Influence of current velocity, density, and detritus on drift of two mayfly species (Ephemeroptera)

1983 ◽  
Vol 61 (1) ◽  
pp. 119-125 ◽  
Author(s):  
Jan J. H. Ciborowski
Keyword(s):  
Water Column ◽  
Linear Function ◽  
Current Velocity ◽  
Substantial Proportion ◽  
Positive Linear Function ◽  
Laboratory Streams ◽  
Indirect Consequence ◽  
Baetis Tricaudatus ◽  
Mean Current

Drift responses of Baetis tricaudatus Dodds and Ephemerella inermis Eaton larvae to manipulations of benthic density, sterile detritus, and current velocity were monitored in laboratory streams. The proportion of larvae departing from the substrate was independent of benthic density, amount of detritus, and interactions between these two variables. In spring, departure of larvae of both species was a positive linear function of current velocity during daylight hours. In darkness, departure of B. tricaudatus larvae became a negative linear function of current velocity. Nocturnal drift of E. inermis larvae was minimal at a mean current velocity of 25 cm∙s−1 and greater at both higher and lower velocities. None of the factors tested influenced departure of B. tricaudatus larvae in autumn experiments. Dead larvae were eroded from the substrate in much smaller proportions than were their live counterparts. This suggests that appearance in the water column of live animals is the direct or indirect consequence of individuals' behaviour. Departure of animals during daytime is largely passive in nature, whereas a substantial proportion of nocturnal drift probably results from active desertion of the substrate.

Downstream and Lateral Transport of Nymphs of Two Mayfly Species (Ephemeroptera)

1983 ◽  
Vol 40 (11) ◽  
pp. 2025-2029 ◽  
Author(s):  
Jan J. H. Ciborowski
Keyword(s):  
Water Column ◽  
Velocity Gradient ◽  
Current Velocity ◽  
Lateral Transport ◽  
Cross River ◽  
Baetis Tricaudatus ◽  
Settling Behavior ◽  
Mean Current ◽  
Lateral Dispersal

By releasing live and dead nymphs of two mayfly species, Baetis tricaudatus Dodds and Ephemerella inermis Eaton, into the water column of a river and catching them downstream in a series of contiguous nets, I estimated settling and lateral dispersal rates. Live animals settled over shorter distances than dead individuals, and became more widely laterally dispersed for any given distance downstream and mean current velocity. Transport of suspended organisms in a river in which mean current velocity increases with increasing distance from shore may produce a skewed cross-river benthic distribution of animals. The degree of skewness will depend on the current velocity gradient and on suspended animals' settling behavior.

Mean current velocity measurement from a movable base

1994 ◽  
Vol 5 (5) ◽  
pp. 395-399
Author(s):  
N. P. Bulgakov ◽  
V. I. Remchukov ◽  
A. G. Evgushchenko
Keyword(s):  
Current Velocity ◽  
Velocity Measurement ◽  
Mean Current

scholarly journals Snare Performance for Sunken and Submerged Oil Detection and Monitoring

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
M.P. VERFAILLIE ◽  
M.D. GLOEKLER ◽  
N.E. KINNER ◽  
E.A. BALCOM ◽  
C.A. BERNARDY ◽  
...  
Keyword(s):  
Water Column ◽  
Oil Spill ◽  
Current Velocity ◽  
Developed Countries ◽  
Fuel Oil ◽  
Detection Techniques ◽  
Drag Forces ◽  
Plastic Bags ◽  
A Chain ◽  
Sunken Oil

ABSTRACT - 687127 Most oil spill response strategies, tactics, and equipment are designed to address floating oil. Previous research and historic events have shown that spilled oil can suspend (i.e., submerged oil) or sink (i.e., sunken oil) as a function of the oil's density relative to that of the receiving waters. Processes such as wave action or current velocity, sediment entrainment, and oil weathering (e.g., evaporation) may change the buoyancy of floating oils causing them to submerge or sink. Non-floating oil is more difficult and expensive to detect and poses significant challenges for containment and cleanup. Many existing detection techniques for non-floating oils rely on oleophilic sorbents, such as snare, which are weighted depending upon the oil's location in the water column and then towed behind a vessel in designated transects. Currently, there is no quantitative method to relate the amount of oil collected by snare to the amount of oil encountered during towing. In addition, the dynamics and interactions of towed snare and oil remain largely unknown. To address these knowledge gaps, various components of snare performance have been evaluated since 2016 by the Coastal Response Research Center (CRRC) at the University of New Hampshire (UNH). The research has evaluated: (1) the impacts of temperature, salinity, oil type, and tow velocity on adsorption and desorption of oil to snare, (2) snare dynamics and position in the water column as a function of tow velocity, (3) the impacts of material type and potential alternatives to snare (e.g., mosquito and fishing nets, plastic debris) for lesser developed countries (LDCs), and (4) the interaction of snare with sunken and submerged oil. The results determined: (1) adsorption of oil to snare was best for less viscous oils (No. 6 Fuel Oil) and lower water temperatures (5°C) and desorption was greatest at low temperatures (6°C) and low current velocities (< 1 knot), while salinity had no significant effect. (2) Tow depth for snare arrays decreased with increased velocity unless a vane was used. (3) Optimal spacing of snare on a chain is a function of tow and current velocity, and drag forces on the tow chain. (4) Snare alternatives with greatest potential for sunken oil detection in LDCs were nylon mosquito netting and plastic bags. The findings from this research improves understanding of the behavior of snare and how it interacts with sunken and submerged oil and can improve towing techniques used by oil spill responders, leading to more effective detection.

scholarly journals Comparative Investigations of Porous Cigarette Papers and Perforated Papers / Zum Problem vergleichender Untersuchungen an porösen und perforierten Cigarettenpapieren

1966 ◽  
Vol 3 (7) ◽  
Author(s):  
G. Lipp
Keyword(s):  
Water Column ◽  
Linear Function ◽  
Pressure Difference ◽  
Air Permeability ◽  
Mainstream Smoke ◽  
Air Stream ◽  
Non Linear

AbstractThere is a proportional dependence between pressure difference and air stream of porous cigarette papers. In the case of perforated papers, however, the said relationship conforms to a non-linear function. It is therefore important to measure the permeability to air of these papers under a pressure difference that corresponds to the actual pressure conditions in cigarettes, i.e. approximately 0.25 dm water column gauge. With identical air permeability and identical degree of ventilation the yields of condensate, nicotine and phenols in the mainstream smoke of cigarettes made with porous paper decrease to a larger extent than the yields of the mentioned substances in the mainstream smoke of cigarettes made with perforated paper.

scholarly journals Variations in Flowering, Vegetative Growth, and Dry Matter Partitioning Induced by Photoperiod and Temperature Treatments in Papaver somniferum

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 887F-888
Author(s):  
Mary C. Acock ◽  
Zhongchun Wang ◽  
Basil Acock
Keyword(s):  
Flowering Time ◽  
Linear Function ◽  
Vegetative Growth ◽  
Dry Matter ◽  
Simulation Models ◽  
Papaver Somniferum ◽  
Shoot Biomass ◽  
Dry Matter Partitioning ◽  
Days To Flowering ◽  
Positive Linear Function

Estimating yields of illicit narcotic crops requires knowledge of how climate, soil, and geography affect these crops. One method for estimating yields is to create databases from which to develop simulation models. This experiment is part of one of those databases, designed to determine if flowering time can be affected in young poppy seedlings by manipulating photoperiod (PP) and temperature. Plants were grown in chambers under a 12-, 13-, 14-, or 24-h PP and a 12-h thermoperiod of 25/20C. Plants at 10 or 20 days after emergence were transferred to separate chambers and treated for 48 h with either a) 10C and a 12-h PP or b) a 24-h PP and a 12-h thermoperiod of 25/20C. Days to flowering (DTF) decreased with increased PP, especially between 12 and 13 h. The 48-h PP interruption decreased DTF for PPs <24 h for both seedling ages, the effect being more pronounced for 10 d and for the 12-h PP. The 48-h 10C interruption had no effect on DTF. The poppy capsule, from which the gum is harvested, was a larger proportion of the shoot biomass under PPs >14 h, but capsule biomass was a positive linear function of DTF. DTF depends on PP and biomass at flowering depends on DTF.

MOVEMENT AND EROSION OF ALBERTA BITUMEN ALONG THE BOTTTOM AS A FUNCTION OF TEMPERATURE, WATER VELOCITY AND SALINITY

2017 ◽  
Vol 2017 (1) ◽  
pp. 2306-2326
Author(s):  
M.D. GLOEKLER ◽  
T.P. BALLESTERO ◽  
E.V. DAVE ◽  
I.P. GAUDREAU ◽  
C.B.R. WATKINS ◽  
...  
Keyword(s):  
Shear Stress ◽  
Water Column ◽  
Current Velocity ◽  
Critical Shear Stress ◽  
Heavy Oils ◽  
Annular Flume ◽  
Length Width ◽  
Higher Temperature ◽  
Trajectory Models ◽  
Temperature Water

Abstract While many trajectory models exist to predict the movement of oil floating in or on water, few are designed to address heavy oil on the bottom of water bodies. In addition, remobilization (erosion) of the material into the water column is also difficult to predict. While properties such as adhesion, viscosity and density of oil may be readily measured, the critical shear stress (CSS) and the effect of (current) velocity, salinity, and temperature are virtually unknown for most heavy oils. The Coastal Response Research Center (CRRC) has a 4,000 L annular flume, with a water depth of 0.43 m. An inner rectangular flume (1.2 m length, 0.2m width, 0.9 m height), placed inside the annular flume, was preceded by two flow straighteners to reduced turbulence and produce a uniform, one dimensional flow field. The current is generated by an electric thrust motor and measured in 3D by a Nortek AS (Norway) Vectrino II Profiling Velocimeter. A 20g circle of Alberta bitumen (API ~ 10°) was placed on a laminated grid (1cm2 square pattern) at the bottom of the straight flume. A total of 2.3m3 of water was then gradually added to the flume. The electric motor was started and the profiler began collecting data. Two cameras, placed along the side and above the oil, collected video of the erosions and length/width changes of the oil. Conditions were held steady for one hour once the desired current velocity was achieved. Temperatures, current velocity (X, Y, Z), and digital videographic data were collected during each run. Erosions and percent lengthening of the oil was monitored as a function of water temperature, salinity and velocity. The turbulent kinetic energy (TKE) method was used to calculate the bed shear stress (BSS). In addition to the expected impact of higher temperature on the movement along the bed and erosion into the water column, the viscoelastic and shear-thinning properties of the bitumen played a role in its behavior (lowering of viscosity at higher BSS slowing erosions and movement) and must be considered when predicting its behavior during a spill.

Stimulus-Response Compatibility in a Small Sample of Cerebral Palsied Adults

1994 ◽  
Vol 79 (3_suppl) ◽  
pp. 1459-1474 ◽  
Author(s):  
Miriam Legare ◽  
Camilla Wolak ◽  
Beverly Doyle
Keyword(s):  
Reaction Time ◽  
Linear Function ◽  
Compatibility Condition ◽  
Movement Time ◽  
Response Compatibility ◽  
Stimulus Response ◽  
Positive Linear Function ◽  
Aimed Movement ◽  
Index Of Difficulty ◽  
Stimulus Response Compatibility

Stimulus-response compatibility refers to the correspondence between a sensory event and the motor response which it specifies. A discrete aimed movement task with two conditions of stimulus-response compatibility tested whether higher compatibility would decrease the reaction time of 5 subjects with normal movement and 6 subjects with cerebral palsy. A board with 3 distances (13.5, 28.0, 40.5 cm) along each of 3 rays (45°, 90°, 135°) provided 9 target sites for a detachable leaf switch. A light on the switch was turned off or on for the low or high compatibility condition. The independent variables were the Index of Difficulty, target position and compatibility. The dependent variables were reaction time and movement time. The reaction times for both groups were less during the high compatibility condition than during the low compatibility condition as shown by a t test for differences between means. Multiple regression analyses showed that reaction time of the normal group was a positive linear function of compatibility and movement time was a positive linear function of the Index of Difficulty for both groups and of position for the normal group, 3 normal subjects and 2 cerebral palsied subjects. There were indications of ballistic rather than aimed movements. The results are discussed with regard to the role of visual fixation in aimed movement, the similarities between groups in conformance to Fitts' Law and differences between groups in reaction and movement times.

Optimum Swimming Speeds in Fish: The Problem of Currents

1980 ◽  
Vol 37 (7) ◽  
pp. 1086-1092 ◽  
Author(s):  
Clifford L. Trump ◽  
William C. Leggett
Keyword(s):  
Energy Expenditure ◽  
Swimming Speed ◽  
Current Velocity ◽  
Migration Behavior ◽  
Fish Swimming ◽  
Retrograde Motion ◽  
The Mean ◽  
The Relationship ◽  
Mean Current ◽  
A Current

A model is presented describing the energetic consequences of various behavioral responses to currents. To minimize the energy cost of migration, when confronted with currents, fish must optimize both the mean swimming speed and the degree to which swimming speed is altered in response to changes in current velocity. The optimum swimming speed in a current is U0 + 1/b where U0 = mean current speed and b is a constant in the equation E(t) = a ebW(t) describing the relationship between specific energy expenditure per unit time E(t) and swimming speed W(t). In a variable current, such as might occur in estuaries and coastal areas, energy expenditure is minimized when these variations are ignored and a constant speed through the water is maintained. This is true even in conditions where occasional retrograde motion over the bottom may occur. The added energy costs of swimming at mean speeds ≠ U0 + 1/b or of varying swimming speeds in response to changes in current velocity are rigorously defined. Predictions of the model are in general agreement with empirical data on fish swimming behavior.Key words: swimming speeds, currents, fish, theoretical ecology, mathematical models, energetics, migration, behavior

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