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BERKALA FISIKA
Published by Universitas Diponegoro
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Core Subject : Science,
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 301 Documents
PENINGKATAN SIFAT MAGNETIK MATERIAL HEMATIT MELALUI SUBTITUSI BARIUM DAN KONTROL TEMPERATUR SINTERING Widanarto, Wahyu; Fauzi, Fuzi Nurrahman; Cahyanto, Wahyu Tri; Effendi, Mukhtar
BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 4 Tahun 2015
Publisher : BERKALA FISIKA

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Abstract

Ferrite magnet or ceramic magnet is a competitive product in the magnet market due to low price, corrosion resistant and chemically stable. Barium hexa-ferrite magnet is one of ferrite magnet which is mostly used as magnetic storage and electronic devices based on nanotechnology. Barium hexa- ferrites are synthetized through solid state reaction method at sintering temperatures of 1100 °C with the composition (100-x)Fe2O3 : xBaCO3 , where x = 0 and 20 in mol % . Results of XRD characterization show that the diffraction peaks of XRD spectrum is dominated by the peaks of barium ferrite crystal with a hexagonal crystal system. Magnetic properties of Fe2O3 material doped with barium carbonate of 20 mol % and sintered at 1100 °C increase significantly compared to the others. This simple and inexpensive method is very promising for the manufacture of barium hexa-ferrite materials with natural ferrite as the main material.Keywords: Iron sand, barium ferrite, structure, magnetic properties
EVALUASI KUALITAS BEBERAPA JENIS MINYAK GORENG KEMASAN SETELAH DIPANASKAN MENGGUNAKAN SIFAT ELEKTROOPTIS Murni, Sri; Bawono Putranto, Ari; Hidayanto, Eko; Firdausi, K Sofjan
BERKALA FISIKA Vol 16, No 3 (2013): Berkala Fisika
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Abstract

In this report, we have determined the average value of polarization angle for various edible oils, before and after heating. The change of polarization angle was measured averagebetween potential differences 0-9 kV. The heating time for the samples was conducted up to 10 hours at average temperature by 180°C. The source of light was He-Ne Laser 1 mW (633 nm) with optical length of samples of 1 cm. In agreement to the previous experiment, our result shows that all vegetable oils provide increasing of free radicals indicated by increasing polarizationangle for longer heating time. For the heating time interval 0-10 hours, the level degradation ofoil rises quadratically. From various edible oils, olive oil is still the relative best quality from allsamples in this experiment. This method, once again, shows more powerful relative to otherstandard methods.Keywords: frying oil, electrooptics, polarization angle
RANCANG BANGUN SISTEM PENGUKUR KONSENTRASI LARUTAN TEMBAGA SULFAT (CUSO4) MENGGUNAKAN KOMPUTER Sumariyah, Sumariyah; Endro Suseno, Jatmiko; L, Fitria
BERKALA FISIKA Vol 10, No 3 (2007): Berkala Fisika
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Abstract

A system  of    Sulphate Copper (CuSO4) liquid consentration measurement by using compute has been made. The display of it through monitor in the computer with the limitation of measurement  0.1 M to 1M. The main components of the measure system of   Sulphate Copper (CuSO4) liquid consentration are : tungsten filamen light which include in the sample and photodioda light sensor also IC 741 as a Operational Amplyfier to strengthen the tension of sensor output. As the chage of the output analog signal power tobe digital signal ADC 0809 is used. And also as an interfce which is the pheripheral instrument of communication equipment with computer is used PPI 8255. The software on  this measure system uses Turbo Pascal version 7.0. This system had been realized and can measure the Sulphate Copper (CuSO4) liquid consentration wich the linier regresion equal is , with X hole is the sample consentration (M) and Y hole is the measure result of the concentration (M) and the deviation is 0.0326.
PERANCANGAN DAN PEMBUATAN SENSOR TDS PADA PROSES PENGENDAPAN CACO3 DALAM AIR DENGAN METODE PELUCUTAN ELEKTRON DAN MEDAN MAGNET Martani, Maylita; Endarko, Endarko
BERKALA FISIKA 2014: Berkala Fisika Vol. 17 No. 3 Tahun 2014
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Abstract

Total Dissolved Solids (TDS) meter has successfully been fabricated based on the principle of conductivity. Control system for monitoring the TDS level in the mini plant have been performed by microcontroller ATMega16 and Personal Computer. The study was to control a precipitation process of CaC03 in the water. Values of TDS from water sample in the mini plant have been monitored and controlled in real-time. All data have been recorded by microcontroller and then, the data will be sent to personal computer via USB interface. Monitoring data will be displayed in a computer screen. The result showed that the system could be used to control level of TDS at 356 - 300 ppm. Keywords : gravity of CaC03, Conduktivity, Control
SOLUSI NUMERIK MODEL DINAMIK PERLAKUAN IMMUNOTHERAPY PADA INFEKSI HIV-1 Kartono, Agus; Rosidah, Rosidah; Arif, Ardian
BERKALA FISIKA Vol 13, No 1 (2010): Berkala Fisika
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Abstract

There are several types of treatment options that can slow the progression of HIV that can be offered if the number of CD4 + cells has been known for certain, one treatment is by immunotherapy with interleukin-2 (IL-2). This type of treatment is to increase the immune system that can help the body fight against the infection itself. Efforts to raise an immune response would be appropriate to reduce the amount of virus. This brings new hope for treatment of HIV infection and the type of treatment is being researched. Interleukin-2 (IL-2) is most of the cytokines which are proteins made by the body. T-helper cells, a type of white blood cells, produce IL-2 when they were stimulated by infection. In this study, a model of HIV disease progression than individuals not treated can be expressed in a mathematical model, and also expressed immunotherapy model to see the dynamics of viral populations and the population of CD4 + T cells from HIV disease based on ordinary differential equation (ODE). This study aims to calculate the numerical solution immunotherapy mathematical model in HIV infection and a mathematical model to predict the outcome of immunotherapy treatment strategies in HIV infection. Keywords: HIV, CD4 + T cells, immunotherapy, mathematical modeling
STUDY OF ELECTROOPTICS BEHAVIOUR OF NAPHTHALENE AND ANTHRACENE Firdausi, K Sofjan; Khumaeni, Ali; Richardina, Very; Arianto, Fajar; Budi, Wahyu Setia
BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 3 Tahun 2015
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Abstract

In this paper, we demonstrate electro-optics behaviour of naphthalene and anthracene using change of polarization of sample induced by external electric field. The source of light for polarization was 1 mW-he-ne Laser 633 nm. The induced external Electric field was produced by high DC voltage 0 ? 7 kV. The samples were diluted in solutions-form using wash-benzene. The result shows that anthracene has higher polarizability than naphthalene, which is indicated by higher change of polarization in anthracene than naphthalene. The Assumption that potential difference is proportional to the distance between molecules is shown qualitatively by graphs of Van der Waals potential energy or force between molecules. In this case, anthracene has higher level Energy than naphthalene so that it can be used in visible excitation for environmental spectroscopy. Keywords: electro-optics, polarization, naphthalene, anthracene, Van der Waals potential energy 
SISTEM PENGENALAN WAJAH DENGAN METODE EIGENFACE DAN JARINGAN SYARAF TIRUAN (JST) Mulyono, Tri; Adi, Kusworo; Gernowo, Rahmat
BERKALA FISIKA Vol 15, No 1 (2012): Berkala Fisika
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Abstract

The development of security systems led to the development of face recognition system using image processing techniques.Research was conducted to identify a face image automatically with theeigenface method. The method used is a normalization, eigenface, neural network training and testing.Eigenface is used to reduce the dimension vector face becomes much simpler (eigen vector). Eigen vectorsobtained are used by back propagation neural network training process and recognition. Then do thetesting process using the image of a face that has not been used in the training process.The results showed the use of neural networks and eigenface to face recognition can give a goodaccuracy. The system is able to produce an acuracy of 84.6% with a FAR (False Acceptance Rate) =16.2%, FRR (False Rejection Rate) = 20% and EER (Equal Error Rate) = 0.3.Keywords : face recognition, eigenface, eigen vector, neural network
RANCANG BANGUN SPEKTROSKOPI FTIR (FOURIER TRANSFORM INFRARED) UNTUK PENENTUAN KUALITAS SUSU SAPI Endro Suseno, Jatmiko; Firdausi, K. Sofjan
BERKALA FISIKA Vol 11, No 1 (2008): Berkala Fisika
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Abstract

A Fourier Transform Infrared spectroscopy instrument has beed developed in the range middle infrared. The important instrument in this research is to make interferogram using He-Ne Laser based on Michelson interferometer. The result indicates that the interferogram seems work well and should give some spectra in the range of middle infrared frequencies. Key words: FTIR, interferogram, spectroscopy
PEMBUATAN SOFTWARE MONITORING JUMLAH PRODUKSI KERUPUK MENGGUNAKAN BORLAND DELPHI 7.0 Adiyani C, Mirsari; Danusaputro, Hernowo
BERKALA FISIKA Vol 14, No 3 (2011): Berkala Fisika
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Abstract

The monitoring program for the crackers counter has been done by Borland Delphi 7.0. The results of this program is intended to help the manager?s job in monitorin the amount ofcracker produced by industry. This program using Borland Delphi 7.0. While to find out the cracker pieces which fellfrom the conveyor using photodiodes sencors and lasers as light sources directed at the sensorphotodiodes. When the sencor detected a cracker pieces which fell from the conveyor, the sensorsend a signal to the microcontroller for processing and then send to computer via serialcommunication. On computer, that data is received by Borland Delphi 7.0 program to displayedand stored in Microsoft Access. The system has been realized successfully and can printer the data stored in databases sothat the amountof crackers produced will be known.Keyword: Crackers, Borland Delphi 7.0, Microsoft Access, photodiodes sencors, lasers
PENENTUAN KOEFISIEN LINIER ELEKTRO OPTIS PADA AQUADES DAN AIR SULING MENGGUNAKAN GELOMBANG RF Jatwiyono, Lilik Eko; Sugito, Heri; Firdausi, K. Sofjan
BERKALA FISIKA Vol 10, No 4 (2007): Berkala Fisika
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Abstract

The coefficients of electrooptics for water and refinery water in RF field have been determined. The RF frequency range used in the research is 6,04 MHz to 11 MHz. Two different light beam (532 nm and 632,8 nm) have been used to measure the change of light polarization after transmitted the samples. The result indicates that the linear and quadratic electro optic coefficients appear in the range of frequency-field. The refinery water has greater value of linear electro optic coefficient than aquades. It is also obtained that the greatest change of polarization angle take place when using the green laser in the field?s position of upright against the RF frequency field and polarization angle of 900.   Keywords: RF field, polarization angle, linear electro optic coefficient.

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