http://dspace.uniten.edu.my/jspui/handle/123456789/11048 2026-04-28T18:15:39Z 2026-04-28T18:15:39Z Manzoor, S. Othman, N.S. Khan, M.A. Ali, A. http://dspace.uniten.edu.my/jspui/handle/123456789/15809 2020-10-07T03:22:30Z 2019-01-01T00:00:00Z

Title: DDT-based chaotic interleaver aided cooperative OFDM system Authors: Manzoor, S.; Othman, N.S.; Khan, M.A.; Ali, A. Abstract: Typically, interleaver is used to recover information signal from outage where errors in burst form is transformed into single errors. The best interleaver should have the optimal properties of spread and dispersion. Therefore, this paper reports a method to design highly dispersive and systematic interleaver. The interleaver is designed using an incremental approach, which uses a Chaotic Logistic Map (CLM) to generate interleaver positions and utilizes the counter-based difference distribution table (DDT) that has been used in cryptanalysis, in order to achieve highly random and disperse interleaver positions by avoiding bad positions that produce repetitive pairs in the output. The proposed interleaver is implemented in single input single out (SISO) and cooperative Orthogonal frequency division multiplexing (OFDM) system. The performance of the proposed interleaver is evaluated in terms of spread, dispersion, bit error rate (BER) as a function of the burst error length and BER versus channel signal-to-noise-ratio (SNR). The performance of the proposed interleaver is compared with chaotic interleaver, block interleaver and with Matlab® random interlaever. The results show that the proposed interleaver outperforms all the interleavers considered in the simulations and there is 1 dB to 3.5 dB improvement in different scenarios of length of burst errors in terms of BER for proposed SISO OFDM systems. More specifically, the employment of the proposed interleaver in the cooperative OFDM system gives improvement of about 2.75 dB to 3.5 dB at BER = 10-2, as compared to the non cooperative OFDM systems when having the burst error length of 5 bits, 10 bits and 15 bits.

2019-01-01T00:00:00Z Hassan, N.H. Zawawi, M.H. Abas, M.A. Mazlan, A.Z.A. Zainol, M.R.R.M.A. Radzi, M.R.M. http://dspace.uniten.edu.my/jspui/handle/123456789/15482 2020-09-17T04:43:40Z 2020-01-01T00:00:00Z

Title: Numerical and Physical Model Analysis Comparison for Velocity of Water at Spillway Authors: Hassan, N.H.; Zawawi, M.H.; Abas, M.A.; Mazlan, A.Z.A.; Zainol, M.R.R.M.A.; Radzi, M.R.M. Abstract: High velocity may affect the structure integrity due to long exposure. Thus, this study was done to assess velocity specifically at energy dissipater and stilling basin of Chenderoh Dam spillway by numerical and physical model analysis. A 3D model drawing of 1:20 scaled had be drawn to be analysed and as a reference for physical model development. Numerical model had been analysed based on the fundamental of computational fluid dynamic (CFD). Physical model of the spillway has been developed to verify the accuracy of numerical model analysis. The result shows that both of the difference percentage at energy dissipater and stilling basin for velocity are less than 10% which are 4.3135% and 4.1879% respectively. Therefore, the numerical and physical model result for 1:20 scale model can be used to validate this dam numerical simulation result up to 95% precision. © 2020, Springer Nature Singapore Pte Ltd.

2020-01-01T00:00:00Z Mohd Sidek, L. Marufuzzaman, M. Rakhecha, P.R. M Radzi, M.R. Hossain, M.S. Zawawi, M.H. http://dspace.uniten.edu.my/jspui/handle/123456789/15481 2020-09-17T04:43:24Z 2020-01-01T00:00:00Z

Title: PMP Driven Probable Maximum Flood for 4 Dams in Sungai Perak Hydroelectric Scheme Authors: Mohd Sidek, L.; Marufuzzaman, M.; Rakhecha, P.R.; M Radzi, M.R.; Hossain, M.S.; Zawawi, M.H. Abstract: Probable Maximum Flood is considered as one of the most applied inflow design floods in the determination of dam structure adequacy in current practices. This study revised the inflow design flood values for Sungai Perak Hydroelectric Scheme using Probable Maximum Flood estimation. Probable Maximum Precipitation is analyzed for the catchment and the most critical rainfall values are used in establishing the maximum flood. The revised inflow design flood values for the (4) four dams are found to be 17 259.2 m3/s at Temengor Dam, 5 436 m3/s at Bersia Dam, 13 522.6 m3/s at Kenering Dam and 13 025 m3/s at Chenderoh Dam. The inflow design flood values are higher by 2%–30% for all four dams in the scheme and these dams are also found to be inadequate in terms of spillway capacities with the percentage of 5%-11% higher than the designed capacities. Further enhancement needs to be done by the dam owner either with or without structural modifications in order to protect the structure and downstream population at risk. © 2020, Springer Nature Singapore Pte Ltd.

2020-01-01T00:00:00Z Radzi, M.R. Zawawi, M.H. Yusairah, W.N. Mazlan, A.Z.A. Abas, A. Zainol, M.R.R.M.A. http://dspace.uniten.edu.my/jspui/handle/123456789/15474 2020-09-14T04:18:27Z 2020-01-01T00:00:00Z

Title: Natural Frequency Analysis for Hydropower Structure Authors: Radzi, M.R.; Zawawi, M.H.; Yusairah, W.N.; Mazlan, A.Z.A.; Abas, A.; Zainol, M.R.R.M.A. Abstract: A dam normally serves the main purpose of retaining water. However, the uncertainties vibration affected from the internal and external sources of the dam such as the flow of water vibration of the hydropower mechanical machine and other related sources has increased the insecurity of the dam structure. In this study, one of the oldest hydroelectric dams in Malaysia which are Chenderoh Dam in Kuala Kangsar, Perak is taken to analyze and discuss the structural dynamic analysis. The analysis has been investigated on the sector gate, right bank, intake and bottom outlet section of the dam structure. The actual size of structures (1:1) for each section has been modeled into the CAD software based on real build-in materials. Finite element (FE) model is constructed with the required boundary condition and meshing sensitivity analysis. From the result, the natural frequency values and mode of shapes are determined for all the section but, only significant value will be shown in this paper. The highest value of natural frequency occurred is 5.09 Hz at sector gate, 52.3 Hz at left bank, 11.73 Hz at right bank, 2.76 Hz at intake and 9.00 Hz at bottom outlet. In addition, from the frequency response friction (FRF) graphs show the highest deflection frequently occurred at x-axis direction for sector gate, right bank, bottom outlet, left bank and intake. All of these values must be taken into consideration before any failure happens at the dam. © 2020, Springer Nature Singapore Pte Ltd.

2020-01-01T00:00:00Z