A model of magnetic order in hexagonal HoMnO3

Symmetry arguments are used to develop a spin Hamiltonian for the description of the complex magnetic ordering in HoMnO$_3$. Using a novel application of the Landau Lifshitz Gilbert dynamic torque equations to this model of the frustrated Mn ions on an $AB$ stacked triangular antiferromagnetic, it is shown that the four principal spin configurations observed in this compound are stabilized. Ho-Mn coupling is found to be a consequence of an unusual trigonal anisotropy term which is responsible for simultaneous Mn spin reorientation and onset of Ho magnetic order. Based on these microscopic considerations, a mean-field Landau-type free energy is derived which reproduces the succession of observed temperature driven magnetic phase transitions at zero field, including re-entrant behavior. In addition, our analysis suggests that the basal-plane magnetic order should be slightly incommensurate with the lattice.Comment: 9 pages, 3 figure

Theory of magnetic phases of hexagonal rare earth manganites

The magnetic phases of hexagonal perovskites RMnO_3 (R=Ho, Er, Tm, Yb, Sc, Y) are analysed using group theory and the Landau theory of phase transitions. The competition between various magnetic order parameters is discussed in the context of antiferromagnetic interactions. A phenomenological model based on four one-dimensional magnetic order parameters is developed and studied numerically. It is shown that coupling of the various order parameters leads to a complex magnetic field-temperature phase diagram and the results are compared to experiment.Comment: 11 pages, 14 figures. Manuscript with higher quality figures can be obtained here: http://www.physics.mun.ca/~curnoe/papers/RMnO3.submit.pd

ANAEROB FIXED BED REAKTOR UNTUK MENURUNKAN COD, FOSFAT (PO4) DAN DETERJEN (LAS)

Laundry wastes can be processed in various ways, one of them using a Fixed Bed Reactor with media in anaerobic Bioball. The initial characteristics of waste laundry is COD: 291 mg/l, detergents: 29,74 mg N/l, total: 172,58 mg/l, P total: 29.12 mg/l. This research was conducted with the variation of the concentrations of COD is to waste the early (So) = 280 mg/l, 232,8 mg/l (80% * So), 174,6 mg/l (60% * So),116 mg/l (40% * So), 58,2 mg/l (20% * So) and debit 150, 130, 110, 80, 60 ml/minute. From research conducted obtained results which best COD concentrations allowance amounting to 91,06% for COD at the COD variation 58,2 mg/l with 60 ml/min discharge, concentrations of phosphate (PO4) amounted to 82.13% at 20% waste discharge 60 mg/minute Concentrations of detergent and 76,13% at 20% waste discharge 60 mg/min. At concentrations of COD, phosphate (PO4) and detergents that are processed on a fixed bed reactor to continue bioball media content kosentrasinya meet the standard quality raw liquid waste based on the decision of the Governor of East Java Number 45 in 2002. Keywords : Laundry wastes, Fixed Bed Reacto

Magnetic Phases of Rare Earth Hexagonal Manganites

We describe the magnetic phases of hexagonal rare earth manganites RMnO3 using Landau theory. A minimal model based on four one-dimensional magnetic order parameters is developed.Comment: 2 Pages, Proceedings of SCES'0

Non-destructive Method for Maturity Assessment of Indonesian's Mangoes by NIRS Spectroscopy

Rapid and non-destructive method to determine maturity quality of mangoes accurately has played an increasing role in the fruits supply chain involving automation. Diffuse reflectance spectra (R) and absorbance spectra (Log 1/R) in the spectral range from 900 to 1400 nm were measured using NIRS spectroscopy at three different points of 257 Indonesians mangoes cultivar arumanis, manalagi, gadong, gincu and golek of different ripeness indices. Through principle component analysis (PCA) and cluster analysis (CA) of the absorbance and reflectance spectra, cultivars can be differed with an accuracy of 99.8%. Multiple linear regression was applied to develop calibration models from mangoes with soluble solid content ranged between 5.5 and 13.5 % Brix and firmness ranged between 0.25 and 4.50 kgf. Log 1 /R calibration model could assess the soluble solid content and firmness of the mangoes with higher accuracy than R model with the coefficient of determination of 0.96 and 0.93, respectively. Results showed that NIRS spectroscopy has the feasibility to be employed in the maturity measures of Indonesian's mangoes

PENINGKATAN PENDAPATAN MASYARAKAT MELALUI KERAJINAN BOSSARA DI DESA BONTO RAJA KECAMATAN GANTARANG KABUPATEN BULUKUMBA

Desa Bontoraja merupakan salah satu dalam wilayah Kecamatan Gantarang Kabupaten Bulukumba.Dengan luas wilayah Desa Bontoraja 9.7 km kepadatan penduduk mencapai 3.899 jiwa penduduktetap.Dengan jumlah wajib pilih 2.875 orang namun dari keluasan yang begitu potensial saat ini masihbanyak sumber daya alam berpotensi belum digali. Letak geografis Desa Bontoraja berada diwilayahbarat kabupaten Bulukumba pada lingkungan 750 M dari permukaan laut. Keseharian masyarakat DesaBontoraja yaitu bercocok tanam bertani,berkebun,bet N ernak sapi ,ayam ,buruh bangunan sertaberdagang lainnya. Mengingat keadaan wilayah sebahagian persawahan dan perkebunan 75% dari luaswilayah Desa Bontoraja dan selebihnya 25% untuk perumahan dan lahan lainnya.masyarakat umumnyasudah aktif mengelolah lahan pertanian dan perkebunan dengan menanam padi, coklat, cengkeh danmerica dengan menggunakan cara yang masih tradasional. Namun seutuhnya hasil panen belumditemukan harga yang sebanding dengan pekerjaan tersebut. Kendala utamanya adalah naik turunnyaharga perdagangan tanaman padi terutama pada saat panen raya. Demikian juga harga cengkeh dancoklat yang sering turun drastis sementara yang tinggi kadang-kadang tidak mampu bertahan lamasehingga banyak yang belum sempat menjual turun harga lagi .Jarak pusat desa dengan ibu kotakabupaten yang dapat ditempuh melalui perjalanan darat kurang lebih 20 km.Kondisi prasarana jalanporos desa yang masih berupa konstruksilapen dengan kondisi aspal waktu tempuh menggunakankendaraan bermotor mencapai kurang lebih 30 menit. Sedangkan jarak pusat desa dengan ibu kotakecamatan yang dapat ditempuh melalui perjalanan darat kurang lebih 15 km. Kabupaten Bulukumbaterletak di bagian selatan Provinsi Sulawesi Selatan dengan jarak kira-kira 150 km dari kota Makassar kearah selatan. Secara umum luas Bulukumba 1.154,67 km2 yang terdiri dari 10 kecamatan dan 27kelurahan serta 109 desa/kelurahan Dan jumlah penduduk kabupaten Bulukumba 394.757 jiwa. DesaBontoraja adalah salah satu Desa di Kecamatan Gantarang Kabupaten Bulukumba yang memilikipotensi yang bisa dikembangkan yaitu pengembangan kewirausahaan melalui pelatihan pembuatanBossara yang dikembangkan oleh kelompok masyarakat. Pembuatan Bossara ini merupakan kegiatanrutin yang dilakukan masyarakat yang akan memberikan nilai tambah untuk meningkatkan pendapatanbagi masyarakat didesa bontoraja.Kata Kunci: Peningkatan, Pendapatan, Masyaraka

Crop-Cattle Integrated Farming System: An Alternative of Climatic Change Mitigation

An integrated farming system is one of the alternatives for climatic change mitigation. This paper reports the application of corn-cattle based integrated farming system in Agrotechno Park Center of Palembang, and discusses its impact on CO2 fixation and the reduction of methane emissions. The study was based on the data of the first 6 yr from 2003 until 2009. The CO2 fixed in the soil and plants was determined based on the content of organic C which was multiplied by the index of 3.67. The methane gas produced by Balinese cattle and its dung was observed and modified into feed rations. The results showed that soil organic C increased from 40.80 tons C/ha in the 1st yr to 66.40 tons C/ha in the 6th yr. In addition, there was organic C fixation equivalent to 93.95 tons of CO2e. Corn biomass increased from 6.67 tons/ha to 18.66 tons/ha, equivalent to an increase in the fixation of atmospheric CO2e as much as 19.80 tons CO2e/ha. The supplementation of 60%-80% grass fodder with concentrate lowered the concentration of methane gas in cattle breathing by 28.7%, from 617 ppm to 440 ppm, while the methane emissions from cattle manure decreased by 31%, from 1367 mL/head/d to 943 mL/head/d. Installing a bio digester that generates biogas served to accommodate methane gas emissions from cattle dung and used it for bioenergy. Composting reduced the formation of methane gas from cattle manure through a regular process of turning over that gives aeration and forms aerobic condition in the heap of cattle dung. Recycling produces a variety of organic products that store carbon for a longer period of time and slowed the conversion of organic C into CO2. This study showed that the diverse activities of an integrated crop-cattle farming could be an alternative solution to climatic change mitigation.Key words: integrated farming, mitigation, organic C, methane, recyclin

Kajian terhadap Naskah Kuna Nusantara Koleksi Fakultas Ilmu Pengetahuan Budaya Universitas Indonesia: Penyakit dan Pengobatan Ramuan Tradisional

From the manuscript, we can take the information about deseases and the medical treatment. The study of nusantara’s manuscripts which keep on the library Faculty of Humanities University of Indonesia (before Faculty of Letters-UI), especially medical text Javanese, Balinese, Melanese, and Sundanese show the information about the deseases, varieties of herba medical, processing, and therapies.&nbsp

Sistem Tracking Panel Surya untuk Pengoptimalan Daya Menggunakan Metode Kendali Logika Fuzzy

Salah satu jenis energi alternatif yang berkembang pesat dan banyak digunakan adalah energi matahari yang digunakan sebagai pembangkit listrik, dalam bentuk panel surya. Dalam rangka mengoptimalkan penggunaan panel surya tersebut, diperlukan sebuah sistem pengendali yang dapat mengontrol posisi panel surya agar selalu mengikuti arah dan posisi dari matahari secara otomatis. Sistem yang digunakan untuk pengaturan tersebut dinamakan sistem tracking matahari dengan dua derajat kebebasan. Sistem ini bekerja menggunakan Perubahan daya yang terbaca oleh panel surya. Kelebihan dari sistem ini dapat mengikuti posisi matahari. Dalam sistem ini digunakan perbandingan daya yang terbaca oleh sistem dan mencari yang paling optimal diantara daya tersebut. Berdasarkan perbedaan daya yang diterima, Kendali Logika Fuzzy akan menggerakkan motor servo untuk melakukan aksi kendali terhadap posisi panel surya supaya selalu tegak lurus terhadap posisi matahari. Perbandingan respon unjuk kerja antara sistem yang tanpa menggunakan kontroler fuzzy yaitu tegangan =15,40 V, arus = 0,46 A, dan daya = 7.17 W , sedangkan untuk sistem yang menggunakan kontroler fuzzy 2 DOF (Degree Of Freedom) menghasilkan tegangan = 15,54 V, arus = 0,51 A, dan daya = 7.94 W. Sistem yang dibuat sudah mengikuti matahari untuk mencapai daya yang maksimal