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INDONESIA
BERKALA FISIKA
Published by Universitas Diponegoro
ISSN : -     EISSN : -     DOI : -
Core Subject : Science,
Physics
BERKALA FISIKA adalah jurnal saintifik yang diterbitkan secara periodik 3 bulanan. Jurnal ini memuat kajian-kajian Fisika baik kajian teoretik maupun hasil eksperimen. Jurnal ini juga memberi ruang yang luas bagi kajian – kajian aplikasi fisika dalam bidang teknologi, ilmu-ilmu hayati dan kedokteran.
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Articles 5 Documents
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Search results for , issue "Vol 15, No 3 (2012): Berkala Fisika" : 5 Documents clear
PEMBUATAN KOMPOSIT SERAT SERABUT KELAPA DAN RESIN FENOL FORMADEHIDE SEBAGAI MATERIAL PEREDAM AKUSTIK Kartikaratri, Yohana Maya; Subagio, Agus; Widyandari, Hendri
BERKALA FISIKA Vol 15, No 3 (2012): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

The sound pollution due to noise is a one clasical problem in Indonesia. Theloudness can be reduced using the accoustic absorber. The composites of coconut fiberhas potential application as an environmental friendly accoustic absorber which is usingan agriculture waste. We reported the preparation of composite of coconut fiber as amatrix material and fenol formaldehide served as binder (coconut fiber/FF composite).The  immersion of coconut fibers  in the NaOH solution of 2% for 4 hours were caried outpriorly for improving the strengthness.The absorption coefficient (α) of the preparedcoconut fiber/FF composite was observed using two microphone impedance tube method(ISO 10534 – 2 dan ASTM E1050 – 08.   The value of tested absorption coefficient (α) allof composites samples have fulfilled the requirement. Requirement of acoustic absorbervalue of α is more than 0,15; and all of composites samples fulfilled the requirement onfrequency 752 Hz - 6400Hz.  Keyword : absorption coefficient, acoustic absorber, composite, coconut fiber, fenolformaldehid.
MODEL ARIMA UNTUK PREDIKSI CURAH HUJAN STUDI KASUS SEMARANG JATENG A Rofik, Muchammad; Gernowo, Rahmat; Setyawan, Agus; Nursamsiah, Nursamsiah
BERKALA FISIKA Vol 15, No 3 (2012): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

Modeling and prediction of rainfall in 2010 in Central Java BMKG Climatological Station has been done with ARIMA approach. The goal is to determine the historical pattern of the dataand then extrapolates this pattern into the future based on the assumption of continuity. Rainfalldata of 2000-2009 is a time series that can be predicted into the future using ARIMA. In thisstudy using two approaches for prediction of rainfall in 2010. The results were correlated with aprediction of rainfall data observed in 2010. Obtained a correlation of 71.1% and 75.48%.Keywords: ARIMA, rainfall, predictions, models
IDENTIFIKASI ALIRAN AIR INJEKSI DI LAPANGAN TALANG JIMAR REGION SUMATRA MENGGUNAKAN METODE SPONTANEOUS POTENTIAL Fithria I D, Ni'matul; Setyawan, Agus; Yulianto, Tony
BERKALA FISIKA Vol 15, No 3 (2012): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

Spontaneous-potential observation using amplitude potential method had been done beneathTalang Jimar area. The purpose of observation are to determine the distribution and depth of fluidinjection. Spontaneous-potential which has been corrected then processed using excel and surfer 9 toknow the distibution of its spread, while for the clarified of the deph we used spherical model. Thespontaneous-potential result shows ranging from -40 mV up to 10 mV with direction towards thereference block and a depth of 244,93 meters show.Keywords : Spontaneous‐potential, fluid injection, Talang Jimar, spherical model.
PENENTUAN CT DOSE INDEX (CTDI) UNTUK VARIASI SLICE THICKNESS DENGAN PROGRAM DOSXYZNRC Andriani, Intan; Anam, Choirul; Setiawati, Evi
BERKALA FISIKA Vol 15, No 3 (2012): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

The calculation of CT dose and CTDI has been done by using DOSXYZnrc software. Two kinds of phantoms have been used, i.e air and PMMA phantoms. The volume of phantoms 16 x 16x 16 cm3. The simulation carried out at 120 kV and the particles source 106. The calculation ofdose at the mid of phantom at the z axis, every voxel 0,2 x 0,2 x 0.2 mm3. The  variation of slicethickness were 5 mm, 10 mm, 15 mm and 20 mm. The dosages at every point then were plotted tofind out dose profile, and then were integrated to find out the CTDI. It was obtained that the peakvalue  on the air phantom has a higher value than the PMMA phantom. In the air phantom at theslice thickness of 5 mm, 10 mm, 15 mm and 20 mm were 68.28%, 80.49%, 90.91%, 99.86%. Whilein PMMA were 63.68%, 77.42%, 89.32%, 100%. At the penumbral region, it was obtained thatdosage at the PMAA phantom has a higher than the air phantom. CTDI from the PMAA phantomwas 212.50% and the air phantom was 184%. It was obtained that CTDI independent of slicethickness at the range 5-20 cm.Keywords: DOSXYZnrc, Slice thickness, CTDI
  AN IMPROVEMENT OF NEW TEST METHOD FOR DETERMINATION OF VEGETABLE OIL QUALITY BASED ON ELECTROOPTICS PARAMETER Firdausi, K Sofjan; Triyana, Kuwat; Susan, Ade Ika
BERKALA FISIKA Vol 15, No 3 (2012): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

An improvement of measurement for determination of frying oil quality has been conducted based on electrooptics parameter. The samples were several palm oils, coconuts oil, arefine olive oil, and a corn oil. The measured electrooptics parameter was the change of light polarizationθ through the samples within an external electric field, which leads to the increase oftransmitted lightζ, obtained by tabulating θ via Malus’ Law. The electric field was produced by high DC voltage power supply 0-10 kV on two parallel plates in a separated distance of circa 1 cm. The sources of light were red diode laser 5 mW (λ=650 nm), green diode laser 5 mW (λ=532 nm), He-Ne laser 1 mW (λ=633 nm), and a 100W-ligth bulb. For palm oils, the average value Δζwas approximately between 3×10-4 and 8×10-4. For coconuts oil and corn oil, Δζ was in the rangevalue of palm oils. However for refine olive oilΔζ was the smallest, out of the range and indicated minimum amount of free radicals. The electrooptics parameter here could classify various types offrying oils, distinguish between fresh oils and used oils, and also distinguish between edible oilsand expired oils.  This method could be an alternative quality test of frying oils. It conductedwithout additional treatments, relative simple, and quite accurate.Keywords: electrooptics, frying oil, polarization, transmitted light

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