Spatial evaluation of speed-flow-geometry relationship on two-lane rural highways

The mean travel speed of drivers on uninterrupted flow facilities such as two-lane rural highways is deemed as good performance indicator for the subject road class; as the variable relates well with user perception. However, the operating conditions on two-lane roads relating to travel speed is different from those on other types of facilities, as fast moving vehicles in either direction are usually impeded by slower moving ones in the same travel direction and also facing oncoming traffic in the opposing lane. Thus, impeded vehicles may be compelled to travel at lower speeds than desired; particularly, in the absence of sufficient sight distance and permissible gap in the opposing traffic stream, being the appropriate lane used for passing maneuvers. This implies that the operating speed on two-lane highways substantially depends on the level of traffic flow and perhaps, its composition as well as the roadway geometric features. This paper examines the effects of traffic level, composition and road geometric features on the operating speed on two-lane highways based on a spatial approach. An empirical model relating mean travel speed to traffic flow parameters and highway geometric features was derived for prediction of mean travel speed on two-lane rural highways based on easily observable variables

Customer Churn Prediction in Telecom Sector: A Survey and way a head

© 2021 International Journal of Scientific & Technology Research. This work is licensed under a Creative Commons Attribution 4.0 International License.The telecommunication (telecom)industry is a highly technological domain has rapidly developed over the previous decades as a result of the commercial success in mobile communication and the internet. Due to the strong competition in the telecom industry market, companies use a business strategy to better understand their customers’ needs and measure their satisfaction. This helps telecom companies to improve their retention power and reduces the probability to churn. Knowing the reasons behind customer churn and the use of Machine Learning (ML) approaches for analyzing customers' information can be of great value for churn management. This paper aims to study the importance of Customer Churn Prediction (CCP) and recent research in the field of CCP. Challenges and open issues that need further research and development to CCP in the telecom sector are exploredPeer reviewe

Dynamic behavior of a smart device on a surface subjected to earthquake motion

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144310/1/eqe3048_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144310/2/eqe3048.pd

Boosting Ant Colony Optimization with Reptile Search Algorithm for Churn Prediction

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).The telecommunications industry is greatly concerned about customer churn due to dissatisfaction with service. This industry has started investing in the development of machine learning (ML) models for churn prediction to extract, examine and visualize their customers’ historical information from a vast amount of big data which will assist to further understand customer needs and take appropriate actions to control customer churn. However, the high-dimensionality of the data has a large influence on the performance of the ML model, so feature selection (FS) has been applied since it is a primary preprocessing step. It improves the ML model’s performance by selecting salient features while reducing the computational time, which can assist this sector in building effective prediction models. This paper proposes a new FS approach ACO-RSA, that combines two metaheuristic algorithms (MAs), namely, ant colony optimization (ACO) and reptile search algorithm (RSA). In the developed ACO-RSA approach, an ACO and RSA are integrated to choose an important subset of features for churn prediction. The ACO-RSA approach is evaluated on seven open-source customer churn prediction datasets, ten CEC 2019 test functions, and its performance is compared to particle swarm optimization (PSO), multi verse optimizer (MVO) and grey wolf optimizer (GWO), standard ACO and standard RSA. According to the results along with statistical analysis, ACO-RSA is an effective and superior approach compared to other competitor algorithms on most datasets.Peer reviewedFinal Published versio

Efficient Photoelectrochemical Performance of Gamma Irradiated gC3N4 and its g-C3N4@BiVO4 Heterojunction for Solar Water Splitting

This is the author accepted manuscript. The final version is available from the American Chemical Society via the DOI in this recordComprehensive experimental and density functional theory simulations have been performed for the enhanced photoelectrochemical performance of gamma irradiated g-C3N4 and its heterojunction with BiVO4. The structure and morphology of g-C3N4@BiVO4 as a heterojunction were analyzed and verified from the correlation of experimental and theoretical data. It is found that gamma radiations have changed the bonding structure of g-C3N4 which ultimately reduces the optical bandgap energy. Moreover, the performance of gamma-irradiated g-C3N4 is two-fold, compared to that of non-irradiated one; increases from 3.59 to 5.86 µAcm-2 at 1.23 V versus Ag/AgCl in 0.5 M Na2SO4 electrolyte solution (pH 7). Finally, it is observed that the performance of gamma irradiated g-C3N4 in g-C3N4@BiVO4 heterojunction increased from 0.53 mA cm-2 to 1.38 mA cm-2, compared to that of the non–irradiated one. In summary, it has been concluded that gamma-irradiated g-C3N4 and its heterojunction is potentially be applied in PEC solar water splitting.National University of Malaysi

Dynamique Hydro-Erosive Actuelle Des Bassins Versants Endoreiques De La Region De Niamey (Sud-Ouest Du Niger)

La généralisation du ravinement et la baisse de la productivité des terres sont quelques-unes des principales contraintes qui assaillent l’utilisation des sols au Sahel. Pour gérer efficacement ces sols, une évaluation des processus hydro-érosifs est nécessaire. Ce travail a ainsi pour objectif d’analyser la dynamique hydro-érosive sur un site expérimental installé depuis 2004 dans la région de Niamey (Niger). Sur ce site, le dispositif de mesure est composé de huit parcelles de mesures de ruissellement et d’érosion, des stations hydrométriques à l’exutoire des deux bassins versants endoréiques et de plusieurs piquets destinés aux suivis morpho-dynamiques des ravines. Après une décennie d’observation, les ruissellements mesurés sur les parcelles se caractérisent par une dynamique saisonnière croissante sur les surfaces encroûtées (croûtes biologique et d’érosion) et décroissante sur les surfaces cultivées. Le coefficient de ruissellement varie de 5 % sur la surface cultivée à 58 % sur la croûte d’érosion. Au cours des 10 années de mesure, ce coefficient a connu une forte croissance en particulier sur la jachère (+ 80 %) et sur la surface cultivée (+ 300 %), traduisant ainsi la dégradation des sols. A l’échelle des bassins versants, l’augmentation du coefficient de ruissellement s’accompagne d’une érosion aréolaire qui décape le sol à une vitesse moyenne de 5 mm/an et d’une érosion linéaire active, de l’ordre de 4 m3/an au niveau des ravines suivies. Les transferts sédimentaires qui en résultent agissent sur le fonctionnement morpho-sédimentaire des cours d’eau. Des aménagements antiérosifs sont nécessaires pour dissiper les processus hydro-érosifs et préserver les services écosystémiques des sols des bassins. Widespread gullying and the declining land productivity are some of the main constraints plaguing land use in the Sahel. In order to effectively manage these soils, it has become necessary to assess the hydro-erosive processes. The current study, thus, aims at analyzing the hydro-erosion dynamics on an experimental site installed since 2004 in the Niamey region (Niger Republic). On this site, the measurement device is made up of eight runoff and erosion measurement plots, hydrometric stations at the outlet of the two endorheic watersheds and several stakes intended for morpho-dynamic monitoring of the gullies. After a decade of observation, the runoff measured on the plots is characterized by an increasing seasonal dynamic on encrusted surfaces (biological and erosion crusts) and a decreasing one on cultivated surfaces. The runoff coefficient varies from 5% on the cultivated area to 58% on the erosion crust. Over the 10 years of measurement, this coefficient has greatly increased, especially on the fallow (+ 80%) and on cultivated area (+ 300%); this increase consequently reflects soil degradation. At the watershed scale, the increase in the runoff coefficient is accompanied by area erosion (or the erosion of the area out of the basin) which strikes the soil at an average speed of 5 mm/year and active linear erosion measuring 4 m3/year as observed at the monitored (the ongoing investigated) gullies. The resulting sediment transfers act on the morpho-sedimentary functioning of rivers. Anti-erosion facilities are necessary to dissipate the hydro-erosive processes and preserve the ecosystem services of the soil in the basin

Optimization, economization and characterization of cellulase produced by marine Streptomyces ruber

Cellulase is a very important enzyme due to its great industrial applications. Six marine strains of actinomycetes were screened for their carboxymethyl cellulase (CMCase) productivity. Streptomyces ruber was chosen to be the best producing strain. The highest enzyme production (25.6 U/ml) was detected at pH 6 and 40°C after 7 days of incubation. Plackett-Burman design was applied to optimize the different culture conditions affecting enzyme production. Results showed that a high concentration of KH2PO4, and a low concentration of MgSO4 had a significant effect on enzyme production. Rice straw was used as a low cost source of cellulose. It was found that 30 g/l rice straw was the suitable concentration for maximum enzyme production. Partial purification of cellulase enzyme using an anionexchange chromatography resulted in the detection of two different types of CMCases, type I and II, with specific activity of 4239.697 and 846.752 U/mg, respectively. Moreover, estimation of their molecular weight revealed 27.0 kDa for cellulase type I and 24.0 kDa for cellulase type II. It could be concluded that S. ruber is a powerful cellulase producer strain under our tested experimental conditions.Key words: Cellulase production, Streptomyces ruber, Plackett-Burman design, rice straw, enzyme characterization

Study of Correlation Between Heavy Metal Concentration, Street Dust and Level of Traffic in Major Roads of Kano Metropolis, Nigeria

This study was aimed at evaluating heavy metal contents in street dust of five major roads within the trunk of Kano metropolis. The dust were collected from heavy traffic roads of the city which include Zaria road (ZR), Maiduguri road (MR), Katsina road (KR), Hadejia road (HR) and Bayero University Kano road (BR). Triplicates samples were collected and the number of vehicles that pass through each road was recorded for one hour. The metal concentration of the dust was determined using atomic absorption spectroscopy (AAS). Strong positive correlation exist between the amount of dust collected and the number of vehicles that passed in all the roads except for Hadejia road with r2 = 0.32 which is less positive. The metal contents in dust of the five streets were higher than the WHO reference value. The positive correlation between the number of vehicles and metal type was significant (P<0.05) for Zn, Fe, and Mg in ZR, Pb and Fe in HR; Fe and Mn in BR, while between street dust and metal type was significant (p<0.05) for Zn and Fe in ZR; Fe and Cu in KR; Ca in HR and Fe in BR. The high positive correlation observed in this study may mean that the metals in the street dust originate from common anthropogenic sources. Higher than reference values of the heavy metals in street dust, indicate hazard associated with residing or conducting business along the major street in the city. The finding is in support of government effort in protecting its citizenries by prohibiting road site business

GC/MS determination of bioactive components and antibacterial properties of Goniothalamus umbrosusextracts

In this study, the antibacterial activity and chemical composition of Goniothalamus umbrosus leaves extracts were evaluated. The antibacterial activity was investigated using two gram-positive bacteria, Methicillin resistant Staphylococcus aureus (MRSA) and Bacillus subtilis B29, and two gram-negative bacteria, Pseudomonas aeruginosa 60690 and Salmonella choleraesuis. The activity was tested using disc diffusion and minimum inhibitory concentration assays. The chemical compositions of the ethyl acetate extract of G. umbrosus were investigated using Shimadzu gas chromatography–mass spectrometry (GC-17A) while the mass spectra of the compounds found in the extract was matched with the library. The results showed that the  extracts demonstrated broad spectrum antibacterial effects against all tested bacteria. GC/MS analysis of ethyl acetate extract of G. umbrosus revealed the existence of 1-butyl-2-cyclohexen-1-ol (46.84%), benzaldehyde (4.42%) and globulol (4.07%). The results of this study offer a platform of using G. umbrosus as herbal alternative for the current synthetic antimicrobial agents

Circulating microRNAs as potential biomarkers of early vascular damage in vitamin D deficiency, obese, and diabetic patients

Vitamin D3 deficiency, obesity, and diabetes mellitus (DM) have been shown to increase the risk of cardiovascular diseases (CVDs). However, the early detection of vascular damage in those patients is still difficult to ascertain. MicroRNAs (miRNAs) are recognized to play a critical role in initiation and pathogenesis of vascular dysfunction. Herein, we aimed to identify circulating miRNA biomarkers of vascular dysfunction as early predictors of CVDs. We have recruited 23 middle-aged Emiratis patients with the following criteria: A healthy control group with vitamin D ≥ 20ng, and BMI 1.5) in high-risk patients for CVDs vs healthy controls. Collectively, our result indicates that four specific circulating miRNA signature, may be utilized as non-invasive, diagnostic and prognostic biomarkers for early vascular damage in patients suffering from vitamin D deficiency, obesity and DM