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INDONESIA
Matematika dan Sains
Published by Universitas Negeri Surabaya
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Core Subject : Education,
Mathematics
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Articles 67 Documents
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CUBIC SPLINE ESTIMATOR IN MULTIPREDICTOR NONPARAMETRIC REGRESSION MODELS WITH LOGNORMAL ERRORS AND ITS Nur Chamidah, ; Toha Saifudin,
Matematika dan Sains Vol 16, No 1 (2009)
Publisher : Matematika dan Sains

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Abstract

Suppose that n observations follow multiplicative nonparametric regression models with errors which are lognormally distributed. The assumption on causes the values of ln would be normally distributed . So, by taking natural logarithm of the model, we have an additive nonparametric regression model. In this paper, we estimate regression function of the model by using nonparametric regression approach, i.e, cubic spline estimator. Next, we give an applying illustration of the model on Gmelina Arborea Roxb data.
STUDI KINETIKA KRISTALISASI Soni Sukendar, ; Triwikantoro,
Matematika dan Sains Vol 16, No 1 (2009)
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Abstract

The crystallization kinetic of metallic glass Zr69.5Cu12Ni11Al7.5 was studied by using differential scanning calorimetry (DSC). The activation energy for such the crystallization of the amorphous phase was about (268 ± 5.7) kJ mole-1 calculated from Arrhenius plot. The crystallization process correspond to the normal Arrhenius plot with a constant linear slope. These results show that the mechanism and activation energy for the crystallization of Zr69.5Cu12Ni11Al7.5 alloy are not temperature-dependent. The order of crystallization (Avrami exponent) was calculated by using the Johnson–Mehl–Avrami (JMA) plot. The average value of the Avrami exponent was about (2,58 ± 0.29) at the range from 663K to 683 K. 69.5Cu12Ni11Al7.5 was studied by using differential scanning calorimetry (DSC). The activation energy for such the crystallization of the amorphous phase was about (268 ± 5.7) kJ mole-1 calculated from Arrhenius plot. The crystallization process correspond to the normal Arrhenius plot with a constant linear slope. These results show that the mechanism and activation energy for the crystallization of Zr69.5Cu12Ni11Al7.5 alloy are not temperature-dependent. The order of crystallization (Avrami exponent) was calculated by using the Johnson–Mehl–Avrami (JMA) plot. The average value of the Avrami exponent was about (2,58 ± 0.29) at the range from 663K to 683 K.
SIMULASI PENDEKATAN FIXED RANDOM WALK DALAM ANALISIS DISTRIBUSI POTENSIAL LISTRIK PADA PELAT BERHINGGA Supardiyono, ; Gagus Ketut Sunnardianto,
Matematika dan Sains Vol 16, No 1 (2009)
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Abstract

The electric potential distribution was needed to determine the electrical field intensity and total charge in the condensator. This paper discussed the simulation of fixed random walk to analyze the electric potential distribution at unlimited plate using the matlab 7.1 program. The Procedure were carried out as follow: drawing configuration of two dimensional plate, determining the boundary condition, grid, and the sum random walk. Accuracy of the Monte Carlo method in fixed random walk approach were determined by the sum random walk (N), grid (Ä), and right of model system. The results obtained from the fixed random walk simulation closed with the analytic result. The presence of electrical potential value in interior plate area showed just there was one probably potential distribution for specific requisite limit of configuration.
OPTIMASI DISTRIBUSI JARINGAN LISTRIK Santi Aris Setyaningrum, ; Aditya Prapanca,
Matematika dan Sains Vol 16, No 1 (2009)
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Abstract

The propose of research was to study algorithm simulated annealing applying to re-arrange electrics extension position for the low voltage electrics network distribution with minimization length of cable using Mathlab 7. Data processed were obtained from the PLN electrics distribution data for the regional distribution of Kertajaya Indah Timur Surabaya. The results showed that length of cable needed without simulated annealing was 2300 m, while the length of cable could be decreased till 1600 m by using simulated annealing.
EFEKTIVITAS BAKTERI PELARUT POSFAT Bacillus subtilis Indriani Agustin, ; Yuliani, ; Yuni Sri Rahayu,
Matematika dan Sains Vol 16, No 1 (2009)
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The aims of research were to study the enfluence adding of B. subtilis in various concentration to the phosfat concentration and TPH value on the mining land and to find the optimum concentration of B. subtilis. This research was experiment with completely randomized design using one treatment namely the concentration of B. subtilis with four replications. Data obtained were analyzed discriptively. The results of research showed that adding of B. subtilis in various concentration enfluence the increasing of phosfat concentration, decreasing of TPH value and C/N ratio on the mining land. The optimum concentration of B. subtilis was 109 cell/mL.9 cell/mL.
KEMAMPUAN BAKTERI Achromobacter xylosoxidans DAN Arthtrobacter polychromogenes TERHADAP PENURUNAN TOTAL PETROLEUM HYDROCARBON (TPH) PADA TANAH TERCEMAR MINYAK BUMI DI BOJONEGORO Lady Diana, ; Yuliani,
Matematika dan Sains Vol 16, No 1 (2009)
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Abstract

The goal of research were to study the enfluence adding of Achromobacter xylosoxidans and Arthtrobacter polychromogenes and its combination to TPH value, P-available, N-total, and C/N ratio on the land polluted by petrolleum and to find the kind of bacteria that could optimally decrease TPH value, increase phosfat available and N total, and decrease C/N ratio. This research was experiment with completely randomized design using one treatment namely using Achromobacter xylosoxidans and Arthtrobacter polychromogenes with four replications. Data obtained were analyzed descriptively. The results of research showed that the adding A. Xylosoxidans, A. Polychromogenes and its combination could decrease the TPH value, increase P-availlabe and N total, and decrease C/N ratio. A. xylosoxidans could decrease TPH value optimally, while A. polychromogenes increase the N total and decrease C/N ratio effectively. The combination of A. xylosoxidans and A. polychromogenes could increase P-availlable optimally.
KARAKTERISASI MEMBRAN KOMPOSIT KITOSAN-SILIKA HASIL SINTESIS UNTUK SEL BAHAN BAKAR M. Ali Zulfikar, ; D. Wahyuningrum, ; S. Achmad, ; N. Tanyela Berghuis,
Matematika dan Sains Vol 16, No 1 (2009)
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Abstract

The composite membrane of chitosan-silica in various curing temperature could be synthezed. It was synthezed using sol-gel method and reverse phase in various curing temperature. The resulted membrane was characterized its physicochemical properties including methanol permeability, ion exchange capacity, water absorbtion, structure by FTIR, ion conductance, morphology analysis using SEM. The results showed that methanol permeability and water absorbtion value decreased with increasing curing temperature, in the other hand ion exchange capacity and ion conductace increase. Morphology analysis result showed that the surface of membrane becomed lebih rapat with increasing curing temperature.
ISOLASI DAN UJI BIOAKTIVITAS SENYAWA KIMIA DARI TALUS LICHEN USNEA DASYPOGA (ACH.) NYL. Sri Winiati1, ; Wahyudi Priyono Suwarso2, ; Herry Cahyana2, ; M. Hanafi3,
Matematika dan Sains Vol 16, No 1 (2009)
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Abstract

Two known compounds, namely (-)-usnic acid and eumitrin A1, had been isolated from the lichen Usnea dasypoga (Ach.) Nyl. The molecular structure of all isolates were determined by the spectroscopic data (UV, IR, NMR, MS). The (-)-usnic acid and eumitrin A-1 showed toxicity against Artemia salina with LC50 of 39,52 µg/mL and 2,25 µg/mL, respectively. While two isolates also showed cytotoxycity againts murine leukemia P-388 cells with IC50 of 6,5 µg/mL dan 3,2 µg/mL, respectively.50 of 39,52 µg/mL and 2,25 µg/mL, respectively. While two isolates also showed cytotoxycity againts murine leukemia P-388 cells with IC50 of 6,5 µg/mL dan 3,2 µg/mL, respectively.
SUATU SENYAWA BIFLAVONOID DARI BIJI BUAH Nurbariyah, ; Taslim Ersam,
Matematika dan Sains Vol 16, No 1 (2009)
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UJI KESTABILAN KALIUM FERAT Nur Hayati, ; Nita Kusumawati, ; Bertha Yonata,
Matematika dan Sains Vol 16, No 1 (2009)
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The synthesis of potassium ferrate and the optimazion as green chemistry degradator had been studied. The purpose of research was to study the influence of pH and reaction time to potassium ferrate stability. This research was started by synthesis and characterization of potassium ferrate. Some parameters influencing degradation process by ferrate ion, such as pH and molar reaction time have been studied, and the decomposition result was quantization by spectrophotometry UV-Vis. Based on the XRD spectra, it was found that the solid phase potassium ferrate had a tetrahedral structure with a space group of D2h(Pnma). The potassium ferrate solution had a maximum stability at pH 9-10. Decomposition result of ferrate indicated that kinetic constant was stable at spanning time 24-72 hours.2h(Pnma). The potassium ferrate solution had a maximum stability at pH 9-10. Decomposition result of ferrate indicated that kinetic constant was stable at spanning time 24-72 hours.

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