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All Journal Jurnal Pendidikan IPA Indonesia Jurnal Spektra Makara Journal of Science
B. Kurniawan
Department of Physics, University of Indonesia, Depok 16424, Indonesia
Education Physics

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KAJIAN PEROVSKITE LA0,73CA0,27MN1-XCUXO3 DENGAN 0 Gunanto, Y. E.; Sinaga, K.; Purwanto, A.; Kurniawan, B.; Poertadji, S.; Steven, E.; Brooks, J. S.
Jurnal Spektra Vol 15, No 1 (2014): Spektra: Jurnal Fisika dan Aplikasinya
Publisher : Jurnal Spektra

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Abstract

We have performed the synthesis and characterization of materials La0.73Ca0.27Mn1-xCuxO3 for 0 <x< 0.19 using  neutron scattering diffraction (HRPD) and SQUID.All the samples are already in phase with the crystal structure  orthorombic and space group P nma. Parameters of the Mn-O bond length obtained from the charactyerization HRPD. From  the parameters of Mn-O bond length can be determined the value of Jahn-Teller distortion. The greater x will result in an  average radius of position B (<rB>) increasing and the tolerance factor t decreasing. From the characterization of the SQUID  was found that the maximum value of conductivity for Cu-doped samples will be lower when compare to the sample without  doping, except for Cu=0.10. If the value of the conductivity is getting smaller, the activation energy will be higher. Keywords: Jahn-Teller distortion, factor tolerance, conductivity, activation energy
MAGNETORESISTANCE in La0.1Ca0.9MnO3 Gunarto, Y.E.; Kurniawan, B.; Poertadji, S.; Steven, E.
Jurnal Spektra Vol 16, No 2 (2015): Spektra: Jurnal Fisika dan Aplikasinya
Publisher : Jurnal Spektra

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AbstractWe have performed measurements of resistivity as a function of temperature with a certain large external magnetic field and resistivity as a function of the external magnetic field in room temperature conditions for L0.1C0.9MnO3 compound. Measurement of resistivity as a function of temperature using quantum squid design is done at a temperature of 8-80 K with an external magnetic field variation of 0, 3, 6, and 8.5 Tesla. The resistivity measurements as a function of the external magnetic field from 0 to 0.7600 Tesla performed at room temperature using a four-point probe. At the same temperature, the greater the external magnetic field, the greater its magnetoresistance. For the same external magnetic field, increasing the temperature will decrease magnetoreistance.Keywords: external magnetic field, squid quantum, magnetoresistance AbstrakTelah kami lakukan pengukuran terhadap resistiviti sebagai fungsi suhu dengan besar medan magnet luar tertentu dan juga resistiviti sebagai fungsi medan magnet luar dalam kondisi suhu ruang untuk senyawa L0,1C0,9MnO3. Pengukuran resistivitas sebagai fungsi suhu menggunakan squid quantum desain dilakukan pada suhu 8-80 K dengan variasi medan magnet luar 0, 3, 6, dan 8,5 Tesla. Pengukuran resistivitas sebagai fungsi medan magnet luar dari 0-0,7600 Tesla dilakukan pada suhu ruang. Pada suhu yang sama, semakin besar medan magnet luar, maka semakin besar magnetoresistansi nya. Untuk medan magnet luar yang sama, semakin bertambah suhunya maka magnetoreistansi akan semakin berkurang.Katakunci: medan magnet luar, squid quantum, magnetoresistansi 
Markov Analysis of Water Discharge as an Indicator of Surface Water Security of the Bandung Basin Wulandari, S.; Sabar, A.; Setiadi, T.; Kurniawan, B.
Jurnal Pendidikan IPA Indonesia Vol 10, No 4 (2021): December 2021
Publisher : Program Studi Pendidikan IPA Fakultas Matematika dan Ilmu Pengetahuan Alam (FMIPA)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jpii.v10i4.28974

Abstract

Water security is the fulfillment of access to adequate and sustainable water needs (quantity and quality) for the growth of human and ecosystem life and the ability to reduce risks associated with water. By knowing the water security of an area, efforts to conserve, utilize, control destructive force, develop information systems and participate in the community can be assessed to what extent and how the management has been carried out. The purpose of this research is to formulate the amount of water availability per capita (quantity) of surface water and to determine the quantity of the worst water quality at a critical time (the worst quantity) to be used as a reference in determining the amount of water resistance for development. The only observed water quality was the BOD (Biological Oxygen Demand) organic pollutant value in the dry year in the dry season using the Markov Chain Method. Water security in the Bandung Basin is currently classified as bad (rare) because the water availability index figures only indicate 174 m3 per capita per year (quantity). Meanwhile, data on the quality value of BOD (Biological Oxygen Demand) pollutants in dry years (R5) of 129 mg/l and very dry years (R10) of 112 mg/l which has also exceeded the class I quality standard of PP No. 22/2021 ( 2 mg/l) regarding water quality management and pollution control which is designated for raw water needs drinking water. Changing water use patterns and promoting effective implementation of integrated water resources management are essential strategies for increasing water security in Indonesia.
REFLECTION INFLUENCE ON OUTPUT FREQUENCY SPECTRUM AT SUBMILLIMETER FREQUENCY TUNABLE GYROTRONS Aripin, Aripin; Kurniawan, B.
Makara Journal of Science Vol. 6, No. 3
Publisher : UI Scholars Hub

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Influence of output window reflections on oscillatory processes in gyrotrons has been studied. The processes in a gyrotron have been modeled numerically, and enhancement of the spectrum signal in the presence of reflections has been studied. Dependencies of output power versus time and frequency spectrum for different value of reflection coefficient are given. Possibilities of significant increasing of output spectrum are demonstrated experimentally. The results demonstrate significant influence of reflections on operation stability and composition of the output radiation of the gyrotron.
REFLECTION INFLUENCE ON OUTPUT FREQUENCY SPECTRUM AT SUBMILLIMETER FREQUENCY TUNABLE GYROTRONS Aripin, Aripin; Kurniawan, B.
Makara Journal of Science Vol. 6, No. 3
Publisher : UI Scholars Hub

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Abstract

Influence of output window reflections on oscillatory processes in gyrotrons has been studied. The processes in a gyrotron have been modeled numerically, and enhancement of the spectrum signal in the presence of reflections has been studied. Dependencies of output power versus time and frequency spectrum for different value of reflection coefficient are given. Possibilities of significant increasing of output spectrum are demonstrated experimentally. The results demonstrate significant influence of reflections on operation stability and composition of the output radiation of the gyrotron.
Co-Authors A. Purwanto Aripin E. Steven, E. J. S. Brooks, J. S. K. Sinaga, K. S. Poertadji S. Wulandari, S. Sabar, A. T. Setiadi, T. Y. E. Gunanto Y.E. Gunarto, Y.E.