69 research outputs found

    Predictive Maintenance of Critical Equipment for Floating Liquefied Natural Gas Liquefaction Process

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    Predictive Maintenance of Critical Equipment for Liquefied Natural Gas Liquefaction Process Meeting global energy demand is a massive challenge, especially with the quest of more affinity towards sustainable and cleaner energy. Natural gas is viewed as a bridge fuel to a renewable energy. LNG as a processed form of natural gas is the fastest growing and cleanest form of fossil fuel. Recently, the unprecedented increased in LNG demand, pushes its exploration and processing into offshore as Floating LNG (FLNG). The offshore topsides gas processes and liquefaction has been identified as one of the great challenges of FLNG. Maintaining topside liquefaction process asset such as gas turbine is critical to profitability and reliability, availability of the process facilities. With the setbacks of widely used reactive and preventive time-based maintenances approaches, to meet the optimal reliability and availability requirements of oil and gas operators, this thesis presents a framework driven by AI-based learning approaches for predictive maintenance. The framework is aimed at leveraging the value of condition-based maintenance to minimises the failures and downtimes of critical FLNG equipment (Aeroderivative gas turbine). In this study, gas turbine thermodynamics were introduced, as well as some factors affecting gas turbine modelling. Some important considerations whilst modelling gas turbine system such as modelling objectives, modelling methods, as well as approaches in modelling gas turbines were investigated. These give basis and mathematical background to develop a gas turbine simulated model. The behaviour of simple cycle HDGT was simulated using thermodynamic laws and operational data based on Rowen model. Simulink model is created using experimental data based on Rowen’s model, which is aimed at exploring transient behaviour of an industrial gas turbine. The results show the capability of Simulink model in capture nonlinear dynamics of the gas turbine system, although constraint to be applied for further condition monitoring studies, due to lack of some suitable relevant correlated features required by the model. AI-based models were found to perform well in predicting gas turbines failures. These capabilities were investigated by this thesis and validated using an experimental data obtained from gas turbine engine facility. The dynamic behaviours gas turbines changes when exposed to different varieties of fuel. A diagnostics-based AI models were developed to diagnose different gas turbine engine’s failures associated with exposure to various types of fuels. The capabilities of Principal Component Analysis (PCA) technique have been harnessed to reduce the dimensionality of the dataset and extract good features for the diagnostics model development. Signal processing-based (time-domain, frequency domain, time-frequency domain) techniques have also been used as feature extraction tools, and significantly added more correlations to the dataset and influences the prediction results obtained. Signal processing played a vital role in extracting good features for the diagnostic models when compared PCA. The overall results obtained from both PCA, and signal processing-based models demonstrated the capabilities of neural network-based models in predicting gas turbine’s failures. Further, deep learning-based LSTM model have been developed, which extract features from the time series dataset directly, and hence does not require any feature extraction tool. The LSTM model achieved the highest performance and prediction accuracy, compared to both PCA-based and signal processing-based the models. In summary, it is concluded from this thesis that despite some challenges related to gas turbines Simulink Model for not being integrated fully for gas turbine condition monitoring studies, yet data-driven models have proven strong potentials and excellent performances on gas turbine’s CBM diagnostics. The models developed in this thesis can be used for design and manufacturing purposes on gas turbines applied to FLNG, especially on condition monitoring and fault detection of gas turbines. The result obtained would provide valuable understanding and helpful guidance for researchers and practitioners to implement robust predictive maintenance models that will enhance the reliability and availability of FLNG critical equipment.Petroleum Technology Development Funds (PTDF) Nigeri

    Towards an Interdisciplinary Approach to Food Accessibility Research

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    An approximately 54.4 million people or 17.7% of the U.S population live in areas without nutritious food outlets, have low access to a vehicle and have challenges accessing a nutritious food outlet. The lack of access to nutritious food outlets mainly affects low-income residents of both urban and rural areas and remains a challenge because the deprived residents mostly depend on innutritious food outlets such as neighborhood convenience stores, which can be detrimental to their health. Researchers of varying disciplines have examined the problem of food access, however, in a piecemeal nature. This paper, therefore, critically examines research across two disciplines concerned with food accessibility - geography and public health to create a more comprehensive approach to food accessibility research based on their perspectives and approaches. Although some dissimilarities exist between the perspectives and approaches employed in food accessibility research by the two disciplines, common grounds are established via the identification of the concept of place and socio-economic characteristics of people as the main driving factors of food accessibility research among the disciplines.These perspectives are integrated along the common driving elements to form an interdisciplinary research approach and construct a comprehensive understanding of the problem of food accessibility

    Assessment of the Service Performance of Zakah Institutions in Gombe Metropolis, Nigeria

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    Zakah is an important tool in Islamic economic system, it plays a crucial role in reducing some social and economic problems such as poverty, unemployment, indebtedness and inequitable redistribution of income in the Muslim communities. The Zakah institutions in Gombe metropolis are said to practice favouritism and unfair service quality and distribution of Zakah funds among recipients. The main objective of this study is to empirically examine perception of the Zakah recipients towards the services provided by the institutions. This study adopted descriptive survey design approach. PLS-SEM is employed to test the hypothesized model of the study. The result reveals that reliability, responsiveness and assurance significantly affect performance of Zakah institutions but tangibility and empathy were found to be insignificant. The study recommends the need for Zakah institutions in Gombe metropolis to consider improving the tangibles and empathy dimensions of service quality. The study also recommends the need to concentrate on the antecedents of service quality as it will assist Zakah institutions to improve performance. Lastly, the study suggests the establishment of Zakah board that will serve as regulatory body in charge of supervising the activities of private  Zakah institutions in Gombe state

    A Smart Real-Time Standalone Route Recognition System for Visually Impaired Persons

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    Visual Impairment is a common disability that results in poor or no eyesight, whose victims suffer inconveniences in performing their daily tasks. Visually impaired persons require some aids to interact with their environment safely. Existing navigation systems like electronic travel aids (ETAs) are mostly cloud-based and rely heavily on the internet and google map. This implies that systems deployment in locations with poor internet facilities and poorly structured environments is not feasible. This paper proposed a smart real-time standalone route recognition system for visually impaired persons. The proposed system makes use of a pedestrian route network, an interconnection of paths and their associated route tables, for providing directions of known locations in real-time for the user. Federal University of Technology (FUT), Minna, Gidan Kwanu campus was used as the case study. The result obtained from testing of the device search strategy on the field showed that the complexity of the algorithm used in searching for paths in the pedestrian network is , at worst-case scenario, where N is the number of paths available in the network. The accuracy of path recognition is 100%. This implies that the developed system is reliable and can be used in recognizing and navigating routes by the visual impaired in real-time

    Forecasting Human Development Index With Double Exponential Smoothing Method And Acorrect Determination

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    Human development is now seen as a measure of the success of the development of a nation which is closely related to the economic, social, cultural, political and environmental fields. The success of human development is measured based on the Human Development Index (IPM). Boyolali Regency is one of the regencies in Central Java Province which has diverse and abundant natural resources. The large potential of natural resources owned should be in line with the quality of human development. However, it turns out that this is not in line with the HDI value of Boyolali Regency which is still below the average HDI value of Central Java. So that the Boyolali government continues to strive to maximize the potential and increase the HDI value. Based on this, it is necessary to do forecasting as a reference to maximize the level of human development in Boyolali Regency in the next few years. In this study, HDI forecasting in Boyolali Regency was carried out using the Double Exponential Smoothing method from Brown with the data used is HDI data in Boyolali Regency from 2011 to 2021. The data used was obtained from the Central Bureau of Statistics (BPS) Boyolali Regency. HDI forecasting was also carried out using the arithmetical method, and the best forecasting results were compared between the two methods based on the mean absolute percentage error (MAPE). Forecasting results using the Double Exponential Smoothing method produce the best alpha smoothing parameter values of 0.91 and MAPE values of 0.4061%. Meanwhile, using the arithmetic series method, the MAPE is 0.4704%. Both methods produce MAPE values with very good criteria, so that both methods can be used for forecasting. However, based on the criteria for the smallest MAPE value, the Double Exponential Smoothing method is used. The results of the HDI forecasting using the Double Exponential Smoothing method for 2022, 2023 and 2024 are 74.61, 74.81 and 75.02 respectively. While the results of forecasting with arithmetical method for the same years are 74.93, 75.45, and 75.98

    Impact of Population Growth on Unemployment in Nigeria: Dynamic OLS Approach

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    This empirical research examined the impact of population growth on unemployment in Nigeria. The study applied annual time series data from 1991 to 2017. The data on population, unemployment, consumer price index, exchange rate and foreign direct investment were tested for unit root using ADF, PP and KPSS unit root tests. The results from the ADF and PP tests revealed that all the variables were stationary at first difference except CPI that is stationary at level. While the KPSS units root test result shows that all the variables are stationary at level. The variables were co-integrated as shown by the Johansen Juselius test for co-integration. The Dynamic Ordinary Least Squares (DOLS) were used in the process of estimating the model. The main results disclosed that population and exchange rate impacted positively with unemployment. Whereas consumer price index, GDP per capita and foreign direct investment impacted negatively thereby reducing the rate of unemployment in the long-run. Government should focus more on attracting foreign direct investment, increasing GDP per capita and the desired rate of consumer price index in order to control the rate of unemployment in the country. Keywords: Population Growth, Unemployment, Dynamic Ordinary Least Squares, Co-integration test, GDP per capita, Consumer Price Index, Foreign Direct Investment. DOI: 10.7176/JESD/10-22-09 Publication date: November 30th 2019

    Insilico analysis of binding interactions and evaluation of mode of action of hydroxy tyrosol on candida albicans I, ii and parapsilosis

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    This work was aimed at purifying the most potent antibiofilm principle from Acalypha wilkesiana leaves against Candida species, analyzing its binding interactions with the molecular targets and evaluating its mode of action. Bioassay guided fractionation was carried and purification of the most potent fraction was achieved by Preparative -TLC. Proton NMR -spectroscopy was used to elucidate the structure of the most potent fraction which was hydroxy tyrosol (HT). There was significant (p < 0.05) increase in the IC50 of HT and caspafungin in the presence of sorbitol. In the presence of ergosterol, there was no significant (p > 0.05) increase in the IC50 of HT but there was significant (p < 0.05) increase in the IC50 of voriconazole. Insilico molecular studies revealed a good docking score (-7.7 and 4 hydogen bonds) with glucan synthase and (7.0 and 1 hydrogen bond) with lanosterole-14α- demethylase. The mode of action of HT is most likely by inhibiting the activities of β-1,3-D glucan synthase. The Significant increase in IC50 of HT in the presence of sorbitol showed that its inhibition leads to depletion of cell wall glucan and subsequent lysis of fungal cells

    Evaluation of some Varieties of Okra (Abelmoschusesculentus) Seed Oil for Consumption and Industrial Uses

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    The demand for seeds oil is rapidly increasing due to the growth of the human population and the resulting increase in its consumption for both domestic and industrial uses. Hence, seed oils from three okra (Abelmoschusesculentus) varieties – Clemson spineless, ex-Samaru and NHAE-74 were extracted and their physicochemical properties were analysed and compared with some conventional seed oils. The percentage oil yield of the seeds determined for NHAE-74 (25.67±0.58 %) is significantly higher (p < 0.05) than Clemson spineless  (24.33±0.29 %) and ex-Samaru (23.05±0.50 %). The acid value (3.65±0.02, 1.96±0.01 and 2.24±0.02 mgKOH/g), Iodine Value (114.59±0.01,110.97±0.02 and 111.67±0.02 mg/100g) and Saponification value (122.02±0.19, 130.43±0.04 and 124.82±0.02 meqKOH/kg) of Clemson  spineless, ex-Samaru and NHAE-74, respectively differ significantly (p < 0.05) among the three varieties, while the peroxide value  (meqKOH/kg) of Clemson spineless (3.92±0.14) is significantly lower (p < 0.05) than the values of NHAE-74 (5.33±0.14) and ex-Samaru (5.00±0.25). The results further showed that the seed oil has a quality comparable to those of conventional oils and has great nutritional and industrial potentials

    Changing patterns of cataract services in North-West Nigeria: 2005-2016.

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    PURPOSE: This study was conducted to assess the impact of the eye care programme on cataract blindness and cataract surgical services in Sokoto, Nigeria over a 12 year period 2005-2016. METHODS: Data from the 2005 population based cross-sectional study of blindness in Sokoto state was re-analysed to obtain baseline estimates of the prevalence of cataract blindness and cataract surgical coverage for persons 50 years and over in Wurno health zone. A population based survey of a representative sample of persons 50 years and over in Wurno health zone was conducted in July 2016. Data on eye health workforce, infrastructure and cataract surgical services between 2005 and 2016 were analysed from relevant documents. RESULTS: In 2005 the unadjusted prevalence of bilateral cataract blindness (<3/60) in people 50 years and over in Wurno health zone was 5.6% (95% CI: 3.1, 10.1). By 2016 this had fallen to 2.1% (95% CI 1.5%, 2.7%), with the age-sex adjusted prevalence being 1.9% (95% CI 1.3%, 2.5%). The CSC for persons with visual acuity <3/60, <6/60, <6/18 for Wurno health zone was 9.1%, 7.1% and 5.5% respectively in 2005 and this had increased to 67.3%, 62.1% and 34.7% respectively in 2016. The CSR in Sokoto state increased from 272 (1005 operations) in 2006, to 596 (2799 operations) in 2014. In the 2005 survey, couching (a procedure used by traditional practitioners to dislocate the lens into the vitreous cavity) accounted for 87.5% of all cataract interventions, compared to 45.8% in the 2016 survey participants. In 2016 18% of eyes having a cataract operation with IOL implantation had a presenting visual acuity of <6/60 (poor outcome) with the main causes being postoperative complications (53%) and uncorrected refractive error (29%). CONCLUSION: Between 2005 and 2016 there was a doubling in cataract surgical rate, a 7 times increase in cataract surgical coverage (<3/60), and a decrease in cataract blindness and the proportion of eyes being couched. However, there remains a high prevalence of un-operated cataract in 2016 indicating a need to further improve access to affordable and good quality cataract surgical services
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