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Articles 5401 - 5430 of 10319
Full-Text Articles in Physical Sciences and Mathematics
Palladium Nanoparticles Supported On Modified Polystyrene Resin As A Polymeric Catalyst For Sonogashira-Hagihara Coupling Reactions, Bahman Tamami, Fatemeh Nowroozi Dodeji, Soheila Ghasemi
Palladium Nanoparticles Supported On Modified Polystyrene Resin As A Polymeric Catalyst For Sonogashira-Hagihara Coupling Reactions, Bahman Tamami, Fatemeh Nowroozi Dodeji, Soheila Ghasemi
Turkish Journal of Chemistry
Pd(0) nanoparticles supported on modified crosslinked polystyrene were synthesized and characterized. Crosslinked polystyrene was reacted with trioxane and chlorotrimethylsilane in the presence of SnCl$_{4}$ to form Merrifield resin. The Merrifield resin was then converted to polymer-bound $\beta $-aminoalcohol and subsequently to $\beta$-aminophosphinite ligand. This polymeric ligand was reacted with PdCl$_{2}$ to obtain a polymeric Pd(0) complex. The TEM image of the Pd catalyst showed good dispersion of catalytic sites. The Pd catalyst exhibits excellent activity and stability in copper-free Sonogashira-Hagihara cross-coupling reactions under aerobic conditions. This protocol can be applied efficiently to the coupling reactions of chloro- as well as …
Ray Tracing For Optimization Of Compound Parabolic Concentrators For Solar Collectors Of Enclosed Design, Vladimir Yurchenko, Eduard Yurchenko, Mehmet Çi̇ydem, Onat Totuk
Ray Tracing For Optimization Of Compound Parabolic Concentrators For Solar Collectors Of Enclosed Design, Vladimir Yurchenko, Eduard Yurchenko, Mehmet Çi̇ydem, Onat Totuk
Turkish Journal of Electrical Engineering and Computer Sciences
We present our developments in computer simulations and optimization of compound parabolic concentrators (CPCs) for solar heat collectors. Issues of both the optical and thermal optimization of CPC collectors of enclosed design are discussed. Ray tracing results for a CPC with a V-shaped absorber are presented. A range of optimal values for the apex angle of a V-shaped absorber is proposed for a CPC collector of typical design.
Integration Of Wind Power For Optimal Power System Black-Start Restoration, Amany El Zonkoly
Integration Of Wind Power For Optimal Power System Black-Start Restoration, Amany El Zonkoly
Turkish Journal of Electrical Engineering and Computer Sciences
Integration of wind farms into power systems may increase the risk of power system blackouts due to the uncertain nature of their output power. In the meantime, wind turbines have relatively short starting time when compared to non-black-start (NBS) generating units. For this reason, wind farms need to participate in power system restoration after blackouts. The decision of restoring a wind farm depends on its output power and the characteristics of the power system. The power system restoration should be accomplished as soon as possible. For complete power system restoration, three stages must be completed: generation restoration, transmission system restoration, …
Reliability Assessment Of A Standalone Wind-Conventional/Energy Storage System Using Probabilistic Production Simulation Method, Hossein Delavaripour, Behzad Mirzaeian Dehkordi
Reliability Assessment Of A Standalone Wind-Conventional/Energy Storage System Using Probabilistic Production Simulation Method, Hossein Delavaripour, Behzad Mirzaeian Dehkordi
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a reliability evaluation technique for a small standalone system including wind and conventional resources integrated with an energy storage system. A battery bank is considered as the energy storage system. The focus in this analysis is on the effect of battery modeling and its performance on system reliability. In this way, this paper presents an accurate model for the electrochemical batteries, which takes into account all the influential characteristics of the battery related to reliability studies, such as depth of charge, efficiency of charge, and rate of discharge. The proposed reliability evaluation method is based on the …
Optimization Of Grid Connected Micro-Grid Consisting Of Pv/Fc/Uc With Considered Frequency Control, Hamid Hasanzadehfard, Masoud Moghaddas-Tafreshi, Sayed Mehdi Hakimi
Optimization Of Grid Connected Micro-Grid Consisting Of Pv/Fc/Uc With Considered Frequency Control, Hamid Hasanzadehfard, Masoud Moghaddas-Tafreshi, Sayed Mehdi Hakimi
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, ultracapacitors are used as short-term storages for the frequency control of grid-connected microgrid that consists of photovoltaic panels, fuel cells, and the battery packs as long-term storages. Fuel cells and battery packs have delays in load tracking; therefore, ultracapacitors are used to compensate for the sudden power fluctuations in the microgrid that occur due to the output power uncertainty of the PV arrays and the loads required in the microgrid, as well as the sudden interruption of the main grid. The microgrid consists of interruptible and uninterruptible loads. When the total produced power in the microgrid, in …
Hybrid Adaptive Neuro-Fuzzy B-Spline--Based Sssc Damping Control Paradigm Using Online System Identification, Laiq Khan, Rabiah Badar
Hybrid Adaptive Neuro-Fuzzy B-Spline--Based Sssc Damping Control Paradigm Using Online System Identification, Laiq Khan, Rabiah Badar
Turkish Journal of Electrical Engineering and Computer Sciences
B-spline membership functions have produced promising results in the field of signal processing and control due to their local control property. This work explores the potential of B-spline--based adaptive neuro-fuzzy wavelet control to damp low frequency power system oscillations using a static synchronous series compensator (SSSC). A comparison of direct and indirect adaptive control based on hybrid adaptive B-spline wavelet control (ABSWC) is presented by introducing the online identification block. ABSWC with identification (ABSWCI) provides the sensitivity information of the plant needed to control the system. The parameters of the control and identification block are updated online using a gradient …
An Ofdm Throughput Analysis For Cognitive Radio Application In Contiguous Or Noncontiguous Tv White Spaces, Cebrai̇l Çi̇fli̇kli̇, Ahmet Turgut Tuncer, Yusuf Öztürk
An Ofdm Throughput Analysis For Cognitive Radio Application In Contiguous Or Noncontiguous Tv White Spaces, Cebrai̇l Çi̇fli̇kli̇, Ahmet Turgut Tuncer, Yusuf Öztürk
Turkish Journal of Electrical Engineering and Computer Sciences
Radio frequency spectrum is a finite and scarce resource. Efficient use of the radio frequency spectrum is a fundamental research issue. Since a large portion of the assigned radio frequency spectrum is used only sporadically, the bands currently allocated to TV services can be opportunistically reassigned to support broadband networking services while continuing to provide broadcast TV. The fragmented and unused TV channels named white spaces have a considerable amount of bandwidth potential and long transmission ranges. Bandwidth scalability can be supported by bonding multiple contiguous or noncontiguous consecutive channels using orthogonal frequency division multiplexing (OFDM)-based cognitive radio. In this …
Effect Of Nonuniform Varying Delay On The Rate Of Convergence In Averaging-Based Consensus, Onur Ci̇han, Mehmet Akar
Effect Of Nonuniform Varying Delay On The Rate Of Convergence In Averaging-Based Consensus, Onur Ci̇han, Mehmet Akar
Turkish Journal of Electrical Engineering and Computer Sciences
This paper discusses the effect of nonuniform varying communication delay on distributed consensus algorithms in discrete time. After introducing the delayed mathematical model, we first investigate the ergodicity of the delayed system using the properties of scrambling matrices. Subsequently, the effect of nonuniform varying delay on convergence is examined. It is shown theoretically that nonuniform delay is not detrimental to the convergence rate of the algorithm for directed acyclic graphs. The results are also illustrated with several numerical examples.
Semiconductor Laser Beam Bending, Remzi̇ Yildirim, Fati̇h Vehbi̇ Çelebi̇
Semiconductor Laser Beam Bending, Remzi̇ Yildirim, Fati̇h Vehbi̇ Çelebi̇
Turkish Journal of Electrical Engineering and Computer Sciences
This study is about a single-component cylindrical structured lens with a gradient curve that was used for bending laser beams. It operates under atmospheric conditions and bends the laser beam independently of temperature, pressure, polarity, polarization, magnetic field, electric field, radioactivity, and gravity. A single-piece cylindrical lens that can bend laser beams was developed. Lenses are made of transparent, tinted, or colored glass and are used to undermine or absorb the energy of laser beams. This study is not a work of a plasma filamentation, nor is related to a self-accelerating wave packet. Rather, it focuses on bending the laser …
Optimal Backup Parent Pools For Resilient Multicast Trees On Peer-To-Peer Networks, Emrullah Turhan Tunali, Müge Sayit
Optimal Backup Parent Pools For Resilient Multicast Trees On Peer-To-Peer Networks, Emrullah Turhan Tunali, Müge Sayit
Turkish Journal of Electrical Engineering and Computer Sciences
Due to churn as well as node and link failures in peer-to-peer (P2P) networks, providing resilient multicast is a challenging issue, particularly for overlay trees. In this work, we first study analytical properties of the backup parent pool that aims at improving the resilience of overlay multicast trees in P2P video streaming. We then present a novel greedy degree-constrained multicast tree construction algorithm that addresses the tradeoffs between maximizing resiliency, maximizing bandwidth utilization, and minimizing delay. The choice of essential design parameters is studied together with seamlessness of the streaming under a variety of fault scenarios. Simulation results indicate that …
Fast Bitwise Pattern-Matching Algorithm For Dna Sequences On Modern Hardware, Giyasetti̇n Özcan, Osman Sabri̇ Ünsal
Fast Bitwise Pattern-Matching Algorithm For Dna Sequences On Modern Hardware, Giyasetti̇n Özcan, Osman Sabri̇ Ünsal
Turkish Journal of Electrical Engineering and Computer Sciences
We introduce a fast bitwise exact pattern-matching algorithm, which speeds up short-length pattern searches on large-sized DNA databases. Our contributions are two-fold. First, we introduce a novel exact matching algorithm designed specifically for modern processor architectures. Second, we conduct a detailed comparative performance analysis of bitwise exact matching algorithms by utilizing hardware counters. Our algorithmic technique is based on condensed bitwise operators and multifunction variables, which minimize register spills and instruction counts during searches. In addition, the technique aims to efficiently utilize CPU branch predictors and to ensure smooth instruction flow through the processor pipeline. Analyzing letter occurrence probability estimations …
A New High-Performance Current-Mode Fuzzy Membership Function Circuit And Its Application, Turgay Temel
A New High-Performance Current-Mode Fuzzy Membership Function Circuit And Its Application, Turgay Temel
Turkish Journal of Electrical Engineering and Computer Sciences
A new current-mode fuzzy-membership function circuit is proposed. The circuit has a very compact and simple architecture based on the simultaneous use of winner- and loser-take-all topologies. The circuit has also the advantage of easily adjusting generated membership function characteristics such as center or mean and width with a straightforward application of respective input currents. It is shown that the new circuit outperforms previous counterparts in terms of speed, power consumption, layout area, and robustness to variations in design parameters and errors. As an application, a fuzzy-classifier is designed with a new membership circuit as a seven fuzzy level controller.
Magnetomineralogical Changes Along The Kohistan-Karakoram Collision Zone Innorth Pakistan: Implications For Variable Thermochemical Activities, Haider Zaman, Abdullah O. Bamousa
Magnetomineralogical Changes Along The Kohistan-Karakoram Collision Zone Innorth Pakistan: Implications For Variable Thermochemical Activities, Haider Zaman, Abdullah O. Bamousa
Turkish Journal of Earth Sciences
To identify remanence-carrying magnetic minerals and document their thermochemical behavior, detailed rock magnetic investigations were conducted on Cretaceous-Tertiary rocks collected from northwestern and northeastern Kohistan, northern Pakistan. Rock magnetic results from each area are clearly differentiated on the basis of site location. Detrital hematite is identified as a main magnetic carrier in red beds of northwestern Kohistan located at some distance from the Northern Suture Zone with subsidiary pigmentary hematite and altered magnetite. In contrast, the magnetic mineralogy of purple-colored rocks adjacent to the Northern Suture Zone is shared by unstable secondary pyrrhotite, magnetite, and hematite. The magnetic mineralogy of …
Petrology And Geochemistry Of Mafic Dykes From The Muslim Bagh Ophiolite (Pakistan): Implications For Petrogenesis And Emplacement, Mohammad Ishaq Kakar, Khalid Mahmood, Mohammad Arif, Mehrab Khan, Andrew C. Kerr, Mohibullah Mohibullah, Aimal Khan Kasi
Petrology And Geochemistry Of Mafic Dykes From The Muslim Bagh Ophiolite (Pakistan): Implications For Petrogenesis And Emplacement, Mohammad Ishaq Kakar, Khalid Mahmood, Mohammad Arif, Mehrab Khan, Andrew C. Kerr, Mohibullah Mohibullah, Aimal Khan Kasi
Turkish Journal of Earth Sciences
Two different types of mafic dykes are found in the Muslim Bagh Ophiolite: 1) a sheeted dyke complex and 2) a mafic dyke swarm. Relative to the host plutonic section, the sheeted dykes are poorly developed, implying that they formed in an oceanic setting with a low and intermittent supply of magma, probably because of cyclic accumulation of crystals at the base of the magma chamber. Both the sheeted dykes and the dyke swarms have been metamorphosed to greenschist/amphibolite facies conditions. With the exception of the upper level gabbros and sheeted dykes, the dyke swarms crosscut almost the whole ophiolite …
A Note On Infinite Groups Whose Subgroups Are Close To Be Normal-By-Finite, Francesco De Giovanni, Federica Saccomanno
A Note On Infinite Groups Whose Subgroups Are Close To Be Normal-By-Finite, Francesco De Giovanni, Federica Saccomanno
Turkish Journal of Mathematics
A group G is said to have the CF-property if the index X:X_G is finite for every subgroup X of G. Extending previous results by Buckley, Lennox, Neumann, Smith, and Wiegold, it is proven here that if G is a locally graded group whose proper subgroups have the CF-property, then G is abelian-by-finite, provided that all its periodic sections are locally finite. Groups in which all proper subgroups of infinite rank have the CF-property are also studied.
Symplectic Groupoids And Generalized Almost Subtangent Manifolds, Fulya Şahi̇n
Symplectic Groupoids And Generalized Almost Subtangent Manifolds, Fulya Şahi̇n
Turkish Journal of Mathematics
We obtain equivalent assertions among the integrability conditions of generalized almost subtangent manifolds, the condition of compatibility of source and target maps of symplectic groupoids with symplectic form, and generalized subtangent maps.
Encapsulation Of Copper(Ii) Complexes With Three Dentate No$_{2}$ Ligands Derived From 2,6-Pyridinedicarboxylic Acid In Nay Zeolite, Massomeh Ghorbanloo, Somayeh Ghamari, Hidenori Yahiro
Encapsulation Of Copper(Ii) Complexes With Three Dentate No$_{2}$ Ligands Derived From 2,6-Pyridinedicarboxylic Acid In Nay Zeolite, Massomeh Ghorbanloo, Somayeh Ghamari, Hidenori Yahiro
Turkish Journal of Chemistry
2,6-Pyridinedicarboxylic acid (H$_{2}$dipic) reacts with copper-exchanged zeolite NaY to form [Cu(dipic)(H$_{2}$O)$_{2}$]$_{n}$, which is encapsulated in the pores of the zeolite. In this zeolite-encapsulated form, the copper derivative functions as an efficient catalyst for the oxidation of cyclohexene, toluene, cyclohexane, and ethyl benzene in the presence of hydrogen peroxide (as an oxidant). The catalyst was readily recovered from the reaction mixture, and it could be reused for an additional three runs without perceptible loss of activity. The heterogeneous catalyst exhibited considerably higher activity and selectivity compared with [Cu(dipic)(H$_{2}$O)$_{2}$]$_{n}$ itself.
Thermal Structure Of Low-Grade Accreted Lower Cretaceous Distal Turbidites, The Central Pontides, Turkey: Insights For Tectonic Thickening Of An Accretionary Wedge, Mesut Aygül, Aral I. Okay, Roland Oberhänsli, Martin A. Ziemann
Thermal Structure Of Low-Grade Accreted Lower Cretaceous Distal Turbidites, The Central Pontides, Turkey: Insights For Tectonic Thickening Of An Accretionary Wedge, Mesut Aygül, Aral I. Okay, Roland Oberhänsli, Martin A. Ziemann
Turkish Journal of Earth Sciences
No abstract provided.
Calcareous Nannofossils Of The Paleocene Eocene Transition In Four Sections From Egypt, Mahmoud Faris, Sherif Farouk
Calcareous Nannofossils Of The Paleocene Eocene Transition In Four Sections From Egypt, Mahmoud Faris, Sherif Farouk
Turkish Journal of Earth Sciences
A detailed analysis of calcareous nannofossil assemblages was carried out across the Paleocene-Eocene transition in four outcrops in Egypt (the Gebel Matulla, Markha, El-Quss Abu Said, and Gebel Duwi sections) that span the Discoaster multiradiatus (NP9) to Discoaster binodosus (NP11) zones. The Paleocene-Eocene (P/E) boundary is placed in the lower part of the Esna Shale Formation based on the LOs of the Calcareous Nannofossil Excursion Taxa (CNET or RD) that define the base of NP9b. The studied sections are considered complete and document the Paleocene-Eocene Thermal Maximum (PETM). The occurrences of long-armed and asymmetrical discoasters (e.g., D. araneus, D. anartios) …
Some Remarks On Distributional Chaos For Bounded Linear Operators, Lvlin Luo, Bingzhe Hou
Some Remarks On Distributional Chaos For Bounded Linear Operators, Lvlin Luo, Bingzhe Hou
Turkish Journal of Mathematics
The aim of this paper is to study distributional chaos for bounded linear operators. We show that distributional chaos of type k \in {1,2} is an invariant of topological conjugacy between two bounded linear operators. We give a necessary condition for distributional chaos of type 2 where it is possible to distinguish distributional chaos and Li--Yorke chaos. Following this condition, we compare distributional chaos with other well-studied notions of chaos for backward weighted shift operators and give an alternative proof to the one where strong mixing does not imply distributional chaos of type 2 (Martínez-Giménez F, Oprocha P, Peris A. …
On Condition $(Pwp)_{W}$ For $S$-Posets, Xingliang Liang, Yanfeng Luo
On Condition $(Pwp)_{W}$ For $S$-Posets, Xingliang Liang, Yanfeng Luo
Turkish Journal of Mathematics
Golchin and Rezaei (Commun Algebra 2009; 37: 1995--2007) introduced the weak version of Condition $(PWP)$ for $S$-posets, called Condition $(PWP)_{w}$. In this paper, we continue to study this condition. We first present a necessary and sufficient condition under which the $S$-poset $A(I)$ satisfies Condition $(PWP)_{w}$. Furthermore, we characterize pomonoids $S$ over which all cyclic (Rees factor) $S$-posets satisfy Condition $(PWP)_{w}$, and pomonoids $S$ over which all Rees factor $S$-posets satisfying Condition $(PWP)_{w}$ have a certain property. Finally, we consider direct products of $S$-posets satisfying Condition $(PWP)_{w}$.
The Iteration Digraphs Of Finite Commutative Rings, Yangjiang Wei, Gaohua Tang
The Iteration Digraphs Of Finite Commutative Rings, Yangjiang Wei, Gaohua Tang
Turkish Journal of Mathematics
For a finite commutative ring $S$ (resp., a finite abelian group $S$) and a positive integer $k\geqslant2$, we construct an iteration digraph $G(S, k)$ whose vertex set is $S$ and for which there is a directed edge from $a\in S$ to $b\in S$ if $b=a^k$. We generalize some previous results of the iteration digraphs from the ring $\mathbb{Z}_n$ of integers modulo $n$ to finite commutative rings, and establish a necessary and sufficient condition for $G(S, k_1)$ and $G(S, k_2)$ to be isomorphic for any finite abelian group $S$.
Solid-Phase Total Synthesis Of Cyclic Peptide Brachystemin A And Its Immunomodulating Activity, Zafar Ali Shah, Almas Jabeen, Samreen Soomro, M.Ahmed Mesaik, M.Iqbal Choudhary, Farzana Shaheen
Solid-Phase Total Synthesis Of Cyclic Peptide Brachystemin A And Its Immunomodulating Activity, Zafar Ali Shah, Almas Jabeen, Samreen Soomro, M.Ahmed Mesaik, M.Iqbal Choudhary, Farzana Shaheen
Turkish Journal of Chemistry
Brachystemin A (\textbf{1}) is a biologically active peptide from a Chinese traditional plant \textit{Brachystemma calycinum} D. Don. (Caryophyllaceae). The current study describes the complete solid-phase total synthesis of peptide \textbf{1} by using Kenner's sulfonamide safety-catch linker strategy. It was identified by QTOF/MS data and NMR studies. Synthetic peptide \textbf{1} was tested for its immunomodulatory effect on different inflammatory parameters, including production of inflammatory cytokines, interleukin 2 (IL-2), tumor necrosis factor-$\alpha $ (TNF-$\alpha )$, and interleukin-1$\beta $ (IL-1$\beta )$, and generation of nitric oxide (NO$^{.})$. The synthetic peptide \textbf{1} showed a moderate to low level of inhibition on the production of …
Schrödinger Equation With Modified Smorodinsky-Winternitz Potential, Akpan Ndem Ikot, Hassan Hassanabadi, Elham Maghsoodi, Saber Zarrinkamar
Schrödinger Equation With Modified Smorodinsky-Winternitz Potential, Akpan Ndem Ikot, Hassan Hassanabadi, Elham Maghsoodi, Saber Zarrinkamar
Turkish Journal of Physics
We present solutions of the Schrödinger equation for the modified Smorodinsky-Winternitz potential in an exact analytical manner. The considered potential is of noncentral nature and includes the Pöschl-Teller potential in the radial as the radial term and includes both azimuthal and polar angle-dependent terms. The problem, after separation of variables, is solved via the Nikiforov-Uvarov method and the solutions are reported.
Higher-Dimensional Bianchi Type-Iii Universe With Strange Quark Matter Attached To String Cloud In General Relativity, Pradyumn Kumar Sahoo, Bivudutta Mishra
Higher-Dimensional Bianchi Type-Iii Universe With Strange Quark Matter Attached To String Cloud In General Relativity, Pradyumn Kumar Sahoo, Bivudutta Mishra
Turkish Journal of Physics
In this paper, our intention is to construct 5-dimensional Bianchi type-III cosmological models for quark matter attached to a string cloud in general relativity. Different cases for the metric potentials are considered and studied. The physical and kinematical behaviors of all the models are discussed. It is observed that most of the models admit initial singularity.
(X, Y)-Gorenstein Projective And Injective Modules, Qunxing Pan, Faqun Cai
(X, Y)-Gorenstein Projective And Injective Modules, Qunxing Pan, Faqun Cai
Turkish Journal of Mathematics
This paper introduces and studies (X,Y)-Gorenstein projective and injective modules, which are a generalization of Enochs' Gorenstein projective and injective modules, respectively. Our main aim is to investigate the relations among various (X,Y)-Gorenstein projective modules.
Investigation Of Respiratory And Heart Rate Variability In Hypertensive Patients, Ramazan Aldemi̇r, Mahmut Tokmakçi
Investigation Of Respiratory And Heart Rate Variability In Hypertensive Patients, Ramazan Aldemi̇r, Mahmut Tokmakçi
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, in order to examine the effect of respiration on heart rate variability (HRV), signal processing analyses were performed between the signal received from the periodic movement of the chest of respiration and the pulse plethysmograph (PPS) signal, providing the calculation of both the time and frequency behavior of HRV and also including pulse rate information at the same time. Respiration is used as the comparison parameter in both healthy subjects and in hypertensive patients, not only with the time and frequency components of the HRV, but also with the galvanic skin resistance simultaneously taken with body temperature …
A Hierarchic Approach Based On Swarm Intelligence To Solve The Traveling Salesman Problem, Mesut Gündüz, Mustafa Servet Kiran, Eren Özceylan
A Hierarchic Approach Based On Swarm Intelligence To Solve The Traveling Salesman Problem, Mesut Gündüz, Mustafa Servet Kiran, Eren Özceylan
Turkish Journal of Electrical Engineering and Computer Sciences
The purpose of this paper is to present a new hierarchic method based on swarm intelligence algorithms for solving the well-known traveling salesman problem. The swarm intelligence algorithms implemented in this study are divided into 2 types: path construction-based and path improvement-based methods. The path construction-based method (ant colony optimization (ACO)) produces good solutions but takes more time to achieve a good solution, while the path improvement-based technique (artificial bee colony (ABC)) quickly produces results but does not achieve a good solution in a reasonable time. Therefore, a new hierarchic method, which consists of both ACO and ABC, is proposed …
Discrete-Time Modeling Of Hamiltonian Systems, Yaprak Yalçin, Leyla Gören Sümer, Salman Kurtulan
Discrete-Time Modeling Of Hamiltonian Systems, Yaprak Yalçin, Leyla Gören Sümer, Salman Kurtulan
Turkish Journal of Electrical Engineering and Computer Sciences
The problem of discrete-time modeling of the lumped-parameter Hamiltonian systems is considered for engineering applications. Hence, a novel gradient-based method is presented, exploiting the discrete gradient concept and the forward Euler discretization under the assumption of the continuous Hamiltonian model is known. It is proven that the proposed discrete-time model structure defines a symplectic difference system and has the energy-conserving property under some conditions. In order to provide alternate discrete-time models, 3 different discrete-gradient definitions are given. The proposed models are convenient for the design of sampled-data controllers. All of the models are considered for several well-known Hamiltonian systems and …
Mras-Based Sensorless Speed Backstepping Control For Induction Machine, Using A Flux Sliding Mode Observer, Mohamed Moutchou, Ahmed Abbou, Hassan Mahmoudi
Mras-Based Sensorless Speed Backstepping Control For Induction Machine, Using A Flux Sliding Mode Observer, Mohamed Moutchou, Ahmed Abbou, Hassan Mahmoudi
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, an induction machine rotor speed and rotor flux control using a sensorless backstepping control scheme is discussed. The most interesting point of this technique is that it deals with the nonlinearity of a high-order system by using the virtual control variable to make this system simple, and thus the control outputs can be derived step by step through appropriate Lyapunov functions. To avoid the use of a mechanical sensor, the rotor speed estimation is made by an observer using the model reference adaptive system (MRAS) technique; in order to estimate rotor flux, a sliding mode observer is …