Coupling Structure Research Articles

Angle of Attack Effects on the Induced Structural Loads of a Weapons Bay

AbstractAero-acoustic analysis was conducted on a weapons bay numerical model with doors, incorporating radar cross section reduction features. The effect of the angle of attack on the aero-acoustic response of the cavity was analysed at Mach numbers of 0.85 and 1.20. It was found that incidence influenced both mean-flow features and acoustic response. Further, linear and angular accelerations induced by the flow on the bay doors revealed potential adverse fluid–structure coupling when the results were compared with modal analysis. Again, the angle of attack did influence the aeroacoustic effects on the cavity door structure.

Kinematics Analysis and Oil Film Lubrication Characteristics in the Piston–Cylinder Interface of a Bent-Axis-Type Piston Motor

Hydraulic piston motors are characterized by their excellent starting performance, high transmission torque, good sealing performance, compact design, and lightweight. These attributes make them highly applicable in fields such as construction machinery and marine applications. With the advancement of hydraulic transmission technology, higher performance requirements have been set for hydraulic motors. While extensive research has been conducted on hydraulic pumps, studies focusing on the performance of hydraulic motors remain relatively limited. Therefore, this paper is novel in that, based on the motion and force conditions of the piston, it differs from previous research on swashplate-type machinery by considering the complex structure of the bent-axis motor; it employs a micro finite element method to analyze the oil film characteristics at the piston–cylinder interface in a bent-axis piston motor, the structural changes in the piston assembly in the bent-axis motor are comprehensively considered, and a fluid–structure coupling model for the piston–cylinder interface is established. The leakage and viscous friction power loss equations for the piston–cylinder interface are derived. Simulation analyses are conducted using MATLAB R2016a to reveal the variation patterns of leakage and viscous friction power loss under different operating conditions and structural parameters, providing valuable insights for the operation analysis, energy loss evaluation, structural design optimization, and engineering applications of bent-axis piston motors.

Novel Designs of Magnetic Coupled Structure With 360° Rotation Misalignment Tolerance for AUVs’ Wireless Charging System

Novel Designs of Magnetic Coupled Structure With 360° Rotation Misalignment Tolerance for AUVs’ Wireless Charging System

A numerical simulation research on fish adaption behavior based on deep reinforcement learning and fluid–structure coupling: The refuge–predation behaviors of intelligent fish under varying environmental pressure

The study of fish swimming behavior and locomotion mechanisms holds substantial scientific and engineering significance. With the rapid progression of artificial intelligence, the integration of artificial intelligence with high-precision numerical simulation methods presents a novel and highly efficient tool for investigating fish behavior. In this paper, we proposed a fish perception model that more closely reflects natural logic. By introducing the individual vision and partially visibility model, a physics-based visual system that mirrored the sensory capabilities of live fish was developed. Furthermore, through the construction of a flow vision using conventional neural networks, we enhanced the intelligent fish's ability to detect unsteady hydrodynamic parameters via numerical lateral line. The validity of the new model was demonstrated through experiments, which the intelligent fish hunts complex moving targets in unsteady flow. Finally, we applied the model to study the refuge/predation behaviors of coral reef fish under varying unsteady flow pressures. The results indicated that swimming capabilities significantly impact fish survival strategies in high flow velocity, highly unsteady hydrodynamic environments, shaping distinct evolutionary decision-making traits. These insights may help to understand the niche competition mechanisms of fish in different flow conditions.

Characterization of Wind Turbine Blade Deformation and Wake Flow Field with Different Numbers of Lay-Up Layers

The change in the composite lay-up method affects the blade stiffness, which in turn affects the structural dynamic and aerodynamic characteristics, but the influence law is not yet clear. In this paper, two-way fluid–structure coupling is used to study wind turbine blades with different numbers of lay-up layers. The analysis results show the following: (1) With the increase in the number of pavement layers, the maximum deformation of the blade tip decreases, the magnitude of the decrease also decreases gradually, and the growth trend of deformation along the blade spreading direction is gradually flattened. (2) The maximum stress–strain of the root of the blade gradually decreases, the tip of the blade is the opposite of the blade, the unevenness of the distribution of the stress–strain of the surface of the blade is gradually slowed down, and the concentration area is shifted back. (3) The different numbers of pavement layers affect the turbulence intensity of the blade in the flow field space. Herein, the spatial distribution trend of turbulence intensity in the flow field of wind turbine blades with different numbers of layers is basically the same, and the trend of turbulence intensity changes is gentle when the number of layers is increased. (4) The amount of the tip vortex in the wake stream of the wind turbine decreases, and the decay rate of the center vortex increases. A reasonable lay-up scheme can improve the deformation and stress of the blade, extend the service life of the blade, promote airflow mixing, and enhance the energy conversion efficiency.

Investigation of certain physical properties of Co2MnGe Heusler: DFT calculation and Monte Carlo simulation

In this work, we have used the first-principles method based on Density Functional Theory (DFT) to study the electronic structure, density of states, band structure, and exchange couplings of the Heusler compound Co₂MnGe. This material's magnetic properties were investigated through the use of Monte Carlo simulations (MCS) in the framework of a three-dimensional Ising model. In particular, we evaluated the magnetization, magnetic susceptibility, specific heat, and Binder cumulant, and calculated some critical exponents of the system. The results showed that the Heusler compound Co₂MnGe exhibits a semi-metallic behavior and undergoes a transition from the ferromagnetic to the paramagnetic phase at a critical temperature Tc ≈ 990 K, in good agreement with the experimental data. The values of the calculated critical exponents are very similar to those known for the three-dimensional Ising model: α ≈ 0.1191, β ≈ 0.3188, γ ≈ 1.2526, and ν ≈ 0.5526, verifying the universal behavior of the studied system.

Triband Metamaterial Absorber Based on a Three-Ring Coupled Structure

Triband Metamaterial Absorber Based on a Three-Ring Coupled Structure

Development and invitro testing of an orthodontic miniscrew for use in the mandible.

Temporary anchorage devices (TADs) have been successfully used in the maxilla. However, in the mandible, lower success rates present achallenge in everyday clinical practice. Anew TAD design will be presented that is intended to demonstrate optimization of the coupling structure as well as in the thread area for use in the mandible. Three TADs were examined: (A)Aarhus® system (68.99.33 A, Medicon, Tuttlingen, Germany), (B)BENEfit® orthodontic screw (ST-33-54209; PSM Medical, Gunningen, Germany) and(C) anew design with atwo-part screw thread. The TADs were inserted into artificial bone blocks after predrilling to test primary stability. To test the fracture stability, the TADs were embedded in Technovit® 4004 (Heraeus Kulzer, Wehrheim, Germany) and torsional loaded at an angle of 90° until fracture. The threshold torque values occurring were recorded digitally. The statistical evaluation was carried out using the Kruskal-Wallis test with aposthoc test according to Bonferroni (p < 0.05). The following values were measured for the insertion torque: A: 33.7 ± 3.3 Ncm; B: 57.1 ± 8.4 Ncm; C: 34.2 ± 1.4 Ncm. There were significant differences between A-B andB-C. The measured values for the fracture strength were as follows: A: 46.7 ± 3.5 Ncm; B: 64.2 ± 5.1 Ncm; C: 55.4 ± 5.1 Ncm. Significant differences were found between all groups. The adapted screw design has no negative influence on primary and fracture stability. Whether the design has apositive effect on the success rates in the mandible must be clarified in further clinical studies.

Fine‐Tuning Thickness‐Dependent Molecular Aggregation for Enhanced Performance in Semitransparent Organic Photovoltaics

Semitransparent organic photovoltaics (ST‐OPV) exhibit tremendous potential for application in integrated photovoltaic architecture. The reduction of the ratio of wide‐bandgap donors in the active layer is crucial for enhancing both the power conversion efficiency (PCE) and the average visible light transmittance (AVT), which are key performance indicators for ST‐OPV. Herein, successful suppression of the thickness‐dependent transition from H‐aggregates to J‐aggregates in PM6 films was achieved through temperature control, significantly improving charge transport and extraction efficiency, thereby markedly enhancing the PCE of sequential processed pseudo p‐i‐n devices employing the Y6 acceptor. With ≈30% AVT maintained, the PCE increases from 6.50% to 11.10%, while the light utilization efficiency rises from 1.98% to 3.40%. Unlike previous studies primarily focused on optical coupling structure design, this research underscores the precise control of molecular aggregation behavior in the active layer material, demonstrating the innovativeness of material and structural design and offering new avenues and methodologies for the development of future semitransparent photovoltaic materials.

Modeling of the tensioned membrane backed by a variable-shape cavity and research on acoustic characteristics

The drum-type muffler comprises a rigid back cavity and a tensioned membrane, which utilizes the radiation sound field of a membrane and the superposition effect of the enclosed sound field to achieve noise reduction. However, most previous studies have been focused on idealized models, with little research on the sound radiation power from a membrane concerning a variable-shape back cavity. This article aims to establish a membrane vibration-acoustic model and investigate the impact of irregular shape and pre-tension conditions on the radiated sound energy. The microunits on the surface of the membrane and the pressure of the sound field are represented as cosine Fourier series. The variable-shape cavity is converted into a normal one by employing the coordinate transformation method. The analytical model of the coupling structure composed by a membrane and the enclosed sound fields is developed based on the energy principle. The acoustic and vibration characteristics of the membrane are solved based on the Rayleigh integral equation. This study also considers the difference in sound insulation performance between the thin plate and the membrane. The analytical results are compared with Finite Element Analysis (FEM) to verify the correctness of the theoretical model. In addition, based on the LMS Simcenter measurement system, experiments are designed to predict the sound pressure on both sides of the membrane. The test results closely correspond with the theoretical calculation results, which confirms the practicality of the theoretical approach.

Structural Coupling System for Cognitive Modeling in Immersive VR Assessment Tasks

Unilateral spatial neglect (USN) is a disorder characterized by the inability to attend to the space opposite the cerebral hemisphere lesion, significantly hindering daily activities. Due to the complex neural circuitry of the brain, understanding the mechanisms of USN has proven challenging. In clinical settings, the Behavioral Inattention Test (BIT), a paper-based examination, is commonly used to assess USN. However, improved scores on this test do not necessarily guarantee functional improvement, as it solely evaluates performance in a two-dimensional space. To address this limitation, various approaches utilizing information and communication technology (ICT) and measurement devices in rehabilitation engineering have been proposed. However, related studies have focused on analyzing motor responses to specific sensory stimuli, and the assessment measures often fail to capture a patient’s symptoms in dynamic environments. Therefore, this study proposes a methodology for modeling human spatial cognition. This cognitive architecture utilizes a structural coupling system that integrates parameters from multiple computational intelligence subsystems. In this study, we constructed a simulation environment capable of replicating the movements of patients with USN using empirical data collected from actual experiments. Furthermore, in this simulation environment, we developed patient agents that incorporated the proposed cognitive architecture. The experimental results suggest that hypothesis testing concerning attention mechanisms can be applied through the performance of patient agents within the simulation environment.

Demonstration of ultra-compact and low-loss 2 × 2 silicon thermo-optic switches based on a mode-conversion nanobeam cavity

Optical switch is an essential component in integrated photonic circuits. A mode-conversion nanobeam cavity (MCNC) coupled with two waveguides has been employed to realize ultra-compact and low-loss 2 × 2 thermo-optic switches in silicon-on-insulator. This system can exhibit either Fano or Lorentzian lineshape in transmission spectra, dependent on the coupling structure. It has a low dropping loss, and two outputs are in the same direction, owing to the unidirectional coupling between the resonant mode and bus waveguides. Here, we have demonstrated a high-performance 2 × 2 Fano switch with a bandwidth of 5.2 nm and a footprint of only 35.5 × 1 µm2. The insertion loss (IL) and crosstalk (CT) are 0.7 dB and −54.1 dB in the bar state, respectively, while the IL and CT are 0.9 dB and −17.4 dB in the cross-state, respectively. In addition, 2 × 2 optical switches with a Lorentzian transmission lineshape have also been realized and then applied to construct a four-channel reconfigurable optical add-drop multiplexer (ROADM). Through thermal tuning, the ROADM has achieved a channel spacing of 200 GHz or 400 GHz, with an inter-channel CT below −12.3 dB or −17.2 dB, respectively. To our knowledge, we have reported the first demonstrations of 2 × 2 Fano switch and ROADM based on MCNCs. The proposed 2 × 2 switches will find potential applications in advanced photonic integrated circuits.

A semiotic lifeworld. Semiotics and phenomenology: Peirce, Husserl, Heidegger, Deleuze, and Merleau-Ponty

Abstract If we think of cognition and experience from the enactivist idea of a structural coupling between organism and environment, we see that this environment is first and foremost a semiotic environment, crowded with objects, norms, habits, institutions, and artefacts that shape our minds and represent the background of our perception of the world. This semiotic environment, which goes far beyond the opposition between nature and culture, (See Paolucci 2021. Cognitive semiotics: Integrating signs, minds, meaning, and cognition. Berlin: Springer: ch. 1.) is a semiotic lifeworld that is important to compare with the classic idea of lifeworld coming from phenomenology. In this paper, (i) we will first start with a comparison of the semiotic Lebenswelt and the phenomenological Lebenswelt; (ii) we will follow the construction of the semiotic lifeworld coming from Peirce’s Anti-Cartesian essays; (iii) we will make a deep comparison between the phenomenology coming from Peirce (phaneroscopy) and the phenomenology coming from Husserl, Heidegger, and Merleau-Ponty; (iv) we will show how these very same principles also ground structuralism; (v) we will show how this new semiotic lifeworld grounded on phaneroscopy is neither pre-logical nor pre-categorial. Rather, it is founded on the primacy of “telling” over “showing,” and on the primacy of discourse over perception.

Construction and Multifunctional Photonic Applications of Light Absorption-Enhanced Silicon-Based Schottky Coupled Structures.

To expand the detection capabilities of silicon (Si)-based photodetector and address key scientific challenges such as low light absorption efficiency and short carrier lifetime in Si-based graphene photodetector. This work introduces a novel Si-based Schottky coupled structure by in situ growth of 3D-grapheneand molybdenum disulfide quantum dots (MoS2 QDs) on Si substrates using chemical vapor deposition (CVD) and plasma-enhanced chemical vapor deposition (PECVD) techniques. The findings validate the "dual-enhanced absorption" effect, enhancing the understanding of the mechanisms that improve optoelectronic performance. The synergistic effect of 3D-graphene's natural nano-resonant cavity and MoS2 QDs enhances light absorption efficiency and extends carrier lifetime. Introducing MoS2 QDs broadens and intensifies the built-in electric field, promoting the separation of photogenerated electrons and holes. The photodetector exhibits a wideband light response in the wavelength range of 380-2200nm. It stably outputs photocurrent under high-frequency (1 kHz) modulated laser (2200nm), with a responsivity (R) of 40mAW-1 and detectivity (D*) of 1.15×109 Jones. Photodetectors show the ability to process and encrypt complex binary signals and achieve versatility in "AND" gate and "OR" gate logic operations, as well as image sensing (240×200 pixels).

Mode entanglement and isospin pairing in two-nucleon systems

Abstract In this study, we explore the entanglement and correlation in two-nucleon systems using isospin formalism. With the help of Slater decomposition, we derive analytical expressions for various entanglement measures. Specifically, we analyse the one- and two-mode entropies, mutual informations, and a basis-independent characteristic known as the one-body entanglement entropy.&amp;#xD;&amp;#xD;To understand the impact of pairing, we consider interactions involving isovector and isoscalar L=0 pairing terms. Our findings show that certain pairing interactions can maximize one-body entanglement entropy of ground states when both total angular momentum and total isospin have zero projections.&amp;#xD;&amp;#xD;We provide numerical examples for the sd shell and explore the mutual informations in LS coupled and jj coupled single-particle bases. We find that the shell structure and angular momentum coupling significantly impact the measures of entanglement. We outline the implications of conserving angular momentum and isospin on one-mode entropies, irrespective of particle number.

Control design for convection‐reaction systems with storage effects and positive relative degree

AbstractOne‐dimensional distributed‐parameter systems consisting of several convection‐reaction equations, which are distributedly coupled with a reaction equation, are considered. To solve the open‐loop control problem for these kind of systems, an inversion‐based approach is proposed. Along the common characteristic projection, the system can be reduced to a single partial differential equation (PDE) whose boundary conditions (BCs) result from the particular choice of the output to be tracked. The solution of this latter equation constitutes the basis of the control design. The particular properties of the scalar boundary value problem (BVP) to be solved depend on the coupling structure of the originally given convection‐reaction system. While in most cases the output has a relative degree of zero, for practical applications a relative degree of one is of particular interest. In this case, the obtained scalar BVP which describes the internal dynamics, possesses the structure of an infinite‐dimensional differential‐algebraic equation (DAE). Within the paper, the properties of the solution of both problems are discussed from a system analytical point of view.

Design of a CPW-based SSPP band-pass filter with reflectionless notch

Abstract This work proposes a band-pass filter (BPF) with a reflectionless notch based on spoof surface plasmon polaritons (SSPPs), utilizing interdigital coupling structures and novel transmission line unit cells. This filter efficiently transmits signals within the 0.67 GHz −4.06 GHz frequency range. By analyzing the equivalent LC circuit of the novel transmission line unit cell, its dispersion relation is derived using microwave network theory, with a cutoff frequency of 4.11 GHz. By comparing its dispersion relation with that of the conventional transmission line unit cell, the miniaturization capability of the proposed unit cell can be verified. In the BPF, loading a zigzag groove onto the central transmission line can be equivalently represented as an interdigital coupling structure, generating a stopband in the low-frequency range near 0 GHz. By deriving and analyzing its S-parameters, it is shown that the bandwidth of the low-frequency stopband can be flexibly adjusted by modifying the geometric dimensions of the zigzag groove. Additionally, loading another set of interdigital coupling structures onto the transmission line generates a notch at its resonant frequency of 3.4 GHz. It is noteworthy that in this configuration, the interdigital coupling structures along with the central transmission line can be represented equivalently as a set of CPW antennas. At the resonant frequency, the atructure radiates signals into free space, forming a reflectionless notch. Based on the simulations, a physical filter was fabricated and tested, showing excellent agreement between simulations and measurements.

Influence of the variation of concrete properties in determining the vibration transmission index Kij

In this work, the influence of the modulus of elasticity, the loss factor and the density of reinforced concrete on the vibration transmission index ([Formula: see text]) of a reduced concrete bench was evaluated. An experimental modal analysis based on the Operating Deflection Shape (ODS) methodology is carried out on a reinforced concrete slab (1.20 × 0.80 × 0.20 m) supported on four concrete pillars, applying four sources of distinct impacts: mallets of 1 and 4 kg, impact machine and one person jumping. The experimental results served to validate the finite element bench model (FEM) considering both the first four modes of slab vibration and the adjustment of the elasticity and shear modulus, the loss factor and the density of the concrete using the NSGA genetic algorithm-II. The [Formula: see text] index between the slab and the columns was determined experimentally, numerically and analytically, according to the Gerretsen model. The FEM model showed a percentage difference in the frequencies of the vibration modes less than 10% concerning the tests for the [Formula: see text] index. The influence of density and the modulus of elasticity mainly in the direction perpendicular to the plane of the structure modify the values of the frequencies of the vibration modes by up to 10% without interfering in the modal forms of the structure. In addition, the internal loss factor alters the amplitude of the [Formula: see text] results by an average of 10 dB. Finally, it is shown that the stiffness varies according to the orthotropy of the material. It was possible to conclude that the computational model showed good convergence in results ([Formula: see text]%) when compared with the [Formula: see text] experiments, with the same varying along the frequency, different from what is proposed in the analytical and normative models. This fact proves the hypothesis raised that structural couplings in practice generate significant interference in the results, as happens in residential buildings, with the test bench being an important experiment for initial predictions with little interference from energy transmission to the environment.

Source–Sink Structural Coupling Within Forest-Clustered Landscapes Drives Headstream Quality Dynamics in Mountainous Sub-Watersheds: A Case Study in Chongqing, China

Water environment quality is profoundly driven by a series of landscape characteristics. However, current knowledge is limited to the independent response of water quality to single landscape elements; this has led to poor knowledge of the potential role of structural coupling within landscapes in driving water quality changes, especially in those agroforestry-mixed mountainous watersheds with highly embedded forest-clustered landscapes and abundant headstreams. Given this fact, this study aims to evaluate whether and how the source–sink coupling structure of forest-clustered landscapes systematically drives headstream quality dynamics. We first systematically assessed the association pattern of source and sink structures within forest-clustered landscapes, and then innovatively proposed and constructed a functional framework of source–sink coupling structure of landscapes across 112 agroforestry-mixed mountainous sub-watersheds in Chongqing, China. On this basis, we further evaluated the driving pattern and predictive performance of the source–sink coupling structure of landscapes behind headstream quality dynamics. We report three findings: (1) headstream quality varied across agroforestry-mixed sub-watersheds, mapping out the source–sink structures and functions of landscapes; (2) there was significant functional coordination between source–sink structures of the forest-clustered landscapes, which significantly drove headstream quality dynamics; (3) the structural positioning and differences of the forest-clustered landscapes along the multivariate functional axes directly corresponded to and predicted headstream quality status. These findings together highlight a key logic that the response of water quality dynamics to landscapes is essentially that to the functional coupling between the source–sink structures of landscapes, rather than the simple combination of a single landscape contribution. This is the first study on the landscape–runoff association from the perspective of source–sink structural coupling, which helps to deepen understanding of the correlation mechanism between water dynamics and landscape systems, and provides a new functional dimension to the development of future landscape ecological management strategies from a local to a global scale.

Impact of U-shaped waveguide structures on optical comb generation in microresonator systems

In the research of soliton microcombs, the pump energy conversion efficiency (ECE) of the microcomb is an important parameter. However, in traditional microresonator systems, the ECE is only a few percent. Researchers have enhanced it by introducing additional feedback coupling structures or composite cavity structures into the microresonator system to suppress the output of pump light in the soliton generation region. The additional structures may affect the output comb characteristics of the system, but most articles do not delve into this issue, which hinders the practical application of high-efficiency soliton microcombs. In this paper, we establish rate equations describing the nonlinear dynamics of a microresonator with a U-shaped waveguide feedback coupling structure (coupled-cavity system, CCS), and numerically simulate and conduct steady-state analysis of the simulation results to obtain the influence of the U-shaped waveguide on the CCS’s output comb characteristics. Then we optimize the structural parameters of the CCS reducing the parametric oscillation threshold of the pump by more than 50%, while increasing the ECE to over 25% when the optical field in the microresonator propagates in the form of a single soliton.