Judul: Nilai Hambur Balik Lamun Enhalus acoroides di Perairan Pulau Panggang
Abstrak: Enhalus acoroides is one species of aquatic vegetation which existence is threatened. Therefore be requiered monitoring of seagrass. Acoustic method is a technology that efficient in detecting marine vegetation. This research has examines measurements values of seagrass Enhalus acoroides backscatter in Panggang island. This measurement using hydroacoustic instrument Cruz Pro, which took place in April-November 2013. The Result of echogram show differences in bottom waters with seagrass in the water column. Backscatter value range of seagrass E. acoroides is (-58.47) - (-48.02) dB. The average value of each transect backscatter seagrass vegetation is -49.70 dB, -49.63 dB, -49.46 dB and -53.70 dB. Backscatter value of bottom waters with sand dominan category of fine sand on is (-26.93) - (-23.72) dB. The results show there is a connection between backscatter value of seagrass with densities in seagrass E. Acoroides.
Keyword: backscattering,, hydroacoustic, Panggang Island, Enhalus acoroides, Seagrass

Judul: Backscattering of Seagrass Enhalus acoroides Based Grazing Angle Using Simrad EK 15 in Teluk Bakau
Abstrak: Lamun Enhalus acoroides merupakan tumbuhan berbunga yang beradaptasi di perairan dangkal dan pengambilan data dilakukan di Teluk Bakau. Pemantauan lamun di perairan laut dangkal menggunakan sistem akustik memiliki keterbatasan akibat adanya pengaruh (near field). Pengukuran nilai hambur balik akustik lamun En ac menggunakan Simrad EK 15 yang dioperasikan agar membentuk sudut pemeruman (0o, 15o, 30o ,45o, 60o dan 75o) antara transduser dan dasar perairan yang ditumbuhi padang lamun. Tujuan penelitian adalah menganalisis nilai hambur balik lamun Enhalus acoroides dengan sudut pemeruman (grazing angle) yang berbeda. Pengambilan data sebanyak 3 Stasiun dengan percent cover standart Stasiun 1 sebesar 40%, Stasiun 2 sebesar 28% dan stasiun 3 sebesar 70%. Rata-rata terbesar hambur balik lamun terdapat pada sudut 0o, 15o, 30o dan 45o. Analisis regresi logaritmik sudut 45o menjadi sudut rekomendasi dengan mengasilkan R2 =0.956 dan hasil pemeruman data lamun sudut 5,50 menghasilkan data yang bagus. Hasil uji beda nilai tengah menghasilkan sudut 300, 600 dan 750 sebagai sudut rekomendasi. Sudut 300 dapat dijadikan sudut rekomendasi dalam pengambilan data lamun secara akustik di perairan dangkal untuk mengurangi near field., Seagrass Enhalus acoroides is a flowering plant that adapts to shallow waters and data retrieval was carried out in Teluk Bakau. Seagrass monitoring uses an acoustic system, in recording acoustic data in shallow waters still has limitation due to (near field). Measurement of the acoustic backscatter value of seagrass En ac using Simrad EK 15 which is operated to form a hearing angle (0o, 15o, 30o ,45o, 60o dan 75o) between the transducer and the bottom of the waters overgrown with seagrass. The purpose of this study was to analyze the backscatter value of the seagrass En ac with different grazing angles. Data retrieval is 3 stations with a percent cover standard of station 1 is 40%, station 2 is 28% and station 3 is 70%. The max average result of seagrass SV based at an angle 0o, 15o, 30o dan 45o. Logarithmic regression analysis that an angle of 45o becomes recomended angle by producting R2=0,956 and the result of sounding seagrass data with polinomials that 5,50 produced good data. The results of the different mean value test produce angles of 300, 600 and 750 as the recommended angles. The angle of 300 can be used as a recommendation angle in acoustic seagrass data collection in shallow waters to reduce near field.
Keyword: seagrass, backscattering, grazing angle, percent cover standart

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
Keyword: