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IPTEK The Journal for Technology and Science
Published by Institut Teknologi Sepuluh Nopember Surabaya
ISSN : 08534098     EISSN : 20882033     DOI : -
Core Subject : Science,
Computer Science & IT
IPTEK The Journal for Technology and Science (eISSN: 2088-2033; Print ISSN:0853-4098), is an academic journal on the issued related to natural science and technology. The journal initially published four issues every year, i.e. February, May, August, and November. From 2014, IPTEK the Journal for Technology and Science publish three times a year, they are in April, August and December in online version.
Arjuna Subject : -
Articles 345 Documents
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Integrated Fuzzy AHP and Weighted-Fuzzy Goal Programming Approach to Solve Supplier Selection Problem with Subjective Factors Annas S. Setiyoko; Udisubakti Ciptomulyono; I. K. Gunarta
IPTEK The Journal for Technology and Science Vol 18, No 1 (2007)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v18i1.181

Abstract

Fuzzy goal programming (FGP) method used in supplier selection process shows that decision maker preferences on each fuzzy goal are not yet considered. In order to accommodate those preferences, that are stated as weight on each fuzzy goal, and called weighted fuzzy goal programming (WFGP) method. Then, the developed method is utilized to solve international supplier selection problem. There would be 4 objective functions developed i.e. to minimize net cost, to minimize late delivery, to minimize net rejected material, as well as to maximize business relationship. Maximization of business relationship objective function is intended to obtain right suppliers related to it score. Those objective functions are optimized subject to total demand, maximum supplier capacity, total purchasing cost based on owner estimate, and minimum order requested by suppliers. Linguistic variables are used to measure criterions in business relationship factor. To do so, fuzzy analytic hierarchy process (FAHP) transforms that qualitative manner in linguistic variables to numerical number as a constant in business relationship objective function. Those proposed method provides enhanced solution that represent decision maker preferences than FGP. That is exhibited with equal relationship between weighted goals value and the output of those weighted goals.
A New Method for Modeling Bottom Shear Stress under Irregular Waves Taufiqur Rachman; Suntoyo Suntoyo
IPTEK The Journal for Technology and Science Vol 22, No 2 (2011)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v22i2.60

Abstract

The bottom shear stress estimation is the most important step to device an input to all the practical sediment transport models. In this paper, the modeling of bottom shear stress in a rough turbulent bottom boundary layer under irregular waves of experimental result is examined by a new calculation method of bottom shear stress based on incorporating velocity and acceleration terms simultaneously. A new acceleration coefficient is proposed to formulate the bottom shear stress under irregular waves. The new formula is further examined with a basic harmonic wave cycle modified with the phase difference and square of the instantaneous friction velocity incorporating the acceleration effect as proposed by the previous researchers. The new method gave the smallest the RMSE value indicating that the new method has the best agreement with the bottom shear stress of experimental results. Therefore, it can effectively be utilized in a beach evolution model by combining it with the irregular wave transformation model.
Unified Discrete Wavelet Transform with Ridge Regression and Principal Component Regression to Predict Concentration of Gingerol Compound in Ginger Crop Sony Sunaryo
IPTEK The Journal for Technology and Science Vol 19, No 3 (2008)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v19i3.148

Abstract

Multivariate calibration model can be used as an alternative method to predict the concentration of a gingerol compound. The prediction usually are carried out chemically through a long and expensive process using High Performance Liquid Chromatography (HPLC) measurement method. Since the number of samples (n) are less than of the number of independent variables (p), and between the independent variables are correlated, so the development of model using conventional regression is not valid. The combination of Discrete Wavelete Transform (DWT) with Ridge Regression and Principal Component Regression have been adopted in this paper to predict concentration of gingerol, and it showed a promising result.
Ethanol Production from Molasses with Immobilized Cells Technique in Packed Bed Bioreactor by Extractive Musfil AS; Tri Widjaja; Ali Altway; R. Darmawan Darmawan
IPTEK The Journal for Technology and Science Vol 21, No 1 (2010)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v21i1.26

Abstract

The aim of this research was to study the effect of total sugar concentration, Ca-Alginate and K Carrageenan density in immobilized cells on packed-bed and batch bioreactor performance for ethanol production. In addition, this research was also aimed to study the effect of solvent flow rate on packed column performance expressed as % extraction recovery. This experiment was carried out with total sugar concentration of 10, 14, 18 % (v/v) and immobilized cells Ca-Alginate and K-Carrageenan at a density of 2% (w/v) with amyl alcohol as solvent. Based on the result of this study, it is concluded that the total sugar concentration influenced the concentration, yield and productivity of ethanol. The result of this study for immobilized Ca-Alginate cells showed that the maximum ethanol product concentration, yield and productivity were 7.28% g/l, 57.48 g/l, 38.22%, 71.85 g/l.hr, respectively. Meanwhile, immobilized K-Carrageenan cells showed the maximum ethanol product concentration, yield and productivity as 7.22% /56.99 g/l, 26.73%, and 68.40 g/l.hr, respectively. In extraction process, increasing amyl alcohol solvent flow rate will increase mass transfer and hence increase ethanol recovery.
An Evaluative Study on Sidoarjo Mud Flow after Phytoremediation Treatment in Milk Fish (Chanos Chanos) Liver Dewi Hidayati
IPTEK The Journal for Technology and Science Vol 21, No 4 (2010)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v21i4.51

Abstract

A sudden discharge of Sidoarjo mud flow into the water bodies would disturb aquatic biota, the fisheries culture. The aim of this research is to evaluate the availability of phytoremediated water of Sidoarjo mud flow (abbreviated: pwmf) as a milkfish culture media using liver histological approach. After two weeks acclimatization period, the juvenile and adult of milkfish were exposed the pwmf at the sub lethal concentration and an acute static bioassay at 96 hours. Control fishes were reared in the artificial brackish water. Each treatment of pwmf exposure was done in three replicates. After exposure, the liver fishes were removed and histologically processed using paraffin method and HE staining. Histopathology change was assessed semi quantitative scoring. The result of the histological analyses suggested the liver pathological features such as vacuolation of hepatocytes, the loss of sinusoid integrity from mild to severe occurrence and necrosis.
Detecting Springs in the Coastal Area of the Gunungsewu Karst Terrain, Yogyakarta Special Province, Indonesia, Analysis using Fractal Geometry Sari Bahagiarti Kusumayudha Sari Bahagiarti Kusumayudha
IPTEK The Journal for Technology and Science Vol 20, No 4 (2009)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v20i4.86

Abstract

The Gunungsewu area is a karst terrain with water scarcity, located in the Yogyakarta Special Province, adjacent to the open sea of Indian Ocean in the South. Shorelines of the Gunungsewu southern parts show fractal geometry phenomenon, and there can be found some groundwater outlets discharging to the Indian Ocean. One of the coastal outlets exists at the Baron Beach.The amount of water discharge from this spring reaches 20,000 l/sec in wet season, and approximately 9000 in dry season. In order to find other potential coastal springs, shoreline of the south coast is divided into some segments. By applying fractal analysis utilizing air photo of 1 : 30,000 scale, the fractal dimension of every shore line segment is determined, and then the fractal dimension value is correlated to the existence of spring in the segment being analyzed. The results inform us that shoreline segments having fractal dimension (D) > 1.300 are potential for the occurrence of coastal springs.
EMS-45 Tool Steels Hardenability Experiment using Jominy ASTM A255 Test Method Syamsul Hadi; Eddy Widiyono; Winarto Winarto; Dedy Z. Noor
IPTEK The Journal for Technology and Science Vol 24, No 1 (2013)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v24i1.137

Abstract

Hardenability of steels is an important way to determine heat treatment and material properties that produce component products. Jominy test is one of the method to know hardenability of steels. The Jominy ASTM A255 in used as a method for carriying out and this reseach. Parameter such as austenite temperature, holding time, cooling rate and then the results is dedicated by the prediction result, with Non Linear Numerical Equation Method. Based on test, it’s known, increasing austenite temperature, longer holding time and high cooling rate, will increase hardenability of steels. The different between the results and the prediction result done by Sonh Yue-Peng[15], Matja equation[14] and Zehtab equation[10], about 5 % -10 %. The data obtained from this experiment can be used to determine the appropriated heat treatment in order to get the desired mechanical properties, as well as to avoid distortion.
PEMFC Optimization Strategy with Auxiliary Power Source in Fuel Cell Hybrid Vehicle Tinton Dwi Atmaja; Amin Amin
IPTEK The Journal for Technology and Science Vol 23, No 1 (2012)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v23i1.17

Abstract

one of the present-day implementation of fuel cell is acting as main power source in Fuel Cell Hybrid Vehicle (FCHV). This paper proposes some strategies to optimize the performance of Polymer Electrolyte Membrane Fuel Cell (PEMFC) implanted with auxiliary power source to construct a proper FCHV hybridization. The strategies consist of the most updated optimization method determined from three point of view i.e. Energy Storage System (ESS), hybridization topology and control system analysis. The goal of these strategies is to achieve an optimum hybridization with long lifetime, low cost, high efficiency, and hydrogen consumption rate improvement. The energy storage system strategy considers battery, supercapacitor, and high-speed flywheel as the most promising alternative auxiliary power source. The hybridization topology strategy analyzes the using of multiple storage devices injected with electronic components to bear a higher fuel economy and cost saving. The control system strategy employs nonlinear control system to optimize the ripple factor of the voltage and the current and using the AOC-EMS system to improve the hydrogen consumption rate. ECMS and BERS strategy based on Time-Triggered Controller Area Network (TTCAN) also promoted to optimize hydrogen consumption rate from recovered kinetic energy while in braking regeneration mode.
A Lvq-Based Temporal Tracking for Semi-Automatic Video Object Segmentation Mochamad Hariadi; Mauridhi H. Purnomo
IPTEK The Journal for Technology and Science Vol 18, No 2 (2007)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v18i2.172

Abstract

This paper presents a Learning Vector Quantization (LVQ)-based temporal tracking method for semi-automatic video object segmentation. A semantic video object is initialized using user assistance in a reference frame to give initial classification of video object and its background regions. The LVQ training approximates video object and background classification and use them for automatic segmentation of the video object on the following frames thus performing temporal tracking. For LVQ training input, we sampling each pixel of a video frame as a 5-dimensional vector combining 2-dimensional pixel position (X,Y) and 3-dimensional HSV color space. This paper also demonstrates experiments using some MPEG-4 standard test video sequences to evaluate the accuracy of the proposed method.
Statistical Downscaling Output GCM Modeling with Continuum Regression and Pre-Processing PCA Approach Sutikno Sutikno; Setiawan Setiawan; Hendy Purnomoadi
IPTEK The Journal for Technology and Science Vol 21, No 3 (2010)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v21i3.41

Abstract

One of the climate models used to predict the climatic conditions is Global Circulation Models (GCM). GCM is a computer-based model that consists of different equations. It uses numerical and deterministic equation which follows the physics rules. GCM is a main tool to predict climate and weather, also it uses as primary information source to review the climate change effect. Statistical Downscaling (SD) technique is used to bridge the large-scale GCM with a small scale (the study area). GCM data is spatial and temporal data most likely to occur where the spatial correlation between different data on the grid in a single domain. Multicollinearity problems require the need for pre-processing of variable data X. Continuum Regression (CR) and pre-processing with Principal Component Analysis (PCA) methods is an alternative to SD modelling. CR is one method which was developed by Stone and Brooks (1990). This method is a generalization from Ordinary Least Square (OLS), Principal Component Regression (PCR) and Partial Least Square method (PLS) methods, used to overcome multicollinearity problems. Data processing for the station in Ambon, Pontianak, Losarang, Indramayu and Yuntinyuat show that the RMSEP values and R2 predict in the domain 8x8 and 12x12 by uses CR method produces results better than by PCR and PLS.

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