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Photoresponsive Circular Supramolecular Polymers: Topological Trap and Photoinduced Ring-opening Elongation
摘要： Topological features of one-dimensional macromolecular chains govern the properties and functionality of natural and synthetic polymers. To address this issue in supramolecular polymers, we have synthesized two topologically distinct supramolecular polymers with intrinsic curvature, i.e., circular and helically folded nanofibers, from azobenzene-functionalized supramolecular rosettes. When a mixture of circular and helically folded nanofibers was exposed to UV light, a selective unfolding of the latter open-ended supramolecular polymers was observed as a result of the curvature-impairing internal force produced by the trans-to-cis photoisomerization of the azobenzene. This distinct sensitivity suggests that the topological features of supramolecular polymers define their mechanical stability. Furthermore, the exposure of circular supramolecular polymers in more polar media to UV irradiation resulted in a ring-opening followed by a chain elongation, demonstrating that the circular supramolecular polymer can work as a topological kinetic trap.
关键词： topology,ring opening,azobenzene,supramolecular polymer,photoisomerization
更新于2025-09-23 15:23:52
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Lightweight Design of Multi-Objective Topology for a Large-Aperture Space Mirror
摘要： For a large-aperture space telescope, one of the key techniques is the method for designing the lightweight primary mirror assembly (PMA). In order to minimize the mirror surface error under axial gravity, lateral gravity, and polishing pressure at the same time, a method for topology optimization with multi-objective function combined with parametric optimization is introduced in this paper. The weighted compliance minimum is selected as the objective function to maximum the mirror structural stiffness. Then sensitivity analysis method and size optimization are used to determine the mirror structure parameters. Compared with two types of commonly used lightweight configurations, the new configuration design shows obvious superiority. In addition, the surface figure root mean square (RMS) of the mirror mounted by given bipod flexure (BF) under 1 g lateral gravity is minimized only with a value of 3.58 nm, which proves the effectiveness of the design method proposed in this paper.
关键词： lightweight structure,space mirror,multi-objective topology optimization,sensitivity analysis
更新于2025-09-23 15:23:52
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Design of a distributed compliant mechanism using spring-lever model and topology optimization for piezoelectrically actuated flapping wings
摘要： We present a distributed compliant mechanism, which acts like a transmission between a flapping wing of a micro air vehicle and a laminated piezoelectric actuator. The piezoelectric bimorph actuator is connected in cantilever configuration with the compliant mechanism at its free end. The mechanism takes translational deflection at its input from the piezoelectric actuator to provide angular deflection at its output, which causes flapping. We used spring-lever model and topology optimization to obtain the design of the mechanism. The design of the mechanism has been finalized by analyzing the design considering beam model with geometric nonlinearity. The final mechanism is a planar structure of 1 mm thickness and 40 mm × 24 mm in-plane footprint. The input stiffness of the compliant mechanism is 711 N/m and the output torsional stiffness is 0.014 Nm/rad. The compliant mechanism is tested with a piezoelectric bimorph actuator. The mechanism takes ±1 mm deflection with ±0.2 N block force at 30 Hz as an input and produces ±6° flap angle at 30 Hz as an output. The first fundamental frequency of the mechanism is 391 Hz, which is almost 13 times greater than our assumed wing flapping frequency 30 Hz. The final mechanism is prototyped with a 3D printer using VeroWhitePlus RGD835 material and tested with a piezoelectric bimorph actuator using a bench-top experimental set-up.
关键词： Mechanism,flapping,piezo-actuated flapping mechanism,flapping wing micro air vehicle,spring-lever model,distributed compliant mechanism,topology optimization
更新于2025-09-23 15:22:29
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A methodology for topology optimization based on level set method and its application to piezoelectric energy harvester design
摘要： Compared to a density based procedure, the level set method can acquire a clear boundary without any intermediate density elements, and has become a topical issue in topology optimization studies. In this method, the material properties of the discretized elements are usually defined as the design variables, giving rise to the so called discrete or sawtooth topologies. In this paper, a topology optimization methodology based on level-set method (LSM) and radial basis function (RBF) is proposed. To enhance the performance of the LSM, an improved material interpolation model is proposed. The RBF based post-processor is proposed to smooth the preliminary optimized topology. The proposed method is applied to the topology design of a piezoelectric energy harvester. The effect of different penalization factors is compared and analyzed. The numerical results validate the feasibility and effectiveness of the proposed method.
关键词： Coupled problems,topology optimization,level set method
更新于2025-09-23 15:22:29
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[SEMA SIMAI Springer Series] Recent Advances in Differential Equations and Applications Volume 18 || Optimal Design of Piezoelectric Microactuators: Linear vs Non-linear Modeling
摘要： The main point of this work is the comparison between linear and geometrically non-linear elasticity modeling in the field of piezoelectric actuators fabricated at the micro-scale. Manufacturing limitations such as non-symmetrical lamination of the structure or minimum length scale are taken into account during the optimization process. The robust approach implemented in the problem also reduces the sensitivity of the designs to small manufacturing errors.
关键词： Large displacements,Electrode profile,Piezoelectric actuators,Heterogeneous bimorph,Topology optimization
更新于2025-09-23 15:22:29
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Framework of Gradient Descent Least Squares Regression Based NN Structure for Power Quality Improvement in PV Integrated Low-Voltage Weak Grid System
摘要： This work proposes a novel gradient descent least squares regression (GDLSR) based neural network (NN) structure for control of grid-integrated solar PV (Photovoltaic) system with improved power quality. Here, a single layer neuron structure is used for the extraction of fundamental component (FC) from the load current. During FC extraction, GDLSR based NN structure attenuates harmonic components, noise, DC offsets, bias, notches and distortions from the nonlinear current, which improves the power quality under normal as well as under abnormal grid conditions. This single layer GDLSR-based NN structure has a very simple architecture, which decreases the computational burden and algorithm complexity. Therefore, it is easy in implementation. In this work, the GDLSR based control technique is tested on a single-phase single-stage grid-integrated PV topology with the nonlinear loads. The prime objective of the GDLSR based NN structure is to provide reactive power compensation, power factor correction, harmonics filtering and mitigation of other power quality issues. Moreover, when solar irradiation is zero, then the DC link capacitor and VSC, act as a distribution static compensator (DSTATCOM), which enhances the utilization factor of the system. The proposed system is modelled, and its performances are verified experimentally on a developed prototype in different grid disturbances as well as solar insolation variation conditions, which performances have satisfied the motive of proposed technique as well as the IEEE-519 standard.
关键词： Single-phase Grid,GDLSR based Control,Grid Integration,Single-stage Topology,Solar Energy,Power Quality,DSTATCOM
更新于2025-09-23 15:22:29
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Topology optimization of flextensional piezoelectric actuators with active control law
摘要： This work deals with the concept of Topology Optimization Method (TOM) applied to the design of a flextensional piezoelectric actuator (FPEA) targeting vibration attenuation of its dynamic response. On these actuators the piezoceramic shape is usually fixed and it is more advantageous to optimize the host structure topology. The flextensional actuator is formed by two piezo-ceramic layers that act as a sensor and an actuator coupled with a constant gain active velocity feedback control law (AVFC). The optimization procedure is fully described and implemented, with no simplification for the piezo-ceramic AVFC introduced to the model acts by modifying the damping matrix according to the measurements of the state variables of the system in time-domain. The dynamic equation analyzed throughout the response for the rectangular four-noded finite element (FE) analysis is obtained by the Newmark’s time-integration method, which is applied to the physical equation and to the adjoint equation needed for the sensitivity analysis. A gradient-based optimization method is applied to minimize the response signal energy of the FPEA under a transient mechanical load. Results are obtained for different control gain values to evaluate their influence on the final topology. The optimized host structure material topology for the nc-nodes model is compared with the collapsed nodes (c-nodes) model. In addition, the nc-nodes model is useful to future developments that intends to provide an external circuit to this FPEA structure aiming to intensify the AVFC damping effect.
关键词： Topology Optimization Method,Time domain transient analysis,Flextensional Piezoactuator,Active control law,Non-collapsed piezoelectric nodes
更新于2025-09-23 15:22:29
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Material distributive topology design of UWB antenna using parallel computation of improved BPSO with FDTD
摘要： In this article, the material distributive topology-based design optimization of ultra-wide band (UWB) antenna is proposed by using improved binary particle swarm optimization (BPSO) with finite difference time domain (FDTD) method. In the improved BPSO implementation, the velocity of each particle is calculated based on complete set of bits of particle position vector. The V-shaped transfer function is employed to transform all real values of velocities to values in the interval [0,1]. The fitness function of all the particles in BPSO algorithm are computed parallely by using FDTD simulation. The usage of FDTD and the parallel computation helps in analyzing the broadband frequency characteristics of the antenna with a single simulation run. The return loss of the optimized UWB antenna obtained from FDTD, Computer Simulation Technology (CST) simulation and practical measurement are in good agreement and show good impedance matching.
关键词： UWB antenna,finite difference time domain (FDTD) method,topology optimization,Binary particle swarm optimization (BPSO)
更新于2025-09-23 15:21:21
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Nanophysics in laser-induced cluster systems: topological quantum states in electrical conductivity and features of optical spectraa??theory and experiment for dimensional effects
摘要： Functional physical properties of laser-induced nanocluster structures of different topology in the thin films deposited on solid surface and 3D-crystallic structures by femto-nanoexperiments are studied. Physical basis and specific topology nanocluster view are under our consideration with regard to the functional properties variation (electrophysics + optics) in granular structures. Modeling of electronic energy levels modification due to the topology factors and nonlinear dynamic model for coupled electronic states in the cluster system are carried out. New physical principles for possible application of such structures of topological photonics with different element compositions are discussed.
关键词： Laser-induced nanoclusters,2D–3D-topology structures,Controllable functional properties of the objects,Femto-nanophotonics
更新于2025-09-23 15:21:01
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Switchable All-Optical Flip-Flop and Inverter Operations in Quantum Well Microring Laser
摘要： In this paper, distributed time-varying formation (TVF) control problems for general linear swarm systems with switching interaction topologies are investigated using an adaptive dynamic protocol. First, a TVF control protocol for switching interaction topologies is constructed using the states of neighboring agents. In the protocol, an adaptive controller that employs gain scheduling technique is provided to estimate the coupling weights among agents. Compared with the previous studies on formation control, the desired formation can be specified by piecewise continuously time-varying differentiable vectors, the interaction topology can be switching, and the disadvantage of requiring global information of the interaction topologies is removed in this paper. Then, an algorithm including a feasible formation condition is proposed to determine the gain matrices of the distributed adaptive formation protocol by solving a linear matrix inequality for swarm systems with switching interaction topologies. Moreover, under the designed distributed adaptive formation protocol, sufficient condition for general linear swarm systems with switching interaction topologies to achieve the given TVF is derived using the Lyapunov theory. Finally, numerical simulations are presented to demonstrate the obtained results.
关键词： general linear dynamics,Distributed adaptive protocol,time-varying formation,swarm systems,switching interaction topology
更新于2025-09-23 15:21:01