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The research was conducted to recycle surgical masks as acoustic panels using hand lay-up methods and to test their effectiveness in reducing noise using the tube method. The frequency used as a sound source is 495 Hz. Tests were carried out with variations in panel thickness, they are 1 cm, 2 cm, 3 cm, 4 cm, and 5 cm and three variations composite material, they are first layer, second layer and third layer of surgical mask. The panel test results show that the thicker acoustic panels are more effective in reducing noise based on the regression analysis that show the thicker panel from three variations composite material is 0.98, 0.99 and 0.96, respectively all of which are included in the very strong category. In addition, ANOVA analysis show that the thicker panels from all variation composite material respectively was 0.002, 0.001 and 0.009, they are showed the significant effect between the thickness of the panel and the effectiveness of the panel in reducing noise. Furthermore, based on the regression analysis from acoustic panels composite made of surgical masks from first layer, second layer and third layer were 8.24, 8.39 and 5.81, respectively the panel acoustic from second layer surgical masks are more effective to reduce the noise than other layer. Overall, it can be concluded that acoustic panels made of surgical masks are effective in reducing noise, as well as a solution to increasing surgical mask waste during the Covid-19 pandemic.

An analysis of the quality of the lighting level in the classroom needs to be carried out to determine the existing lighting level. If the level of lighting is below the specified standard, it can cause eye damage. Meanwhile, if the level of lighting is above the standard, the classroom will be too bright. The purpose of this study was to determine the level of lighting in the Regular and Full Day classroom of MTs. Miftahul Huda Tayu. The tools and materials used in this experiment are lux meter, roller meter and thermohygro. The experiment was carried out in the Regular class school building and the Full Day classroom building with a sample of three rooms per building with each room representing each floor. The experiment was carried out during the day for three consecutive days. There are two types of the intensity measured in this experiment, namely natural intensity (lights off) and natural artificial intensity (lights on). In each room, 9 points were taken. The floor area and window area were measured using a roller meter. From the experiments that have been carried out, it can be concluded that the lighting in the Regular class (17-73 lux) and Full Day class (97-181 lux) buildings do not meet Indonesian National standards (Standar Nasional Indonesia, SNI).

The study aim is to analyze soil quality for dryland agriculture with variations in fertilization and plant rotation in Argomulyo sub-district, Salatiga city. This study took samples on dryland agricultural land in Ledok Village by taking sample points using random sampling with a cluster sampling pattern by dividing them into 4 clusters. The Step of the research are field and laboratory observation to know the soil pH and moisture, also to determine the soil value and cation test, respectively. Next is the interview step to know the effect of fertilization and plant rotation variation. This research uses quantitative description analysis techniques. Based on the field observation was obtained the cluster 2 has pH value around 6.5 in the category slightly acidic. Then, for cluster 1,3, and has 4 neutral pH category in the range 6.6 – 7.5. The humidity of clusters in the dry category is in the range of 0 - 30%. Laboratory observation shows cluster 3 has a lower resistance around 8.1KW and has the best cation exchange capacity (CEC) test compared with other clusters. Based on the results of interviews, cluster 2 received organic fertilization and crop rotation occurred. Clusters 1 and 4 have not received any planting activity since October 2020. Meanwhile, fertilization in cluster 3 uses inorganic fertilizers. So Cluster 2 soil quality is better than the other three clusters due to organic fertilization and plans rotation so that the soil nutrients become stable. Cluster 1 has poor soil quality due to variations in inorganic fertilization, neglecting the soil, and being planted Manihot esculenta which impacted the reduction in the amount of nitrogen and phosphorus in the land.

This paper demonstrates an optical waveguide based- refractive index (RI) sensor using the temperature compensation method. The optical waveguide was formed using a polymethylmethacrylate sheet as the cladding material and unsaturated polyester resin as the core material. The sensor design consists of two input waveguide branches, a sensing area and an output branch. Two light emitting diodes with wavelength of 530 nm and 660 nm were used as light sources. In this work, temperature compensation was done by dual-wavelength technique in which RI and temperature sensitivities were measured at two different wavelengths at 530 nm and 660 nm. Based on the RI and temperature sensitivities, temperature compensation was implemented. Experimental findings indicated that the average relative error of the uncompensated measurement using the light source of 530 nm and 660 nm were 0.4372% and 0.2749%, respectively. Meanwhile, the average error of the temperature compensation method was 0.0344%. Hence, the temperature compensation method provides measurement error up to 92% lower compared to the uncompensated method. As such, the proposed dual-wavelength compensation method could effectively improve the RI measurement accuracy.

Temperature measurement is important in various applications; therefore, various temperature sensors have been developed. Due to its advantages, many optical fiber-based temperature sensors have been proposed. The wavelength modulation-based optical sensor is interesting due to high accuracy. However, the complex fabrication process and high cost limit the advantages of the sensors. Therefore, we proposed a simple and low-cost Mach Zehnder interferometer (MZI) sensor using step-index plastic optical fiber (SI-POF). Performance characterization of the sensor to temperature variation is presented. The sensor consists of two tapers at several distances, forming an interferometer. The first taper was designed to be steep to allow excitation of cladding modes, while the second taper was gradual to suppress power loss. Characterizations were done in terms of sensitivity, hysteresis, and repeatability by analyzing the output spectrums recorded by the spectrometer at various environment temperatures, 35oC to 85oC, with an increment of 10oC. The results showed that the sensor has a sensitivity of 0.0431 nm/oC and a correlation coefficient of 0.9965. Hysteresis of 6.9×10-3 was observed. In terms of repeatability, the sensor shows a maximum deviation, ±3oC, which was mainly resulted from the fluctuation of the oven temperature. Despite its high deviation, the sensor has advantages of simple fabrication, low cost, robust, and low power loss, which make it a good candidate for temperature sensors.

Refractive index is important parameter in various fields, such as environmental, chemical, industrial, and medical. Measurement of refractive index can be done using optical sensor based buried waveguide core offset. This research aims to fabricate and characterize core offset buried waveguide based on Polymethyl Methacrylate (PMMA). Fabrication of buried waveguide was done by creating a cladding of waveguide made from PMMA which has a refractive index of 1.4908 using computer numerical Control machine (CNC). The material used as waveguide core was unsaturated polyester resin (UPR). Characterization was performed to determine the spectrum of input intensity and output intensity. Characterization were done by dipping the waveguide sample in to a container containing glucose solution with concentration of 12%, 14%, 16%, 18%, 20%, and 24%. Waveguide was connected to Polymer Fiber Optic (POF). One of the of POF as an input is connected to light emited diode with wavelength of 470 nm and one of the end other POF as an output was connected to Spectrometer Ocean Optic USB4000. The result showed that the total loss at concentration of 12%-24% is -4.62 dB, -5,70 dB, -6,01 dB, -6,49 dB, -6,15 dB, -6,16 dB, respectively. Sensor works well at a solution concentration of 16%-20% with a sensitivity value of 19.62 dB/RIU and correlation factor of 92.76%.

One of the technologies available to support the assessment process is the e-portfolio. Much research has been done for e-portfolio assessment, and the result can easily find the result in journals. Even though systematic study about e-portfolio as physics learning assessment still rarely done. This research aims to identify the role of e-portfolio as a physics learning assessment in school. A literature study is carried out using four procedures based on PRISMA that are (1) identification, (2) screening, (3) eligibility, and (4) included. Article search has been done through the DOAJ, ERIC, IOP Science, Science Direct, and Springer Link. Based on analysis results, the use of e-portfolio encourages the creation of self-regulation learning. Furthermore, self-regulation learning can help develop a metacognitive skill that students much need for learning physics. Even so, based on 220 articles identified, research about e-portfolio as physics learning assessment has not been found. Therefore, further research is needed to develop and implement an e-portfolio as a physics learning assessment.

Sasis merupakan bagian penting dari sebuah kendaraan, yang membentuk kerangka dari sebuah kendaraan. Sasis harus cukup kaku untuk menahan kejutan, twist, getaran dan tekanan lainnya. Pertimbangan penting dalam desain sasis adalah memiliki kekakuan lentur yang memadai disertai kekuatan untuk karakteristik handling yang lebih baik. Oleh karena itu tegangan maksimum, dan defleksi merupakan kriteria penting untuk desain sasis. Tujuan kajian ini untuk menentukan desain paling optimal dari ketiga desain sasis tipe C, I dan Rectangular Box (Hollow). Mendapatkan ketebalan sasis paling minimum pada sasis bus tipe Rectangular Box (Hollow) dari metode optimasi ASO dan MOGA. Serta membandingkan hasil optimasi yang didapatkan dari kedua metode optimasi tersebut. Pada kajian ini digunakan 2 jenis software yaitu software CAD (SOLIDWORKS 2015) untuk pembuatan model sasis bus dan software Finite Element Analysis (ANSYS Workbench v.16) untuk melakukan simulasi pembebanan static structural dan optimasi. Hasil pada kajian ini menunjukan bahwa tegangan maksimum terjadi pada cross section C besar tegangan 73,235 Mpa, dan defleksi sebesar 1,5455 mm. Hasil analisis pembebanan statik menunjukan bahwa desain tipe Rectangular Box (Hollow) jauh lebih optimal daripada tipe C ataupun I. Berdasarkan optimasi pada sasis bus tipe Rectangular Box (Hollow) dengan dua metode tersebut, hasil terbaik menggunakan metode ASO dengan nilai massa optimum sebesar 682,57 kg (persentase penurunan massa sebesar 1,224 %) dengan equivalent (von-misses) stress sebesar 53,557 MPa dan total deformasi sebesar 1,1847 mm. Sedangkan hasil optimasi metode MOGA, massa hasil optimasi sebesar 686,83 kg dengan equivalent (von-misses) stress 53,517 MPa dan total deformasi sebesar 1,1809 mm. Terjadi penurunan massa sebesar 0,608%.

Penggunaan bahan bakar menjadi kebutuhan sehari-hari rumah tangga terutama untuk memasak. Keterbatasan persediaan bahan bakar gas menyebabkan peralihan ke bahan bakar alternatif seperti penggunaan kompor sekam padi. Ruang pembakaran dirancang untuk mencapai pembakaran sempurna dengan meningkatkan efisiensi dan mengurangi polusi udara dalam ruangan. Pengembangan tambahan yang diperkenalkan dalam penelitian ini, melibatkan penggunaan 6 modul generator termoelectric TEC1-12706 yang dirangkai secara seri untuk membangkitkan energi listrik untuk penerangan dan pengisian daya handphone. Uji eksperimental sederhana dilakukan dengan menvariasikan massa sekam padi 200 gram dan 500 gram. Hasil penelitian ini didapatkan tegangan output maksimum sebesar 6,21 volt dan arus yang masuk ke baterai sebesar 2,40 A yang dapat digunakan untuk penerangan dan pengisian daya handphone sampai 70% dari daya awalnya yang dicapai untuk bahan bakar 500 gram sekam padi. The use of fuel is a daily necessity for the household, especially for cooking. Limited supply of natural gas causes a shift to alternative fuels such as the use of rice husk stoves. The combustion chamber is designed to achieve complete combustion by increasing efficiency and reducing indoor air pollution. Additional development introduced in this study, involves the use of 6 TEC1-12706 thermoelectric generator modules arranged in series to generate electrical energy for lighting and charging mobile phones. A simple experimental test was carried out by varying the mass of rice husk 200 grams and 500 grams. The results of this study obtained a maximum output voltage of 6.21 volts and a current entering the battery of 2.40 A which can be used for lighting and charging mobile phones up to 70% of the initial power achieved for 500 grams of rice husk fuel. Keywords: Thermoelectric Generator, rice husk stove, electric energy generator.

The study of stability and optical properties of the dye-sensitized solar cell (DSSC) based extract of Musa Acuminata bracts have been done.Banana flowers extract was used as photoactive material because it contains anthocyanin. This study focuses on the optimization of semiconductor, natural pigment, and the counter electrode.The ZnO coating used spray coating method. Anthocyanin and polyethylene glycol (PEG) coating were conducted using droplet method.Fabrication of plated copper counter electrode was performed using the electrochemical method. PEDOT:PSS electrolyte is coated on the final process after the two electrodes are coupled by inserting between the two electrodes. The highest efficiency reached 6.24x10-2%.

Investigation of refractive index (RI) and temperature response of unsaturated polyester resin (UPR)/polymethylmethacrylate (PMMA) based waveguides is presented. Three type waveguide structures were fabricated which are straight waveguide (sensor A), curved waveguide (sensor B) and half-filled core waveguide (sensor C). Simple fabrications were done by engraving PMMA sheets using CNC engraving machine to form grooves with cross section of 1 × 1 mm 2 . The grooves were then filled with UPR as core material. To investigate the RI response, the waveguides were immersed in glucose solution with various concentration values having RI of 1.33 to 1.3547. Meanwhile, for temperature response characterization, the sensors were placed in distilled water while heated using magnetic stirrer with temperature variation of 35°C-85°C with increment of 5°C. The results showed that the sensors showed good RI sensitivity and linearity with the highest sensitivity of -48.476 dB/RIU. It was also observed that the sensors were temperature dependent. The highest error due to temperature effect is -1.8 × 10 − 4 RIU/°C.

The purpose of this study is to obtain the optimum buried waveguide structure through modeling for refractive index sensor applications. The waveguide cladding material used as Polymethylmethacrylate (PMMA). The core cross-section size was 1 × 1 mm2. The simulation was carried out at a wavelength of 650 nm using the Finite Element Method (FEM). The parameter of the buried waveguide optimized in this model was the core refractive index and the thickness of the upper cladding to obtain a high propagation constant and good sensitivity to refractive index. Modeling was done for various core refractive index values ​​varied in the range of 1.52 to 1.59, which are the refractive index of various types of polymers. To optimize the sensitivity, the thickness of the upper cladding was varied between 0.125mm to 0.5mm. Besides, a simulation was also carried out for a waveguide without an upper cladding. The results show that the optimum waveguide is a waveguide without upper cladding using polyester as core material with a refractive index value of 1.57 and a sensitivity of 4.9 × 10-10rad /m. RIU.

This paper presents characterization of optical temperature sensor using step-index plastic optical fiber (SI-POF) in intrinsic Mach Zehnder interferometer (MZI) structure. The MZI was developed by forming two tapers at several distance. By exploiting the wavelength dependency of spectrum intensity, measurement was done by using intensity based measurement at two different wavelengths. Characterizations were done to obtain the sensor performance which were sensitivity and hysteresis. The characterization was carried out by launching white LED to the sensor while the sensor was in temperature controlled-oven. The output spectrum was observed at the other sensor tip using spectrometer at various temperature which are 35°C to 85°C with increment of 10°C. It was found that the sensor has sensitivity and hysteresis of 1×10−3/°C and 1.97×10−2, respectively.

Viscosity determination is necessary in variety of applications such as evaluation of environmental pollution, chemical analysis, and as a material quality assessment. Optical fiber-based viscosity sensors are interested since it has various advantages compared to conventional viscosity sensors such as free from electromagnetic interference, compact and could be applied in hazard environment. This study aims to study the performance of back scattering method based viscosity sensor using optical coupler. The sensor design consists of 2×2 plastic optical fiber coupler connected with un-cladded POF as sensor head (sensor A). Characterization was done by connecting 660 nm LED as light source to the one of the coupler branch and an Ocean Optic USB4000 spectrometer to the other branch as light detector. Meanwhile, the sensor head was immersed in glycerin solution. The glycerin solution concentration was varied for various concentration which are 40%, 50%, 60%, 70%, and 80%. Sensor head without the use of optical coupler was fabricated and characterized as comparison (sensor B). The results show that sensor A has a better performance compared to sensor B in terms of linear range. The sensitivity of sensor A is -0.88584 dB/mPa.s at working range of 8.765-57.265 mPa.s with a correlation coefficient of 95.72%.

This paper presented the optimization of bus frame to obtain the optimum weight of bus frame. Failure of the frame can be caused by bending loads and torque experienced by the structure in the conditions of two wheel bumped and one wheel bumped. The optimization process applied is structural size optimization. The method used includes solver deck input and element criteria, input material used, making load collector and load step, running program, convergence test. Then a static linear analysis is performed using the finite element method to see the maximum stress that occurs in the frame, the magnitude of the Von-mises stress value is 1,303 × 103 MPa under static bending conditions and 1,305 × 103 MPa under static torsion conditions. The next step is size optimization which results in a mass reduction of 0.236 tons under static torsion conditions and 0.46 tons under static bending conditions.

This paper presents the development of an object rotator to be applied in digital radiography to modify it as 3D micro-CT. The device was developed using I2C LCD display, tactile buttons and a stepper motor with an L293D motor shield. The first development stage was testing all components. The circuit was designed and then realized using the components that were tested. The device was designed to rotate discretely from rotation angle of 0 – 360° in 256 steps. For performance testing, the device was tested for a rotation angle range of 0° to 90°. The images of each rotation were captured and measured by Inkscape to determine the magnitude of the rotate angle of the object rotating device. The measurement results are compared with theoretical data to determine device error. The highest error was 4.79%. The device was then applied in digital radiography as an object rotator so that the digital radiography functioned as a micro-CT. By using a phantom as an object, the device as an object rotator in micro-CT was tested. The results showed that the device could capture and develop a 3D image of the phantom.

This work presents synthesization and characterization of polyester resin doped with lead acetate (Pb (CH3COO)2) as an alternative material for radiation protection in radiography. Five samples were synthesized with various lead concentration which are 0%, 3.5%, 3.75%, 4% and 4.5%. The samples were characterized using X-ray, He-Ne laser, and FTIR. The results showed that as lead concentration was increased, optical density increased while X-ray transmission decreased. It were found that the attenuation coefficients for each samples were 0.132 cm−1, 0.435 cm−1, 0.543 cm−1, 0.691 cm−1, and 1.156 cm−1. In terms of transmission and attenuation coefficient, lead-polyester composite with lead concentration of 3.5% has an optimum performance.

Films used in Rontgen aperture by conventional radiography process yielding a fluorescent-based digital radiography have been conducted in medical-physics laboratory, Unnes for several applications. The continued research was improving the 2D radiograph imaging to be 3D, i.e. the object was rotated and X-Ray radiated simultaneously that yielded a 2D radiograph data by reconstruction and rendering. These covered a development of simulation object, an algorithmic modeling of scanning simulation and FDK (Feldkamp, Davis, Kress), and finally utilizing the algorithms resulting in 3D radiograph. In the future, this cheap technology would be a benefit in dentistry, because this technology is not popular nowadays, an implication of the expensive cost. The development process covered; software developing stage of CBCT (cone beam computed tomography) system in Phantom, data analysis, and finally reaching the result: CBCT model in laboratory scale. Prototype development of CBCT system can be done through study of the system in laboratory scale and then integrating the CBCT system for validated system in laboratory scale. According to the background above, we need innovation in CBCT system supporting the development of CBCT system aperture that leads to ease the dental implant installation in dentistry. At this level, CBCT prototype was used in early validation of the concept of CBCT technology in limit quantity and laboratory scale.

This study presents the fabrication and characterization of polymethylmethacrylate (PMMA)-based buried waveguide for operation in the visible light range. The fabrication was done by engraving PMMA sheet using a computer numerical control (CNC) machine to be filled with a waveguide core material and then covered with PMMA sheet. The material used for waveguide core were Unsaturated Polyester Resin (UPR) with the brand of Yukalac C108B and Eternal 2441IP. Characterization was done to determine the output power loss by passing light from an LED with wavelength of 660 nm into the waveguide. The output spectrum was observed using a spectrometer. The results showed that power loss for waveguide with Yukalac C108B and Eternal are -7.89 dB and -13.85 dB, respectively.

This work presents simulation of light propagation inside tapered structure-plastic optical fibre (POF) subjected to various surrounding temperatures and refractive index (RI). The tapered structure served as Mach-Zehnder interferometer (MZI) which split light into core modes and clad modes that recombined at the end of the taper. Simulation was done by using Beam Propagation Method (BPM) solved using Finite Difference Method (FDM). The light launched in to the MZI was varied from 611nm to 655nm. In order to give temperature effect, the temperature was varied from 30°C to 80°C with increment of 10°C. The results showed that the free spectral range (FSR) of the MZI are shifted as temperature increased. The sensitivity for the peak and dip of the FSR are -0.0158 nm/°C and -0.0153 nm/°C, respectively. For RI sensitivity investigation, the surrounding RI was varied from 1.333 to 1.349. The sensitivity of peak FSR and dip FSR to RI change are -98.638 nm/RIU and 105.4 nm/RIU. Therefore, the MZI can be used to measure RI and temperature simultaneously.

Microtremor is harmonic vibration of land that occurs continuosly at a low frequency. In this paper presents the analysis of shear wave velocity profile to interpret site classification at Universitas Negeri Semarang. The data acquisition was done at 20 points by using microtremor single station method. The data was processed using Horizontal to Vertical Spectral Ratio (HVSR) method to obtain the HVSR curve and then inverted using ellipticity curve method to get 1D shear wave velocity profile. The value of shear wave velocity profile used to interpret subsurface layers to classification of the site. The result shows the range value of shear wave velocity profile is 160 m/s until 2900 m/s. The AIP Proceedings article template has many predefined paragraph styles for you to use/apply as you write your paper. This value show that site classification in research area consists of soft soil until hard rock.Microtremor is harmonic vibration of land that occurs continuosly at a low frequency. In this paper presents the analysis of shear wave velocity profile to interpret site classification at Universitas Negeri Semarang. The data acquisition was done at 20 points by using microtremor single station method. The data was processed using Horizontal to Vertical Spectral Ratio (HVSR) method to obtain the HVSR curve and then inverted using ellipticity curve method to get 1D shear wave velocity profile. The value of shear wave velocity profile used to interpret subsurface layers to classification of the site. The result shows the range value of shear wave velocity profile is 160 m/s until 2900 m/s. The AIP Proceedings article template has many predefined paragraph styles for you to use/apply as you write your paper. This value show that site classification in research area consists of soft soil until hard rock.

Torsional stiffness is important parameter of chassis that affect the handling performance of chassis. Torsional stiffness can be determined using Finite Element Method (FEM) in early stage design of its. In order to validate the FEM result, experimental work needs to be done. The fixture has been design in simpler stucture, flexible for any kind of chassis and using a simple measurement’s equipment such as dial indicator and load cell. Twist fixture has been designed for measuring of torsional stiffness of TATA cab chassis indirectly. The fixture measured the deflection caused by torsion subjected to the chassis. The torsional stiffness was calculated based on measured displacement of chassis. The result of comparison shows that the experimental results in agreement with the simulation results. Therefore, the simulation results of TATA cab chassis model are valid.

This work presents optimization of the dimension of ridge waveguide structure to be used as temperature sensor. The objective of the work is to obtain an optimum dimension of ridge waveguide so that it provides high sensitivity to temperature. Ridge waveguide structure was chosen since it has strong light confinement and low bending loss. The optimization was done by simulating the temperature distribution and electric field distribution inside the waveguide using Finite Difference Method (FDM). The simulations were done for various waveguide width and waveguide thickness. The results showed that as the width increased, the sensitivity decreased. The optimum ranges of waveguide dimensions are between 10μm to 20μm and 15μm to 25μm for width and thickness, respectively.

Papua is one of part in Indonesia which is the geology research of that place isn’t developed and limited. It causes the seismotectonic of Papua hasn’t been known. WinITDB was used to determine the dip angle plate which was on the north part of Papua. The determination of angle was done through seismicity’s cross section analysis in the area. To show that seismicity, earthquake history data that ever occurred in the area is needed. The result on the seismicity’s cross section of plane A–A’, was confluence by two plates with angle 150° against horizontal on the depth up to ±68 km. On the seismicity’s cross section of plane B–B’ had angle 135° against horizontal on the ±82 km depth. On the plane C–C’ seismicity’s cross section, was confluence of two plate which located between -1,77°S until -4,97°S subducted until 171 km depth on 1,38°N - 4,97°S. It proved that subduction characteristic in the northern Papua which was Australia continent plate subducted to north, followed by collision and the Pacific plate subduction on New Guinea. It is also confirmed by focus mechanism analysis which showed the earthquake activities are controlled by the not really deep active fault.

Air compressor tank is the important equipment in the automotive workshops and laboratories. Air compressor can be categorized as pressure vessel. Pressure vessel often has a combination of high pressure together with high temperature, in some cases of flammable fluids or highly radioactive material. Due to hazards, it is crucial to ensure there is no leakage on the products. In addition, vessel has to be design cautiously to cope with the operating temperature and pressure. The thickness of the PMAC should be optimized to get the best performance, the thickness cannot be very large due to the cost of material and exceeded weight and also cannot be very thin due to the failures caused by its internal pressure. In order to get the optimum thickness, finite element method software was used to simulate the stress analysis of PMAC with various thickness and various shapes.

The presence of mercury ions is a serious threat to human health and environment. Water consumption containing mercury is very dangerous for human healt. The purpose of this work is to design a heavy metal sensor ion using plastic optical fiber to detect mercury ions in water. The sensor was fabricated by coating the optical fiber by chitosan through dip-coating technique. There are three diameter of optical fiber sensor that was fabricated, which are 1087.64 μm (sensor A), 1691.64 μm (sensor B) and 1736.33 μm (sensor C). Sensor characterization was done by connected the tip of plastic optical fiber to an LED and the other tip was connected to a photodioda. The results show that sensitivity of sample A is 0.32 mA/ppm, sample B is 0.56 mA/ppm and sample C is 0.64 mA/ppm. In terms of respone time, it is shown that thr respon time for sensor A, B and C are 22 s, 42.5 s and 86 s respectively.

Mach Zehnder interferometer (MZI) based on plastic optical fiber (POF) is interesting due to its robustness and simple fabrication. In this work, MZI-POF was designed and its sensitivity to temperature change was characterized to investigate its performance for sensor application. The MZI-POF was fabricated by forming two tapers at several distance by simple heat-pull method. The spectra was investigated by launching white light emitting diode (LED) and the output were observed using VIS-NIR spectrometer. It is shown that the wavelength of spectrum peak and spectrum dip were shifted compared to that of un-tapered POF which indicates that the structure serves well as MZI. Sensor sensitivity to temperature was determined by measuring the spectrum for various temperature which was varied from 40°C to 80°C with increment of 5°C. The result showed that the sensor sensitivity is 0.0693nm/°C in terms of peak measurement and 0.0487nm/°C for dip measurement. Therefore, MZI-POF is a potential candidate for temperature sensor.

This work presents the quality analysis of the digital image of pet to obtain optimum exposure factors for pet radiography diagnosis using conventional-modified digital radiography. The digital radiography that used was conventional radiography which was modified by using the digital camera, intensifying screen and image processing software so that it works as digital radiography. The object, a bone-broken cat, was exposed to X-ray radiation from the digital radiography with various exposure factors which are voltage, current and exposure time. The image quality analysis was done by performing Contrast-to-Noise Ratio (CNR) analysis and histogram analysis using image processing toolbox provided by MATLAB. The results show that exposure factors of the voltage of 60 kV, the current of 16 mA and exposure time of 0.20 s provided CNR highest value which is 57.249. Histogram analysis shows that the image with the above-mentioned exposure factors has almost uniform grey intensity distribution

A new sensor for simultaneous measurement of humidity and temperature is proposed. The sensor consists of Fabry–Perot cavity formed by two identical uniform fiber Bragg gratings. To make the cavity serves as humidity sensor, moisture sensitive polymer, which is polyimide, is coated on the FBG and on the cavity with different thickness. When the sensor is exposed to the relative humidity change, the polyimide will expand and stretch the fiber and induces strain on the FBG and on the cavity. The induced strain alters the grating period, cavity length and effective refractive index of fiber. The simulation results show that the humidity sensitivity and thermal sensitivity are 1.92 pm/%RH and 8.87 pm/°C, respectively, for polyimide coating thickness of 10 μm on the FBG and 15 μm on the cavity.

The main issues that were examined in this study is the modulus of elasticity bamboo betung with variable length. The purpose of this study was to measure the modulus of elasticity on bamboo betung with variable. Modulus of elasticity in bamboo shows the flexibility for using in a various fields. In this study the bamboo is made into small girders with a uniform thickness and width are respectively 0.8cm and 1.5cm. The length of the bamboo that is used in this study are the 50cm, 60cm, 70cm, 80cm, 90 cm, 100cm. To determine the elasticity of the bamboo it is provided with a load in the middle position. From the research results obtained showing the longer bamboo the greater flexibility gained linearly elastic modulus is 1.0122E+10N/m2. Keywords: bamboo, girder, modulus of elasticity.