Diffraction loading

Blast wave (Overpressure and negative phase pressure relative to atmospheric condition) Diffraction loading—forces on a structure resulting from the direct and reflected overpressure... 

The pressure differential between the front and back faces will have its maximum value when the blast wave has not yet completely surrounded the structure, as in Figs. 7c, and d or g and h. Such a pressure differential will produce a lateral (or translational) force tending to cause the structure to deflect and thus move bodily, usually in the same direction as the blast wave. This force is known as the "diffraction loading" because it operates while the blast wave is being diffracted around the structure. 

Reference 7 gives explicit procedures for calculating diffracted loads on surfaces of box-shaped structures, and they will not be repeated here. But, we do reproduce several formulas for diffraction times from this reference. These are... 

The actual pressures on all faces of the structure are in excess of the ambient atmospheric pressure and will remain so, although decreasing steadily, until the positive phase of the blast wave has ended, thus the diffraction loading on a structure without openings is eventually replaced by an inwardly directed pressure. 

As these names imply, in a nuclear explosion, the former would be affected mainly by diffraction loading and the latter by drag loading. While it is true that... 

Nitrogen adsorption experiments showed a typical t)q5e I isotherm for activated carbon catalysts. For iron impregnated catalysts the specific surface area decreased fix>m 1088 m /g (0.5 wt% Fe ) to 1020 m /g (5.0 wt% Fe). No agglomerization of metal tin or tin oxide was observed from the SEM image of 5Fe-0.5Sn/AC catalyst (Fig. 1). In Fig. 2 iron oxides on the catalyst surface can be seen from the X-Ray diffractions. The peaks of tin or tin oxide cannot be investigated because the quantity of loaded tin is very small and the dispersion of tin particle is high on the support surface. 

The TEM images of 12 wt.% Co/MgO calcined at 873 K (Catalyst I) before and after reduction are shown in Fig. 1 (a) and (b), respectively. Although Co metal phase was detected in reduced Co/MgO by X-ray diffraction measurements (XRD) [7, 8], no Co metal particle was observed on both catalysts. EDS elemental analysis showed that primary particles contain both Mg and Co elements, whose concentrations were about the same as loaded amounts. Figure 2 shows TEM image of 12 wt.% Co/MgO calcined at 1173 K (Catalyst II). 

Samples with different loadings of rare earth and yttrium oxides on MS25 Si-Al were prepared and characterized. Figure 1 shows the x-ray diffraction spectra of a sample of 25% Nd203/Si-Al compared with the unmodified Si-Al. 

The pressures on the sides and roof of the structure build up to the incident overpressure as the blast wave traverses the structure. Traveling behind the blast wave front there is a short period of low pressure caused by a vortex formed at the front edge during the diffraction process (Figures A. 8c and A. 9c). After the vortex has passed, the pressure returns essentially to that in the incident blast wave. The air flow causes some reduction in the loading to the sides and roof, because the drag pressure has a negative value for these surfaces. 

At the present time the only online facility that we provide for analyzing the data is the display function, which provides graphical outputs tailored to the data in the diffraction data files. The user specifies the run number for the data he wishes to plot. The display program then loads the header from the appropriate data file and determines what kind of plot to display. The user can dump the resulting plot to the printer to provide a record of his experiment. The "revise file" function can be used to create auxiliary files for plotting selected features of the data. 

On the basis of a number of physico-chemical methods (Mossbauer spectroscopy, electron diffraction, EXAFS) the iron cores of naturally occurring haemosiderins isolated from various iron-loaded animals and man (horse, reindeer, birds and human old age) were consistently shown to have ferrihydrite-like iron cores similar to those of ferritin (Ward et ah, 1992, 2000). In marked contrast, in the tissues of patients with two pathogenic iron-loading syndromes, genetic haemochromatosis and thalassaemia, the haemosiderins isolated had predominantly amorphous ferric oxide and goethite cores, respectively (Dickson etah, 1988 Mann etah, 1988 ... 

Figure 5. Evolution of the main neutron diffraction peak intensity versus methane confined phase loading in AlP04-5 zeolite.

Similar neutron diffractogram modifications have been al-ready observed several time during our studies concerning the structural proper-ties of confined molecular species (D2, Ar, N2, Kr, CD4, C2D6) in Silicalite-I zeolite. But for such a MFI type of framework porosity, characterized by a two dimensional micropore network, the intensity of the diffraction peaks (101) and (020), observed at small wave vector Q (A1) values, vanishes completely when increasing the confined phase loading ( as shown on figure 6, for the Ar / Silicalite-I system Ld. = 68 % ). 

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