Mathematical Characterization of Biological Control of Cassava Pests Model

Pests are major constraints to the effective growth and development of every crop through their damage, and can be controlled effectively by the use of their natural enemies which is referred to as the biological pest control. In this study, the biological control model of cassava pests through optimal control theory was presented in order to minimize the population of the pests and stabilize the natural enemies population so as not to affect the crop negatively. A mathematical model was formulated via the Lotka-Volterra model, and the model was characterized. The optimality system was established, the equilibrium point with its uniqueness was established for the model. Finally, stability analysis of the model was investigated through optimal control approach and numerical data were employed to validate the system. The results obtained showed that cassava pests can be effectively controlled biologically. Keywords: Optimal control, Cassava pest, Biological control, Stability, Natural enemie

PERFORMANCE EVALUATION OF ENERGY-SAVING BULBS IN SELECTED NIGERIAN LOCATIONS WITH ARTIFICIAL NEURAL NETWORK MODELLING

The performance evaluation of energy-saving bulbs in the Nigerian market is crucial in assisting energy auditing, which is beneficial to producers and consumers of electricity. Specifically, the high-power bills issued monthly by Electricity Distribution Company in most parts of Nigeria have made Nigerians in our various domestic homes embrace the latest lighting technology that consumes less energy.In this study, lighting system data were obtained from twenty-four households from different geographical zones in Nigeria. The performance evaluation of compact fluorescent light(CFL) bulbs was investigated and the observation was predicted with artificial neural networks (ANN) to enhance informed policy formulation and decision-makingResults showed that CFL bulbs givehigh-quality light that is cost-effective and environmentally friendly. ANN predicted the observation with high accuracie

MODELLING AND OPTIMIZATION OF COEFFICIENT OF PERFORMANCE OF LOWER TEMPERATURE CYCLE OF TWO-STEP REFRIGERATION SYSTEMS

The coefficient of performance (COP) of a single-stage refrigeration system is low, thus there is a need for two-step refrigeration systems when there is a desire to have an evaporator temperature that is below -25 oC. The COP of the lower temperature cycle of the two-step refrigeration systems is a function of the COP of the refrigeration systems.This research aimed at optimizing COP of the lower temperature cycle of two-step refrigeration systems using eco-friendly refrigerants.Thermodynamic analysis of these refrigeration systems was performed by varying seven operating parameters. R-134a was used in the high-temperature cycle (HTC) and R-23 was used in the low-temperature cycle (LTC). The coefficient of performance of the lower temperature cycle (COP.REF[LTC]) of the refrigeration systems was optimized using Half Factorial Design of Design-Expert 12.0.1. The influence of the condensing temperature (TC,HTC),evaporating temperature (TE,HTC), cascade temperature difference (∆TCAS,DIFF), evaporating temperature (TE,LTC), superheating temperature (TSUP,LTC), sub-cooling temperature (TSUB,LTC), and refrigerant mass Flow rate (ṁHTC)was investigated on the values of COP.REF[LTC] of the refrigeration systems. The highest value of COP.REF[LTC] (18.1) was obtained under optimum conditions of the 30 TC,HTCoC , -40 TE,HTCoC, 0 ∆TCAS,DIFFoC, -50 TE,LTCoC, 0 TSUP,LTCoC, 20 TSUB,LTCoC and 0.01 ṁHTC kg/s.The study revealed that all the factors having interaction with TC[HTC] and TE[HTC] have a great influence on the value of COP.REF[LTC

SENSITIVITY ANALYSIS OF HYBRIDIZED WIND/PV ENERGY SYSTEM FOR POWERING TELECOMMUNICATION MAST IN LAGOS SOUTH-WEST NIGERIA

Power delivery micro-grid of hybridized wind and solar system installations keep growing worldwide. There is a great economic advantage in the use of cleaner renewable energy for power generation in the telecommunication industries, especially in remote areas. This studyanalyses the effect of three wind speed fluctuationsor levels on a hybridizedwind energy system’s electricity production for a typical three (3) BTS telecommunication mast using Hybrid Optimization Model for Energy Resources (HOMER)PRO software in Lagos south-western Nigeria as a case study. The economic implication of energy at the different wind speed levels investigated was also derived. From the obtained results, a wind speed of 4, 4.22, and 5 m/s gave an annual electric production of 39,950, 39,050, and 39,250 kWh and energy cost of 195, 192, and ₦175, respectively. This result is useful for the techno-economic operation of hybridized wind/solar system powered by three (3) BTS telecommunication masts

PERISTALTIC FLOW OF SOME SELECTED FOOD SUPPLEMENTS IN A MODELED OESPHAGUS

This paper presents thermal and hydrodynamic behaviours of some selected food supplements in a modelled oesophagus. These food supplements are orange juice and water melon juice while chyme was used as the base food supplement for comparison. Numerical method was adopted using Solid Works 2014 and Ansys fluent as working tools

Thermal Analysis of Solar Box Cooker in Omu-Aran Metropolis

Just like other solar cookers, the solar box cooker needs energy gotten from the sun to operate without producing emissions. In this research, a solar box is fabricated to reduce over-dependence on fossil fuel for energy generation. This reduces the environmental degradation caused by the use of other sources of energy. The ASHRAE empirical model was used to obtain the solar irradiance present in Omu-Aran metropolis. Thereafter, the no-load and load test was conducted to determine the cooker’s thermal performance. The tests were conducted between January 2018 and January 2019 in Landmark University, Omu-Aran, Kwara State, Nigeria with geographical coordinates 8° 8' 0" North, 5° 6' 0" East. The average energy and exergy efficiency of the cooker were 32oC and 28oC respectively. A decrease in the efficiency of the cooker was observed. This was because the reflector, which is made from aluminium foil, was degrading. As a result of this degradation caused the sun rays (radiation) to be reflected poorly into the absorber and also caused a myth of overcast sky. Meanwhile, the variation in solar radiation during the sensible heating test resulted in the fluctuation inefficiency. The ratio of water to absorber temperature which was above 0.80 during the pre-boiling heating process indicates that the cooker can be recommended for sterilization

Effects of Geometric Ratios on Heat Transfer in Heated Cylinders: Modelling and Simulation

The application of fluid and heat transfer in electronic and nuclear technology is gaining popularity, particularly in equipment's life span and risk management.  However, further study is required for applications involving rectangular cylinders placed inside a square cavity.  This study investigates the effects of height ratio  and width ratio  for Prandtl number  on natural convective heat transfer and the flow field around the annulus of a square domain fitted internally with a heated rectangular cylinder.  The square enclosure and the inner rectangular cylinder walls were respectively maintained at cold and hot isothermal conditions. COMSOL Multiphysics (Version 5.6) software was adopted to implement the governing equations and boundary conditions. The results are presented in the form of streamlines, isothermal contours, and Nusselt number (Nu). The study reveals that the combined average Nu of the rectangular cylinder walls improves with    and Rayleigh number (Ra). The maximum Nu occurred at  and ; however, height variation at peak average Nu was 37.7% greater than width variation at peak average Nu.  This study finds applications in the cooling of electronic chips and aerospace engines