MAKARA Journal of Technology
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LIMITING MAXIMUM DRAG REDUCTION ASYMPTOTE FOR THE MOMENT COEFFICIENT OF AN ENCLOSED ROTATING DISK WITH FINE SPIRAL GROOVES
Get PDFIn this study, the limiting maximum drag reduction asymptote for the moment coefficient of an enclosed rotating diskwith fine spiral grooves in turbulent flow region were obtained analytically. Analysis which were based on anassumption for a simple parabolic velocity distribution of turbulent pipe flow to represent relative tangential velocity,was carried out using momentum integral equations of the boundary layer. For a certain K- parameter the momentcoefficient results agree well with experimental results for maximum drag reduction in an enclosed rotating disk withfine spiral grooves and drag reduction ratio approximately was 15 %. Additionally, the experimental results for dragreduction on a rotating disk can be explained well with the analytical results.Keywords: drag reduction, boundary layer, enclosed rotating disk, friction momen
PREPARASI KARAKTERISTIK BIODIESEL DARI MINYAK KELAPA SAWIT
Get PDFBiodiesel's characteristics preparation from palm oil. Using vegetable oils directly as an alternative diesel fuel has presented engine problems. The problems have been attributed to high viscosity of vegetable oil that causes the poor atomization of fuel in the injector system and pruduces uncomplete combustion. Therefore, it is necessary to convert the vegetable oil into ester (metil ester) by tranesterification process to decrease its viscosity. In this research has made biodiesel by reaction of palm oil and methanol using lye (NaOH) as catalyst with operation conditions: constant temperature at 60 oC in atmosferic pressure, palm oil : methanol volume ratio = 5 : 1, amount of NaOH used as catalyst = 3.5 gr, 4.5 gr, 5 gr and 5.5 gr and it takes about one hour time reaction. The ester (metil ester) produced are separated from glycerin and washed until it takes normal pH (6-7) where more amount of catalyst used will decrease the ester (biodiesel) produced. The results show that biodiesels' properties made by using 3.5 (M3.5) gr, 4.5 gr (M4.5) and 5 (M5.0) gr catalyst close to industrial diesel oil and the other (M5.5) closes to automotive diesel oil, while blending diesel oil with 20 % biodiesel (B20) is able to improve the diesel engine performances.Keywords: Palm oil, catalyst NaOH, transesterification, biodiese
PENGARUH KANDUNGAN Ca PADA CaO-ZEOLIT TERHADAP KEMAMPUAN ADSORPSI NITROGEN
Get PDFIn industry, Ca zeolite is used as nitrogen selective adsorbent with the use of PSA (Pressure Swing Adsorption)/VSA (Vacuum Swing Adsorption) methods. Natural zeolite modified to be Cao-zeolite by ion exchange process using Ca(OH)2. Adsorption test was done on CaO-zeolite with different Ca concentration to understand how it's adsorption phenomena on oxygen and nitrogen. Adsorption test has been done for CaO-zeolite with Ca concentration = 0,682%, 0,849% and 1,244% to oxygen and nitrogen with equal concentration seperately. Pressure variation has being done three times (5 minutes long each time) adsorption time to analyze the connection between adsorption time and how many moles of nitrogen and oxygen being adsorbed. Adsorption test showed that there is a limit of Ca concentration to make CaO-zeolite more selective to adsorb nitrogen. CaO-zeolite with Ca concentration . 1,125% adsorb nitrogen more selective than oxygen. Because the nitrogen content in air is four times the oxygen so we can conclude that the air adsorption rate by zeolite will be four times the adsorption rate by oxygen. This differences in adsorption rate will make the use for CaO-zeolite as a oxygen enrichment equipment possible.Keywords: CaO-zeolite, adsorption, limit, adsorption rate, nitroge
PEMETAAN EKOSISTEM DI WILAYAH GUNUNG BROMO DENGAN TEKNOLOGI PENGINDERAAN JAUH
Get PDFMapping of Ecosystems in Mount Bromo Using Remote Sensing Technology. Covered land analyses of Landsatimage have been done to get ecosystem types and map in Mount Bromo region using remote sensing technology. Thereare nine types of ecosystems in Mount Bromo region, i.e. primary forest, secondary forest, lake, crater, sands,uncovered land, underbrush, dry-field and residence. Distribution of rock analysis has also been done by comparing themanual image interpretation with geological map. The results were coorelated with the digital image interpretation tofind rock distribution map which can be useful to get the information about water reservation potencial in Mount Bromoregion. The coorelation results together with slope, covered vegetation and rain falls can give description about absolutewater reservation and buffer zone map in Mount Bromo region.Keywords: Mapping, water reservation, buffer zone, remote sensing technolog
PERANAN KATALIS K3-xHxPW12O40 PADA KATALISIS SELEKTIF SINTESIS METILAMINA DARI METANOL DAN AMONIAK
Get PDFRole of K3-xHxPW12O40 as a Catalyst in Selective Catalysis of Methylamine Synthesis from Ammonia andMethanol. Synthesize of methylamine from methanol and ammonia was studied in this research work using a partiallypotassium heteropoly salt (K3-xHxPW12O40 abbreviated as KPW) as a catalyst. KPW was prepared from heteropoly saltand potassium carbonate by using ion exchange method. The reaction was conducted at 600 ~ 800K and at theatmospheric pressure. Reactor used was a continue flow reactor with W/F=0,1~0,9g-kat.mnt./cc.Concentration ofreactants and products were analyzed by gas chromathography while catalyst structure was observed by XRD (X-raydiffraction). Isothermal adsorption method was used for determining catalyst pore size. The result showed that ionexchange between H ion in zeolit with K ion produced potassium heteropoly salt that caused the change of interstitialspace. The change of interstitial space was observed by the change of the lattice constant of the catalyst crystal.Trimethylamine(TMA) has molecule size smaller than catalyst pore size but bigger than molecular size ofDimethylamine (DMA) and Monimethylamine (MMA). This phenomenon caused the suppression of TMA formation.KPW has a rigid crystal structure and stabil during reaction. On the other hand, crystal structure of a non selectivecatalyst (NH4)3PW12O40 was not rigid and its pore size is easy to change depending on the product molecule size.Keywords : methylamina, shape selective, heteropoly aci
ANALISIS PERFORMANSI RADIO BASE STATION (RBS) FLEXI DI BASE STATION CON TROL (BSC) KOTA 2 JAKARTA BARAT UNTUK TRAFIK SUARA DAN DATA
Get PDFFlexi Radio Base Station (RBS) Performance Analysis of Voice and Trafic on Kota 2 Jakarta Barat Base StationControl (BSC). The CDMA 2000 technology uses circuit switch method to handle voice traffic and packet switchmethod to handle data traffic between the user and RBS (Radio Base Station). These two parameters can be used tomeasure performance of the network generally, so it is necessary to optimize them. This paper analyze the performanceof RBS by measuring its parameters such as set up failure ratio, drop ratio, and occupancy. Furthermore, the trafficincrement is calculated too in order to provide information for improvement in the future. Through the analysis, it isrealized that a way to improve configuring it uniquely based on its area of scope. Some RBS need soon, but some othersdon't. Beside of that, it is also known that the voice communication effectively while data communication roughly.Keywords: CDMA, RB
DESAIN DAN REALISASI STEPPED FREQUENCY GPR 1-2 GHZ UNTUK APLIKASI DETEKSI LOGAM DALAM TANAH
Get PDFDesign and Implementation of 1-2 GHz Stepped Frequency GPR for Buried Metal Detection. In this paper, wedescribe the design and realization steps of 1 - 2 GHz SFGPR (Stepped Frequency Ground Penetrating Radar)transceiver for metal detection under the ground. Before using prototyped GPR for detecting the metal under theground, several of calibration processes must be performed, namely phase calibration and monocycle pulse waveformcalibration. After completing the calibrations, this prototyped GPR would be ready for detecting a hidden object such asa metal plate 5 cm under the ground in our small test range size 25 cm x 75 cm x 10 cm. From the calibration anddetection results, we concluded that the prototyped SFGPR passed the technical specifications of the design and couldperform the metal detection under the ground with high SNR.Keywords: stepped frequency, GPR, metal detector, phase and monocylce calibration
PENGEMBANGAN PROBE SENSOR KELEMBABAN SERAT OPTIK DENGAN CLADDING GELATIN
Get PDFDevelopment of Fiber-Optic Humidity Sensor Probe with Gelatin Cladding. Humidity sensor based on optical fiberwith gelatin cladding has been developed. In this humidity sensor probe, the origin cladding of optical fiber is replacedby gelatin coating as humidity sensitive cladding. Testing of the optical fiber sensor probe was conducted by measuringof light intensity transmitted on the optical fiber probe for each variation of different humidity treatments. Response ofthe optical fiber sensor probe measured from 42%RH to 99%RH, the results show an optical transmission curve variedwith relative humidity (RH). Optical transmission in the optical fiber probe increase with RH value at a specificwavelength range, that is from green to red spectrum bands (500 nm - 700 nm), where a significant variation from 600nm to 650 nm in yellow to red spectrum bands. Wavelength where is a maximum intensity of optical transmissionoccurs at 610 nm. Therefore, the optical fiber humidity sensor probe could response humidity form 42%RH to 99%RHwith the best response in humidity range of 60%RH to 72%RH that is have a good linearity and sensitivity.Keywords: humidity sensor, fiber-optic sensor, gelatin, swellin
