Hole, spherical

Four volumetric defects are also included a spherical cavity, a sphere of a different material, a spheroidal cavity and a cylinderical cavity (a side-drilled hole). Except for the spheroid, the scattering problems are solved exactly by separation-of-variables. The spheroid (a cigar- or oblate-shaped defect) is solved by the null field approach and this limits the radio between the two axes to be smaller than five. 

Mephisto is devoted to predict the ultrasonic scans (A,B or C-scans) for a priori knowledge of the piece and the defects within. In the present version Mephisto only deals with homogeneous isotropic materials. The piece under test can be planar, cylindrical or have a more complex geometry. The defects can be either planar (one or several facets), or volumetric (spherical voids, side drilled holes, flat or round bottom holes). 

As any conventional probe, acoustic beam pattern of ultrasound array probes can be characterized either in water tank with reflector tip, hydrophone receiver, or using steel blocks with side-drilled holes or spherical holes, etc. Nevertheless, in case of longitudinal waves probes, we prefer acoustic beam evaluation in water tank because of the great versatility of equipment. Also, the use of an hydrophone receiver, when it is possible, yields a great sensitivity and a large signal to noise ratio. 

Figure 2.6 Model of a particle P, a hole H, and the bottleneck between them in a liquid of spherical molecules.

The light ( and heavy (B) hole masses are the spherical average values defined in text. 

A spherical preventer contains a packing element that seals the space around a drillpipe. This preventer is not designed to shut off the well when the drillpipe is out of the hole, although it allows stripping operations and some pipe rotation. Hydril Corporation, Shaffer and other manufacturers provide several models with different packing system designs for specific types of service. The ram-type preventer seals the annulus around the drillpipe however, each size of ram is designated for only one size of drillpipe. In other words, the preventer with 5-in. pipe rams can provide a seal only on 5-in. drillpipe. The preventer with blind rams is used to shut in the well if the pipe is not in the hole. If this type of preventer is activated with the pipe in the hole, the pipe can be cut. 

The best products have smooth, natural curves and drawn sections that are spherical or nearly so in shape. Their walls will be more uniform, they will be more rigid, their surfaces will be less apt to show tool marks, and their tooling and molds will be lower in cost. Notches or square holes should be avoided when punching formed products. Round holes are preferred to oval ones for minimizing stress buildup. 

Further modification of the above nanostructures is useful for obtaining new functional materials. Thirdly, we apply the dopant-induced laser ablation technique to site-selectively doped thin diblock copolymer films with spheres (sea-island), cylinders (hole-network), and wormlike structures on the nanoscale [19, 20]. When the dye-doped component parts are ablated away by laser light, the films are modified selectively. Concerning the laser ablation of diblock copolymer films, Lengl et al. carried out the excimer laser ablation of diblock copolymer monolayer films, forming spherical micelles loaded with an Au salt to obtain metallic Au nanodots [21]. They used the laser ablation to remove the polymer matrix. In our experiment, however, the laser ablation is used to remove one component of block copolymers. Thereby, we can expect to obtain new functional materials with novel nanostmctures. 

In order to derive an expression for the interaction parameter T on the basis of elasticity theory, the elastic energy of a single sphere of volume F( is considered which is embedded in a spherical hole of volume Fq in the elastic medium ... 

PALS is based on the injection of positrons into investigated sample and measurement of their lifetimes before annihilation with the electrons in the sample. After entering the sample, positron thermalizes in very short time, approx. 10"12 s, and in process of diffusion it can either directly annihilate with an electron in the sample or form positronium (para-positronium, p-Ps or orto-positronium, o-Ps, with vacuum lifetimes of 125 ps and 142 ns, respectively) if available space permits. In the porous materials, such as zeolites or their gel precursors, ort/zo-positronium can be localized in the pore and have interactions with the electrons on the pore surface leading to annihilation in two gamma rays in pick-off process, with the lifetime which depends on the pore size. In the simple quantum mechanical model of spherical holes, developed by Tao and Eldrup [18,19], these pick-off lifetimes, up to approx. 10 ns, can be connected with the hole size by the relation ... 

Show that for a spherical storage vessel containing liquid at an initial height ha the time for the liquid to drain from a hole in the bottom of the sphere is given by... 

Emission spectra have been recorded for electron injection into Au and Ag spherical electrodes and hole injection into Au(lll) planar electrodes. These processes were brought about in solutions of acetonitrile containing tetrabutylammonium hexafluoro-phosphate (TBAHP), using the trans-stilbene radical anion as the electron injector and the thianthrene radical cation as hole injector. The spectrum for the hole injection process into planar Au(lll) electrodes has been resolved into the P S-polarised components of the emitted light. A comparison of the spectral distribution of emitted light for the above electron injection process, occurring at both Au and Ag... 

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