Effect of soaking sample cubes on concrete compressive strength: The case of Ethiopian Construction Industry
February 2022
Concrete is a major component of construction work composed of fine and coarse aggregates bound together with a cement-water solution paste produced with hydration process. Concrete is best characterized by its compressive strength and relatively low in cost as well as the availability of ingredients that makes it the most favorable component of construction compared to other materials like steel. However, this...
Mantle electrical conductivity determination employing the ionospheric solar quiet day (Sq) currents in the Southern African regions
January 2022
Solar quiet (Sq) daily currents variation obtained in the Hermanus (34.34oS, 19.22oE), Tsumeb (19.24oS, 17.72oE), Hartebeesthoek (25.68oS, 28.09oE) and Maputo (25.97oS, 32.57oE), were employed in determining the mantle electrical conductivity depth profile of the Southern African region. The external and internal contributions in the solar quiet field were separated using the spherical harmonic analysis (SHA), after...
Space-earth coupling with relation to earth’s thermal capacity: A case study for Nsukka Region, Nigeria
January 2022
The radiation coming from the sun to the earth is the only form of incoming radiant energy that determines the heat balance and thermal regime of the earth. Variation of solar radiation is the single most important factor affecting the earth’s surface temperature. This study seeks to investigate the relationship between ambient temperature and soil temperature with a view to determine the existence of space-earth...
Solar activities and geomagnetism: Long-term statistical study of magnetics clouds activity day’s occurrence as a function of the phases of solar cycles 11 to 24
December 2021
This article examines magnetics clouds activity day’s occurrence as a function of the different phases of the solar cycle and the duration of their geoeffectiveness. The study period extends from cycle 11 to cycle 24. Magnetic clouds activity day’s occurrence were identified using pixel diagram from the years 1867 to 2019, that is to say, fourteen (14) solar cycles. The results show that in the study period:...
Theoretical and experimental studies of effective carriers lifetime: Magnetic effects
December 2021
In this manuscript, we present a study on the effects of magnetic field on charge carrier effective lifetime within the base of a polycrystalline PV solar cell p-n junction. This study is elaborated in two forms as a theoretical study and an experimental study. Indeed, under various magnetic field values, PV solar cell is illuminated by using the light from stroboscopic. From a theoretical approach mainly use the open...
Plastics: The good, the bad and the ugly
December 2021
Plastics’ demand and consumption is on the increase since 1950s due to their unique properties. Their high use coupled with challenges in end-of-use handling and their inherent resistance to degradation has led to their accumulation in the environment, which is a matter of grave concern. This review presents a general overview of the state of knowledge of the diverse faces of plastics with special reference to...
High pressure phase stability, elastic anisotropy and electronic properties of BC2N
November 2021
Crystal lattice structure searching by Particle Swarm Optimization (PSO) and first-principles structural optimization have been used to explore polymorphs of BC2N, possessing sp3 hybridization, under a varying applied hydrostatic pressure. Two low Gibbs free energy structures were identified: one with a primitive orthorhombic structure and Space Group, Pmm2, and the other with a primitive tetragonal structure and Space...
Monitoring the loss of mass or the volume recessed into a waveguide by resonant signal principle: Nano-inscribed slots in DUV210 micro-resonators
November 2021
The goal of this paper is to study the impact of a differential mass loss or a lack of material (void) directly located into the core structure of matter together with the possibility of measuring its effect by a resonant signal surface at optical frequencies. To this end, the focus has been on the evolution of effective indices or eigenvalues of micro-resonators as relevant models. Specific lack of mass was measured by...
Total electron content (TEC) seasonal variability under fluctuating activity, from 2000 to 2002, at Niamey station
October 2021
This paper presents the Total Electron Content variability, during the solar cycle 23 maximum under geomagnetic fluctuating activity conditions from 2000 to 2002 at Niamey station (lat. :13°28’N ; long : 2°10’E) in Niger. A comparative study of TEC profiles variation under quiet and fluctuating geomagnetic activity conditions allowed us to analyze the effects of fluctuations in solar wind on...
Performance analysis of the 23 MWp grid connected photovoltaic plant in Diass Senegal
October 2021
This paper presents the performance analysis of a 23 MWp photovoltaic solar power plant installed in Diass, Senegal. The solar photovoltaic power plant is composed of 85608 polycrystalline PV modules and 8 transformer stations (TS). Each TS consists of 4 inverters, several DC BOX and 2 transformers. The environmental and performance data of the plant used in this work were recorded throughout the year 2020. The...
Design, green synthesis and reactions of 2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6 sulfonohydrazide derivatives
October 2021
2,3-Dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonohydrazide and its derivatives were synthesized and characterize by IR, 1H-NMR, 13C-NMR and mass spectrometry analytical methods. The 2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonyl hydrazide (compound 1), was synthesized from the reaction of o-phenylenediamine with oxalic acid to obtain quinoxaline-2,3-dione, which was subjected to chlorosulfonation with chlorosulfonic...
Physical-chemical characterization of kanyu almond oil (Sclerocarya birrea) for use as biofuel
September 2021
Plant oil extracted from Kanyu almonds offers the potential to be an alternative to fossil fuel resources. This study aims to characterize the physico-chemical properties of kanyu almond oil, as safe indicators of the use of this biofuel for energy generators. Samples of the oils examined were density, kinematic viscosity, acid value, and oxidation stability. The experimental results showed that the oils had different...
Thick lenses systems
July 2021
The matrix optics formalism is applied to show that a simple Gaussian equation is enough to relate object and image distances in an optical system consisting of an arbitrary number of thick lenses in cascade immersed in air. First, the case of a single thick lens was studied. Applying sequentially the optical matrixes corresponding to refraction and displacement of the optical ray, and imposing certain conditions on the...
Adsorption and thermodynamic studies of the corrosion inhibition effect of Rosmarinus officinalis L. leaves on aluminium alloy in 0.25 M HCl and effect of an external magnetic field
May 2021
The corrosion inhibition of Aluminium alloy AA8011 in 0.25 M hydrochloric acid solution by Rosmarinus officinalis L. (rosemary) leaves extract was studied using the gravimetric technique at 303, 313, 323 and 333K, and in the presence of an external magnetic field. The study reveals that the methanolic extract of rosemary leaves inhibits corrosion of Al in 0.25 M HCl. The inhibition efficiency was found to increase with...
Evaluation of PV performance prediction model in tropical environment in Senegal
April 2021
Many authors in the literature have worked on models for producing PV module performance, but the question of a climate-specific model is problematic. Some studies have shown more appropriate models for any PV module technology, while others have highlighted models that are more appropriate for a given climate. The aim of this work is to evaluate our model which is based on the I-V characteristic and their accuracy was...
Analysis of wind distribution and potential wind energy in Senegal with a focus on Basse Casamance
April 2021
This work uses the Weibull distribution for assessing the wind potential in Senegal; a country located in West Africa. In this study, data from the ERA5 reanalysis and the Ziguinchor station were used to characterize the spatio-temporal variability of wind and its available power density at 10 m and 100 m of altitude. The results showed that the wind potential was stronger on the coast and the north-western part of the...
Evaluation of the anti-microbial efficiency of scrap metal-based coagulant and local salt modified-biomaterials for point-of-use water treatment
March 2021
The anti-microbial efficiency of a composite material formulated from a scrap metal-based (iron (III) sulphate) coagulant and indigenous salt (NaCl) activated biomaterials (coconut shell carbon and counter wood) were evaluated by using the composite materials as coagulant and disinfectant adsorbent by treating borehole water and river samples at point-of-use. The results of the microbial analysis of the untreated and...
Stability and elastic anisotropy of diamond related C8-yBy materials
February 2021
A number of potentially super-hard materials were examined using ab-initio methods. Low Gibbs free energy polymorphs of diamond-like materials for y = 0 to 7 in the stoichiometric type C8-y By, were identified at absolute zero of temperature. These were proposed as possible super-hard materials with useful applications. The materials with y = 0 to 3, that is, diamond (C), cubic C7B (c-C7B), rhombohedral C3B (r-C3B) and...
Test of velocity-displacement estimation using variometric method under the condition of ionospheric scintillation during equinoctial months of solar maximum period 2012
February 2021
The Global Navigation Satellite System (GNSS) technologies have made significant contribution to seismology studies. Some processing strategies are well known, like real time PPP and DGPS techniques. These two methods have been widely used for GNSS based seismic activities monitoring. The first method requires accurate models of GNSS measurement errors to achieve accuracy in centimeter (cm) and need convergence time in...
Evaluation of simulated rain-based attenuation techniques at k-v frequency bands for satellite services under different modulation techniques over Southwestern Nigeria
January 2021
Rain-based attenuation (RBA) is a major deteriorating factor affecting radio wave signals operating at microwave and millimetre wave bands for a typical Earth-Space Communication Link (ESCL). Although the international telecommunication union (ITU) recommended a standard model for predicting RBA along the terrestrial and ESCL, the technique underperforms in tropical environments. However, the model can be supported by...
Coherent perfect absorption in plasmonic planar metasurface
December 2020
The coherent perfect absorption (CPA) for a planar resonator of silver has been elaborated here in numerical and analytical approaches. It is investigated numerically in different geometrical shapes and spectral regimes. The CPA mode is observed to be spectrally sensitive to the geometry of the resonator. The scattering matrix method is employed in theoretical analysis. The CPA conditions and output irradiance...
Analysis and feasibility of 50 kWp self-consumption solar photovoltaic system for four Senegalese typical climatic zones using PVsyst software
December 2020
This study investigates analysis and feasibility of 50 kWp self-consumption photovoltaic system used for supplying the electrical load of military bases in Senegal. It refers to a simulation of performance photovoltaic system in four Senegalese typical climatic zones. In constructing the 50 kWp self-consumption photovoltaic simulation, the number of modules is 144, the power of each module is 280 Wp, 18 modules are in...
Effects of elevated humidity on stratospheric ozone content in the tropics
October 2020
This study examines the effects of elevated humidity on stratospheric ozone content in the tropics, a case study of Nigeria. The specific stations in Nigeria studied with their co-ordinate include Makurdi (7.7°N 8.5°E), Maiduguri (11.9°N 13.2°E), Kano (12.0°N 8.5°E), Port-Harcourt (4.9°N 7.0°E) and Lagos (6.5°N 3.4°E). Using monthly mean stratospheric ozone data from Earth Probe...
Optical and scanning kelvin probe microscopic characterization of sol-gel synthesized aluminum doped zinc cobalt ferrite nanoparticles
October 2020
In this work, Zn1-xCoFe2AlxO4 (x=0, 0.2, 0.4, 0.6, 0.8 and 1.0) ferrites were synthesized using the sol-gel method. XRD analysis was done and confirmed the formation of spinel structure, where the particle size and lattice parameter decrease with increase of aluminum concentration. This may be attributed to a shift of the bigger Al3+ ions, from the tetrahedral to the octahedral sites, interchanging with smaller Zn2+...
Fof2 prediction with IRI-2016 at Dakar Station during quiet activity over solar cycles 21 and 22
October 2020
This study deals with comparison between Dakar station ionospheric’s F2 layer critical frequency (foF2) data and the two subroutines (CCIR and URSI) of IRI-2016 model predictions. Comparisons are made for very quiet geomagnetic activity during the four phases of the solar cycles 21 and 22 (minimum, increasing, maximum and decreasing). Model's predictions are suitable with observed data by day than by night....
River water lever sensor as river flood warning system
October 2020
Senate Report recorded last 2013 show that tropical storms and floods are the principal disasters with 102 and 72 occurrences, respectively. Distinctly, flood is still one of the biggest problems of the country. Statistics shows that 31.9% of the natural disasters, which occur in the Philippines in the years 1990-2014, are attributed to flood related episodes with a mortality rate of 5.9%. The researchers seek to...
Modification of plastic tank for bio-digestion of food wastes for biogas generation for cooking foods
October 2020
The anaerobic states of the modified bio-digester and potentials of the generated biogas in cooking foods were evaluated. The study adopted experimental design. Data generated were analyzed using one - way analysis of variance and independent t-test. Carbon, free fatty acid, chemical and biochemical oxygen demand decreased significantly (p<0.05) while moisture and protein contents of the wastes increased...
Preparation of MWCNT/Ba0.2Sr0.2La0.6MnO3/PANI nanocomposites and investigation of its electromagnetic properties in KU-band
October 2020
The aim of this study was enhanced the absorption of electromagnetic waves by nanocomposite containing polyaniline (PANI), functionalized multi wall carbon nanotubes (MWCNTs) in the presence of magnetic Ba0.2Sr0.2La0.6MnO3 nanoparticles (NPs). At First MWCNTs was functionalized by 3:1 ratio of sulfuric and nitric acid, then functionalized MWCNTs was coated by NPs with the traditional sol-gel method. In the final step,...
Variations in equatorial electrojet current along the 210ºMM chain: A comparison of two approaches
August 2020
Variations of equatorial electrojet (EEJ) in six Magnetic Data Acquisition System (MAGDAS) stations (four stations within the magnetic equator region and two stations outside the region) on the 210ºMagnetic Meridian (MM) chain were examined. Data of hourly values of horizontal component of magnetic field, H in the year 2007 for Cooktown (CKT), Amami-oh-Shima (AMA), Davao (DAV), Langkawi (LKW), Yap- Island (YAP) and...
Application of integrated geophysical methods in environmental studies: A case study of oil spillage in Thange Area Makueni County, Kenya
August 2020
This research was conducted with the aim of mapping the extent of soil and ground water hydrocarbon contamination from an oil pipeline leak point within the area. An integrated geophysical survey approach involving horizontal electrical profiling (HEP), vertical electrical sounding (VES) and Gravity Survey was applied. Resistivity and gravity lows were identified as aquifer zones confined within basalts and potential...
Simulating ionosphere parameters by thermosphere-ionosphere-electrodynamics general circulation model
July 2020
Ionosphere region is the part of atmosphere layer where radio waves reflect for telecommunication. This is due to its composition in particles. Solar radiation hit particles in ionosphere. This phenomenon causes an ionization of particles in the ionosphere. According to the particles density in this region, radio waves emitted in telecommunication can pass through this region or be reflected. The ionization of...
Thermo-mechanical properties of V-5Cr-5Ti alloy: 3D molecular dynamics simulation
July 2020
This paper presents the results of the study of 3D molecular dynamics simulation to investigate the thermomechanical properties of the V-5Cr-5Ti ternary alloy. The main purpose of this work is to evaluate the quality of the Finnis-Sinclair potential for V-rich V-Cr-Ti random alloys with a body-centered-cubic (bcc) structure. The results demonstrated that the elastic constants of the V-5Cr-5Ti alloy are close to the...
Application of the alternative variational iteration method to solve delay differential equations
July 2020
In this paper, alternative variational iteration method (AVIM) is presented to solve linear and nonlinear delay differential equations (DDEs). A general lagrange multiplier is used to construct a correction functional. The proposed series solutions are found to converge to exact solution rapidly. The computation of three test examples of DDEs was presented to confirm the efficacy and validity of AVIM. The results...
Interpretation of aeromagnetic data over some parts of Sokoto Basin, Nigeria, using source parameter imaging and 3D Euler deconvolution methods
June 2020
This investigation is aimed at determining depth to the bottom of magnetic source and to reveal some certain geological features across Sokoto basin using source parameter imaging and 3D Euler deconvolution techniques. The investigation employed fifteen number aeromagnetic sheets covering longitude 4°30'E - 6°00E and latitude 11°00'N - 13°30'N. The total magnetic intensity of the area was...
Determination and establishment of empirical relationship between magnetic susceptibility and mechanical properties of typical basement rocks in Southwestern Nigeria
June 2020
Magnetic susceptibility and mechanical properties of rocks in a typical basement complex Southwestern Nigeria were correlated with the aim of establishing empirical equations relating the two parameters and evaluate the parameters as related to its competency in hosting civil structures. A total of thirty rock samples were taken across the geology of the area and subjected to mechanical properties determinations....
Influence of natural additives and crushed bricks on the physical and mechanical properties of repair and restoration mortars
May 2020
This study aims to evaluate the influence of different additives, including natural additives such as olive oil and eggs, on repair and restoration mortars. This work enables us to verify the effects of these natural components and their impact on the physical and mechanical characteristics of various types of repair mortars. Four mortar formulations were developed and analysed: Two jointing mortars, including the...
Preparation of thermal neutron absorber based B4C/TiO2/polyaniline nanocomposite
April 2020
B4C nanoparticles (NPs) have been integrated at that point veiled by TiO2 NPs lastly composited by utilizing polyaniline (PANI), (B4C/TiO2/PANI). Shields of thermal neutrons by B4C/TiO2/PANI have been considered, B4C/TiO2/PANI nanocomposite was described by FTIR spectroscopy, and nanometer size, morphology, and structures of tests were estimated by SEM and XRD. The electric property was additionally performed by the...
Solar events and seasonal variation of foF2 at Korhogo station from 1992 to 2002
March 2020
In this paper we report the effect of solar events (CMEs and solar winds) on foF2 diurnal profiles at Korhogo Station (Long 8.427° W; Lat: 9.336° N; dip: -1.88°) from 1992 to 2002. We reviewed on seasons and all the four geomagnetic activity classes (Quiet activity, recurrent activity, Shock activity, and Fluctuating activity). The results show that (1) Coronal Mass Ejections (CMEs) and high-speed solar...
Performance assessment of cross polarization models at millimetre wavelengths along Earth–Space path in Nigeria
March 2020
Rain-induced depolarization impairments have been a constraint on the effective use of satellite communication systems at millimetre wave band especially in the tropical regions like Nigeria. This region often experiences high and varying degree of rainfall intensity accompanied with large raindrops due to distortion of raindrops when dual orthogonal polarization is employed to double the channel capacity without...
Estimation of swelling potential of Enugu Shale using cost effective methods
February 2020
The behavior of swelling soils is mainly governed by its mineralogical composition as well as its environmental factors and stress history. Enugu Shale is one of these shales that assessment of its soil swelling potential cannot only be based on its mineralogical composition alone. The identification of its clay mineral types is basic to understand the roles of other factors of swelling in the soils. The results of...
Assessment of groundwater quality condition at Tarauni dumpsite area, Kano Northwestern Nigeria
January 2020
2-D resistivity imaging and physicochemical analysis were used to investigate the intrusion of leachates on groundwater quality around a dumpsite in Tarauni Local Government Area of Kano State, Nigeria. Four (4) imaging traverse lines were established and Wenner configuration was adopted using an electrode spacing from 5.0, 10.0, 15.0 to 60.0 m. Data collected from the imaging were inverted using AGI EarthImager 2D...
On the slow-time geomagnetic field modulation of cosmic rays
November 2019
In this work, monthly means of cosmic ray count rates from two mid latitude (Hermanus and Rome), and two higher latitude (Inuvik and Oulu) neutron monitors (NM) were employed and their variability was compared with geomagnetic stations that are in close proximity to the NMs. The data spans 1966 to 2008 and covers four solar cycles. The difference (CRdiff) between the mean count rate of all days and the mean of the five...
Assessment of heavy metal pollution in marine sediments receiving produced water, Delta State, Nigeria
October 2019
Every aspect of oil and gas operations poses significant negative impacts on the environment in varying levels, these environmental impacts have economic and public health consequences on the indigenes of the operation locality. Produced water discharge is one of such aspects of the upstream oil and gas operation whose potential for environmental degradation has necessitated both local and international regulations for...
Comparative study of caffeine content in beans and leaves of Coffea arabica using UV/Vis spectrophotometer
October 2019
Caffeine is one of the compounds found in coffee beans and other parts of coffee plant. However, the relative caffeine content in different coffee plant parts is least researched. Therefore, this study was designed to determine the content of caffeine in green coffee leaves and beans. In this work, we report content of caffeine in green coffee beans and leaves of Coffea arabica using UV/Vis spectrophotometer with...
The magnetic moment of elementary particles is studied by space vector and space curvature
September 2019
This paper reaffirms the basic agreement of the material space theory: (1) Space is a physical existence; (2) "Force" is the action to space, and "force" is equal to the reciprocal value of "time"; in the absence of special description, "force" is the reciprocal of time; (3) There is a steady velocity field in three-dimensional space, whose intensity is the speed of light C; (4)...
Gravitational waves as a test of general relativity
August 2019
General relativity has been very successful as a model for space and gravity. It is supported from a range of experimental results. With the advent of the detection of gravitational waves, another platform exists to trumpet its triumph. The merger of black holes has provided evidence in support of the theory of Einstein. Furthermore, the one neutron star merger so far detected provides much more information because of...
Integrated geophysical approach for imaging sedimentary outcrop at Northwestern Peninsular Malaysia
August 2019
An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. In recent years, outcrop studies have become very important to understand the geology of the earth. The lack of studies on outcrops depends on the interpretations and observations at the surface of the earth only. Besides that, lack of specific physical value for the type of materials can cause misinterpretation of...
Seasonal analyses of solar radiation on flat ground for different stat of sky: Case of Nouakchott, Mauritania
August 2019
This paper proposes a method to evaluate solar energy on flat ground for different state of sky (clear sky, moderately covered sky and covered sky). Four semi-empirical models (Link Cloudiness Factor (LCF), Perrin-Brichambaut (PB), Ghouard (GD), Bird Hulstrom (BH)) have been considered to predict solar radiation. An influence analysis of the seasonal variation on the quality of solar energy potential was carried out. In...
Mineralogical and major oxide characterization of Panyam clays, North - Central Nigeria
July 2019
Clay minerals are form over long periods of time, through weathering as a result of gradual chemical breakdown of rocks rich in feldspar. The extent of weathering is determined by many factors. Most common constituent mineral of clays is often one of the members of the mica mineral group. They include illite, sericite, muscovite, and biotite. Others are kaolinite, smectite, mixed-layer clays and chlorite. This paper...
A framework of 5G networks as the foundation for IoTs technology for improved future network
June 2019
The quest for improved communications among objects interconnected in a network has long been awaited. The current fourth generation network (4G) does not enable the range of services the future require, as the fifth-generation network (5G) will be faster and more flexible. The 5G networks and Internet of Things technology seem to be the reality that best describes the basic principles of the future generation mobile...
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