ANALISIS TINGKAT BAHAYA EROSI PADA VEGETASI KEBUN KARET PADA BERBAGAI KELERENGAN DI SUB DAS BATI-BATI DAS MALUKA PROVINSI KALIMANTAN SELATAN

The danger level of erosion at each land closure and Slopes has different results. It is important to know the handling of erosion hazards later. The purpose of this study is to calculate the amount of erosion due to changes in land closures and to know the level of erosion hazard (TBE) of rubber plantations on various slopes in Sub Das Bati – Bati Das Maluka. The research method is purposive random sampling. Sample points taken based on soil type, slopes class, vegetation, and land cover are adjusted to the land units of the land unit map (overlay). Soil sampling using ring samples and soil drills will then be tested. Land cover and marbles are closely related to erosion values. The highest erosion value is in Land Unit (LU) 38 with an erosion value of 73.64 tons/ha/yr, while the lowest value is at LU 7 with an erosion value of 6.34 tons/ha/yr. The degree of erosion hazard is related to the soil solum. Erosion hazard level in all land units and land cover indicates grade II-S (medium) is present at LU 38 while light (I-SR) is on, LU 37, LU 50, and LU 59, and very light (0-SR) is on LU 7 and LU 34.Tingkat bahaya erosi pada masing-masing penutupan lahan dan kelerengan mempunyai hasil yang berbeda. Hal ini penting untuk mengetahui penanganan bahaya erosi nantinya. Tujuan dari penelitian ini ialah untuk menghitung besarnya jumlah erosi akibat perubahan penutupan lahan serta mengetahui tingkat bahaya erosi (TBE) vegetasi kebun karet pada berbagai kelerengan di Sub Das Bati-Bati Das Maluka. Metode penelitian dilakukan secara purposive random sampling. Titik sampel yang diambil berdasarkan jenis tanah, kelas kelerengan, vegetasi, dan tutupan lahan yang disesuaikan dengan unit lahan dari peta satuan lahan (overlay). Pengambilan sampel tanah menggunakan ring sample dan bor tanah yang kemudian akan dilakukan pengujian. Tutupan lahan dan kelerengan erat kaitannya dengan nilai erosi. Nilai erosi tertinggi berada pada Unit Lahan (UL) 38 dengan nilai erosi sebesar 73,64 ton/ha/thn, sedangkan nilai terendah ada pada UL 7 dengan nilai erosi sebesar 6,34 ton/ha/thn. Tingkat bahaya erosi berhubungan dengan solum tanah. Tingkat bahaya erosi pada semua unit lahan dan tutupan lahan, menunjukkan TBE kelas II-S (sedang) terdapat pada UL 38 sedangkan TBE ringan (I-SR) ada pada, UL 37, UL 50, dan UL 59 serta TBE sangat ringan (0-SR) ada pada UL 7 dan UL 34.

EFFECT OF CHROMIUM COATINGS ON THE MECHANICAL PROPERTIES OF Zr1Nb FUEL CLADDINGS IN LONGITUDINAL AND TRANSVERSE DIRECTIONS

This study was aimed at investigating the chromium coating effect on the mechanical properties of Zr1Nb fuel claddings in the case of a tensile fracture in longitudinal and transverse directions at temperatures of 20 and 350 °С. Tests were carried out using the samples of a similar shape, namely, with an equal test portion length that is important for comparison of results. The obtained results have shown that at a test temperature of 20 °С the mechanical properties of initial samples are higher in the longitudinal direction than in the transverse direction. The ductility is slightly higher at T = 350 °С in the longitudinal direction, and σ0.2 and σв are practically equal. The preliminary deformation of ring samples increases their ductility from 23 to 34% independently on the test temperature. Deposition of the chromium coatings on the samples leads to the slight increase of mechanical properties in the transverse direction and decrease of σ0.2 with unchanged σв and δ% in the longitudinal direction at the room test temperature, and at 350 °С it practically do not change the properties of coated samples in both the directions except the ring sample ductility decrease.

Kepadatan Tanah Pasca Tambang Batu Bara Setelah di Revegetasi

Penelitian tinjauan kepadatan lahan paska tambang batu bara yang sudah direveggetasi dilaksanakan di lahan bekas tambang batubara milik PT. Nan Riang, di Kota Muara Tembesi, Provinsi Jambi. Analisis tanah dilakukan di Laboratorium Fisika Tanah dan Mineralogy Fakultas Pertanian Universitas Jambi. Penelitian dilaksanakan selama 6 bulan dari bulan Juni 2016 sampai November 2016. Penelitian ini dilaksanakan menggunakan metode survey dan data yang diperoleh dianalisis secara deskriptif analitik pada lahan bekas tambang yang telah ditanami vegetasi reklamasi (jabon umur 6 tahun, jambu umur 5 tahun , rambutan umur 4 tahun, dan karet umur 2 tahun). Contoh tanah utuh diambil pada kedalaman 0-20 cm dengan menggunakan ring sample (core samplers), lalu ditutup pada kedua sisinya agar air di dalam sampel tidak mengalami penguapan selama disimpan. Pada saat bersamaan, resistensi penetrasi tanah, yakni suatu variabel yang menggambarkan besarnya hambatan penetrasi akar ke dalam tanah, diukur pada kedalaman 0-5 cm, 5-10 cm, 15-20 cm dengan menggunakan penetrometer. Contoh tanah utuh digunakan untuk menganalisis berat volume, porositas total, dan kadar air tanah pada kondisi lapangan, sdangkan contoh tanah komposit digunakan untuk analisis kandungan bahan organik tanah. Data dianalisis secara deskriptif untuk mendapatkan interval variabel kualitas tanah timbunan bekas tambang pada setiap umur vegetasi reklamasi. Interval variabel tersebut selanjutnya dibandingkan dengan kebutuhan tanaman pangan berdasarkan beberapa hasil penelitian. Hasil penelitian menunjukkan bahwa revegetasi lahan paska tambang mempengaruhi kepadatan tanah. Kepadatan tanah berkurang dengan semakin bertambah umur tanaman revegetasi yang digunakan (jabon umur 6 tahun, jambu umur 5 tahun , rambutan umur 4 tahun, dan karet umur 2 tahun). Semakin dalam tanah kepadatan semakin meningkat, namun semakin berkurang pada tanaman yang lebih tua. Reklamasi lahan paska tambang batubara dengan tanaman jabon, jambu, rambutan dan karet mempengaruhi iklim mikro.

Numerical simulation of the heat treatment process for 100Cr6 steel

<p class="AMSmaintext1"><span lang="EN-GB">The success of quenching process depended heavily on the suitable choice of a quenching media. In this work, a numerical simulation of the process of quenching C-ring sample of 100Cr6 steel was discussed. The results showed an overview of the phase transformation, residual stress, distortion and hardness on the specimen throughout quenching process to the end. The simulation results also revealed that the sample is not cracked and the highest residual stress located on the inner and outer at the bottom edge of the C-ring with C-ring model being quenched in PVP-12 solution. At the same time, the obtained hardness was qualified the working requirements.</span></p>

Piston ring-cylinder liner tribology investigation in mixed lubrication regime: part I-correlation with bench experiment

Purpose – The purpose of this paper is to improve the environment and save energy, friction reduction, lower oil consumption and emissions demand that are the chief objectives of the automotive industry. The piston system is the largest frictional loss source, which accounts for about 40 per cent of the total frictional loss in engine. In this paper, the reciprocating tribometer, which is updated, was used to evaluate the friction and wear performances. Design/methodology/approach – An alternate method is introduced to investigate the effect of reciprocating speed, normal load, oil pump speed and ring sample and oil temperature on friction coefficient with the ring/liner of a typical inline diesel engine. The orthogonal experiment is designed to identify the factors that dominate wear behavior. To understand the correlations between friction coefficients and wear well, different friction coefficient results were compared and explained by oil film build-up and asperity contact theory, such as the friction coefficient over a long period and averaged the friction coefficient over one revolution. Findings – The friction coefficient changes little but fluctuates with a small amplitude in the stable stage. The sudden change of frequency, load and stroke will lead to the oil film rupture. The identification for the factors that dominates the wear loss is ranged as F (ring sample) > , E (oil sample) > , B (stroke) > , D (temperature) > , A (load) > , G (liner) > and C (frequency). Originality/value – This paper develops and verifies a methodology capable of mimicking the real engine behavior at boundary and mixed lubrication regimes which can minimize frictional losses, wear, reduce much work for the experiment and reduce the cost. The originality of the work is well qualified, as very few papers on a similar analysis have been published, such as: The friction coefficient values fluctuating in the whole stage may be caused by the vibration of the system; suddenly, boundary alternation may help the oil film to form the lubrication; and weight loss mainly comes from the contribution of the friction coefficient value fluctuation. The paper also found that the statistics can gain more information from less experiment time based on a design of experiment.

Forming and Simulation of Titanium Alloy Ti-6Al-4V by Hot Isostatic Pressing

Numerical simulation of titanium alloy powder during hot isostatic pressing (HIP) with Shima model is studied in this paper. Material parameters in this model were determined based on uniaxial compression test with different relative density specimens. A titanium alloy ring sample was designed and formed by hot isostatic pressing. The sample was analyzed by using Shima model in the platform of MSC.Marc with the determined parameters of titanium alloy (Ti-6Al-4V). The results of simulation with Shima model were in a good agreement with that result of experiment. Finally, the model is successfully applied to complex model of impeller to predict the deformation during HIP.

Residual Stress Measurements in an Autofrettage Tube Using Hole Drilling Method

Relieved strains due to drilling hole in a ring sample cut from an autofrettage cylinder are measured. Measured strains are then transformed to residual stresses using calibration constants and mathematical relations of elasticity based on ASTM standard recommendations (American Society for Testing and Materials, ASTM E 837-08, 2008, “Standard Test Method for Determining Residual Stresses by the Hole-Drilling Strain-Gage Method,” American Society for Testing and Materials). The hydraulic autofrettage is pressurizing a closed-end long cylinder beyond its elastic limits and subsequently removing the pressure. In contrast to three-dimensional stress state in the autofrettage tube, the stress measurement in hole drilling method is performed on a traction free surface formed from cutting the ring sample. The process of cutting the ring sample from a long autofrettaged tube is simulated using finite element method (FEM) and the redistribution of the residual stress due to the cut is discussed. Hence, transformation of the hole drilling measurements on the ring slice to the autofrettage residual stresses is revealed. The residual stresses are also predicted by variable material properties (VMP) method (Jahed, H., and Dubey, R. N., 1997, “An Axisymmetric Method of Elastic-Plastic Analysis Capable of Predicting Residual Stress Field,” Trans. ASME J. Pressure Vessel Technol., 119, pp. 264–273) using real loading and unloading behavior of the test material. Prediction results for residual hoop stress agree very well with the measurements. However, radial stress predictions are less than measured values particularly in the middle of the ring. To remove the discrepancy in radial residual stresses, the measured residual hoop stress that shows a self-balanced distribution was taken as the basis for calculating residual radial stresses using field equations of elasticity. The obtained residual stresses were improved a lot and were in good agreement with the VMP solution.

Use of Ring Sample for High-Pressure Torsion and Microstructural Evolution with Equivalent Strain

This study introduces a process of high-pressure torsion (HPT) using ring samples and compares with the results of conventional disk HPT. Both types of HPT were conducted at room temperature on pure Al and pure Cu. The microhardness was measured along the diameters of the disks and rings. Microstructures were examined using transmission electron microscopy. When hardness values were plotted against equivalent strain, all data points fell on a single line for each material. There was a hardness maximum for pure Al but no such a maximum was present in pure Cu. In pure Al, many dislocations were visible within grains up to the equivalent strain corresponding to the hardness maximum but beyond this strain, grains with low dislocation density appear. All materials exhibited steady state where the hardness remains constant with respect to imposed equivalent strain. This study concludes that use of ring samples is effective as an alternative to the disk samples.