ABSTRACT:The Landsat-8 satellite imagery is now highly developed compares to the former of Landsat projects. Both land and water area are possibly mapped using this satellite sensor. Considerable approaches have been made to obtain a more accurate method for extracting the information of water area from the images. It is difficult to generate an accurate water quality information from Landsat images by using some existing algorithm provided by researchers. Even though, those algorithms have been validated in some water area, but the dynamic changes and the specific characteristics of each area make it necessary to get them evaluated and validated over another water area. This paper aims to make a new algorithm by correlating the measured and estimated TSS and Chla concentration. We collected in-situ remote sensing reflectance, TSS and Chl-a concentration in 9 stations surrounding the Poteran islands as well as Landsat 8 data on the same acquisition time of April 22, 2015. The regression model for estimating TSS produced high accuracy with determination coefficient (R 2 ), NMAE and RMSE of 0.709; 9.67 % and 1.705 g/m 3 respectively. Whereas, Chla retrieval algorithm produced R 2 of 0.579; NMAE of 10.40% and RMSE of 51.946 mg/m 3 . By implementing these algorithms to Landsat 8 image, the estimated water quality parameters over Poteran island water ranged from 9.480 to 15.801 g/m 3 and 238.546 to 346.627 mg/m 3 for TSS and Chl-a respectively.

ABSTRACT:The Sea Surface Temperature (SST) retrieval from satellites data Thus, it could provide SST data for a long time. Since, the algorithms of SST estimation by using Landsat 8 Thermal Band are sitedependence, we need to develop an applicable algorithm in Indonesian water. The aim of this research was to develop SST algorithms in the North Java Island Water. The data used are in-situ data measured on April 22, 2015 and also estimated brightness temperature data from Landsat 8 Thermal Band Image (band 10 and band 11). The algorithm was established using 45 data by assessing the relation of measured in-situ data and estimated brightness temperature. Then, the algorithm was validated by using another 40 points. The results showed that the good performance of the sea surface temperature algorithm with coefficient of determination (R 2 ) and Root Mean Square Error (RMSE) of 0.912 and 0.028, respectively.

Abstract. Vertical-axis hydrokinetic turbines with fixed pitch blades typically suffer from poor starting torque, low efficiency and shaking due to large fluctuations in both radial and tangential force with azimuth angle. Maximizing the turbine power output can be achieved only if the mechanism of generation of the hydrodynamic force on the blades is clearly identified and tools to design high-performance rotors are developed. This paper describes an initial experimental investigation to understand more of the performance on vertical-axis turbine related to the effect of fixed-pitch and passive variable-pitch application using airfoil NACA 0018. Comparative analysis according to aspects of rotation and tip speed ratios was discussed. Information regarding the changes of foil position in passive variable-pitch during rotation at a limited range of flow velocity variations test was obtained and analyzed.

AbstractTSS and Chl-a are globally known as a key parameter for regular seawater monitoring. Considering the high temporal and spatial variations of water constituent, the remote sensing technique is an efficient and accurate method for extracting water physical parameters. The accuracy of estimated data derived from remote sensing depends on an accurate atmospheric correction algorithm and physical parameter retrieval algorithms. In this research, the accuracy of the atmospherically corrected product of USGS as well as the developed algorithms for estimating TSS and Chl-a concentration using Landsat 8-OLI data were evaluated. The data used in this study was collected from Poteran's waters (9 stations) on April 22, 2015 and Gili Iyang's waters (6 stations) on October 15, 2015. The low correlation between in situ and Landsat Rrs(λ) (R 2 = 0.106) indicated that atmospheric correction algorithm performed by USGS has a limitation. The TSS concentration retrieval algorithm produced an acceptable accuracy both over Poteran's waters (RE of 4.60% and R 2 of 0.628) and over Gili Iyang's waters (RE of 14.82% and R 2 of 0.345). Although the R 2 lower than 0.5, the relative error was more accurate than the minimum requirement of 30%. Whereas, the Chl-a concentration retrieval algorithm produced an acceptable result over Poteran's waters (RE of 13.87% and R 2 of 0.416) but failed over Gili Iyang's waters (RE of 99.14% and R 2 of 0.090). The low correlation between measured and estimated TSS or Chl-a concentrations were caused not only by the performance of developed TSS and Chl-a estimation retrieval algorithms but also the accuracy of atmospherically corrected reflectance of Landsat product. Keywordsremote sensing; water quality; TSS; Chl-a.Abstrak TSS dan Chl-a secara global dikenal sebagai parameter utama dalam pemantauan kualitas air laut. Mengingat tingginya variasi temporal dan spasial dari konstituen perairan, teknik penginderaan jauh adalah metode yang efisien dan akurat untuk mengekstrak parameter fisik air tersebut. Akurasi dari parameter fisik yang diturunkan dari data penginderaan jauh tergantung pada algoritma koreksi atmosfer dan algoritma estimasi parameter fisik yang akurat. Dalam penelitian ini, akurasi dari produk USGS yang terkoreksi secara atmosfer serta algoritma yang dikembangkan untuk menghitung konsentrasi TSS dan Chl-a menggunakan Landsat 8-OLI data telah dikaji. Data yang digunakan dalam penelitian ini dikumpulkan dari Perairan Poteran (9 stasiun) pada tanggal 22 April 2015, dan Perairan Gili Iyang (6 stasiun) pada tanggal 15 Oktober 2015. Korelasi yang rendah antara data in situ dan Landsat Rrs(λ) (R 2 = 0,106) menunjukkan algoritma koreksi atmosfer yang digunakan oleh USGS memiliki keterbatasan. Algoritma estimasi konsentrasi TSS menghasilkan akurasi yang dapat diterima di Perairan Poteran (RE sebesar 4,60% dan R 2 sebesar 0,628) dan di perairan Gili Iyang (RE sebesar 14,82% dan R 2 sebesar 0,345). Meskipun R 2 lebih rendah dari 0,5, kesalahan relatifnya lebih akurat dari persyaratan minimum seb...

AbstrakPengawasan sumber daya laut terhadap tindakan pencurian menjadi salah satu tolok ukur bahwa negara dapat mempertahankan kedaulatan wilayah maritimnya. Kebutuhan kapal perang tentunya dapat mendukung kinerja TNI untuk menjalankan operasi militernya. Kendala teknis utama pada kapal perang adalah perilaku seakeeping yang relatif kurang stabil. Disisi lain perilaku slamming yang sering terjadi pada kapal berkecepatan tinggi berakibat pada kegagalan struktur pada bagian haluan kapal sehingga membahayakan keselamatan. Penelitian ini dimaksudkan untuk mengkaji desain lambung kapal perang untuk daerah operasional tertentu dimana perairan terbuka di Indonesia memiliki tinggi rata-rata gelombang sekitar 2-5 m. Pembahasan dititikberatkan pada analisa gerakan kapal (seakeeping) untuk mengetahui tingkat keamanan dan kenyamanan kapal dan kekuatan lambung untuk mengetahui ketahanan struktur dimana diakibat oleh hidroelastisitas slamming. Analisa dapat dibuktikan dengan metode numerik / komputasi dengan metode elemen hingga dan metode panel. Skenario divariasikan berdasarkan kecepatan kapal, sudut hadap, dan sea state. Dari hasil simulasi didapatkan beban slamming terjadi paling besar adalah 306,893 kPa pada gading ke 147 ketika kapal beroperasi pada sea state 7, sudut hadap 180 derajat, dan kecepatan kapal 30 knot. Tegangan yang terjadi pada konstruksi kapal masih memenuhi persyaratan tegangan izin peraturan Biro Klasifikasi Indonesia (BKI).