Water temperature modelling in a small forested stream: implication of forest canopy and soil temperature

2000 ◽  
Vol 27 (6) ◽  
pp. 1095-1108 ◽  
Author(s):  
André St-Hilaire ◽  
Guy Morin ◽  
Nassir El-Jabi ◽  
Daniel Caissie
Keyword(s):  
Soil Temperature ◽  
Water Temperature ◽  
Forest Canopy ◽  
Deterministic Model ◽  
Heat Budget ◽  
Original Model ◽  
Small Catchment ◽  
Negative Exponential Function ◽  
Modified Model ◽  
Crown Closure

The demand for comprehensive environmental assessment of river ecosystem has increased for engineers and scientists. Accurate and versatile water temperature models are required to meet this demand. A number of hydrological models take vegetation and soil characteristics into account, but very few temperature models do. The objective of this paper is to incorporate soil temperature and vegetation as input variables in a deterministic heat budget model. The CEQUEAU hydrological and water temperature model was used to simulate water temperature in Catamaran Brook, a small catchment located in central New Brunswick. The model was modified by incorporating soil temperature as a parameter influencing the temperature of interflow, using the so-called force-restore method. Crown closure was also incorporated in the model as a factor influencing locally advected water using a negative exponential function. The modified model simulated daily water temperatures better than the original model. Root-mean-square error for a period of 5 years decreased from 2.10°C with the original model to 1.77°C with the modified model. Nash coefficient increased from 0.78 with the original model to 0.82 with the modified model. An analysis of residuals showed that the modified model is sensitive to additional parameters such as crown closure, especially for short time scales during periods of higher discharge and during extreme meteorological and hydrological events such as tropical storms.Key words: stream temperature, hydrology, deterministic model, CEQUEAU, forestry.

scholarly journals Modification and Validation of the Phosphate Removal Model: A Multicenter Study

2021 ◽  
pp. 1-10
Author(s):  
Weichen Zhang ◽  
Qiuna Du ◽  
Jing Xiao ◽  
Zhaori Bi ◽  
Chen Yu ◽  
...  
Keyword(s):  
Polynomial Regression ◽  
External Validation ◽  
Original Model ◽  
Phosphate Concentration ◽  
Phosphate Removal ◽  
Internal Validation ◽  
Modified Model ◽  
New Model ◽  
Significant Difference ◽  
Removal Model

<b><i>Background:</i></b> Our research group has previously reported a noninvasive model that estimates phosphate removal within a 4-h hemodialysis (HD) treatment. The aim of this study was to modify the original model and validate the accuracy of the new model of phosphate removal for HD and hemodiafiltration (HDF) treatment. <b><i>Methods:</i></b> A total of 109 HD patients from 3 HD centers were enrolled. The actual phosphate removal amount was calculated using the area under the dialysate phosphate concentration time curve. Model modification was executed using second-order multivariable polynomial regression analysis to obtain a new parameter for dialyzer phosphate clearance. Bias, precision, and accuracy were measured in the internal and external validation to determine the performance of the modified model. <b><i>Results:</i></b> Mean age of the enrolled patients was 63 ± 12 years, and 67 (61.5%) were male. Phosphate removal was 19.06 ± 8.12 mmol and 17.38 ± 6.75 mmol in 4-h HD and HDF treatments, respectively, with no significant difference. The modified phosphate removal model was expressed as Tpo<sub>4</sub> = 80.3 × <i>C</i><sub>45</sub> − 0.024 × age + 0.07 × weight + β × clearance − 8.14 (β = 6.231 × 10<sup>−3</sup> × clearance − 1.886 × 10<sup>−5</sup> × clearance<sup>2</sup> – 0.467), where <i>C</i><sub>45</sub> was the phosphate concentration in the spent dialysate measured at the 45th minute of HD and clearance was the phosphate clearance of the dialyzer. Internal validation indicated that the new model was superior to the original model with a significantly smaller bias and higher accuracy. External validation showed that <i>R</i><sup>2</sup>, bias, and accuracy were not significantly different than those of internal validation. <b><i>Conclusions:</i></b> A new model was generated to quantify phosphate removal by 4-h HD and HDF with a dialyzer surface area of 1.3–1.8 m<sup>2</sup>. This modified model would contribute to the evaluation of phosphate balance and individualized therapy of hyperphosphatemia.

Modification of DDES Based on SST kω Model for Tip Leakage Flow in Turbomachinery

2020 ◽  
Author(s):  
Yanfei Gao ◽  
Yangwei Liu
Keyword(s):  
Reynolds Number ◽  
Flow Model ◽  
Turbulence Modeling ◽  
Streamwise Vortex ◽  
Original Model ◽  
Leakage Flow ◽  
Mean Flow ◽  
Tip Leakage Flow ◽  
Modified Model ◽  
Tip Leakage

Abstract Both LES and DDES are conducted in a low-Reynolds number tip leakage flow model. The DDES uses the SST kω model and employs the same grid with the LES, but the turbulence field diverges from the LES result. Referring to the comparison between LES and DDES, a modification of the zonal function in the DDES model is proposed, which enhances the dissipation of the modeled turbulence thus promote the transition to fully LES in the tip region when the mesh is fine enough. It can generate much finer vortex structure than the original model, including the primary streamwise vortex, induced vortices and the vortex fragments after breakdown. The modification fixes the underestimation of the vorticity and pressure drop at the formation stage of the tip leakage vortex, and generates more reasonable turbulence field and energy spectra. The modified model is introduced to a real rotor simulation at engineering Reynolds number. Compared with the original model on both mean flow field and turbulence field, the modified model shows favorable agreements with the measurements. The study also gives a practical example of using the tip leakage flow model in turbulence modeling.

scholarly journals An Improved Numerical Simulation Approach for the Failure of Rock Bolts Subjected to Tensile Load in Deep Roadway

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Rui Wang ◽  
Jian-biao Bai ◽  
Shuai Yan ◽  
Yuan-ba Song ◽  
Guang-dong Wang
Keyword(s):  
Numerical Simulation ◽  
Tensile Load ◽  
Elongation Rate ◽  
Original Model ◽  
Rock Bolt ◽  
Tensile Failure ◽  
Simulation Approach ◽  
Rock Bolts ◽  
Modified Model ◽  
Free Section

Our goal was to develop an effective research tool for roadways with significant deformations supported by rock bolts. The improved numerical simulation approach is constructed through additional development of FLAC3D. The aim is to modify the shortcoming that the original model in FLAC3D regards the plastic tensile strain of any arbitrary rock bolt element node as the rupture discrimination criterion. The FISH programming language is adopted to conduct the secondary development and to embed the revised model into the main program of FLAC3D. Taking an actual mining roadway as the simulation object, two simulation schemes adopting the newly improved approach and the original method were conducted, respectively. The results show that (1) the PILE element that constitutes the rock bolt-free section with the maximum elongation rate ruptures after modification, while the rock bolt tendon elongation rate reaches beyond the predefined tensile rupture elongation rate; (2) the modified model in which the rock bolt is mainly subjected to tension realises the tensile rupture phenomenon at the end of the rock bolt-free section and the rock bolt at the junction between the free section and the anchoring section; and (3) only four rock bolts that are in the roadway sides showed rupture in the modified model, and all rock bolts showed rupture in the original model. The tensile failure of the rock bolt led that the modified model scheme is closer to the actual. Compared with the modified model, in the original model, deformation of the surrounding rock masses is severe. This is resulted by the rupture of all rock bolts in the original model. The analysis shows that the improved numerical simulation approach is much more reliable for large deformation roadway behavior with rock bolt support.

scholarly journals The Influence of Hyporheic Exchange on Water Temperatures in a Headwater Stream

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1615
Author(s):  
Christopher Surfleet ◽  
Justin Louen
Keyword(s):  
Water Temperature ◽  
Heat Budget ◽  
Stream Water ◽  
Temperature Response ◽  
Headwater Stream ◽  
Low Flow ◽  
Hyporheic Exchange ◽  
Maximum Temperature ◽  
Net Radiation ◽  
Heat Transfers

A headwater stream in coastal California was used to evaluate the temperature response of effective shade reduction. Spatial distribution of stream water temperatures for summer low-flow conditions (<0.006 m3 s−1) were highly correlated with net radiation and advective heat transfers from hyporheic exchange and subsequent streambed conduction. Using a heat budget model, mean maximum stream water temperatures were predicted to increase by 1.7 to 2.2 °C for 50% and 0% effective shade scenarios, respectively, at the downstream end of a 300 m treatment reach. Effects on mean maximum stream water temperature changes, as water flowed downstream through a 500 m shaded reach below the treatment reach, were reduced by 52 to 30% from the expected maximum temperature increases under the 50% and 0% effective shade scenarios, respectively. Maximum stream water temperature change predicted by net radiation heating alone was greater than measured and heat-budget-estimated temperatures. When the influence of hyporheic water exchange was combined with net radiation predictions, predicted temperatures were similar to measured and heat-budget-predicted temperatures. Results indicate that advective heat transfers associated with hyporheic exchange can promote downstream cooling following stream water temperature increases from shade reduction in a headwater stream with cascade, step-pool, and large woody debris forced-pool morphology.

Reproduction of salal (Gaultheriashallon) under forest canopy

1990 ◽  
Vol 20 (1) ◽  
pp. 91-100 ◽  
Author(s):  
F. L. Bunnell
Keyword(s):  
Sexual Reproduction ◽  
Forest Canopy ◽  
Vegetative Reproduction ◽  
Resource Limitation ◽  
Shoot Density ◽  
Physiological Integration ◽  
Forest Canopies ◽  
Plant Persistence ◽  
Crown Closure ◽  
Optimality Models

Sexual and vegetative reproduction of salal (Gaultheriashallon Pursh) was measured under forest canopies of different closure. Sexual reproduction occurred only at ≤33% closure; vegetative reproduction occurred under sparse and dense closure. Crown closure influenced sexual reproduction primarily through interception of radiation and associated reductions in salal vigour. Irradiance had a greater influence on the mode of reproduction than did shoot density, and allocation of total reproductive effort (sexual plus vegetative) was contrary to optimality models, but consistent with resource limitation. No shoot <5 years old flowered; shared costs of flowering indicated physiological integration among salal shoots. Vegetative reproduction was negatively associated with age (r2 = 0.95), and 85% of the space occupied after 9 years of growth was occupied during the first 3 years. Under canopy the spatial pattern of salal shoots was better adapted to maintain plant persistence than to colonize new areas. Implications of salal's rates and modes of reproduction to forest and wildlife management are noted.

Refinements to the Ergonomic Model for Keyboard Fingering of Parncutt, Sloboda, Clarke, Raekallio, and Desain

2001 ◽  
Vol 18 (4) ◽  
pp. 505-511 ◽  
Author(s):  
J. Pieter Jacobs
Keyword(s):  
Original Model ◽  
Modified Model

Aspects of the groundbreaking ergonomic model for keyboard fingering of isolated melodic fragments developed by R. Parncutt, J. A. Sloboda, E. F. Clarke, M. Raekallio, and P. Desain (1997) are reviewed, including the potentially problematic specification of finger spans in semitones. Modifications to some of the underlying rules are introduced in order to better reflect modern piano-pedagogical thought on finger strength and the playing of notes that are not spaced closely together on the keyboard. On the whole, the modified model had more pianists' fingering choices represented in its top predicted fingerings for opening fragments of Czerny studies than did the original model.

Replication and extension of Little et al.'s (2003) forms and functions of aggression measure

2008 ◽  
Vol 32 (3) ◽  
pp. 238-242 ◽  
Author(s):  
Paula J. Fite ◽  
Kirstin Stauffacher ◽  
Jamie M. Ostrov ◽  
Craig R. Colder
Keyword(s):  
Factor Analysis ◽  
Confirmatory Factor Analysis ◽  
Aggressive Behavior ◽  
Small Sample ◽  
Original Model ◽  
Modified Model ◽  
American Sample ◽  
Confirmatory Factor ◽  
Exact Replication

The goal of the current study was to replicate the confirmatory factor analysis of Little et al.'s (2003) aggression measure in an American sample of 69 children (mean age = 12.93 years; SD = 1.27). Although an exact replication of the original model could not be estimated given the small sample, a modified model representing a conceptual replication provided a good fit to the data. Findings suggest that this child self-reported aggression measure can be used with American samples to distinguish four domains of aggressive behavior (relational, overt, instrumental, and reactive).

scholarly journals Investigation into Settlement Behaviour of Mussels and the Hydrology of a Selected Area with a View to Farming the Shellfish

2021 ◽  
Author(s):  
◽  
Philip Tortell
Keyword(s):  
Water Temperature ◽  
Mytilus Edulis ◽  
Environmental Conditions ◽  
Catchment Area ◽  
Organic Nitrogen ◽  
Water Movement ◽  
Freshwater Inflow ◽  
Small Catchment ◽  
Perna Canaliculus ◽  
Suitable Substrate

<p>Physical observations in the Beatrix Basin, Marlborough Sounds, New Zealand, revealed four distinct regions: a partially exposed northern region with moderate water currents, low rainfall, small catchment area and scant freshwater inflow; a central highly exposed region with strong currents, moderate rainfall, no land catchment area and no direct freshwater inflow; an eastern region with a high degree of exposure and strong water movement, moderate rainfall, extensive catchment and seasonally high freshwater inflow; a southern sheltered region with sluggish water movement, comparatively high rainfall, extensive catchment and the highest rainfall in the study area. Differences between the four regions in monthly mean temperature and salinity were slight and there was an indication of more mixing in the central region than elsewhere. No thermocline was observed and surface water temperature demonstrated a diurnal rhythm in summer. Mean winter temperature fell to 10 degrees C and rose to 17 degrees C in summer. Mean salinity ranged from 32.8 degrees C in winter to 34.8 degrees C in summer and no halocline was present. Salinity fell occasionally after heavy rain, but tidal currents soon dissipated the freshwater except in the southern region where it persisted for a short time. The reproductive cycles of Perna canaliculus and Mytilus edulis aoteanus, the occurrence of their larvae in plankton samples, their season of settlement and peaks in settlement activity, were monitored. Physical environmental conditions preceeding or accompanying spatfall were recorded. A broad temporal relationship was found between spawning adult mussels, pelagic larvae, environmental conditions, and settlement of Perna canaliculus in Elie Bay. It appears that P. canaliculus spawned in early summer and in autumn when the water temperature was 18 plus-minus 0.5 degrees C. However, it was not possible to predict spatfall since the duration of the pelagic phase was not known and settlement is a function of larval survival and dispersal, as well as the presence of a suitable substrate. Accurate spatfall prediction is required to facilitate timed immersion of spat-collecting ropes while ensuring "seasoning" and avoiding fouling. As it was not possible to predict settlement by relating it to other biological or physical phenomena, this study sought an alternative spat-collecting material not so susceptible to fouling but still attractive to mussels. Carbon black fibrillated polypropylene film proved to be such an alternative. The determination of available food for mussels within the study area was attempted using particulate organic nitrogen as the indicator. The problems encountered are discussed. The concentration of particulate organic nitrogen was 11.78 microgram at N/litre. The larvae of Mytilus edulis aoteanus and Aulacomya maoriana were reared in the laboratory to the late veliger stage. The most likely causes of their failure to metamorphose were a too high larval density, an excess of food organisms and the lack of a suitable substrate for settlement. It was not possible to induce spawning of Perna canaliculus under controlled conditions.</p>

Sign in / Sign up

Export Citation Format

Share Document