MAKARA Journal of Technology
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PAPAN SERAT BERKERAPATAN SEDANG BERBAHAN BAKU SLUDGE TERASETILASI DARI INDUSTRI KERTAS
Get PDFMedium Density Fibreboard Made of Acetylated Sludge from Paper Mill. Research of using sludge as raw material for making medium density fibreboard (MDF) was useful to create additional value of sludge. The objective of the research was to evaluate physical properties, mechanical properties, and durability of MDF from acetylated sludge in 4 levels of acetate anhydride (0%, 3%, 5%, and 7%) with 3 replicates. The MDF was made using dry process. After materials were mixed with adhesives, they were pressed using hotpress under 170 oC temperature and 45 Pa pressure for 25 minutes. The size of the MDF sample was 25 cm x 20 cm x 1 cm with 0.8 g/cm3 density. The physical properties (density, moisture content, water absorption, thickness swelling) and mechanical properties (modulus of elasticity, modulus of rupture, internal bond, screw holding power) was tested based on JIS A 5905-2003 standard. The durability was evaluated using SNI 01-7207-2006. All physical properties of MDF fulfill JIS A 5905-2003. Acetate anhydride decreased the moisture content value of MDF. On the other hand, all mechanical properties did not fulfill the standard. That was caused by calcium carbonate in sludge that blocked the adhesion between sludge fibres. The durability of MDF tested here was classified Class I which is very resistant to termites.Keywords: acetylated sludge, durability properties, MDF, mechanical properties, physical propertie
OBSERVATION OF CENTER DISASTER DAMAGE ON PARIAMAN AND WASIOR USING DIFFERENTIAL SAR INTERFEROMETRY (DInSAR)
Get PDFThis study focuses on disaster observations in Pariaman (West Sumatera) and Wasior (Papua) using remote sensing techniques (differential SAR interferometry). Differential interferometry (DInSAR) method was performed on two PALSAR data sets with different acquisition months, i.e. about a month after and before disaster, respectively. The center damage of Pariaman earthquake and Wasior flood can be determined by deriving Land Subsidence using DInSAR method.Keywords: ALOS/PALSAR, DInSAR, flood potential area, land Subsidence (LS), log rati
PENAMBAHAN TEMBAGA PADA KOMPOSIT PP/C DAN PENGARUHNYA PADA SIFAT MEKANIK DAN KONDUKTIVITAS LISTRIK PELAT BIPOLAR KOMPOSIT PP/C-Cu
Get PDFEffect of Copper Addition on Mechanical Properties and Electrical Conductivity of PP/C-Cu Bipolar Plate Composites. Bipolar plate is a major component in PEM fuel cell which possess main function of collecting and removing electrons from anode to cathode. Therefore, materials for bipolar plates produced must have high electrical conductivity. To obtain bipolar plate materials which is cheap, lightweight and high conductivity, so it is developedbipolar plates material based on PP/C-Cu composite. PP/C-Cu composites has been made by mixing all materials then compounding, rheomix, hot blending and hot press. Cu (Copper) has been used various from 0.1 wt%, 1 wt% to 2 wt% to increase electrical conductivity of PP/C-Cu composite. It is found that the effect of Cu addition in PP/C-Cu composite has increased tensile strength, flexural strength, flexural modulus, tensile modulus, elongation, electrical conductivity and decreasde porosity, unfortunately the value of electrical conductivity was still lower than standard requirement for bipolar plate fuel cell.Keywords: bipolar plates, electrical conductivity, mechanical properties, PEM fuel cell, polypropylene matrix composit
EFFECTS OF DEPOSITION PARAMETERS AND OXYGEN ADDITION ON PROPERTIES OF SPUTTERED INDIUM TIN OXIDE FILMS
Get PDFIndium tin oxide (ITO) films were sputtered on corning glass substrate. Oxygen admixture and sputtering deposition parameters were optimized to obtain the highest transparency as well as lowest resistivity. Structural, electrical and optical properties of the films were then examined. Increasing deposition rate and film thickness changed the crystallographic orientation from (222) to (400) and (440), as well as higher surface roughness. It was necessary to apply substrate heating during reposition to get films with better crystallinity. The lowest resistivity of 5.36 x 10-4 Ω•cm was obtained at 750 nm film thickness. The films’ resistivity was increased by addition of oxygen up to 2% in the argon sputtering gas. All films showed over 85% transmittance in the visible wavelength range, possible for applications in photovoltaic and display devices. Keywords: characterization, indium semiconductor, sputtering, thin films, tin oxid
IMPROVED OPTICAL PROBE FOR MEASURING PHYTOPLANKTON SUSPENSION CONCENTRATIONS BASED ON OPTICAL FLUORESENSCE AND ABSORPTION
Get PDFThis paper discusses the results of improved optical probe that works according to optical fluorescence and absorption phenomena for measuring the phytoplankton suspension concentrations. Measurements are made on the Scenedesmus sp. culture. The laboratory test has shown that range of concentration from 104 up to around 1 x 106 cells/mL; fluorescence intensity at λ= 685 nm; and logarithmic of transmission intensity at λ= 405 nm are proportional to the cell concentration linear with proportional constant γ = 4 × 10-5 and β = –2 × 10-7 mL/cell respectively.Keywords: optical probe, optical fluorescence, optical absorption, phytoplankton concentratio
Development of Seebeck-Coefficient Measurement Systems Using Kelvin-Probe Force Microscopy
Get PDFThermoelectric device is investigated by a number of researchers in order to enhance the thermoelectric efficiency. It is known that the efficiency can be improved by quantum effect. However, it is difficult to measure the thermoelectric characteristics of nanometer-scale structures. Thus a new measurement method is expected to be developed. We propose to apply Kelvin-probe force microscopy (KFM) to characterization of thermoelectric materials. KFM can locally observe surface potential of Fermi energy of a sample without touching the sample surface. In the present paper, we estimate the Seebeck coefficient of thin Si-on-insulator layers using KFM.Keywords: Fermi energy, Kelvin-probe force microscopy, Seebeck coefficien
MODIFICATION OF FLOW STRUCTURE OVER A VAN MODEL BY SUCTION FLOW CONTROL TO REDUCE AERODYNAMICS DRAG
Get PDFAutomobile aerodynamic studies are typically undertaken to improve safety and increase fuel efficiency as well as to find new innovation in automobile technology to deal with the problem of energy crisis and global warming. Some car companies have the objective to develop control solutions that enable to reduce the aerodynamic drag of vehicle and significant modification progress is still possible by reducing the mass, rolling friction or aerodynamic drag. Some flow control method provides the possibility to modify the flow separation to reduce the development of the swirling structures around the vehicle. In this study, a family van is modeled with a modified form of Ahmed's body by changing the orientation of the flow from its original form (modified/reversed Ahmed body). This model is equipped with a suction on the rear side to comprehensively examine the pressure field modifications that occur. The investigation combines computational and experimental work. Computational approach used a commercial software with standard k-epsilon flow turbulence model, and the objectives was to determine the characteristics of the flow field and aerodynamic drag reduction that occurred in the test model. Experimental approach used load cell in order to validate the aerodynamic drag reduction obtained by computational approach. The results show that the application of a suction in the rear part of the van model give the effect of reducing the wake and the vortex formation. Futhermore, aerodynamic drag reduction close to 13.86% for the computational approach and 16.32% for the experimental have been obtained.Keywords: active flow control, aerodynamic drag reduction, reversed Ahmed body, suctio
CONCURRENT ENGINEERING OF TOLERANCE SYNTHESIS AND PROCESS SELECTION FOR PRODUCTS WITH MULTIPLE QUALITY CHARACTERISTCS CONSIDERING PROCESS CAPABILITY
Get PDFThe existences of variances that are very difficult to be removed from manufacturing processes provide significance of tolerance to the product quality characteristics target of customer functional requirement. Furthermore, quality loss incurred due to deviation of quality characteristics of the target with a specified tolerance. This article discusses the development of concurrent engineering optimization model of tolerance design and manufacturing process selection on product with multiple quality characteristics by minimizing total costs in the system, namely total manufacturing cost and quality loss cost as functions of tolerance, also rework and scrap costs. The considered multiple quality characteristics have interrelated tolerance chain. The formulation of proposed model is using mixed integer non linear programming as the method of solution finding. In order to validate of the model, this study presents a numerical example. It was found that optimal solution are achieved from proposed model in the numerical example. Keywords: optimization model, quality loss, rework, scrap, toleranc
AGE, GENDER, AND MUSCLE STRENGTH: A STUDY BASED ON INDONESIAN SAMPLES
Get PDFAge and gender have been commonly used as a main criterion in accepting a job aplicant, but it is usually not clear how these affect job performance. While a number of recent studies have been done that describe the relationships between age, gender, and participants capacity (e.g., muscle strength), the results have been inconclusive. In Indonesia, in particular, such issues have been rarely investigated, and it is still important to study the issue since the relationships between these factors are population-specific. This study aimed at describing the relationships between age and muscle strength among workers for both genders. Ninety-six male and female workers (aged 18–65) were recruited in this study, and data on handgrip and lower back strength were collected. Findings of this study show that peak hand-grip strength occured at the age of around 35-40 years of age, regardless of gender. Maximum lower back strengh was identified at the age of 31-35 years old (for males) and 26-30 years old (for females). Comparisons between two extreme age groups (18-20 vs. 61-65 years of age) showed a mean strength decline of 50% for hand-grip and 30% for the lower back. For both protocols, female participants tended to have lower muscle strength (70-80% of their male counterparts). Findings of this study can be used as a basis in evaluating physical requirements of a job, and the corresponding factors (age and gender) relevant for the job.Keywords: age, capability, gender, handgrip strength, lower back strengt
EVALUATION OF UNIVERSITAS INDONESIA’S RECHARGE POND PERFORMANCE AND POTENTIAL UTILIZATION FOR RAW WATER SOURCE
No full textThe UI recharge pond has been constructed 5 years ago. However, monitoring and evaluation activities on its performances are very lack. Aims of this study are to understand the recharge rate, and to evaluate existing quantity and water quality of the pond during dry and rainy season. Measurement of water depth, rainfall intensity, and evaporation is conducted to determine water availability, recharge rate, and water balance of the recharge pond. Amount of surface water is collected from recharge pond and river at three sampling point to determine existing water quality of the pond. The results showed that recharge rate of the pond between dry season (3.2 mm/day) and wet season (6.1 mm/day) are considered as insignificant different. The water balance of the recharge pond shows an excessive rate. Various physics and chemical parameters (turbidity, color, TDS, pH, and Cl) are found to have concentration lower than the water quality standard. The results suggest that the pond surface water is remain suitable to be recharged into aquifer zone so that sustaining ground water conservation campaign, and it is potential to be utilized as an additional raw water source for domestic water demand of UI Campus Depok.Keywords: raw water source, recharges rate, UI recharge pond, water conservation, water quantity and qualit