Hysteretic Motion Research Articles

Improving the accuracy of motion quantification using area detector computed tomography for real-time tumor-tracking irradiation in stereotactic ablative radiotherapy.

CyberKnife radiotherapy enables tumor-tracking irradiation using positional information regarding the tumor and a fiducial marker in a patient's body. This positional information acts as a surrogate of tumor motion. Therefore, deviations in these movements should be quantitatively estimated and included as an internal margin for radiation treatment planning. This study aimed to investigate variations between the positions of fiducial markers and tumor regions using 320-row area detector computed tomography and to analyze the effectiveness of our proposed method in contouring tumor regions based on the fiducial marker position. To determine the moving tumor volume, a typical single-phase image was selected, and pixel values in other phase images were accumulated. Moreover, a maximum-intensity projection image was created to clarify motion deviations in the tumor volume. To evaluate the delineation accuracy, the dice similarity coefficient and mean distance to agreement were calculated in phase-selected and breath-holding computed tomography. Moving chest phantom images were acquired using helical scanning 4-dimensional computed tomography (H-4DCT) and volumetric scanning 4-dimensional computed tomography (V-4DCT), and the delineation accuracies were compared for each scanning type. The average dice similarity coefficient and mean distance to agreement were degraded in limited-phase images, which cannot represent the hysteretic motion of a tumor. Moreover, deviations in tumor volume with unstable motion reached 71.6% in H-4DCT but only 1.6% in V-4DCT. Our proposed method with V-4DCT using area detector computed tomography can achieve accurate moving tumor delineation and can clarify positional associations between the fiducial marker and tumor under respiratory motion.

On the understanding of damping capacity in SMA: From the material thermomechanical behaviour to the structure response

Superelastic Shape Memory Alloys (SMAs) provide a high damping capacity due to the hysteretic motion of the inter-phase boundaries during the martensitic transformation. They have demonstrated their ability to control vibrations of SMA-based Civil Engineering and Aerospace structures. In order to improve existing damping devices, characterization of SMA damping capacity is necessary, despite the lack of a standard procedure. Classical characterizations such as tensile or torsion tests on SMA samples are very attractive, the fact that they are common and simple to process. Furthermore, environment and loading conditions are quite easy to control. Different energy-based formulations have been proposed in the literature to explicitly predict SMA damping capacity from the hysteretic mechanical behaviour. The aim of this paper is to classify commonly used formulations from the literature, using a new thermomechanical vibration numerical model of a SMA beam structure. Thus, three energy-based predictions of SMA intrinsic damping ratio measured at the material scale are compared to the damping ratio measured from the free vibration signal at the SMA beam structure scale, taken as the objective reference. The formulation proposed by Piedbœuf and Gauvin provided a better match in three study-cases.

Damping and transformation behaviors of Ti50(Pd50−xCrx) shape memory alloys with x ranging from 4.0 to 5.0

The damping and transformation behaviors of Ti50(Pd50−xCrx) shape memory alloys with x ranging from 4.0 to 5.0 are systematically investigated. The damping capacity (Q−1) at the martensitic transformation is found to be inversely proportional to the square root of frequency, i.e., Q−1∝ω−0.5. A relaxation peak or shoulder is observed slightly below the martensitic transformation damping peak for compositions within the compositional crossover region (4.5 ⩽x⩽ 4.8). Furthermore, the damping capacity at the martensitic transformation is smaller within the compositional crossover region (4.5 ⩽x⩽ 4.8), compared with that of compositions at both sides (x=4.0 and x=5.0). These observations can be ascribed to the hysteretic motion of interfaces between different phases near the compositional crossover region.

Correction of hysteretic respiratory motion in SPECT myocardial perfusion imaging: Simulation and patient studies.

Amplitude-based respiratory gating is known to capture the extent of respiratory motion (RM) accurately but results in residual motion in the presence of respiratory hysteresis. In our previous study, we proposed and developed a novel approach to account for respiratory hysteresis by applying the Bouc-Wen (BW) model of hysteresis to external surrogate signals of anterior/posterior motion of the abdomen and chest with respiration. In this work, using simulated and clinical SPECT myocardial perfusion imaging (MPI) studies, we investigate the effects of respiratory hysteresis and evaluate the benefit of correcting it using the proposed BW model in comparison with the abdomen signal typically employed clinically. The MRI navigator data acquired in free-breathing human volunteers were used in the specially modified 4D NCAT phantoms to allow simulating three types of respiratory patterns: monotonic, mild hysteresis, and strong hysteresis with normal myocardial uptake, and perfusion defects in the anterior, lateral, inferior, and septal locations of the mid-ventricular wall. Clinical scans were performed using a Tc-99m sestamibi MPI protocol while recording respiratory signals from thoracic and abdomen regions using a visual tracking system (VTS). The performance of the correction using the respiratory signals was assessed through polar map analysis in phantom and 10 clinical studies selected on the basis of having substantial RM. In phantom studies, simulations illustrating normal myocardial uptake showed significant differences (P<0.001) in the uniformity of the polar maps between the RM uncorrected and corrected. No significant differences were seen in the polar map uniformity across the RM corrections. Studies simulating perfusion defects showed significantly decreased errors (P<0.001) in defect severity and extent for the RM corrected compared to the uncorrected. Only for the strong hysteretic pattern, there was a significant difference (P<0.001) among the RM corrections. The errors in defect severity and extent for the RM correction using abdomen signal were significantly higher compared to that of the BW (severity=-4.0%, P<0.001; extent=-65.4%, P<0.01) and chest (severity=-4.1%, P<0.001; extent=-52.5%, P<0.01) signals. In clinical studies, the quantitative analysis of the polar maps demonstrated qualitative and quantitative but not statistically significant differences (P=0.73) between the correction methods that used the BW signal and the abdominal signal. This study shows that hysteresis in respiration affects the extent of residual motion left in the RM-binned data, which can impact wall uniformity and the visualization of defects. Thus, there appears to be the potential for improved accuracy in reconstruction in the presence of hysteretic RM with the BW model method providing a possible step in the direction of improvement.

Dynamic nonlinearity in epitaxialBaTiO3films

Dynamic dielectric and piezoelectric constants of ferroelectrics increase proportionally to the amplitude of alternating electric field as a result of hysteretic Rayleigh-type motion of domain walls. Here a hysteresis-free quadratic field dependence of the dynamic dielectric response is experimentally demonstrated in the absence of domain walls in epitaxial $\mathrm{BaTi}{\mathrm{O}}_{3}$ films. This extraordinary behavior is related to polar entities, whose presence is confirmed by the Vogel-Fulcher relaxation. The polar entities are ascribed to polarization fluctuations associated with lattice inhomogeneity.

Non-uniform steel strip dampers subjected to cyclic loadings

This paper describes the cyclic performance of non-uniform steel strip dampers. The shapes proposed are (a) a dumbbell-shaped strip, (b) a tapered strip, and (c) an hourglass-shaped strip. Each of these strip shapes was designed to reduce stress concentration when subjected to cyclic loadings. In order to evaluate the performance of the dampers, six specimens were tested cyclically. Cumulative damage caused by hysteretic motion was effectively distributed throughout the entire height of the strips, and SEM microstructures of the fracture surfaces represented a typical ductile failure mode. The experimental results showed that the proposed strip dampers indicate excellent seismic performance compared to conventional prismatic slit dampers. Furthermore, it was verified that structural performance can be accurately estimated using the design equations presented in the paper.

Electrically Tunable Wetting Defects Characterized by a Simple Capillary Force Sensor

We present a concept of a wetting defect of continuously variable strength based on electrowetting, along with a capillary force sensor adapted for the characterization of macroscopically heterogeneous surfaces. Patterned electrodes submerged under an insulating layer are used to generate potential wells for drops of electrically conductive liquids on the solid surface, with a well depth that scales with the diameter of the drop and square of the applied alternating (AC) voltage. We characterize the strength of the electrowetting trap and the hysteretic motion of the drop along the surface, using a simple force sensor based on optical imaging of a thin bendable capillary. A force resolution of approximately 0.1 μN is achieved.

Geometric Hysteresis of Alveolated Ductal Architecture

Low Reynolds number airflow in the pulmonary acinus and aerosol particle kinetics therein are significantly conditioned by the nature of the tidal motion of alveolar duct geometry. At least two components of the ductal structure are known to exhibit stress-strain hysteresis: smooth muscle within the alveolar entrance rings, and surfactant at the air-tissue interface. We hypothesize that the geometric hysteresis of the alveolar duct is largely determined by the interaction of the amount of smooth muscle and connective tissue in ductal rings, septal tissue properties, and surface tension-surface area characteristics of surfactant. To test this hypothesis, we have extended the well-known structural model of the alveolar duct by Wilson and Bachofen (1982, "A Model for Mechanical Structure of the Alveolar Duct," J. Appl. Physiol. 52(4), pp. 1064-1070) by adding realistic elastic and hysteretic properties of (1) the alveolar entrance ring, (2) septal tissue, and (3) surfactant. With realistic values for tissue and surface properties, we conclude that: (1) there is a significant, and underappreciated, amount of geometric hysteresis in alveolar ductal architecture; and (2) the contribution of smooth muscle and surfactant to geometric hysteresis are of opposite senses, tending toward cancellation. Quantitatively, the geometric hysteresis found experimentally by Miki et al. (1993, "Geometric Hysteresis in Pulmonary Surface-to-Volume Ratio during Tidal Breathing," J. Appl. Physiol. 75(4), pp. 1630-1636) is consistent with little or no smooth muscle tone in anesthetized rabbits in control conditions, and with substantial smooth muscle activation following methacholine challenge. The observed local hysteretic boundary motion of the acinar duct would result in irreversible acinar flow fields, which might be important mechanistic contributors to aerosol mixing and deposition deep in the lung.

WE‐E‐BRC‐09: 4D CT Image Based Bifurcation Trajectory Tracking in the Lung

Purpose: Vessel and bronchial bifurcations are ubiquitous in the lungs and their motions caused by respiration are detectable in 4D CT and serve as valuable internal fiducial markers for studying and monitoring the respiratory motion patterns of the lungs. Bifurcations also serve as reliable landmarks for validation of deformable registration models. In this work, we report the first systematic investigation of motion patterns of a large collection of lung bifurcations. Methods: More than 500 bifurcations are identified automatically on a reference image. Each bifurcation is tracked separately. Trajectory of a bifurcation is defined by a B‐spline space curve with 5 control points with imposed cyclic constraints. A metric is defined as the combination of the correlation coefficients from all images with respect to the reference image. It is used to measure how well the image intensities on the trajectory match. Correlation coefficient is employed since it is bounded and straightforward to indicate the reliability of a tracked trajectory. Finally, an optimization strategy based on the L‐BFGS method is employed to optimize the metric parameterized by the coordinates of control points. Local extrema, if found, are suppressed by improving the initial conditions by random walks from pair‐wise optimizations. Results: We successfully tested our method in 5 cases. With automatically detected bifurcations, the tracked trajectories correspond to image intensities of high correlation coefficients. Non‐homogeneous and hysteretic motion is clearly observable in all cases. For validation, the tracking error is measured by computing the distance between the tracked and manual bifurcations. On average, the error is within the voxel size in all cases. Conclusions: We have shown that our approach can track the motion of the bifurcations in 4D CT images of the lung accurately. It may substitute the invasive fiducial markers as noninvasive counterparts for future real‐time volumetric imaging guided radiation therapy.

Magnesium matrix composites as interesting HIDAMETS

Metal matrix composites, made of Mg or Mg-2wt.%Si matrices reinforced with C or SiC long fibres, were processed by gas-pressure infiltration. Such composites are an advantageous solution for developing light metallic materials, which exhibit simultaneously good mechanical properties and a high damping capacity. For instance C/Mg-Si composites have a specific Young's modulus more than 4 times and a damping capacity 10-100 times higher than steels or aluminium alloys. The thermal behaviour of these materials was investigated by mechanical spectroscopy. Thermal stress relaxation at interfaces gives rise to transient damping, which is interpreted as being due to hysteretic dislocation motion. Hysteretic dislocation motion is also responsible for the mechanical loss background. As this mechanism is not thermally activated, high damping is maintained in a wide frequency and temperature range.

ボールねじの玉挙動とロストモーション（第２報）―ダブルナットあるいはオーバサイズ球予圧方式による荷重の影響―

It is well known that preloaded ball screws with double nut produced hysteretic motion between the rotary motion of the screw shaft and the linear motion of the nut, which is called “lost motion”, affects positioning accuracies of ball screws.Preloaded ball screws with a double nut have the characteristic that loaded balls wedge into a right angle direction to a ball rolling direction because the directions of screw shaft and nut raceways differ from the ball rolling direction. Loaded balls of preloaded ball screws with a double nut have two contact points geometrically. When the ball screw is operated under the condition of screw shaft turning and nut stationary, the balls have the velocity component perpendicular to the load line of action due to the helical raceway groove. Therefore the balls wedge into nut grooves. In the case of a ball screws with a circular-arc groove profile, “ball wedging” phenomenon is saturated when the force of resistance to ball wedging exceeds a frictional force between the ball and the raceway groove.In the present study, the authors experimentally investigated the lost motion of the X-table which is composed of a preloaded precision ball screw and a couple of linear air bearings, and the ball wedging behaviors under the condition of varied preload with double nut or over-sized balls have also measured.

Thermal stress relaxation in magnesium matrix composites controlled by dislocation breakaway

In metal matrix composites (MMCs) thermal stress relaxation can be achieved either by interface debonding, crack propagation or by dislocation motion. The present paper shows that in the case of magnesium matrix, interface thermal stresses are relaxed by dislocation motion. Moreover the results obtained by mechanical spectroscopy prove that this dislocation motion is controlled by a solid friction mechanism, which is not thermally activated. This point is very interesting for the development of MMCs, which exhibit a high damping capacity over a wide frequency range. Dislocation hysteretic motion in the magnesium matrix is evidenced by the dependence of the mechanical loss on the stress amplitude. The obtained relationship obeys perfectly to the Granato–Lücke model for dislocation breakaway.

Polarization rotation contributions to dielectric nonlinearity in 65Pb(Mg1/3Nb2/3)O3–35PbTiO3 single crystals

The dielectric response of 65Pb(Mg1/3Nb2/3)O3–35PbTiO3 (PMN-35PT) single crystals is reported for ac field amplitudes up to ∼3.5 kV/cm over a frequency range from 3 Hz to 1 kHz. The nonlinear dielectric response is described by a Rayleigh-like analysis, indicating extrinsic contributions from nonlinear and hysteretic motion of internal interfaces (phase boundaries and domain walls). Furthermore, the extrinsic contributions are more than five times higher in the [110]- and [001]-poled crystals than crystals poled along the [111] axis. This is attributed to the ease of the polarization vector rotation along the MC mirror plane between orthorhombic and tetragonal phases of PMN-35PT.

A novel study of head motion hysteresis issues in contact probe recording systems

Contact-based recording on ferroelectric media and polymer media have been proposed and investigated for high-density probe storage. To achieve fast data rate, it is necessary to perform reading or writing with multiple probe heads simultaneously. However, localized variations in tribological behavior at the contact interface between the probes and recording media and variation in normal contact force would result in variation in friction and stiction over the interface and therefore amongst individual heads in the probe head array. This causes variation in the hysteretic motion of the heads over the array, which in turn results in off-track motion during track-positioning and timing errors during scanning. In this paper a novel method of modeling these effects is developed to study the effect of relative head-motion hysteresis (RHMH) on timing-error during data read–write and off-track errors during seek-settle. A mathematical model of RHMH during scanning along the bit-wise direction is developed based on the idea of stochastic averaging. A transient response model is similarly developed for estimating hysteresis effects during seek-settle. These models help to understand parametric dependencies of RHMH and can be used in designing the probe heads, the probe–media interface (PMI) and the probe system in general. Further several schemes involving modulation of the normal force at the PMI are proposed to mitigate RHMH and their benefits are analyzed using the models described in this paper.

Fe-Cr-Mn-(Co) High Damping Stainless Alloy (HIDAS)

Based on the recent requirements, high strength, high damping stainless alloy HIDAS was developed. The chemical compositions are Fe-12%Cr-22%Mn and Fe-12%Cr-22%Mn-2%Co. After solution annealing, microstructure consisting of austenite fcc , martensite hcp and bcc ’. When cold work was given, and increased. Damping capacity increased with the increase of phase. The mechanism of high damping capacity would come from the hysteretic motion of Shockley partial dislocations which are lying at interphase interface of /. This alloy has also high strength. This is due to fine structure of /. Because of these properties, HIDAS can be applied to machinery industries.

Mechanical spectroscopy of interface stress relaxation in metal–matrix composites

C/Mg–2 wt%Si composites were processed by gas-pressure infiltration of long carbon fibers with molten Mg–2 wt%Si. These composites have specific Young's modulus more than 4 times and damping capacity 10–100 times higher than steels or aluminum alloys. The thermal behavior of these materials was investigated by mechanical spectroscopy. A shear modulus anomaly was observed between 200 and 400 K, which has been attributed to the interface de-bonding of the fibers at low temperature. Thermal stress relaxation at interfaces gives rise to transient damping ( T ˙ effect), which has been interpreted as being due to hysteretic dislocation motion. It is shown that the hysteretic and reversible motion of dislocations that relax interface stresses is a beneficial factor for high damping capacity and good resistance to fatigue.

Quasiperiodic energy pumping in coupled oscillators under periodic forcing

The effect of a nonlinear energy sink (NES) with relatively small mass on the dynamics of a coupled system under periodic forcing in the vicinity of a main (1:1) resonance is studied theoretically and experimentally. It is demonstrated that over a range of amplitudes of the external forcing the damped system exhibits a quasiperiodic vibration regime, rather than the steady-state response reported in earlier publications. This regime is related to attraction of the dynamical flow to a damped–forced nonlinear normal mode (NNM) of the system and hysteretic motion of the flow in the vicinity of this mode. A physical experiment using an appropriate electric circuit confirms the above results. The regime of quasiperiodic response is shown to provide more efficient vibration suppression than the best-tuned linear absorber with the same mass.

Quasi-Periodic Response Regimes of Linear Oscillator Coupled to Nonlinear Energy Sink Under Periodic Forcing

Quasi-periodic response of a linear oscillator attached to nonlinear energy sink with relatively small mass under external sinusoidal forcing in a vicinity of main (1:1) resonance is studied analytically and numerically. It is shown that the quasi-periodic response is exhibited in well-defined amplitude-frequency range of the external force. Two qualitatively different regimes of the quasi-periodic response are revealed. The first appears as a result of linear instability of the steady-state regime of the oscillations. The second one occurs due to interaction of the dynamical flow with invariant manifold of damped-forced nonlinear normal mode of the system, resulting in hysteretic motion of the flow in the vicinity of this mode. Parameters of external forcing giving rise to the quasi-periodic response are predicted by means of simplified analytic model. The model also allows predicting that the stable quasi-periodic regimes appear for certain range of damping coefficient. All findings of the simplified analytic model are verified numerically and considerable agreement is observed.

Oxygen Vacancy Relaxation and Domain Wall Hysteresis Motion in Cobalt‐Doped Barium Titanate Ceramics

Mechanical and dielectric loss measurements were carried out in the BaTiO3 ceramics doped with Co at frequencies between 0.01 Hz and 1 MHz as a function of temperature from −150° to 150°C. The relaxation peak observed in the ferroelectric phase with an activation energy of 0.27 eV is assumed to be related to the motion of oxygen vacancies. This peak could be because of the reorientation of an electrical dipole made of oxygen vacancies and Co3+ ions in the lattice. Furthermore, another loss peak located just below the Curie temperature Tc could be interpreted as hysteretic motion of the domain walls in a regime where the domain wall density is changing.

Visualization of vortex chains inBi2Sr2CaCu2O8+yby magneto-optical imaging

We visualized vortex chains in the crossing-lattices state in ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+y}$ by using magneto-optical imaging technique. From the spacing of vortex chains, we could determine the anisotropy parameter quantitatively, from $\ensuremath{\gamma}=800\ifmmode\pm\else\textpm\fi{}80$ for a slightly underdoped sample to $\ensuremath{\gamma}=490\ifmmode\pm\else\textpm\fi{}50$ for slightly overdoped samples. Vortex chains can be rotated by changing the direction of in-plane field in the ${\mathrm{CuO}}_{2}$ plane. Hysteretic motion and the forking of vortex chains are discussed in relation to the indirect pinning of Josephson vortices through pinning of pancake vortices.