| Nama Pengarang | : | Yosaphat Sumardi |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 85-90 |
| Abstraksi Narasi | : | Exponential decline curve analysis is used to predict the life of production well. This analysis is applied to the Kamojang geothermal area. The mathematical equation of decline relates the production rate of well to times. This equation can be manipulated to calculate the life and the reserve of well. The codes of computer program are written in Visual Basic 6.0 programming language. The decline of production rate can be presented graphically. The life and the reserve of well are unique for each well. The life can be lengthen by increasing the number of re-injection well distributed evenly throughout the Kamojang geothermal area and substitute several production wells with monitoring wells. |
| Nama Pengarang | : | PK Purwadi |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 41-48 |
| Abstraksi Narasi | : | This study examined the temperature distribution in all positions of 1 dimensional solid with characteristics which were close to the real ones of the solid. The conductivity value of the solid (k) was a function of temperature, i.e.k = k(T). The specific gravity (...) and the specific heat (c) were assumed constant during unsteady states. The temperature distribution can be obtained by solving the equation of 1 dimensional heat diffusion with k = k(T). A selected boundary condition, serve as a sample, was two wall surfaces of the 1 dimensional solid which were in contact with the flowing fluid enabling heat convection between the wall surfaces and the fluid. The initial temperature of the solid was equally distributed. The solution was carried out by using the explicit-numeric-computational finite-difference method. The selected solid was copper. |
| Nama Pengarang | : | Darmawan Utomo |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 61-66 |
| Abstraksi Narasi | : | Illuminance meter is needed in many areas such as room designers and industries that manufacture and process lightings. Their goal is how to make human eyes feel comfort on any place and at any time. This illuminance meter is implemented using photodiode sensor SL-69EBG1 on photovoltaic mode. The current is pulled whenever photodiode is obtaining illuminance, and then this current is amplified, changed to a voltage, and converted to digital-form. This result is processed again using programmable system on chip in order to display the result on LC 16 x 2 and sent via serial communication standard RS-232 to computer as well. On the other side, the computer can save and show the result on its monitor. The experiments show that show that the illuminance meter provides error lower than 3% compared to TES-1330. In adition to the result, this meter is also able to display characters, to save the results in computer, and to give the results in foot-candle unit. |
| Nama Pengarang | : | Y.G. Hartono |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 195 |
| Abstraksi Narasi | : | Deskripsi abstrak ringkas tidak tersedia untuk artikel ini. |
| Nama Pengarang | : | Asan Damanik |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 109-115 |
| Abstraksi Narasi | : | We evaluate the neutrino magnetic moment contributions to the differential cross-section of the neutrino-electron scattering in the sceme of GWS model of particle Physics. The neutrino magnetic moment effects are different kind of involve neutrino flavor in the scattering. The neutrino magnetic moment effect for a e v scattering is very small compared to the neutral-current contribution. For a vµ e scattering, the neutrino magnetic moment effects on the differential cross-section are of the order as the neutral-current interaction contributions. For avt e scattering, the neutrino magnetic moment contributions to the differential cross-section are very large and dominate the neutral-current interaction contributions. |
| Nama Pengarang | : | TJ Doddy Purwadianto, Jamasri |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 161-171 |
| Abstraksi Narasi | : | The purpose of this study is to investigate the effect of multi overload to the fatigue crack growth behavior of AI 2024-T3. The pre-test of crack growth was performed under the constant amplitude and the periodic single overload, which was used as a comparison test of the result from the multi overload. The test was performed under the constant amplitude with stress level of 20%, stress ratio (R) of 0.1 and 0.3 and frequency of 11 Hz. The test, which involved overload was done with Overload Ratio (OLR) of 1.6 and Occurrence Ratio (OCR) of 1/50000. The method used to analyze the crack growth data ( da/dN vs AK curve ) was a polynomial incremental method. The fatigue crack growth behavior can be determined from N vs a or da/dN vs AK Curve. The experimantal results show that the fatigue crack growth, with or without overload on the same material, has the same behavior after the effect of overload disappears. The placement of overload in the plastic zone with a longer distance than radius of the plastic zone on the multi overload test increases the fatigue lifespan. |
| Nama Pengarang | : | Yosaphat Sumardi |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 93-107 |
| Abstraksi Narasi | : | The explicit finite difference method is use to simulate numerically the hydraulic head distribution of groundwater flow. The groundwater system here is assumed as a single confined isotropic aquiter. The governing equations of groundwater system are based on continuity equation and Darcy's law. The codes of computer program are written in Visual Basic 6.0 programming language. The hydraulic head distribution of groundwater system can be presented graphically. It depends on the number of discharge wells and the location of wells. Yhe minimum of hydraulic head becomes lower if the number of discharge wells is increased. If the grid size of modelled area is made smaller, the distributed propertities of groundwater system can be presented more accurately, the hydraulic head distribution included. |
| Nama Pengarang | : | M.Andy Rudhito |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 131-139 |
| Abstraksi Narasi | : | This article disusses the algebraic structure used in the dynamical systems with maximum ( ) and operation as its basic operations. We will show that max-plus algebra Rmax ( ), where is the set of all real numbers, is an idempotent semifield, is an idempotent semiring, ( ) is a semimodul over (Rmax), and order relation in ( ) is a partial order relation. |
| Nama Pengarang | : | Frans Susilo |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 145-151 |
| Abstraksi Narasi | : | This paper investigates a method of ranking fuzzy numbers by using the integral value defuzzification as developed by Liou and Wang (1992). This ranking method has been generalized by Chang and Lee (1994) using the concept of Overall Existence Ranking Index (OERI) |
| Nama Pengarang | : | Dwi Nugraheni Rositawati |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 117-122 |
| Abstraksi Narasi | : | Polymerization of polyaniline (PANI) was done using the electrochemical method (0,4 A for 1 hour) with aniline as monomer, HCIO4 and H2SO4 as doping solution and methanol as solvent. The result of the syntesis was black powder which adheres to the anode. After being neutralized and dried, the PANI powder was disolved in NMP with weight ratio of 1:5. The solution was stirred using magnetic stirrer for 6 hours until being homogenous. The solution was processed into a thin film using casting method on PCB, and then was dried with sislica gel and its thickness was measured by the V-I method, both with and without the annealing process for 5 hours and 10 hours at 100°C. The result of the experiment shows that the concentration of doping increases while the concentration of annealing decreases the electrical conductivity of PANI. |
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