Multi-layered

Waterproofing, whether it has to do with protecting civil engineering structures or roofs or terraces. Poured asphalt, often placed in layers with kraft paper, oxidized bitumen or modified bitumen can be used, generally with copolymer. The modified bitumen are used for the making prefabricated multi-layer waterproofing composites. 

If gas export or disposal is a problem gas re-injection into the reservoir may be an alternative, although this implies additional compression facilities. Gas production may be reduced using well intervention methods similar to those described for reducing water cut, though in this case up-dip wells would be isolated to cut back gas influx. Many of the options discussed under water treatment for multi-layered reservoirs apply equally well to the gas case. 

In the Neural Spectrum Classifier (NSC) a multi-layer perceptron (MLP) has been used for classifying spectra. Although the MLP can perform feature extraction, an optional preprocessor was included for this purpose (see Figure 1). 

The performance of the classifier has been verified using a number of practical applications, such as civil engineering [3], inspection of aerospace composite structures, ball bearings and aircraft multi-layer structures. Here we present shortly some results, focusing on detection of disbonds in adhesively joint multi-layer aerospace structures using Fokker Bond Tester resonance instrument, details can be found in [1]. 

Fokker Bond Tester. An ultrasonic inspection technique commonly used for aircraft structures is based on ultrasonic spectroscopy [2]. Commercially available instruments (bond testers) used for this test operate on the principle of mechanical resonance in a multi-layer structure. A piezoelectric probe shown in Figure 3b, excited by a variable frequency sine signal is placed on the surface of the inspected structure. A frequency spectrum in the range of some tens of kHz to several MHz is acquired by the instrument, see Figure 3a. 

A resonance in the layered stracture occurs when echoes between two boundaries travel back and forth due to differences in acoustic impedances at the boundaries. For multi-layer structures a number of resonances can be observed depending on their geometry and condition. For each particular defect-free structure and given transducer we obtain a characteristic resonance pattern, an ultrasonic signature, which can be used as a reference. 

We have presented a neural network based spectrum classifier (NSC) aimed at ultrasonic resonance spectroscopy. The ultrasonic spectroscopy and the NSC has been evaluated in many industrial applications, such as concrete inspection, testing of aerospace composite structures, ball bearings, and aircraft multi-layer structures. The latter application has been presented in some detail. 

The model allows to perform thermal calculation of a multi-layer annular structure of a kiln body with a granular mixture-clinker, roasted inside it (Fig 1). 

The actuality of researches of multi-layer objects with high density of materials for airspace technics is substantiate by several firms. The distribution of the heavier in longerons and elements of the screw of the helicopter was determined with the help of RCT. In the filler made of graphite or rubbers the layers of heavier from leaden alloys and the air stratification 1 up to 5 mm wide are revealed with the ratio signal / noise more than 3, even at presence of an external steel cover. 

The new instrument introduced for inspection of multi-layer structures from polymeric and composite metals and materials in air-space industry and this is acoustic flaw detector AD-64M. The principle of its operation based on impedance and free vibration methods with further spectral processing of the obtained signal. 

A.STM.B764, Std. Methodfor Simultaneous Thickness and Electrochemical Potential determination of Individual Eayers in Multi-layer Mickel deposit (STEP test), American Society for Testing and Materials, Philadelphia, Pa., 1986. 

L.D. Bertholf et al.. Kinetic Energy Projectile Impact on Multi-Layered Targets Two-Dimensional Stress Wave Calculations, Prepared by Sandia National La-... 

Metallocene-catalysed very low density polyethylene (m-VLDPE) has become available with densities of as low as 0.903. This is of use for sealing layers of multi-layer films since sealing can commence at lower temperatures than with conventional materials such as LLDPE and EVA (see Section 11.6) with the polymer seal exhibiting both cold strength and hot tack strength. 

The earliest observations of carbon nanotubes with very small (nanometer) diameters [151, 158, 159] are shown in Fig. 14. Here we see results of high resolution transmission electron microscopy (TEM) measurements, providing evidence for m-long multi-layer carbon nanotubes, with cross-sections showing several concentric coaxial nanotubes and a hollow core. One nanotube has... 

The Back-Propagation Algorithm (BPA) is a supervised learning method for training ANNs, and is one of the most common forms of training techniques. It uses a gradient-descent optimization method, also referred to as the delta rule when applied to feedforward networks. A feedforward network that has employed the delta rule for training, is called a Multi-Layer Perceptron (MLP). 

From the point of view of solute interaction with the structure of the surface, it is now very complex indeed. In contrast to the less polar or dispersive solvents, the character of the interactive surface will be modified dramatically as the concentration of the polar solvent ranges from 0 to l%w/v. However, above l%w/v, the surface will be modified more subtly, allowing a more controlled adjustment of the interactive nature of the surface It would appear that multi-layer adsorption would also be feasible. For example, the second layer of ethyl acetate might have an absorbed layer of the dispersive solvent n-heptane on it. However, any subsequent solvent layers that may be generated will be situated further and further from the silica surface and are likely to be very weakly held and sparse in nature. Under such circumstances their presence, if in fact real, may have little impact on solute retention. 

Where there are multi-layers of solvent, the most polar is the solvent that interacts directly with the silica surface and, consequently, constitutes part of the first layer the second solvent covering the remainder of the surface. Depending on the concentration of the polar solvent, the next layer may be a second layer of the same polar solvent as in the case of ethyl acetate. If, however, the quantity of polar solvent is limited, then the second layer might consist of the less polar component of the solvent mixture. If the mobile phase consists of a ternary mixture of solvents, then the nature of the surface and the solute interactions with the surface can become very complex indeed. In general, the stronger the forces between the solute and the stationary phase itself, the more likely it is to interact by displacement even to the extent of displacing both layers of solvent (one of the alternative processes that is not depicted in Figure 11). Solutes that exhibit weaker forces with the stationary phase are more likely to interact with the surface by sorption. 

The main fluids of interest with plastics are oxygen and water vapour (for packaging applications) and CO2 (for carbonated drinks applications). Fig. 1.13 and Fig. 1.14 illustrate the type of behaviour exhibited by a range of plastics. In some cases it is necessary to use multiple layers of plastics because no single plastic offers the combination of price, permeation resistance, printability, etc. required for the application. When multi-layers are used, an overall permeation constant for the composite wall may be obtained from... 

It is becoming common practice to have the cross-section of a plastic moulding made up of several different materials. This may be done to provide a permeation barrier whilst retaining attractive economics by having a less expensive material making up the bulk of the cross-section. To perform stress analysis in such cases, it is often convenient to convert the cross-section into an equivalent section consisting of only one material. This new section will behave in exactly the same way as the multi-layer material when the loads are applied. A very common example of this type of situation is where a solid skin and a foamed core are moulded to provide a very efficient stiffness/weight ratio. This type of situation may be analysed as follows ... 

The main reason for producing multi-layer co-extruded films is to get materials with better barrier properties - particularly in regard to gas permeation. The following Table shows the effects which can be achieved. Data on permeability of plastics are also given in Figs 1.13 and 1.14. 

As the diameter of the catalyst particle is supposed to be close to that of the single-shell tubule[20], or to that of the inner tubule [8], the number of graphitic layers might depend on the flow rate of acetylene at the catalyst particle. The graphitic layers are supposed to be formed by the Cj units formed on the catalyst particle, exceeding those needed for the growth of the multi-shell tubule inner layer. This generalisation to multi-layer tubules is just a hypothesis, since we do not have any experimental proof yet. 

The remarkable stability of onion-like particles[15] suggests that single-shell graphitic molecules (giant fullerenes) containing thousands of atoms are unstable and would collapse to form multi-layer particles in this way the system is stabilized by the energy gain from the van der Waals interaction between shells [15,26,27],... 

Stephenson D. G., and Mitalas G. R Calculation of heat conduction transfer functions for multi-layer slabs. ASHRAE Transactions, vol. 77, part II, p. 117, 1971. 

In this review article we have tried to show that an analytical approach to the thermodynamics and the kinetics of adsorbates is not restricted to simple systems but can deal with rather complicated situations in a systematic approach, such as multi-site and multi-component systems with or without precursor-mediated adsorption and surface reconstruction, including multi-layers/subsurface species. This approach automatically ensures that such fundamental principles as detailed balance are implemented properly. 

L. Botz, Sz. Nyiredy and O. Shelter, The principles of long distance OPLC, a new multi-layer development technique , 7. Planar Chromatogr. 3 352-354 (1990). 

E. Tyihak, E. Mincsovics and T. J. Szekely, Oveipressured multi-layer chromatography , J. Chromatogr. 471 375-387 (1989). 

Structured Packing NOR-PAC Multi-layers P Hi Hi Lo Hi Ideal packing for... 

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