Biodiesel as renewable alternative energy produced from vegetable and animal oils can be used to fuel diesel engines. Pertamina has officially release Biodiesel B30, which sells on fuel stations in Indonesia. The purpose of this study is to investigate the diesel engine performance on Solar-Dex and Biodiesel blend. Testing the performance of a diesel engine by mixing Solar-Dex and Biodiesel on power and torque produces different data and can be concluded: (1) Pure Solar-Dex without the addition of Biodiesel gives the lowest power yield of 49.55 kW, while the data fluctuates when adding Biodiesel and it is known that the most considerable average power occurs when a mixture of Biodiesel is 30% with 70 Solar-Dex and 40% biodiesel with 60% Solar-Dex which is 54 kW. (2) Pure Solar-Dex without the addition of bio-diesel gives the lowest torque yield of 120.45 Nm, while the data fluctuates when adding Biodiesel and it is known that the most considerable average torque occurs when a mixture of 20% bio-diesel with 80 Solar-Dex is 122, 8 Nm.

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The anechoic chamber is closely related as a device for precisely measuring various acoustic characteristics. Anechoic chambers room conditions controlled to produce a sound field-free space. This study focused on testing various commercial wedges such as Eckel, diamond, pyramidal, and oblique pyramidal. The test was done by varying the elevation of an incident angle at 0°-85° with a stepping distance is 5°. This study is analyzed at 1-3 GHz frequency. This research was conducted based on a computational analysis using the finite element method on electromagnetic wave physics interfaces using COMSOL Multiphysics. The results show that, in general, pyramidal has the best performance. These results are assessed from the stability of absorption performance, the Eckel model obtains -66.6 dB at 1 GHz frequency but on another frequency tests with drastic performance fluctuations. In general, a pyramidal model can be an ideal absorber for anechoic applications because it provides good absorption performance for near normal and normal incidence angles. The results of the design and testing of the wedges model for anechoic are expected to be references in designing the optimal anechoic chamber room. Furthermore, it can contribute positively to tuning acoustic instruments such as microphones or reducing the antenna measurement error.