Let H1 and H2 be two Hilbert spaces and Aj : H1 → H2 be bounded linear operators and Ui: H1 → 2H1, Tj : H2 → 2H2, 1 ≤ i ≤ n, 1 ≤ j ≤ r be two multi-valued demi-contractive operators with demi-contractive constants βi and ...

An underlying theorem due to Gauss and Lengendre asserts that for an over determined system, there are solutions that minimize kAx − bk 2 which is given by the generalized in-verse of the matrix A even when A is singular ...

The theory of analytic functions plays a central role in operator theory. It has been a source of methods, examples and problems, and has led to numerous important results. Weighted shifts (which we shall see in the sequel) ...

In recent time, one of the ways of optimizing hydrocarbon production is commingling production from stacked reservoirs. Commingled production refers to the production of hydrocarbon from two or more separate zones through ...

The understanding of the behaviour of vertical upward and downward two-phase flow in large diameter pipes is very important in chemical, petroleum and nuclear sector where safety is of utmost concern. This work helps to ...

Gas hydrate is one of the major plagues of gas wells in the industry, capital costs to prevent hydrate blockage in pipelines is an dissociation temperatures for the operating pressures. The model developed was tested on ...

Nigeria is blessed with mineral resources but unfortunately many have been poorly exploited. This has resulted to spending huge sums of money to import these minerals rather than taking advantage of available local natural ...

The main challenge of heavy oil (bitumen) is the high viscosity making it not flow easily to production wells at normal reservoir conditions. Thermal recovery methods are used to exploit heavy oil reservoirs, where oil ...

In this project, the optimum position of ESP is evaluated for horizontal wells. The inflow and outflow performance of the horizontal well has been estimated using Joshi’s steady-state approximation for horizontal flow and ...

Wellbore instability (WI) is one of the major challenges experienced during drilling operations costing the oil and gas industry over $1 billion yearly. During the drilling, borehole breakout and drilling induced fractures ...

Unconventional resources are of major importance to the oil and gas industry due to its enormousness, however, due to the low permeability of these resources, there is a need for hydraulic fracturing. Hydraulic fracturing ...

More than three decades have passed since Stewart Myers coined the term “real options” and introduced this new paradigm into the investment science. In the following years a number of publications in both the finance and ...

This study aimed at characterizing and evaluating the viability of barite deposits within Ribi for industrial applications. There is an inadequacy of information as regards mineralization, chemical and geotechnical properties ...

The organic-inorganic halide perovskite solar cells have continued to attract serious research interest since the first introduction as solar light absorber by Miyasaka and co-workers with a power conversion efficiency ...

Nigeria ranks among the top ten petroleum producers in the world with over eighty petroleum Investors in its upstream sector. This creates an enormous challenge for the upstream institutions’ managers especially in the ...

Globally, 30–50% of hydrocarbon volumes in silici-clastic reservoirs are contained within the thin-bedded pay. In the Niger Delta deep water assets, over 30% of in-place volumes are found within the complex turbidites. The ...

Wax is often precipitated out of solution in waxy crude oil found in most oil reservoirs around the world, especially as the production of oil and gas has moved from on shore to more challenging terrains offshore. Waxes ...

Although there have been significant efforts in breast cancer treatment over the past many decades, current therapeutic approaches are limited by non-specific systemic distribution, inadequate drug concentrations ...

Due to the growing concern of deforestation, renewable materials such as recycled cellulosic waste and non-wood fibres provide an alternative solution for partial replacement of wood resources as a reinforcement agent in ...

The aim of this dissertation is to contribute to efforts towards increasing the use of Nigerian barites in drilling mud production and other industrial applications. In order to achieve the above objectives, three projects ...