Spektra: Jurnal Fisika dan Aplikasinya
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BIOSENSOR SYSTEM DESIGN FOR DISSOLVED OXYGEN MEASUREMENT USING CURRENT MIRROR CIRCUIT
Get PDFA biosensor system using a current mirror circuit has been designed and characterized. Biosensor system usually implements an amperometric circuit such as a trans-impedance topology to measure current flowing in the solution due to the contained dissolved oxygen. The trans-impedance circuit implemented for the biosensor has some drawbacks and disadvantages. The implementation of this circuit exhibits rather high noise, besides the impracticality of the power supply used due to bipolar voltage need to allow negative voltage output. In this paper, a classical current mirror circuit is used to convert the flowing current in the solution. The use of the classical current mirror circuit is aimed to obtain lower noise level, besides the easiness in providing the power supply for the system, since the circuit consists only of small number of active components and does not need a bipolar power supply. The measurement is performed utilizing an algae species as a bio-receptor for the measured dissolved oxygen. By utilizing this circuit, the biosensor measurement system can be optimized with better precision and noise performance. Consequently, the dissolved oxygen measurements can be improved and achieve good results. Besides, the system can detect the changes in dissolved oxygen due to the photosynthetic process of the algae
THE APPLICATION OF SHIFT METHOD USING MOVING LASER ON CANCER CASES IN HEAD AREA USING 3DCRT AND VMAT TECHNOLOGY
Get PDFThe accuracy of patient position is essential to achieve the purpose of radiotherapy. Therefore, before radiotherapy, the isocenter of the patient must be determined to find out the target location. Verification serves to determine the isocenter that shifts from the reference point on the CT simulator. This research was conducted using field observation method, comparing the results of the isocenter after verification with the isocenter on the moving laser. Eight (8) samples from primary data were taken. Shift data was obtained from the average value and standard deviation. The instrument used was a linear accelerator of clinic iX type and On-Board Imager. The results obtained were the average lateral coordinate point of 0.055 cm; at the longitudinal isocenter point of 0.10 cm; and at the vertical isocenter point of 0.053 cm. From this research, it was concluded that the average value o the isocenter shift was less than 0.3 cm. This method can be used because the shift does not exceed the tolerance limit
UTILIZATION OF COAL BOTTOM ASH AS BRIQUETTE MATERIAL
Get PDFResearch has been carried out on the use of coal bottom ash as a material for making briquettes as an alternative fuel. Carbonized of rubber seed shells and Halaban wood were used as mixtures and tapioca flour as adhesives. The composition used in making Halaban wood charcoal and coal bottom ash briquettes is 100% : 0%, 90% : 10%, 80% : 20%, and 70% : 30%. Tapioca flour used was as much as 5%, the pressure of 150 kg/cm2 and the size of 250 meshes. While for rubber seed shell and coal bottom ash briquettes, the composition used was with ratio 60% : 40% and 70% : 30%, the pressure used was 100, 150, and 200 kg/cm2 and the size of 50 meshes. Tapioca flour used was as much as 5%. The results of the characterization of rubber seed shell and coal bottom ash briquettes were water content (4.35 - 10.65)%, ash content (12.53 - 17.26)%, and calorific value (3597.59 - 4549.88) cal/g. While the characterization results of Halaban wood charcoal and coal bottom ash briquettes were water content (2.947 – 4.097)%, ash content (0.383 – 26.667)%, and calorific value (4749-6621) cal/g. The results showed that if coal bottom ash in the composition were higher, it would increase the water content and ash content of the briquettes, while the calorific value would be lower. The recommended composition of coal bottom ash was about 10-20 %. While if the briquettes pressure was higher, the water content, ash content and calorific value would be smaller. The recommended pressure was 150 kg /cm2
ANALYSIS THE EFFECT OF PRIMARY COIL LENGTH OF TRANSFORMATOR TO THE RESULTED ELECTROMOTIF FORCE
Get PDFTransformator is an electrical device that uses a principle of solenoid wrapped in kern, and there are usually two or more coils. Each coil of the taranformator is electromagnetically connected. The transformator is made to fulfill the specific level of voltage required in the devices or systems that use alternating current electrical energy. For example, transformator tap change is design to have different number of primary turns to produce a fixed output voltage, in term there is a changing in the input voltage. This research tries to analyze the effect of the length of primary coil difference of transformator to the voltage resulted in the secondary coil. The objective of the study is producing a relationship of primary coil length variation to the resulting voltage. Variation of coil length is made from 1 cm to 15 cm with interval of 1 cm coil length. The length of the secondary coil is also varied imto 3 cm, 6 cm, and 9 cm. The test is performed by providing the same input voltage at each variation of the primary coil length and then measure the output voltage. The results show that the longer primary coil will produce the smaller output voltage in the secondary coil of tranformator. Based on the resulted graph, the relationship of the length variant of primary coil is linear to the voltage measured in the secondary coil.with determination coefficient (R2) of
0.9603, 0.9775, and 0.9822 respectively forlength of 3 cm, 6 cm, and 9 cm of the secondary coil
OPTIMIZATION OF THE USE OF FLY ASH AS AN ADDITIVE PORTLAND COMPOSITE CEMENT (PCC)
Get PDFResearch has been carried out on the optimization of the use of Lahat Fly Ash as an Additive Portland Composite Cement (PCC) which aims to determine the optimum conditions for adding Lahat fly ash to produce cement with physical and chemical requirements in accordance with SNI 7064:2014 and discover the ideal composition of cement with fly additions Lahat ash from various cement compositions. The quality analysis in making PCC cement is chemically in the form of Insoluble Residue (IR), Loss of Ignition (LOI), and free lime (FCaO) as well as the quality of physics in the form of Blaine, setting time, and cement mortar compressive strength. The results obtained after the process of making PCC cement with the addition of 14% Lahat fly ash, namely PCC cement in optimum conditions with physical and chemical requirements in accordance with SNI 7064: 2014 where the ideal composition of PCC cement manufacture is 14% Lahat fly ash, clinker 62%, 3% gypsum, 18% limestone, and 3% pozzolans in making PCC cement. Therefore, Lahat fly ash can be used as an alternative mixture in making PCC cement
ANALYSIS OF STRUCTURE AND ANTIMICROBIAL ACTIVITY OF CeO2 AND Nd2O3 NANOPARTICLES
Get PDFCerium oxide (CeO2) and Neodymium oxide (Nd2O3) nanoparticles using local content have been synthesized by precipitation method. The CeO2 and Nd2O3 nanoparticles were characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) to analyze the material phase and structure. The XRD spectrum shows that CeO2 and Nd2O3 nanoparticles have face-centered cubic and hexagonal, and cubic, respectively. The anti-microbial activity of CeO2 and Nd2O3 nanoparticles was analyzed by diffusion method using gram-negative bacteria (E. coli, S. aureus, P. aeruginosa), and gram-positive bacteria (S. entericatyphi, L. monocyogenes), and fungus (C. albicans). The result confirms that CeO2 and Nd2O3 nanoparticles have the capability of microbial pathogen inhibition. The CeO2 nanoparticles have the effective activities of inhibition for the microbial of S. aureus and S. entericatyphi, whereas Nd2O3 nanoparticles can inhibit the microbial of P. aeruginosa, S. entericatyphi, and L. monocyogenes
THE SPRING VARIATION IN TWO DIMENSIONAL MODELING OF RED BLOOD CELL DEFORMABILITY BASED ON GRANULAR
Get PDFThe red blood cell membrane has a complex structure and high deformability. Simulation of that complex red blood cell membrane can simpler use granular-based modeling. Red blood cell is modeled consisting of 50 granular particles connected by springs. An i-particle is connected with two of its first nearest particles which are i+1-particle and i-1-particle and with two of its second nearest particles which are i+2-particle and i-2-particle. Each particle has a spring force and forces from internal hydrostatic pressure. Spring force is a product of the spring constant and change of spring length of two particles. Meanwhile, forces of internal hydrostatic pressure is a product of particle diameter and the difference in the outside and inside pressure of red blood cell membrane. In this research, there is variation in spring length and spring constant that can model deformability of three shapes of red blood cell; those are biconcave, ellipse, and circle. This variation in spring length and spring constant for every cell shape in this modeling can also use for other initial cell shapes, which shows that initial cell shapes deform into shape according to variation used
GREENESS ANALYSIS OF FOREST IN MINING AREA OF SAWAHLUNTO USING NDVI METHOD BASED ON LANDSAT IMAGERIES IN 2006-2016
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Pembukaan lahan hutan yang dijadikan lokasi pertambangan merupakan salah satu kegiatan yang dapat merubah jenis tutupan lahan atau sering disebut dengan konversi lahan. Salah satu daerah yang telah mengalami konversi lahan tersebut adalah Sawahlunto. Konversi lahan yang tidak menggunakan prinsip kelestarian lingkungan dapat mengakibatkan banyak hal negatif misalnya degradasi atau penurunan kualitas hutan. Tujuan dari penelitian ini adalah melakukan analisis tingkat degradasi hutan daerah pertambangan Sawahlunto tahun 2006 sampai 2016. Penelitian ini menggunakan teknologi penginderaan jauh berbasis citra satelit landsat. Citra satelit landsat ini diklasifikasikan dengan metode Normalized Difference Vegetation Index (NDVI) berdasarkan kerapatan vegetasi. Kemudian hasil klasifikasi ini dibuat dalam bentuk pemetaan. Klasifikasi pertama dikategorikan menjadi dua yakni hutan dan non hutan. Hasil yang didapatkan dari penelitian ini menunjukkan bahwa terjadi perubahan tutupan lahan yang semula hutan menjadi non hutan meningkat sebesar 7,5% selama kurun waktu sepuluh tahun. Klasifikasi selanjutnya yakni berdasarkan enam kategori yakni vegetasi sangat rapat, rapat, cukup rapat, non vegetasi 1, 2 dan 3. Dari klasifikasi ini, juga terlihat perubahan nilai NDVI maksimum maupun minimumnya. Tahun 2006 memiliki kisaran nilai NDVI maksimum 0,71 dan tahun 2016 memiliki kisaran nilai NDVI maksimum 0,56. Hal ini mengidentifikasi bahwa tingkat kehijauan yang ada di daerah pertambangan Sawahlunto menurun.
Kata Kunci : degradasi, hutan, landsat, ndvi, klasifikasi, Sawahlunto.
Abstract
The clearing of forest land that is used as a mining site is one of the activities that can change the type of land cover or often called land conversion. One of the forest areas that convert the land is Sawahlunto. Conversion of land that does not use the principles of environmental sustainability can lead to many negative things one of which is the degradation. The purpose of this research is to analyze the level of forest degradation of Sawahlunto mining area in 2006 until 2016. This research uses a remote sen sing technology based on landsat satellite imagery. This landsat satellite image is classified by Normalized Difference Vegetation Index (NDVI) method based on vegetation density. Then the results of this classification is made in the form of mapping. The first classification is categorized into two namely forest and non forest. The results obtained from this study indicate that a change in land cover from forest to non-forest increased by 7.5% over a period of ten years. The next classification is based on six categories namely very dense vegetation, dense vegetation, fairly dense, non vegetation 1, 2 and 3. From this classification, also seen the change in NDVI maximum and minimum value. The year 2006 has a maximum NDVI value range of 0.71 and 2016 has a maximum NDVI value range of 0.56. This identifies that the existing greenness in the mining area of Sawahlunto is decreasing.
Keyword : degradation, forest, landsat, ndvi, classification, Sawahlunto
KARAKTERISASI KELISTRIKAN AIR PAYAU DAN AIR SUNGAI SEBAGAI BAHAN ELEKTROLIT
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Air payau dan air sungai memiliki potensi sebagai sumber energi alternatif terbaharui. Studi kelistrikan mereka berhasil dilakukan menggunakan prinsip elektrokimia sel volta, yaitu dengan membuat pasangan elektroda disusun secara seri dalam 20 kotak persegi panjang. Elektroda yang dipakai adalah tembaga (Cu), dan seng (Zn), sedangkan sebagai elektrolit adalah larutan air payau dan air sungai. Karakteristik bahan elektrolit diketahui melalui pengukuran tegangan dan arus yang mengalir pada LED (1,2 watt) yang diletakkan pada rangkaian sel elektroda. Pengambilan data pengukuran dilakukan selama 3 hari dengan selang 2 jam. Hasil pengukuran dan analisis untuk kombinasi elektroda Cu-Zn, menunjukkan air payau memiliki daya kelistrikan lebih besar daripada air sungai, dengan rasio 12,008 : 5,84 (hari pertama) dan 1,752 : 0,572 (hari ketiga). Nilai ini juga menunjukkan bahwa air payau sebagai larutan elektrolit mampu menghasilkan energi untuk menghidupkan LED selama 72 jam dengan nilai rata-rata intensitas LED yaitu 322,8 lux.
Kata-kata kunci: elektrolit, air payau, sel elektroda, intensitas LED
Abstract
Brackish water and river water have the potential as an alternative renewable energy source. Their electrical studies have been successfully conducted using the electrochemical principle of voltaic cells, by making electrode pairs arranged in series in 20 rectangular squares. Electrodes used are copper (Cu), and zinc (Zn), while as an electrolyte is some brackish water and river water. The characteristic of the electrolyte material is known by measuring the voltage and current flowing on the LED (1.2 watt) placed on the electrode cell circuit. Taking measurement data is done for three days with 2 hour interval. The results of measurement and analysis for Cu-Zn electrode combinations have shown that brackish water has greater electrical power than river water, with a ratio of 12.008: 5.84 (day one) and 1.752: 0.572 (third day). This value also shows that brackish water as electrolyte solution has been able to produce energy to turn on the LED for 72 hours with an average value of LED intensity of 322.8 lux.
Keywords: electrolyte, brackish water, electrode cell, LED intensit