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- 摘要
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- 实验方案
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI, USA (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Reliability of Short-Term Heart Rate Variability Indexes Assessed through Photoplethysmography
摘要： The gold standard method to monitor heart rate variability (HRV) comprises measuring the time series of interbeat interval durations from electrocardiographic (ECG) recordings. However, due to the widespread use, simplicity and usability of photoplethysmographic (PPG) techniques, monitoring pulse rate variability (PRV) from pulse wave recordings has become a viable alternative to standard HRV analysis. The present study investigates the accuracy of PRV, measured as a surrogate of HRV, for the quantification of descriptive indexes computed in the time domain (mean, variance), frequency domain (low-to-high frequency power ratio LF/HF, HF band central frequency) and information domain (entropy, conditional entropy). We analyze short time series (300 intervals) of HRV measured from the ECG and of PRV acquired from Finometer device in 76 subjects monitored in the resting supine position (SU) and in the upright position during head-up tilt (HUT). Time, frequency and information domain indexes are computed for each HRV and PRV series and, for each index, the comparison between the two approaches is performed through statistical comparison of the distributions across subjects, robust linear regression, and Bland-Altman plots. Results of the comparison indicate an overall good agreement between PRV-based and HRV-based indexes, with an accuracy that is slightly lower during HUT than during SU, and for the band-power ratio and conditional entropy. These results suggest the feasibility of PRV-based assessment of HRV descriptive indexes, and suggest to further investigate the agreement in conditions of physiological stress.
关键词： information domain,photoplethysmography,time domain,pulse rate variability,frequency domain,heart rate variability
更新于2025-09-10 09:29:36
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Time-Division Parallel FDTD Algorithm
摘要： We propose a novel and efficient algorithm to parallelize the finite-difference time-domain method, where the observation period is divided into an arbitrary number of subsections, whose computation is distributed to corresponding computer nodes. The proposed algorithm roughly reduces the computational time to an n-th fraction of the conventional algorithm, where n is the number of nodes for parallel computing, thus verifying its efficiency improvement.
关键词： finite-difference complex-frequency-domain method,fast inverse Laplace transform,finite-difference time-domain method,time-division parallel algorithm
更新于2025-09-10 09:29:36
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[IEEE 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Cartagena des Indias, Colombia (2018.9.10-2018.9.14)] 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Equivalence Principle Algorithm for Potential Integral Equations
摘要： We present a new frequency-domain implementation of the equivalence principle algorithm (EPA) using the recently developed potential integral equations (PIEs) as inner formulations. The set of equivalent sources is updated by including all components of electric and magnetic fields, as well as potentials required for PIEs. The developed implementation is stable when applied to challenging problems involving extremely dense discretizations with respect to wavelength, while it is efficient at the same time thanks to the improved iterative solutions using EPA. The accuracy of the implementation is shown for the first time on canonical problems.
关键词： equivalence principle algorithm,dense discretizations,frequency-domain,potential integral equations,canonical problems
更新于2025-09-10 09:29:36
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[IEEE 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - Athens, Greece (2018.7.4-2018.7.6)] 2018 41st International Conference on Telecommunications and Signal Processing (TSP) - A Novel Discrete Wavelet Transform based Coherent Optical OFDM System
摘要： In optical communication, which is an important part of the Radio over Fiber (RoF) systems, coherent optical OFDM (CO-OFDM) systems allow the use of amplitude and phase belong to the light at the same time for data transmission. However, the data transmission speed and distance of the CO-OFDM system are limited by optical channel impairment effects. One of the major disadvantages of CO-OFDM systems is its sensitivity to fiber nonlinearity effects. For this reason, in order to be used the new signal processing techniques efficiently in the receiver, the optical channel information must be estimated and the received signal must be equalized. In this work, different equalizer constructions are investigated and a frequency domain channel equalizer used in the novel DWT-based CO-OFDM system has been proposed. With the simulation studies made, the equalizers were compared and the results were given with different changes. From the obtained simulation results, it is seen that the proposed method provides about 5.5 OSNR gain for 1E-4 BER value.
关键词： fiber nonlinearity impairment,discrete wavelet transform,Radio over Fiber,CO-OFDM systems,frequency domain equalizer
更新于2025-09-10 09:29:36
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Magnetic Optical FBG Sensors Using Optical Frequency-Domain Reflectometry
摘要： The optical frequency-domain reflectometry (OFDR) sensing system and signal processing method, which is based on the short-time Fourier transform, enable us to interrogate reflected wavelengths of fiber Bragg gratings (FBGs) and their relative position along the optical fiber with high spatial resolution. An FBG is an optical fiber with an appropriately inscribed periodic refractive index modulation. When a broadband optical signal is launched into the FBG, narrow wavelength bandwidth is reflected. Due to an attached transducer, such as Terfenol-D, the reflected wavelength changes with the applied magnetic field. The proposed magnetic FBG sensor consists of a small rod of magnetostrictive alloy TbDyFe, also known as Terfenol-D, which has large magnetostriction. The FBG is attached to the Terfenol-D rod with UV glue. Consequently, the external magnetic field is applied to the sensor and as a result, the Terfenol-D rod length increases. The reflected wavelength shift is observed and measured by the OFDR sensing system. Therefore, we determine the external magnetic field along the optical fiber from the reflected Bragg wavelength shift. The measurement results show that the proposed magnetic field sensors based on Terfenol-D using OFDR can be successfully used for measurement of the external magnetic field along an optical fiber.
关键词： Terfenol-D,optical frequency-domain reflectometry (OFDR),magnetic field sensor,Fiber Bragg gratings (FBGs)
更新于2025-09-09 09:28:46
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Background-free fluorescence decay time sensing and imaging of pH with highly photostable diazaoxotriangulenium dyes
摘要： Novel fluorescent diazaoxatriangulenium (DAOTA) pH indicators for lifetime-based self-referenced pH sensing are reported. The DAOTA dyes were decorated with phenolic receptor groups inducing fluorescence quenching via photoinduced electron transfer mechanism. Electron-withdrawing chlorine substituents ensure response in the most relevant pH range (apparent pK’a values ~5 and 7.5 for the p,p-dichlorophenol- and the p-chlorophenol-substituted dyes, respectively). The dyes feature long fluorescence lifetime (17-20 ns), high quantum yield (~60%) and high photostability. Planar optodes are prepared upon immobilization of the dyes into polyurethane hydrogel D4. Apart from the response in the fluorescence intensity, the optodes show pH-dependent lifetime behaviour which makes them suitable for studying 2D pH distribution with help of fluorescence lifetime imaging technique. The lifetime response is particularly pronounced for the sensors with high dye concentration (0.5-1% wt. in respect to the polymer) and is attributed to efficient homo-FRET mechanism.
关键词： pH sensor,photoinduced electron transfer,Decay time,triangulenium,Frequency Domain FLIM,FRET
更新于2025-09-09 09:28:46
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[IEEE 2018 Days on Diffraction (DD) - St.Petersburg, Russia (2018.6.4-2018.6.8)] 2018 Days on Diffraction (DD) - Semi-analytical hybrid approach for modelling wave motion excited by a piezoelectric transducer in periodic layered composite with a crack
摘要： The paper presents a semi-analytical hybrid approach for modelling the interaction of a piezoelectric transducer and with a periodic elastic structure with a crack. It combines advantages of the frequency domain spectral element method using Gauss–Legendre–Lobatto polynomials and the boundary integral approach. The unknown crack-opening-displacement and the traction vector in the contact area are determined via Galerkin method.
关键词： semi-analytical hybrid approach,frequency domain spectral element method,Galerkin method,periodic elastic structure,boundary integral approach,piezoelectric transducer,crack
更新于2025-09-09 09:28:46
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A NOVEL POLARIZATION INDEPENDENT CHIPLESS RFID TAG USING MULTIPLE RESONATORS
摘要： A novel polarization independent RFID tag employing multiple resonators is proposed. The prototype of the tag is fabricated on a low-cost substrate of dielectric constant 4.4 and loss tangent 0.02. Designing a reader for chipless RFID is a hard task since both the polarization and operating frequency agility have to be implemented. The new tag design proposed in this paper is polarization independent, making the design of the reader easier. A prototype of a 3 bit data encoded tag is demonstrated using single structure which can be extended to any order by cascading. This new design is experimentally validated in the frequency domain using monostatic measurement with magnitude response to decode the information.
关键词： polarization independent,multiple resonators,low-cost substrate,chipless RFID tag,frequency domain
更新于2025-09-09 09:28:46
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Josephson Effects in Frequency-Domain Multiplexed TES Microcalorimeters and Bolometers
摘要： Frequency-division multiplexing is the baseline read-out system for large arrays of superconducting transition-edge sensors (TES’s) under development for the X-ray and infrared instruments like X-IFU (Athena) and SAFARI, respectively. In this multiplexing scheme, the sensors are ac-biased at different frequencies from 1 to 5 MHz and operate as amplitude modulators. Weak superconductivity is responsible for the complex TES resistive transition, experimentally explored in great detail so far, both with dc- and ac-biased read-out schemes. In this paper, we will review the current status of our understanding of the physics of the TES’s and their interaction with the ac bias circuit. In particular, we will compare the behaviour of the TES nonlinear impedance, across the superconducting transition, for several detector families, namely: high-normal-resistance TiAu TES bolometers, low-normal-resistance MoAu TES microcalorimeters and high-normal-resistance TiAu TES microcalorimeters.
关键词： Frequency-domain multiplexing,Josephson effect,Transition-edge sensors
更新于2025-09-09 09:28:46
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A research on fiber-optic vibration pattern recognition based on time-frequency characteristics
摘要： To detect and recognize any type of events over the perimeter security system, this article proposes a fiber-optic vibration pattern recognition method based on the combination of time-domain features and time-frequency domain features. The performance parameters (event recognition, event location, and event classification) are very important and describe the validity of this article. The pattern recognition method is precisely based on the empirical mode decomposition of time-frequency entropy and center-of-gravity frequency. It implements the function of identifying and classifying the event (intrusions or non-intrusion) over the perimeter to secure. To achieve this method, the first-level prejudgment is performed according to the time-domain features of the vibration signal, and the second-level prediction is carried out through time-frequency analysis. The time-frequency distribution of the signal is obtained by empirical mode decomposition and Hilbert transform and then the time-frequency entropy and center-of-gravity frequency are used to form the time-frequency domain features, that is, combined with the time-domain features to form feature vectors. Multiple types of probabilistic neural networks are identified to determine whether there are intrusions and the intrusion types. The experimental results demonstrate that the proposed method is effective and reliable in identifying and classifying the type of event.
关键词： time-frequency domain features,time-frequency analysis,empirical mode decomposition,time-frequency entropy,Event recognition,pattern recognition,center-of-gravity frequency,time-domain features
更新于2025-09-04 15:30:14