Physics

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Start date: 2020

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Now showing 1 - 5 of 5
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    Development of a Microcontroller Based Heat Index Meter
    (JOST, 2023-04-07) Lawal, Y.B.
    The research focuses on the development of a heat index meter using microcontroller technology. A DHT22 thermo-hygrometer sensor was employed to measure ambient temp and relative humidity simultaneously. The analogue values of these parameters were fed into Arduino Uno Microcontroller which is the heart of the developed meter. The microcontroller has been programmed to compute the heat index using an embedded equation. The microcontroller is interfaced with a 16 by 2 Liquid Crystal Display (LCD) to display the measured temperature, relative humidity as well as the computed heat index. The developed instrument performed satisfactorily during testing and evaluation. It is therefore recommended for measurement and monitoring of heat index.
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    Design and Construction of a Two Channel Microcontroller Based Remote Control for Switching Electrical Appliances
    (ABUAD, 2020-04-14) Mobolaji Aduramo SODUNKE, Adeyemi Idris OLATEJU, Yusuf Babatunde LAWAL, Joseph Ogheneruemu ODIETE, Taiwo Titus ABATAN, Waliu Olayemi MUFUTAU
    This paper presents the design and development of a microcontroller-based system that can switch off and on Electrical appliances or wall sockets at user’s will remotely. This research is aimed at increasing the accessibility as well as response rate to prevent appliances from damage due to transient, intermittent and fluctuations in power supply. This system uses a wireless telemetry technique through an infra-Red (IR) transmitter and receiver to control the switching state of home and laboratory/industrial electrical or electronic devices. The entire circuit is built around ATMEGA-328P microcontroller which was programmed to interpret digital signal sent from the IR transmitter (remote control) to the IR receiver. As the microcontroller receives a real time signal from the IR transmitter through the IR receiver module, a command is sent to the relay switching unit which activates or deactivates the channel(s) based on the software code embedded in the microcontroller. The normally open (N/O) and normally closed (N/C) terminals of the relay are connected to the live terminals of AC sockets for automation. The Liquid Crystal Display (LCD) displays the status of the sockets in any of the two channels (points) as instructed by the microcontroller. The system is cost effective, durable and versatile as it can be applied to any devices connected to electrical socket outlet.
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    DESIGN AND CONSTRUCTION OF A DARK-ACTIVATED EMERGENCY MAINS FAILURE TORCH
    (GVU Science, 2023-08-02) Dada, J. B.1* and Lawal, Y. B.
    This paper presents the design and construction of a dark-activated emergency mains failure (DAEMF) torch mounted on a printed circuit board (PCB). The battery-powered torch called a DAEMF is intended to automatically light up a home and its surroundings in the dark, but it will turn off if it detects the presence of a power source, even if the lighting system is not on. The charging, switching, and lighting sections comprise the three main sections. During the dark period, the switching circuit was switched ON by a voltage of 1.7 volts, and a current of 0.006 mA measured across the light-dependent resistor (LDR) at the switching section. The charging section uses a linear Integrated Circuit (IC) LM 317 as the main electronic component to charge the battery with about 0.65A load current. The high-voltage transformer (HVT) at the lighting unit inverts and converts a 12 Volts direct current (DC) to approximately 100 Volts alternating current (AC) to drive the 6 watts 12 volts fluorescent tube in the lighting section to illuminate the household and its surrounding for 10.5 hours of continuous use
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    Comparative Analysis of Surface Refractivity Variations in the Sahel and Coastal Zones of Nigeria
    (Science Publishing Group, 2023-04-03) Yusuf Babatunde Lawal, Joseph Babatunde Dada
    Variation in Surface Refractivity N is largely influenced by changes in some meteorological parameters such as air temperature, relative humidity, and pressure. These parameters are more accurate when measured locally due to their temporal and spatial variations. The research studies and verifies the contributions of the dry and wet term components of surface radio refractivity. The research focuses on the comparison of surface refractivity variations in two geoclimatic zones of Nigeria. The study reveals that the Sahel and Coastal zones have dissimilar distinct weather conditions and consequently diverse variational pattern of their surface refractivities diurnally and seasonally. The diurnal values of surface refractivity vary moderately on typical sunny days with average values of about 345-391 N-units and 275-314 N-units in the Coastal and Sahel respectively. Wider daily variations were observed during the rainy season in both geoclimatic zones due to frequent rainfalls, especially in the Coastal Stations. The average daily refractivity in the Coastal and Sahel during the rainy seasons are 339-390 and 311-384 N-units respectively. Analysis of the results obtained indicates that the annual mean of the ITU-R recommendation underestimates surface refractivity by 11-15% across the coastal stations and by 5-10% across the Sahel zone. The derived values for each station would be useful for radio engineers in the design and optimization of terrestrial radio links.
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    Analysis of Cross-Polarization Discrimination Due to Rain for Earth–Space Satellite Links Operating at Millimetre-Wave Frequencies in Pretoria, South Africa
    (MDPI, 2025-06-16) Yusuf Babatunde Lawal, Pius Adewale Owolawi and Joseph Sunday Ojo
    This study investigates the impact of rain-induced attenuation on cross polarization discrimination (XPD) in Earth–space satellite links operating at millimeter wave frequencies in Pretoria, South Africa. The traditional method of computing XPD employs a constant annual mean rain height and annual mean co-polar attenuation (CPA) over a certain location. This research utilized seasonal rain height data obtained from a recent study and the latest ITU-R P.618-14 guidelines, to compute and analyze XPD variations across six selected frequencies (11.7 GHz to 35 GHz) for different percentages of time exceedance in Pretoria. The study reveals significant seasonal dependencies of rain heights, with XPD reaching its maximum during winter due to lower rain height, and lower rain-induced attenuation and its minimum during summer, characterized by intense convective rainfall and maximum rain height. FFor instance, the estimated XPD for a 35 GHz signal at 0.01% of the time in the summer, spring, winter, and autumn are 13, 14, 15, and 14 dB, respectively. This implies that radio signals suffer severe attenuation caused by low XPD in the summer. The relationship between CPA and XPD highlights the need for increased XPD margins at higher frequencies to mitigate signal degradation caused by rain depolarization. Practical recommendations include the adoption of adaptive modulation and coding schemes to maintain link reliability during adverse weather conditions, particularly in summer. This research highlights the significance of incorpo-rating frequency-dependent parameters and rain height variability in XPD estimation to enhance the design of satellite communication systems, ensuring optimized performance and reliable operation in a tropical climate.