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Analisis Regresi Sifat Tanah Terhadap Rebound Tiang Pancang Amalia, Nadya; Rokhmat, Mamat; Sutisna, Sutisna; Viridi, Sparisoma; Abdullah, Mikrajuddin
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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Abstract

The behavior of soil around driven pile during pile driving process directly affect the driving process. Two categories of stress are produced during the driving process, i.e. stress along the pile shaft (shear stress) and stress at the end of the pile (compression stress). Since soil is a porous medium, shear and compressive stresses during the driving process will force water to come out of the pores in the soil. Related to hammering and low permeability of the soil at rebound zones such as clay, water can not flow out of the pores and can not be dissipated instantly. As a result, a high pore water pressure will be generated along the shaft and at the end of the pile. Pile coating with titanium dioxide (TiO2) is able to make the pile to be driven deeper than pile without coating with the same count of hammer strokes for pile driving in clay soils. Uniquely, the coating does not give effect to the pile driving in non-cohesive soils. This indicates that the coating is capable in minimizing pile rebound. Regression model is used in this study to identify the characteristics of engineering soil parameters which may cause the rebound phenomenon.
Fabrikasi Transparant Conducting Film Berbahan Dasar Grafit pada Substrat Plastik dengan Proses Mekanik Rahman, Dui Yanto; Sustini, Euis; Abdullah, Mikrajuddin
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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Abstract

Transparent Conducting Film (TCF) employing graphite powder as conducting material has been successfully fabricated by using extremely cheap and simple method.  This method doesn’t use heating and transfer process which is commonly used in fabrication of Transparent Conducting Film. Graphite powder was directly deposited on the surface of plastic using circle motion of tube shaped-metal which its surface was covered with thick tissue. The film thickness was varied to investigate the influence of it to the transmittance and resistance of the film. The transmittance and resistance measurement was carried out under UV-Vis electrometer and I-V El-Kahfi equipment assistance, and finally the transmittance of 60% and resistance of 24,4 kΩ was gained for one time of coating, While 9 times of coating produced 13% of transmittance and 773 Ω of resistance.
Sintesis Nanokomposit -Fe2O3/SiO2 dengan Metode Salt-Assisted Spray Pyrolysis untuk Menurunkan Viskositas Minyak Berat Anrokhi, Mohamad Samsul; Nuryadin, Bebeh Wahid; Abdullah, Mikrajuddin; Khairurrijal, Khairurrijal; Iskandar, Ferry
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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A α-Fe2O3/SiO2 nanocomposite as aquathermolisys catalyst material at heavy oil has been synthesized and optimized by using  Salt-Assisted Spray Pyrolysis method. The α-Fe2O3/SiO2 nanocomposite is obtained by thermal decomposition from the precursor.  The precursor is made of FeCl3, SiO2 and NaCl and water as a solvent. Concentration of FeCl3, SiO2, and NaCl are 1:1:5 in order. the composition of SiO2 in the composite is 0%, 25% and 50% of total mass, respectively. the droplets were transported to the furnace reactor using air as a carrier gas with a fixed flow rate at 5 liter/min and the furnace’s temperature is 800 °C in order to get the pyrolysis reaction. The resulted powder is then characterized by using XRD, SEM and Chatalytic aquathermolysis test. The result of XRD characterization shows that crystal peaks of α-Fe2O3 has been formed. SEM result shows nanocomposite morphology of α-Fe2O3/SiO2 with circle particle form with average particle diametre of α-Fe2O3, SiO2 25% and SiO2 50% of total mass are 765 nm, 850 nm, and 746 nm, respectively. Catalytic Aquathermolysis test showed catalyst α-Fe2O3/SiO2 50%  has catalytic properties better than catalytic properties of α-Fe2O3/SiO2 and α-Fe2O3/SiO2 25%.
Pengembangan Material Sorben Berbasis Zeolite dan Clay Alam se-bagai Media Desalinasi Air Laut Wibowo, Edy; Rokhmat, Mamat; Sutisna, Sutisna; Khairurrijal, Khairurrijal; Abdullah, Mikrajuddin
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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We have developed a sorbent based natural materials for seawater desalination application. We used clays, soil, rock and zeolite as raw materials. We conducted a thermal activation process to improve the sorption ability of the materials. The sorption ability of materials were tested to reduce the salinity of seawater and it is expressed by the reduction efficiency. The highest reduction efficiency (4%) was obtained from the activation of the soil at temperature of 600 ° C and the zeolite at a temperature of 200 ° C. It can be seen that the reduction efficiency was linearly increased with the increase of the doses of sorbent. We observed that the sorption ability of zeolite can be enhanced through thermal activation at a relatively low temperature so that it was potentially used as a low-cost sorbent material for seawater desalination.
Pengaruh Perbandingan Molaritas Prekursor terhadap Fotoluminesensi BCNO yang Disintesis dengan Metode Hidrotermal Septia Mahen, Ea Cahya; Nuryadin, Bebeh Wahid Nuryadin Wahid; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal, Khairurrijal
Jurnal Matematika dan Sains Vol 18 No 3 (2013)
Publisher : Institut Teknologi Bandung

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Abstrak Fosfor BCNO yang terdispersi pada likuid telah berhasil disintesis menggunakan metode hidrotermal. Bahan dasar (prekursor) yang digunakan adalah asam borat [B(OH)3] sebagai sumber boron, urea [(NH2)2CO] sebagai sumber nitrogen, dan asam sitrat (C6H8O7)sebagai sumber karbon. Dalam penelitian ini, telah dilakukan variasi rasio molar nitrogen terhadap boron (N/B) dan rasio molar karbon terhadap boron (C/B) dan pengaruhnya terhadap pendaran fosfor BCNO yang dihasilkan. Hasil karakterisasi spektrum fotoluminesen dari sampel yang dibuat menunjukkan bahwa pendaran fosfor BCNO mempunyai puncak emisi tunggal disekitar warna biru (~450 nm) ketika dieksitasi dengan sinar UV(365 nm). Intensitas pendaran dipengaruhi oleh kadar karbon terhadap kandungan boron (C/B) dan kadar nitrogen terhadap kandungan boron (N/B). Penambahan kadar karbon dan nitrogen diketahui dapat meningkatkan intensitas pendaran. Sedangkan intensitas optimum pendaran fosfor BCNO dicapai pada saat ratio molar C/B = 1 dan N/B =20. Kata kunci: Fosfor BCNO, Spektrum fotoluminesen, Metode hidrotermal. Influence of Precursor Molar Ratio on the BCNO Photoluminescence synthesized by Hydrothermal Method Abstract BCNO phosphor which is dispersed into liquid has been successfully synthesized by using hydrothermal method. The precursor consists of the borate acid [B(OH)3] as boron source, urea [(NH2)2CO] as nitrogen source, and citric acid (C6H8O7) as carbon source. In this research, molar ratio variations of nitrogen and carbon  towards boron (N/B and C/B), and their influence on resulted BCNO phosphor luminescence were done. The characterization results of the sample shows the single peak of BCNO phorphorous luminescence around blue color (~450 nm) on the photoluminescence spectrum, when excited by UV light (365nm). The photoluminescence intensity was affected by the ratio N/B and C/B. The increase of carbon and nitrogen ratio can increase the photoluminescence intensity. The optimum intensity of BCNO phosphor photoluminescence was obtained at the molar ratio N/B = 20 and C/B =1. Keywords : BCNO phosphor, Photoluminescence spectrum, Hydrothermal method.
Aktivitas Fotokatalitik TiO2 yang Dilapiskan pada Polipropilena Berbentuk Lembaran dan Butiran Sutisna, Sutisna; Rokhmat, Mamat; Wibowo, Edy; Rahmayanti, Handika Dany; Khairurrijal, Khairurrijal; Abdullah, Mikrajuddin
Jurnal Matematika dan Sains Vol 22 No 1 (2017)
Publisher : Institut Teknologi Bandung

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The sheet and granule of polypropylene (PP) have been used as the support material for TiO2 catalyst. The TiO2 powder was coated to the polymer surface using a combination of electrostatic and heating methods (for the PP sheet) and thermal milling method (for PP granule). The photocatalytic testing of catalysts conducted on a 300 ml solution of Methylene Blue (MB) with initial concentration of 25 ppm. Under solar ilumination, the catalyst sheets have a higher photocatalytic activity than the catalyst granules.
Sintesis Nanopartikel Nd-CeO2 Menggunakan Metode Simple Heating untuk Aplikasi Solid Oxide Fuel (SOFCs) Sriyanti, Ida; Abdullah, Mikrajuddin
Jurnal Natur Indonesia Vol 12, No 1 (2009)
Publisher : Lembaga Penelitian dan Pengabdian kepada Masyarakat Universitas Riau

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (92.209 KB) | DOI: 10.31258/jnat.12.1.82-86

Abstract

Nd-CeO2 nanoparticles have been synthesized with a simple heating method. The microstructure and morphologyof material were characterized by a Scanning Electron Microscopy (SEM), and the conductivity of the material wasmeasured by an AC Impedance Spectroscopy. At room temperature we obtain a sample prepared at 9% at/at. Ndhave the highest conductivity of 1.47 x 10-4. Scm-1. This conductivity surpass the value reported by Anefleous for Nd-CeO2 (NDC) material prepared by different method. Sample has been 49 nm crystals size obtained from FWHM .Thisresult proves that a simple heating method is the promising for synthesizing electrolyte materials for SOFCapplication.
APROKSIMASI BRAGG-WILLIAMS PADA MODEL ISING 2D: FENOMENA KRITIS MATERIAL FEROMAGNETIK Wibowo, Edy; Ulya, Naily; Abdullah, Mikrajuddin
Physics Communication Vol 1, No 2 (2017): August 2017
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (772.669 KB) | DOI: 10.15294/physcomm.v1i2.10339

Abstract

Aproksimasi Bragg-Williams pada model Ising 2D material feromagnetik disajikan dalam makalah ini berdasarkan tinjauan mekanika statistik. Mekanika statistik menjelaskan fenomena fisika pada skala makroskopik ditinjau dari bentuk interaksi materi penyusun sistem tersebut. Berdasarkan tinjauan mekanika statistik, jika ungkapan energi sistem diketahui maka fungsi partisi sistem tersebut akan dapat ditentukan sehingga besaran-besaran termodinamik pada skala mikroskopik dapat ditentukan. Sistem makroskopik tersusun oleh materi dengan kuantitas yang sangat besar dengan karakteristik yang juga sangat kompleks sehingga tidak bisa lagi didekati dengan mekanika klasik. Berangkat dari permasalahan ini, Ising membangun sebuah model sederhana untuk menjelaskan fenomena pada skala makroskopoik dengan melihat keteraturan interaksi yang terjadi pada skala mikroskopik. Dengan menggunakan model tersebut, Ising berhasil menyatakan ungkapan energi total dan fungsi partisi sebuah sistem material feromagnetik. Banyak pendekatan yang telah dilakukan untuk mencari solusi model Ising ini, pendekatan yang paling sederhana adalah aproksimasi Bragg-Williams. Dari hasil aproksimasi Bragg-Williams pada model Ising 2D diperoleh informasi bahwa kemagnetan bahan feromagnetik ditentukan oleh tingkat keteraturan spin dari atom-atom dalam kristal (short-range order dan long-range order). Keteraturan spin-spin ini akan berkurang dan akhirnya lenyap saat mencapai temperatur kritis. Temperatur kritis merupakan temperatur transisi material feromagnetik dari sifat magnet ke bukan magnet. Pendekatan ini berhasil menjelaskan fenomena magnetisasi spontan dan peristiwa perubahan capasitas panas yang terjadi secara drastis pada material feromagnetik. Miskipun pada awalnya model Ising digunakan untuk menjelaskan terjadinya fenomena kritis pada material feromagnetik, namun saat ini sudah dikembangkan untuk memodelkan berbagai fenomena fisika yang lain seperti binary alloy, kisi gas, cacat kristal, ketidak teraturan material kaca, bahkan sejumlah fenomena di luar bidang fisika.
A Low Cost C8051F006 SoC-Based Quasi-Static C-V Meter for Characterizing Semiconductor Devices Endah Rahmawati; Riska Ekawita; Maman Budiman; Mikrajuddin Abdullah; Khairurrijal Khairurrijal
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 10, No 4: December 2012
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v10i4.862

Abstract

Based on a C8051F006 SoC (system on-a-chip), a simple and low cost quasi-static capacitance-voltage (C-V) meter was designed and developed to obtain C-V characteristics of semiconductor devices. The developed C-V meter consists of a capacitance meter, a programmable voltage source, a C8051F006 SoC-based slave controller, and a personal computer (PC) as a master controller. The communication between the master and slave controllers is facilitated by the RS 232 serial communication. The accuracy of the C-V meter was guaranteed by the calibration functions, which are employed by the program in the PC and obtained through the calibration processes of analog to digital converter (ADC), digital to analog converters (DACs) of the C8051F006 SoC, and the programmable voltage source. Examining 33-pF and 1000-pF capacitors as well three different p-n junction diodes, it was found that the capacitances of common capacitors are in the range of specified values and typical C-V curves of p-n junction diodes are achieved.
Numerical Simulation of Tunneling Current in an Anisotropic Metal-Oxide-Semiconductor Capacitor Fatimah A. Noor; Ferry Iskandar; Mikrajuddin Abdullah; Khairurrijal Khairurrijal
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 10, No 3: September 2012
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v10i3.826

Abstract

In this paper, we have developed a model of the tunneling current through a high- dielectric stack in MOS capacitors with anisotropic masses. The transmittance was numerically calculated by employing a transfer matrix method and including longitudinal-transverse kinetic energy coupling which is represented by an electron phase velocity in the gate. The transmittance was then applied to calculate tunneling currents in TiN/HfSiOxN/SiO2/p-Si MOS capacitors. The calculated results show that as the gate electron velocity increases, the transmittance decreases and therefore the tunneling current reduces. The tunneling current becomes lower as the equivalent oxide thickness (EOT) of HfSiOxN layer increases. When the incident electron passed through the barriers in the normal incident to the interface, the electron tunneling process becomes easier. It was also shown that the tunneling current was independent of the substrate orientation. Moreover, the model could be used in designing high speed MOS devices with low tunneling currents.