Time-dependent Movements Research Articles

Alignment of the ATLAS Inner Detector in Run 2

The performance of the ATLAS Inner Detector alignment has been studied using pp collision data at sqrt{s} = 13,hbox {TeV} collected by the ATLAS experiment during Run 2 (2015–2018) of the Large Hadron Collider (LHC). The goal of the detector alignment is to determine the detector geometry as accurately as possible and correct for time-dependent movements. The Inner Detector alignment is based on the minimization of track-hit residuals in a sequence of hierarchical levels, from global mechanical assembly structures to local sensors. Subsequent levels have increasing numbers of degrees of freedom; in total there are almost 750,000. The alignment determines detector geometry on both short and long timescales, where short timescales describe movements within an LHC fill. The performance and possible track parameter biases originating from systematic detector deformations are evaluated. Momentum biases are studied using resonances decaying to muons or to electrons. The residual sagitta bias and momentum scale bias after alignment are reduced to less than sim 0.1hbox { TeV}^{-1} and 0.9times 10^{-3}, respectively. Impact parameter biases are also evaluated using tracks within jets.

An unstructured mesh algorithm for simulation of hydraulic fracture

The paper describes a flexible computational method that can be used to represent the complex geometric evolution of a fluid-driven fracture front using an unstructured triangular element mesh. A specific motivation for the method is to allow subsequent treatment of non-planar fracture growth problems. Elastic interactions between the crack opening displacements and the surrounding medium are calculated using displacement discontinuity boundary element influence functions. A novel feature of the approach is the use of an adjustable region of tip elements to accommodate both time-dependent crack edge movements and to ensure correct velocity-dependent asymptotic behavior for viscous and viscous-toughness flow conditions. The adjustable tip element region is represented using a special-purpose data structure that allows the iteration of the moving edge element vertices to be linked directly to the flow rate and the crack opening solution values that are determined in each time step. The fringe region is periodically replaced with a set of fixed vertex elements as the fracture surface evolves. The proposed scheme has been evaluated using available analytic and experimental results for planar fracture propagation. The method is found to be both accurate and robust for a range of choices of geometric fracture shapes and time step sizes.

Lessons learnt from a deep excavation for future application of the observational method

This paper draws lessons learnt from a comprehensive case study in overconsolidated clay. Apart from the introduction of the case study, including field measurements, the paper draws on the observations and a three-dimensional (3D) numerical analysis to discuss the implications of observations in the application of the observational method (OM) in the context of the requirements of EUROCODE 7 (EC7). In particular, we focus on corner effects and time-dependent movements and provide initial guidance on how these could be considered. Additionally, we present the validation of a new set of parameters to check that it provides a satisfactory compliance with EC7 as a set of design parameters. All these findings and recommendations are particularly important for those who want to use the OM in similar future projects.

On-the-fly analysis of molecular dynamics simulation trajectories of proteins using the Bayesian inference method.

Robust and reliable analyses of long trajectories from molecular dynamics simulations are important for investigations of functions and mechanisms of proteins. Structural fitting is necessary for various analyses of protein dynamics, thus removing time-dependent translational and rotational movements. However, the fitting is often difficult for highly flexible molecules. Thus, to address the issues, we proposed a fitting algorithm that uses the Bayesian inference method in combination with rotational fitting-weight improvements, and the well-studied globular protein systems trpcage and lysozyme were used for investigations. The present method clearly identified rigid core regions that fluctuate less than other regions and also separated core regions from highly fluctuating regions with greater accuracy than conventional methods. Our method also provided simultaneous variance-covariance matrix elements composed of atomic coordinates, allowing us to perform principle component analysis and prepare domain cross-correlation map during molecular dynamics simulations in an on-the-fly manner.

Numerical model for shaley rock masses displaying long-term time dependent deformation (TDD) behavior and its application to a pedestrian tunnel constructed under Lake Ontario

Southern Ontario is known for very high horizontal in-situ stresses and time dependent behavior of shale formations, which has resulted in continued rock deformation and distress in final linings in several previous projects in the region, sometimes years after installation. Billy Bishop Toronto City Airport Pedestrian Tunnel is a passenger access tunnel under the Western Channel of Lake Ontario. This paper discusses a series of numerical approaches used for predicting time dependent deformations, both during, as well as after the completion of the tunnel, to determine the optimal timing of the placement of the final lining, such that the remaining time-dependent movements can be sufficiently accommodated within the structural capacity of the tunnel lining. The paper also discusses the design process using a series of numerical analysis and construction sequencing considerations pertaining to the long-term time dependent deformation of the shaley rock formation, the instrumentation and monitoring program, and a comparison of the predicted against the actual movements during construction. Results from a custom-made FLAC sub-routine are provided in addition to the details of the numerical analysis - both the problems that were identified during the analyses as well as their solutions - throughout the discussion.

Assessment of Torque and Vertical Force Generated by Torque-sensitive and Time-dependent Reciprocal Movements of Nickel-titanium Rotary Root Canal Instruments

Assessment of Torque and Vertical Force Generated by Torque-sensitive and Time-dependent Reciprocal Movements of Nickel-titanium Rotary Root Canal Instruments

Time-dependent ground movements induced by shield tunneling in soft clay: a parametric study

In this work, the effects of coupled hydromechanical (consolidation) processes associated with shield tunneling excavation in soft clays are investigated with particular attention to the prediction of ground movements at the ground surface. A series of 2d FE analyses have been carried out in parametric form in order to investigate the effects of tunnel excavation velocity relative to the soil consolidation rate and the hydraulic boundary conditions at the tunnel boundary. The shield advancement process has been simulated with a simplified procedure incorporating both volume loss and ovalization of the tunnel section. In order to investigate the relative importance of soil consolidation during the excavation process, different characteristic times for the tunnel face advancement and for the consolidation process around the tunnel have been considered, for the two limiting conditions of fully permeable liner and impervious liner. The potential damage induced by the tunnel excavation on existing structures, based on computed ground surface distortions and horizontal deformations, has been found to vary significantly with time during the consolidation process. The results of the simulations allowed to obtain useful information on the minimum tunnel face advancement speed for which the assumption of fully undrained conditions for the soil during the excavations is acceptable, as well as on the speed range for which solving the fully coupled hydromechanical problem is necessary.

Dynamic response of cracked rotor-bearing system under time-dependent base movements

Dynamic response of cracked rotor-bearing system under time-dependent base movements is studied in this paper. Three base angular motions, including the rolling, pitching and yawing motions, are assumed to be sinusoidal perturbations superimposed upon constant terms. Both the open and breathing transverse cracks are considered in the analysis. The finite element model is established for the base excited rotor-bearing system with open or breathing cracks. Considering the time-varying base movements and transverse cracks, the second-order differential equations of the system will not only have time-periodic gyroscopic and stiffness coefficients, but also the multi-frequency external excitations. An improved harmonic balance method is introduced to obtain the steady-state response of the system under both base and unbalance excitations. The response spectra, orbits of shaft center and frequency response characteristics, are analyzed accordingly. The effects of various base angular motions, frequency and amplitude of base excitations, and crack depths on the system dynamic behaviors are considered in the discussions.

Dynamic ultrasound imaging—A multivariate approach for the analysis and comparison of time-dependent musculoskeletal movements

BackgroundMuscle functions are generally assumed to affect a wide variety of conditions and activities, including pain, ischemic and neurological disorders, exercise and injury. It is therefore very desirable to obtain more information on musculoskeletal contributions to and activity during clinical processes such as the treatment of muscle injuries, post-surgery evaluations, and the monitoring of progressive degeneration in neuromuscular disorders.The spatial image resolution achievable with ultrasound systems has improved tremendously in the last few years and it is nowadays possible to study skeletal muscles in real-time during activity. However, ultrasound imaging has an inherent problem that makes it difficult to compare different measurement series or image sequences from two or more subjects. Due to physiological differences between different subjects, the ultrasound sequences will be visually different – partly because of variation in probe placement and partly because of the difficulty of perfectly reproducing any given movement.MethodsUltrasound images of the biceps and calf of a single subject were transformed to achieve congruence and then efficiently compressed and stacked to facilitate analysis using a multivariate method known as O2PLS. O2PLS identifies related and unrelated variation in and between two sets of data such that different phases of the studied movements can be analysed. The methodology was used to study the dynamics of the Achilles tendon and the calf and also the Biceps brachii and upper arm. The movements of these parts of the body are both of interest in clinical orthopaedic research.ResultsThis study extends the novel method of multivariate analysis of congruent images (MACI) to facilitate comparisons between two series of ultrasound images. This increases its potential range of medical applications and its utility for detecting, visualising and quantifying the dynamics and functions of skeletal muscle.ConclusionsThe most important results of this study are that MACI with O2PLS is able to consistently extract meaningful variability from pairs of ultrasound sequences. The MACI method with O2PLS is a powerful tool with great potential for visualising and comparing dynamics between movements. It has many potential clinical applications in the study of muscle injuries, post-surgery evaluations and evaluations of rehabilitation, and the assessment of athletic training interventions.

Alignment of the CMS silicon tracker

The CMS all-silicon tracker consists of 16 588 modules with 25 684 sensors in total. In 2010 it has been successfully aligned using tracks from cosmic rays and proton-proton collisions, following the time dependent movements of its innermost pixel layers. In 2011, ultimate local precision is achieved by determining sensor curvatures in addition to module shifts and rotations, challenging the alignment procedure to determine about 200 000 parameters. This is achieved in a global fit approach using Millepede II with the General Broken Lines track model. Remaining alignment uncertainties are dominated by systematic effects that bias track parameters by an amount relevant for physics analyses. These effects are controlled by including information about the Z boson mass in the fit.

Hangingwall surface subsidence at the Kiirunavaara Mine, Sweden

Large scale surface subsidence has been experienced at the Kiirunavaara mine since sublevel caving was implemented as a mining method. Surface disturbances are affecting part of the city of Kiruna, the railway, and the power station. Continuous and discontinuous subsidences characterize the hangingwall deformation, which is periodically monitored using surveying techniques and mapping of surface cracks. A historic review of subsidence prognoses has been carried out and the results compared with the actual condition of the hangingwall. The review showed discrepancies between different prognoses. In addition, limit equilibrium analyses indicated that break angles flatten while the mining depth increases. However, this tendency is not clear in the field where break angles show a large dispersion of values. By using surveying data, two different analyses have been performed. The time-dependent movements of the hangingwall have been described using time–displacement curves and strain analysis has been performed for different sections of the hangingwall. Three different stages of the time–displacement behavior have been identified and described. It has been concluded that extension strain can reach values which may damage civil structures before surface crack can be observed.

Isomorphism of Existing But Hidden Time In Quantum Mechanical Formalism and Human Consciousness

Time is thought to be inexistent in the formalism of quantum mechanics. But time can also become unobservable and hidden in classical physics and in human consciousness. All physical or societal laws show timeless invariance, indicating that time dependent movements can show timeless behaviour. Therefore timeless behaviour includes an unobservable form of underlying movements implying time. Movements in the present can be directly perceived and necessarily show time coordinates, but movements accomplished in the past can no longer be directly perceived and only leave traces of grouped movements, similar to animal tracks. Invariance of movements can only be found when movements are grouped together in traces and accomplished in the past. Then time can only be estimated and when necessary retrospectively associated to the traces. Time is no longer required, when different traces of movements are compared with each other. Nevertheless, invariant traces testify underlying regularly movements and therefore time, even if time is no longer observable in the traces. In a similar way physical formalism includes present, past and future of movements at a higher concentrated information level. Since only the present is observable, information including past and future becomes unobservable, thereby hiding time. Time is also hidden in the digit codes of music on registered CDs and becomes only observable again after back-transformation by a convenient device. The phenomenon of hidden time can be found in consciousness and in classical physics, but becomes dominant in quantum mechanics

A case study on the behaviour of a deep excavation in sand

A complete case record of an excavation in sand is explored in this study. Numerical analyses were conducted to evaluate the influences of soil elasticity, creep and soil–wall interface. Back-analyses indicate small strain parameters should be used if an elastic–perfect plastic model is selected. In addition, excavation-induced seepage has only a limited effect on vertical displacements. Delayed installation of 3rd level struts and base slab construction caused significant time-dependent (creep) movements during the excavation. Back-analyses show that the dynamic viscosity ( D v) used in the visco-elastic model for creep simulation is in the range of 1.5 × 10 15–2.0 × 10 15 Pa, but there are still inconsistencies in movements both near to and far from the excavation. Interpreting from observation data, the creep rate of wall movement caused in the non-supported stage of the excavation varies between 0.14 and 0.38 mm/day. Finally, parametric studies of interface elements indicate that the most sensitive parameters are the normal ( K n) and shear stiffness ( K s) of the interface. Back-analyses using an elastic–perfect plastic model indicate that using 3 × 10 6 Pa for K n and K s produces more acceptable results.

Tunnelling and geotechnics: new horizons

New developments in both the theory and the practice of tunnelling are covered in the lecture. The important relationship between tunnelling and geotechnics is highlighted, and recent advances in research and practice are described, drawing on model studies, theoretical developments and field measurements from case histories from around the world. Simplified plasticity models are presented that can be used by designers to assess ground movements and tunnel lining loads in complex ground conditions. The important role of pilot tunnels and in situ measurements to validate such models, drawing on a case history from Bolu, Turkey, and on other tunnelling projects, is described. Recent technical advances in earth pressure balance tunnelling are considered, illustrated by measurements from the Channel Tunnel Rail Link project, with emphasis on key factors influencing volume loss, such as face pressure, soil conditioning and effective screw conveyor operation. A recent case history in Bologna is described, in which the innovative use of directional drilling to install curved grout tubes was employed for a compensation grouting project in granular soils. Time-dependent ground movements and tunnel lining distortions occurring after tunnelling are discussed, their magnitude depending on the relative permeability of the tunnel lining and soil, the degree of anisotropy of the soil permeability, and the initial pore pressure prior to tunnelling. The effects of tunnelling-induced settlements on pipelines are considered, drawing on centrifuge tests and analytical solutions, and a new design approach is presented, taking into account the reduction of soil stiffness with increasing shear strain as a result of tunnel volume loss. The lecture concludes with a description of a distributed strain sensing technique using fibre optic technology, based on Brillouin optical time domain reflectometry (BOTDR), and its innovative application to field monitoring of a masonry tunnel subjected to new tunnel construction beneath it.

Fast Adaptation in Vestibular Hair Cells Requires Myosin-1c Activity

In sensory hair cells of the inner ear, mechanical amplification of small stimuli requires fast adaptation, the rapid closing of mechanically activated transduction channels. In frog and mouse vestibular hair cells, we found that the rate of fast adaptation depends on both channel opening and stimulus size and that it is modeled well as a release of a mechanical element in series with the transduction apparatus. To determine whether myosin-1c molecules of the adaptation motor are responsible for the release, we introduced the Y61G mutation into the Myo1c locus and generated mice homozygous for this sensitized allele. Measuring transduction and adaptation in the presence of NMB-ADP, an allele-specific inhibitor, we found that the inhibitor not only blocked slow adaptation, as demonstrated previously in transgenic mice, but also inhibited fast adaptation. These results suggest that mechanical activity of myosin-1c is required for fast adaptation in vestibular hair cells.

Estimation of the time-dependent crustal movements of the İzmit Earthquake

The 17 August 1999 İzmit earthquake significantly deformed the earth's crust in the Marmara Region, especially in the Gölcük–Sapanca Zone, Turkey. It broke a 150-km long segment of the northern branch of North Anatolian Fault Zone. The geodetically determined moment magnitude was Mw=7.5. Global Positioning System (GPS) sites, which are a small subset of the Marmara Continuous GPS Network (MAGNET), and survey sites in the region were studied to estimate coseismic and postseismic deformations, using different methodologies with linear, quadratic and exponential kinematic models. Six GPS epochs for these sites, which were carried out before and after the 17 August 1999 İzmit earthquake, were used to define the kinematic models. The quadratic deformation model was also applied to determine the time-dependent crustal movement parameters (velocity and acceleration) of the sites, using the Kalman filter technique. In order to show the differences between the models, the estimated deformation fields on the last epoch were compared. In all models, as expected, the faults near the sites show large coseismic displacements with fault parallel direction, whereas the far sites show small coseismic displacements due to the effects of the İzmit earthquake. Each kinematic model, fitted to the epochs after the earthquake, shows different behaviour. While the linear model shows insufficient results, the nonlinear models (quadratic and exponential) give the best fitted to the postseismic deformations. As a result of Kalman filter analysis, the fault near-sites shows significant velocities with fault parallel direction, whereas the far sites have insignificant velocities. All stations have insignificant accelerations in the last epoch.

A CFD study of unsteady flow in narrow spacer-filled channels for spiral-wound membrane modules

In spiral-wound membrane modules, spacers are used to enhance wall shear stress and to promote eddy mixing, thereby reducing wall concentration and fouling. Insights into the effect of spacer filaments on flow patterns in narrow channels were obtained using a computational fluid dynamics (CFD) code. The flow patterns were visualized for different filament configurations incorporating variations in mesh length, filament diameter and for channel Reynolds numbers up to 1000. The simulated flow patterns revealed the dependence of the formation of recirculation regions on the filament configuration, mesh length, filament diameter and the Reynolds number. When the channel Reynolds number is increased above 300, the flow becomes super-critical showing time-dependent movements for a filament located in the center of a narrow channel; and when the channel Reynolds number is increased above 500, the flow becomes super-critical for a filament adjacent to the membrane wall. For multiple filament configurations, flow transition can occur at channel Reynolds numbers as low as 80 for the submerged spacer at a very small mesh length ( l m / h ch = 1) and at a slightly larger Reynolds number at a larger mesh length ( l m / h ch = 4). The transition occurs above Re ch of 300 for the cavity spacer ( l m / h ch = 4) and above Re ch of 400 for the zigzag spacer ( l m / h ch = 4).

Design and Performance of an Electro-Pneumatic Pile Hammer for Laboratory Applications

Abstract Small piles used in research programs have generally been installed by pushing or driving using slow mechanical drop hammers, because of the expense and technical difficulties associated with manufacture of realistic small-scale pile driving hammers. However, pushing does not model inertial effects and slow driving does not model diffusive effects in the soil. It remains to be demonstrated whether these effects are important or not. To help clarify this issue, an electronically controlled, single-acting air hammer, with a rated energy of 211 J (156 ft · lb), and an operating frequency of up to 1.2 Hz, was designed and built. The hammer was used successfully to drive 90 mm (3.5 in.) diameter piles into dense sand under a confining pressure of 138 kPa (20 psi). The behavior of the hammer was documented using detailed measurements of time-dependent ram movements, accelerations, and chamber pressures. This paper is concerned with the design and performance of the hammer.

Simulation of time-dependent movements in Syncrude tailings dyke foundation

Foundation movements at the Syncrude tailings dyke continued over several years in response to the construction of the dyke. Major movements have been observed in a relatively narrow layer of previously sheared clay-shale material of the Clearwater Formation. The residual strength of this highly plastic clay increases with the rate of shear. By reviewing the existing literature on the rate effects on residual strength and using data from new experiments on Clearwater Clay Shale, a general correlation between soil plasticity and rate effects is found. This rate dependence of the residual strength of Clearwater clay shale has been incorporated into a deformation analysis, which made it possible to compute time-dependent movements of the foundation soil to a satisfactory level. By using a rate-dependent plasticity model, a prediction of anticipated foundation velocities and how they decrease with time may be achieved.Key words: finite element, rate effects, residual strength, Syncrude tailings dyke, time-dependent movements.

Simulation of time-dependent movements in Syncrude tailings dyke foundation

Simulation of time-dependent movements in Syncrude tailings dyke foundation