Showing papers on "Water flow published in 1986"
TL;DR: A review of the current conceptual understanding of the basic processes of water flow and chemical transport in the untsaturated (vadose) zone and of various deterministic mathematical models that are being used to describe these processes can be found in this article.
Abstract: This paper gives a review of our current conceptual understanding of the basic processes of water flow and chemical transport in the untsaturated (vadose) zone and of various deterministic mathematical models that are being used to describe these processes. During the past few decades, tremendous effort has been directed toward unravelling the complexities of various interactive physical, chemical, and microbiological mechanisms affecting unsaturated flow and transport, with contributions being made by soil scientists, geochemists, hydrologists, soil microbiologists, and others. Unfortunately, segmented, disciplinary research has contributed to a lack of experimental and theoretical understanding of the vadose zone, which, in turn, has precluded the accurate prediction and management of flow and contaminant transport through it. Thus a more unified and interdisciplinary approach is needed that considers the most pertinent physical, chemical, and biological processes operative in the unsaturated zone. Challenges for both fundamental and applied researchers to reveal the intricacies of the zone and to integrate these with currently known concepts are numerous, as is the urgency for progress inasmuch as our soil and ground water resources are increasingly subjected to the dangers of long-term pollution. Specific research areas in need of future investigation are outlined.
526 citations
TL;DR: The author discusses the growth Equations, stress Relaxation, and the Yield Threshold among other topics.
Abstract: INTRODUCTION ... ..... . 377 THE PHYSICS OF IRREVERSIBLE CELL ENLARGEMENT 378 Growth Equations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379 GROWTH OF MULTICELLULAR TISSUES . . . . . . . . . . . . . . . . . . . . . . .. . .... . . . . . . . . . . . . 381 Variation in Growth Properties . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 381 Geometry of Water Flow . . . . . . . . . . . . . . . . . . . . . . . .. . . . 382 DOES WATER TRANSPORT LIMIT GROWTH? 385 Water Potentials of Growing Tissues . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385 Driving Forces for Water Uptake . . . ..... . . . . . . . . . . . . . . . . . . . . . . . . 388 Propagation of Water across Tissues. . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 389 YIELDING OF CELL WALLS 393 Stress Relaxation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....... 393 Turgor Pressure and Wall yielding . . . . . . . . . . . . . . . . . . . . . . . ..... 396 The Yield Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 398 SUMMARy 400
369 citations
TL;DR: In this paper, a fluorometric method for measuring H/sub 2/O/Sub 2/ vapor in air utilizes peroxidase enzyme to catalyze the reaction in which hydroperoxides cause dimerization of (p-hydroxyphenyl)acetic acid.
Abstract: A fluorometric method for measuring H/sub 2/O/sub 2/ vapor in air utilizes peroxidase enzyme to catalyze the reaction in which hydroperoxides cause dimerization of (p-hydroxyphenyl)acetic acid. In a second channel, H/sub 2/O/sub 2/ is selectively decomposed by catalase so that the fluorescence signal is due only to organic hydroperoxides. The difference between the two signals is a measure of H/sub 2/O/sub 2/ vapor. The H/sub 2/O/sub 2/ vapor is collected by means of a glass coil though which air and water flow concurrently. The coefficient of variation is 0.5% at 2.5 parts per billion by volume. The standard deviation of the base line is 10 parts per trillion by volume (pptv) under laboratory conditions. This standard deviation has varied between 3 and 33 pptv during ground-based field missions, and was 70 pptv on aircraft flights. Thirty seconds is required for the signal to change from 10 to 90% of its maximum value. 13 references, 4 figures, 1 table.
294 citations
TL;DR: This chapter focuses on the role of the soil structure (the soil–pore system) through which both water and roots move, and evidence that loosening of zones of high strength improves crop–water relations.
Abstract: Publisher Summary This chapter focuses on the role of the soil structure (the soil–pore system) through which both water and roots move. The principle reason for concentrating on soil structure is that, of the soil's intrinsic physical properties, it is the one most easily, frequently, and widely altered, particularly by cultivation. The transmission porosity is responsible for rapid water movement and provides pre-existing channels for root growth. Disruption or lack of, transmission pores is common in cultivated soil. This leads to impeded water flow and root growth within the profile. Structural instability is frequently encountered at the surface of tilled soils. It gives rise to crusting and translocation of clay into the subsoil. Crusting can reduce the infiltration rate by up to two orders of magnitude. Organic matter accumulation at the soil surface, by conservation tillage practices, provides the most cost-effective remedy. Crop roots have been studied less than crop canopies, but it appears that considerable inter-and intra-specific variation exists in such properties as maximum rooting depth, lateral branch production, xylem vessel diameter, and root hair length. Mechanical impedance and transient waterlogging are structurally related causes of restriction to root development in arable soils. There is evidence that loosening of zones of high strength improves crop–water relations.
275 citations
TL;DR: The transfer function model (TFM) of solute transport through unsaturated soil initiated by W. A. Jury (1982) is generalized to describe the movement of a solute that may undergo physical, chemical, or biological transformations as it moves in a soil unit through which the water flow may vary in both space and time as mentioned in this paper.
Abstract: The transfer function model (TFM) of solute transport through unsaturated soil initiated by W. A. Jury (1982) is generalized to describe the movement of a solute that may undergo physical, chemical, or biological transformations as it moves in a soil unit through which the water flow may vary in both space and time. The generalized TFM is shown to be related to the law of mass balance for a solute as interpreted in the context of probability theory. The principal conceptual entity in the TFM is the solute lifetime probability density function. Methodologies for determining this function experimentally are outlined and its relation to the solute travel time density function defined by Jury is shown. Since the generalized TFM is formulated independently of any particular mechanism of solute transport through soil, it is concluded that mechanistic models of solute movement consistent with the law of mass balance are also consistent with the TFM.
238 citations
TL;DR: In this paper, a three-dimensional finite element model for simulating water flow in variably saturated porous media is presented, which is general and capable of accommodating complex boundary conditions associated with seepage faces and infiltration or evaporation.
Abstract: A three-dimensional finite-element model for simulating water flow in variably saturated porous media is presented. The model formulation is general and capable of accommodating complex boundary conditions associated with seepage faces and infiltration or evaporation on the soil surface. Included in this formulation is an improved Picard algorithm designed to cope with severely nonlinear soil moisture relations. The algorithm is formulated for both rectangular and triangular prism elements. The element matrices are evaluated using an “influence coefficient” technique that avoids costly numerical integration. Spatial discretization of a three-dimensional region is performed using a vertical slicing approach designed to accommodate complex geometry with irregular boundaries, layering, and/or lateral discontinuities. Matrix solution is achieved using a slice successive overrelaxation scheme that permits a fairly large number of nodal unknowns (on the order of several thousand) to be handled efficiently on small minicomputers. Six examples are presented to verify and demonstrate the utility of the proposed finite-element model. The first four examples concern one- and two-dimensional flow problems used as sample problems to benchmark the code. The remaining examples concern three-dimensional problems. These problems are used to illustrate the performance of the proposed algorithm in three-dimensional situations involving seepage faces and anisotropic soil media.
177 citations
TL;DR: In this paper, the effects of the soil air flow on the process of water infiltration in a 93.5 cm deep vertical column for varied boundary conditions at the surface - positive time constant head; time constant fluxes smaller and greater than saturated soil hydraulic conductivity.
Abstract: The purpose of this study is to analyze the effects of the soil air flow on the process of water infiltration in a 93.5 cm deep vertical column for varied boundary conditions at the surface - positive time constant head; time constant fluxes smaller and greater than saturated soil hydraulic conductivity. Several experiments conducted on a sandy soil column with and without a possible air flow through the wall are presented. Continuous and simultaneous measurements of water content and air and water pressure heads at different depths allow the analysis of the air and water movements within the soil and the determination of the capillary pressure and relative permeability for each phase as functions of the volumetric water content. A numerical solution of the equations describing the simultaneous flow of air and water is compared with the experimental data and with the traditional one-phase flow modeling. The results show that the air movement may significantly affect water flow variables such as infiltration rates, water content profiles, and ponding times. Furthermore, some basic assumptions used in two-phase flow modeling, such as the hydrodynamic stability of the wetting fronts and the pertinence of the relative permeability concept, are discussed in the light of the experimental data.
173 citations
TL;DR: Observations suggest that in intestinal membranes water moves through the lipid matrix but that in renal plasma membranes water channels may be involved, which allows for an entirely transcellular route for water flow during volume reabsorption.
Abstract: The osmotic water permeabilityPf of brush border (BBM) and basolateral (BLM) membrane vesicles from rat small intestine and renal cortex was studied by means of stopped-flow spectrophotometry. Scattered light intensity was used to follow vesicular volume changes upon osmotic perturbation with hypertonic mannitol solutions. A theoretical analysis of the relationship of scattered light intensity and vesicular volume justified a simple exponential approximation of the change in scattered light intensity. The rate constants extracted from fits to an exponential function were proportional to the final medium osmolarity as predicted by theory. For intestinal membranes, computer analysis of optical responses fitted well with a single-exponential treatment. For renal membranes a double-exponential treatment was needed, implying two distinct vesicle populations.Pf values for BBM and BLM preparations of small intestine were equal and amount to 60 μm/sec. For renal preparations,Pf values amount to 600 μm/sec for the fast component, BBM as well as BLM, and to 50 (BBM) and 99 (BLM) μm/sec for the slow component. The apparent activation energy for water permeation in intestinal membranes was 13.3±0.6 and in renal membranes, 1.0±0.3 kCal/mole, between 25 and 35°C. The mercurial sulfhydryl reagentpCMBS inhibited completely and reversibly the highPf value in renal brush border preparations. These observations suggest that in intestinal membranes water moves through the lipid matrix but that in renal plasma membranes water channels may be involved. From the highPf values of renal membrane vesicles a transcellular water permeability for proximal tubules can be calculated which amounts to ∼1 cm/sec. This value allows for an entirely transcellular route for water flow during volume reabsorption.
164 citations
TL;DR: In this article, a model for simulating the flow and bed topography in a meandering alluvial channel is developed, where the main controlling parameters are the channel's width-depth ratio, radius-width ratio, resistance characteristics (or gradient), and sediment Froude number.
Abstract: A model for simulating the flow and bed topography in a meandering alluvial channel is developed. The basis is a solution to the equations for conservation of mass and momentum and for lateral stability of the streambed. The bed‐stability equation is a transverse force balance for bed‐sediment particles relating the transverse bed slope to primary flow variables. The main controlling parameters are the channel's width‐depth ratio, radius‐width ratio, resistance characteristics (or gradient), and sediment Froude number. An innovative feature is the use of a simple mass‐flux balance (mass conservation) to link the equation for bed stability to the momentum equations. The mass‐flux balance relates the net lateral transport of flow volume to the streamwise variation of transverse bed slope. Thereby, the equations governing the secondary‐current velocity and the transverse bed slope become those of a damped oscillating system subjected to a driving force, the change in channel curvature. The model is tested wi...
159 citations
TL;DR: The biomechanical basis of morphological acclimation to wave force was studied in intertidal demosponges, suggesting that the habitat—dependent changes observed in H. panicea are engineering solutions to environmental stresses.
Abstract: The biomechanical basis of morphological acclimation to wave force was studied in intertidal demosponges. Colonies of Halichondria panicea were found to be stronger and stiffer in high wave force habitats than in low wave force habitats. These biomechanical changes are due to increase spicule number and size in sponges from areas of high wave action. The spicule changes follow the predictions of theories developed for particulate composite materials (e.g., those comprised of a flexible matrix with ridge imbedded stiffeners), suggesting that the habitat—dependent changes observed in H. panicea are engineering solutions to environmental stresses. An additional constraint imposed upon the basic Porifera body plan is the necessity of pumping water through the skeleton for feeding and respiration. In H. panicea, piping elements decrease in diameter in high wave force environments. This increases the resistance of oscular systems to water flow, thereby increasing the costs of water pumping. Environments with ex...
134 citations
TL;DR: In this paper, a column of 100 cm length and 15.4 cm diameter was filled with sand and tritium tracer was added to the infiltrating water for some period.
01 Jan 1986
TL;DR: In this article, the distribution and flow of Mediterranean waters in the western Alboran Sea were studied using hydrographic and current meter data, obtained during June to October 1982, and numerical model experiments were used to study the distribution of Mediterranean water in the Mediterranean waters, and a rough estimate of the mean westward Intermediate Water transport was 0.4 × 106 m3 s−1, about one-third of the total outflow, so that the best estimates of the contributions of traditionally defined Intermediate Water and Deep Water account for only about one half of the overall outflow
Abstract: Hydrographic and current meter data, obtained during June to October 1982, and numerical model experiments are used to study the distribution and flow of Mediterranean waters in the western Alboran Sea. The Intermediate Water is more pronounced in the northern three-fourths of the sea, but its distribution is patchy as manifested by variability of the temperature and salinity maxima at scales ≤10 km. Current meters in the lower Intermediate Water showed mean flow toward the Strait at 2 cm s−1. A reversal of this flow lasted about 2 weeks. A rough estimate of the mean westward Intermediate Water transport was 0.4 × 106 m3 s–1, about one-third of the total outflow, so that the best estimates of the contributions of traditionally defined Intermediate Water and Deep Water account for only about one-half of the total outflow. The Deep Water was uplifted against the southern continental slope from Alboran Island (3°W) to the Strait. There was also a similar but much weaker banking against the Spanish slope, but a deep current record showed that the eastward recirculation implied by this banking is probably intermittent. Two-layer numerical model experiments simulated the Intermediate Water flow with a flat bottom and the Deep Water with realistic bottom topography. Both experiments replicated the major circulation features, and the Intermediate Water flow was concentrated in the north because of rotation and the Deep Water flow in the south because of topographic control.
TL;DR: The present model improved by incorporating the actual lumen transectional shape and the tapering that occurs at the ends of its tracheids allowed reasonable predictions of the hydraulic conductance per unit length over a wide size range of stipes for this fern.
Abstract: Calkin, H. W., Gibson, A. C. and Nobel, P. S. 1986. Biophysical model of xylem conductance in tracheids of the fern Pteris vittata.—J. exp. Bot. 37: 1054-1064. Water movement in the xylem is often analysed with the Hagen-Poiseuille equation, which applies to capillaries of specific diameters. However, the predicted hydraulic conductances per unit length (Kh) are generally much higher than measured values and important anatomical details, such as the pits of tracheids, are ignored. Here, a previous model based on the Hagen-Poiseuille analysis for water flow in the stipes of Pteris vittata is improved by incorporating the actual lumen transectional shape (usually elliptical or ovate) and the tapering that occurs at the ends of its tracheids, as well as using a better method for analysing the electrical circuit analogues for the pits (pit cavities plus pit membranes). The measured Kb was similar to that predicted by the Hagen-Poiseuille equation for narrow stipes with their small tracheids, but was only about half the measured Kh for large stipes. Correcting for the actual shape changed Kb 2- to 3-fold for tracheids with elliptic and ovate transections. For the smaller diameter tracheids, most of the flow resistance was from the lumens but for the larger tracheids most was from the pit membranes. For all stipes the pit cavities accounted for 12-22% of the total resistance. When the pit membranes were partially digested away with cellulase, Kh increased about 66%, consistent with the deduced resistance of this part of the pathway. The present model incorporating realistic anatomical details allowed reasonable predictions of the hydraulic conductance per unit length over a wide size range of stipes for this fern.
TL;DR: In this article, the authors present a method for solving a coupled set of wave equations for general low-frequency, large-scale wind stress forcing as input, and examine convergence properties of the solution analytically.
Abstract: Friction, the alongshore pressure gradient and time-dependent effects are all of lowest-order importance in the dynamics of wind-driven fluctuating currents and sea levels on continental shelves. Previous work has shown that when all these effects are included, the ocean response can be described by an infinite sum of coastal- trapped waves whose amplitudes satisfy a fully coupled infinite set of forced, first-order wave equations. We present a practical method for solving this coupled set of equations for general low-frequency, large-scale wind stress forcing as input. Convergence properties of the solution are examined analytically. For the same accuracy, more modes are required to describe alongshore currents than sea level and fewer modes are required to describe barotropic than depth-dependent motion. As an example, numerical calculations were carried out for a model of the West Florida Shelf. The sea level field was effectively described by one mode but the alongshore velocity field was not...
TL;DR: In this article, the authors developed a two-component convection-dispersion equation (CDE) model as a special case of the transfer function model (TFM) of solute transport.
Abstract: The two-component convection-dispersion equation (CDE) model is developed as a special case of the transfer function model (TFM) of solute transport. It is shown that the two-component CDE model can be reformulated as an integral equation for the “fast” solute component which has the same form and interpretation as the TFM integral equation specialized to (1) steady water flow conditions and (2) solute input or loss restricted to the entrance or exit surface of a soil unit. The travel time probability density function (pdf) for a solute according to the two-component CDE model then is calculated analytically as a Laplace transform. Numerical inversion of the transformed pdf is carried out for several different sets of values of the four adjustable parameters in the CDE model. The effects of convection, dispersion, and linear sorption processes, as well as the influence of the “slow” solute component, are illustrated by the numerically simulated travel time pdf. It is suggested that the fractional transport volume is the most significant physical parameter in the model in terms of impact on the shape of the travel time pdf.
Patent•
07 Mar 1986
TL;DR: In this article, a modular water faucet, which includes a base operatively connected to a spout, is described, and the base and spout each have a cubical design and include thereon means for mounting decorative panels of various design and/or color.
Abstract: A modular water faucet, which includes a base operatively connected to a spout. The base and spout each have a cubical design and include thereon means for mounting decorative panels of various design and/or color. The modules making up the base can be stacked to any desired height, and the spouts are interchangeable with the base. The water faucet includes an automatic control system for dispensing water upon the sensing of a human body or other object near an outlet of the spout. The control system uses infrared light to detect the presence of an object. Means for differentiating the reflected light from ambient light are included. Water temperature is also sensed and compared to a preselected temperature. Water is prevented from flowing if the temperature is in excess of the preselected temperature and warnings are given in an automatic mode. Water flow will proceed if a manual mode is initiated. The control system also detects the position of the spout relative to the base. If the spout is turned through a preset angle to the side, then water flow is forced off for maintenance. A mixing valve is operated by a slide passing through the base to preset the temperature of the water supplied. A manual override is provided in the automatic water faucet in the event of a power outage.
TL;DR: Detailed water flow around larvae of Simulium vittatum Zett (sibling IS-7) was investigated using flow tanks, aluminium flakes, pigment, still photography, cinematography, and video recordings to demonstrate the basic hydrodynamic phenomenon of downstream paired vortices.
Abstract: Detailed water flow around larvae of Simulium vittatum Zett. (sibling IS-7) was investigated using flow tanks, aluminium flakes, pigment, still photography, cinematography, and video recordings. Angle of deflection of a larva from the vertical has a hyperbolic relationship to water velocity. Velocity profiles around larvae show that the body is in the boundary layer. Frontal area of the body decreases as velocity increases. Disturbed larvae exhibit "avoidance reaction" and pull the body into the lower boundary layer. Longitudinal twisting and yawing of the larval body places one labral fan closer to the substrate, the other near the top of the boundary layer. Models and live larvae were used to demonstrate the basic hydrodynamic phenomenon of downstream paired vortices. Body shape and feeding stance result in one of the vortices remaining in the lower boundary layer. The other rises up the downstream side of the body, passes through the lower fan, then forms a von Karman trail of detaching vortices. This ...
TL;DR: The steady-state leaching theory and related concepts regarding soil salinity control were evaluated in view of the transient-state theories presented and recent experimental results as mentioned in this paper, which indicated that irrigation water quality and quantity, rather than irrigation frequency, influenced dry matter production of grass.
Abstract: The steady-state leaching theory and related concepts regarding soil salinity control were evaluated in view of the transient-state theories presented and recent experimental results. Data from small plot experiments to establish the leaching requirement of nine crops and from a rhizotron study on the influence of irrigation frequency on soil salinity control agreed with theoretical, transient-state predictions that consider water flow, salt transport, and water uptake by crop roots, simultaneously. Root water uptake was assumed to depend on matric (water content) and osmotic (soil salinity) potentials, and on a critical root-water potential of about −0.3 MPa. The assumption that the major effect of soil salinity is a reduction in plant water uptake was substantiated. Results show water balance components (for nine crops irrigated several times each day and for grass irrigated with various combinations of quantity, quality, and frequency) deviated significantly from predictions based on the steady-state leaching fraction equation. The deviation was attributed to an increase in soil-water content and transpiration as irrigation applications increased; or conversely, an increase in soil-water content as transpiration decreased because of increased soil salinity. The practical limitations of salinity control in irrigated agriculture based on the steady-state leaching equation were evident even for high frequency irrigation where steady-state conditions should be approached. Measured commercial yields and aboveground dry matter production compared well with yields computed on the assumption that relative crop yield is equivalent to relative transpiration. Both measured and computed results indicated that irrigation water quality and quantity, rather than irrigation frequency, influenced dry matter production of grass.
TL;DR: The number of mucous-net layers in the feeding filter of Oikopleura vanhoeffeni collected from March 1985 to February 1986 is determined, and the pathway of water flow through the filter is described to be the “food concentrating filter”.
Abstract: Although the feeding apparatus of oikopleurid Appendicularia has been described in general, functional details of the feeding mechanism and fluid mechanical constraints on the feeding process remain unknown. My goals were to determine the number of mucous-net layers in the feeding filter of Oikopleura vanhoeffeni collected from March 1985 to February 1986, and to describe the pathway of water flow through the filter. Marker particles (i.e. Isochrysis galbana, carmine, charcoal powder, and starch), and rhodamine dye were added to the natural food suspension to help in visualizing structure and flow. The feeding filter was composed of three layers. Water flowed into the filter through two large, lateral openings at the base of each wing, and along the open distal margins of the filter. Under hydrostatic pressure generated by the tail, water moved through the filter in a one-way bulk flow and was forced through the mucous mesh of both the dorsal and ventral layers. Thus, the feeding filter concentrated the food suspension by sieving most of the incoming water. The filter did not collect or trap food particles. Because of its function, I propose calling the feeding filter the “food concentrating filter”.
01 Jan 1986
Patent•
01 Jul 1986
TL;DR: A valve member for a water interruption pool cleaner installable within the operating head between an open mouth and the flexible hose connection as discussed by the authors is a tubular body of flexible material, which assumes a substantially collapsed condition over a segment thereof in absence of a pressure differential across the wall.
Abstract: A valve member for a water interruption pool cleaner installable within the operating head between an open mouth and the flexible hose connection. The valve is a tubular body of flexible material. The body assumes a substantially collapsed condition over a segment thereof in absence of a pressure differential across the wall. Along the collapsed segment, the body has diverging interior walls in the direction of water flow. Longitudinal ribbing on each side of the body may be provided for reinforcement.
TL;DR: It is demonstrated that the fluidity of rat colonic brush-border membranes can influence Na+-H+ exchange and osmotic water flow across these vesicles.
Patent•
13 Nov 1986
TL;DR: In this paper, a tankless electric water heater with instantaneous hot water output includes an open-ended folded tubular conduit having a separate metal-sheathed immersion heating element inserted in to each end of the conduit and carried by a cap member sealing the open end.
Abstract: A tankless electric water heater having instantaneous hot water output includes an open-ended folded tubular conduit having a separate metal-sheathed immersion heating element inserted in to each end of the conduit and carried by a cap member sealing the open end. Each cap member carries a thermostat having a preset temperature of about 140° F. and connected in series with the heating element carried by the respective cap member. A self-regulating PTC heating cable, either disposed in or wrapped around the tubular conduit, is continuously energized independently of the metal-sheathed heating elements to maintain the water in the tubular conduit a constant temperature of about 150° C. during standby periods. A water inlet conduit connected to one cap member is provides with a water flow responsive switch connected in series with the thermostastic for energizing the metal-sheathed heating elements upon demand for hot water flow and hot water is discharged through an outlet conduit connected to the other cap member.
01 Sep 1986
TL;DR: The Habitat Suitability Index (HSI) model as mentioned in this paper provides an objective quantifiable method of assessing the existing habitat conditions for chinook salmon within a study area by measuring how well each habitat variable meets the habitat requirements of the species by life stage.
Abstract: : This publication contains habitat models constructed and information compiled for two distinctly different purposes. The Habitat Suitability Index (HSI) model by Raleigh and Miller contains 17 habitat variables for chinook salmon by life stage. The HSI model provides an objective quantifiable method of assessing the existing habitat conditions for chinook salmon within a study area by measuring how well each habitat variable meets the habitat requirements of the species by life stage. The model thus provides an objective basis for predicting probable project impacts, documenting post project impacts, and guiding habitat protection, mitigation, enhancement, and management decisions. The section by Nelson contains habitat criteria curves for five flows-related variables for use in the Instream Flow Incremental Methodology (IFIM) (Bovee 1982; Milhouse et al. 1984). The IFIM model is intended to provide an objective method of assessing the effects of changes in water flow on habitat of chinook salmon by life stage. The HSI model is presented first followed by the IFIM section. Comments on model assumptions or performance, should be addressed to the appropriate author of each section. A brief overview of the HSI modeling procedures and IFIM curves follow.
TL;DR: In this article, a method based on the instantaneous value of the Reynolds stress was developed for detecting bursts in the wall region of the boundary layer of a turbulent boundary layer in a water channel.
Abstract: Flow visualization and Reynolds-stress measurement were combined in an investigation of a turbulent boundary layer in a water channel. Hydrogen bubbles were used to visualize the flow; a laser-Doppler anemometer capable of measuring two velocity components was applied to measure the instantaneous value of the Reynolds stress. Owing to the three-dimensional, time-dependent character of the flow it was rather difficult to identify flow structures from measured velocity signals, especially at larger distances from the wall. Despite this difficulty a method based on the instantaneous value of the Reynolds stress could be developed for detecting bursts in the wall region of the boundary layer. By this method the three-dimensional, time-dependent character of the flow is taken into account by attributing to the same burst ejections occurring successively with very short time intervals. This identification procedure is based on a comparison on a one-to-one basis between visualized flow structures and measured values of the Reynolds stress. The detected bursts were found to make a considerable contribution to the momentum transport in the boundary layer.
TL;DR: In this paper, the authors conducted experiments in a recirculating saltwater flume to determine if flow influences the vertical distribution of meiofauna within fine cohesive sediments and found that the number of nematodes and foraminiferans within the top 2 mm of sediment was significantly lower in the flow treatments than in the no flow treatments.
Abstract: Laboratory experiments were conducted in a recirculating saltwater flume to determine if flow influences the vertical distribution of meiofauna within fine cohesive sediments Replicate flume boxcores collected from a nonvegetated mudflat were exposed to either a no flow or a flow experimental treatment After 3 h in the flume, the boxcores were sampled by taking smaller sediment cores and sectioning these cores vertically in 2-mm intervals There was no statistical difference in the number of copepods (adults, copepodites, and nauplii) in the top 2mm of sediment in flow vs no flow treatments The number of nematodes and foraminiferans within the top 2 mm of sediment was significantly lower in the flow treatments than in the no flow treatments Downward migrations may decrease the susceptibility of these fauna to passive erosion by tidal currents
Patent•
26 Jun 1986
TL;DR: A rotary stream sprinkler unit comprises a body having a water flow passage in which is disposed a flow control unit having one or more arcuate passages configured to control the volume and pressure of a primary stream delivered to a rotary distributor head rotatably mounted at the outlet of the housing for dividing each primary stream into a plurality of final streams and rotating each of the final streams through a selected arc during the rotation of the rotary head.
Abstract: A rotary stream sprinkler unit comprises a body having a water flow passage in which is disposed a flow control unit having one or more arcuate passages configured to control the volume and pressure of a primary stream delivered to a rotary distributor head rotatably mounted at the outlet of the housing for dividing each primary stream into a plurality of final streams and rotating each of the final streams through a selected arc during the rotation of the rotary head.
TL;DR: It is concluded that apical membrane retrieval causes the phenomenon of flux inhibition, which increases the osmotic water permeability of toad urinary bladder and reduces the effectiveness of ADH-stimulated Posm.
Abstract: Antidiuretic hormone (ADH) increases the osmotic water permeability (Posm) of toad urinary bladder. This increase is believed to be produced by fusion of intracellular vesicles called aggrephores with the granular cell apical plasma membrane. Aggrephores contain intramembrane particle aggregates postulated to be water channels. ADH-stimulated Posm is decreased by osmotic gradient exposure, which is termed flux inhibition. We studied flux inhibition by exposing ADH-stimulated bladders to various osmotic gradients. Osmotic water flow was initially proportional to the applied osmotic gradient, but Posm decreased with time. Ultrastructural and quantitative studies of endocytosis demonstrate that apical membrane retrieval was a direct function of the transepithelial osmotic gradient. Posm remained unchanged when apical membrane retrieval was blocked by incubation of bladders at 2 degrees C, or under low water-flow conditions. These effects were reversed by increases in temperature or the applied osmotic gradient. We conclude that apical membrane retrieval causes the phenomenon of flux inhibition.
TL;DR: In this article, a quasi-three dimensional finite difference model which simulates coupled, fresh water and salt water flow, separated by a sharp interface, is used to investigate the effects of storage characteristics, transmissivity, boundary conditions and anisotropy on the transient responses of such flow systems.
TL;DR: In this article, the combined effects of soil-pore size and preferential flow on the hydraulic conductivity of forest soils were quantified using macroscopic analytical methods, based upon the capillary rise formula and the Hagen-Poiseuille equation.
Abstract: Macroscopic analytical methods, based upon the capillary rise formula and the Hagen-Poiseuille equation, were used to quantify the combined effects of soil-pore size and preferential flow on the hydraulic conductivity of forest soils. A density function was derived that relates effective pore diameters of heterogeneous soil-pore systems to measured hydraulic conductivity. Density functions derived for soils from sites with different topographic influences and disturbance effects characterized the effect of preferential flow on their hydraulic conductivity. It was shown that macroscopic methods can describe preferential flow without having to resort to microscopic examination of individual pores. If the required properties of the undisturbed parent soil (hydraulic conductivity and equivalent pore size) have been characterized, then these methods can predict the effect of disturbance on the hydraulic behavior of the soils.