A Comparison of Beat Frequency Estimation Methods for Large Ring Laser

Autoregressive (AR2) technique has always been used to estimate frequency of the output signal from Large ring laser. However, the acquisition rate is not at near real time which is the requirement and noise level still challenge the process resulting to errors in the final estimation. A research was done to compare the Autoregressive (AR2) with the counterparts such as Pisarenko, Quinn, Hilbert and Phase looking for a better technique that will estimate the frequency at near real time to minimize errors. Secondary data from G and C – II ring laser were used during the comparison between the techniques and Autoregressive (AR2). Results shows that, the output characteristics from the counterpart does not depict the oscillations of the Earth rotation as expected contrast to that of Autoregressive (AR2) which does. Moreover, there were much deviation from the expected true value for the techniques contrast to that of AR2 which is very minimum. On the other hand, when the C – II data were used, it was observed that both techniques resemble on their output characteristics though AR2 was still better in the acquisition rate expect for Hilbert transform which does not resemble with others. Following the scope of this paper, Autoregressive (AR2) technique still emerge as a favorite frequency estimation technique contrast to the four counterparts due to its robustness, high acquisition rate as well as low noise level.

Computational Study for Molecular Properties of Some of the Isolated Chemicals from Leaves Extract of Guiera Senegalensis as Aluminium Corrosion Inhibitor

The present work describes the computational methods for the corrosion inhibition of aluminium using three selected chemical constituents (5-methyldihydroflavasperone, 5-methylflavasperone and methoxylated naphthyl butanone) reportedly obtained from the leaves extract of Guirea senegalensis. Quantum chemical calculations including EHOMO, ELUMO, energy gap (ΔE), electronegativity (χ), global hardness (η) and fraction of electrons transfer from the inhibitor molecule to the aluminium surface (ΔN) were calculated. The local reactive sites through Fukui indices which explain the effect of structural features of these components in relation to electrophilic and nucleophilic point of attack were evaluated. The similarities in quantum chemical parameters for the compounds obtained revealed that the adsorption strengths of the molecules will be mostly determined by molecular size rather than electronic structure parameters. Fukui indices showed that the point of interaction of inhibitor molecule with the Al(l10) surface were through aromatic carbon atom rich in pi-electrons and oxygen atom of the alkanone functional group in the inhibitor molecules. Molecular dynamics simulations describing the adsorption behavior of the inhibitor molecule on Al(110) surface through Forcite quench molecular dynamics were carried out. The compounds were found to all obey the mechanism of physical adsorption because of their relatively low adsorption energies.

Adsorption of Aqueous Using Granular Adsorbents from Accanthospermum hispendum DC

Granular activated carbons have been important adsorbents for the decontamination of aqueous environmental contaminants. Acanthospermum hispidum weed represents a ready available source of low-cost adsorbents in sub-Saharan Africa that has barely been paid attention. The effects of pH, contact time, concentration, adsorbent dosage, particle size and temperature on the adsorptive removal of Pb (II) from aqueous solutions over activated carbon granules from the thorns of Accanthospermum hispindum (AC-T) were for the first time investigated and compared with those of the leaves (L), the sodium hydroxide modified thorns (NaOH-T) and regular thorns (T) of this plant. These adsorbents were characterised by the surface charge analysis, scanning electron microscopy (SEM) and the Attenuated Total Reflectance Fourier Transform infrared (ATR FTIR) spectroscopy. The SEM revealed a wafer-like appearance for the AC-T with a large distribution of open pores. The adsorption data of lead uptake onto the adsorbents were examined using two pseudo-order kinetic schemes and three isotherm models. To fully understand the adsorption capacities of the adsorbents, batch desorption recoveries were studied. The FTIR depicted the various functionalities responsible for the adsorption. Adsorption over AC-T was found to agree with pseudo second-order kinetic scheme, the Langmuir and Freundlich isotherm. This material exhibited the highest adsorption capacity. The order of reusability of the adsorbents is T < AC-T < NaOH-T.

Effects of an Acute Bout of Exercise on Salivary Lactoferrin Responses among Smokers and Non-Smokers

Smoking can weaken immune function as reported in previous studies. However, benefits of exercise in reducing negative effects of smoking on salivary lactoferrin responses is scarce to date. Hence, the purpose of this study is to determine the effects of an acute bout of exercise on salivary lactoferrin responses among smokers and non-smokers. Eighteen sedentary men were recruited; nine smokers (age = 22.4 ± 1.4 years; BMI = 22.1 ± 1.1 kg/m2) and nine non-smokers (age = 22.1 ± 0.7 years old; BMI = 22.5 ± 1.9 kg/m2). In this study, participants cycled at an intensity of 60% maximum heart rate for 60 minutes. Participants were given cool water as much as 3 ml/kg body weight at minutes 20 and 40 during the exercise session. Participants’ body weight and saliva samples were collected at pre and post-exercise. Heart rate and rate of perceived exertion (RPE) were recorded at pre, during and post-exercise. Mixed ANOVA was used to measure significant differences between groups and within group. The results showed that saliva flow rate, lactoferrin concentration and lactoferrin secretion rate were not significantly different (p>0.05) between smokers and non-smokers groups and also between pre and post-exercise within each group. Heart rate and RPE showed significant increased (p<0.05) during the exercise session in both groups. As a conclusion, acute bout of exercised does not affect salivary lactoferrin responses among sedentary smokers and non-smokers men.

Effect of Hydrostatic Pressure and Temperature on Quantum Confinement of AlGaN/GaN HEMTs

In this paper, an analytical model for quantum confinement electron density in two-dimensional quantum well, has been investigated. In order to obtain the exact AlGaN/GaN HEMTs parameters such as electron density, the wave function, band gap, polarization charge, effective mass and dielectric constant, the hydrostatic pressure and temperature effects are taken into account. It has been found that the electron density decreases with increasing temperature and increases with increasing hydrostatic pressure. With increasing hydrostatic pressure, the effective mass decreases and the quantum confinement electrons are increased in the quantum well. Also with increasing hydrostatic pressure, the height of wave functions increase and decreases electron wave functions to penetrate the quantum barrier but increasing the temperature behaves the opposite of increasing the pressure. However, with increasing temperature, the effective mass is increased and the quantum confinement electrons are reduced. The calculated results for electron density are in good agreement with existing experimental data.

Strategies for Engendering Health and Safety Culture in Construction Firms in Abuja, Nigeria

Many countries have put in place policies and legislation to reduce accidents and diseases on construction sites though having varied degree of comprehensiveness, the extent of implementation, will and capacity of enforcement. In spite of these efforts, it has been revealed that the increase in the rate of unsafe acts and rate of fatalities in the construction industry is significant due to poor safety culture. Hence, this study assessed the level of health and safety (H&S) culture in construction firms in Abuja by self-administering a total of 152 questionnaires on H&S issues to construction professionals. It included Builders, Quantity Surveyors, Architects, Civil Engineers, and Project Managers/supervisors who were involved in construction works. The data obtained were analysed using percentages and mean scores. It was discovered that despite the increasing growth in the construction firms in Nigeria, the H&S culture practice in construction firms is highly fragmented and poorly implemented. It is recommended among others that there should be high commitment from the top of organisations which will in turn produce higher level of motivation and commitment throughout the organisations.

Analysis of Land Use Land Cover Changes Using Remote Sensing Data and Geographical Information Systems (GIS) at an Urban Set up of Damaturu, Nigeria

Change detection is useful in many applications related to land use and land cover change (LULCC), such as shifting cultivation and landscape changes. Land degradation and desertification. Remote sensing technology has been used for the detection of the changes in land use land cover in Damaturu town Nigeria. The main objectives of this research is to derive the land use/cover change map of Damaturu town from 1986 to 2017 and to quantify land use/ land cover change in the study area. Methodology employed while carry the research includes three satellites images for the year 1986, 1998 and 2017 were downloaded from USGS websites and used for detecting the land cover changes. Ground truth points were collected using google images and used for verification of image classifications. The accuracy of images classification was checked using ground truth point which showed the overall accuracy of 84.6% and a kappa coefficient of 0.89 which indicated that the method of classification was accurate. In the process of the research work, an increased was recorded in the built-up area which rose from 7.2% to 22.0%, open space increased from 10.8 to 22.8%, vegetation from 4.0% to 9.7%, water bodies from 0.0% to 0.1% while agricultural land decreased from 78% to 45.4% due to increase in interest of building as a result of the expansion of the town. The study arrived at the conclusion that there has been a significant land use change due to increase in population and development interest in built up areas which resulted in increased of amount of agricultural land being converted to build up areas over the period of 31 years.

Effect of Anisaldehyde as Corrosion Inhibitor for Aluminium in Sulphuric Acid Solution

The inhibition effect of anisaldehyde on the corrosion of aluminium in sulphuric acid was investigated by weight loss method and characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analyses. The effect of different inhibitor concentrations was studied at varying temperature (308, 313 and 318 K). It was found that the percentage of inhibition efficiency (% I.E.) increases with increase of inhibitor concentration and decreases with increase in temperature. The values of activation energy and half-life were found to be higher in inhibited acid solution compared to uninhibited acid solution, while that for the rate constant reduced from uninhibited to inhibited acid solution. The negative values of Gibbs free energy of adsorption confirmed the spontaneity of the process. Other thermodynamic parameters such as enthalpy and entropy were also evaluated and discussed. The investigation of adsorption isotherm model indicates that the inhibitor fitted to Langmuir isotherm model. Result of SEM analysis shows how the inhibitor reduced the acid attack on the aluminium surface, and FTIR analysis result of the corrosion product proves the formation of thin layer of inhibitor molecules on aluminium surface.