Judul: Pembuatan Sensor Serat Optik dengan Cladding Dye Methyl Violet untuk Mendeteksi Gas Hidrogen Sulfida
Abstrak: Serat optik adalah salah satu media transmisi yang dapat menyalurkan informasi dengan kapasitas besar dengan keandalan yang tinggi. Karena itu, serat optik banyak dimanfaatkan sebagai sensor. Penelitian ini dibuat untuk mendeteksi gas hidrogen sulfida (H2S). Gas H2S merupakan gas yang berbahaya bagi lingkungan. Gas ini pada konsentrasi 500 ppm, dapat menyebabkan kematian pada manusia. Tidak hanya pada manusia, gas ini juga berbahaya bagi tanaman dan bangunan yang bahan-bahannya seperti batu kapur, batu pualam, dan dolomit. Pada penelitian ini, probe sensor dibuat dengan mengganti cladding serat optik dengan gel yang didoping dye methyl violet. Probe sensor yang dikenai gas H2S diberi sinar masukan dari sumber sinar dan diterima oleh sensor cahaya. Data yang dihasilkan berupa kurva respon time sensor serat optik terhadap gas H2S. Semakin tinggi konsentrasi gas H2S yang dihasilkan maka semakin cepat sensor merespon gas tersebut.
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Judul: Pembuatan probe sensor serat optik untuk mengukur konsentrasi uap metanol menggunakan polianilin sebagai cladding pengganti
Abstrak: Serat optik tidak hanya digunakan sebagai kabel biasa tetapi juga dimanfaatkan untuk membuat sensor yang dikenal sebagai sensor serat optik. Sensor inibisa dibuat untuk mengukur besaran fisika, seperti suhu, tekanan, kelembaban, maupun besaran kimia seperti mengukur kandungan gas CO2, alkohol, dan lain sebagainya. Karakterisasi polianilin sebagai bahan sensor gas telah banyak dikaji dan terus diteliti secara mendalam, namun penelitian tentang hubungan antara panjang gelombang dan absorbansi terhadap waktu respon polianilin terhadap gas -gas belum banyak dikaji.
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Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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