Vibrational coarse structure

The resolution of 0.2 eV (1600 cm-1) of which XPS is typically capable is too low, in most cases, for even the vibrational coarse structure accompanying ionization to be observed. 

In a search for the defining structural parameter of a composite, the free volume of disperse system proved to be the most sound one from the physical standpoint Presumably, for disperse systems the free volume is a measure of the mobility of filler particles, just as for liquids it is a measure of the mobility of molecules. But as applied to highly-loaded coarse systems of the type solid particles — liquid — gas this notion requires a certain correction. In characterizing the structure of such specific systems as highly-loaded coarse composites, it should be noted that to prevent their settling and separation into layers under the action of vibration, the concentration of the finest filler fraction with the largest specific surface in dispersion medium should be the maximum possible. Because of this and also because of the small size of particles (20-40 pm), the fine fraction suspended in the dispersion medium practically does not participate in the formation of the composite skeleton, which consists of coarser particles. Therefore... 

Performance often is improved by appropriate pretreatment of the slurry with flocculants or other means. An operating practice that is receiving increased acceptance is the delaying of cake deposition by some mechanical means such as scraping, brushing, severe agitation, or vibration. In these ways most of the filtrate is expelled before the bulk of the cake is deposited. Moreover, when the cake is finally deposited from a thickened slurry, it does so with an open structure that allows rapid filtration. A similar factor is operative in belt or top feed drum filters in which the coarse particles drop out first and thus form the desirable open structure. A review of such methods of enhancement of filtration rates is by Svarovsky (1981). 

Both loose and dense soil structures are capable of supporting considerable static overburden loads with little or no distortion. However, loose soils with grain sizes in the coarse silt fine sand range are inherently metastable as shown by Terzaghi (1925). Shocks and vibrations readily cause movement of the particles to denser, more stable arrangements. Highly metastable, loose sediments are often produced by rapid deposition of silt and fine sand in quiet environments, such as delta fronts of large rivers. Many of the fine silt-sized... 

Vibroflotation is used to improve poor ground below foundation structures. The process may reduce settlement by more than 50%, and the shearing strength of treated soils is increased substantially. Vibrations of appropriate form can eliminate intergranular friction of coarse soils, so that those initially packed loosely can be converted into a dense state. A vibroflot is used to penetrate the coarse soil and can operate efficiently below the water table. The best results have been obtained in fairly coarse sands that contain little or no silt or clay, since these reduce the effectiveness of the vibroflot. 

The coarse grained models we have considered thus far are valuable for examining qualitative trends. However, in order to make comparisons directly with experimental data, more local structural details presumably need to be taken into account in the calculation of d>(k). A realistic way of incorporating monomer structure is through the rotational isomeric state approximation, successfully employed [16] by Flory and others to describe isolated polymer chains in a theta solvent. In this description the continuous rotational potentials are replaced by discrete rotational states corresponding to the lowest vibrational... 

According to several authors, the value of the average mortar intercept (AMI) should be equal to 3.5 mm for composites of continuous grading and manual compaction to ensure appropriate workability. When vibration of the fresh mix is applied, which is common practice at present, that value may be lower. Similar modification of that limit value is needed when very fine sand is used. A larger value of the AMI may indicate that the composite structure is not correct, but an additional amount of coarse aggregate would probably improve it. 

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