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13 August 2010

Prekursor Ionosfer Gempabumi dari Anomali Variasi Harian

Prekursor Ionosfer Gempabumi dari Anomali Variasi Harian
GPS TEC Ionosfer
Buldan Muslim1), Sarmoko Saroso1), The Houw Liong2)
Hasanuddin Z. A.3), dan Wedyanto3)
1)National Institute of Aeronautucs and Space (LAPAN), Bandung, Indonesia
2)Dept. of Physics, Bandung Institute of Technology, Bandung Indonesia
3)Geomagnetic and Geodesy Group, Bandung Institute of Technology, Bandung, Indonesia

Abstract
Total elektron content ionosfer (TEC) dapat diperoleh dari sebuah observasi dasar Global Positioning System (GPS). Kumpulan GPS terdiri dari 24 jumlah satelit., yang terdistribusi pada 6 orbit mengelilingi bumi pada ketinggian ~20200 km. masing-masing satelit menstranmisikan sinyal pada dua frekuensi (f1 = 1575,42 MHz dan f2 = 1227,60 MHz) dengan dua kode yang berbeda, C/A dan P(Y) dan dengan dua fase pengangkut yang berbeda, L1 dan L2. Karena ionosfer adalah sebuah medium yang menyebar, kecepatan perambatan gelombang elektromagnetik ditransmisikan oleh satelit GPS tergantung pada frekuensi gelombang radio. Kenaikan fase pengangkut dan keterlambatan pengelompokan sinyal GPS di ionosfer adalah sebanding dengan elektron content terintegrasi sepanjang perambatan garis edar satelit. Berdasarkan fase pengangkutan dan kode data pseudorange pengamatan oleh penerima GPS berlokasi di sekitar Indonesia, kami memperoleh TEC ionosfer meggunakan metode fase levelling. Tujuan menemukan hubungan anomali variasi harian dengan gempa-gempa besar di Indonesia dan area sekitarnya, kami menggunakan analisis harmonik dari pengamatan TEC pada beberapa stasiun GPS. Hasil dari analisis harmonik menampakkan bahwa amplitudo variasi harian dari TEC mengalami penurunan (anomali negatif) atau peningkatan (anomali positif) beberapa hari setelah gempa utama, dan mengggunakan analisis spasial dari anomali amplitudo, magnitude beberapa gempa besar dapat diperkirakan. Kemungkinan mekanisme anomali variasi harian GPS TEC ionosfer akan didiskusikan juga.

MODEL 1-D PERTUMBUHAN BUTIRAN AWAN KONVEKSI DI DAERAH BANDUNG

Master Theses from #PUBLISHER# / 2005-09-15 18:13:19
MODEL 1-D PERTUMBUHAN BUTIRAN AWAN KONVEKSI DI DAERAH BANDUNG

By: Plato Martuani Siregar
Advisor : Prof. Dr. The Houw Liong
Prof. Dr. Bayong Tj.H.K.

S2 - Oceanography and Atmospheric Sciences
Created: 2000-01-00 , with 1 file(s).

Keywords:
Convection process, cloud droplet

Subject:
Clouds - Meteorology

Heading:
Earth science


Abstrak:
Model kopel pertumbuhan butiran awan dibentuk dari penurunan persamaan dinamika, termodinamika, dan fisis awan dengan menganggap bahwa uap air berada diantara dua plat sejajar yaitu permukaan bumi dan lapisan tropopause. Kecepatan arus ke atas di kedua permukaan plat adalah nol. Faktor konvergensi,adveksi horizontal, turbulensi,gerak vortisitas arus ke atas,dan wujud es diabaikan, sehingga dapat dibuat model numerik satu dimensi untuk pertumbuhan awan konveksi. Kelemahan model ini sangat sensitif terhadap syarat awal.

Untuk tumbuh menjadi butiran, maka uap harus memiliki kelembaban yang tinggi agar dapat melawan efek kelengkungan hingga mencapai nisbah jenuh kritis 0.6%. Jadi perlu ditambahkan amonium sulfat untuk menaikkan nisbah jenuh hingga jari jari 0.13 mikrometer, setelah nisbah jenuh kritis terpenuhi, butiran akan tumbuh meskipun kelembaban jenuh mendekati satu. Disamping pengaruh larutan garam pertumbuhan butiran juga dipengaruhi oleh pemanasan konduksi dan diffusi penguapan hingga jari jari sekitar 10 mikrometer.

Sebagian besar radiasi matahari terserap di permukaan bumi yang berakibat pemanasan di permukaan. Dengan demikian lapisan di permukaan bumi lebih panas sehingga menimbulkan paket udara tidak stabil dan mengalami proses konveksi. Suhu paket udara menurun bila terangkat ke atas, hal ini diakibatkan proses adiabatik. Proses perubahan wujud uap air menjadi butiran awan akan melepas panas laten saat terjadi kondensasi. Laju penurunan suhu pada permukaan ditentukan oleh keseimbangan uap air di atmosfer. Digunakan data radio sonde stasiun LAPAN Bandung tahun 1992-1996 sebagai penerapan model sekaligus verifikasinya. Kemudian model digunakan untuk menaksir perubahan arus ke atas, profil suhu paket udara, nisbah tetes hujan, dan nisbah kadar total air di atmosfer.
Proses konveksi adalah faktor yang berperan dalam proses pembentukan butiran awan. Jika teijadi pembentukan awan dapat menimbulkan variasi pada suhu dan nisbah kadar air atmosfer. Hal ini terlihat bahwa variasi suhu 1.5 km di atas Bandung lebih besar dibandingkan dengan dekat permukaan. Pada ketinggian ini terdapat awan yang dapat menyerap radiasi matahari, terjadinya arus, dan pemisahan kutub listrik di dalam awan itu sendiri, sehingga memberi efek pada variasi suhu paket udara.

Translation:

Abstract:
Couple model of droplet growth is developed by three kinds of processes, which are dynamic, thermodynamic, and cloud physics that assume water vapor is present between ground surface and tropopause layer. Updraft in boundary condition is zero. Factor of convergence, lateral advection, turbulent montion, updraft vorticity, and ice phase are neglected, then developed numerical modeling in one dimention of the formation, of droplet growth. This model is very sensitive to initial conditons.
The formation of droplet growth requires high supersaturated vapor to oppose curvature term. For the saturation ratio at relative humidities less than 100 %, droplet growth will be blocked by curvature term, so it needs addition of amonium sulfat solution to an air parcel until droplet radius 0.13 micrometer, after critical saturation ratio is formed, droplet will grow although relative humidities approach one. On the other hand,solution effect growth is increased by heat conduction and vapor diffusion becomes droplet of radius around 10 micrometer.

A major part of solar radiation have absorbed by the surface of the earth. The atmosphere then becomes unstable due to the heating around ground,and thus convection is generated in the troposphere. The temperature of an air parcel moving upward decreases because of the adiabatic expansion,while water vapor in the air is warmed when it condenses. The temperature lapse rate in the troposphere is thus determined by balance of water vapor in the atmosphere. Using ratio sonde data at LAPAN Bandung period in the 1992-1996 to optimize model trend and do verification, after that modeling can be used to estimate updraft rate, pacel temperature, rain mixing ratio, and mixing ratio of the condensed water in the atmosphere.
Convection process is determined in cloud droplet growth. The formation of cloud causes give temperature variations and mixing ratio in atmosphere. It can be seen that temperature variations in the level of 1500m over Bandung is larger than near ground. In this level, the cloud will be formed to absorb solar radiation, current air in cloud and separation of electrical dipole of water moleculer which will give temperature variation of air parcel.

Copyrights:

Copyright © 2005 ITB Central Library,
Jl. Ganesha 10 Bandung, 40132, Indonesia.
Verbatim copying and distribution of this entire article is permitted by author to ITB Central Library in any medium, provided this notice is preserved

05 August 2010

Measuring Quality of Black Tea From Theaflavins Analysis Using Secondary Measurement

International Conference on Instrumentation, Communication and Information Technology (ICICI) 2005 Proc., August 3 -5 , 2005, Bandung, Indonesia

Measuring Quality of Black Tea From Theaflavins Analysis Using Secondary Measurement Melania S. Muntini1), Yul Y. Nazaruddin2), The Houw Liong 3), Lienda Handojo4)
1) Department of Physics, Institut Teknologi Sepuluh Nopember (ITS) Surabaya, Indonesia
2) Department of Engineering Physics, Institut Teknologi Bandung, Indonesia
3) Department of Physics, Institut Teknologi Bandung, Indonesia
4) Department of Chemical Engineering, Institut Teknologi Bandung Jl. Ganesa 10 Bandung 40132, Indonesia
Phone/Fax: +62-22-2508138
E-mail: melania@students.tf.itb.ac.id, yul@tf.itb.ac.id

Abstract – Theaflavins (Tf) is a key compound that significantly contributes in the quality of black tea. It undergoes a series of chemical changes during the fermentation process. Fermentation is one of the most critical processes in black tea processing. There are many parameters that significantly influenced the process including room temperature, thickness of greendhool, and duration of the process. In general, it is difficult to measure theaflavins directly as it involves some chemical analysis and enzymes for pigment. An alternative approach, theaflavins is measured indirectly and inferred from easily made process measurements or secondary measurements. This inferential method of measurements employs a scheme which is called a virtual sensor, which is realized by integrating artificial neural networks with the Extended Kalman Filter algorithm. Secondary variables are several parameters of fermentation process and results of color analysis of tea liquid, whereas primary variable is Theaflavins. The data for implementing this proposed technique were obtained by conducting several real-time experiments at black tea factory in Indonesian Tea and Cinchona Research Institute (PPTK Gambung), West Java. Results show how the quality of black tea can be infered indirectly using the proposed technique.The mean and variance of error between the obtained output of virtual sensor algorithm and the output chemical analysis of theflavins were 1,81 x 10^-4 and 5,07 x 10^-6 respectively .
Keywords – artificial neural network, black tea, Extended Kalman Filter, indirect measurements, Theaflavins, virtual sensor

04 August 2010

Solar Effects on Weather and Climate

Proceedings of The 9th Asian-Pacific Regional IAU Meeting 2005, 79–80 (2005)
Solar Effects on Weather and Climate
in the Indonesian Archipelago
H. L. The1, P. M. Siregar2, and I. Radiman.3
1Department of Physics, Institut Teknologi Bandung, Indonesia
2Department of Geophysics and Meteorology, Institut Teknologi Bandung, Indonesia
3Department of Astronomy and Bosscha Observatory, Institut Teknologi Bandung, Indonesia

ABSTRACT
From various stations at Geographic Latitudes from 6.0 N to 10.0 S throughout the Indonesian Archipelago, anomalies of yearly rainfall were collected and plotted to those of the yearly Sunspot Number between 1948 and 2003. It is shown that there is a tight correlation between solar activity and the various geophysical variables, such the cloud cover, the sea surface temperature and the rainfall throughout the region. The Number of Sunspot to Rainfall from each station against the Geomagnetic Latitude of the stations is also studied. The coefficients of correlations increase as we go to higher Geomagnetic Latitudes. This research shows that the knowledge of solar activities can be used to predict extreme weather in Indonesia.
Key words: solar cycles – geomagnetic effects – solar activity – extreme weather