Intrusion phenomena

A main function of geotextile-geonet composite (Fig. 18.2(a)) is drainage these composites are always installed under a confined loading system. When a geotextile-geonet composite is under load, the transmissivity (horizontal water permeability) is decreased by intrusion phenomena, especially needlepunched nonwoven geotextiles. 

Sleepiness in narcolepsy has also been considered a subjective phenomenon associated with the instability of boundaries between behavioral states and the constant intrusion of sleep episodes into wakefulness. Under baseline conditions, 0X2R, orexin , and orexin/ataxin-3 transgenic mice have normal amounts of wakefulness and non-REM sleep during the light and dark phases and over 24 h (Chemelli et al, 1999 Hara et al, 2001 Mochizuki et al, 2004 Willie... 

Although a number of methods are available to characterize the interstitial voids of a solid, the most useful of these is mercury intrusion porosimetry [52], This method is widely used to determine the pore-size distribution of a porous material, and the void size of tablets and compacts. The method is based on the capillary rise phenomenon, in which excess pressure is required to force a nonwetting liquid into a narrow volume. 

Houcine et al. (64) used a non-intrusive laser-induced fluorescence method to study the mechanisms of mixing in a 20 dm CSTR with removable baffles, a conical bottom, a mechanical stirrer, and two incoming liquid jet streams. Under certain conditions, they observed an interaction between the flow induced by the stirrer and the incoming jets, which led to oscillations of the jet stream with a period of several seconds and corresponding switching of the recirculation flow between several metastable macroscopic patterns. These jet feedstream oscillations or intermittencies could strongly influence the kinetics of fast reactions, such as precipitation. The authors used dimensional analysis to demonstrate that the intermittence phenomenon would be less problematic in larger CSTRs. 

Figure 2 shows the cumulative pore volume vs. pore radius for AC-ref SC-100 and SC-155 obtained by mercury intrusion technique. The curve corresponding to AC-ref shows a wide pore radius distribution instead, the curves assigned to SC-100 and SC-155 showed sharpened zones with maximum slope in 459A and 524A respectively, denoting a small increase of these values with the increase of the synthesis temperature. This phenomenon is probably produced by the growing of the big pores of the silica network at the expense of the... 

The starting point of a number of theoretical studies of packed catalytic reactors, where an exothermic reaction is carried out, is an analysis of heat and mass transfer in a single porous catalyst since such system is obviously more conductive to reasonable, analytical or numerical treatment. As can be expected the mutual interaction of transport effects and chemical kinetics may give rise to multiple steady states and oscillatory behavior as well. Research on multiplicity in catalysis has been strongly influenced by the classic paper by Weisz and Hicks (5) predicting occurrence of multiple steady states caused by intrapellet heat and mass intrusions alone. The literature abounds with theoretical analysis of various aspects of this phenomenon however, there is a dearth of reported experiments in this area. Later the possiblity of oscillatory activity has been reported (6). 

Recently microporous and mesoporous materials were found to be particularly suitable for a new type of applications in the mechanical field. This paper reports experimental features about the dissipative forced intrusion of water in highly hydrophobic mesoporous materials this phenomenon can be used to develop a new type of dampers and/or actuators. Silica-based materials behavior was investigated. Among them, MCM-41 exhibits original and interesting properties towards the potential developments of dampers and appears to be of great interest for the comprehension of energy dissipation mechanisms. 

When plasma polymers of hydrophilic monomers were deposited or the surface of LDPE grafted with hydrophilic poly(acrylic acid), the dielectric breakdown occurred in a very short time. These observations indicate that hydrophilic sites act as the gate for salt intrusion. Since the bulk properties of LDPE are believed to be unchanged with these surface modifications, the quick failure can be interpreted as the consequence of an interfacial phenomenon. The population of the potential salt intrusion sites is a very important factor that ultimately determines the breakdown of the insulation occurring in the presence of salt and electrical stress. 

In most experimental devices, the main problem is to eliminate the different sources of error. For pressure drop measurements, the pressure sensors must not be intrusive and interfere with the physical phenomenon. In most pubhshed works, the pressure sensors are added to the circuit and the fitting itself can create a singular pressure loss. Two experiments are presented. The first one has a rectangular channel whose hydraulic diameter varies from 100 pm to 1 mm with pressure sensors on either side of the test channel and includes entrance effects. The second one whose hydrauhc diameter is 7.1 pm has the pressure taps far from the inlet and outlet to eliminate entrance and exit effects. 

In other installations, there might be a gap between the foam and the required thermal barrier, thus permitting air intrusion. The phenomenon of decreasing R-value has presented the industry with a dilemma. What is the proper statement to make about the thermal resistance of one s rigid polyurethane foam insulation The lower the R-value statement you make, the less competitive your product will be. In the past, it has been difficult to advertise the aged R-values when your competition advertises only the initial R-values. 

The thermocline was ventilated in the NSCS, which was accompanied by the occurrence of potential vorticity with a specific circulation pattern. The thermocline ventilation is a seasonal phenomenon in the SCS actually. The potential vorticity in winter has a high value center and its distribution looks like a thin and fiat ellipsoid. Around the edge of this center, a horizontal circulation movement can be tracked. Water subducted into a thermocline from the mixed layer moves southward in the path of the cyclone along the edge of a seasonal potential vorticity pool. Research shows that signals in terms of the monthly temperature increment seem to come from the intrusion of the Kuroshio into the SCS. These show that seasonal variation in the SCS can deeply effect the thermocline. Thus, a study of the SCS upper circulation should include thermocline dynamics. Moreover, research into the dynamics of the thermocline and the mixed layer can help interpret the seasonal variation in the SCS circulation. 

This phenomenon is well known in fluid mechanics (Leal 1980) and was applied by Simkin (1967) to the intrasion of the mafic magma of dikes on the Isle of Skye in Scotland and by Upton and Wadsworth (1967) to the intrusion of a small sill on the volcano Piton des Neiges on Reunion. The textures of igneous rocks that result from flow differentiaton of mafic magma have been described by Marsh (1996a, b). 

The layering of differentiated mafic intrusions is an important phenomenon because the layers are a record of processes that occurred within the magma chamber, such as ... 

It is, however, fimdamental to point out that the total volume variation recorded by mercury porosimetry is a true measure of the material pore volume, whether the phenomenon is due to intrusion or densification. Except for rare materials with a large micropore volume, the specific volume measmed by mercury porosimetry is equal to the difference... 

Moreover, after completion of an intrusion-extrusion cycle some portion of mereury is always retained by the sample (pore entrapment) avoiding loop elosing. This phenomenon usually ceases after the second pressurization-depressurization run. 

Diffusion Media Channel Intrusion Figure 6.59 illustrates the phenomenon of DM tenting, or sagging into gas flow channels. This phenomenon occurs mostly with flexible cloth DM. The result is a lack of contact with the catalyst layer under the channel and excessive pressure drop in the affected channel. In large stacks this can cause severe flow maldistribution effects and the gap created can serve as a liquid pooling location under the DM. This is reversible in principle by replacing the DM in the affected fuel cell. 

Mercury pycnometry experiments allowed to explain these discrepancies by revealing a strong swelling of the CSOs especially in nitrogen. The phenomenon was first strictly established for both ores by comparing the mercury intrusion curves before and after treatment at 700 C in nitrogen the results are given in table 2. 

Ink-bottle effect The main criticism of the MIP technique is the fact that MIP does not measure pore size but pore entry size. This phenomenon, known as the ink-bottle effect, leads to an overestimation of small pores and an underestimation of big pores (Diamond 2000 Moro and Bohni 2002). More simply said, if the only path towards a big pore is a smaller one, the volume of the big cavity will be evaluated at the small pore intrusion pressure. The main evidence of this phenomenon is that not all the mercury intruded in the sample can exit when the pressure is subsequently decreased and at the end of MIP experiments, some mercury remains entrapped in the sample (Van Brakel et al. 1981). Figure 9.11 shows an example of intrusion and extrusion curves when measuring mature cement samples. In the... 

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