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"ABSTRAKCentral forces play important role in the analysis of results obtained with particle simulation methods, since they allow evaluating stress fields. In this work we derive expressions for a central force decompositon of the Tersoff potential, which is often used to describe interatomic interactions in covalently bonded materials. We simplify the obtained expressions and discuss their properties. "

"Penelitian ini melakukan identifikasi lapisan shale gas menggunakan Inversi Impedansi Akustik dan Dekomposisi Spektral. Penelitian dilakukan di Lapangan "AP", Cekungan Barito dan formasi target yaitu Formasi Tanjung. Nilai Total Organic Carbon (TOC) ditentukan dengan menggunakan Passey's Number dan data geokimia. Selanjutnya, zona shale gas ditentukan dengan mengorelasikan Log Gamma-ray dengan Log Densitas, Sonic, NPHI, dan Resistivitas pada dua sumur. Hasil korelasi menunjukkan terdapat zona shale gas pada masing-masing sumur, yaitu dikedalaman 7130-7370 ft (Sumur A-1) dan 3100-3280 ft (Sumur P-1). Zona shale gas Sumur A-1 dan Sumur P-1 memiliki TOC rata-rata 5.4 wt% dan 2.8 wt%. Hasil tersebut didukung oleh hasil inversi impedansi akustik (AI) yang menujukkan nilai impedansi rendah untuk zona shale gas antara 5000-8000 m/s*g/cc (Line A-1), dan 7200-8900 m/s*g/cc (Line P-1). Selain itu, hasil tersebut juga didukung oleh hasil dekomposisi spektral yang menunjukkan anomali Continuous Wavelet Transform (CWT) tinggi pada frekuensi 18 Hz (untuk Line A-1) dan 20 Hz (untuk Line P-1). Analisis terintegrasi antara data seismik, hasil inversi AI dan CWT menunjukkan terdapat daerah potensial shale gas pada punggungan antilkin di Line A-1 dan Line P-1.

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This study identify shale gas layer using acoustic impedance (AI) and spectral decomposition. The object of this study is Field ‘AP’, Barito Basin, and the formation target is Tanjung Formation. Total Organic Carbon (TOC) values was determined using Passey’s Number and geochemical data. Furthermore, shale gas zone was determined by correlating Gamma-ray log with Density, Sonic, NPHI and Resistivity log in two wells.

Correlation result showed there are a shale gas zone in each well, which is at 7130-7370 ft (Well A-1) and 3100-3280 ft (Well P-1). Shale gas zone Well A-1 and P-1 has average TOC of 5.4 wt% and 2.8 wt%. These results are supported by calculation of AI inversion, which showed a low impedance values for shale gas zone between 5000-8000 m/s*gr/cc (Line A-1) and 7200-8900 m/s*gr/cc (Line P-1).

Besides, spectral decomposition also showed high CWT anomaly at 18 Hz (Line A-1) and 20 Hz (Line P-1). Integrated analysis of seismic data, AI, and CWT indicates there are potentials area of shale gas on the anticline ridge on Line A-1 and Line P-1."

"Penelitian telah dilakukan di kawasan hutan mangrove cagar alam Pulau Dua Serang, Banten pada bulan September hingga November 2011. Tujuan dari penelitian adalah untuk mengetahui produksi dan potensi unsur hara, serata menduga pelepasan unsur hara dari serasah ke lingkungan perairan laut. Pengambilan sampel untuk analisis vegetasi mangrove dilakukan dengan menggunakan metode transek-kuadrat. Guguran serasah ditangkap dengan littertrap dan besarnya serasah yang dilepas ke perairan laut dilakukan pengujian dengan menyaring serasah di aliran air yang menghubungkan antara hutan mangrove dengan perairan laut, untuk produksi potensial unsur hara dari serasah dilakukan analisis unsur hara (C, N, P) di laboratorium. Hasil penelitian menunjukkan bahwa jenis mangrove yang mendominasi yaitu Avicennia marina dan Rhizophora apiculata dengan kerapatan relatif sebesar 51,43% dan 36,19%. Hutan mangrove cagar alam Pulau Dua menghasilkan total rata-rata serasah sebesar 4,05 gr/m2/hari atau 14,78 ton/ha/tahun dengan penyumbang terbesar dari serasah daun. Produksi potensial unsur hara serasah yang dihasilkan sebesar 0,3456 gr-C/m2/hari atau 1,2616 ton-C/ha/tahun, 0,0091 gr-N/m2/hari atau 0,0333 ton-N/ha/tahun, 0,0008 gr-P/m2/hari atau 0,0031 ton-P/ha/tahun. Hutan mangrove cagar alam Pulau Dua turut menyumbangkan serasahnya ke perairan laut sebesar 855,4724 gr/m3/hari.

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The research has been conducted at mangrove forest of Pulau Dua conservation in Serang town of Banten province from September to November 2011. The purposes of study were to know the production and potential nutrient of mangrove litter and to expect the nutrients released into marine environment. The sample was taken by employing transect-square method. Mangrove litter avalanches were caught by litter-trap and the size was examined by filtering the litter in water flow which connected mangrove forest and marine. The potential nutrient production of mangrove litter was analyzed by administering nutrient analysis of C, N, and P in laboratory.

The findings showed that the dominating mangrove types were Avicennia marina and Rhizophora apiculata with 51.43% and 36.19%. of relative density. The mangrove forest of Pulau Dua conservation produced 4.05 gr/m2 /day litters on average total or 14.78 ton/ha/year litters, and the largest contributor was leaves. The production of litters’ potential nutrient achieved 0.3456 gr-C/m2/day or 1.2616 ton-C/ha/year, 0.0091 gr-N/m2/day or 0.0333 ton-N/ha/year, 0.0008 gr-P/m2/day or 0.0031 ton-P/ha/year. Mangrove forest of Pulau Dua conservation also contributed 855.4724 gr.day/m3 litters to marine waters."

"The central subject of the book is the generalization of Loewy's decomposition, originally introduced by him for linear ordinary differential equations, to linear partial differential equations. Equations for a single function in two independent variables of order two or three are comprehensively discussed. A complete list of possible solution types is given. Various ad hoc results available in the literature are obtained algorithmically. The border of decidability for generating a Loewy decomposition are explicitly stated. The methods applied may be generalized in an obvious way to equations of higher order, in more variables or systems of such equations."

"This book introduces audio watermarking methods in transform domain based on matrix decomposition for copyright protection. Chapter 1 discusses the application and properties of digital watermarking. Chapter 2 proposes a blind lifting wavelet transform (LWT) based watermarking method using fast Walsh Hadamard transform (FWHT) and singular value decomposition (SVD) for audio copyright protection. Chapter 3 presents a blind audio watermarking method based on LWT and QR decomposition (QRD) for audio copyright protection. Chapter 4 introduces an audio watermarking algorithm based on FWHT and LU decomposition (LUD). Chapter 5 proposes an audio watermarking method based on LWT and Schur decomposition (SD). Chapter 6 explains in details on the challenges and future trends of audio watermarking in various application areas."

"Dekomposisi spektral telah diaplikasikan untuk interpretasi data seismik 3D dalam meningkatkan resolusi, meningkatkan visualisasi stratigrafi, memprediksi ketebalan lapisan tipis, mengurangi noise, dan mendeteksi langsung keberadaan hidrokarbon. Beberapa metode yang telah digunakan untuk melakukan dekomposisi spektral amplitudo antara lain: DFT (Discrete Fourier Transform), EMD (Empirical Mode Decomposition), CWT (Continuous Wavelet Transform) dan MPD (Matching Pursuit Decomposition).Pada kasus ini, Metode Empirical Mode Decomposition digunakan untuk mendekomposisi suatu sinyal utama menjadi beberapa sub-sinyal yang bervariasi, yang memiliki berbagai macam frekuensi. Beberapa sub-sinyal tersebut biasa disebut IMF (Interinsic Mode Function). Kemudian dilakukan Hilbert Transform untuk setiap IMF.Hasil yang didapatkan dari proses Spectral Decomposition dengan metode Empirical Mode Decomposition menunjukan distribusi channel pada daerah Stratton Texas terlihat cukup baik dan memiliki resolusi yang lebih baik dibandingkan metode konvensional seperti FFT.

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Spectral Decomposition has been applied to the interpretation of 3D seismic data to enhance resolution, improved visualization of stratigraphic features, thickness estimation for thin beds, noise suppression, and direct hydrocarbon indication. There are variety of spectral decomposition methods. These include the DFT (Dicrete Fourier Transform), EMD (Empirical Mode Decomposition), CWT (Continuous Wavelet Transform) and MPD (Matching Pursuit Decomposition).

In this study, Empirical Mode Decomposition method is used to decompose a main signal into several sub signal, which has many types of frequencies. Some subsignals are usually called IMF(Interinsic Mode Function). Then do the Hilbert transform to each IMF.

The results of spectral decomposition with EMD method can show channel distribution in Stratton Texas Field more clearly and have better resolution than conventional methods such as FFT."