Strain and Temperature Sensing Properties of Multiwalled Carbon Nanotube Yarn Composites

Strain and temperature response of Multiwalled Carbon Nanotube (MWCNT/CNT) yarns on a stainless steel test beam has been studied. The carbon nanotube yarns are spun from a multiwalled carbon nanotube forest grown on a silicon substrate to a 4-ply yarn with a diameter of about 15-20 microns. Four of the 4-ply CNT yarns are arranged in a Wheatstone bridge configuration on the stainless steel test beam using a thin layer of polyurethane resin that insulates and protects the yarns from the test beam. Strain sensitivities of the CNT yarn sensors range from 1.39 to 1.75 mV/V/1000 microstrain at room temperature, and temperature sensitivity of the CNT yarn bridge is 91 microA/degC. Resistance of the yarns range from 215 to 270 ohms for CNT yarn length of approximately 5 mm. Processes used in attaching the CNT yarns on the test beam and experimental procedures used for the measurements are described. Conventional metallic foil strain gages are attached to the test beam to compare with the CNT sensors. The study demonstrates multifunctional capability of the sensor for strain and temperature measurements and shows its applicability where engineering strain is less than 3%

Application of Three Electrical Resistivity Arrays to Evaluate Resolution Capacity of Fractured Zones at Apatara Farms, Iwo, Osun State, Nigeria

The study applied three different electrical resistivity arrays (Wenner, dipole-dipole, and Pole-dipole) based on their resolution capacity to delineate fractured zones at Apatara Farm in Iwo, Osun State, Nigeria. Theoretical apparent resistivity data were computed for each model and contaminated with 5% Gaussian noise as a further concession to real field conditions. The simulated results revealed that the Wenner array gave the least error in trying to reconstruct the true model when the fractured zone is placed near the subsurface. However, when the fractured zone is placed at a depth beyond 5 m, the Dipole-Dipole array gave a better resolution than Pole-Dipole and Wenner array in decreasing order of resolution. The study further revealed that the Wenner array is less susceptible to edge effect at shallow depth while Dipole-dipole is more susceptible to edge effect at deeper depth followed by the Pole-dipole array. 2D electrical resistivity field measurements were carried out to confirm the results of the numerical simulation in the same field using the same parameters. The inverted resistivity images showed that the fractured zones are well delineated by the Dipole-dipole and Pole-dipole arrays but poorly resolved by the Wenner array. The study has demonstrated the usefulness of numerical modelling for imaging of fractured zone necessary for hydrogeological purpose and through modelling, the user has unlimited power to image or simulate a real-world scenario seamlessly before carrying out the actual field survey.Keywords: Electrical resistivity array; fractured zones; finite element method; 2-D models; resolution, mean absolute erro

Towards Multifunctional Characteristics of Embedded Structures With Carbon Nanotube Yarns

This paper presents recent results on research of achieving multifunctional structures utilizing Carbon Nanotube (CNT) yarns. The investigation centers on creating composite structures with CNT yarns to simultaneously achieve increases in mechanical strength and the ability to sense strain. The CNT yarns used in our experiments are of the single-ply and two-ply variety with the single-ply yarns having diameters on the order of 10-20 m. The yarns are embedded in silicon rubber and polyurethane test specimens. Mechanical tests show an increase in modulus of elasticity, with an additional weight increase of far less than one-percent. Sensing characteristics of the yarns are investigated on stainless steel test beams in an electrical bridge configuration, and are observed to have a strain sensitivity of 0.7mV/V/1000 micro-strain. Also reported are measurements of the average strain distribution along the direction of the CNT yarns on square silicon rubber membranes

Influence of Power Quality Problem on the Performance of an Induction Motor

This paper presents the application of MATLAB® Simulink as a useful tool for predicting the performance of an induction motor. The influence of power quality problem on the performance of an induction motor is critically investigated. Mathematical modelling of an induction motor subjected to an unsymmetrical voltage conditions are presented. The results obtained from the simulation reveal the presence of rotor noise and vibration during operation of induction motor under voltage unbalance

Multifunctional Characteristics of Carbon Nanotube (CNT) Yarn Composites

By forming composite structures with Carbon Nanotube (CNT) yarns we achieve materials capable of measuring strain and composite structures with increased mechanical strength. The CNT yarns used are of the 2-ply and 4-ply variety with the yarns having diameters of about 15-30 micrometers. The strain sensing characteristics of the yarns are investigated on test beams with the yarns arranged in a bridge configuration. Additionally, the strain sensing properties are also investigated on yarns embedded on the surface of a flexible membrane. Initial mechanical strength tests also show an increase in the modulus of elasticity of the composite materials while incurring a weight penalty of less than one-percent. Also presented are initial temperature characterizations of the yarns

Prognostic Roles of C-Reactive Protein and Erythrocyte Sedimentation Rate As Acute Phase Reactants in Mentally Challenged Subjects

Background: A mental disorder is a psychiatric disease that presents as mild or severe disturbances in a person’s behavior, mood, or thought. Mental illnesses are very common because of excessive stress. Recent studies show that mental illnesses are on the rise generally because of increasing stress. In Nigeria, medical records suggest an upsurge in mental health cases since the onset of the country’s economic downturn and the consequent trauma following it. The erythrocyte sedimentation rate (ESR) is an indirect marker of serum acute-phase protein concentrations, whereas C-reactive protein (CRP) is a direct protein measurement and it is inherently more well-defined. This study thus evaluated the roles of ESR and CRP as sensitive markers of inflammation and correlated their levels with severity stratification and prognosis in schizophrenic patients. Materials and Methods: This is a case-control study, and it was carried out on 40 patients diagnosed with schizophrenia. Thirty (30) controls were matched for age and sex; 8 millimeters of venous blood was collected from each participant using ante-cubital veins. Samples collected were dispensed into appropriate bottles foranalysis of CRP and hematological parameters using standard laboratory procedures. Statistical analysis of the data was done appropriately and P-value of less than 0.05 was considered as significant. Results: At the end of the study, the mean granulocytes, ESR, and CRP were significantly higher in schizophrenia cases than in the controls, while the mean PCV, RBC, and hemoglobin were significantly lower in the subjects. CRP had a higher area than ESR under the ROC curve (AUROC). Conclusion: This study thus evaluated the role of ESR and CRP as sensitive markers of inflammation and acute phase reactants in schizophrenic patients. The findings showed that CRP was a better diagnostic or predictor treatment outcome of schizophrenia

Individual and contextual factors associated with childhood malnutrition : a multilevel analysis of the double burden of childhood malnutrition in 27 countries

Background Malnutrition is a key global health challenge and a major contributor to childhood morbidity and mortality. In recent times, the contrasting coexistence of undernutrition including micronutrient deficiencies and overweight/obesity called double burden of malnutrition has been noted at individual, household or population level and/or at different times in life. The objective of this study was to examine individual, neighborhood and country level factors that are associated with the double burden of childhood malnutrition. Methods We conducted multivariable multilevel logistic regression analyses on the most recent demographic and health datasets from surveys conducted between 2015 and 2020 in low- and middle-income countries. We analyzed data of 138,782 children (level 1) living in 13,788 communities (level 2) from 27 countries (level 3). Results The results of our analysis show variation in childhood malnutrition across the 27 countries from as low as 6.5% in Burundi to as high as 29.5% in Timor Leste. After adjusting for all level factors, we found that those who were wasted/overweight tended to have had an episode of diarrhea or fever in the last two weeks preceding the survey, were part of a multiple birth, were being breastfed at the time of the survey and born to mothers with more than one under 5-child resident in neighborhoods with high illiteracy and unemployment rates. The intra-neighbourhood and intra-country correlation coefficients were estimated using the intercept component variance; 44.3% and 21.0% of variance in odds of double burden of childhood malnutrition are consequent upon neighborhood and country level factors respectively. Conclusions Evidence of geographical clustering in childhood malnutrition at community and country levels was found in our study with variability due to neighborhood level factors twice that of country level factors. Therefore, strategies in tackling the double burden of malnutrition must consider these shared drivers, contextual barriers and geographical clustering effects

Obesity burden by socioeconomic measures between 2000 and 2018 among women in sub‐Saharan Africa : a cross‐sectional analysis of demographic and health surveys

Background: The increasing global burden of obesity especially in low‐and‐middle‐income countries (LMICs) accentuates the need for critical action. In the absence of evidence‐based approaches to mitigate recent obesity trends, the likelihood of reaching global obesity targets will be almost zero. Objective: This study examined the obesity prevalence in Sub‐Sahara Africa and observed transitions on the burden of obesity prevalence over time. Methods: Data from the Demographic and Health Survey which is based on cross sessional design was used. Most recent surveys carried out in 16 sub‐Saharan Africa (SSA) between 2000 and 2018 were included in the analysis. Equiplot by the International Centre for Equity was used to display the inequities by the following socioeconomic measures: wealth index, education, and place of residence. Age‐standardized prevalence was measured across these socioeconomic measures using the WHO standard population age distribution, examined changing trends and finally assessed transition in obesity prevalence by percentage point difference of highest and lowest prevalence within each of the three socioeconomic measures. Results: A total of 496,482 women were included in the analysis. Obesity prevalence among women varied substantially, from 2% in Chad to 27% in Lesotho. Variation in obesity prevalence was observed across countries and by socioeconomic status measures. Among women in all the countries except Comoros, the burden was concentrated among the wealthiest. Out of the 16 countries included, the prevalence of obesity was concentrated among women with no education in eight countries (Benin, Burundi, Chad, Cote d'Ivoire, Guinea, Mali, Niger, Comoros) while it was concentrated in those with primary education in Congo and Lesotho and among those with secondary school education in DR Congo, Gabon, Namibia, Nigeria, and Zimbabwe. The burden of obesity was more concentrated in the urban across the 16 countries except in Comoros and Lesotho where they were higher in the rural (8.9 [7.2, 11.1] and 15.1 [13.0, 17.5] respectively) than in urban (6.6 [5.0, 8.8] and 6.8 [5.2, 8.8] respectively). Finally, the trend analysis with five countries indicated that the prevalence and gap in obesity among women increased between previous and most recent surveys except in Zimbabwe where it reduces across the three socioeconomic measures between 2011 and 2018. Conclusions: This study examined transition in obesity prevalence among women across three socioeconomic measures in selected sub‐Saharan African countries. Increasing prevalence of obesity was found in SSA but transition to women in lower socioeconomic status is already taking place in some countries