A sound produced from the music box could mesmerize music lovers. The complex mechanism that combined manual with semi-automatics movement creates the music box as a challenge for the manufacturer to innovate and optimize. This study focused on redesigning a hand-cranked music box's base structure using 3D printing and comparing the sound produced with the original model. It is shown that 3D printing can create a complex model with minimum material waste and good repeatability. After remodeling the music box's in a 3D CAD model, the prototype was built, and the tune played by each model was recorded and compared. The results showed that four improvements were made in the barrel mounting, crankshaft holder, crankshaft locker, and comb locker from the built four models. The sound analysis shows that the quality of sound can be improved by using the system's spacer. Furthermore, the finite element method and exact experiment results show that the loudest and best sound quality can be achieved using a 60° angle slope for the music box base structure.

Biodiesel has caught the attention of many researchers because it has great potential to be a sustainable fossil fuel substitute. Biodiesel has a non-toxic and renewable nature and has been proven to emit less environmentally harmful emissions such as hydrocarbons (HC), and carbon monoxide (CO) as smoke particles during combustion. Problems related to global warming caused by greenhouse gas (GHG) emissions could also be solved by utilizing biodiesel as a daily energy source. However, the expensive cost of biodiesel production, mainly because of the cost of natural feedstock, hinders the potential of biodiesel commercialization. The selection of natural sources of biodiesel should be made with observations from economic, agricultural, and technical perspectives to obtain one feasible biodiesel with superior characteristics. This review paper presents a detailed overview of various natural sources, their physicochemical properties, the performance, emission, and combustion characteristics of biodiesel when used in a diesel engine. The recent progress in studies about natural feedstocks and manufacturing methods used in biodiesel production were evaluated in detail. Finally, the findings of the present work reveal that transesterification is currently the most superior and commonly used biodiesel production method compared to other methods available.

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The issue of energy availability and the impact of global warming has become a specific concern for researchers in various countries in the world. This condition opens up space for potential alternative energy sources that are newer and more sustainable. Biodiesel as a sustainable alternative energy can be applied directly to industrial and automotive fields and even as a fuel source for power plants. This study provides a specific overview of the use and development of biodiesel as a fuel source for renewable power generation based on material sources. An essential part of this study discusses the development of various combinations of biodiesel mixtures and their applications in various types of industries. The physical and chemical characteristics of various types of biodiesel have been studied for their use in various parts of the world. The use of biodiesel has a positive effect on reducing emissions and pollutants, but a particular method is needed to optimize the efficiency and effectiveness, both technically and nontechnically. However, the utilization accompanied by optimizing the characteristics and parameters of biodiesel shows that this alternative energy is feasible and can be applied as a renewable fuel source for automotive industry and power generation in the future.

Based on its characteristics, biodiesel has a higher density, viscosity, and acidity level than diesel fuel, so it has a disadvantages in terms of lubricants especially in the long run. The impact, it can decrease the kinematic viscosity of the lubricant, a decrease in the total base number, and the impact by decreased of the engine performance. This research aims to determine the characteristics of lubricants from the use of biodiesel (B20 and B100) related to the kinematic viscosity of lubricants and Total Base Number (TBN). The testing method were used ASTM D2896-15 and ASTM D445-06 standard. The study used two units Kubota RD 65 DI-NB diesel engines with a cylinder volume of 376 cc. The rotary speed of the machine was keep constant at 2200 rpm and were operated for 300 hours non-stop. Moreover, the sampled was carried out every multiple of 100 hours. Based on the research results, the quality of lubricants with B100 fuel is no better than lubricants with B20 fuel. B100-fueled lubricants have kinematic viscosity values at temperatures of 40 °C and 100 °C and has lower TBN values than B20-fueled lubricants.

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