scholarly journals Supplemental Material: Onset of permanent Taklimakan Desert linked to the mid-Pleistocene transition

2020 ◽  
Author(s):  
Weiguo Liu ◽  
Zhonghui Liu
Keyword(s):  
Grain Size ◽  
Taklimakan Desert ◽  
Lop Nur ◽  
Size Data

Materials, methods, and interpretations, Figure S1 (stratigraphic columns and age assignments), Figure S2 (δ<sup>13</sup>C correlated with rainfall and temperature), Figure S3 (detailed view of the onset of desertification), Figure S4 (representative core photos), Figure S5 (Lop Nur and Mazartag δ<sup>13</sup>C), Figure S6 (spectral results), Figure S7 (close-up views of records), and Table S1 (δ<sup>18</sup>O, δ<sup>13</sup>C, and grain-size data).<br>

scholarly journals Supplemental Material: Onset of permanent Taklimakan Desert linked to the mid-Pleistocene transition

2020 ◽  
Author(s):  
Weiguo Liu ◽  
Zhonghui Liu
Keyword(s):  
Grain Size ◽  
Taklimakan Desert ◽  
Lop Nur ◽  
Size Data

Materials, methods, and interpretations, Figure S1 (stratigraphic columns and age assignments), Figure S2 (δ<sup>13</sup>C correlated with rainfall and temperature), Figure S3 (detailed view of the onset of desertification), Figure S4 (representative core photos), Figure S5 (Lop Nur and Mazartag δ<sup>13</sup>C), Figure S6 (spectral results), Figure S7 (close-up views of records), and Table S1 (δ<sup>18</sup>O, δ<sup>13</sup>C, and grain-size data).<br>

scholarly journals Supplemental Material: Onset of permanent Taklimakan Desert linked to the mid-Pleistocene transition

2020 ◽  
Author(s):  
Weiguo Liu ◽  
Zhonghui Liu ◽  
et al.
Keyword(s):  
Grain Size ◽  
Taklimakan Desert ◽  
Lop Nur ◽  
Size Data

Materials, methods, and interpretations, Figure S1 (stratigraphic columns and age assignments), Figure S2 (δ<sup>13</sup>C correlated with rainfall and temperature), Figure S3 (detailed view of the onset of desertification), Figure S4 (representative core photos), Figure S5 (Lop Nur and Mazartag δ<sup>13</sup>C), Figure S6 (spectral results), Figure S7 (close-up views of records), and Table S1 (δ<sup>18</sup>O, δ<sup>13</sup>C, and grain-size data).<br>

scholarly journals Supplemental Material: Onset of permanent Taklimakan Desert linked to the mid-Pleistocene transition

2020 ◽  
Author(s):  
Weiguo Liu ◽  
Zhonghui Liu
Keyword(s):  
Grain Size ◽  
Taklimakan Desert ◽  
Lop Nur ◽  
Size Data

Materials, methods, and interpretations, Figure S1 (stratigraphic columns and age assignments), Figure S2 (δ<sup>13</sup>C correlated with rainfall and temperature), Figure S3 (detailed view of the onset of desertification), Figure S4 (representative core photos), Figure S5 (Lop Nur and Mazartag δ<sup>13</sup>C), Figure S6 (spectral results), Figure S7 (close-up views of records), and Table S1 (δ<sup>18</sup>O, δ<sup>13</sup>C, and grain-size data).<br>

scholarly journals Paleoenvironments from robust loess stratigraphy using high-resolution color and grain-size data of the last glacial Krems-Wachtberg record (NE Austria)

2020 ◽  
Vol 248 ◽  
pp. 106602
Author(s):  
Tobias Sprafke ◽  
Philipp Schulte ◽  
Simon Meyer-Heintze ◽  
Marc Händel ◽  
Thomas Einwögerer ◽  
...  
Keyword(s):  
Grain Size ◽  
High Resolution ◽  
Last Glacial ◽  
Size Data ◽  
The Last Glacial

As-Cast Grain Size of Aluminum Alloys Refined by Al-Ti-B Master Alloys

2019 ◽  
Author(s):  
Mark Easton ◽  
David St John ◽  
Prasad Arvind
Keyword(s):  
Grain Size ◽  
Al Alloys ◽  
Good Ability ◽  
Refined Microstructure ◽  
Critical Technology ◽  
Master Alloys ◽  
Near Net Shape ◽  
Empirical Approaches ◽  
Cast Parts ◽  
Size Data

Grain refinement is a critical technology for the successful production of cast parts; whether that be preforms such as extrusion billet or rolling slab, or near net-shape castings. A refined microstructure has many advantages with reduced defects and improved mechanical properties. This article describes the approaches to the prediction of grain size in Al-alloys refined by Al-Ti-B master alloys. Included are empirical approaches based on the generation and analysis of grain size data, the development of analytical equations, and the use of finite element approaches to the prediction of grain sizes. It is clear that researchers have a good ability to predict grain size of Al-alloys grain refined by Al-Ti-B master alloys, although there are still some outstanding challenges, particularly in considering more extreme solidification conditions and poisoning of the master alloys.

Sedimentary environment prediction of grain-size data based on machine learning approach

2020 ◽  
Vol 8 (3) ◽  
pp. SL71-SL78
Author(s):  
Qiao Su ◽  
Yanhui Zhu ◽  
Fang Hu ◽  
Xingyong Xu
Keyword(s):  
Machine Learning ◽  
Grain Size ◽  
Prediction Model ◽  
Sedimentary Environment ◽  
Machine Learning Algorithms ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Data Set ◽  
Sedimentary Environments ◽  
Size Data

Grain size is one of the most important records for sedimentary environment, and researchers have made remarkable progress in the interpretation of sedimentary environments by grain size analysis in the past few decades. However, these advances often depend on the personal experience of the scholars and combination with other methods used together. Here, we constructed a prediction model using the K-nearest neighbors algorithm, one of the machine learning methods, which can predict the sedimentary environments of one core through a known core. Compared to the results of other studies based on the comprehensive data set of grain size and four other indicators, this model achieved a high precision value only using the grain size data. We have also compared our prediction model with other mainstream machine learning algorithms, and the experimental results of six evaluation metrics shed light on that this prediction model can achieve the higher precision. The main errors of the model reflect the length of the conversation area of sedimentary environment, which is controlled by the sedimentary dynamics. This model can provide a quick comparison method of the cores in a similar environment; thus, it may point out the preliminary guidance for further study.

A basic end-member model algorithm for grain-size data of marine sediments

2020 ◽  
Vol 236 ◽  
pp. 106656 ◽  
Author(s):  
Xiaodong Zhang ◽  
Hongmin Wang ◽  
Shumei Xu ◽  
Zuosheng Yang
Keyword(s):  
Grain Size ◽  
Marine Sediments ◽  
Member Model ◽  
Model Algorithm ◽  
Size Data ◽  
End Member Model

Glacio-eustatic variability in the sedimentation pattern over northern Japan during the past 600 ka

2020 ◽  
Author(s):  
Sushree Sova Barik ◽  
Raj K. Singh ◽  
Pratik K. Upadhyaya ◽  
Lisantaraj Biswal ◽  
Nishant Vats ◽  
...  
Keyword(s):  
Grain Size ◽  
Energy Condition ◽  
Ice Sheets ◽  
Japan Sea ◽  
Mineral Analysis ◽  
Sedimentation Pattern ◽  
The Past ◽  
The Japan Sea ◽  
Size Data ◽  
Northern Japan

&lt;p&gt;The Japan Sea is a semi-enclosed marginal sea affected by global sea-level fluctuation, expansion of seasonal and permanent sea-ice cover, having a significant influence on the regional climate neighboring Japan Sea. Middle Pleistocene to Holocene sediments of the Integrated Ocean Drilling Program site U1423 situated in the northeastern part of Japan Sea was processed for the grain size analysis, semi-quantitative mineral analysis, and clay mineral analysis to access glacio-eustatic control on sedimentation pattern over Japan Sea during the past 610 ka. The average time resolution per sample is ~10 kyr. The mean grain size data suggest the dominance of silt size fraction over the sand and clay. The end member modeling of grain size data suggests the presence of two different energy conditions that varied with the time and influenced by the glacio-eustatic changes over the Japan Sea. The grain size data are relatively coarser and deposited in the higher energy condition during the glacial periods in comparison to interglacial periods except for MIS 2, 4, and 8. The higher energy condition during the glacial intervals suggesting deposition of grains due to the melting of seasonal/permanent ice sheets in the northern Japan Sea. The eolian dust brought from the Chinese loess deposits are relative finer in size and dominated by a higher proportion of quartz. During the glacial phases, illite and kaolinite (%) show a decreasing trend than the interglacial phases suggesting less terrigenous input. The high illite and decreased smectite (%) during interglacial phases suggest a higher degree of physical weathering. The significant increase in the smectite/(illite+chlorite) ratio suggests a higher degree of chemical weathering of the nearby source area, which varied over time. The overall study suggests the phase-wise variability in the presence of permanent/seasonal ice sheets and East Aian Winter Monsoon strength during the past 600 ka.&lt;/p&gt;

A synchronous change of mid- to late- Holocene hydroclimate and prehistoric population in coastal East Asia indicated by pollen, XRF and grain size data

2020 ◽  
Author(s):  
Jinheum Park ◽  
Jungjae Park ◽  
Sangheon Yi ◽  
Jin Cheul Kim ◽  
Eunmi Lee ◽  
...  
Keyword(s):  
Grain Size ◽  
Pacific Ocean ◽  
Korean Peninsula ◽  
Late Holocene ◽  
Southern Oscillation ◽  
Precipitation Amount ◽  
Equatorial Pacific ◽  
Equatorial Pacific Ocean ◽  
The Core ◽  
Size Data

&lt;p&gt;A relationship between climate change and prehistoric civilizations is a topic of growing interest. Here, we present a 6,000-year-long pollen, X-ray fluorescence (XRF), and grain size data of the core STP18-03 from the southern Korean peninsula, spanning the mid- to late- Holocene. The proxies generally show a synchronous change throughout the core. During dry periods, reduced precipitation indicated by lower sand proportion (river discharge) would have hindered tree growth, which then resulted in increased titanium erosion from nearby hills, and vice versa. The drying trend is remarkable during ca. 4.8, 4.3, 4.0, 3.3, 2.7-2.3 ka BP and corresponds with sudden dropping points of a summed probability distribution (SPD) of archaeological records found in the Korean Peninsula. This implies that ancient civilizations of Korea responded highly sensitively to abrupt climate deterioration. As an underlying mechanism of the change, we suggest a role of the equatorial Pacific Ocean. The temporal pattern of our arboreal pollen proportion closely follows that of sea surface temperature (SST) data from the Western Pacific Warm Pool (WPWP) region. Furthermore, the dry periods indicated by our multiple proxies coincide with strong El Ni&amp;#241;o&amp;#8211;Southern Oscillation (ENSO) activity, when the core region of the warm seawater pool deviated eastward than usual. This supports that the equatorial Pacific Ocean has served as an important factor for modulating mid- to late- Holocene hydroclimate of the Korean Peninsula, where the East Asian Summer Monsoon (EASM) accounts for nearly 70 percent of the total annual precipitation amount.&lt;/p&gt;

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