Bualkar Abdullah

Nanocomposites Fe/Activated Carbon/PVA for Microwave Absorber: Synthesis and Characterization

Nanocomposites, activated carbon/polyvinyl alcohol (AC/PVA) filled with Fe to form Fe/AC/PVA, were characterized by using X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and vector network analyzer (VNA). The crystal orientations from Fe are (104), (110), and (200) and the bonding formations of AC are O-H, C-H, and C=C show existence in nanocomposites, which may be due to the Fe that has been filled the pore of AC via a chemical bond. 20% AC (3 mm in thickness) in nanocomposites shows higher performance absorption for C-band (4.65 GHz) with maximum reflection loss of −32.5 dB.

Comparison of sensitivity and resolution load sensor at various configuration polymer optical fiber

This study uses a load sensor with a macro-bending on polymer optical fiber loop model which is placed between two plates with a buffer spring. The load sensor with light intensity modulation principle is an infrared LED emits light through the polymer optical fiber then received by the phototransistor and amplifier. Output voltage from the amplifier continued to arduino sequence and displayed on the computer. Load augment on the sensor resulted in an increase of curvature on polymer optical fibers that can cause power losses gets bigger too. This matter will result in the intensity of light that received by phototransistor getting smaller, so that the output voltage that ligable on computer will be getting smaller too. The sensitivity and resolution load sensors analyzed based on configuration with various amount of loops, imperfection on the jacket, and imperfection at the cladding and core of polymer optical fiber. The results showed that the augment on the amount of load, imperfection on the jacket an...

Study of Image Quality, Radiation Dose and Low Contrast Resolution from MSCT Head by Using Low Tube Voltage

Effect of low tube voltage (80 kV) on image quality, radiation dose, and low contrast (LCD) detection capability on CT Scan head was studied by using a solid phantom contains four modules with scanning CT at 80 and 120 kV tube voltages, with tube current timing at 200, 250 and 300 mAs. The difference between image noise, noise to ratio contrast and LCD values obtained with 80 and 120 kV at 200, 250 and 300 mAs were then compared. Substantially the image noise increases with the use of low tube voltage. However, with the same dose, the LCD values are between 120 kV at 300 mAs and 80 kV at 200, 250 and 300 mAs (P> 0.05). The relative dose given at 80 kV against 200, 250 and 300 mAs is equal to 68%. By reducing the tube voltage from 120 kV to 80 kV at head CT, the radiation dose can be reduced by 32% without CNR and LCD degradation.

Dye sensitized solar cell (DSSC) with natural dyes extracted from Jatropha leaves and purple Chrysanthemum flowers as sensitizer

DSSC (Dye-Sensitized Solar Cell) prototype has been investigated using Jatropha leaves and purple Chrysanthemum flowers as natural dyes. DSSC consists of working electrode and counter electrode. A working electrode composed of semiconductor nanoparticles TiO2 that has been coated with dye molecules. Dye molecules serve as light photon catchers, while semiconductor nanoparticles TiO2 function to absorb and forward photons into electrons. In the electrode counter given catalyst carbon, serves to accelerate the reaction kinetics of triiodide reduction process on transparent conductive oxide (TCO). DSSC using TiO2 as a semiconductor material and natural dyes as sensitizer from Jatropha leaves and purple Chrysanthemum flowers are successful produced. The physical properties of the working electrode have been determined by using XRD and the chemical properties of the TiO2 powder and dye powder using FTIR and dye solution using UV-Vis. The resulted fabrications are also examined its I-V characteristics. The best performance is generated by mixed dye 1.91 x 10−3 % compared than those DSSC for dye extracted from Jatropha leaves or purple Chrysanthemum. The characterization results show that the higher of the absorption wavelength of the DSSC efficiency is high.

Measurement of radiation distribution for radon (Rn) and thoron (Th) concentrations in heritage Gua Batu and Gua mimpi of maros regency, South Sulawesi

Measurement of natural radiation produced by radioactivity such as radon and thoron has been observed in Gua mimpi and Gua batu caves, Bantimurung. South Sulawesi. This study measured the intensity of the Radon and thoron radiations using Trace Detector Nuclear CR-39 (Baryotrex) as a passive dosimeter. Measurements were performed in two phases, which direct measurements by using RAD 7 at several locations namely in the area of the door and the middle of the cave. It is intended to fine the concentration of radon and thoron radiation content in the cave. Passive measurement is done by putting a nuclear trace detector at some point in the cave and kept within 3 months. The data analysis performed at the Center Safety technology and radiation metrology of National Nuclear Energy Agency (PTKMR-BATAN). The result of thoron gas concentrations in the mouth of the Gua mimpi shows the average 9.50 pCi/l, while in the middle of the cave by 34,5pCi/l. Result for direct measurements obtained using a sun nuclear of ra...

Physical Properties of Nyamplung Oil (Calophyllum inophyllum L) for Biodiesel Production

This research is intended to measure the physical properties of nyamplung oil using FFA method to analyze the density of biodiesel as a standard quality.

Design of sensor water turbidity based on polymer optical fiber

This research discusses about polymer optical fiber sensor for measurement of water turbidity. The main material used was an infrared LED, polymer optical fiber and photodetector. Turbidity sensor based on polymer optical fiber has two types; optical fiber sensor with cladding and without cladding. The sensor is made with different types of length and configuration. Turbidity sensor was made, dipped into a turbidity water sample. The measurement was concentration with turbidity percentage. The results showed that the output voltage is affected by the changes of turbidity concentration, sensor length, with or without cladding, and curvature sensor. The bigger of bending of the optical fiber will cause the increasing power losses so the light intensity will be smaller, consequences the measured output voltage will be smaller. Sensitivity and resolution turbidity sensor with cladding showed the best result rather than turbidity sensor without cladding. The best sensor configurations was u with 2 cm lenght and showed output power range, sensitivity, and resolution were 0,931 μW, 0,046 μW/NTU, and 0,022 NTU, respectively.