Judul: Perubahan Penggunaan Lahan dan Kaitannya dengan Urban Heat Island (Studi Kasus Kota Semarang, Jawa Tengah).
Abstrak: Jumlah penduduk di Kota Semarang semakin meningkat, di sisi lain permintaan lahan untuk aktivitas terbangun juga semakin meningkat, kondisi tersebut menyebabkan terjadinya peningkatan suhu permukaan yang memicu terjadinya fenomena Urban Heat Island (UHI). Penelitian ini bertujuan mengetahui hubungan antara perubahan penggunaan lahan dan fenomena UHI di Kota Semarang. Data yang digunakan meliputi data penginderaan jauh citra satelit Landsat TM5 tahun 2008 dan Landsat 8 OLI tahun 2018. Metode yang digunakan yaitu koreksi Top of Atmosphere (ToA), analisis spasial dan suhu permukaan. Hasil penelitian menunjukkan bahwa pada periode tahun 2008-2018 telah terjadi peningkatan lahan terbangun sebesar 13%, sedangkan penggunaan lahan hutan dan perkebunan mengalami penurunan sebesar 7%. Pada periode tahun 2008-2018 terjadi peningkatan suhu permukaan dari 20-320C menjadi 22-360C. Penggunaan lahan yang memiliki suhu permukaan tinggi yaitu pada lahan terbangun sebesar 26-300C pada tahun 2008 dan 30-340C pada tahun 2018, sedangkan yang terendah pada penggunaan lahan tubuh air sebesar 22-260C pada tahun 2008 dan 24-260C pada tahun 2018. Perubahan penggunaan lahan menjadi lahan terbangun mendorong meningkatnya suhu permukaan yang menyebabkan fenomena Urban Heat Island di Kota Semarang. Skenario pengurangan efek Urban Heat Island di Kota Semarang dapat dilakukan dengan 4 skenario, pertama skenario 4 (roof garden, vertical garden dan pengecatan permukaan atap berwarna cerah) pada 38% area yang dianalisis, kedua skenario 3 (perbanyakan vegetasi, roof garden dan pengecatan permukaan atap berwarna cerah) pada 24% area yang dianalisis, ketiga skenario 2 (penambahan RTH, perbanyakan vegetasi, dan roof garden) pada 21% area yang dianalisis dan keempat adalah skenario 1 (penambahan RTH, dan perbanyakan vegetasi) pada 19% area yang dianalisis.
Keyword: Perubahan Penggunaan Lahan, UHI, Penginderaan Jauh

Judul: Distribusi Spasial Suhu Permukaan dan Kecukupan Ruang Terbuka Hijau di Kota Semarang
Abstrak: Semarang is one of cities that become center of public activity which is always developing in many aspects such as settlement, , roads, industries and other infrastructures. Unfortunately, The development seems to ignore environmental sustainability, in which large of green open space are converted into other land uses. The conversion will lead micro climate changes resulted in Urban Heat Island and green house effect. Those phenomenon can be observed by utilizing Geographic Information System and remote sensing. The objectives of the research are as follows : (1) land cover type identification and surface thermal of spatial distribution, , (2) the relationship between surface thermal with Green Space capacity, open land and built areas. (3) the relationship between surface thermal with Normalized Difference Vegetation Index (NDVI), through interpretation and landsat Imaginery 7 ETM. The research area situated at in Semarang City and data used were Landsat Imaginery 7ETM path/row 120/065 acquiring on April 2001 and June 2006. Landsat imagery were analyzed using an Arc View 3.2 and ERDAS Imagine 8.5 software. Surface temperature were estimated using band 6. Those analysis were aimed to identify relationship between surface thermal with Green Space, the open land, built area and NDVI. Semarang city with 38.721.70 Ha are dominated by land cover, such as built area 27.52% on year 2001 and 35,58% in 2006. The biggest land cover changes happened on built area and with advancing is 8.06%. Thermal Surface distribution were found ranges from <20 oC - ≥34 oC. The area which have thermal surface value of ≥34 oC was expanded from 16.80 % in 2001 to 25.68% in 2006. However, green space capacity areal are still covering 30%, inline with proportion based on UU. No.26 on 2007 about areal governance. The relationship between surface thermal with Green Space and other land uses were identified. It showed that surface temperature of open space area is lower than other landuses such as bare land and settlement. Moreover, It analysis result showed that surface temperature will infllence by NDVI, in which the surface temperature will increase by the lowering NDVI and vice versa.
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Judul: The Exploration of Discrete Logarithm over Finite Field GF(3m)
Abstrak: The security of many public~key algorithms is based on the problem of finding discrete logarithms. The generalized discrete logarithm problem is the following: given a finite cyclic group G of order n, a generator a of G, and an element fl E G, find the integer x, 0 ~ x ~ n - 1, such that 0: = fl. Algorithm for discrete logarithm problem focused on Menezes et al. (1997) that consist of exhaustive search algorithm, the baby-step giant-step algorithm, Pollard's rho algorithm, Pohlig-Hellman algorithm, and index-calculus algorithm. These algorithms are explorated to be used in discrete logarithm problem over finite field GF(3m ). The exploration also produces some algorithms, i.e. naif negative algorithm, baby-step mother-step algorithm, baby-step mother free-step algorithm, and baby-step free-step algorithm. All algorithms implemented using Maple 11. The Pohlig-Hellman and baby-step giant-step algorithms are efficient enough to be used in discrete logarithm problem over finite field GF(3m ) for m < 20.
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