Optimum Orientation Angles for Photovoltaic Arrays to Maximize Energy Gain at Near Equator Location in Indonesia

2017 ◽  
Vol 10 (1) ◽  
pp. 86
Author(s):  
Rudi Kurnianto ◽  
Ayong Hiendro ◽  
Muhammad Ismail Yusuf
Author(s):  
Hajime Inoue

Abstract We investigate a mechanism for a super-massive black hole at the center of a galaxy to wander in the nucleus region. A situation is supposed in which the central black hole tends to move by the gravitational attractions from the nearby molecular clouds in a nuclear bulge but is braked via the dynamical frictions from the ambient stars there. We estimate the approximate kinetic energy of the black hole in an equilibrium between the energy gain rate through the gravitational attractions and the energy loss rate through the dynamical frictions in a nuclear bulge composed of a nuclear stellar disk and a nuclear stellar cluster as observed from our Galaxy. The wandering distance of the black hole in the gravitational potential of the nuclear bulge is evaluated to get as large as several 10 pc, when the black hole mass is relatively small. The distance, however, shrinks as the black hole mass increases, and the equilibrium solution between the energy gain and loss disappears when the black hole mass exceeds an upper limit. As a result, we can expect the following scenario for the evolution of the black hole mass: When the black hole mass is smaller than the upper limit, mass accretion of the interstellar matter in the circumnuclear region, causing the AGN activities, makes the black hole mass larger. However, when the mass gets to the upper limit, the black hole loses the balancing force against the dynamical friction and starts spiraling downward to the gravity center. From simple parameter scaling, the upper mass limit of the black hole is found to be proportional to the bulge mass, and this could explain the observed correlation of the black hole mass with the bulge mass.


2021 ◽  
Vol 13 (1) ◽  
pp. 433
Author(s):  
Tamer Khatib ◽  
Haneen Alwaneh ◽  
Wajdi Mabroukeh ◽  
Yassmin Abu-Ghalion ◽  
Fatima Abu-Gadi ◽  
...  

This paper presents a smartphone application game that aims to increase the awareness of preschoolers on renewable energy. The age of the selected preschoolers is in the range of 4-6 years. The game is called DAYSAM, and it aims to increase awareness regarding photovoltaic arrays, wind turbines, mini-hydropower stations, energy efficiency, and risks that polar bears are facing. The game provides two superior features compared to other available games in Arabic language, targeting the same age group. Preschoolers from An-Najah Child Institute are selected to play this game to investigate the impact of this game. The preschoolers’ awareness is tested before and after playing the game using coloring sheets in an unsupervised coloring process. The results show that the proposed game has increased preschooler’s awareness of renewable energy. Before playing the game, none of the preschoolers recognized images like the photovoltaic array or the wind turbine. After playing the game the preschoolers recognized these devices in different situations and shapes. This indicates that such a game can be used as a fun and educational tool in nurseries that have Arabic communication medium to increase awareness of renewable energy.


2021 ◽  
Vol 103 (5) ◽  
Author(s):  
Mohammad Yousuf Jamal ◽  
Santosh K. Das ◽  
Marco Ruggieri
Keyword(s):  

2021 ◽  
Vol 13 (11) ◽  
pp. 6194
Author(s):  
Selma Tchoketch_Kebir ◽  
Nawal Cheggaga ◽  
Adrian Ilinca ◽  
Sabri Boulouma

This paper presents an efficient neural network-based method for fault diagnosis in photovoltaic arrays. The proposed method was elaborated on three main steps: the data-feeding step, the fault-modeling step, and the decision step. The first step consists of feeding the real meteorological and electrical data to the neural networks, namely solar irradiance, panel temperature, photovoltaic-current, and photovoltaic-voltage. The second step consists of modeling a healthy mode of operation and five additional faulty operational modes; the modeling process is carried out using two networks of artificial neural networks. From this step, six classes are obtained, where each class corresponds to a predefined model, namely, the faultless scenario and five faulty scenarios. The third step involves the diagnosis decision about the system’s state. Based on the results from the above step, two probabilistic neural networks will classify each generated data according to the six classes. The obtained results show that the developed method can effectively detect different types of faults and classify them. Besides, this method still achieves high performances even in the presence of noises. It provides a diagnosis even in the presence of data injected at reduced real-time, which proves its robustness.


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