T. A. Adagunodo

Monitoring of seepages around dams using geophysical methods: a brief review

The slow escape of a liquid or gas through a porous material or small openings is called seepage. It is a process of seeping in soil engineering whereby water in soils move. nSeepages often pose a grave problem in building foundations and also a common problem in earth dams (Dams are structures built to retain water/fluild) due to abnormal or excessive nleakage. Seepage through or around dams have been responsible for most dam failures. Dam failures are usually catastrophic with many fatalities and causing the destruction of infrastructure and properties. Therefore, monitoring of seepage through and around dams nbecomes a necessity in other to maintain dam’s stability. The main field of application of this investigation is subjected to site characterization and foundation quality assurance. This paper reviews the geophysical techniques which have been considered for the monitoring and control nof seepages around dams

Radiation from Visual Display Unit

The radiation from different types of Visual Display Units (VDU) (that is, Liquid Crystal nDisplay (LCD) and Cathode Ray Tube (CRT)), projector and interactive screen were examined using a nCell Sensor Extremely Low Frequency (ELF) detection meter. The study revealed that ELF radiation in nCRT VDUs is eight (8) times greater than in LCD VDUs. The mean ELF obtained from interactive screen nat 30 cm was 1.6 mG and 1.9 mG at start-up and after 3 hours of use respectively with a mean value of n1.03 mG for a distance of 100 cm at start up. The mean ELF radiation from the projector screen at a ndistance of 10 cm is 0 mG, while that of interactive screen is 2.4 mG at the same distance. Thus, the nstudy suggested that, projector and screen is better than interactive screen when making presentation nconsidering the closeness of user to the interactive screen throughout the course of presentation.

Construction of an in-situ smart device that measures some basic environmental factors for agricultural monitoring

Most of the rural agricultural and extension officers have no access to the daily nvariations in meteorological data that affect the growth and yield of crops. This is as a result of nlittle or no access to the data that could be used to predict the best agricultural practices for noptimum output in the rural environments. In this work, a portable and user friendly smart nAutomated Weather Station (AWS) was constructed. The device that is programmed with nArduino UNO is capable of measuring the temperature, relative humidity and moisture content nof the soil. The performance evaluation of the device was observed in the laboratory and onsite n(Covenant University farm) both on the sunny and rainy days respectively. It was revealed nthat there is positive linear relationship between the volume of water added to the soil sample nand the soil moisture content in the laboratory measurements. The on-site measurements nshowed that the temperature is inversely proportional to the relative humidity and soil moisture ncontent. This device is efficient in taking the short-term essential parameters that could nimprove the yield of agricultural products in the rural environments if properly utilized.

Analysis and comparison of tropospheric scintillation prediction models at Covenant University

Knowledge of tropospheric scintillation is an important phenomenon in the design of nsatellite communication system. One year (January 2015-December 2015) scintillation data nextracted from Astra 2E/2F/2G Satellite link measurement installed at Covenant University, nOta (Lat: 6.7 oN, Long: 3.23 oE) southwest Nigeria, at an elevation angle of 59.9o and a nfrequency of 12.245 GHz was used in this study. The analysis and the result were compared nwith some reputable scintillation prediction models so as to obtain best performance model for nOta region. From the result, it was discovered that the Karasawa model gives the lowest npercentage error rate for both fade and enhancement of about 0.57% at 0.1 percentage of time nand 6.93% at 0.01 percentage of time respectively and therefore was best found fit for the nprediction of propagation impairment for the region. However, the model should be tested nfurther using higher frequency band such as Ka and V bands to confirm the accuracy of the nmodel. The information provided in this study will help in fade margin for antenna sizing and nperformance needed for satellite communication link in the region.

Impact of magnetic activity on occurrence of ionospheric amplitude scintillation over Lagos, Nigeria

With the increasing researches in the understanding of the ionospheric irregularities behaviour near the magnetic equator, an attempt has been made to study the impact of magnetic activity on occurrence of Amplitude Scintillation (S4) over Lagos, Nigeria. The occurrence rate of international quiet (Q) and international disturbed (D) days were examined compared for five days. The occurrences of S4 were recorded during quiet days than the disturbed days in the study area, except in September where there were more S4 during disturbed days than quiet days. Generally, occurrence of S4 was enhanced during pre-midnight hours but was suppressed during post-midnight hour both at quiet and disturbed days in Lagos.