MAKARA Journal of Technology
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Recognition System of Indonesia Sign Language based on Sensor and Artificial Neural Network
Get PDFSign language as a kind of gestures is one of the most natural ways of communication for most people in deaf community. The aim of the sign language recognition is to provide a translation for sign gestures into meaningful text or speech so that communication between deaf and hearing society can easily be made. In this research, the Indonesian sign language recognition system based on flex sensors and an accelerometer is developed. This recognition system uses a sensory glove to capture data. The sensor data that are processed into feature vector are the 5-fingers bending andthe palm acceleration when performing the sign language. The most important part of the recognition system is a featureextraction. In this research, histogram is used as feature extraction. The extracted features are used as data training and data testing for Adaptive Neighborhood based Modified Backpropagation (ANMBP). The system is implemented andtested using a data set of 1000 samples of 50 Indonesia sign, 20 samples for each sign. Among these 500 data were usedas the training data, and the remaining 500 data were used as the testing data. The system obtains the recognition rate of91.60% in offline mode.Keywords: accelerometer sensor, backpropagation, flex sensor, Indonesia sign language, neural networ
A New Experimental Approach to Evaluate Plasma-induced Damage in Microcantilever
Get PDFPlasma etching, during micro-fabrication processing is indispensable for fabricating MEMS structures. During the plasma processes, two major matters, charged ions and vacuum–ultraviolet (VUV) irradiation damage, take charge of reliability degradation. The charged ions induce unwanted sidewall etching, generally called as “notching”, which causes degradation in brittle strength. Furthermore, the VUV irradiation gives rise to crystal defects on the etching surface. To overcome the problem, neutral beam etching (NBE), which use neutral particles without the VUV irradiation, has been developed. In order to evaluate the effect of the NBE quantitatively, we measured the resonance property of a micro-cantilever before and after NBE treatment. The thickness of damage layer (δ) times the imaginary part of the complex Young's modulus (Eds) were then compared, which is a parameter of surface damage. Although plasma processes make the initial surface of cantilevers damaged during their fabrication, the removal of that damage by NBE was confirmed as the reduction in δEds. NBE will realize a damage-free surface for microstructures.Keywords: cantilever, neutral beam etching, surface los
Production Optimization for Plan of Gas Field Development Using Marginal Cost Analysis
Get PDFGas production rate is one of the most important variables affecting the feasibility plan of gas field development. It take into account reservoir characteristics, gas reserves, number of wells, production facilities, government take and market conditions. In this research, a mathematical model of gas production optimization has been developed using marginal cost analysis in determining the optimum gas production rate for economic profit, by employing the case study of Matindok Field. The results show that the optimum gas production rate is mainly affected by gas price duration and time of gas delivery. When the price of gas increases, the optimum gas production rate will increase, and then it will become closer to the maximum production rate of the reservoir. Increasing the duration time of gas delivery will reduce the optimum gas production rate and increase maximum profit non-linearly.Keywords: marginal cost, natural gas fields, production optimizatio
Performance Optimization of Microbial Fuel Cell (MFC) Using Lactobacillus bulgaricus
Get PDFElectrical energy needs in Indonesia are expected to continue to rise. The use of petroleum as a source of energy still dominates, although oil reserves in Indonesia are increasingly being depleted. Therefore, there is a need to develop alternative sources of sustainable energy, such as microbial fuel cell (MFC). In this study, Lactobacillus bulgaricus was used as an electricity producer in a dual-chamber MFC reactor. We investigated the maximum electrical energy by varying the bacterial optical density (OD), the operational time of MFC, the reactor volume, the electrolyte solution, and the configuration of MFC reactor. In this study, the maximum electrical energy (201.8 mW/m2) was generated at an OD of 0.5 in an MFC reactor series using potassium permanganate as the electrolyte solution.Keywords: dual-chamber reactor, Lactobacillus bulgaricus, microbial fuel cell, power densit
Characteristics of Vacuum Freeze Drying with Utilization of Internal Cooling and Condenser Waste Heat for Sublimation
Get PDFVacuum freeze drying is an excellent drying method, but it is very energy-intensive because a relatively long drying time is required. This research investigates the utilization of condenser waste heat for sublimation as a way of accelerating the drying rate. In addition, it also investigates the effect of internal cooling combined with vacuum cooling in the pressure reduction process. Jelly fish tentacles were used as the specimen, with different configurations for condenser heat waste and internal cooling valve opening. The results show that heating with condenser heat waste can accelerate the drying rate up to 0.0035 kg/m2.s. In addition, pre-freezing by internal cooling prevents evaporation until the mass of the specimen is 0.47 g and promotes transition of the specimen into the solid phase.Keywords: condenser waste heat, drying rate, internal cooling, sublimation, vacuum freeze dryin
Determining the Air Gap Length of an Axial Flux Wound Rotor Synchronous Generator
Get PDFThe air gap length of the designed axial flux wound rotor (AFWR) synchronous generator is determined properly according to the design parameters. One of the distinct advantages of an axial flux (AF) machine is its adjustable air gap. An AF generator’s performance might be controlled by adjusting its air gap. The designed generator has a small-scale capacity that has 1 kW, 380 V, and 50 Hz. The windings are laid into slots made from laminated core. The slots are carved in the face of the stator and rotors. The generator has a single-double-sided slotted wound stator sandwiched between twin rotors. The effect of air gap changes on its performance can be seen from the calculation results using the given equations. The results reveal electric quantities suited to the machine’s effective performance. The smaller the air gap, the greater the efficiency and power factor and the smaller the armature current and voltage. The efficiency and armature current for 0.1 cm air gap are 85.30 % and 1.815 A, respectively.Keywords: Synchronous generator, axial flux, wound rotor, air gap, efficienc
ANTIBACTERIAL ACTIVITY OF PAPAYA LEAF EXTRACTS AGAINST PATHOGENIC BACTERIA
Get PDFIt was reported that the extracts of papaya leaves could inhibit the growth of Rhizopus stolonifer. Antibacterial activity of Carica papaya leaf extracts on pathogenic bacteria was observed in this study. Papaya leaves were extracted by using maceration method and three kinds of solvents: ethanol, ethyl acetate, and hexane. Papaya leaf extracts were tested against Bacillus stearothermophilus, Listeria monocytogenes, Pseudomonas sp., and Escherichia coli by agar diffusion method. The objectives of this study were to determine extract ability against pathogenic bacteria, to observe the influence of pH, NaCl, and heat on extracts ability, and to observe extract ability against B. stearothermophilus spores. The data showed that ethyl acetate extract could inhibit B. stearothermophilus, L. monocytogenes, Pseudomonas sp., and E. coli. The extract activity was influenced by pH, and it was more effective in low pH. The extract activity was influenced by NaCl against B. stearothermophillus and E. coli. However, it was not influenced by NaCl in bioassay against L. monocytogenes and Pseudomonas sp. The extract activity was influenced by heating process against all the bacteria tested. The extracts inhibited B. stearothermophilus spores as well. Papaya leaves are potential natural anti-bacteria, which might be used in certain kinds of food.Keywords: antibacterial activity, heat, NaCl solution, papaya leaves, p
COASTAL PHYSICAL VULNERABILITY OF SURABAYA AND ITS SURROUNDING AREA TO SEA LEVEL RISE
Get PDFThe study for coastal vulnerability to sea level rise was carried out in Surabaya and its surrounding area, it has focused on calculations of the physical vulnerability index were used coastal vulnerability index (CVI) methods. It was standardized by the multi criteria analysis (MCA) approach according to the study area. The score of each physical variable derived from remote sensing satellite data and the results of studies that have been done, such as modeling results and thematic maps, and then integrated into geographic information systems (GIS). Result of this study shows that the coastal areas of Gresik, Surabaya, and Sidoarjo in the very low to very high vulnerability level. Physically, the low land areas with open and slightly open coastal have a high vulnerability category. The high level vulnerability was found located in the northern of Madura Strait (Gresik Regency) that overlooks to the Java Sea is about 28.81% from the entire of study areas. Meanwhile, the moderate, low and very low levels of vulnerability were located on Surabaya and Sidoarjo Regency that have more protected coastal area, relatively. According to the physical condition, the coastal elevation is the most variable that contributes to the high of vulnerability index in the coastal of Surabaya City and Sidoarjo Regency. Keywords: coastal vulnerability, sea level rise, remote sensing, CVI, MC
The Plasma Electrolysis Phenomenon in A Two-Compartment Reactor for Chlor-Alkali Production
Get PDFChlor-alkali is one of the most important processes in the chemical industry. It produces chlorine and caustic soda, which become the main feedstock of daily products. The aim of this study is to report the phenomenon of plasma electrolysis and how it can be used in chlor-alkali production for more efficient energy consumption. When the plasma is formed, the current fluctuates and gradually declines. Plasma electrolysis begins with the process of electrolysis itself. Due to Joule heating, gas bubbles are formed and a sheath is made on both electrodes, resulting in the plasma field. Plasma electrolysis can be identified by its radical production. The higher the voltage and concentration, the greater the production of radicals. In 10 minutes or less, the number of OH radicals produced can reach 4 ppm at 400 V and 0.1 M. This amount is relatively small and is caused by other reactions consuming OH radicals to form other radicals such as chlorine. The energy consumption of plasma electrolysis in this study can reach 16 kJ/mmol Cl2 at 0.5 M NaCl solution.Keywords: chlor-alkali, current, plasma electrolysis, radical formation, voltag
ANALISIS FLUTTER SIRIP ROKET BALISTIK RX-420 DENGAN MELIBATKAN MODUS GERAK KAKU STRUKTUR ROKET
Get PDFFlutter Analysis of RX-420 Balistic Rocket Fin Involving Rigid Body Modes of Rocket Structures. Flutter is a phenomenon that has brought a catastrophic failure to the flight vehicle structure. In this experiment, flutter was analyzed for its symmetric and antisymmetric configuration to understand the effect of rocket rigid modes to the fin flutter characteristic. This research was also expected to find out the safety level of RX-420 structure design. The analysis was performed using half rocket model. Fin structure used in this research was a fin which has semispan 600 mm, thickness 12 mm, chord root 700 mm, chord tip 400 mm, made by Al 6061-T651, double spar configuration with skin thickness of 2 mm. Structural dynamics and flutter stability were analyzed using finite element software implemented on MSC. Nastran. The analysis shows that the antisymmetric flutter mode is more critical than symmetric flutter mode. At sea level altitude, antisymmetric flutter occurs at 6.4 Mach, and symmetric flutter occurs at 10.15 Mach. Compared to maximum speed of RX-420 which is 4.5 Mach at altitude 11 km or equivalent to 2.1 Mach at sea level, it can be concluded that the RX-420 structure design is safe, and flutter will not occur during flight.Keywords: fin flutter, Nastran, rigid body modes, rocket, RX-42