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INDONESIA
Jurnal Matematika & Sains
Published by Institut Teknologi Bandung
ISSN : -     EISSN : -     DOI : -
Core Subject : Education,
Mathematics
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Articles 339 Documents
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Sintesis dan Karakteristik Membran Komposit Akrilonitril Butadiena Stirena (ABS)-Kitosan Tersulfonasi untuk Direct Metanol Fuel Cell (DMFC) Hidayati, Nur; Mujiburohman, Muhammad; Abdillah, Hamid; Harmoko, Tri; Arimurti, Rizki Dyah
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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Direct Methanol Fuel Cell (DMFC) is a type of fuel cell that converts methanol directly into electrical energy. The commercialization constraints of fuel cells in Indonesia is due to the high cost of manufacturing, including the expensive electrolyte membrane which is one of the important components of fuel cells. Utilization of cheap and abundant local materials such as acrylonitrile butadiene styrene (ABS) and chitosan can reduce the fuel cell manufacturing cost burden. The membrane currently used for DMFC is the Nafion® membrane. The superiority of Nafion® membrane has high ionic conductivity and membrane stability, while Nafion® membrane deficiency is a very expensive price and has a high enough methanol permeability that can lead to a decrease in overall cell voltage performance. This study studied the characteristics of ABS-sulfonated Chitosan membrane membrane with ratio (20:80) and (40:60) prepared on 6-hour, 12 hour, 18 hour, 24 hour sulphonation time variation. The experimental results show a sulfonation time of 24 hours, in the ratio of ABS: Chitosan (20:80 wt) provides membrane characteristics such as water uptake 48.50%, swelling degree 25%, ion exchange chamber 2.030 meq / g, and methanol permeability 2,9336x10 -6 cm2 / s.
Pengaruh Oksidasi Setelah Deposisi Terhadap Sifat Film Tipis ZnO:Ga Faizal, Reza; Marwoto, Putut; Sulhadi, Sulhadi; Sugianto, Sugianto
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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The effect of after-deposition oxidation to the thin film properties Ga doped ZnO has been studied.  Film deposited using dc magnetron sputtering method at temperature 300oC for one hour and then it was performed variations of oxidation using oxygen gas (99,9%) with pressure of 0 mTorr and 50 mTorr at a temperature of 300 ° C for 20 minutes. According to the image scanning of electron microscopy, it shows that the film grain size became larger in oxygen pressure of 50 mTor as compared to the pressure of 0 mTor. UV-Vis spectrophotometer analysis showed the film transmittance in visible light increases with the increasing of oxygen pressure reached ~83%. Band-gap energy that has been produced by film on the oxygen pressure of 0 mTorr and 50 mTorr are respectively 3.32 eV and 3.4 eV.
The Effects of Atomic Substitutions (Bismuth, Gallium, Arsenic) on Electronic and Magnetic Properties of Carbon Nanotubes Aprilia, Ely; Muttaqien, Fahdzi; Purqon, Acep; Suprijadi, Suprijadi
Jurnal Matematika dan Sains Vol 20 No 1 (2015)
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Investigations of carbon nanotubes (CNT) properties by substituting impurity atoms are interesting, since the the defects show different properties and potentially wide applications. In this paper, we investigate the effects of atomic substitutions (Bismuth, Gallium, Arsenic) on electronic and magnetic properties of CNT by using Density Functional Theory method with Generalized Gradient Approximation. Our results show that Bismuth and Arsenic doped on zigzag CNT (10, 0) give the band gap and magnetic moment 0.19 eV and 2 μB, respectively. In contrast, Gallium doped shows no band gap and change the semiconductor properties of zigzag edge CNT (10, 0) into metal. Furthermore, the moment magnetic for Gallium-Arsenide doped CNT (10, 0) is 1 μB. Keywords: Atomic substitution, Band gap, Carbon nanotubes (CNT), DOS, Impurity.   Pengaruh Atom Pengganti (Bismut, Galium, Arsenik) pada Sifat Elektronik dan Magnetik Karbon Nanotube Abstrak Kecacatan pada struktur CNT mengakibatkan adanya perubahan sifat elektronik dan magnetiknya. Perubahan sifat inilah yang menyebabkan CNT  menarik untuk diteliti karena berpotensi memiliki aplikasi yang luas. Pada penelitian ini, dibahas mengenai  efek dari atom pengganti (Bismut, Galium dan Arsen) pada sifat elektronik dan magnetik CNT(10,0) yang dihitung dengan menggunakan teori fungsional kerapatan dan Generalized Gradient Approximation. Hasilnya menunjukan bahwa atom pengotor Bismut dan Arsen pada CNT (10,0) menghasilkan band gap sebesar 0.19 eV dan momen magnetik sebesar 2 μB. Sedangkan atom pengotor Galium tidak menghasilkan band gap pada CNT(10,0) dan mengubah sifat semikonduktor CNT(10,0) menjadi metal. Dari perhitungan didapatkan juga magnetik momen pada CNT (10,0) dengan atom pengotor Galium dan Arsen sebesar 1 μB. Kata kunci: Atom pengganti, Band gap, Karbon nanotube, DOS, Ketidakmurnian.
Aljabar Max-Min Bilangan Kabur dan Matriks Rudhito, M. Andy
Jurnal Matematika dan Sains Vol 21 No 1 (2016)
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Artikel ini membahas suatu aljabar himpunan semua bilangan kabur (fuzzy number) yang dilengkapi denganoperasi maximum dan minimum, serta matriks atas aljabar tersebut. Aljabar ini merupakan perluasan aljabar maxmin melalui aljabar max-min interval dan Teorema Dekomposisi dalam himpunan kabur. Dapat ditunjukkanoperasi maximum dan minimum yang didefinisikan melalui potongan-alfa tertutup dalam himpunan semua bilangankabur tersebut. Himpunan semua bilangan kabur yang dilengkapi dengan operasi maximum dan minimum tersebutmerupakan semiring idempoten komutatif. Selanjutnya himpunan semua matriks atas atas aljabar tersebutmerupakan semimodul. Diberikan pula contoh perhitungannya dengan menggunakan Program MATLAB
Pengaruh Temperatur Solution Treatment dan Aging terhadap Struktur Mikro dan Kekerasan Copperized-AISI 1006 Sutarsis, Sutarsis; Vicky, Widia Anggia; Purwaningsih, Hariyati
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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As one of the alloying elements used in low carbon steel, copper can increase the strength of steel without lowering its ductility significantly. Copper increases the strength of steel by precipitation hardening. In this research, copper and AISI 1006 steel were alloyed by immersing the pre-heated steel into molten copper. After the imersion process, the precipitation hardening was performed with variations in temperature of solution treatment and aging. From the results of this study, it was found that the solution treatment temperature did not affect the phase of copperized-AISI 1006, but the aging process affected the formation of secondary phase. The increase of solution treatment temperature is proportional to the increase of copperized-AISI 1006 average grain diameter. In contrast, the use of aging temperature of 450oC obtained the smallest average grain diameter than others, in the amount of 49,23 μm and 50,26 μm for sample that previously being  solution treatment at 800 and 900oC. Besides, the increase of the solution treatment temperature is inversely  proportional to the hardness number of copperized-AISI 1006. However, the aging temperature of 450oC obtained the highest hardness number than other aging temperature, in the amount of 119,47 VHN and 115,75 VHN for sample that previously being solution treatment at 800 and 900oC.
Penentuan Kondisi Operasi Elektroplating Krom yang Ramah Lingkungan Perdana, Sanjaya Putra; Priambodo, Anton; Munarsyah, Tryas; Pustaka, Bagas Winagandi; Widayanto, Tri
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
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Electroplating is a method of surface coating by using an electrolytic process. The technique was aimed to improve its corrosion resistance and to obtain an aesthetic and decorative appearance. In the experiments, metalic chrome was used to be electrodeposited on to copper substrates. A thin layer of electrodeposited chrome was expected to be on the surface of working electrode. The working electrode was copper plate (3 mm thickness) with a length of 2 cm and a width of 1 cm. Polarization experiments were carried out at various electrolyte concentrations of 5 g/l, 10 g/l and 15g/l. Electrolytes were prepared using chromium chloride because it is more environmentally friendly. Polarization experiments were carried out by applying potentials range between 0.1V ando 3.5V at intervals of 0.1 V. The electrical current responses were recorded so that polarization curves were obtained. Electrochemical parameters such as potential and current for electroplating were determined based on the polarization curves. The electrical currents used for electroplating experiments were 80% of  limiting current and the limiting current for  each concentration. The results of electroplating experiments were then analyzed using digital microscopy. The results obtained at a concentration of 5 g/l and 10 g/l show more uniform and smoother surfaces. Deposited chrome obtained at the concentration of 15 g/l was non uniform thickness. It can be concluded that a relatively good deposited chrome was obtained at the electrolyte concentration of 5 g/l at a current of 18.2 mA which shows more uniform and dense plated chrome.
Aturan Cramer dalam Aljabar Maks-Plus Interval Siswanto, Siswanto
Jurnal Matematika dan Sains Vol 20 No 1 (2015)
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Dalam paper ini dibahas aturan Cramer yang dapat digunakan untuk menyelesaikan suatu sistem persamaan linear dalam aljabar maks-plus interval berbentuk . Misalkan  himpunan semua bilangan real dan  dengan  Aljabar maks-plus adalah himpunan  dilengkapi dengan operasi  (maksimum) dan  (plus). Telah dibahas tentang aturan Cramer untuk menyelesaikan sistem persamaan linear dalam aljabar maks-plus. Dari himpunan  dapat dibentuk himpunan  yaitu himpunan yang anggotanya merupakan interval-interval tertutup dalam . Himpunan  yang dilengkapi dengan operasi  (maksimum) dan   (plus) disebut aljabar maks-plus interval.  Kata kunci : Aturan Cramer, Aljabar maks-plus interval.Cramer's Rule in Interval Max-Plus AlgebraAbstract This paper discusses Cramer's rule that can be used to solve a system of linear equations in interval max-plus algebra . Let  be the set of real numbers and  with  Max-plus algebra is the set  that is equipped with operations  (maximum) and  (plus). It has been discussed about Cramer's rule to solve a systems of linear equations in the max-plus algebra. From the set  can be formed the set , the set whose members are closed intervals in . The set  equipped with operations  (maximum) and  (plus) is called interval max-plus algebra. Keywords : Cramer's rule, Interval max-plus algebra.  
Pembentukan Ring Bersih Menggunakan Lokalisasi Isnaini, Uha
Jurnal Matematika dan Sains Vol 21 No 1 (2016)
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Abstract

Diberikan sebarang ring R (tidak harus komutatif) dan himpunan multiplikatif S R  yang tidak memuat elemennol. Lokalisasi Ore merupakan salah satu teknik pembentukan ring sehingga setiap elemen S memiliki invers di ringyang baru. Ring hasil lokalisasi tidak selalu mempertahankan sifat ring awal. Suatu ring sebarang dapat disisipkanke ring bersih, ring bersih-n dan ring peralihan. Sehingga sangat menarik untuk dikaji sifat-sifat yang diperlukanuntuk menyisipkan sebarang ring ke ring tersebut menggunakan lokalisasi.
Efektifitas Penggunaan Silika dari Abu Sekam Padi sebagai Katalis pada Material Penyimpan Hidrogen Sistem MgH2 Jalil, Zulkarnain; Pajriana, Elisa; Rahwanto, Adi
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
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Magnesium (Mg) and its alloys are among the potential candidates as materials for hydrogen stor-age applications because they have the ability to absorb hydrogen in large quantities. However Mg has a drawback, ie kinetic reaction is quite slow. For that we need an intensive effort to overcome this, one of them is with catalyst insertion. In this paper, we report on the use of silica catalyst (SiO2) from rice husk ash in the MgH2 hydrogen storage material. SiO2 material inserted into MgH2 of 1 wt%, 3wt% and 5wt% using high energy ball milling technique. Results of observations by XRD showed a milling process that lasted for 5 hours successfully reduced to nanokristal scale. The emerging phase, from the XRD observation, is the MgH2 phase as the most dominant phase. Thermal characterization with DSC showed that the addition of SiO2 was able to decrease the desorption time and temperature of 338,720C in 14.75 minutes in 5wt% catalyst variation.

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