The Perception of a Depth Interval with Binocular Disparity Cues

1960 ◽  
Vol 50 (2) ◽  
pp. 257-269 ◽  
Author(s):  
Walter C. Gogel
Keyword(s):  
Binocular Disparity ◽  
Depth Interval

scholarly journals Depth Interval Estimates from Motion Parallax and Binocular Disparity beyond Interaction Space

Perception ◽  
10.1068/p6868 ◽  
2011 ◽  
Vol 40 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Barbara Gillam ◽  
Stephen A Palmisano ◽  
Donovan G Govan
Keyword(s):  
Binocular Disparity ◽  
Motion Parallax ◽  
Interaction Space ◽  
Depth Interval ◽  
Interval Estimates

scholarly journals Reductive dissolution of biogenic magnetite

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Toshitsugu Yamazaki
Keyword(s):  
Japan Sea ◽  
Depth Interval ◽  
Reductive Dissolution ◽  
Magnetic Minerals ◽  
Specific Chemical ◽  
Biogenic Magnetite ◽  
Transmission Electron ◽  
Dissolution Zone ◽  
Central Ridge ◽  
Redox Boundary

Abstract Reductive dissolution of magnetite is known to occur below the Fe-redox boundary in sediments. In this study, detailed processes associated with biogenic magnetite dissolution are documented. A sediment core from the Japan Sea was used for this purpose, in which reductive dissolution of magnetic minerals is known to start at depths of about 1.15 m and is mostly complete within a depth interval of about 0.35 m. Using first-order reversal curve diagrams, preferential dissolution of biogenic magnetite within this interval is estimated from the observation that a narrow peak that extends along the coercivity axis (central ridge), which is indicative of biogenic magnetite, diminishes downcore. Transmission electron microscopy is used to demonstrate that the sediments contain three magnetofossil morpho-types: octahedra, hexagonal prisms, and bullet-shaped forms. Within the reductive dissolution zone, partially etched crystals are commonly observed. With progressive dissolution, the proportion of bullet-shaped magnetofossils decreases, whereas hexagonal prisms become more dominant. This observation can be explained by the differences in resistance to dissolution among crystal planes of magnetite and the differences in surface area to volume ratios. Magnetofossil morphology may reflect the preference of magnetotactic bacterial lineages for inhabiting specific chemical environments in sediments. However, it could also reflect alteration of the original morphological compositions during reductive diagenesis, which should be considered when using magnetofossil morphology as a paleoenvironmental proxy.

scholarly journals The Root-Soil Water Relationship Is Spatially Anisotropic in Shrub-Encroached Grassland in North China: Evidence from GPR Investigation

2021 ◽  
Vol 13 (6) ◽  
pp. 1137
Author(s):  
Xihong Cui ◽  
Zheng Zhang ◽  
Li Guo ◽  
Xinbo Liu ◽  
Zhenxian Quan ◽  
...  
Keyword(s):  
Soil Water ◽  
Root Distribution ◽  
Preferential Flow ◽  
Distribution Density ◽  
Vertical Direction ◽  
Additive Models ◽  
Depth Interval ◽  
Soil Core ◽  
Semi Arid ◽  
Free Area

To analyze the root-soil water relationship at the stand level, we integrated ground-penetrating radar (GPR), which characterized the distribution of lateral coarse roots (>2 mm in diameter) of shrubs (Caragana microphylla Lam.), with soil core sampling, which mapped soil water content (SWC) distribution. GPR surveys and soil sampling were carried out in two plots (Plot 1 in 2017 and Plot 2 in 2018) with the same size (30 × 30 m2) in the sandy soil of the semi-arid shrubland in northern China. First, the survey area was divided into five depth intervals, i.e., 0–20, 20–40, 40–60, 60–80, and 80–100 cm. Each depth interval was then divided into three zones in the horizontal direction, including root-rich canopy-covered area, root-rich canopy-free area, and root-poor area, to indicate different surface distances to the canopy. The generalized additive models (GAMs) were used to analyze the correlation between root distribution density and SWC after the spatial autocorrelation of each variable was eliminated. Results showed that the root-soil water relationship varies between the vertical and horizontal directions. Vertically, more roots are distributed in soil with high SWC and fewer roots in soil with low SWC. Namely, root distribution density is positively correlated with SWC in the vertical direction. Horizontally, the root-soil water relationship is, however, more complex. In the canopy-free area of Plot 1, the root-soil water relationship was significant (p < 0.05) and negatively correlated in the middle two depth intervals (20–40 cm and 40–60 cm). In the same two depth intervals in the canopy-free area of Plot 2, the root-soil water relationship was also significant (p < 0.01) but non-monotonic correlated, that is, with the root distribution density increasing, the mean SWC decreased first and then increased. Moreover, we discussed possible mechanisms, e.g., root water uptake, 3D root distribution, preferential flow along roots, and different growing stages, which might lead to the spatially anisotropic relationship between root distribution and SWC at the stand level. This study demonstrates the advantages of GPR in ecohydrology studies at the field scale that is challenging for traditional methods. Results reported here complement existing knowledge about the root-soil water relationship in semi-arid environments and shed new insights on modeling the complex ecohydrological processes in the root zone.

ON SHALLOW‐HOLE TEMPERATURE MEASUREMENTS—A TEST STUDY IN THE SALTON SEA GEOTHERMAL FIELD

Geophysics ◽  
1977 ◽  
Vol 42 (3) ◽  
pp. 572-583 ◽  
Author(s):  
Tien‐Chang Lee
Keyword(s):  
Numerical Methods ◽  
Ground Surface ◽  
Nonlinear Least Squares ◽  
Geothermal Gradient ◽  
Geothermal Field ◽  
The Other ◽  
Temperature Measurements ◽  
Salton Sea ◽  
Depth Interval ◽  
Average Value

Shallow‐hole (<13 m) temperature measurements made at various depths and/or times may yield reliable values of geothermal gradient and thermal diffusivity if the groundwater table is shallow (a few meters) such that the effect of time‐dependent moisture content and physical properties is negligible. Two numerical methods based on nonlinear least‐squares curve fitting are derived to remove the effect of annual temperature wave at the ground surface. One method can provide information on the gradient and diffusivity as a function of depth while the other gives average value over the depth interval measured. Experiments were carried in six test holes cased with 2 cm OD PVC pipes in the Salton Sea geothermal field. A set of 5 to 7 thermistors was permanently buried inside the individual pipes with dry sand. Consistent gradient determinations have been obtained with both numerical methods from six monthly observations. By linearly extrapolating the depths to the 100°C and 200°C isotherms from the calculated gradients and mean ground temperatures, we have found good agreement with the nearby deep‐well data for four holes. Discrepancy is found for two holes, one of which is located near the field of [Formula: see text] mud volcanoes and the other near the volcanic Red Hill, reflecting complicated local hydrologic conditions.

Relation between Judged and Physical Distance in Multicue Conditions as a Function of Instructions and Tasks

1975 ◽  
Vol 41 (1) ◽  
pp. 171-178 ◽  
Author(s):  
Steven P. Rogers ◽  
Walter C. Gogel
Keyword(s):  
Physical Distance ◽  
Depth Interval ◽  
Verbal Reports ◽  
Bisection Task ◽  
Interval Reproduction

Using a rod adjustable in distance, 48 Os produced equal depth intervals along a floor of a visual alley (interval reproduction) or bisected a given depth interval into two equal parts (bisection). Also, verbal reports were obtained of a depth interval located at a near and farther distance from O (absolute judgments). Two kinds of instructions, “apparent” and “objective,” were used with different Os with each of the three tasks. There was an over-all tendency ( p = .05 on two of three tasks) for apparent instructions to produce less over-constancy or more under-constancy of distance than that produced by objective instructions. This tendency is consistent with a cognitive interpretation of over-constancy of distance. Clear over-constancy was obtained only by the combination of objective instructions and the bisection task. Clear under-constancy was obtained only by the combination of apparent instructions and the method of absolute judgments. The reason for the effect of task on magnitude of distance constancy is not understood.

On the effects of thermal properties structure and water bottom temperature variation on temperature gradients in lake sediments

1986 ◽  
Vol 23 (9) ◽  
pp. 1257-1264 ◽  
Author(s):  
K. Wang ◽  
P. Y. Shen ◽  
A. E. Beck
Keyword(s):  
Heat Flow ◽  
Temperature Variation ◽  
Stratified Medium ◽  
Depth Interval ◽  
Flow Density ◽  
Detailed Knowledge ◽  
Bottom Temperature ◽  
Temperature Variations ◽  
Density Values ◽  
Finite Sum

In heat flow determinations, it is customary to treat the surface temperature variation as a finite sum of Fourier components. The medium is assumed to be homogeneous or horizontally stratified with each layer having a constant conductivity and diffusivity. This allows the effect of each periodic component to be calculated analytically. We extend this formulation to include cases where thermal conductivities in some layers of a stratified medium may vary linearly with depth as have been found in the sediments of some continental lakes. The application of this formalism to temperature measurements in Lake Greifensee and Lac Leman shows that even with excellent records of bottom temperature variations over several years, failure to take into account the conductivity variation leads to errors as high as 20% in heat flow density values, depending on the depth interval used. The combined effects of lack of detailed knowledge of conductivity structure and the use of too short and (or) inaccurate records of bottom temperature variations, leading to very significant errors, are also discussed, with particular reference to the problems arising from a lack of recognition of the existence of nonannual terms in the bottom temperature variation and the use of probes that do not penetrate the sediments deeply enough.

Direct Push Technology and Application to Vertical Profiling of Hydraulic Conductivity in Unconsolidated Formations

2003 ◽  
Author(s):  
Wesley McCall ◽  
Thomas M. Christy ◽  
James J. Butler
Keyword(s):  
Hydraulic Conductivity ◽  
Test Data ◽  
Small Diameter ◽  
Cost Effective ◽  
Depth Interval ◽  
Contaminant Migration ◽  
Slug Tests ◽  
Monitoring Wells ◽  
Direct Push ◽  
Vertical Profiling

Direct push (DP) methods provide a cost-effective alternative to conventional rotary drilling for investigations in unconsolidated formations. DP methods are commonly used for sampling soil gas, soil and groundwater; installing small-diameter monitoring wells; electrical logging; cone penetration testing; and standard penetration tests. Most recently, DP methods and equipment for vertical profiling of formation hydraulic conductivity (K) have been developed. Knowledge of the vertical and lateral variations in K is integral to understanding contaminant migration and, therefore, essential to designing an adequate and effective remediation system. DP-installed groundwater sampling tools may be used to access discrete intervals of the formation to conduct pneumatic slug tests. A small-diameter (38mm OD) single tube protected screen device allows the investigator to access one depth interval per advancement. Alternatively, a larger diameter (54mm OD) dual-tube groundwater profiling system may be used to access the formation at multiple depths during a single advancement. Once the appropriate tool is installed and developed, a pneumatic manifold is installed on the top of the DP rod string. The manifold includes the valving, regulator, and pressure gauge needed for pneumatic slug testing. A small-diameter pressure transducer is inserted via an airtight fitting in the pneumatic manifold, and a data-acquisition device connected to a laptop computer enables the slug test data to be acquired, displayed, and saved for analysis. Conventional data analysis methods can then be used to calculate the K value from the test data. A simple correction for tube diameter has been developed for slug tests in highly permeable aquifers. The pneumatic slug testing technique combined with DP-installed tools provides a cost-effective method for vertical profiling of K. Field comparison of this method to slug tests in conventional monitoring wells verified that this approach provides accurate K values. Use of this new approach can provide data on three-dimensional variations in hydraulic conductivity at a level of detail that has not previously been available. This will improve understanding of contaminant migration and the efficiency and quality of remedial system design, and ultimately, should lead to significant cost reductions.

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