A method is presented to determine power dissipation in one-dimensional piezoelectric slabs with internal losses and the resulting temperature distribution. The length of the slab is much greater than the lateral dimensions. Losses are represented using complex piezoelectric coefficients. It is shown that the spatially non-uniform power dissipation density in the slab can be determined by considering either hysteresis loops or the Poynting vector. The total power dissipated in the slab is obtained by integrating the power dissipation density over the slab and is shown to be equal to the power input to the slab for special cases of mechanically and electrically excited slabs. The one-dimensional heat equation that includes the effect of conduction and convection, and the boundary conditions, are then used to determine the temperature distribution. When the analytical expression for the power dissipation density is simple, direct integration is used. It is shown that a modified Fourier series approach yields the same results. For other cases, the temperature distribution is determined using only the latter approach. Numerical results are presented to illustrate the effects of internal losses, heat conduction and convection coefficients, and boundary conditions on the temperature distribution.
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http://dx.doi.org/10.1121/1.3478777 | DOI Listing |
Nanotechnology
January 2025
Electronic Sci.&Eng., Xi'an Jiaotong University, 28 Xianning West Road,Beilin District, Xi 'an, Shaanxi Province, China, Xi'an, 710049, CHINA.
The accurate estimation of the temperature distribution of the GaN based power devices and optimization of the device structure is of great significance to possibly solve the self-heating problem, which hinders the further enhancement of the device performances. We present here the operando temperature measurement with high spatial resolution using Raman spectroscopy of AlGaN/GaN high electron mobility transistors (HEMTs) with different device structures and explore the optimization of the device thermal design accordingly. The lateral and depth temperature distributions of the single-finger HEMT were characterized.
View Article and Find Full Text PDFVisible-light integrated photonics serve applications inaccessible to conventional (C- and O-band) silicon photonics, including trapped-ion and neutral atom quantum experiments, biophotonics, and displays. Despite demonstrations of increasingly advanced functionalities and levels of integration, the development of low-power, monolithically integrated, visible-light switches and phase shifters remains an outstanding challenge. Here, we demonstrate an integrated photonic, electrostatic MEMS-actuated Mach-Zehnder interferometer optical switch for the visible spectrum.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Science Institute and Faculty of Physical Sciences, University of Iceland, Reykjavík, Iceland.
Understanding the ultrafast vibrational relaxation following photoexcitation of molecules in a condensed phase is essential to predict the outcome and improve the efficiency of photoinduced molecular processes. Here, the vibrational decoherence and energy relaxation of a binuclear complex, [Pt2(P2O5H2)4]4- (PtPOP), upon electronic excitation in liquid water and acetonitrile are investigated through direct adiabatic dynamics simulations. A quantum mechanics/molecular mechanics (QM/MM) scheme is used where the excited state of the complex is modeled with orbital-optimized density functional calculations while solvent molecules are described using potential energy functions.
View Article and Find Full Text PDFISA Trans
January 2025
Department of Applied Mathematics, Bharathiar University, Coimbatore 641046, India; Department of Mathematics, Sungkyunkwan University, Suwon 440746, Republic of Korea. Electronic address:
This work describes the dissipative constraint-based load frequency control problem for multi-area power system under load disturbances. Particularly, a new model incorporating time-varying delays and cyber-attacks are widespread in communication networks, significantly impacting control and stability. Consequently, the state-space equations of the addressed model are formulated and analyzed under the impact of false data injection attacks, and time-varying delays.
View Article and Find Full Text PDFPacing Clin Electrophysiol
January 2025
Aurora Cardiovascular and Thoracic Services, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin, USA.
Background: Concurrent Micra leadless pacemaker (Medtronic, Minneapolis, Minnesota) implantation and atrioventricular node (AVN) ablation has been shown to be feasible and safe in patients with symptomatic, drug-refractory atrial fibrillation (AF). However, major complications within the 30 days after concurrent Micra implantation and AVN ablation have been reported. We evaluated the efficacy and safety of the concurrent procedure at our institution.
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