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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 6 Documents
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Search results for , issue "Vol. 31 No. 1 (1999)" : 6 Documents clear
Pengukuran Kristalinitas Silika berdasarkan Metode Difraktrometer Sinar-X N.R. Herdianita; Ong H.L.; E.A. Subroto; B. Priadi
Journal of Mathematical and Fundamental Sciences Vol. 31 No. 1 (1999)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Sari. Mineralogi dan derajat kristalinitas mineral silika non- dan mikrokristalin dapat ditentukan dengan metode difraktometer sinar-X, yaitu dengan mengukur lebar peak atau hump pada setengah intensitas-maksimum difraksi pada posisi sekitar 4 Ã…. Hasil optimum pengukuran kristalinitas diperoleh bila sampel silika kering berukuran butir 75 hingga 106 μm dipreparasi pada cetakan aluminium dan dianalis mulai 10 hingga 40°2θ dengan kecepatan goniometer 0,6°2θ/menit dan interval pencatatan 0,01°. Prosedur seperti ini akan mempunyai kesalahan tidak lebih dari 0,3°2θ. Measurement of Silica Crystallinity Using X-Ray Diffraction MethodAbstract. Mirralogy and the degree of crystallinity of non- and microcrystalline silica could be determined using the X-ray diffraction method, i.e. by measuring the half-width peak or hump at about 4 Ã…. The optimum and most reproducible results were obtained when dry silica sample powder having a grain size of 75 to 106 μm was prepared at the aluminium holder and scanned from 10 to 40°2θ using goniometer speed of 0.6°2θ and a step size of 0.01°. This procedure will give an experimental error less than 0.3°2θ.
Identifikasi Lapisan Batubara dari Segi Geokimia Anorganik Darmawan Sumardi; Totok Darijanto
Journal of Mathematical and Fundamental Sciences Vol. 31 No. 1 (1999)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Sari. Penentuan kelimpahan unsur kimia dalam percontoh lapisan batubara dilakukan melalui analisis unsur kimia pada abu batubara berupa V, Ni, Cr, Co, Mo, Cu, Zn,Pb, Mn, Sn, Sr, Ba, Cd, As, Ag, Al, Ca, Mg, Fe, Na, dan K serta melalui fraksi-fraksi batubara hasil pemisahan sink and float berupa Si, Al, Ca, Mg, Fe, Ni, Cu, Na, dan K. Jenis unsur tersebut dapat menjadi parameter identifikasi lapisan yang berguna dalam korelasi stratigrafi lapisan, dan gambaran kecenderungan asosiasi mineral dengan golongan maseral batubara yang dapat mendukung pararameter tadi. Dari analisis principal component didapati bahwa Ni, Cr, dan V merupakan parameter yang baik untuk identifikasi lapisan; sebagai pembanding digunakan data lapisan batubara Bihar dari India dan Kanada. Unsur ini diperkirakan terikat pada molekul bahan organik sebelum diagenesis gambut, bersama terbentuknya kuarsa, kaolinit, gips dan cenderung berasosiasi dengan huminit/vitrinit. Mineral yang cenderung terbentuk selama diagenesis adalah siderit, kalsit, Mnkarbonat, serta illit/smektit yang lebih berasosiasi dengan inertinit. Coal Seam Identification from the Aspect of Inorganic GeochemistryAbstract. Elements abundance in the coal scams samples were determined by analyzing 1) the coal ash, namely V, Ni, Cr, Co, Mo, Cu, Zn, Pb, Mn, Sn, Sr, Ba, Cd, As, Ag, Al, Ca, Mg, Fe, Na, and K, and 2) maceral rich coal fractions by sink & float separation,  namely Si, Al, Ca, Mg, Fe, Ni, Cu, Na, and K. The scope is to obtain certain elements as a parameter for coal scam identification which could be applied as a useful stratigraphic correlation tool and an inferrence on mineral occurence associated with maceral groups within the coal seam Ni, Cr, and V are shown to be the best parameter for seam identification by means of principal component analysis; for comparison purposes data from Bihar (India) and Canada were used. These elements are interpretated to be fixed to the organic molecules before peat diagenesis contemporancously with the formation of quartz, kaolinite, and gypsum and tend to associate with huminite/vitrinite. Minerals tend to be formed during diagenesis are siderite, calcite, carbonate of Mn, and illite/smectite with the associated inertinite.
Penerapan Spouted-ben dalam Pembuatan Natrium Silikat dari Abu Sekam Padi: Hidrodinamika, Perpindahan Massa, dan Perolehan Silikat Johnner P. Sitompul; Chrismono Himawan; Agus Wanadri
Journal of Mathematical and Fundamental Sciences Vol. 31 No. 1 (1999)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Sari. Telah dilakukan satudi awal penerapan spouted-bed untuk menyelenggarakan reaksi cair-padat, NaOH-abu sekam padi guna memperoleh natrium silikat yang mencakup studi hidrodinamika, perpindahan massa, dan perolehan silikat. Korelasi kecepatan minimum spouting dan kriteria kestabilan spouting telah diperoleh lewat pengematan sistem tak bereaksi air-abu sekam padi. Korelasi untuk koefisien perpindahan massa pada rezim transisi, Re partikel 7-25 atau Re fluida 19-254, diperoleh lewat penerapan model reaksi cair-padat dengan anggapan laju difusi NaOH dari bulk ke permukaan partikel sebagai pengendali. Konversi SiO2 tertinggi yang diperoleh mencapai 62% dengan pemakaian larutan NaoH yang relatif encer, yaitu 0,8 M. unjuk kerja ini lebih baik dibandingkan dengan hasil yang telah diperoleh peneliti terdahulu. Tawar-menawar antara konversi SiO2 dengan perolehan rasio SiO2/Na2O dalam produk perlu diperhatikan berdasarkan hasil studi ini. Spouted-Bed Reactor in Producing Sodium Silicate from Paddy Husk Ash: Hydrodynamics, Mass Transfer, and Silicate YieldAbstract. A laboratory-scale spouted bed reactor has been applied for producing sodium silicate from paddy husk ash and NaOH. The study covered hydrodynamics, mass transfer, and silicate-yield in the reactor. The correlation of minimum superficial velocity was determined by using nonreacting paddy ash-water system. Mass transfer correlation is spouted-bed which is valid for transition regim, i.e. Reynold particle range 7-25 or Reynold fluid number 19 -254, was derived from a simple model assuming the diffusion rate of NaOH from bulk to the particle surface as a determining step. Conversion of SiO2, equivalent to Na-silicate yield, is up to 62% using 0.8 M NaOH. This performance is significantly better than the other previous research. The study found that in producing silicate pay-off between SiO2 conversion and SiO2/Na2O mol ratio should be considered.
Inhibisi Korosi Baja Karbon di dalam Larutan Karbonat-bikarbonat Isdiriayani Nurdin; M. Syahri
Journal of Mathematical and Fundamental Sciences Vol. 31 No. 1 (1999)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Sari. Sistem absorpsi CO2 yang menggunakan absorben K2CO3 merupakan salah satu satuan operasi yang rawan korosi, terutama di bagian yang berhubungan dengan larutan "kaya" yang mengandung KHCO3. Baja karbon, yang biasa digunakan sebagai bahan konstruksi pada sistem absorpsi CO2 terkorosi oleh larutan K2CO3 + KHCO3 tetapi juga bersifat mampu pasif dalam larutan tersebut. Oleh sebab itu, korosi pada sistem absorpsi CO2 dapat dikendalikan dengan menggunakan inhibitor pasivator seperti KVO3. Dari hasil pengujian yang telah dilakukan, ternyata KVO3 dengan dosis 20 g/dm3 efektif menurunkan laju korosi baja karbon dalam larutan K2CO3 + KHCO3 pada suhu 100 °C, dan turbulensi yang tinggi. Lapisan pasif yang terbentuk dengan penambahan inhibitor vanadate terutama terdiri dari n-Fe2O3 dan FeVO4 Na-benzoat, yang juga inhibitor pasivator, dapat menurunkan laju korosi baja karbon dalam lingkungan yang sama dengan efektifitas yang tidak jauh berbeda, tetapi dengan dosis lebih rendah (14 g/dm3). Lapisan pasif yang dihasilkan dengan penambahan inhibitor Na-benzoat terdiri dari n-Fe2O3 dan Fe2(OH)2CO3. Corrosion Inhibition of Carbon-Steel in Carbonate-Bicarbonate SolutionAbstract. Carbondioxide (CO2) absorption system, using K2CO3 as absorbent, is one of the absorption unit which is susceptible to corrosion attack, especially the parts contacting the KHCO3 rich solution. Carbon steel which used to be the construction material of CO2 absorption system, is susceptible to corrosion in K2CO3 + KHCO3 solution with a passivation tendency. The use of passivating inhibitor, especially KVO3, is one of the most popular corrosion prevention method. Experimental results show that 20 g/dm3 KVO3 is effective to inhibit corrosion of carbon steel in K2CO3 + KHCO3 solution at temperature up to 100°C and high turbulence. This passivation is due to the formation of protective layer which consists of η-Fe2O3 and FeVO4. Another passivating inhibitor, Na-benzoate, is found to be similarly effective to KVO3 in the same testing conditions. The passive film, formed by the addition Na-benzoate, consists of η-Fe2O3 and Fe2(OH)2CO3.
Modelling of the Heated Water Spreading in Muara Karang Coastal Waters, Jakarta Bay D.K. Mihardja; M.S. Fitriyanto; M.R. Putri
Journal of Mathematical and Fundamental Sciences Vol. 31 No. 1 (1999)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Abstract. Modelling of the heated water spreading in Jakarta Bay had been performed as a part of the study on cooling water circulation of Muara Karang Power Plant, North Jakarta. The results of the simulation described in this paper illustrated for cast season (August 1994), transitional season (November 1995), and west season (Januari 1996). The spreading of thermal water in Muara Karang coastal waters near the outlet canal of the power plant for each season and all tidal and wind conditions is dominantly influenced by discharge of cooling water that has maximum value of 35.1 m3/sec. In the far field area the spreading is directed by monsoon (wind-induced) currents and slightly influenced by tidal currents. Thermal water which spreads out from the outlet canal into coastal waters has a minimum area of about 58.60 hectares in transitional season at highest water level, and a maximum area of about 156 hectares in transitional season when water level goes to cbb. In general, the simulation results in the cast season are comparable to the observed data, while in the transitional season of cast-west season of cast-west season the and in the west season the model is still being verified. Pemodelan Penyebaran Air Hangat dari Pembangkit Listrik Tenaga Uap di Peraian Muara Karang, Teluk JakartaSari. Pemodelan sebaran panas di Teluk Jakarta merupakan salah satu bagian dari studi resirkulasi air pendingin PLTU Muara Karang, Jakarta Utara. Hasil simulasi pada makalah ini menggambarkan kondisi pada musim timur (Agustus 1994), musim peralihan (November 1995), dan musim barat (Januari 1996). Sebaran termal di perairan Muara Karang dekat saluran outlet PLTU untuk masing-masing musim dan semua kondisi pasang surut dan angina sangat dominan dipengaruhi oleh debit PLTU yang maksimum 35,1 m3/detik. Di daerah jauh, arah sebaran termal bergantung pada arus musim (pengaruh angin) dan sebagian dipengaruhi oleh pasang surut. Temperatur air panas yang keluar dari saluran outlet menyebar ke perairan dengan luas minimum 58,60 hektar pada musim peralihan pada saat air pasang maksimum, dan luas maksimum sekitar 156 hektar pada musim peralihan saat air menuju surut. Secara umum hasil simulasi pada musim timur yang dibandingkan dengan data lapangan hamper sesuai, sedangkan pada musim peralihan dari musim timur ke musim barat dan pada musim barat masih akan diverifikasi lebih lanjut. 
Zero Gravity of Free-Surface Flow Over A Weir L.H. Wiryanto
Journal of Mathematical and Fundamental Sciences Vol. 31 No. 1 (1999)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Abstract. The exact solution of free-surface flow over a weir in a channel of finite depth is presented for a thin weir with various weir heights. This exact solution can be obtained by neglecting the effect of gravity. This is an extreme case which can be used to answer a question: why do we have to incline the wall to obtain solutions with a curving back jet but the flow leaves the wall smoothly. Gravitasi Nol dari Aliran Permukaan Bebas yang Melewati BendungSari. Solusi eksak dari aliran permukaan bebas yang melompati bendung pada suatu saluran dengan kedalaman-hingga disampaikan dalam tulisan ini, yaitu untuk bendung tipis dengan ketinggian bervariasi. Solusi ini dapat diperoleh dengan mengabaikan pengaruh gravitasi. Hal ini merupakan kasus ekstrem yang dapat digunakan untuk menjawab pertanyaan: mengapa kita harus memiringkan dinding bendung untuk mendapatkan solusi dengan jet yang membalik tetapi alirannya ditinggalkan dinding dengan mulus.

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