Browsing by Author "Loko, A.Z."

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    Analysis of loss levels in a single mode fiber optic cable for some fiber plants in Northern Nigeria
    (Department of Physics, Nasarawa State University Keffi, 2020-08-25) Dauda, Samson Yusuf; George, Olawale Adedoyin; Umar, Ibrahim; Loko, A.Z.; Lumbi, Lucas Williams
    Increasing demand for transmission capacity due to digital revolution is causing an increasing demand for optical fiber systems. However, as bit-error-rate (BER) increases the fiber optic cable signal quality becomes degraded, causing signal delays, jitters, poor quality of service, packet loss, link outage, etc. In this study, the analysis of loss levels in a single mode fiber optic cable was carried out using the optical time domain reflectometer (OTDR), network monitoring system (NMS) and CACTI (V 1.1.38). Various OTDR traces were carried out to determine the loss levels in the fiber cores. Similarly, using the NMS, the actual link losses were calculated and compared with the loss budget to derive the link loss margin of the links; with a benchmark loss margin of 5 dB, high and low loss levels were determined. Lastly, bandwidth utilization was carried out using network graphical solution software (CACTI, V 1.1.38). The results show that, from the OTDR traces, 60% of the tested fiber cores had high losses at the spliced joints, whereas the analysis of the NMS shows 41.7% high losses. The bandwidth utilization analysis shows a reduction in fiber link availability by 8.3%. This work has revealed the different loss levels in the tested fiber cores with high loses leading to increase in BER which negatively impacts the optimum usability of a link. Therefore, maintaining a low and within-budget loss level is very essential for efficient signal transmission and optimization of the fiber optic cable for both manufacturers and the end users.
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    Assessment of Underground Water Potential in Ninga, Akwanga West Development Area, North Central, Nigeria
    (Department of Physics, Nasarawa State University Keffi, 2022-12-12) Ayanninuola, O.S.; Abdullahi, N.K.; Loko, A.Z.; Isah, S.H.; Ogwola, P.
    Ninga area of Akwanga Development Area, North central Nigeria was investigated for the evaluation of groundwater potential. The area is underlain by the Basement Complex of the North-Central Nigeria. Twelve Vertical Electrical Sounding points were identified in the study area using Omega Resistivity Terameter, GPS12Garmix with cable spread of AB/2=160m. Schlumberger electrode configuration was employed. The Vertical Electrical Sounding (VES) data acquired were interpreted into a model curve using IX1D. From this interpretation three (3) different curve types were obtained from the acquired data. They are QH, QA and H. QH type is the dominant type of the curve obtained. It was observed that the aquifer depth range between 8m-46m, basement resistivity 700 Ωm -3700Ωm, depth to basement 16- 56m, aquifer thickness 4m – 31m and aquifer resistivity 150 Ωm -600Ωm. The groundwater potential varies in the study area, VES 1, 4, 5, 6, 7, 9,10, 11, and 12 are viable locations for groundwater exploration, with true aquifer resistivity values range from 150-600Ωm. Keywords: Aquifer, Basement Complex, Electrical Resistivity, Vertical Electrical Sounding,
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    Comparative Analysis of Savitzky-Golay and Butterworth Filters for Electrocardiogram De- Noising Using Daubechies Wavelets
    (Department of Physics, Nasarawa State University Keffi, 2020-06-19) Dauda, Samson Yusuf; Maduakola, Chinomso Francis; Umar, Ibrahim; Loko, A.Z.; Lumbi, Lucas Williams
    Introduction: Electrocardiogram (ECG) provides a wealth of information and remains an essential part of the assessment of cardiac patients. However, noise distortions associated with the signal could lead to wrong interpretation and diagnosis. Aim: To carry out an extensive comparative analysis of Savitzky-Golay (S-G) and Butterworth filters for ECG de-noising using Daubechies wavelets in a MATLAB version 2015a. Methodology: Noisy ECG signals downloaded from physionet.org under MIT-BIH arrhythmia database were de-noised using S-G and Butterworth filters displayed in both time and frequency domains. A quantitative evaluation was done to assess the performance of the filters for Signal to Noise Ratio (SNR), Mean Square Error (MSE) and Signal to Interference Ratio (SIR). The results of SNR for this work are compared with the results of other researches with other methods. Results: Experimental result for de-noising with Butterworth filter shows abnormal spiky waves in time domain quite unusual in morphology of the original waves and in the frequency domain creates image signals which are indications of noise and baseline drift. While S-G filter maintains the signal power constant and only tries to decrease the noise power with peak preservation. Performance analysis for SNR, MSE and SIR using Butterworth filter gives mean values of 1.63 dB, 0.2036 and 0.259 dB, while that of S-G filter gives 32.78 dB, 0.0001 and 1852.358 dB respectively. Discussion: Significant reduction of noise by S-G filter and retaining the ECG signal morphology effectively as compared to Butterworth filter is an evident that S-G filter delivers better performance results as compared to Butterworth filter in terms of noise separation, artifacts and baseline drifts. Conclusion: The importance of ECG de-noising filters and the criteria for their selection must be clearly understood by hospital managements and cardiac health centers for good quality ECG in diagnosis and therapy for cardiac diseases.
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    DESIGN AND CONSTRUCTION OF A TWO AXIS SOLAR MAXIMUM POWER POINT TRACKING USING PIC16F877A MICRCONTROLLER BASED SYSTEM
    (Department of Physics, Nasarawa State University Keffi, 2016-09-01) Loko, A.Z.; Bugaji, A.I.; Ewa, I.I.; Ibrahim, Umar; Kwaha, B.J.
    Today, most of the streetlights in Nigeria use solar energy to operate; however, streets and road within cities of Nigeria experience street black out as night goes by due to minimum power tracking of sunlight during the day time thereby resulting to low or slow charging of backup systems (battery). Consequently, this research focus on the design and implementation of a maximum power tracking using the PIC16F877A microcontroller and dc motors for two dimensional sun tracking under different temperature, humidity and irradiation and extract maximum available power from photovoltaic (PV) panel that would serve as an alternative solution towards solving the issue of street blackout. This paper also covers the designing and construction of the Solar Tracking mechanical structure together with the associated electronic circuits and two DC motors. One DC motors is mounted to control the rotation part, while the second one is to control the tilting part. Four pairs of Light sensors Cadmium sulphide (CdS) were installed for detecting the light source position. The PIC16F877A is programmed using C language in microC PRO for PIC. The sensor values, temperature of the day are transmitted to the PC for monitoring purpose. A working system was finally demonstrated to validate the design.
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    GEOELECTRIC SOUNDINGS FOR THE DETERMINATION OF AQUIFER CHARACTERISTICS IN ANJAGWA, NASARAWA STATE NIGERIA
    (Department of Physics, Nasarawa State University Keffi, 208-09-28) Ayanninuola, O.S.; Jatau, B.S.; Loko, A.Z.
    A total of fifteen (15) Schlumberger Vertical Electrical Soundings (VES) were carried out in Anjagwa area of Nasarawa State, Nigeria, using a maximum current electrode separation of 500 m. The data were interpreted using a conventional partial curve-matching method to obtain initial model parameters, which were used in a computer program IXID to obtain final parameters. Aquifer parameters of longitudinal conductance and transmissivity were obtained using Dar-Zarouk parameters. The results of interpretation revealed four to five geoelectric layers. High transmissivity values are recorded at VES 3, 4, and 5 with high thicknesses, which imply that thick aquifer materials have higher transmissivity values than areas underlain by relatively thin aquifer materials. Such result is expected because transmissivity is a function of aquifer thickness.
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    Gravitomagnetism, Coupling, Scalar Potential, Vector potential, Riemann’s Laplacian Operator
    (Department of Physics, Nasarawa State University Keffi, 2018-12-10) Lumbi, W.L.; Uchenna, E.T.; Ewa, I.I.; Loko, A.Z.; Ndikilar, Chifu E.
    In this article, the generalized Schwarzschild metric for time varying spherical fields is used to derive equations of motion for test particles in the vicinity of a time varying spherical mass. A generalized gravitational scalar potential is expanded and used to construct equations of motion for test particles exterior to a time varying spherical distribution of mass. The world line element at the equatorial plane of a spherical massive body was constructed. This was used to study the motion of photons. The equations of motion obtained have additional terms not found in equivalent equations in the Schwarzschild’s field. These are uncovered for theoretical and astrophysical development and applications. Remarkably, when the time varying scalar gravitational potential reduces to that of a static field, results obtained in Schwarzschild's field are obtained. Thus, our generalization is mathematically satisfactory and has astrophysical implications for the study of time varying spherical gravitational fields.
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    PROPOSED THERMAL MODEL OF SILICON-ON-INSULATOR (SOI) INTEGRATED CIRCUITS
    (Department of physics, Nasarawa State Univesity Keffi, 2018-10-13) Loko, A.Z.; Anyanninuola, O.S.; Muhammad, S.
    The Silicon-on-insulator (SOI) metal oxide semiconductor field effect transistor (MOSFET) structure with a layer of buried silicon oxide added to isolate the device body and the silicon substrate can significantly cut down source and drain depletion capacitances and can reduce the effect of short channel. Though, the low thermal conductivity of the buried oxide (BOX) can cause local heating, changed electrical properties, altered heat flow down interconnects, and failure of thermal devices. The current thermal models that are presently used in simulation of a circuit to account for thermal effects do not accurately capture the heat flow in the devices. However, accurate models rely on large network circuits or arithmetic simulations which does not execute speedily enough for large scale integrated circuit (LSIC) simulation. The drive of this research work is to advance a method that is efficient balance between accuracy, adaptability and speed and can be used in large scale simulation. The approach will integrate efficient SOI device thermal model and communicate thermal model into integrated circuit (IC) simulation, and will offer accurate, effective and efficient electro-thermal simulation tool for large scale SOI integrated circuit structure.
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    Structural Shielding Evaluation: A Case Study of the Radiography Room of a Rural Hospital in Jos, Nigeria
    (Department of Physics, Nasarawa State University Keffi, 2020-12-12) Dauda, Samson Yusuf; Lumbi, Lucas Williams; Umar, Ibrahim; Loko, A.Z.; Mundi, Abubakar Abdullahi
    Introduction: Most Nigerian rural hospitals constructed before the publication of the 2005 National Council on Radiation Protection and Measurements Report No. 147 did not undergo a performance assessment at the time of construction. To avoid overexposure to ionizing radiation and to ensure adequate protection of patients, workers, and the public, the shielding barriers need to be evaluated to ascertain that they conform to this standard. Methods: This study evaluates the shielding barriers for the general radiography room in a rural hospital in Jos, Nigeria. The workload information, generator voltage waveform, anode material, filtration, and anode angle with XRAYBARR calculation model were used to estimate the thickness of lead, concrete, gypsum, steel, plate glass, and wood required to shield the X-ray facility installed in the hospital. The design dose limit was compared to the estimated shielded dose, and the calculated shielded barrier thickness to the design shielded barrier thickness was also compared. Results: The unshielded radiation doses inside the X-ray room were high, indicating that the radiological department of the study area is not minimizing radiation doses to patients. The calculated doses beyond the barriers were greater than the design dose limit, indicating that the shielded barriers in place were not adequate and did not comply with the international standard. Discussion: Hospitals must understand the type of shielding materials that can provide adequate protection and to what extent they can protect their radiography rooms. Management and radiation protection agencies need to ascertain whether these barriers are still adequate or require reinforcement through regular quality assurance testing. Due to an increase in workload associated with an increase in population and urbanization, proper policies are needed more than ever in this and other rural hospitals in Nigeria. Conclusion: The tested X-ray rooms did not comply with international recommendations for shielding thickness. Except for the door, console, and changing room, a 0.5 mm-thick lead reinforcement is required. It is also recommended that quality assurance testing occur on an annual basis.