- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2019
- time delay
- fiber Bragg grating
- microwave photonics
- finite impulse response
- Fourier transform
- optical sensors
- Optoelectronic Information Science and Engineering
- Southern University of Science and Technology
- University of Kent
- University of Kent, Tianjin Normal University
-
[IEEE 2019 26th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD) - Kyoto, Japan (2019.7.2-2019.7.5)] 2019 26th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD) - Identification of Edge Recombination from CIGS Solar Cells
摘要： We study the detection and estimation of the parameters related to the deterministic model of the re?ections of room impulse responses measured with a spherical microphone array. More speci?cally, we investigate the problem of detecting and estimating several re?ections of a single snapshot of data in the spherical harmonic (SH) domain with four detection and four estimation methods, presented previously in the array processing research. Three of the estimation methods are based on Bayesian Maximum a Posteriori (MAP) estimation, and they employ a prior normal distribution on the signals. The estimation methods are compared with the deterministic maximum likelihood (DML) method [Tervo & Politis 2015]. In the detection task, two information criteria-based methods, minimum description length (MDL) and Akaike information criteria (AIC), a normalized likelihood (NL) based method, and a Bayesian detection scheme (BDS) are explored. The experiments study the performance of the methods with simulated and real data experiments. The simulation results show that the MAP estimation methods have a lower root mean squared error (RMSE) than DML in the re?ection signal amplitude estimation, but all three have similar performance in the direction of arrival (DOA) and noise variance estimation, although in general RMSE of DOA estimation of MAP methods is slightly lower that that of DML. In addition, in the detection task, the BDS and AIC are the most robust against additive noise, and NL and AIC have the best detection rate when more than two re?ections are simulated. The results of the real data experiments show that all the estimation methods have similar performance for DOA and noise variance estimation, while the Bayesian MAP methods have a clearly lower RMSE for re?ection signal amplitude estimation than DML. In total, NL has the highest detection rate in the real data experiments.
关键词： spatial room impulse response,direction of arrival,room acoustics,Detection of Re?ections,single snapshot,spherical microphone arrays
更新于2025-09-23 15:19:57
-
Non-destructive discrimination of avocado fruit ripeness using laser Doppler vibrometry
摘要： Consumers increasingly desire ready-to-eat avocado fruit, yet if supplies fall short of customer expectations, complaints follow, incurring considerable cost and waste. In the avocado sector, wastage due to destructive testing and inaccurate assessment of firmness is significant. The aim of this study was to evaluate whether non-destructive laser Doppler vibrometry (LDV) was capable of assessing avocado ripeness. Data were sourced from two trials using preclimacteric imported 'Hass' avocado fruit originating from Chile and Spain, ripened at 12 and 18 °C, respectively. Standard force-deformation measurements, and either single or simultaneous dual vibration time signals were recorded during shelf-life, and assessed against respiration and non-structural carbohydrate content. Resonant frequencies measured from fruit by means of LDV decreased two- to four-fold during ripening and this corresponded with a concomitant decrease in firmness (253 N e2 N). The capability of the LDV system to non-destructively discriminate between ripeness stages was demonstrated.
关键词： Quality control,Persea americana,Mannoheptulose,Impulse response,Firmness
更新于2025-09-23 15:19:57
-
Multispectral incoherent holography based on measurement of differential wavefront curvature
摘要： We propose a technique of multispectral incoherent holography. The differential wavefront curvature is measured, and the principle of Fourier transform spectrometry is applied to provide a set of spectral components of three-dimensional images and continuous spectra for spatially incoherent, polychromatic objects. This paper presents the mathematical formulation of the principle and the experimental results. Three-dimensional imaging properties are investigated based on an analytical impulse response function. The experimental and theoretical results agree well.
关键词： Impulse response function,Multispectral imaging,Depth resolution,3D imaging property,Spectroscopy,Incoherent holography
更新于2025-09-19 17:13:59
-
[IEEE 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA) - Brasov, Romania (2019.11.3-2019.11.6)] 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA) - Influence of an Impulse Current near a Photovoltaic Solar Module on Bypass Diode Characteristics
摘要： Recently, failures in photovoltaic systems (PVSs) caused by lightning damage have been increasing. When lightning strikes a PVS, the bypass diode (BPD), which is a protection element in the solar cell module (PV-MDL), breaks down and burns out, rendering the PVS inoperable. In this study, an impulse current test was conducted to clarify the lightning-induced BPD failure mechanism. The impulse current with a peak of 100 kA was employed to simulate a lightning strike traveling in the vicinity of a PV-MDL. The results indicated that a BPD fails because lightning (induced electromotive force) strikes in the bypass circuit of the PV-MDL as the impulse current passes in its vicinity. Furthermore, installing a metal frame in the PV-MDL was shown to reduce the negative impact of such lightning strikes.
关键词： impulse current test,bypass diode,lightning,photovoltaic module,induced lightning
更新于2025-09-19 17:13:59
-
Compressive Holography from Poisson Noise plagued Holograms using Expectation-Maximization
摘要： We present the concept of an acoustic rake receiver—a microphone beamformer that uses echoes to improve the noise and interference suppression. The rake idea is well-known in wireless communications; it involves constructively combining different multipath components that arrive at the receiver antennas. Unlike spread-spectrum signals used in wireless communications, speech signals are not orthogonal to their shifts. Therefore, we focus on the spatial structure, rather than the temporal. Instead of explicitly estimating the channel, we create correspondences between early echoes in time and image sources in space. These multiple sources of the desired and the interfering signal offer additional spatial diversity that we can exploit in the beamformer design. We present several “intuitive” and optimal formulations of acoustic rake receivers, and show theoretically and numerically that the rake formulation of the maximum signal-to-interference-and-noise ratio beamformer offers significant performance boosts in terms of noise and interference suppression. Beyond signal-to-noise ratio, we observe gains in terms of the perceptual evaluation of speech quality (PESQ) metric for the speech quality. We accompany the paper by the complete simulation and processing chain written in Python. The code and the sound samples are available online at http://lcav.github.io/AcousticRake-Receiver/.
关键词： echo sorting,noise suppression,interference cancellation,room impulse response,beamforming,Acoustic rake receiver,perceptual evaluation of speech quality (PESQ)
更新于2025-09-19 17:13:59
-
Study on Three-Phase Reclosing Strategy Applicable to Tie Line of Photovoltaic Power Station
摘要： When a fault occurring in the tie line of photovoltaic power station is cleared by the protection three-phase trip, photovoltaic power source (PVS) will form an unplanned island with the local load. However, since the voltage regulation and frequency control capability of PVS is generally poor, it is very difficult to satisfy the synchronous reclosing conditions, eventually resulting in an automatic reclosing failure. According to the islanding control strategy of PVS and the principle of phase-locked loop (PLL), a vector relationship model of PVS port actual voltage, port calculation voltage, grid-connected point voltage and so on before and after reclosing is established. Based on this, the influences of reclosing phase difference, amplitude difference and frequency difference on reclosing impulse voltage and current are analyzed, and a synchronous check reclosing strategy applicable to the tie line of PVS is proposed, which can effectively improve the success rate of the three-phase reclosing in tie line. Digital simulation results verify the correctness of the proposed reclosing strategy.
关键词： reclosing impulse,three-phase reclosing,Photovoltaic power,synchronous check reclosing strategy,analysis of influencing factors
更新于2025-09-16 10:30:52
-
[IEEE 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Shenzhen, China (2019.11.25-2019.11.27)] 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - High color rendering index white LEDs fabricated using InP/ZnS green-emitting quantum dots and InP/ZnSe/ZnS red-emitting quantum dots
摘要： This paper presents a 3-D statistical channel impulse response (IR) model for urban line of sight (LOS) and non-LOS channels developed from 28- and 73-GHz ultrawideband propagation measurements in New York City, useful in the design of 5G wireless systems that will operate in both the ultra-high frequency/microwave and millimeter-wave (mmWave) spectrum to increase channel capacities. A 3GPP-like stochastic IR channel model is developed from measured power delay profiles, angle of departure, and angle of arrival power spectra. The extracted statistics are used to implement a channel model and simulator capable of generating 3-D mmWave temporal and spatial channel parameters for arbitrary mmWave carrier frequency, signal bandwidth, and antenna beamwidth. The model presented here faithfully reproduces realistic IRs of measured urban channels, supporting air interface design of mmWave transceivers, filters, and multi-element antenna arrays.
关键词： 5G,28 GHz,3-D ray-tracing,multipath,time cluster (TC),spatial lobe (SL),millimeter-wave (mmWave) propagation,statistical simulator,spatial channel model (SCM),time cluster spatial lobe (TCSL),Channel model,impulse response (IR),73 GHz
更新于2025-09-16 10:30:52
-
Electrical synapses interconnecting axons revealed in the optic nerve head – a novel model of gap junctions’ involvement in optic nerve function
摘要： Purpose: To characterize newly discovered electrical synapses, formed by connexin (Cx) 36 and 45, between neighbouring axons within the optic nerve head. Methods: Twenty-?ve Wistar rats were killed by CO2 inhalation. Proximal and distal optic nerve (ON) stumps were collected and processed for immunostainings, electron microscopy (EM) with immunogold labelling, PCR and Western blots (WB). Additional 15 animals were deeply anaesthetized, and ?ash visual evoked potentials (fVEP) after retrobulbar injection of saline (negative control) or 100 lM meclofenamic acid solution (gap junctions’ blocker) were recorded. Human para?n cross-sections of eyeballs for immunostainings were obtained from the Human Eye Biobank for Research. Results: Immunostainings of both rat and human ON revealed the presence of Cx45 and 36 colocalizing with b3-tubulin, but not with glial ?brillary acidic protein (GFAP). In WB, Cx36 content in optic nerve was approximately halved when compared with retina (0.58 (cid:1) 0.005 in proximal stump and 0.44 (cid:1) 0.02 in distal stump), Cx45 showed higher levels (0.68 (cid:1) 0.01 in proximal stump and 0.9 (cid:1) 0.07 in distal stump). In immunogold-EM of optic nerve sections, we found electric synapses (formed mostly by Cx45) directly coupling neighbouring axons. In fVEP, blocking of gap junctions with meclofenamic acid resulted in signi?cant prolongation of the latency of P1 wave up to 160% after 30 min (p < 0.001). Conclusions: Optic nerve (ON) axons are equipped with electrical synapses composed of neuronal connexins, especially Cx45, creating direct morphological and functional connections between each other. This ?nding could have substantial implications for understanding of the pathogenesis of various optic neuropathies and identi?es a new potential target for a therapeutic approach.
关键词： electrical synapses,optic nerve,retinal ganglion cell axons,impulse conduction,conduction resistance
更新于2025-09-11 14:15:04
-
[Institution of Engineering and Technology 11th International Conference on Wireless Communications, Networking and Mobile Computing (WiCOM 2015) - Shanghai, China (21-23 Sept. 2015)] 11th International Conference on Wireless Communications, Networking and Mobile Computing (WiCOM 2015) - An improved image denoising method based on the pulse coupled neural network
摘要： In this paper, we proposed an image denoising filtering method based on PCNN (pulse coupled neural network) for images polluted by the pulse noise. The method firstly determined the position of pixels polluted by noise ac- cording to the fire capture features of PCNN. Then, a sim- ilar median filtering step was applied in the processing of noised pixels. Finally, the iterations and the sizes of filter window were chosen according to the noise intensity, which realized the adaptive-filtering of images. The main result stated that, compared to mean filtering, median fil- tering and adapted-median filtering, the method we pro- posed was not only effective in denoising and keeping details of images, but also showing good performances in different SNR conditions.
关键词： Image Denoising,PCNN,Neural Network,Impulse Noise
更新于2025-09-11 14:15:04
-
An IR-UWB Angle-of-Arrival Sensor IC Using Auto-Toggled Time-to-Digital Converter
摘要： This letter introduces an impulse radio-ultrawideband (IR-UWB) angle-of-arrival (AoA) sensor integrated circuit (IC) using an auto-toggled time-to-digital converter (TDC). The detectable range of the proposed AoA sensor can be extended by a factor of 2 by utilizing an auto-toggle operation that toggles the TDC’s input signal according to the target’s position. The analog front end (AFE) of the receivers is designed with a 3–5 GHz band and the system comprises two AFEs and one digital back end (DBE). The proposed IR-UWB AoA sensor IC was fabricated using a 65-nm CMOS process. The measurable angular range was ± 40?, and an angle error of ± 1.5? was measured.
关键词： impulse radio-ultrawideband (IR-UWB),time-to-digital converter (TDC) with auto-toggle,Angle-of-arrival (AoA)
更新于2025-09-11 14:15:04