RADIO ASTRONOMY - An Introduction

Wonders of the night sky developed curiously to the ancient civilization and paved way to the development of an oldest branch of knowledge, Astronomy. Today it has developed to be rich field in science. Astronomy is much different from many other science fields. ? It deals with remote subjects, unimaginable magnitude distances, sizes and time. The conventional optical telescope could not reveal vast majority of objects in the sky. Apart from light there are other invisible radiations reaching the Earth from the celestial objects. People started exploring both ends of the electromagnetic spectrum. Ever since World War II, astronomers are exploring the radio sky, by using Radio Telescopes. It became a new branch of study, the Radio Astronomy. Interesting fundamental discoveries and the inquisitive nature of the problems developed curiosity for future explorations in this field. The celestial radio signals reaching us are extremely week. It is required to develop sophisticated tools and powerful techniques to aid radio astronomy observations. Today Radio Astronomy has developed to be a highly interdisciplinary field with connections to various fields of science and engineering

Studies on ecology of phytoplankton from Pichavaram mangroves, South East Coast of India

The spatial and seasonal distribution of phytoplankton species and their abundance to hydrographical parameters were studied during April 2000 and March 2001 from two stations of Pichavaram mangroves located in south east coast of India, (Lat. 11°27’N: Long 79°47E).  During the study 91 species of phytoplankton were recorded which belongs to different groups viz. Diatoms (73), Dinoflagellates (17) and Slicoflagellates (1). Species such as Coscinodiscus centralis, Pleurosigma elongatum, Thalassionema nitzschioides, Skeletonema costatum Triceratium favus, Odentella sinensis, Navicula longa and Ceratium furca Constituted bulk of the population density.  More number of species was recorded at station 1 and the production of phytoplankton was very high during summer season. The temperature, salinity, pH and dissolved oxygen examined fairly stable during the study period except monsoon. During the summer season nutrients level was low as well as the phytoplankton density was very high

Finite Element Modeling Of Multiwalled Carbon Nanotube

Three-dimensional finite element (FE) model for armchair, zigzag and chiral single-walled carbon nanotubes (SWCNTs) is proposed. The model development is based on the assumption that carbon nanotubes, when subjected to loading, behave like space-frame structures. The bonds between carbon atoms are considered as connecting load-carrying members, while the carbon atoms as joints of the members.To create the FE models, nodes are placed at the locations of carbon atoms and the bonds between them are modeled using three-dimensional elastic beam elements. The elastic moduli of beam elements are determined by using a linkage between molecular and continuum mechanics. The investigation includes armchair and zigzag SWCNTs. It is found that the choice of Vanderwall forces, the interaction significantly affects the calculation of Young’s modulus. The obtained values of Young’s modulus agree very well with the corresponding theoretical results and many experimental measurements. Dependence of elastic moduli to diameter and length of the nanotubes is also obtained. The presented results demonstrate that the proposed FE model may provide a valuable tool for studying the mechanical behavior of carbon nanotubes and their integration in nanocomposites. So for we dealt with single walled carbon nanotube, in our case, we are going to consider into doubled walled carbon nanotube generally speaking multi-walled carbon nanotube. The therefore properties so obtained is completely different that of single walled. The DWCNT is then modeled in ANSYS-multiphysics then in is analysed for the mechanical properties using the same. The elements were considered as beam4, it is an uniaxial element with tension, compression, torsion, and bending capabilities. The element has six degrees of freedom at each node: translations in the nodal x, y, and z directions and rotations about the nodal x, y, and z axes. Stress stiffening and large deflection capabilities are included. The interaction between the two layers of the MWCNT, the Vanderwalls interation, is considered in the calculation of mechanical parameter .The interation are also made of beam4 element, which researchers have not so far attempted to work on

Perencanaan Injeksi Waterflooding Dengan Metode Prediksi Buckley Leverett Dan Craig Geffen Morse Pada Sumur Injeksi I Di Lapisan W3 Struktur Niru PT Pertamina Ep Asset 2 Field Limau

Tekanan reservoir yang berkurang akibat produksi minyak secara terus menerus dengan laju yang tinggi merupakan latar belakang dilakukannya proses injeksi waterflooding.Metodeprediksi yang dipilih adalah Buckley Leverett dan Craig Geffen Morse untuk memprediksikan waktuinjeksi, laju produksi, jumlah air injeksi serta faktor perolehan setelah injeksi.Dari hasil perhitungan metodeBuckley Leveret dianalisis waktu yang dibutuhkan tahap awal sampai fill up 9 hari, fill up sampai breaktrough 144 haridan tahap setelah breaktrough 1.014 hari sampai air terproduksi. Dari hasil perhitungan metode Craig Geffen Morse waktu yang dibutuhkan tahap awal sampai interference 30 hari, tahap interference sampai fill up 39 hari dan tahap setelah breaktrough 2.405 hari. Sisa cadangan yang lebih sedikit ada metode Craig Geffen Morse yaitu 5.328 STB sedangkan metode Buckely Leverett 7.548 STB.Dari hasil perhitungan waktu yang paling lama ialah prediksi craig geffen morse namun sisa cadangan yang tertinggal setalah injeksi lebih sedikit danberdasarkan dari asumsi,metoda yang mendekati keadaan sebenarnya ialah metoda craig geffen morse sehingga disimpulkan metode prediksi yang paling efektif ialah metode graig geffen morse

Desain Sucker Rod Pump Untuk Optimasi Produksi Sumur Sembur Alam L5a-x Di Pertamina Ep Asset 2 Field Limau

Sumur yang terus berproduksi akan mengalami penurunan tekanan reservoir dan akibatnya produktifitas sumur menurun, maka perlu ditambah tekanan agar fluida dapat mengalir ke permukaan, yaitu melalui metode pengangkatan buatan (artificial lift)[1]. Dalam perencanaannya dapat dilakukan dengan analisis kualitatif dan analisis kuantitatif (perhitungan) berupa besarnya laju produksi sumur. Penurunan produksi yang terjadi pada sumur sembur alam L5A-X struktur Niru hanya mencapai 41,67 BOPD [2]. Oleh sebab itu dibutuhkan metode pengangkatan buatan agar sumur dapat berproduksi secara optimal. Metode artificial lift yang dipilih adalah menggunakan sucker rod pump. Pemilihan alat ini dilakukan berdasarkan laju produksi sumur yaitu, melalui analisis kurva inflow performance relationship (IPR). Dari hasil análisis kurva IPR sumur L5A-X struktur Niru masih produktif untuk menghasilkan fluida yaitu sebesar 594,12 BFPD. Untuk merencanakan setiap komponen-komponen pompa maka dilakukan perhitungan secara teoritis. Hasil perhitungan optimasi pompa untuk sumur L5A-X jenis pompa yang digunakan adalah tipe pompa Tubing Heavy Wall Barrel (TH). Parameter pemilihan pompa, yaitu diameter plunger sebesar 2 ¼ in dan diameter tubing 2 7/8 in. Dengan merencanakan kecepatan pemompaan 7 SPM, panjang langkah pemompaan 144 inch dan kombinasi ukuran rod yang akan dipakai, yaitu ¾ in, 7/8 in, 1in maka, diperoleh laju produksi sebesar 578,62 BFPD. Dapat disimpulkan metode yang efektif untuk sumur produksi L5A-X adalah metode artificial lift dengan menggunakan sucker rod pump

Perencanaan Squeeze Cementing Metode Balance Plug Pada Sumur “X” Dan Sumur “Y” Di Lapangan Ogan Pt.pertamina Ep Asset 2 Prabumulih

Squeeze cementing adalah penyemenan ulang yang dilakukan sebagai salah satu langkah perawatan sumur, dengan cara menempatkan cement slurry dengan volume yang relative sedikit di posisi yang diinginkan, salah satunya untuk menutup zona perforasi . Metode squeeze cementing yang digunakan dalam penelitian yaitu dengan metode balance plug. Penelitian ini dilakukan terhadap sumur X dan sumur Y dengan cara mengumpulkan data-data sumur, melakukan pengolahan data yang meliputi perhitungan design penyemenan, perencanaan prosedur penyemenan, pengujian hasil penyemenan dengan melakukan tag cement dan uji compressive strength. Hasil penelitian didapatkan bahwa saat dilakukan injectivity test sumur X mengalami loss sehingga perlu dilakukan perencanaan penyemenan ulang karena perencaanaan yang telah dibuat tidak dapat diaplikasikan. Hasil perencanaan ulang didapat bahwa volume semen harus ditambah, dari 6,258 barrel menjadi 8,38 barrel. Sementara sumur Y dalam keadaan normal dan design cementing yang sudah dibuat dapat diterapkan pada sumur. Pada sumur Y dilakukan hesitation dengan tekanan 1.000, sedangkan pada sumur X tidak dilakukan hesitation . Setelah Waiting on cement, dilakukan tag cement, hasil dari tag cement memperkirakan slurry yang masuk zona perforasi sumur X yaitu sebanyak 1,47 barrel dan sumur Y sebanyak 1,77 barrel. Sedangkan uji compressive strength pada semen dilakukan dengan memberi tekanan 600 psi selama 10 menit, dan menunjukkan tekanan tidak turun yang berarti tekanan hasil penyemenan tidak bocor. Sehingga dapat disimpulkan squeeze cementing berhasil menutup zona perforasi sumur X dan sumur Y

The relationship between dental caries and dental fluorosis in low, moderate and high fluoride areas of Udaipur district, India.

Objective: The purpose of the study was to assess the relationship between dental caries and dental fluorosis in Bhil Tribes living in Udaipur district India, known for endemic fluorosis. Method: A total of 420 Bhil tribes selected from areas with low (0-1.5mg/l), moderate (1.5-3.0mg/l) and high (>3mg/l) water fluoride concentration were interviewed and examined for caries and dental fluorosis. Dental caries and fluorosis were recorded according to the DMFT system and Dean Fluorosis index. All the Bhil tribes were exposed to a written questionnaire, constructed in English and translated into local language and – for control purposes – translated back to English. Intra-oral examination was conducted using by two examiners. Result: Bhil, Garasia, Meena and Gameti were most commonly present castes among Bhil tribes. The prevalence of dental fluorosis was 33.1% in low, 33.3% in moderate and 33.6% in high fluoride areas. In the low fluoride area mean number of decayed teeth and mean DMFT was 5.52 and 7.37 respectively while in high fluoride area it was higher, mean decayed and mean DMFT was 9.27 and 12.06 respectively. There was significant difference in mean DMFT between low, moderate andthe high fluoride areas (P = 0.00). DMFT score was 12.04 in severe fluorosis cases while it was 8.67 in normal fluorosis cases. There was significant difference in mean DMFT between all four castes (Bhil, Garasia, Meena and Gameti). Conclusion: Dental caries increases with increasing severity of dental fluorosis in low, moderate and high fluoride areas. Thus, a positive relationship between dental caries and dental fluorosis was observed in all the three areas. Key words: Dental caries, Fluorosis, Bhil tribes