- 标题
- 摘要
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- 实验方案
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Effect of an underdamped vibration with both diagonal and off‐diagonal exciton–phonon interactions on excitation energy transfer
摘要： A numerically exact approach, named as the hierarchical stochastic Schr?dinger equation, is employed to investigate the resonant vibration-assisted excitation energy transfer in a dimer system, where an underdamped vibration with both diagonal and off-diagonal exciton–phonon interactions is incorporated. From a large parameter space over the site-energy difference, excitonic coupling, and reorganization energy, it is found that the promotion effect of the underdamped vibration is significant only when the excitonic coupling is smaller than the site-energy difference. Under the circumstance, there is an optimal strength ratio between diagonal and off-diagonal exciton–phonon interactions for the resonant vibration-assisted excitation energy transfer as the site-energy difference is greater than the reorganization energy, whereas in the opposite situation the most efficient energy transfer occurs as the exciton–phonon interaction is totally off-diagonal.
关键词： underdamped vibration,energy transfer,exciton–phonon interaction,non-Condon effect
更新于2025-09-04 15:30:14
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Design of a real-time two-color interferometer for MAST Upgrade
摘要： A single chord two-color CO2/HeNe (10.6/0.633 μm) heterodyne laser interferometer has been designed to measure the line integral electron density along the mid-plane of the MAST Upgrade tokamak, with a typical error of 1 × 1018 m?3 (～2? phase error) at 4 MHz temporal resolution. To ensure this diagnostic system can be restored from any failures without stopping MAST Upgrade operations, it has been located outside of the machine area. The ?nal design and initial testing of this system, including details of the optics, vibration isolation, and a novel phase detection scheme are discussed in this paper.
关键词： electron density,phase detection,MAST Upgrade,vibration isolation,two-color interferometer
更新于2025-09-04 15:30:14
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Vibration measurement based on multiple Hilbert transform for self-mixing interferometry
摘要： In order to reconstruct the micro-vibration quickly and easily, a novel phase unwrapping algorithm based on multiple Hilbert transform is proposed. Hilbert transform is performed once and three times for self-mixing fringes on different inclined directions, then the unwrapped phase is obtained and the micro-vibration can be reconstructed under weak or even moderate feedback. In this paper, the validity of the proposed algorithm is confirmed by means of simulated signals and demonstrated by several experimental measurements for both harmonic and aleatory target vibration.
关键词： Vibration measurement,Multiple Hilbert transform,Self-mixing interferometry,Phase unwrapping
更新于2025-09-04 15:30:14
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Effect of elastic modulus of cantilever beam on the performance of unimorph type piezoelectric energy harvester
摘要： Piezoelectric energy harvesting is a technique that can utilize ambient vibration energy to generate useful electrical energy, which is promising for powering small-scale autonomous devices such as sensors for wearable, biomedical, and industrial applications. Typically, cantilever-type piezoelectric energy harvesters (PEHs) are operated under resonance condition to achieve the maximum output power at low frequency stimuli. Along with resonance matching, it is also necessary to optimize the PEH configuration with high electromechanical properties for the efficient energy conversion. The purpose of this study is to investigate the effect of the elastic modulus of the passive layer in the cantilever structured PEH on the electromechanical properties and thus harvesting performance. In this regard, two unimorph type PEHs having the identical geometry, piezoelectric properties, and proof mass but with different elastic modulus (55 GPa and 97 GPa) of Ti alloy-based passive layers were fabricated and their output performance was compared under the same acceleration amplitude excitation stimuli. The PEH with the smaller elastic modulus passive layer exhibited almost 53% improvement in the maximum power than that with the higher elastic modulus passive layer, which is attributed to a smaller mechanical damping ratio, higher quality factor, and larger vibration amplitude.
关键词： vibration energy,piezoelectric energy harvesting,cantilever beam,elastic modulus,unimorph type
更新于2025-09-04 15:30:14
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[Solid Mechanics and Its Applications] Piezoelectric Shells Volume 247 (Sensing, Energy Harvesting, and Distributed Control—Second Edition) || Linear/Nonlinear Piezoelectric Shell Energy Harvesters
摘要： Development of energy harvesting technologies, e.g., converting vibration energy to electric energy, has attracted much attention in recent years. Among the proposed technologies, piezoelectric energy harvesters can easily convert the vibration induced energy to useful electric energy with the electromechanical coupling of piezoelectricity. Most piezoelectric energy harvesters have been designed based on various non-shell structures, such as cantilever beams and plates. Electromechanical coupling mechanism and distributed sensing of shell structures, which are commonly used in aerospace, civil and mechanical systems, also have captured researchers’ attention for decades. However, most of them only considered the signal generations in the open-circuit condition and the sensing theory becomes impractical when it is used to power electric devices whose impendence can no longer be ignored. Therefore, the output energy across a resistive load in a closed-circuit condition for the shell energy harvesters should be exploited. Accordingly, this study focuses on a development of a generic piezoelectric shell energy harvesting mechanism that can be simplified and applied to many linear/nonlinear shell and non-shell distributed energy harvesters.
关键词： shell structures,energy harvesting,electromechanical coupling,vibration energy,piezoelectric
更新于2025-09-04 15:30:14
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Dynamic Characteristics of Satellite Solar Arrays under the Deployment Shock in Orbit
摘要： Understanding the dynamic characteristics of solar arrays is important for satellite structural design and attitude control design. Considerable theoretical researches have been carried out towards this problem, but they have not been supported by actual orbit data from outer space yet. In this paper, the on-orbit vibration characteristic data of solar arrays under the deployment shock are measured by using vibration measurement apparatuses based on structural strain. With these valuable experimental data, more eigenfrequencies of the solar arrays in the microgravity environment are obtained, and the prediction that the vibration of solar arrays will have larger amplitude and longer decay time under vacuum conditions is veri?ed. Moreover, by comparing the eigenfrequency of main vibration under the space condition with that under the ground condition, the accurate value of the system damping ratio is gained, which has an important guideline signi?cant for the structural design of solar arrays.
关键词： solar arrays,deployment shock,on-orbit data,vibration measurement,dynamic characteristics
更新于2025-09-04 15:30:14
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Dual-loop Controller Design Considering Robust Vibration Suppression in Piezo-actuated Stage Systems
摘要： This paper presents a controller design approach considering robust vibration suppression against resonant frequency variations in piezo-actuated systems. In piezo-actuated systems, the improvement of suppression performance with respect to external disturbances and nonlinearities such as hysteresis and creep by the expansion of feedback control bandwidth is indispensable for achieving high-precision positioning. The vibration suppression approach is a key technology for the expansion of bandwidth. From a practical point of view, a minor feedback loop including a simple compensator with a few parameters to increase the design freedom is added to the general feedback control system. In the minor-loop design, the reduction of sensitivity gain at around the resonant frequencies is considered to suppress the residual vibration of the references and disturbances, and the loop-shaping approach based on the frequency domain is adopted to provide an intuitive and practical design guideline. A major-loop for an augmented plant, including the minor-loop, is designed by considering the system stability, servo bandwidth, and settling performance. The proposed approach is veri?ed by conducting experiments using a commercial piezo-actuated stage system.
关键词： loop-shaping,vibration suppression,piezo-actuated stages,robust property,high-precision positioning
更新于2025-09-04 15:30:14
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Feasibility of PCB-Integrated Vibration Sensors for Condition Monitoring of Electronic Systems
摘要： The increasing complexity of electronics in systems used in safety critical applications, such as for example self-driving vehicles requires new methods to assure the hardware reliability of the electronic assemblies. Prognostics and Health Management (PHM) that uses a combination of data-driven and Physics-of-Failure models is a promising approach to avoid unexpected failures in the field. However, to enable PHM based partly on Physics-of-Failure models, sensor data that measures the relevant environment loads to which the electronics is subjected during its mission life are required. In this work, the feasibility to manufacture and use integrated sensors in the inner layers of a printed circuit board (PCB) as mission load indicators measuring impacts and vibrations has been investigated. A four-layered PCB was designed in which piezoelectric sensors based on polyvinylidenefluoride-co-trifluoroethylene (PVDF-TrFE) were printed on one of the laminate layers before the lamination process. Manufacturing of the PCB was followed by the assembly of components consisting of BGAs and QFN packages in a standard production reflow soldering process. Tests to ensure that the functionality of the sensor material was unaffected by the soldering process were performed. Results showed a yield of approximately 30 % of the sensors after the reflow soldering process. The yield was also dependent on sensor placement and possibly shape. Optimization of the sensor design and placement is expected to bring the yield to 50 % or better. The sensors responded as expected to impact tests. Delamination areas were present in the test PCBs, which requires further investigation. The delamination does not seem to be due to the presence of embedded sensors alone but rather the result of a combination of several factors. The conclusion of this work is that it is feasible to embed piezoelectric sensors in the layers of a PCB.
关键词： PVDF-TrFE,piezoelectric sensors,Prognostics and Health Management (PHM),condition monitoring,electronic systems,PCB-integrated vibration sensors
更新于2025-09-04 15:30:14
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Drying process of water in a Nafion membrane embedded in the fuel cell analyzed by coherent anti-Stokes Raman scattering spectroscopy
摘要： A coherent anti-Stokes Raman scattering (CARS) spectroscopy system was designed to measure the transient behavior of the humidi?cation of a Na?on membrane used in a polymer electrolyte fuel cell (PEFC). We observed a variation in the intensity of the O–H stretching vibration peak of water during dry and wet gas ?ow. From our measurements, we found that our system showed a high time resolution enough to measure humidi?cation variation in a Na?on membrane in a PEFC. The high acquisition rate revealed the nonequilibrium process of the dehydration or hydration of the Na?on membrane through the temporal variation in the intensity of the O–H stretching vibration peak. The peak consisted of three peaks, suggesting that water molecules hydrated with di?erent bonding energies. The transient behavior of the peaks was probably attributed to the motion of hydration molecules in the proton channel. ? 2018 The Japan Society of Applied Physics
关键词： CARS spectroscopy,O–H stretching vibration,hydration,Na?on membrane,PEFC
更新于2025-09-04 15:30:14
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A reversible fluorescent probe for directly monitoring protein-small molecules interaction utilizing vibration-induced emission
摘要： The interactions between proteins and small molecules play an important role in the regulation of various cellular processes and modern drug discovery. Herein, we have developed a novel strategy for real-time monitoring the protein-ligand interaction based on vibration-induced emission (VIE) mechanism. These results demonstrated that the probe DPAC-DB could directly visualize the binding process in biotin-avidin system, which was undisturbed to other environmental stimuli, such as pH, interference species and temperature. Furthermore, the unique VIE effect caused by dramatic and reversible intramolecular vibrations enabled our strategy possible to build up the bio-logic gate. This method to efficiently control the emission of VIE-based probe through the reversible noncovalent protein-small molecules interactions opens new avenues for the development of potent protein pharmaceuticals and small molecule drugs.
关键词： Reversible,Vibration-induced emission (VIE),Biotin-avidin system,Bio-logic gate
更新于2025-09-04 15:30:14