Types of Shear Disparity and the Perception of Surface Inclination

Perception ◽  
1998 ◽  
Vol 27 (2) ◽  
pp. 129-145 ◽  
Author(s):  
Ian P Howard ◽  
Byron J Pierce
Keyword(s):  
Opposite Direction ◽  
Horizontal Axis ◽  
Vertical Shear ◽  
Wide Area ◽  
Textured Surface ◽  
Horizontal Shear ◽  
Curved Boundary ◽  
Surface Inclination ◽  
Depth Contrast ◽  
Depth Enhancement

A study is reported of (i) the perceived inclination of a textured surface in depth about a horizontal axis as a function of disparity magnitude for horizontal-shear disparity, vertical-shear disparity, and rotation disparity; and (ii) interactions between patterns with shear or rotation disparity and superimposed or adjacent patterns or lines with zero disparity. Horizontal-shear disparity produced strong inclination which was enhanced by superimposed or adjacent zero-disparity stimuli. It produced little or no inclination contrast in superimposed or adjacent zero-disparity stimuli. Vertical-shear disparity produced inclination in the opposite direction (induced effect) which was reduced to near zero by a superimposed zero-disparity pattern. Adjacent vertical-shear and zero-disparity patterns appeared inclined at slightly different angles with a wide curved boundary. This suggests that vertical-shear disparities are averaged over a wide area. Rotation disparity produced minimal inclination. A superimposed or adjacent zero-disparity line appeared strongly inclined. A superimposed or adjacent zero-disparity pattern appeared vertical and caused the pattern with rotation disparity to appear inclined. Four mechanisms are proposed to account for the results: depth contrast, depth enhancement, deformation-disparity processing, and disparity transfer arising from cyclovergence.

Types of Size Disparity and the Perception of Surface Slant

Perception ◽  
1997 ◽  
Vol 26 (12) ◽  
pp. 1503-1517 ◽  
Author(s):  
Byron J Pierce ◽  
Ian P Howard
Keyword(s):  
Vertical Axis ◽  
Textured Surface ◽  
Curved Boundary ◽  
Surface Slant ◽  
Size Disparity ◽  
Horizontal Size ◽  
Depth Contrast ◽  
Depth Enhancement ◽  
Vertical Size

We examined (i) perceived slant of a textured surface about a vertical axis as a function of disparity magnitude for horizontal-size disparity, vertical-size disparity, and overall-size disparity; and (ii) interactions between patterns with various types and magnitudes of size disparity and superimposed or adjacent zero-disparity stimuli. Horizontal-size disparity produced slant which increased with increasing disparity, was enhanced by superimposed zero-disparity stimuli, and induced contrasting slant in superimposed or adjacent zero-disparity stimuli. Vertical-size disparity produced opposite slant (induced effect) which was reduced to near zero by a superimposed zero-disparity pattern and both patterns appeared as one surface. Adjacent vertical-size-disparity and zero-disparity patterns appeared as separate surfaces with a wide curved boundary. Overall-size disparity produced slant which was enhanced by a superimposed zero-disparity pattern and less so by a zero-disparity line, and induced more slant in a zero-disparity line than in a zero-disparity pattern. The results are discussed in terms of depth underestimation of isolated surfaces, depth enhancement, depth contrast, and the processing of deformation disparity.

scholarly journals Numerical and Experimental Simulation of Extreme Operational Conditions for Horizontal Axis Wind Turbines Based on the IEC Standard

2020 ◽  
Author(s):  
Kamran Shirzadeh ◽  
Horia Hangan ◽  
Curran Crawford
Keyword(s):  
Wind Turbines ◽  
Test Chamber ◽  
Horizontal Axis ◽  
Vertical Shear ◽  
Experimental Simulation ◽  
Extreme Condition ◽  
Horizontal Shear ◽  
Operational Conditions ◽  
Physical Experiments ◽  
Horizontal Axis Wind Turbines

Abstract. In this study, the possibility of simulating some transient and deterministic extreme operational conditions for horizontal axis wind turbines based on the IEC 61400-1 standard in the Wind Engineering, Energy and Environment (WindEEE) Dome at Western University was investigated. There are 60 fans (a matrix of 4 by 15 with 0.8 m diameter each) on one of the walls of this hexagonal wind tunnel for creating straight flows which the power set-points for each fan can be specified individually. In addition, these fans have adjustable Inlet Guiding Vanes (IGV) that can be controlled uniformly across all of the fans. Using these capabilities, experiments were carried out for the Extreme Operational Gust (EOG), positive and negative Extreme Vertical Shear (EVS), and Extreme Horizontal Shear (EHS) cases, tailored for a 2.2 m HAWT scaled turbine. This study started by developing a numerical model for the test chamber, then using it to tune the fan setups for each extreme condition with proper scaling. Physical experiments then carried out using those settings, then a comparison made between the flow field time history and the prescribed conditions from the standard. The comparisons show promising results, this can be a contribution to future scholars investigating the interaction of the HAWT with these conditions in physical experiments.

scholarly journals Experimental and numerical simulation of extreme operational conditions for horizontal axis wind turbines based on the IEC standard

2020 ◽  
Vol 5 (4) ◽  
pp. 1755-1770
Author(s):  
Kamran Shirzadeh ◽  
Horia Hangan ◽  
Curran Crawford
Keyword(s):  
Wind Turbines ◽  
Test Chamber ◽  
Horizontal Axis ◽  
Vertical Shear ◽  
Extreme Condition ◽  
Horizontal Shear ◽  
Horizontal Axis Wind Turbine ◽  
Operational Conditions ◽  
Energy And Environment ◽  
Horizontal Axis Wind Turbines

Abstract. In this study, the possibility of simulating some transient and deterministic extreme operational conditions for horizontal axis wind turbines based on the IEC 61400-1 standard using 60 individually controlled fans in the Wind Engineering, Energy and Environment (WindEEE) Dome at Western University was investigated. Experiments were carried out for the extreme operational gust (EOG), positive and negative extreme vertical shear (EVS), and extreme horizontal shear (EHS) cases, tailored for a scaled 2.2 m horizontal axis wind turbine. For this purpose, firstly a numerical model for the test chamber was developed and used to obtain the fans' configurations for simulating each extreme condition with appropriate scaling prior to the physical experiments. The results show the capability of using numerical modelling to predict the fans' setup based on which physical simulations can generate IEC extreme conditions in the range of interest.

Depth Interactions between Inclined and Slanted Surfaces in Vertical and Horizontal Orientations

Perception ◽  
1998 ◽  
Vol 27 (1) ◽  
pp. 87-103 ◽  
Author(s):  
Byron J Pierce ◽  
Ian P Howard ◽  
Catina Feresin
Keyword(s):  
Vertical Shear ◽  
Test Surface ◽  
Horizontal Shear ◽  
Frontal Surface ◽  
Horizontal Orientation ◽  
Size Disparity ◽  
Horizontal Size ◽  
Depth Contrast ◽  
Effects Of Rotation ◽  
Vertical Size

Depth interactions between a frontal test surface and an adjacent induction surface were measured as a function of the type of disparity in the induction surface and of the vertical/horizontal orientation of the boundary between the surfaces. The types of disparity were 4° horizontal-shear disparity, 4° vertical-shear disparity, and 4° rotation disparity; 4% horizontal-size disparity, 4% vertical-size disparity, and 4% overall-size disparity. Depth contrast in a frontal surface was produced by surfaces containing horizontal-size disparity but not by those containing horizontal-shear disparity. Vertical-shear and vertical-size disparities produced induced effects in both the induction and the test surface, which is here explained in terms of deformation-disparity processing. Effects of rotation disparity on the test surface can be accounted for in terms of cyclovergence, deformation disparity, and perhaps also depth contrast. The fact that horizontal-size disparity produced more depth contrast than horizontal-shear disparity is due to an anisotropy of disparity processing rather than the relative orientation of the surfaces. Ground surfaces appeared more slanted than ceiling surfaces. Surfaces containing horizontal disparities produced a sharp boundary with the test surface because horizontal disparities are processed locally. Surfaces with vertical disparities produced a gradual boundary with the test surface because vertical disparities are processed over a wider area.

DETERMINATION OF WIND SHEAR AND TURBULENCE INTENSITY ACCORDING TO YAK42-D “ROSHYDROMET” RESEARCH AIRCRAFT DATA

2021 ◽  
pp. 117-129
Author(s):  
V. V. VOLKOV ◽  
◽  
M. A. STRUNIN ◽  
A. M. STRUNIN ◽  
◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Wind Shear ◽  
Vertical Shear ◽  
Horizontal Shear ◽  
S 100 ◽  
Research Aircraft ◽  
The Difference ◽  
Wind Shears ◽  
Aircraft Data

The results of the development and comparative analysis of methods for determining wind shear in the atmosphere (regression and difference ones) based on research aircraft data are presented. It is shown that shear calculation by the regression method gives the error of 0.002-0.006 (m/s)/km (depending on the length of the measurement sections) for horizontal shears and 0.04-0.12 (m/s)/100 m for vertical shears; the respective error of the difference method is 0.007 (m/s)/km and 0.07 (m/s)/100 m. Based on the Yak-42D “Roshydromet” research aircraft data, the values of shears of two horizontal components of wind speed in three directions (two horizontal and vertical) were calculated. According to the data of two research aircraft flights, the maximum values of the horizontal shear of wind speed components were reached above the boundary layer and were equal to 0.2 (m/s)/km, and the vertical shear was 1.2 (m/s)/100 m. The energy profiles of horizontal and vertical turbulent pulsations are constructed, it is shown that intense turbulence smooths wind shears in the convective atmospheric boundary layer.

Developing versus Nondeveloping Disturbances for Tropical Cyclone Formation. Part I: North Atlantic

2012 ◽  
Vol 140 (4) ◽  
pp. 1047-1066 ◽  
Author(s):  
Melinda S. Peng ◽  
Bing Fu ◽  
Tim Li ◽  
Duane E. Stevens
Keyword(s):  
Water Vapor ◽  
North Atlantic ◽  
Large Scale ◽  
Relative Vorticity ◽  
Water Vapor Content ◽  
Vertical Shear ◽  
Horizontal Shear ◽  
Synoptic Scale ◽  
The North ◽  
The North Atlantic

This study investigates the characteristic differences of tropical disturbances that eventually develop into tropical cyclones (TCs) versus those that did not, using global daily analysis fields of the Navy Operational Global Atmospheric Prediction System (NOGAPS) from the years 2003 to 2008. Time filtering is applied to the data to extract tropical waves with different frequencies. Waves with a 3–8-day period represent the synoptic-scale disturbances that are representatives as precursors of TCs, and waves with periods greater than 20 days represent the large-scale background environmental flow. Composites are made for the developing and nondeveloping synoptic-scale disturbances in a Lagrangian frame following the disturbances. Similarities and differences between them are analyzed to understand the dynamics and thermodynamics of TC genesis. Part I of this study focuses on events in the North Atlantic, while Part II focuses on the western North Pacific. A box difference index (BDI), accounting for both the mean and variability of the individual sample, is introduced to subjectively and quantitatively identify controlling parameters measuring the differences between developing and nondeveloping disturbances. Larger amplitude of the BDI implies a greater possibility to differentiate the difference between two groups. Based on their BDI values, the following parameters are identified as the best predictors for cyclogenesis in the North Atlantic, in the order of importance: 1) water vapor content within 925 and 400 hPa, 2) rain rate, 3) sea surface temperature (SST), 4) 700-hPa maximum relative vorticity, 5) 1000–600-hPa vertical shear, 6) translational speed, and 7) vertically averaged horizontal shear. This list identifies thermodynamic variables as more important controlling parameters than dynamic variables for TC genesis in the North Atlantic. When the east and west (separated by 40°W) Atlantic are examined separately, the 925–400-hPa water vapor content remains as the most important parameter for both regions. The SST and maximum vorticity at 700 hPa have higher importance in the east Atlantic, while SST becomes less important and the vertically averaged horizontal shear and horizontal divergence become more important in the west Atlantic.

Magnetosensitive Polymer Composites and Effect of Magnetic Field Directivity on their Properties

2016 ◽  
Vol 251 ◽  
pp. 3-7 ◽  
Author(s):  
Egidijus Dragašius ◽  
Evguenia Korobko ◽  
Zoya Novikava ◽  
Elena Sermyazhko
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Magnetic Properties ◽  
Polymer Composites ◽  
Matrix Material ◽  
Vertical Shear ◽  
Horizontal Shear ◽  
Dispersed Particles ◽  
The Magnetic Field ◽  
Ferromagnetic Particles

Mechanical properties of polymer composite materials, containing ferromagnetic small dispersed particles of carbonyl iron that create structures along force lines of the magnetic field have been investigated. In paper the influence of the polymer matrix material and the orientation of ferromagnetic particles inside it on the properties of polymer composites are considered in the regimes of horizontal shear, vertical shear and periodical (sinusoidal) deformation of the samples. Magnetic properties at the change of magnetic field induction B in the range of 0 to 1 T are determined.

scholarly journals Numerical Study of Horizontal Shear Instability Waves along Narrow Cold Frontal Rainbands

2011 ◽  
Vol 68 (4) ◽  
pp. 878-903 ◽  
Author(s):  
Masayuki Kawashima
Keyword(s):  
Numerical Study ◽  
Leading Edge ◽  
Shear Instability ◽  
Vertical Shear ◽  
Horizontal Shear ◽  
Edge Waves ◽  
Instability Waves ◽  
Low Level ◽  
Wide Range ◽  
The Mean

Abstract The effects of variations in low-level ambient vertical shear and horizontal shear on the alongfront variability of narrow cold frontal rainbands (NCFRs) that propagate into neutral and slightly unstable environments are investigated through a series of idealized cloud-resolving simulations. In cases initialized with slightly unstable sounding and weak ambient cross-frontal vertical shears, core-gap structures of precipitation along NCFRs occur that are associated with wavelike disturbances that derive their kinetic energy mainly from the mean local vertical shear and buoyancy. However, over a wide range of environmental conditions, core-gap structures of precipitation occur because of the development of a horizontal shear instability (HSI) wave along the NCFRs. The growth rate and amplitude of the HSI wave decrease significantly as the vertical shear of the ambient cross-front wind is reduced. These decreases are a consequence of the enhancement of the low-level local vertical shear immediately behind the leading edge. The strong local vertical shear acts to damp the vorticity edge wave on the cold air side of the shear zone, thereby suppressing the growth of the HSI wave through the interaction of the two vorticity edge waves. It is also noted that the initial wavelength of the HSI wave increases markedly with increasing horizontal shear. The local vertical shear around the leading edge is shown to damp long HSI waves more strongly than short waves, and the horizontal shear dependency of the wavelength is explained by the decrease in the magnitude of the vertical shear relative to that of the horizontal shear.

Radial profiling of the three formation shear moduli and its application to well completions

Geophysics ◽  
2006 ◽  
Vol 71 (6) ◽  
pp. E65-E77 ◽  
Author(s):  
Bikash K. Sinha ◽  
Badarinadh Vissapragada ◽  
Lasse Renlie ◽  
Sveinung Tysse
Keyword(s):  
Shear Modulus ◽  
Mechanical Damage ◽  
Vertical Shear ◽  
Horizontal Shear ◽  
Stress Concentrations ◽  
Shear Moduli ◽  
Anisotropic Formation ◽  
Mobility Impaired ◽  
Well Completions ◽  
Optimum Production

Near-wellbore alteration in shear stiffnesses in the three orthogonal planes can be described in terms of radial variations of the three shear moduli or slownesses. The three shear moduli are different in formations exhibiting orthorhombic or lower degree of symmetry, as is the case in deviated wellbores in triaxially stressed formations. These shear moduli are affected by factors such as overbalanced drilling, borehole stress concentrations, shale swelling, near-wellbore mechanical damage, and supercharging of permeable formations. The two vertical shear moduli [Formula: see text] and [Formula: see text] in an anisotropic formation with a vertical [Formula: see text]-axis are obtained from crossed-dipole sonic data, whereas the horizontal shear modulus [Formula: see text] is estimated from borehole Stoneley data. The effective shear modulus [Formula: see text] is smaller than the vertical shear moduli [Formula: see text] or [Formula: see text] in a poroelastic formation exhibiting high horizontal fluid mobility. Consequently, analyses of radial profiling of the three shear moduli in a reasonably uniform lithology interval yield useful correlations, with mobility impaired by an increased amount of clay or by near-wellbore damage in a shaley sand reservoir interval in a North Sea vertical well. Radial profiling results help to identify suitable depths for fluid sampling and to complete a well for optimum production.

scholarly journals Investigating the loads and performance of a model horizontal axis wind turbine under reproducible IEC extreme operational conditions

2021 ◽  
Vol 6 (2) ◽  
pp. 477-489
Author(s):  
Kamran Shirzadeh ◽  
Horia Hangan ◽  
Curran Crawford ◽  
Pooyan Hashemi Tari
Keyword(s):  
Power Generation ◽  
Wind Turbine ◽  
Extreme Event ◽  
Horizontal Axis ◽  
Force Balance ◽  
Dynamic Responses ◽  
Horizontal Shear ◽  
Horizontal Axis Wind Turbine ◽  
Operational Conditions ◽  
Wind Shears

Abstract. The power generation and loading dynamic responses of a 2.2 m diameter horizontal axis wind turbine (HAWT) under some of the IEC 61400-1 transient extreme operational conditions, more specifically extreme wind shears (EWSs) and extreme operational gust (EOG), that were reproduced at the WindEEE Dome at Western University were investigated. The global forces were measured by a multi-axis force balance at the HAWT tower base. The unsteady horizontal shear induced a significant yaw moment on the rotor with a dynamic similar to that of the extreme event without affecting the power generation. The EOG severely affected all the performance parameters of the turbine.

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