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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
Showing 201 - 265 of 265 Journals sorted by number of followers
Revista Científica de la Universidad Nacional del Este     Open Access   (Followers: 12)
History of Science and Technology     Open Access   (Followers: 5)
Orbis Cógnita : Revista Científica     Open Access   (Followers: 4)
Research Policy : X     Open Access   (Followers: 4)
Data     Open Access   (Followers: 4)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 4)
Frontiers in Climate     Open Access   (Followers: 4)
MUST : Journal of Mathematics Education, Science and Technology     Open Access   (Followers: 4)
Journal of the Indian Institute of Science     Hybrid Journal   (Followers: 4)
Discover Sustainability     Open Access   (Followers: 3)
Journal of Composites Science     Open Access   (Followers: 3)
Research     Open Access   (Followers: 3)
Journal of Big History     Open Access   (Followers: 3)
Patterns     Open Access   (Followers: 3)
People and Nature     Open Access   (Followers: 3)
Science & Technology Studies     Open Access   (Followers: 3)
Citizen Science : Theory and Practice     Open Access   (Followers: 2)
Indonesian Journal of Science and Mathematics Education     Open Access   (Followers: 2)
International Journal of Culture and Modernity     Open Access   (Followers: 2)
Experimental Results     Open Access   (Followers: 1)
Global Journal of Science Frontier Research     Open Access   (Followers: 1)
International Journal of Innovative Research and Scientific Studies     Open Access   (Followers: 1)
Acta Scientifica Malaysia     Open Access   (Followers: 1)
Applied Mathematics and Nonlinear Sciences     Open Access   (Followers: 1)
Bilge International Journal of Science and Technology Research     Open Access   (Followers: 1)
Journal of Science and Engineering     Open Access   (Followers: 1)
Uluslararası Bilimsel Araştırmalar Dergisi (IBAD)     Open Access   (Followers: 1)
Journal of Science and Technology     Open Access   (Followers: 1)
AAS Open Research     Open Access   (Followers: 1)
ARPHA Conference Abstracts     Open Access   (Followers: 1)
Revista Vivências em Ensino de Ciências     Open Access   (Followers: 1)
iScience     Open Access   (Followers: 1)
Scientonomy : Journal for the Science of Science     Open Access   (Followers: 1)
Futures & Foresight Science     Hybrid Journal   (Followers: 1)
International Journal of Research in Science     Open Access   (Followers: 1)
Jaunujų mokslininkų darbai     Open Access   (Followers: 1)
Impact     Open Access   (Followers: 1)
Revista Saber Digital     Open Access   (Followers: 1)
Fundamental Research     Open Access  
BJHS Themes     Open Access  
South American Sciences     Open Access  
Middle European Scientific Bulletin     Open Access  
Journal of Alasmarya University     Open Access  
Research Integrity and Peer Review     Open Access  
Natural Sciences Education     Hybrid Journal  
Proceedings of the Indian National Science Academy     Full-text available via subscription  
Indian Journal of History of Science     Hybrid Journal  
RAC: Revista Angolana de Ciências     Open Access  
The Innovation     Open Access  
Journal of Responsible Technology     Open Access  
Natural Sciences     Open Access  
Revista de la Sociedad Científica del Paraguay     Open Access  
Rekayasa     Open Access  
Rihan Journal for Scientific Publishing     Open Access  
Türk Bilim ve Mühendislik Dergisi     Open Access  
ArtefaCToS : Revista de estudios sobre la ciencia y la tecnología     Open Access  
Ethiopian Journal of Sciences and Sustainable Development     Open Access  
Vilnius University Proceedings     Open Access  
Sciential     Open Access  
ARPHA Proceedings     Open Access  
Gaudium Sciendi     Open Access  
Crea Ciencia Revista Científica     Open Access  
Rafidain Journal of Science     Open Access  
Journal of Al-Qadisiyah for Pure Science     Open Access  
Revista Tecnológica     Open Access  
Himalayan Journal of Science and Technology     Open Access  
International Journal of Academic Research in Business, Arts & Science     Open Access  
Universidad, Ciencia y Tecnología     Open Access  
Fides et Ratio : Revista de Difusión Cultural y Científica     Open Access  
Acta Nova     Open Access  
Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales     Open Access  
Entre Ciencia e Ingeniería     Open Access  
Revista Politécnica     Open Access  
Reportes Científicos de la FaCEN     Open Access  
Jurnal Ilmiah Ilmu Terapan Universitas Jambi : JIITUJ     Open Access  
Revista Eletrônica Ludus Scientiae     Open Access  
Emergent Scientist     Open Access  
Journal of Scientific Research and Reports     Open Access  
Asian Journal of Advanced Research and Reports     Open Access  
Archives of Current Research International     Open Access  
Advances in Research     Open Access  
International Journal of Applied Science     Open Access  
Iranian Journal of Science and Technology, Transactions A : Science     Hybrid Journal  
J : Multidisciplinary Scientific Journal     Open Access  
Revista Binacional Brasil - Argentina: Diálogo entre as ciências     Open Access  
Revista Ciencia y Tecnología     Open Access  
Journal of Institute of Science and Technology     Open Access  
Journal of Science (JSc)     Open Access  
WikiJournal of Science     Open Access  
Acta Materialia Transilvanica     Open Access  
Integrated Research Advances     Open Access  
PENDIPA : Journal of Science Education     Open Access  
Open Conference Proceedings Journal     Open Access  
Naturen     Full-text available via subscription  
Ekaia : EHUko Zientzia eta Teknologia aldizkaria     Open Access  
Sci     Open Access  
Maskana     Open Access  
Hoosier Science Teacher     Open Access  
Reports in Advances of Physical Sciences     Open Access  
Facets     Open Access  
Adıyaman University Journal of Science     Open Access  
Revista Brasileira de Iniciação Científica     Open Access  
Communications Faculty of Sciences University of Ankara Series A2-A3 Physical Sciences and Engineering     Open Access  
Scientific African     Open Access  
Scientific Journal of Mehmet Akif Ersoy University     Open Access  
Black Sea Journal of Engineering and Science     Open Access  
Fırat University Turkish Journal of Science & Technology     Open Access  
Gazi University Journal of Science     Open Access  
Middle East Journal of Science     Open Access  
International Journal of Computational and Experimental Science and Engineering (IJCESEN)     Open Access  
International Journal of Engineering, Technology and Natural Sciences     Open Access  
Bulletin of the National Research Centre     Open Access  
Uni-pluriversidad     Open Access  
ConCiencia     Open Access  
Ciencia y Tecnología     Open Access  
Revista Bases de la Ciencia     Open Access  
Elkawnie : Journal of Islamic Science and Technology     Open Access  
Ciência ET Praxis     Open Access  
Arab Journal of Basic and Applied Sciences     Open Access  
International Annals of Science     Open Access  
Science Heritage Journal     Open Access  
Avrasya Terim Dergisi     Open Access  
International Scientific and Vocational Studies Journal     Open Access  
TÜBAV Bilim Dergisi     Open Access  
LOGIKA Jurnal Ilmiah Lemlit Unswagati Cirebon     Open Access  
Dalat University Journal of Science     Open Access  
Investiga : TEC     Open Access  
Investigación Joven     Open Access  
Respuestas     Open Access  
Science Diliman     Open Access  
Instruments     Open Access  
Revista Científica y Tecnológica UPSE     Open Access  
HardwareX     Open Access  
Sultan Qaboos University Journal for Science     Open Access  
Borneo Journal of Resource Science and Technology     Open Access  
Sainstek : Jurnal Sains dan Teknologi     Open Access  
Revista de Información Científica     Open Access  
Indonesian Journal of Fundamental Sciences     Open Access  
Sainteknol : Jurnal Sains dan Teknologi     Open Access  
Jurnal Natural     Open Access  
Frontiers for Young Minds     Open Access  
Revista Ciência, Tecnologia & Ambiente     Open Access  
Journal of Indian Council of Philosophical Research     Hybrid Journal  
Journal of Negative and No Positive Results     Open Access  
Revista Conhecimento Online     Open Access  
Nova     Open Access  
CienciaUAT     Open Access  
Enseñanza de las Ciencias : Revista de Investigación y Experiencias Didácticas     Open Access  
Makara Journal of Science     Open Access  
Jurnal Sains Dasar     Open Access  
Indonesian Journal of Science and Technology     Open Access  
Ethiopian Journal of Science and Technology     Open Access  
Jurnal Matematika, Sains, Dan Teknologi     Open Access  
Heidelberger Jahrbücher Online     Open Access  
ARO. The Scientific Journal of Koya University     Open Access  
International Journal of Recent Contributions from Engineering, Science & IT     Open Access  
Estação Científica (UNIFAP)     Open Access  
The Winnower     Open Access  

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Sakarya Üniversitesi Fen Bilimleri Enstitüsü Dergisi
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1301-4048 - ISSN (Online) 2147-835X
Published by Sakarya Üniversitesi Homepage  [3 journals]
  • Metal-containing Coordination Complexes (MCCs): Assessment of Biological
           Activity with Helicobacter pylori Caused Gastric Ulcer

    • Authors: Dursun KISA; Yusuf CEYLAN, Merve YILDIRIM, Sümeyra DURGUN, Nesrin KORKMAZ
      Abstract: The ulcer is a vital disease that unfavorably affects human health globally. Helicobacter pylori, a reason forhave an antibacterial effect against ulcers and some stomach disorders, live on using the urease enzyme and induces the condition to occur. Metal coordination complexes (MCC) are used in numerous industrial areas and the health field. Cyanide bridged metal complexes are also applied in several places. In the current study, antibacterial characteristic of (C1), [Ni(bishydeten)2Ag(CN)2][Ag(CN)2].H2O), and (C2), ([Ni(hydeten)2Ag(CN)2][Ag(CN)2], MCC were analyzed by disk diffusion and broth dilution broth and urease enzyme inhibition assays were performed. As a result of both antibacterial tests, C1 and C2 were observed to provide favorable effects. The synthesized compounds have effective inhibitory potential with IC50 value between 26.65±1.21 and 12.37±0.87 µM for urease.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Conformational Analysis of Tyrosyl-Lysyl-Threonine Tripeptide Using MM, MD
           and QM Methods and Its Hyperpolarizability Study

    • Authors: Bilge BIÇAK; Serda Kecel GUNDUZ
      Abstract: Peptides are important structures that offer important opportunities for therapeutic interventions in various diseases. Tyrosyl-Lysyl-Threonine is an important peptide structure that contains the antiviral, antioxidant and anticancer properties of the amino acids in its structure. Examination of the conformational structure, which has great importance on both the ability of the molecule to fulfill its biological functions and electronic properties, is important for molecular studies. In this study, determination of the stable conformations and optimization of the most stable structure of Tyrosyl-Lysyl-Threonine molecule was carried out using molecular mechanical and quantum mechanical methods. With molecular dynamics simulation studies, the changes in conformational structure, RMSD and Rg values in different environments were monitored for 10 ns. Additionally, the hyperpolarizability study of Tyrosyl-Lysyl-Threonine were carried out. As a result of this study, it was aimed to determine the optimized geometry of the tripeptide, its conformational changes and nonlinear optical properties.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Potential Use of Lactobacillus gasseri G10 Isolated from Human Vagina
           along with Intrauterine Devices (IUD) to Prevent Pathogen Colonization

    • Authors: Busra AKTAS
      Abstract: Intrauterine devices (IUDs), well effective long-term contraception methods used around the world, are potential reservoir for pathogens and carry risk of reproductive-tract infections such as bacterial vaginosis and vulvovaginal candidiasis. A healthy vagina is dominated by Lactobacillus involved in protecting reproductive system against pathogens. This study aims to investigate the impact of L. gasseri G10 (G10), a vaginal isolate, and its Exopolysaccharide (EPS) on adherence of Staphylococcus aureus and Candida albicans to IUD-tail. Three conditions were simulated to examine if G10 with/without EPS is capable of displacing, excluding, and competing pathogen adhesion to IUD. Inhibitory impact of EPS at various concentrations on pathogen adherence was also evaluated with co-incubation. G10 blocked by co-incubation (97%) and displacement (46%) of S. aureus adherence to IUD tail and displaced C. albicans attached to IUD with about 99%. Compared with S. aureus, the biofilm formation by C. albicans was highly susceptible to EPS. All concentrations of EPS inhibited the adherence of C. albicans (81-97%); however, no significant reductions were observed in S. aureus adherence. Moreover, G10 and EPS together reduced the adherence of both S. aureus (>99%) and C. albicans (94-98%) through all three mechanisms. This study indicates that G10 and its EPS have the ability to inhibit adhesion of S. aureus and C. albicans to IUD and potential use in intravaginal products to prevent/manage IUD associated infections in women. The results suggest development of a new way of applying IUD along with probiotic agents alone or as synbiont.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • A Numerical Study of a Pico Hydro Turbine

    • Authors: Ümit BEYAZGÜL; Ufuk DURMAZ, Orhan YALÇINKAYA, Mehmet Berkant ÖZEL, Ümit PEKPARLAK
      Abstract: Pico hydro turbines are suitable for low head applications in power plants since their efficiency is more stable than other turbine types. In some situations, computational fluid dynamics (CFD) has also been utilized as well as experimental studies for the performance prediction of water turbines at a pico scale. Also, CFD methods are getting much closer to real conditions in terms of steady-state with moving references and transient domains with rotor movements. For this purpose, electricity production related to the flow in a PHT was investigated numerically. This study presents six degrees of freedom (6-DOF) and moving reference frame (MRF) methods to predict the maximum conditions of a pico scale two-dimensional turbine by comparing the torque and angular velocities on the runner based on the turbine output power of 1 W determined by an experimental study. Besides, the effect of the torque, angular velocity, tip speed ratio, and turbine body profile was investigated comprehensively. In this regard, MRF and 6-DOF methods were performed to validate and compare the numerical model with the experimental results. Also, the results obtained from 6-DOF and MRF methods were compared to experimental study. It is concluded that PHT is generating 0.3 W power under 6.47 rad/s angular velocity with 6-DOF method, however; this value corresponds to 31.4 rad/s angular velocity against 1 W with the MRF method. Also, the maximum velocity of the turbine was 6.1 m/s according to the simulation result. It is accepted that the turbine maximum velocity inlet was 0.53 m/s based on the experimental study. As a conclusion, numerical results for the pico hydro turbine were reasonable taking the experimental study into account. It is also concluded that there is a tip speed ratio of 2.36 with the MRF method and 0.48 with the 6-DOF method between water tangential velocity and runner velocity for the turbine model.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Investigation of Lateral and Vertical Direction Dynamic Responses of a
           Full Car Model Exposed to Sine Road Input

    • Authors: Mustafa EROĞLU
      Abstract: In this study, the full car model, which is exposed to a sinusoidal road input, has been examined to ensure the driving safety of the vehicles and the comfort of the passengers. In this context, the full car, including lateral and vertical movements, is modeled with fourteen degrees of freedom. The second-order equations of motion of the modeled vehicle were obtained using the Lagrangian method and reduced to first-order equations of motion using the state-space form. Then, these equations of motion were solved precisely in the time domain using the Euler method in the Matlab environment. To examine the lateral movements and the rotations of the vehicle in the pitch and roll axis, a sine wave with a wavelength of 5 m and an amplitude of 0.1 m was applied to the wheels of the vehicle. In the analysis, the right front wheel is exposed to a sinusoidal road input at t=0 s, while the left front wheel is exposed to a sinusoidal road input after the vehicle moves 2.5 m. Thus, both the pitch and roll motion of the vehicle will be examined in detail. In the study, four different vehicle masses 500 kg, 1000 kg, 2000 kg, and 3000 kg were taken into consideration and the effect of different vehicle masses on passenger and vehicle dynamic behaviors was investigated. In addition, the situation of passing vehicles at variable speeds from the given disruptive road input has also been examined. The maximum dynamic responses of the passenger and the vehicle were examined when the vehicle speed changed from 3 m/s to 50 m/s by 0.1 m/s. In the study, it has been observed that the vehicle mass and certain vehicle speed have effects on the vertical and lateral displacements and accelerations of the passenger and the vehicle
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • An Investigation of the Correlation of Antibacterial Activity of Thyme
           (Thymus vulgaris L.) with its Nutrient Elements

    • Authors: Muazzez GÜRGAN ESER; Sevinc ADİLOGLU
      Abstract: The present study aimed to examine the correlation of plant nutrient elements with the antibacterial activity of methanol extract of Thymus vulgaris L. grown on soil from the experimental field without application of fertilizers or pesticides on two Gram-positive and two Gram-negative bacteria. The extract of thyme was obtained by maceration of aerial parts of the plant using methanol as the solvent. The contents of macro (P, K, Ca, and Mg) and micro (Fe, Cu, Zn, Mn, and B) nutrients were detected by ICP-OES. The results showed that the macro nutrients were compatible with herbaceous perennial plants, while Fe, Mn and B micro nutrients were high. The methanol extract was significantly effective on inhibiting P. aeruginosa, S. aureus and E. faecalis, while did not inhibit E. coli. The correlation of K and Mg was significantly positive with the growth inhibition of P. aeruginosa suggesting that higher K and Mg contents of the plant would result in higher antibacterial activity against P. aeruginosa, most probably up to a point. On the other hand, significant positive correlation of B was found with the inhibition of both Gram-positive bacteria. In addition, the positive correlation of Ca with the growth inhibition of S. aureus was highly significant. The importance of nutrient contents in medicinal aromatic plants such as thyme was shown with this study. The results therefore imply the conscious and sustainable agriculture of medicinal aromatic plants is crucial for the antibacterial activity of thyme.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Synchronization of Gursey System

    • Authors: Eren TOSYALI; Fatma AYDOĞMUŞ
      Abstract: Gursey Model, the only possible four-dimensional pure spinor model, proposed as a possible basis for a unitary description of elementary particles. The model exhibits chaotic behaviors depending on the system parameter values. In this study, we investigate the synchronization of chaotic dynamic in the Gursey wave equation that has particle-like solutions derived classical field equations. Numerical results for synchronization of the Gursey system are performed to indicate the accuracy of the used method.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Effect of Iron on Some Parameters Recombinant Pseudomonas aeruginosa
           Carrying Vitreoscilla Hemoglobin Gene

    • Authors: Hüseyin KAHRAMAN
      Abstract: In this study, the effects of iron presence on some bacterial parameters of Pseudomonas aeruginosa and its recombinant bacteria carrying Vitreoscilla hemoglobin on its chromosome were investigated for the first time. These parameters are; optical density, pH, glucose, trehalose production and biomass. Parameters; It was studied at 37 °C and 250 rpm ventilated conditions depending on time. Bacteria have developed mechanisms by which they can resist heavy metal stress with many other mechanisms, including making metals less toxic and excreting them out of the cell. The Efflux system is the most widely used mechanism. The bacterium that makes the best use of these mechanisms is P. aeruginosa, which has an environmental and versatile feature. In the presence of LB alone, an increase was observed in the first 48 hours and a decrease of 43% in the other time periods, especially in the 96th hour compared to the control. The highest increase was detected in the 48th time periods, up to 259% in the 3,32. When iron was added to the medium, significant increases were observed in all time periods compared to the controls and these increases reached 575% at 72 hours. In the same time periods, the maximum value of OD600 4.55 was reached.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Mechanical and Structural Evaluation of LiSrH3 Perovskite Hydride for
           Solid State Hydrogen Storage Purposes

    • Authors: Selgin AL; Çağatay YAMÇIÇIER
      Abstract: Increasing catastrophic climate events, energy needs, human population lead to look for clean, cheap and environmentally friendly energy production methods and sources. International agreements have been made to lower carbon emissions and support carbon free way of energy productions. Hydrogen technology is suggested one excellent way of accomplishing these aims. Hydrogen is an excellent energy carrier with almost zero carbon emission and high efficiency. There are four steps to make hydrogen energy ready for usage: production, transportation, storage and converting it to electricity. Each steps have its own obstacles to be overcome. Among the storage methods, solid state storage of hydrogen is very promising since it allows us to store hydrogen in high content safely. Thus, there are intense ongoing research on this area. Therefore, this study adopts a well proved, time and cost saving method density functional theory to search and evaluate mechanical and electronic properties of LiSrH3 perovskite hydride with space group Pm3 ̅m (221) for hydrogen storage purposes. Two critical parameters gravimetric hydrogen density and hydrogen desorption temperature along with elastic constants, Poisson’s ratio, Shear, bulk, Young modulus are collected and discussed. The mechanical evaluation is demonstrated that LiSrH3 is a mechanically stable material, however, elastic constant evaluation is showed that it is a brittle material which can be an obstacle when handling the material. The electronic band structure is also obtained which demonstrated an indirect band gap of 3.65 eV.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Preparation and Characterization of Intrinsically Fluorescent
           Polyphosphazene Microspheres

    • Authors: Simge METİNOĞLU ÖRÜM
      Abstract: The novel polyphosphazene and cyclomatrix type microspheres were synthesized via a one-pot self-assembly polycondensation method. Octachlorocyclotetraphosphazene and two fluorescent compounds; fluorescein and curcumin were used as a crosslinker and monomers, respectively. The prepared microspheres were characterized by SEM, EDX, FTIR, XRD, UV-vis techniques. Also, the fluorescence properties of the microspheres were investigated. The microspheres exhibited fluorescence emissions both in ethanol and as solid-state when excited at 470 nm. The optimum pH was determined as 9.0 for fluorescence measurements. Owing to fluorescent properties of the microspheres, the delivery of curcumin from the prepared microspheres, and cell imaging can be investigated in the future. It is thought that the obtained intrinsically fluorescent polyphosphazene microspheres have the potential for use as sensors and labels, also.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Synthesis and Characterization of Thiazole Compounds in the Presence of
           Various Reagents, Catalysts and Solvents

    • Authors: Nurcan BERBER
      Abstract: The reaction medium plays a key role in organic synthesis and pharmaceutical research. There are many opinions on choosing the best condition, including cost and environmental implications, but the main requirement is that they have the necessary interaction with solvents to cause dissolution, precipitation, stabilization, or instability. For this purpose, in this article synthesis of the thiazole ring was made under various reaction conditions. So new compounds 2-(isoquinolin-5-ylimino)-3-phenylthiazolidin-4-one (1), (4-amino-3-phenylthiazol-2(3H)-ylidene) isoquinolin-5-amine (2), (4-amino-3-phenylthiazol-2(3H)-ylidene) isoquinolin-5-amine (3) were synthesized from the reaction between thiourea derivative and monochloroacetic acid, diethyloxalate and chloro acetonitrile. For this synthesizes were created in various reaction conditions, using different bases (sodium acetate/sodyum etoksit/ triethylamine or pyridine) and solvents (1,4-dioxane, toluene, acetic acid, ethanol, tetrahydrofuran, dimethyl formamide). At the end of these reactions, the best efficiency was obtained with the one-pot reaction using THF/DMF, Et3N. The structures of all novel compounds reported herein were established using FT-IR, 1H NMR, and 13C NMR spectra as well as elemental analysis technique.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Transition Gas Flow Between Two Parallel Plates with a Slit-Type Obstacle
           of Various Geometry by Event Driven Molecular Dynamics Simulation

    • Authors: Mustafa KOÇ; İlyas KANDEMİR, Volkan Ramazan AKKAYA
      Abstract: In this study, pressure-driven flow through a slit-type obstacle with various length (L) and height (H) placed in between two parallel plates was investigated by Event Driven Molecular Dynamics (EDMD) simulation. Mach number, temperature and pressure distributions were obtained along the channel in the transition regime. The change in these macroscopic properties and flow rate were examined for different cases created by changing Knudsen number (Kn) of the gas, the geometry of the slit and the outlet/inlet pressure ratio of the flow. Collision of gas molecules with plates and the obstacle were modeled with diffuse reflection boundary condition. The flow rate showed a sudden change in the transition regime and significant differences in the molecular regime depending on the pressure ratio. Except for the Kn, H and L dimensions were found to be effective in Mach disc formation. Pressure drops at the exit of the slit were shaped differently in normalized pressure profiles depending on Kn, H and L dimensions. In addition, the structure of the vortices formed at the entrance and exit of the slit varies depending on Kn. Some of the results obtained were confirmed to be consistent with the similar studies in the literature.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Temporal Analysis Based Driver Drowsiness Detection System Using Deep
           Learning Approaches

    • Authors: Furkan KUMRAL; Ayhan KÜÇÜKMANİSA
      Abstract: With the development of technology, artificial intelligence comes into our lives more and also comes up as a solution to many problems. Recently, deep learning approaches have been bringing fast and highly accurate solutions to problems. In this work, within the scope of Advanced Driver Assistance Systems (ADAS), deep learning based driver drowsiness detection system is proposed. First, face regions of drivers are detected using SSD MobileNet object detection method. The aim is to detect the eye, mouth and head positions of the drivers from this face region and to make a situation estimation with the combinations of these detected objects which are “normal”, “drowsy” and “danger”. The proposed approach examines the driver's behaviour over a certain period of time for making a decision, rather than a one-time eye closure or yawning decision. The detected eye, mouth and head positions are monitored and recorded over a period of time. Finally, these merged patterns are classified with Convolutional Neural Networks (CNN). Experimental results show that the performance of proposed novel CNN approach outperforms existing approaches in literature.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Notes On A Rare Species From Turkey: Opopanax chironius

    • Authors: Mehmet SAĞIROĞLU
      Abstract: The first Turkish record of Opopanax chironius (L.) W.D.J. Koch was firstly collected from Tekirdağ province in 1969. The morphological description of the species in “Flora of Turkey and the East Aegean Islands” was written based on these specimens. The species has not been collected for along time untilday. This species was re-collected by us during a flora study in 2014 at Malkara district, Karaiğdemir Dam road in Tekirdağ. The name of this species was mispelled. This situation has been corrected here. Its correct use is Opopanax chironius. Also, in this study, expanded description of the species, pictures, disdictive morphological characters from other species, ecology, fruit photographs and ethnobotanical usage were given.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • An Investigation of the Influence of Various Shaped Cutouts on the Free
           Vibration Behavior of Sandwich Structures

    • Authors: Ufuk DEMİRCİOĞLU; Mutlu Tarık ÇAKIR
      Abstract: The current study deals with free vibration analysis of a sandwich beam in presence of different cutouts. PVC foam and glass fiber were used for the core and surface layers of the sandwich structures, respectively. First 6 frequencies of the sandwich structures were determined for different cutout shapes to see the effect of cutout shapes on the free vibration behavior of sandwich structures. For this, sandwich beams with different cutout shapes but with the same area were modeled. To see the effect of cutouts-shape only the shape of cutouts was changed and all other parameters were kept unchanged. Analyses were performed by using ANSYS apdl commercially available software. The analysis gives information about the influence of the cutout shape on the first six natural frequencies of the sandwich structures. From the results, it was observed that the changes of cutout shapes caused a significant decrease or increase in natural frequencies of sandwich structures beam depending on the cutout shape.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Investigation of Matrices Q^(n._L ), M^(n._L ) and R^(n._L ) and Some
           Related Identities

    • Authors: İbrahim GÖKCAN; Ali Hikmet DEĞER
      Abstract: In this study, it is aimed to use the Lorenz matrix multiplication to find the n^th powers of some special matrices and to reach the quadratic equations and characteristic roots of the matrices obtained in this way. In addition, it is aimed to contribute literature to the studies in the field by reaching some identities.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Global Existence and Uniqueness of The Inviscid Velocity-Vorticity Model
           of The g-Navier-Stokes Equations

    • Authors: Özge KAZAR; Meryem KAYA
      Abstract: In this paper, we prove the global existence and uniqueness of the weak solutions to the inviscid velocity-vorticity model of the g-Navier-Stokes equations. The system is performed by entegrating the velocity-pressure system which is involved by using the rotational formulation of the nonlinearity and the vorticity equation for the g-Navier-Stokes equations without viscosity term. In this study we particularly interest the inviscid velocity-vorticity system of the g-Navier-Stokes equations over the two dimensional periodic box Ω=(0,1)^2⊂R^2.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Modeling and Analysis of Battery Thermal Control in a Geostationary
           Satellite

    • Authors: Murat BULUT; Nedim SÖZBİR
      Abstract: Battery technology has been used for geostationary satellites since the first satellite sputnik-1 was launched in 1957. The majority of larger geostationary satellite’s lives range from 7 to 15 years. During the lifetime of satellites, the batteries used must complete 1000 to 33000 cycles without any problems or likelihood of maintenance. There are three battery technologies, Li-ion, Ni-H2 and Ni-Cd, that are well proven for Geostationary satellite applications. Energy density, lifetime, weight, ampere-hour capacity, depth of discharge, ruggedness and recharge-ability, battery management, thermal management, and self-discharge are main parameters that should be considered when comparing electrical and thermal performance of these three battery technologies. The purpose of this study is to compare the thermal control system for these three batteries for three-axis stabilized geostationary satellites. In particular, the thermal dissipation was compared, which is the temperature range required for battery operation. Thermal analysis was performed for Li-ion batteries using ThermXL software, and showed a temperature results variation ranging between 10.9 oC and 32.7 oC. The temperature during the battery module was not greater that its qualification temperature results.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Energy Levels and Radiative Lifetimes for Four Times Ionized Xenon (Xe V)

    • Authors: Selda ESER
      Abstract: By employing the general-purpose relativistic atomic structure package (GRASP) based on the fully relativistic multiconfiguration Dirac-Fock (MCDF) method, energies and radiative lifetimes of levels have been reported for four times ionized xenon (Xe V). In calculations, the Breit interactions for relativistic effects, quantum electrodynamical (QED) contributions have been included as a perturbation, as well as electron correlation effects (VV, CV, and CC). We have compared the results obtained from this work with other available experimental and theoretical values in available literature for Xe V. We have obtained good agreement with previous works.
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
  • Neutronic and Thermalhydraulic Evaluation of Annular Fuel in PWR with
           Three Different Nanofluids

    • Authors: Ali TİFTİKÇİ
      Abstract: In pressurized nuclear reactors, one of the fuel design principles is the fuel centerline temperature limit. Since the thermal conductivity of UO2 is not high, the temperature increases rapidly from the fuel surface to the fuel center. To overcome this limitation, the use of annular type fuels instead of solid fuels is one of the improvement efforts. In this study, the effects of using annular fuel in a typical PWR are investigated. At the same time, the effects of adding nanoparticles (〖Al〗_2 O_3,Cu and TiO_2) to the coolant water in the case of solid and annular fuels are also investigated. For both cases, neutronic and thermalhydraulic calculations are made and compared. In neutronic point of view, it has been shown that the use of annular fuel does not cause a significant change in the k_eff value but the presence nanoparticles reduces the k_eff. This reduction is maximum for Cu+water and minimum for 〖Al〗_2 O_3+water nanofluids. In thermalhydraulic point of view, it has been shown that the annular fuel positively affects the fuel temperature limits and the addition of nanoparticles could provide an additional contribution to this, provided that it is in very small amounts (φ
      PubDate: Wed, 31 Aug 2022 00:00:00 +030
       
 
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