Article
Engineering, Biomedical
Robert S. Stormont, Gareth R. Davies, P. James Ross, David J. Lurie, Lionel M. Broche
Summary: In this study, methods to evaluate and preserve the signal-to-noise ratio (SNR) of a low frequency coil array were investigated. It was found that ultra fine strand litz wire with a diameter of 16.2 cm exhibited lower losses and provided the mechanical flexibility needed for a conforming array. Additionally, the low noise interfacing electronics were optimized and tested to minimize SNR penalties and allow for rapid setup.
PHYSICS IN MEDICINE AND BIOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Qi Dong, Junjie Zhao, Yong Zhou, Xiaoli Fu
Summary: This study investigates the temperature characteristics of water inner-cooled stator coil using Litz wire for HTS motor. The study accumulates rich experience in transposed Litz bundle windings and verifies the rationality of the numerical temperature field calculation method. It also explores the effects of pipe blockage and epoxy thermal conductivity changes on the coil temperature, forming a relatively complete method for evaluating the temperature characteristics of water inner-cooled windings.
JOURNAL OF ELECTRICAL ENGINEERING & TECHNOLOGY
(2023)
Article
Engineering, Mechanical
Yushin Hara, Keisuke Otsuka, Kanjuro Makihara
Summary: In this study, a structural system identification method using semi-active inputs generated from piezoelectric transducers is proposed. By developing a suitable semi-active input generation strategy and a data calibration method, the method significantly reduces energy consumption while achieving accurate structure identification, making it suitable for onsite structural health monitoring.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Chemistry, Multidisciplinary
Marios Giouvanakis, Christos Sevastiadis, George Papanikolaou
Summary: A system for low-frequency noise control in small, enclosed sound fields is proposed, using compound sound sources optimized by a genetic algorithm (GA). It aims to control the modal field by integrating low-Bl driver compound sources with a GA computer program in Python. The system is designed to adapt to any available position due to the lack of appropriate free space in small rooms. Two quadrupole topologies of the secondary compound source are applied and examined in a room, achieving convergence to optimal solutions through parametric configuration. The experimental results demonstrate successful control of resonances of different low frequencies and significant tonal noise attenuation, confirming the practicality and effectiveness of the system as an alternative to typical abatement techniques in limited spaces.
APPLIED SCIENCES-BASEL
(2023)
Article
Mathematics, Applied
C. S. Barquist, W. G. Jiang, K. Gunther, Y. Lee
Summary: In this study, analytical calculations were performed on the response of a driven Duffing oscillator to low-frequency fluctuations in resonance frequency and damping, revealing distinctive features that allow for their differentiation. The results indicate strong attenuation of amplitude and phase noise due to resonance frequency fluctuations and amplitude noise due to damping fluctuations in the strongly nonlinear regime, while the transduction of damping fluctuations into phase noise remains significant. This suggests a method for determining the source of low-frequency noise in a driven Duffing oscillator.
PHYSICA D-NONLINEAR PHENOMENA
(2021)
Article
Multidisciplinary Sciences
Jingkun Guo, Jin Chang, Xiong Yao, Simon Groblacher
Summary: In this study, the researchers demonstrate ground-state cooling of a nanostring mechanical resonator using measurement-based feedback. They achieve an average phonon occupation of 0.76 when starting from liquid helium temperature, and 3.5 when starting from liquid nitrogen. This provides a promising platform for studying fundamental physics and enables various applications, including precise sensing.
NATURE COMMUNICATIONS
(2023)
Article
Engineering, Mechanical
Jincan Liu, Zhengchao Xie, Jinwu Gao, Yunfeng Hu, Jing Zhao
Summary: This study provides a unified modeling method to describe the failure characteristics of active-passive damping in functionally graded piezoelectric layers-magnetorheological elastomer sandwich structures, investigates the failure mechanism and the impact of the improved control method for active-passive damping.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Engineering, Ocean
Giulio Dubbioso, Roberto Muscari, Fabrizio Ortolani, Andrea Di Mascio
Summary: Maneuvering motion has a significant impact on the acoustic signature of marine propellers. In this study, a comprehensive tool for design and mission planning is developed based on previous analysis. Passive and active noise control strategies are considered, and the noise sources are calculated using a non-interacting RANS-BEMT procedure and analyzed with an acoustic analogy. The test case involves a modern twin screw ship undergoing rectilinear advance and turning maneuvers.
APPLIED OCEAN RESEARCH
(2022)
Article
Engineering, Electrical & Electronic
Delu Li, Xiao Zhang, Xianming Deng, Changyi Li
Summary: The paper proposes a hybrid inductive and active filter (HIAF) system with a Ddy converter transformer to suppress harmonics in low-voltage distribution networks. The system utilizes detection points on the grid-side winding and compensation points on the filtering winding to achieve harmonic suppression under both balanced and unbalanced loads. Simulation results demonstrate the effectiveness of the HIAF system in various load conditions.
Article
Engineering, Electrical & Electronic
Paulo A. C. Lopes, Jose Antonio Beltran Gerald
Summary: This study proposes a new approach by removing the AA and RC filters of sigma-delta converters and using oversampled signals directly in an ANC system, allowing for a large sample frequency with significantly reduced computational complexity. The research presents the first short-word length implementation of the LMS algorithm, achieving up to 6 times gains in computational complexity compared to long-word length implementations. Theoretical and simulation results support the effectiveness of the proposed solution.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2021)
Article
Engineering, Electrical & Electronic
Shin Hyung Kim, Jung Keun Ahn
Summary: A compact superconducting magnet was constructed for low-energy nuclear physics experiments at the RAON heavyion accelerator facility. The magnet generates a uniform magnetic field and allows the beam to pass in two different modes. The magnet's design and performance were successfully tested and reported in this study.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2021)
Article
Acoustics
Paul E. Slaboch, Sophie Kaye, Ethan Casavant
Summary: The study found that adjusting the outer diameter and spacing of hollow cylindrical arrays can effectively increase the absorption of low-frequency sound, reducing disturbance to listeners.
JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME
(2021)
Article
Quantum Science & Technology
Songya Ma, Niannian Wang
Summary: The study investigates hierarchical remote preparation of an arbitrary two-qubit state for the first time, proposing two deterministic schemes extended to multiparty scenarios. There is a hierarchy among agents based on their ability to reconstruct the target state. The impact of two important decoherence noises, amplitude-damping and phase-damping noise, is also considered.
QUANTUM INFORMATION PROCESSING
(2021)
Article
Acoustics
Pierangelo Libianchi, Jonas Brunskog, Finn Agerkvist, Elena Shabalina
Summary: Sound field control can be used to reduce noise emissions from outdoor live music events, and pressure matching is one method employed. The proposed method utilizes the conjugate gradient least square to compute a solution, which provides an easier way to find suitable regularization and control the radiation pattern to reduce side lobes. Through simulations and outdoor measurements, it is demonstrated that the method achieves 10 dB insertion loss over a broad frequency range.
Article
Engineering, Electrical & Electronic
Chenyi Peng, Guodong Chen, Borong Wang, Jinfeng Song
Summary: The importance of high-frequency transformers in power electronics devices cannot be underestimated. Traditional prediction models for winding losses in litz wire often overlook the impact of operating conditions and geometrical parameters. This article introduces a simple semi-analytical model that takes these factors into account, resulting in improved accuracy in predicting winding losses.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)