Mathematical Theory and Modeling
http://www.iiste.org/Journals/index.php/MTM
<p><span id="internal-source-marker_0.04939836589619517"><span id="internal-source-marker_0.04939836589619517">Mathematical Theory and Modeling </span>is a peer reviewed journal published by IISTE. The journal publishes original papers at the forefront of mathematical theories, modelings, and applications. The journal is published in both printed and online versions. The online version is free access and download.</span></p><p><span>IISTE is member of <a href="http://www.crossref.org/01company/17crossref_members.html">CrossRef</a>.<br /></span></p>en-USMathematical Theory and Modeling2224-5804Computer Simulation of the Mathematical Models for the Determination of the Uplift Resistance of a Gas Pipeline
http://www.iiste.org/Journals/index.php/MTM/article/view/40507
<p>Mathematical models for the determination of the uplift resistance of gas pipelines network system have been developed. The computer simulation of the mathematical models is the bane of this work. The paramount parameters in view to be determined by computer simulated algorithms are optimal wall thickness, the restoring moment, pipe deflection and pipe support spacing for a laid pipeline to avoid buckling of the pipeline subject to the different loading conditions. At nominal pipe wall thickness of 11cm, the simulated optimal wall thickness is 17cn. The simulation results confirmed the deflection of the pipe as -2.698m, the restoring force as -3.33x10<sup>17</sup>N. Subject to these findings, three pipe supports are required to bear restoring the load of 1.11x10<sup>17</sup>N at each support.<strong> </strong></p> <p><strong>Keywords: </strong>Uplift Resistance; Earth Mass Centroid; Pipe Thickness; Maximum Deflection; Internal Fluid Pressure; External Loads; Support Reaction; Buckling Load.</p> <p> </p>Mathew, Shadrack UzomaTobinson A. Briggs8The Development of Learning Devices Based Realistic Approach for Increasing Problem Solving Mathematics Ability of Student in SMPS Gema Buwana
http://www.iiste.org/Journals/index.php/MTM/article/view/40508
<p><em>This type of research was a of learning devices with the aim to produce devices based learning approach that was valid realistic mathematics, practical and effective, and all the instruments of research related to the application of these devices in the learning of mathematics on the subject of rectangle and square for seventh grade students of SMP. This study was conducted in two stages, namely the first stage was the development of learning tools. The development of devices based learning mathematics realistic approach with reference to the development model learning device according to Thiagarajan, and Semmel Semmel ie 4-D models (four D models). The second stage was the implementation of learning devices that were considered feasible. The design of the trials was a one-group posttest-only design. The findings of the research were: 1) the resulting learning, such as: lesson plan, student books, student activity sheet, and test problem solving had met the criteria of good / valid; 2) The effectiveness of the learning device inferred based on: (i) complete student learning classical at the first trial amounted to 85.17% and in the second test by 90%, (ii) achievement of learning goals at the trials I was not achieved in a matter of question number 3 and 4 and no trial II was reached on each item, (iii) the performance of the ideal time at the trial I and II trials were ideal, 3) The student’s response to the component and learning activities was postive.</em></p> <p><strong><em>Keywords: </em></strong><em>Learning devices, Realistic Approach, 4-D Development Model, Problem Solving Mathematics ability.</em></p> <p> </p>Selvi Septiani HarahapHasratuddin .Elmanani Simamora8Stability Results of Nonlinear Integro-differential Equations
http://www.iiste.org/Journals/index.php/MTM/article/view/40509
<p>In this paper, the stability of a class of nonlinear integro-differential equation is investigated and analyzed. By defining a suitable Lyapunov functional we establish necessary and sufficient condition -for the stability of the zero solution. Our results extends known results in the literature.</p> <div><p><strong>Keywords: </strong>Integro-differential equation, Lyapunov functional, Nonlinear, Stability.<strong></strong></p></div>Prebo Clifford JackreeceStephen Aniaku8Vector Autoregressive Models for Multivariate Time Series Analysis; Macroeconomic Indicators in Ghana
http://www.iiste.org/Journals/index.php/MTM/article/view/40510
<p>This study investigated the relationship, the percentage contribution of endogenous shocks and the direction of causality between real gross domestic product, exchange rate, foreign direct investment and unemployment rate in Ghana. It employed the multivariate Johansen co-integration test via vector auto-regressive model and the vector error correction model, to examine both long-run and short-run dynamic relationships respectively, between the selected macroeconomic variables for the period 1991-2016. The dynamic interactions between the variables were studied with Granger causality tests, impulse response functions, and forecast error variance decompositions. Augmented Dickey-Fuller (ADF) test indicated that all the variables were stationary after their first differencing, thus variables are integrated of order one, I (1). The diagnostic tests on the model residuals revealed that the models were adequate, valid and stable. The Trace test statistic of the Johansen cointegration test indicated one cointegrating relationship indicating long run relationship among the variables. Granger Causality analysis indicated a uni–directional causal relationship between real GDP and FDI. It also showed that FDI Granger-causes all of the other variables. The results revealed the positive effect and sensitivity of the FDI variable in determining the activities pertaining to real GDP, exchange rate, and unemployment rate and vice versa in the Ghanaian economy.</p> <p><strong>Keywords: </strong>Vector Autoregression Model (VAR), Multivariate Time Series, Macroeconomic Variables, Cointegration, Granger causality, Impulse response function, Forecast error variance decomposition,</p> <p> </p>Erasmus Tetteh-BatorMohammed Adjei AdjietehLin Chun JinTheophilus Quachie Asenso8A NEW MODIFIED GENERALIZED ODD LOG-LOGISTIC DISTRIBUTION WITH THREE PARAMETERS
http://www.iiste.org/Journals/index.php/MTM/article/view/40511
<p>Statistical distributions are very useful in describing and predicting real-world phenomena. Numerous extended distributions have been extensively used over the last decades for modeling data in many applied sciences such as medicine, engineering and finance. Recent developments focus on defining new families that extend well-known distributions and at the same time provide great flexibility in modeling data in practice. In this paper, we have introduced a new three-parameter exponential distribution called the generalized odd log-logistic-exponential distribution by using the generator defined by Cordeiro et al (2017). This model extends the odd log-logistic-exponential and exponential distributions. Several of its structural properties are discussed in detail. These include shape of the probability density function, hazard rate function, quantile function order statistics, and moments. The method of maximum likelihood is adopted to estimate the model parameters. The applicability of the new models is illustrated by using real data. The goodness-of-fits of the exponential, beta exponential, Kumaraswamy exponential and the generalized odd log-logistic-exponential distributions have been compared through the AIC, AICC, BIC and KS statistics and found that the generalized odd log-logistic-exponential distribution fits well the data.</p> <p><strong>Key Word</strong>: Exponential distribution, odd log logic distribution, maximum likelihood estimation, Monte Carlo.<em></em></p>Arber QoshjaMarkela Muca8