| Nama Pengarang | : | Kekenusa, John S. |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 43-52 |
| Abstraksi Narasi | : | Skipjack (Katsuwonus pelamis L.) needs to be managed well as a renew-able natural resource but vunerable to depletion or extinction. One approach in fish resource management is by modelling. Analysis was carried out, aimed to get the best model for surplus production model, to assess the Maximum Sustainable Yield (MSY), and to get the skipjack utilization and effort level. Data used for surplus production model were collected from skipjack landings data provided by Marine and Fisheries Service (Dinas Kelautan dan Perikanan) of North Sulawesi Province. The best Surplus Production Model that can be used to assess the skip-jack potential yield is the Schaefer model. The optimum effort per year biologically EMSY is (38,319 trip). The optimum yield biologically CMSY is (34, 504, 39 ton). Utilization level in 2003 is 106.60% with effort level 96.96 %. The catch in 2003 is al-ready above the MSY value, which shows an overfishing. |
| Nama Pengarang | : | Jumina |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 111-117 |
| Abstraksi Narasi | : | N-Indol-1-ylacetamide 3 was obtained in 90% yield from treatment of 3,4 dimethoxy-2,3-diphenylindole 1 with N,N-dimethylchloroacetamide in dimethylsulfoxide in the presence of potassium hydroxide. When reacted with oxalyl chloride in benzene followed by dymethylamine, indol-1-ylacetamide 2 turned to glyoxylamide 3 in 89% yield. Slightly different to this last phenomenon, indol-1-ylacetate 4 gave only 44% of glyoxyl ester 5 when treated with oxalylchloric in benzene, followed by methanol. Both of glyoxylamide 3 and glyoxyl ester 5 failed to undergo cyclisation to generate the related pyrroloindoles when treated with some bases such as sodium hydride, sodium methoxide, and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The crystal structure of glyoxylamide 3 indicated that geometrically this glyoxylamide is unlikely to undergo cyclisation to afford the expected pirroloindole. |
| Nama Pengarang | : | Yosaphat Sumardi |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 141-150 |
| Abstraksi Narasi | : | The aim of this research is to make numerical simulation of effective stress, birefringence, and eigenmode in a silica-on-silicon waveguide. By this simulation the effect of optical-stress to the parameters of the material in the waveguide can be identified. The numerical simulation is performed using FEMLAB which is integrated in MATLAB. The numerical analysis is limited to plane strain and fundamental eigenmode. The results of this research are ; (1) the effective stress pattern in the surface, contour, and cross section plots, (2) the birefringence pattern in the surface and cross section plots, (3) the fundamental eigenmode pattern in the cross section plot with accuracy up to five and four decmal places, (4) the optical stress in the waveguide influences the propagation constants and the birefringence. The values of birefringence vary libnearly in vertical direction from 2.9 x 10.. at the bottom to 2.4 x 10.. at the top of the core. |
| Nama Pengarang | : | Anastasia Rita Widiarti |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 167-176 |
| Abstraksi Narasi | : | Segmentation is a process to separate document images into their individual compponents. There are currently many algorythm available for segmentation. In this research, projection profil of the input document were used to derive to the image`s constituent characters. The result shows an 86.78 percent successrate using this method to segment images modern Javanese manuscripts, specifically Menak Sorangan I and Panji Sekar. This leads us to conclude that the use of this document image segmentation method is appropiate. |
| Nama Pengarang | : | D.Asmi, I. M. Low and B. O Connor |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 119-125 |
| Abstraksi Narasi | : | The analysis of X-ray diffraction (XRD) patterns using the Rietveld method was tested to the quantitatively phase compositions of ß-spodumene ... modified ... composites. It is clear that the addition of ... has significant effect on the phase composition of the ... composites as confirmed by XRD Rietveld refinement analysis. The addition of >2.5 wt % ß-spodumene caused the reduction of ... content and the formation of ß-quarts solid solution, which can be attributed due to the in-situ reaction sintering of alumina and ... precusor to form ß-spodumene modified ... composite as expected was not achieved. The refinement X-ray diffraction data analysis showed that the goodness of fit (GOF) values was relatively low and the fluctuations in the differnce plots showed a reasonable fit between the observed and the calculated plot. |
| Nama Pengarang | : | Linggo Sumarno |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 185-197 |
| Abstraksi Narasi | : | This paper proposes a system of off-line recognition of noisy and scaled handwritten letters based on DCT (Discrete Cosine Transform), which is used extensively in lossy compression of data. The system employs Probabilistic Neural Netwrok, which is used in many enineering problems and pattern recognition. Simulation results on existing database, which was created by a single writer, indicate that the system is adequate to be used up to certain levels of noise and scalling. At noise level 0% and scale 1, the system is able to get recognition rate up to 91 %, whereas at noise level 0% and scale 0,7% as well as at noise level 10% and scale level 0.8, the recognition rates are 84.6% and 79.9%, respectively. |
| Nama Pengarang | : | I Nyoman Budiantara, Mulianah |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 159-166 |
| Abstraksi Narasi | : | Kernel approach has local characteristics which can be used to estimate the parameter ... and the regression curve ... in regression semiparametric model. The Kernel estimator depends on bandwidth parameters. In this research we compute the optimal bandwidth using Rice (T) method, which can handle local characteristics in data. We also investigate the asymptotic behaviour of the T method. An application in health science is done to explore the heart function ..., where ... is ASAT (Aspartate Aminotrasfose) having parametric relationship with cholesterol (..). Using T method we obtained the optimal bandwidth h = 30,72. |
| Nama Pengarang | : | Dwiretnani Sudjoko |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 177-183 |
| Abstraksi Narasi | : | The aim of this research was to observe the preparation of zirconium dioxide from zirconium hidroxide by calcination process. Zirconium dioxide was made by calcination of zirconium hidroxide at high temperature for certain period of time. The variable studied were temperature of 800 C - 1000 C and a time of 1-4 hours. From the calcination of zirconium hidroxide the followings came to reality: X-Ray diffraction showed that the oxide, i.e zirconium oxide and zirconium concentration of oxidized samples, increased with the increasing of the temperature of 1000 C. At this condition the conversion was 99,57%, while the purity of zirconium dioxide was 80,86% |
| Nama Pengarang | : | Fahru Nurosyid, Nuryani, Budi Purnama, Erti Fatkul Jannah |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 127-132 |
| Abstraksi Narasi | : | In this research the effect of Cu and indium tin oxide (ITO) substrates with respect to the growth of crystal structure, morphology structure, and magnetoresistance rqtio of thin film has been explores. The growth of NiFe thin film has been done by electrodeposition method. The crystal structure was analyxed using x-rsy diffractometer (XRD), the morphology structure was examined using scanning electron microscope (SEM), and the magnetoresistance was determined by two point probe methods. The XRD spectrum showed that the substrate influences the crystal structure. The thin film produced was in the form of NiFe polycrystalline with FCC (face center cubic) structure. The NiFe thin film formed crystal planes (111), (200), and (220) on Cu substrate, (111) and (200) on ITO substrate. The result of SEM showed that the surface morphology of substrate has influenced the porphology structureof the thin film. The ratio of magnetoresistance of NiFe thin film was 8.9 % on Cu and 10.9% on ITO substance |
| Nama Pengarang | : | Syamsurijal Rasimeng, Andius Dasaputra, Alimuddin |
| Nama Majalah/Jurnal | : | Sigma Jurnal Sains dan Teknologi |
| Volume / Nomor Edisi | : | - |
| Nomor Halaman | : | 151-158 |
| Abstraksi Narasi | : | The aim of this research is to make numerical simulation of effective stress, birefringence, and eigenmode in a silica-on-silicon waveguide. By this simulation the effect of optical-stress to the parameters of the material in the waveguide can be identified. The numerical simulation is performed using FEMLAB which is integrated in MATLAB. The numerical analysis is limited to plane strain and fundamental eigenmode. The results of this research are ; (1) the effective stress pattern in the surface, contour, and cross section plots, (2) the birefringence pattern in the surface and cross section plots, (3) the fundamental eigenmode pattern in the cross section plot with accuracy up to five and four decmal places, (4) the optical stress in the waveguide influences the propagation constants and the birefringence. The values of birefringence vary libnearly in vertical direction from 2.9 x 10-4 at the bottom to 2.4 x 10 -4 at the top of the core. |
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