GEORGE OGUNTALA | University of Bradford (original) (raw)

Papers by GEORGE OGUNTALA

This paper proposes a new technique for wideband transmission and direction-finding using orthogo... more This paper proposes a new technique for wideband transmission and direction-finding using orthogonal frequency division multiplexing (OFDM) for wearable devices in noisy Rician channels. The technique uses a coded OFDM signal combined with a pseudo-random permutation and a Walsh sequence to mitigate inter-carrier interference, peak-to-average power ratio, and frequency offset. The technique also inserts a pilot symbol into each OFDM block and uses it for frequency offset estimation, channel estimation, message detection, and angle of arrival estimation. The technique employs a delay discrimination algorithm to extract the first arriving impulse from each antenna channel and then applies a direction-finding algorithm to estimate the angle of arrival. The technique is evaluated through rigorous simulations using MATLAB. It shows superior performance and reliability compared to existing methods in terms of signal-to-noise ratio, bit error rate, and angle error.

Iet Microwaves Antennas & Propagation, May 19, 2017

In this paper, we present a simple reconfigurable multiband antenna with two PIN diode switches f... more In this paper, we present a simple reconfigurable multiband antenna with two PIN diode switches for WiMAX/WLAN applications. The antenna permits reconfigurable switching in up to ten frequency bands between 2.2 GHz and 6 GHz, with relative impedance bandwidths of around 2.5% and 8%. The proposed antenna has been simulated using CST microwave studio software and fabricated on an FR-4 substrate. It is compact, with an area of 50 × 45 mm 2 , and has a slotted ground substrate. Both measured and simulated return loss characteristics of the optimized antenna show that it satisfies the requirement of 2.4/5.8 GHz WLAN and 3.5 GHz WiMAX antenna applications. Moreover, there is good agreement between the measured and simulated result in terms of radiation pattern and gain.

It has been recognized that artificial intelligence (AI) will play an important role in future so... more It has been recognized that artificial intelligence (AI) will play an important role in future societies. AI has already been incorporated in many industries to improve business processes and automation. Although the aviation industry has successfully implemented flight management systems or autopilot to automate flight operations, it is expected that full embracement of AI remains a challenge. Given the rigorous validation process and the requirements for the highest level of safety standards and risk management, AI needs to prove itself being safe to operate. This paper addresses the safety issues of AI deployment in an aviation network compatible with the Future Communication Infrastructure that utilizes heterogeneous wireless access technologies for communications between the aircraft and the ground networks. It further considers the exploitation of software defined networking (SDN) technologies in the ground network while the adoption of SDN in the airborne network can be optional. Due to the nature of centralized management in SDN-based network, the SDN controller can become a single point of failure or a target for cyber attacks. To countermeasure such attacks, an intrusion detection system utilises AI techniques, more specifically deep neural network (DNN), is considered. However, an adversary can target the AI-based intrusion detection system. This paper examines the impact of AI security attacks on the performance of the DNN algorithm. Poisoning attacks targeting the DSL-KDD datasets which were used to train the DNN algorithm were launched at the intrusion detection system. Results showed that the performance of the DNN algorithm has been significantly degraded in terms of the mean square error, accuracy rate, precision rate and the recall rate.

Fire and Materials, Jun 7, 2021

The paper presents the non-Fourier bioheat transfer prediction methodology of human skin to deter... more The paper presents the non-Fourier bioheat transfer prediction methodology of human skin to determine skin burn injury with non-ideal properties of tissue, metabolism and blood perfusion. The dual-phase lag bioheat transfer model with the inclusion of evaporation is developed for the triple-layer skin tissues. The developed models are solved numerically using Galerkin's finite element method. Parametric studies on the effects of skin tissue properties, initial temperature, blood perfusion rate and heat transfer parameters for the thermal response and exposure time of the layers of the skin tissue are carried out. The results of the investigation are compared with experimental results in the literature. The study demonstrates that the initial tissue temperature, the thermal conductivity of the epidermis and dermis, relaxation and thermalisation time and convective heat transfer coefficient are critical parameters to examine skin burn injury threshold. The study also shows that thermal conductivity and the blood perfusion rate exhibits negligible effects on the burn injury threshold. The objective of the present study is to support the accurate quantification and assessment of skin burn injury for reliable experimentation, design and optimisation of thermal therapy delivery.

The increase in the utilization of high performance equipments has necessitated the use of lamina... more The increase in the utilization of high performance equipments has necessitated the use of laminated beams in aerospace engine, machine structures and electronic devices in order to dampen vibration and reduce noise. In such equipments, two laminates are pressed together and the occurrence of micro interfacial slip between these two laminates helps to effectively dissipate any unwanted vibration or noise. Also, when such structure are subjected to either static or dynamic loading, non-uniformity in interfacial pressure have significant effect on both the energy dissipated and the logarithmic damping decrement associated with the mechanism of slip damping. Thus, laminated beams can be effectively used to increase the level of damping available in such a mechanism. Hence, in this work, with the aid of Finite Difference Method, the effects of laminates on the energy dissipation due to frictional damping between the two laminates are investigated, so also the effects of the material pro...

In this paper, effects of magnet field on the thermal performance of convective-radiative straigh... more In this paper, effects of magnet field on the thermal performance of convective-radiative straight fin with temperature-dependent thermal conductivity using wavelet collocation method. The exact analytical solution is used to analyze the thermal performance, establish the optimum thermal design parameters and also, investigate the effects of thermo-geometric parameters and thermal conductivity (non-linear) parameters on the thermal performance of the fin. The analysis can serve as basis for comparison of any other method of analysis of the problem and they also provide platform for improvement in the design of fin in heat transfer equipment.

Aviation Cybersecurity: Foundations, principles, and applications, 2021

In this work, a parametric analysis on a porous fin heat sink for electronic components operating... more In this work, a parametric analysis on a porous fin heat sink for electronic components operating in a convective-radiative environment is performed using Chebychev spectral collocation method (CSCM). CSCM is used in analysing the developed thermal models. The numerical solution developed is used in investigating the effects of porosity, thermo-geometric and non-linear thermal conductivity variables on the performance of the fin. From the study, it is established that an increase in the convective, radiative and porosity parameters increases the rate of heat dissipated by the fin, which subsequently improves the overall thermal efficiency of the heat sink. The numerical solution of CSCM applied in the present study is validated by the established result of Runge-Kutta method, in which both methods show excellent agreement

Antenna Fundamentals for Legacy Mobile Applications and Beyond, Oct 5, 2017

Defect and Diffusion Forum, 2020

Excess fin length results in material waste and additional weight leading to increased cost with ... more Excess fin length results in material waste and additional weight leading to increased cost with no benefit in return. Moreover, extra fin length affects the overall performance of the fin as fluid motion is suppressed, resulting in reduced convective heat transfer coefficient. To achieve a miniaturised system with effective cooling, the determination of appropriate length of extended surfaces becomes a key performance and fabrication process factor. Therefore, the present work aims at determining the proper or effective length of a convective-radiative moving fin of functionally graded material under the influence of a magnetic field. The developed governing equation of the analysis is solved analytically with the aid of Kummer’s function. The analytical solutions are used to investigate the effects of non-homogeneity, convective, radiative and magnetic parameter on the thermal performance and the proper fin length. The present study is hoped to assist in making cost-effective deci...

ICST Transactions on Mobile Communications and Applications, 2019

5G enabling technologies and applications has been proposed in Multicast or group communication t... more 5G enabling technologies and applications has been proposed in Multicast or group communication to solve the challenge of increasing demand of mobile data traffic. One of the key 5G technologies that would address the increase in mobile traffic is network densification, poses a challenge to group communication. With group communication, several groups are formed into clusters and this technique promises to improve various services in 5G network technology by way of efficient management. As a result, this paper proposes a 5G-enabled software defined multicast networks (5G-SDMNs), where software-defined networking (SDN) is exploited to dynamically manage multicast groups in 5G and mobile multicast environment. Also, mobile edge computing (MEC) is exploited to strengthen network control of 5G-SDMN. The combination of SDN and MEC ensures a flexible, cheap, programmable, and manageable network architecture is proposed for 5G-SDMN. This architecture promises a simplified network management, an improved resource management and a sustainable network development. This article also presents a case study of multicast cloud computing and enumerates the advantages of 5G-SDMN. In the end, open issues in 5G-SDVN are identify and discuss.

International Journal of Applied and Computational Mathematics

Applied and Computational Mechanics, 2017

Due to increasing applications of extended surfaces as passive methods of cooling, study of therm... more Due to increasing applications of extended surfaces as passive methods of cooling, study of thermal behaviors and development of mathematical solutions to nonlinear thermal models of extended surfaces have been the subjects of research in cooling technology over the years. In the thermal analysis of fin, various methods have been applied to solve the nonlinear thermal models. This paper focuses on the application of Legendre wavelet collocation method to the prediction of temperature distribution in longitudinal rectangular fin with temperature-dependent thermal conductivity and internal heat generation. The numerical approximations by the method are used to carry out parametric studies of the effects of the model parameters on the temperature distribution in the fin. The results show that the thermal performance of the fin is favoured at low values of thermogeometric parameter and internal heat generation decreases the performance of the fin. The results can serve as verification o...

The development and production of high performance equipment necessitate the use of passive cooli... more The development and production of high performance equipment necessitate the use of passive cooling technology. In this paper, heat transfer study of convective-radiative straight fin with temperature-dependent thermal conductivity under the influence of magnetic field is carried out using Legendre wavelet collocation method. The numerical solution is used to investigate the effects of magnetic, convective and radiative parameters on the thermal performance of the fin. From the results, it is established that increase in magnetic, convective and radiative parameters increase the rate of heat transfer from the fin and consequently improve the thermal performance of the fin. The results obtained are compared with the results established results in literature and good agreements are found. The analysis can help in enhancing the understanding and analysis of the problem. Also, they can provide platform for improvement in the design of extended surfaces in heat transfer equipment under t...

Loughborough Antennas & Propagation Conference 2018 (LAPC 2018), 2018

This paper presents the design, optimisation and physical implementation of a compact ultra-wideb... more This paper presents the design, optimisation and physical implementation of a compact ultra-wideband (UWB) printed circular monopole antenna (PCMA) for microwave imaging applications, specifically for breast cancer detection. The profile of the proposed antenna features T-Slots etching over a driven circular patch. To achieve the desired impedance bandwidth both in free-space and in proximity to human tissues, the geometrical profiles of the T-slot monopole antenna are optimised using the surrogate model assisted differential evolution for antenna synthesis (SADEA) optimiser. The bandwidth, gain, radiation pattern and efficiency of the optimised antenna are then evaluated. The simulation and measurement results of the antenna's responses are deduced to be in reasonable agreement for the input impedance, gain, radiation pattern and efficiency, respectively, in the operating band of 3.1 GHz to 10.6 GHz. The proposed antenna also gives an adequate radiation in the broad side direction, which contributes significantly to clutter level reduction, and makes the proposed antenna applicable for effective and efficient microwave imaging applications.

Thermal Science and Engineering Progress, 2018

Cooling fins are efficient passive heat transfer devices used to prevent thermal breakdown from v... more Cooling fins are efficient passive heat transfer devices used to prevent thermal breakdown from various heat dissipating components. In this work, the numerical analysis of nonlinear transient thermal response of a convective-radiative cooling fin with convective tip and subjected to magnetic field is presented using finite volume method. An exact solution using Laplace transform is developed for the linear thermal model to verify the numerical solution. Using the numerical solution, the effects of convective tip on the theoretical predictions of the thermal performance of the solid fin are investigated. From the parametric studies, increase in the Biot number, convective, radiative and magnetic variable improves the fin efficiency. The assumption of negligible heat transfer at the fin tip present highly accurate results for short cooling fin operating in a steady state. However, such an assumption should not be used for a long cooling fin of finite length operating in a transient state, especially for a short period of time. The results presented in the paper, hopefully, serves as motivation for the design of thermally-enhanced heatsinks of solid fin under various thermal and fin tip conditions.

Modelling and Simulation in Engineering, 2019

Nonlinear transient thermal analysis of a convective-radiative fin with functionally graded mater... more Nonlinear transient thermal analysis of a convective-radiative fin with functionally graded materials (FGMs) under the influence of magnetic field is presented in this study. The developed nonlinear thermal models of linear, quadratic, and exponential variation of thermal conductivity are solved approximately and analytically using the differential transformation method (DTM). In order to verify the accuracies of the nonlinear solutions, exact analytical solutions are also developed with the aids of Bessel, Legendre, and modified Bessel functions. Good agreements are established between the exact and the approximate analytical solutions. In the parametric studies, effects of heat enhancement capacity of fin with functionally graded material as compared to fin with homogeneous material are investigated. Also, influence of the Lorentz force and radiative heat transfer on the thermal performance of the fin are analyzed. From the results, it is shown that increase in radiative and magne...

2017 13th International Wireless Communications and Mobile Computing Conference (IWCMC), 2017

The growing synergy between engineering applications and medical science has resulted in the deve... more The growing synergy between engineering applications and medical science has resulted in the development of effective health care services and applications responsible for higher quality of living for the world's elderly. The growing numbers of elderly demands more efficient system to monitor patients, especially those with degenerative and chronic diseases constrained to indoor healthcare environments. However, effective monitoring requires constant detection of patients' physical position and orientation, as a large proportion of in-hospital accidental deaths result from delays in responding to the physical needs of frail and elderly patients. In this paper, we propose an unobtrusive hybridized indoor approach using passive RFID sensors, biological pressure sensors, low-resolution infrared detectors and triboelectric motion detectors. The proposed system uses a two-level intelligent framework of location and orientation estimation, providing an efficient and prompt response in any emergency while giving the patients freedom to move around within their healthcare environment.