On differences between fractional and integer order differential equations for dynamical games

We argue that fractional order (FO) differential equations are more suitable to model complex adaptive systems (CAS). Hence they are applied in replicator equations for non-cooperative game. Rock-Scissors-Paper game is discussed. It is known that its integer order model does not have a stable equilibrium. Its fractional order model is shown to have a locally asymptotically stable internal solution. A FO asymmetric game is shown to have a locally asymptotically stable internal solution. This is not the case for its integer order counterpart.Comment: 4 page

Numerical and experimental investigations on efficient design and performance of hydrokinetic Banki cross flow turbine for rural areas

Micro hydrokinetic energy scheme presents an attractive, environmentally-friendly and efficient electric generation in rural, remote and hilly areas. However, this scheme is yet to be fully discovered, as researchers are still searching for solutions for the main problems of low velocity of current in the open flow channels and low efficiency of hydrokinetic turbines. This research proposes a novel system configuration to capture as much kinetic energy as possible from stream water current. This system, known as bidirectional diffuser augmented (BDA) channel, functions by utilizing dual directed nozzles in the flow and is surrounded by dual cross flow/Banki turbines. It is also important to obtain the efficient design parameters of the turbines to use in the current configuration. The appropriate angle is important in order to guide the flow to touch the blades more perpendicularly to capture as much torque and power as possible. Hence, experimental and numerical investigations have been carried out in this research paper to study the performance characteristics of the CFT configuration applied in BDA system and investigate the effects of blades’ inlet and outlet angles of CFT runners on the internal flow characteristics and efficiency. In this study, four different runners with various inlet and outlet angles of two CFT have been investigated. The CFD results have been validated with the experimental work and proven acceptable with flow pattern and performance characteristics. The results of the current study conclude that the maximum power coefficients (Cp) of 0.612 and 0.473 for lower and upper turbines are recorded for best runner angles of Case 3

Optimization of EDM process parameters for Al-SiC reinforced metal matrix composite

Volume 8 Issue 2 (February 201

Performance analysis of wells turbine blades using the entropy generation minimization method

Wells turbine concept depends on utilizing the oscillating air column generated over marine waves to drive a turbine. As a matter of fact, previous researches on the performance analysis of such turbine were based on the first law of thermodynamics only. Nonetheless, the actual useful energy loss cannot be completely justified by the first law because it does not distinguish between the quantity and the quality of energy. Therefore, the present work investigates the second law efficiency and entropy generation characteristics around different blades that are used in Wells turbine under oscillating flow conditions. The work is performed by using time-dependent CFD models of different NACA airfoils under sinusoidal flow boundary conditions. Numerical investigations are carried out for the incompressible viscous flow around the blades to obtain the entropy generation due to viscous dissipation. It is found that the value of second law efficiency of the NACA0015 airfoil blade is higher by approximately 1.5% than the second law efficiency of the NACA0012, NACA0020 and NACA0021 airfoils. Furthermore, it is found that the angle of attack radically affects the second law efficiency and such effect is quantified for NACA0015 for angle of attack ranging from -15° to 25°

Flame extinctions: Critical stretch rates and sizes

The paper reports how experimental data from a fan-stirred explosion vessel have extended the boundary of the previously defined regime, within which stable premixed turbulent combustion occurs. It also defines the properties of the bordering regime of turbulent flame quenching. The combustion regime is defined by the normalised turbulent burning velocity, U, the Karlovitz stretch factor, K, and strain rate Markstein number, Masr. The data cover hydrogen, methane, and higher hydrocarbons, at different equivalence ratios and pressures. In contrast, the flame quench regime is defined by the mean diameters of flame kernels at quench, normalised by their laminar flame thickness, dk/δk. These values must be exceeded to initiate a propagating flame. Values of dk/δk increase with both K and Masr. It is also shown, that the flame extinction at blow-off of non-premixed jet flames, is closely related to the observed single kernel quenching of premixed flames. With jet flames, the flow number, U*, has similarities with K. The normalised jet burner diameters, Db/δk, change with U*, in a similar fashion to the way dk/δk changes with K for premixed flames. Finally, the way in which highly turbulent premixed flames can survive extinction by the entrainment of flame gases from a pilot flame is analysed

Effect of antibodies and latently infected cells on HIV dynamics with differential drug efficacy in cocirculating target cells

In this paper, we investigate the qualitative behaviors of three viral infection models with two types of cocirculating target cells. The models take into account both antibodies and latently infected cells. The incidence rate is represented by bilinear, saturation and general function. For the first two models, we have derived two threshold parameters, R0 and R1 which completely determined the global properties of the models. Lyapunov functions are constructed and LaSalle's invariance principle is applied to prove the global asymptotic stability of all equilibria of the models. For the third model, we have established a set of conditions on the general incidence rate function which are sufficient for the global stability of the equilibria of the model. Theoretical results have been checked by numerical simulations.The Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah.http://link.springer.com/journal/108192018-06-30hb2017Electrical, Electronic and Computer Engineerin

Passive flow control for aerodynamic performance enhancement of airfoil with its application in Wells turbine – under oscillating flow condition

In this work, the passive flow control method was applied to improve the performance of symmetrical airfoil section in the stall regime. In addition to the commonly used first law analysis, the present study utilized an entropy generation minimization method to examine the impact of the flow control method on the entropy generation characteristics around the turbine blade. This work is performed using a time-dependent CFD model of isolated NACA airfoil, which refers to the turbine blade, under sinusoidal flow boundary conditions, which emulates the actual operating conditions. Wells turbine is one of the most proper applications that can be applied by passive flow control method because it is subjected to early stall. Additionally, it consists of a number of blades that have a symmetrical airfoil section subject to the wave condition. It is deduced that with the use of passive flow control, torque coefficient of blade increases by more than 40% within stall regime and by more than 17% before the stall happens. A significantly delayed stall is also observed

Antioxidant and cardioprotective activity of Stachys schimperi Vatke against doxorubicin-induced cardiotoxicity

AbstractCardiotoxicity is one of the major side effects of anthracycline antibiotics. Most studies implicated increased oxidative stress as the major determinant of doxorubicin (DOX) cardiotoxicity. The aim of the current investigation was to study the possible cardioprotective effect of Stachys schimperi Vatke (family Lamiaceae) on DOX-induced cardiotoxicity in rats based on biochemical and histopathological parameters. The phenolic profile of the methanol extract was determined qualitatively by HPLC. Isoscutellarein 7-O-[2″-O-(6″′-acetyl)-β-d-allopyranosyl]-β-d-glucopyranoside (compound 1) was isolated and identified from EB fraction as a major constituent for the first time from this Stachys species. The methanolic extract and the combined EtOAc and n-butanol fractions (EB) as well as compound 1 showed prominent free radical scavenging activity when assessed by the DPPH method. The methanolic extract showed moderate protection against DOX-induced alteration in cardiac oxidative stress markers; GSH and MDA, and cardiac serum markers; CK-MB and LDH activities. Additionally, histopathological study denoted mild protection against DOX-induced cardiotoxicity.It was concluded that Stachys schimperi Vatke methanolic extract protected against DOX-induced cardiotoxicity, at least in part, by virtue of its antioxidant activity