Leakage current and surface discharge phenomena : effect on tracking and morphological properties of LLDPE-natural rubber compounds

Polymeric insulators are widely used for high voltage outdoor insulating application due to their substantial advantages compared to the porcelain and glass insulators. Although polymer materials have been proven good, research on development of new polymerbased materials is still on going since the benefits of using polymeric materials are not yet utilised to their full potential. In this work, a new formulated thermoplastic elastomer materials that are composed of linear low-density polyethylene (LLDPE) and natural rubber (NR) filled with different loadings of alumina trihydrate (ATH) fillers is presented. A surface tracking and erosion test is conducted to investigate the characteristics of leakage current on the material surface under the influence of wet contaminated conditions. A computer-based leakage current monitoring system is developed to monitor the leakage current waveform pattern as well as its frequency spectrum. The scanning electron microscope is used to investigate the morphological properties of the materials before and after the tracking test

Simulation Studies of Gas-Solid in the Riser of a Circulating Fluidized Bed

A numerical parametric study was performed on the influence of various riser exit geometries on the hydrodynamics of gas-solid two-phase flow in the riser of a Circulating Fluidized Bed (CFB). A Eulerian continuum formulation was applied to both phases. A two fluid framework has been used to simulate fully developed gas-solid flows in vertical riser. A two dimensional Computational Fluid Dynamics (CFD) model of gas-particle flow in the CFB has been investigated using the code FLUENT. The turbulence was modeled by a k-e turbulence model in the gas phase. The simulations were done using the geometrical configuration of a CFB test rig at the Universiti Teknologi Malaysia (UTM). The CFB riser column has 265 mm (width), 72 mm (depth) and 2.7 m height. The riser is made up of interchangeable Plexiglas columns. The computational model was used to simulate the riser over a wide range of operating and design parameters. In addition, several numerical experiments were carried out to understand the influence of riser end effects, particle size, gas solid velocity and solid volume fraction on the simulated flow characteristics. The CFD model with a k-e turbulence model for the gas phase and a fixed particle viscosity in the solids phase showed good mixing behaviour. These results were found to be useful in further development of modeling of gas solid flow in the riser

Mineralogy and Genesis of Soils in Uuiversiti Pertanian Malaysia, Serdang, Selangor

Soils of Universiti Pertanian Malaysia were surveyed and studied in order to determine their mineralogy and genesis. The results of the study showed that there were four major soil series on the Universiti Pertanian farm. Two of these series, namely Melaka and IVlunchong Series, were taxonomically classified as Tropeptic Haplorthox, while the other two, namely Serdang and Bungor Series, were classified as Typic Paleudult. The structure of the soils was found to be weak. The texture was clay in the case of Melaka, Munchong and Bungor Series and sandy clay loam in the case of Serdang Series. Melaka Series soil which contained petroplinthite occur as capping on top of hills. Soils of Munchong, Bungor and Serdang occur either on the slope or on the lower position than Melaka Series. All soils were extremely weathered. The dominant clay minerals were kaolinite, gibbsite and goethite; 2:1 type of clay mineral was virtually absent, except possibly some illite in Melaka Series. The pH was low, and so were exchangeable cations, CEC and %base saturation. On the other hand, exchangeable Al and H were significantly hig

Analisis Kelayakan USAha Penggilingan Padi di Kecamatan Lubuk Pakam Kabupaten Deli Serdang

Penelitian ini bertujuan untuk mengetahui efisiensi kinerja mesin penggiling padi, untuk mengetahui biaya produksinya, untuk mengetahui besar pendapatan, serta untuk melihat kelayakan dari USAha penggilingan padi tersebut. Metode yang digunakan pada penelitian ini adalah R/C yang digunakan untuk melihat kelayakan USAha, serta formula-formula sederhana yang sesuai untuk menghitung efisiensi kinerja mesin, biaya produksi, dan pendapatan USAha. Hasil penelitian terhadap 5 (lima) sampel didapatkan bahwa efisiensi kinerja mesin masih rendah, yaitu di bawah 80%. Rata-rata efisiensi untuk kapasitas 500 kg/jam sebesar 54,25% sedangkan untuk kapasitas 2000 kg/jam sebesar 55%. Biaya produksi rata-rata tahun 2012 untuk kapasitas 500 kg/jam adalah sebesar Rp. 1.940.475.289 sedangkan untuk kapasitas 2000 kg/jam adalah sebesar Rp. 3.066.506.000. Pendapatan rata-rata tahun 2012 untuk kapasitas 500 kg/jam adalah sebesar Rp. 112.138.152 sedangkan untuk kapasitas 2000 kg/jam adalah sebesar Rp. 386.944.000. Hasil penelitian terhadap studi kelayakan menunjukkan bahwa USAha penggilingan padi layak untuk dikembangkan

Spatial Variability of Selected Chemical Characteristics of Paddy Soils in Sawah Sempadan, Selangor, Malaysia

A study was conducted to evaluate the spatial variability of selected soil chemical properties of paddy soils in the Barat Laut Paddy Project area in Selangor. A total of 138 geo-referenced soil samples were collected from the area at 0-20 cm depth after harvest, at an interval of 80-90 m to determine the selected chemical properties: pH, organic carbon, total nitrogen (N), available phosphorus (P) and exchangeable potassium (K). Geostatistical analyses were applied to examine the within-field spatial variability using semivariograms and kriged maps. Kriged maps for each property were prepared using geostatistical software package based on the results of spatial dependence. The effective ranges for the areas were about 6 km for pH, 1 km for organic carbon, 8 km for total N and available P and 9 km for exchangeable K, respectively. Kriged maps produced showed that most of the area have pH values within the range of 4-4.5 (moderately acidic) and high amount of organic carbon content (3-5%). The kriged maps also showed that a large portion of the study area (66%) have high total N (0.30-0.40%), with low amount of available P (< 40 mg kg-1) covering 70% of the total study area, while most of the area have optimum content of exchangeable K (> 0.10 cmol(+) kg-1). These results suggest the need for a site specific approach in managing paddy soils particularly with regard to nutrient management. The results also suggested that future soil sampling in these area can be carried out by increasing the sampling interval depending on the soil properties, and appropriate management should be applied according to the variations which exist

Analisis Marketing Bill Komodti Cabai Merah di Kota Medan

Penelitian ini bertujuan untuk mengetahui analisis marketing bill komoditi cabai merah di Kota Medan. Diantaranya dengan menganalisis tingkat konsumsi nilai transaksi dan margin pemasaran yang terdapat pada petani dan pedagang perantara cabai merah didaerah penelitian. Lokasi penelitian dilakukan secara purposive, pengambilan sampel penelitian ini dilakukan dengan menggunakan metode snowball sampling. Data yang digunakan adalah data primer yang diperoleh dari petani yang di Kabupaten Karo, pedagang besar dan pedagang pengecer yang di Kota Medan melalui wawancara langsung dengan menggunakan daftar pertanyaan yang telah dipersiapkan terlebih dahulu dan data sekunder diperoleh dari Badan Ketahanan Pangan Kota Medan, Badan Pusat Statistik Sumatera Utara, dan Dinas Perhubungan Sumatera Utara. Responden diambil dengan menggunakan metode snowball Sampling sehingga ditentukan besar sampel untuk keseluruhan sebanyak 30 orang yang mengusahakan dan menyalurkan cabai merah ke Kota Medan . Metode analisis data yang digunakan adalah analisis deskriptif mengenai Tingkat Konsumsi, Volume dan Nilai Transaksi, dan Marketing Bill dianalisis dengan Marketing Margin, Price Spread dan Share Margin. Hasil penelitian menunjukkan bahwa tingkat konsumsi cabai merah meningkat tahun 2010 sebesar 4.761,8 ton/tahun, dan pada tahun 2011 sebesar 23.480 ton/tahun, total volume cabai merah sebesar 9.827 ton dengan total nilai transaksi Rp.241.698.699. Marketing Bill diperoleh sebesar Rp. 5.400 dimana share cost tertinggi terdapat pada pedagang besar sebesar 54,06% dan share profit tertinggi terdapat pada pedagang pengumpul sebesar 84,2%. Terdapat perbedaan biaya dan keuntungan setiap pelaku pemasaran