Controllability for some nonlinear impulsive partial functional integrodifferential systems with infinite delay in Banach spaces
OMA-Vol. 4 (2020), Issue 2, pp. 104 – 115 Open Access Full-Text PDF
Patrice Ndambomve, Khalil Ezzinbi
Abstract: This work concerns the study of the controllability for some impulsive partial functional integrodifferential equation with infinite delay in Banach spaces. We give sufficient conditions that ensure the controllability of the system by supposing that its undelayed part admits a resolvent operator in the sense of Grimmer, and by making use of the measure of noncompactness and the Mönch fixed-point Theorem. As a result, we obtain a generalization of the work of K. Balachandran and R. Sakthivel (Journal of Mathematical Analysis and Applications, 255, 447-457, (2001)) and a host of important results in the literature, without assuming the compactness of the resolvent operator. An example is given for illustration.
Transient free convection heat and mass transfer of Casson nanofluid over a vertical porous plate subjected to magnetic field and thermal radiation
EASL-Vol. 3 (2020), Issue 4, pp. 35 – 54 Open Access Full-Text PDF
M. G. Sobamowo
Abstract: In this present study, the transient magnetohydrodynamics free convection heat and mass transfer of Casson nanofluid past an isothermal vertical flat plate embedded in a porous media under the influence of thermal radiation is studied. The governing systems of nonlinear partial differential equations of the flow, heat and mass transfer processes are solved using implicit finite difference scheme of Crank-Nicolson type. The numerical solutions are used to carry out parametric studies. The temperature as well as the concentration of the fluid increase as the Casson fluid and radiation parameters as well as Prandtl and Schmidt numbers increase. The increase in the Grashof number, radiation, buoyancy ratio and flow medium porosity parameters causes the velocity of the fluid to increase. However, the Casson fluid parameter, buoyancy ratio parameter, the Hartmann (magnetic field parameter), Schmidt and Prandtl numbers decrease as the velocity of the flow increases. The time to reach the steady state concentration, the transient velocity, Nusselt number and the local skin-friction decrease as the buoyancy ratio parameter and Schmidt number increase. Also, the steady-state temperature and velocity decrease as the buoyancy ratio parameter and Schmidt number increase. Also, the local skin friction, Nusselt and Sherwood numbers decrease as the Schmidt number increases. However, the local Nusselt number increases as the buoyancy ratio parameter increases. It was established that near the leading edge of the plate), the local Nusselt number is not affected by both buoyancy ratio parameter and Schmidt number. It could be stated that the present study will enhance the understanding of transient free convection flow problems under the influence of thermal radiation and mass transfer as applied in various engineering processes.
\(C_6\)-decompositions of the tensor product of complete graphs
ODAM-Vol. 3 (2020), Issue 3, pp. 62 – 65 Open Access Full-Text PDF
Abolape Deborah Akwu, Opeyemi Oyewumi
Abstract: Let \(G\) be a simple and finite graph. A graph is said to be decomposed into subgraphs \(H_1\) and \(H_2\) which is denoted by \(G= H_1 \oplus H_2\), if \(G\) is the edge disjoint union of \(H_1\) and \(H_2\). If \(G= H_1 \oplus H_2 \oplus \cdots \oplus H_k\), where \(H_1\), \(H_2\), …, \(H_k\) are all isomorphic to \(H\), then \(G\) is said to be \(H\)-decomposable. Furthermore, if \(H\) is a cycle of length \(m\) then we say that \(G\) is \(C_m\)-decomposable and this can be written as \(C_m|G\). Where \(G\times H\) denotes the tensor product of graphs \(G\) and \(H\), in this paper, we prove that the necessary conditions for the existence of \(C_6\)-decomposition of \(K_m \times K_n\) are sufficient. Using these conditions it can be shown that every even regular complete multipartite graph \(G\) is \(C_6\)-decomposable if the number of edges of $G$ is divisible by \(6\).
Facile synthesis of Nickel-iron based electrocatalyst anodes for efficient oxygen evolution reaction
OJC-Vol. 3 (2020), Issue 1, pp. 6 – 12 Open Access Full-Text PDF
Aisha Batool, Farah Kanwal, Shahzad Ahmad, Sumreen Asim, Murtaza Saleem
Abstract: In this research, we reported facile synthesis of efficient \(Ni_3Fe\) electrocatalyst nanostructures deposited on conducting carbon fibers surface by a simple chemical bath deposition method at moderate temperature. The composition, phase and electrocatalytic property of as-prepared binder-free electrocatalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and electrochemical measurements. The as-synthesized \(Ni_3Fe@t-CF\) presented excellent performance and durability as water oxidation electrocatalyst in alkaline electrolyte owing to non-segregated deposition of \(Ni_3Fe\) nanostructures on conducting surface of carbon, high electrochemical surface area, and the fast absorption and desorption of water molecules during oxygen evolution reaction due to the \(3D\) architecture of conducting interlaced carbon fibers template.
Chemical composition and Antioxidant activity of essential oil from flowers of Couroupita guianensis Aubl. from El Salvador
OJC-Vol. 3 (2020), Issue 1, pp. 1 – 6 Open Access Full-Text PDF
Francesco Saverio Robustelli della Cuna, Ilaria Bruni, Morena L. Martínez, Marvin J. Núnez
Abstract: Couroupita guianensis Aubl. (Lecythidaceae) “Cannonball tree” is a tropical plant with ethnobotanical uses. The present study is focused on analyzing the essential oil composition of Couroupita guianensis (C. guianensi) fresh flowers collected in El Salvador. Steam distillation, coupled with GC/FID and GC/MS analysis were employed to characterize the chemical composition and in vitro antioxidant activity study were carried out using DPPH assay. Eugenol was identified to be the most abundant constituent and quantified as \(46.20\)% of the total volatiles. Other constituents were found to be \(2\)-phenylethanol \((34.82\)%), \((E)-(E)\)-farnesol \((5.53\)%), nerol \((3.95\)%), geraniol \((3.20\)%), benzyl alcohol \((1.77\)%). \(DPPH\) assay showed a dose-dependent antioxidant activity. The study demonstrated that C. guianensis essential oil from El Salvador is a rich source of eugenol, which may be responsible for its antioxidant properties. Based on these results, further studies on the antibacterial and antifungal activity of C. guianensis essential oil are of fundamental importance.
Truncating the series expansion for unsteady velocity-dependent Eyring-Powell fluid
EASL-Vol. 3 (2020), Issue 4, pp. 28 – 34 Open Access Full-Text PDF
Emran Khoshrouye Ghiasi, Samad Noeiaghdam
Abstract: The main difficulty in dealing with the basic differential equations of fluid momentum is in choosing an appropriate problem-solving methodology. In addition, it is necessary to correct minor errors incurred by neglecting some losses. However, in many cases, such methodologies suffer from long processing time (P-time). Therefore, this article focuses on the truncation technique involving an unsteady Eyring-Powell fluid towards a shrinking wall. The governing differential equations are converted to the non-dimensional from through similarity variables. It is seen that the present system is totally convergent in 8th-order approximate solution together with \(\hbar=-0.875\).
The forgotten index of complement graph operations and its applications of molecular graph
ODAM-Vol. 3 (2020), Issue 3, pp. 53 – 61 Open Access Full-Text PDF
Mohammed Saad Alsharafi, Mahioub Mohammed Shubatah, Abdu Qaid Alameri
Abstract: A topological index of graph \(G\) is a numerical parameter related to graph which characterizes its molecular topology and is usually graph invariant. Topological indices are widely used to determine the correlation between the specific properties of molecules and the biological activity with their configuration in the study of quantitative structure-activity relationships (QSARs). In this paper some basic mathematical operations for the forgotten index of complement graph operations such as join \(\overline {G_1+G_2}\), tensor product \(\overline {G_1 \otimes G_2}\), Cartesian product \(\overline {G_1\times G_2}\), composition \(\overline {G_1\circ G_2}\), strong product \(\overline {G_1\ast G_2}\), disjunction \(\overline {G_1\vee G_2}\) and symmetric difference \(\overline {G_1\oplus G_2}\) will be explained. The results are applied to molecular graph of nanotorus and titania nanotubes.
The rank of Pseudo walk matrices: controllable and recalcitrant pairs
ODAM-Vol. 3 (2020), Issue 3, pp. 41 – 52 Open Access Full-Text PDF
Alexander Farrugia
Abstract: A pseudo walk matrix \(\bf{W}_\bf{v}\) of a graph \(G\) having adjacency matrix \(\bf{A}\) is an \(n\times n\) matrix with columns \(\bf{v},\bf{A}\bf{v},\bf{A}^2\bf{v},\ldots,\bf{A}^{n-1}\bf{v}\) whose Gram matrix has constant skew diagonals, each containing walk enumerations in \(G\). We consider the factorization over \(\mathbb{Q}\) of the minimal polynomial \(m(G,x)\) of \(\bf{A}\). We prove that the rank of \(\bf{W}_\bf{v}\), for any walk vector \(\bf{v}\), is equal to the sum of the degrees of some, or all, of the polynomial factors of \(m(G,x)\). For some adjacency matrix \(\bf{A}\) and a walk vector \(\bf{v}\), the pair \((\bf{A},\bf{v})\) is controllable if \(\bf{W}_\bf{v}\) has full rank. We show that for graphs having an irreducible characteristic polynomial over \(\mathbb{Q}\), the pair \((\bf{A},\bf{v})\) is controllable for any walk vector \(\bf{v}\). We obtain the number of such graphs on up to ten vertices, revealing that they appear to be commonplace. It is also shown that, for all walk vectors \(\bf{v}\), the degree of the minimal polynomial of the largest eigenvalue of \(\bf{A}\) is a lower bound for the rank of \(\bf{W}_\bf{v}\). If the rank of \(\bf{W}_\bf{v}\) attains this lower bound, then \((\bf{A},\bf{v})\) is called a recalcitrant pair. We reveal results on recalcitrant pairs and present a graph having the property that \((\bf{A},\bf{v})\) is neither controllable nor recalcitrant for any walk vector \(\bf{v}\).
Uniformity of dynamic inequalities constituted on time Scales
EASL-Vol. 3 (2020), Issue 4, pp. 19 – 27 Open Access Full-Text PDF
Muhammad Jibril Shahab Sahir
Abstract: In this article, we present extensions of some well-known inequalities such as Young’s inequality and Qi’s inequality on fractional calculus of time scales. To find generalizations of such types of dynamic inequalities, we apply the time scale Riemann-Liouville type fractional integrals. We investigate dynamic inequalities on delta calculus and their symmetric nabla results. The theory of time scales is utilized to combine versions in one comprehensive form. The calculus of time scales unifies and extends some continuous forms and their discrete and quantum inequalities. By applying the calculus of time scales, results can be generated in more general form. This hybrid theory is also extensively practiced on dynamic inequalities.
On divisible and pure multigroups and their properties
OMS-Vol. 4 (2020), Issue 1, pp. 377 – 385 Open Access Full-Text PDF
P. A. Ejegwa, M. A. Ibrahim
Abstract: The theory of multigroups is a generalized group’s theoretic notions in multiset framework. Although myriad of researches have been done in multigroup theory, but some group’s analogue concepts have not been investigated in multigroup setting. In this paper we propose the notions of divisible and pure multigroups and characterize some of their properties. It is established that the image and preimage of homomorphism of divisible and pure multigroups are divisible and pure multigroups. The nexus between divisible and pure multigroups and that of divisible and pure groups are instituted using the concept of cuts of multigroups.