Journal of Mathematical and Fundamental Sciences
ISSN : 23375760     EISSN : 23385510
Journal of Mathematical and Fundamental Sciences welcomes full research articles in the area of Mathematics and Natural Sciences from the following subject areas: Astronomy, Chemistry, Earth Sciences (Geodesy, Geology, Geophysics, Oceanography, Meteorology), Life Sciences (Agriculture, Biochemistry, Biology, Health, Medical, Pharmacy), Mathematics, Physics, and Statistics.
Articles 547 Documents
PQL: Operasi Komposisi dan Jaringan Semantik Data

Sitohang, Benhard ( Laboratorium Basis Data, Departemen Teknik Informatika, ITB, Jl. Ganeca No.10, Bandung 40132 )

Journal of Mathematical and Fundamental Sciences Vol 33, No 2 (2001)
Publisher : ITB Journal Publisher, LPPM ITB

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Abstract

Sari. Public Query Language (PQL) adalah bahaas penelusuran (query) pada basis data model relasi, yang lebih bersifat user friendly relative terhadap bahasa penelusuran pada Generasi ke-IV (SQL, QBE, QUEL, dll). Dari sisi struktur bahasa, PQL didasarkan pada struktur sintaks linier (tidak terdapat struktur blok rekursif). Pada sisi tampilan, hasil eksekusi dibentuk berdasarkan definisi entitas (bukan tuppel, seperti pada SQL). Dengan demikian duplikasi data pada tampilan dapat dihilangkan. Proses query dan prinsip tampilan yang dimaksudkan pada PQL dapat diimplementasikan dalam DBMS, dengan menerapkan teknik penggabungan (operator komposisi), yang didasarkan pada prinsip operator join dan navigasi pada jaringan semantik data. Operator komposisi dan jaringan semantik data adalah topik utama penelitian yang dijelaskan pada tulisan ini. PQL: Composition Operator and Semantic Data NetworkAbstract. Public Query Language (PQL) is the syntax of query for relational database, which is categorized as highly user friendly compared to the 4-th generation language (SQL, QBE, QUEL,etc.). As a query language, PQL is constructed as linear syntax (without block recursive). Visualization of the result is constructed as an entity (not tupple, as happened in SQL). As a consequence, duplication of data on the results could be rejected. Query process and the principle of visualization of result of PQL can be adapted as part of DBMS, using composition method  (Composition Operator), developed as an interpretation of join operator and navigation, supported by Data Semantic Network. Both Composition Operator and Data Semantic Network are main topic discussed in this article, as the result of this research on PQL.

Penutupan dengan Asbes Dapat Memperbaiki Sifat Mekanik dari Sambungan Baja dengan Las Busur Listrik

Trisno, Trisno ( Balai Penelitian Bahan-Bahan, Bandung ) , Sulaiman, A. ( Lembaga Metallurgi Nasional, Bandung ) , Wirjosumarto, H. ( Departemen Mesin, Institut Teknologi Bandung )

Journal of Mathematical and Fundamental Sciences Vol 11, No 3 (1978)
Publisher : ITB Journal Publisher, LPPM ITB

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Abstract

Ringkasan. Sifat-sifat mekanik yang penting dari sambungan las adalah kekuatan dan keuletan. Kedua sifat ini dapat diuji dengan pengujian tarik, pengujian takik dan pengujian kekerasan. Kedua sifat utama tersebut sangat tergantung dari perlakuan lanjut yang dikenakan pada sambungan yang dimaksud. Di dalam penelitian ini dibandingkan pengaruh dari tiga perlakuan lanjut terhadap kedua sifat mekanik tersebut di atas pada sambungan las baja dengan busur listrik. Ketiga perlakuan lanjut yang dimaksud adalah: (a) tanpa perlakuan apa-apa, (b) dipanaskan dalam tungku pada temperature 650’C selama setengah jam dan diikuti dengan pendinginan di dalam tungu dan (c) ditutup dengan asbes segera setelah selesai pengelasan lapisan las yang terakhir. Hasil penelitian menunjukkan bahwa penutupan dengan asbes menghasilkan sifat-sifat mekanik yang lebih baik dari pada pengelasan yang tidak diikuti dengan perlakuan apa-apa, walaupun belum menyamai hasil dari pengelasan yang mendapat perlakuan lanjut dengan pemanasan di dalam tungku. Abstract. The important mechanical properties in welding technology are strength and ductility of the welded joint. These two properties can be examined through tensile testing, impact testing and hardness testing. It has been known that those two properties are influenced by the post treatment imposed to the welded joint. In this work, those properties were studied on electric arc welded joints of steel plates which have undergone three different post treatments. The three treatments are: (a) without post treatment,  (b) heated in the furnace at 650° C for half an hour followed by furnace cooling and (c) covering the weld with asbest immediately after the last pass of welding process. Results of the study shows that covering the weld with asbests produces better mechanical properties than that without treatment, eventhough  it is still inferior compared to the one which has been heated in the furnace. Due to the incomplexity and uncostly of the asbest-covered post treatment, it is necessary to study further the development of this treatment process for practical use.

Gerak Photon dalam Medan Gravitasi jang Kuat disekitar Bintang jang Mampat.

Sutantyo, Winardi ( Observatorium Bosscha, I.T.B. )

Journal of Mathematical and Fundamental Sciences Vol 6, No 2 (1971)
Publisher : ITB Journal Publisher, LPPM ITB

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Abstract

Ringkasan. Dalam tulisan ini, review mengenai gerak photon dalam medan gravitasi jang kuat diberikan. Photon jang dipantjarkan dari sekitar atau dalamnja sebuah bintang jang sangat mampat dapat lepas, djatuh kembali, atau bergerak dalam orbit lingkaran, bergantung pada arah mula2 dari ketjepatan photon. Abstract. In this paper, a review of the motion of photons in a strong gravitational field is given. Photon which are emitted from the neighborhood or from within a superdense star, may escape, falling or moving in a circular orbit, depending on the initial direction of the photons. 

The Role of Equatorial Oceanic Waves in the Activation of the 2006 Indian Ocean Dipole

Iskandar, Iskhaq ( 1Jurusan Fisika, Fakultas MIPA, Universitas Sriwijaya Kampus Inderalaya, Jln. Raya Palembang-Prabumulih Km. 32 Indralaya, Ogan Ilir, Sumatra Selatan 30662, Indonesia 2Pusat Study Geohazard dan Perubahan Iklim, Fakultas MIPA, Universitas Sriwijaya, J )

Journal of Mathematical and Fundamental Sciences Vol 44, No 2 (2012)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Original Source | Check in Google Scholar | Full PDF (428.045 KB) | DOI: 10.5614/itbj.sci.2012.44.2.2

Abstract

Observations and a linear wave model were used to evaluate the role of equatorial oceanic wave processes in affecting the evolution of the 2006 positive Indian Ocean Dipole (IOD), focusing on the activation phase of the event. The observations indicate the presence of upwelling equatorial waves and westward near-surface zonal currents along the equator during the activation phase of the event in August 2006. These upwelling equatorial waves (negative sea surface height anomalies) and westward zonal current anomalies contributed to significant sea surface cooling in the eastern equatorial Indian Ocean. The model results reveal that the upwelling equatorial waves and westward nearsurface zonal currents were mainly generated by wind-forced Kelvin waves associated with the easterly wind anomalies. On the other hand, anomalous easterly winds along the equator during June caused downwelling waves (positive sea surface height anomalies) in the off-equatorial region which propagated westward and elevated sea levels in the western region. The model further shows that a complex interplay of wind-forced and boundary-generated Rossby waves elevated sea levels in the western equatorial Indian Ocean during the activations phase of the 2006 IOD event.

Penurunan Zat Organik dan Kekeruhan Menggunakan Teknologi Membran Ultrafiltrasi dengan Sistem Aliran Dead-End (Studi Kasus : Waduk Saguling, Padalarang)

Notodarmojo, Suprihanto ( Departemen Teknik Lingkungan ITB, Fakultas Teknik Sipil dan Perencanaan Jl. Ganesha No. 10 Bandung – 40132 ) , Deniva, Anne ( Departemen Teknik Lingkungan ITB, Fakultas Teknik Sipil dan Perencanaan Jl. Ganesha No. 10 Bandung – 40132 )

Journal of Mathematical and Fundamental Sciences Vol 36, No 1 (2004)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Original Source | Check in Google Scholar | Full PDF (1142.764 KB) | DOI: 10.5614/itbj.sci.2004.36.1.5

Abstract

A laboratory scale experiment to study the aplicability of ultrafiltration membrane technology to treat the water of Saguling Reservoir has been done. The main parameters in this study are flux, organic content, and turbidity. The membranes used are cellulose accetate based membrane, composed of 11, 13, 15 percent cellulose accetate respectively. Chemical analysis of Saguling Reservoir water shows that, color, organic content, and turbidity are the parameters exceeding the standard. In this study, treated water by using Poly Alummunium Chloride (PAC) as feeding solution was also been used. The results shows that CA-15, membrane has 15 % content of cellulose accetate, performed best. The permeability of the membrane was 5-12 l/m2.hr.bar, and rejects up to 90 % of organic content, 90-100% rejection of Total Suspended Solid and 90% turbidity.

Kajian Biodegradasi Limbah Cair Industri Biodiesel pada Kondisi Anaerob dan Aerob

Syafila, Mindriany ( Fakultas Teknik Sipil dan Lingkungan, Program Magister Teknik Lingkungan Institut Teknologi Bandung, Jl. Ganesa No. 10 Bandung-40132 ) , Setiadi, Tjandra ( Fakultas Teknologi Industri, Program Magister Teknik Kimia Institut Teknologi Bandung, Jl. Ganesa No. 10 Bandung-40132 ) , Mulyadi, Abdul Haris, Esmiralda, ESMIRALDA

Journal of Mathematical and Fundamental Sciences Vol 39, No 1-2 (2007)
Publisher : ITB Journal Publisher, LPPM ITB

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Abstract

Penelitian ini bertujuan untuk menangani limbah yang terjadi dari industri biodiesel. Air limbah yang dihasilkan dari industri biodiesel diperkirakan memiliki kandungan organik yang cukup tinggi. dengan demikian perlu dipertimbangkan untuk mengolahnya dengan proses anaerob, sehingga berpotensi untuk mendapatkan produk samping berupa biogas (gas metana). Namun demikian, proses aerob sebagai kelanjutan degradasi secara anaerob harus pula ditinjau, karena masih adanya kandungan organik yang tersisa setelah proses anaerob. Hasil penelitian menunjukkan bahwa efisiensi proses anaerob masih kecil yang ditunjukkan oleh hasil uji Biochemical Methane Potential (BMP) yang hanya sekitar 30%, akan tetapi dari uji Anaerobic Toxicity Assay (ATA) tampak bahwa limbah cair tidak menghambat pertumbuhan mikroorganisme metanogen. Kinerja proses aerob juga belum menunjukkan hasil yang maksimal, karena efisiensi biodegradasi baru sekitar 75-80%. Hal ini karena proses aerob seharusnya ditujukan untuk mengolah lebih lanjut efluen proses anaerob.

Seismic Velocity Structures beneath the Guntur Volcano Complex, West Java, Derived from Simultaneous Tomographic Inversion and Hypocenter Relocation

Nugraha, Andri Dian ( Global Geophysical Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, ) , Widiyantoro, Sri ( Global Geophysical Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, ) , Gunawan, Awan ( Graduate Program of Earth Science, Faculty of Earth Science and Technology, Institut Teknologi Bandung ) , Suantika, Gede ( Center for Volcanology and Geological Hazard Mitigation (CVGHM) )

Journal of Mathematical and Fundamental Sciences Vol 45, No 1 (2013)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Original Source | Check in Google Scholar | Full PDF (1676.032 KB) | DOI: 10.5614/j.math.fund.sci.2013.45.1.2

Abstract

We conducted travel time tomographic inversion to image seismic velocity structures (Vp, Vs, and Vp/Vs ratio) with simultaneous hypocenter adjustment beneath the Guntur volcano complex that is located in the Garut district, West Java province, Indonesia. The Guntur volcano is one of the active volcanoes in Indonesia, although large eruptions have not occurred for about 160 years. We used volcanic and tectonic earthquakes catalog data from seismic stations deployed by Centre for Volcanology and Geological Hazard Mitigation (CVGHM). For the tomographic inversion procedure, we set grid nodes with a horizontal spacing of 2 x 2 km2 and an average vertical spacing of 2 km. Our results show low Vp, low Vs, and high Vp/Vs ratio regions beneath the Guntur crater and the Gandapura caldera at depths of 6-8 km and 7-9 km, respectively. These features can be associated with amelt-filled pore rock structure. However, a low Vp/Vs ratio and low velocities are exhibited beneath the Kamojang caldera at depths of 2-6 km that may be associated with rock with H2O-filled pores with a high aspect ratio.

Detecting Rice Phenology in Paddy Fields with Complex Cropping Pattern Using Time Series MODIS Data

Sari, Dewi Kania ( 1 Study Program of Geodesy & Geomatics, Faculty of Earth Science & Technology, ITB Jl. Ganesha 10, Bandung 40132 Indonesia. E-mail: dewiks@yahoo.com 2 Department of Geodetic Engineering, Institute of Technology Nasional (Itenas) Jl. P.H.H. Mustafa 2 ) , Ismullah, Ishak H. ( 1 Study Program of Geodesy & Geomatics, Faculty of Earth Science & Technology, ITB Jl. Ganesha 10, Bandung 40132 Indonesia. ) , Sulasdi, Widyo N. ( Study Program of Geodesy & Geomatics, Faculty of Earth Science & Technology, ITB Jl. Ganesha 10, Bandung 40132 Indonesia. ) , Harto, Agung B. ( Study Program of Geodesy & Geomatics, Faculty of Earth Science & Technology, ITB Jl. Ganesha 10, Bandung 40132 Indonesia. )

Journal of Mathematical and Fundamental Sciences Vol 42, No 2 (2010)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Original Source | Check in Google Scholar | Full PDF (613.299 KB) | DOI: 10.5614/itbj.sci.2010.42.2.2

Abstract

Monitoring paddy rice phenology and cropping schedules over wide areas is essential for many applications. Remote sensing provides a viable means to meet the requirement of improved regional-scale data set of paddy rice fields, such as phenological stages. A number of methods have been developed for detecting seasonal vegetation changes by using satellite images. Development of such methods to paddy fields with complex cropping pattern is still challenging. In this study, we developed a method for remotely determining phenological stages of paddy rice that uses time series of two vegetation indices (EVI and LSWI) obtained from MODIS data. We ran the algorithm to determine the planting date, heading date, and harvesting date of paddy rice in 5 districts of West Java Province, using the 8-day composite MODIS Surface Reflectance products (500-m spatial resolution) in 2004. Estimated harvesting dates were then used to calculate paddy rice harvested area. We validated the performance of the method against statistical data in 13 subdistricts. The root mean square errors of the estimated paddy rice harvested area against the statistical data were: 851 Ha for monthly data, 1227 Ha for quarterly data, and 2433 Ha for yearly data. Subdistrict-level comparisons of paddy rice harvested area between the MODIS estimation and statistical data showed moderate correlation, with coefficient of determination (r2) 0.6, 0.7, and 0.6 for monthly, quarterly and yearly data, respectively. The results of this study indicated that the MODIS-based paddy rice phenological detection algorithm could potentially be applied at large spatial scales to monitor paddy rice agriculture on a timely and frequent basis.

Source Processes of the March 2007 Singkarak Earthquakes Inferred from Teleseismic Data

Afnimar, A. ( Seismological Laboratory, Bandung Institute of Technology ) , Kobayashi, Reiji ( Graduate School of Science and Engineering, Kagoshima University ) , Natawidjaja, Danny Hilman ( Research Center of Geotechnology, Indonesian Institute of Sciences (LIPI) )

Journal of Mathematical and Fundamental Sciences Vol 46, No 2 (2014)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Original Source | Check in Google Scholar | Full PDF (1514.964 KB) | DOI: 10.5614/j.math.fund.sci.2014.46.2.4

Abstract

The rupture processes of two sequentialearthquakes have been inverted from teleseismic data. The first event released a total seismic moment of 7.9×1018 Nm (Mw 6.5) and the slip distribution shows three asperities, 1.5 m at the shallowside, 0.7 m at the rightsouth-east deep side and 0.5 m atthe north-west deep side. The second event had one asperity with 1.7 m slip and released a seismic moment of 7.5×1018 Nm (Mw 6.5). In both cases, maximum slip occurred above the hypocenter which was responsible for the surface displacement pattern.

Surfaces with Prescribed Nodes and Minimum Energy Integral of Fractional Order

Gunawan, H. ( Analysis and Geometry Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Bandung, Indonesia. ) , Rusyaman, E. ( Department of Mathematics, Padjajaran University, Bandung, Indonesia. ) , Ambarwati, L. ( Department of Mathematics, State University of Jakarta, Jakarta, Indonesia )

Journal of Mathematical and Fundamental Sciences Vol 43, No 3 (2011)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Original Source | Check in Google Scholar | Full PDF (501.841 KB) | DOI: 10.5614/itbj.sci.2011.43.3.6

Abstract

This paper presents a method of finding a continuous, real-valued, function of two variables z = u(x, y) defined on the square S := [0,1]2 , which minimizes an energy integral of fractional order, subject to the condition u(0, y) = u(1, y) = u(x,0) = u(x,1) = 0 and u(xi ,yj)=c𝑖𝑗 , where 0<x1<...<xM,<1, 0<y1<...<yN<1, and c𝑖𝑗 ∈ ℝ are given. The function is expressed as a double Fourier sine series, and an iterative procedure to obtain the function will be presented.

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