804 research outputs found
Robustness analysis and experimental validation of a deep neural network for acoustic source imaging
Full text linkDeep Neural Network (DNN) models offer an attractive alternative to existing acoustic source imaging techniques, such as acoustic beamforming, due to their ever-growing potential with increasing computational power. Source resolution of acoustic beamforming methods is limited at lower frequencies and their source maps may possess sidelobes at higher frequencies. However, acoustic beamforming methods are typically robust over a wide range of simulation and experimental conditions, such as (i) the number of sources present, (ii) source frequency and (ii) extraneous noise sources. The performance of DNN models, when these conditions are varied from their specific design criteria, is yet to be investigated and much work is needed in this area before DNN models can be utilized in experiments, such as wind tunnel tests. Furthermore, few studies have been conducted on experimental validation of DNN models, predominately due to the difficulty of large sets of experimentally obtained data needed for DNN model training and the sensitivity of DNN model performance when any of the aforementioned experimental conditions are varied. In this paper, a series of studies on the robustness of DNN models based on numerical data and experimental data are presented. Numerical DNN (NDNN) models are trained using in-phase and random-phase pressure data generated from six sources over design frequencies from 500 Hz to 20,000 Hz. The robustness of the NDNN models is tested via (1) inclusion of extraneous Gaussian white noise, (2) inclusion of extraneous tonal noise near the design frequency, (3) using source frequencies that slightly differ from the design frequencies and (4) using a number of sources that differs from the design source number. DNN model performance metrics are introduced that present a promising framework for future DNN model studies and bridging the gap between NDNN and experimentally trained DNN models. A preliminary experimental validation was conducted using a single speaker that was systematically placed over a speaker grid to generate training data via acoustic superposition, from which an experimentally trained DNN (EDNN) model was produced. The EDNN model yields exceptional noise source localization capability of the DNN model, revealing a promising start for a more sophisticated EDNN model
Decelerating Airy pulse propagation in highly non-instantaneous cubic media
Full text linkThe propagation of decelerating Airy pulses in non-instantaneous cubic medium is investigated both theoretically and numerically. In a Debye model, at variance with the case of accelerating Airy and Gaussian pulses, a decelerating Airy pulse evolves into a single soliton for weak and general non- instantaneous response. Airy pulses can hence be used to control soliton generation by temporal shaping. The effect is critically dependent on the response time, and could be used as a way to measure the Debye type response function. For highly non- instantaneous response, we theoretically find a decelerating Airy pulse is still transformed into Airy wave packet with deceleration. The theoretical predictions are confirmed by numerical simulations
THE APPLICATION OF RAPID THERMAL ANNEALING TO REDUCE LEAKAGE CURRENT OF TA2O5
No full textMaster'sMASTER OF ENGINEERIN
MOF-derived CoP nanoparticles anchored on P, N co-doped carbon nanoframework as robust electrocatalyst for rechargeable Li-O2 batteries
No full textCurrently, transition-metal phosphides (TMPs) coupled with heteroatom-doped carbon materials have attracted promising prospects in lithium‑oxygen (Li-O2) batteries. The CoP electrocatalysts have been extensively studied as popular electrode materials because of their efficient catalytic activity. However, numerous obstacles remain in optimizing synthetic techniques and exploring electrocatalytic mechanisms for CoP-based electrocatalysts. Herein, metal-organic frameworks (MOFs)-derived CoP nanoparticles anchored on P, N co-doped carbon nanoframeworks (CoP@PNCFs) are successfully designed at different phosphorization temperatures. The effects of the concentration of CoP active species, and the amount of P and N doping on the electrochemical performances are comparatively investigated and compared for different catalysts. The optimal catalyst, CoP@PNCF-700, displays high CoP active component, pyridinic-N and graphitic-N content, and abundant defect structures to enhance the electrochemical activity. More importantly, the CoP@PNCF-700 catalytic Li-O2 batteries deliver a high discharge specific capacity of 9630.5 mAh g−1 at 100 mA g−1 and a prominent long cycling stability of 187 cycles with a fixed capacity of 500 mAh g−1 at 200 mA g−1. This effort provides a facile strategy for designing cost-effective electrocatalysts for other energy-storage systems.<br/
Degradation and Failure Mechanisms of Lithium/LiNixCoyMn1-x-yO2 Batteries
Full text linkPublisher Copyright: © 2025 The Authors. Published by American Chemical Society.Lithium (Li)/LiNixCoyMn1-x-yO2 (NCM) batteries are considered one of the most promising battery technologies for next-generation energy storage, but their commercial viability is still hampered by rapid capacity decay and safety concerns. Recently, the mechanistic understanding of Li/NCM battery degradation and failure processes has made significant progress thanks to advances in battery diagnostics and analysis. Herein we comprehensively review the current understanding of Li/NCM battery degradation as a function of the type of electrode materials, electrolytes, packaging formats, and cycling conditions, and discuss the degradation mechanisms related to the interplay between the Li metal anode and the NCM cathode. We also review the safety threats and eventual failure of Li/NCM batteries and their root causes. Moreover, we provide our perspectives on the future research necessary to gain a more complete understanding of the degradation and failure of Li/NCM batteries.Peer reviewe
Redox-Driven Lithium Perfusion to Fabricate Li@Ni–Foam Composites for High Lithium-Loading 3D Anodes
No full textAs
the hostless nature of the conventional Li anodes with planar surfaces
inevitably causes volume expansion and parasitic dendrite growth,
it is essential to develop a composite electrode structure with improved
Li plating/stripping behaviors to mitigate such issues. Herein, a
composite Li@NF anode was successfully fabricated through lithium
perfusion into the commercial nickel foam (NF) decorated with lithiophilic
NiO nanosheets, demonstrating an exceptionally high areal Li loading
of 53.2 mg cm–2 with suppressed Li dendrite formation
and volume expansion, improved Coulombic efficiency, as well as extended
cycling stability in all half, symmetric, and full cell tests. More
importantly, density functional theory calculations and control studies
with Fe2O3@NF, pristine NF, and Cu2O@CF reveal a linear correlation between the thermodynamics of the
surface reactions and the lithiophilicity of the reaction products,
attesting to a redox-driven Li perfusion process. Further, through
ex situ scanning electron and in situ optical microscopy, the enhanced
performance of Li@NF is mainly attributed to the mediation of Li plating/stripping
through homogenizing the Li+ flux, decentralizing local
charge density, and accommodating multidirectional Li deposition by
the conductive 3D scaffolds. Consequently, this study offers important
insights into the driving of thermal Li perfusion through appropriate
material and surface design for achieving safe and stable lithium
metal anodes
Redox-Driven Lithium Perfusion to Fabricate Li@Ni–Foam Composites for High Lithium-Loading 3D Anodes
No full textAs
the hostless nature of the conventional Li anodes with planar surfaces
inevitably causes volume expansion and parasitic dendrite growth,
it is essential to develop a composite electrode structure with improved
Li plating/stripping behaviors to mitigate such issues. Herein, a
composite Li@NF anode was successfully fabricated through lithium
perfusion into the commercial nickel foam (NF) decorated with lithiophilic
NiO nanosheets, demonstrating an exceptionally high areal Li loading
of 53.2 mg cm–2 with suppressed Li dendrite formation
and volume expansion, improved Coulombic efficiency, as well as extended
cycling stability in all half, symmetric, and full cell tests. More
importantly, density functional theory calculations and control studies
with Fe2O3@NF, pristine NF, and Cu2O@CF reveal a linear correlation between the thermodynamics of the
surface reactions and the lithiophilicity of the reaction products,
attesting to a redox-driven Li perfusion process. Further, through
ex situ scanning electron and in situ optical microscopy, the enhanced
performance of Li@NF is mainly attributed to the mediation of Li plating/stripping
through homogenizing the Li+ flux, decentralizing local
charge density, and accommodating multidirectional Li deposition by
the conductive 3D scaffolds. Consequently, this study offers important
insights into the driving of thermal Li perfusion through appropriate
material and surface design for achieving safe and stable lithium
metal anodes
Redox-Driven Lithium Perfusion to Fabricate Li@Ni–Foam Composites for High Lithium-Loading 3D Anodes
No full textAs
the hostless nature of the conventional Li anodes with planar surfaces
inevitably causes volume expansion and parasitic dendrite growth,
it is essential to develop a composite electrode structure with improved
Li plating/stripping behaviors to mitigate such issues. Herein, a
composite Li@NF anode was successfully fabricated through lithium
perfusion into the commercial nickel foam (NF) decorated with lithiophilic
NiO nanosheets, demonstrating an exceptionally high areal Li loading
of 53.2 mg cm–2 with suppressed Li dendrite formation
and volume expansion, improved Coulombic efficiency, as well as extended
cycling stability in all half, symmetric, and full cell tests. More
importantly, density functional theory calculations and control studies
with Fe2O3@NF, pristine NF, and Cu2O@CF reveal a linear correlation between the thermodynamics of the
surface reactions and the lithiophilicity of the reaction products,
attesting to a redox-driven Li perfusion process. Further, through
ex situ scanning electron and in situ optical microscopy, the enhanced
performance of Li@NF is mainly attributed to the mediation of Li plating/stripping
through homogenizing the Li+ flux, decentralizing local
charge density, and accommodating multidirectional Li deposition by
the conductive 3D scaffolds. Consequently, this study offers important
insights into the driving of thermal Li perfusion through appropriate
material and surface design for achieving safe and stable lithium
metal anodes
Redox-Driven Lithium Perfusion to Fabricate Li@Ni–Foam Composites for High Lithium-Loading 3D Anodes
No full textAs
the hostless nature of the conventional Li anodes with planar surfaces
inevitably causes volume expansion and parasitic dendrite growth,
it is essential to develop a composite electrode structure with improved
Li plating/stripping behaviors to mitigate such issues. Herein, a
composite Li@NF anode was successfully fabricated through lithium
perfusion into the commercial nickel foam (NF) decorated with lithiophilic
NiO nanosheets, demonstrating an exceptionally high areal Li loading
of 53.2 mg cm–2 with suppressed Li dendrite formation
and volume expansion, improved Coulombic efficiency, as well as extended
cycling stability in all half, symmetric, and full cell tests. More
importantly, density functional theory calculations and control studies
with Fe2O3@NF, pristine NF, and Cu2O@CF reveal a linear correlation between the thermodynamics of the
surface reactions and the lithiophilicity of the reaction products,
attesting to a redox-driven Li perfusion process. Further, through
ex situ scanning electron and in situ optical microscopy, the enhanced
performance of Li@NF is mainly attributed to the mediation of Li plating/stripping
through homogenizing the Li+ flux, decentralizing local
charge density, and accommodating multidirectional Li deposition by
the conductive 3D scaffolds. Consequently, this study offers important
insights into the driving of thermal Li perfusion through appropriate
material and surface design for achieving safe and stable lithium
metal anodes
- …
