Geometry parameters testing

The viscoelastic parameters are generally measured by dynamic oscillatory measurements. Apparatus of three different configurations can be used cone and plate, parallel plates, or concentric cylinders. In the case of cone and plate geometry, the test material is contained between a cone and a plate with the angle between cone and plate being small (<4°). The bottom member undergoes forced harmonic oscillations about its axis and this motion is transmitted through the test material to the top member, the motion of which is constrained by a torsion bar. The relevant measurements are the amplitude ratio of the motions of the two members and the associated phase lag. From this information it is relatively simple to determine G and G". 

Parameter Indenter geometry/ material Test force/ indentation depth Definition Special requirements/aspects... 

Third, for all liquid temperatures and for both pressurant gases, bubble point pressure does not scale with the mesh of the screen. This is the most complex trend of the original five parameters tested. The second finest 450 x 2750 mesh produced the highest bubble points, for both GHe and GH2. The 510 x 3600 mesh outperformed the 325 x 2300 mesh at LH2 temperatures, but the 325 x 2300 yielded higher pressures in room temperature liquids. The reason for this crossover in performance is due to the temperature dependence of the screen pore diameter and geometry of the actual L/V interface at breakdown, as mentioned previously. The 510 screen has the largest gain at LH2 temperatures over the room temperature bubble point. 

An ASTM draft standard test method has been developed mid readied for full-consensus ballot to determine the flexural strength of composite tubes subjected to pure bending. Numerical modeling mid empirical tests of composite tubes provided validation of the parameters specified in the test metiiod. The draft standard addresses the following experimental issues - test specimen geometries/preparation, test fixtures, test equipment, interferences, testing modes/procedures, data collection, calculations, reporting requirements, precision/bias. 

In contrast to a direct injection of dc or ac currents in the sample to be tested, the induction of eddy currents by an external excitation coil generates a locally limited current distribution. Since no electrical connection to the sample is required, eddy current NDE is easier to use from a practical point of view, however, the choice of the optimum measurement parameters, like e.g. the excitation frequency, is more critical. Furthermore, the calculation of the current flow in the sample from the measured field distribution tends to be more difficult than in case of a direct current injection. A homogenous field distribution produced by e.g. direct current injection or a sheet inducer [1] allows one to estimate more easily the defect geometry. However, for the detection of technically relevant cracks, these methods do not seem to be easily applicable and sensitive enough, especially in the case of deep lying and small cracks. 

The sensibility to defects and other testing parameters of pieces can be modified by the geometry of the piece to be controlled and the conception of the probe. It is sufficient to set the direction of circulation of eddy currents, regulate the magnetic field intensity and choose the coil of the appropriate size. 

Accidentially, one of the drills (core B2, Fig. 6) hit a duct. The depth of the duct was 15cm with a diameter of 3cm. According to these parameters and the geometry, which former studies [Ref 1] concluded, the dectection of a defect (here the duct) under these conditions would be possible if at least one dimension of the defect exceeds 4cm. Since the duct s diameter was only 3 cm, whereas the parameter of the testing-system was 4cm, possibly more than one drill would be needed to hit a duct. 

If all nuclei are assigned and the spectral parameters for the conformational analysis are extracted, a conformation is calculated - usually by distance geometry (DG) or restrained molecular dynamics calculations (rMD). A test for the quality of the conformation, obtained using the experimental restraints, is its stability in a free MD run, i.e. an MD without experimental restraints. In this case, explicit solvents have to be used in the MD calculation. An indication of more than one conformation in fast equilibrium can be found if only parts of the final structure are in agreement with experimental data [3]. Relaxation data and heteronuclear NOEs can also be used to elucidate internal dynamics, but this is beyond the scope of this article. 

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