Browsing by Author "Lumbi, Lucas Williams"

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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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    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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    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.