Composites homogeneous

The above discussion holds for dispersion by atmospheric turbulence. In addition, a momentum release of fuel sometimes generates its own turbulence, e.g., when a fuel is released at high pressure in the form of a high-intensity turbulent jet. Fuel mixes rapidly with air within the jet. Large-scale eddy structures near the edges of the jet entrain surrounding air. Compositional homogeneity, in such cases, can be expected only downstream toward the jet s centerline. 

Scanning patterns and many analytical data obtained by electron-microprobe analyzer reveal that most stannoidite grains are compositionally homogeneous. There is... 

Mizuta, T. (1988) Compositional homogenization of sphalerite in hydrothermal ore deposits of Japan by post-depositional diffusion processes with particular reference to metamorphosed Besshi-type deposits. Mining Geology, 38, 263-278. 

PBd-b-PI-b-PCHD tetrablock quarterpolymers. In a few cases chain transfer or termination reactions led to the presence of a small amount of PCHD homopolymer. In general, detailed characterization revealed that narrow molecular weight distribution products with high chemical and compositional homogeneity were obtained. 

Anionic polymerization techniques were also critical for the synthesis of a model cyclic triblock terpolymer [cyclic(S-fo-I-fr-MMA)] [196]. The linear cctw-amino acid precursor S-fr-I-fr-MMA was synthesized by the sequential anionic polymerization of St, I and MMA with 2,2,5,5-tetramethyl-l-(3-lithiopropyl)-l-aza-2,5-disilacyclopentane as the initiator and amine generator, and 4-bromo-l,l,l-trimethoxybutane as a terminator and carboxylic acid generator. Characterization studies of the intermediate materials as well as of the final cyclic terpolymer revealed high molecular and compositional homogeneity. Additional proof for the formation of the cyclic structure was provided by the lower intrinsic viscosity found for the cyclic terpolymer compared to that of the precursor. 

Fig. 29. CO oxidation at 240°C over Pd-Rh alloy films as a function of apparent surface composition homogeneous alloys and pure metals ( ) alloys showing phase separation (3) (34).

This section presents a classification of conversion concepts (read section 0), described in the literature on PBC, for example, fuel-bed mode (batch or continuous) and fuel-bed configuration (cocurrent, countercurrent, crosscurrent). Some new conversion concepts, namely fuel-bed movement (fixed, moving and mixed) and fuel-bed composition (homogeneous, heterogeneous), are introduced by these authors, which makes this an extended classification compared with earlier classifications in literature [8,9,10,11], The classification is made in the context of the three-step model. The three-step model, see Figure 14 below, is a system theory, which places the theory of thermochemical conversion of solid fuels into the context of PBC. 

The classification is based on the different conversion concepts cited in the literature, such as fuel-bed mode (batch and continuous), fuel-bed configuration (cocurrent, countercurrent, and crosscurrent), and some new concepts presented by the author, such as fuel-bed movement (fixed, moving, and mixed) and fuel-bed composition (homogeneous and heterogeneuos). The classification resulted in 18 types of updraft conversion systems, according to Figure 32. Some of them are more or less hypothetical, while others are found in practice, see section B 3.4 below. 

According to the three-step model, proposed by the authors, a PBCS can be divided into three subsystems, namely a conversion system, combustion system, and boiler system. It is in the conversion system that the thermochemical conversion of the solid fuel takes place. The conversion system can be designed according to several conversion concepts. The conversion concept can be classified with respect to fuel-bed mode (batch and continuous), fuel-bed configuration (countercurrent, cocurrent and crosscurrent), fuel-bed composition (homogeneous and heterogeneous), and fuel-bed movement (fixed, moving and mixed). 

The light scattering equation for molecular weight-heterodisperse samples which are compositionally homogeneous simplifies if dn/dc is constant for all species ... 

For copolymers, the above development shows that LALLS molecular weight measurements can be carried out in several solvents in order to check for compositional polydispersity. lymers which are compositionally homogeneous will give a which is independent of solvent identity. 

K Kawakami, Y Nishihara, K Hirano. Compositional homogeneity of liposomal membranes investigated by capillary electrophoresis. J Coll Interface Sci 206 177-180, 1998. 

Compositional homogeneity may strongly impact the observed properties of bulk material. Often the fact that Tc is a sensitive function of composition (the maximum Tc for BaPb1 xBixOs is observed at 13K (13) for x = 0.25, and a Tc of 34K is found for x =. 6 in Ba K BiOg (11)) means that the width of the resistive transition can be used to determine the uniformity of the product. Use of the resistive Tc onset to characterize these solid solutions, especially in bulk form can lead to errors due to stoichiometric nonuniformity. The results of Tomeno and Ando (50) who have reported that Tc remains constant at 29K for x values from 0.28 to 0.44 in Ba RbjjBiOg, are... 

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