iosr-Jm   Volume-16 ~ Issue-1 ~ Jan – Feb 2020

Abstract: In this article, we have analyzed international concerns about the environment, in particular current United Nations policy, indicating the goal is for the world to be committed to the elimination of contaminants in order to achieve a healthy, non-polluting environment and achieving that the results reach an environment with acceptable pollutant concentrations. Here we present a model through a system of periodic differential equations in the elimination function, which simulates the elimination of pollution by oxidation ponds. The system is reduced to the normal combined form, a qualitative study is made, and necessary and sufficient conditions are given on the future behavior of the trajectories.

Keywords: Environment, pollution, mathematical model.

[1]. Batista E, Sánchez S, Lacort M, Ferreira R, Ribeiro Z e Ruiz A. I." Mathematical Modeling of Pollution Elimination" Journal of Scientific and EngineeringResearch, 5(5):234-240, 2018.
[2]. Batista E, Lacort M, Ferreira R, Ribeiro Z and Ruiz A. I. "Normal FormCombined In Pollution Elimination Model. Journal of Research in Applied Mathematics Volume 5 pp: 21-282. (2018).
[3]. E. Batista, L. Leão, S. Sáncheza, E. Rodrigues P, R. Ferreira, N.Fernandes. E.Rodrigues F, A. I. Ruiz "Mathematical Modeling with General Periodic Coefficients in Elimination of Pollution". IOSR Journal of Mathematics (IOSR-JM). Volume 15, Issue 6 Ser. II (Nov – Dec 2019), PP 01-06. [4]. Boudonov, M. Study of ordinary differential equations. Habana University. Evolutionary dictation. Year 1998. [5]. Cachapuz, A. The teaching of science for excellence in learning. In: Oak, A (Org.). New Methodologies of Education. Porto: Porto Publisher, 1995

Abstract: Backed by the Saudi Vision 2030, The Kingdom of Saudi Arabia (KSA) has paid a special attention to the sector of Small & Medium Enterprises (SMEs), in view of the economic and social importance of SMEs, the role they play in the overall development process in general and economic development in particular. This researcher paper aims to deciding the most important factors affecting the development and success of SMEs. This objective is achieved by conducting a statistical analysis using the Cox regression model to analyze the data through using Statistical package for social sciences (SPSS). The sample of the study consists of 1292 enterprises from different regions of the Kingdom of Saudi Arabia. The study found several variables that have a significant effect are the age, educational.....

Key Word: Small and Medium Enterprises; Development; Economy; Cox Regression

[1]. Government of Saudi Arabia. (2016). Vision Saudi 2030. Kingdom of Saudi Arabia.
[2]. Beck, T.,&Demirguc-Kunt, A. (2006). Small and medium-size enterprises: Access to finance as a growth constraint, Journal of Banking & Finance, 30(11), 2931-2943.
[3]. Jeddah Chamber (2016), SMALL–MEDIUM ENTERPRISES IN SAUDI ARABIA REPORT April 2016, Jeddah, Kingdom of Saudi Arabia.
[4]. Bokhari, A. A. (2013). Entrepreneurship as a Solution to Youth Unemployment in the Kingdom of Saudi Arabia, American Journal of Scientific Research, (87), 120-134.
[5]. Al-Tit, A., Omri, A.,&Euchi, J. (2019). Critical Success Factors of Small and Medium-Sized Enterprises in Saudi Arabia: Insights from Sustainability Perspective, Administrative Sciences Journals, 9(2), 32-43.

Abstract: Traditional statistical methods for nonlinear models require a starting point (initial parameters or guess values) to begin the optimization process. The nonlinear model expression must be written, the parameter names declared, and initial parameter values specified, then the parameters are estimated through an iterative approach. A computer program for estimating three growth models (Richards, Gompertz and Weibull model) using the modified version of the Levenberg-Marquardt method for solving non-linear regression model was employed. The growth models were decomposed by additive and multiplicative error terms which help in identifying the most appropriate model for growth studies. The problem of the initial parameters was addressed by second-order regression techniques before an iterative approach was done. The result contain the final estimate of the parameters, standard....

Keywords: Growth Models; Modified Levenberg-Marquardt Algorithm; Initial Parameters; Additive and Multiplicative Error Terms and Model Adequacy Criteria.

[1]. Aggrey, S. E. (2002). Comparison of three Nonlinear and Spline Regression Models for Describing Chicken Growth and Curves. Poultry, Sci. 811782-1788.
[2]. Amanullah H. M. J., Nawab K., and Ali A., (2007). Response of SLA, LAI and LAR of Maize as affected by plant density, rate and timing of nitrogen application. World Appl. Sci. J. 2, 235–243.
[3]. Amir, A. S. (2013). Application of Richards Function to the Description of Growth of Green Gram. International Journal of Farming and Allied Sciences; Vol 2:694-697.
[4]. Bethea, R. M., Duran, B. S. and Boullion, T. L. (1985). Statistical Methods for Engineers and Scientists. New York: Marcel Dekker.
[5]. Biswas, K. ; Chattopadhyay, I. ; Banerjee, R. K. ; Bandyopadhyay, U., ( 2002). Biological activities and medicinal properties of neem (Azadirachta indica). Current Sci., 82 (11): 1336-1345.

Abstract: Cholera remains a global threat to public health and key indicator of lack of social development. It has been classified as remerging global threat. The disease is primarily linked to insufficient access to safe clean water supplies, crowded living condition, poor hygiene and sanitation. The objective of the study is to model the significant factors that have effect on status (survival or death) of cholera infected person in order to predict the survival probability. Recorded data of 513 patients were obtained from UNICEF Cholera Hospital for Internally Displaced Persons within Maiduguri, Borno State of Nigeria. Descriptive and binary logistic regression were used to analyze the data. The result of binary logistic regression revealed that vaccinating a patient before the infection and mild degree of dehydration are statistically significant predictors that increases chance of survival of cholera infected person. To ensure an improved chance of cholera patient's survival effort should be made to hydrate the infected person and Vaccine (killed oral 01 with whole-cell with Bsubunit) should be administer whenever there is outbreak.

Keywords-binary logistic, cholera, odds ratio, logit model,survival probability

[1]. Pub med/Google scholarWorld Health Organization, 2016.
[2]. National Population Commission Nigeria. Accessed 25 December. 2016
[3]. Umar M Hassan and A.A. Abiodun,Survival analysis of cholera patients a parametric and non-parametric approachSCIENCEDOMAIN international, Asian Journal of Probability and Statistics,5(4): 2019, 1-18
[4]. Peng CYJ, So TSH. Logistic regression analysis and reporting (Erlbaum Associate Inc:A primer, Lawrence, 2000
[5]. Hosmer, W.D. and S. Lemeshow, Applied Logistic Regression (New York, United States of America: John Wiley and Sons, 2000).

Abstract: An industrial application of extended surfaces occurs in electric motors, which are of vital importance in the industry, as they are used in machines of all types. In this work, one-dimensional models are used to define physical and thermal characteristics to be applied to extended surfaces. Results for temperature, heat transfer rate, efficacy, and efficiency are obtained to compare one-dimensional radial fin model, "Frobenius Method," with the mathematical model already established and validated, called "Improved One-dimensional Classic Radial Fin" in the literature. The results obtained by the one-dimensional models, for effectiveness and efficiency, were compared numerically with the results of the two-dimensional model for the radial fin. The finned electric motor, with an aspect ratio of 5.82, is used to generate the numerical and graphical results. The equivalence of one-dimensional models is evident, considering the Reynolds number range and the aspect ratio value.

Keywords- Radial Fin; Frobenius Method; Improved Classical Method; Finned Electric Motor.

[1]. Felipe Suárez, Sergio D. Keeganb, Néstor J. Marianib, Guilhermo F. Barreto (2019). "A Novel One-Dimensional Model to Predict Fin Efficiency of Continuous Fin-Tube Heat Exchangers."Applied Thermal Engineering, Volume 149, 25 February, Pages 1192-1202.
https://doi.org/10.1016/j.applthermaleng.2018.12.125
[2]. R.J. Moitsheki, M.M. Rashidi, A. Basiriparsa, and A. Mortezaei. (2013)."Analytical Solution and Numerical Simulation for One‐Dimensional Steady Nonlinear Heat Conduction in a Longitudinal Radial Fin with Various Profiles."Inc. Heat Trans Asian Res; Published online in Wiley Online Library. (wileyonlinelibrary.com/journal/htj).DOI 10.1002/htj.21104
[3]. A. Aziz, Mohsen Torabi, and Kaili Zhang. (2013). "Convective–Radiative Radial Fins with Convective Base Heating and Convective–Radiative Tip Cooling: Homogeneous and Functionally Graded Materials."Energy Conversion and Management, Volume 74, October, Pages 366-376.
[4]. Marcus V. F. Soares & Élcio Nogueira (2019). "Finned Electric Motor with Prescribed Heat Fluxand Influence of the Internal and External Heat Convection Coefficients on the Temperature of the Core." Global Journal of Researches in Engineering: A Mechanical and Mechanics Engineering, Volume 19, Issue 3, Version 1.0.

Abstract: In this study, variational iteration method (VIM) is performed to elucidate the Legendre ordinary differential equations (LODEs). Before this, we apply a substitution which modifies the LODEs to a standard ordinary differential equations (SODEs). Using this substitution, this approach will be very simple and execute the results straight forward. Hence, the excellent results reveal that it is feasible to obtain an analytical or approximate solution of any problem by VIM. Some illustrations are specified, which reduces the calculation and overcomes the hurdle of nonlinear terms to demonstrate the competence of this method.

Key Word: VIM, Lagrange multiplier, Correction functional, Legendre equation

[1]. He J.H. Some asymptotic methods for strongly nonlinear equations, Internat. J Modern Phys. B 2006;20 (10):1141-1199
[2]. He J.H. Non-Pertrbative Method for Strongly Nonlinear Problems, Dissertation. de-Verlagim Internet GmbH, Berlin, 2006
[3]. He J.H. Approximate analytical solution for seepage flow with fractional derivatives in porous media, Computer Methods in Applied Mechanics Engineering1998;167:57-68
[4]. WazwazA. M. The variational iteration method for analytic treatment for linear and nonlinear ODEs, Applied Mathematics and Computation. 2009;212 (1):120-134
[5]. He J.H. Variational iteration method for autonomous ordinary differential systems, Applied Mathematics and Computation. 2000;114(2/3):115-123

Abstract: The study investigated the effect of jigsaw, team-pair-solo and reciprocal teaching strategies on secondary school students' achievement in mathematics. Four research questions and five hypotheses guided the study. The quasi-experimental design was adopted for the study. The population of the study was 4,852 senior secondary school year two (SS2) mathematics students in Onitsha Education Zone, of Anambra state. A sample of 211 SS 2 mathematics students was involved in the study. The instrument for data collection was Mathematics Achievement Test (MAT) validated by two experts from Nnamdi Azikiwe University, Awka and one experienced secondary school mathematics teacher. The reliability of the instrument was established using Kuder-Richardson Formula 20 for MAT which yielded coefficient of internal consistency of 0.71. The three experimental groups were.....

Keywords: jigsaw, team-pair-solo, reciprocal teaching, achievement, mathematics

[1]. Agoro, A.A. & Akinsola, M.K. (2013).Effectiveness of reflective-reciprocal teaching on pre-service teachers‟ achievement and science process skills in integrated science.International Journal of Education and Leadership, 1(8), 1-20.
[2]. Awan R., Noureen, I., & Naz, A. (2011).A study of relationship between achievement motivation, self-concept and achievement in English and Mathematics at secondary level.International Education Studies, 4(3), 72-79.
[3]. Bessong, F.E. & Felix, O. (2018).Evaluating secondary mathematics education in Nigeria.International Journal of Advanced Research in Public Policy, Social Development and Enterprise Studies (IJARPPSDES), 3(1), 90-99.
[4]. Bukunola, B. J. & Idowu, O.D. (2012).Effectiveness of cooperative learning strategies on Nigerian junior secondary students' academic achievement in basic science.British Journal of Education, Society & Behavioural Science, 2(3), 307-325.
[5]. Busari, O.O., Ernest, S. B., & Ugwuanyi, P.N. (2016).Effect of Computer Assisted Instruction (CAI) on senior secondary students' achievement in chemical reaction and equilibrium in Egbeda Local Government Area of Oyo State.International Journal of Secondary Education, 4(4),39-43.

Abstract: For the estimation of finite population variance in double sampling, an extended generalized class of estimators is proposed. After obtaining the bias and mean square error of the proposed estimator, it is compared with the usual conventional estimator of the finite population variance in the sense of having lesser mean square error. A subclass of estimators relying on optimum values for which the subclass achievesthe minimum mean square error is investigated and further a subclass of estimators depending upon estimated optimum value is also explored and its properties are studied.

Keywords: Bias and mean square error, Generalized class of estimators, Optimum values, Estimated optimum values and Efficient estimator

[1]. COCHRAN, W.G. (1977). Sampling Techniques (3rd Edition), John Wiley & Sons, Inc., New York.
[2]. MURTHY, M. N. (1967). Sampling Theory and Methods, Statistical Publishing Society, India.
[3]. RIZVI, S. A. M., and RIZVI, S. A. H.(2017).A Generalized Double sampling Estimator for Finite Population Variance, IOSR Journal of Mathematics (IOSR-JM), Vol. 13, Issue1 Ser.1 (Jan.-Feb.-2017), pp. 89-96, INDIA.
[4]. RIZVI, S. A. H. and SINGH, R. KARAN (2016).An Alternative Estimator of Finite Population Variance Using Auxiliary Information, Chapter 21, Recent Advances in Applied Statistics and its Applications. pp. 173-176 Lambert Academic Publishing, Republic of MOLDOVA, CHISINAU, EUROPE.
[5]. RIZVI, S. A. H., and RIZVI, S. A. M.(2009).Some Estimators of Population Variance Using Auxiliary Information, Journal of Applied Research, Vol. I, No.1, June-2009, pp. 54-61, INDIA.