Water flow frequency distribution

Taylor et al. (T6, T7) have reported on wave velocities in upward cocurrent gas/film flow. It was found that the wave velocity increased rapidly with increasing gas flow rate but varied little with liquid flow rate. It was found, furthermore, that the individual wave velocities were not uniformly distributed around the mean value under given flow conditions, but that certain preferred velocities appeared to exist. The reasons for such behavior are not clear at present. More recently, Nedderman and Shearer (Nla) have carried out similar studies over a wider range of gas and liquid flow rates. Although the results were similar in many respects, it seems that the wave frequencies, of the large disturbance waves in particular, are dependent on the geometry of the apparatus. These results showed that, at constant water flow rate, the wave velocity for upward cocurrent flow varied with the square root of the air velocity relative to the waves. 

PG-ROUT is a deterministic river model applicable throughout the United States (57). Predictions are based on more than 500,000 United States river miles. This model also predicts concentrations under 7Q10 and mean-flow conditions. The model is driven by several large EPA databases. Predictions are made below each of the 11,500 POTWs, at drinking water intakes and at any desired mile points in the river systems. The model output includes a frequency distribution by river mile and a detailed PC database. 

Inspection and Preventive Maintenance As with all water-based extinguishing systems, particularly those installed outside, inspection and preventive maintenance are critical to reliable operation. Detection devices are typically inspected, tested, and maintained quarterly or at a frequency deemed more appropriate for a particular location. The water-spray system itself is typically flow-tested at least annually (NFPA 25, 1995). Because of the nozzles small orifice size, scale and corrosion buildup can compromise flow and spray patterns. The use of strainers and the conduct of flow tests will help minimize this potential problem. As stated earlier, preventive maintenance of the overall water supply and distribution systems is an integral part of a reliable system. 

The results obtained during the Couette flow of aqueous solutions of polyethylene oxide and other water-soluble polymers appear especially promising since they showed an appreciable increase in the current noise level with shear rate. The current noise level depended also on the viscosity (molecular weight) of the solution. A slight increase of thermal noise was recorded also. The pseudoplasticity exponent n in the Ostwald-de Waele power law formula and the exponent a in the l/f -frequency distribution of the current noise were interrelated. This relation appeared to be generally valid. 

When the anode and cathode humidities are different, we saw in Figure 8.11 that the proton distribution is shifted in the direction of additional water flow toward the cathode. Also in Figure 8.16, the impedance increases at high frequency when the additional water flow is toward the cathode. However,... 

When the airflow rate is doubled to 2 L min the low-frequency arc vanishes, as shown in Figure 6.38. This can be explained by a change in the stoichiometry coefficient and a decrease in liquid water content in the GDL as more water is removed from the cell via the air stream. With an air flow rate of only 1 L min 1 there is no significant performance loss. Since the variations between the individual cell voltages do not vanish at higher airflow rates, the variations are not attributable to improper air distribution within the stack. 

Such changes could be due to an increase in the frequency or severity of storms. Strong winds tend to increase the intensity of random water-velocity fluctuations near the Sound floor but produce only a small change in the mean flow (Bokuniewicz and Gordon, this volume, p. 84). In terms of the mass-balance equation, the diffusion coefficient for mobile sand might be expected to increase during periods of high winds. The influence of such events on the sand distribution was examined with a tifne-de-... 

Induction heating uses a medium- or high-frequency electric coil (water cooled) to induce a current in a metal load. (See figs. 3.1 and 3.2.) The flux lines are most concentrated just below the surface of the load. Conduction distributes the heat across the load. The heat flow is not reduced by surface resistances as with convection and radiation. 

Anticipated operational occurrences are off-normal events, usually plant transients, which can be coped with by the plant protection systems and normal plant systems but which could have the potential to damage the reactor if some additional malfunction should happen. Their typical frequency of occurrence may be more than 10 year Some of the anticipated occurrences (PIEs - postulated initiating events) are due to the increase of reactor heat removal (as might occur for an inadvertent opening of a steam relief valve, malfunctions in control systems, etc.). Some are due to the decrease of reactor heat removal (such as for feed-water pumps tripping, loss of condenser vacuum and control systems malfunctions). Some are due to a decrease in reactor coolant system flow rate, as in the case of a trip of one or more coolant pumps. Some are connected with reactivity and power distribution anomalies, such as for an inadvertent control rod withdrawal or unwanted boron dilution due to a malfunction of the volume control system for a PWR. Events entailing the increase or decrease of the reactor coolant inventory may also happen, due to malfunctions of the volume control system or small leaks. Finally, releases of radioactive substances from components may occur. 

Frequency spectra or moments of the velocity distribution do give some additional information. A sketch of Sinha s results for water, premix polymer solution and nonhomogeneous injection is shown in Figure 7. The comparison is for equal Reynolds numbers and equal drag reduction for the polymer flows. Premix solutions show a lower skewness of axial fluctuations than pure solvent in the center of the pipe and no change near the wall. 

Water quality monitoring consists of frequent analysis of the main constituents. The required data input consists of (1) mean composition of the influent (2) mean composition of native groundwater in each layer of the target aquifer (3) native geochemistry of each layer of the target aquifer (4) the cumulative frequency curve of detention times in each model layer or flow path as derived from either separately run hydrological model or tracer breakthrough data and (5) specific information derived from the mass balance of the water phase (the reactions that are needed, how O2 and NO3" distribute over the various redox reactions, etc.). 

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