Journal of Mathematical and Fundamental Sciences
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The Synthesis of Imidazoline Derivative Compounds as Corrosion Inhibitor towards Carbon Steel in 1% NaCl Solution
Get PDFOleic imidazoline is one of the nitrogen containing heterocyclic compounds that has been widely used as commercial corrosion inhibitor, especially in minimizing the carbon dioxide induced corrosion process in oilfield mining. In this present work, some imidazoline derivative compounds have been synthesized utilizing both conventional and microwave assisted organic synthesis (MAOS) methods, in order to determine their corrosion inhibition properties on carbon steel surface. The MAOS method is more effective in synthesizing these compounds than the conventional method regarding to the higher chemical yields of products (91% to 94%) and the shorter reaction times (7 to 10 minutes). The characterization of corrosion inhibition activities of the synthesized products towards carbon steel in 1% NaCl solution was determined by the Tafel plot method. The corrosion inhibition activities of compound 1b ((Z)-2-(2-(heptadec-8-enyl)-4,5-dihydroimidazol-1-yl)ethanamine), 2b ((Z)-2-(2-(heptadec-8-enyl)-4,5-dihydroimidazol-1-yl)ethanol) and 3b (2-(2-heptadecyl-4,5-dihydroimidazol-1-yl)ethanamine) at 8 ppm concentration in 1% NaCl solution are, respectively, 32.18%, 39.59% and 12.73%. The heptadec-8-enyl and hydroxyethyl substituents at C(2) and N(1) position of imidazoline ring, respectively, gave the most effective corrosion inhibition activity towards carbon steel compared to the presence of other substituents. The increase in concentrations of compound 1b, 2b and 3b in 1% NaCl solution tends to improve their corrosion inhibition activities. Based on the analysis of the free Gibbs adsorption energy (ÄG0ads) values of compound 1b, 2b and 3b (-32.97, -34.34 and -31.27 kJ/mol, respectively), these compounds have the potential to interact with carbon steel through semi-physiosorption or semi-chemisorption
Nanolithography on the Electron Beam Resist using the Scanning Probe Microscope Cantilever
Get PDFThis research demonstrates the feasibility of fabricating nanoscale resist patterns on a silicon (Si) substrate using a scanning probe microscope (SPM). In order to utilize scanning probe nanolithography (SPNL) with the other micro-machining techniques such as dry etching, plating and lift-off process, nanoscale resist patterns should be created on an Si substrate with high accuracy in SPNL. We have, so far, established the negative type of SPNL using the negative-tone electron beam (EB) resist named SAL601. The primary objective of this research is to find out appropriate process conditions for establishing the positive type of SPNL using the positive EB resist "³ZEP520A"³. This paper describes the variations of experimentally created nano-patterns depending on the process conditions, and determines the appropriate process conditions from the variations obtained. In addition, we analyzed the electric field in the EB resist by a finite element method (FEM), for estimating the line width of the nano-pattern created by SPNL
Historical Fire Detection of Tropical Forest from NDVI Time-series Data: Case Study on Jambi, Indonesia
Get PDFIn addition to forest encroachment, forest fire is a serious problem in Indonesia. Attempts at managing its widespread and frequent occurrence has led to intensive use of remote sensing data. Coarse resolution images have been employed to derive hot spots as an indicator of forest fire. However, most efforts to verify the hot spot data and to verify fire accidents have been restricted to the use of medium or high resolution data. At present, it is difficult to verify solely upon those data due to severe cloud cover and low revisit time. In this paper, we present a method to validate forest fire using NDVI time series data. With the freely available NDVI data from SPOT VEGETATION, we successfully detected changes in time series data which were associated with fire accidents
Ab Initio Calculation of UV-Vis Absorption Spectra of a Single Chlorophyll a Molecule: Comparison Study between RHF/CIS, TDDFT, and Semi-Empirical Methods
Get PDFChlorophyll a is the most abundant pigment on Earth responsible for trapping light energy to perform photosynthesis in green plants. This molecule has been studied for many years from different points of interest with both experimental and theoretical methods. In this study, the Restricted Hartree-Fock/Configuration Interaction Single (RHF/CIS), Time-Dependent Density Functional Theory (TDDFT), and several semi-empirical methods (CNDO/S and ZINDO) calculations were carried out to reconstruct the UV-Vis absorption spectra of chlorophyll a. To some extent, the calculation results based on the single-molecule approach succeeded to reconstruct the absorption spectra, but they required to be rescaled to fit the experimental results. In general, the semiempirical methods provide a better energy scaling factor. However, they lack vertical transition fine features with respect to the spectrum obtained experimentally. In this case, the ab initio calculations provided more complete features, especially the TDDFT with high-level basis sets, which also has a good accuracy with regards to the transition energies. The contribution of the ground state and excited state orbitals in the main vertical transitions is discussed based on the delocalized nature of the wave functions and the presence of solvents using the polarizable continuum model (PCM)
Studi Optimasi Parameter Daya RF untuk Penumbuhan Lapisan Tipis Mikrokristal Silikon dengan Metode Hot Wire Cell PECVD
Get PDFThe Hot Wire Cell PECVD method has been developed and successfully applied to grow the hydrogenated amorphous silicon (a-Si:H) thin films with a relatively high conductivity. The a-Si:H thin films were grown on the 7059 corning glass at a filament temperature of 800 oC. Ten percents silane (SiH4) gas diluted in hydrogen (H2) gas was used as gas source. In the hot wire cell PECVD method, reactant gases are decomposed as a result of reaction with a heated filament. The filament was placed parallelly with inlet gas system and outside of electrodes. The characterization results exhibited that the deposition rate increased from 1.02 Å/s to 1.90 Å/s with increasing the rf power from 80 watt to 120 watt. The optical bandgap decreased from 1.65 eV to 1.56 eV with increasing the rf power from 80 watt to 120 watt. The SEM image and the XRD spectrum exhibited the transition of amorphous to microcrystalline silicon at an rf power of 120 watt. The transition of amorphous to microcrystalline was indicated by the reduction of amorphous parts and the appearance of peak diffraction at <111> preferential crystal orientation. The dark and photo conductivities of the obtained μc-Si:H thin films was 6.84x10-6 S cm-1 and 4.16x10-4 S cm-1, respectively
Datum Geodetik Batas Maritim Indonesia â Singapura: Status dan Permasalahannya
Get PDFMaritime boundary between Indonesia and Singapore in the strait of Singapore has been defined by the territorial sea boundary treaty of 1973.In this treaty, geodetic datum of the geographic coordinates of six boundary points between Indonesia and Singapore are not explicitly stated. This paper investigates the possible datum for these coordinates, namely KERTAU48, KERTAU68, GENUK and SOUTH ASIA, and its impacts on the coordinates and location of boundary points. Related aspects are also discussed. Paper is sum up with some conclusions and recommendations
Transmission Coefficient of an Electron through a Heterostructure with Nanometer-Thick Trapezoidal Barrier Grown on an Anisotropic Material
Get PDFTransmission coefficient of an electron incident on a heterostructure potential with nanometer-thick trapezoidal barrier grown on anisotropic materials are derived by solving the effective-mass equation including off-diagonal effective-mass tensor elements. The boundary condition for an electron wave function (under the effective-mass approximation) at a heterostructure anisotropic junction is suggested and included in the calculation. The analytic expressions are applied to the Si(110)/Si0.5Ge0.5/Si(110) heterostructure, in which the SiGe barrier thickness is several nanometers. It is assumed that the direction of propagation of the electrons makes an arbitrary angle with respect to the interfaces of the heterostructure and the effective mass of the electron is position dependent. The transmission coefficient is calculated for energy below the barrier height, varying the applied voltage to the barrier. The transmission coefficient depends on the valley where the electron belongs and it is not symmetric with respect to the incidence angle
g- Inverses of Interval Valued Fuzzy Matrices
Get PDFIn this paper, we have discussed the g-Inverses of Interval Valued Fuzzy Matrices (IVFM) as a generalization of g- inverses of regular fuzzy matrices. The existence and construction of g-inverses, {1, 2} inverses, {1, 3} inverses and {1, 4} inverses of Interval valued fuzzy matrix are determined in terms of the row and column spaces
Optimization Model for an Airline Crew Rostering Problem: Case of Garuda Indonesia
Get PDFThis paper discusses the cockpit crew rostering problem at Garuda Indonesia, taking into account a number of internal cockpit crew labor regulations. These internal labor regulations are in general more restrictive at Garuda Indonesia than at other airlines, so that modeling the cockpit crew rostering problem for Garuda Indonesia is challenging. We have derived mathematical expressions for the cockpit crew labor regulations and some technical matters. We model a non-linear integer programming for the rostering problem, using the average relative deviation of total flight time to the ideal flight time as the objective function. The optimization model have been tested for all classes of cockpit crews of Garuda Indonesia, using a simulated annealing method for solving the problem. We obtained satisfactory rosters for all crew members in a short amount of computing time. This shows that the optimization problem is well-defined
Catalytic Carbon Submicron Fabrication Using Home- Built Very-High Frequency Plasma Enhanced Chemical Vapour Deposition
Get PDFIn this research, carbon nanotubes (CNT) fabrication has been tried by using an existing home-made Plasma Enhanced Chemical Vapour Deposition (PECVD) system. The fabrication is a catalytic growth process, whereby a Fecatalyst thin film is grown on the Silicon substrate by using dc-Unbalanced Magnetron Sputtering. Methane (CH4) as carbon source and diluted silane (SiH4) in hydrogen as hydrogen source (ratio 10:1) was used for the CNT fabrication with the Very High Frequency PECVD (VHF-PECVD) method. The fabrication process was executed at the relatively low temperature of 250oC, but with the higher operating plasma frequency of 70 MHz. Recently, a fabrication process with only a single gas source has been carried out as well, but using a modified VHF-PECVD system with an additional hot-wirecomponent. The attempt was done at an higher growth temperature of 400oC. Morphological characterizations, by using Scanning Electron Micrograph (SEM) and Scanning Probe Microscopy (SPM), and composition characterization, by using Energy Dispersion Analysis by X-Ray (EDAX), show convincing results that there are some signatures of CNT present