Analysis of rainfall data of some West African countries using wavelet transform and nonlinear time series techniques

2022 ◽  
pp. 1-12
Author(s):  
E. O. Falayi ◽  
J. O. Adepitan ◽  
A. T. Adewole ◽  
T. O. Roy-Layinde
Keyword(s):  
Time Series ◽  
Wavelet Transform ◽  
Nonlinear Time Series ◽  
West African ◽  
Rainfall Data ◽  
African Countries

scholarly journals RAINFALL ANALYSIS IN KLANG RIVER BASIN USING CONTINUOUS WAVELET TRANSFORM

2016 ◽  
Vol 10 (1) ◽  
pp. 3-10 ◽  
Author(s):  
Celso A. G. Santos ◽  
Richarde Marques Silva ◽  
Seyed Ahmad Akrami
Keyword(s):  
Time Series ◽  
Wavelet Transform ◽  
River Basin ◽  
Continuous Wavelet Transform ◽  
Rainfall Data ◽  
Accurate Information ◽  
Rainfall Time Series ◽  
Continuous Wavelet ◽  
Rainfall Analysis ◽  
Frequency Components

The rainfall characteristics within Klang River basin is analyzed by the continuous wavelet transform using monthly rainfall data (1997–2009) from a raingauge and also using daily rainfall data (1998–2013) from the Tropical Rainfall Measuring Mission (TRMM). The wavelet power spectrum showed that some frequency components were presented within the rainfall time series, but the observed time series is short to provide accurate information, thus the daily TRMM rainfall data were used. In such analysis, two main frequency components, i.e., 6 and 12 months, showed to be present during the entire period of 16 years. Such semiannual and annual frequencies were confirmed by the global wavelet power spectra. Finally, the modulation in the 8–16-month and 256–512-day bands were examined by an average of all scales between 8 and 16 months, and 256 and 512 days, respectively, giving a measure of the average monthly/daily variance versus time, where the periods with low or high variance could be identified.

scholarly journals A novel subband forecast method for nonlinear time series using wavelet transform

2005 ◽  
Vol 54 (5) ◽  
pp. 1988
Author(s):  
Lei Ming ◽  
Han Chong-Zhao ◽  
Guo Wen-Yan ◽  
Wen Xiao-Qin
Keyword(s):  
Time Series ◽  
Wavelet Transform ◽  
Nonlinear Time Series ◽  
Forecast Method

EXPERIMENTALLY OBTAINED BIFURCATION PHENOMENON IN CHAOTIC TRACTOR VIBRATING IN TIME AND FREQUENCY DOMAIN

2005 ◽  
Vol 15 (01) ◽  
pp. 225-231 ◽  
Author(s):  
L. O. GARCIANO ◽  
K. SAKAI ◽  
R. TORISU
Keyword(s):  
Time Series ◽  
Wavelet Transform ◽  
Continuous Wavelet Transform ◽  
Period Doubling ◽  
Nonlinear Resonance ◽  
Nonlinear Time Series ◽  
Continuous Wavelet ◽  
Bifurcation Phenomenon ◽  
Dominant Feature ◽  
Positive Exponent

This paper investigates through experimental methods the dynamic characteristics of a farm tractor by changing the forward velocity from 0.63 m/s to 4.50 m/s. Nonlinear time series, frequency spectrum and continuous wavelet transform were used in the analysis. From the nonlinear time series analysis, a nonlinear resonance of the tractor vibration occurred at forward velocity of 2.15 m/s. The existence of a subharmonic frequency at 4.32 m/s indicated chaotic dynamics that was confirmed by the trend of the Lyapunov exponent analysis with a positive exponent indicating chaos. Continuous wavelet transform analysis results, presented graphically, called coefficient plots showed patterns composed of large and fine feature distribution in both time and scale. Quasi-periodic velocities of 1.95 m/s and 2.15 m/s were estimated by these coefficient plots. At forward velocity of 2.88 m/s, the coefficient plots showed dominant features that varied periodically and were estimated to be a period-doubling vibration. The coefficient plots during chaotic vibration at 3.52 m/s, 4.02 m/s and 4.32 m/s showed various feature distributions. At forward velocities of 0.95 m/s and 1.42 m/s, the existence of features with scale values of almost equal and half of the dominant feature was due to the influence of the gravel road surface and not to the artificial test track profile. Experimentally obtained bifurcation was observed clearly from the coefficient plots that showed three different patterns from quasi-periodic vibration at 2.15 m/s, period-doubling at 2.88 m/s and chaos at 3.52 m/s.

scholarly journals RAINFALL ANALYSIS IN KLANG RIVER BASIN USING CONTINUOUS WAVELET TRANSFORM

2016 ◽  
Vol 10 (1) ◽  
pp. 3-10
Author(s):  
Celso A. G. Santos ◽  
Richarde Marques Silva ◽  
Seyed Ahmad Akrami
Keyword(s):  
Time Series ◽  
Wavelet Transform ◽  
River Basin ◽  
Continuous Wavelet Transform ◽  
Rainfall Data ◽  
Accurate Information ◽  
Rainfall Time Series ◽  
Continuous Wavelet ◽  
Rainfall Analysis ◽  
Frequency Components

The rainfall characteristics within Klang River basin is analyzed by the continuous wavelet transform using monthly rainfall data (1997–2009) from a raingauge and also using daily rainfall data (1998–2013) from the Tropical Rainfall Measuring Mission (TRMM). The wavelet power spectrum showed that some frequency components were presented within the rainfall time series, but the observed time series is short to provide accurate information, thus the daily TRMM rainfall data were used. In such analysis, two main frequency components, i.e., 6 and 12 months, showed to be present during the entire period of 16 years. Such semiannual and annual frequencies were confirmed by the global wavelet power spectra. Finally, the modulation in the 8–16-month and 256–512-day bands were examined by an average of all scales between 8 and 16 months, and 256 and 512 days, respectively, giving a measure of the average monthly/daily variance versus time, where the periods with low or high variance could be identified.

The Contribution of Foreign Direct Investment for Economic Growth of Ethiopia: Time Series Analysis

2018 ◽  
Vol 9 (02) ◽  
Author(s):  
Addissie Melak
Keyword(s):  
Economic Growth ◽  
Time Series ◽  
Foreign Direct Investment ◽  
Time Series Analysis ◽  
Direct Investment ◽  
Policy Framework ◽  
Annual Growth Rate ◽  
African Countries ◽  
Series Analysis ◽  
Integration Test

Economic growth of countries is one of the fundamental questions in economics. Most African countries are opening their economies for welcoming of foreign investors. As such Ethiopia, like many African countries took measures to attract and improve foreign direct investment. The purpose of this study is to examine the contribution of foreign direct investment (FDI) for economic growth of Ethiopia over the period of 1981-2013. The study shows an overview of Ethiopian economy and investment environment by the help of descriptive and econometric methods of analysis to establish empirical investigation for the contribution of FDI on Ethiopian economy. OLS method of time series analysis is employed to analyse the data. The stationary of the variables have been checked by using Augmented Dickey Fuller (ADF) Unit Root test and hence they are stationery at first difference. The co- integration test also shows that there is a long run relationship between the dependent and independent variables. Accordingly, the finding of the study shows that FDI, GDP per capita, exchange rate, total investment as percentage of GDP, inflow of FDI stock, trade as percentage of GDP, annual growth rate of GDP and liberalization of the economy have positive impact on Ethiopian GDP. Whereas Gross fixed domestic investment, inflows of FDI and Gross capital formation influence economic growth of Ethiopia negatively. This finding suggests that there should be better policy framework to attract and improve the volume of FDI through creating conducive environment for investment.

The Coin of the African Realm

2017 ◽  
Author(s):  
Jeffrey Herbst
Keyword(s):  
Twentieth Century ◽  
West Africa ◽  
West African ◽  
Regional Economies ◽  
African Countries ◽  
New Strategies

This chapter examines the politics of the currency in West Africa from the beginning of the twentieth century. A public series of debates over the nature of the currency occurred in West Africa during both the colonial and independence periods. Since 1983, West African countries have been pioneers in Africa in developing new strategies to combat overvaluation of the currency and reduce the control of government over the currency supply. The chapter charts the evolution of West African currencies as boundaries and explores their relationship to state consolidation. It shows that leaders in African capitals managed to make the units they ruled increasingly distinct from the international and regional economies, but the greater salience of the currency did not end up promoting state consolidation. Rather, winning the ability to determine the value of the currency led to a series of disastrous decisions that severely weakened the states themselves.

Political Stability in West African States: Problems and Solutions. (Case Studies of Côte d’Ivoire and Senegal)

2018 ◽  
pp. 75-88
Author(s):  
Lyubov Sadovskaya
Keyword(s):  
Cote D'ivoire ◽  
Côte D’Ivoire ◽  
Political Stability ◽  
West African ◽  
The Political ◽  
Political Systems ◽  
African Countries ◽  
Cote D’Ivoire ◽  
External Threats ◽  
Côte D'ivoire

The article presents a new view on the problems of political stability in West African countries. For the first time was carried out a comparative analysis of the sustainability of the political systems of the two Francophone fastest growing countries in West Africa, Côte d’Ivoire and Senegal. The author analyzes the factors negatively influencing political stability social order, and those that reduce conflict potencial in these States. Internal and external threats to the political systems of Senegal and Сôte d’Ivoire are examined. The response of both countries to internal and external challenges is shown. The study proves that while external threats indanger Senegal’s political stability, such as the penetration of religious extremism, the crisis in Casamance, maritime piracy, drug traffic, for Côte d’Ivoire, on the contrary, main risks are internal: electoral, socio-political crises, the split of elites, arms smuggling, banditry. The study demonstrates that the level of social governance in Senegal is higher than in other West African countries, including Сôte d’Ivoire, due to the dualism of the political system: the coexistence of Western-style political institutions with local faiths (tariqas), as well as policy pursued by President M. Sall. aimed at achieving mutual compromise that ensure the peaceful settlement of conflicts and contradictions. The author concludes that a new approach to the development of a security strategy is required.

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