Main purpose of this paper is to analyse the forced vibration prevention system with positive or negative damping by damped dynamic absorber. The cases treated in are: case I (the alternative exciting force a constant magnitude acting on mass main system), II force, which proportional square its frequency, and III displacement given foundation It explained how spring factor absorber are desirably optimized make effect minimum. optimum values above convenient empirical formulae.

Abstract We propose a new method to compute elastic properties of rocks from computed tomography (CT) images. A CT volume captures X‐ray attenuation, which is scaled in number unit. Our improves an existing segmentation‐less where the directly converted property arrays without using segmentation. drawback that it typically requires scan physical targets known density along with sample. Targets map into petrophysical by comparing numbers sample those targets. introduce workflow no longer but...

Micro computed tomography (μCT) is an effective way to obtain rock digital models that can be used, along with physics (DRP), calculate properties. However, DRP has yielded mixed success are in part due limitations and uncertainty introduced by the segmentation processing method. Lately, segmentation-less been put forward potentially enabling become avenue inexpensively Ideally, could applied infinite number of samples such as drill cuttings. Here we present investigation about medium...

Digital rock physics (DRP) aims at estimating physical properties from computed-tomography (CT) imagery. DRP could improve our knowledge of subsurface without increasing laboratory testing that is time consuming, expensive and might damage the samples. Classic employs segmentation assigns to CT imagery voxels. However, obliterates information leading a loss precision in final result. Segmentation quality improves by scanning sample sub-micrometric resolution, but this leads trade-off: volume...

We demonstrate that the static elastic properties of a carbonate sample, comprised dolomite and calcite, could be accurately predicted by Digital Rock Physics (DRP), non-invasive testing method for simulating laboratory measurements. present state-of-the-art algorithm uses X-ray Computed Tomography (CT) imagery to compute lacustrine rudstone sample. The high-resolution CT-images provide digital sample is used analyzing microstructures performing quasi-static compression numerical...

Describing physical properties of reservoir rocks is great interest. Lab testing can be expensive, and may not have the desired spatial sampling for long cores. Here, we describe a hand sample carbonate rock comprised calcite dolomite. We use digital physics to numerically estimate how density, porosity, electrical conductivity change along across bedding (vertically laterally). This higher than possible with standard laboratory methods such as core plug or whole analysis. Our models were...

Digital rock physics (DRP) is used to estimate physical properties of rocks by means digital models. Conventional requires very high resolution images, as grains and pores need be well resolved in order assign each voxel the an endmember. Using targeted method, which does not require segmentation, voxels that capture a mixture pore grain are assigned effective medium theory. The therefore, resolving individual boundaries, lower scanning possible. Here we show results segmentation-less DRP...

This paper treats analytically the vibration prevention effect of Houde damper which is attached to a main system with positive or negative damping. Analyses about this type been done in past only cases without In paper, analyses are both case damping, that self-excited system, and damping subjected various alternate disturbing external forces. It shown better can be obtained each case, if optimum value given consideration system.

The present paper treats the bending theory of sandwich plates in which individual stiffness facings or core can not be neglected comparison with total plate as a whole. ln developing theory, it is assumed that deformation produced by are"irrotational " paralle1 plane surface. This assumption may be, however, considered reasonable, since tacitly accepted ordinary transverse shear neglected.The solution fundamental equations gives deflection and stress function, turn give stresses core....

The stress concentration during the loading and unloading processes of transient creep is investigated for a strip with semi circular notches by means photo‐viscoplasticity, using specimens celluloid at 65d̀C. relations between factor, geometries strips, time are derived from dependent variations isochromatic fringe orders. Such trends cannot be analysed ordinary photoplasticity in which effect not taken into account.

Elastic properties of rocks control the behavior seismic waves such as wave amplitudes and speeds. Usually, elastic are measured in laboratory. Unfortunately, some laboratory measurements invasive. Digital Rock Physics (DRP) provides an alternative solution by simulating common on computerized tomography images (CT-images) samples. However, evaluating using "segmentation-based DRP" is not accurate. Here, we propose automatic inversion-based algorithm to estimate monomineralic rocks. The...

Fractures control the transport and elastic properties of rocks. Typically, seismic methods are inefficient to determine fracture such as orientation distribution. An alternative approach assess includes analysis non-elastic response waves, which is usually quantified through coefficient attenuation (1/Q). Previous studies have shown that fractures affect wave much more than speeds. Attenuation also enhanced when rocks partially saturated. At low-frequencies, in saturated rocks, primary...

Actual rocket bodies have a finite bending stiffness. Low stiffness reduces the pitching moment of body in comparison with case where is assumed to be rigid and this tendency becomes stronger as velocity increases. This paper treats single step gives an approximate equation righting movent. approximation expected also applicable multi-step rockets.

The representative elementary volume (REV) is the minimum sized subsample where a measured attribute of bulk media as whole. For sandstones, researchers have estimated that REV approximately between 5 and 11 times grain diameter. Here, we show accounting for properties from many samples smaller than can provide an accurate averaged property, although with some uncertainty. We demonstrate this by taking three dimensional model sandstone then analyzing various subsamples. begin X-ray computed...

This paper describes the analysis of a dynamic vibration absorber with absolute damping which acts on mass alone. The shows that effectiveness is greater than conventional absorber. Two conditions main system are considered for optimum tuning: has undamping or damping. In undamped system, tuning and formulated basis theory fixed points. damped values obtained through numerical to minimize two resonant amplitudes. results given by convenient empirical formulae. Also it explained effect...