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From Fog Chamber to Aircraft Window: Pixel-Registered Imaging and Synthetic Fine-Tuning Enable Cross-Domain Defogging
Authors:
Alexander Ingold,
Sabina D. Menon,
Manya Yellepeddy,
Alec Ikei,
John D. Hodges,
Jordan Baker,
Syed N. Qadri,
Rajesh Menon
Abstract:
A deep defogging pipeline pretrained on controlled laboratory fog and fine-tuned with domain-randomized synthetic fog applied to clear outdoor scenes generalizes across a graded sequence of out-of-distribution settings with no target-domain training, from chamber-free free-flowing fog to iPhone video recorded through an aircraft cabin window in flight, an entirely unseen sensor, scene, and optical…
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A deep defogging pipeline pretrained on controlled laboratory fog and fine-tuned with domain-randomized synthetic fog applied to clear outdoor scenes generalizes across a graded sequence of out-of-distribution settings with no target-domain training, from chamber-free free-flowing fog to iPhone video recorded through an aircraft cabin window in flight, an entirely unseen sensor, scene, and optical path. This directly addresses an open transfer limitation reported for real-world binocular defogging. Two design choices support the transfer. First, a single-camera fog imager photographs a flat-panel display through an artificial-fog enclosure with a fixed 114~mm scattering path, producing 5{,}495 pixel-aligned foggy/clear pairs. Exact registration permits a paired Laplacian ratio that predicts per-image restoration quality far better than single-image proxies (Spearman $ρ= 0.632$ versus $0.399$) and supports pixel-exact $L_1$ reconstruction training that avoids adversarial hallucination. Second, the fog-chamber checkpoint is fine-tuned on Mapillary Vistas crops overlaid with on-the-fly randomized synthetic fog spanning a broad range of strengths, spatial variations, airlights, and noise conditions. On a 552-image held-out split, a uniform comparison of 30 restoration backbones places NAFNet at the top (24.33~dB~/~0.7912~SSIM), with a compact alternative within 1.29~dB at 3\% of the parameter count, and a ResNet-50 classifier confirms that the restoration preserves semantic content rather than only pixel-level structure. On unpaired aircraft-window video, NIQE decreases from a mean of 6.22 to 4.97 after fine-tuning, with temporally stable output across full-motion sequences. The same backbone, under paired supervision, also reaches 20.71~dB~/~0.683~SSIM on a non-overlapping O-HAZE/NH-HAZE split (a transferability check rather than a competitive ranking).
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Submitted 27 June, 2026;
originally announced June 2026.
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Flexural wave modulation and mitigation in airfoils using acoustic black holes
Authors:
Kaushik Sampath,
Caleb F Sieck,
Matthew D Guild,
Alec K Ikei,
Charles A Rohde
Abstract:
This study introduces a framework for the design and implementation of acoustic black holes (ABHs) in airfoils. A generalized multi-parameter damped-ABH generation function is mapped onto NACA series airfoils. Representative geometries and a uniformly distributed baseline, all with the same mass of structure and damping are fabricated using multi-material PolyJet 3D printing. Laser Doppler vibrome…
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This study introduces a framework for the design and implementation of acoustic black holes (ABHs) in airfoils. A generalized multi-parameter damped-ABH generation function is mapped onto NACA series airfoils. Representative geometries and a uniformly distributed baseline, all with the same mass of structure and damping are fabricated using multi-material PolyJet 3D printing. Laser Doppler vibrometer measurements along the airfoil chord in response to a broadband 0.1 - 12 kHz excitation show a decrease in trailing edge vibrations by as much as 10 dB, a broadband 5 dB reduction across the entire chord as well as substantial spatial and temporal modulation of flexural waves by ABH-embedded foils. Finite element analysis (FEA) models are developed and validated based on the measured data. Furthermore, a parametric FEA study is performed on a set of comparable designs to elucidate the scope of modulation achievable. These findings are applicable to trailing-edge noise reduction, flow control, structural enhancement and energy harvesting for airfoils.
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Submitted 15 April, 2021;
originally announced April 2021.
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3D Printed PVDF
Authors:
Alec Ikei,
James Wissman,
Gregory Yesner,
Charles Rohde
Abstract:
In this paper we report on the 3D printing and testing of the piezoelectric polymer polyvinylidene difluoride (PVDF). Samples of PVDF were fabricated using a fused deposition modeling (FDM) 3D printer and then activated using a corona poling process. The d33 piezoelectric coefficient, which is related to the overall piezoelectric performance, was experimentally measured using a d33 meter to be 6 p…
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In this paper we report on the 3D printing and testing of the piezoelectric polymer polyvinylidene difluoride (PVDF). Samples of PVDF were fabricated using a fused deposition modeling (FDM) 3D printer and then activated using a corona poling process. The d33 piezoelectric coefficient, which is related to the overall piezoelectric performance, was experimentally measured using a d33 meter to be 6 pC/N. While less than commercially available PVDF fabricated using traditional techniques (which can have a d33 between 10 and 40 pC/N), the value of 6 pC/N achieved in this work is several orders of magnitude larger than comparable previously published results for 3D printed PVDF, and as a result represents a significant step in the 3D printing of piezoelectric polymers.
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Submitted 25 February, 2021;
originally announced February 2021.
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Hydraulically Amplified Self-Healing ELectrostatic (HASEL) Inspired Actuators
Authors:
James P. Wissman,
Alec K. Ikei,
Kaushik Sampath,
Charles A. Rohde
Abstract:
This report presents research conducted on amplified self-healing electrostatic (HASEL) actuators. HASEL actuators are comprised of a dielectric fluid sealed between two inextensible layers with bonded, flexible electrodes on its outer surface. When charge is applied to the electrodes, Coulomb force compresses the fluid and causes the actuator to contract. In this work a faster, more customizable…
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This report presents research conducted on amplified self-healing electrostatic (HASEL) actuators. HASEL actuators are comprised of a dielectric fluid sealed between two inextensible layers with bonded, flexible electrodes on its outer surface. When charge is applied to the electrodes, Coulomb force compresses the fluid and causes the actuator to contract. In this work a faster, more customizable and convenient way of creating a HASEL actuator is presented, using a laser engraver to heat-seal and cut polypropylene sheets. Using this technique, a hydraulically actuated soft lens is fabricated and demonstrated.
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Submitted 25 February, 2021;
originally announced February 2021.
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Remote Operation of a Single-Point LDV System to Acquire 2D Measurements
Authors:
Alec K. Ikei,
Kaushik Sampath
Abstract:
Due to the unprecedented increase in telework requirements, the motivation to further automate and remotely control experiments has become apparent. This work documents the technical development of creating a two-dimensional (2D) Laser Doppler Vibrometry (LDV)measurement using a single-point LDV system through an automated and remotely controllable process. This report aims to assist in rapid deve…
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Due to the unprecedented increase in telework requirements, the motivation to further automate and remotely control experiments has become apparent. This work documents the technical development of creating a two-dimensional (2D) Laser Doppler Vibrometry (LDV)measurement using a single-point LDV system through an automated and remotely controllable process. This report aims to assist in rapid development of setups for similar use cases. The setup described is also modular, and has been used to analyze the modal response of samples actuated through air-based acoustic signals as well as those mechanically induced.
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Submitted 25 February, 2021;
originally announced February 2021.