Phase Slip Research Articles

Experimental Studies on Bond Performance of BFRP Bars Reinforced Coral Aggregate Concrete

Basalt fiber reinforced polymer (BFRP) rebars reinforced coral aggregate concrete is a new type of concrete used in ocean engineering. In order to investigate the bond performance between BFRP rebars and coral concrete, 30 pull-out tests were carried out in 10 groups with different diameters of BFRP rebars, bonding lengths and strength of the coral concrete. The results show that good bonding between BFRP rebars and coral concrete were achieved. The main failure modes can be categorized as BFRP rebars pull out destruction, splitting failure of coral concrete and BFRP rebars fracture. The bond slip (tau{text{-}}s) curves of the BFRP rebars and coral concrete were obtained during the tests. It was found to be similar to the common concrete using fiber reinforced polymer (FRP) bars. The bond-slip relation can be roughly divided into micro-slip phase, slip phase, decline phase, and the residual stress stage. The bond between BFRP rebars and coral concrete increases with the increase of the bond length and diameter of BFRP rebars, but the average bond stress will decrease. Moreover, increasing the strength of coral concrete is effective to improve the bond performance of BFRP rebars. In this paper, the continuous bond slip model (Gao et al. in J Zhengzhou Univ 23:1–5, 2002) was used to represent the tau{text{-}}s constitutive relationship of BFRP rebars and coral concrete. The analysis show that the proposed model has a high degree of accuracy in representing tau{text{-}}s curve of BFRP rebars and coral concrete.

Experimental research on a phase slip and pressure loss during boiling of the refrigerant R134a in a mini-channel

This article is devoted to the development of a methodology for calculating the hydrodynamic characteristics of liquids boiling in mini-channels. In contrast to the well-known methods, the proposed methodology is based on the use of the true volumetric steam content and prediction of two-phase flow regimes in the field of a steady flow. The article presents experimental data on the true volumetric steam content, pressure loss, and two-phase flow pattern in mini-channels

An analytical model of subcritical and critical vapor-liquid flow through a granular bed

This paper presents a computational and experimental justification of a theoretical model for the two-phase vapor-liquid flow through a fixed bed of solid particles. The theoretical description is based on the equations of gas dynamics of the granular bed and the homogeneous model of a single-component two-phase flow, given the difference between the velocities of liquid and vapor phases. Relationships between the phase slip ratio and polytropic coefficient of isenthalpic expansion of vapor-liquid flow were obtained using the multi-parameter nonlinear regression. We used the experimental data on the vapor-liquid flow with an inlet pressure, P1, of 0.6-1.2 MPa and an inlet flow quality, x1, of 0.016-0.178 through a H=50-355 mm bed consisting of steel spheres, 2 and 4 mm in diameter, d. An expression for the critical pressure ratio in the granular bed is proposed. The developed model makes it possible to predict the values of mass velocity of the mixture over the entire range of experimental data with an average error of 3%. Based on the model equations, we obtained expressions for dimensionless mass velocity depending on the pressure ratio that can be applied to two-phase flows through both granular beds and other porous media.

METHOD OF GAS PRESSURE OPTIMIZATION IN PRODUCING WELL ANNULUS

The process of oil production using sucker rod-pumping installations, especially with high gas content of formation fluid, is accompanied by accumulation of oil gas in the annulus of wells. The growth of the annular gas pressure causes an increase in the back pressure on the reservoir and a number of other negative consequences, to exclude which various technologies are used to pump out gas from the annular space of production wells. The article considers the problem of optimizing the gas pressure in the annulus by pumping gas with a compressor at a constant speed. The design of the suspended plunger compressor driven by the balance of the pumping unit and the method for calculating the technological parameters of the compressor based on the balance of the compressor supply and the volumetric flow rate of the separated gas into the annulus are proposed. A two-stage algorithm for calculating the parameters of the optimal technological mode of well operation has been developed. As an optimization criterion, joint fulfillment of the following conditions was proposed: ensuring the permissible volume fraction of gas at the inlet, minimum pump immersion under the dynamic level, and maximizing the flow rate of the well. To assess the effectiveness of the proposed well operation technology and to calculate the increase in well flow rate during compressor operation, a mathematical model of a multiphase stationary gas-liquid mixture flow in a wellbore operated by a pumping pump unit, taking into account the equilibrium processes of separation and dissolution of oil gas, the effects of oil and gas phase slip, is proposed. The calculation results confirm that the use of compressors for pumping gas from the annulus allows one to obtain a significant increase in the flow rate of liquid and oil, which depends on the parameters and properties of the pumped product, the operational characteristics of the formation and barothermal conditions.

Optical control of the current-voltage relation in stacked superconductors

We simulate the current-voltage relation of short layered superconductors, which we model as stacks of capacitively coupled Josephson junctions. The system is driven by external laser fields, in order to optically control the voltage drop across the junction. We identify parameter regimes in which supercurrents can be stabilized against thermally induced phase slips, thus reducing the effective voltage across the superconductor. Furthermore, single driven Josephson junctions are known to exhibit phase-locked states, where the superconducting phase is locked to the driving field. We numerically observe their persistence in the presence of thermal fluctuations and capacitive coupling between adjacent Josephson junctions. Our results indicate how macroscopic material properties can be manipulated by exploiting the large optical nonlinearities of Josephson plasmons.

Mechanical properties and deformation behavior of dual-phase Al0.6CoCrFeNi high-entropy alloys with heterogeneous structure at room and cryogenic temperatures

Dual-phase Al0.6CoCrFeNi high-entropy alloys (HEAs) with heterogeneous structure are obtained by cold rolling and annealing. Tensile experiments show that this alloy exhibits excellent combinations of yield strength, tensile strength and tensile elongation at room (298 K) and cryogenic (77 K) temperatures. Through the thermodynamic formula, the stacking fault energy of face-centered cube (fcc) phases in Al0.6CoCrFeNi alloys are calculated to be 49.33 mJ/m2 and 28.69 mJ/m2 at 298 K and 77 K, respectively. Combining with EBSD (electron backscattering diffraction) and TEM (transmission electron microscopy), it is concluded that the deformation of dual-phase Al0.6CoCrFeNi alloys with heterogeneous structure at 298 K is mainly dominated by the dislocation slip in fcc plus bcc (body-centered cube) phases, and the deformation mode at 77 K can be divided into two stages: (1) when the true strain is between 0 and 3.8%, the plasticity is mainly caused by dislocation slip of fcc and bcc phases; (2) when the true strain is between 3.8% and samples fracture, the plasticity is mainly induced by deformation twins in fcc phase and dislocation slip in bcc phase.

Nonlinear phase bores in drift wave-zonal flow dynamics

A minimal model of nonlinear phase dynamics in drift waves is shown to support phase bore solutions. Coupled nonlinear equations for amplitude, phase, and zonal flow are derived for the Hasegawa-Mima system and specialized to the case of spatiotemporally constant amplitude. In that limit, phase curvature (finite second derivative of the phase with respect to the radius) alone generates propagating shear flows. The phase field evolves nonlinearly by a competition between phase steepening and dispersion. The analytical solution of the model reveals that the phase bore solutions so obtained realize the concept of a phase slip in a concrete dynamical model of drift wave dynamics. The implications for phase turbulence are discussed.

A stick-slip/inchworm hybrid rotary piezo motor based on a symmetric triangular driving mechanism

A stick-slip/inchworm hybrid rotary piezomotor based on a symmetric triangular driving mechanism, which can simultaneously achieve the benefits of both stick-slip and inchworm motors, was reported in this letter. It is based on the principle of stick-slip motors, and, inspired by the clamping-releasing actions from inchworm motors, it employs a symmetric triangular driving mechanism to generate a clamping action during the stick phase and a releasing action during the slip phase. Compared with stick-slip motors, it involves a clamping action during the stick phase and a releasing action during the slip phase, thus resulting in a larger driving force. Compared with inchworm motors, which require active control and coordination of clamping/releasing modules with feeding modules, it involves the control and operation of only one feeding piezoactuator without any actively controlled clamping/releasing module. Therefore, the control is easier, and a much larger operation frequency and driving speed can be achieved. Under the sawtooth waveform voltage of 90 V at 2600 Hz with a self-holding torque of 4 N m, the prototype achieved a no-load speed higher than 0.6 rad/s, a load torque capacity larger than 1.8 N m, and a weight carrying capacity more than 100 kg for both clockwise and anticlockwise directions. Compared with load torque capacity and weight carrying capacity in the reported stick-slip and inchworm rotary piezomotors, the current levels in terms of the same driving speed have been improved over 60 times and 12 times, respectively, in the proposed hybrid motor.

Simulation of the stick‐slip motion of an oscillatory roller

AbstractA three degrees‐of‐freedom (3DOF) lumped parameter model (LPM) of the oscillatory roller‐soil interaction system is presented that captures the stick‐slip motion of the drum during near‐surface compaction of non‐cohesive soils. The deformed soil below the drum is predefined as a rigid curved asymmetric guiding track (i.e. the compaction process in the soil is not simulated), supported by a vertical and horizontal Kelvin‐Voigt element, to predict also the vertical drum accelerations as observed in situ. The solution of this model, found by switching between the sets of highly nonlinear ODEs for the stick and slip phase, is compared with recorded and numerically simulated (Finite Element model) drum responses.

Nonlinear denoising for characterization of solid friction under low confinement pressure.

The present work investigates paper-paper friction dynamics by pulling a slider over a substrate. It focuses on the transition between stick-slip and inertial regimes. Although the device is classical, probing solid friction with the fewest contact damage requires that the applied load should be small. This induces noise, mostly impulsive in nature, on the recorded slider motion and force signals. To address the challenging issue of describing the physics of such systems, we promote here the use of nonlinear filtering techniques relying on recent nonsmooth optimization schemes. In contrast to linear filtering, nonlinear filtering captures the slider velocity asymmetry and, thus, the creep motion before sliding. Precise estimates of the stick and slip phase durations can thus be obtained. The transition between the stick-slip and inertial regimes is continuous. Here we propose a criterion based on the probability of the system to be in the stick-slip regime to quantify this transition. A phase diagram is obtained that characterizes the dynamics of this frictional system under low confinement pressure.

Experimental Study on Bond-Slip Behavior between Corroded I-Shaped Steel and Concrete in Subsea Tunnel

Degradation of the bond between I-shaped steel and concrete due to the corrosion of I-shaped steel significantly affects the durability of steel reinforced concrete (SRC) structures. This study carried out the accelerated corrosion test and push-out test to study the bond-slip behavior and characteristics considering the corrosion of I-shaped steel, and test results indicated that: (1) The performance degradation of the bond-slip accelerated when the corrosion ratio reached 12%. (2) The corrosion failure pattern of SRC experienced slip phase and destruction phase in the rising stage. (3) Based on the principle of minimum potential energy, the bond stress was obtained only with the load and the displacement in the free end and the loading end. (4) Meanwhile, a new bond-slip degradation model was developed using the interface damage theory. Finally, the proposed model agreed with the experimental results.

Synchronization in alternating linear chains of vortex-based spin-torque oscillators

Abstract The dynamic properties of magnetic vortices in single nanopillars, such as the gyrotropic orbital radius and frequency, have been shown to be well-modeled by the Thiele equation. Similarly, a set of coupled Thiele equations also describe synchronization of two or more interacting free layer vortices. Here the Thiele equations are used to model vortex dynamics in linear chains of alternating radius (where nearest-neighbor free layer have different radii) free layer oscillators, which is a system of interacting non-identical oscillators that can synchronize and lock onto a common frequency. For vortices interacting as magnetic dipoles it is shown that there are critical nanopillar separations below which the oscillator chain will synchronize. As the nanopillar separation increases, it is noticed that there is a narrow region of parameter space where synchronization is temporarily lost owing to phase slips and at larger separation synchronization is lost completely. The relation between the critical separation and the free layer radii difference is also estimated analytically.

Hilbert transform-based time-series analysis of the circadian gene regulatory network.

In this work, the authors propose the Hilbert transform (HT)‐based numerical method to analyse the time series of the circadian rhythms. They demonstrate the application of HT by taking both deterministic and stochastic time series that they get from the simulation of the fruit fly model Drosophila melanogaster and show how to extract the period, construct phase response curves, determine period sensitivity of the parameters to perturbations and build Arnold tongues to identify the regions of entrainment. They also derive a phase model that they numerically simulate to capture whether the circadian time series entrains to the forcing period completely (phase locking) or only partially (phase slips) or neither. They validate the phase model, and numerics with the experimental time series forced under different temperature cycles. Application of HT to the circadian time series appears to be a promising tool to extract the characteristic information about circadian rhythms.

Quantum fluctuations and phase coherence in superconducting nanowires

Quantum behavior of superconducting nanowires may essentially depend on the employed experimental setup. Here we investigate a setup that enables passing equilibrium supercurrent across an arbitrary segment of the wire without restricting fluctuations of its superconducting phase. The low temperature physics of the system is determined by a combined effect of collective sound-like plasma excitations and quantum phase slips. At $T=0$ the wire exhibits two quantum phase transitions, both being controlled by the dimensionless wire impedance $g$. While thicker wires with $g>16$ stay superconducting, in thinnest wires with $g<2$ the supercurrent is totally destroyed by quantum fluctuations. The intermediate phase with $2<g<16$ is characterized by two different correlation lengths demonstrating superconducting-like behavior at shorter scales combined with vanishing superconducting response in the long scale limit.

Superconducting properties of tungsten nanowires fabricated using focussed ion beam technique

We report superconducting properties of tungsten meander structures fabricated using the focussed ion beam (FIB) induced technique. Three meander structures with individual line widths of ∼70, ∼300 and ∼450 nm were fabricated for evaluation and comparison of the superconducting properties. The resistance-temperature characteristics of the meanders were measured and analysed down to a temperature of 100 mK. The superconducting properties such as critical temperature (TC) and upper-critical field (HC2) of these wires are in comparison to the reported values of FIB deposited tungsten available in literature. While the normal state resistance increases sharply as the width of the wire decreases, the superconducting transition temperature registered a slight decrease. Significant amount of residual resistance (3.8% of normal state value at 100 mK) was observed for the sample with the lowest width (70 nm). The residual resistance trails as function of temperature was analysed invoking theoretical models governing the phase slip induced dissipations in superconducting nanowires. The results indicated signature of phase slips as the width of the wire decreases: thermally activated phase slips dominant near to the TC and quantum phase slip (QPS) near to TC as well as much below to the TC. The magneto-resistance isotherms indicated quantum phase transitions (QPT); typical of a superconductor-to-insulator transition (SIT) driven by magnetic field. The SIT transition which originates from the intrinsic disorder present in the sample can be tuned by an external parameter such as magnetic field, and can be modelled by standard theories of QPT for quasi 2D or (2 + 1) D XY models. The successful fabrication of meander structures of W using FIB and the demonstration of superconductivity suggest that FIB deposited W can be exploited for many of the technological applications of superconducting nanowires such as superconducting nanowire single photon detectors, bolometers, transition edge sensors and even for quantum current standard employing the QPS phenomenon.

Temporal evolution of beta bursts in the parkinsonian cortical and basal ganglia network

Beta frequency oscillations (15 to 35 Hz) in cortical and basal ganglia circuits become abnormally synchronized in Parkinson's disease (PD). How excessive beta oscillations emerge in these circuits is unclear. We addressed this issue by defining the firing properties of basal ganglia neurons around the emergence of cortical beta bursts (β bursts), transient (50 to 350 ms) increases in the beta amplitude of cortical signals. In PD patients, the phase locking of background spiking activity in the subthalamic nucleus (STN) to frontal electroencephalograms preceded the onset and followed the temporal profile of cortical β bursts, with conditions of synchronization consistent within and across bursts. Neuronal ensemble recordings in multiple basal ganglia structures of parkinsonian rats revealed that these dynamics were recapitulated in STN, but also in external globus pallidus and striatum. The onset of consistent phase-locking conditions was preceded by abrupt phase slips between cortical and basal ganglia ensemble signals. Single-unit recordings demonstrated that ensemble-level properties of synchronization were not underlain by changes in firing rate but, rather, by the timing of action potentials in relation to cortical oscillation phase. Notably, the preferred angle of phase-locked action potential firing in each basal ganglia structure was shifted during burst initiation, then maintained stable phase relations during the burst. Subthalamic, pallidal, and striatal neurons engaged and disengaged with cortical β bursts to different extents and timings. The temporal evolution of cortical and basal ganglia synchronization is cell type-selective, which could be key for the generation/ maintenance of excessive beta oscillations in parkinsonism.

Analytical modeling of the stick-slip motion of an oscillation drum

In this paper, a lumped parameter model of the interacting oscillation roller-subsurface system is proposed. The main aim of the model is to predict the response acceleration of the roller drum during near-surface compaction of non-cohesive soils. The compaction process of the soil itself is not captured, but different degrees of compaction are considered by varying the soil stiffness. The roller is represented by the oscillation drum and its viscoelastic connection to the roller frame. In the chosen modeling strategy, the curvature of the soil surface below the drum is prescribed. In this way, also the vertical drum acceleration can be computed. The discrete subsoil model consists of a vertical and a horizontal Kelvin–Voigt element. Contact between drum and soil surface is described by means of dry friction according to Coulomb’s law. As such, the stick-slip motion of the drum can be simulated. In the stick phase, pure rolling between drum and soil surface is assumed. The highly nonlinear equations of motion of this three degrees-of-freedom model are derived separately for the stick and the slip phase of the motion. Selective numerical studies show that this model captures the fundamental response characteristics of the dynamic drum–subsoil interacting system observed in the field.

THE DISTRIBUTION OF MOLECULES OF THE INTERCELLULAR ADHESION ON BLOOD LEUKOCYTES DEPENDING ON THEIR MORPHOLOGY

Physiological understanding of the processes of migration of immunocompetent cells, as well as the conditions under which migration can be activated or slowed down, is especially important for the interpretation of the reserves of stability and preservation of homeostasis. Migration of leukocytes through the endothelium of the microcirculation is regulated by adhesion molecules. The aim of the study was to study the distribution of intercellular adhesion molecules on leukocytes depending on their morphology. An examination of 50 healthy individuals aged 20 to 60 years with no history of chronic disease was carried out. Venous blood for the study was taken in the morning on «empty» stomach. On a flow cytometer FC-500 company Beckman Coulter (USA) determined the number of neutrophils, monocytes and lymphocytes of venous blood containing molecule L-selectin (CD62L), LFA-1 (CD11a), LFA-3 (CD58), ICAM-1 (CD54), PECAM-1 (CD31), while differentiated them based on morphology. The results is shown that more than 50% of neutrophils and 42% of monocytes are ready to enter the slip phase, while the number of lymphocytes entering this phase is relatively small - 11%. In the phase of strong adhesion and transmigration more than 90% of neutrophils and monocytes were ready to enter, while the number of lymphocytes in blood did not exceed 13%. Correlation analysis showed that in the absence of antigenic stimulation the greatest readiness for the implementation of the slip phase, strong adhesion and the transmigration was observed in neutrophils with 5-segments in the nucleus and polymorphonuclear monocytes. Willingness to transmigrate lymphocytes was relatively small and concerned mainly of medium size lymphocytes and large granular lymphocytes.

Substrate mediated nitridation of niobium into superconducting Nb2N thin films for phase slip study

Here we report a novel nitridation technique for transforming niobium into hexagonal Nb2N which appears to be superconducting below 1K. The nitridation is achieved by high temperature annealing of Nb films grown on Si3N4/Si (100) substrate under high vacuum. The structural characterization directs the formation of a majority Nb2N phase while the morphology shows granular nature of the films. The temperature dependent resistance measurements reveal a wide metal-to-superconductor transition featuring two distinct transition regions. The region close to the normal state varies strongly with the film thickness, whereas, the second region in the vicinity of the superconducting state remains almost unaltered but exhibiting resistive tailing. The current-voltage characteristics also display wide transition embedded with intermediate resistive states originated by phase slip lines. The transition width in current and the number of resistive steps depend on film thickness and they both increase with decrease in thickness. The broadening in transition width is explained by progressive establishment of superconductivity through proximity coupled superconducting nano-grains while finite size effects and quantum fluctuation may lead to the resistive tailing. Finally, by comparing with Nb control samples, we emphasize that Nb2N offers unconventional superconductivity with promises in the field of phase slip based device applications.

Towards quantum phase slip based standard of electric current

An accurate standard of electric current is a long-standing challenge of modern metrology. It has been predicted that a superconducting nanowire in the regime of quantum fluctuations can be considered as the dynamic equivalent of a chain of conventional Josephson junctions. In full analogy with the quantum standard of electric voltage based on the Josephson effect, the quantum phase slip phenomenon in ultrathin superconducting nanowires could be used for building the quantum standard of electric current. This work presents advances toward this ultimate goal.