Mohd Aftar Abu Bakar

Exploratory data analysis of Twitter’s rhythm in Malaysia

Twitter is a social media service which enable users to send and also received messages or post known as tweet. In the era of big data, one of the main source of data is from Twitter. However, this types of data usually are unstructured, massive and complicated to be analyzed. In this study, Twitter’s data from Malaysian users were collected for one whole week. The objectives are to study the daily rhythm of Twitter usage in Malaysia and also to identify relationships between various types of Twitter users in Malaysia. Since the data are unstructured, pre-processing technique have to be done on the collected data which will enable the data to be analysed. The post-processed data were then analyze by using various statistical analysis tools. From the result of the analysis, we observed some interesting findings which are useful on the describing usage behaviour of Malaysian Twitter users.Twitter is a social media service which enable users to send and also received messages or post known as tweet. In the era of big data, one of the main source of data is from Twitter. However, this types of data usually are unstructured, massive and complicated to be analyzed. In this study, Twitter’s data from Malaysian users were collected for one whole week. The objectives are to study the daily rhythm of Twitter usage in Malaysia and also to identify relationships between various types of Twitter users in Malaysia. Since the data are unstructured, pre-processing technique have to be done on the collected data which will enable the data to be analysed. The post-processed data were then analyze by using various statistical analysis tools. From the result of the analysis, we observed some interesting findings which are useful on the describing usage behaviour of Malaysian Twitter users.

Comparison between content-based and collaborative filtering recommendation system for movie suggestions

In this current and recent decade, various data and information are actively collected. The problem with increasing data from year to year has made it difficult for people to make the right decisio...

Multi-criteria decision-making analysis in selecting suitable plotting positions for IDF curves of storm events

Selecting suitable distributions for rainfall data is usually subjective and complex since it requires decision-makers to consider results from various measures of goodness-of-fit indices. In this study, the VIKOR method in multi-criteria decision-making analysis is modified to select the most suitable plotting positions to represent extreme storm intensities in order to build the intensity–duration–frequency (IDF) curves of storm events. This is done by considering the rankings provided by all goodness-of-fit indices used to obtain a compromise solution. Nine plotting positions are considered: Weibull (W), Adamowski (A), Gringorten (G), Hazen (H) and Gumbel (EV I) and two known plotting positions for generalized extreme value (GEV) distribution using Pearson’s skewness and another two using L-skewness. The IDF curves obtained are compared to a reference IDF curves which was found using the GEV distribution. The mean and median for three goodness-of-fit indices, the coefficient of variation of root mean square error, CVRMSE, the mean percentage of difference, Δ, and the coefficient of determination, R2, are taken as the criteria for selection process. The results show that six plotting positions, A, H, W, G and the two plotting positions with L-skewness, are equally superior compared to the other three plotting positions.

Time series ARIMA models for daily price of palm oil

Palm oil is deemed as one of the most important commodity that forms the economic backbone of Malaysia. Modeling and forecasting the daily price of palm oil is of great interest for Malaysias economic growth. In this study, time series ARIMA models are used to fit the daily price of palm oil. The Akaike Infromation Criterion (AIC), Akaike Infromation Criterion with a correction for finite sample sizes (AICc) and Bayesian Information Criterion (BIC) are used to compare between different ARIMA models being considered. It is found that ARIMA(1,2,1) model is suitable for daily price of crude palm oil in Malaysia for the year 2010 to 2012.

Unscented Kalman filtering for wave energy converters system identification

A model for a oscillating flap wave energy converter (WEC) is as a single degree of freedom system with a non-linear term to allow for the drag of the device through the water, known as the Morison term. The focus of this system identification is on estimating the dynamic state of the system and estimating the non-linear parameter from observations of the wave elevation and the vertical displacement of the device. It is assumed that the mass, stiffness and damping of the system, without the Morison term, are known from the physical characteristics of the device. The Kalman Filter (KF) can be used to estimate the states of a linear system, however, it is not directly applicable to a non-linear system. Various adaptations have been proposed for non-linear systems. One of the first was the extended Kalman Filter (EKF) which relied on a linearization about the current state values. However, an alternative approach, known as the unscented Kalman Filter (UKF) has been found to give a better performance and is e...

Comparison of heaving buoy and oscillating flap wave energy converters

Waves offer an attractive source of renewable energy, with relatively low environmental impact, for communities reasonably close to the sea. Two types of simple wave energy converters (WEC), the heaving buoy WEC and the oscillating flap WEC, are studied. Both WECs are considered as simple energy converters because they can be modelled, to a first approximation, as single degree of freedom linear dynamic systems. In this study, we estimate the response of both WECs to typical wave inputs; wave height for the buoy and corresponding wave surge for the flap, using spectral methods. A nonlinear model of the oscillating flap WEC that includes the drag force, modelled by the Morison equation is also considered. The response to a surge input is estimated by discrete time simulation (DTS), using central difference approximations to derivatives. This is compared with the response of the linear model obtained by DTS and also validated using the spectral method. Bendats nonlinear system identification (BNLSI) techni...