- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Real-time signal processing of photoplethysmographic signals to estimate the on-demand and continuous heart rate by spectral analysis
摘要： In healthcare applications, heart rate is one of the vital signs which give the health informatics of a person. Nowadays, the evolution of PPG sensors help to develop low cost heart rate monitoring devices with minimal hardware resources compared to ECG. In this paper, an efficient algorithm is proposed to find the heart rate using frequency spectrum analysis on PPG signals. Using the proposed algorithm, the heart rate is calculated with a pass percentage of 99.2, mean absolute percentage error (MAPE) of 1.59%, mean absolute error (MAE) of 1.20 BPM and reference closeness factor (RCF) of 0.989. The first reliable heart rate output comes in 6.5th second, which is the minimum possible time. The algorithm operates with a speed of 2 MIPS and with a memory of 18 KB. So the proposed method can be integrated to any low cost real-time embedded platforms to accurately measure the heart rate.
关键词： PPG,fast Fourier transform,heart rate,smoothing,frequency domain,FFT,photoplethysmography,decimation
更新于2025-09-23 15:23:52
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Singular spectrum analysis filtering and Fourier inversion: an efficient and fast way to improve resolution and quality of current density maps with low-cost Hall scanning systems
摘要： We provide a Biot–Savart inversion scheme that, for any two-dimensional, or bulk with planar crystallization, high-temperature superconducting (HTS) sample, determines current density maps with a higher resolution and accuracy than previous procedures and at a fraction of its computational cost. The starting point of our scheme is a Hall scanning microscopy map of the out-of-plane component of the magnetic field generated by the current. Such maps are noisy in scans of real samples with commercial-grade equipment, and their error is the limiting factor in any Biot–Savart inversion scheme. The main innovation of our proposed scheme is a singular spectrum analysis (SSA) filtering of the Hall probe maps, which cancels measurement errors such as noise or drifts without introducing any artifacts in the field map. The SSA filtering of the Hall probe data is so successful in this task that the resulting magnetic field map does not require an overdetermined QR inversion, allowing Fourier inversion of the Biot–Savart problem. Our implementation of SSA filtering of the Hall scan measurements, followed by Biot–Savart inversion using the fast Fourier transform (FFT), is applied to both simulations and real samples of HTS tape stacks. The algorithm works in cases where ill conditioning ruled out the application of Fourier inversion, and achieves a finer resolution for a fraction of the cost of the QR inversion used to date. The computation passes physical and statistical validity tests in all cases, and in three-dimensional samples it is shown to yield the average, with a depth-dependent weight, of the current density circulating in the different layers of the sample.
关键词： Hall magnetometry,SSA filtering,fast Fourier transform,high-temperature superconducting tapes,Biot–Savart inversion
更新于2025-09-23 15:23:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Highly Squinted Imaging for Diving SAR with 3-Dacceleration
摘要： A uniform linear motion is generally assumed in traditional synthetic aperture radar(SAR) processing algorithms. However, it is inevitable that if there is 3-D acceleration, the image formulation processing complexity will be significantly increased, especially in highly squinted situations. This paper aims to handle the imaging problems in the highly squinted SAR with three-dimensional acceleration, which utilizes the Taylor formula to expand the distance equation and further resolve it. Based on the formulated range formula, we further utilize the two-dimensional non-uniform Fast Fourier Transform (2D-NUFFT) to obtain focused SAR imagery. The proposed methods are verified with simulation results.
关键词： 2D-NUFFT algorithm,highly squinted,synthetic aperture radar (SAR),nonuniform fast Fourier transform (NUFFT),3-D acceleration model
更新于2025-09-23 15:22:29
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Hyperspectral Face Recognition with Patch-Based Low Rank Tensor Decomposition and PFFT Algorithm
摘要： Hyperspectral imaging technology with sufficiently discriminative spectral and spatial information brings new opportunities for robust facial image recognition. However, hyperspectral imaging poses several challenges including a low signal-to-noise ratio (SNR), intra-person misalignment of wavelength bands, and a high data dimensionality. Many studies have proven that both global and local facial features play an important role in face recognition. This research proposed a novel local features extraction algorithm for hyperspectral facial images using local patch based low-rank tensor decomposition that also preserves the neighborhood relationship and spectral dimension information. Additionally, global contour features were extracted using the polar discrete fast Fourier transform (PFFT) algorithm, which addresses many challenges relevant to human face recognition such as illumination, expression, asymmetrical (orientation), and aging changes. Furthermore, an ensemble classifier was developed by combining the obtained local and global features. The proposed method was evaluated by using the Poly-U Database and was compared with other existing hyperspectral face recognition algorithms. The illustrative numerical results demonstrate that the proposed algorithm is competitive with the best CRC_RLS and PLS methods.
关键词： spectral and spatial information,polar discrete fast Fourier transform,band fusion,ensemble classifier,global and local features,tensor decomposition,hyperspectral images
更新于2025-09-23 15:22:29
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FPGA Implementation of Underwater Image Enhancement using Nonlinear Filtering
摘要： Background/Motivation: Statistical Analysis: they suffer from various adversary underwater conditions and require low power devices such as FPGA. Methods/ Optical image captured by autonomous underwater vehicles need to be preprocessed as Underwater image degradation due to non uniform illumination is corrected by non linear filtering and is implemented in FPGA. Two dimensional Fast Fourier Transform (FFT) and its inverse along with logarithmic computation were implemented in FPGA as a part of filter implementation. One dimensional row wise and column wise FPGA’s can be used for implementing FFT were computed first and then combined to form two dimensional FFT. architectures that require high level parallelism such as image processing algorithms due to its inherent parallelism. Frequency based filtering method which is employed for preprocessing an underwater image successfully provided good histogram compared to the original one. Device utilization for implementing structure was estimated. Novel method of FFT implementation, its inverse and logarithmic computation was used in this work. The method can be applied to digital signal processing applications that can be implemented in FPGA. Automation of image preprocessing is required in unmanned underwater vehicles used for cable detection, navigation etc. These vehicles are to be provided with low power devices such as FPGAs for long run in underwater applications.
关键词： Nonlinear Filtering,Fast Fourier Transform,FPGA,Automated Underwater Vehicles,Underwater Image Enhancement
更新于2025-09-23 15:21:01
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[IEEE TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON) - Kochi, India (2019.10.17-2019.10.20)] TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON) - Low-Frequency Effectiveness of Differential Detection for Electro-optic Sensor System
摘要： This paper describes the effectiveness of differential detection for reducing laser noise in the low-frequency region in an electro-optic (EO) sensor system. Improvement in the signal-to-noise ratio (SNR) is necessary for expanding the applications of EO sensor systems. In a previous work, an alternating current coupling was used at an optical receiver to eliminate a direct current (DC) signal. As a result, the low-frequency effectiveness of the differential detection could not be estimated. Therefore, in this study, we modified a photodiode bias circuit for DC coupling measurement.
关键词： phasor diagram,differential detection,fast Fourier transform,signal-to-ratio,electro-optic sensor
更新于2025-09-23 15:19:57
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Grain Boundary Induced Ultralow Threshold Random Laser in a Single GaTe Flake
摘要： Random lasing is a lasing phenomenon realized in random media, and has attracted a great deal of attention in recent years. An essential requirement for strong random lasing is to achieve strong and recurrent scattering among grain boundaries of a disordered structure. Herein, we report a random laser (RL) based on individual polycrystalline GaTe microflakes (MFs) with a lasing threshold of 4.15 kW cm-2, about 1-2 orders of magnitude lower than that of the reported single GaN microwire random laser. The strongly enhanced light scattering and trapping benefit from the reduced grain size in the polycrystalline GaTe MF, resulting in a ultralow threshold. We also investigate the dependence of spatially localized cavities’ dimension on the pumping intensity profile and temperature. The findings provide a feasible route to realize RL with low threshold and small size, opening up a new avenue in fulfilling many potential optoelectronic applications of RL.
关键词： fast Fourier-transform,random laser,GaTe,ultralow-threshold,grain-boundary
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE Sustainable Power and Energy Conference (iSPEC) - Beijing, China (2019.11.21-2019.11.23)] 2019 IEEE Sustainable Power and Energy Conference (iSPEC) - Analysis on Load Characteristics of Distributed Photovoltaic Access to EVs industry
摘要： In this communication, the computation of the perturbation-based electric field integral equation of the form Rn?1, n = 0, 1, 2, . . . , is accelerated by using fast Fourier transform (FFT) technique. As an effective solution of the low-frequency problem, the perturbation method employs the Taylor expansion of the scalar Green’s function in free space. However, multiple impedance matrices have to be solved frequency orders, and the computational cost becomes at different extremely high, especially for large-scale problems. Since the perturbed kernels still satisfy Toeplitz property on the uniform Cartesian grid, incorporated the FFT based on Lagrange interpolation can be well to accelerate the multiple matrix vector products. Because of the nonsingularity property of high-order kernels when n ≥ 1, we do not need to do any near field amendment. Finally, the efficiency of the proposed method is validated in an iterative solver with numerical examples.
关键词： perturbation method,integral equation (IE),Fast Fourier transform (FFT),low frequency
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 3rd Advanced Information Management, Communicates, Electronic and Automation Control Conference (IMCEC) - Chongqing, China (2019.10.11-2019.10.13)] 2019 IEEE 3rd Advanced Information Management, Communicates, Electronic and Automation Control Conference (IMCEC) - Research on Control algorithm of Photovoltaic Grid-connected Inverter Based on Fuzzy Logic
摘要： In this communication, the computation of the perturbation-based electric field integral equation of the form Rn?1, n = 0, 1, 2, . . . , is accelerated by using fast Fourier transform (FFT) technique. As an effective solution of the low-frequency problem, the perturbation method employs the Taylor expansion of the scalar Green’s function in free space. However, multiple impedance matrices have to be solved frequency orders, and the computational cost becomes at different extremely high, especially for large-scale problems. Since the perturbed kernels still satisfy Toeplitz property on the uniform Cartesian grid, incorporated the FFT based on Lagrange interpolation can be well to accelerate the multiple matrix vector products. Because of the nonsingularity property of high-order kernels when n ≥ 1, we do not need to do any near field amendment. Finally, the efficiency of the proposed method is validated in an iterative solver with numerical examples.
关键词： integral equation (IE),perturbation method,Fast Fourier transform (FFT),low frequency
更新于2025-09-19 17:13:59
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[IEEE 2019 4th International Conference on Mechanical, Control and Computer Engineering (ICMCCE) - Hohhot, China (2019.10.24-2019.10.26)] 2019 4th International Conference on Mechanical, Control and Computer Engineering (ICMCCE) - Evaluation of Distributed Photovoltaic Consumption Capacity of Distribution Network Based on Cuckoo Search Algorithm
摘要： In this communication, the computation of the perturbation-based electric field integral equation of the form Rn?1, n = 0, 1, 2, . . . , is accelerated by using fast Fourier transform (FFT) technique. As an effective solution of the low-frequency problem, the perturbation method employs the Taylor expansion of the scalar Green’s function in free space. However, multiple impedance matrices have to be solved frequency orders, and the computational cost becomes at different extremely high, especially for large-scale problems. Since the perturbed kernels still satisfy Toeplitz property on the uniform Cartesian grid, incorporated the FFT based on Lagrange interpolation can be well to accelerate the multiple matrix vector products. Because of the nonsingularity property of high-order kernels when n ≥ 1, we do not need to do any near field amendment. Finally, the efficiency of the proposed method is validated in an iterative solver with numerical examples.
关键词： perturbation method,integral equation (IE),Fast Fourier transform (FFT),low frequency
更新于2025-09-19 17:13:59