Department of Electrical and Computer Engineering

To address congestion issues in Opportunistic Networks (OppNets), a modified token-based congestion control with adaptive forwarding mechanism is proposed. The mechanism allows the network nodes holding a valid token to inject message into the network or other neighboring node. At the point of congestion, the algorithm has the potential to redirect the traffic from a more congested node to congestion free node for the purpose of effective resource utilization and fairness in the network. Tokens are evenly distributed throughout the network. Using the opportunistic network environment (ONE) simulator, we illustrate the performance of a modified token-based congestion control algorithm, which results in reduction of dropped messages and network transit time due to congestion across all the scenarios considered. At different queue sizes of (QS-10, QS-20, QS-30 and QS-40), modified token based congestion control algorithm has 13.91%, 10.71%, 5.46%, and 4.22%, respectively, reduction in dropped messages. In addition, at the greatest connected component values of 50%, 60%, 70% and 80%, the modified token-based congestion control has 8.34%, 2.19%, 4.61%, and 7.63%, respectively, decrease in network transit time. These results are substantial, because they indicate a reduction in both network storage and time. ACM CCS (2012) Classification: Networks → Network types → Ad hoc networks → Mobile ad hoc networks Networks → Network properties → Network mobility Networks → Network protocols → Network layer protocols → Routing protocols Networks → Network performance evaluation → Network simulations Networks → Network performance evaluation → Network performance analysis

The aim of the research is the modeling and implementation of an intrusion detection system (IDS) with focus on internally generated intrusions on a multi-Disciplinary campus network using Ahmadu Bello University (ABU) Zaria as a case study. A.B.U Zaria campus network is a complex network covering three campuses, 12 faculties and over a hundred Departments and as such there are varied types of users with diverse application requirements. Traffic data for a period of 24 months (January 2011 to December 2012) comprising of local to local and local to remote were used in developing the knowledge base of the IDS. The overhead of each packet derived from properties and composition of each packet is determined and used to form the behavior base of the IDS. The overhead determined is compared to a threshold called the safe score. This is the maximum allowable overhead for an Ethernet frame and has a value of 0.45. The developed model hybridizes the knowledge –based and behavior-based detection techniques and is implemented as an agent based application (using autonomous and adaptic agents or workers) in a program written in C-sharp(C#). If any packet has an overhead greater than the safe score, it is logged for further analysis. In the validation stage, the model processed 3,422,000 packets and 2328 packets were logged. Using Wireshark for the analysis of the logged packets, 298 packets (13% of the logged packets) were determined not to be malicious but of applications and or protocols not in the original knowledge-base and as such the knowledge base was updated. The IDS model developed is capable of updating its knowledge base, can sniff traffic directly on the network and utilizes less than 15.5% of ROM and CPU capacity at peak traffic period. It also showed about 50% improvement in the number of unknown applications and protocols identified by Netflow analyzer upon implementation.

The objective of this paper was to design an improved U-Slot based 1 X 2 triple band antenna array for Flying Ad-hoc Networks (FANETs). The purpose of this modification is to increase the bandwidth and gain of the existing 1 X 2 triple band antenna array as presented by (Khawaja et al., 2014) and (Bilal et al , 2016). This is because high bandwidth and gain are essential requirement for UAVs in FANET. However, to achieve this, the resonating frequency needed to be selected appropriately. The proposed antenna array resonates at 3.2GHz, 5.1GHz and 6.4GHz frequency band respectively. The antenna is optimized using a U-Slot resonating at triple-bands by introducing two symmetrical slits at the non-radiating edges of the patch. Simulation results were achieved using CST Studio and showed that the antenna has a bandwidth of 313MHz, 51MHz and 167MHz for the three bands respectively. This implies that practical applications can be achieved using this antenna.

Renewable energy technologies has been an area of intensive research and have been experiencing a rapid growth and improvement over the years which have made them attractive to the global energy agencies because of it environmental friendliness and it affordable cost of implementation. In this paper, we presents an improvement of Perturbation and Observation (P&O) Maximum Power Point Tracking (MPPT) algorithms that improves the maximum power point of a Photovoltaic (PV) solar system under fast rapidly changing atmospheric condition. Simulation results shows that the 59.25W of maximum power of photovoltaic array when using normal P&O algorithm was stepped up to 59.70W using improved P&O algorithm with 95% reduction in overshoot. The results were interpreted using MATLAB/Simulink as a means of validation and it is evident that the improved perturbation and observation algorithm recorded an improvement of 0. 50W of maximum power of the photovoltaic array as compared to the normal P & O...

There are several wireless sensor network use for environmental monitoring applications. However, most wireless sensor network designed for real time environmental monitoring application are application specific and static in nature. Hence, the need for reprogramming of base station for every change in sensor type or the introduction of new sensor node into the network. More so, since these sensors nodes are deploy by end users in a random region of interest, it is necessary to develop a new plug and play mechanisms with more software modules and more user-friendly interface that is scalable to ease larger area deployment, installation and maintenance. Hence, this paper developed a base station with an auto detection and configuration system for detecting new sensor node, faulty nodes, and update user in real time. The developed system is implemented on a mesh topology network and was calibrated using standard Davis vantage pro2 weather station in Ahmadu Bello University Liquefied Natural Gas Environmental Laboratory and a mean error of 0.12 and root mean square error of 0.14 were obtained.

This paper addresses poor cluster formation and frequent Cluster Head (CH) failure issues of underwater sensor networks by proposing an energy-efficient hierarchical topology-aware clustering routing (EEHTAC) protocol. In this paper, fault-tolerant backup clustering (FTBC) algorithms and multi-parameter cluster formation (MPCF) model were developed for the EEHTAC operation. The MPCF model tackles the issue of poor cluster formation performance by integrating multiple parameters to achieve effective clustering process. The FTBC algorithms tackle the issue of frequent CH failures to avoid interruption in data transmission. Performance of the MPCF model was evaluated using normal, high-fault, and high routing overhead network scenarios. Performance metrics employed for this analysis are temporal topology variation ratio (TTVR), CH load distribution (CLD), and cluster stability (STB). Obtained results show that operating with a CH retention period of 90s achieves better CH duty cycling ...

This is a technical report written by Mohammed Dahiru Adamu, a pupil engineer working with the Nigerian ports authority as electrical engineer ii. The report is written to be presented to the Council for The Regulation of Engineering in Nigeria as one the organisation’s criteria for engineer’s registration.
The report is written in four chapters, chapter one discusses about the port work procedures, the organizational structure and the lighting technical system in port.
Chapter two presented an x-ray of technical maintenance procedures which includes faults detection, examination and corrections. And ICT support system that aid some aspect of an engineer’s work.
Chapter three is a presentation of an academic research on the analysis of photovoltaic (PV) power generation and utilization. This chapter presented an engineering analysis from conceptualization to installation of the PV system.   
Chapter four is the concluding chapter, hence its presents recommendations.

Pilot Contamination (PC) is considered a major drawback of Time Division Duplexing (TDD) Massive Multiple-Input Multiple-Output (M-MIMO) systems because it limits their expected capacity. A Pilot Allocation Protocol (PAP) scheme is proposed in this letter to mitigate the effect of PC in order to improve the performance of users affected severely by PC. Specifically, the PAP technique is based on sectional pilot sequence initialization and sharing which allocate more than one user to share the same orthogonal pilot sequence within a cell which then creates intra cell interference between the users sharing the same pilot sequence but suppresses inter cell interference between users sharing the same pilot sequence in other cells and mitigate the effect of PC. Simulation results verify the performance gain of the proposed scheme over that of conventional schemes in a typical M-MIMO system.

(ACS) and parallel observations with NICMOS and WFPC2. A square field (1.8$\sq$\deg) has been imaged with single-orbit ACS I-F814W exposures with 50% completeness for sources 0.5\arcsec in diameter at I$_{AB} $ = 26.0 mag. The ACS imaging is a key part of the COSMOS survey, providing very high sensitivity and high resolution (0.09\arcsec FWHM, 0.05\arcsec pixels) imaging and detecting 1.2 million objects to a limiting magnitude of 26.5 (AB). These images yield resolved morphologies for several hundred thousand galaxies. The small HST PSF also provides greatly enhanced sensitivity for weak lensing investigations of the dark matter distribution.

Power law correlations for sediment transport in pressure driven channel flow was derived in the previous work of the authors. Those correlations can be used as predictive tools in the fracturing industry but they are in implicit forms. New data from slot experiments for fractured reservoir were collected which enable us to derive correlations in explicit forms and applicable over a wide range of data. In this paper we present correlations for bed load transport of slurries as a composition of bi-power laws in the proppant and fluid Reynolds number with exponents and prefactors expressed as logarithmic functions of dimensionless sedimentation numbers. The bed load transport correlations are very accurate and are apparently the only such in the published literature.

We present an experimental study on the adsorption behaviour of Intan-100, a nonionic surfactant, at the bitumen/water interface when the density difference between the two phases is increased by diluting the crude oil with 10% Xylene by weight or using heavy water (Deuterium Oxide) as the aqueous phase. Their equilibrium interfacial tension, surface excess and critical micelle concentration of Intan-100, at 30, 60 and 75 °C, are determined using a spinning drop tensiometer, which gives fast and accurate results for low and high values of the tension. Comparison with previous published data indicate that the use of heavy water is to be preferred over dilution of the heavy crude oil when the densities of the two phases are closely matched.

During the last ten years the lattice Boltzmann equation (LBE) method has been developed as an alternative numerical approach in computational fluid dynamics (CFD). Originated from the discrete kinetic theory, the LBE method has emerged with the promise to become a superior modeling platform, both computationally and conceptually, compared to the existing arsenal of the continuum-based CFD methods. The LBE

A modified distributed Lagrange multiplier/fictitious domain method (DLM) that allows particles to undergo collisions is developed for particulate flows. In the earlier versions of the DLM method for Newtonian and viscoelastic liquids the particle surfaces were restricted to be more than one velocity element away from each other. A repulsive body force was applied to the particles when the distance

The flow characteristics of aqueous foams were studied in a thin flow channel and a round pipe instrumented for pressure gradient and flow rate measurements. The quality of the foam was varied by controlling the volumetric flow rate of liquid and gas, and different flow types were identified and charted. Uniform foams move as a rigid body lubricated by water

We give a simple mathematical argument that as the weight of a floating disk is gradually increased, the maximum contact angle at its sharp rim which is attained before the disk sinks is greater than 90 • , and present numerical results which support this conclusion.  2004 Elsevier Inc. All rights reserved.

The instability of circular liquid jet immersed in a coflowing high velocity air stream is studied assuming that the flow of the viscous gas and liquid is irrotational. The basic velocity profiles are uniform and different. The instabilities are driven by Kelvin-Helmholtz instability due to a velocity difference and neckdown due to capillary instability. Capillary instabilities dominate for large Weber numbers. Kelvin-Helmholtz instability dominates for small Weber numbers. The wavelength for the most unstable wave decreases strongly with the Mach number and attains a very small minimum when the Mach number is somewhat larger than one. The peak growth rates are attained for axisymmetric disturbances (n = 0) when the viscosity of the liquid is not too large. The peak growth rates for the first asymmetric mode (n = 1) and the associated wavelength are very close to the n = 0 mode; the peak growth rate for n = 1 modes exceeds n = 0 when the viscosity of the liquid jet is large. The effects of viscosity on the irrotational instabilities are very strong. The analysis predicts that breakup fragments of liquids in high speed air streams may be exceedingly small, especially in the transonic range of Mach numbers.

This paper is concerned with the dispersion of particles on the fluid-liquid interface. In a previous study we have shown that when small particles, e.g., flour, pollen, glass beads, etc., contact an air-liquid interface, they disperse rapidly as if they were in an explosion. The rapid dispersion is due to the fact that the capillary force pulls particles into the interface causing them to accelerate to a large velocity. In this paper we show that motion of particles normal to the interface is inertia dominated; they oscillate vertically about their equilibrium position before coming to rest under viscous drag. This vertical motion of a particle causes a radially-outward lateral (secondary) flow on the interface that causes nearby particles to move away. The dispersion on a liquid-liquid interface, which is the primary focus of this study, was relatively weaker than on an air-liquid interface, and occurred over a longer period of time. When falling through an upper liquid the particles have a slower velocity than when falling through air because the liquid has a greater viscosity. Another difference for the liquid-liquid interface is that the separation of particles begins in the upper liquid before the particles reach the interface. The rate of dispersion depended on the size of the particles, the densities of the particle and liquids, the viscosities of the liquids involved, and the contact angle. For small particles, partial pinning and hysteresis of the three-phase contact line on the surface of the particle during adsorption on liquid-liquid interfaces was also important. The frequency of oscillation of particles about their floating equilibrium increased with decreasing particle size on both air-water and liquid-liquid interfaces, and the time to reach equilibrium decreased with decreasing particle size. These results are in agreement with our analysis.