Performance Analysis of a Constructed Dual Axis Solar Tracker

A major drawback to photovoltaic system is the fact that solar cells become useless at night. In the quest to overcome this, use of batteries, converters, backup generator and addition of extra panels at higher cost to PV grid have been proposed but the performance of the system with integration of the said components is still very much dependent how much solar energy directly reach the solar cell surface. A feasible approach to achieve this is solar tracking. In this study, performance evaluation of a constructed dual axis solar tracker integrated PV system was carried out for five weeks and compared with that of a flat fixed PV system installed at Ogbomoso, Nigeria (8° 08’ N, 4° 16’ E). It was discovered that the power and performance of dual axis system obtained averagely was 62.91 W compared to that of flat fixed PV System which was 47.88 W thereby improving the power output by 31.4%. Keywords: Solar Energy, Dual Axis System, Photovoltaic, Performance, Tropical region, Nigeria. DOI: 10.7176/APTA/75-0

Electro-Optical Characterization of Stannous Oxide Based Conductive Glass Fabricated Locally with Stannous Chloride Dihydrate Precursor

Most commercially available conductive oxides such as indium doped tin oxide (ITO) and fluorine doped tin oxide (FTO) are expensive. This has made local production of alternative oxides necessary. This work demonstrates local production of transparent conducting stannous oxide (SnO) film via thermal decomposition of stannous chloride dihydrate (SnCl2·2H2O). The films were then characterized optically and electrically using UV/VIS spectrophotometer and four point probe, respectively. The thickness of the film increased linearly with precursor mass. While the sheet resistance and optical transmittance decreased, the optical absorbance increased with increased thickness. Average optical transmittance ranged between 85% and 94% and the sheet resistance lies between 62.89 Ω/sq and 84.57 Ω/sq. With these characteristics, the deposited film will be useful for optoelectronic applications

MONTE CARLO SIMULATIONS FOR UNCERTAINTY QUANTIFICATION: MATHEMATICAL FOUNDATION AND IMPLICATION OF UNDERLYING ASSUMPTIONS

Many problems in petroleum engineering involve solving multivariable complex integrals and analytic calculation is rarely possible in most practical cases. Numerical approximation appears to be practicable. However, majority of existing numerical solution of a D–dimensional integral with a relative accuracy (ϵ) requires a computation time proportional to ϵ-D. Hence, the use of Ordinary Monte Carlo simulation (OMCS) in uncertainty quantification has gained tremendous attention. In reality, when historical data is available, variables are not independent and identically distributed (iid). The direct sampling of variable under this condition is not expected to be easy and use of OMCS can be erroneous. Methods based on Markov Chains will offer reasonable solution to this problem. This study evaluates simulation methods for quantifying uncertainty in reservoir forecast. The implications of underlying mathematics and assumptions that characterizes them were covered. The p5-p10–p50–p90-p95 uncertainty envelopes from different methods were presented using a case study from Niger Delta. The result is useful for identification and selection of effective tools in uncertainty quantification in the oil industry

Africa’s response to the COVID-19 pandemic : A review of the nature of the virus, impacts and implications for preparedness

Background: COVID-19 continues to wreak havoc in different countries across the world, claiming thousands of lives, increasing morbidity and disrupting lifestyles. The global scientific community is in urgent need of relevant evidence, to understand the challenges and knowledge gaps, as well as the opportunities to contain the spread of the virus. Considering the unique socio-economic, demographic, political, ecological and climatic contexts in Africa, the responses which may prove to be successful in other regions may not be appropriate on the continent. This paper aims to provide insight for scientists, policy makers and international agencies to contain the virus and to mitigate its impact at all levels. Methods: The Affiliates of the African Academy of Sciences (AAS), came together to synthesize the current evidence, identify the challenges and opportunities to enhance the understanding of the disease. We assess the potential impact of this pandemic and the unique challenges of the disease on African nations. We examine the state of Africa’s preparedness and make recommendations for steps needed to win the war against this pandemic and combat potential resurgence. Results: We identified gaps and opportunities among cross-cutting issueswhich must be addressed or harnessed in this pandemic. Factors such as the nature of the virus and the opportunities for drug targeting, point of care diagnostics, health surveillance systems, food security, mental health, xenophobia and gender-based violence, shelter for the homeless, water and sanitation, telecommunications challenges, domestic regional coordination and financing. Conclusion: Based on our synthesis of the current evidence, while there are plans for preparedness in several African countries, there are significant limitations. A multi-sectoral efforts from the science, education, medical, technology, communication, business, and industry sectors, as well as local communities, must work collaboratively to assist countries in order to win this fight

Genome-Wide Meta-Analysis of Five Asian Cohorts Identifies PDGFRA as a Susceptibility Locus for Corneal Astigmatism

Corneal astigmatism refers to refractive abnormalities and irregularities in the curvature of the cornea, and this interferes with light being accurately focused at a single point in the eye. This ametropic condition is highly prevalent, influences visual acuity, and is a highly heritable trait. There is currently a paucity of research in the genetic etiology of corneal astigmatism. Here we report the results from five genome-wide association studies of corneal astigmatism across three Asian populations, with an initial discovery set of 4,254 Chinese and Malay individuals consisting of 2,249 cases and 2,005 controls. Replication was obtained from three surveys comprising of 2,139 Indians, an additional 929 Chinese children, and an independent 397 Chinese family trios. Variants in PDGFRA on chromosome 4q12 (lead SNP: rs7677751, allelic odds ratio = 1.26 (95% CI: 1.16–1.36), Pmeta = 7.87×10−9) were identified to be significantly associated with corneal astigmatism, exhibiting consistent effect sizes across all five cohorts. This highlights the potential role of variants in PDGFRA in the genetic etiology of corneal astigmatism across diverse Asian populations

A year of genomic surveillance reveals how the SARS-CoV-2 pandemic unfolded in Africa

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The evolving SARS-CoV-2 epidemic in Africa: insights from rapidly expanding genomic surveillance

Investment in SARS-CoV-2 sequencing in Africa over the past year has led to a major increase in the number of sequences generated, now exceeding 100,000 genomes, used to track the pandemic on the continent. Our results show an increase in the number of African countries able to sequence domestically, and highlight that local sequencing enables faster turnaround time and more regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and shed light on the distinct dispersal dynamics of Variants of Concern, particularly Alpha, Beta, Delta, and Omicron, on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve, while the continent faces many emerging and re-emerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Emergence and spread of two SARS-CoV-2 variants of interest in Nigeria.

Identifying the dissemination patterns and impacts of a virus of economic or health importance during a pandemic is crucial, as it informs the public on policies for containment in order to reduce the spread of the virus. In this study, we integrated genomic and travel data to investigate the emergence and spread of the SARS-CoV-2 B.1.1.318 and B.1.525 (Eta) variants of interest in Nigeria and the wider Africa region. By integrating travel data and phylogeographic reconstructions, we find that these two variants that arose during the second wave in Nigeria emerged from within Africa, with the B.1.525 from Nigeria, and then spread to other parts of the world. Data from this study show how regional connectivity of Nigeria drove the spread of these variants of interest to surrounding countries and those connected by air-traffic. Our findings demonstrate the power of genomic analysis when combined with mobility and epidemiological data to identify the drivers of transmission, as bidirectional transmission within and between African nations are grossly underestimated as seen in our import risk index estimates

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance.

Investment in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing in Africa over the past year has led to a major increase in the number of sequences that have been generated and used to track the pandemic on the continent, a number that now exceeds 100,000 genomes. Our results show an increase in the number of African countries that are able to sequence domestically and highlight that local sequencing enables faster turnaround times and more-regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and illuminate the distinct dispersal dynamics of variants of concern-particularly Alpha, Beta, Delta, and Omicron-on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve while the continent faces many emerging and reemerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century