Increase In Inflow Rate Research Articles

Effects of upslope inflow rate, tillage depth, and slope gradients on hillslope erosion processes and hydrodynamic mechanisms

Inflow rate, tillage depth and slope gradient play vital roles in hillslope soil erosion processes. However, the effects of these factors and their interactions on hillslope soil erosion processes, particularly on long slopes in the Chinese Mollisol region, are still lacking to date. Thus, a set of laboratory experiments, including six upslope inflow rates (0, 50, 100, 150, 200 and 300 L min−1), two tillage depths (5 and 20 cm) and two slope gradients (5° and 10°), were conducted to quantify the impacts of these factors and their interactions on hillslope soil erosion processes. The results showed that soil erosion rates increased as a power function with increase of inflow rate and slope gradient, while they decreased as a power function with an increase in tillage depth. The slope gradient had a greater impact on soil erosion rates than inflow rate and tillage depth. Moreover, inflow rate, slope gradient, and their pairwise interaction mainly governed hillslope soil erosion. Compared with hillslope soil erosion, hillslope runoff rate was dominantly affected by inflow rate. The inflow rate and slope gradient affected the hydrodynamic characteristics and erosion rates by shifting erosion patterns; while tillage depth mainly influenced them by converting surface flow to seepage flow. In addition, the dimensionless effective stream power was the optimal index (R2 = 0.884, NSE = 0.861) affecting soil erosion rates, followed by the dimensionless stream power (R2 = 0.879, NSE = 0.848). The dimensionless soil erosion rates were correlated with the dimensionless hydrodynamic parameter following a power function. Therefore, soil erosion in the Chinese Mollisol region could be effectively prevented by dispersing runoff, increasing deep tillage and reducing the impact of slope gradient through soil conservation measures.

Length Measurement of Chain-Like Structure of Micron Magnetic Particles Dispersing in Carrier Fluid Effected by Magnetic Field

The chain-like structure and motion of the magnetic particles (MPs) in magnetorheological fluid (MRF) determine the rheological properties of MRF. In order to investigate the appearance and motion state of the chain-like structure of MPs under both static and flowing states of MRF, the formation process of MP chains in a stationary MRF under the action of an external magnetic field was observed by microscope. And the length of MP chains was measured by an objective micrometer to reveal the key factors affecting the length of formed chain. The MP chains broke after the magnet rotated by 90 degrees. The MRF was injected into a microchannel to observe the motion of MP chains. The speeds of the MP chains were measured by micrometer under different magnetic field strengths and inflow rates. The static test results show that the particle diameter has the greatest influence on the length of chain. The maximum length of the MP chains is 978.2 μm with a magnetic field strength of 130.31 mT; the diameter and mass fraction of the MPs are 2 μm and 3%. The MP chains will break from a long chain into short chains and rotate at a certain angle due to the rotation of magnetic field. The test results at different inflow rates show that the moving speed of MP chains in the microchannel increases with the increase of inflow rate and the decrease of magnetic field strength. In addition, the MP chains can withstand a carrier fluid flow rate of up to 0.32 m/s.

A laboratory study of channel sidewall expansion in upland concentrated flows

Gully erosion contributes large amounts of sediment within watersheds around the world. Gully widening constitutes about 80% of total soil loss, especially in the presence of a plow pan which manifests a less or non-erodible soil layer. Current knowledge on sidewall toe scour (scour arcs) and tension crack processes in gully widening is limited. Thus, simulated channel sidewall expansion tests, where the channel bed was fixed to represent a non-erodible layer, were designed to investigate how inflow rate, slope gradient and initial channel width affect channel widening processes. Soil boxes (2.0 m-long, 0.3 m-wide and 0.5 m-deep) with two slope gradients (15° and 20°), four inflow rates (1.0, 2.0, 3.0 and 4.0 L min−1) and two initial channel widths (4 and 8 cm) were subjected to clear-water overland flow. Photogrammetry was used to detect tension crack and width variations of channels. The results show that sediment delivery and channel width increase with the increase of inflow rate, bed slope and the decrease of initial channel width. Exponential equations were used to predict the channel width time series. Time lag occurred between sediment peak and soil block failure. Toe scour, crack development, sidewall failure and block detachment and transport, in sequence, were the four main processes of channel widening. Basal scour arc length, tension crack length and width decreased with initial channel width and increased with time, flow discharge and bed slope. Basal scour arcs were divided into three patterns according to different shapes in comparison to the failure arcs. Sediment delivery equations based on the disaggregation of concentrated flow entrainment and mass failure were also fitted. This study provides new insight on improving gully erosion measurements and prediction technology.

Dynamic simulation for wastewater treatment plants management: Case of Souk-Ahras region, north-eastern Algeria

AbstractTreatment performances of two wastewater treatment plants (WWTPs), located in North-Eastern Algeria (Souk-Ahras and Sedrata) were tested using ASM1 model. The model, to be considered as a decision tool for the appropriate management of activated sludge systems, served for the prediction of both WWTP behaviours under different operating conditions. In Sedrata WWTP the first management scenarios is based on an increase of inflow rate, taking into account a new transfer volume from a nearby zone. In a second scenerio, the ultimate flow of 40 000 m3·d-1 is estimated. Regarding Souk-Ahras WWTP, three scenarios were tested. The first tested the impact of an increase of the extraction flow rate and yielded a reduction by 37% of sludge production. The second dealt with the management of the mass budget of substrata and biomass. Finally, the third application was devoted to the estimation of the plant ultimate capacity, estimated to be 60 000 m3·d-1.

Numerical and multivariate stochastic approaches to characterize flow in a constructed wetland basin

Reduction in specific and viscous dissipation rate in surface waters by flow control and contaminant removal are the goals of constructed wetlands. A two-dimensional simulation study on surface flow through a constructed wetland in Guilin, China is performed. The flow through the wetland is modeled and dynamically simulated by distinct case studies by varying both inlet width and inflow rate. Nonlinear increase in peak dynamic pressure and specific dissipation rates as a function of increasing inflow rate is reported for the different cases studied. The results of the numerical models confirm an increase in viscous dissipation, shear stress and dynamic pressure within the wetland with increase in inflow rate. These modeling results are used as inputs for performing a statistical data analysis. Further, a multivariate stochastic statistical framework has been proposed for the prediction of dissipation as a function of variables including inflow rate, inlet geometry and wall shear stress. Multivariate and variance analysis is performed to validate the appropriateness of the theoretical models proposed. Results provide simplified meaningful suggestions to constructed wetland design and related applications.

Heavy Metals Removal in a Horizontal Rotating Tubular Bioreactor

Mixed microbial culture was isolated from heavy metal-contaminated ground soils located inside iron, vinyl and cement factory area. Isolated mixed microbial culture was used for the heavy metal ions (Fe2+, Cu2+, Ni2+ and Zn2+) removal process in horizontal rotating tubular bioreactor (HRTB). In this research, the effect of bioreactor process parameters on the bioprocess dynamics in the HRTB was studied. Results of this research have shown that profiles of heavy metals concentration were gradually reduced along HRTB at all combinations of bioreactor process parameters [inflow rates (0.5–2.0 L h-1) and rotation speed (5–30 min-1)]. Hydrodynamic conditions and biomass sorption capacity have main impact on the metal ions removal efficiency that was varied in the range of 38.1% to 95.5%. Notable pH gradient (cca 0.7 pH unit) along the HRTB was only observed at the inflow rate of 2.0 L h-1. On the basis of obtained results, it is clear that medium inflow rate (F) has higher impact on the heavy metal removal process than bioreactor rotation speed (n) due to the fact that increase of inflow rate was related to the reduction of equilibrium time for all examined metal ions. Furthermore, equilibrium times for all metal ions are significantly shorter than medium residence times at all examined combinations of bioreactor process parameters. The main impact on the biofilm sorption capacity has covalent index of metal ions and biofilm volumetric density. The sorption capacity of suspended microbial biomass is closely related to its concentration. Results of this research have also shown that the removal of heavy metals ion can be successfully conducted in an HRTB as a one-step process.

Heterotrophic cultivation of Paracoccus denitrificans in a horizontal rotating tubular bioreactor

In this work, the heterotrophic cultivation of bacterium Paracoccus denitrificans has been studied in a horizontal rotating tubular bioreactor (HRTB). After development of a microbial biofilm on the inner surface of the HRTB, conditions for one-step removal of acetate and ammonium ion were created. The effect of bioreactor process parameters [medium inflow rate (F) and bioreactor rotation speed (n)] on the bioprocess dynamics in the HRTB was studied. Nitrite and nitrogen oxides (NO and N2O) were detected as intermediates of ammonium ion degradation. The biofilm thickness and the nitrite concentration were gradually reduced with increase of bioreactor rotation speed when the medium inflow rate was in the range of 0.5–1.5 l h−1. Further increase of inflow rate (2.0–2.5 l h−1) did not have a significant effect on the biofilm thickness and nitrite concentration along the HRTB. Complete acetate consumption was observed when the inflow rate was in the range of 0.5–1.5 l h−1 at all bioreactor rotation speeds. Significant pH gradient (cca 1 pH unit) along the HRTB was only observed at the highest inflow rate (2.5 l h−1). The results have clearly shown that acetate and ammonium ion removal by P. denitificans can be successfully conducted in a HRTB as a one-step process.

Factors Affecting the Concentration of Compound A Resulting from the Degradation of Sevoflurane by Soda Lime and Baralyme Registered Trademark in a Standard Anesthetic Circuit

Carbon dioxide absorbents, such as soda lime and Baralyme Registered Trademark brand absorbent, convert sevoflurane to CF2 = C(CF3)OCH2 F, a vinyl ether called "Compound A," whose toxicity raises concerns regarding the safety of sevoflurane in rebreathing circuits.Because an increased inflow rate to an anesthetic circuit decreases rebreathing, we assumed that an increased rate would proportionately decrease the concentration of Compound A. In the present report, we measured the Compound A concentration resulting from the action of wet (standard) soda lime and wet (standard) Baralyme Registered Trademark on 2% sevoflurane in a model anesthetic circuit, using inflow rates (0.5, 1.0, 2.0, 4.0, and 6.0 L/min), ventilations (5 and 10 L/min), and carbon dioxide production/removal (200 and 400 mL/min) found in clinical practice. An increase in inflow rate decreased Compound A concentration to lower levels as inflow rate approached minute ventilation. At lower inflow rates, increasing duration of sevoflurane inflow increased the concentration of Compound A, a finding consistent with a progressive increase in absorbent temperature from absorption of carbon dioxide and consequently greater sevoflurane degradation. There was no material difference between Baralyme Registered Trademark and soda lime in the concentrations of Compound A produced at a particular inflow rate. An increase in ventilation increased the concentration of Compound A, having a much greater effect at high rather than low inflow rates. An increase in amount of carbon dioxide absorbed also increased the concentration of Compound A. We conclude that inflow rate, ventilation, and carbon dioxide production are major determinants of the concentration of Compound A. (Anesth Analg 1995;81:564-8)

Factors affecting the concentration of compound A resulting from the degradation of sevoflurane by soda lime and Baralyme in a standard anesthetic circuit.

Carbon dioxide absorbents, such as soda lime and Baralyme brand absorbent, convert sevoflurane to CF2 = C(CF3)OCH2F, a vinyl ether called "Compound A," whose toxicity raises concerns regarding the safety of sevoflurane in rebreathing circuits. Because an increased inflow rate to an anesthetic circuit decreases rebreathing, we assumed that an increased rate would proportionately decrease the concentration of Compound A. In the present report, we measured the Compound A concentration resulting from the action of wet (standard) soda lime and wet (standard) Baralyme on 2% sevoflurane in a model anesthetic circuit, using inflow rates (0.5, 1.0, 2.0, 4.0, and 6.0 L/min), ventilations (5 and 10 L/min), and carbon dioxide production/removal (200 and 400 mL/min) found in clinical practice. An increase in inflow rate decreased Compound A concentration to lower levels as inflow rate approached minute ventilation. At lower inflow rates, increasing duration of sevoflurane inflow increased the concentration of Compound A, a finding consistent with a progressive increase in absorbent temperature from absorption of carbon dioxide and consequently greater sevoflurane degradation. There was no material difference between Baralyme and soda lime in the concentrations of Compound A produced at a particular inflow rate. An increase in ventilation increased the concentration of Compound A, having a much greater effect at high rather than low inflow rates. An increase in amount of carbon dioxide absorbed also increased the concentration of Compound A. We conclude that inflow rate, ventilation, and carbon dioxide production are major determinants of the concentration of Compound A.

Enhancement of the post-occlusive oscillation in the splenic circulation by adenosine.

1. The blood flow to the splenic artery of dogs anaesthetized with sodium pentobarbitone was measured under constant pressure perfusion with the animal's own blood led from the femoral artery.2. Immediately after release of occlusion there was a rapid increase of inflow rate above the pre-occlusion level which then oscillated up and down. In a majority of cases such oscillatory responses continued for a while but progressively diminished during a period of about 6 min.3. This post-occlusive oscillatory response was not modified by either neural or autonomic receptor blocking agents such as tetrodotoxin, guanethidine, phentolamine, propranolol, atropine and methysergide.4. In the cases with a relatively short-lasting response, the selective administration of adenosine into the splenic artery caused a distinct enhancement of the oscillation.5. These results suggest that adenosine may play an important role in the post-occlusive oscillatory response of the splenic circulation.