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All Journal Jurnal Silvikultur Tropika (JST) Jurnal Ilmu dan Teknologi Kelautan Tropis Indonesian Journal of Geography JOURNAL OF COASTAL DEVELOPMENT Jurnal Matematika & Sains Journal of Mathematical and Fundamental Sciences International Journal of Advances in Intelligent Informatics JURNAL ILMIAH PENDIDIKAN FISIKA AL BIRUNI Science and Technology Indonesia Jurnal Penelitian Sains Jurnal Penelitian Pendidikan IPA (JPPIPA) Marine Research in Indonesia Jurnal Kelautan Nasional International Journal of Remote Sensing and Earth Sciences (IJReSES) Jurnal Teori dan Aplikasi Fisika Indobiosains SRIWIJAYA JOURNAL OF ENVIRONMENT Makara Journal of Science

Iskhaq Iskandar

University Of Sriwijaya

Author-ID : 289165

Agriculture, Biological Sciences & Forestry Astronomy Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Computer Science & IT Decision Sciences, Operations Research & Management Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Environmental Science Immunology & microbiology Library & Information Science Materials Science & Nanotechnology Mathematics Physics Public Health Social Sciences

Published : 31 Documents Claim Missing Document

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Dynamics of Intraseasonal Sea Level Variations Observed at Gan Island and Sibolga Iskhaq Iskandar
Jurnal Matematika & Sains Vol 14, No 3 (2009)
Publisher : Institut Teknologi Bandung

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Dynamics of intraseasonal sea level variability in the central and eastern equatorial Indian Ocean is examined using 66 months (1 January 1993 to 30 June 1998) of the observed sea level at Gan Island (0Â°41S, 73Â°E) and Sibolga (1Â°45N, 98Â°46E). The analysis shows that the intraseasonal signals of 20-100-day at those two tidal stations are coherent and exhibit eastward energy propagation. These intraseasonal variations are associated with the propagation of equatorial Kelvin waves generated by the zonal winds along the equator. The lag-correlation analysis reveals that their phase speed is closed to the theoretical phase speed of the first and second baroclinic modes of the Kelvin waves.

30â75-day Sea Level Variations in The Equatorial Indian Ocean as Observed by Satellite Altimeter Iskhaq Iskandar
Jurnal Matematika & Sains Vol 16, No 1 (2011)
Publisher : Institut Teknologi Bandung

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Basin-wide structure of intraseasonal sea level variations in the equatorial Indian Ocean is investigated using satellite altimeter data. The spectral analysis reveals that the intraseasonal sea level variations are dominated by the 30-75-day oscillations. The spatial amplitude structures of the intraseasonal sea level inferred from the complex empirical orthogonal function (CEOF) analysis show a typical structure of equatorial Kelvin and off-equatorial Rossby waves. Moreover, the spatial phase structures of the CEOF mode reveal eastward propagating signal. The estimated phase speed does not correspond exactly to that of one particular baroclinic modes though it falls within the range expected for the first three baroclinic modes in the Indian Ocean. This may suggest that the propagating signals do not involve a single baroclinic mode, but instead the first, second and possibly higher baroclinic modes.

ANOMALOUS OCEANIC CONDITIONS IN THE TROPICAL INDIAN OCEAN DURING 2006 AS REVEALED BY MULTI-SATELLITE SENSORS Iskandar, Iskhaq
Marine Research in Indonesia Vol 34, No 2 (2009)
Publisher : Research Center for Oceanography - Indonesian Institute of Sciences (LIPI)

A positive Indian Ocean Dipole (IOD) took place in the tropical Indian Ocean during 2006. The evolution of this event started in July 2006 and intensified during August 2006. It was indicated by negative sea surface temperature anomalies, lower than normal sea level and supressed convection in the southeastern equatorial Indian Ocean in contrast to western counterpart. Peak negative SST anomalies exceeding 1Â°C were observed in the eastern basin during September-November coinciding with anomaous easterly winds along the equator and strong southeasterly winds along the coast of Sumatra and Java. The expression of this positive IOD was also seen in other physical variables: negative sea surface height anomalies about 30 cm and negative rainfall anomalies exceeding 8 mm/day were observed in the eastern basin. The events was terminated in December 2006 mainly due to warming of the eastern pole. The magnitude of this event determined by the east-west temperature gradient across the tropical Indian Ocean was the third largest in the last 30 years, after 1997 and 1994 events.

Spatial and Temporal Variability of Sea Surface Height in the Southeastern Tropical Indian Ocean Based on the Satellite Altimeter Data Iskandar, Iskhaq; Mardiansyah, Wijaya; Setiabudidaya, Dedi
Jurnal Matematika dan Sains Vol 19 No 2 (2014)
Publisher : Institut Teknologi Bandung

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Sea surface height (SSH) data from merged-satellite observations (e.g. TOPEX/Poseidon, JASON and ERS) were used to evaluate the spatial and temporal variations of sea surface circulations in the southeastern tropical Indian Ocean (SETIO). A Complex Empirical Orthogonal Function (CEOF) was used to extract the dominant mode of variability in the SETIO region. The results show that the first mode accounts for 41.2% of the total variance dominates the variation. The second mode accounts for 18.2% of the total variance, while the third and the fourth modes explain 6.5% and 2.6% of the total variance, respectively. The spectrum analysis indicates that the 35-day variations is a prominent feature in all CEOF modes. Furthermore, semiannual variation at period of about 180-day was observed in the first third modes, while the annual variation of about 300-day was only observed in the first two modes. A relatively strong variation at period of around 500-day was observed in the first, second and fourth modes. It is suggested that the spatial and phase pattern of the first and third modes are related to the propagation of the Kelvin waves generated by wind stress over the equatorial Indian Ocean. On the other hand, the second was likely related to the local upwelling and downwelling generated by the seasonal changes in the alongshore winds. Furthermore, the fourth mode represents the oceanic eddy generated from the downstream straits of the Indonesian Throughflow.Variasi Spasial dan Temporal Tinggi Muka Laut di Wilayah Tropis Samudera India Bagian Tenggara Berdasarkan Data Satelit AltimetriAbstrak Data tinggi permukaan laut hasil observasi dari beberapa satelit (yaitu: TOPEX/Poseidon, JASON dan ERS) digunakan untuk evaluasi variasi spasial dan variasi temporal sirkulasi permukaan laut di wilayah tropis Samudera Hindia bagian tenggara. Analysis dilakukan menggunakan metode Complex Empirical Orthogonal Function (CEOF) untuk mendapatkan mode variasi yang dominan di wilayah ini. Hasil analisis menunjukkan bahwa mode CEOF pertama menjelaskan 41,2% dari variasi total dan merupakan mode yang paling dominan. Mode CEOF kedua mengandung 18,2% dari variasi total, sedangkan mode ketiga dan keempat menjelaskan masing-masing 6,5% dan 2,6% dari variasi total. Analisis spektrum terhadap deret waktu masing-masing mode CEOF menunjukkan bahwa variasi dalam skala 35 hari merupakan variasi yang signifikan untuk setiap mode. Selanjutnya, variasi setengah-tahunan dengan periode osilasi sekitar 180 hari terekam pada tiga mode pertama, sementara variasi tahunan dengan periode osilasi sekitar 300 hari hanya terekam pada mode pertama dan mode kedua. Variasi yang cukup kuat pada periode osilasi sekitar 500 hari terekam pada mode pertama, mode kedua dan mode keempat. Hasil analisis ini juga menunjukkan bahwa pola spasial dan fase gelombang pada mode pertama dan mode ketiga adalah terkait dengan penjalaran gelombang Kelvin yang dibangkitkan oleh stres angin di wilayah ekuator Samudera Hindia. Sementara itu, mode kedua terkait dengan proses upwelling dan downwelling yang dibangkitkan oleh angin muson di sepanjang pantai. Selanjutnya, mode keempat merepresentasikan oceanic eddy yang terbentuk dari selat-selat arus lintas Indonesia (ARLINDO). Kata kunci: Complex empirical orthogonal function, Analisis Fourier, Samudera Hindia, Tinggi permukaan laut.

ANOMALOUS OCEANIC CONDITIONS IN THE TROPICAL INDIAN OCEAN DURING 2006 AS REVEALED BY MULTI-SATELLITE SENSORS Iskandar, Iskhaq
Marine Research in Indonesia Vol 34 No 2 (2009)
Publisher : Research Center for Oceanography - Indonesian Institute of Sciences (LIPI)

A positive Indian Ocean Dipole (IOD) took place in the tropical Indian Ocean during 2006. The evolution of this event started in July 2006 and intensified during August 2006. It was indicated by negative sea surface temperature anomalies, lower than normal sea level and supressed convection in the southeastern equatorial Indian Ocean in contrast to western counterpart. Peak negative SST anomalies exceeding 1°C were observed in the eastern basin during September-November coinciding with anomaous easterly winds along the equator and strong southeasterly winds along the coast of Sumatra and Java. The expression of this positive IOD was also seen in other physical variables: negative sea surface height anomalies about 30 cm and negative rainfall anomalies exceeding 8 mm/day were observed in the eastern basin. The events was terminated in December 2006 mainly due to warming of the eastern pole. The magnitude of this event determined by the east-west temperature gradient across the tropical Indian Ocean was the third largest in the last 30 years, after 1997 and 1994 events.

Penentuan Tanggapan Frekuensi Rangkaian Pengatur Nada Baxandall Pasif Berbantuan Komputer Iskhaq Iskandar
Jurnal Penelitian Sains No 3 (1998)
Publisher : Faculty of Mathtmatics and Natural Sciences

Penentuan tanggapan frekuensi Rangkaian Pengatur Nada Baxandall Pasif bila dilakukan secara manual memerlukan pengkajian matematis yang relatif cukup rumit karena melalui perhitungan yang berulang-ulang sehingga ketelitian perhitungan akan berkurang. Dengan penelitian ini diperoleh datu software yang dapat menampilkan tanggapan frekuensi Rangkaian Pangatur Nada Baxandall Pasif yang berupa tampilan tanggapan amplitudo dan tanggapan fasa. Software yang dihasilkan dari penelitian ini akan membantu pemakai mempermudah memahami hal-hal yang berkaitan dengan masalah ini.

Aplikasi Bidirectional Assosiatif Memori (BAM) Network pada Pengenalan Model Iskhaq Iskandar
Jurnal Penelitian Sains No 10 (2001)
Publisher : Faculty of Mathtmatics and Natural Sciences

Penelitian ini bertujuan untuk menyusun suatu simulasi komputer yang dapat dipergunakan untuk menguji kemampuan memori komputer dalam mengenali suatu model tertentu berdasarkan algoritma Bidirectional Assosiatif Memori Neural Network. Model yang digunakan dalam penelitian dalam penelitian ini adalah huruf-huruf abjad yang dinyatakan dalam kode polar –1 dan +1 dalam bentuk matrik [5x3]. Hasil yang didapat dalam penelitian ini menunjukkan bahwa rancangan network yang disusun mampu mengenali model input yang diberikan walaupun model tersebut mengandung noise. Network masih tetap memberikan respon yang cukup baik untuk model input yang mengandung maksimum 4 (empat) buah noise untuk model input yang dinyatakan dalam vektor X, dan 1 (satu) buah noise untuk model input yang dinyatakan dalam vektor Y.

Validasi Areal Terbakar dengan Metode Normalized Burning Ratio Menggunkan UAV (Unmanned Aerial Vehicle): Studi Kasus Agus Dwi Saputra; Dedi Setiabudidaya; Dwi Setyawan; Iskhaq Iskandar
Jurnal Penelitian Sains Vol 19, No 2 (2017)
Publisher : Faculty of Mathtmatics and Natural Sciences

Kebakaran hutan merupakan suatu bentuk bencana yang di picu oleh faktor alam maupun faktor kelalaian ma-nusia, bencana ini mempunyai dampak terhadap aspek-aspek kehidupan masyarakat. Salah satu dampaknya adalah de-gradasi hutan dan lahan terutama keanekaragaman hayati didalamnya. Untuk dapat menyusun rencana rehabilitasi pasca kebakaran pada wilayah yang luas dibutuhkan data area terbakar yang sudah terklasifikasi tingkat keparahan terbakarnya. Pada penelitian ini akan melakukan validasi tingkat keparahan terbakar pada kebakaran tahun 2015 di kawasan hutan gambut Merang-Kepayang. Data areal terbakar diturunkan dengan metoda Normalized Burning Ratio dari Citra Landsat 8 yang menggunakan kanal Near Infra Red (NIR) dan kanal Short Wave Infra Red (SWIR), dari perhitungan metoda NBR dihasilkan nilai ambang batas keparahan terbakar yang diklasifikasikan berdasarkan rentang nilai reflektansi yaitu unburned bernilai -1.02 - 0.29 μm, low bernilai 0.29 - 0.42 μm, moderate bernilai 0.42 - 0.55 μm, dan moderate extreme 0.55 - 0.80 μm. Setelah dilakukan klasifikasi tingat keparahan terbakar, kemudian dilakukan validasi hasil klasifikasi menggunakan foto udara dari Unmanned Aerial Vehicle (UAV) dengan 31 titik pengamatan lapangan dengan ketinggian terbang rata-rata 100 m dari permukaan tanah. Validasi menggunakan confusion matrix antara nilai reflektansi dan klasi-fikasi visual foto udara. Hasil validasi menyatakan bahwa akurasi keseluruhan adalah 70.97 % artinya tidak ditemukan perbedaan yang signifikan antara nilai indeks NBR dan klasifikasi lapangan. Dan juga nilai Koefisen Kappa 0.59 yang berarti hasil klasifikasi tersebut mampu mampu menghindari 59.2% kesalahan yang akan muncul pada klasifikasi lapangan.

Monthly rainfall prediction based on artificial neural networks with backpropagation and radial basis function Ian Mochamad Sofian; Azhar Kholiq Affandi; Iskhaq Iskandar; Yosi Apriani
International Journal of Advances in Intelligent Informatics Vol 4, No 2 (2018): July 2018
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26555/ijain.v4i2.208

Two models of Artificial Neural Network (ANN) algorithm have been developed for monthly rainfall prediction, namely the Backpropagation Neural Network (BPNN) and Radial Basis Function Neural Network (RBFNN). A total data of 238 months (1994-2013) was used as the input data, in which 190 data were used as training data and 48 data used as testing data. Rainfall data has been tested using architecture BPNN with various learning rates. In addition, the rainfall data has been tested using the RBFNN architecture with maximum number of neurons K = 200, and various error goals. Statistical analysis has been conducted to calculate R, MSE, MBE, and MAE to verify the result. The study showed that RBFNN architecture with error goal of 0.001 gives the best result with a value of MSE = 0.00072 and R = 0.98 for the learning process, and MSE = 0.00092 and R = 0.86 for the testing process. Thus, the RBFNN can be set as the best model for monthly rainfall prediction.

COMMUNITY-BASED MANGROVE FORESTS CONSERVATION FOR SUSTAINABLE FISHERIES Syaiful Eddy; Mohammad Rasyid Ridho; Iskhaq Iskandar; Andy Mulyana
Jurnal Silvikultur Tropika Vol. 7 No. 3 (2016): Jurnal Silvikultur Tropika (Suplemen Desember)
Publisher : Departemen Silvikultur, Fakultas Kehutanan dan Lingkungan, Institut Pertanian Bogor (IPB)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29244/j-siltrop.7.3.S42-S47

The mangrove forests are a type of salt tolerant vegetation, living in tidal zones in tropical and subtropical coastalareas with unique ecosystem that have a strategic function as a connector and counterweight of terrestrial and marineecosystems. Mangrove forests are a productive ecosystem and they have complex functions, such as physical functions,biological functions and socio-economic functions. Fishery resources of mangrove forests are very productive, bothquantitatively and qualitatively, because the mangrove forests act as the natural habitat (spawning, nursery and feedinggrounds) for various species of fish, shrimps and crabs, as well as a source of germplasm and genetic pool. Mangroveforests also provide valuable ecosystem services to coastal communities, tourist attractions, nature conservation,education and research. However, these ecosystems are fragile because it is very sensitive to environmental changes,usually because anthropogenic influences; therefore, it is difficult to be restored. In addition, these ecosystems are soopenly accessible that easily exploited by humans; this can reduce its quality and quantity. Local communities who usemangrove forests and their resources may have considerable botanical and ecological knowledge about their forests.Silvofishery techniques in aquaculture are very suitable for community-based mangrove forests conservation efforts.Silvofishery is an integrated model that considers both economically benefit and conservation.Key words: mangrove conservation, sustainable fisheries, community-based

Co-Authors Aan Johan Wahyudi Adam Darmawan Afdal Agus Dwi Saputra Akmal Johan ANDY MULYANA Anna IS Purwiyanto Apriani, Yosi Arsali Arsali Azhar Affandi Azhar Kholiq Affandi Dedi Setiabudidaya Deni Okta Lestari Deni Okta Lestari Dominikus Krisna Herlambang Dwi Setyawan Eddy, Syaiful Edy Sutriyono Edy Sutriyono Fadli Syamsuddin Fena Siska Putriyani Hamdi akhsan, Hamdi Hilda Zulkifli Hilda Zulkifli Ian Mochamad Sofian Indra Yustian Keisuke Mizuno Khakim, Mokhamad Yusup Nur Kusuma, Willy Anta Lestrai, Deni Okta Melly Ariska Moh. Rasyid Ridho Mokhamad Yusup Nur Khakim Muhammad Hendri Muhammad Irfan Muhammad Irfan Muhammad Nur Nuril Azhar Pradanto Poerwono Puad Maulana Mandailing Qurnia Wulan Sari Raden Putra Rezi Apri Rozirwan . Sabaruddin Kadir Sabaruddin Sabaruddin SABARUDDIN, . Septi Hermialingga Supari Supari Supari Supari Syaiful Eddy Wijaya Mardiansyah Wijaya Mardiansyah Wijaya Mardiansyah Wijaya Mardiansyah Wijaya Mardiansyah Wijaya Mardiansyah, Wijaya Yukio Masumoto Zulfikhar Zulfikhar Zulfikhar, Zulfikhar Zulkifli Dahlan

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