Judul: Sistem filtrasi akuarium air laut untuk pengendalian senyawa nitrogen dalam air
Abstrak: Sistem filtrasi merupakan bagian terpenting dari sistem akuarium air laut, fungsinya untuk tetap menjaga kualitas air laut yang digunakan sesuai dengan yang dibutuhkan. Alat yang digunakan untuk melakukan proses filtrasi disebut dengan filter atau sump.
Keyword: 

Judul: Teknik Perbaikan Filter Fisik Dan Filter Kimia Pada Sistem Resirkulasi Pembenlhan Ikan Patin (Pangasius Hipophtlwlmus)
Abstrak: Pembenihan ikan Patin dalam aquarium bertujuan untuk meminimumkan tingkat kematian memerlukan pengontrolan terhadap parameter-parameter yang berpengaruh terhadap kondisi ikan.Parameter tersebut antam lain kandungan pH., N03, N02, DO,dan NH3. Kelima faktor kimia tersebut sangat mempengaruhi kualitas air. Air sebagai lingkungan abiotik diresirkulasi secam tertutup. Sistem resirkulasi ini dibagi kedalam empat bagian yaitu bak pemeliharaan, filter mekanik, filter biologi, dan filter kimia.Filter mekanik dan filter biologi dijadikan satu bagian dengan susunan dari atas kebawah : ijuk, busa (filter mekanik), pasir, kerikil,dan zeolit (filter biologi). Perbandingan susunan masing-masing 2:1:3:2:LKetinggian filtmsi sebesar duapertiga dari total tinggi bak saringan. Kerusakan filter mekanik diindikasikan dengan meluapnya air dibak saringan pada tenggang waktu tertentu, Hal ini disebabkan oleh menumpuknya kotoranJpartikel organik berukuran besar sehingga menyumbat filter. Waktu yang tepat untuk mengganti filter tersebut diduga dengan menggunakan rumus Inhibited Population Model dengan mengetahui terlebih dulu nilai faktor retardasi (y) dan koefisien u. Tanaman kangkung air digunakan sebagai filter kimia yang berfungsi untuk mereduksi konsentmsi nitrat hasil dari biofilter. Diperlukan panjang akar rata-rata kangkung yang optimal supaya mencapai konsentrasi nitrat yang diijinkan. Reduksi konsentrasi nitrat dinyatakan dalam persen. Koefisien u dan y pada persamaan Inhibited PopUlation Model dipecahkan terlebih dulu menggunakan rumus Least Square Methode, Newton Raphson, Jacobian Matrik, dan Gaus Jordan. Berdasarkan hasil penelitian diperoleh kualitas air yang ideal bagi pembenihan ikan patiCl yaitu pH = 6.91, NH3 = 0.626 ppm, DO = 5.65 ppm, dan NO) = 0.632 ppm, N02 = 0.52 ppm. Pada pendugaan wak'tu yang tepat untuk penggantian filter diperoleh nilai faktor retardasi = 0.048 dan koefisien a = 2 Sedangkan panjang akar rata-rata kaTIgiwng yang optimum dapat riiperoieh menggunakan software Borland Delphi 6.0 dengan input konsentrasi nitrat awal dan konsentrasi nitrat yang diijinkan, koefisien a = 2 dan y = 0.2.
Keyword: 

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.
Keyword: