MAKARA Journal of Technology
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ON THE PERFORMANCE OF IMT-2000 COMMUNICATION LINK BASED ON STRATOSPHERIC PLATFORMS
Get PDFA new means for providing wireless communication has been currently proposed. It is based on aerial vehicle known asHigh Altitude Platform or Stratospheric Platforms (SPF). The SPF will be operated at an altitude of 17-22 km above theground. Therefore, the channel condition may be different compared with those of the conventional terrestrial orsatellite wireless channel. In this paper, the channel propagation characteristic of such a system is firstly investigated bymeans of ray tracing algorithm. We emphasize our investigation in a typical urban environment, in which the mobileusers mostly exist. We developed building block model for simulation based on building height distribution, which isobtained from measurement inside Tokyo. As a result, propagation loss model and Ricean channel parameter for theSPF channel is reported in different scenarios. By using this result we then estimate the required transmitted power ofSPF to serve the mobile users in a several transmission rate that is used in IMT-2000 services. Finally, an evaluation ofBER of IMT-2000 link is performed in order to estimate the system level performance. From this evaluation, the maincontribution of this paper is to clearly show the critical limitations of both power requirement as well as system levelperformance of mobile communication IMT-2000 by using the concept of the SPF.Keywords: link performance, IMT-2000, high altitude platform, stratospheric platfor
PRODUKSI BIOGASOLINE DARI MINYAK SAWIT MELALUI REAKSI PERENGKAHAN KATALITIK DENGAN KATALIS γ-ALUMINA
Get PDFBiogasoline Production from Palm Oil Via Catalytic Hydrocracking over Gamma-Alumina Catalyst. Bio gasolineconversion from palm oil is an alternative energy resources method which can be substituted fossil fuel base energyutilization. Previous research resulted that palm oil can be converted into hydrocarbon by catalytic cracking reactionwith γ-alumina catalyst. In this research, catalytic cracking reaction of palm oil by γ-alumina catalyst is done in a stirrerbatch reactor with the oil/catalyst weight ratio variation of 100:1, 75:1, and 50:1; at suhue variation of 260 to 340oCand reaction time variation of 1 to 2 hour. Post cracking reaction, bio gasoline yield could be obtained after 2 steps batch distillation. Physical property test result such as density and viscosity of this cracking reaction product and commercialgasoline tended a closed similarity. According to result of the cracking product's density, viscosity and FTIR, it canconclude that optimum yield of the palm oil catalytic cracking reaction could be occurred when oil/catalyst weight ratio100:1 at 340 oC in 1.5 hour and base on this bio gasoline's FTIR, GC and GC-MS identification results, its hydrocarbons content was resembled to the commercial gasoline. This palm oil catalytic cracking reaction shown 11.8% (v/v) in yield and 28.0% (v/v) in conversion concern to feed palm oil base and produced a 61.0 octane number's biogasoline.Keywords: Bio gasoline, γ-alumina, viscosity, density, palm oi
SULFONASI FILM cPTFE TERCANGKOK STIRENA UNTUK MEMBRAN PENGHANTAR PROTON SEL BAHAN BAKAR
Get PDFSulfonation of cPTFE Film grafted Styrene for Proton Exchange Membrane Fuel Cell. Sulfonation of γ-rayiradiated and styrene-grafted crosslinked polytetrafluoroethylene film (cPTFE-g-S film) have been done. The aim of theresearch is to make hydropyl membrane as proton exchange membrane fuel cell. Sulfonation was prepared withchlorosulfonic acid in chloroethane under various conditions. The impact of the percent of grafting, the concentration ofchlorosulfonic acid, the reaction time,and the reaction temperature on the properties of sulfonated film is examinated.The results show that sulfonation of surface-grafted films is incomplete at room temperature. The increasing ofconcentration of chlorosulfonic acid and reaction temperature accelerates the reaction but they also add favor sidereactions. These will lead to decreasing of the ion-exchange capacity, water uptake, and proton conductivity butincreasing the resistance to oxidation in a perhidrol solution. The cPTFE-g-SS membrane which is resulted has stabilityin a H2O2 30% solution for 20 hours.Keywords: proton exchange membrane, sulfonation, chorosulfonic acid, cPTFE film
RANCANG BANGUN PERANGKAT LUNAK SISTEM AUTO TRACKING SATELLITE ANTENNA MOBILE MENGGUNAKAN METODE AZIMUT-ELEVASI DAN KOREKSI MODEM
Get PDFSoftware Design of Mobile Antenna for Auto Satellite Tracking using Modem Correction and Elevation AzimuthMethod. Pointing accuracy is an important thing in satellite communication. Because the satellite’s distance to thesurface of the earth's satellite is so huge, thus 1 degree of pointing error will make the antenna can not send data tosatellites. To overcome this, the auto-tracking satellite controller is made. This system uses a microcontroller as thecontroller, with the GPS as the indicator location of the antenna, digital compass as the beginning of antenna pointingdirection, rotary encoder as sensor azimuth and elevation, and modem to see Eb/No signal. The microcontroller useserial communication to read the input. Thus the programming should be focused on in the UART and serialcommunication software UART. This controller use 2 phase in the process of tracking satellites. Early stages is themethod Elevation-Azimuth, where at this stage with input from GPS, Digital Compass, and the position of satellites(both coordinates, and height) that are stored in microcontroller. Controller will calculate the elevation and azimuthangle, then move the antenna according to the antenna azimuth and elevation angle. Next stages is correction modem,where in this stage controller only use modem as the input, and antenna movement is set up to obtain the largest valueof Eb/No signal. From the results of the controller operation, there is a change in the value of the original input levelfrom -81.7 dB to -30.2 dB with end of Eb/No value, reaching 5.7 dB.Keywords: azimut, controller, digital compass, elevasi, GPS, microcontroller, modem, rotary encoder, UAR
DETEKTOR ML UNTUK KOMUNIKASI ANTENA JAMAK
Get PDFSimple ML Detector for Multiple Antennas Communication System. In order to support providing broadbandwireless communication services against limited and expensive frequency bandwidth, we have to develop a bandwidthefficient system. Therefore, in this paper we propose a closed-loop MIMO (Multiple-Input-Multiple-Output) systemusing ML (Maximum Likelihood) detector to optimize capacity and to increase system performance. What is especiallyexciting about the benefits offered by MIMO is that a high capacity and performance can be attained without additionalfrequency-spectral resource. The grand scenario of this concept is the attained advantages of transformation matriceshaving capability to allocate transmitted signals power suit to the channel. Furthermore, product of these matrices formsparallel singular channels. Due to zero inter-channels correlation, thus we can design ML detector to increase thesystem performance. Finally, computer simulations validates that at 0 dB SNR our system can reach optimal capacityup to 1 bps/Hz and SER up to 0.2 higher than opened-loop MIMO.Keywords: fading, MIMO, SVD, M
KINERJA SKEMA PEMBERIAN TANDA AIR VIDEO DIJITAL BERBASIS DWT-SVD DENGAN DETEKTOR SEMI-BLIND
Get PDFOn the Performance of SVD-DWT Based Digital Video Watermarking Technique with Semi-Blind Detector.This paper presents a watermarking technique for digital video. The proposed scheme is developed based on the workof Ganic and Chan which took the virtue of SVD and DWT. While the previous works of Chan has the blind detectorproperty, our attempt is to develop a scheme with semi-blind detector, by using the merit of the DWT-SDV techniqueproposed by Ganic which was originally applied to still image. Overall, our experimental results show that our proposedscheme has a very good imperceptibility and is reasonably robust especially under several attacks such as compression,blurring, cropping, and sharpening.Keywords: discrete-wavelet-transform, imperceptibility, robustness, singular-value-decomposition, watermarkin
HYDROGEN ABSORPTION IN WELDMENTS OF OVERLAID CLADED PRESSURE VESSEL
Get PDFCracks was found in type 347 stainless steel internal attachment welds of a reactor for a high temperature, and highpressure hydrogen service. One of the possible causes of cracking is low cycle fatigue cracking induced by repetition ofthermal stress to embrittled weld metal. Type 347 weld metal loses its ductility by presence of sigma phase andhydrogen.Keywords: desulfurization, hydrogen embrittlement, hydrocracking, martensitic, weldmen
AUDIT SARANA PRASARANA PENCEGAHAN PENANGGULANGAN DAN TANGGAP DARURAT KEBAKARAN DI GEDUNG FAKULTAS X UNIVERSITAS INDONESIA TAHUN 2006
Get PDFBuilding Fire Safety Audit at Faculty X, University of Indonesia, Year 2006. Fire may cause loss of life, material and valuable assets. The objective of this study is to conduct audit for fire safety and emergency response in the building at Faculty X, University of Indonesia, Depok. The audit results on the building fire safety facilities including emergency response and preparedness are then compared to the Building Code Australia (BCA) and Indonesian regulation on the building fire safety (Kep.MenPU.No 10 and 11/KPTS/2000). The building selected are Building A, B, C, D, F and G. Building classification for A, B, D, F and G are classified as Class 5, while Building C is classified as Class 9b. Variable which are evaluated including emergency exit, building structure, fire alarm and detector, communication and fire warning system, evacuation procedure, portable fire extinguishers, hydrant, sprinkler, and emergency response preparedness. Results suggested that emergency exit is locked, and this is not comply to the regulation. Building structure has been complied to the regulation since it was made of concrete. Fire detector and alarm only provided in Building G, while other building is not available. There is no evacuation procedure available. Portable fire extinguisher has been available in all the building. Hydrant an sprinkler only available in building G. There is no emergency response preparedness in this faculty. In conclusion, the fire safety facilities in this faculty need to be improved.Keywords: fire safety audit, building fire safety, emergency response plannin
Stress Corrosion Cracking Behavior of Stainless Steel 304 in the Sulfuric Acid Environment Due to Prestrain
Get PDFTheaim of research is to investigate the effect of prestrain on the stress corossion cracking behavior of AISI 304 stainless steel in the sulfuric acid of 10% concentration under the static cantilever loading according to ASTM E-1681 standart. The specimen of 304 Stainless steel was strain up over the yield strength until reaching the uniform strain of 5% and 10% using servopulser UTM 9506 under the displacement control of 0,3 mm/sec. The results of test show that the prestrain of 5% specimen is faster failure than both of the prestrain of 10% and unprestrain specimen. It was caused by both of the decrease of ductility and the short incubation period. The change of deflection could be only recorded under the loading 20% of yield strength. Intergranular crack was the prestrain of 10% specimen under the static loading of 616 MPa. Whereas, for the prestrain of 10% specimen transgranular crack was found under the static loading of 554,4 MPa. The prestrain of 5% specimen was mixed crack under the static loading of 369.6 MPa. Higher dislocation density on the layer surface due to plastic deformation with increasing the percentage of pre-strain, so more difficult hydrogen diffused into the crack tip. Consequently, The incubation period can be prolonged.Keywords: stress corrosion cracking, incubation period, prestrain, trans-inter granular crackin
ALAT PENURUN EMISI GAS BUANG PADA MOTOR, MOBIL, MOTOR TEMPEL DAN MESIN PEMBAKARAN TAK BERGERAK
Get PDFEmission gas reducer on motor vehicle, automobile, light engine of boat and stationary combustion engine. The use of motor vehicle should be followed by protection against damages on the environment, since the exhaust gas from combustion engine has significantly affect on air and environmental pollution. One method to solve the problems in air pollution has been done by using a re-heater designed in Mechanical Engineering Department, University of Udayana. In accordance to the test on the re-heater, it can be seen very clear that the re-heater has significantly reduce the CO emission of about 54%. It also reduces the CO2 dan HC emission, and in the other side increases the number of O2. The re-heater has no significant effect to engine performance during the operation and also reduces the noise of motor.Keywords: emission gas reducer, moto