Intermediate Mode Research Articles

Global Solutions of the Two-Dimensional Kuramoto–Sivashinsky Equation with a Linearly Growing Mode in Each Direction

We consider the Kuramoto–Sivashinsky equation in two space dimensions. We establish the first proof of global existence of solutions in the presence of a linearly growing mode in both spatial directions for sufficiently small data. We develop a new method to this end, categorizing wavenumbers as low (linearly growing modes), intermediate (linearly decaying modes that serve as energy sinks for the low modes), and high (strongly linearly decaying modes). The low and intermediate modes are controlled by means of a Lyapunov function, while the high modes are controlled with operator estimates in function spaces based on the Wiener algebra.

Modal dynamics in multimode optical fibers: an attractor of high-order modes.

Multimode fibers (MMFs) support abundant spatial modes and involve rich spatiotemporal dynamics, yielding many promising applications. Here, we investigate the influences of the number and initial energy of high-order modes (HOMs) on the energy flow from the intermediate modes (IMs) to the fundamental mode (FM) and HOMs. It is quite surprising that random distribution of high-order modes evolves to a stationary one, indicating the asymptotic behavior of orbits in the same attraction domain. By employing the Lyapunov exponent, we prove that the threshold of the HOMs-attractor is consistent with the transition point of the energy flow which indicates the HOMs-attracotr acts as a "valve" in the modal energy flow. Our results provide a new perspective to explore the nonlinear phenomena in MMFs, such as Kerr self-cleaning, and may pave the way to some potential applications, such as secure communications in MMFs.

Network structure and governance in sport clusters: a mixed methods analysis

ABSTRACT Research question This study contributes to our understanding of how network structures influence cluster governance and consequently cluster outcomes. We investigate the relational structure of cross-sectoral sport clusters and how these influence network governance. Research methods We employed a mixed methods approach, combining qualitative research data and social network analysis (SNA). Forty-nine interviews were conducted with employees from the surfing clusters in Aquitaine (France) and Torquay (Australia). The interview transcripts were subjected to two rounds of coding prior to SNA on an aggregated actor level. Results and findings Findings from both show the core is comprised of five actor types, while five other actor types are peripheral. The French case is a Network Administrative Organisation-governed Network while the Australian case is a Leading Group-governed Network. Implications This article contributes to knowledge on network governance, more specifically on network governance in sport clusters. We extend existing theory on network governance by suggesting a fourth, intermediate mode of network governance, the leading group-governed network. Furthermore, our research provides insights for sport clusters, an under-researched context in interorganisational sport networks.

Process Window for Highly Efficient Laser-Based Powder Bed Fusion of AlSi10Mg with Reduced Pore Formation.

The process window for highly efficient laser-based powder bed fusion (LPBF), ensuring the production of parts with low porosity, was determined by analyzing cross-sections of samples that were generated with laser powers varying between 10.8 W and 1754 W, laser beam diameters varying between 35 μm and 200 μm, and velocities of the moving laser beam ranging between 0.7 m/s and 1.3 m/s. With these parameters, the process alters between different modes that are referred to as simple heating, heat conduction melting (HCM), key-bowl melting (KBM), and deep-penetration melting (DPM). It was found that the optimum process window for a highly efficient LPBF process, generating AlSi10Mg parts with low porosity, is determined by the ratio PL/db of the incident laser power PL and the beam diameter db of the beam on the surface of the bead, and ranges between PL/db = 2000 W/mm and PL/db = 5200 W/mm, showing process efficiencies of about 7–8%. This optimum process window is centered around the range PL/db = 3000–3500 W/mm, in which the process is characterized by KBM, which is an intermediate process mode between HCM and DPM. Processes with PL/db < 2000 W/mm partially failed, and lead to balling and a lack of fusion, whereas processes with PL/db > 5200 W/mm showed a process efficiency below 5% and pore ratios exceeding 10%.

Hydrodynamic model of blood flow in major arteries pulsing in various modes.

Traditionally, the arteries in mammals are viewed as the tubes with elastic wall, whose elasticity could be slowly (during a minute) tuned to change its diameter thereby regulating regional blood supply. Recent findings showed that an artery is a much more sophisticated organ, which can change elasticity of vascular wall within a fraction of a second during a cardiac cycle due to activation of its smooth muscles manifested by generation of arterial action potentials. The rapid variations in elasticity of vascular wall resulted in three basic modes of arterial pulsing: passive, active, and intermediate. The latter is characterized by counteraction of dilation force of arterial pressure and the contractile one of smooth muscle in arterial wall, which can result in seemingly "rigid" artery of constant diameter. The prevalence of any of these forces results in active or passive pulsing modes. Existence of various pulsing modes raises the question of their effect on the main function of blood vessels, i.e., the transport of blood. The aim of this study is to assess the effect of various modes of arterial pulsing on hydraulic impedance of major arteries. The linearized Navier-Stokes equation was employed to develop a model of pulsatile flow of viscous incompressible fluid at small velocity via a conduit artery with the walls of variable or constant elasticity. An essential feature of the developed model is the shape of variable pressure drop applied to the ends of arterial segment, which simulates the real changes in arterial pressure during the heartbeat. Here, it is modeled by periodic (systolic) positive bell-shaped impulses with maxima corresponding to systolic arterial pressure, while the minimal plateau level refers to diastolic arterial pressure. The model assesses the changes in arterial hydraulic impedance during a cardiac cycle relatively to the stable level corresponding to constant blood flow driven by persistent pressure drop. Within intermediate variety of pulsing modes between the active and passive ones, the approximation of rigid arterial segment with infinite elasticity of arterial wall showed that hydraulic impedance in rigid artery is not constant due to inertial properties of the flowing blood. In passive pulsing mode characterized with constant elasticity of arterial wall, the diameter of artery changes in parallel with systolic pressure applied to the ends of arterial segment. At this, the overall change of hydraulic resistance is negative. In active pulsing mode, elasticity of arterial wall varies at different phase shifts relative to arterial pressure due to periodic contractions and relaxation of the smooth muscles in arterial wall. An important feature of active mode is possibility to decrease the hydraulic impedance during the front of arterial pressure. Various experimental modes of artery pulsing can be mathematically simulated. The passive and active modes of pulsing as well as a broad variety of intermediate pulsing modes with various phase shifts between arterial pressure and its diameter result in potency of the arteries to tune its performance in order to meet the regional circulatory requirements. The model showed that active arterial pulsing can diminish the arterial hydraulic impedance and contribute to the work needed for circulation thereby helping the pumping action of the heart.

Stress-Strain and Stress-Relaxation Behaviors of Solution-Coated Layers Composed of Block Copolymers Mixed with Tackifiers.

The relationship between the mechanical properties and the structure of block copolymers mixed with tackifiers whose relative solubility to the respective components of block copolymers differs was examined. Coated layers were prepared by solution coating using a block copolymer composed of polystyrene (PS) and polyisoprene (PI), which forms spherical microdomains of PS in the PI matrix, mixed with three types of tackifiers: aliphatic (C5) resin, aliphatic–aromatic (C5–C9) resin, and rosin ester (RE) resin. Furthermore, the correlation between the changes in the nanostructure and mechanical properties including the stress-relaxation behaviors was clarified by two-dimensional small-angle X-ray scattering measurement. The amount of the PI-bridge conformation in the case of C5 resin is the lowest, resulting in the lowest stress. On the contrary, the largest amount of RE resin was solubilized in the PS phase so that it can be considered that pulling out of the PS chains took place easily. We were able to explain the stress-relaxation behavior by fitting with the three-component exponent functions. The triple exponential decay functions indicate the hierarchy of the structures that are the origins of the ″fast mode″ relating to the local relaxation due to the rotation of the repeating unit of polymer chains; the ″intermediate mode″ of the disentanglement of the mid-PI chains; and the ″slow mode″ relating to, in this particular case, pulling out of the PS chains from the PS sphere.

Alpha particle driven Alfvénic instabilities in ITER post-disruption plasmas

Fusion-born alpha particles in ITER disruption simulations are investigated as a possible drive of Alfvénic instabilities. The ability of these waves to expel runaway electron (RE) seed particles is explored in the pursuit of a passive, inherent RE mitigation scenario. The spatiotemporal evolution of the alpha particle distribution during the disruption is calculated using the linearized Fokker–Planck solver CODION coupled to a fluid disruption simulation. These simulations are done in the limit of no alpha particle transport during the thermal quench, which can be seen as a most pessimistic situation where there is also no RE seed transport. Under these assumptions, the radial anisotropy of the resulting alpha population provides free energy to drive Alfvénic modes during the quench phase of the disruption. We use the linear gyrokinetic magnetohydrodynamic code LIGKA to calculate the Alfvén spectrum and find that the equilibrium is capable of sustaining a wide range of modes. The self-consistent evolution of the mode amplitudes and the alpha distribution is calculated utilizing the wave-particle interaction tool HAGIS. Intermediate mode number (n = 7–15, 22–26) toroidal Alfvén eigenmodes are shown to saturate at an amplitude of up to δB/B ≈ 0.1% in the spatial regimes crucial for RE seed formation. We find that the mode amplitudes are predicted to be sufficiently large to permit the possibility of significant radial transport of REs.

Rational versus Fashionable: Youth Identity, Play and Agency in Namibian Cycling Mobilities

The bicycle has been prescribed as an ‘intermediate mode of transport’ intended as a low-cost approach to address mobility inequality and poverty in sub-Saharan Africa. Within this framework, the bicycle is commonly intended to technologically advance head portage for those who cannot access motorized transport. The singular vision of the bicycle as a load-carrying device has sought to encourage industrious activities over alternative practices, such as play, embodied sensory experiences of mobility and conspicuous consumption for identity performance that are important aspects of youth agency. This article alternatively demonstrates the complexity of mobility and consumer behaviour among young Namibians as they negotiate multiple identities embodied in their mobility. In doing so, the article examines the limitations of youth agency expressed in play, mobility and subject formation, given the normative understandings of gender.

Dripping and jetting of semi-dilute polymer solutions co-flowing in co-axial capillaries

This work is focused on the mechanisms of the dripping and jetting flow modes of viscoelastic semi-dilute polyacrylamide aqueous solutions co-flowing with silicone oil in co-axial capillaries. A phase diagram of the dripping, jetting, and intermediate flow modes is established. It was found that in the dripping mode, the elongation velocity of the filament between the terminal droplet and the inner capillary is controlled solely by the continuous phase rate. At the same time, the decrease in the filament diameter is due to both stretching and outflow of the polymer solution into the terminal droplet. In the jetting mode, the thread diameter was found to evolve in three stages. In the first stage, the average jet velocity increases, whereas in the second and third stages, it becomes constant and corresponds to the velocity of the continuous phase. The transition from the second to the third stage is defined by the appearance of capillary waves resulting in the formation of the beads-on-string structure. In the third stage, the filament diameter between the neighbor beads decreases exponentially and is governed by the relaxation time, which strongly depends on polymer concentration, but does not depend on the continuous phase flow rate. A simple physical model was proposed for describing the evolution of dimensions of filaments and beads during development of jet capillary instability. The universal character of the evolution of filaments and beads sizes, which is independent of concentration of semi-diluted polymer solutions and flow rates of the continuous phase, is revealed.

Coherent phonon-mediated dynamics for an addressable transducer of coupled micro-mechanical resonators

We present coherent phonon-mediated dynamics for addressable motion transfer in a scalable mechanical transducer consisting of three nearest-neighboring coupled micro-cantilevers. To connect two distant cantilevers without direct interaction, two parametric pumps are applied to couple the cantilevers to an intermediate mechanical mode simultaneously. We demonstrate that the distant cantilevers can be coherently coupled even when the intermediate mode is effectively decoupled as a result of two-pump on-resonance coupling. The phonon-mediated coupling is controlled for long-range transferring of both iterating and intra-mode motions while avoid unwanted exciting of the intermediate mode.

Optimal control of grid-connected microgrid PV-based source under partially shaded conditions

Microgrids are gaining increasing attention globally and becoming increasingly powered by photovoltaic (PV) systems, thereby requiring high-efficiency control to function as a microgrid distributed generation unit. Accordingly, this study presents an optimal control of a grid-connected Microgrid PV Source (MPVS) under partially shaded conditions. The objective is to ensure the MPVSs ability to rapidly and precisely deliver the amount of power assigned by the supervisory controller. Thus, MPVS must shift rapidly and smoothly between the maximum and intermediate power point modes. The proposed system is composed of PV array, grid emulators, and two converters coupled to a common DC bus. The control strategy of the boost converter is based on the combination of two algorithms: particle swarm optimization algorithm and the proposed intermediate power point tracker algorithm. The voltage source inverter is controlled to keep the DC bus voltage constant and inject the power to the grid, in which the voltage-oriented control technique is applied and combined with the phase-locked loop algorithm for voltage synchronization. Lastly, all control algorithms are implemented in a DSpace 1104 environment and largely tested under various partially shaded patterns.

Narrow-band, low-sideband plasmonic filter of asymmetric bi-layer metallic nanoslit arrays.

We propose a narrow-band plasmonic filter with low sidebands in the VIS-NIR regime, consisting of two closely spaced, optically thin layers of asymmetric metallic nanoslit arrays that have equal periods but different slit widths. Based on numerical simulations, we clarify that the filtering characteristics in the transmission spectrum is mainly due to intercoupled local plasmon resonance (LPR) modes in the top- and bottom-layer nanoslits and in-plane waveguiding surface plasmon resonance (SPR) modes bound to the top and bottom metal structure layers respectively. The intercoupled LPR modes boost the transmission in a way that the adjoining nanoslits in the top and bottom metal layers act as optical antennas efficiently receiving and emitting light via intermediate plasmon modes, while the in-plane SPR modes at neighboring wavelengths suppress the transmission, so as to shape the passband peak. It's important that asymmetry of the nanoslits helps to improve quality factor of the intercoupled LPR mode and thus to reduce the passband width. Also, asymmetry of the bi-layer metallic nanoslit arrays helps to suppress the sidebands that are relevant to the higher-order in-plane SPR modes at shorter wavelengths. In the spectrum at longer wavelengths, non-resonant transmission of light is suppressed by increased total thickness of the structured metal layers. Furthermore, a two-dimensional version of the filter structure is presented, demonstrating similar filtering characteristics that can be optimally used for arbitrarily polarized or unpolarized light.

Liquid-induced topological transformations of cellular microstructures.

The fundamental topology of cellular structures-the location, number and connectivity of nodes and compartments-can profoundly affect their acoustic1-4, electrical5, chemical6,7, mechanical8-10 and optical11 properties, as well as heat1,12, fluid13,14 and particle transport15. Approaches that harness swelling16-18, electromagnetic actuation19,20 and mechanical instabilities21-23 in cellular materials have enabled a variety of interesting wall deformations and compartment shape alterations, but the resulting structures generally preserve the defining connectivity features of the initial topology. Achieving topological transformation presents a distinct challenge for existing strategies: it requires complex reorganization, repacking, and coordinated bending, stretching and folding, particularly around each node, where elastic resistance is highest owing to connectivity. Here we introduce a two-tiered dynamic strategy that achieves systematic reversible transformations of the fundamental topology of cellular microstructures, which can be applied to a wide range of materials and geometries. Our approach requires only exposing the structure to a selected liquid that is able to first infiltrate and plasticize the material at the molecular scale, and then, upon evaporation, form a network of localized capillary forces at the architectural scale that 'zip' the edges of the softened lattice into a new topological structure, which subsequently restiffens and remains kinetically trapped. Reversibility is induced by applying a mixture of liquids that act separately at the molecular and architectural scales (thus offering modular temporal control over the softening-evaporation-stiffening sequence) to restore the original topology or provide access to intermediate modes. Guided by a generalized theoretical model that connects cellular geometries, material stiffness and capillary forces, we demonstrate programmed reversible topological transformations of various lattice geometries and responsive materials that undergo fast global or localized deformations. We then harness dynamic topologies to develop active surfaces with information encryption, selective particle trapping and bubble release, as well as tunable mechanical, chemical and acoustic properties.

Structure and Microwave Dielectric Properties of Gillespite-Type ACuSi4O10 (A = Ca, Sr, Ba) Ceramics and Quantitative Prediction of the Q × f Value via Machine Learning.

Structure and dielectric properties of gillespite-type ceramics ACuSi4O10 (A = Ca, Sr, Ba) were investigated by crystal structure refinement, far-infrared reflectivity spectroscopy, and microwave dielectric measurements. A series of (CaxSr1-x)CuSi4O10 (0 < x < 1) ceramics with relative permittivities of 5.70-5.82, Q × f values of 20391-48794 GHz (@ ∼ 13.5 GHz), and τf of -46.3 to -38.9 ppm/°C were synthesized. By Ca2+ substitution for Sr2+ at the A-site, the rigid double-layered copper silicate framework remains stable, resulting in the nearly unchanged relative permittivity, while the [(Ca,Sr)O8] dodecahedron undergoes shrinkage and distortion, which is correlated to the changes in the Q × f and τf values. The normalized bond valence sums indicate that almost all ions are rattling, weakening the bond strengths and enlarging the molecular dielectric polarizability. The fitting of far-infrared reflectivity spectra reveals that the local structure changes suppress the intermediate and low-frequency vibrational modes significantly and improves the contribution from electronic polarization to permittivity. Symmetry breaking of the [(Ca,Sr)O8] dodecahedron conforms to the elevated restoring forces acting on the ions and improves the τf value. The large span in Q × f value may have intricate correlations to local structure changes and defects. Machine learning methods were introduced to explore the decisive structural factors for the Q × f value. A Q × f value prediction model correlated with the A-O2 bond length and the variance of A-O bond lengths was established. The Q × f values of isostructural (BaySr1-y)CuSi4O10 ceramics were predicted and verified by experiments.

Cavity magnomechanical storage and retrieval of quantum states

We show how a quantum state in a microwave cavity mode can be transferred to and stored in a phononic mode via an intermediate magnon mode in a magnomechanical system. For this we consider a ferrimagnetic yttrium iron garnet (YIG) sphere inserted in a microwave cavity, where the microwave and magnon modes are coupled via a magnetic-dipole interaction and the magnon and phonon modes in the YIG sphere are coupled via magnetostrictive forces. By modulating the cavity and magnon detunings and the driving of the magnon mode in time, a stimulated Raman adiabatic passage-like coherent transfer becomes possible between the cavity mode and the phonon mode. The phononic mode can be used to store the photonic quantum state for long periods as it possesses lower damping than the photonic and magnon modes. Thus our proposed scheme offers a possibility of using magnomechanical systems as quantum memory for photonic quantum information.

Secure communication with joint resource allocation, relay and jammer selection in OFDM‐based cooperative networks

SummaryThis paper considers an orthogonal frequency division multiplexing (OFDM) based cooperative network, where a source node communicates with a destination node with the help of multiple intermediate nodes, in the presence of an eavesdropper. Each intermediate node is assumed to be able to act as a relay or a jammer to improve the physical layer security. The problem of joint subcarrier allocation, power allocation, and mode selection to maximize the sum secrecy rate is investigated. We first reformulate the problem of subcarrier allocation and intermediate node mode selection as a three‐sided matching game and propose an algorithm that achieves a stable matching. Then, the sum secrecy rate is further improved by proposing a heuristic algorithm to switch the modes of the intermediate nodes. Finally, an iterative power allocation algorithm is proposed. It is verified by simulation results that the proposed algorithm outperforms various benchmark algorithms such as the equal subcarrier allocation algorithm, the pure relay selection algorithm, and the random relay selection algorithm, especially when the transmit power limit is high and the number of intermediate nodes is large.

Pgainsim: an R-package to assess the mode of inheritance for quantitative trait loci in GWAS.

MotivationWhen performing genome-wide association studies conventionally the additive genetic model is used to explore whether a single nucleotide polymorphism (SNP) is associated with a quantitative trait. But for variants, which do not follow an intermediate mode of inheritance (MOI), the recessive or the dominant genetic model can have more power to detect associations and furthermore the MOI is important for downstream analyses and clinical interpretation. When multiple MOIs are modelled the question arises, which describes the true underlying MOI best.ResultsWe developed an R-package allowing for the first time to determine study specific critical values when one of the three models is more informative than the other ones for a quantitative trait locus. The package allows for user-friendly simulations to determine these critical values with predefined minor allele frequencies and study sizes. For application scenarios with extensive multiple testing we integrated an interpolation functionality to determine critical values already based on a moderate number of random draws.Availability and implementationThe R-package pgainsim is freely available for download on Github at https://github.com/genepi-freiburg/pgainsim.Supplementary informationSupplementary data are available at Bioinformatics online.

Fusion layer attention for image-text matching

Image-text matching aims to find the relationship between image and text data and to establish a connection between them. The main challenge of image-text matching is the fact that images and texts have different data distributions and feature representations. Current methods for image-text matching fall into two basic types: methods that map image and text data into a common space and then use distance measurements and methods that treat image-text matching as a classification problem. In both cases, the two data modes used are image and text data. In our method, we create a fusion layer to extract intermediate modes, thus improving the image-text processing results. We also propose a concise way to update the loss function that makes it easier for neural networks to handle difficult problems. The proposed method was verified on the Flickr30K and MS-COCO datasets and achieved superior matching results compared to existing methods.

Mode localization and suppressed heat transport in amorphous alloys

Glasses usually represent the lower limit for the thermal conductivity of solids, but a fundamental understanding of lattice heat transport in amorphous materials can provide design rules to beat such a limit. Here we investigate the role of mass disorder in glasses by studying amorphous silicon-germanium alloy (a-Si$_{1-x}$Ge$_x$) over the full range of atomic concentration from $x=0$ to $x=1$, using molecular dynamics and the quasi-harmonic Green-Kubo lattice dynamics formalism. We find that the thermal conductivity of a-Si$_{1-x}$Ge$_x$ as a function of $x$ exhibits a smoother U-shape than in crystalline mass-disordered alloys. The main contribution to the initial drop of thermal conductivity at low Ge concentration stems from the localization of otherwise extended modes that make up the lowest 8\% of the population by frequency. Contributions from intermediate frequency modes are decreased more gradually with increasing Ge to reach a broad minimum thermal conductivity between concentrations of Ge from $x=0.25$ to $0.75$.

Evaluating the safety integrity of safety systems for all values of the demand rate

The knowledge about the possible influence of demands on the reliability of safety systems comes from a long way back in time. In IEC 61508 this has been taken care of by indicating two different ways to evaluate the safety integrity of SIS: low demand and high demand mode. The main focus of this paper lies in the intermediate and high demand modes. We investigate the effect of the demand on the system hazard rate when the failed states of individual components are detected during a demand. Component failures can then be repaired before the occurrence of the failure of the safety system. The results of this paper show that the system hazard rate exhibits an unexpected behaviour in the intermediate to high demand region. It is also shown that depending on the SIS repair scheme, the use of Probability Failure per Hour (PFH) based on the equations for a continuous demand as proposed in IEC 61508 leads to very conservative results in the high and continuous demand regions. New asymptotic equations are proposed to evaluate the PFH of kooN systems for all values of the demand rate, together with new associated rules for discrimination of the demand regions.