Review of Researches on Techno-Economic Analysis and Environmental Impact of Hybrid Energy Systems

Hybrid energy systems, which are combinations of two or more renewable and non-renewable energy sources, have been identified as a viable mechanism to address the limitations of a single renewable energy source, utilized for electricity generation. In view of this, several research works have been carried out to determine the optimal mix of different renewable and non-renewable energy resources used for electricity generation. This paper presents a comprehensive review of the optimization approaches proposed and adopted by various authors in the literature for optimal sizing of hybrid energy systems. It is observed that the objective functions - considered by a large percentage of researchers to optimize the sizing of hybrid energy systems - are cost minimization of the generated electricity, system reliability enhancement and environmental pollution reduction. Other factors covered in the literature are equally discussed in this article. Similarly, simulation and optimization software used for the same purpose are covered in the paper. In essence, the main aim of this paper is to provide a scope into the works that have been carried out in the field of hybrid energy systems, used for electricity generation with the view to informing researchers and members of the public alike, on trends in methods applied in optimal sizing of hybrid energy systems. It is believed that the information provided in this paper is very crucial in advancing research in the field

Environmental Impact of Lumber Production using Life Cycle Assessment: A Case Study of the Production System in South-west Nigeria

Life Cycle Assessment (LCA) is a decision support tool that can be used to evaluate the potential environmental impact of a product system. Environmental impact associated with the production of (0.0508×0.1524×3.6576) m lumber referred to as “2by6” in the primary wood industry was evaluated. This assessment is a cradle to gate system with boundaries spanning from the point of raw material extraction in Osun state, to transportation of the lumber product to wood market in Ibadan, Oyo state. The study compared four production scenarios by varying haulage distance and energy source during production at two sawmill facilities located in Ife and Ikire in Osun state. Data obtained from the production system were analysed using GaBi6 software to estimate and classify the emissions into five impact categories. Life Cycle Impact Assessment result (LCIA) showed that Acidification Potential (AP), Global Warming Potential (GWP) and Smog Potential (SP) were the most significant impact indicators observed in the four production scenarios. AP (2.883, 3.352, 3.483, 3.951) kg H+ mole-Equiv, GWP (13.25, 14.44, 15.45, 16.65) kg CO2-Equiv and SP (1.86, 2.15, 2.24, 2.53) kg O3-Equiv. Scenario 4 which involved a longer transportation distance and employed a diesel generator for the milling process showed the least environmental performance. Processes that contributed significant impact were wood waste disposal method employed and the secondary transportation processes during logging activities. In order to achieve a better production system, practices that encourage less waste generation and the use of renewable energy were recommended.Keywords— LCA, lumber production, environmental impact, wood wast

A steepest descent algorithm for the optimal control of a cascaded hydropower system

Optimal power generation along the cascaded Kainji-Jebba hydroelectric power system had been very difficult to achieve. The reservoirs operating heads are being affected by possible variation in impoundments upstream, stochastic factors that are weather-related, availability of the turbo-alternators and power generated at any time. Proposed in this paper, is an algorithm for solving the optimal release of water on the cascaded hydropower system based on steepest descent method. The uniqueness of this work is the conversion of the infinite dimensional control problem to a finite one, the introduction of clever techniques for choosing the steepest descent step size in each iteration and the nonlinear penalty embedded in the procedure. The control algorithm was implemented in an Excel VBA® environment to solve the ormulated Lagrange problem within an accuracy of 0.03%. It is recommended for use in system studies and control design for the optimal power generation in the cascaded hydropower system

Antipsychotics-related hyperprolactinaemia among patients with schizophrenia in Maiduguri

Background: Hyperprolactinaemia among patients on antipsychotic medications is generally overlooked due to lack of outwardly visible symptoms, patient resistance to reporting because the symptoms are perceived as shameful, or to clinician’s insufficient knowledge. Aim: The study aimed to evaluate the patterns and correlates of hyperprolactinemia among patients with schizophrenia on antipsychotic medications. Setting: The study was conducted in a psychiatric facility in Maiduguri, Northeastern Nigeria. Methods: A total of 209 patients with schizophrenia were evaluated through a cross-sectional design and assayed for serum prolactin with ELISA Kits. Frequencies and percentages were tabulated for categorical variables. Variables with significant associations with hyperprolactinaemia on chi-square (p  0.05) were subjected to logistic regression analysis. Results: The prevalence of hyperprolactinaemia was 45.9% in all patients on antipsychotic medication. The prevalence because of the use of typical and atypical antipsychotics was 51.5% and 25.0%, respectively. Hyperprolactinaemia was significantly associated with typical antipsychotics (β = 0314, p = 0.002), high overall drug dosage (β = 2.340, p = 0.003), high-dose typical antipsychotics (β = 3.228, p = 0.000), twice daily dosing frequency (β = 2.751, p = 0.001) and polypharmacy (β = 1.828, p = 0.0024). Conclusion: The findings support that patients on typical, high-dose antipsychotic medications and polypharmacy have a high prevalence of hyperprolactinaemia. As hyperprolactinaemia is often undetectable, screening and patient psycho-education on the significance of the signs and symptoms of hyperprolactinaemia is required for necessary clinical intervention. Contribution: The study provides evidence for the rational use of antipsychotic medications in sub-Saharan Africa

Substance Use: Prevalence, Pattern and Risk Factors among Undergraduate Students in a Tertiary Institution in Southwest Nigeria

Background: Substance use is a global public health problem with increasing burden among university students. This study assessed the prevalence, pattern and risk factors of substance use among undergraduate students of Afe Babalola University, Ado-Ekiti, Nigeria.Methods: This was a cross-sectional study of undergraduate students of Afe Babalola University, Ado-Ekiti. A multi-stage sampling technique was used to select respondents. Data collection tool was a structured self-administered questionnaire. Data analysis was done using Statistical Package for the Social Sciences (SPSS) version 23. Statistical significance was set at p value <0.05Results: The respondents’ mean age was 19.5 ± 2.0 years and all 416 (100.0%) were aware of substance abuse. The prevalence of substance use was 299 (71.9%). Alcohol 133 (32.0%) and over-the-counter drugs (29.9%) were the two most commonly used substance. Being male (p=0.017) and in 400 level (p=0.047) were associated with substance use while curiosity 112 (37.5%), peer pressure 95 (31.8%) and school stress 85 (28.4%) were reasons given. Predictors of substance use were being a female (aOR: 2.54; 95% CI=1.89-3.66; p=0.011), civil servant mother (aOR: 5.75; 95% CI=1.90-17.4; p=0.002) and mother with secondary education (aOR: 5.27; 95% CI= 2.20- 12.65; p<0.001).Conclusion: There was high prevalence of substance use with curiosity, peer pressure and school stress being influencers of substance use among the study population. Predictors of substance use were being a female, civil servant mother and mother with secondary education. The University authority should institute measures to prevent access to alcohol and other substances by the students

A NON-LINEAR FILTERING APPROACH TO RIDGE AND FURROW SEGMENTATION OF FINGERPRINTS

Ridge and furrow segmentation or ridge extraction is an important processing step in automatic fingerprint identification; as its success simplifies the task of tracing the most distinguishing features of the print, the ridge ends and bifurcations. In this work, a new method for ridgeextraction in fingerprints is proposed. The method uses normalisation, local histogram equalisation, median filtering and global thresholding to segment the fingerprint foreground into ridges and furrows. The result obtained shows that the new algorithm is robust to image noise. It is also less computationally demanding when compared with an earlier ridge detection scheme

Influence of various sacrificial reagents on congo red degradation and H₂O₂ production based on heteroanionic titanium oxycarbide photocatalyst and its mechanism

Combining a rational design strategy with a simple synthetic method to produce an eco-friendly material presents a unique challenge in photocatalysis technology. This work reports the successful synthesis of a heteroanionic titanium oxycarbide photocatalyst—TiO0.25C0.75 (TiOC) via a solid-state reaction and employed for the decomposition of Congo red (CR) and H2O2 generation from water under visible light radiation. Initially, TiOC demonstrated a moderate CR degradation efficiency of 54% (1 g/L) in 120 min and evolved a minimal amount of H2O2 after 90 min (2 mmol) and 120 min (10 mmol) of light exposure. This clearly indicates that the localization of hybridization of O-2p and C-2p orbitals and a more positive conduction band edge (CB) of TiOC lead to reduced carrier mobility and, consequently, high recombination of photogenerated charge carriers. Therefore, sacrificial reagents such as H2O2 and isopropyl alcohol (ISA) were employed to improve CR removal and H2O2 evolution rate, resulting in 70% and 21.5 mmol (120 min), respectively

Multi-metals column adsorption of lead(II), cadmium(II) and manganese(II) onto natural bentonite clay

The present work was aimed at evaluating the multi-metals column adsorption of lead(II), cadmium(II) and manganese(II) ions onto natural bentonite. The bentonite clay adsorbent was characterized for physical and chemical properties using X-ray diffraction, X-ray fluorescence, Brunauer-Emmett-Teller surface area and cation exchange capacity. The column performance was evaluated using adsorbent bed height of 5.0 cm, with varying influent concentrations (10 mg/L and 50 mg/L) and flow rates (1.4 mL/min and 2.4 mL/min). The result shows that the breakthrough time for all metal ions ranged from 50 to 480 minutes. The maximum adsorption capacity was obtained at initial concentration of 10 mg/L and flow rate of 1.4 mL/min, with 2.22 mg/g of lead(II), 1.71 mg/g of cadmium(II) and 0.37 mg/g of manganese(II). The order of metal ions removal by natural bentonite is lead(II) > cadmium(II) > manganese(II). The sorption performance and the dynamic behaviour of the column were predicted using Adams-Bohart, Thomas, and Yoon-Nelson models. The linear regression analysis demonstrated that the Thomas and Yoon-Nelson models fitted well with the column adsorption data for all metal ions. The natural bentonite was effective for the treatment of wastewater laden with multi-metals, and the process parameters obtained from this work can be used at the industrial scale

Knowledge, attitude and practice of hospital waste disposal among cleaners in a tertiary health institution in Plateau State, Nigeria

Background: Hospital waste disposal has become an important public health concern especially in low and middleincome countries.  Health hazards could occur where there are inadequate and improper techniques in handling these wastes. The aim of this study was to assess the knowledge, attitude and practice of hospital waste disposal among cleaners in a tertiary hospital of Plateau State, Nigeria.Method: This was a cross-sectional study carried out among 206 cleaners. Data was collected using a semi-structured interviewer-administered questionnaire. Knowledge, attitude and practice were all graded and scored. Analysis was done using Epi Info version 3.5.4 at a confidence level of 95% and pvalue of < 0.05.Results: The mean age of respondents was 36.9 ± 9.5 years. The highest level of education was secondary school among 110 (54%) of them and 169 (82%) had been working for =10 years. Knowledge, attitude and practice was good among 83 (41%), 203 (98%) and 17 (8.3%) of respondents respectively. Knowledge grade and previous training were found to have a statistically significant relationship with practice on biomedical waste disposal (p < 0.05).Conclusion: The study revealed a lack of knowledge and poor practice of hospital waste disposal among hospital cleaners though with most having a good attitude. The hospital needs to train and retrain hospital cleaners, adopt and enforce guidelines specific for their use on medical waste disposal