Displacement Path Research Articles

Comparison of 2-D speckle tracking and tissue Doppler imaging in an isolated rabbit heart model

Ultrasound strain imaging has been proposed to quantitatively assess myocardial contractility. Cross-correlation-based 2-D speckle tracking (ST) and auto-correlation-based tissue Doppler imaging (TDI) [often called Doppler tissue imaging (DTI)] are competitive ultrasound techniques for this application. Compared with 2-D ST, TDI, as a 1-D method, is sensitive to beam angle and suffers from low strain signal-to-noise ratio because a high pulse repetition frequency is required to avoid aliasing in velocity estimation. In addition, ST and TDI are fundamentally different in the way that physical parameters such as the mechanical strain are derived, resulting in different estimation accuracy and interpretation. In this study, we directly compared the accuracy of TDI and 2-D ST estimates of instantaneous axial normal strain and accumulated axial normal strain using a simulated heart. We then used an isolated rabbit heart model of acute ischemia produced by left descending anterior artery ligation to evaluate the performance of the two methods in detecting abnormal motion. Results showed that instantaneous axial normal strains derived using TDI (0.36% error) were less accurate with larger variance than those derived from 2-D ST (0.08% error) given the same spatial resolution. In addition to poorer accuracy, accumulated axial normal strain estimates derived using TDI suffered from bias, because the accumulation method for TDI cannot trace along the actual tissue displacement path. Finally, we demonstrated the advantage 2-D ST has over TDI to reduce dependency on beam angle for lesion detection by estimating strains based on the principal stretches and their corresponding principal axes.

Prediction of spatial displacement development

AbstractOne of the major shortcomings of two‐dimensional approaches for underground excavation design is the (mostly) inadequate modelling of the effects of the face advance. Although they may roughly estimate the evolution of the displacements towards their final value, none of the 2D solutions available so far provide information about the extent of the pre‐relaxation the ground has undergone. On the other hand, 3D calculations pose a much greater effort in modelling and evaluation, and can be conducted only by using numerical methods.The method presented in this paper is intended to narrow this gap, representing an easy‐to‐implement tool allowing fast assessment of displacement development for a circular cavity in a linearly elastic‐ideally plastic Mohr‐Coulomb material under hydrostatic loading. A numerical parametric study has been performed on a 3D model in FLAC3D. The parameters for the numerical simulations were chosen in such a way that they form a regular grid in a co‐ordinate system spanned by the friction angle and a non‐dimensional variable defined as the ratio between the depth of failure and the tunnel radius. Based on the displacement data obtained from numerical simulations, the respective fictitious support pressures have been back‐calculated for every face position, using the closed‐form solution developed by Feder & Arwanitakis. The back‐calculated curves of the fictitious support pressure, its dimensionless form λ (equivalent support pressure coefficient), defined as the ratio between the fictitious support pressure and the primary stress respectively, have been fitted with a slightly modified version of the function proposed by Sulem et al. The fitting process yields function shape parameters, allowing the establishment of three interpolation relationships. The knowledge of the shape parameters for an arbitrary set of mechanical parameters allows the calculation of the displacement path. The results have been verified on a set of ten 3D calculations with a random set of parameters and show very good agreement in all cases. In addition, the presented method is demonstrated through case histories.

Geometrically nonlinear analysis of functionally graded shells

The nonlinear response of functionally graded ceramic–metal shell panels under mechanical and thermal loading is studied. The nonlinear formulation is based on a modified version of Sander's nonlinear shell theory, in which the geometric nonlinearity takes the form of von Kármán strains. It is assumed that the material properties vary through the thickness according to a power-law distribution of the volume fraction of the constituents. The displacement field is expressed in terms of a set of mesh-free kernel particle functions. The bending stiffness is evaluated using a stabilized conforming nodal integration technique, and the shear and membrane terms are computed using a direct nodal integration to eliminate shear and membrane locking. The arc-length method, combined with the modified Newton–Raphson approach, is employed to trace the full load–displacement path. The characteristic of the displacement and the axial stress in panels under thermal and mechanical loading is investigated, and the effects of the volume fraction exponent, boundary conditions, and material properties on the nonlinear response of shell panels are also examined.

Effects of wettability and pore-level displacement on hydrocarbon trapping

We use a three-dimensional mixed-wet random network model representing Berea sandstone to extend our previous work on relative permeability hysteresis during water-alternating-gas (WAG) injection cycles [Suicmez, VS, Piri, M, Blunt, MJ, 2007, Pore-scale simulation of water alternate gas injection, Transport Porous Med 66(3), 259–86]. We compute the trapped hydrocarbon saturation for tertiary water-flooding, which is water injection into different initial gas saturations, S gi, established by secondary gas injection after primary drainage. Tertiary water-flooding is continued until all the gas and oil is trapped. We study four different wettability conditions: water-wet, weakly water-wet, weakly oil-wet and oil-wet. We demonstrate that the amounts of oil and gas that are trapped show surprising trends with wettability that cannot be captured using previously developed empirical trapping models. We show that the amount of oil that is trapped by water in the presence of gas increases as the medium becomes more oil-wet, which is opposite from that seen for two-phase flow. It is only through a careful analysis of displacement statistics and fluid configurations that these results can be explained. This illustrates the need to have detailed models of the displacement processes that represent the three-phase displacement physics as carefully as possible. Further work is needed to explore the full range of behavior as a function of wettability and displacement path.

Spectral and electro-chemical characterization of transition metal complexes of a modified [N6] macrocycle. A mimic to cyclic hexapeptide

The 16-membered modified [N6] macrocylic ligand (L), a mimic to cyclic, hexapeptide is reacted with MCl2 and MCl3 resulting in complexes with stoichiometrices [MLCl2] (M = Cr, Mn, Co, Ni, Cu), [MLCl3] (M = Pt, Pd) and [MLCl2]Cl (M = Fe, Ru). Its reactions with the precursors [M(Ph3P)2Cl2] (M = Co, Ni, Pt, Pd) follow a ligand displacement path affording the final products which do not contain coordinated Ph3P. Complexes have been characterized from results of elemental analyses, conductometric, magnetic susceptibility, i.r. and u.v.–vis (ligand field) spectral studies. Magnetic susceptibility and ligand field spectral data are consistent with a hexacoordinate geometry for Cr2+, Mn2+, Fe3+, Co2+, Ni2+ and Cu2+ and four coordinate square-planar geometry for Pt2+ and Pd2+. Molecular orbital computations using CSChem ultra MOPAC software for an optimized minimum energy plot of the structure shows that the ligand binds metal ions as a tetradentate (N,N,N,N) chelating agent. Cyclic voltammetric studies indicate formation of stable reversible or quasi-reversible redox couples in solutions, which corroborates a kinetic stability of these complexes in their variable oxidation states.

Beating the Standard Quantum Limit with Four-Entangled Photons

Precision measurements are important across all fields of science. In particular, optical phase measurements can be used to measure distance, position, displacement, acceleration, and optical path length. Quantum entanglement enables higher precision than would otherwise be possible. We demonstrated an optical phase measurement with an entangled four-photon interference visibility greater than the threshold to beat the standard quantum limit-the limit attainable without entanglement. These results open the way for new high-precision measurement applications.

Geometrically nonlinear analysis of cylindrical shells using the element-free kp-Ritz method

In this paper, the geometrically nonlinear analysis of cylindrical shells is carried out using the element-free kp-Ritz method. The first-order shear deformation shell theory, which can cater for both thin and relatively thick shells, is utilized in the present study. Meshfree kernel particle functions are employed to approximate the two-dimensional displacement field. The nonlinear equilibrium equations are formulated by applying the Ritz procedure to the energy functional of shells. The Newton–Raphson method and the arc length technique are used to determine the load–displacement path. To validate the accuracy and stability of this method, convergence studies based on the support size and number of nodes were performed. Comparisons were also made with the existing results available in the open literature, and good agreement is obtained.

The effects of bend–twist coupling on the post-buckling characteristics of composite laminated plates using semi-energy finite strip approach

In composite laminated plates various mechanical properties may be attained by changing the lay-up arrangement. The bent–twist coupling is one of the significant properties which dominate the mechanical performance of a laminated plate structure in large out-of-plane deformations. The effects of bend–twist coupling on the post-buckling behavior of composite laminated plates have been studied in this paper by implementing a finite strip approach based on the concept of a rigorous post-buckling solution for composite plates and plate structures, namely the semi-energy approach. All the plates are assumed to be symmetrically balanced laminates having uniform in-plane stiffness properties. As far as the out-of-plane stiffness properties are concerned, all the properties, except for the bend–twist coupling terms which are assumed to change from one laminate to another, are the same among different laminates. The orthotropic solutions have also been determined by precluding the bend–twist coupling terms. A comprehensive set of parametric studies have been carried out to investigate the effects of bend–twist coupling terms on the post-buckling load–displacement path, post-buckling deformations and stress distribution. The comparison between the results revealed markedly different behaviors among different laminates due to the bend–twist coupling effects. The outcome of the paper can help structural designers to have a better understanding of the effects of bend–twist coupling terms on the post-buckling behavior of laminated composite plates at the design stage.

Analysis of the lateral displacement and optical path difference in wide-field-of-view polarization interference imaging spectrometer

The mechanism of beam splitting and principle of wide-field-of-view compensation of modified Savart polariscope in the wide-field-of-view polarization interference imaging spectrometer (WPIIS) are analyzed and discussed. Formulas for the lateral displacement and optical path difference (OPD) produced by the modified Savart polariscope are derived by ray-tracing method. The theoretical and practical guidance is thereby provided for the study, design, modulation, experiment and engineering of the polarization interference imaging spectrometers and other birefringent Fourier-transform spectrometers based on Savart polariscopes.

小型三次元咬合力計の開発

The aim of this study was to develop a three-dimensional small occlusal force sensor which could be set up inside the crown of the tooth and measure both the three-dimensional occlusal force and the tooth displacement path during function at the same time in vivo. The measurement error of this occlusal force sensor was 11.9%, 8.7%, and 5.9% at maximum in the mesio-distal, bucco-lingual and colono-apical directions, respectively. The subject was a Japanese male who had good periodontal conditions and an acceptable centric occlusion. After this occlusal force sensor and tooth displacement transducer were set up at the upper left first molar, the three-dimensional occlusal force and the tooth displacement were measured simultaneously during clenching at the intercuspal position and biting a ready-made monoaxial occlusal force meter. During clenching at the intercuspal position, the tooth displaced toward the palato-disto-apical direction and this was almost the same direction in which the occlusal force acted. The difference between the values measured by this sensor and a ready-made monoaxial occlusal force meter was about 9.5% at maximum. This three-dimensional occlusal force sensor is able to reveal how occlusal force is diffused.

Przetwarzalnosc tworzyw fenolowych wyznaczana metoda BIP

Processing properties of phenol-formaldehyde plastics were determined using BIP plastometer, unmodified and modified by us (Fig. 1). Investigations of plastic processability were carried out for,,Polofen FF1WHG taking into consideration the following changeable parameters: temperature of plastometer mold (TBIP), water content in the plastic (f w ), diameter of plastometer die flow channel (d) and mass of plastic (m BIP ). The functions were obtained (Fig. 2) and two basic processability factors were determined based on them, namely maximal mass flow rate G maks. and standard holdup time (t WS ) of plastic in BIP plastometer mold. The values of the factors lower with increasing temperature T BIP of plastometer mold (Fig. 3) as a result of faster crosslinking reaction. In case of increase in water content in a plastic (Fig. 4) and in the diameter of plastometer die flow channel (Fig. 5) the relationships are inverse. The use in measurements the samples of bigger masses cause non-uniform flow of material because of non-uniform plastification (Fig. 6). Analyses of dependence of mass flow rate of plastic on press molding time (Fig. 7) as well as of dependence of displacement path of the plastometer punch during the press molding on this time (Fig. 8) allow to analyze the properties of the plastic studied in more details.

噛みしめ強度に伴う三次元こう合力と歯の変位の関係

This study evaluated the relationship between occlusal force and tooth displacement in function. The three-dimensional tooth displacement transducer Type M-3 was used to measure the tooth displacement path and a three-dimensional small occlusal force sensor was developed to detect the occlusal force. Subjects' teeth were the upper and lower first molars. The three-dimensional tooth displacement and occlusal force of the upper and lower first molars were measured at the same time during light and heavy clenching in vivo. The direction of the tooth displacement and that of the occlusal force of the upper first molar almost coincided and they were along the palato-apical direction. However, in the lower first molar, the direction of occlusal force was in the apical direction, and the tooth displacement path was along the lingual direction. There was no relationship between the direction of occlusal force and clenching intensity at the upper and lower first molars and no relationship was observed between the direction of tooth displacement and occlusal force at the lower first molar. However, the upper molars showed a tendency to move more in the palatal direction as the force increased. In the case of the upper first molar, the energy of force seemed to change with the distortion of the alveolar bone especially around the root surface. However, in the case of the lower first molar, the energy of this occlusal force might be absorbed by the deformation of the mandible.

Discrete element modelling of deep penetration in granular soils

This paper presents a numerical study on deep penetration mechanisms in granular materials with the focus on the effect of soil–penetrometer interface friction. A two-dimensional discrete element method has been used to carry out simulation of deep penetration tests on a granular ground that is under an amplified gravity with a K0 lateral stress boundary. The numerical results show that the deep penetration makes the soil near the penetrometer move in a complex displacement path, undergo an evident loading and unloading process, and a rotation of principal stresses as large as 180°. In addition, the penetration leads to significant changes in displacement and velocity fields as well as the magnitude and direction of stresses. In general, during the whole penetration process, the granular ground undergoes several kinds of failure mechanisms in sequence, and the soil of large deformation may reach a stress state slightly over the strength envelope obtained from conventional compression tests. Soil–penetrometer interface friction has clear effects on the actual penetration mechanisms. Copyright © 2005 John Wiley & Sons, Ltd.

Determination of Multidirectional p-y Curves for Soft Clays

Abstract The evaluation of performance of soil-pile-structure systems under seismic loading is one of the most complex problems in earthquake engineering. In the most common methodology, force-displacement curves are used to describe the nonlinear response of discrete soil springs connecting the piles to the “free-field” soil column using the concept of beam on nonlinear Winkler foundation. Although there is a great interest and on-going research to characterize the multi-directional “free-field” soil response, there is a lack of information and experimental data to formulate p-y curves in multi-directional loading conditions. A new testing device was designed and constructed to obtain high quality data to calibrate numerical tools used to evaluate the seismic performance of structures supported on deep foundations in soft clay. A suite of different ground displacement path scenarios observed during recent earthquakes was simulated to assess the effect of displacement history on measured p-y response.

Quantification of Displacement Mechanisms in Multicomponent Gasfloods

Summary Local displacement efficiency in gasfloods depends strongly on the minimum miscibility pressure (MMP) or minimum miscibility enrichment (MME). The values for these design parameters depend in turn on the displacement mechanisms: vaporizing, condensing, or a combination of the two known as a condensing/vaporizing (CV) drive. Characterization of the displacement mechanism, however, is currently limited to these broad categories, with little reference to the degree to which a CV displacement is condensing or vaporizing. This "discrete" classification approach can result in significant confusion in the interpretation and comparison of various miscible gasfloods. The focus of this paper, therefore, is to present a method to quantify in a continuous way the fraction of a multicomponent gasflood that is vaporizing or condensing as the pressure or gas enrichment is increased. The approach relies on finding key tie lines for a dispersionfree 1D displacement using method of characteristic theory (MOC). We quantify the displacement mechanism for any number of oil or gas components by calculating the displacement path lengths along ruled surfaces bounded by these key tie lines. We show how to determine the displacement mechanism along each of these ruled surfaces by the calculation and comparison of the key tie-line lengths. Several multicomponent fluid characterizations are considered, including a 12-component enriched-gasflood and a 13-component CO2 flood. The results show that as the pressure or enrichment is increased, condensation occurs at the expense of vaporization. We also show by numerical simulations that the sensitivity of the local displacement efficiency to dispersion depends on the condensing fraction of the displacement. We show that the trends in displacement efficiency sensitivity to dispersion oppose previously published results, which showed that vaporizing displacements are more sensitive to dispersion than condensing ones. The differing trends are likely the result of improper and discrete determination of the displacement mechanism.

DFT-based pseudo-Jahn-Teller coupling studies on the steric and energetic lone pair effect of four- and five-coordinate halide molecules and complexes with central ions from the fifth, sixth, and seventh main groups.

The energetical and stereochemical effect of the s(2) lone pair in the title molecules and complexes is investigated using a pseudo-Jahn-Teller coupling model with parameters adjusted to energies and wave functions from DFT calculations. Vibronic coupling parameters were calculated and compared with those of the coordination number (CN) 3. Inspecting the correlation between the chemical hardness and the vibronic coupling energy (hardness rule), it is found that the tendency to distort decreases with increasing CN. While all considered molecules AX(3) (A(III) = P to Bi; X(-) = F to I) undergo lone pair deformations (D(3h)---> C(3v)), only part of the AX(4)(-) and BX(4) species (B(IV) = S to Po) do so (T(d)---> C(2v)-and even less the ones with CN = 5 (D(3h)---> C(2v) (congruent with C(4v)), AX(5)(2-), BX(5)(-), and CF(5) (C(V); Cl to I). The distorted polyhedra of minimum energy possess usually the butterfly C(2v) shape (CN = 4, tau(2)(zeta) displacement path) and a C(2v) = C(4v)geometry (CN = 5, epsilon' (epsilon) distortion path). A further symmetry lowering to C(s) occurs, if the central ion becomes too small with respect to the ligands (ionic size influence, PCl(Br)(4)(-), PCl(5)(2-)), with the tendency to reduce the CN toward 3 + 1 and 4 + 1, respectively. For CN = 4 the various stationary points of, for example, compressed and elongated C(3v), C(4v), etc. in the multidimensional ground-state potential surface have been characterized. Though of higher energy than the absolute C(2v) minimum, they are shown to govern the dynamics and reactivity of the CN = 4 species to a large extent. To simulate the chemical environment (positively charged counterions, polar solvents), the DFT calculations were performed using the polarizable continuum model COSMO (conductor-like screening model). Though the electronic energy gain upon distortion is not significantly affected by the solvent, the total stabilization energy is distinctly enhanced, frequently leading to lone pair deformations of otherwise electronically stable species. All results obtained by the combined vibronic/DFT approach are well in accord with available experimental data.

Development of combined loading apparatus for centrifuge test

This paper presents the design, mechanism and performance of a combined loading apparatus that has been jointly developed at The Tokyo Institute of Technology and the Railway Technical Research Institute of Japan for centrifuge tests. The unique feature of the test system developed is that any combination of load and displacement path of combined vertical (V), horizontal (H) and moment (M) load can be generated and directly applied to model footing. The combined load, displacement and rotation can be accurately achieved by a feedback system that controls three loading jacks and three servo motors. The Cambridge-high performance contact stress transducer was customarily designed and placed into the system in order to evaluate the loads acting on the model footings. A set of LVDTs is also positioned to measure the movement of footings. The primary aim of the development of this system was to observe the footing behavior in V-H-M load and displacement space. The apparatus was first used to evaluate the performance and effectiveness of the new composite structure of shallow foundation and sheet pile called “sheet pile foundation”. The test results confirmed the expected performance of the newly developed loading apparatus.

Seismic energy dissipation in deteriorating systems through low‐cycle fatigue

AbstractEnergy dissipation characteristics of structural members which exhibit both strength and stiffness deterioration under imposed displacement reversals are investigated. In the experimental part, 17 reinforced concrete beam specimens were tested under constant and variable amplitude inelastic displacement cycles. The constant‐amplitude tests were employed to determine the low‐cycle fatigue behaviour of specimens where the imposed displacement amplitude was the major variable. A two‐parameter fatigue model was developed in order to express the variation of dissipated energy with the number of displacement cycles. This model was then used to predict the energy dissipation of test specimens subjected to variable‐amplitude displacement cycles simulating severe seismic excitations. It has been demonstrated that the remaining energy dissipation capacity in a forthcoming displacement cycle is dependent on the energy dissipated along the completed displacement path. Moreover, it is observed that total energy dissipation is dependent on the length of the displacement path. Copyright © 2003 John Wiley & Sons, Ltd.

Energy‐based hysteresis and damage models for deteriorating systems

AbstractThe low‐cycle fatigue model presented in the companion paper is employed for developing hysteresis and damage models for deteriorating systems. The hysteresis model performs strength reduction at a current displacement cycle by evaluating the loss in the energy dissipation capacity along the completed displacement path. Hence it is completely memory dependent. Pinching is accounted for implicitly by a reduced energy dissipation capacity in a displacement cycle. The model predicts the experimental results obtained from variable‐amplitude tests reasonably well. Response analysis under earthquake excitations reveals that both the maximum displacements and the number of large‐amplitude displacement response cycles increase significantly with the reduction in energy dissipation capacity, resulting in higher damage. Damage is defined as the deterioration in the effective stiffness of a displacement cycle, which is in turn related to the reduction in the energy dissipation capacity. A simple damage function is developed accordingly, consisting of displacement and fatigue components. It is observed that the fatigue component of damage is more significant than the displacement component for deteriorating systems under ground motions with significant effective durations. Copyright © 2003 John Wiley & Sons, Ltd.

Motion characteristics of murrah buffalo bull spermatozoa in various seasons and its relationship with functional integrity of the plasmallema

Semen was collected from six adult (3.5–7-year-old) Murrah buffalo bulls at weekly intervals for 1 year and evaluated for routine parameters, motion characteristics, reactivity in hypoosmotic solution, and acrosomal and other morphological abnormalities of the spermatozoa. The overall motility (MOT), straight line velocity (VSL), curvilinear velocity (VCL), linearity (LIN), lateral head displacement (ALH) and average path velocity (VAP) were 66.85±2.79%, 26.58±0.24 and 107.07±1.47 μm/s, 26.91±0.01%, 11.19±0.09 and 61.78±2.79 μm/s, respectively. Significant seasonal variation was observed in sperm kinematics and hypoosmotic swelling (HOS) reactivity. Except for LIN, the mean values of sperm dynamics were higher during summer and rainy season and significantly lower in winter season. Sperm kinematics showed significant ( P<0.01) positive correlation ( r=0.25–0.60) with plasmallemal integrity. Ejaculates with less than 50% HOS-reactive spermatozoa had significantly lowered MOT, VSL, VCL and VAP as compared to the ejaculates with >50% HOS-positive spermatozoa. No significant difference was observed in sperm kinematics among the ejaculates having 50–70% and >70% HOS-reactive spermatozoa. The trend of motion dynamics of the spermatozoa with respect to HOS reactivity was similar in all the three seasons (summer, rainy and winter). The results indicate that ejaculates having more than 50% of HOS-reactive sperm show a higher magnitude of sperm kinematics compared to ejaculates having less than 50% HOS-positive spermatozoa.