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Full-Text Articles in Physical Sciences and Mathematics
A Comprehensive Review Of Geometrical Thermodynamics: From Fluctuations To Black Holes, S. Mahmoudi, Kh. Jafarzade, Seyed Hossein Hendi
A Comprehensive Review Of Geometrical Thermodynamics: From Fluctuations To Black Holes, S. Mahmoudi, Kh. Jafarzade, Seyed Hossein Hendi
Turkish Journal of Physics
This paper presents a comprehensive review of geometrical thermodynamics, which employs geometric concepts to study the thermodynamic properties of physical systems. The review covers key topics such as thermodynamic fluctuation theory, proposed thermodynamic metrics in various coordinate systems, and thermodynamic curvature.Additionally, the paper discusses the geometrical approach to black hole thermodynamics and provides an overview of recent research in this field.
The Application Of Brzdek's Fixed Point Theorem In The Stability Problem Of The Drygas Functional Equation, Mehdi Dehghanian, Yamin Sayyari
The Application Of Brzdek's Fixed Point Theorem In The Stability Problem Of The Drygas Functional Equation, Mehdi Dehghanian, Yamin Sayyari
Turkish Journal of Mathematics
Using the Brzdek fixed point theorem, we establish the Hyers?Ulam stability problem of Drygas functional equations \begin{equation} \delta(x+y-z)+\delta(x-y)+\delta(-y-z)+\delta(y)=\delta(x-y-z)+\delta(y-z)+\delta(x+y)+\delta(-y)\nonumber \end{equation} for all $x,y,z\in A$.
Qualitative Study Of A Second Order Difference Equation, Messaoud Berkal, Juan Francisco Navarro
Qualitative Study Of A Second Order Difference Equation, Messaoud Berkal, Juan Francisco Navarro
Turkish Journal of Mathematics
In this paper, we study a second order rational difference equation. We analyze the stability of the unique positive equilibrium of the equation and prove the existence of a Neimark-Sacker bifurcation, validating our theoretical analysis via a numerical exploration of the system.
Some Convergence, Stability, And Data Dependence Results For $K^{\Ast }$ Iterative Method Of Quasi-Strictly Contractive Mappings, Ruken Çeli̇k, Neci̇p Şi̇mşek
Some Convergence, Stability, And Data Dependence Results For $K^{\Ast }$ Iterative Method Of Quasi-Strictly Contractive Mappings, Ruken Çeli̇k, Neci̇p Şi̇mşek
Turkish Journal of Mathematics
In a recent paper, Yu et al. obtained convergence and stability results of the $K^{\ast }$ iterative method for quasi-strictly contractive mappings [An iteration process for a general class of contractive-like operators: Convergence, stability and polynomiography. AIMS Mathematics 2021; 6 (7): 6699-6714.]. To guarantee these convergence and stability results, the authors imposed some strong conditions on parametric control sequences which are used in the $K^{\ast }$ iterative method. The aim of the presented work is twofold: (a) to recapture the aforementioned results without any restrictions imposed on the mentioned parametric control sequences (b) to complete the work of Yu et …
Quercetin Enhances Vitamin D2 Stability And Mitigate The Degradation Influenced By Elevated Temperature And Ph Value, Sukkum Ngullie Chang, Jeong Jun Lee, Hyun Jin Kim, Sun Chul Kang
Quercetin Enhances Vitamin D2 Stability And Mitigate The Degradation Influenced By Elevated Temperature And Ph Value, Sukkum Ngullie Chang, Jeong Jun Lee, Hyun Jin Kim, Sun Chul Kang
Turkish Journal of Chemistry
Vitamin D2 (vit. D2) is a nutraceutical essentially needed for good health. However, it is susceptible to oxygen and high temperature. The use of natural products such as bioflavonoids possessing anti-degradative effect of vit. D2 degradation has not been described before. A combinational effect of vit. D2 with quercetin showed a positive effect and inhibited vit. D2 degradation when exposed to high temperature (50 oC and 75 oC) at different time points. The results obtained revealed vit. D2 degradation was drastically increased with longer incubation under thermal treatment. However, quercetin and vit. D2 groups were able to significantly inhibit the …
Aspect Ratio Dependent Air Stability Of Pbse Nanorods And Photovoltaic Applications, Demet Asi̇l, Tuğba Haciefendi̇oğlu
Aspect Ratio Dependent Air Stability Of Pbse Nanorods And Photovoltaic Applications, Demet Asi̇l, Tuğba Haciefendi̇oğlu
Turkish Journal of Chemistry
Development of unique strategies to overcome Shockley-Queisser (SQ) limit in solar cells has gained a great deal of interest. Multiple exciton generation (MEG) process has been considered as one of the best approaches to the SQ limitation. In this respect, PbSe quantum dots (QDs) and nanorods (NRs) have been regarded as promising solar energy harvesting materials owing to their noticeable MEG yields. Although air stability has been regarded as one of the main disadvantage of PbSe QDs, no study has pointed out to the air sensitivity of PbSe NRs yet. Here, we reveal the effect of aspect ratio on air …
Optimal Siting, Sizing, And Parameter Tuning Of Statcom And Sssc Using Mpso And Remote Coordination Of The Facts For Oscillation Damping Of Power Systems, James Garba Ambafi, Sunusi Sani Adamu
Optimal Siting, Sizing, And Parameter Tuning Of Statcom And Sssc Using Mpso And Remote Coordination Of The Facts For Oscillation Damping Of Power Systems, James Garba Ambafi, Sunusi Sani Adamu
Turkish Journal of Electrical Engineering and Computer Sciences
In electromechanical oscillation damping within power system, power system stabilizers (PSSs) are often deployed. However, a PSS is less effective in damping interarea oscillation and is limited by changes in network configuration due to weak tie-lines and load variations. Consequently, this paper presents a wide-area coordination approach that damps interarea oscillations using FACTS devices and phasor measurement units. We selected a static synchronous compensator (STATCOM) and static series synchronous compensator (SSSC) for realistic power system interarea oscillation damping. The performance of the coordinated FACTS installed in a power system depends on their suitable locations, sizes, tuned parameters, and remote input …
Exponential Stabilization Of A Neutrally Delayed Viscoelastic Timoshenko Beam, Sebti Kerbal, Nasser Eddine Tatar
Exponential Stabilization Of A Neutrally Delayed Viscoelastic Timoshenko Beam, Sebti Kerbal, Nasser Eddine Tatar
Turkish Journal of Mathematics
A Timoshenko type beam subject to a viscoelastic damping in the rotational displacement component is considered. Taking into account a neutral type delay, we prove a fast stability result despite the previously observed destabilizing effect due to delays in such systems. The proof relies on the introduction of nine different functionals with which we modify the energy of the system. These functionals are carefully selected and adapted to cope with both the viscoelasticity and the neutral delay.
Stability Analysis For A Class Of Nabla $(Q,H)$-Fractional Difference Equations, Xiang Liu, Baoguo Jia, Lynn Erbe, Allan Peterson
Stability Analysis For A Class Of Nabla $(Q,H)$-Fractional Difference Equations, Xiang Liu, Baoguo Jia, Lynn Erbe, Allan Peterson
Turkish Journal of Mathematics
This paper investigates stability of the nabla $(q,h)$-fractional difference equations. Asymptotic stability of the special nabla $(q,h)$-fractional difference equations are discussed. Stability theorems for discrete fractional Lyapunov direct method are proved. Furthermore, we give some new lemmas (including important comparison theorems) related to the nabla $(q,h)$-fractional difference operators that allow proving the stability of the nabla $(q,h)$-fractional difference equations, by means of the discrete fractional Lyapunov direct method, using Lyapunov functions. Some examples are given to illustrate these results.
A Circulant Functional Equation For The Additive Function And Its Stability, Vichian Laohakosol, Watcharapon Pimsert, Kanet Ponpetch
A Circulant Functional Equation For The Additive Function And Its Stability, Vichian Laohakosol, Watcharapon Pimsert, Kanet Ponpetch
Turkish Journal of Mathematics
A general solution of a matrix functional equation involving circulant matrices of the additive function is determined, and its stability is established.
An Effective Application Of Differential Quadrature Method Based Onmodified Cubic B-Splines To Numerical Solutions Of The Kdv Equation, Ali̇ Başhan
Turkish Journal of Mathematics
In this study, numerical solutions of the third-order nonlinear Korteweg--de Vries (KdV) equation are obtained via differential quadrature method based on modified cubic B-splines. Five different problems are solved. To show the accuracy of the proposed method, $L_{2}$ and $L_{\infty }$ error norms of the problem, which has an analytical solution, and three lowest invariants are calculated and reported. The obtained solutions are compared with some earlier works. Stability analysis of the present method is also given.
Supercapacitor Utilization For Power Smoothening And Stability Improvement Of Ahybrid Energy System In A Weak Grid Environment, Rahul Sharma, Sathans Suhag
Supercapacitor Utilization For Power Smoothening And Stability Improvement Of Ahybrid Energy System In A Weak Grid Environment, Rahul Sharma, Sathans Suhag
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a novel control scheme based on the application of a supercapacitor (SC) is proposed for power smoothening and stability improvement of a hybrid energy system (HES) in weak grid conditions. The basic property of fast charging/discharging of the SC is utilized to design the proposed control. In weak grid conditions, the control structure is proposed for power smoothening and DC link voltage regulation with the help of the SC. Moreover, the stability is increased, ripples in voltage are reduced, there is fast dynamic response, and oscillations are damped out under different conditions. In conventional control, voltage controller …
Exponential Stability Of Periodic Solutions Of Recurrent Neural Networks With Functional Dependence On Piecewise Constant Argument, Marat Akhmet, Duygu Aruğaslan Çi̇nçi̇n, Nur Cengi̇z
Exponential Stability Of Periodic Solutions Of Recurrent Neural Networks With Functional Dependence On Piecewise Constant Argument, Marat Akhmet, Duygu Aruğaslan Çi̇nçi̇n, Nur Cengi̇z
Turkish Journal of Mathematics
In this study, we develop a model of recurrent neural networks with functional dependence on piecewise constant argument of generalized type. Using the theoretical results obtained for functional differential equations with piecewise constant argument, we investigate conditions for existence and uniqueness of solutions, bounded solutions, and exponential stability of periodic solutions. We provide conditions based on the parameters of the model.
Design And Implementation Of A Modified Communication Disturbance Observer For Teleoperation Systems, Zahra Zeinaly, Amin Ramezani, Sadjaad Ozgoli
Design And Implementation Of A Modified Communication Disturbance Observer For Teleoperation Systems, Zahra Zeinaly, Amin Ramezani, Sadjaad Ozgoli
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a novel structure for a communication disturbance observer in teleoperation systems is proposed to achieve robust stability. A time delay compensation method based on the concept of network disturbance and a communication disturbance observer (CDOB) has been proposed in past research. Unlike model-based approaches, it works without a time delay model. Therefore, it can be implemented in teleoperation systems with unknown and time-varying delay. However, it has been observed that the system model errors and external disturbances seriously affect the steady-state characteristics. Hence, in this paper, to achieve robustness against disturbance and model uncertainty, the structure of …
Concurrent Optimal Design Of Tcsc And Pss Using Symbiotic Organisms Search Algorithm, Muwaffaq Alomoush
Concurrent Optimal Design Of Tcsc And Pss Using Symbiotic Organisms Search Algorithm, Muwaffaq Alomoush
Turkish Journal of Electrical Engineering and Computer Sciences
The symbiotic organisms search (SOS), which has been recently introduced, is a robust powerful metaheuristic global optimizer. This nature-inspired algorithm imitates the symbiotic interaction strategies in an ecosystem exercised by organisms involved in interrelationships to survive and reproduce. One of the main beneficial features of the SOS in contrast to many other competent metaheuristic algorithms is that the algorithm does not need any specific algorithm parameters or tuning process. This paper applies the SOS algorithm to simultaneously design optimal controllers of a power system equipped with both a power system stabilizer (PSS) and a thyristor-controlled series compensator (TCSC). The algorithm …
Temporal Preconditioners For Marching-On-In-Time-Based Time Domain Integral Equation Solvers, Hüseyi̇n Arda Ülkü
Temporal Preconditioners For Marching-On-In-Time-Based Time Domain Integral Equation Solvers, Hüseyi̇n Arda Ülkü
Turkish Journal of Electrical Engineering and Computer Sciences
Temporal preconditioners to stabilize the marching-on-in-time (MOT)-based time domain integral equation (TDIE) solvers are proposed. Exponentially decaying functions are used as temporal preconditioners and the proposed scheme is applied to analyze scattering from perfect electrically conducting objects using the second-order formulation. The effectiveness of the proposed scheme is demonstrated via numerical examples. It is shown that the temporal preconditioners stabilize the MOT system and the solution. In addition, the initial condition problem of TDIEs is investigated by extending the second-order formulation of the time domain electric field integral equation to the time domain magnetic and combined field integral equations.
Stability Of Nonmonotone Critical Traveling Waves Forspatially Discrete Reaction-Diffusion Equations With Time Delay, Ge Tian, Guobao Zhang, Zhao-Xing Yang
Stability Of Nonmonotone Critical Traveling Waves Forspatially Discrete Reaction-Diffusion Equations With Time Delay, Ge Tian, Guobao Zhang, Zhao-Xing Yang
Turkish Journal of Mathematics
This paper is concerned with the existence and stability of critical traveling waves (waves with minimal speed $c=c_*$) for a nonmonotone spatially discrete reaction-diffusion equation with time delay. We first show the existence of critical traveling waves by a limiting argument. Then, using the technical weighted energy method with some new variations, we prove that the critical traveling waves $\phi(x+c_{*}t)$ (monotone or nonmonotone) are time-asymptotically stable when the initial perturbations are small in a certain weighted Sobolev norm.
Stability Analysis Of Nonlinear Fractional Differential Order Systems With Caputo And Riemann--Liouville Derivatives, Javad Alidousti, Reza Khoshsiar Ghaziani, Ali Bayati Eshkaftaki
Stability Analysis Of Nonlinear Fractional Differential Order Systems With Caputo And Riemann--Liouville Derivatives, Javad Alidousti, Reza Khoshsiar Ghaziani, Ali Bayati Eshkaftaki
Turkish Journal of Mathematics
In this paper we establish stability theorems for nonlinear fractional orders systems (FDEs) with Caputo and Riemann--Liouville derivatives. In particular, we derive conditions for $ {\bf \cal{F}}$-stability of nonlinear FDEs. By numerical simulations, we verify numerically our theoretical results on a test example.
Near Optimal Step Size And Momentum In Gradient Descent For Quadratic Functions, Engi̇n Taş, Memmedağa Memmedli̇
Near Optimal Step Size And Momentum In Gradient Descent For Quadratic Functions, Engi̇n Taş, Memmedağa Memmedli̇
Turkish Journal of Mathematics
Many problems in statistical estimation, classification, and regression can be cast as optimization problems. Gradient descent, which is one of the simplest and easy to implement multivariate optimization techniques, lies at the heart of many powerful classes of optimization methods. However, its major disadvantage is the slower rate of convergence with respect to the other more sophisticated algorithms. In order to improve the convergence speed of gradient descent, we simultaneously determine near-optimal scalar step size and momentum factor for gradient descent in a deterministic quadratic bowl from the largest and smallest eigenvalues of the Hessian. The resulting algorithm is demonstrated …
$\Mathcal{Vw}$-Gorenstein Complexes, Renyu Zhao, Wei Ren
$\Mathcal{Vw}$-Gorenstein Complexes, Renyu Zhao, Wei Ren
Turkish Journal of Mathematics
Let $\mathcal{V,W}$ be two classes of modules. In this paper, we introduce and study $\mathcal{VW}$-Gorenstein complexes as a common generalization of $\mathcal{W}$-complexes, Gorenstein projective (resp., Gorenstein injective) complexes, and $G_C$-projective (resp., $G_C$-injective) complexes. It is shown that under certain hypotheses a complex $X$ is $\mathcal{VW}$-Gorenstein if and only if each $X^n$ is a $\mathcal{VW}$-Gorenstein module. This result unifies the corresponding results of the aforementioned complexes. As an application, the stability of $\mathcal{VW}$-Gorenstein complexes is explored.
Stability Assessment Of Isolated Six-Phase Induction Generator Feeding Static Loads, Kiran Singh, Girish Kumar Singh
Stability Assessment Of Isolated Six-Phase Induction Generator Feeding Static Loads, Kiran Singh, Girish Kumar Singh
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents the stability analysis of a six-phase self-excited induction generator (SP-SEIG) based on the eigenvalue stability criteria for its linearized model. This demonstrates the small signal stability behavior during steady-state operating conditions. The eigenvalue approach also establishes an opportunity to correlate eigenvalues with machine parameters. The investigation in this paper reveals that the eigenvalues are dependent upon the machine parameters, and the most critical parameter is the variation in magnetizing inductance (L$_{m})$. The eigenvalues are varied in accordance with the machine variables and give focus to the stabilization of the SP-SEIG. A particular voltage build-up phenomenon is also …
Effect Of Load Increase And Power System Stabilizer On Stability Delay Margin Of A Generator Excitation Control System, Şahi̇n Sönmez, Saffet Ayasun
Effect Of Load Increase And Power System Stabilizer On Stability Delay Margin Of A Generator Excitation Control System, Şahi̇n Sönmez, Saffet Ayasun
Turkish Journal of Electrical Engineering and Computer Sciences
This paper studies the impact of load increase and a power system stabilizer (PSS) on the stability delay margin of a single-machine-infinite-bus system including an automatic voltage regulator. An analytical method is proposed to determine the stability delay margin of the excitation control system. The proposed method first eliminates transcendental terms in the characteristic equation of the excitation system without making any approximation and transforms the transcendental characteristic equation into a regular polynomial. The key result of the elimination process is that the real roots of the new polynomial correspond to the imaginary roots of the transcendental characteristic equation. With …
Structure And Stability Of Primordial Stars, Aysel İbrahi̇m Karafi̇stan
Structure And Stability Of Primordial Stars, Aysel İbrahi̇m Karafi̇stan
Turkish Journal of Physics
For decades large-scale cosmic structures have been modeled as the gravitational amplification of small-density perturbations of the cosmological recombination epoch of the Big Bang. In astrophysics, cosmological nucleosynthesis is considered responsible for the production of the pristine gas, which should be found in the first-generation stars in the form of hydrogen and helium as the main constituents. In the later type of second-generation stars, hydrogen is converted into helium by the CN-cycle reactions, in which heavier elements are produced. These elements are believed to enrich the intergalactic medium by possible star bursts at the last stages of evolution. Stability criteria …
Linear Model Of A Three-Phase Shunt Active Power Filter With A Hysteresis Controller, Kadi̇r Vardar, Eyup Akpinar
Linear Model Of A Three-Phase Shunt Active Power Filter With A Hysteresis Controller, Kadi̇r Vardar, Eyup Akpinar
Turkish Journal of Electrical Engineering and Computer Sciences
In this work, a linear model of a 3-phase active power filter (APF) is obtained to design a DC link proportional--integral (PI) controller. The system is designed on the basis of a TMS320F2812 digital signal processer (DSP). The PI controller is implemented in the program of the DSP. The hysteresis controller and sampling frequency are also taken into account in the linear model. The effect of hysteresis bandwidth, filter inductance, DC link capacitor, and sampling frequency on the stability are investigated by using the Routh--Hurwitz method. The detailed simulation model in MATLAB and experimental results showed that the linear model …
Stability And Data Dependence Results For The Jungck--Khan Iterative Scheme, Abdul Rahim Khan, Fai̇k Gürsoy, Vivek Kumar
Stability And Data Dependence Results For The Jungck--Khan Iterative Scheme, Abdul Rahim Khan, Fai̇k Gürsoy, Vivek Kumar
Turkish Journal of Mathematics
The Jungck--Khan iterative scheme for a pair of nonself operators contains as a special case Jungck--Ishikawa and Jungck--Mann iterative schemes. In this paper, we establish improved results about convergence, stability, and data dependence for the Jungck--Khan iterative scheme.
Analysis And Simulation Of Semiconductor Laser Dynamics With Optoelectronic Delay Feedback, Varghese Bejoy, Sivasankaran Rajesh, Vadakkedath Madhom Nandakumaran
Analysis And Simulation Of Semiconductor Laser Dynamics With Optoelectronic Delay Feedback, Varghese Bejoy, Sivasankaran Rajesh, Vadakkedath Madhom Nandakumaran
Turkish Journal of Physics
In this work we investigate semiconductor laser dynamics with optoelectronic delay feedback, both analytically and numerically. Stability criteria are derived from the delay differential equations of the system. Stability curves are obtained in the feedback strength-delay parameter space. We show that delay has a role in determining the stability only for a range of feedback strength and this range can vary depending on other parameters. Effects of bias current and nonlinear gain reduction on the stability curves are shown in the analysis and numerically verified.
Preparation And Physicochemical Characterizations Of Solid Lipid Nanoparticles Containing Dotap$^®$ For Dna Delivery, Gülay Büyükköroğlu, Emi̇ne Yasemi̇n Yazan, Ayşe Fi̇li̇z Öner
Preparation And Physicochemical Characterizations Of Solid Lipid Nanoparticles Containing Dotap$^®$ For Dna Delivery, Gülay Büyükköroğlu, Emi̇ne Yasemi̇n Yazan, Ayşe Fi̇li̇z Öner
Turkish Journal of Chemistry
The aim of this study was to prepare and evaluate stable cationic solid lipid nanoparticles (SLNs) as colloidal carriers for gene therapy. SLNs were mainly composed of three different biocompatible and biodegradable matrix lipids called tripalmitin, glyceryl dibehenate, and triglyceride, all containing the cationic lipid $N$-(1-(2,3-dioleoyloxy)propyl)-$N,N,N$-trimethylammonium (DOTAP$^®$). Each of these SLNs were divided into three parts and characterized by applying different processes: Part I was autoclaved (121 $^{\circ}$C, 15 min), Part II was lyophilized (5 mbar, --50 $^{\circ}$C), and Part III was kept in its intact form. These parts were stored at 4 $^{\circ}$C, 25 $^{\circ}$C (room temp.), and 40 …
Stability Of Compact Ricci Solitons Under Ricci Flow, Mina Vaghef, Asadollah Razavi
Stability Of Compact Ricci Solitons Under Ricci Flow, Mina Vaghef, Asadollah Razavi
Turkish Journal of Mathematics
In this paper we establish stability results for Ricci solitons under the Ricci flow, i.e. small perturbations of the Ricci soliton result in small variations in the solution under Ricci flow.
Stability Of Perturbed Dynamic System On Time Scales With Initial Time Difference, Coşkun Yakar, Bülent Oğur
Stability Of Perturbed Dynamic System On Time Scales With Initial Time Difference, Coşkun Yakar, Bülent Oğur
Turkish Journal of Mathematics
The behavior of solutions of a perturbed dynamic system with respect to an original unperturbed dynamic system, which have initial time difference, are investigated on arbitrary time scales. Notions of stability, asymptotic stability, and instability with initial time difference are introduced. Sufficient conditions of stability properties are given with the help of Lyapunov-like functions.
Dynamics, Stability, And Actuation Methods For Powered Compass Gait Walkers, Koray Kadi̇r Şafak
Dynamics, Stability, And Actuation Methods For Powered Compass Gait Walkers, Koray Kadi̇r Şafak
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, methods to achieve actively powered walking on level ground using a simple 2-dimensional walking model (compass-gait walker) are explored. The walker consists of 2 massless legs connected at the hip joint, a point mass at the hip, and an infinitesimal point mass at the feet. The walker is actuated either by applying equal joint torques at the hip and ankle, by an impulse applied at the toe off, immediately before the heel strike, or by the combination of both. It is shown that actuating the walker by equal joint torques at the hip and ankle on level …