Flow Induced Vibration on Piezoelectric Structures: Prediction, Experiment and Applications

https://louis.uah.edu/research-horizons/1196/thumbnail.jp

Flow Induced Vibration on Piezoelectric Structures: Prediction, Experiment and Applications

https://louis.uah.edu/vbs-posters/1168/thumbnail.jp

Flow induced vibration on piezoelectric structures : theory, characterization, and application

Harvesting energy using piezoelectric transduction has focused on vibration-based types that rely on ambient vibrations. The challenge is to identify a consistent vibration source which is essential for uninterrupted power. Wind energy can provide a reliable and sustained source of vibration to achieve these energy harvesting goals if flow-induced vibration on piezoelectric structures is carefully explored. In this dissertation, flow-induced vibration on piezoelectric structures is investigated based on the galloping piezoelectric energy harvester (GPEH) concept. A GPEH is composed of a cantilevered piezoelectric beam with a tip bluff body. Self-excited vibration is induced when the tip bluff body is subjected to airflow. Then, the piezoelectric materials can convert the mechanical energy into electrical energy. In order to understand the underlying physics, nonlinear coupled aero-electro-mechanical models are developed in which both geometric and material nonlinearities are considered. Dimensionless formulation is adopted so that it is convenient to conduct scaling and performance comparison of different galloping piezoelectric devices. Analytical approximate approach is employed to solve the nonlinear coupled equations using the Krylov-Bogoliubov method. This ensures that system parameters such as galloping velocity, limit cycle oscillation (LCO) amplitude, transient period, and harvested energy are determined accordingly and presented in an explicit form. Additionally, numerical studies are conducted using COMSOL Multiphysics. Several GPEH prototypes were fabricated. The baseline prototype is composed of a bimorph piezoelectric cantilever beam with a square cross-section bluff body. Subsequently, improved designs including addition of an impact bump stop to improve fatigue life and a bio-inspired tip bluff body borrowed from tubercles on flippers of the humpback whale. Comprehensive tests were conducted in a subsonic wind tunnel to determine system damping, electrical response, and LCO amplitude data. An optimal bump stop configuration was determined from tests that showed a significant reduction in LCO amplitude but with less effect on harvested voltage. Also, results from tests with the bio-inspired bluff body reveal the protuberances can be used as a passive control scheme to tune galloping velocity which hitherto depended on system damping and the shape of the bluff body cross-section. Moreover, measured data was used to validate model predictions. Finally, an airflow sensor prototype was developed to demonstrate an application of the GPEH concept. In summary, flow-induced vibration on piezoelectric structures is characterized in which model predictions on the GPEH were validated by experimental data with good agreement. It is expected that the current findings will advance the state-of-the-art of piezoelectric energy harvesting and lead to an innovative airflow sensor system

Neonatal Mortality and Maternal/Child Health Care in Nigeria: An Impact Analysis

Reducing the rate of mortality in neonates to as low as 12 per 1,000 live births is one of the clearly spelt out aims of the third tenet of the Sustainable Development Goals (SDG) because of its importance to the dynamics of population. While there have been various studies focused majorly on the causes, rates and determinants of neonatal mortality in Nigeria, studies on the impact of maternal/child care characteristics on neonatal mortalityand the potential implication of failing to attain the SDG target for neonatal mortality have seemingly been neglected. In this study, we undertake an analysis of the impact of maternal / child care characteristics on neonatal mortality using the logistic regression model. Results from the study showed that antenatal care (P-value = 0.000, odds ratio = 0.546 for women who visited the hospital during pregnancy on more than 5 occasions), post natal care (P-value = 0.004, odds ratio = 0.402 for women who received early neonatal care from skilled medical personnel), place ofdelivery (P-value = 0.000, odds ratio = 0.592 for babies that were delivered in a government hospital) and skill of birth attendant (P-value = 0.000, odds ratio = 0.706 for babies who were delivered by trained doctors/nurses/midwives) had significant impact on neonatal mortality at the 95% confidence level implying that improved maternal health care: before, during and immediately after delivery as well as the quality of care to motherand child are both important and necessary to the reduction of neonatal mortality in Nigeria. To achieve the sustainable development target for neonatal mortality, it is therefore recommended that stake holders in the public health sector improve the quality of existing health care facilities and access to quality services. Keywords: Neonatal mortality, logistic regression, maternal care, child health care, Nigeri

Oil Trading Products and Economic Growth in Nigeria: A Disaggregated Case

The impact of crude oil trade on economic growth has sustained a lasting debate on the Nigerian economic stage given the relevance of oil in the revenue generation capacity of the country since the advent of oil. This study examines the impact of crude oil traded goods on economic growth using annual data from 1986-2019. The study adopts the Error correction model (ECM) technique and the empirical findings from the ECM indicate that importation of automotive gas oil was significant and negatively related to economic growth in Nigeria. On the contrary, premium motor spirit import impacts economic growth positively and quite significantly in the period under review. Other variables-dual purpose kerosene and liquefied petroleum gas are also revealed to have negative and positive relationship on economic growth in Nigeria respectively, though not significant at 5% significant level. Similarly, the study further finds that oil export exhibits a hugely significant impact on economic growth in Nigeria in the period under study. Based on these findings, we recommend among others that: the Nigerian government should revamp the existing refineries to encourage domestic production to meet up with the domestic demand for petroleum products, especially for PMS. We also recommend the diversification of the economy into other oil products as well as addressing the twin issues of oil theft and insecurity in the oil-producing delta region of the Nigerian federation. Keywords: Economic growth, import, export, oil trading products, premium motor spirit   &nbsp

EXTRACTION AND EVALUATION OF OIL FROM GREEN ALGAE CLADOPHORA GLOMERATA BY HEXANE/ETHER MIXTURE

The overall aim of this study was to grow green algae Cladophora glomerata, extract oil from it, and characterize the extracted oil to gain insight into its physicochemical properties. The effects of parameters affecting the solvent extraction process, temperature, time and biomass particle size were investigated at a fixed solvent ratio of 4:1 hexane to ether. An optimization of oil separation from algae biomass via the solvent extraction method was studied. The obtained results showed that at the extraction temperature of 60 oC, extraction time of 2.5 h, and the particle size of ≤0.6 mm, the maximum oil yield was 18.3% from the process. The functional group analysis revealed the presence of alkane, esters, carboxylic acid, and unsaturated groups on the extracted oil, while the result from the fatty acid profile analysis confirmed the dominance of oleic acid. The physicochemical properties of the extracted algal oil conformed to the ASTM standard

Religious intolerance and the quest for progressive change in Nigeria

The clamour for change in Nigeria's socio-political terrain in contemporary times is a strong attestation to the fact that this country is embroiled in acute social, political and economic quagmire. One of the issues serving as obstacle to Nigeria's progress as a pluralistic polity is intolerance. There are various categories of intolerance in Nigeria. They include religious, ethnic, political, and gender intolerance, among others. More acute is religious intolerance because the metaphysical nature of religion makes it to be easily manipulated and dragged into other issues of public life. Therefore, this study investigates religious intolerance with a view to underscore how it has encumbered progressive change in Nigeria. Historical, critical, analytical and constructive methods of research were adopted for this study. Leaning on the theory of religious relativism, this paper ascertained that the issue of religious intolerance has indeed encumbered Nigeria's effort towards positive change and development in the areas of security and social stability, economic prosperity, democratic transformation and consolidation, integration of values and national unity. The author submits that for Nigerians to experience progressive change in public life, religious adherents across religious divides must demonstrate genuine attitude of tolerance towards believers of other faith traditions in the country

Ethical Concerns and Risk Perceptions Associated with the Application of Genetic Engineering

Genetics and ethics have had numerous convergences and divergences over time. One major area where genetics and ethics have connection is the application of genetic engineering research. Genetic engineering has increased significantly in recent years. The advocates of this biotechnology portrayed it as a major scientific and technological revolution in the contemporary world. Howbeit, the application of genetic engineering brings with it ethical issues. Therefore, this study examines the ethical concerns and risk perceptions associated with the application of genetic engineering with a view to ascertain the dangers and usefulness of this biotechnological advancement to the wellbeing of humanity. Data for this study was generated through secondary sources and subjected to historical, critical, content and constructive analyses. The research discovered that genetic engineering have some major problems relating to technical complexity and ethical dilemma that call for public concerns. The paper maintains that despite the aforementioned problems, there are indications that genetic engineering has the potential to improve the quality of life. Howbeit, the application of genetic engineering must be seriously guided by laws and standard ethical systems so that man will not be a victim of his own creations. Therefore, biotechnologists, medical scientists, Legal experts, social and religious ethicists and other relevant stakeholders need to engage in sincere, fruitful and meaningful dialogue to resolve the pending, technical, legal and ethical dilemma inherent in the application of genetic engineering in order to advance the moral and scientific wellbeing of humanity. Keywords: Genetics, Ethics, Genetic Engineering, Ethical Concerns, Moral and scientific wellbein

Challenges Facing the Utilization of Mobile Telephony in Learning in Some Selected Higher Institutions of Learning in Nigeria

The study investigated challenges facing the utilization of mobile telephony in learning in some selected higher institutions of learning in Nigeria. The study adopted a descriptive survey using questionnaire to collect data. The population of the study consist of 355 students which were randomly picked from some selected higher institutions of learning in Nigeria. A total of the 355questionnaires were distributed only 309 were retrieved. Descriptive statistics, (mean and percentage) were used for analysis. A mean score of 2.5 and above and a percentage score of 50% were considered for decision making. The study revealed the following as the prospects of using mobile telephony in learning as it increases academic performance, enhances learning, fostering creativity, ease communication, and provide access to vast information. The study further affirmed the challenges facing the utilization of mobile telephony in learning in some selected higher institutions of learning in Nigeria as issues of digital literacy of smartphones usage among students, issues of internet connectivity among students in higher education in Nigeria, issues of affordability of smartphones among students in higher education in Nigeria, battery-related problem, and speed-related problem. The study recommends that every institution of higher learning should make mobile telephony mandatory for all students to ease learning and the awareness of digital literacy should be spread to all students

Exponentiated Complementary Kumaraswamy-G Power Series Family of Distributions with Application to Lifetime Data

This paper proposed the Exponentiated Complementary Kumaraswamy - G Power (ECK-GP) Series family of distributions which is an extension of the Complementary Kumaraswamy-G Power Series family of distributions. The expressions for its densities, basic statistical properties and parameters estimation using the method of Maximum Likelihood were derived and established. An application of the Exponentiated Complementary Kumaraswamy Exponential Poisson (ECKEP) distribution to a real lifetime dataset clearly reveals its suitability and flexibility in fitting real life dataset