Voltage quality enhancement in distribution system using artificial neural network (ANN) based dynamic voltage restorer

Voltage quality issue and invariably power quality has become an important issue in distribution power system operation due to presence of increased use of nonlinear loads (computers, microcontrollers and power electronics systems). Voltage sags and swells as well as harmonics are problems for industrial, commercial and residential customers with sensitive loads, which need urgent attention for their compensation. In this paper, the modeling and simulations of a dynamic voltage restorer (DVR) was achieved u sing MATLAB/Simulink. The aim was to employ artificial intelligence to provide smart triggering pulses for the DVR to mitigate and to provide compensation against voltage sags and swells. The Artificial Neural Network (ANN) was trained online by data gener ated via a 3 - phase programmable voltage generator and these were used as inputs to the ANN, fault conditions were simulated to create voltage sags and swells in the source supply, while faultless condition of the system was simulated and the data obtained from it was used as targets of the ANN. A net fitting, feed forward back propagation, Lavenberg - Marquardt training algorithm and mean square error performance were used. ANN Simulink block was used as control for the gate of the full wave 3 - phase Insulated Gate Bipolar Transistor (IGBT) inverter employed in constructing the DVR. Three single phase injection transformers were employed to regulate the output amplitude voltage from the DVR, while filters were used to reduce the harmonics from 11.09% to 3.5%. A t the end, voltage sags and swells were effectively mitigated and harmonics in the system reduced to 3.5%, which is within the maximum acceptable IEEE standard 519 of 1992 for harmonic distortion. Key words : Voltage, Distribution System, ANN, Dynamic Volt age Restorer, Voltage quality enhancement, non - linear load

Distribution of metals in Labeo coubie (Ruppel, 1832) from a National Park river in Nigeria

This study assesses heavy metals distribution in body parts of Labeo coubie (African carp) fromRiver Oli, in Kainji Lake National Park as pollution index of the ecosystem. Fish parts samples (gills, muscles andvertebra bone) were prepared and specifically analyzed for the levels of Pb, Cr, Zn, Cu, Fe and Cd using Atomicabsorption spectrophotometry. The concentration of metals in the samples at different concentrations ranged from0.001±0.000 μg/g for Cd to 224.87±4.07 μg/g of Fe in the fish gill. There is significant (p<0.05) differences in the Pb,Zn, Cu and Fe concentrations across the different fish parts with gills accumulated the highest levels metals while Crlevels significantly (p<0.05) differed in the fish body parts and accumulated more in the muscles (10.75±0.15 μg/g).The mean concentrations of metal elements in the fish parts had shown some distinguish connection in its distributionswith Pb and Cu; Gills > Muscles > Vertebra bones, Fe and Zinc; Gills > Vertebra bones > Muscles while Cr wasdistributed in Muscles > Gill > Vertebra bones. However, it is revealed that Labeo coubie, a euryphagus fish probablyabsorb these metals through ingestion of contaminated food or absorption by the gills and bioaccumulate in differentfish parts. It is therefore established that River Oli is contaminated with heavy metals as presence of these metals infish is an indication of its immediate environment. Keywords: absorption, bioaccumulation, fish parts, heavy metals, pollutio

Upright or dorsal? childbirth positions among antenatal clinic attendees in Southwestern Nigeria

Background: Upright childbirth positions are associated with better delivery outcomes. These positions such as kneeling and squatting were the norm for childbirth in indigenous Nigerian custom. However, westernization has largely replaced them with supine positions.Objective: This study was conducted to compare the knowledge, attitude and experience regarding childbirth positions between antenatal clinic attendees in southwest and northwest Nigeria.Materials and Methods: A mixed methods design was employed. Quantitative data were obtained using a structured questionnaire in Obafemi Awolowo University Teaching Hospitals Complex, Ile‑Ife (n = 201) and Federal Medical Centre, Katsina (n = 104). Knowledge was graded as poor, fair or good whereas attitude toward each position was graded as favoured, indifferent or against. The resulting proportions were compared using Chi‑square. Qualitative data were obtained through key‑informant interviews.Results: Knowledge of childbirth positions was generally poor. Overall, only to women (0.6%) had good knowledge, whereas 60 (19.7%) had fair knowledge and the rest (79.7%) had poor knowledge. More women in Katsina than Ile‑Ife knew the squatting position (32.7% vs. 16.4%; P < 0.001) and favoured it (25.0% vs. 7.5%; P < 0.001), whereas more Ile‑Ife women knew the lithotomy position (42.3% vs. 26.9%; P = 0.01). Attitudes towards the remaining positions were comparable between them. Key‑informant interviews of the midwives revealed that they were trained to conduct delivery exclusively in the supine positions. They were, however, interested in learning the use of upright positions.Conclusion: Knowledge about childbirth positions was very poor. Women in northwestern Nigeria were more aware and favorably disposed to childbirth in their customary squatting position. Training of Nigerian midwives on upright childbirth positions is recommended.Keywords: Childbirth position; knowledge; labour duration; practice; preference; Yoruba wome

Model prediction and climatology of aerosol optical depth (τ550) and angstrom exponent (α470-660) over three aerosol robotic network stations in Sub-Saharan Africa using moderate resolution imaging spectroradiometer data

The spatial and temporal variations of aerosol optical depth at 550 nm (τ550) and Angstrom exponent derived from 470 and 660 nm (α470-660) over Nairobi (NAI), Skukuza (SKU) and Ilorin (ILO) Aerosol Robotic Network (AERONET) stations in sub-Saharan Africa, as recorded by Moderate Resolution Imaging Spectroradiometer (MODIS) satellites for fifteen years (2000-2015), were examined in relation to their climatologies and prediction. The MODIS measurements of τ550 and α470-660 from aqua (MYD04) and terra (MOD04) satellites were used in this study. Retrievals of τ550 for both satellites were validated with AERONET τ550 for the same period. The validation results showed that they compare favourably over the three stations, but MOD04 performed better than MYD04 data in NAI and ILO for τ550. This shows that the τ550 of NAI and ILO are best captured using the MOD04 data while that of SKU is best with MYD04. It was also discovered that MODIS underestimated AERONET τ550 data over NAI and SKU. The most polluted station is ILO while the least polluted one is NAI. Similarly, the station with the highest concentration of absorbing aerosols is NAI and the least was observed in ILO. The aerosol climatology shows that the most polluted months in NAI, SKU and ILO are October, June and March respectively. On the other hand, February, November and March has the highest amount of scattering aerosols in the atmosphere for NAI, SKU and ILO respectively. The highest amount of absorbing aerosols was found, respectively, in the months of June, June and August. The generated time series (TS) models are all good, though a general underestimation of the parameters by the models was also observed. Keywords: Aerosol optical depth, Angstrom exponent, MODIS, Time series, sub-Saharan Afric

Preliminary techno-economic analysis of non-commercial ceramic and organosilica membranes for hydrogen peroxide ultrapurification

Polymeric membrane cascades have demonstrated their technical and economic viability for hydrogen peroxide ultrapurification. Nevertheless, these membranes suffer from fast degradation under such oxidative conditions. Alternative membranes with higher chemical resistance could improve the ultrapurification process. Therefore, this work presents the preliminary techno-economic analysis of two non-commercial membranes (a ceramic one and a hybrid organosilica one). This analysis is complemented with further research regarding the competitiveness of these alternative membranes compared to polymeric ones. The results confirm the technical viability for both membranes, but the ceramic membrane is not appropriate when Na is considered as the limiting impurity (because it has too low rejection coefficient). The economic viability of the proposed ultrapurification processes is also probed, but not under competitive conditions, as the polyamide membrane appears to be the optimal choice. Nonetheless, improvements in the permeability of the hybrid membrane (an increase in the membrane permeability by a factor of 10) or the rejection performance of the ceramic membrane (an increase in the reflection coefficient above 0.85) could transform these non-commercial membranes into the most profitable alternative.This research has been financially supported by the Spanish Ministry of Economy and Competitiveness (MINECO) through CTQ2014-56820-JIN Project, co-financed by FEDER funds. R. Abejón acknowledges the assistance of the Japan Society for Promotion of Science (JSPS) for the award of a Post-Doctoral Fellowship (Short-Term) for North American and European Researchers (PE14057)

Blood Biochemical Profile and Carcass Characteristics of Weaner Rabbits Fed Varying Inclusion Levels of Gamba Grass (Andropogon gayanus Kunth.) Forage

A study was conducted to investigate the effect of varying inclusion levels of Gamba grass (Andropogon gayanus Kunth) forage on haematological, blood biochemical and carcass characteristics of weaner rabbits. A total of 20 male rabbits of mixed breeds with an average initial weight of 450g were randomly assigned into four dietary treatments containing varying inclusion levels of gamba grass forage (0, 5, 10 and 15%). There were four rabbits per treatment, each serving as a replicate in a completely randomized design. Blood samples were collected at the end of eight (8) week feeding period before the carcass analysis.. Results indicated that there were significant (P<0.05) increasing trend in the haematological and blood biochemical parameters measured. There were 51% and 55% increases (P<0.05) in total protein (8.53 vs. 5.65g/dl) and calcium ions (2.65 vs. 1.18mmol/dl) in rabbits fed diet containing 15% inclusion level of gamba grass forage compared to the control. However, there were 10% and 17% decreases (P<0.05) in white blood cells (4.92 vs. 4.43%) and alkaline phosphate (89.33 vs. 76.33IU/dl) in rabbits fed the control diet than those fed diet containing 15% inclusion level of gamba grass. Also, there were 13% and 49% increase (P<0.05) in dressing percentage (54.80 vs. 48.60%) and weight of thigh (16.95 vs. 11.35%) in rabbits fed diet containing 15% inclusion level of gamba grass forage compared to the control. However, length of small intestine and weights of heart, head, stomach and small intestines were similar (P>0.05) across the treatments, respectively. It was concluded that gamba grass forage can be included up to 15% in the diet of weaner rabbits, without adverse effect on haematological, biochemical profile and carcass characteristics of the rabbits in Northern Guinea savanna of Nigeria. Gamba grass (Andropogon gayanus Kunth) forage can be included in the diets of weaner rabbits to reduce cost of production.Keywords: Blood, competition, carcass, feed, gamba, Nigeria, rabbi

Development of Yawning Detection Algorithm for Normal Lighting Condition and IR Condition

Drowsiness monitoring system has been widely used in this current technology to monitor the driver’s state while driving. This paper presents a drowsiness detection method through the activity of yawning for both normal lighting condition and Infrared (IR) condition. Development of the algorithm consists of several steps. Initially, the detection of face and mouth implementing the Viola-Jones algorithm takes place. For IR condition, the mouth is detected by applying the geometrical measurements of a face. After the detection process is done, the tracking process for both face and mouth takes place utilizing the Kanade-Lucas-Tomasi (KLT) algorithm which is basically a point tracking algorithm. Based on the tracked mouth, the region of interest (ROI) is selected which is to be used as an input image in the image processing step in order to get a clearer image of the mouth. From the finalized mouth image in the preprocessing step, the properties of the image are further used in the yawning detection step. In the indication of yawning, the height of the mouth opening reading score is observed. The performance of the proposed method is tested on 5 subjects and achieved an overall accuracy of 98.89% for normal lighting condition and 95.29% for IR condition

The TBX21 transcription factor T-1993C polymorphism is associated with decreased IFN-γ and IL-4 production by primary human lymphocytes

T-bet is a transcription factor that drives the Th1 immune response primarily through promoting expression of the IFN-γ gene. Polymorphisms in the T-bet gene, TBX21, have been associated with immune-mediated diseases such as asthma and systemic sclerosis. We found that the TBX21 promoter polymorphism T-1993C is associated with a significant decrease in IL-4 and IFN-γ production by stimulated primary human lymphocytes from healthy participants

Chandra Smells a RRAT: X-ray Detection of a Rotating Radio Transient

"Rotating RAdio Transients" (RRATs) are a newly discovered astronomical phenomenon, characterised by occasional brief radio bursts, with average intervals between bursts ranging from minutes to hours. The burst spacings allow identification of periodicities, which fall in the range 0.4 to 7 seconds. The RRATs thus seem to be rotating neutron stars, albeit with properties very different from the rest of the population. We here present the serendipitous detection with the Chandra X-ray Observatory of a bright point-like X-ray source coincident with one of the RRATs. We discuss the temporal and spectral properties of this X-ray emission, consider counterparts in other wavebands, and interpret these results in the context of possible explanations for the RRAT population.Comment: 5 pages, 2 b/w figures, 1 color figure. To appear in the proceedings of "Isolated Neutron Stars", Astrophysics & Space Science, in pres