Decoupling Mechanism Research Articles

Evidence from high frequency seismic waves for the basalt–eclogite transition in the Pacific slab under northeastern Japan

Seismic multi-pathing effects, attributed to a contrast in seismic attenuation between the back-arc mantle wedge and subducted crust, are detected in central Honshu, northeastern Japan. We observe an initial broadened P-wave which is followed by a delayed higher frequency P-wave signal. Their discrepant frequencies are best explained by attenuation effects: delayed P-wave signals travel in the low-attenuation oceanic crust and therefore contain more high frequency components. The time separation between the initial broadened P-waves and the delayed P-wave signals are affected by the seismic velocity in the subducted oceanic crust. We observe systematic variation in the delay times of the later waves indicating an increase in seismic velocity in the oceanic crust (relative to the mantle wedge) at ∼130–150 km depth. High-frequency seismic simulations incorporating mineral-physics derived models show that a 4% Vp increase due to the blueschist decomposition and a 9% Vp increase associated with the (lawsonite, talc)–eclogite transition replicate the observed delay time variation. The blueschist breakdown may occur at a depth of ∼100 km and the (lawsonite, talc)–eclogite transition might be linked with the reduced seismicity level at depths greater than 150 km. Distinct from traditional guided waves, the multi-pathing effects in this study are mainly controlled by attenuation contrast and therefore may not require the oceanic crust to have low velocity and any special decoupling mechanism. The multi-pathing effects offer us another important tool to image subducted oceanic crust below back-arc mantle wedges, especially where guided waves are not observable. In this study, we demonstrate the value of observing and simulating high frequency seismic waves (>20 Hz) in advancing our understanding of subduction zones.

Two-degrees-of-freedom piezo-driven fast steering mirror with cross-axis decoupling capability.

Because mechanical cross coupling between its axes would lead to degradation of the scanning precision of a piezo-driven fast steering mirror (PFSM), a two-degrees-of-freedom (2-DoF) PFSM with a cross-axis decoupling capability, in which 2-DoF flexure hinges are used, is proposed in this work. The overall structure of the proposed PFSM is first introduced and then both static and dynamic models are established analytically; in addition, the decoupling mechanism is described in detail and the low dynamic cross coupling ratios that occur between the two DoFs are shown. Because of the decoupling property of the PFSM, the 2-DoF motion is treated as a combination of two independent one-degree-of-freedom (1-DoF) motions and two independent proportional-integral-derivative controllers are thus used separately in the control of the two DoFs. Based on this control strategy, experiments involving both 1-DoF trajectory tracking and 2-DoF trajectory tracking are implemented. The test results show that the proposed PFSM can achieve the tilt range of ±7 mrad for both axes with the low coupling ratios that are less than 2% (-34 dB), and the bandwidths of both axes are higher than 810 Hz; in addition, the maximal tracking full scale range errors for 1-DoF trajectory tracking and 2-DoF trajectory tracking are less than 0.2% and 1%, respectively, where the larger error of 2-DoF trajectory tracking is mainly caused by the remaining cross coupling between axes.

Decoupling of a Three-Port MIMO Antenna With Different Impedances Using Reactively Loaded Dummy Elements

A simple and efficient decoupling technique for a compact three-port multiple-input–multiple-output antenna is proposed in this letter, and the theory of general design procedures is also introduced. A three-port monopole antenna working at 3.5 GHz is used to demonstrate the decoupling mechanism. The high isolation is achieved by introducing two dummy elements terminated with the reactive loads, which ensures lossless decoupling in the case of ideal elements. The most noteworthy is the radiating elements; all can be matched independently after decoupling since they are well isolated. Measured S -parameters show that the isolation is better than –30 dB within the band of interest. The envelope correlation coefficient is also within the acceptable range. The basic principle provides a promising method for any antenna since the method only relies on the antenna impedances.

Melting and freeze-out conditions of hadrons in a thermal medium

We describe two independent frameworks which provide unambiguous determinations of the deconfinement and the decoupling conditions of a relativistic gas at finite temperature. First, we use the Polyakov-Nambu-Jona–Lasinio model to compute meson and baryon masses at finite temperature and determine their melting temperature as a function of their strangeness content. Second, we analyze a simple expanding gas within a Friedmann-Robertson-Walker metric, which admits a well-defined decoupling mechanism. We examine the decoupling time as a function of the particle mass and cross section. We find evidences of an inherent dependence of the hadronization and freeze-out conditions on flavor, and on mass and cross section, respectively.

Identification of a Stable ZnII–Oxyl Species Produced in an MFI Zeolite and Its Reversible Reactivity with O2 at Room Temperature

AbstractAlthough a terminal oxyl species bound to certain metal ions is believed to be the intermediate for various oxidation reactions, such as O−O bond generation in photosystem II (PSII), such systems have not been characterized. Herein, we report a stable ZnII–oxyl species induced by an MFI‐type zeolite lattice and its reversible reactivity with O2 at room temperature. Its intriguing characteristics were confirmed by in situ spectroscopic studies in combination with quantum‐chemical calculations, namely analyses of the vibronic Franck–Condon progressions and the ESR signal features of both ZnII–oxyl and ZnII–ozonide species formed during this reversible process. Molecular orbital analyses revealed that the reversible reaction between a ZnII–oxyl species and an O2 molecule proceeds via a radical O–O coupling–decoupling mechanism; the unpaired electron of the oxyl species plays a pivotal role in the O−O bond generation process.

An Analytical Model for Fully Grouted Rockbolts with Consideration of the Pre- and Post-yielding Behavior

For rockbolts subjected to tensile loads, there exists a unique local slip–strain relationship as well as a unique bond–slip relationship between rockbolts and rock mass. An analytical model is presented in this study for fully grouted rockbolts under tension, based on the slip–strain relationship of rockbolts. This analytical model takes into account the trilinear bond–slip relationship and the pre- and post-yielding characteristics of the rockbolt material. The reliability and accuracy of the proposed analytical model are verified by experimental pullout tests. Verification studies show that the proposed model is capable of representing the strain and stress distributions of the rockbolts, and the overall load–displacement relationships of rockbolts before and after yielding. Additionally, the model has successfully captured the decoupling mechanism at the bolt–rock interface.

Organisational routines for school improvement: exploring the link between ostensive and performative aspects

This article explores organisational routines introduced in schools and preschools in a Swedish municipality and analyses the relationship between ostensive and performative aspects of improvement work. We take our theoretical point of departure in organisational psychology and an organisation development (OD) perspective by integrating the coupling mechanisms of decoupling, assimilation and accommodation to former research. The analysis shows that the ostensive and performative aspects of organisational routines must be closely connected if improvement initiatives are to impact daily practice. For this to happen, leaders of improvement work must design and operate development programmes that go beyond decoupling by also enabling assimilation and at least partial accommodation. The findings from this study provide a theoretical contribution to understanding the relationship between ostensive and performative aspects of organisational routines; in other words, the ways in which organisational routines play out in practice.

Design and characteristic analysis of an aerostatic decoupling table for microelectronic packaging

This paper presents a novel 2-DOF XY table with high-precision positioning to improve the efficiency and precision of micro-electro-mechanical system packaging. The XY table, which is supported by aerostatic bearings to realize high-precision positioning motion, is directly driven by two linear voice coil actuators. The motion decoupling between the X-and Y-axes is realized through a novel aerostatic decoupling mechanism, by which the mass and inertia of motion parts are reduced significantly. The mechanical structure of the XY table is designed and the decoupling mechanism is studied. Based on the Navier–Stokes equation, the influences of orifice diameter and lubrication gap on the carrying capacity as well the static stiffness of the aerostatic bearings are analyzed. The parameters of the aerostatic bearings are determined by single factor method. Using the finite element method, the static, modal, and transient analyses of the developed positioning table are carried out to investigate the characteristics of the positioning table. The results show that the positioning table provides good performance and can also provide important information for the optimization design and control of this kind of the positioning table.

Improved power decoupling control strategy based on virtual synchronous generator

Virtual synchronous generator (VSG) control scheme, which can be regarded as an extension of droop control, has received much attention from researchers as the introduction of rotational inertia to inverters. This study discusses an active and reactive power decoupling technique for VSGs in microgrid, as an important aspect of VSG. The traditional power decoupling mechanism is initially analysed. Subsequently, the properties of the line impedance at different voltage degrees are compared. Results indicate that the traditional power decoupling method is unsuitable for medium- and low-voltage microgrids. Thus, an improved power decoupling method is proposed. By estimating the voltage at the point of common coupling and tracking their reference values, the output active and reactive power of inverters can perform dynamic decoupling. Furthermore, the stability of the new control structure and selection of relevant coefficients are analysed. The simulation and experimental results verify the enhanced decoupling strategy for VSGs.

Compact Dual-Band Decoupling Structure for Improving Mutual Coupling of Closely Placed PIFAs

In this letter, a dual-band isolation enhancement technique for two closely located dual-band planar inverted-F antennas (PIFAs) is proposed using a compact planar spiral line (PSL) structure. The decoupling structure has the dimensions of less than 0.15λ × 0.1λ and can be flexibly applied to various practical multiple-input multiple–output systems. By employing this structure, two PIFAs (with port distance of 0.1λ) can achieve high isolation better than 20.3 and 26.7 dB within the lower band (2.4–2.483 GHz) and higher band (5.25–5.9 GHz), respectively. Meanwhile, the decoupling mechanism and design requirement of PSL are discussed. Influences of the proposed PSL to the efficiency, gain, and radiation pattern of PIFAs were also studied. Good agreement between the simulated results and measured results is obtained.

Graphene/SiC(0001) interface structures induced by Si intercalation and their influence on electronic properties of graphene

Epitaxial graphene growth on SiC surfaces is considered advantageous in terms of device application. However, the first graphitic layer on SiC transforms to a buffer layer because of strong coupling with the substrate. The properties of several subsequent layers are also significantly degraded. One method to decouple graphene from the substrate is Si intercalation. In the present work, we report observation and analysis of interface structures formed by Si intercalation in between the graphene layer and the SiC(0001) surface depending on Si coverage and influence of these interfaces on graphene electronic structure by means of low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), angle-resolved photoemission spectroscopy (ARPES), and theoretical first-principles calculations. The STM appearance of observed periodic interface structures strongly resembles previously known Si-rich phases on the SiC(0001) surface. Based on the observed range of interface structures we discuss the mechanism of graphene layer decoupling and differences in stability of the Si-rich phases on clean SiC(0001) and in the graphene/SiC(0001) interface region. We also discuss a possibility to tune graphene electronic properties by interface engineering.

Mechanically tunable terahertz graphene plasmonics using soft metasurface

This letter presents a new approach to continuously tune the resonances of graphene plasmons in terahertz soft metasurface. The continuous tunability of plasmon resonance is either unachievable in conventional plasmonic materials like noble metals or requires gate voltage regulation in graphene. Here we investigate a simplest form of terahertz metasurface, graphene nanoribbon arrays (GNRAs), and demonstrate the graphene plasmon resonance modes can be tailored by mechanical deformation of the elastomeric substrate using finite element method (FEM). By integrating the electric doping with substrate deformation, we have managed to tune the resonance wavelength from 13.7 to 50.6 μm. The 36.9 μm tuning range is nearly doubled compared with that by electric doping regulation only. Moreover, we observe the plasmon coupling effect in GNRAs on waved substrate and its evolution with substrate curvature. A new decoupling mechanism enabled by the out-of-plane separation of the adjacent ribbons is revealed. The out-of-plane setup of plasmonic components extends the fabrication of plasmonic devices into three-dimensional space, which simultaneously increases the nanoribbon density and decreases the coupling strength. Our findings provide an additional degree of freedom to design reconfigurable metasurfaces and metadevices.

Understanding decoupling mechanisms of liquid-mixture transport properties through regression analysis with structural perturbation

Optimization of liquid thermophysical properties is important for engineering applications; often achieved by mixing two or more liquids. An important issue is that properties tend to be coupled, which can be problematic if improvement of one property is accompanied by deterioration in another. Therefore, optimization is typically a compromise between properties, and it could be enhanced if they could be decoupled. Such decoupling however first requires an understanding of the common and distinct physical origins of each thermophysical property of interest. Here, we introduce a new approach to gain such understanding, combining molecular-simulation-based structural perturbation with regularized statistical analysis. Considering viscosity and thermal conductivity of a water–glycol mixture as a test-case, we identify the role of structure on each property, and highlight the important role that hydrogen bonding can play in such decoupling.

First-Principles Study of the Role of O2 and H2O in the Decoupling of Graphene on Cu(111).

The structural and electronic properties of graphene coated on a Cu(111) surface can be strongly influenced by the arrangement of adsorbates at the graphene edges. Oxygen and water intercalation at the graphene edges could lead to oxidation and hydrolysis at the graphene/Cu(111) interface, eventually causing decoupling of graphene from the Cu substrate. However, the reaction pathways for oxygen or water (or both) intercalation at the graphene edges are not well understood at the molecular level. Using ab initio density functional theory calculations, we observed a strong hybridization of π orbitals at a zigzag edge of a graphene nanoribbon (GNR) on a bare Cu(111) surface, whereas such hybridization was absent for the corresponding armchair edge under otherwise identical conditions. These results indicate that the edge type influences the oxidation chemistry beneath the GNR. Moreover, we demonstrate that the presence of oxygen species, as well as GNR, facilitates the propagation of H2O. The following decoupling mechanisms are discussed: (i) GNRs with armchair edge configurations on Cu(111) can be decoupled via a sequential reaction that involves O2 dissociation followed by H2O intercalation, whereas (ii) GNRs with zigzag edge configurations on Cu(111) can be decoupled by oxygen intercalation.

A Flexure-Based Kinematically Decoupled Micropositioning Stage With a Centimeter Range Dedicated to Micro/Nano Manufacturing

Precision positioning stages with large strokes and high positioning accuracy are attractive for high-performance micro/nano manufacturing. This paper presents the dynamic design and characteristic investigation of a novel XY micropositioning stage. First, the mechanism of the stage was introduced. The XY stage was directly driven by two linear motors, and the X - and Y -axes kinematic decoupling was realized through a novel flexible decoupling mechanism based on the flexure hinges and preloaded spring. The dynamic model of the XY stage was established, and the influences of the rotational stiffness of the flexure hinge and the initial positions of the working table on the dynamic rotation of the positioning stage were investigated. The stiffness and geometric parameters of the flexure hinges were determined at the condition that the angular displacements of the working table were within ±0.5° with a motion stroke of ±25 mm. Finally the stage performance was investigated through simulation and experiments, and the X - and Y -axes step responses, the rotation angle, and positioning accuracy of the stage were obtained. The results show that the stage exhibits good performance and can be used for micro/nano manufacturing.

Mechanism of inhibition and decoupling of oxygen evolution from electron transfer in photosystem II by fluoride, ammonia and acetate

Ca2+ extraction from oxygen-evolving complex (OEC) of photosystem II (PSII) is accompanied by decoupling of oxygen evolution/electron transfer processes [Semin et al. Photosynth. Res. 98 (2008) 235] and appearance of a broad EPR signal at g=2 (split “S3” signal) what can imply the relationship between these effects. Split signal have been observed not only in Ca-depleted PSII but also in PSII membranes treated by fluoride anions, sodium acetate, and NH4Cl. Here we investigated the question: can such compounds induce the decoupling effect during treatment of PSII like Ca2+ extraction does? We found that F−, sodium acetate, and NH4Cl inhibit O2 evolution in PSII membranes more effectively than the reduction of artificial electron acceptor 2,6-dichlorophenolindophenol, i.e. the action of these compounds is accompanied by decoupling of these processes in OEC. Similarity of effects observed after Ca2+ extraction and F−, CH3COO− or NH4Cl treatments suggests that these compounds can inactivate function of Ca2+. Such inactivation could originate from disturbance of the network of functionally active hydrogen bonds around OEC formed with participation of Ca2+. This inhibition effect is observed in the region of low concentration of inhibitors. Increasing of inhibitor concentration is accompanied by appearance of other sites of inhibition.

Proving as problem solving: The role of cognitive decoupling

This paper discusses the process of proving from a novel theoretical perspective, imported from cognitive psychology research. This perspective highlights the role of hypothetical thinking, mental representations and working memory capacity in proving, in particular the effortful mechanism of cognitive decoupling: problem solvers need to form in their working memory two closely related models of the problem situation – the so-called primary and secondary representations – and to keep the two models decoupled, that is, keep the first fixed while performing various transformations on the second, while constantly struggling to protect the primary representation from being “contaminated” by the secondary one. We first illustrate the framework by analyzing a common scenario of introducing complex numbers to college-level students. The main part of the paper consists of re-analyzing, from the perspective of cognitive decoupling, previously published data of students searching for a non-trivial proof of a theorem in geometry. We suggest alternative (or additional) explanations for some well-documented phenomena, such as the appearance of cycles in repeated proving attempts, and the use of multiple drawings.

A novel flexure-based vertical nanopositioning stage with large travel range.

This paper presents the design of a novel flexure-based vertical (or Z-axis) nanopositioning stage driven by a piezoelectric actuator (PZT), which is capable of executing large travel range. The proposed stage consists mainly of a hybrid displacement amplification mechanism (DAM), a motion guiding mechanism, and a decoupling mechanism. The hybrid DAM with amplification ratio of 12.1 is developed to transfer the transverse motion of the PZT actuator into the vertical motion. The motion guiding mechanism is introduced to avoid cross coupling at the output end. The decoupling mechanism can significantly reduce the cross coupling at the driving end to protect the PZT. The stiffness and dynamics of the proposed stage are improved by these mechanisms. Analytical modeling and finite element analysis (FEA) are then adopted to optimize dimensions of the stage. Finally, a prototype of the stage is fabricated and tested for verification. The results of static and dynamic tests show that the proposed stage is capable of vertical travel range of 214 μm with resolution of 8 nm, and the first two resonance frequencies are 205 Hz and 1206 Hz, respectively. Cross coupling tests under various lateral loads (0 g-1000 g) show that the maximum variances of the lateral and angular cross couplings are less than 0.78 μm and 95 μrad, respectively, indicating good decoupling capability. In addition, the low-profile structure of the stage is well suited to be used in limited vertical space.

A novel voice coil motor-driven compliant micropositioning stage based on flexure mechanism.

This paper presents a 2-degrees of freedom flexure-based micropositioning stage with a flexible decoupling mechanism. The stage is composed of an upper planar stage and four vertical support links to improve the out-of-plane stiffness. The moving platform is driven by two voice coil motors, and thus it has the capability of large working stroke. The upper stage is connected with the base through six double parallel four-bar linkages mechanisms, which are orthogonally arranged to implement the motion decoupling in the x and y directions. The vertical support links with serially connected hook joints are utilized to guarantee good planar motion with heavy-loads. The static stiffness and the dynamic resonant frequencies are obtained based on the theoretical analyses. Finite element analysis is used to investigate the characteristics of the developed stage. Experiments are carried out to validate the established models and the performance of the developed stage. It is noted that the developed stage has the capability of translational motion stroke of 1.8 mm and 1.78 mm in working axes. The maximum coupling errors in the x and y directions are 0.65% and 0.82%, respectively, and the motion resolution is less than 200 nm. The experimental results show that the developed stage has good capability for trajectory tracking.

Parity-dependent State Engineering and Tomography in the ultrastrong coupling regime.

Reaching the strong coupling regime of light-matter interaction has led to an impressive development in fundamental quantum physics and applications to quantum information processing. Latests advances in different quantum technologies, like superconducting circuits or semiconductor quantum wells, show that the ultrastrong coupling regime (USC) can also be achieved, where novel physical phenomena and potential computational benefits have been predicted. Nevertheless, the lack of effective decoupling mechanism in this regime has so far hindered control and measurement processes. Here, we propose a method based on parity symmetry conservation that allows for the generation and reconstruction of arbitrary states in the ultrastrong coupling regime of light-matter interactions. Our protocol requires minimal external resources by making use of the coupling between the USC system and an ancillary two-level quantum system.