scholarly journals PREDICTIVE MODEL OF CONTOUR LINE AND GRAIN SIZE CHANGES CONSIDERING EQUILIBRIUM SLOPE DEPENDING ON DOMINANT GRAIN SIZE POPULATION

2007 ◽  
Vol 63 (2) ◽  
pp. 154-167
Author(s):  
Takayuki KUMADA ◽  
Takaaki UDA ◽  
Masumi SERIZAWA
Keyword(s):  
Grain Size ◽  
Predictive Model ◽  
Contour Line ◽  
Size Population

scholarly journals Contour-Line-Change Model Considering Local Longitudinal Slope Corresponding to Grain Size Composition

2007 ◽  
Vol 54 ◽  
pp. 426-430
Author(s):  
Yasuhito NOSHI ◽  
Akio KOBAYASHI ◽  
Takaaki UDA ◽  
Takayuki KUMADA ◽  
Masumi SERIZAWA
Keyword(s):  
Grain Size ◽  
Size Composition ◽  
Contour Line ◽  
Change Model ◽  
Grain Size Composition ◽  
Longitudinal Slope

Prediction of Surface Hardness in Laser-Assisted Milling

2019 ◽  
Author(s):  
Yixuan Feng ◽  
Tsung-Pin Hung ◽  
Yu-Ting Lu ◽  
Yu-Fu Lin ◽  
Fu-Chuan Hsu ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Grain Size ◽  
Predictive Model ◽  
Work Hardening ◽  
Surface Hardness ◽  
Size Variation ◽  
Milling Process ◽  
Depth Of Cut ◽  
Recrystallization Process ◽  
Hardness Change

Abstract The control of work hardening in laser-assisted milling process while keeping a desirable cutting efficiency is quite challenging. Surface hardness is a good indicator of the work hardening. Therefore, it is valuable to predict surface hardness in laser-assisted milling such that the effects of process parameters can be better quantified to facilitate process planning. In the current study, a general surface hardness predictive model based on theories of metal machining and microstructure evolution in laser-assisted milling process is proposed to describe the grain size variation-induced hardness change. The laser preheating temperature field is first calculated by treating the laser beam as a moving heat source. Then, the oblique milling process is transferred to equivalent orthogonal cutting process at each rotation angle to predict the grain size dependent on dynamic recrystallization process. The inverse relationship between the grain diameter and surface hardness is applied to decide grain size variation-induced hardness change. The model is validated through laser-assisted milling experiments on Ti-6Al-4V and Ti-6Al-4V ELI. The proposed predictive model is able to match the experimental measurements in all cases with an average error of 3% for Ti-6Al-4V and 3.3% for Ti-6Al-4V ELI. In addition, a sensitivity analysis is conducted on Ti-6Al-4V to study the influences of cutting speed, depth of cut, laser power, and laser-tool distance on hardness. The proposed analytical model is valuable for providing a fast, credible, and physics-based method for the prediction of surface hardness in laser-assisted milling of various materials. Through sensitivity analysis, the model is able to guide the selection of cutting and laser parameters when the control of surface hardness is the main target.

scholarly journals Evaluation of Effect of Beach Nourishment using Fine and Coarse Sand by Contour-line-change Model Considering Change in Grain Size

2007 ◽  
Vol 54 ◽  
pp. 641-645
Author(s):  
Takaaki UDA ◽  
Takayoshi YOSHIZOE ◽  
Yasushi MACHII ◽  
Takeshi YAMAMOTO ◽  
Kou FURUIKE ◽  
...  
Keyword(s):  
Grain Size ◽  
Beach Nourishment ◽  
Coarse Sand ◽  
Contour Line ◽  
Change Model

scholarly journals GrainSizeTools: a Python script for estimating the dynamically recrystallized grain size from grain sectional areas

2014 ◽  
Vol 6 (2) ◽  
pp. 3141-3196
Author(s):  
M. A. Lopez-Sanchez ◽  
S. Llana-Fúnez
Keyword(s):  
Grain Size ◽  
Structural Geology ◽  
Density Estimation ◽  
Kernel Density Estimation ◽  
Kernel Density ◽  
Gaussian Kernel ◽  
Lithospheric Deformation ◽  
Python Script ◽  
Size Population ◽  
Recrystallized Grain Size

Abstract. Paleopiezometry and paleowattometry studies, required to validate models of lithospheric deformation, are increasingly common in structural geology. These studies require a numeric parameter to characterize and compare the dynamically recrystallized grain size of natural mylonites with those obtained in rocks deformed under controlled conditions in the laboratory. We introduce a new tool, a script named GrainSizeTools, to obtain a single numeric value representative of the dynamically recrystallized grain size from the measurement of grain sectional areas (2-D data). For this, it is used an estimate of the most likely grain size of the grain size population, using an alternative tool to the classical histograms and bar plots: the peak of the Gaussian kernel density estimation. The results are comparable to those that can be obtained by other stereological software available, such as the StripStar and CSDCorrections, but with the advantage that the script is specifically developed to produce a single and reproducible value avoiding manual steps in the estimation, which penalizes reproducibility.

scholarly journals BEACH CHANGES AROUND DAWU FISHING PORT IN TAIWAN CAUSED BY OBSTRUCTION OF LONGSHORE SAND TRANSPORT AND MEASURES

2012 ◽  
Vol 1 (33) ◽  
pp. 118 ◽  
Author(s):  
Takayuki Kumada ◽  
Takaaki Uda ◽  
Jimmy J. Y. Liu
Keyword(s):  
Grain Size ◽  
Survey Data ◽  
Beach Nourishment ◽  
Contour Line ◽  
Aerial Photographs ◽  
Sand Transport ◽  
Change Model ◽  
Road Tunnel ◽  
Bathymetric Survey ◽  
Wave Overtopping

The Dawu fishing port breakwater has been extending since 1956 in Taitung City located in the southeast part of Taiwan, obstructing southward longshore sand transport. Because of the blockage of longshore sand transport at this fishing port, severe downcoast erosion occurred, resulting in the wave overtopping damage to Route No. 9 extending along the coastline, and urgent measures were required to enhance the safety of the route. As measures, beach nourishment using coarse materials including gravel produced from the construction of a road tunnel was planned, as well as the construction of groins on the downcoast. We first analyzed beach changes around this fishing port using past aerial photographs and bathymetric survey data, and beach changes were reproduced using the contour-line-change model considering changes in grain size. Then, the effect of measures was investigated using the model.

scholarly journals MOVING GRAVEL BODY METHOD TO CONTROL DOWNCOAST EROSION

2012 ◽  
Vol 1 (33) ◽  
pp. 40 ◽  
Author(s):  
Toshinori Ishikawa ◽  
Takaaki Uda ◽  
Shiho Miyahara
Keyword(s):  
Grain Size ◽  
Beach Nourishment ◽  
Contour Line ◽  
Sand Transport ◽  
Change Model ◽  
Body Method

The concept of the moving gravel body (MGB) method, in which topographic changes are controlled by beach nourishment using gravel, was introduced, using the contour-line-change model considering changes in grain size. The model was applied to the Fuji coast, assuming that coarse materials were nourished on a straight coast wherein a predominant longshore sand transport develops. The grain size that is effective for the recovery and maintenance of the shoreline and that does not cause further downcoast erosion was d, which is 5-10 times larger than that of the original sand, d0.

Sensitive grain-size records of Holocene East Asian summer monsoon in sediments of northern South China Sea slope

2011 ◽  
Vol 75 (3) ◽  
pp. 734-744 ◽  
Author(s):  
Jie Huang ◽  
Anchun Li ◽  
Shiming Wan
Keyword(s):  
Grain Size ◽  
South China Sea ◽  
South China ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Northern South China Sea ◽  
East Asian ◽  
China Sea ◽  
Size Population ◽  
Asian Summer

AbstractChanges in paleoenvironments over the last 17,500 yr have been documented by a high-resolution clay mineralogy and grain–size records of Core KNG5 from the northern slope of the South China Sea. Our results indicate that clay minerals are mainly from the Pearl River from 17,500 to 12,500 cal yr BP, and the South China Sea modern current system began to form since 12,500 cal yr BP, as a result, Taiwan turns to be the major contributor of clay minerals after 12,500 cal yr BP. Two grain-size populations with high variability through time were identified in the 13–28 μm and 1–2.2 μm grain-size intervals. The 1–2.2 μm grain-size population are mainly controlled by provenance supply and current transport. The 13–28 μm grain-size fraction could be controlled mainly by the sea-level change. The 1–2.2 μm grain-size population record demonstrates that East Asian Summer Monsoon intensity generally follows changes in insolation and that the response is similar for a large area of China and other northern low-latitude records, implying the globality of the monsoon evolution since Holocene. The anomalous environmental conditions in the northern South China Sea may imply intensified ENSO activity during the late Holocene.

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