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INDONESIA
Journal of Mathematical and Fundamental Sciences
Published by Institut Teknologi Bandung
ISSN : 23375760     EISSN : 23385510     DOI : https://doi.org/10.5614/j.math.fund.sci.
Core Subject : Science, Education,
Astronomy Chemistry Earth & Planetary Sciences Mathematics Physics
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.
Arjuna Subject : Matematika - Matematika (Lain-Lain)
Articles 689 Documents
 44   45   46   47   48 
Penerapan Sistem Tegangan Tinggi Arus Searah (TTAS) Guna Menyalurkan Daya dari Bukit Asam ke Jakarta Harsono Harsono
Journal of Mathematical and Fundamental Sciences Vol. 15 No. 3 (1982)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Sari. Teknologi sistem penyaluran daya listrik dengan menggunakan tegangan tinggi arus searah (TTAS) telah semakin dewasa. Hal tersebut dibuktikan dengan semakin banyaknya instalasi sistem tersebut. Salah satu kemungkinan untuk menerapkan sistem dimaksud di Indoensia, adalah dalam rangka menyalurkan energi listrik dari PLTU-PLTU yang dibangun di dekat daerah penambangan batubara Bukit Asam, Sumatera Selatan ke Jakarta. Untuk tahapan pembangunan yang menggunakan satuan kapasitas sebesar 800MW, disarankan untuk menggunakan 3 sistem TTAS bipolar dengan tegangan kerja ± 400 kV, guna keperluan menyalurkan daya sebesar 2400 MW pada keadaan akhirnya. Abstract. At this moment the technology of the high voltage direct current (HVDC) power transmission is readily available. It is proven by the already existing system and the under construction and/or planned ones. One possibility to apply that mentioned technology in Indonesia is for transporting the electric energy generates at bukit Asam (South Sumatera) area to fulfill the energy need in Jakarta. For implementing the above purpose this paper propose to use three 800 MW capacity transmission lines to transport the ultimate power of 2400 MW. Each transmission is a bipolar with an operating voltage of ±400 kV.
Computational Scheme for Geosynchronous Satellite Orbit due to Gravitation of the Earth Harijono Djojodiharjo; Yus Kadarusman
Journal of Mathematical and Fundamental Sciences Vol. 15 No. 3 (1982)
Publisher : Institute for Research and Community Services (LPPM) ITB

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By analyzing the influence of the earth's gravitational anomaly on the orbit of a satellite around the earth, a computational scheme for geosynchronous satellite orbit with small inclination is developed. The governing equations of motion, which consist of three equations and have been simplified to take into account geosynchronous conditions and small displacements, are solved by numerical technique. In particular the radius of geosynchronous orbit is obtained by solving the first governing equation by Regula-Falsi method. Stationary points are obtained by indirect method, i.e. by first finding the longitude positions with zero longitudinal accelerations. The trajectory of the subsatellite point is obtained by solving the governing equations for small displacement by Runge-Kutta method. Comparison of computational result with Blitzer's and Flury's using IAU 1968 and GEM-8 data, leads confidence to the present scheme.
Tes Sensitometri D-19 Moedji Raharto; B. Hidayat; Daryanto Daryono
Journal of Mathematical and Fundamental Sciences Vol. 15 No. 2 (1982)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Design Procedure for Optimal Multi–input Control System via Time-domain Technique R.J. Widodo
Journal of Mathematical and Fundamental Sciences Vol. 15 No. 2 (1982)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Abstract. Design procedures for Linear-optimal control systems with respect to a quadratic performance index are developed. Via a Time-domain Technique and based on the phase-variable canonical-system description, the optimal feedback vector k and the weighting matrix Q can be directly determined from the characteristic equations of the open and closed loop systems. Formerly the design procedures has been developed for single input systems, and then to be extended to multi-systems. PROSEDUR RANCANGAN UNTUK SISTEM-SISTEM KONTROL OPTIMAL DENGAN MASUKAN BANYAK MELALUI BIDANG WAKTUSari. Suatu prosedur rancangan untuk Sistem-sistem Kontrol Optimal Linier dengan indeks performans kwadrat telah dikembangkan. Berdasarkan deskripsi sistem perubah pada dan melalui bidang waktu, vector catubalik optimal k dan matrik pembobotan Q dapat ditentukan secara langsung dari persamaan-persamaan karakteristik sistem putaran terbuka dan putaran terutup. Semula prosedur rancangan dikembangkan untuk sistem-sistem masukan tunggal dan kemudian dilanjutkan untuk sistem-sistem masukan banyak.Mungkin nanti bila ybs sudah mengirimkan surat resmi saya kabari lagi Bapak. Saya sudah sampaikan hal ini ke Pa Ilik juga.
Nitrification in the Contact-Stabilization Process Wisjnuprapto Wisjnuprapto; S. Saipanich; B. Capdeville; H. Roques
Journal of Mathematical and Fundamental Sciences Vol. 15 No. 2 (1982)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Abstract. A series of experiment on the contact-stabilization process treating municipal waste water were conducted at various sludge ages. Sludge recycling rates, hydraulic retention times in contact-stabilization reactors, and at constant temperature. A kinetic model of nitrifiers growth rates in the contact reactor were developed based on the calculated values of the experimental results, as a function of sludge age and fractional biomass in the contact reactor. The influence of these parameters on the nitrification efficiency were observed during the experiments; the ammonia removal rate as a function of the VSS and ammonia nitrogen consumption by the microorganisms were determined experimentally.Sari. Telah dilakukan satu seri percobaan pengolahan air buangan kota dengan menggunakan proses kontak-stabilisasi pada berbagai variasi harga umur sludge, sludge recycling rate, waktu retensi di dalam reaktor kontak dan reaktor stabilisasi, pada temperatur konstan. Berdasarkan nilai yang diperhitungkan dari hasil percobaan, telah dicoba untuk mengembangkan sebuah model kinetik tentang kecepatan pertumbuhan bakteri nitrifikasi (nitrifier) di dalam reaktor kontak sebagai fungsi dari umur sludge dan fraksi biomas di dalam kontak reaktor. Selanjutnya, dalam percobaan ini juga diamati pengaruh parameter-parameter tersebut lerhadap efisiensi nitrifikasi. Dan dari hasil percobaan juga telah dihitung kecepatan penghilangan ammonia sebagai fungsi dari Volatile Suspended Solids yang terbentuk dan pemakaian nitrogenammonia oleh mikroorganisme.
The Influence of Stress and Strain on the Tempering of SAE 4340 Martensitic Steel Rochim Suratman
Journal of Mathematical and Fundamental Sciences Vol. 15 No. 1 (1982)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Abstract. An investigation into the influence of stress and/or strain on the tempering of SAE 4340 martensitic steel is being done. The as-quenched steel is tempered at several temperatures (100° - 600°C) with and without the influence of stress. The resulting changes in hardness and structure were then followed by microhardness measurements and electron microscopy. The primary variables of interest in this work are hardening conditions, tempering time, tempering temperature, stress, and strain during tempering. From the experimental result it appears that the hardness of steel SAE 4340 tempered under stress between 100°C and 300°C is higher than the hardness of the same steel tempered without stress, while the hardness of steel tempered under stress al a temperature higher than 300°C is lower than the hardness of steel tempered without stress. In all cases, at higher stresses the specimens undergo plastic deformation during tempering and it is seen that the plastic strain has more influence on the tempering than the stress. The electron microscopic observations show that the increase in hardness, due to the strain occuring during tempering, is caused mainly by a more abundant precipitation of carbides of about the same shape and size as in specimens tempered without stress. When the strain occuring during tempering causes a lower hardness, the carbide precipitations are coarser, more equlaxed and fewer than after tempering without stress. In all cases, at higher stresses the specimens undergo plastic deformation during tempering and it is seen that the plastic strain has more influence on the tempering than the stress. The electron microscopic observations show that the increase in hardness, due to the strain occurring during tempering, is caused mainly by a more abundant precipitation of carbides of about the same shape and size as in specimens tempered without stress. When the strain occurring during tempering causes a lower hardness, the carbide precipitations are coarser, more equiaxed and fewer than after tempering without stress. Pengaruh Tegangan dan/atau Regangan yang Diberikan pasa saat Menemper Baja Martensit SAE 4340Sari. Suatu penyelidikan mengenai pengaruh tegangan dan/atau regangan yang diberikan selama menemper baja martensit SAE 4340 terhadap proses penguraian martensit dan proses presipitasi. Hasil-hasil percobaan menunjukkan bahwa kekerasan baja SAE 4340, setelah distemper pada suhu antara 100°C dan 300°C di bawah pengaruh tegangan, lebih keras dibandingkan dengan kekerasannya setelah distemper tanpa pengaruh tegangan. Setelah distemper di bawah pengaruh tegangan pada suhu yang lebih tinggi dari 300°C, kekerasan dari semua baja yang diamati menjadi lebih rendah dibandingkan dengan kekerasannya setelah distemper tanpa pengaruh tegangan. Dari hasil pengamatan dengan bantuan mikroskopelektron, ternyata bahwa penyebab dari bertambah kerasnya kekerasan baja setelah ditemper di bawah pengaruh tegangan, adalah adanya presipitat-presipitat yang jauh lebih banyak jumlahnya dibandingkan dengan jumlah presipitat-presipitat yang ada setelah ditemper tanpa pengaruh tegangan; sedangkan penyebab dari berkurangnya kekerasan baja setelah ditemper di bawah pengaruh tegangan adalah adanya presipitat-presipitat yang kasar dan lebih sedikit jumlahnya dibandingkan dengan presipitat-presipitat setelah ditemper tanpa pengaruh tegangan.
Beberapa Aspek Teori dan Pemakaian dalam Masalah Dekomposisi Singulir M.A. Djauhari
Journal of Mathematical and Fundamental Sciences Vol. 14 No. 3 (1981)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Sari. Dekomposisi singular suatu matriks real dapat dipandang dari berbagai sudut. Dengan bantuan rangkaian dual, di sini akan dipandang dari sudut operator Escoutier yang berkaitan dengan matriks tersebut. Selanjutnya akan dikemukakan beberapa aspek yang diakibatkan oleh pandangan ini. Abstract. The singular decomposition of a real matrix can be approached from several points of view. Here we use the Escoufier's operator and the instrument called diagram of duality. With this instrument we can visualize all mathematical terms involved in that problem.
Fungsi Distribusi Statistik tN dalam Suatu Penyebaran Individu yang Beraturan dalam Bentuk Hexagon M.A. Djauhari
Journal of Mathematical and Fundamental Sciences Vol. 14 No. 1/2 (1981)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Sari. Statistik pengujian keacakan suatu penyebaran individu pada bidang datar selalu didasarkan pada hipotesis awal H0 bahwa penyebaran individu merupakan suatu realisasi dari suatu proses Poisson. Selanjutnya sebagai hipotesis alternatif biasa dipergunakan;(i). H11 : penyebaran individu merupakan suatu realisasi dari suatu proses Thomas.(ii). H12 : penyebaran individu adalah teratur dalam bentuk segitiga-segitiga sama sisi.(iii). H13 : penyebaran individu adalah teratur dalam bentuk bujursangkar-bujursangkar. Abstract. In order to determine the index of randomness a spatial pattern of objects the null hypothesis Ho that our spatial pattern is a realization of a Poisson's process is needed. The alternative usually used are:(i). H11: the spatial pattern is a realization of a Thomas' process.(ii). H12: the spatial pattern is regular in the form of equilateral triangles.(iii). H13: the spatial pattern is regular in the form of squares.We propose here the fourth alternative H14 that the spatial pattern is regular in the form of hexagons. Our interest here is to study, under H14, the distribution of tN, i.e. the best test of randomness under the first three alternatives (Djauhari, 1977). 
Plateholder-Mirror Alignment of Schmidt Telescope Suganda Jutamulia; Bambang Hidayat
Journal of Mathematical and Fundamental Sciences Vol. 14 No. 1/2 (1981)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Abstract. In the plateholder mirror alignment, we produce an auxiliary point source which falls at the correcting lens. If the adjustment is correct, then the image of once reflection, I1, will coincide with the image of three relections I3, as proposed by Dewhirst and Yates. However our results indicate that, due to off-axis position of the source, there exists aberrations at I1 and I3. Sari. Sebuah sumber-cahaya-titik buatan telah dibentuk pada lensa-koreksi guna tes pelempangan kaset pelat potret Schmidt, di Observatorium Bosscha. Cara Dewhirst dan Yates diadaptasikan untuk keperluan tes. Dalam tes ini, diselidiki jalan berkas cahaya yang terpantul sekali (I1) dan 3 kali (I3) oleh cermin utama. Kalau kedudukan kaset pelat baik, maka I1 akan berimpit dengan I3. Tetapi hasil tes kita memperlihatkan bahwa, akibat kedudukan sumber cahaya di luar sumbu, terjadi aberasi pada I1 dan I3. 
Pengujian Beberapa Tumbuhan Ekonomi terhadap Serangan Suatu Nematoda Puru Akar Buddy D. Kosasih; Inge Birsyam; Nuryati Yuli
Journal of Mathematical and Fundamental Sciences Vol. 13 No. 3 (1980)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Sari. Serangan nematode puru akar, Meloidogyne sp, terhadap 21 spesies tanaman terdiri dari 40 varietas, telah dilakukan di Unit Fitopatologi, Jurusan Biologi, ITB. Sebagian besar tanaman yang diamati adalah peka terhadap serangan nematode tersebut, kecuali 6 varietas tanaman kapas (DP. 16, DP. 25, DP. 45A, DPSL, RBTK dan Carolina Queen), cabai (var. Local), rosella (var. Altissima) dan kacang rambat varietas Surakarta, adalah tahan terhadap serangan nematoda tersebut. Sedangkan tanaman tomat (var. Monalbo dan STS No.3865), kentang (var. Desiree), terung (var. Long purple) dan selada (var. Batavia Green), adalah sangat peka. Abstract. Twenty one species and 40 varietas of economical plants were tested for susceptibility to the root-knot nematode, Meloidogyne sp. The experiment were conducted at the Phytopathological Laboratory, Department of Biology, Institute of Technology Bandung. Six varieties of cotton (DP. 16, DP.15, DP.45A, DPSL, RBTK and Carolina Queen), red pepper (var. Local), roselle (var. Altissima), and one species of bean (var. Surakarta) were resistant. Two varieties of tomatos (var. Monalbo and STS No.3835), potato (var. Desiree), egg plant (var. Long purple), and lettuce (var. Batavia Green), were found highly susceptible to root-knot nematode.

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