The study of digital rock physics has seen significant advances due to the development of X-ray micro computed tomography scanning devices. One of the advantages of using such a device is that the pore structure of rock can be mapped down to the micrometre level in three dimensions. However, in providing such high-resolution images (low voxel size), the resulting file sizes are necessarily large (of the order of gigabytes). Lower image resolution (high voxel size) produces smaller file sizes (of the order of hundreds of megabytes), but risks losing significant details. This study describes the effect of the image resolution obtained by means of hardware-based and software-based approach. Four samples of porous rock were scanned using a SkyScan 1173 High Energy Micro-CT. We found that acquisition using increased pixel binning of the camera (hardware-based resizing) significantly affects the calculated physical properties of the samples. By contrast, voxel resizing by means of a software-based approach during the reconstruction process yielded less effect on the porosity and specific surface area of the samples. However, the decreasing resolution of the image obtained by both the hardware-based and the software-based approaches affects the permeability significantly. We conclude that simulating fluid flow through the pore space using the Lattice Boltzmann method to calculate the permeability has a significant dependency on the image resolution.
Calculation of permeability from 3D tomographic rock images was performed by combining renormalization group approaches (RGA) and lattice Boltzmann method (LBM). Images of sandstone rock samples (i.e., Fontainebleau, Berea, and Sumatera sandstones) with block size of 256 3 voxels were used in this study. LBM was applied to calculate permeability of each smallest block (i.e., 64 and 128 voxels) as sub-blocks of the larger block (256 3 voxels). The calculated permeability will form analogue to hydraulic conductance networks. RGA were then applied to the networks for all three perpendicular directions using several RGA schemes, i.e., King, Karim-Krabbenhoft, Green-Paterson, and their combinations. It was shown that as the number of renormalizations increases, the average permeability decreases. The effective permeability calculated by combining RGA and LBM were lower than permeability of the single largest block. Karim and Krabbenhoft's scheme produced mostly higher estimation than the others and closest to the true permeability. Degree of anisotropy is influenced by the initial block size prior to RGA scheme.
Aeroponic potato seed production in the lowlands has been carried out by root zone cooling and evaporative cooling in order to reduce high temperature stress for the roots and tops of potato plants. However, the effect of nutrient solution EC on several varieties of potato seeds for an aeroponic system with a combination of root zone cooling and evaporative cooling for potato seed production in the lowlands has not been done. This study aims to obtain the response of potato varieties and the application of different ECs on aeroponic seed production with root zone and evaporative cooling in tropical lowlands. The factors analyzed : 1. Variety (V): V1 (MZ), V2 (Granola K), V3 (Granola L), and 2. Nutrient concentration (EC): EC1 (1.5 mS/cm for Week 1- 4, 2 mS/cm for Week 5 until harvest), and EC2 (1.5 mS/cm for Week 1-4, and 3 mS/cm for Week 5 until harvest), while the design used was RAK with 3 replications. The results showed that the Granola K and EC2 varieties are more efficient for potato seed production in the lowlands with the application of root zone and evaporative cooling. This variety produced the highest number of tubers up to 30 tubers/plant. Similarly, the Granola L and MZ varieties showed similar results with a total number of tubers above 10 tubers/plant. Keywords: Cultivation, Greenhouse, Hydroponics, Nutrition, Tubers
<p>Investigasi bidang gelincir<strong> </strong>zona rawan longsor di sekitr lokasi mahkota longsor Bukit Pawinihan Sijeruk Banjarnegara telah dilakukan dengan menggunakan metode geolistrik tahanan jenis metode Wenner. Uji sifat plastisitas tanah penyusun di lokasi penelitian dilakukan pada tingkat pelapukan yang berbeda. Tujuannya untuk menentukan kedalaman, jenis pelapukan dan sifat dari bidang gelincir. Hasil pemodelan resistivitas 2D menunjukkan bahwa bidang gelincir berada pada kedalaman 6-8 meter berupa batu breksi lapuk (30-118 <strong>Ω</strong>m). Batuan ini merupakan batuan dengan tingkat pelapukan 3 dan bersifat kohesif. Nilai indeks plastisitasnya adalah 8,27.</p>
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