Spektra: Jurnal Fisika dan Aplikasinya
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254 research outputs found
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THE COMPARISON OF 2D DOSE PATIENT-SPECIFIC QUALITY ASSURANCE BETWEEN MONTE CARLO-CONVOLUTION AND MODIFIED CLARKSON INTEGRATION ALGORITHM
Full text linkA sophisticated machine of radiotherapy treatment process follows the complexity of the quality assurance (QA) measurement. Non-measurement QA becomes one of the solutions to reduce the medical physicists’ workload. However, this method has not been clinically established. This study compared two non-measurement methods of patient-specific quality assurance (PSQA) to find the feasible algorithm for the adaptive radiotherapy process. Monte Carlo-based (MC) PSQA used a phase space file of the medical linear accelerator (Linac) to obtain the photon energy fluence and forward projected to the isoplane. In contrast, Modified Clarkson Integration-based (MCI) used a non-uniform fluence map in the isoplane. For the modulated intensity, we used a pair of the dynamic log files of the multileaf-collimator (MLC) and then employed them in the algorithms. The dose distributions of MC and MCI methods were compared to the treatment planning system (TPS) using gamma index analysis. We found that the gamma pass rates (GPR) for MC-TPS and MCI-TPS were 99.54% and 99.57%, respectively. Further, the dose distribution in the off-axis region for the MCI method showed lesser accuracy due to the higher secondary dose contribution. The linac log file information can be used and calculated into a 2D dose distribution using both MC and MCI methods, providing high-accuracy results
DEVELOPMENT OF DC-DC BUCK CONVERTER FOR SOLAR PANEL ENERGY STORAGE THROUGH LOAD OPTIMIZATION AND FEEDBACK CIRCUIT
Full text linkSolar panels are crucial components in converting sun radiation into electrical energy through the photovoltaic effect. A solar panels cannot be connected directly to the load due to its low energy conversion efficiency and low output voltage. One of the methods used to control solar cells to operate efficiently at their maximum power point is MPPT. In this paper, we design a DC-DC converter by modifications of the Butterworth filter circuit and feedback circuit in the MPPT system for storing solar panel electrical using the Hill Climbing (HC) method. The device consists of a DC-DC buck converter circuit, two pieces of INA219 sensors, a DS18B20 temperature sensor, a MAX44009 light intensity sensor, a SD card module and a DS3231 RTC. The DC-DC buck converter circuit simulation is carried out to determine the optimal load. The load optimization was conducted by analyzing the AC simulation using Ltspice software. The magnitude of the output voltage ripple in nine different loads was observed. From the simulations performed, it was found that the 50 Ω load has an output voltage ripple of 8.96 mV and is smaller than the other loads. The main DC-DC buck converter circuit is designed using a butterworth low pass filter with a cut-off frequency of 1000 Hz (R = 50 Ω, L = 33.8 mH and C = 750 nF) and a feedback circuit with a cut-off frequency of 500 Hz is added. From the prototype measurement, it was found that the average output power was 3249,7 milliwatts and the average input power was 4779 milliwatts, thus the average efficiency was 68%. With these results, the DC-DC converter circuit configuration is suitable for use in electrical energy storage systems from solar panels that have high efficiency
COMBINED METHOD OF BULK MATERIAL SHIELDING EVALUATION FOR 200 MEV HIGH ENERGY NEUTRON SOURCE USING PHITS MODELLING AND PARTIAL DENSITY
Full text linkNeutron encounters difficulties in shielding protection. Thus, many researchers have performed simulation and experimental research on neutron shielding materials. The characteristic of materials is highly dependent on neutron energy. The evaluation of neutron shielding for various materials, such as iron, concrete, aluminum, and borated polyethylene (BPE), was conducted in this paper through simulation using a Monte Carlo code of PHITS 3.27 and calculation via partial density method. A mono-energetic neutron source with an energy of 200 MeV is emitted perpendicular to the shielding material with a thickness of 105 cm. The parameters measured in this analysis include flux, fast neutron removal cross-section, neutron depth dose, ambient dose H*(10) equivalent, and neutron dose reduction factor (RF). Results show that iron is a good material against high-energy neutron and secondary photon radiation at the energy range with the highest removal cross-section and the lowest RF value (0.39), followed by concrete, BPE, and aluminum. The integrated fluence and effective dose profiles were consistent with previous results in the literature. Benchmarking calculation of neutron dose RF was conducted with other publications and was in good agreement within the value range
SYNTHESIS AND CHARACTERIZATION ANALYSIS OF FE3O4/SiO2 CORE SHELL
Full text linkFe3O4/SiO2 core shell synthesis has been carried out, and its characteristics has been analyzed to be used as a photocatalyst using co-precipitation and sol-gel method. Fe3O4 is used as the core material to eliminate the difficulty of separating the photocatalyst powder from the solution medium, SiO2 is used to avoid oxidation by preventing the Fe3O4 core from coming into direct contact with the solution. The samples were then characterized using X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR), and Vibrating Sample Magnetometer (VSM). The XRD and FTIR results showed that the crystal structure and movement of the sample molecules matched the standard characteristics from previous studies. The VSM characterization results show that SiO2 succeeded in reducing the value of the magnetization of Fe3O4, which proves that Fe3O4 has been successfully coated by SiO2
DESIGN A MONITORING SYSTEM OF A SINGLE-PHASE ELECTRICITY METER BASED ON THE INTERNET OF THINGS
Full text linkThis research aims to create systematic monitoring of a single-phase electricity meter that is accompanied by power monitoring features, the amount of electrical energy usage costs and relay control features using internet connections. The design has been carried out using PZEM-004T current and voltage sensors. The microcontrollers have been implemented by using ESP8266. This configuration is to reduce separate micro-controller. The embedded microcontroller and WiFi are made improvements from previous research. This embedded microcontroller is used to send data to the internet through WIFI. This monitoring system can then be accessed using the Cayenne interface. The test results of this tool show that the connection between the microcontroller and the Cayenne application works well through an internet connection. With this tool, users can see real-time data on the use of electrical energy and its cost, as shown in the cayenne dashboard. The voltage sensor test results show an average accuracy is 99.17%. The current sensor testing has an average accuracy rate of 96.9%. On average, the wattage delta between the cayenne dashboard and multimeter measurement is 2.16 watts