Judul: Metode Pemulus dengan Regresi Tertimbang Lokal Kekar
Abstrak: Kajian ini bertujuan untuk membandingkan garis regresi yang diperoleh melalui metode OLS (Drdinrrry Least Square)dengan suatu metode kekar terhadap pengingkaran anggapananggapan formal, yaitu LOWESS (LocaLLy Weighted Smoothing Scat terpLots). Data referensi yang digunakan adalah data sekunder, hasil penelitian Puslitbang Gizi, Bogor, mengenai ."keadaan kesehatan dalam hubungannya dengan keadaan gizi ibu hamil" Sebagai peubah respons digunakan data ntropometri bayi lahir yaitu bobot dan panjang bayi lahir hidup dengan peubah prediktor lama dikandung.
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Judul: Penggunaan Metode Lowess Memuluskan untuk Kurva perkembangan Antropometrik Perempuan Hamil
Abstrak: Telaahan ini dimaksudkan untuk memperkenalkan suatu prosedur pemulusan persentil dengan menggunakan metode 'Robust Locally Weighted Regression', disingkat LOWESS. Kurva yang dihasilkan digunakan untuk menggambarkan perkembangan antropometrik perempuan selama kehamilan. Data yang digunakan adalah data sekunder hasil 'observational study' yang dilakukan oleh Pusat Penelitian dan Pengembangan Gizi di Bogor tahun 1983-1985. Peubah yang diamati meliputi antropometrik perempuan selama kehamilan yaitu tinggi badan, perkembangan bobot badan, LLA, LLBK dan BMI. Hasil kehamilan yang digunakan adalah bobot badan bayi lahir hidup. Analisis data dilakukan terhadap perempuan yang dianggap memenuhi syarat yaitu yang melahirkan bayi lahir hidup sebanyak 1337 orang. Langkah awal analisis adalah dengan memeriksa perilaku data dari tiap peubah amatan untuk perempuan yang melahirkan bayi BBLR (bobot lahir < 2500 g) dan BBLC (bobot lahir≥2500 g). Untuk peubah tinggi badan diperoleh hasil bahwa sebaran tinggi badan dapat dianggap menyebar normal. Diantara keempat peubah yang diamati, hanya bobot badan dan BMI yang mengalami peningkatan dengan bertambahnya umur kehamilan, sedangkan LLA dan LLBK relatif tetap. Kurva pemulusan perempuan yang melahirkan bayi BBLC lebih tinggi daripada yang melahirkan bayi BBLR. Peningkatan nilai ƒ dari 0.2 ke 0.5 menyebabkan peningkatan kemulusan dari kurva pemulusan yang ada.
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Judul: Application of phycocyanin from microalgae Spirulina platensis as light harvesting in anatase TiO2 nanoparticle solar cell.
Abstrak: The dye sensitized solar cell (DSSC) has been assemblied used hybrid titanium oxide (TiO2) film/phycocyanin. The TiO2 film was synthesized by sol gel method with titanium chlorida (TiCl4) as precursor by hydrolysis used sulfuric acid (H2SO4). Furthermore, it calcinated for 2,5 hours in variation of annealing temperature (400oC, 600oC, 800oC, dan 1000oC). In XRD patterns exhibited which annealing temperature at 400oC to 800oC were anatase phase all. When annealed at temperature 1000oC, it caused phase transformation from anatase to rutile. The crystals size according to XRD patterns were 13,75 nm, 20,79 nm, 25,25 nm, 48,88 nm and particle size from SEM images were 43,06 nm, 44,91 nm dan 64,99 nm, 80,40 nm, respectively. The crystals and particle size increased with annealing temperature. The film thickness influenced material absorption. The optical measurement of TiO2 film and TiO2/phycocyanin hybrid film used UV-Vis spectrophotometer. Additional phycocyanin caused peak width of absorbed region from ultraviolet to visible region. The band gap energy of TiO2 can be calculated using the cut off wavelength obtained from the absorbance spectrum of a nanoparticles TiO2 films. Based on intersection between linear and energy (hv) axis. In this study just limited for anatase phase. It was caused anatase band gap is wider than rutile phase. That’s meaningful for solar cell application such as dye sensitized solar cell (DSSC). The absorption coefficient average at difference annealing temperature such as at 400oC, 600oC, 800oC were 8,1600x102, 1,7535x103 and 4,0154x102, where α < 104 include to direct transition. Band gap energy 400oC, 600oC, 800oC were 3,79 eV, 3,59 eV, and 3,35 eV, respectively. Based on this result, exhibition that band gap energy of TiO2 semiconductor film decreased with increasing annealing temperature. Spirulina platensis was cultivated in technical modification (Hastuti) with aeration under light intensity about 3000 lux. The cell density (stationer phase) for eighth day which OD value was more than 0,5. It means, the culture can be harvested. In 80 liters Spirulina platensis culture have been produced biomass dry about 10,46 gram and extracted phycocyanin in dry powders was 5,50 gram. The phycocyanin absorption spectrum at the wavelength of 619,36 nm (visible region) which had relaxation energy was 2,945 eV. The emission peak at the wavelength of 708,55 nm with relaxation energy about 2,793 eV. The Stokes shift based on difference energy absorption and emission calculated about 0,152 eV. Both of this showed phycocyanin can absorbed and radiated the sun light which received. This choice characteristic pigment was a good one related to sensitizer in solar cell application. Integration between light harvesting protein and TiO2 semiconductor surface had important role in improving of output as solar cell materials. The presence of carboxylate group (-COOH) made pigment be more efficient was due to anchored to the surface of TiO2 ampoter. The phycocyanin pigment had carboxylate group which reacted with TiO2 surface formed ester. The carboxylate group increased of dye electronics couple from excited state (p anti bonding orbital) to semiconductor acceptor state (TiO2 conduction band). The samples which made based on annealing temperature variation formed be solar cell respectively. Furthermore, cells be assembled for
Keyword: anatase, dye sensitized solar cell, efficiency, gap energy, phycocyanin