Nutritional ecology of the invasive freshwater mysid Limnomysis benedeni: field data and laboratory experiments on food choice and juvenile growth

Hydrobiologia ◽  
2012 ◽  
Vol 705 (1) ◽  
pp. 75-86 ◽  
Author(s):  
Almut J. Hanselmann ◽  
Bettina Hodapp ◽  
Karl-Otto Rothhaupt
Keyword(s):  
Food Choice ◽  
Field Data ◽  
Laboratory Experiments ◽  
Nutritional Ecology ◽  
Juvenile Growth ◽  
Limnomysis Benedeni

scholarly journals Do Disadvantageous Social Contexts Influence Food Choice? Evidence From Three Laboratory Experiments

2020 ◽  
Vol 11 ◽  
Author(s):  
Qëndresa Rramani ◽  
Holger Gerhardt ◽  
Xenia Grote ◽  
Weihua Zhao ◽  
Johannes Schultz ◽  
...  
Keyword(s):  
Food Choice ◽  
Laboratory Experiments ◽  
Social Contexts

Estimation of Turbulence Coefficient Based on Field Observations

2000 ◽  
Vol 3 (02) ◽  
pp. 160-164 ◽  
Author(s):  
M.G. Kelkar
Keyword(s):  
Pressure Drop ◽  
Field Data ◽  
Laboratory Experiments ◽  
Gas Wells ◽  
Time Intervals ◽  
Transient Conditions ◽  
Forchheimer’S Equation ◽  
A Value ◽  
Transient Period ◽  
Fixed Period

Summary Isochronal testing is commonly used to evaluate the performance of gas wells. This paper proposes a new technique to estimate the value of the turbulence coefficient based on isochronal tests. The proposed method is easy to apply and evaluate. Further, the method also provides a value of bg under stabilized conditions which can be used to predict the performance of gas wells under stabilized conditions. The proposed method is validated using field data under a variety of operating conditions. The values of the turbulence coefficient based on the field data can differ significantly compared to the literature correlations. This further shows the importance of obtaining appropriate reservoir parameters based on the field rather than the laboratory data. Introduction The use of isochronal or modified isochronal testing is well established in the gas industry. These tests are common for gas wells which take a long time to reach a stabilized rate. A common example would be a low permeability, fractured reservoir. Instead of testing these wells until a stabilized rate is reached, the wells are tested for a fixed period of time and the bottomhole pressure is measured. For isochronal testing, the well is then shut in until it reaches a stabilized pressure and the procedure is repeated for a different rate. For modified isochronal testing, the well is shut in for a fixed period of time, and the shut-in pressure is measured at the end of that period. The procedure is then repeated at other rates. By repeating this procedure for different time intervals, we can gather information about rate vs. pressure drop in the formation for these time intervals. Ultimately, using this information, our goal is to establish an appropriate rate vs. pressure drop relationship under stabilized conditions. Two procedures are commonly used to establish the equation for rate vs. pressure drop. An empirical method states that q g = C ( p ￣ 2 − p w f 2 ) n . ( 1 ) We can write a simpler equation in terms of pseudo-real pressures as q g = C [ m ( p ￣ ) − m ( p w f ) ] n . ( 2 ) Under transient conditions, the value of C is not constant. Instead, we can write Eq. 2 as q g = C ( t ) [ m ( p ￣ ) − m ( p w f ) ] n , ( 3 ) where C(t) represents a term which is a function of isochronal interval t. In the literature, methods are proposed to estimate the value of C corresponding to the stabilized rate based on the transient state information ?C(t) For example, Hinchman et al.1 propose that 1/C(t)1/n be plotted as a function of log t, and the line be extrapolated until t is equal to the time it takes to reach the stabilized state period. In their method, they assume that n is constant, where n is an inverse of slope when log[m(p¯)−m(pwf)] is plotted as a function of qg. Although we get different straight lines corresponding to different t, the authors assume that the slopes are approximately constant. Another commonly used approach in analyzing isochronal tests is to use an equation, m ( p ￣ ) − m ( p w f ) = a g q g + b g q g 2 . ( 4 ) A similar equation can also be written in terms of pressure squared terms. Eq. 4 is derived starting from Forchheimer's equation. Under transient conditions, we can rewrite Eq. 4 as m ( p ￣ ) − m ( p w f ) = a g ( t ) q g + b g q g 2 , ( 5 ) where ag(t) is a function of isochronal interval, and bg is assumed to be constant. A commonly used technique is to plot ag(t) vs. log (t) and extrapolate ag(t) corresponding to a value of t which represents the time required to reach a stabilized rate.2–4 In using both Eqs. 3 and 5, we have assumed that the contribution due to the non-Darcy effect is not affected during the transient conditions. For example, in applying Eq. 3, we assume that n is constant during the transient period, and in applying Eq. 5, we assume that bg is constant during the transient period. Both n and bg represent the relative contributions of the non-Darcy flow. n will approach 0.5 as the non-Darcy effect becomes dominant, and bg becomes larger as the non-Darcy effect becomes significant. However, by assuming that n and bg are constant during the transient periods, we are ignoring the changes in the relative contributions due to the Darcy and non-Darcy terms. In this article, we extend the previous analysis to account for changes in the non-Darcy term during the transient period. Further, by proper analysis, we propose a method to estimate the value of the turbulence coefficient based on the evaluation of the transient period data. Approach In our approach, instead of using the empirical equation (Eq. 3), we will begin with Forchheimer's equation, where the pressure gradient in a radial reservoir is calculated by ∂ p ∂ r = μ g k v + β ρ g v 2 . ( 6 ) The permeability (k) of the reservoir may be established based on well test data or core information. The turbulence coefficient is difficult to estimate. Although literature correlations5,6 exist to calculate the value of ? based on the laboratory experiments, field evidence7 indicates that the ? values in the field are significantly greater than the laboratory experiments.

An experimental study of the surface elevation probability distribution and statistics of wind-generated waves

1980 ◽  
Vol 101 (1) ◽  
pp. 179-200 ◽  
Author(s):  
Norden E. Huang ◽  
Steven R. Long
Keyword(s):  
Experimental Study ◽  
Probability Density Function ◽  
Probability Distribution ◽  
Wave Field ◽  
Field Data ◽  
Laboratory Experiments ◽  
Laboratory Data ◽  
Surface Elevation ◽  
Strong Wind ◽  
Non Gaussian

Laboratory experiments were conducted to measure the surface elevation probability density function and associated statistical properties for a wind-generated wave field. The laboratory data together with some limited field data were compared. It is found that the skewness of the surface elevation distribution is proportional to the significant slope of the wave field, §, and all the laboratory and field data are best fitted by \[ K_3 = 8\pi\S, \] with § defined as ($(\overline{\zeta^2})^{\frac{1}{2}}/\lambda_0 $, where ζ is the surface elevation, and λ0 is the wavelength of the energy-containing waves. The value of K3 under strong wind could reach unity. Even under these highly non-Gaussian conditions, the distribution can be approximated by a four-term Gram-Charlier expansion. The approximation does not converge uniformly, however. More terms will make the approximation worse.

scholarly journals Investigating the Accuracy of One‐Dimensional Volcanic Plume Models using Laboratory Experiments and Field Data

2019 ◽  
Vol 124 (11) ◽  
pp. 11290-11304
Author(s):  
James S. McNeal ◽  
Graham Freedland ◽  
Larry G. Mastin ◽  
Raúl Bayoán Cal ◽  
Stephen A. Solovitz
Keyword(s):  
Field Data ◽  
Laboratory Experiments ◽  
Volcanic Plume ◽  
One Dimensional

scholarly journals Contrasting effects of cover crops on earthworms: Results from field monitoring and laboratory experiments on growth, reproduction and food choice

2020 ◽  
Vol 100 ◽  
pp. 103225
Author(s):  
Pia Euteneuer ◽  
Helmut Wagentristl ◽  
Siegrid Steinkellner ◽  
Martin Fuchs ◽  
Johann G. Zaller ◽  
...  
Keyword(s):  
Cover Crops ◽  
Food Choice ◽  
Laboratory Experiments ◽  
Field Monitoring

Laboratory Investigation of Fracture Initiation Pressure and Orientation

1979 ◽  
Vol 19 (02) ◽  
pp. 129-144 ◽  
Author(s):  
W.L. Medlin ◽  
L. Masse
Keyword(s):  
Hydraulic Fracture ◽  
Field Data ◽  
Laboratory Experiments ◽  
Fracture Initiation ◽  
Stress Conditions ◽  
Elastic Behavior ◽  
Fracturing Fluids ◽  
Initiation Pressure ◽  
Cylindrical Cavities ◽  
Griffith Theory

Abstract The mechanics of hydraulic fracture initiation have been investigated by comparing laboratory experiments with theoretical predictions based on poro-elastic behavior. Experiments were conducted poro-elastic behavior. Experiments were conducted with 4-in. (10-cm) diameter cores containing spherical and cylindrical cavities and loaded in a triaxial cell under variable confining pressure, end load, and pore pressure. Experimental results agreed with theory for nonpenetrating fracturing fluid for limited ranges of hydrostatic confining stresses for four kinds of limestone rock. With penetrating fracturing fluids, the theory was penetrating fracturing fluids, the theory was confirmed only partially. Under nonhydrostatic stress conditions, reproducibility of measurements was too poor to evaluate the theory. Fracture orientation was controlled predominantly by stress conditions and cavity geometry. Notching of cylindrical cavities failed through notch extension only if the notch depth exceeded the value predicted approximately by a simple Griffith theory predicted approximately by a simple Griffith theory equation. Field applications of all results are discussed. Introduction This paper describes a combined theoretical/ experimental investigation of the mechanics of hydraulic fracture initiation. We considered fracture initiation pressure, fracture orientation, and mode of failure for various stress conditions and wellbore geometries. Our intention has been to consider theory applicable for both field and laboratory conditions, to test this theory with laboratory experiments, and to apply the results to interpretation of field data. The laboratory experiments were designed not to duplicate field conditions so much as to provide a critical test of the theory. Some field data are examined, but it is impractical to learn much about fracture initiation from field experiments because of the limited number of quantities that can be measured. The theory presented here is more a generalization of earlier work than a development of new theory. It provides a completely general treatment of fracture initiation in spherical and cylindrical cavities for poro-elastic materials. An extension of this theory poro-elastic materials. An extension of this theory to porous materials with nonelastic behavior already has been developed by Biot and will be referred to later. We begin by presenting theory for fracture initiation in spherical and cylindrical cavities. The theoretical results are followed by descriptions of laboratory experiments that test the equations for failure pressure in these geometries under various stress conditions, using penetrating and nonpentrating fracturing fluids. The effects of notching in cylindrical cavities then are considered, and a simple model based on Griffith crack theory is developed to explain experimental results. Field applications of all results then are discussed in detail. THEORY OF FRACTURE INITIATION The theory of hydraulic fracture initiation in rock materials has been treated in successive degrees of refinement. Cases of interest are hollow sphere and long hollow cylinder geometry with penetrating and nonpenetrating fracturing fluids. penetrating and nonpenetrating fracturing fluids. Refs. 1 through 7 cover various parts of the overall picture; Rice and Cleary give the most complete picture; Rice and Cleary give the most complete analysis. We present here an independent analysis based on Biot's theory for fluid saturated porous solids. Our analysis adds little that is new to the basic literature of fracture initiation theory. It is presented mainly to provide a way to analyze presented mainly to provide a way to analyze scaling effects between field results and our laboratory experiments. We start with Biot's stress-strain relations for a fluid saturated porous solid: (1) SPEJ P. 129

Thermocline drawdown above cooling water intakes

1982 ◽  
Vol 9 (1) ◽  
pp. 31-37 ◽  
Author(s):  
Emad E. M. Elsayed
Keyword(s):  
Water Body ◽  
Field Data ◽  
Laboratory Experiments ◽  
Thermal Structure ◽  
Cooling Water ◽  
Surrounding Water ◽  
Geometric Properties ◽  
Analytical Expression ◽  
Critical Discharge ◽  
Dimensionless Variables

An analytical expression was developed to define the incipient drawdown of a thermocline into a submerged intake equipped with a circular cover. The critical discharge at the incipient drawdown was expressed in terms of dimensionless variables defining the thermal structure of the surrounding water body and the geometric properties of the intake structure.The relationship was verified by laboratory experiments and by field data.

The influence of soil heterogeneity on exploratory tunnelling by the subterranean termite Coptotermes frenchi (Isoptera: Rhinotermitidae)

2003 ◽  
Vol 93 (5) ◽  
pp. 413-423 ◽  
Author(s):  
T.A. Evans
Keyword(s):  
Water Conservation ◽  
Field Data ◽  
Large Scale ◽  
Laboratory Experiments ◽  
Field Studies ◽  
Soil Heterogeneity ◽  
Large Field ◽  
Small Scale ◽  
Scale Field ◽  
Large Scale Field

AbstractThe exploration of sand-filled arenas by workers of an entire colony of the Australian, subterranean foraging, tree-nesting termite, Coptotermes frenchi Hill was investigated under laboratory conditions. The first experiment tested whether termite exploration of sand was influenced by the presence of gaps or objects in the sand. Gaps and objects were chosen to represent soil heterogeneity in the urban environment: gaps to represent tunnels dug by other animals, perspex strips to represent cables and pipes, and wood strips to represent roots. Termites always chose to explore gaps thoroughly before they began tunnelling in the sand. Significantly more and longer tunnels were excavated from the end of gaps at the far end of the arenas, and relatively little tunnelling occurred around and along objects. Termite density was significantly greater around and along wood compared with perspex blocks. The second experiment tested whether termite exploratory tunnelling was influenced by soil moisture. The termites tunnelled slowly in dry sand, but after discovering a patch of wet sand, increased tunnelling five-fold until it was completely explored, after which activity declined. Energy and water conservation may be behind these patterns of exploratory tunnelling as well as those seen in large field studies, but caution is urged when interpreting small scale laboratory experiments to explain large scale field data.

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