<p class="Abstract">Technology that is increasingly developing produces equipments in the form of information, communication, production, transportation and entertainment facilities. Most of the equipments produce noises. Noise can be reduced by using acoustic dampers. This study aims to determine the potential for sound absorption from rice husks and straw as natural acoustic materials. Materials used include rice husks, rice straw, and resin. 12 cylindrical samples were made. Samples that have been made are tested using a sound absorption measuring instrument that is the impedance tube to measure the value of the sample sound absorption coefficient. The test results show the value of the sound absorption coefficient (α) can be influenced by the thickness. At a frequency of 500 Hz the value of the sound absorption coefficient (α) for each sample is 0.034dB; 0.030dB; 0.030dB; 0.027dB; 0.026dB; 0.027dB; 0.025dB; 0.025dB; 0.025dB; 0.024dB; 0.024dB; 0.023dB; 0.023dB. The sample material is good in research on materials 1 and 2 which have a sound absorption of 0.034 dB and 0.030 dB.</p>

The research aims to determine the potential of tea waste as an environmentally friendly alternative acoustic material. The acoustic material is made by mixing tea waste powder with fox glue and water, formed, and dried. The acoustic material was made into six samples with different compositions of tea wastes, that were 20 g, 40 g, 60 g, 80 g, 100 g, and 120 g. The value of the effectiveness of noise reduction and the coefficient of sound absorption, both were obtained the most optimum in sample 6 with a composition of 120 g, that were 10.1% and 0.07497 dB. The value of both increases with the increase of the composition of the tea wastes in the acoustic material.

This research was conducted to analyze the Mg doping concentration effect on the structure, morphology, and optical properties of ZnO thin film prepared using the sol gel spin coating method. The Mg concentration was varied in the mole fraction of 1%, 3%, and 5%. Firstly, ZnO: Mg solution was dropped on a substrate and grown with a rotating speed of 3000 rpm and then annealed at 500 °C for 2 hours. The characterization of thin films' structure, morphology, and optical properties was done using XRD, FESEM, EDX, and UV-VIS spectrophotometer. XRD result showed a polycrystalline structure with three dominant peaks of (100), (002), and (101) plane, hexagonal wurtzite structures. Furthermore, the crystallite size was increased with the increase of Mg doping. FESEM results showed that the 5% ZnO: Mg thin film was the densest and least void from other films. In addition, the results of UV-Vis-NIR analysis showed the highest absorption value at a wavelength of 360-370 nm. The bandgap energy increased at 1% and 3% Mg doping samples but decreased by 5% Mg doping comes from the excess of oxygen in thin film with 5% Mg doping.

The CuInAlSe2 (CIAS)

Weather is a very important factor in supporting various human activities. However, weather is a natural event that keeps on changing due to various air conditions that affect it. One way to anticipate weather changes that may occur early is to create a system that can predict weather changes. Fuzzy logic is one of the methods that can be used in system prediction to find out the cause at a certain time and place. In this system, two fuzzy logic methods were used, they are the Mamdani and Sugeno methods, with three supporting criteria, including air temperature, humidity, and air pressure. In this research, data levers were carried out in June 2022 and resulted in a percentage accuracy of 73.34% for the Mamdani method and 70% for the Sugeno method.