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Articles 7051 - 7080 of 10319
Full-Text Articles in Physical Sciences and Mathematics
Synthesis And Anti-Helicobacter Pylori Activity Of (4-Nitro-1-Imidazolylmethyl)-1,2,4-Triazoles, 1,3,4-Thiadiazoles, And 1,3,4-Oxadiazoles, Asal Fallah-Tafti, Tahmineh Akbarzadeh, Parastoo Saniee, Farideh Siavoshi, Abbas Shafiee, Alireza Foroumadi
Synthesis And Anti-Helicobacter Pylori Activity Of (4-Nitro-1-Imidazolylmethyl)-1,2,4-Triazoles, 1,3,4-Thiadiazoles, And 1,3,4-Oxadiazoles, Asal Fallah-Tafti, Tahmineh Akbarzadeh, Parastoo Saniee, Farideh Siavoshi, Abbas Shafiee, Alireza Foroumadi
Turkish Journal of Chemistry
A series of [(4-nitro-1H-imidazol-1-yl)methyl]-1,2,4- triazoles and 1,3,4-thiadiazoles were prepared and evaluated for their activity against sensitive and resistant H. pylori strains. Study of the structure-activity relationship of these series of compounds indicated that the type of nitroimidazole moiety and the pendent group on the heteroaryl analog dramatically impact the anti-H. pylori activity. In triazole series, compound 5d, containing a 4-methyl phenyl group on the triazole ring, was the most potent compound tested against both metronidazole-sensitive and -resistant strains at a concentration of 8 \mu g.
Synthesis, Characterization, And Biological Activity Studies Of (E)-N'-((Thiophen-2-Yl)Methylene)Benzofuran-2-Carbohydrazide And Its Metal(Ii) Complexes, Madappa B. Halli, Vijayalaxmi B. Patil, Sumathi R. Bevinamarada
Synthesis, Characterization, And Biological Activity Studies Of (E)-N'-((Thiophen-2-Yl)Methylene)Benzofuran-2-Carbohydrazide And Its Metal(Ii) Complexes, Madappa B. Halli, Vijayalaxmi B. Patil, Sumathi R. Bevinamarada
Turkish Journal of Chemistry
Metal complexes of the type MLX_2, where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II), and X = Cl and L = TMBC, Schiff base derived from the condensation of benzofuran-2-carbohydrazide with thiophene-2-aldehyde were synthesized. The structure of the complexes was proposed in light of analytical, IR, UV-Vis, ^1H-NMR, FAB-MS, ESR spectral data, and magnetic studies. The complexes were soluble in DMF and DMSO. The measured molar conductance values indicated that the complexes were nonelectrolytic in nature. On the basis of these studies, 6 coordinated octahedral polymeric structures were assigned to the Co(II), Ni(II), and Cu(II) complexes, and 4 …
Voltammetric Behavior Of Indole-3-Acetic Acid And Kinetin At Pencil-Lead Graphite Electrode And Their Simultaneous Determination In The Presence Of Anionic Surfactant, Yavuz Yardim, Zühre Şentürk
Voltammetric Behavior Of Indole-3-Acetic Acid And Kinetin At Pencil-Lead Graphite Electrode And Their Simultaneous Determination In The Presence Of Anionic Surfactant, Yavuz Yardim, Zühre Şentürk
Turkish Journal of Chemistry
A method was developed for the simultaneous determination of indole-3-acetic acid (IAA) and kinetin, based on the oxidation of both phytohormones at a pencil-lead graphite electrode. The electrochemical behaviors were examined by cyclic, linear sweep, and square-wave voltammetry in the pH range of 2-12. In Britton-Robinson buffer solution (pH 6), the oxidation peaks of IAA and kinetin are well separated by square-wave voltammetry. By adding an anionic surfactant (sodium dodecylsulfate) in a concentration of 50 \mu M, the sensitivity of kinetin was increased significantly without reducing the resolution. The detection limits were 0.14 and 0.11 \mu M (24.53 and 23.67 …
Stable Ester And Amide Conjugates Of Some Nsaids As Analgesic And Antiinflammatory Compounds With Improved Biological Activity, Meci̇t Orhan Uludağ, Burcu Çalişkan Ergün, Duygu Asli Alkan, Ni̇lüfer Ercan, Güler Yağmur Özkan, Erden Banoğlu
Stable Ester And Amide Conjugates Of Some Nsaids As Analgesic And Antiinflammatory Compounds With Improved Biological Activity, Meci̇t Orhan Uludağ, Burcu Çalişkan Ergün, Duygu Asli Alkan, Ni̇lüfer Ercan, Güler Yağmur Özkan, Erden Banoğlu
Turkish Journal of Chemistry
A set of ester and amide derivatives of some acidic NSAIDs, including ibuprofen, ketoprofen, and mefenamic acid (1-3), were synthesized and evaluated for their in vivo analgesic and antiinflammatory activity using the p-benzoquinone-induced writhing test and the carrageenan-induced paw edema model, respectively. Among the synthesized compounds, ester derivatives of ketoprofen showed especially potent analgesic and antiinflammatory activity as compared to the parent drug. In vitro chemical stability studies revealed that ester and amide derivatives were chemically stable in simulated gastric (pH 1.2) and intestinal fluids (pH 6.8). In 80\% human plasma, the ester derivatives were found to be relatively stable …
Simultaneous Determination Of Dopamine, Uric Acid, And Folic Acid By A Modified Tio_2 Nanoparticles Carbon Paste Electrode, Mohammad Mazloum Ardakani, Mohammad Ali Sheikhmohseni, Hadi Beitollahi, Ali Benvidi, Hossein Naeimi
Simultaneous Determination Of Dopamine, Uric Acid, And Folic Acid By A Modified Tio_2 Nanoparticles Carbon Paste Electrode, Mohammad Mazloum Ardakani, Mohammad Ali Sheikhmohseni, Hadi Beitollahi, Ali Benvidi, Hossein Naeimi
Turkish Journal of Chemistry
The electrochemical behavior of dopamine (DA) was studied at the surface of a 2,2-[1,2 buthanediylbis(nit- riloethylidyne)]-bis-hydroquinone/TiO_2 nanoparticles modified carbon paste electrode (BQTMCPE) in aqueous media using voltammetric and chronoamperometric techniques. It was found that under optimum conditions (pH 8.0), the oxidation of DA at the surface of such an electrode occurred at about 220 mV lower than that of an unmodified carbon paste electrode (CPE). Using differential pulse voltammetry (DPV), a highly selective and simultaneous determination of DA, uric acid (UA), and folic acid (FA) was explored at the modified electrode. DPV peak currents of DA, UA, and FA increased …
Bromination Of 2,3-Dihydrobenzobarrelene And Synthesis Of Its Mono- And Dibromide Derivatives: Unexpected Wagner-Meerwein Rearrangement On Silica Gel, Selçuk Eşsi̇z, Mehmet Emi̇n Şengül, Ertan Şahi̇n, Ari̇f Daştan
Bromination Of 2,3-Dihydrobenzobarrelene And Synthesis Of Its Mono- And Dibromide Derivatives: Unexpected Wagner-Meerwein Rearrangement On Silica Gel, Selçuk Eşsi̇z, Mehmet Emi̇n Şengül, Ertan Şahi̇n, Ari̇f Daştan
Turkish Journal of Chemistry
The bromination reaction of dihydrobenzobarrelene under different conditions was studied. The bromination reaction of dihydrobenzobarrelene with molecular bromine gave only a Wagner-Meerwein rearrangement product by aryl and alkyl migration. Its high-temperature bromination reaction resulted in the formation of normal addition products besides rearrangement products. The bromination reaction of the alkene with 1,2- dibromotetrachloroethane (DBTCE) gave a non-rearrangement product as the sole product. The synthesis and bromination reaction of 2-bromodihydrobenzobarrelene was also studied. An unexpected Wagner-Meerwein rearrangement was observed on silica gel during the column chromatography of isomeric tribromides. Herein, we report the results of the synthesis, and the X-ray crystal …
Constituents Of Plantago Major Subsp. Intermedia With Antioxidant And Anticholinesterase Capacities, Ufuk Kolak, Mehmet Boğa, Emi̇ne Akalin Uruşak, Ayhan Ulubelen
Constituents Of Plantago Major Subsp. Intermedia With Antioxidant And Anticholinesterase Capacities, Ufuk Kolak, Mehmet Boğa, Emi̇ne Akalin Uruşak, Ayhan Ulubelen
Turkish Journal of Chemistry
The methanol extract of Plantago major subsp. intermedia (Gilib.) Lange afforded 4 known compounds, namely isomartynoside (1), 10-hydroxymajoroside (2), \beta -sitosterol (3), and ursolic acid (4). Their structures were established by spectroscopic methods. After determination of the total phenolic and flavonoid contents of the methanol extract, the antioxidant potentials of the crude extract and isolated compounds 1-4 were determined by \beta -carotene bleaching, DPPH free radical and ABTS cation radical scavenging, and cupric reducing antioxidant capacity methods. The methanol extract, rich in phenolic contents, indicated the same DPPH free radical scavenging activity (72\% inhibition) as a standard compound, butylated hydroxytoluene, …
Chemistry Of Dibenzobarallene, Moustafa A. Gouda, Moged A. Berghot, Khaled M. Elattar, Abd El Galil M. Khalil
Chemistry Of Dibenzobarallene, Moustafa A. Gouda, Moged A. Berghot, Khaled M. Elattar, Abd El Galil M. Khalil
Turkish Journal of Chemistry
This review represents a systematic and comprehensive survey of the methods of syntheses and chemical reactivity of dibenzobarallene. This compound is an important intermediate for the synthesis of useful and novel heterocycle systems.
Synthesis Of Starch-G-Poly(Acrylic Acid-Co-2-Hydroxy Ethyl Methacrylate) As A Potential Ph-Sensitive Hydrogel-Based Drug Delivery System, Mohammad Sadeghi
Synthesis Of Starch-G-Poly(Acrylic Acid-Co-2-Hydroxy Ethyl Methacrylate) As A Potential Ph-Sensitive Hydrogel-Based Drug Delivery System, Mohammad Sadeghi
Turkish Journal of Chemistry
The present work focused on the design of a drug delivery system (DDS) based on pH-sensitive hydrogel. The hydrogels were prepared via graft copolymerization of mixtures of acrylic acid (AA) and 2-hydroxy ethyl methacrylate (HEMA) onto starch backbones by a free radical polymerization technique. Sodium bicarbonate (NaHCO_3) was added to function as a foaming agent under acidic conditions, rendering the hydrogels to be porous. The porous structure of the hydrogel was essential in this system to yield a large surface area so that 5-fluorouracil (5-FU) release could be facilitated. The hydrogel, thus prepared, possessed a porous structure as determined by …
Electrochemical Impedance Spectroscopy Study On Intercalation And Anomalous Diffusion Of Alcl_4^- Ions Into Graphite In Basic Molten Salt, Ali Ehsani, Mohammad Ghasem Mahjani, Majid Jafarian
Electrochemical Impedance Spectroscopy Study On Intercalation And Anomalous Diffusion Of Alcl_4^- Ions Into Graphite In Basic Molten Salt, Ali Ehsani, Mohammad Ghasem Mahjani, Majid Jafarian
Turkish Journal of Chemistry
Electrochemical impedance spectroscopy (EIS) was employed to investigate diffusion of AlCl_4^- ions in basic (AlCl_3-NaCl-KCl) molten salt. Nyquist plots in different DC offset potentials showed finite and restricted aluminum ion diffusion due to insertion and blocking in the graphite electrode. The general Warburg, open Warburg, and short Warburg impedance in the complex Nyquist plot of this system showed the anomalous diffusion behavior of the ions in the graphite electrode. The diffusion coefficient of the AlCl_4^- ions was calculated from the slope of the Warburg line in a totally blocking film in the graphite electrode and was found to be 2.8 …
Studies On The Mechanism Of Phosphazene Ring-Opening Polymerization (Rop), Selen Bi̇lge
Studies On The Mechanism Of Phosphazene Ring-Opening Polymerization (Rop), Selen Bi̇lge
Turkish Journal of Chemistry
In this study, the ring-opening polymerization (ROP) of cyclic trimer N_3P_3Cl_6 catalyzed by [Et_3Si(N_3 P_3Cl_6)][CHB_{11}H_5Br_6] (3) obtained from the reaction of N_3P_3Cl_6 (1) and Et_3Si(CHB_{11}H_5Br_6) (2) at room temperature was investigated. This provided a unique opportunity to explore the polymerization mechanism. The coordinatively unsaturated cation [N_3P_3Cl_5]^+ is responsible for the ROP of N_3P_3Cl_6, and is formed by the intramolecular elimination of Et_3SiCl from 3. The detection of Et_3SiCl by ^1H-NMR as the catalysis proceeded offers new evidence for the formation of [N_3P_3Cl_5]^+. The progress of the catalysis was followed using ^{31} P-NMR and revealed the build-up of a polymer. Cyclic …
Synthesis And Characterization Of A New Methacrylic Glycomonomer, Liliana Marinela Stefan, Ana Maria Pana, Mihai Cosmin Pascariu, Eugen Sisu, Geza Bandur, Lucian Mircea Rusnac
Synthesis And Characterization Of A New Methacrylic Glycomonomer, Liliana Marinela Stefan, Ana Maria Pana, Mihai Cosmin Pascariu, Eugen Sisu, Geza Bandur, Lucian Mircea Rusnac
Turkish Journal of Chemistry
The carbohydrate containing monomer 3-O-(2'-hydroxy-3'- methacryloyloxypropyl)-1,2:5,6-di-O-isopropylidene-\alpha -D-glucofuranose was easily prepared from D-glucose and methacrylic acid in 4 steps. The structure of the new methacrylic monomer was confirmed using FTIR, NMR (including ^1H-NMR, ^{13}C-NMR, COSY, HMQC and HMBC), and HPLC-MS. This work is part of our group's effort to obtain new polymers based on renewable resources with enhanced biodegradability and biocompatibility.
Polyphenolic Compounds From Geranium Purpureum Vill. Growing In Turkey, Di̇dem Şöhretoğlu, Mahmut Koray Sakar, Olov Sterner
Polyphenolic Compounds From Geranium Purpureum Vill. Growing In Turkey, Di̇dem Şöhretoğlu, Mahmut Koray Sakar, Olov Sterner
Turkish Journal of Chemistry
Two new flavonol derivatives, Geranioside A (kaempferol 3-[3-(\alpha-rhamnopyranosyl)-4-oxy-5-hydroxy-6-methyl-3,4-dihyropyran-2H- 2-pyranoside]) (1) and Geranioside B (quercetin 3-[3-(\alpha-rhamnopyranosyl)- 4-oxy-5-hydroxy-6-methyl-3,4-dihyropyran-2H-2-pyranoside]) (2), along with 5 known flavonols (quercetin (3), kaempferol (4), quercetin 4'-O-\beta -glucopyranoside (5), quercetin 3-O-\beta -glucopyranoside (6), and kaemferol-3-O-\beta -glucopyranoside (7)), a gallic acid derivative (methyl gallate (8)), and a hydrolysable tannin (pusilagin (9)), were isolated from the aerial parts of Geranium purpureum. The structures of the isolated compounds were elucidated on the basis of UV, IR, and 1D- and 2D-NMR experiments as well as TOF-MS.
Power Of Inhibition Activity Screening And 3d Molecular Modeling Approaches In Hdac 8 Inhibitor Design, Gamze Bora Tatar, Tenzi̇le Deni̇z Tokluman, Kemal Yelekçi̇, Hayat Yurter
Power Of Inhibition Activity Screening And 3d Molecular Modeling Approaches In Hdac 8 Inhibitor Design, Gamze Bora Tatar, Tenzi̇le Deni̇z Tokluman, Kemal Yelekçi̇, Hayat Yurter
Turkish Journal of Chemistry
In-vitro inhibition activity screening and in-silico 3D molecular modeling approaches are important tools for design and development of specific histone deacetylase (HDAC) inhibitors. The objective of this study was to investigate the consistency between these 2 approaches. The HDAC 8 inhibition activities of 8 randomly selected different carboxylic acid derivatives were screened and in-vitro experimental results were compared with in-silico molecular modeling calculations. This study demonstrated that there is no sole gold standard technique for inhibitor design, and it was concluded that a combination of molecular modeling and activity screening assays will ensure more comprehensive and dependable results.
Arsenic And Antimony Determination In Refined And Unrefined Table Salts By Means Of Hydride Generation Atomic Absorption Spectrometry--Comparison Of Sample Decomposition And Determination Methods, Nur Aksuner, Vedi̇a Nüket Ti̇rtom, Emür Henden
Arsenic And Antimony Determination In Refined And Unrefined Table Salts By Means Of Hydride Generation Atomic Absorption Spectrometry--Comparison Of Sample Decomposition And Determination Methods, Nur Aksuner, Vedi̇a Nüket Ti̇rtom, Emür Henden
Turkish Journal of Chemistry
An evaluation was made of different digestion methods for the determination of arsenic and antimony in table salt samples prior to hydride generation atomic absorption spectrometric analysis. Microwave acid digestion, classical wet digestion, dry ashing, and fusion were applied to the decomposition of salt samples and optimum conditions were investigated. Samples were decomposed by changing heating time, digestion techniques, and the amount and composition of acid, and then the concentrations of arsenic and antimony in an unrefined salt sample were measured. It is concluded that microwave acid digestion decomposes salt samples with a very short heating time and with small …
Facile And Convenient Synthesis Of Pyrimidine, 4h-3,1-Benzoxazin-4-One, Pyrazolo[5,1-B]Quinazoline, Pyrido[1,2-A]Quinazoline, And Chromeno[3' ,4' :4,5]Pyrido[1,2-A]Quinazoline Derivatives, Yousry A. Ammar, Samir Bondock, Abdallah G. El-Sehmi, Mohamed S.A El_Gaby, Ahmed M. Fouda, Hamdy Kh. Thabet
Facile And Convenient Synthesis Of Pyrimidine, 4h-3,1-Benzoxazin-4-One, Pyrazolo[5,1-B]Quinazoline, Pyrido[1,2-A]Quinazoline, And Chromeno[3' ,4' :4,5]Pyrido[1,2-A]Quinazoline Derivatives, Yousry A. Ammar, Samir Bondock, Abdallah G. El-Sehmi, Mohamed S.A El_Gaby, Ahmed M. Fouda, Hamdy Kh. Thabet
Turkish Journal of Chemistry
A convenient synthesis of a series of pyrimidine, 4H-3,1-benzoxazin-4-one, pyrazolo[5,1-b]quinazoline, pyrido[1,2-a]quinazoline, and chromeno[3' ,4' :4,5]pyrido[1,2-a]quinazoline derivatives, via the reactions of versatile and readily accessible methyl 2-(2-cyanoacetamido)benzoate (1) with the appropriate reagents, is described here.
Design And Evaluation Of A Query-Based Jamming Detection Algorithm For Wireless Sensor Networks, Murat Çakiroğlu, Ahmet Turan Özceri̇t
Design And Evaluation Of A Query-Based Jamming Detection Algorithm For Wireless Sensor Networks, Murat Çakiroğlu, Ahmet Turan Özceri̇t
Turkish Journal of Electrical Engineering and Computer Sciences
Jamming attacks, which are the main cause of data corruption and network blockages in wireless sensor networks (WSNs), are one of the most serious threats for WSNs. This type of attack not only blocks the ongoing communication in the network, but also causes the wireless nodes to exhaust their energy much earlier than expected. A countermeasure must be deployed against jamming attacks, especially in military and medical applications in which security breaches cannot be tolerated. In this paper, we have designed a new query-based jamming detection algorithm (QUJDA) to detect jamming attacks occurring in WSNs. QUJDA is an attack detection …
Neuro-Fuzzy Soft-Switching Hybrid Filter For Impulsive Noisy Environments, Şaban Özer, Hasan Zorlu
Neuro-Fuzzy Soft-Switching Hybrid Filter For Impulsive Noisy Environments, Şaban Özer, Hasan Zorlu
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, a new soft-switching hybrid filter based on a neuro-fuzzy network for impulsive noisy environments is proposed. The hybrid filter was built by combining an adaptive finite impulse response (FIR) filter, an adaptive weighted myriad (WMy) filter, and a soft-switching mechanism based on a neuro-fuzzy (NF) network. Performance of the hybrid filter was tested in \alpha-stable noisy situations and compared with adaptive FIR, WMy, and weighted median (WMd) filter performances. According to the simulation results; the proposed hybrid filter has better performance than the adaptive FIR, WMy, and WMd filters, and has the ability of effectively suppressing the …
Co-Occurrence Matrix And Its Statistical Features As A New Approach For Face Recognition, Alaa Eleyan, Hasan Demirel
Co-Occurrence Matrix And Its Statistical Features As A New Approach For Face Recognition, Alaa Eleyan, Hasan Demirel
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a new face recognition technique is introduced based on the gray-level co-occurrence matrix (GLCM). GLCM represents the distributions of the intensities and the information about relative positions of neighboring pixels of an image. We proposed two methods to extract feature vectors using GLCM for face classification. The first method extracts the well-known Haralick features from the GLCM, and the second method directly uses GLCM by converting the matrix into a vector that can be used in the classification process. The results demonstrate that the second method, which uses GLCM directly, is superior to the first method that …
Adaptive Wiener-Turbo Systems With Jpeg & Bit Plane Compressions In Image Transmission, Ersi̇n Göse
Adaptive Wiener-Turbo Systems With Jpeg & Bit Plane Compressions In Image Transmission, Ersi̇n Göse
Turkish Journal of Electrical Engineering and Computer Sciences
In recent years, for transmission of 2D colored images over the fading channels, a new scheme has been denoted as ``adaptive Wiener-turbo systems with JPEG & bit plane compressions'' (AW-TSwJBC). In this paper, the performance of AW-TSwJBC is introduced over Rician and Rayleigh fading channels. We benefited from the neighborhood relation of pixels for each color plane by using a new iterative block, the ``adaptive Wiener-turbo'' scheme, which employs a turbo decoder, JPEG encoder/decoders, and adaptive Wiener filtering. In our approach, we could also alter compression ratios due to the importance of the image to be transferred. Based on the …
Imitation Of Basic Hand Preshapes By Fluid Based Method: Fluidics Formation Control, Umut Ti̇lki̇, İsmet Erkmen, Aydan Müşerref Erkmen
Imitation Of Basic Hand Preshapes By Fluid Based Method: Fluidics Formation Control, Umut Ti̇lki̇, İsmet Erkmen, Aydan Müşerref Erkmen
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a new approach is developed, avoiding the correspondence problem caused by the difference in embodiment between imitator and demonstrator in imitation learning. In our work, the imitator is a fluidic system of dynamics totally different than the imitatee, which is a human performing hand gestures. The fluidic system is composed of fluid particles, which are used for the discretization of the problem domain. In this work, we demonstrate the fluidics formation control so as to imitate by observation basic hand preshaping features. Our fluidic formation control is based on setting suitable parameters of Smoothed Particle Hydrodynamics (SPH), …
Design And Ground Plane Optimization Of A Cpw-Fed Ultra-Wideband Antenna, Mohammed Al-Husseini, Ali Ramadan, Youssef Tawk, Ali El-Hajj, Karim Y. Kabalan
Design And Ground Plane Optimization Of A Cpw-Fed Ultra-Wideband Antenna, Mohammed Al-Husseini, Ali Ramadan, Youssef Tawk, Ali El-Hajj, Karim Y. Kabalan
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, an ultra-wideband antenna based on an egg-shaped conductor and a co-planar waveguide (CPW) feed is presented. The ground plane incorporates an egg-shaped slot with parametrized center and dimensions. By resizing the slot and moving its center, a slotted or a partial ground can be obtained. Based on this configuration, a parametric study that aims at achieving the best ultra-wideband (UWB) response of the antenna is done. The study shows that an excellent UWB response is achieved for a certain ground slot size, beyond which the response starts to degrade. However, as the slot size tends to infinity, …
Remote Mutual Authentication And Key Agreement Scheme Based On Elliptic Curve Cryptosystem, Eunjun Yoon
Remote Mutual Authentication And Key Agreement Scheme Based On Elliptic Curve Cryptosystem, Eunjun Yoon
Turkish Journal of Electrical Engineering and Computer Sciences
Remote mutual authentication is an important part of security, along with confidentiality and integrity, for systems that allow remote access over untrustworthy networks, like the Internet. In 2006, Shieh-Wang pointed out the weakness of Juang's remote mutual authentication scheme using smart card and further proposed a novel remote user authentication scheme using smart card. However, this paper demonstrates that Shieh-Wang's scheme still does not provide perfect forward secrecy and is vulnerable to a privileged insider's attack. We also present an improved scheme based on the Elliptic Curve Diffie-Hellman problem (ECDHP) and secure one-way hash function, in order to isolate such …
Experimental Analysis Of An Alternator Excited With Photovoltaic Cells For Small Power Plants, Kami̇l Ri̇fat İrfan Güney, Nevzat Onat
Experimental Analysis Of An Alternator Excited With Photovoltaic Cells For Small Power Plants, Kami̇l Ri̇fat İrfan Güney, Nevzat Onat
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, an automatic voltage regulator fed by photovoltaic (PV) cells was designed for use in small power alternators. The design aimed to increase the energy output of the alternator and to ensure necessary current output from the PV cells to support the synchronous generator excitation system. For energy transformation from small renewable energy sources, designers have favored the use of alternators that produce higher quality electric power, rather than asynchronous generators. We also address the designed system's suitability for real-life application, examining the steady-state performance of the photovoltaic cell excited alternator (PVCEA) with various loads and its behavior …
Fully Integrated Universal Biquads Using Operational Transresistance Amplifiers With Mos-C Realization, Ahmet Gökçen, Selçuk Kilinç, Uğur Çam
Fully Integrated Universal Biquads Using Operational Transresistance Amplifiers With Mos-C Realization, Ahmet Gökçen, Selçuk Kilinç, Uğur Çam
Turkish Journal of Electrical Engineering and Computer Sciences
Universal biquadratic filters employing operational transresistance amplifiers are presented. All 5 different second-order filtering functions, namely low-pass, high-pass, band-pass, notch, and all-pass, can be realized. The quality factor of the filters can be adjusted electronically without affecting resonant frequency. The configuration can be made fully integrated based on MOS-C realization, by making use of the current differencing and internally grounded inputs of OTRA. PSpice simulation results are given to verify the theoretical analysis.
An Effective Real Coded Ga Based Fuzzy Controller For Speed Control Of A Bldc Motor Without Speed Sensor, Ömer Aydoğdu, Ramazan Akkaya
An Effective Real Coded Ga Based Fuzzy Controller For Speed Control Of A Bldc Motor Without Speed Sensor, Ömer Aydoğdu, Ramazan Akkaya
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, an effective Real Coded Genetic Algorithm (GA) based optimal fuzzy controller is proposed. The fuzzy controller is used for sensorless speed control of a Brushless DC (BLDC) motor in DSP based application system. The advantages of adopting a real coded GA for the design and optimization of fuzzy controllers, which have a great deal of design and optimization parameters, are analyzed. Having accomplished optimization of developed fuzzy control system, a multi-objective performance index has been defined and it has been used as an objective function to be minimized in the real coded GA. Thus, the system can …
A Study On Influence Of Borax To Polyester Insulators, Aysel Ersoy, Ayten Kuntman
A Study On Influence Of Borax To Polyester Insulators, Aysel Ersoy, Ayten Kuntman
Turkish Journal of Electrical Engineering and Computer Sciences
In this study the effect of borax on polyester insulators is investigated by evaluating the tracking and erosion resistance using the inclined plane test. The test procedure follows the ASTM D2303 standard. During the test, 50 Hz current was acquired from the ground electrode allowing a sampling rate of 48000 samples per second. The effect of borax concentration on the glass transition and the degradation temperature is studied by employing differential scanning calorimetry (DSC) analysis. The addition of borax to the unsaturated polyester resulted in an increase in the glass transition temperature, while the addition of 0.5% of borax by …
Low-Complexity Parameters Estimator For Multiple 2d Domain Incoherently Distributed Sources, Xiansheng Guo, Qun Wan, Xiaofeng Shen, Heng Dou
Low-Complexity Parameters Estimator For Multiple 2d Domain Incoherently Distributed Sources, Xiansheng Guo, Qun Wan, Xiaofeng Shen, Heng Dou
Turkish Journal of Electrical Engineering and Computer Sciences
A new low-complexity parameters estimator for multiple two-dimensional (2D) domain incoherently distributed (ID) sources is presented. One 2D domain ID source is parameterized with four parameters, the central azimuth direction-of-arrival (DOA), azimuth angular spread, central elevation DOA and elevation angular spread. Based on the eigenstructure between the steering matrix and signal subspace, an average total least-squares via rotational invariance technique (TLS-ESPRIT) is used to estimate the central elevation DOA, and then a generalized multiple signal classification (GMUSIC) algorithm is derived to estimate the central azimuth DOA. Utilizing preliminary estimates obtained at a pre-processing stage, the angular spread parameters can be …
Decentralized Robust Load-Frequency Control Of Power System Based On Quantitative Feedback Theory, Aidin Sakhavati, Gevork Gharehpetian, Seyed Hossein Hosseini
Decentralized Robust Load-Frequency Control Of Power System Based On Quantitative Feedback Theory, Aidin Sakhavati, Gevork Gharehpetian, Seyed Hossein Hosseini
Turkish Journal of Electrical Engineering and Computer Sciences
This paper aims at investigating the problem of Load Frequency Control (LFC) in interconnected power systems in order to obtain robustness against uncertainties. A design method for a robust controller, based on Quantitative Feedback Theory (QFT), has been presented in this paper. For a two-area power system, the simulation results show that the system response with the proposed QFT controller exhibits transient response beyond PI controllers. It is also shown that the transient response of the tie line power can also be improved.
A Logic Method For Efficient Reduction Of The Space Complexity Of The Attribute Reduction Problem, Mehmet Hacibeyoğlu, Fati̇h Başçi̇ftçi̇, Şi̇rzat Kahramanli
A Logic Method For Efficient Reduction Of The Space Complexity Of The Attribute Reduction Problem, Mehmet Hacibeyoğlu, Fati̇h Başçi̇ftçi̇, Şi̇rzat Kahramanli
Turkish Journal of Electrical Engineering and Computer Sciences
The goal of attribute reduction is to find a minimal subset (MS) R of the condition attribute set C of a dataset such that R has the same classification power as C. It was proved that the number of MSs for a dataset with n attributes may be as large as (_{n/2}^n) and the generation of all of them is an NP-hard problem. The main reason for this is the intractable space complexity of the conversion of the discernibility function (DF) of a dataset to the disjunctive normal form (DNF). Our analysis of many DF-to-DNF conversion processes showed that approximately …