INTRODUCTION Questions about controllability and stability arise in almost every dynamical system problem. As a result, controllability and stability are one of the most extensively studied subjects in system theory. A departure point of control theory is the dierential equation
ABSTRACT In this study, the complex interaction of surface runoff with the biomechanics of soil water transport and heat transfer rate is theoretically investigated using mathematical model that rely on the two phase flows of an incompressible Newtonian fluid (stormwater) within the soil (porous medium) and on the soil surface (runoff). The flow and heat transfer characteristics within the soil are determined numerically based on Darcy-Brinkman-Forchheimer model for porous medium coupled with...
ABSTRACT Chemical method is the most efficient and flexible method of hydrate control in offshore operations. In recent times, polymers and surfactants have been used to influence the kinetics of hydrate growth and coagulation. However, the traditional polar solvents are still relevant because of their ability to melt hydrates. Due to the large volume of polar thermodynamic inhibitors usually required in the field, this work examines the effect of hybrid hydrate inhibitors (HHI) comprising b...
ABSTRACT Density-Functional Theory (DFT) offers a simplification to electronic structure problems by using the electron density instead of the wave-function. Unlike the wavefunction which is a function of 3N variables (excluding spin) for an N-electron system, the density depends only on three variables, irrespective of the number of electrons in the system. While DFT, in principle, gives an accurate description of ground state properties, practical applications of DFT are based on approximat...
ABSTRACT A year-long campaign that accounted for seasonal differences have been conducted to examine the levels, chemical composition and sources of ambient particulate matter in multiple neighbourhoods of varying socioeconomic status in Accra, Ghana. Between September 2007 and August 2008, simultaneous measurements of PM2.5 and PM10 aerosols at five monitoring sites in four neighbourhoods (Asylum Down, East Legon, Nima and James Town/Ussher Town) were done for one 48-hour period every six d...
The cardinal goal to the study of theory of Partial Differential Equations (PDEs) is to insure or find out properties of solutions of PDE that are not directly attainable by direct analytical means. Certain function spaces have certain known properties for which solutions of PDEs can be classified. As a result, this work critically looked into some function spaces and their properties. We consider extensively, L p − spaces, distribution theory and sobolev spaces. The emphasis is made on sob...
ABSTRACT The development of inexpensive, non-toxic, high efficiency and earth-abundant solar absorbers is critical for terawatt scale implementation of photovoltaics. Cu2SnS3 is a promising earth abundant absorber material that is attracting attention recently for optoelectronic application including photovoltaic solar cells. However, very little is known about the relationship between structural and optical properties such as the absorbance, reflectivity, refractive index, extinction coeffic...
ABSTRACT Recent breakthrough in mobile technology, wireless communication and sensing ability of smart devices promote the ease to detect real-world learning status of students as well as the context aware for learning. Targeted information can be provided to individual students in the right place and at the right time. This work is one of the three major modules of our Smart Learning Framework, others include Multimedia Module Contents (MMC) and Learning Style Index (LSI). However, this mod...
Abstract Graphene is an effectively two dimensional form of carbon atoms arranged in honeycomb lattice. Due to its lightweight, high electron mobility and other special electronic properties it is considered both an academically interesting and industrially promising candidate for various electronics applications. Many investigations focused on graphene require theoretical simulations to be performed over a large number of unit cells of graphene. For simulation scenarios where ab-initio meth...
Abstract Fraud, waste, and abuse in many financial systems are estimated to result in significant losses annually. Predictive analytics offer government and private financial institutions the opportunity to identify, prevent or recover such losses. This work proposed a novel Big Data driven approach for fraud detection based on Deep Learning methods. A supervised Deep Learning solution leveraging Big Data was shown to be an effective Fraud predictor. Additionally, an unsupervised method base...
ABSTRACT Since the appearance of the first wind turbines at the end of the nineteenth century, wind energy has been considered to be a renewable energy source for not just developed countries but also developing countries as well. Thus, since 2004, there has been a steady rise in wind energy production worldwide, with substantial actively installed capacity in Africa. However, due to the fact that wind turbines are highly dynamic systems that are excited by stochastic loads from the wind, var...
Abstract We present theoretical results of the study of H2S adsorption on gold cluster Aun(n = 1, 5) using density functional theory with PerdewBurke-Ernzerhof (PBE) exchange-correlation energy functional. Minimum energy structures of the gold cluster along with their isomers are considered in the optimization process. H2S molecule is observed to adsorb on to the gold cluster. However, the adsorption energy decreases with increasing cluster size. The structure of the gold clusters are simila...
Abstract C-DEVS is a formalism for modeling and analysis of discrete event systems. It refers to the original formalism defined by Zeigler in 1976. While the simulation algorithms are well defined, their implementation is a challenge due to both correctness and efficiency issues. This work aims at studying the formalism and its operational semantics. We review and validate the meta-model for SimStudio - a Java implementation of the DEVS simulation protocol, and we debug its existing Java cod...
ABSTRACT Let E be a real normed space with dual space E ∗ and let A : E → 2 E∗ be any map. Let J : E → 2 E∗ be the normalized duality map on E. A new class of mappings, J-pseudocontractive maps, is introduced and the notion of J-fixed points is used to prove that T := (J − A) is J-pseudocontractive if and only if A is monotone. In the case that E is a uniformly convex and uniformly smooth real Banach space with dual E ∗ , T : E → 2 E∗ is a bounded J-pseudocontractive map wi...
ABSTRACT The consumption o f rice is on the increase in Ghana. However, local rice is said not to compare well with imported rice. The need to make local rice more competitive is recognized in the light of the increasing role of quality as an important factor of economic competitiveness. This work was aimed at studying the pre- and postharvest technologies for rice, studying rice handling, management and marketing systems, assessing the performance o f rice mills in Ghana and characterising ...