http://dspace2020.uniten.edu.my:8080/handle/123456789/12752 eBooks and articles collections used by UNITEN for the process of teaching and learning in digital format 2026-07-13T12:18:40Z http://dspace2020.uniten.edu.my:8080/handle/123456789/23087 Title: Breaking A Playfair Cipher Using Single and Multipoints Crossover Based on Heuristic Algorithms Authors: Naji M.A.; Atee H.A.; Jebur R.S.; Hammood D.A.; Der C.S.; Abosinnee A.S.; Yasari A.K.I.; Ahmad R.B. Abstract: The process of data protection in our time is one of the most important challenges to maintain data integrity. The massive problem of breaking ciphertext is to find the key. In this work, cryptanalyze Playfair cipher is presented using a heuristic, and optimization methods search such as Memetic algorithm (MA) and Genetic algorithms (GA) to optimize fitness function. Di-gram letters are used as an essential factor in cryptanalyzing cipher. Mathematical methods are used to identify plain text. Furthermore, Single and multi-points crossover are used as parameters in the heuristic algorithm, and two points mutation as well. The results revealed that the multi-points are better than single point, which take a chance for exchanging the key to close the key encryption. In addition to, MA is better than GA, which the number of maximum correct letters in MA was 24 out of 25 letters after 100 generations, while in GA was 20 out of 24 letters after 200 generations. MATLAB application is used for programming and tested successfully. © 2021 IEEE. 2021-01-01T00:00:00Z http://dspace2020.uniten.edu.my:8080/handle/123456789/22166 Title: Pathe geothermal power plant, Hidalgo, Mexico: A comprehensive retrospective assessment of the first plant of its kind in the Americas Authors: DiPippo R. Abstract: In November 1959 geothermal power plants were in commercial operation in Italy since 1914, in New Zealand since 1958, and in only one other country, Mexico. It was here that the first geothermal power plant in the Americas was inaugurated at Pathé on November 20, 1959. The United States joined this exclusive club the next year when it inaugurated the PG&E Geysers Unit 1 in Northern California in September 1960. This article summarizes the historic development of geothermal energy with an emphasis on Mesoamerica. This account of the Pathé plant covers its geological environment, field development, unit design, operations and economics, and preservation after reaching the end of its operational life. The account concludes with some thoughts on the future of the Pathé geothermal field. © 2021 2022-01-01T00:00:00Z http://dspace2020.uniten.edu.my:8080/handle/123456789/22165 Title: Structural changes and trends in China's renewable electricity production in the policy evolution process Authors: Wang Y.; Shi R.; Zhang C.; He Y.; Jiang H.; Kubota J. Abstract: This study employs the econometrics test of endogenous structural breaks to separately investigate the changes in trends of the share of hydropower and non-hydro renewable power in electricity production for China using two separate sub-panels of data spanning from 1971 to 2015 and 1990–2015. To identify structural changes in each renewable power generation series, we apply the Bai and Perron procedure for determining structural breaks to estimate shifting-mean autoregressions and use the low frequency Fourier-type Lagrange Multiplier test to approximate the time series in a non-linear form. Through these tests, our empirical results reveal that the series under investigation are characteristic of segmented trend stationary processes around four or one structural breaks, among which, there are two upward shifts in the 45-year series of hydroelectricity generation occurring in 1978 and 2008, respectively. Meanwhile, one upward shift is identified in the 26-years series of non-hydro renewable generation occurring in 2005. The patterns in the timing of structural changes are suggestive of the causal effects from the recent regulatory shocks and policy change. In the present study, we conduct an innovative attempt to reveal the relevance of renewable energy and policy changes, which may also provide some empirical value in investigating the effect of policy series on renewable energy in other countries. © 2021 2022-01-01T00:00:00Z http://dspace2020.uniten.edu.my:8080/handle/123456789/22164 Title: Evaluation of the multi-doublet performance in sandstone reservoirs using thermal-hydraulic modeling and economic analysis Authors: Ke T.; Huang S.; Xu W.; Tang X.; Li X. Abstract: A good understanding of the long-term multi-doublet performance is imperative to sustainable and economical hydrothermal production with reinjection in sandstone reservoirs. This paper presents a case study from the Guanzhong Basin, northwest China to systemically evaluate the performance of different multi-doublet layout plans in two sandstone reservoirs through 3D thermal-hydraulic modeling and economic analysis. Based on the single-doublet models designed to determine the optimal well spacing to improve heat extraction performance, the multi-doublet models are established for five multi-doublet layout plans with different well spacing at 500, 600, and 700 m and flow rate at 125 and 200 m³ h−1, respectively. Results indicate that the different layouts and doublet orientations with respect to the natural groundwater flow can lead to a difference of about 25% in energy production and 15% in the Levelized Cost of Heat (LCOH) for an assumed lifespan of 50 years. The well spacing and flow rate have a great impact on the determination of the optimal multi-doublet layout. The change in well spacing can lead to a difference up to 35% in energy production and 25% in LCOH, and the change in flow rate can lead to a difference up to 54% in energy production and 40% in LCOH. Compared with checkboard configurations, better doublet performance is achieved in tramline configurations due to a strong cross flow occurs among doublets. Moreover, the reservoir with greater permeability has higher recovery efficiency and prominent superiority of tramline configurations. Results offer decision-making support to the geothermal development in the areas where 100% fluid reinjection is mandated for environmental and resource conservation. © 2021 Elsevier Ltd 2022-01-01T00:00:00Z