scholarly journals Assessing the ecological hydrology of natural flow conditions in Taiwan

2008 ◽  
Vol 354 (1-4) ◽  
pp. 75-89 ◽  
Author(s):  
Fi-John Chang ◽  
Meng-Jung Tsai ◽  
Wen-Ping Tsai ◽  
Edwin E. Herricks
Keyword(s):  
Flow Conditions ◽  
Natural Flow

scholarly journals An approach to the modeling of a virtual thermal manikin

2014 ◽  
Vol 18 (4) ◽  
pp. 1413-1423 ◽  
Author(s):  
Dragan Ruzic ◽  
Sinisa Bikic
Keyword(s):  
Turbulence Models ◽  
Thermal Conditions ◽  
Heat Fluxes ◽  
Thermal Manikin ◽  
Flow Conditions ◽  
Body Segments ◽  
Nominal Size ◽  
Natural Flow ◽  
Good Agreement ◽  
Made In

The aim of the research described in this paper, is to make a virtual thermal manikin that would be simple, but also robust and reliable. The virtual thermal manikin was made in order to investigate thermal conditions inside vehicle cabins. The main parameters of the presented numerical model that were investigated in this paper are mesh characteristics and turbulence models. Heat fluxes on the manikin's body segments obtained from the simulations were compared with published results, from three different experiments done on physical thermal manikins. The presented virtual thermal manikin, meshed with surface elements of 0.035 m in nominal size (around 13,600 surface elements) and in conjunction with the two-layer RANS Realizable k-? turbulence model, had generally good agreement with experimental data in both forced and natural flow conditions.

Nuisance odours produced by benthic cyanobacteria in a Mediterranean river

2004 ◽  
Vol 49 (9) ◽  
pp. 25-31 ◽  
Author(s):  
E. Vilalta ◽  
H. Guasch ◽  
I. Muñoz ◽  
A. Romaní ◽  
F. Valero ◽  
...  
Keyword(s):  
Nutrient Content ◽  
Flow Conditions ◽  
Cyanobacterial Mats ◽  
River Waters ◽  
Mediterranean River ◽  
Benthic Cyanobacteria ◽  
Natural Flow ◽  
High Nutrient

Geosmin dynamics in the Llobregat waters were related to the waxing and waning of benthic cyanobacterial mats developing in the river. Geosmin concentration in the water during 2002 reached a maximum of 204 ng L-1, and coincided with an abundance of cyanobacteria in the river. Cyanobacterial mats were favoured by the high nutrient content of the waters. The cyanobacterial mats experienced a process of growth in thickness (attached forms), until they became unattached and drifted downstream (free-floating forms), accumulating in shallow areas of the river. Geosmin in the biofilm ranged from 0.55 ± 0.97 ng geosmin per mg DW-1 in the attached biofilms and 5.25 ± 4.96 ng geosmin per mg DW-1 in the free-floating biofilms. While the attached mats could be responsible for the local occurrence of geosmin at a given site, the free-floating mats became a relevant agent for the dispersion of the metabolite downstream. This impression was reinforced by the extremely high correlation between the geosmin content in the free-floating biofilm and in the water (r = 0.917, p = 0.00001). In order to reduce the geosmin concentration and accumulation of the cyanobacterial mats in shallow river waters, the nutrient content should be controlled and the natural flow conditions restored, to prevent the growth and accumulation of the geosmin-producing cyanobacterial mats.

Comparative responses to endothelin-2 and sarafotoxin 6b in the pulmonary vascular bed of the cat

1991 ◽  
Vol 69 (2) ◽  
pp. 211-214 ◽  
Author(s):  
R. K. Minkes ◽  
B. D. Nossaman ◽  
P. Kvamme ◽  
P. J. Kadowitz
Keyword(s):  
Arterial Pressure ◽  
Systemic Arterial Pressure ◽  
Significant Activity ◽  
Constant Flow ◽  
Carboxy Terminus ◽  
Flow Conditions ◽  
Vascular Bed ◽  
Natural Flow ◽  
Pulmonary Arterial ◽  
Pulmonary Vascular Bed

Pulmonary vascular responses to endothelin-2 and sarafotoxin 6b were investigated in the feline pulmonary vascular bed under natural flow and constant flow conditions. Injections of endothelin-2 and sarafotoxin 6b in a dose of 0.3 nmol/kg iv increased pulmonary arterial and left atrial pressures and cardiac output, and caused a biphasic change in calculated pulmonary vascular resistance. Endothelin-2 caused a biphasic change in systemic arterial pressure, while sarafotoxin 6b only decreased arterial pressure. Under constant flow conditions in the intact-chest cat, injections of endothelin-2 and sarafotoxin 6b in doses of 0.1–1 nmol into the perfused lobar artery increased lobar arterial pressure in a dose-related manner but were less potent than the thromboxane A2 mimic, U46619. An ET analog with only the Cys1–Cys15 disulfide bond and an amidated carboxy terminus had no significant activity in the pulmonary vascular bed. The present data show that endothelin-2 and sarafotoxin 6b have significant vasoconstrictor activity in the pulmonary vascular bed of the cat.Key words: pulmonary circulation, endothelin-2, sarafotoxin 6b.

Mass Flux and Enthalpy Distribution in a Rod Bundle for Single- and Two-Phase Flow Conditions

1971 ◽  
Vol 93 (2) ◽  
pp. 197-206 ◽  
Author(s):  
R. T. Lahey ◽  
B. S. Shiralkar ◽  
D. W. Radcliffe
Keyword(s):  
Mass Flux ◽  
Operating Conditions ◽  
Boiling Water ◽  
Flow Diversion ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Water Reactor ◽  
Rod Bundle ◽  
Natural Flow

Diabatic multirod subchannel data have been obtained in a 9-rod bundle for operating conditions typical of a boiling water reactor. These data have been used to obtain both the natural flow and enthalpy distribution in a rod bundle and information on the flow diversion enthalpy and the effective flow diversion length.

Flow-dependent antiarrhythmic properties of ammonia during catecholamine-driven ventricular tachycardia

1992 ◽  
Vol 70 (1) ◽  
pp. 94-99
Author(s):  
A. Malootian ◽  
G. S. Friedrichs ◽  
G. F. Merrill
Keyword(s):  
Blood Flow ◽  
Ventricular Tachycardia ◽  
Coronary Blood Flow ◽  
Coronary Flow ◽  
Ammonium Hydroxide ◽  
Functional Hyperemia ◽  
Flow Conditions ◽  
Natural Flow ◽  
Increased Blood Flow ◽  
Antiarrhythmic Effects

Fifteen mongrel dogs weighing 22–34 kg were instrumented to investigate the antiarrhythmic effects of ammonia (0.1 – 0.2 mmol/min ammonium hydroxide), adenosine (1.87 μmol/min), and saline (0.9% NaCl) during norepinephrine-driven ventricular tachycardia, under conditions of controlled and natural coronary blood flow. Under natural flow conditions, the severe ectopy caused by norepinephrine (100–800 ng∙kg−1∙min−1) was reduced by 42 ± 4% after 30 s of ammonia infusion. Adenosine infusion reduced percent ectopy by 97 ± 2% at 30 s. Ammonia also significantly increased coronary blood flow by 26 ± 4%, while adenosine increased blood flow by 72 ± 14%. Saline infusion had no significant effect on either the severity of ventricular tachycardia or coronary blood flow. Norepinephrine consistently caused coronary functional hyperemia as previously reported. When coronary blood flow was controlled by a peristaltic pump to match natural coronary blood flow and to prevent norepinephrine-induced coronary functional hyperemia, the antiarrhythmic effects of ammonia were lost while those of adenosine were unaffected. Additionally, increasing coronary blood flow manually during norepinephrine-induced ventricular tachycardia, to a level seen with combined norepinephrine and ammonia under natural flow conditions, appeared to worsen the venticular arrhythmias. We conclude that the antiarrhythmic properties of ammonia against norepinephrine-driven ventricular tachycardia might be dependent on coronary blood flow, while those of adenosine are independent of coronary blood flow.Key words: coronary flow, ammonium hydroxide, cardiac, norepinephrine.

U, Th, Eu and colloid mobility in a granite fracture under near-natural flow conditions

2004 ◽  
Vol 92 (9-11) ◽  
Author(s):  
Thorsten Schäfer ◽  
Horst Geckeis ◽  
Muriel Bouby ◽  
Thomas Fanghänel
Keyword(s):  
Flow Velocity ◽  
Test Site ◽  
Swiss Alps ◽  
Flow Conditions ◽  
Grimsel Test Site ◽  
Natural Flow ◽  
Core Migration ◽  
Colloid Mobility

SummaryLaboratory core migration experiments were performed in a granite fracture from the Grimsel Test Site (GTS, central Swiss Alps). The flow velocity was varied (46 m yr

Effects of increasing salinity on freshwater ecosystems in Australia

2003 ◽  
Vol 51 (6) ◽  
pp. 655 ◽  
Author(s):  
D. L Nielsen ◽  
M. A. Brock ◽  
G. N. Rees ◽  
D. S. Baldwin
Keyword(s):  
Physical Environment ◽  
Aquatic Ecosystems ◽  
Freshwater Ecosystems ◽  
Low Flow ◽  
Limited Information ◽  
Flow Conditions ◽  
Saline Groundwater ◽  
Natural Flow ◽  
And Function ◽  
Natural Component

Salt is a natural component of the Australian landscape to which a number of biota inhabiting rivers and wetlands are adapted. Under natural flow conditions periods of low flow have resulted in the concentration of salts in wetlands and riverine pools. The organisms of these systems survive these salinities by tolerance or avoidance. Freshwater ecosystems in Australia are now becoming increasingly threatened by salinity because of rising saline groundwater and modification of the water regime reducing the frequency of high-flow (flushing) events, resulting in an accumulation of salt. Available data suggest that aquatic biota will be adversely affected as salinity exceeds 1000 mg L–1 (1500 EC) but there is limited information on how increasing salinity will affect the various life stages of the biota. Salinisation can lead to changes in the physical environment that will affect ecosystem processes. However, we know little about how salinity interacts with the way nutrients and carbon are processed within an ecosystem. This paper updates the knowledge base on how salinity affects the physical and biotic components of aquatic ecosystems and explores the needs for information on how structure and function of aquatic ecosystems change with increasing salinity.

Hydrochemical and isotopic characterization of carbonate aquifers under natural flow conditions, Sierra Grazalema Natural Park, southern Spain

2017 ◽  
Vol 466 (1) ◽  
pp. 275-293 ◽  
Author(s):  
Damián Sánchez ◽  
Juan Antonio Barberá ◽  
Matías Mudarra ◽  
Bartolomé Andreo ◽  
José Francisco Martín
Keyword(s):  
Southern Spain ◽  
Flow Conditions ◽  
Carbonate Aquifers ◽  
Natural Park ◽  
Natural Flow ◽  
Isotopic Characterization

scholarly journals Sensitivity of Regulated Flow Regimes to Climate Change in the Western United States

2018 ◽  
Vol 19 (3) ◽  
pp. 499-515 ◽  
Author(s):  
Tian Zhou ◽  
Nathalie Voisin ◽  
Guoyong Leng ◽  
Maoyi Huang ◽  
Ian Kraucunas
Keyword(s):  
Climate Change ◽  
Water Management ◽  
United States ◽  
River Flow ◽  
Flow Regimes ◽  
Western United States ◽  
Regulated River ◽  
Flow Conditions ◽  
Natural Conditions ◽  
Natural Flow

Abstract Water management activities modify water fluxes at the land surface and affect water resources in space and time. Conventional understanding on the role of water management suggests that regulated river flow would be less sensitive to future climate conditions than natural flow in terms of the absolute changes in mean monthly flows. In this study the authors evaluate such an assumption by redefining sensitivity as the difference in the emergence of changes in cumulative distribution functions (CDFs) of future regulated and natural flows in response to climate change with respect to their respective historical regulated and natural flow conditions. The emergence of changes (shift in CDFs) in natural and regulated river flow regimes across the western United States from simulations driven by multiple climate models and scenarios were compared. Forty percent of Hydrologic Unit Codes 4 (HUC4s) over the western United States might perceive such a shift in seasonal regulated flow earlier than they would have seen in natural flow conditions, although the absolute change is smaller than that under natural conditions. About 10% of the regulated HUC4s see a delay and are therefore less sensitive to climate change. In the spring (MAM), the overall sensitivity tends to decrease as the level of river regulation increases, as expected. However, in the winter (DJF) and summer (JJA) seasons, the sensitivity tends to increase with increasing levels of regulation, with changes in smaller magnitudes than under natural conditions. The results could inform integrated assessment studies when designing adaptation strategies in the water–energy–food nexus.

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