Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 5761 - 5790 of 10319

Full-Text Articles in Physical Sciences and Mathematics

Mppt Of Pv Array Using Stepped-Up Chaos Optimization Algorithm, Lihua Wang, Xueye Wei, Yuqin Shao, Tianlong Zhu, Junhong Zhang Jan 2015

Mppt Of Pv Array Using Stepped-Up Chaos Optimization Algorithm, Lihua Wang, Xueye Wei, Yuqin Shao, Tianlong Zhu, Junhong Zhang

Turkish Journal of Electrical Engineering and Computer Sciences

In order to achieve maximum efficiency, a maximum power point tracking (MPPT) scheme should be applied in photovoltaic systems. Among all the MPPT schemes, the chaos optimization scheme is one of the hot topics in recent years. In this study, a novel stepped-up chaos optimization algorithm is presented. A chaos mapping $x_{n+1} =\mu \sin (\pi x_{n} )$ is used as a chaos generator to produce a chaos variable. In the process of MPPT, a coarse search is done to find the current optimal solution in a certain range, and then a fine search reduces the space of optimized variables. Compared …


Group Control And Identification Of Residential Appliances Using A Nonintrusive Method, Sunil Semwal, Munendra Singh, Rai Sachindra Prasad Jan 2015

Group Control And Identification Of Residential Appliances Using A Nonintrusive Method, Sunil Semwal, Munendra Singh, Rai Sachindra Prasad

Turkish Journal of Electrical Engineering and Computer Sciences

Identifying and controlling (ON/OFF) electrical appliance(s) from a remote location is an essential part of energy management. This motivated us to design a system that can collect the aggregate load signature from a single point, obtain the features, and finally identify the ON state of electrical appliance(s). The proposed disaggregation technique can be divided into two modules: the first part proposes an electrical installation system to disaggregate the appliance at the circuit level, whereas the second part consists of feature selection, dimension reduction, and classification algorithms. Load signatures of electrical appliances were combined with white Gaussian noise to analyze how …


Model-Reference Sliding Mode Control Of A Three-Phase Four-Leg Voltage Source Inverter For Stand-Alone Distributed Generation Systems, Ayhan Özdemi̇r, İrfan Yazici, Zeki̇ye Erdem Jan 2015

Model-Reference Sliding Mode Control Of A Three-Phase Four-Leg Voltage Source Inverter For Stand-Alone Distributed Generation Systems, Ayhan Özdemi̇r, İrfan Yazici, Zeki̇ye Erdem

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a discrete-time model-reference sliding mode control of three-phase four-leg voltage source inverters for stand-alone distributed generation systems. Three-phase four-leg voltage source inverters (VSIs) are used in a broad area. A discrete-time model-reference sliding mode controller, having superior advantages such as insensitivity to external disturbances, system parameter variations, and modeling errors, is applied to control the output voltage of three-phase four-leg VSIs. As a new study, the discrete-time model-reference sliding mode control with a supplemented output feedback integral controller is proposed so that the controlled output voltages of the VSI tracks the input reference signal. The controller is …


Transient Stability Analysis Of Vsc Hvdc Transmission With Power Injection On The Dc-Link, Agha Francis Nnachi, Josiah Munda, Dan Valentine Nicolae, Augustin Mabwe Mpanda Jan 2015

Transient Stability Analysis Of Vsc Hvdc Transmission With Power Injection On The Dc-Link, Agha Francis Nnachi, Josiah Munda, Dan Valentine Nicolae, Augustin Mabwe Mpanda

Turkish Journal of Electrical Engineering and Computer Sciences

The utilization of a DC-link transmission corridor of embedded VSC HVDC for a DC power injection from renewable energy sources to increase the power flow capability and AC network stability support is a promising technology. However, DC faults on the DC transmission line are likely to threaten the system's operation and stability, especially when the DC power injection exceeds certain limits. A DC single line-to-earth fault is the most likely fault scenario and its effect on the VSC HVDC operation will depend on the earth-loop impedance. Adding an injection point on the DC-link will reduce the earth-loop impedance, hence imposing …


Supercapacitor Energy Storage Based-Upqc To Enhance Ride-Through Capability Of Wind Turbine Generators, Gangatharan Sivasankar, Velu Suresh Kumar Jan 2015

Supercapacitor Energy Storage Based-Upqc To Enhance Ride-Through Capability Of Wind Turbine Generators, Gangatharan Sivasankar, Velu Suresh Kumar

Turkish Journal of Electrical Engineering and Computer Sciences

The recent advancement in electric energy storage technologies provides an opportunity of using energy storage systems to address the issues of grid-integrated wind energy conversion systems. This paper proposes a novel configuration of a unified power quality conditioner (UPQC) with a supercapacitor-based short-term energy storage system for managing wind power intermittency during grid faults. The STATCOM-like compensation device can compensate only current related issues. The dynamic voltage restorer can compensate voltage-related issues but it can contribute only 50{\%} voltage due to converter rating limitations. Moreover, real power handling capabilities of these devices are very poor. This new UPQC scheme can …


An Elegant Emergence Of Optimal Siting And Sizing Of Multiple Distributed Generators Used For Transmission Congestion Relief, Rajamanickam Manickaraj Sasiraja, Velu Suresh Kumar, Sankaralingam Ponmani Jan 2015

An Elegant Emergence Of Optimal Siting And Sizing Of Multiple Distributed Generators Used For Transmission Congestion Relief, Rajamanickam Manickaraj Sasiraja, Velu Suresh Kumar, Sankaralingam Ponmani

Turkish Journal of Electrical Engineering and Computer Sciences

After the implementation of deregulation in a power system, an appreciable volume of renewable energy sources is used to generate electric power. Even though they are intended to improve the reliability of the power system, the unpredictable outages of generators or transmission lines, an impulsive increase in demand, and failures of other equipment lead to congestion in one or more transmission lines. There are several ways to alleviate this transmission congestion, such as the installation of new generation facilities in the place where the demand is high, the addition of a new transmission facility, generation rescheduling, and curtailment of load …


Renewable Energy Integration In Smart Grids-Multicriteria Assessment Using The Fuzzy Analytical Hierarchy Process, Aleksandar Janjic, Suzana Savic, Lazar Velimirovic, Vesna Nikolic Jan 2015

Renewable Energy Integration In Smart Grids-Multicriteria Assessment Using The Fuzzy Analytical Hierarchy Process, Aleksandar Janjic, Suzana Savic, Lazar Velimirovic, Vesna Nikolic

Turkish Journal of Electrical Engineering and Computer Sciences

Unlike the traditional way of efficiency assessment of renewable energy sources integration, the smart grid concept is introducing new goals and objectives regarding increased use of renewable electricity sources, grid security, energy conservation, energy efficiency, and deregulated energy market. Possible benefits brought by renewable sources integration are evaluated by the degree of the approach to the ideal smart grid. In this paper, fuzzy analytical hierarchy process methodology for the integration efficiency has been proposed, taking into account the presence of multiple criteria of both qualitative and quantitative nature, different performance indicators, and the uncertain environment of the smart grid. The …


Stability Preservation And Power Management In Autonomous Microgrids Using Adaptive Nonlinear Droop Scheme, Sara Nourollah, Abolfazl Pirayesh, Poria Astero Jan 2015

Stability Preservation And Power Management In Autonomous Microgrids Using Adaptive Nonlinear Droop Scheme, Sara Nourollah, Abolfazl Pirayesh, Poria Astero

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes sharing active and reactive power in autonomous voltage source inverter (VSI)-based microgrids with no physical communication links. In decentralized VSI-based microgrids, when the demand or generation changes, the output voltage of distributed generation units and the frequency of the system will also change. This study presents a novel adaptive nonlinear droop (ANLD) scheme for preserving network stability, improving the system's dynamics, and controlling power sharing in multibus microgrids in a decentralized manner. Subcontrollers are modeled in a state space and combined together so that a complete dynamic model of the network can be developed. Note that controller …


Performance Analysis Of A Low-Cost Current-Source 1-Ph Grid-Connected Pv Inverter, Gürhan Ertaşgin, Wen Liang Soong, Nesimi Ertugrul Jan 2015

Performance Analysis Of A Low-Cost Current-Source 1-Ph Grid-Connected Pv Inverter, Gürhan Ertaşgin, Wen Liang Soong, Nesimi Ertugrul

Turkish Journal of Electrical Engineering and Computer Sciences

This paper investigates the design and performance of a 150 W single-phase current-source grid-connected inverter topology that is based on a PV array and DC link inductor acting as a constant-current source. The inverter is implemented using a single boost switch, an H-bridge inverter, and a CL output filter. The inverter output current is simply controlled using the boost switch and open-loop or feedforward control. The dark I-V configuration is used to simulate two series PV modules. Comprehensive test results are obtained to validate the computer simulation results. Furthermore, the proposed inverter's ability to deliver a sinusoidal current to the …


High-Speed Separation Of Anechoic Mixtures Of Speech Signals Using Fusion Of Iterative And Closed-Forms Separation Method, Mahdi Mahdikhani, Mohammad Hosein Kahaei Jan 2015

High-Speed Separation Of Anechoic Mixtures Of Speech Signals Using Fusion Of Iterative And Closed-Forms Separation Method, Mahdi Mahdikhani, Mohammad Hosein Kahaei

Turkish Journal of Electrical Engineering and Computer Sciences

We introduce the fusion of iterative and closed-forms separation (FICS) method for high-speed separation of anechoic mixed speech signals. This method is performed in two stages: 1) iterative-form separation and 2) closed-form separation. This algorithm significantly improves the separation quality simply due to incorporating only some specific frequency bins into computations. We apply the FICS method to the frequency-domain independent component analysis (ICA) to evaluate its performance in increasing the signal separation speed for anechoic mixtures. Simulation results show that for speech signals and anechoic conditions, the proposed algorithm is on average 65 times faster than ICA while preserving the …


Speech Emotion Recognition Using Nonlinear Dynamics Features, Ali Shahzadi, Alireza Ahmadyfard, Ali Harimi, Khashayar Yaghmaie Jan 2015

Speech Emotion Recognition Using Nonlinear Dynamics Features, Ali Shahzadi, Alireza Ahmadyfard, Ali Harimi, Khashayar Yaghmaie

Turkish Journal of Electrical Engineering and Computer Sciences

Recent developments in man--machine interaction have motivated researchers to recognize human emotion from speech signals. In this study, we propose using nonlinear dynamics features (NLDs) for emotion recognition. NLDs are extracted from the geometrical properties of the reconstructed phase space of speech signals. The traditional prosodic and spectral features are also used as a benchmark. The Fisher discriminant ratio acts as a filter to remove irrelevant features quickly. Then a wrapper method based on a genetic algorithm and support vector machine is employed to find the best feature subset that obtains the maximum recognition rate. The classification accuracy of the …


A Real-Time American Sign Language Word Recognition System Based On Neural Networks And A Probabilistic Model, Neelesh Sarawate, Ming Chan. Leu, Cemi̇l Öz Jan 2015

A Real-Time American Sign Language Word Recognition System Based On Neural Networks And A Probabilistic Model, Neelesh Sarawate, Ming Chan. Leu, Cemi̇l Öz

Turkish Journal of Electrical Engineering and Computer Sciences

The development of an American Sign Language (ASL) word recognition system based on neural networks and a probabilistic model is presented. We use a CyberGlove and a Flock of Birds motion tracker to extract the gesture data. The finger joint angle data obtained from the sensory glove defines the handshape while the data from the motion tracker describes the trajectory of the hand movement. The four gesture features, namely handshape, hand position, hand orientation, and hand movement, are recognized using different functions that include backpropagation neural networks. The sequence of these features is used to generate a specific sign or …


Comparison Of Clustering Techniques For Traffic Accident Detection, Nejdet Doğru, Abdülhami̇t Subaşi Jan 2015

Comparison Of Clustering Techniques For Traffic Accident Detection, Nejdet Doğru, Abdülhami̇t Subaşi

Turkish Journal of Electrical Engineering and Computer Sciences

Transportation infrastructure in intelligent transportation systems (ITSs) is complemented with information and communication technologies to achieve better passenger safety and reduced transportation time, fuel consumption, and vehicle wear and tear. This paper shows how data mining techniques are used in ITSs for accident detection and prevention on motorways. In traffic, vehicles show similar behavior to that of vehicles in closed neighborhoods. Vehicles that show different behaviors than neighbor vehicles in cases like accidents, inappropriate lane changes, and speeding can be considered as anomalies and detected. In this paper, a traffic accident is simulated and the effectiveness of different clustering techniques …


Central Coordination Relay For Distribution Systems With Distributed Generation, Fati̇h Mehmet Nuroğlu, Ayşen Basa Arsoy Jan 2015

Central Coordination Relay For Distribution Systems With Distributed Generation, Fati̇h Mehmet Nuroğlu, Ayşen Basa Arsoy

Turkish Journal of Electrical Engineering and Computer Sciences

As distributed generation resources penetrate into distribution systems, protection and service continuity are becoming major issues. A new approach for protection coordination and higher reliability of a distribution system with distributed generation is explored in this paper. The concept of central coordination relay (CCR) is developed for this purpose. After a brief introduction of the design and operating procedures of CCR, the utilization of the proposed relay on two feeders of a substation in the Kocaeli region of Turkey is simulated using DIgSILENT PowerFactory. The study results show that CCR can provide better protection coordination and improved reliability indices for …


Analysis And Design Of An Interleaved Current-Fed High Step-Up Quasi-Resonant Dc-Dc Converter For Fuel Cell Applications, Sina Salehi, Behrooz Vahidi, Jafar Milimonfared, Maghdad Taheri, Hadi Moradi Jan 2015

Analysis And Design Of An Interleaved Current-Fed High Step-Up Quasi-Resonant Dc-Dc Converter For Fuel Cell Applications, Sina Salehi, Behrooz Vahidi, Jafar Milimonfared, Maghdad Taheri, Hadi Moradi

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a current-fed quasi-resonant converter with soft switching method. Input current ripple is reduced by employing two boost circuits at the input, which makes this converter appropriate for fuel cell application. Current stress on switches is reduced because of the resonance in switches, and also, as a result of zero voltage switching in switches, switching losses will be reduced in this proposed converter. In the output, the reverse recovery problem of diodes is alleviated by zero current switching, so there is no need for fast diodes anymore. The reduction of losses improves the efficiency, and in a wide …


Impedance Modeling For Classification Of Flavored Green Teas, Munendra Singh, Sunil Semwal, Ashavani Kumar, Shailendra Singh Jan 2015

Impedance Modeling For Classification Of Flavored Green Teas, Munendra Singh, Sunil Semwal, Ashavani Kumar, Shailendra Singh

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes an electrical impedance model of flavored green teas. Typically, impedance data of flavored green teas, obtained by electrochemical impedance spectroscopy (EIS), fit into an equivalent circuit that represents the physical and chemical processes taking place in it. The total impedance of each flavor alone is not sufficient, but different values of impedance parameters in the electrical impedance model are responsible for better classification of flavored green teas. Successfully classified data on the basis of their flavors were obtained by different support vector machine (SVM) techniques with encouraging results. The results show that a linear SVM has better …


Improving The Drain-Current Expression Of Bsim4 For Hot-Carrier Degradation Modeling That Is Suitable For Analog Applications, Gürsel Düzenli̇ Jan 2015

Improving The Drain-Current Expression Of Bsim4 For Hot-Carrier Degradation Modeling That Is Suitable For Analog Applications, Gürsel Düzenli̇

Turkish Journal of Electrical Engineering and Computer Sciences

The reliability evaluation of MOS transistors is one of the most important subjects in device engineering and VLSI design. The down-scaling of device dimensions adversely affects device reliability and lifetime. Although different factors contribute to device reliability and lifetime, the most influential factor is hot-carrier degradation. Furthermore, hot-carrier degradation affects each application uniquely. In analog applications, hot-carrier degradation is more complex and diverse relative to digital applications. In this study, we improve the BSIM4 drain-current model to develop a hot-carrier degradation model that is suitable for both analog and digital applications. Our approach is readily applicable to all process technologies …


A New Method For Segmentation Of Microscopic Images On Activated Sludge, Hali̇me Boztoprak, Yüksel Özbay Jan 2015

A New Method For Segmentation Of Microscopic Images On Activated Sludge, Hali̇me Boztoprak, Yüksel Özbay

Turkish Journal of Electrical Engineering and Computer Sciences

Activated sludge samples were taken from the Konya Wastewater Treatment Plant. Two hundred images for each sample were captured by a systematic examination of the slides. Segmentation of microscopic images is a challenging process due to lack of focus. Therefore, adjustment of the focus is required for every movement of the mobile stage. Because the mobile stage does not have the z axis, the focus cannot be adjusted. A new method that uses automatic segmentation of the captured images is developed for solving this problem. The proposed method is not dependent on image content, has minimal computation complexity, and is …


Ga Based Adaptive Receiver For Mc-Cdma System, Muhammad Adnan Khan, Muhammad Umair, Muhammad Aamer Saleem Choudhry Jan 2015

Ga Based Adaptive Receiver For Mc-Cdma System, Muhammad Adnan Khan, Muhammad Umair, Muhammad Aamer Saleem Choudhry

Turkish Journal of Electrical Engineering and Computer Sciences

Multicarrier systems like the multicarrier code division multiple access (MC-CDMA) systems are designed for maximum usability of available bandwidth. We use the MC-CDMA system with Alamouti's space time coding in this paper. We propose the genetic algorithm (GA) in order to calculate MC-CDMA receiver weights with two variation schemes. The proposed schemes reduce receiver complexity. The bit error rate and convergence rate are also improved by increasing the number of genes and chromosomes of the GA in both schemes as compared with conventional LMS based receivers of the MC-CDMA system. This is verified via simulations.


2d High-Frequency Forward-Looking Sonar Simulator Based On Continuous Surfaces Approach, Hakan Saç, Mehmet Kemal Leblebi̇ci̇oğlu, Gözde Akar Jan 2015

2d High-Frequency Forward-Looking Sonar Simulator Based On Continuous Surfaces Approach, Hakan Saç, Mehmet Kemal Leblebi̇ci̇oğlu, Gözde Akar

Turkish Journal of Electrical Engineering and Computer Sciences

Optical cameras give detailed images in clear waters. However, in dark or turbid waters, information coming from electro-optical sensors is insufficient for accurate scene perception. Imaging sonars, also known as acoustic cameras, can provide enhanced target details in these scenarios. In this paper, a computationally efficient 2D high-frequency, forward-looking sonar image simulator is presented. Stages and requirements of the image formation process are explained in detail. For the postprocessing of the returned sonar signals, a novel computation engine is proposed based on the geometric structures of the simulated surfaces. By treating all the continuous surfaces separately, the simulator is able …


Modified Particle Swarm Optimization For Economic-Emission Load Dispatch Of Power System Operation, Mohd Noor Abdullah, Ab Halim Abu Bakar, Nasrudin Abd Rahim, Hazlie Mokhlis Jan 2015

Modified Particle Swarm Optimization For Economic-Emission Load Dispatch Of Power System Operation, Mohd Noor Abdullah, Ab Halim Abu Bakar, Nasrudin Abd Rahim, Hazlie Mokhlis

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a modified particle swarm optimization considering time-varying acceleration coefficients for the economic-emission load dispatch (EELD) problem. The new adaptive parameter is introduced to update the particle movements through the modification of the velocity equation of the classical particle swarm optimization (PSO) algorithm. The idea is to enhance the performance and robustness of classical PSO. The price penalty factor method is used to transform the multiobjective EELD problem into a single-objective problem. Then the weighted sum method is applied for finding the Pareto front solution. The best compromise solution for this problem is determined based on the fuzzy …


Research On Heat Dissipation And Cooling Optimization Of A Power Converter In Natural Convection, Yang Xu, Hao Chen, Zhentao Hu, Hui Zeng, Qianlong Wang Jan 2015

Research On Heat Dissipation And Cooling Optimization Of A Power Converter In Natural Convection, Yang Xu, Hao Chen, Zhentao Hu, Hui Zeng, Qianlong Wang

Turkish Journal of Electrical Engineering and Computer Sciences

A thermal model for the power converter in a switched reluctance motor drive under natural air cooling is presented. In this compact model, the modeling of the power device is simplified reasonably. Based on the computational fluid dynamics and finite element tools, the thermal and fluid characteristics of the power converter are obtained. The experiment platform is then established, which verifies the correctness of the simulation model. To increase the reliability of the power converter, the layouts of devices on the heat sink and the placement direction of the heat sink are optimized without changing the heat sink shape. Four …


Ethernet-Based Automation Network Systems Mobile Laboratory: A Case Study In Nonlinear Control Of Water Tank System, Levent Ucun, Onur Akbati, Gali̇p Cansever Jan 2015

Ethernet-Based Automation Network Systems Mobile Laboratory: A Case Study In Nonlinear Control Of Water Tank System, Levent Ucun, Onur Akbati, Gali̇p Cansever

Turkish Journal of Electrical Engineering and Computer Sciences

This paper studies an automation network configuration for the concept of a mobile laboratory establishment. The study also covers the design and implementation of a nonlinear controller for the water tank system as a case study. The design and establishment of the mobile laboratory is involved in CoNeT (Cooperative Network Training), a European Union-funded project that aims to design mobile laboratories for different uses in industrial network systems to be used for both application-oriented research and training. In addition to automation network communication and nonlinear controller design, this study also includes Modbus communication analysis and Ethernet traffic monitoring in an …


Homological Dimensions Of Complexes Related To Cotorsion Pairs, Chongqing Wei, Limin Wang, Husheng Qiao Jan 2014

Homological Dimensions Of Complexes Related To Cotorsion Pairs, Chongqing Wei, Limin Wang, Husheng Qiao

Turkish Journal of Mathematics

Let (A, B) be a cotorsion pair in R-Mod. We define and study notions of A dimension and B dimension of unbounded complexes, which is given by means of dg-projective resolution and dg-injective resolution, respectively. As an application, we extend the Gorenstein flat dimension of complexes, which was defined by Iacob. Gorenstein cotorsion, FP-projective, FP-injective, Ding projective, and Ding injective dimension are also extended from modules to complexes. Moreover, we characterize Noetherian rings, von Neumann regular rings, and QF rings by the FP-projective, FP-injective, and Ding projective (injective) dimension of complexes, respectively.


Highly Nonconcurrent Longest Paths And Cycles In Lattices, Yasir Bashir Jan 2014

Highly Nonconcurrent Longest Paths And Cycles In Lattices, Yasir Bashir

Turkish Journal of Mathematics

We investigate here the connected graphs with the property that any pair of vertices are missed by some longest paths (or cycles), embeddable in n-dimensional lattices L^n where L denotes the set of integers.


On Transformations Of Index 1, Leyla Bugay, Osman Kelekci̇ Jan 2014

On Transformations Of Index 1, Leyla Bugay, Osman Kelekci̇

Turkish Journal of Mathematics

The index and the period of an element a of a finite semigroup are defined as the smallest values of m \geq 1 and r \geq 1 such that a^{m+r}=a^m, respectively. If m=1 then a is called an element of index 1. The aim of this paper is to find some properties of the elements of index 1 in T_n, which we call transformations of index 1.


Horizontally Submersions Of Contact Cr-Submanifolds, Fortune Massamba, Tshikunguila Tshikuna-Matamba Jan 2014

Horizontally Submersions Of Contact Cr-Submanifolds, Fortune Massamba, Tshikunguila Tshikuna-Matamba

Turkish Journal of Mathematics

In this paper, we discuss some geometric properties of almost contact metric submersions involving symplectic manifolds. We show that the structures of quasi-K-cosymplectic and quasi-Kenmotsu manifolds are related to (1, 2)-symplectic structures. For horizontally submersions of contact CR-submanifolds of quasi-K-cosymplectic and quasi-Kenmotsu manifolds, we study the principal characteristics and prove that their total spaces are CR-product. Curvature properties between curvatures of quasi-K-cosymplectic and quasi-Kenmotsu manifolds and the base spaces of such submersions are also established. We finally prove that, under a certain condition, the contact CR-submanifold of a quasi Kenmotsu manifold is locally a product of a totally geodesic leaf …


Coloring Hypercomplete And Hyperpath Graphs, Yusuf Ci̇van, Demet Taylan Jan 2014

Coloring Hypercomplete And Hyperpath Graphs, Yusuf Ci̇van, Demet Taylan

Turkish Journal of Mathematics

Given a graph G with an induced subgraph H and a family F of graphs, we introduce a (hyper)graph H_H(G;F)=(V_H, E_H), the hyper-H (hyper)graph of G with respect to F, whose vertices are induced copies of H in G, and \{H_1,H_2,\ldots,H_r\} \in E_H if and only if the induced subgraph of G by the set \cup_{i=1}^r H_i is isomorphic to a graph F in the family F, and the integer r is the least integer for F with this property. When H is a k-complete or a k-path of G, we abbreviate H_{K_k}(G;F) and H_{P_k}(G;F) to H_k(G;F) and HP_k(G;F), respectively. …


Euler-Seidel Matrices Over F_P, Nesri̇n Tutaş Jan 2014

Euler-Seidel Matrices Over F_P, Nesri̇n Tutaş

Turkish Journal of Mathematics

A Euler--Seidel matrix is determined by an infinite sequence whose elements are given by recursion. The recurrence relations are investigated for numbers and polynomials such as hyperharmonics, Lucas numbers, and Euler and Genocchi polynomials. Linear recurring sequences in finite fields are employed, for instance, in coding theory and in several branches of electrical engineering. In this work, we define the period of a Euler--Seidel matrix over a field F_p with p elements, where p is a prime number. We give some results for the matrix whose initial sequence is \{s_r(n)\}_{n=0}^{\infty}, where s_r(n)=\sum_{k=0}^n {\binom{n}{k}}^r, n \geq 0, and r is a …


On Betti Series Of The Universal Modules Of Second Order Derivations Of \Frac{K[X_1,X_2,...,X_S]}{(F)}, Ali̇ Erdoğan, Hali̇se Meli̇s Teki̇n Akçi̇n Jan 2014

On Betti Series Of The Universal Modules Of Second Order Derivations Of \Frac{K[X_1,X_2,...,X_S]}{(F)}, Ali̇ Erdoğan, Hali̇se Meli̇s Teki̇n Akçi̇n

Turkish Journal of Mathematics

Let R be a coordinate ring of an affine irreducible curve represented by \frac{k[x_1,x_2,...,x_s]}{(f)} and m be a maximal ideal of R. In this article, the Betti series of \Omega_2(R_m) is studied. We proved that the Betti series of \Omega_2(R_m), where \Omega_2(R_m) denotes the universal module of second order derivations of R_m, is a rational function under some conditions.