ORIENTATION OF AEDES AEGYPTI IN VERTICAL AIR CURRENTS

1967 ◽  
Vol 99 (3) ◽  
pp. 303-308 ◽  
Author(s):  
P. N. Daykin
Keyword(s):  
Aedes Aegypti ◽  
Air Flow ◽  
Sensory Information ◽  
Vertical Movement ◽  
Stripe Pattern ◽  
Vertical Movements ◽  
Speed Sensor ◽  
Air Stream ◽  
Cybernetic System ◽  
Air Speed

AbstractThe orientation of Aedes aegypti in an upward or downward vertical air current was studied. The vertical movements of A. aegypti which have been activated by CO2 are always against the air flow and toward the inlet end, where the insects alight and probe. With sufficient illumination A. aegypti locate an invisible artificial host whether it is at the top with air moving down or at the bottom with air moving up. They do not attempt to locate a visible, black, artificial host placed downstream. Body attitude is similar in upward or downward air flow. The mosquitoes follow the vertical movement of a surrounding spiral stripe pattern, whether stripe movement is upward or downward, whether air is still or moving vertically with or against the stripes. They will not fly against stripe movement to reach an upstream host, real or artificial. Repellent vapor destroys the upstream orientation when air flow is vertical but not when the flow is horizontal. The stripe-following action is not affected by repellent. The experiments indicate that A. aegypti possesses a vertical-air-speed sensor, of a mechanical type, to direct movement up or down in a vertical air stream. The cybernetic system must be complex and requires cooperative use of mechanical and optical sensory information channels. The initial action of repellent vapor appears to be peripheral rather than central to the nervous system, and to affect only the mechano-, chemo-, and thermo-receptors.

scholarly journals EXPERIMENTAL RESEARCH ON THE DISTRIBUTION OF AIR STREAM VELOCITY USING THE TWO-LEVEL CYCLONE / EKSPERIMENTINIAI ORO SRAUTO GREIČIŲ PASISKIRSTYMO DVIEJŲ LYGIŲ CIKLONE TYRIMAI

2013 ◽  
Vol 5 (4) ◽  
pp. 330-336 ◽  
Author(s):  
Egidijus Baliukas ◽  
Pranas Baltrėnas
Keyword(s):  
Air Flow ◽  
Solid Particles ◽  
Maximum Speed ◽  
Stream Velocity ◽  
Velocity Measurements ◽  
Air Velocity ◽  
Air Volume ◽  
Air Stream ◽  
Before And After ◽  
Air Speed

In order to properly analysethe operation of a two-level multichannel cyclone,a studyon how air flow moves inside the cyclone is necessary. The two-level multichannel cyclone is designed to separate solid particles from the air stream andhas been built in the Environmental Protection Laboratory at Vilnius Gediminas Technical University. Researches on findinghow theair flow distributes withintwo levels and channels of the six-channel cyclone were made. Air velocity was measured using multimeter Testo–400 and dynamic Pito tube. Air velocity measurements in ducts before and after thedevice were done using an anemometer. The results showed that the air volume at both cyclone levels wereequal, and air velocity inthe channels that werethe same at both levels was also distributed equally. The highest air speed was measured at the end of the last IV channel and reached 13 m/s. Minimum air velocity can be observed when the rings are arranged in such way that 75% of the air flow returns to the previous channel, and the maximum speed is when the previous channel returns 25% of the air flow. Article in Lithuanian. Santrauka Siekiant tinkamai išanalizuoti dviejų lygių daugiakanalio ciklono veikimą būtina išnagrinėti valomo oro srauto judėjimą. Šis įrenginys skirtas kietosioms dalelėms iš oro srauto valyti. Daugiakanalis dviejų lygių ciklonas sukurtas ir pastatytas Vilniaus Gedimino technikos universiteto Aplinkos apsaugos laboratorijoje. Tyrimais siekiama nustatyti oro srauto pasiskirstymą dviejuose šešiakanalio ciklono lygiuose bei kanaluose. Oro greičiams kanaluose nustatyti naudojamas daugiafunkcis matuoklis Testo-400 ir dinaminis Pito vamzdelis. Oro srauto greičiams matuoti ortakiuose prieš ir už įrenginio naudojamas sparninis anemometras. Rezultatai rodė, kad į abu ciklone įrengtus lygius patenka vienodas oro tūris, ir greičiai šių lygių kanaluose pasiskirsto vienodai. Didžiausias greitis – 13 m/s užfiksuotas paskutiniojo kanalo pabaigoje. Mažiausi oro greičiai kanaluose esti, kai žiedai sudėti taip, kad 75 % oro srauto grįžtų į ankstesnį kanalą, o didžiausias greitis yra tada, kai į ankstesnį kanalą grįžta 25 % oro srauto.

The Swimbladder and the Vertical Movement of Teleostean Fishes

1951 ◽  
Vol 28 (4) ◽  
pp. 553-566
Author(s):  
F. R. HARDEN JONES
Keyword(s):  
Body Wall ◽  
Bladder Wall ◽  
Relative Size ◽  
Perca Fluviatilis ◽  
Vertical Movement ◽  
Physical Factors ◽  
Vertical Movements ◽  
Perch Perca Fluviatilis ◽  
Percentage Volume ◽  
Two Factors

The vertical movements of a teleostean fish may be restricted by the presence of the swimbladder, which will increase or decrease in volume when the fish moves up or down in the water. It is shown that the restriction that the swimbladder imposes to vertical movements involving a reduction in pressure will depend on physical factors such as (1) The resistance that the bladder and body wall offer to the expansion of the bladder gas. (2) The percentage volume of the swimbladder and the density change of the fish when it is subjected to a reduction in pressure. (3) The pressure reduction that leads to the rupture of the bladder wall. A distinction is made between rapid and slow movements. In the former the compensatory ability of the fish must be considered and in the latter the speed with which the fish can accommodate itself to pressure changes. An equation is derived from which the minimum speed at which a physoclist can migrate from deep to shallow water can be calculated. To solve the equation two factors must be determined experimentally. Various experiments are described which were made on the perch, Perca fluviatilis, the wrasse, Crenilabrus melops, the rockling, Onos mustela and the dragonet, Callionymus lyra. The results showed that there was a relation between the relative size of the swimbladder and the change in the density of a fish when it is subjected to a reduction in pressure; that the bladder and body wall of the perch offer little resistance to the expansion of the bladder gas; and that the danger of the bladder wall rupturing might restrict the extent of rapid movements made by the perch. Experiments on the restriction that the swimbladder imposes to the rapid and slow vertical movements of the perch will be described in a following paper.

Optical Atmospheric Air-Speed Sensor for EDL Operations

2020 ◽  
Author(s):  
Elie R. Salameh ◽  
Jaime Da Silva ◽  
M. Volkan Otugen ◽  
Dominique Fourguette
Keyword(s):  
Atmospheric Air ◽  
Speed Sensor ◽  
Air Speed

scholarly journals Horizontal-vertical movement relationships: Adélie penguins forage continuously throughout provisioning trips

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Javed Riaz ◽  
Sophie Bestley ◽  
Simon Wotherspoon ◽  
Louise Emmerson
Keyword(s):  
Environmental Conditions ◽  
Optimal Foraging ◽  
Three Dimensional ◽  
Spatial Location ◽  
Vertical Movement ◽  
Foraging Activity ◽  
Directed Movement ◽  
Vertical Movements ◽  
Movement Trajectories ◽  
Adélie Penguins

Abstract Background Diving marine predators forage in a three-dimensional environment, adjusting their horizontal and vertical movement behaviour in response to environmental conditions and the spatial distribution of prey. Expectations regarding horizontal-vertical movements are derived from optimal foraging theories, however, inconsistent empirical findings across a range of taxa suggests these behavioural assumptions are not universally applicable. Methods Here, we examined how changes in horizontal movement trajectories corresponded with diving behaviour and marine environmental conditions for a ubiquitous Southern Ocean predator, the Adélie penguin. Integrating extensive telemetry-based movement and environmental datasets for chick-rearing Adélie penguins at Béchervaise Island, we tested the relationships between horizontal move persistence (continuous scale indicating low [‘resident’] to high [‘directed’] movement autocorrelation), vertical dive effort and environmental variables. Results Penguins dived continuously over the course of their foraging trips and lower horizontal move persistence corresponded with less intense foraging activity, likely indicative of resting behaviour. This challenges the traditional interpretation of horizontal-vertical movement relationships based on optimal foraging models, which assumes increased residency within an area translates to increased foraging activity. Movement was also influenced by different environmental conditions during the two stages of chick-rearing: guard and crèche. These differences highlight the strong seasonality of foraging habitat for chick-rearing Adélie penguins at Béchervaise Island. Conclusions Our findings advance our understanding of the foraging behaviour for this marine predator and demonstrates the importance of integrating spatial location and behavioural data before inferring habitat use.

scholarly journals Surface Air Movement: An Important Contributor to Ventilation of Isolated Subsurface Structures?

2019 ◽  
Vol 4 (2) ◽  
pp. 23 ◽  
Author(s):  
Thomas Neil McManus ◽  
Assed Haddad
Keyword(s):  
Air Flow ◽  
Helmholtz Resonator ◽  
Worker Safety ◽  
Time Base ◽  
Near Surface ◽  
Helmholtz Resonators ◽  
Subsurface Structures ◽  
Air Movement ◽  
Air Speed ◽  
Almost All

This study reports on near-surface airspeed measured using a fast-responding thermoanemometer during an investigation of ventilation of an isolated subsurface structure induced by natural forces. Air speed changes continuously, rapidly, and unpredictably when assessed on the time base of one or two seconds. Zero, the most common air speed, occurred in almost all tests throughout the year but especially during cool and cold months. The most probable non-zero air speed, 10.7 m/min (35 ft/min), occurred in all tests. This air speed is below the level of detection by the senses. The number of zero values and the height of the peak at 10.7 m/min follow a repetitive annual cycle. Isolated subsurface structures containing manhole covers share the characteristics of Helmholtz resonators. Grazing air flow across the opening to the exterior induces rotational air flow in the airspace of a Helmholtz resonator. Rotational flow in the airspace potentially influences the exchange of the confined atmosphere with the external one. Ventilation of the airspace occurs continuously and without cost and is potentially enhanced by the unique characteristics of the Helmholtz resonator excited by surface air movement. These results have immense importance and immediate applicability to worker safety.

Effect of Cross-Flow Swirl on the Trajectory of Spray in an Annular Passage

2020 ◽  
Author(s):  
Tushar Sikroria ◽  
Abhijit Kushari
Keyword(s):  
Momentum Flux ◽  
High Speed ◽  
Air Flow ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Swirl Number ◽  
Flow Swirl ◽  
Air Stream ◽  
The Impact

Abstract This paper presents the experimental analysis of the impact of swirl number of cross-flowing air stream on liquid jet spray trajectory at a fixed air flow velocity of 42 m/s with the corresponding Mach number of 0.12. The experiments were conducted for 4 different swirl numbers (0, 0.2, 0.42 and 0.73) using swirl vanes at air inlet having angles of 0°, 15°, 30° and 45° respectively. Liquid to air momentum flux ratio (q) was varied from 5 to 25. High speed (@ 500 fps) images of the spray were captured and those images were processed using MATLAB to obtain the path of the spray at various momentum flux ratios. The results show interesting trends for the spray trajectory and the jet spread in swirling air flow. High swirling flows not only lead to spray with lower radial penetration due to sharp bending and disintegration of liquid jet, but also result in spray with high jet spread and spray area. Based on the results, correlations for the spray path have been proposed which incorporates the effects of the swirl number of the air flow.

Three Dimensional Simulation of Ventilation Flow Through a Solar Windcatcher

2019 ◽  
Author(s):  
Peter Abdo ◽  
Rahil Taghipour ◽  
B. P. Huynh
Keyword(s):  
Natural Ventilation ◽  
Air Flow ◽  
Ventilation System ◽  
Three Dimensional ◽  
Windward Side ◽  
Efficient Design ◽  
Indoor Space ◽  
Wind Speeds ◽  
Air Stream ◽  
Stack Ventilation

Abstract Natural ventilation is the process of supplying and removing air through an indoor space by natural means. There are two types of natural ventilation occurring in buildings: winddriven ventilation and buoyancy driven or stack ventilation. The most efficient design for natural ventilation in buildings should implement both types of natural ventilation. Stack ventilation which is temperature induced is driven by buoyancy making it less dependent on wind and its direction. Heat emitted causes a temperature difference between two adjoining volumes of air, the warmer air will have lower density and be more buoyant thus will rise above the cold air creating an upward air stream. Combining the wind driven and the buoyancy driven ventilation will be investigated in this study through the use of a windcatcher natural ventilation system. Stack driven air rises as it leaves the windcatcher and it is replaced with fresh air from outside as it enters through the positively pressured windward side. To achieve this, CFD (computational fluid dynamics) tool is used to simulate the air flow in a three dimensional room fitted with a windcatcher based on the winddriven ventilation alone, buoyancy driven ventilation alone, and combined buoyancy and winddriven ventilation. Different wind speeds between 0 up to 2.5 m/s are applied and the total air flow rate through the windcatcher is investigated with and without temperature of 350 K applied at the windcatcher’s outlet wall. As the wind speed increased the efficiency of the solar windcatcher decreased.

Optimization of Flow Passage Geometry for Air-Heating, Plate-Type Solar Collectors

1981 ◽  
Vol 103 (4) ◽  
pp. 323-330 ◽  
Author(s):  
K. G. T. Hollands ◽  
E. C. Shewen
Keyword(s):  
Air Flow ◽  
Solar Collectors ◽  
Absorber Plate ◽  
Flow Passage ◽  
Air Heating ◽  
Path Design ◽  
Air Stream ◽  
Back Plate ◽  
Collector Efficiency ◽  
Plate Type

The effect of the choice of shape and dimensions of the air flow passages in plate-type, air-heating solar collectors is assessed. Particularly examined is their effect on the overall heat transfer coefficient Upf between the air stream and the plate, which has an important effect on collector efficiency. It is emphasized in this study that in comparing various designs of flow passage, they should be compared for the same pressure drop Δp suffered by the air in passing through the collector, and for the same mass flow rate m per unit of collector area. On the basis of this type of comparison, two main conclusions are drawn. First, when the length of the air flow passage L is made less than about 1 m, Upf increases dramatically with decreasing values of L. Second, outside the transition regime, the value of Upf for a V-corrugated absorber plate is from 47 to 300 percent higher than that for a flat absorber plate, depending on whether the flow is laminar or turbulent, and on whether the V-corrugated plate is thermally bonded to the back plate. The first conclusion has led to a proposal for a novel air-heating solar collector design, called the “short-path” design.

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