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TWO-DIMENSIONAL DYNAMICS OF SPHERICAL GRAIN FLOATING ON THE PROPAGATING WAVE FLUID SURFACE

Viridi, Sparisoma, Nurhayati, Nurhayati, Sabaryati, Johri, Muliyati, Dewi

Spektra: Jurnal Fisika dan Aplikasinya Vol 3 No 3 (2018): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 3 Issue 3, December 2018
Publisher : Program Studi Fisika Universitas Negeri Jakarta

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Abstract

  Abstract Simulation of a spherical grain floating in fluid surface propagating sinusoidal wave is performed using molecular dynamics method by assuming that superposition of buoyant, gravitational, and viscous forces will make the grain to move in two-dimension. It is different than previous result, where the grain can only move in one-dimension since size of the grain Db << λf. In this work Db < λf so that direction of buoyant force must be considered. It is predicted theoretically that the two-dimensional motion tends to be a one-dimensional motion when Db/λ less than a certain value, but it remains as a two-dimensional motion when more than that value. In 20 s of observation frequency of the sinusoidal wave can determine whether the grain will move in the same direction of the travelling wave or not. Keywords: grains, simulation, buoyant force, gravitational force, viscous force.

IMAGING OF 3-D SEISMIC TOMOGRAPHY FOR INTERNAL STRUCTURE UNDER THE MOUNTAIN MERAPI USING THE LOTOS-10 SOFTWARE

Sari, Ayu Wita, Suparta, Gede Bayu

Spektra: Jurnal Fisika dan Aplikasinya Vol 3 No 2 (2018): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 3 Issue 2, August 2018
Publisher : Program Studi Fisika Universitas Negeri Jakarta

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Abstract

Abstrak Telah dilakukan penelitian pencitraan tomografi seismik 3D untuk stuktur internal di bawah Gunung Merapi dengan empat stasiun pencatat gempa dan gempa vulkanik sebagai sumber sinar gelombang. Penelitian ini menggunakan perangkat LOTOS-10 (Local Tomography Software 10) untuk inversi tomografi seismik 3D. Karakteristik medium bawah Gunung Merapi dapat digambarkan oleh parameter fisis seperti kecepatan gelombang primer dan sekunder. Hasil pengolahan data seismograf menunjukkan metoda tomografi seismik dapat mengungkap struktur bawah permukaan Gunung Merapi melalui distribusi anomali deviasi kecepatan dan Vp/Vs ratio. Kualitas citra yang dihasilkan dengan menggunakan gelombang primer lebih jelas resolusinya dan waktu yang digunakan lebih efesien, sehingga dapat digunakan sebagai informasi mitigasi bencana sebelum gempa erupsi terjadi. Daerah anomali negatif yang diperoleh terletak di bawah puncak Gunung Merapi pada kedalaman 3 - 5 km mempunyai karakter fisis yaitu zona lemah, kurang kompak, panas dan heterogen. Daerah anomali tersebut dapat diinterpretasikan sebagai keberadaan zona materi panas yang berasosiasi dengan sisa dapur magma dangkal. Kata-kata kunci: Gunung api Merapi, sifat fisis, tomografi seismic, lotos-10. Abstract 3D seismic tomography imaging research conducted for internal structures under Merapi Volcano with four earthquake recording and volcanic earthquake stations as a source of wave rays. This study used LOTOS-10 (Local Tomography Software 10) for 3D seismic tomography inversion. Characteristics of the medium under Merapi Volcano described by physical parameters such as primary and secondary wave velocities. The result of seismograph data processing shows seismic tomography method can reveal the subsurface structure of the Merapi Volcano through the distribution of deviation anomaly speed and Vp / Vs ratio. Image quality generated by using primary wave more clearly the resolution and time used more efficient, so that can be used as disaster mitigation information before earthquake eruption happened. The negative anomaly area obtained under the peak of Merapi Volcano at a depth of 3 - 5 km has the physical characteristics of weak, less compact, hot and heterogeneous zones. The anomalous region can interpret as the existence of a zone of heat material associated with the rest of the shallow magma kitchen. Keywords: Mount of Merapi, physical character, Seismic of Tomography, lotos-10.

FABRICATION AND CHARACTERIZATION OF THE COMPOSITES OF RESIN – HUSK OF RICE AND RESIN - RUB ASH

Pattersons, Muhammad Lawrence, Naripa, Arin, Winarno, Sendiko Janu, Abhan, Siti Mawaddah, Sanjaya, Edi

Spektra: Jurnal Fisika dan Aplikasinya Vol 3 No 2 (2018): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 3 Issue 2, August 2018
Publisher : Program Studi Fisika Universitas Negeri Jakarta

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Abstract

We have done the fabrication of two kinds of composite material the fillers that we used rub ash for one type of composite and the husk of rice for another, the matrix for both is resin. The resin – rub ash composite, the volume ratio of filler and matrix is 1:1, while in the resin – husk of rice composite we used three volume ratios, those are 1:1, 1:2, and 2:1. After the process of fabrication was done, we did TGA test and three points flexural test for every composite we fabricated. The results of TGA test show that the most significant weight decrease of resin – rub ash composite occurred at 390,29 ºC, while the resin – rub ash composites most considerable weight decrease occurred at 399,86 ºC. The results of three points flexural test show that elasticity of resin – rub ash composite is 4,97 x 109 N/m2, while elasticity modulus of all kinds of the resin – husk of rice composite is in order of 108 N.m2 and 106 N/m2. Overall, we can conclude that the resin – husk of rice composite is more heatproof and more elastic than the resin – rub ash composite. Keywords: composite, resin, rub ash, the husk of rice.

UV-VISIBLE OPTICAL ABSORBANCE OF GRAPHENE OXIDE IN COPPER IONIC LIQUID SYNTHESIZED VIA ELECTROCHEMICAL METHOD ASSISTED BY A COPPER COIL

Dwandaru, Wipsar Sunu Brams, Priyani, Oktiana Lusi, Prakoso, Bagas, Wisnuwijaya, Rhyko Irawan, Santoso, Iman

Spektra: Jurnal Fisika dan Aplikasinya Vol 3 No 2 (2018): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 3 Issue 2, August 2018
Publisher : Program Studi Fisika Universitas Negeri Jakarta

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Abstract

An optical absorbance study using Ultraviolet-Visible (UV-Vis) spectrophotometer device has been conducted on graphene oxide (GO) in copper (Cu) ionic liquid using electrochemical exfoliation combined with a direct current (DC) electrical circuit of copper coil given inside the electrolyte solution. The electrolyte solutions used are sulfuric acid (H2SO4) and chloride acid (HCl). The UV-Vis spectrum of the samples shows absorbance peaks at around 214 nm to 218 nm and shouldering peaks around 245 nm to 249 nm. The first peak corresponds to the existence of copper (Cu) ionic liquid in the solution, whereas the shouldering peak is related to the occurrence of GO material. A comparison between UV-Vis spectral of graphite in dimethylformamide (DMF) and GO in Cu ionic liquid in DMF resulted in the existence of a blue shift which signifies the production of Cu ionic liquid from the Cu coils inside the electrolyte solution. Increasing the concentration of the solution increases the absorbance peaks. Furthermore, raising the number of loops yields in the increase of the absorbance value at the first peaks that show Cu ionic liquid, but tends to decrease the absorbance value of the shouldering peaks of the GO material.

FLOW UNITS DETERMINATION USING FLOW ZONE INDICATOR FOR CARBONATE RESERVOIR

Haris, Abdul, Riyanto, Agus, Harsanto, Tri Aji Adi, Rachmanto, Ambar, Sukmatiawa, Adang

Spektra: Jurnal Fisika dan Aplikasinya Vol 3 No 2 (2018): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 3 Issue 2, August 2018
Publisher : Program Studi Fisika Universitas Negeri Jakarta

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Abstract

In the last few years, the use of flow unit technique in the oil and gas industry has shown a great deal of success. Porosity and permeability from wire-line log and special core data analysis (SCAL) along with its cementation exponent value were integrated to characterize the reservoir in terms of pore volume caused by facies changing. In this work, we determine flow unit of the carbonate reservoir, which is applied to the Northwest Java Basin Field, Indonesia by performing the flow unit analysis, which allows approximating absolute permeability. Furthermore, the quantity and the flow unit of the reservoir rock is also determined to identify the secondary porosity. To reduce the level of uncertainty, wire-line logs data were validated with core data before it is used to interpret the reservoir. Subsequently, the result can be extrapolated to un-cored wells. Our experiment shows that flow units can be determined reliably from the integration between porosity and permeability, which have defined two different rock types in term of flow unit zone. The correlation of the flow units between wells leads to the definition of reservoir quality.

ANALOG COMPUTER FOR STUDYING DIATOMIC MOLECULAR SPECTRA IN TERAHERTZ FREQUENCY

Malik, Usman, Hamdi, Muhamad, Salomo, Salomo

Spektra: Jurnal Fisika dan Aplikasinya Vol 3 No 2 (2018): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 3 Issue 2, August 2018
Publisher : Program Studi Fisika Universitas Negeri Jakarta

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Abstract

This paper introduces a harmonic oscillator model for rovibronic terahertz spectrum of a model of a rigid diatomic rotor with some control parameters. The model shows a study of rotationally-resolved terahertz band spectra of the vibrational transition in diatomic molecules. THz radiation absorption is used as a closed-form system known as the analog computer dynamics mode. The optical terahertz region spectrum of the diatomic molecule consists of a series of lines. Their separations are not exactly constant. A diatomic molecule is not truly a rigid rotator, because it simultaneously vibrates with a small amplitude. Due to quantized vibrational and rotational energy levels and the selection rules, allowed transitions result in a highly ordered spectrum consisting of a P branch separated by a central gap. Adjacent spectral lines are separated by a spacing of 2B, and since line intensities depend on Boltzmann factor for thermal population and quantum number J, each branch monotonically increases and decreases. As temperature increases, more lines are observed, and line intensities decrease due to the population being spread over more rotational levels. Interactivity research also involves on effects of the fundamental vibrational frequency, rotational constant B and temperature included line width on the observed spectrum.

TWO STATIC FLUID DARK MATTER MODEL WITH ADDITIONAL COSMOLOGICAL CONSTANT

Supriyadi, Izrul, Sawitar, Widya, Budi, Esmar, Fahdiran, Riser

Spektra: Jurnal Fisika dan Aplikasinya Vol 3 No 2 (2018): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 3 Issue 2, August 2018
Publisher : Program Studi Fisika Universitas Negeri Jakarta

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Abstract

Abstrak Pada persamaan medan gravitasi Einstein terdapat konstanta kosmologi sebagai konstanta alam yang menjelaskan model mengembangnya alam semesta dan yang paling dominan terdapat di jagad raya ini adalah dalam bentuk energi gelap (dark energy). Kami meninjau model objek dua fluida tidak terkopel, seperti layaknya materi gelap (dark matter) atau bintang yang memiliki karakteristik tensor energi-momentum dan kecepatan-4 nya yang berbeda serta bersifat anisotropik, kemudian disatukan sebagai model dua fluida untuk ditinjau persamaan TOV (Tolman-Oppenheimer-Volkoff) dan persamaan geodesiknya dalam menunjukkan sifat gerak dan model dua fluida tersebut. Hasil perhitungan menunjukkan bahwa model ini dapat menjelaskan persamaan potensial efektif dengan tambahan konstanta kosmologi sebagai karakteristik gerak dan kecepatan tangensial partikel uji dalam orbit lingkaran stabil. Kata-kata kunci: konstanta kosmologi, anisotropik, potensial efektif, kecepatan tangensial. Abstract In Einsteins gravitational field equation has been found the cosmological constant as the natural constant that describes the universes expansion model and the most dominant in the universe is the dark energy form. We review the two objects of fluid models are not coupled, like dark matter or stars which has the different characteristic energy-momentum tensor and four velocities and anisotropic tend, then combined as two-fluid models for TOV (Tolman-Oppenheimer-Volkoff) equation and the geodesic equation to characterize the movement and the two fluid models. The calculation result shows that this model can explain the potential equation with an addition of an effective cosmological constant as the movement characteristic and tangential velocity of a tested particle in a stable circular orbit. Keywords: cosmological constant, anisotropic, effective potential, tangential velocity.

OPTICAL PROPERTIES ANALYSES OF CHLOROPHYLL OF LEAF EXTRACT BY UV-VIS SPECTROMETER AS PRE-STUDY OF DYE SENSITIZER

Dianisya, Dona, Silmina, Amalia Dini, Purwanto, Novan, Isnaeni, Isnaeni, Sugihartono, Iwan

Spektra: Jurnal Fisika dan Aplikasinya Vol 3 No 2 (2018): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 3 Issue 2, August 2018
Publisher : Program Studi Fisika Universitas Negeri Jakarta

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Abstract

ABSTRAK Telah dilakukan studi ekstraksi awal klorofil dari 3 jenis daun yaitu daun bayam (Amarantus), daun pepaya (Carica papaya), dan daun jarak (Ricinus communis). Ekstraksi dilakukan dengan teknik penghancuran menggunakan blender. Pelarut yang digunakan adalah isopropanol, asam asetat, dan DI water. Hasil penyaringan ekstrak daun diperoleh larutan sebayak 75 ml untuk setiap larutan ekstrak klorofil. Uji Ultrasonic Visible memberikan konfirmasi adanya penyerapan di rentang cahaya ultraviolet dan cahaya tampak. Sementara itu, serapan klorofil teramati di rentang cahaya tampak. Apabila dibandingkan serapan UV dan cahaya tampak, pada larutan ekstrak masih mengandung banyak gugus asam dibandingkan klorofil yang di ekstrak. Kata-kata kunci: daun bayam, daun pepaya, daun jarak, absorbansi, klorofil ABSTRACT We studied for chlorophyll extract from 3 leaf types that are spinach leaf (Amarantus), papaya leaf (Carica papaya), and castor leaf (Ricinus communis). The extraction is done by using a blender. The solvents used are isopropanol, acetic acid, and DI water. The result of leaf extract was obtained 75 ml solution for each solution of chlorophyll extract. The Visible Ultrasonic Test confirms absorption in the range of ultraviolet light and visible light. Meanwhile, chlorophyll uptake is observed in the visible light spectrum. When compared to UV absorption and visible light, in the extract solution still contains a lot of acid groups than the chlorophyll extracted. Keywords: spinach leaf, papaya leaf, Castor leaf, absorbance, chlorophyll.

ANALISIS PROKSIMAT PADA BRIKET ARANG LIMBAH PERTANIAN

Rumiyanti, Leni, Irnanda, Annisa, Hendronursito, Yusup

Spektra: Jurnal Fisika dan Aplikasinya Vol 3 No 1 (2018): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 3 Issue 1, April 2018
Publisher : Program Studi Fisika Universitas Negeri Jakarta

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Abstract

AbstrakTelah dilakukan penelitian yang bertujuan untuk mengetahui kualitas briket arang terbaik dan terburuk dari limbah pertanian berdasarkan kandungan proksimatnya. Limbah pertanian yang digunakan adalah sekam padi, ampas tebu, kulit singkong, tongkol jagung, dan batok kelapa. Metode penelitian yang digunakan adalah karbonisasi pirolisis pada suhu 700-800 oC selama 45 menit dan dianalisis proksimat dengan teknik yang sesuai Standar Nasional Indonesia (SNI) untuk pengujian kadar air lembab, abu, zat terbang, dan karbon tertambat. Hasil penelitian menunjukkan bahwa kualitas briket arang terbaik adalah kulit singkong karena memiliki kadar air dan abu terendah, yaitu 0,3833% dan 0,8452%. Sementara, kualitas briket arang terburuk adalah tongkol jagung karena memiliki kadar air tertinggi yaitu 2,412 % dan karbon tertambat terendah yaitu 71,442 %. Kata kunci: briket arang, limbah pertanian, analisis proksimat. AbstractResearch has been conducted to know the best and worst quality of charcoal briquettes from agricultural wastes based on their proximate content. These agrarian wastes are rice husk, sugarcane baggage, cassava peel, corncob, and coconut shell. The research method is pyrolysis carbonization at 700-800 oC for 45 min and proximate analysis with techniques that suitable Indonesian National Standard (SNI) for testing of moisture, ash, volatile matter, and fixed carbon content. The research result showed that the best charcoal briquettes quality is cassava peel because it has the lowest water content of 0.3833% and the lowest ash content of 0.8452%. While the worst charcoal briquettes quality is corncob because it has the highest water content of 2,412% and the lowest fixed carbon of 71,442%.Keywords: charcoal briquettes, agricultural wastes, proximate analysis.

GREENESS ANALYSIS OF FOREST IN MINING AREA OF SAWAHLUNTO USING NDVI METHOD BASED ON LANDSAT IMAGERIES IN 2006-2016

Cahyono, Bowo Eko, Frahma, Yazella Feni, Nugroho, Agung Tjahjo

Spektra: Jurnal Fisika dan Aplikasinya Vol 3 No 1 (2018): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 3 Issue 1, April 2018
Publisher : Program Studi Fisika Universitas Negeri Jakarta

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Abstract

Abstrak Pembukaan lahan hutan yang dijadikan lokasi pertambangan merupakan salah satu kegiatan yang dapat merubah jenis tutupan lahan atau sering disebut dengan konversi lahan. Salah satu daerah yang telah mengalami konversi lahan tersebut adalah Sawahlunto. Konversi lahan yang tidak menggunakan prinsip kelestarian lingkungan dapat mengakibatkan banyak hal negatif misalnya degradasi atau penurunan kualitas hutan. Tujuan dari penelitian ini adalah melakukan analisis tingkat degradasi hutan daerah pertambangan Sawahlunto tahun 2006 sampai 2016. Penelitian ini menggunakan teknologi penginderaan jauh berbasis citra satelit landsat. Citra satelit landsat ini diklasifikasikan dengan metode Normalized Difference Vegetation Index (NDVI) berdasarkan kerapatan vegetasi. Kemudian hasil klasifikasi ini dibuat dalam bentuk pemetaan. Klasifikasi pertama dikategorikan menjadi dua yakni hutan dan non hutan. Hasil yang didapatkan dari penelitian ini menunjukkan bahwa terjadi perubahan tutupan lahan yang semula hutan menjadi non hutan meningkat sebesar 7,5% selama kurun waktu sepuluh tahun. Klasifikasi selanjutnya yakni berdasarkan enam kategori yakni vegetasi sangat rapat, rapat, cukup rapat, non vegetasi 1, 2 dan 3. Dari klasifikasi ini, juga terlihat perubahan nilai NDVI maksimum maupun minimumnya. Tahun 2006 memiliki kisaran nilai NDVI maksimum 0,71 dan tahun 2016 memiliki kisaran nilai NDVI maksimum 0,56. Hal ini mengidentifikasi bahwa tingkat kehijauan yang ada di daerah pertambangan Sawahlunto menurun. Kata Kunci : degradasi, hutan, landsat, ndvi, klasifikasi, Sawahlunto.  Abstract The clearing of forest land that is used as a mining site is one of the activities that can change the type of land cover or often called land conversion. One of the forest areas that convert the land is Sawahlunto. Conversion of land that does not use the principles of environmental sustainability can lead to many negative things one of which is the degradation. The purpose of this research is to analyze the level of forest degradation of Sawahlunto mining area in 2006 until 2016. This research uses a remote sen sing technology based on landsat satellite imagery. This landsat satellite image is classified by Normalized Difference Vegetation Index (NDVI) method based on vegetation density. Then the results of this classification is made in the form of mapping. The first classification is categorized into two namely forest and non forest. The results obtained from this study indicate that a change in land cover from forest to non-forest increased by 7.5% over a period of ten years. The next classification is based on six categories namely very dense vegetation, dense vegetation, fairly dense, non vegetation 1, 2 and 3. From this classification, also seen the change in NDVI maximum and minimum value. The year 2006 has a maximum NDVI value range of 0.71 and 2016 has a maximum NDVI value range of 0.56. This identifies that the existing greenness in the mining area of Sawahlunto is decreasing.  Keyword : degradation, forest, landsat, ndvi, classification, Sawahlunto.