Journal of Mathematical and Fundamental Sciences
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Offshore Tertiary Sedimentary Basins in Indonesia
Get PDFRingkasan. Cekungan-cekungan sedimen berumur Tersier yang kaya akan minyak dan gas bumi terutama terdapat di bagian barat Indonesia. Cekungan-cekungan ini dahulunya disebut sebagai "ideogeosynclines", dan terdapat sekeliling tepi suatu masa daratan pre-Tersier yang diperkirakan dan dinamakan "Sunda Shelf". Dewasa ini daerah tersebut ditutup oleh laut-laut Epikontinental yang dangkal (Laut Jawa, Laut China Selatan). Bahagian luarnya cekungan-cekungan ini dibatasi oleh busur kepulauan volkanik dalam. Penyelidikan-penyelidikan seismic lautan yang sangat luas, yang dilakukan baru-baru ini dan disusul oleh pengeboran telah membuktikan adanya penerusan dari beberapa cekungan ini kelepas pantai (antara lain Sumatra Utara, Jawa Barat, Jawa Timur dan Kalimantan Timur). Lebih penting lagi penyelidikan tersebut telah membuka tabir bahwa paparan Sunda yang semula diperkirakan bertindak sebagai sumber-sumber sedimen selama "Tersier" dalam kenyataannya terdiri dari banyak cekungan-cekungan sedimen dan peninggian-peninggian yang memisahkannya, dan hanya daerah antara Bangka, Belitung, serta kepulauan Natuna-Anambas adalah daratan Sunda yang sebenarnya. Peninggian-peninggian ini bertindak sebagai sumber dari berbagai lapisan sedimen dan beberapa diantaranya diwakili oleh pulau-pulai pre-Tersier antara lain Bangka, Belitung dan Karimun Jawa. Pematahan bongkah dari batuan dasar ternyata bertanggung jawab atas perkembangan cekungan-cekungan ini, dan juga mengendalikan pengendapan maupun tektonik dari lapisan Tersier yang menutupinya. Selanjutnya explorasi lepas-pantai juga telah membuktikan adanya lapisan-lapisan sedimen tersier di antara Busur Kepulauan Volkanik dalam (misalkan Sumatra) dan busur Non-volkanik luar (pulau Nias dan lain-lain). Sampai saat ini belum terdapat cukup data-data untuk membahasa cekungan sedimen lepas-pantai di Indonesia Timur. Penyelidikan-penyelidikan geofisika laut dan pengeboran masih dalam kemajuan dewasa ini. Lokasi-lokasi pengeboran lepas-pantai masih sangat banyak yang direncakan untuk tahun-tahun yang akan datang. Sehingga masih terlalu pagi untuk membahas implikasi-implikasi geologi yang luas. Abstract. Prolific Tertiary sedimentary basins are mainly located in Western Indonesia. They have previously been described as "ideo-geo-synclines", and are situated around the periphery of a supposed pre-Tertiary land-mass the "Sunda Shelf", now largely covered by shallow epicontinental seas, (Java Sea, South China Sea). Outward they are bordered by the Inner Volcanic island arc. Recent extensive marine seismic investigations and subsequent drilling have confirmed the extension of some of these basins offshore (e.g. North Sumatra, West Java, East Java and East Kalimantan). More important, however, these surveys have revealed that the "Sun Shelf" which supposedly served as source of sediments during the Tertiary, actually consist of numerous sedimentary basins and intervening uplifts, leaving the area between Bangka-Billiton and Natuna-Anambas Islands as the Sunda-land proper. These uplifts served as source of sediments and some are represented by pre-Tertiary islands, e.g. Bangka, Billiton and Karimun Jawa. Basement block-faulting is apparently responsible for the development of these basins, and controlled depositions as well as tectonics of the Tertiary cover. Further offshore exploration has also confirmed the presence of Tertiary sediments between the Inner Volcanic islands (c.q. Sumatra) and the outer non-volcanie arc (c.q. Nias). There is no sufficient data to date to describe offshore sedimentary basins is eastern Indonesia. Marine geophysical surveys and drilling are still in progress at present. Numerous offshore drilling locations are scheduled for several years, so that it is still too preliminary to discuss the broad geological implications.
Some Notes on the Design, Construction and Performance of the Low-Speed Wind-Tunnel at ITB
No full textAbstract. A concise description of the design and construction of the low speed wind-tunnel at Institut Teknologi Bandung and the calculation of its energy losses are presented. Some tests have been undertaken to evaluate its performance, in particular to evaluate the flow pattern at the test-section and the power input for a specific range of wind velocity at the test-section. The maximum velocity achieved at the test-section was 30 m/sec with corresponding Reynolds number of 2 x 104 per cm. Ringkasan. Konstruksi dan perhitungan kerugian energi pada terowongan angin kecepatan rendah di ITB diuraikan secara garis besar. Selanjutnya dipaparkan hasil-hasil penilaian performance dari terowongan angin ini, terutama mengenai keadaan aliran pada testsectiondan hubungan antara daya input pada motor dengan kecepatan aliran pada test-section. Kecepatan angin sebesar 30 m/det dapat diperoleh pada test-section, dengan bilangan Reynolds sebesar 2 x 104 per cm model
Pengamatan Okultasi Beta Scorpio oleh Planit Jupiter
No full textThe occultation of the multiple star Beta Scorpio by Jupiter was observed visually and photographically with the 24"-twin telescope of the Bosscha Observatory. The photographic records obtained by S.M. Larson, using the instrument of the Bosscha Observatory, provided support to a scale height greater than 8 km. The Lembang visual measurement is shown to be consistent with other observations, taken from other observatories.
Origin of Lake Singkarak in the Padang Highlands (Central Sumatra)
No full textSince long it has been accepted that Lake Singkarak in the Padang Highlands is nothing else but a remnant of a gigantic volcano-the Singkarak volcano- which one blew off its top to form a lake. Van Bemmelen though not referring to Singkarak Lake especially, explained the numerous depressions in Sumatra as the combined result of volcanic and tectonic activities, a phenomenon he called volcano-tectonic process which caused the formation of the so called volcano-tectonic depressions.A short visit to the lake area in the months of February and March (1970) convinced the author that the Singkarak Lake is neither a volcanic ruin nor a volcano-tectonic depression in the sense of Van Bemmelen.Faulting evidences, morphology and the position of the Singkarak trough plus the distribution of volcanic products north and south of the lake lead to the conclusion that the Singkarak trough is a depression making part of the 1650 km graben zone which stretches from Sumatra's northern tip until the Semangko valley in the SE. Field evidences suggest that the lake results from a damming process by volcanic material produced by the Marapi-Singgalang-Tandikat volcanoes in the north and by the products from the Talang volcano in the south.
Industrial Possibilities of Idjen Crater Lake Water
No full textAbstract. Idjen Crater Lake Water containing 600.000 tons of sulfur 1) 4) (compare total Indonesian sulfur reserves of 1 million tons 2) has been investigated as to the possibility of its use as an industrial raw material. Although sulfate can most conveniently be recovered from the dilute acid solution as gypsum, it is advantageously suggested to convert the latter into ammonium sulfate, thus potentially increasing the possibility of fertilizer production in Indonesia. A flowsheet has been proposed. Although processing the Lake Water seems to be feasible front a technological point of view, a possible danger of Idjen Volcano eruption, however small, should not be overlooked. Ichtisar. Air Kawah Idjen jang mengandung 600.000 ton belerang (bandingkan dengan tjadangan Indonesia sebanjak sedjuta ton) telah diselidiki mengenai kemungkinan untuk dipakainja sebagai bahan mentah industri. Meskipun sulfatnja dengan mudah dapat diperoleh dari larutan asam jang entjer itu sebagai gips, telah diusulkan untuk mengolah terus zat achir ini mendjadi ammoniumsulfat (Z.A.), jang merupakan bahan pupuk jang berharga. Walaupun pengolahan Air Kawah Idjen ternjata mungkin sekali dari sudut teknologi, perlu diselidiki pula kemungkinan meletusnja gunung api tsb., meskipun hal itu telah lama tidak terdjadi
Beberapa Pikiran Mengenai Perkembangan Televisi di Indonesia
No full textIchtisar. Televisi, selain vital untuk bangsa2 NEFO guna memperkuat persatuan dan memperkembangkan kepribadiannja, djuga merupakan suatu keharusan jang mutlak untuk menghadapi tantangan2 jang disebabkan oleh kemadjuan2 teknik, chusus dalam bidang telekomunikasi. Dengan kemadjuan2 jang ditjapai dalam Space radio2 communication, jaitu hubungan radio melalui satelit buatan jang diorbitkan diangkasa luar, dalam waktu jang tidak terlalu lama, dapat diramalkan bahwa tiap penduduk dibumi ini, tidak hanja dapat menerima siaran2 radio, tetapi djuga dapat mengikuti siaran2 televisi dari tiap negara diseluruh dunia. Untuk menghadapi tantangan ini, Indonesia tidak dapat tergantung hanja dari djaringan2 telekomunikasi jang dibangun melulu dengan alat2 buatan luar negeri. Tulisan ini menjarankan suatu djaringan alternatip jang sederhana dan murah, dimana potensi industri dalam negeri jang ada, sudah dapat diikut sertakan. Djaringan alternatip ini berdasarkan suatu projek-teladan stasiun relay televise digunung Tangkubanprahu untuk penerimaan dikota Bandung, jang merupakan hasil karja Panitia Transmisi Televisi Eksperimentil. Sedikit perhitungan jang merupakan dasar dari projek-teladan di Tangkubanprahu ini, diuraikan sekadarnja. Abstract. Television is vital to the New Emerging Forces nations, and is also a means of strengthening their unity and developing their integrity. Television is also important to a nation facing the challenge of modern technical development, particularly in the field of telecommunication. With the advances achieved in Space-Radio Communication, that is radio communication through manmade satellites orbited into outer space, it can be predicted that in the near future, people on earth will not only be able to receive radio broadcasts, but also to watch programs from every country in the world. To face this challenge, Indonesia, in setting up her telecommunication network, must not depend on foreign made instruments. This paper suggests an alternative and less expensive telecommunication network in which potential domestic industries are able to participate. This alternative network is based on a pilot project television relay station on Mount Tangkubanperahu for reception in the Bandung area. This pilot project is the work of the Committee on Television Experimentation. A few basic computation on which the Tangkubanperahu pilot project is based are demonstrated. The proposed television network, are taking advantages of high mountains which are a feature of Indonesian landscape; unfortunately a complete survey has not yet been made. The use of high mountains, however, has logistic consequences, and further study of this aspect is necessary
The Photoelectric Instrument at the Bosscha Observatory
Get PDFIchtisar. Sebuah uraian tentang pesawat ptotoelectris photometer di Observatorium Bosscha Lembang, dengan mempergunakan sebuh photomultiplier type 1P21 jang didinginkan dengan es kering atau sebuah multiplier type EMI pada pendinginan telah disadjikan dibawah ini. Photometer tersebut jang diperlengkapi dengan filter2 U, B, V dan R, dipasangkan pada teropong lensa 37 cm Bamberg-Schmidt dan baru dapat dipergunakan untuk menentukan ekstingsi atmosfir untuk Observatorium Bosscha di Lembang pada penghabisan musim terang dalam tahun 1962.Abstract. A description of the photoelectric photometer at the Bosscha Observatory Lembang, operated with a photomultiplier of type IP21 refrigerated with dry ice or using an EMI-type of multiplier (non-refrigerated) is presented below. The photometer, provided with U, B, V, and R filters and attached to the 37 cm Bamberg-Schmidt refractor, has been used for determining the atmospheric extinction of the Observatory during the last part of the dr season in 1962
Limiting Behavior of A Sequence of Density Ratios
Get PDFLet X1, X2,"¦.. be a sequence of random variables and Ð = {Pθ,θ Є (-)} be a family of distributions of the sequence. For each n, An is the σ-field generated by X1,"¦, Xn.If θ1,θ2 Є (-), we define Rn (θ1,θ2) as the density ratio of Pθ1,Pθ2 on An.The main purpose of the paper is to investigate limiting behavior of the sequence Rn with respect to any Pθ. This has applications in sequential analysis, where it is desired to know whether a sequential probability ratio test terminates with probability one. The same conclusion can be drawn in the case of generalized sequential probability ratio test, under some restriction as to how the stopping bounds vary with n.If the Xi are independent and identically distributed, then we can write in Rn as where the Yi are independent and identically distributed. We have then that converges to ~ or to -~ a.e. according as Eθ {Yi}>0 or <0. For any θ, say θ0, for which Eθ0{Yi}=0 we have lim inf Rn="0" and lim sup Rn=~ a.e. Pθ0.A sequence of non-independent nor identically distributed random variables {Xi} may arise in tests of composite hypotheses in the presence of nuisance parameters. An example of the situation is the sequential t-test, by some authors called the WAGR test. In this example we have the same qualitative result as if the Xi are independent and identically distributed.The foregoing example suggested the more general problem with the assumption A and B (see chapters 2 and 3). The result can be described as follows: If θ1 < θ2then Rn converges a.e. to 0 if θ≤θ1 and to ~ if 0 ≥ θ2. For θ between θ1and θ2, except perhaps for one θ0, then lim inf is 0 or lim sup is ~ a.e. So that a sequential probability ratio test terminates with probability one, except perhaps for one value of θ. There is no example known to show that there may exist a θ0 for which the sequence density ratios has a positive lim inf and a finite lim sup
Widerstandtransformationen Mit Gekoppelten Zweikreisigen Schaltungen Bei Beliebiger Bandbreite
Get PDFDi bidang frekwensi gelombang pendek, yaitu kira-kira antara 1 MHz sampai 30 MHz, penjesuaian2 tahanan biasanja dilakukan dengan transformator2 saluran atau rangkaian2 transformasi jang terjadi dari kapasitet2 dan induktivitet2 tanpa botjor tenaga. Beberapa percobaan untuk melakukan penjesuaian tahanan dengan tjara jang sering dipakai di bidang frekwensi suara, jaitu dengan dua kumparan jang bergandengan, memberikan hasil jang memuaskan.Publikasi ini memuat hasil2 perhitungan jang merupakan dasar teori dari pertjobaan jang di atas, dan membatasi diri pada bidang frekwensi, dimana transformator masih bersifta kwasi-stationer.Perhitungan jang banjak persamaannja dengan perhitungan di publikasi ini, telah dilakukan oleh Feldtkeller, tetapi hanja untuk bidang frekwensi relatip jang sempit (∆ f/fm < 10%).Untuk bidang frekwensi jang lebar, Meinke mengusulkan tjara perhitungan grafis jang berdasarkan perhitungan Feldkeller. Kesalahan-kesalahan jang dibuat karena pengabaian2 , jang sebetulnja tak dapat lagi dilakukan pada bidang-frekwensi jang lebar, diperbaiki setjara bertahap.Tjara perhitungan tanpa pengabaian2 untuk lebar bidang frekwensi sembarang, haruslah memakai fungsi Tschebyscheff dalam bentuk petjahan. Berlainan dengan Cauer, fungsi petjahan Tschebyscheff jang dipergunakan dalam publikasi ini adalah dalam bentuk aslinja
The Behaviour of Blood Chloride During Osmo-regulation in the Sawahcrab (Paratelphusa Conveka)
Get PDFPARATELPHUSA CONVEXA, JG MULA-MULA ADALAH CHEWAN laut dan sekarang hidup di air tawar dan djelas menggambarkan kemampuannja untuk memelihara komposisi darahnja dalam berbagai matjam keadaan sekitarnya (osmoregulasi).Bila ketam sawah itu dibiarkan di dalam air suling, maka mula-mula kadar chlorida di dalam darahnja menurun tetapi kadar chlorida tersebut tjepat kembali seperti semula. Kedjadian ini mungkin disebabkan karena pelepasan chlorida di dalam chewan itu. Pelepasan chlorida itu mungkin dipengaruhi oleh berbagai faktor, misalnja konsentrasi total daripada sekitarnja, konsentrasi chlorida, atau konsentrasi daripada ion-ion lainnja. Banjak dari kemungkinan-kemungkinan itu telah ditjoba dengan memakai tjampuran-tjampuran garam buatan dan kadar chlorida dalam darah telah ditentukan setjara kwantitatip (micro Volhard). Ternjata turunnja chlorida darah dalam air suling itu tidak hanja disebabkan karena kekurangan kadar chlorida. Faktor-faktor jang sesuai sudah diselidiki dan hubungan kwantitatip antara kadar chlorida darah dan pelepasan chlorida telah dianalisa.