronic sub-systems for a rocket mechanism capable of operating at low altitudes. The safe recovery and reusability of model rockets are prominent tasks to address. Various actuator systems are used in model rockets to solve the safe recovery problem by safely releasing and recovering the payloads that they carry at specific altitudes, allowing the rockets to be recovered. Traditionally, model rockets have employed recovery units powered by gunpowder. This research aims to design a novel hybrid actuator system integrating mechanical components with pressurized gas and servo motor components as an alternative to traditional gunpowder systems to enhance reliability and safety. The objective is to develop a prototype of a hybrid recovery actuator system using CO2 tubes and servo motors. The principle behind the designed recovery system relies on the release of CO2 gas, which facilitates the separation of the rocket motor body from the main body. This principle is based on the mechanism within the designed actuator system, which functions by releasing the potential energy stored in compressed springs. Servo motors triggered by signals from the rocket's flight computer release the springs, allowing the CO2 gas to escape. The released gas separates the rocket bodies, ensuring a safe descent. Within the scope of this research, the efficiency and effectiveness of the CO2 based hybrid recovery actuator system are evaluated through the production of a prototype. The experimental results unveiled that the development of the CO2 based hybrid recovery actuator system enables safe and successful recovery of model rockets. To achieve the timely release of the CO2 gas in the recovery system, the required pressure is determined via experimental studies for the separation of rocket bodies, ensuring a safe descent.
Study of the heat?mass transfer process considering the well?reservoir system in fractured reservoirs
(Geology and Geophysics Institute at Azerbaijan National Academy of Sciences (ANAS), 2023) Jalalov, G.; Rasulov, M.; Sinsoysal, Bahaddin
The theoretical study of oil field development processes and the creation of adequate technological schemes, taking into account the possible compound physical processes occurring in the field to ensure optimal exploitation of deposits, highlight the necessity of a complex scientific approach. Besides the geological-geophysical data required for the creation of technological schemes, obtaining the physical data of the deposit is one of the important factors. Obviously, much of these data come from wells drilled into the reservoir. The most important aspect of these studies is the investigation of the mass exchange and phase transition mechanisms of hydrocarbons, taking into account the pressure and temperature changes in the reservoir and the well during liquid filtration. In this paper, the effect of pressure and temperature changes during the processing of hydrocarbon deposits on exploitation indicators is examined by considering the well-reservoir system.
(?i, ?)-constacyclic codes and DNA codes over Z4
(AIMS Mathematics, 2024) Uzekmek, Fatma Zehra; Öztaş, Elif Segah; Özen, Mehmet
In this paper, three new automorphisms were identified over the ring Z(4)+uZ(4)+u(2)Z(4) where u(3 )= u(2). With the help of these automorphisms, the characteristic structures of the generator polynomials for the theta i-cyclic codes and (theta(i),lambda)-constacyclic codes of odd length on this ring were investigated. Also, for all the units over the ring, Z(4)-images of theta i-cyclic and (theta(i),lambda)-constacyclic codes were reviewed with the associated codes based on determined transformations. Using these observations, new and optimal codes were obtained and presented in the table. In addition, a new transformation was identified that involved DNA base pairs with the elements of Z(4). Moreover, a unit reverse polynomial was created, and in this way a new generation method has been built to construct reversible DNA codes over this ring. Finally, this article was further enhanced with supporting examples of the DNA as a part of the study.
Investigating ultra-thin rGO coated ZnO core-shell structures in MOS devices: electrical/dielectric characteristics and relaxation mechanism
(Elsevier Ltd, 2024) Kırkbınar, Mine; İbrahimoğlu, Erhan; Demir, Ahmet; Çalışkan, Fatih
The study focused on the relaxation and polarisation mechanisms of Al/(rGO:ZnO core-shell)/pSi/Al MOS structures. For this purpose, the rGO:ZnO core-shell structures were synthesised by sol-gel procedures and coated on pSi by spin-coating. The structures were characterized as chemical, morphological and micro-structural using FESEM-EDS, AFM, XRD and Raman analysis. Additionally, the capacitance (C), conductance (G/omega), dielectric permittivity (epsilon ' and epsilon ''), loss factor(tan delta), electric modulus(M ' and M '') of the samples were successfully examined by DS over the wide range of frequencies (100 Hz-1 MHz) for determining dielectric parameters. Three distinct regions were visible on the C-V and C-omega plots: accumulation (-4 to 0 V), depletion (0 to 2 V), and inversion (2 to 4 V). Two relaxation times (10(-4)s-10(-7)s) were obtained in epsilon '-V and epsilon '-omega graphs between 1-100 kHz (region 1) and 100 kHz-1 MHz (region 2). The relaxation times were according to the Maxwell-Wagner and dipolar polarisation mechanism. As a result, the capacitive effect was observed and the equivalent RC circuit obtained from the Cole-Cole diagrams allowed the samples to be used in energy storage or different electronic applications.
Microstructural and mechanical characterizations of weld metal of S960QL ultra high strength steel joints obtained with different multi-pass laying techniques using GMAW
(Institute of Physics, 2024) Mert, Tolga; Gürol, Uğur; Tümer, Mustafa
15 mm thick ultra-high strength steel plates with 960 MPa yield strength were welded using different multi-pass laying techniques (i.e., stringer and weaving beads) with torch manipulation. Weld metals obtained were compared using different mechanical (i.e., micro tensile tests and Vickers hardness maps) and microstructural (i.e., optical microscope, scanning electron microscope, x-ray diffraction, electron backscatter diffraction) characterization techniques. Coarser grains and acicular ferrite were observed in weld metal obtained with the weaving pass procedure. There were hardness differences in the face and root passes of both weld metals. Yet, hardness values were 19% and 11% higher for the face and root regions of the joint obtained by stringer pass procedure, respectively. Fractographs of micro tensile test specimens revealed dimples depicting ductile network structure for both joints.
Tailored proton conductive membranes of PVdF-co-HFP: investigating the synergistic effects of ammonium tetrafluoroborate and phosphoric acid dopants on dielectric characteristics
(Institution of Chemical Engineers, 2024) Yılmazoğlu, Mesut; Abacı, Ufuk; Erdemi, Hamit; Çoban, Ozan
This study investigates the structural, thermal, and dielectric properties of pure PVdF-co-HFP matrix and its composite electrolytes, PVdF-co-HFP/NH4BF4[x], both before and after PA doping, using FTIR, SEM, TGA, and dielectric analyses. FTIR spectra reveal characteristic vibrational bands, confirming the presence of various functional groups and phases. SEM images display a smooth and homogeneous surface morphology for pure PVdF-co-HFP, while the composite electrolytes exhibit irregular dispersion of NH4BF4 salt and rougher surfaces upon PA doping. TGA analysis shows that the onset of thermal degradation occurs at approximately 370 ? for pure PVdF-co-HFP, while PA-doped samples demonstrate higher decomposition temperatures, exceeding 400 ? due to hydrogen bonding and ionic complex formation. The presence of NH4BF4 and PA doping also affects the crystallinity of the PVdF-co-HFP matrix, notably shifting the transition temperatures of the alpha and beta phases. Ionic conductivity measurements indicate that PA doping significantly enhances conductivity by increasing charge carrier concentration and facilitating ion transport. PA-doped PVdF-co-HFP/NH4BF4[10] showed the highest conductivity reaching 1.68 × 10?3 S.cm?1 at 1 MHz and 400 K. Dielectric studies reveal frequency-dependent behavior, with dielectric constant (?') and loss (?") showing distinct trends influenced by salt concentration and PA doping. The dielectric tangent loss (tan?) of PA-doped PVdF-co-HFP/NH4BF4 composite membranes exhibits frequency and temperature dependence. At higher temperatures, tan? increases with frequency, showing a resonance peak that shifts towards higher frequencies. The study elucidates the impact of PA doping on the structural, thermal, and electrochemical performance of PVdF-co-HFP/NH4BF4 composites, providing insights for their potential applications in advanced electrolyte systems.
Investigating ultra-thin rGO coated ZnO core-shell structures in MOS devices: electrical/dielectric characteristics and relaxation mechanism
(Elsevier Ltd, 2024) Kırkbınar, Mine; İbrahimoğlu, Erhan; Demir, Ahmet; Çalışkan, Fatih
The study focused on the relaxation and polarisation mechanisms of Al/(rGO:ZnO core–shell)/pSi/Al MOS structures. For this purpose, the rGO:ZnO core–shell structures were synthesised by sol–gel procedures and coated on pSi by spin-coating. The structures were characterized as chemical, morphological and micro-structural using FESEM-EDS, AFM, XRD and Raman analysis. Additionally, the capacitance (C), conductance (G/?), dielectric permittivity (?? and ??), loss factor(tan?), electric modulus(M? and M?) of the samples were successfully examined by DS over the wide range of frequencies (100 Hz-1 MHz) for determining dielectric parameters. Three distinct regions were visible on the C-V and C-? plots: accumulation (?4 to 0 V), depletion (0 to 2 V), and inversion (2 to 4 V). Two relaxation times (10-4s-10-7s) were obtained in ??-V and ??-? graphs between 1–100 kHz (region 1) and 100 kHz-1 MHz (region 2). The relaxation times were according to the Maxwell-Wagner and dipolar polarisation mechanism. As a result, the capacitive effect was observed and the equivalent RC circuit obtained from the Cole-Cole diagrams allowed the samples to be used in energy storage or different electronic applications.
Proton conductivity and dielectric studies on chitosan/polyvinyl alcohol blend electrolytes: synergistic improvements with ionic liquid and graphene oxide
(Elsevier B.V., 2024) Yılmazoğlu, Mesut; Okkay, Hikmet; Abacı, Ufuk; Çoban, Ozan
This study investigates the impact of ionic liquid, 1-methylimidazolium tetrafluoroborate (IL) and graphene oxide (GO) on the performance of chitosan/polyvinyl alcohol (CS/PVA)-based composite electrolytes. Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) confirm the successful incorporation of IL and GO, affecting the structural and morphological properties of the electrolytes. Thermogravimetric analysis (TGA) reveals enhanced thermal stability in GO-doped samples, with increased residual weight at high temperatures, while IL addition leads to higher initial weight loss due to its hygroscopic nature. Ionic conductivity measurements demonstrate that the CS/PVA/IL-GO(4.0) composite achieves the highest proton conductivity of 1.76 × 10?3 S/m at 300 K and 1 MHz, surpassing other samples and aligning with top values reported in literature. Dielectric studies show a significant increase in dielectric constant to 9.55 × 104 at 300 K and 20 Hz for CS/PVA/IL-GO(4.0), attributed to enhanced dipole alignment and polarization effects. The loss tangent analysis indicates the shortest relaxation time of 2.07 × 10?4 s for CS/PVA/IL-GO(4.0), correlating with its superior proton conductivity. These findings highlight the potential of CS/PVA/IL-GO electrolytes for advanced energy storage and conversion applications, suggesting further research into GO dispersion and long-term stability for optimized performance in practical devices.
Investigation of the network made with the complementary motor of the thalamus with the DTI method in individuals with tinnitus
(Kare Publishing, 2024) Elpen Karyemez, Pınar; Yağımlı, Mustafa; Tozan, Hakan
Objectives:This This study aimed to investigate the differences in the networks between the thalamus and the supplementary motor area in brain MRI examinations of individuals with subjective chronic tinnitus and healthy control groups. Methods: In the study, brain MRI imaging was performed on 47 patients suffering from bilateral tinnitus for two years or more and 42 healthy individuals. The tensor information obtained using the diffusion tensor imaging sequence data obtained from both groups was processed in the DSI Studio program. Brain connection maps were obtained from the data obtained. Quantitative information of the individual connecogram maps of each case was recorded and the groups were compared. Results: In the tinnitus group, there is an increase in the pathways between the thalamus and the supplementary motor area. In addition, it was determined that the pathways of the thalamus with the hippocampus, superior and middle occipital area and frontal area increased, and the pathways with the hippocampus and cerebellum decreased. Conclusion: Important functions of the supplementary motor area and thalamus; These are cognitive actions in which attention plays an important role, such as noticing the stimulus from the environment, planning and implementing the response action. It is thought that changes in the pathways between the thalamus and the supplementary motor area will especially affect attention-related functions.
Analysis and evaluation of quality parameters of commercial propolis products using a new high Performance Liquid Chromatography (HPLC) method and Comparison of antimicrobial properties
(Elsevier Inc., 2024) Karagül, Bora; Uğraş, Serpil; Karagül, Pınar; Usta, Mehtap; Uğraş, Halil İbrahim
Propolis, which has an important place in functional foods, is a natural bee product with high biological active value and is consumed in different formulations and packages worldwide. Thanks to the active compounds it contains, propolis shows biological properties such as antibacterial, antifungal, antiviral, antiprotozoal, antitumoral, antiulcer and anti-inflammatory. However, it is seen that propolis supplements are prepared unconsciously in the market. Such commercial products need to be standardized. Within the scope of this study, characteristic compounds of Turkish propolis were initially determined with support from the literature. Subsequently, bioactive components of 23 commercial propolis products were analyzed using the new HPLC method. Then, the flavonoid content and antimicrobial activity of the samples were determined. According to the results of these analyses, the amounts of Caffeic Acid (2,16-1620,57 ppm, Quercetin (0,19-203,99 ppm), Apigenin (0,30-319,08 ppm), Kaempferol (0,56-251,15 ppm), Chrysin (3,97-2830,93 ppm), and Caffeic Acid Phenethyl Ester (13,08-9666,48 ppm) were found to be quite different. The highest flavonoid content was measured as P2: 20847,43 mg/L and the lowest was 00003,10 mg/L in sample P13. Samples prepared for children were found to be highly diluted in terms of content. Again, it was determined that the samples with high preservation of active ingredients were products with production certificates based on laboratory analyzes. The samples were generally found to have inhibition activity against Gram (+) bacteria. Propolis samples P6 and P22 showed high activity against Gram (+) and Gram (-) bacteria and even fungi. When we evaluated some products that are insufficient in terms of content and antimicrobial activity, it was observed that antimicrobial activity increased depending on the other auxiliary chemicals used in the products. In this context, propolis products, which are very valuable in terms of health, may lose their real activity due to uncontrolled production and will gradually be devalued in the market. It is important that this valuable product should be produced and offered to the market with the necessary analysis methods without losing its effectiveness.
A comparative study of silver electrodeposition from pyrophosphate-cyanide and high concentration cyanide electrolytes in the presence of brighteners
(Tubitak Scientific & Technological Research Council Turkey, 2020) Akben, Hatice Kübra; Timur, Servet İbrahim
A study of the electrodeposition of silver from 2 different types of electrolytes; (1) neutral pyrophosphatecyanide electrolyte and (2) alkaline high concentrated cyanide electrolyte in the presence of a variety of additives such as 2-mercaptobenzothiazole, potassium selenocyanate, and potassium antimony tartrate was performed. Influence of additives and cyanide concentration on microstructure and kinetics of the cathodic processes were studied. A brightener couple, 2-mercaptobenzothiazole and potassium antimony tartrate, were combined within this investigation and detected to be highly effective for silver electrodeposition. The rapid increase in current density at the same potential interval related to grain refinement effect of potassium antimony tartrate was shown. The cyclic organic compound, 2-mercaptobenzothiazole, polarizes the reduction to high cathodic potential in pyrophosphate electrolyte. However, the sufficient levelling effect required for the mirror-bright appearance seems to be related to the high polarizing effect of the high concentration cyanide content. In the case of pyrophosphate electrolytes, sufficient levelling cannot be achieved, so semigloss coatings are obtained. The low cathodic potential electrodeposition of silver in pyrophosphate electrolyte, which is found to proceed by 3D instantaneous nucleation, is polarized to high cathodic potentials and grows into 3D progressive nucleation and diffusion-controlled growth in high concentration cyanide electrolyte.
Veri madenciliği karar ağaçları kullanarak ülkelerin inovasyon değerlerinin tahmini ve doğrusal regresyon modeli ile karşılaştırmalı bir uygulama
(İstanbul Üniversitesi, 2021) Doğruel, Merve; Ümit Fırat, Seniye
Ülkelerin sahip olduğu inovasyon seviyeleri ve kapasiteleri, günümüzde hem rekabet edebilirlik hem de yaşamakta olduğumuz Endüstri 4.0 Devrimi açısından son derece önemlidir. Bu kapsamda bakıldığında, ülkeler açısından kapasite ve seviye göreceli bir kavram olarak kalmaktadır ve küresel karşılaştırmalar açısından ortak bir ölçme sistemine gereksinim vardır. Bu ihtiyacı önemli ölçüde karşılayan Ağ Yapılara Hazır Olma Endeksi (AYHOE) ve Küresel İnovasyon Endeksi (KİE), ülkelerin inovasyon seviyelerinin belirlenmesinde etkili ve kapsamlı endekslerdir. Ayrıca her iki endeks de akademik altyapıya sahiptir ve bu nedenle araştırmacılar için önemli bir veri kaynağıdır. Bu çalışma, KİE değeri ve AYHOE endeksine ait alt endekslerin boyutlarında yer alan göstergeler kullanılarak, denetimli makine öğrenmesi temellerine dayanan bir veri madenciliği tekniği olan regresyon ağacı analizi ve doğrusal regresyon analizi uygulamalarını ve karşılaştırmasını içermektedir. Araştırmanın amacı regresyon ağacı uygulayarak, AYHOE göstergelerinden hareketle KİE tahminlemesi yapmak ve en iyi ayrılmayı sağlayan KİE göstergelerini belirlemektir. Analiz için Sınıflandırma ve Regresyon Ağacı ((SRA) - Clasification and Regression Tree (CART)) algoritması kullanılmıştır. Analiz sonucunda AYHOE kapsamındaki hangi göstergelerin, KİE değerleri tahmininde ve ülke sıralamasında kullanılabileceği belirlenmiştir. Aynı veri seti kullanılarak doğrusal regresyon analizi uygulanmıştır. SRA algoritması ile elde edilen regresyon ağacı sonuçları, doğrusal regresyon modelinden elde edilen çıkarımlar ile karşılaştırılmıştır.
Endüstriyel hücrelerde bulanık tabanlı taşıma yöntemi seçimi için geliştirilen bir yaklaşım: vaka çalışması
(Gazi Üniversitesi, 2023) Ateş, Ozan; Durmuroğlu, Mehmet Bülent
Lojistiğin diğer boyutlarının aksine üretim lojistiği veya iç lojistik ile ilgili literatürde yeterli sayıda denebilecek çalışma mevcut değildir. Hâlbuki üretim faaliyetleri içerisinde lojistik, önemli bir yer işgal eder, üretimin süresine ve ürün kalitesine doğrudan etki eder. Böylesine önemli olan üretim lojistiği ile ilgili literatürdeki sınırlı sayıdaki çalışmaya bakıldığında çalışmaların depolama stratejilerinin belirlenmesi, depolama araçlarının seçimi, malzeme tasıma hareketlerinin yapılandırılması, malzeme tasıma araç türlerinin seçimi, hücresel yerleşim, hücre içi ve hücreler arası hareketlerin yapılandırılması ile ilgili olduğunu görüyoruz. Bulanık tabanlı bir seçim yaklaşımı olan bulanık ve ağırlıklandırılmış bulanık bilgi aksiyomunun endüstriyel hücrelerdeki taşıma faaliyetleri için kullanılması literatürde yeni sayılabilecek bir çalışma olacaktır. Aksiyomlarla tasarım metodolojisi içerisinde yer alan bilgi aksiyomu, en yalın iç lojistik taşıma yönteminin belirlenmesinde kullanılmıştır. Yalın lojistik yalın üretimin lojistik boyutudur. Makalemizle ilgili bir otomotiv yan sanayi firmasının fabrikasında uygulama çalışması yapılmıştır. Üretim ortamında kullanılabilecek farklı taşıma yöntemleri mevcuttur. Bulanık bilgi aksiyomu ve ağırlıklandırılmış bulanık bilgi aksiyomu kullanılarak müşteri beklentilerin en çok sağlayan, en yalın ve en verimli hücre besleme yöntemi bulunmaya çalışılmıştır. Mevcut iç lojistik taşıma yöntemi ile önerilen yalın iç lojistik taşıma yöntemi arasındaki farklara çalışmamızda yer verilmiştir. Karar vericilerin tereddütten uzak karar verebilmelerine yardımcı olabilmek için duyarlılık analizi ile çalışmamız güçlendirilmiştir.
Developing a virtual safety training tool for scaffolding and formwork activities
(Turkish Chamber Civil Engineers, 2022) Kazar, Gökhan; Çomu, Semra
As occupational accidents usually occur due to unsafe human behaviours in the construction industry, safety training is inevitably necessary for site personnel. On construction sites, various training methods including traditional and innovative ones, have been adopted to prevent accidents. In recent years, virtual safety training has been more prevalent because of providing highly engaging practice in a risk-free environment. Although these training tools have innumerable advantages in providing safety knowledge and awareness, they can be further improved. This study introduces a virtual safety training tool, V-SAFE.v2, to provide a more reliable and effective safety training for high-risk construction works. V-SAFE.v2 consists of three main modules; i) Training Module, ii) Testing Module 1, and iii) Testing Module 2. These modules are generated firstly to provide safety training for scaffolding and formwork activities and then to evaluate the safety performance of the trainees. An experiment was conducted with fifteen construction workers and ten engineers to measure the effectiveness of the training tool. The findings showed that V-SAFE.v2 is a reliable safety training tool for high-risk construction tasks as it supports collaboration, provides individual feedback, and repeatable practice. Also, the participants stated that V-SAFE.v2 has a great potential to reduce the falling from height accidents in the construction workplaces.
Temperature dependent electrical and electrocaloric properties of textured 0.72PMN-0.28PT ceramics*
(Taylor & Francis Ltd, 2022) Böbrek, İrem; Berksoy Yavuz, Ayşe; Kaya, Mustafa Yunus; Alkoy, Sedat; Okatan, Mahmut Barış; Mısırlıoğlu, İbrahim Burç; Mensur Alkoy, Ebru
Lead magnesium niobate (PMN) - lead titanate (PT) solid solution ceramics in the ratio of 0.72PMN-0.28PT was produced by a combination of tape-casting in ?001?(pc) textured and random forms. The Lotgering factor, f, of textured ceramics was approximately calculated as 80%. Modified Curie-Weiss analysis indicated relaxor dominant behavior for both the random and textured ceramics. Development of texture led to an enhancement in the electromechanical properties with converse piezoelectric charge coefficient (d(33)*) under 20 kV/cm electric field reaching 545 pm/V for the textured ceramic. Electrocaloric (EC) behavior of random and textured ceramics were obtained from indirect measurements using temperature dependent polarization vs. electric field hysteresis loops. An EC temperature change (Delta T-EC) of similar to 0.5 K was calculated from the PMN-28PT ceramics at around 80 degrees C under an electric field of 60 kV/cm. Development of texture was demonstrated to have led to an anisotropy in the EC response.
Structural and dielectric properties of Europium based copper oxide layered perovskite material
(Taylor & Francis Ltd, 2017) Güven Özdemir, Zeynep; Kılıç, Mehmet; Karabul, Yaşar; Aslan Çataltepe, Özden; İçelli, Orhan; Onbaşlı, Ülker
In this study, EuBa2Cu3O7+x (coded as Eu-123) material was synthesized by solid state reaction method and its chemical and physical properties were determined by FTIR, XRF, TGA and DTA techniques. The dielectric and impedance properties of Eu-123 were determined by HP-4194A Impedance Analyzer at room temperature. Eu-123 displays negative dielectric constant (NDC) property, which has a crucial importance for producing metamaterials. Moreover, the relaxation process of the material was also determined as pure conduction. In addition, it was revealed that application of magnetic field does not affect the NDC property of the sample but slightly changes the values of epsilon'.
Some properties of generalized complex space forms
(American Institute of Physics Inc., 2019) Mutlu, Pegah
In the present paper, we determine the holomorphic curvature tensor of generalized complex space forms and study some properties of this tensor in generalized complex space forms. Moreover, we present results on generalized complex space forms satisfying curvature identities named Walker type identities.
Application of AI approaches to estimate discharge coefficient of novel kind of sharp-crested v-notch weirs
(American Society of Civil Engineers (ASCE), 2022) Gharehbaghi, Amin; Ghasemlounia, Redvan
In this study, the hydraulic features of the SCVW (a novel type of sharp-crested V-notch weirs) were scrutinized in the popular vertex angles theta, i.e., 30 degrees, 45 degrees, 60 degrees, 90 degrees, 120 degrees, 128 degrees, and 150 degrees, under aerated, steady and free overflow conditions in an open channel for large physical models. To assess the changes of the discharge coefficient of the SCVW (i.e., C-dSCVW) versus weir height and theta, widespread laboratory works were performed by measuring the water head over the crest of the weir and the discharge. Special formulas for the C-dSCVW in the theta=60 degrees were checked, and an appropriate empirical equation was recommended. The calculated C-dSCVW by the proposed equation was within 0%-10% of the measured values. Three types of nonparametric artificial intelligence (AI) methods, namely, support vector regression (SVR), gene expression programming (GEP), and a robust hybrid model entitled hybrid (SVR-ACO) were developed to estimate the C-dSCVW. For the sake of modeling, 196 experimental datasets were applied in the mentioned methods to evaluate the C-dSCVW by taking into consideration the dimensionless variables which impact the determining procedure of the C-dSCVW. In this modeling, by varying the architecture and core factors of the aforementioned methods, several scenarios were defined. The generated mathematical equation of C-dSCVW by the best scenario of the GEP was compared with the corresponding measured values in which the results were in 0%-10%. According to the attained statistical indices, scatter plots, and the values of the total grade (TG) technique, the hybrid SVR(RBF)-ACO model was determined as the superior and optimal method to estimate the C-dSCVW with high performance and accuracy.

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