The New American Wind Tunnels

1930 ◽  
Vol 34 (235) ◽  
pp. 559-576 ◽  
Author(s):  
R. McKinnon Wood
Keyword(s):  
Wind Tunnels ◽  
Small Scale ◽  
Science And Engineering ◽  
Scale Models

Much has been learnt, in many branches of science and engineering, from the use of small scale models. The earliest successful experiments in humanly contrived flight with heavier-than-air craft, were made with small scale prototypes of the man-carrying machine of a later day : experiments with man-carrying craft, kite, glider and power-driven, followed.

scholarly journals Cognitive map formation through haptic and visual exploration of tactile city-like maps

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Loes Ottink ◽  
Marit Hoogendonk ◽  
Christian F. Doeller ◽  
Thea M. Van der Geest ◽  
Richard J. A. Van Wezel
Keyword(s):  
Visual Information ◽  
Spatial Information ◽  
Cognitive Map ◽  
Visual Exploration ◽  
Distinct Advantage ◽  
Small Scale ◽  
Map Learning ◽  
Scale Models ◽  
Spatial Tasks ◽  
Tactile Maps

AbstractIn this study, we compared cognitive map formation of small-scale models of city-like environments presented in visual or tactile/haptic modalities. Previous research often addresses only a limited amount of cognitive map aspects. We wanted to combine several of these aspects to elucidate a more complete view. Therefore, we assessed different types of spatial information, and consider egocentric as well as allocentric perspectives. Furthermore, we compared haptic map learning with visual map learning. In total 18 sighted participants (9 in a haptic condition, 9 visuo-haptic) learned three tactile maps of city-like environments. The maps differed in complexity, and had five marked locations associated with unique items. Participants estimated distances between item pairs, rebuilt the map, recalled locations, and navigated two routes, after learning each map. All participants overall performed well on the spatial tasks. Interestingly, only on the complex maps, participants performed worse in the haptic condition than the visuo-haptic, suggesting no distinct advantage of vision on the simple map. These results support ideas of modality-independent representations of space. Although it is less clear on the more complex maps, our findings indicate that participants using only haptic or a combination of haptic and visual information both form a quite accurate cognitive map of a simple tactile city-like map.

scholarly journals Roughness Lengths for Momentum and Heat Derived from Outdoor Urban Scale Models

2007 ◽  
Vol 46 (7) ◽  
pp. 1067-1079 ◽  
Author(s):  
M. Kanda ◽  
M. Kanega ◽  
T. Kawai ◽  
R. Moriwaki ◽  
H. Sugawara
Keyword(s):  
Wind Direction ◽  
Roughness Length ◽  
Scale Dependence ◽  
Scale Model ◽  
Small Scale ◽  
Physical Scale ◽  
Scale Models ◽  
Roughness Lengths ◽  
Urban Sites ◽  
Obstacle Height

Abstract Urban climate experimental results from the Comprehensive Outdoor Scale Model (COSMO) were used to estimate roughness lengths for momentum and heat. Two different physical scale models were used to investigate the scale dependence of the roughness lengths; the large scale model included an aligned array of 1.5-m concrete cubes, and the small scale model had a geometrically similar array of 0.15-m concrete cubes. Only turbulent data from the unstable boundary layers were considered. The roughness length for momentum relative to the obstacle height was dependent on wind direction, but the scale dependence was not evident. Estimated values agreed well with a conventional morphometric relationship. The logarithm of the roughness length for heat relative to the obstacle height depended on the scale but was insensitive to wind direction. COSMO data were used successfully to regress a theoretical relationship between κB−1, the logarithmic ratio of roughness length for momentum to heat, and Re*, the roughness Reynolds number. Values of κB−1 associated with Re* for three different urban sites from previous field experiments were intercompared. A surprising finding was that, even though surface geometry differed from site to site, the regressed function agreed with data from the three urban sites as well as with the COSMO data. Field data showed that κB−1 values decreased as the areal fraction of vegetation increased. The observed dependency of the bulk transfer coefficient on atmospheric stability in the COSMO data could be reproduced using the regressed function of Re* and κB−1, together with a Monin–Obukhov similarity framework.

Fine-Scale Fire Spread in Pine Straw

Fire ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 69
Author(s):  
Daryn Sagel ◽  
Kevin Speer ◽  
Scott Pokswinski ◽  
Bryan Quaife
Keyword(s):  
Fire Spread ◽  
Small Scale ◽  
Natural Setting ◽  
Fine Scale ◽  
Prescribed Burn ◽  
Fire Dynamics ◽  
Rate Of Spread ◽  
Scale Models ◽  
Fire Front ◽  
Visible Images

Most wildland and prescribed fire spread occurs through ground fuels, and the rate of spread (RoS) in such environments is often summarized with empirical models that assume uniform environmental conditions and produce a unique RoS. On the other hand, representing the effects of local, small-scale variations of fuel and wind experienced in the field is challenging and, for landscape-scale models, impractical. Moreover, the level of uncertainty associated with characterizing RoS and flame dynamics in the presence of turbulent flow demonstrates the need for further understanding of fire dynamics at small scales in realistic settings. This work describes adapted computer vision techniques used to form fine-scale measurements of the spatially and temporally varying RoS in a natural setting. These algorithms are applied to infrared and visible images of a small-scale prescribed burn of a quasi-homogeneous pine needle bed under stationary wind conditions. A large number of distinct fire front displacements are then used statistically to analyze the fire spread. We find that the fine-scale forward RoS is characterized by an exponential distribution, suggesting a model for fire spread as a random process at this scale.

Tearing Resistance of Advanced Double Hulls

1997 ◽  
Vol 41 (01) ◽  
pp. 69-80
Author(s):  
Mark D. Bracco ◽  
Tomasz Wierzbicki
Keyword(s):  
Steady State ◽  
Cutting Force ◽  
Average Error ◽  
Small Scale ◽  
Complex Deformation ◽  
Scale Models ◽  
State Force ◽  
Deformation Patterns ◽  
Double Hull ◽  
Tearing Resistance

This paper studies the cutting by a wedge of advanced double hull (ADH) small-scale models. A total of six cutting experiments were performed with six different wedge geometries. Complex deformation patterns observed in the damaged specimens were simplified to obtain a closed-form upper bound for the steady-state cutting force. The ADH steady-state cutting force solution varied from 6% above to 12% below the experimental mean steady-state force. The absolute average error is 5%.

Wave Energy Hyperbaric Converter: Small Scale Models, Prototype and Control Strategies

2012 ◽  
Author(s):  
Segen F. Estefen ◽  
Paula B. Garcia-Rosa ◽  
Eliab Ricarte ◽  
Paulo Roberto da Costa ◽  
Marcelo M. Pinheiro ◽  
...  
Keyword(s):  
Control Strategies ◽  
Applied Pressure ◽  
Ocean Waves ◽  
Wave Climate ◽  
Small Scale ◽  
Scale Models ◽  
Pressure Water ◽  
Climate Analysis ◽  
Brazilian Northeast ◽  
And Control

A device for electricity generation from ocean waves has been developed for installation on the Brazilian northeast coast. It is based on pumping modules and a two-stage accumulator linked to a hyperbaric chamber in order to provide a prescribed high pressure water flow, which operates a turbine coupled with an electrical generator. In the period between 2001 and 2007, wave tank testing of small-scale models have been carried out. A prototype with two pumping modules is presently installed in the Port of Pecém. This paper describes an overview of the device development since the first tests to the installation of the prototype. Wave climate analysis, design analysis and optimization studies have been developed and are briefly revised in this study. Furthermore, control strategies are proposed to optimize the electrical output considering the proper combination of both pressure and flow rate as a function of the predominant wave climate, when the applied pressure is constant and the generator is a synchronous machine.

Dynamic Compression of Rigid and Flexible Risers: Part I — Experimental Results

2003 ◽  
Author(s):  
Andre´ L. C. Fujarra ◽  
Alexandre N. Simos ◽  
Newton Y. Yamamoto
Keyword(s):  
Dynamic Compression ◽  
Critical Issue ◽  
Companion Paper ◽  
Experimental Results ◽  
Small Scale ◽  
Steel Catenary Riser ◽  
Scale Models ◽  
Floating System ◽  
The Subject ◽  
Flexible Risers

Dynamic compression is a critical issue for the viability of submerged lines used in offshore applications, especially for deepwater operations. The subject has been addressed both numerically and analytically. However, few experimental data exist in literature for validation purposes. The aim of this first paper is to present experimental results on the dynamic compression of rigid and flexible risers, obtained in towing-tank tests. Two small-scale models have been built, one emulating the dynamic behavior of a steel catenary riser (SCR) and the other corresponding to a much more flexible case. Uniform circular motion has been applied to the top of the line, representing the floating system oscillation. Four different amplitudes have been considered, each one of them with five different frequencies. The influence of current velocity has also been evaluated. Tension has been measured at the top. In this work the small-scale models and experimental setup are described and some comprehensive results are presented and discussed. In a companion paper, comparisons between theoretical (numerical and analytical) and experimental results are presented.

scholarly journals Attractiveness of thermally different, uniformly black targets to horseflies: Tabanus tergestinus prefers sunlit warm shiny dark targets

2019 ◽  
Vol 6 (10) ◽  
pp. 191119 ◽  
Author(s):  
Gábor Horváth ◽  
Ádám Pereszlényi ◽  
Tímea Tóth ◽  
Szabolcs Polgár ◽  
Imre M. Jánosi
Keyword(s):  
Field Experiments ◽  
Elevated Temperatures ◽  
Thermal Characteristics ◽  
Optical Characteristics ◽  
Degree Of Polarization ◽  
Small Scale ◽  
Host Animal ◽  
Reflected Light ◽  
Scale Models ◽  
Imaging Polarimetry

From a large distance tabanid flies may find their host animal by means of its shape, size, motion, odour, radiance and degree of polarization of host-reflected light. After alighting on the host, tabanids may use their mechano-, thermo-, hygro- and chemoreceptors to sense the substrate characteristics. Female tabanids prefer to attack sunlit against shady dark host animals, or dark against bright hosts for a blood meal, the exact reasons for which are unknown. Since sunlit darker surfaces are warmer than shady ones or sunlit/shady brighter surfaces, the differences in surface temperatures of dark and bright as well as sunlit and shady hosts may partly explain their different attractiveness to tabanids. We tested this observed warmth preference in field experiments, where we compared the attractiveness to tabanids ( Tabanus tergestinus ) of a warm and a cold shiny black barrel imitating dark hosts with the same optical characteristics. Using imaging polarimetry, thermography and Schlieren imaging, we measured the optical and thermal characteristics of both barrels and their small-scale models. We recorded the number of landings on these targets and measured the time periods spent on them. Our study revealed that T. tergestinus tabanid flies prefer sunlit warm shiny black targets against sunlit or shady cold ones with the same optical characteristics. These results support our new hypothesis that a blood-seeking female tabanid prefers elevated temperatures, partly because her wing muscles are more rapid and her nervous system functions better (due to faster conduction velocities and synaptic transmission of signals) in a warmer microclimate, and thus, she can avoid the parasite-repelling reactions of host animals by a prompt take-off.

Sign in / Sign up

Export Citation Format

Share Document