Indonesian Journal of Applied Physics最新文献

Polymethylhydrosiloxane (PMHS) can be synthesized from dichloromethylsilane (DCHS) by the hydrolysis-condensation method. In this synthesis method, a solvent is needed. Dichloromethane (DCM) or diethyl ether (DE) can be used as a solvent in the synthesis of PMHS. These two solvents greatly affect the physical properties of the resulting PMHS. Therefore, studies are needed to look at the characteristics and chemical content of the PMHS synthesized using these two solvents. In this research, we reported the characteristics and content studies of PMHS synthesized using different solvents, DCM and DE, using ¹H-NMR and ¹³C-NMR. It was found that both samples had three peaks (Si-H, Si-CH₃, and Si-CH₃) on ¹H-NMR measurement and one peak (Si-CH₃) on ¹³C-NMR measurement. All of the peaks found were by the characteristics of PMHS and no other elements were found from solvents indicating that the PMHS samples had been successfully synthesized with a high degree of purity. In addition, the possibility of structures formed in the PMHS samples was also obtained.

The electric field distribution of the Neddle-Plate (NP) electrospinning set up has reported due to the simple classical electrodynamics solutions. The charge is assumed to distribute uniformly in the needle (nozzle) and the collector (plate). The electric field has an influence only in the early stage of the electrospinning process. The electric field and the viscosity of the jet fluid have caused the bending of the straight jet. The high viscosity of the fluid can preserve the straight jet length much longer. The electric field gives the initial angular momentum of the jet due to the whipping motion of the jet. For the area away from the nozzle, the electric does not influence the whipping motion. Then the whipping motion solely due to the influence from the charge repulsion of the jet fluid and the evaporation of the solvent.

In this research, the manufacture of barium hexaferrite (BaFe₁₂O₁₉) magnetic ceramics and the addition of titanium dioxide (TiO₂) additives with variations of 0%: 0.3%: 0.6% and 0.9% used the powder metallurgical method. The characterization used in this study is the measurement of density, porosity, X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Vibrating Sample Magnetometer (VSM), and Impulse Magnetizer K-Series. Based on the results of density and porosity measurements, the highest values were 4.95 g/cm3 and 5.45%, respectively. XRD results showed the formation of a BaFe₁₂O₁₉ phase with some impurities at 0% (Fe₂O₃), 0.3% and 0.9% (Ti₆O₁₁), and 0.6% (Ti₄O₇). The SEM results showed that the morphology of TiO₂-BaFe₁₂O₁₉ was quite homogeneous, and the size and cavity ranged from 0.5 – 1.5 μm and 0.25 – 0.9 μm, respectively. VSM results show Mr, Ms, Hc, and Bhmax values of 1,489 kG, 3,235 kG, 1,758 kOe, and Bhmax of 0,867 MGOe, respectively. The results of the Impulse Magnetizer K-Series show the maximum and lowest magnetic flux values of 272.65 gauss and 218.10 gauss at 0.6% and 0% variation, respectively.

The development of Dye Sensitized Solar Cells (DSSC) is increasing fast because fabrication costs are more affordable than silicon solar cells. In this study, anthocyanin pigments were used as a natural dye source. Anthocyanins are a group of flavonoids that can be extracted most proficiently in acidic conditions; therefore, variations in the composition of solvents and acids significantly impact anthocyanin yield. The anthocyanin pigments in this study were extracted from dragon fruit peels using a maceration method with variations in methanol composition and the addition of hydrochloric acid or citric acid (3/0; 3/0.5; 3/1). This study aims to improve the efficiency of DSSC by varying the solvent composition and adding Cu ion doping. The characterizations include measurement of absorbance, functional group, and efficiency using UV-Vis Spectrophotometer, Fourier Transform Infrared (FTIR), and current-voltage, respectively. The results show that anthocyanin dye with a composition of methanol/acid (3/0) and the addition of Cu ion produced the highest absorbance value and efficiency of 0.4102 Ω^-1m^-1 and 0.016%, respectively.

The absence of bow sight in a traditional bow can be replaced by introducing sight lines as a reference for accurate elevation angles in archery. Assuming a quadratic drag force acting on the arrow, a sight line can be calculated by using the values of target distances, initial arrow speed, arrow velocity decay, and the stance of the archer. This method can improve shooting accuracy for various target distances.

Four High-Frequency radar systems (HF) have been installed in Indonesia to monitor surface currents. In-situ ocean current observations are relatively expensive and limited by spatial and temporal resolution. Satellite remote sensing enables the estimate of surface current data generally from surface tracer data, including sea surface temperature (SST). Various methodologies have been developed to obtain surface currents. With Himawari-8 SST data, this study examines the accuracy of the resulting estimation. The cross-correlation fields of two identical-sized interrogation windows obtained from sequential images are employed in Particle Image Velocimetry (PIV). The HF radar in Labuan Bajo was used to validate surface current velocity estimates. RMSE, bias, and the Willmott index determined the accuracy. According to the estimates of surface currents made on July 29, 2022, the results follow a monsoon characteristic wind pattern in the Flores Sea. HF radar observations better validate the V component current estimation than the U component current estimation. A study of sea surface currents from SST data is lacking in Indonesian seas, and more repetition is required. As a result, This method has the potential can be employed to observe aquatic environments in other Indonesian areas.

The alternative provincial in Bengkulu Tengah Regency is located in a location bordering the Musi Fault segment that is part of the Great Sumatran Fault Zone. This condition makes cross-provincial roads in Central Bengkulu Regency vulnerable to natural disasters such as landslides. The purpose of the study was to determine areas that have the potential for landslides in earthquake-prone areas of Central Bengkulu Regency, Bengkulu Province, Indonesia. We performed the HVSR (horizontal to vertical spectral ratio) analysis and the simple additive weighting (SAW) method to achieve the study purpose. Field data acquisition using the PASI Gemini2 broadband seismometer (triaxial geophone). Next, we analyzed the tremor data recorded in the field using a wave spectrum. From the results of this study, we knew that the possibility of landslides in the survey area classified into three categories that is low, medium and high. Landslide risk should be paid more attention in areas with high potential, especially in densely populated areas. The main threat in the study area is an earthquake along the active Sumatran fault. Earthquakes in areas that are very steep and prone to landslides can increase the risk and cause landslides.