Athens Journal of Sciences
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Published By Athens Institute For Education And Research Atiner

2241-8466

2021 ◽  
Vol 8 (4) ◽  
pp. 309-332
Author(s):  
Efosa Michael Ogbeide ◽  
Joseph Erunmwosa Osemwenkhae

Density estimation is an important aspect of statistics. Statistical inference often requires the knowledge of observed data density. A common method of density estimation is the kernel density estimation (KDE). It is a nonparametric estimation approach which requires a kernel function and a window size (smoothing parameter H). It aids density estimation and pattern recognition. So, this work focuses on the use of a modified intersection of confidence intervals (MICIH) approach in estimating density. The Nigerian crime rate data reported to the Police as reported by the National Bureau of Statistics was used to demonstrate this new approach. This approach in the multivariate kernel density estimation is based on the data. The main way to improve density estimation is to obtain a reduced mean squared error (MSE), the errors for this approach was evaluated. Some improvements were seen. The aim is to achieve adaptive kernel density estimation. This was achieved under a sufficiently smoothing technique. This adaptive approach was based on the bandwidths selection. The quality of the estimates obtained of the MICIH approach when applied, showed some improvements over the existing methods. The MICIH approach has reduced mean squared error and relative faster rate of convergence compared to some other approaches. The approach of MICIH has reduced points of discontinuities in the graphical densities the datasets. This will help to correct points of discontinuities and display adaptive density. Keywords: approach, bandwidth, estimate, error, kernel density


2021 ◽  
Vol 8 (4) ◽  
pp. 249-272
Author(s):  
Marinko Oluić ◽  
Sreten Romandić ◽  
Ratko Vasiljević

The main goal of the presented exploration was to estimate potential for mineralization in the Mawat ophiolitic massif in Kurdistan, Iraq. The aim of the study was to explore existing copper mineralization and assessor elements gold, platinoids and chromium. Geological exploration detected two types of Cu occurrence a) secondary Cu carbonates (malachite) and b) Cu sulfides (chalcopyrite-pyrite). The Mawat region is mostly built of ultrabasic and basic rocks: peridotites, gabbros, serpentinites and basalts which are heavily deformed, with faults mostly oriented NNW-SSE, and NE-SW. The first phase of exploration comprised digital processing of ASTER and QuickBird satellite images, with appropriate geometrical and radiometric corrections and transformation into coordinate system. Color composite images were produced in different scales. They served to define lithological composition, tectonic settings, location of the points of interest etc. The field work was designed to check satellite data in situ, with focus on perspective rock formations, which might host copper mineralization, and other elements. The host rocks of the ore occurrences are primarily gabbros and metagabbros intersected by diabase dykes, epidote and quartz veins. Secondary mineralization is the product of surficial weathering and it is represented by malachite and limonite. The geophysical survey was very useful in the detection of area with elevated induced polarization and low resistivity. Three perspective areas have been selected for detailed explorations: Waraz, Mirava-Chenara and Konjirin-Kuradawi. The concentration of copper varies highly in very wide ranges; the maximum measured concentration of Cu was determined in Waraz area 6.7%. Some rock samples also show concentration of gold from 0.36 to 2.59 ppm Au. Keywords: Mawat ophiolitic massif, geologic-geophysical explorations, copper mineralization, Kurdistan-Iraq


2021 ◽  
Vol 8 (4) ◽  
pp. 229-248
Author(s):  
Yusuf Alapata Ahmed ◽  
Nathaniel Bayode Eniolorunda ◽  
Yakubu Fakai Musa ◽  
Samuel Igra

This study assessed the nature of solid waste generation, its spatio-temporal pattern and existing management strategies in Sokoto metropolis. The greatest challenges facing cities in the developing world are; paucity of solid waste management and control. In the Nigeria context, solid waste management is characterized by inefficient collection, insufficient coverage of the collection system and improper disposal methods. In Sokoto metropolis, increase in population has resulted into accelerated of solid waste generation with pollution of all categories, and the consequent is dearth of modern management. The study used; selection of different wastes for observation, sampling-up four sub-soils at 0-30cm at random from each of the waste dump sites to determine not only for heavy metal concentrations but also for fertility supplement in comparison with the National Environmental Standard and Regulation Enforcement Agency (NESREA). Also, fifty scheduled questionnaires were administered each on selected residents around dumped sites and to the staff of Town Planning Board to solicit for relevant information on government and its agencies effectiveness in disposal and management of waste. Landsat data was also used to map out the waste sites for spatio-temporal analysis from 1999 to 2016. Results are expected to inform major decisions makers and urban planners in order to promote a sustainable urban development for Sokoto metropolis and its environs. Keywords: developing world, protection agencies, Metropolis, urban planners, Sokoto


2021 ◽  
Vol 8 (4) ◽  
pp. 273-308
Author(s):  
Mohammed Ali ◽  
Md. Abdul Alim

The two-dimensional axisymmetric magnetohydrodynamic boundary layer flow with heat transfer of Newtonian fluid over a stretching and non-stretching bullet-shaped object has been investigated. Therefore, fluid flow and heat transfer have been investigated in two types of flow geometries such as the thicker surface and the thinner surface of the bullet-shaped object. The present analysis also focuses on the physical relevance and accurate trends of the boundary layer profiles which are adequate in the laminar boundary layer flow. The novelty of this current work is to discuss the effect of shape and size (surface thickness parameter s) and the stretching factor of the bullet-shaped object on the fluid velocity and temperature profiles within the boundary layer region also develop the relationship between the dependent and independent parameters by the correlation coefficient. The partial differential equations of momentum and energy have been reduced to a system of non-linear ordinary differential equations along with the transformed boundary conditions by applying the local similarity transformations. These coupled non‐linear ordinary differential equations’ governing the flow field has been solved by the Spectral Quasi-Linearization Method (SQLM). The numerical analysis of the SQLM has been carried out with MATLAB for investigating the effect of various controlling parameters on the flow fields. The residual error infinity norms have been analyzed to determine the speed of convergence and accuracy of the method. The numerical results have been displayed graphically and in tabular form and the physical behavior of the problem also discussed. The investigation shows that in the case of a thicker bullet-shaped object the velocity profile does not approach the ambient condition asymptotically but intersects the axis with a steep angle and the boundary layer structure has no definite shape whereas in the case of a thinner bullet-shaped object the velocity profile converge the ambient condition asymptotically and the boundary layer structure has a definite shape. It is also noticed that thinner bullet-shaped object acts as good cooling conductor compared to thicker bullet-shaped object and the wall friction can be reduced much when thinner bullet-shaped object is used rather than the thicker bullet-shaped object in both types of non-stretching or stretching bullet-shaped object . Keywords: forced convection, correlation coefficient, multiple regression, MHD, stretching


2021 ◽  
Vol 8 (3) ◽  
pp. 213-228
Author(s):  
Yerizon Yerizon ◽  
Atus Amadi Putra

The aim of this paper is to describe the research results on multiple intelligences in mathematics learning, using a descriptive approach. It also ascertains the influence of various learning models on mathematics learning outcomes based on students’ multiple intelligences. Student Teams-Achievement Divisions (STAD) and Team Games Tournament (TGT) learning models improved learning outcomes for students possessing logical-mathematical, kinesthetic, and interpersonal intelligences. Furthermore, Group Investigation (GI) and Numbered Head Together (NHT) learning models improved student learning outcomes with logical-mathematical intelligence. Two Stay Two Stray (TSTS) learning model with peer tutors improved student learning outcomes with linguistic, logical-mathematical, and interpersonal intelligences. Team Assisted Individualization (TAI) and Jigsaw learning improved student learning outcomes with linguistic intelligence. Also, TSTS and NHT learning models improved student learning outcomes with logical-mathematical, and interpersonal intelligences. Keywords: compound intelligence, learning model, mathematics


2021 ◽  
Vol 8 (3) ◽  
pp. 183-198
Author(s):  
Maged M.A. Hussein

Mean daily variability of latent heat (E), sensible heat (H), net long wave (Lwnet), net short wave, and net flux of surface heat balance were estimated from hourly sea surface water temperature (SST) and meteorological time series obtained for three months during summer season (2019) in Alexandria Eastern Harbor (AEH), Egypt. Latent and sensible heat were not in phase and had their maximum 181.12 W/m2 (5:00 PM), 16.5 W/m2 (5:00 AM) and minimum 103.64 W/m2 (8:00 AM), -12.14 W/m2 (3:00 PM), resulting in Bowen ration of -0.11 and 0.09, respectively. The loss of heat by evaporation therefore predominates than sensible heat utilized to warm surface atmosphere. The instability of the atmosphere was existing nearly most of the time period, rising exchange coefficients of sensible and latent heat flux by about 24.26% over estimated neutral values (from 1.15 × 10−3 to 1.43 × 10−3). Mean Lwnet changed from 165.63 at early morning to 173.52 W/m2 at late afternoon, point out its significant importance in the total balance of heat flux of eastern harbor surface. Latent heat flux and Lwnet were positive (energy losing from eastern harbor), throughout the day. The daily average of net energy budget (S) was 38.52 W/m2; daytime gain exceeded nighttime loss, with consequent heating the eastern harbor. Qualitatively, daily variations of net energy budget (S) were nearly consistent with time delay to the variability of sea surface temperature, indicating the predominant role of the heat budget of the surface layer in modulating surface temperatures of the Eastern Harbor. Keywords: heat flux, shortwave, long wave, latent heat, sensible heat, Eastern Harbor


2021 ◽  
Vol 8 (3) ◽  
pp. 199-212
Author(s):  
Ellene Tratras Contis ◽  
Batoul Abdallah

Science, Technology, Engineering and Mathematics (STEM) programs that attract and sustain student interest feature learning that is experiential, investigative, hands-on, personally significant to both students and faculty, connected to other inquiries, and suggestive of practical application to students’ lives. Such learning flourishes in a community in which faculty are committed equally to teaching, to maintaining their own intellectual vitality, and to partnering with students in learning, and in which institutional support for such a community exists. The Creative Scientific Inquiry Experience (CSIE) Program at Eastern Michigan University (EMU) is involved in retaining and increasing the number of STEM graduates by including faculty professional development, student connectedness to the sciences and mathematics through academic service-learning, and curricular reform. In this conference paper we report on the success of the CSIE program, including course development, student engagement, student success, especially among underserved students, and sustainability. This work is important because it offers insight into the development, sustainability, and scalability into faculty-driven STEM education reform spanning 15 years. Keywords: STEM education, retention strategies, undergraduate STEM, majors/non-majors


2021 ◽  
Vol 8 (3) ◽  
pp. 167-182
Author(s):  
Jose Luis Tiedemann

The present study is aimed at quantifying and comparing the net aerial primary productivity (NAPP) of two alfalfa varieties (Medical sativa L.) by determining the Radiation Use Efficiency (Ɛ) for each variety, estimating the NAPP though the Red Vegetation Index and relating it to the quantified NAPP. Significant differences between the individual NAPP of each variety were not found: G969 = 1564 g dm m-2 and M901 = 1636 g dm m-2 (T = 0.92; p>0.05). The Ɛ of the G969 was 0.56 g Mj-1 while that of M901 was 0.58 g Mj-1. Significant direct relationships between the quantified NAPP and that calculated using the Red Vegetation Index were found. The models obtained were: NAPPG969 = 506.06x – 343.25 (R2 = 0.88; p<0.001) and NAPPM901 = 420.28x + 37.82 (R2 = 0.98; p<0.001). The Ɛ values of the alfalfa varieties under study, determined at local level, reduce uncertainty when generating predictive models of productivity. The NAPP of alfalfa varieties can be non-destructively predicted using the Red Vegetation Index obtained by a reflex RGB digital camera. Keywords: radiation use efficiency, digital camera, canopy reflectance, RGB indices


2021 ◽  
Vol 8 (2) ◽  
pp. 105-122
Author(s):  
Onisogen Simeon Edori ◽  
Enize Simeon Edori

Water samples were collected from four different stations bimonthly from the Orashi River for a period of one year. The samples were collected from the shores of selected communities along the Engenni axis of the river. The samples were treated and analyzed according to standard laboratory and analytical procedures for water physicochemical parameters. The parameters examined were pH, Salinity, chlorides (Cl-), Conductivity, total dissolved solids (TDS), total suspended solids (TSS) turbidity, temperature, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrates (NO3-), sulphate (SO42-) and phosphates (PO43-). The results showed that the mean values of the evaluated parameters were; pH (6.91±0.11), salinity (9.79±0.27 mg/L), Cl (6.25±0.25 mg/L), conductivity (29.66±1.20 µS/cm), TDS (17.66±2.08 mg/L), TSS (16.83±1.15 mg/L), turbidity (11.84±1.50 mg/L), temperature (28.16±0.12 oC), DO (5.91±0.18 mg/L), BOD (7.30±0.60 mg/L), COD (9.41±0.70 mg/L), NO3- (3.42±0.27 mg/L), SO42- (1.15±0.56 mg/L) and PO43- (15.65±5.76 mg/L). The results of the different parameters showed that all of them fall within the WHO acceptable limit except turbidity, DO and BOD that were not within the recommended range, then COD and phosphates that were either within or above the recommended values at different instances. Based on the findings of this work, the water may not be particularly suitable for drinking purposes, but can be used for other household functions that do not require consumption and also for irrigation. Keywords: water, physicochemical property, human activity, environment, contamination


2021 ◽  
Vol 8 (2) ◽  
pp. 147-166
Author(s):  
Alex B Pablos

This essay tries to make a tangential cut between the debate that seeks the most adequate definition of scientific progress (involving authors such as K. Popper, T Kuhn, A Bird or J Saatsi) and the debate on the viability of structural realism to be considered the best epistemological approach to the understanding of nature (B van Fraassen, J Ladyman, J Worrall, S Psillos...). Thus, we will first connect both debates by showing that they shared a common problem before their progressive distancing. Finally, we will outline a formulation of scientific progress inferred from the structural realism approach; in particular, our definition will be based on J. Ladyman’s proposal in Every Thing Must Go as we will emphasize that it also provides an answer to the aforementioned original problem. Our conclusion is that this formulation of scientific progress differs from the three main ones, namely, truthlikeness, problem-solving, and accumulation of knowledge. This fourth form is necessarily linked to a speculative approximation of reality. Moreover, we want to suggest that this fourth conception is articulated under the shadow of the ideas of CS Peirce. Keywords: structural realism, scientific progress, J Ladyman, speculative realism


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