Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Open-channel-like

From Eq. (43), asymptotically (i.e., for U vo) one has Vf U/la(U), which corresponds to (40) for a = 1. Expressions such as Eq. (40) have been proposed for flows with many scales (e.g., turbulent flows), and different values of a have been reported 141 —441. The fact that also the simple one-scale vortical flow investigated here displays such a behavior may be incidental. However, we believe that it can be due to physical reasons. Indeed, the large-scale features of the flow—for example, the absence of open channels (like for the shear flow)— can be more important than the detailed multiscale properties of the flow [37]. [Pg.537]

One of the advantages of the state-specific calculation of I mchf is that this wavefunction accounts in an efficient way for the self-consistently adjusting major correlations that contribute to localization, including a few that incorporate parts of the open-channel continuous spectrum, which we have named the "open-channel-like" (OCL) configurations [56,77]—see below. [Pg.227]

Current Meters. Various vane designs have been adapted for open-channel flow measurement. The rotating element is partially immersed and rotates rather like a water wheel. Operation is similar to that of vane anemometers. [Pg.63]

G -protein-coupled receptors are often located on the presynaptic plasma membrane where they inhibit neurotransmitter release by reducing the opening of Ca2+ channels like inactivation and breakdown of the neurotransmitter by enzymes, this contributes to the neuron s ability to produce a sharply timed signal. An a2 receptor located on the presynaptic membrane of a noradrenaline-containing neuron is called an autoreceptor but, if located on any other type of presynaptic neuronal membrane (e.g., a 5-HT neuron), then it is referred to as a heteroreceptor (Langer, 1997). Autoreceptors are also located on the soma (cell body) and dendrites of the neuron for example, somatodendritic 5-HTia receptors reduce the electrical activity of 5-HT neurons. [Pg.23]

There are three broad categories of materials that have been utilized in this endeavor. In the first, even in fully stoichiometric compounds, the ionic conductivity is high enough to be useful in devices because the cation or anion substructure is mobile and behaves rather like a liquid phase trapped in the solid matrix. A second group have structural features such as open channels that allow easy ion transport. In the third group the ionic conductivity is low and must be increased by the addition of defects, typically impurities. These defects are responsible for the enhancement of ionic transport. [Pg.252]

The flow of thin liquid films in channels and columns has also served as the basis of fundamental studies of wave motion (M7), the effects of wall roughness in open-channel flow (R4), the effects of surface-active materials (T9-T12), and the like. [Pg.152]

This equation is cubic in liquid depth. Below a minimum value of Ip there are no real positive roots above the minimum value there are two positive real roots. At this minimum value of lp the flow is critical that is, Fr = 1, V= rsh, and lp = (3/2)h. Near critical flow conditions, wave motion and sudden depth changes called hydraulic jumps are likely. Chow (Open Channel Hydraulics, McGraw-Hill, New York, 1959) discusses the numerous surface profile shapes which may exist in nonuniform open channel flows. [Pg.13]

Figure 7.14 Depth profiles of the 3-to-2 photon ratio for plain silica Xerogel and versions that include tantalum (blue upward triangles) or iron (green downward triangles). In the plain and tantalum case, positronium can move far through the open sponge like network of channels. This is reduced dramatically for the case of embedded iron. The line stems from a fit to extract the escape depth of 880 nm. Figure 7.14 Depth profiles of the 3-to-2 photon ratio for plain silica Xerogel and versions that include tantalum (blue upward triangles) or iron (green downward triangles). In the plain and tantalum case, positronium can move far through the open sponge like network of channels. This is reduced dramatically for the case of embedded iron. The line stems from a fit to extract the escape depth of 880 nm.
Like diffusion, ionic conduction is a thermally activated process. Low activation barriers are, therefore, achieved in the same manner. Geometric features, such as open channels, result in larger diffusivities (easier ion movement) because this lowers the magnitude of the AH terms in Eqs. 6.38 and 6.39. For example, in /3 alumina, the sodium ions are located in sparsely populated layers positioned between spinel blocks. Accordingly, they diffuse through these channels easily owing to the large number of vacancies present. [Pg.281]

Venturi flume—An open-channel measuring device with a longitudinal section that is shaped like a venturi meter. [Pg.222]

When modern industrialization started in the 19th century, many people migrated from the agricultural area to the big cities. Public hygiene became a major problem. Human excrement and waste was discharged into open channels, rivers, and lakes. The pollution was disastrous and hygiene-related epidemic diseases, like cholera and typhus, occurred frequently. Therefore, it was an important step forward when public water collection systems and treatment plants were introduced at the end of the 19th century. [Pg.323]

Several conclusions can be drawn from Eqs. (76) and (77). First, the influence of fluctuations is the largest when the number of open channels u is of the order of unity, because then the distribution Q k) is the broadest. Second, the effect of a broad distribution of widths is to decrease the observed pressure dependent rate constant as compared to the delta function-like distribution, assumed by statistical theories [288]. The reason is that broad distributions favor small decay rates and the overall dissociation slows down. This trend, pronounced in the fall-of region, was clearly seen in a recent study of thermal rate constants in the unimolecular dissociation of HOCl [399]. The extremely broad distribution of resonances in HOCl caused a decrease by a factor of two in the pressure-dependent rate, as compared to the RRKM predictions. The best chances to see the influence of the quantum mechanical fluctuations on unimolecular rate constants certainly have studies performed close to the dissociation threshold, i.e. at low collision temperatures, because there the distribution of rates is the broadest. [Pg.230]

Hollow Fiber. Hollow-hbers are open channel products however, due to their small fiber diameters, they do not require the high-energy consumption of tubular membrane products. Hollow fibers are self-supported they do not require additional support substrates like flat sheet membranes do. Figure 14.6 shows a schematic of a hoUow-fiber module. [Pg.415]


See other pages where Open-channel-like is mentioned: [Pg.815]    [Pg.1045]    [Pg.1309]    [Pg.102]    [Pg.289]    [Pg.360]    [Pg.95]    [Pg.364]    [Pg.13]    [Pg.329]    [Pg.145]    [Pg.432]    [Pg.208]    [Pg.403]    [Pg.541]    [Pg.1331]    [Pg.442]    [Pg.487]    [Pg.124]    [Pg.223]    [Pg.14]    [Pg.6]    [Pg.370]    [Pg.371]    [Pg.35]    [Pg.79]    [Pg.227]    [Pg.815]    [Pg.1045]    [Pg.1309]    [Pg.464]    [Pg.279]    [Pg.155]    [Pg.685]    [Pg.341]    [Pg.48]    [Pg.242]   
See also in sourсe #XX -- [ Pg.227 ]




SEARCH



Open channel

© 2024 chempedia.info