The Estimation of Peatlands Reserve on Carbon in the Forest and Shrubs That Has Been Drained

Global warming and greenhouse gas emissions (GHGs) became a hot issue in the world today. An increased concentration of carbon in the atmosphere becomes one of the serious problems that can affect life on Earth. Peatlands pointed out as one of the sources of GHG emissions. Drainage of peatlands cause decreased water level so that the decomposition process is faster on a layer above the groundwater table, thus affecting the chemical characteristics of peat. In addition to affecting the ground water level, drainage also leads to a decrease in surface height peat soil (subsidence). Given the magnitude of the role of drainage and land use types in affecting carbon stocks and emissions of CO2 on peat soil, this study is to measure carbon stocks and emissions of CO2 on peat soil in forests and shrubs that have been drained. CO2 emissions increase with the closer spacing of the drainage channel that is at a distance of 50 m to 500 m of drainage channels. Meanwhile, at a distance of 5 m and 10 m of the drainage channel can not be concluded because of the condition of ground water that is stagnant at the time of sampling gas, so be very low CO2 emissions. CO2 emissions on the use of forest land are higher than the shrub land

An Investigation of Alternative Path Planning Strategies for Machining of Nickel-Based Superalloys

Nickel-based superalloys play a crucial role in elevated temperature applications where high strength and high resistance to corrosion and creep resistance are required. These environments are largely found in the aerospace, nuclear power and gas turbine industries. Due to the properties that make them suitable for their end use they remain a challenge to manufacture. In the machining of nickel-based superalloys high cutting forces and tool wear occur greatly reducing their machinability. Although there have been multiple recent studies on the machining of such alloys, the field remains vastly unexplored. A limited amount of research has been done in tool path methods, as most previous research focuses on finding optimal machining parameters to curtail the difficulties in machining while keeping the tool path constant. An alternative tool path, trochoidal milling, has been identified to combat the difficulties in machining superalloys and combines linear motion with uniform circular motion, reducing chip load in exchange for increased machining time. Although this method has been shown to reduce flank wear on tools it suffers from notch wear at the depth of cut line

Comparison and Cost Optimization of Solid Tool Life in End Milling Nickel-Based Superalloy

Nickel-based superalloys constitute a significant portion of the materials used in important industries such as aerospace, energy production, automotive, and biomedical industries. Due to their superior properties that make them appealing for these industries such as their high strength at elevated operating temperatures, manufacturing these alloys to end product specifications has been a difficult task. Despite the several recent studies that unearth various methods to tackle different aspects of this challenge, machining of nickel-based superalloys continues to be a mostly unknown territory. Researchers have mostly worked on finding optimal machining parameters that provide milder operating conditions, lower cost of tooling, or better end-product dimensional accuracy and surface quality; however, the tool material and type are generally constant in these studies. Therefore, it is difficult to apply the information gathered from these studies when there is a change in the machine tool that has been used, as it frequently happens when tool manufacturers produce new tools that perform better

Effect of cutting speed on the surface integrity of face milled 7050-T7451 aluminium workpieces

The guarantee of surface integrity has become a primary objective for researchers when analysing the reliability of machined aircraft aluminium alloy structural parts in high-speed machining. This work studies the effect of cutting speed on the surface integrity of face milled 7050-T7451 aluminium workpieces. First, 7050-T7451 aluminium workpieces were face milled under dry conditions using three cutting speeds (200, 800, 1400 m/min) at constant feed (0.20 mm/tooth) and depth of cut (1 mm). An indexable face milling cutter with a diameter of 50 mm with five uncoated inserts was used in the face milling tests. During the machining process, cutting forces were acquired employing a Kistler dynamometer in order to understand the influence of the mechanical load on the final surface quality. The surface roughness p roduced by the milling process was measured using a portable rugosimeter. The residual stresses generated by the cutting process were measured by the holedrilling technique. In addition, small specimens were cut out from the workpieces and microstructural alterations of the surface layer were analysed employing optical microscopy techniques. The results demonstrate that the magnitude of residual stresses and the thickness of the affected layer is sensitive to the cutting speed, while surface roughness and microstructural defects do not show significant variations for the tested conditions

Numerical Simulation of Surface Modification During Machining of Nickel-based Superalloy

The main objective of this study is to implement a reliable FE model of the orthogonal machining of a Nickel based superalloy for the prediction of microstructural changes occurring during the process. A FE numerical model was properly calibrated using an iterative procedure based on the comparison between simulated and experimental results. A user subroutine was implemented in the FE code to simulate the dynamic recrystallization and consequently the grain refinement and hardness variation when orthogonal cutting of Nickel based superalloy is performed. Thus, Zener-Hollomon and Hall-Petch equations were implemented to predict the grain size and micro hardness, respectively. In addition, the depth of the affected layer was predicted using the critical strain equation. The obtained results proved the adequacy of the proposed model showing a good agreement between the simulated and the experimental results

Experimental and FEM analysis of surface integrity when broaching Ti64

The performance of aeronautic critical components is strongly dependent on its fatigue behavior, which is directly linked to their surface integrity condition. Broaching operation is a machining operation extensively used for the manufacturing of some features due to the good dimensional quality and surface integrity condition obtained. Thus, the characteristics of surface integrity obtained in broaching is a key aspect to be considered for the improvement of the fatigue life. This work proposes a Finite Element Method (FEM) model for the prediction of the surface integrity (material damage and residual stresses) of the workpiece obtained after the broaching process using the commercial finite element software DEFORM 2D. The model includes a self-characterized Johnson-Cook flow stress constitutive law for the titanium alloy Ti64. Experimental tests were carried out in an EKIN RAS 10x160x320 hydraulic broaching machine at different cutting conditions for the validation of the predictive model. Apart from the fundamental output variables, such as, forces and chip morphology, a comprehensive study of the surface integrity of the machined piece was done. The residual stresses generated by the cutting process were measured by the hole-drilling technique. Microstructural alterations (material damage) of the workpiece was analyzed by optical microscopy and Scanning Electron Microscope. Finally, the surface topography was examined by contact and optical profilometers. The results of the predictions showed significant good agreement with the experimental tests

Impact of Hemoglobin, Leucocyte and Thrombocyte Levels at Diagnosis on the Survival Outcomes of Chronic Myeloid Leukemia Patients

Background:Since the development of tyrosine kinase inhibitors (TKIs), the prognosis for chronic myeloid leukemia (CML) has significantly improved. Several predicted prognostic scores and indicators at diagnosis have been used to predict the prognosis of chronic phase chronic myeloid leukemia (CML-CP) during the TKI period. When CML patients are first diagnosed, hemogram parameter aberrations are rather prevalent in clinical practice, although it is still unknown how those parameters affect the prognosis. This study aims to evaluate the hemogram parameters at diagnosis on the survival outcomes of CML-CP patients. Materials and Methods:One hundred thirty-seven patients who were diagnosed with CML-CP and received treatment were assessed between the years 2006 and 2020. Results:There were 65 (47.4%) males and 72 (52.6%) females with a median age of 50 (range: 18-78) years at diagnosis. Median hemoglobin level was 12.1 gr/dL (4.3-17.4), leucocyte count was 66.2 ×109 /L (7.5-520.2), and thrombocyte count was 362 ×109 /L (18-3.496) for all patients. The median progression-free survival (PFS) was 16.7 months 16.7 (2.0-106.4) and the median overall survival (OS) was 63.8 months (0.43-166.2) for all patients. Conclusion:This study is valuable in terms of predicting the prognosis of CML patients with hemoglobin, leukocyte, and platelet values at the time of diagnosis. While emphasizing the importance of platelet count at the time of diagnosis, similar to the previously defined risk scores, it showed that leukocyte and hemoglobin values at the time of diagnosis did not have a statistically significant effect on OS and PFS