Mühendislik Fakültesi / Faculty of Engineering
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Publication Metadata only Thermal investigation of acid-activated clay minerals(Elsevier, 1987-09-30) Güler, Çetin; SARIER, NİHAL; 114920Samples of the clay mineral from the Çanakkale reserve in Turkey were activated with sulphuric acid under three different sets of conditions. DTA and TG curves of both natural and activated samples were then obtained and compared with one other.Publication Metadata only An Approach to the Design of Bilingual Desktop Publishing Systems(1988) Taylı, Murat; Salamah, A.; Tantawy, A.; 9351Publication Open Access Analysis of Single Flying Capacitor Converter by the State-Space Averaging Technique(IEEE, 1988) Bilgiç, Mehmet Oruç; Ehsani, M.; 1616The single flying capacitor converter (SFCC) is a two-quadrant power supply for energy storage and transfer system. It has applications in nuclear research and pulsed power systems in which superconductive coils are used in superconductive magnets. The authors derive analytical expressions for the time-averaged behavior of the SFCC by using the state-space averaging technique. Useful expressions are found for the average behavior of the SFCC. The results can be used in the design, control, and optimum operation of the system.Publication Metadata only Analysis of inductor-converter bridge by means of state-space averaging technique (superconducting magnet energy storage)(1988) Bilgiç, Mehmet Oruç; Ehsani, M.; 1616The time-averaged behavior of an inductor-converter bridge (ICB) circuit has been analyzed using a state-space averaging technique. The application of the state-space averaging technique to the ICB circuit analysis is somewhat different from the well known DC-to-DC converter cases such as buck, boost, and flyback of Cuk converter analysis in that the first-order approximation of the state transition matrix will give trivial results. The results, which were previously obtained in infinite Fourier series form, are in closed form. A comparison is also made with the Fourier result. The ICB is a two-quadrant power supply for superconductive energy storage magnets. Closed-form expressions are found for the average current, voltage, and power behavior of the ICB. This application is somewhat different from the analysis of other DC choppers such as buck, boost, flyback, and Cuk converters in that the first-order terms are identically zero and the second-order terms have to be used.Publication Metadata only β-Carotene adsorption on acid-activated montmorillonite(1988-05) Güler, Çetin; SARIER, NİHAL; 114920The adsorption of β-carotene from solution in benzene on acid-activated Canakkale montmorillonite of Turkey has been investigated. The adsorption isotherm had two steps. The first step was of the Langmuir type, and the isosteric heat of adsorption corresponding to this step was equal to −193.514 kJ/mol. The decrease in the total number of acid sites of the clay surface was determined to be 0.45×10−4 mol/g clay by nonaqueous titration with diethylamine. The phenomenon seems to be mainly a chemisorption stemming from the interaction of β-carotene with acid sites. Also, the activated clay acts as an oxidation catalyst on the β-carotene left in the solution.Publication Metadata only The mechanism of β- Carotene adsorption on activated montmorillonite(Springer-Verlag, 1989-07) Güler, Çetin; SARIER, NİHAL; 114920The variations in the structure of mineral during adsorption have been examined comparing the results of X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetry (TG) and infrared (IR) spectroscopy of the acid activated montmorillonite clay mineral before and after adsorption of β-carotene. Based on the results, it was concluded that β-carotene attaches to the clay surface in the form of carbonium ions either by forming hydrogen bonds with Brönsted sites or by forming coordination bonds with Lewis sites of the activated clay mineral.Publication Open Access Inverse Dual Converter (IDC) for High Power DC-DC Applications(IEEE, 1990) Ehsani, Mehrdad; Husain, Iqbal; Bilgiç, Mehmet Oruç; 1616The inverse dual converter (IDC), suitable for high-power DC-DC conversion applications, is presented. The IDC is a voltage source converter with an AC link and has been derived from an inductor converter bridge. This capacitor commutated converter is capable of continuous voltage step-up or step-down control over a wide range without the need of a transformer. In addition to high-frequency switching the converter is characterized by soft switching techniques, reducing constraints on the ratings of the switches. The average model developed with the help of gyrator theory provides sufficient information for control strategies and design considerations. The results of gyrator modeling and computer simulation are compared with experimental results obtained from a prototype IDC.Publication Metadata only Kinetics of the thermal dehydration of acid-activated montmorillonite by the rising temperature technique(1990) Güler, Çetin; SARIER, NİHAL; 114920The activation energies of dehydration and combustion of organic materials in a clay sample, and of dehydration of natural and acid-activated montmorillonite have been determined using a rising temperature programme technique. The effect of acid activation of the montmorillonite on the dehydroxylation is discussed.Publication Metadata only Object Oriented Approach to the Design of Real Time Distributed Operating Systems(1990) Bor, M.; Taylı, M.; 9351Publication Metadata only An efficient circuit switching mechanism for Inter process communication in a transputer network(IEEE, 1990) Taylı, Murat; Benmaiza, M.; 9351Distributed real time system require interprocess communication (IPC) services to be not only reliable and efficient but also predictable. In such dynamic systems, predictability can only be achieved by proper architectural support that embodies adequate mechanisms and policies within the operating system. The authors present the design and implementation of predictable transport level communication services supported by the kernel of a real time distributed operating system (RTDOS). RTDOS IPC services are built on a hybrid platform, involving both message- and circuit-switching. Experimental results showed that RTDOS IPC was able to deliver millisecond-level connection times, guaranteed within the prescribed limits of system configuration.Publication Metadata only Proceedings of the 1993 World Transputer Congress(1990) Taylı, Murat; Benmaiza, M.; 9351Publication Metadata only Object Oriented Approach to the Design of Real Time Distributed Operating Systems(1990) Bor, M.; Taylı, Murat; 9351Publication Metadata only Building Bilingual Microcomputer Systems(1990-05) Taylı, Murat; Salamah, A.; 9351In the Arab world the need for bilingual microcomputer systems is ever increasing. In addition to the ability to process the Arabic and English scripts, an ideal system should support the use of existing applications with Arabic data and the access to the system facilities through Arabic interfaces. The Integrated Arabic System (IAS) was developed to study the feasibility of building such systems using existing microcomputers and software solutions.Publication Open Access Topological Variations of the Inverse Dual Converter for High Power DC-DC Applications(IEEE, 1990-10-07) Ehsani, M.; Laskai, L.; Bilgiç, Mehmet Oruç; 1616DC to DC power converter topologies that are suitable for high-density, high-power supplies are presented. Topological variations on the basic inverse dual converter (IDC) circuit, such as the coupled transformer and the multiphase and multipulse derivation of the single-phase IDC, are analyzed, and simulation results are discussed. The topologies have most of the IDC features, such as buck-boost operation, bidirectional power processing, capacitive commutation for switches, and unlimited high-power capability. The multiphase, the coupled transformer, and the power distribution IDC topologies offer additional properties, such as significant power-density improvement isolation. AC tapping, and input-current reduction. A quantitative comparison between the single- and the multiphase IDC is presented.Publication Metadata only The Mechanism of Acid Activation of Montmorillonite(TÜBİTAK Yayınları, 1991-01) Güler, ÇetinPublication Open Access Capacitively Coupled Converter (C3) for HighPower DC-DC Conversion(1991-07) Ehsani, Mehrdad; Bilgiç, Mehmet Oruç; Khan, S.; 1616The capacitive coupled converter for high-power voltage source DC-DC applications is described. Its steady-state and dynamic behavior are analyzed theoretically and by computer simulation. Factors affecting its operation and control are discussed and some design rules are presented. A proof-of-principle model of the capacitive coupled converter was constructed, and its waveforms were recordedPublication Metadata only IPC for Predictable Message Passing in a Multiloop Transputer Network(1993) Benmaiza, M.; Taylı, Murat; 9351Publication Metadata only Inverse dual converter (IDC) for high power DC-DC applications(IEEE, 1993) Ehsani, M.; Husain, I.; Bilgiç, Mehmet Oruç; 1616A family of DC-DC converters suitable for high-power applications is introduced. The inverse dual converter (IDC) is capable of continuous voltage step-up or step-down control over a wide range of and without the need of a transformer. Experimental verification of the analysis is given for the simple single-phase IDC. Some of the more sophisticated members of the IDC family are described, and their characteristics and possible application, are mentioned.Publication Metadata only Power converters as natural gyrators(IEEE, 1993-12) Ehsani, Mehrdad; Husain, Iqbal; Bilgiç, Mehmet Oruç; 1616The authors investigate the open-loop gyrator behavior of a class of DC-DC converters that are characterized by double bridges. If the switching frequency of the double bridge converter is high enough with respect to its natural frequencies, the converter can be viewed as a gyrator from its terminals. Unlike other gyrator modeling approaches for converters, the double bridge converters naturally behave as gyrators without any extra control circuits.Publication Metadata only Capacitor coupled converter (C3) for high power DC conversion(IEEE, 1995) Ehsani, Morteza; Bilgiç, Mehmet Oruç; Khan, S.; Laskai, L.; Jeong, Seung-Gi; 1616The bang-bang controlled capacitor coupled converter (C3) is described in this paper. Due to the converter's inherent commutating property, the C3 can accommodate thyristors as well as high-power gate turn-off switches, due to zero-current switching transitions. The zero-current switching is achieved at no current stress increase, therefore, the topology is considered appropriate for high-power processing. DC and small signal AC models are derived for the bang-bang controlled C3, a design procedure is proposed, and simulation results are discussed. Finally, oscillograms from a proof of principle prototype circuit are presented