This paper presents a control technique for reducing the reflection of acoustic signals for the plane array of multilayer acoustic absorbers underwater. In order to achieve this, a plane array of multilayer acoustic absorbers is proposed to attenuate low-frequency noise, with each unit consisting of a piezoelectric transducer, two layers of polyvinylidene fluorides and three layers of the acoustic window. Time-delay separation is used to find the incident and reflected acoustic signals to achieve reflected sound reduction. Experimental comparison of the attenuation rate of the reflected acoustic signal when performing passive and active controls is considered to verify the effectiveness of the time-delay separation technique applied plane array absorbers. Experiments on the plane array of smart skin absorbers confirmed that the reduction of reflected acoustic signals makes it suitable for a wide range of underwater applications.
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http://dx.doi.org/10.3390/s21248432 | DOI Listing |
Eur Arch Otorhinolaryngol
January 2025
Vrije Universiteit Brussel, Brussels Health Centre, Brussels, Belgium.
Purpose: Cochlear implants (CI) are the most successful bioprosthesis in medicine probably due to the tonotopic anatomy of the auditory pathway and of course the brain plasticity. Correct placement of the CI arrays, respecting the inner ear anatomy are therefore important. The ideal trajectory to insert a cochlear implant array is defined by an entrance through the round window membrane and continues as long as possible parallel to the basal turn of the cochlea.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Dalian University of Technology State Key Laboratory of High-Performance Precision Manufacturing, Key Laboratory for Micro/Nano Technology and System of Liaoning Province, School of Mechanical Engineering, Dalian 116024, China.
Inspired by ancient trilobites, novel curved microlens arrays (CMLAs) were designed. Direct, fast, and low-cost CMLAs with two focal planes were fabricated using ultraprecision machining technology and hot embossing technology. We designed four pairs of artificial compound eyes (ACEs) composed of large and small lenses with four different curvatures to achieve focusing and imaging on two focal planes.
View Article and Find Full Text PDFNano Lett
January 2025
State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yu Tian Road, Shanghai 200083, China.
Enhancing photoluminescence (PL) efficiency in colloidal quantum dots is pivotal for next-generation near-infrared photodetectors, imaging systems, and photonic devices. Conventional methods, especially metal-based plasmonic structures, suffer from large optical losses, which limits their practical use. Here, we introduce a quasi-bound state in the continuum (quasi-BIC) metasurface on a silicon-on-insulator platform, tailored to provide high-quality factor resonances with minimized losses.
View Article and Find Full Text PDFSci Rep
January 2025
Faculty of Electric and Computer, Malek Ashtar University of Technology, Tehran, Iran.
In this paper, a multilayer monopulse antenna at Ku-Band with high efficiency, high power handling capability, high gain, 45° linear polarization and low sidelobe is presented. A new slot antenna is proposed as a radiating element based on a cavity-backed slot-coupled patch antenna. Using an enclosed cavity structure reduces coupling between antenna elements, thus increasing the antenna efficiency.
View Article and Find Full Text PDFSensors (Basel)
January 2025
Department of Electrical and Electronics Engineering, Faculty of Engineering, Karadeniz Technical University, Trabzon 61080, Türkiye.
Electric heaters are widely used owing to their portability, fast heating, single-focus heating, and energy efficiency advantages. Manufacturers provide customers with information on the power consumption and energy efficiency classes of heaters but do not provide any information on heating patterns. Knowing the heating pattern enables users to select the correct heater, which has a significant effect on comfort, health, energy efficiency, industrial process performance, plant growth, and climate change.
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