Journal of the Nigerian Association of Mathematical Physics

On oscillations of solutions of second-order linear differential equations with constant complex coefficients

2020-06-01T20:17:14+00:00

By using a general result connected to the zeros of the solutions of linear ordinary differential equations with constant complex coefficients, we describe criteria for the existence of oscillatory and non-oscillatory solutions to the Cauchy problem for a second order linear homogeneous differential equation with constant complex coefficients. We deduce that the oscillatory behavior of the solutions does not depend on the initial conditions.

Keywords: Second order linear ordinary differential equation, oscillatory and non-oscillatory solutions, Cauchy problem, constant complex coefficients, characteristic roots.

Approximation solutions to viscous stability of unsteady MHD viscous flow through a porous vertical channel induced by hall-effect with dissipation function

2020-06-01T20:24:10+00:00

The effect of magnetic field and dissipation function parameter as a radiation in electrodynamic froth (two phase) flow process was analyzed. Expressions for magnetic flux and temperature with dissipation function were obtained based on a conductive two phase flow. The couple non-linear differential equations governing the flow were solved using the method of successive approximation techniques. It was found that at a constant time t, the influence of magnetic field was very sharp along the channel due to dissipation function and radiation parameters. The velocity of fluid flow was very rapid and increased at a faster rate as a result of dissipation function parameters.

Keywords: Unsteady hydromagnetic fluid flow dissipation function. Transverse magnetic field. Hall-effect. Porous vertical channel radiation. Optically thick limit.

Natural convective flow of hydromagnetic heat generating fluidflow through a vertical channel with time-periodic boundary conditions

2020-06-01T20:29:32+00:00

The effect of viscous dissipation and heat generation on unsteady natural convective hydromagnetic fluid with time dependent boundary conditions in a porous vertical channel was investigated. The coupled nonlinear partial differential equations governing the fluid flow and heat transfer were transformed into system of dimensionless coupled nonlinear ordinary differential equations. Differential transform technique (DTM) was used to solve the obtained dimensionless coupled nonlinear ordinary differentials equations. The effects of parameters such as suction/injection, Strouhal number, Hartmann number and heat generation/absorption parameterson the fluid temperature and velocity were presented graphically and discussed.

Assets allocation strategy in a DC pension scheme with refund clause of contributions with predetermined interest under Heston’s Volatility model

2020-06-02T07:19:34+00:00

We studied asset allocation strategy in a defined contribution (DC) pension plan with refund contribution clauses under Heston's Volatility model using mean-variance utility function. We assumed that the refund contributions are with predetermined interest and considered investments in cash and equity to help increase the accumulated funds of the remaining members to meet their retirement needs. Also, the actuarial symbol is used to formalize the problem as a continuous time mean-variance stochastic optimal control problem. We established an optimized problem from the extended Hamilton Jacobi Bellman equations and solved the optimized problem and obtained the optimal allocation strategy for the two assets and also the efficient frontier of the pension members. Furthermore, we analysed numerically the effect of some parameters on the optimal allocation strategy. We deduced that as the initial wealth, predetermined interest rate, and risk averse level increases, the optimal allocation strategy for equity decreases.

Keywords: DC Pension Fund, HJB, optimal allocation strategy, Refund of contribution clause, Interest Rate.

Ratio type estimators with Kalman filter output

2020-06-02T07:41:43+00:00

Kalman filter have been very successful as an estimator in various forms. In this paper, we introduce the use of the Kalman filter version for two phase sampling with an auxiliary variance. The computational instance gave the same precise result as that of the conventional process.

Keywords: Kalman filter, Phase sampling, Auxiliary variable.

A new spectral density Kalman filter function

2020-06-02T09:47:11+00:00

Spectral density function with respect to Kalman filter process is defined and investigated. Using the basic ideas of Kalman filter mean, filter variance and filter covariance the model gives a computational efficiency of getting a solution.

Keywords: Spectral density, Kalman filter, Filter mean, Filter variance, Filter covariance.

Econometric modeling of the impact of exchange rate fluctuation on the Nigerian economic growth

2020-06-02T10:07:52+00:00

This study investigates the impact of exchange rate fluctuation on the Nigerian economic growth and examines the possible direct and indirect relationship between exchange rate and GDP growth. The data for this study is a secondary data collected from central bank of Nigeria (CBN) and National Bureau of statistics (NBS) statistical bulletin various issues and is based on quarterly series from the period 1986 to 2013. The test of stationarity using Augmented Dickey Fuller (ADF) showed that all the variables were integrated of order one. The test of cointegration showed one cointegration vector which confirmed the existence of a long run relationship among the variables. The relationship is derived in two ways using a simultaneous equation model within a fully specified (but small) macroeconomic model and a Generalized Method of Moments (GMM) technique. The estimation result showed that there is evidence of a strong direct relationship between changes in exchange rate and GDP growth. It also showed that Nigerian economic growth has been directly affected by monetary factors. These factors have tended to sustain a pattern of real exchange rate depreciation, which has been unfavorable for growth. The conclusion is that improvements in exchange rate management are necessary but not adequate to revive the Nigerian economy. A broad program of economic reform is required, to complement the exchange rate policy.

Keywords: Exchange Rate, Economic Growth, GMM, Instruments, cointegration, Unit Root.

Migration, unemployment, income, and dollar exchange rate: An application of the bounds testing approach to cointegration

2020-06-02T10:12:17+00:00

This paper investigates the nature of the causal relationship between migration and three macroeconomic indicators, GDP per capita, unemployment and Dollar exchange rate in Nigeria using autoregressive distributed lag (ARDL ) bounds testing procedure and granger-causality within vector error correction model (VECM ) based on monthly data (2000 – 201 ). Result of ARDL shows that there is a long-run equilibrium level relationship. A critical examination of the granger-causality test reveals the existence of a long-run bidirectional causality between migration and GDP, migration does not cause unemployment but evidence shows that unemployment causes migration .Besides, evidence also showed that exchange rate granger causes migration, whereas migration does not seem to cause exchange rate. meaning that unemployment and the high Dollar exchange rate are some of the reason why Nigerian citizens are exiting the country in mass.

Keywords: Migration, ARDL, Dollar exchange rate ,Granger-causality, Unemployment

Analysis of daily average temperature of Benin City using the two – parameter Weibull model

2020-06-02T10:21:40+00:00

An analysis of daily average temperature of Benin City is carried out in this paper using 5-years temperature observations obtained from the recording station of the National Center for Energy and Environment, University of Benin, Benin City. The two-parameter Weibull model is used to fit the temperature observations and the attendant average temperature, median temperature, most probable temperature and the variance of the temperature are computed. Results from the analysis clearly revealed that the two-parameter Weibull model is a very adequate model for the temperature observations and hence can be used to efficiently calculate temperature probabilities for Benin City.

Keywords: Cumulative distribution function; maximum likelihood estimator; probability density function; temperature; Weibull model

Usability and acceptance of interactive whiteboards: MCIU as a case study

2020-06-02T10:56:56+00:00

Determining the significance of a particular tool and predicting the success of implementation is essential prior to its adoption. This study aimed to investigate the issue with acceptance and use of Interactive Whiteboard (IWB) and examine factors that influence and predict acceptance and use among Staff Members based on the construct presented by Technology Acceptance Model (TAM). To empirically test the model, a survey was administered to fifty respondents consisting of academicians from Michael and Cecilia Ibru University (MCIU). Pearson’s Product-Moment Correlation and Regression analysis techniques were employed to describe the acceptance process. The result revealed that the level of acceptance of the IWB amongst the University staff members was low. However, the independent variables (Perceived Usefulness, Job Relevance, Computer Self Efficacy, Facilitating Condition, Perceived Ease of Use, and Awareness) were found to have strong support to predict the Behavioral Intention to use the IWB. Based on the findings, approaches on how to improve the level of acceptance and usage were recommended.

Keywords — Interactive Whiteboard, Technology Acceptance Model, Learning Institution, Academic Staff

Stock dependent demand inventorymodel for instanteneous deteriorating item with time dependent back logging rate

2020-06-02T11:19:55+00:00

This paper investigates stock dependent demand model having instantaneous deterioration, linear time dependent holding cost and linear time dependent partial backlogging rate. In real life situation, deterioration of some items such as fruits, vegetables, meat, fish, and so on start immediately the item arrives the inventory and the backlogging rate cannot always be complete because it is not every customer will be patient enough to wait for arrival of item during the stockout period. The inventory policy is to determine the optimal replenishment policy in order to maximize the profit function. The inventory system was represented by a system of differential equations and also appropriate methods for solving differential equations were used to obtain the solutions to the inventory system. We determined the necessary and sufficient condition for optimality, after which we provided numerical example. We also conducted sensitivity analysis to demonstrate the application of the model. The results of the model show that the various changes on the input parameters have a great impact on the optimal replenishment policy.

Mathematical model of eradication of tuberculosis through vaccination and treatment strategy with absence of immigration effect

2020-06-02T16:01:58+00:00

In this study, we proposed a mathematical model for the vaccination and treatment strategy to eradicate tuberculosis with absent of immigration effect, where we modified the existing model by incorporating the emigrants effect, efficacy of vaccination, treatment and new babies were considered 100% vaccinated. Existence and uniqueness of solution of the modified model was carried out and it shows that the solution exists and it is unique. The stability analysis of the disease free equilibrium shows that the disease-free equilibrium (DFE) is locally asymptotically stable. The effective reproductive number Re was computed under different conditions. In the case where there is treatment and vaccination we found Re to be 0.1530. The results show that mycobacterium tuberculosis can be eradicated if mass vaccination and treatment actions are properly initiated and enforced. Also, infected immigrants need to be restricted from entering the population to ensure fast eradication of mycobacterium tuberculosis.

A deterministic model for prediction of hard waste production in the presence of inhabitants and industrial escalation

2020-06-02T16:30:18+00:00

Solid administration issues are increasing in developing world due to increase in ppopulation and industries and with majority of cases , there are no data of how much solid waste is produced in a precise period of time in mainly urban areas. Solid waste production rate increases with raise in inhabitants and industrial actions. In this paper, we proposed deterministic model equations in the existence of industrial and inhabitants’ expansion was reformulated by add in industrial waste and industrial compartments in an existing model. Fourth-order Runge-Kutta scheme was used as numerical method to solved the reformulated model. The stability analysis of the model was carrying out where the model equations were asymptotically stable. Empirical data were used to valid the model and the result show that an increase in industries and population there will be an increase industrial waste.

Keywords: Hard waste , inhabitants and Industry

Linear model for fuel optimizing speed on roads connecting Lafia metropolis to neighbouring communities

2020-06-02T16:52:07+00:00

Fueling cost represents a very significant portion of vehicle maintenance cost. For some vehicle it takes up to 50% of the total maintenance cost. Fuel consumption has been established to depend largely on factors like vehicle characteristics, highway characteristics and the attitudes of drivers. In this study, a real time fuel consumption model was developed for the 5 major roads connecting neighboring communities to Lafia metropolis. In most of these communities over speeding in a bid to minimize fuel consumption is paramount and this study was designed to experimentally arrive at fuel minimizing speed for these roads. To develop the model, a large speed fuel experiment involving more than 1000km of driving was carried out for a speed range of 40km/h to 120km/h using a Toyota corolla car with fittings to take instantaneous data of fuel consumption and road characteristics. A model was constructed for fuel consumption as a function of speed and number of applied brake. The full speed equation for each of these roads was minimized to yield a range of numerical values for optimal fuel for each road. These equations are found to be consistent and within the neighbourhood of EPA (Environmental Protection Agency) minimal fuel speed of the used vehicle.

Keywords: Optimal fuel consumption; road characteristic; vehicle characteristics.

A conjugate gradient method-based algorithm for optimizing the generalized 2-dimensional optimal proportional control problems

2020-06-02T17:52:23+00:00

A generalized two-dimensional optimal proportional control problem constrained by ordinary differential equations is presented in this study. The analytical method and numerical technique for solving optimal proportional control problems with equality constraints are discussed. Complete discretization approach is adopted for the numerical optimization of the problem. Simpson’s ?? Rule and Fifth-order Adams Moulton Technique are employed for the discretization of the objective functional and the constraint, respectively. Quadratic penalty function method is used to transform the constrained discretized optimal proportional control problem to unconstrained problem. Numerical solution of the unconstrained optimization problem is obtained using Conjugate gradient method algorithm. Two numerical optimal proportional control problems are considered and their analytical and numerical solutions are presented. The accuracy and efficiency of the new scheme over the existing algorithms is demonstrated through the analysis of convergence. The results show that the new scheme exhibits a superlinear convergence, which is an improvement on the existing schemes.

Keywords: Proportional Control, Discretization, Quadratic Penalty Function, Convergence, Conjugate Gradient Method.

A survey on the utilization of cloud computing services for academic learning

2020-06-02T18:34:30+00:00

With the rapid innovations of storage and powerful computational processing technologies, as well as the achievements of the Internet have made computing resources to be affordable at reduced pricing and more available than ever before. This technological drift has facilitated the recognition of a novel computer technology called cloud computing. Thus, enabling its resources to be provisioned as collective services that can be leased by cloud service providers to end users via the Internet in an on-demand approach. The education sector in the developed countries is achieving more knowledge and benefits from cloud services, as they shift more of their core academic learning activities onto the cloud platforms. However, Institutions in developing countries such as Nigeria, have not yet embraced this rapidly growing technology to facilitate their academic learning environments. Therefore, this paper tends to carry out a survey to investigate the perception of students in three higher Institutions (located in Delta State, Nigeria) about their perception of cloud computing usage and its benefits in academic learning. The investigation was achieved with the aid of a questionnaire survey. Thus, the results obtainedshow that most of the students have the awareness of cloud computing but are yet to explore its services in their studies and learning. Furthermore, the tendency of adopting cloud services to facilitate learning by the students is reasonably in the increase. However, there are some issues such as funding and access to free network/ Internet broadband are to be addressed before the realization of the said technology will be adopted massively by the students.

Keywords: Cloud Computing, Software as a Service (SaaS), Platform as a Service (PaaS), Infrastructure as a Service (IaaS) and Cloud Service Providers (CSPs)

Epidemiological model of computer malware prevalence and control

2020-06-02T20:21:09+00:00

The mathematical model of computer Malware remains a challenging research area for modeling and simulation in an attempt to devise policies and guidelines to curb the impact and transmission of malware in computer networks. The Susceptible high risk, Susceptible low risk, Exposed class, Infectious due to virus, Infectious due to worms and Recovered (ShSlEIvIwR) model was formed. Basic reproduction number, the equilibrium point of the virus and worm free computers and the endemic equilibrium state are discussed. For locally and globally asymptotically stability of the infection free equilibrium state, the next generation matrix was applied. Numerical solution was carried out to solve and simulate the system with the view to understand the prevalence behavior, transmission dynamics and the control of computer viruses and worms in computer network and also the efficiency of antivirus software.

Keywords: Malware, Computer virus, susceptible, expose, infectious, recovered.

Elliptic approach to the locations of the equilibrium points of the robe’s restricted three-body problem

2020-06-02T20:37:27+00:00

No Abstract.

Performance of CMIP5 models in temperature simulation over West Africa

2020-06-02T21:07:38+00:00

The performance of forty-five Global Climate Models GCMs that participated in the fifth phase of the Coupled Model Inter-comparison Project (CMIP5) in temperature simulation is evaluated over four temperature regions of West Africa the Guinean Savannah (GS), Western Sahel (WS), Lower Sahel (LS), and Eastern Sahel (ES) by comparing the model outputs with ground observation(CRU data) for the period of 1961-2005 using Normalized Mean Absolute Error, Normalized Root Mean Square Error and Taylor diagram at different percentiles. The analyses is done to select models that best simulate the temperature with least error for application in climate projections and climate change impact over this highly vulnerable region of interest. The skillful models for temperature simulation over each region are selected and compared. The skillful models over at least two temperature regions over West Africa (twenty three out of the 45 models considered) are finally selected and suggested for applicability in future projection and climate impact studies.

Keywords: Temperature simulation, General Circulation Models, normalized mean absolute error, percentiles

Healthcare data analytics using traditional and Hadoop frameworks for smart healthcare decision making

2020-06-02T21:26:43+00:00

This study aimed to describe the healthcare analytics data infrastructure used by organizations to carry out report and analysis regarding their healthcare data. Healthcare data involved data generated from electronic medical records which are structured and unstructured in nature. There is need for healthcare organization to make use of effective analytical techniques (i.e. big data analytics or traditional approach) in health sector which provides health practitioners and stakeholders with new insights that have the potential to advance personalized care to improve patient outcomes and avoid unnecessary costs. This study aimed to carry out a comparative analysis regarding healthcare data analytics between Traditional system that adapted relational database management system (RDBMs) using MySQL and big data approach using Hadoop/Mapreduce. Based on the comparison metrices, the analysis was conducted with a traditional relational databases tool installed on a stand-alone system, such as a desktop or laptop. But using big data Analytic tools and platforms, processing is broken down and executed across multiple nodes. However, after detailed comparative analyses between the two approaches have been done, the research found out that Hadoop is the best technique for handling Big Data compared to that of Mysql. As day by day, the data used increases and therefore a better way of handling such huge amount of data is becoming a hectic task.

Keywords: Big data, Big Data Analytics, Hadoop/MapReduce, HDFS, Healthcare data, Structured data, Unstructured data, RDBMs, Traditional Relational Database.

Review of Supervisory Control and Data Acquisition Systems (SCADAS)

2020-06-02T21:32:34+00:00

SCADA simply means, Supervisory Control and Data Acquisition System. As the name point out, the system is not a full control program, but it concentrates on the supervisory level. The system is a computer program for gathering and analyzing real time data. They are used in the following areas: to monitor and control a plant or equipment in industries, in telecommunications, water and waste control, energy, oil and gas refining and transportation. They relatively simple, which can monitor environmental conditions of a small office building, or a very complex one. It can also be used in monitoring the activities in a nuclear power plant or the activities in a municipal water system. This paper describes the SCADA systems in terms of their architecture, their interface to the process hardware, the functionality and the application development facilities they provide.

Keywords: Supervisory Control, Data Acquisition, Monitor, Control program, Real Time

Development of genetic algorithms based weighted method for multi-objective optimization

2020-06-03T06:31:03+00:00

This study presents a method to determine weights of objectives in multi-objective optimization without decision maker's preference This method is based on Scalarization and normalization of convex objective functions as well as the principle of proportional selection of Genetic Algorithms procedure. The proposed method is shown with a numerical example and several fuzzy solution approaches are used to get a solution by using obtained weights. Also the results of problems that are obtained from literature are presented. The method developed in aggregating the two or more conflicting objective functions show the possibility of solving multi-objective problems without: (i) the articulation of preferences among the criteria and (ii) arbitrary choice of weights; which usually required sensitivity analysis to be carried out.

Keywords: weighted method, multi-objective optimization, genetic algorithms, Pareto method, aggregated objective functions

Symmetries of rhotrix using Aunu permutation pattern

2020-06-03T06:53:16+00:00

This study deals with connection between rhotrices and Aunu permutation patterns. The features of rhotrices and Aunu permutations patterns are observed. A relationship between Aunu permutation patterns and rhotrices is established for a case where n is a prime number equal to 5. It is also observed that the heart of the rhotrix is necessarily 1 everywhere. The derivation of the Aunu permutation pattern from the rhotrix starts from the heart of the rhotrix to the upward direction; from upward direction to the left and to the right of the heart, and finally to the buttom of the heart. When the rhotrix is rotated at right angle, a semigroup is obtained. Embedding an identity element into the semigroup again produces a Carley group.

Keywords: Rhotrices, Aunu permutation patterns, semigroup, carley group, derivation of Aunu permutation patterns.

Research on encryption and decryption algorithm of audio with chaotic mapping

2020-06-03T07:06:13+00:00

With the audio application in the modern communication technology, audio information is necessary to ensure safety in the transmission section of communication system. The technique used to privately and securely transmit an audio (voice) signal by applying two-dimensional (2D) Henon and one-dimensional Logistic (1D) maps is introduced to enhance the security by increasing the key space and the dimension which in turn increases the nonlinearity. In this paper, The algorithm uses the chaotic iteration to generate the symmetric encryption keys, and then carries out the XOR operation on the plaintext (audio signal samples) to form the cipher text (encrypted signal samples).The algorithm owns large key space to make brute-force attack impossible. Statistical analysis demonstrates the effectiveness for fast audio encryption, the simulation is performed in MATLAB and the results are observed. The results showed the effectiveness of the proposed scheme in terms of security due to its large key space, nonlinearity and sensitivity to the keys.

Keywords -Audio signal, PCM, Encryption and Decryption, Chaotic Mapping.

Shear wave estimation for rock physics reservoir evaluation of jay field in the Niger Delta basin

2020-06-03T07:24:49+00:00

Shear wave logs are one of the key data required for most Amplitude Versus Offset (AVO) studies and quantitative seismic interpretation. Despite its overwhelming importance, it is hardly available in most wells due to its very high cost of acquisition. In the absence of shear wave logs in the field, the Castagna’s empirical relationship that relates P-wave and S-wave velocities and Biot-Gassman’s Fluid substitution equations were adopted for its estimation. The results obtained revealed that Castagna’s empirical relationship underestimated the Shear wave log in the field, even after Biot-Gassman’s Fluid substitution model was applied to define P-wave of the brine filled scenario. A cross plot of Mu-Rho versus Lambda-Rho presented low values for Mu-Rho due to the underestimated shear wave used. To correct for the underestimation, a modified form of the Castagna’s Equation constants were establish. This was achieved by generating several linear regression equations that defines the relationship between P and S-wave for brine sands in the field. The cross plot of Mu-Rho versus Lambda-Rho done with the modified shear wave gave very good results as expected for both fluid and lithology discrimination.

Keywords: Shear Wave, Castagna’s Equation, Biot-Gassman’s Equation, Rock Physics, Cross plots

Performance of a tapered vertical well in an infinite-acting reservoir – a novel approach

2020-06-03T07:33:51+00:00

This study adopts a new form of vertical well technology involving the use of a tapered well completion. It presents a mathematical model for evaluating the performance of a tapered vertical well masked by an infinite acting flow regime. Matthews and Russell’s solution to the radial flow diffusivity equation was utilized infiguring the strength of a vertical wellbore designed with a tapered configuration. To accomplish objective, pressure drawdown per unit rate was computed employing three distinct vertical tapered well completion combinations: Conventional, 2-Step tapered and 3-Step tapered completion. The derived model was demonstrated using a hypothetical well and reservoir case. Sensitivity of unit rate function to tapered height and wellbore radii was critically examined using several tapered ratios. Results obtained are compared against that from a conventional well configuration. It shows a better performance for a 2-step tapered vertical well and an even better performance when the well is tapered in 3-Steps. Furthermore, as the tapered ratio became farther apart, a better performance resulted. Radial flow persisted the larger the number of tapering. The number of taper possible was seen to be limited by the pay thickness. Reservoir, wellbore and fluid properties also largely affected well performance for all cases of completion considered. The completion efficiency of the tapered vertical well was seen to exceed largely that of the conventional vertical well completion on the basics of pressure drawdown per unit flowrate. This paper successfully shows that the capacity of the vertical well has not yet been fully exploited. It therefore follows that a tapered vertical well completion is more efficient that the conventional vertical well and is strongly recommended to Petroleum Engineers and the Oil and Gas industry in general especially for reservoirs with a large pay thickness where high rates are desired.

Keywords: Tapered Well, Performance evaluation, Infinite-acting, Pressure drawdown, completion, Reservoir, Pressure drawdown/unit flowrate.

Acoustic properties of shale and sandstone

2020-06-03T07:49:51+00:00

Acoustical properties employ sonic wave velocities as spring board to mirror the sediments. The albatross associated with analyzing constituent sediment warrants that grain structures and mineral composition are well highlighted for meaningful results. The combination of whole rock mineralogy and well logs give a detailed road map to unraveling the rock physics trend of sediments through mechanical properties and petrophysics generation. The generations of velocity ratio (Vp/Vs), acoustic impedance (AI), Poisson ratio (PR) in this work were in no small means helpful. These accomplishments held without losing focus of the dominance of either smectite or kaolinite and even their combination by pore filling smectite of kaolinite in the case of clay volume in shale; quartz cementation by pore filling smectite in the case of sandstone to pure sandstone (zero clay volume) without down-playing the all important K-feldspar. In well 1, quartz has a range of 19-27% with some points showing high Vp/Vs, PR and high AI at close percentage of S-I and KDH; other points yielded low Vp/Vs, PR and high AI; points of high percentage pore filling smectite showed low Vp/Vs, PR but high AI. In well 2, points of high Vp/Vs, PR but abnormally low AI are present; also are points of low Vp/Vs, PR but high and low AI. High velocity ratio may be due to poorly compacted situation of possibly high overpressure and low effective stress. Porosity and permeability diminish with reducing Vp/Vs and PR. Contrast in permeability of shale minerals (smectite and kaolinite) for which the latter rates higher is a requisite in the assessment of shale for the purpose of seal and reservoir alternation.

Keywords: Velocity ratio, Poisson ratio, acoustic impedance, quartz cementation and dilation factor.

Use of Azimuthal square-array direct-current resistivity method to determine geological fractures in the golf course area, Kaduna north, Nigeria

2020-06-03T08:05:08+00:00

Azimuthal square array using direct-current electrical resistivity was used to determine the presence of fracture in Kaduna Golf Club, Kaduna state Northwest Nigeria. The objective is to apply the electrical resistivity method using square array technique to identify probable geological structures (faults and fracture) within the study area as may influence groundwater condition and to identify fracture anisotropy. With the aid of Ohmega resistivity meter, the square array data were collected in five profiles, with each rotated at different azimuths ranging from 00ᵒ to 180ᵒ at an interval of 15ᵒ at an electrode spacing of 12m and 15m respectively. The polar plots showed variation of resistivity with azimuths which is indicate of the presence of electrical anisotropy. Fracture strike was found with dominant strike in the SW and SE directions, while the calculated apparent coefficient of anisotropy (??) varies from 1.0 to 3.4 which shows the presence of rocks with different physical properties in different orientation in the subsurface of the study area.

Computation of elastic wave signals from a line source in a layered medium

2020-06-03T08:18:38+00:00

The need for synthetic seismograms arises in several seismic profiling contexts. This paper outlines a method of computing synthetic seismograms for elastic wave signals from a point or line source with a prescribed time dependence and at a distance h from the surface in a layered medium. Laplace transform is applied to the elastodynamic equation to obtain the velocity functions. Both the Laplace and Fourier transforms were applied to the linear stress-strain relation to derive the displacement functions. Knowing the source function and a model, these displacements and velocity functions can be used to generate theoretical seismograms for modeling with observational records from seismic profiling.

The application of Doppler effect to approximate the rate of change of volume of the lungs

2020-06-03T08:32:50+00:00

The use of sound in probing the internal organs has proven to be vital as it is a non-invasive means of acquiring information about the internal area of the desired organ. The Doppler Effect phenomenon is employed in this research to calculate the frequency shift of the lungs during respiration. Through this manner, the rate of change of volume of the lungs can be approximated.

Keywords: Doppler Effect, frequency shift, expansion and contraction of lungs, rate of change of volume.

Empirical study on the effect of temperature on the electrical parameters of Schottky diode using Cheung’s model

2020-06-03T08:47:55+00:00

An empirical study on the effect of temperature on some electrical parameters of Schottky diode contacts of three different metals, namely; Chromium (Cr), Tungsten (W) and Molybdenum (M_o) with n – type Silicon and n – type Germanium using Cheung’s model is been analyzed. The electrical parameters are the saturation current (I_o); ideality factor (n); barrier height Φ_B ) and series resistance (R_s). Three different temperatures were chosen, 300 K, 310 K and 320 K. The range of values of the voltage used in the computation process are 0.09 V – 0.15 V. Results show that increase in temperature of most of the metal – semiconductor contacts is proportional to the saturation current and the ideality factor, but inversely proportional to the barrier height and the series resistance. This result agrees with some experimental outcomes, and to some extend shows the validity of the model used.

Keywords: Schottky Diode; Temperature; Saturation Current; Ideality factor; Barrier Height and Series Resistance.

Effect of HfO₂and Al₂O₃ high -k dielectrics double layer thickness on the breakdown voltage of enhancement mode of iii-v metal insulator semiconductor-high electron mobility transistor

2020-06-03T08:59:44+00:00

Dependence of Breakdown voltage (Vbr) on oxide thickness (TCH) for GaN-based Metal–Insulator Semiconductor High-Electron-Mobility Transistors (MIS-HEMTs) using HfO₃ and Al₂O₃ as gate dielectric is studied in detail. Different (III-V) heterostructures (AlGaN/GaN and AlInN/GaN) with different dielectrics passivation layers were used and compared with HfAlOx double layer thickness for the simulation of these MIS devices. Interestingly, for all the sets of devices, anincrease in Vbr was observed initially with Al₂O₃, followed by another positive shift with HfAlOxof the same. A maximum of Vbr1500V was achieved. A comprehensive analytical model has been proposed to explain the variation of Vbr withAl₂O₂dielectrics and HfAlOx has been shown to match the experimental data for MIS-HEMTs fabricated on different heterostructures and with different values dielectrics. This model allows the extraction of different charge components in the oxide or at oxide/III-V interface. Normally OFF AlGaN/GaN MIS-HEMTs have been demonstrated with the optimized TCH of HfO2 and Al₂O₃. Index Terms—HfO₂, Al₂O₃, AlGaN/GaN, MIS-HEMT, oxide thickness, threshold voltage

Review of the nuclear systematics for nuclei ?≈140−214

2020-06-03T09:14:16+00:00

The excitation energies of lowest-lying spin/parity Iπ = 2+ nuclei states and ratio of first spin/parity 4+ to 2+ states, R(4/2) = E(4+)/E(2+)have been used to investigate the systematics of shape evolution with changing nucleon number which have been used to describe the degree of nuclei collectivity in heavy even-even nuclei for A ≈ 140-214. The review showedhigh excitation energy values ofyrast 2+ states near magic numbers of nucleons. The scattered points of isotopes of Po and Pb around N ≈ 96 – 126 and the magic numbersN = 82 and 126 whereR(4/2)< 2 is consistent with spherically shaped nuclei. The nuclei around R(4/2) ≈ 2.00 are consistent with quadrupole vibrational excitations about near-spherical nuclei which implied oblate shaped nuclei. Nuclei with N ≈ 90 – 96 where R(4/2≈ 2.5 agreed with? - soft rotor. The clustering of points around values of R(4/2)≈ 3.33 with N = 96 – 114 showed consistency with the perfect, axially symmetric quantum rotor nuclei with well deformed prolate shape. It is concluded that the nuclei with R(4/2)≈ 3.33 around N ≈ 96 – 114, would generate higher energy when used inthe production of betavoltaics and in nuclear power plants due to the ease in ?−-decay. On the other hand,nuclei with R(4/2)< 2 can easily be studied in the laboratory due to longer half-lives but may require larger amount of energy for nuclear synthesis due to closed shell and higher stability.

Keywords: Exotic nuclei, Shape evolution, Quadrupole deformation, Nuclei Stability.

Half-life measurement of the yrast 1^x = 2⁺ In ¹⁵²sm

2020-06-03T09:24:46+00:00

The half-life of the excited 2⁺ state at 121 keV in ¹⁵²Sm has been investigated using the fast-timing cerium-doped lanthanum-bromide (LaBr3(Ce)) scintillator detectors of the RoSPHERE gamma-ray spectrometer at IFIN- HH Bucharest. The half-life was deduced by fitting the exponential slope of the decay spectra ΔT and via the centroid shift methods. Results from both methods are in agreement with the global half-life value of 1.403(11) ns reported for the 2⁺ yrast state of ¹⁵²Sm.

Keywords: RoSPHERE, Coincidence, Gamma-ray array, Spectrometer, high-purity germanium, lanthanum tribromide scintillators, slope methods, centroid shift methods and time difference.

The effect of mineral nuclei modes in the particle distributions of Sahara mineral dust aerosols

2020-06-03T09:33:45+00:00

In this work, the aerosols optical depth (AOD) of Sahara aerosols were extracted from Optical Properties of Aerosols and Clouds (OPAC) software package (4.0)at eight relative humidities RHs (00,50, 70, 80, 90, 95, 98,and 99)% and ultraviolet to visible wavelengths (0.25 to 0.9) μm. The mixture or composition of Sahara aerosols are water, mineral nuclei mode nonspherical, mineral accumulation mode nonspherical and mineral coarse mode nonspherical. The number concentrations of mineral nuclei modes nonspherical were varied. The angstrom exponent (α) which is normally used to analyze the type of particle and size distributions using inverse law was applied at all RHs. The inverse law was linearized by using natural logarithm and also into the second order polynomial with the natural log. From the linear part α were determined and analyzed while in quadratic part α2 (known as curvature)were also analyzed. It was observed that α is less than 1.0 signified coarse mode particles and increases with the increase in the concentration of nuclei mode particles and RHs. The α2 which gives additional information of particle mode distributions is positive at the RHs between 0 to 95%, this shows bimodal type of size distributions and negative at 98 and 99% which shows monomode type of size distributions with the dominance of coarse mode particles. With the increased in nuclei mode and RHs, it was clearly shown that from the figures 1 to 5 values of AOD is high at shorter wavelengths and decreases towards longer wavelengths indicating the loading of fine and coarse mode particles into the atmosphere.

Keywords: Angstrom exponent, aerosols optical depth, curvature, wavelengths, relative humidity

Estimation of the contamination levels of heavy metals in selected soil samples from Irri, Delta State-Nigeria

2020-06-03T09:39:08+00:00

Soil samples obtained from different locations in Idheze-Irri was analyzed for the presence of heavy metals; lead (Pb), Nickel (Ni), Chromium (Cr), Copper (Cu) and Cadmium (Cd). The estimated mean concentrations of the studied metals were below the global world average respectively while Cd was undetected in the samples. Pollution (contamination) Index (PI) values obtained for Pb, Ni, Cu and Cd are within the category of PI ≤ 1. Enrichment Factor (EF) values indicate that the samples are moderately enriched with Pb and Cu, minimally enriched with Ni and extremely enriched with Cd. Geo-accumulation Index (Igeo) shows that the samples are unpolluted with Pb, Ni, Cu, Cd and Cr. Ecological Risk Index (ERI) values are within the category of ERI ≤ 50 which implies that their quantity in the soil is minimal and hence poses low risk to the environment. All the results and analysis show that the samples are unpolluted with heavy metals (Pb, Ni, Cu, Cd and Cr) and thus the study area is considered safe for habitation and other human activities.

Keywords: Heavy metals, Concentration, Oil spillage, Pollution, Soil samples.

Study of electromagnetic radiation from gsm base transceiver stations within the University of Benin, Ugbowo Campus

2020-06-03T09:47:33+00:00

This paper presented a study on electromagnetic radiation level from different GSM Base transceiver stations (BTS) in Ugbowo campus environment of the University of Benin, and compared these levels of radiation with that recommended by Regulatory Authority. Measured electromagnetic radiation levels in terms of maximum power density with respect to distance from existing GSM BTS were taken. A total of five functional BTSs located within the campus were used investigated. Using a Tenmars RF 3-axis Field Strength Meter, the amount of radiated energy at 10m from the BTS was measured, and repeated for a span of 100 meters (at 10m intervals). These Measurements were taken from three radial directions from each BTS, to improve the accuracy of data collected. The obtained data were analysed using Microsoft Excel package. The result showed that the radiation levels for all sampled BTS are within the recommended regulatory standard.

Keywords: Electromagnetic Radiation (EMR); GSM; Base Transceiver Station (BTS); Power Density; Radial Direction; Tenmars RF Meter.

Comparative study of a developed SEAODV with conventional AODV

2020-06-03T09:53:47+00:00

An ad-hoc network of wireless nodes is a temporarily formed network, created, operated and managed by the nodes themselves. Nodes assist each other by passing data and control packets from one node to another, often beyond the wireless range of the original sender using routing protocols. Ad hoc On-demand Distance Vector (AODV) is a reactive or On-Demand routing protocol where routes are created as and when required. In this paper, we conducted a comparative study of a developed Secured Ad-Hoc On-Demand Distance Vector routing protocol (SEAODV) with the conventional AODV. The simulation and comparison of SEAODV with conventional AODV protocols was done using OPNET (Optimized Network Engineering Tools). The performance of SEAODV routing protocol was compared to that of the conventional AODV using media access delay, network throughput and total packets dropped.

Keywords: AODV, MANET, ad hoc, on-demand, vector routing protocol, and OPNET

Adsorption models for the sequestration of dye from wastewater using potatopeels as adsorbents

2020-06-03T09:58:12+00:00

This study investigated the use of locally prepared adsorbent from potato peels for the sequestration of dye (amino-phenol) from wastewater. The popular kinetic adsorption models were utilized for the assessment of the mechanisms of the adsorption process. Findings from the study showed that when the adsorbent dosage increased from 4 to 12g, adsorbed dye increased from 0.31to 0.35mg/g. Increase in contact time from 20 minutes to 120 minutes and temperature (20°C to 80°C) also increased the quantity of dye adsorbed from 0.20mg/g to 0.22mg/g and 0.23mg/g to 0.27mg/g respectively. In the same vein, increase in dye concentration from 20 mg/gto60mg/g, caused an increase in adsorption(0.21mg/g to1.32 mg/g). The Langmuir and Freundlichisotherm models fit the experimental data well with R2of 0.995 and 0.992 respectively. The constants (k1 and k2) gotten respectively from the Pseudo to first and second order kinetic models were 0.07 and 1.51.

Keywords: Potato peels, adsorption, dye, modeling

Bearing capacity improvement of sandy soils at Oleri community using cement stabilization

2020-06-03T10:04:09+00:00

The constructional activities in the coastal areas often demand deep foundations because of the poor engineering properties and the related problems arising from weak soil at shallow depths. The very low bearing capacity of the foundation bed causes shear failure and excessive settlements. Furthermore, the high water table and limited depth of the top sandy layers in these area restrict the depth of foundation thereby further reducing the safe bearing capacity. This paper discusses the bearing capacity improvement of the sandy soil at Oleri community of Delta State, Nigeria; using cement stabilization as the possible solution to foundation problems in the community. The collected soil samples were stabilized by adding ordinary portland cement at different percentages (0%, 3%, 5%, 8% and 10%).The bearing capacity of the natural soil was calculated at varying depths and compared with the ones stabilized with cement. The result showed that the bearing capacity improved from 12.44kN/m2 at 0% cement content to 120.55kN/m² at 10% cement content on surface level; and 21.89kN/m2 at 0% cement content to 194.97kN/m² at 5% cement content for a depth of 1.5m.

Keywords: Bearing Capacity, Sandy Soil, shear failure, foundations, settlement, cement stabilization

Throughput optimization in IEEE802.11 and IEEE 802.3 networks using LAN for implementation

2020-06-03T10:16:53+00:00

The aim of this research work is to evaluate the performance characteristics of wired and wireless communication systems, using Local Area Network (LAN) as a case study with respect to throughput optimization. To ensure high quality services in wireless and wired networks environment is very crucial in network deployment. Rapid advances have taken place in the field of wired and wireless networks, networks provide means of network resources assessment and sharing. The throughput optimization analysis is based on IEEE802.11 wireless and IEEE802.3 wired standards. The research methodology employed, was the measurement method and Delta State University e-library network infrastructure was used as the test bed for data collection. Wireshark Version 1.6.7 Software was used to capture the downlink traffic statistics on both networks for a period of six months. Microsoft Excel software was used for the computation of the performance metric, throughput and bit error rate on both networks. The lowest computed network throughput was optimized and the fixed packet length and the variable transmission rate optimization method was used. The model was simulated with Matlab Version 2016a. From the computed and simulated downlink throughput, the throughput increases with increases in transmission rate.

Keywords: Throughput, Optimization, Local Area Network, IEEE 802.11 and IEEE 802.3

Utilization of power generating plants in Nigeria

2020-06-03T10:22:20+00:00

We study the utilization of electricity power generating plants in Nigeria. In particular, Azura power plant in Edo State, Nigeria, is used as a case study. Utilization of a power generating plants is the ratio of the power generated by the plant to the name plate of the plant. The name plate of a plant is the installed capacity. We use published data on daily net power output (MWh) and the constraints (MWh) to derive the total expected output. The total expected output is the sum of net power output and the constraints. The constraints (MWh) is the power not generated by a power plant due to limiting factors such as the national grid requirements (transmission requirements), gas supply, and demand load. The empirical maximum utilization of all the generating plants using the available data is 0.69, where Utilization is given by net output divided by total expected output. At Azura power plant, the maximum utilization observed for a thirty- day period (25/09/2018-24/10/208) is 0.53. The main reason for this low utilization at Azura power plant was grid requirement. The results support other studies that the transmission system in the country is a bottle neck in supplying electricity to consumers. We propose the use of off grid solution such as the introduction of micro-grid so that generating plants can generate electricity and supply to consumers near them without using the national grid.

An enhanced keylogging detection system using honeypot approach

2020-06-03T10:31:14+00:00

In this work a countermeasure scheme known as an enhanced keylogging detection system using honeypot approach (EKDS) was developed for detecting keylogging attacks. A honeypot is a technology deployed to stop unauthorized access to information system. The EKDS is divided into five modules namely: The honeypot database, pre-processing and pattern extraction phase, Discretization, Classification and the Detection phase. The honeypot database was scanned with prefixspan algorithm to get patterns. The extracted patterns are passed onto the discretization phase so that we can have our data in discrete form. The data in the discretization phase was passed to the classification phase where Support Vector Machine (SVM) was used for training and the output was later optimized using Bat Algorithm. Particle swarm Optimization (PSO) was used to compare the result got from EKDS. The result obtained through accurate analysis showed that EKDS outperformed PSO in all the matrices that it was compared with. Therefore the honeypot approach has proved to be robust in solving the problem of software keylogging attacks.

Keywords: Honeypot, Keylogging, Prefix Span Algorithm, Particle Swarm Optimization, Bat Algorithm

Orbits and axes around L_{4, 5} of the low-mass X-ray binary cen X-4 in the photogravitational er3bp with oblateness and triaxiality

2020-06-03T10:42:47+00:00

We study both analytically and numerically, the effects of eccentricity, oblateness of the primary body, and luminosity-triaxiality of the secondary on the frequencies of the long and short periods and their eccentricities, semi major and semi-minor axes around the triangular points of Cen X-4 in particular and some general systems with mass ratios μ 0.015, μ 0.025 and μ 0.03. The combined effect of increasing triaxiality and oblateness keeping eccentricity of the primaries constant is an increase in: frequency of the short period, eccentricity of the long period and both semi-major axes, and a decrease in frequency of the long period, eccentricity of the short period and both semi-minor axes of the low mass X-ray binary Cen X-4.

Keywords: Celestial Mechanics; ER3BP; Periodic orbits; LMXB: Cen X-4. PACS Nos: 95.10.ce

A framework for campus wide network using cluster virtualization and transmission rate management

2020-06-03T10:48:16+00:00

With cluster virtualization, coexistence of multiple virtual servers in a shared network infrastructure without requiring unified protocols, applications, and control and management plane is realizable. In this case, Delocalized Software Defined Networking (DSDN) was use to enhanced the performance of campus cloud service network. This offers virtualized resource management thereby saving cost for enterprise organization(s). Also, for optimizations of bandwidth link in such wireless network, transmission rate management is needful. In this paper, a conceptual framework for campus wide network is presented leveraging the two highlighted perspectives. Detailed algorithms that ensures network and traffic stability on a typical Campus Wide network substrate is described. Using Riverbed Modeler event based simulation; the algorithms for computational intelligence were migrated from switch-centric to server-centric cloud datacenter network topology. This architecture is recommended for enterprise web application services deployment in Campus networks. Furthermore, Admission Control Synthesis Architecture (ACSA), transmission rate management by scheduling, and virtualization implementation with IBM Flex System manager were extensively analyzed in the proposed framework. A feasible production testbed (CWN FiConn) for unified services is presented as a validation/proof of concept showing over 50.57% efficiency in terms of throughput, resource utilization of about 31.25% and near zero network latency when compared with a legacy FatTree model. The perspective offered in this work demonstrates that campus networks can be re-engineered for enterprise efficiency.

Keywords: Cloud Computing, Datacenter, QoS, Campus Network, Virtualization, Riverbed Modeler.

Investigating commercial banks profitability in Nigeria using Bayesian statistical approach

2020-06-03T10:52:20+00:00

This paper investigates the profitability of Nigeria commercial banks using internal and external variables considered to be determinants of bank profitability. The well celebrated Bayesian model averaging is employed systematically. And it reveled that from the thirteen variables considered EQTY, AST, INV, CAR, CRR, BSZ, EXM, LTA, DTA, GDP, IRR, EXR and IR which gave 8192 plausible models generated by MCMC algorithm a sample of 1393 models were sampled. Only EQTY, AST, INV, CAD, CRR, BSZ and EXM showed evidence of strong explanatory power in explaining commercial
Banks profitability, with EQTY as the most probable predictor. It is found that the mean recorded number of covariates is seven with a shrinkage statistics 0.9988 meaning that for any commercial bank to improve in their profitability they must give more attention and improve greatly on their returns on EQTY, AST, INV, CAD, CRR, BSE and EXM.

Keyword: Shrinkage, Posterior Probability. MCMC, Profitability.

Characterization of subsurface structures across a functional borehole at Mabushi Area of Kaduna State Nigeria

2020-06-03T10:56:48+00:00

Mabushi area lies between latitudes 9⁰30' N and 9⁰45'N and longitudes 8⁰20'E and 8⁰35'E in the southern part of Kaduna state Nigeria. A Profile of 200m length was established comprising of nine (9) VES Points with a functional Borehole located betweenVESmb3 and VESmb4. The Borehole is one of the oldest in the Area. This study was aimed at characterizing the subsurface structures along the profile taken NE-SW across the functional borehole. The survey area is dominated by mainly four layers, namely: Topsoil, weathered layer, fractured layer and Fresh basement. The topsoil resistivity values varies between 100-1200Ωm. This layer is predominantly sandy clay with an outcrop of granitic rock at VESmb6. The second and third layers within the subsurface structures are taken as the aquifer constituting of sandy soil and coarse/medium grain sand with a relatively large thickness of 65m. The Borehole was sited between VESmb3 and VESmb4. It has been functional for the past twenty nine (29) years. A critical observation of the tomogram shows that the borehole was drilled to a sufficient depth of 45m and the thickness of the aquifer which is 65m where the borehole was sited is appropriate to sustain the borehole. The depth to fresh basement rock was found to be approximately 100m as calculated from the sounding curves of the VES points.

Keywords: Borehole, Aquifer, Subsurface