MAKARA Journal of Technology
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INDUKSI DAN KONDUKSI GELOMBANG ELEKTROMAGNETIK AKIBAT SAMBARAN PETIR PADA JARINGAN TEGANGAN RENDAH
Get PDFInduction and Conduction Electromagnetic Waves Caused by Lightning Strike on the Low Voltage Network.Direct and indirect lightning strikes can disturb and induce low voltage overheadlines and it can produced overvoltagedue to traveling waves along the lines. This overvoltage can damage the equipments connected to it. It was recordedthat there were already a lot of damages of electronic equipments and arrestesr located inside the building of LightningMeasurement Station at Mnt. Tangkuban Perahu. Most of the overvoltage which was developed on the low voltage lineswere coming from indirect lightning strike nearby due to the fact that most of the lines were covered by trees. Researchwas carried out to study and evaluate the induction and conduction of the lightning strikes to the LV lines that can leadto the cause of equipment and arrester damages inside the building. Local lightning data for the analysis were derivedfrom measurement system installed at the stations and historical lightning data from lightning detection network calledJadpen (National Lightning Detection Network). The data was used for calculating and evaluating the voltage elevation,induction voltage profiles and conduction in the form of traveling waves using Rusck Model. Two damaged arresterswere evaluated and compared and it give the better understanding on how the protection system work.Keywords: arrester, arrester damages, lighting data, lightning induction, rusck model, voltage elevation
PENGARUH OZON DAN KONSENTRASI ZEOLIT TERHADAP KINERJA PROSES PENGOLAHAN LIMBAH CAIR YANG MENGANDUNG LOGAM DENGAN PROSES FLOTASI
Get PDFThe Effect of Ozone and Zeolite Concentration to the Performance of the Treatment of Wastewater Containing Heavy Metal Using Flotation Process. Industrial wastewater which contains heavy metal cannot be disposed to the environment directly, due to its toxicity. In this research, separation of metal from wastewater was conducted by sorptive flotation method, using Lampung natural zeolite as bonding agent. The most common diffuser used in the flotation process is air or oxygen. In this research, ozone is used as diffuser because it is a stronger oxidant and more dissolvable in water than oxygen. Besides, ozone is a coagulant aid and disinfectant. With ozone as diffuser, it is expected that the process become faster with higher efficiency. This research was conducted to determine ozone effectiveness as diffuser, compared with other diffuser, and also to determine optimum concentration and effectiveness of zeolite in flotation of iron, nickel and copper. The research result shows that separation of iron with air diffuser is 90.8%, air-oxygen diffuser is 95.7%, air-ozone (from air) diffuser is 99.7%, and air-ozone (from oxygen) diffuser is 99.7%. Natural zeolite is effective as bonding agent with optimum concentration equal to 2 gram/liter, producing separation percentage for iron equal to 99.70%, copper equal to 88.98% and Nickel equal to 98.46%.Keywords: flotation, ozone, zeolite, heavy meta
PENGARUH WAKTU KONTAK TERHADAP REAKSI ANTAR MUKA PADUAN ALUMINIUM 7%-Si DAN ALUMINIUM 11%-Si DENGAN BAJA CETAKAN SKD 61
Get PDFEffect of Contact Time on Interface Reaction between Aluminum Silicon (7% and 11%) Alloy and Steel DiesSKD 61. Die soldering (die sticking) is a defect of metal casting in which molten metal “welds” to the metallic die moldsurface during casting process. Die soldering is the result of an interface reaction between the molten aluminum and thedie material. Aluminum alloy with 7 and 11% silicon and SKD 61 die steel are the most common melt and die materialused in aluminum die casting. This research is done to study the morphology and the characteristics of the formedAlxFeySiz intermetallic layer during interface reaction at dipping test. The samples of as-anneal SKD 61 tool steel wasdipped into the molten of Al-7%Si held at temperature 680oC and into molten Al-11%Si held at temperature 710oC withthe different contact time of 10 minutes; 30 minutes; and 50 minutes. The research results showed that the interfacereaction can form a compact intermetallic layer with AlxFey phase and a broken intermetallic layer with AlxFeySizphase on the surface of SKD 61 tool steel. The increasing of the contact time by the immersion of material SKD 61 toolsteel in both of molten Al-7%Si and Al-11%Si will increase the thickness of the AlxFeySiz intermetallic layer until anoptimum point and then decreasing. The micro hardness of the AlxFeySiz intermetallic layer depends on the content ofthe iron. Increasing of the iron content in intermetallic layer will increase the micro hardness of the AlxFeySiz. Thiscondition happened because the increasing of Fe content will cause forming of intermetallic AlxFeySiz phase becomesquicker.Keywords: Aluminum silicon alloy, interface reaction, AlxFeySiz intermetallic layer, die soldering, SKD 61 tool stee
PERANAN FASE AMORF Si3N4 PADA NANOKOMPOSIT nc-TiN/a-Si3N4 DALAM MENINGKATKAN KEKERASAN DAN STABILITAS TERMAL
Get PDFThe role of Si3N4 amorphous phase in nc-TiN/a-Si3N4 nanocomposites will be shown and compared with polycrystalline ZrN/Ni which has no such amorphous phase (non-composites). The presence of amorphous phase Si3N4 increases the hardness of film as well as the toughness of the bulk nanocomposites under indentation load. It has been observed that nc-TiN/a-Si3N4 nanocomposites films has higher thermal stability than ZrN/Ni polycrystalline films.Keywords: Nanokomposit, ZrN/Ni, fase amorf Si3N
STUDI TENTANG PENGARUH DOPING TINGGI TERHADAP RESISTANSI BASIS DAN BANDGAP NARROWING PADA Si/Si1-xGex /Si HBT
Get PDFStudy About High Influence Doping to Base Resistance and Bandgap Narrowing at Si/Si1-xGex/Si HeterojunctionBipolar Transistor. Heterojunction is a link formed bedween two semiconductor materials and differend bandgapwhich has thinness under 50nm and grow the mixture of plate SiGe as bases. The link is an abrupt link or graded one.In this research learnt formulation of doping concentration influence to basis resistance and bandgap narrowing throughSi/Si1-xGex/Si Heterojunction Bipolar Transistor with abrupt emitter-basis link, besides taking care to mobility andbasis wide to basis resistance, it is also influence of mole fraction to bandgap power. From the result shows that dopingconcentration addition of NB=5.1018 cm-3 to NB=5.1020 cm-3 in basis can decrease resistance basis value about 3.6%,increase bandgap narrowing about 0.126, and increase collector current density for about 1.36 times to Ge 24%.Keywords : Heterojunction, doping, bandgap narrowin
CHANNEL CAPACITY OF HIGH-SPEED POWERLINE COMMUNICATION IN VEHICLES
Get PDFPowerline Communication (PLC) Systems intents to use the mains network in vehicles for high-speed datatransmission. Carrier frequencies in the range of MHz are required to establish data rates of some megabits per second.In this paper, typical reference channels extracted from channel measurements are presented and computation results oftheir capacities according to Shannon's theorem are presented. Furthermore, the effect of limitations of frequencyrange and power spectral density of transmitted signal on achievable capacity is investigated. This paper outlines anassessment for theoretical channel capacity and achievable data rates of vehicular PLC transmission schemes. Finally,EMC (Electromagnetics Compatibility) constraint according to CISPR 25 (Comite International Special desPerturbations Radioelectrique - The International Special Committee on Radio Interference) is deeply considered.Keywords: vehicular PLC, noise, channel capacity, data rates, EMC
OPTIMASI DIFFUSER PADA EXHAUST SYSTEM DENGAN CATALYTIC CONVERTER UNTUK SEPEDA MOTOR 110 CC DENGAN SIMULASI CFD ALIRAN FLUIDA
Get PDFDiffuser Optimation at Exhaust System with Catalytic Converter for 110 cc Mopet with Fluid Flow CFDSimulation. CFD simulation used to get behavior of exhaust gas through catalyst, this result will be used to optimizegeometry form to perform uniform stream distribution to catalyst, and CFD Simulation will used to analyzebackpressure that happened at the model.Keywords: catalytic converter, selection of material, CFD simulation, diffuser optimizatio
SIMULASI PENGUKURAN INTRAFAIRNESS DAN INTERFAIRNESS PROTOKOL-PROTOKOL STREAM CONTROL TRANSMISSION PROTOCOL (SCTP) DAN TRANSMISSION CONTROL PROTOCOL (TCP) PADA JARINGAN UNICAST
Get PDFThis paper elaborates the performance analysis of a unicast network when two protocols, SCTP (Stream ControlTransmission Protocol) and TCP (Transmission Control Protocol) coexist in the network. These two protocols are testedusing File Transfer Protocol (FTP) and Constant Bit Rate (CBR) based traffic. From the simulations, it could beconcluded that SCTP could achieve better throughput compared to TCP in both FTP and CBR based traffic, withsufficiently high fairness index of both intrafairness and interfairness. The increase of simulation time yields to theincrease and relatively stable network performance. The increase of the number of sessions of small bandwidthapplications resulted in the increase of troughput and link utilization. The simulations show that implementation ofSCTP and TCP in a unicast network generally could be done without having to degrade the network performance, withrelatively high fairness index, over 0.85 for various traffic variations.Keywords: SCTP, Interfairness, Intrafairness, TCP, Unicas
AN ECONOMIC ANALYSIS OF VARIABLE RATE TECHNOLOGY
Get PDFVariable Rate Technology (VRT) offers an opportunity to improve production efficiency by allowing input applicationsto fluctuate in response to spatial variations in soil characteristics and nutrient levels. Society may also benefit fromreduced negative externalities, such as surface and groundwater contamination, from input applications. Using adynamic spatial model, this study examines how the interaction among variability, spatial autocorrelation, and meanlevel of soil fertility affects optimal sampling density and the economic gains from VRT. VRT was found to beprofitable under selected conditions, and the optimal grid size will vary with these conditions. In the case wherevariability and mean fertility levels are significantly high associated with low spatial autocorrelation, VRT producesgreater net returns than Uniform Rate Technology (URT), even with the smallest grid size to base the input applicationdecisions. Results also demonstrate that optimal grid size increases with increased spatial autocorrelation.Keywords: spatial autocorrelation, spatial variability, variable rate technology
PENGARUH PENEMPATAN PENYAMBUNGAN PADA PERILAKU RANGKAIAN BALOK-KOLOM BETON PRACETAK BAGIAN SISI LUAR
Get PDFInfluence of Connection Placement to the Behavior of Precast Concrete Exterior Beam-Column Joint. This paperpresents an experimental study on the influence of connection placement to the behaviour of exterior beamcolumnjoint of precast concrete structure under semi cyclic loading. Four half-scale beam-column specimens wereinvestigated. Three beam-columns were jointed through connection that are placed in beam-column joint region and theforth is connected at the plastic hinge potensial region of the beam. Crack patterns, strength, stiffness and ductility ofthe test specimens have been evaluated. The test result indicated that all beam-column specimens show good ductilitybehavior.Keywords: precast concrete, beam-column joint, reinforced concret