scholarly journals THE IDEAL DISTRIBUTION OF FARMERS: EXPLAINING THE EURO-AMERICAN SETTLEMENT OF UTAH

2017 ◽  
Vol 83 (1) ◽  
pp. 75-90 ◽  
Author(s):  
Peter M. Yaworsky ◽  
Brian F. Codding
Keyword(s):  
Population Density ◽  
Ideal Free Distribution ◽  
Negative Relationship ◽  
Coarse Grained ◽  
Distribution Model ◽  
Test Model ◽  
Fine Grained ◽  
Fine Grain ◽  
Model Predictions ◽  
The Ideal

Explaining how and why populations settle a new landscape is central to many questions in American archaeology. Recent advances in settlement research have adopted predictions from the Ideal Free Distribution model (IFD). While tests of IFD predictions to date rely either on archaeologically derived coarse-grained diachronic data or ethnographically derived fine-grained synchronic data, here we provide the first test using historically derived data that is both fine-grained and diachronic. Fine-grain diachronic data allow us to test model predictions at a temporal scale in line with human settlement decisions and to validate proxies for application in archaeological contexts. To test model predictions pertaining to the relationship between population density and habitat quality, we use data from the historical settlement of Utah. The results demonstrate a negative relationship between population density and the quality of habitats occupied. These results are consistent with IFD predictions, suggesting that Euro-American settlement of Utah resulted from individuals attempting to maximize individual returns via agricultural productivity. Our results provide a quantitative and testable explanation for population dispersion over time and explain the spatial distribution of population density today. The results support predictions derived from a general theory of behavior, providing an explanatory framework for colonization events worldwide.

scholarly journals Submarine lava deltas of the 2018 eruption of Kīlauea volcano

2021 ◽  
Vol 83 (4) ◽  
Author(s):  
S. Adam Soule ◽  
Michael Zoeller ◽  
Carolyn Parcheta
Keyword(s):  
Grain Size ◽  
Pore Pressure ◽  
Mechanistic Model ◽  
Large Fraction ◽  
Volcanic Hazards ◽  
Lava Flows ◽  
Coarse Grained ◽  
Fine Grained ◽  
Fine Grain ◽  
Delta Formation

AbstractHawaiian and other ocean island lava flows that reach the coastline can deposit significant volumes of lava in submarine deltas. The catastrophic collapse of these deltas represents one of the most significant, but least predictable, volcanic hazards at ocean islands. The volume of lava deposited below sea level in delta-forming eruptions and the mechanisms of delta construction and destruction are rarely documented. Here, we report on bathymetric surveys and ROV observations following the Kīlauea 2018 eruption that, along with a comparison to the deltas formed at Pu‘u ‘Ō‘ō over the past decade, provide new insight into delta formation. Bathymetric differencing reveals that the 2018 deltas contain more than half of the total volume of lava erupted. In addition, we find that the 2018 deltas are comprised largely of coarse-grained volcanic breccias and intact lava flows, which contrast with those at Pu‘u ‘Ō‘ō that contain a large fraction of fine-grained hyaloclastite. We attribute this difference to less efficient fragmentation of the 2018 ‘a‘ā flows leading to fragmentation by collapse rather than hydrovolcanic explosion. We suggest a mechanistic model where the characteristic grain size influences the form and stability of the delta with fine grain size deltas (Pu‘u ‘Ō‘ō) experiencing larger landslides with greater run-out supported by increased pore pressure and with coarse grain size deltas (Kīlauea 2018) experiencing smaller landslides that quickly stop as the pore pressure rapidly dissipates. This difference, if validated for other lava deltas, would provide a means to assess potential delta stability in future eruptions.

Efficient Utilization of Copper Sulfide Ore in Chile by Flotation

2012 ◽  
Vol 524-527 ◽  
pp. 975-982
Author(s):  
Jiu Shuai Deng ◽  
Shu Ming Wen ◽  
Yong Jun Xian ◽  
Shao Jun Bai ◽  
Dan Liu ◽  
...  
Keyword(s):  
Copper Sulfide ◽  
Copper Recovery ◽  
Coarse Grained ◽  
Efficient Utilization ◽  
Two Stage ◽  
Fine Grained ◽  
Sulfide Ore ◽  
Concentrate Grade ◽  
Copper Sulfide Ore ◽  
The Ideal

The valuable minerals of a copper sulfide ore in Chile, mainly consist of chalcopyrite and chalcocite as well as contain small amounts of cuprite. Gangue minerals are mainly chlorite, quartz, calcite, arsenopyrite, etc. Most are coarse-grained disseminated minerals, while some are fine-grained disseminated minerals. Flotation has been used for processing these ores. The grinding fineness, lime dosage, collector type and dosage all have influences on flotation results. In the present work, the best condition of grinding fineness, lime, and collector dosage was used to separate the copper sulfide and other minerals in the ores. The results showed that, in the grinding fineness of −74 μm accounting for 80%, the vast majority of copper minerals were to monomer dissociation. The flowsheet of one stage roughing, two stage scavenging, and two stage cleaning was adopted. The ideal results of 27.58% and 96.89% for the copper concentrate grade and copper recovery, respectively, were obtained.

Effect of Different Proportion of Coarse and Fine Grain Microstructure on Superplastic Forming Characteristics

2016 ◽  
Vol 838-839 ◽  
pp. 528-533
Author(s):  
Vivek Pancholi ◽  
K. Rohit ◽  
A. Raja
Keyword(s):  
Superplastic Forming ◽  
Stir Zone ◽  
Thickness Variation ◽  
Friction Stir ◽  
Fine Grained ◽  
Fine Grain ◽  
Forming Characteristics ◽  
Inhomogeneous Microstructure ◽  
Bulge Height ◽  
The Ideal

The study was carried out to understand the effect of inhomogeneous microstructure on thickness variation in superplastically formed bulge. Friction stir processing was performed at rotational and traverse speeds of 720rpm and 155mm/min respectively on a 6mm sheet maintaining 50% overlap on the retreating side. Different probe dimensions were selected to obtain different proportions of fine grained stir zone in thickness direction. The proportions of the fine grained stir zone were 25%, 50%, 72% and, 100%. The sheets containing inhomogeneous microstructure were subjected to superplastic bulge forming under constant gas pressure up to a bulge height of 23.5mm. The sheet which was processed with 72% fine grains showed lower thickness variation from edge to apex and the bulge shape in this condition was close to the ideal spherical profile.

scholarly journals Effect of Grinding Time on the Particle Size Distribution Characteristics of Tuff Powder

2021 ◽  
pp. X
Author(s):  
Shuhua LIU ◽  
Hao WANG ◽  
Hongling WANG
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Milling Time ◽  
Milling Process ◽  
Coarse Grained ◽  
Distribution Model ◽  
Fine Grained ◽  
Fractal Characteristics ◽  
Grinding Time

We study the grinding dynamic behavior and particle size distribution (PSD) characteristics of tuff powder. With the analysis of particle size and data of activity test, the results indicate that tuff powder is easy to be ground for the coarse-grained while is difficult for the fine-grained. It is feasible to quantitatively express the milling process of tuff powder by Divas-Aliavden milling dynamic equation. The milling speed and the milling time are negatively correlated, and the grinding efficiency is minimized after 60 min. Equivalent particle size (EPS) is positively linearly correlated with the logarithm of grinding time, while specific surface area (SSA) is inversely correlated, both of them have a highly linear correlation. The PSD of tuff powder, which complies well with the Rosin-Rammler-Bennet (RRB) distribution model, has typical fractal characteristics, and its fractal dimension is also positively correlated with the milling time.

scholarly journals Coarse-grained component concurrency in Earth System modeling

2016 ◽  
Author(s):  
V. Balaji ◽  
R. Benson ◽  
B. Wyman ◽  
I. Held
Keyword(s):  
Climate Models ◽  
System Modeling ◽  
Coarse Grained ◽  
Earth System ◽  
Recursive Structure ◽  
Earth System Modeling ◽  
Component Structure ◽  
Fine Grained ◽  
Fine Grain ◽  
First Results

Abstract. Climate models represent a large variety of processes on a variety of time and space scales, a canonical example of multi-physics multi-scale modeling. Current hardware trends, such as GPUs and MICs, are based on marginal increases in clock speed, coupled with vast increases in concurrency, particularly at the fine grain. Multi-physics codes face particular challenges in achieving fine-grained concurrency, as different physics and dynamics components have different computational profiles, and universal solutions are hard to come by. We propose here one approach for multi-physics codes. These codes are typically structured as components interacting via software frameworks. The component structure of a typical Earth system model consists of a hierarchical and recursive tree of components, each representing a different climate process or dynamical system. This recursive structure generally encompasses a modest level of concurrency at the highest level (e.g atmosphere and ocean on different processor sets) with serial organization underneath. We propose to extend concurrency much further by running more and more lower- and higher-level components in parallel with each other. Each component can further be parallelized on the fine grain, potentially offering a major increase in scalability of Earth system models. We present here first results from this approach, called Coarse-grained Component Concurrency. Within the GFDL Flexible Modeling System, the atmospheric radiative transfer component has been configured to run in parallel with the atmospheric dynamics and all other atmospheric physics components. We will explore the algorithmic challenges involved in such an approach, and present results from such simulations. Plans to achieve even greater levels of coarse-grained concurrency by extending this approach within other components such as the ocean, will be discussed.

scholarly journals Understanding design-based learning context and the associated emotional experience

2020 ◽  
Author(s):  
Feiran Zhang ◽  
Panos Markopoulos ◽  
Tilde Bekker ◽  
Mpuerto Paule-Ruíz ◽  
Martine Schüll
Keyword(s):  
Design Thinking ◽  
Emotional Experience ◽  
Negative Relationship ◽  
Three Dimensions ◽  
Coarse Grained ◽  
Learning Context ◽  
School Students ◽  
Fine Grained ◽  
Multiple Data ◽  
Interaction Task

Abstract Educational settings are emotional places where students experience diverse emotions in relation to academic activities and their outcomes. Emotions, in turn, greatly influence students’ learning process and engagement. Research on emotions in Design-Based Learning (DBL) has so far been coarse-grained examining how students evaluate their overall feelings towards the DBL project. As yet, little is known regarding how specific DBL activities influence students’ emotional experience. Therefore, we report a three-month field study of a DBL project involving 30 middle school students (aged 13–14) addressing dual research purposes: (1) to faithfully reconstruct the manner and sequence of activities during DBL from a fine-grained perspective; and (2) to examine the relationship between these activities and students’ emotional experience. This study used a mixed research method and collected multiple data sources, including experience sampling surveys, classroom observations, and interviews. The research outcomes in this study are multiple. First, this paper reveals detailed inspection regarding the types of task students performed, the strategies of shifting, and executing tasks during the process student experienced. Second, this paper identifies specific types of activities that have a significant positive or negative relationship with students’ emotional experiences. Derived from reported empirical evidence in the present study, this paper furtherly proposes an Activity-and-Affect model of DBL. This model provides a fine-grained description of DBL activity as continuous along three dimensions: task (design thinking process, project management, social interaction) task strategy (single-tasking vs. multitasking), and collaboration strategy (individual or group). Our analysis highlights the variability in how different DBL activities can be associated with different emotions.

scholarly journals Controlling the high temperature deformation behavior and thermal stability of ultra-fine-grained W by re alloying

2021 ◽  
Author(s):  
Johann Kappacher ◽  
Oliver Renk ◽  
Daniel Kiener ◽  
Helmut Clemens ◽  
Verena Maier-Kiener
Keyword(s):  
High Temperature ◽  
Peierls Stress ◽  
Coarse Grained ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Fine Grained ◽  
Boundary Interaction ◽  
Kink Pair ◽  
Fine Grain

Abstract Due to their outstanding properties, ultra-fine-grained tungsten and its alloys are promising candidates to be used in harsh environments, hence it is crucial to understand their high temperature behavior and underlying deformation mechanisms. Therefore, advanced nanoindentation techniques were applied to ultra-fine-grained tungsten–rhenium alloys up to 1073 K. A continuous hardness decrease up to 0.2 $$T_{\text{m}}$$ T m is rationalized by a still dominating effect of the Peierls stress. However, the absence of well-established effects of Rhenium alloying, resulting in a reduced temperature dependence of strength for coarse-grained microstructures, was interpreted as an indication for a diminishing role of kink-pair formation in ultra-fine-grained metals with sufficiently fine grain size. Despite slight grain growth in W, dislocation–grain boundary interaction was identified as the dominating deformation mechanism above 0.2 $$T_{\text{m}}$$ T m . Interaction and accommodation of lattice dislocations with grain boundaries was affected by a reduced boundary diffusivity through alloying with Re. Graphic abstract

Effects of food and oxygen availability on habitat selection by guppies in a laboratory environment

1986 ◽  
Vol 64 (1) ◽  
pp. 88-93 ◽  
Author(s):  
André J. Talbot ◽  
Donald L. Kramer
Keyword(s):  
Food Supply ◽  
Poecilia Reticulata ◽  
Ideal Free Distribution ◽  
Oxygen Availability ◽  
Distribution Model ◽  
Oxygen Effect ◽  
Potential Cost ◽  
Free Distribution ◽  
Ideal Free ◽  
The Ideal

Using the ideal free distribution model proposed in 1970 by S. D. Fretwell and H. L. Lucas, we investigated how local food and oxygen availability influenced the distribution of a group of guppies (Poecilia reticulata, Teleostei, Poeciliidae) among five habitats in a large tank. Our study differed from previous investigations of ideal free distributions in the larger number of habitats available, the presence of resource-free zones between habitats, the visual isolation of the different habitats, the availability of resources over an entire day rather than a short feeding period, and the systematic variation of a potential cost component (low oxygen). In our system, the ideal free distribution model was a poor predictor of fish distributions. Although the proportion of fish in a habitat was positively correlated with food supply, there were too few fish where the food supply was high and too many fish where the food supply was low to equalize average feeding rates in all habitats. The proportion of fish in a habitat was not affected by oxygen concentration, whether food was limited or superabundant. Large, stable differences in density occurred between habitats receiving identical treatments. Time spent by the fish in sampling alternative habitats and the ease with which some individuals could restrict the access of others to the habitats may have contributed to the failure of the ideal free distribution model. The effectiveness with which guppies use the surface film for respiration under hypoxic conditions may explain the lack of a dissolved oxygen effect. Our study demonstrates the need to understand conditions that promote or hinder the appearance of ideal free distributions before they can be used to predict the relationship between animal density and resource availability in nature.

On Improving the Fracture Toughness of a Niai-Based Alloy by Mechanical Alloying

1990 ◽  
Vol 213 ◽  
Author(s):  
J. Kostrubanic ◽  
D.A. Koss ◽  
I.E. Locci ◽  
M. Nathal
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Mechanical Alloying ◽  
Room Temperature ◽  
Coarse Grained ◽  
Fracture Characteristics ◽  
Fine Grained ◽  
Fine Grain

ABSTRACTMechanical alloying (MA) has been used to process the NiAl-based alloy Ni-35Al-2OFe such that a fine-grain (∼2 μm) microstructure is obtained through the addition of 2 v/o Y2O3 particles. When compared to a conventionally processed, coarse-grained (∼;28 μm) Ni-35–20 alloy without the Y2O3 particles, the MA alloy exhibits two to three times higher fracture toughness values, despite a 50% increase in yield strength. Room temperature KQ values as high as 34 √Pa m are observed accompanied by a yield strength in excess of 1100 MPa. Fractography confirms a change in fracture characteristics of the fine-grained MA alloy.

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